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Thermolysis of [Cp*Ru(PPh2(CH2)PPh2)BH2 (L2)] 1 (Cp*=η5-C5Me5; L=C7H4NS2), with terminal alkynes led to the formation of η4-σ,π-borataallyl complexes [Cp*Ru(μ-H)B{R-C=CH2}(L)2] (2 a-c) and η²-vinylborane complexes [Cp*Ru(R-C=CH2)BH(L)2] (3 a-c) (2 a, 3 a: R=Ph; 2 b, 3 b: R=COOCH3; 2 c, 3 c: R=p-CH3-C6H4; L=C7H4NS2) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a-c are linked by a unique η4-interaction. Conversions of 1 into 3 a-c proceed through the formation of intermediates 2 a-c. Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ-borane complex [Cp*RuCO(μ-H)BH2L] 4 (L=C7H4NS2) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η4-σ,π-borataallyl complexes [Cp*Ru(μ-H)BH{R-C=CH2}(L)] 5 and [Cp*Ru(μ-H)BH{HC=CH-R}(L)] 6 (R=COOCH3; L=C7H4NS2) by Markovnikov and anti-Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η4-σ,π-borataallyl complex [Cp*Ru(μ-H)BH{R-C=CH-R}(L)] 7 (R=COOCH3; L=C7H4NS2). An agostic interaction was also found to be present in 2 a-c and 5-7, which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, ¹H, 11B, 13C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b, 3 a-c and 5-7. DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds. [ABSTRACT FROM AUTHOR]

Reactivity of [Cp*Mo(CO) Me], 1 with various chalcogenide ligands such as Li[BH E] and Li[BH EFc] (E = S, Se or Te; Fc = (C H-Fe-C H)) has been described. Room temperature reaction of 1 with Li[BH E] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO) ( η-S CCH)], 2 and [Cp*Mo(CO) ( η-SeC H)], 3. In compound 2, {Cp*Mo(CO) } fragment adopts a four-legged piano-stool geometry with a η-dithioacetate moiety. In contrast, treatment of 1 with Li[BH (EFc)] (E = S, Se or Te; Fc = C H-Fe-C H) yielded borate complexes [Cp*Mo(CO) (μ-H)(μ-EFc)BH ], 4-6 in moderate yields. Compounds 4-6 are too unstable and gradual conversion to [{Cp*Mo(CO) } (μ-H)(μ-EFc] ( 7: E = S; 8: Se) and [{Cp*Mo(CO) } (μ-TeFc) ], 9 happened by subsequent release of BH . All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Reactions of both Cp* and borated-based κ 2- N,S -chelated Ru(II) complexes have been carried out with 1,4-diethynyl benzene that led to the formation of hydrotrisborate ruthenium species and alkyne inserted ruthenium alkenyl complexes. [Display omitted] The chemistry of κ2-N,S -chelated Ru(II) complexes, [Cp*RuPPh 3 (κ 2- N,S -(NC 7 H 4 S 2)] (Cp*=ƞ5-C 5 Me 5), 1a and [PPh 3 { κ2-N,S -(NS 2 C 7 H 4)}Ru{ κ3 -H,S,S-H 2 B(NC 7 H 4 S 2) 2 }], 1b has been explored with a terminal alkyne 1,4-diethynylbenzene. For example, the room-temperature reaction of Cp* based κ2 - N,S -chelated Ru(II) species 1a with 1,4-diethynyl-benzene yielded [RuCp*(κ 1- N,S -C 7 H 4 NS 2)C 7 H 4 NS 2 -(E)-N−C=CHC 8 H 5 ], 2. On the other hand, although treatment of 1b with 1,4-diethynylbenzene at room temperature showed no reactivity, thermolysis led to the formation of two borate complexes, [PPh 3 {C 7 H 4 NS 2 -(E)-N−C=CHC 8 H 5 }Ru{ κ 3-H,S,Sʹ-H 2 B(C 7 H 4 NS 2) 2 }], 3 and [PPh 3 (κ 2- N,S -C 7 H 4 NS 2) Ru{ κ 3-S,Sʹ,Sʹʹ-HB(C 7 H 4 NS 2) 3 }], 4 , albeit in poor yields. Both the Ru(II) species 2 and 3 contain a five-membered ruthenacycle with an exocyclic C=C moiety attached to carbon atom. In complex 4 , the ruthenium center is stabilized by hydrotrisborate, phosphine, and hemilabile one N,S -chelating ligand. The key feature of 4 is the coordination of the boron atom to the metal center through a common sulphur atom of the 2-mercaptobenzothiazole ligand. Characterization of these Ru(II) species has been carried out by various spectroscopic techniques and single-crystal X-ray diffraction analysis for 4. In addition, Density Functional Theory (DFT) calculations were further performed to provide insight into the bonding and electronic structures of these complexes. [ABSTRACT FROM AUTHOR]

A metal rich cluster made of Groups 8 and 9 metals was synthesized featuring a µ 5 -boride moiety. [Display omitted] • A new type of μ 5 -boride cluster [(IrCp*){Ru(CO) 2 }{Ru(CO) 3 } 3 (µ -H) 5 B 2 H 2 (μ 5 -B)] (1) is synthesised. • Cluster 1 is a unique boride derived from an eight-vertex closo -dodecadeltahedron by removal of one five-connected vertex followed by capping of a Ru(CO) 3 moiety. • Trimetallic and tetrametallic metallaboranes with a µ 3 -coordinated triply-bridged borylene moiety is also isolated. A series of metal-rich clusters of group 9 containing boride or borylene units have been isolated and structurally characterized. The thermolysis reaction of arachno- [IrCp*H 2 (B 3 H 7)] ( I ) with [Ru 3 (CO) 12 ] allowed to isolate the µ 5 -boride nido -[(IrCp*){Ru(CO) 2 }{Ru(CO) 3 } 3 (µ -H) 5 B 2 H 2 (μ 5 -B)] (1) and the tetrametallic cluster [(IrCp*) 2 {Ru(CO) 2 }{Ru(CO) 3 }(μ -CO) 2 (μ 3 -BH)] (2) with a µ 3 -coordinated triply-bridged borylene moiety. The geometry of cluster 1 can be derived from an eight-vertex closo -dodecadeltahedron by removal of one five-connected vertex followed by capping of a Ru(CO) 3 moiety. The borylene moiety (BH) of cluster 2 is connected in a μ 3 -fashion to the deltahedral face of a tetrametallic tetrahedron (Ir 2 Ru 2). To synthesize the Mn analogue of 2 , thermolysis reaction with [Mn 2 (CO) 10 ] was carried out, that afforded the trimetallic tetrahedral borylene [(IrCp*) 2 {MnH (CO) 3 }(μ -CO) 2 (μ 3 -BH)] (3) along with the known face-fused boride [{Ir(CO) 2 } 3 (IrCp*) 3 (μ 3 -CO)(μ -CO)(μ 5 -BH)] (4). Clusters 2 and 3 are the first triply-bridged borylenes having an Ir metal atom in the core. All these clusters were characterized by NMR (1H, 11B and 13C), infrared (IR) spectroscopies and mass spectrometry. The structure of cluster 1 was confirmed by X-ray diffraction analysis. In addition, density functional theory (DFT) calculations were conducted to interpret and study the nature of bonding and electronic structure of cluster 1. [ABSTRACT FROM AUTHOR]

Trinuclear complexes of group 6, 8, and 9 transition metals with a (μ3-BH) ligand [(μ3-BH)(Cp*Rh)2(μ-CO)M′(CO)5], 3 and 4 ( 3: M′=Mo; 4: M′=W) and 5- 8, [(Cp*Ru)3(μ3-CO)2(μ3-BH)(μ3-E)(μ-H){M′(CO)3}] ( 5: M′=Cr, E=CO; 6: M′=Mo, E=CO; 7: M′=Mo, E=BH; 8: M′=W, E=CO), have been synthesized from the reaction between nido-[(Cp*M)2B3H7] ( nido- 1: M=Rh; nido- 2: M=RuH, Cp*=η5-C5Me5) and [M′(CO)5 ⋅thf] (M′=Mo and W). Compounds 3 and 4 are isoelectronic and isostructural with [(μ3-BH)(Cp*Co)2(μ-CO)M′(CO)5], (M′=Cr, Mo and W) and [(μ3-BH)(Cp*Co)2(μ-CO)(μ-H)2M′′H(CO)3], (M′′=Mn and Re). All compounds are composed of a bridging borylene ligand (B−H) that is effectively stabilized by a trinuclear framework. In contrast, the reaction of nido- 1 with [Cr(CO)5 ⋅thf] gave [(Cp*Rh)2Cr(CO)3(μ-CO)(μ3-BH)(B2H4)] ( 9). The geometry of 9 can be viewed as a condensed polyhedron composed of [Rh2Cr(μ3-BH)] and [Rh2CrB2], a tetrahedral and a square pyramidal geometry, respectively. The bonding of 9 can be considered by using the polyhedral fusion formalism of Mingos. All compounds have been characterized by using different spectroscopic studies and the molecular structures were determined by using single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Thermolysis of [Cp*Ru(PPh2(CH2)PPh2)BH2(L2)] 1 (Cp*=η5-C5Me5; L=C7H4NS2), with terminal alkynes led to the formation of η4-σ,π-borataallyl complexes [Cp*Ru(μ-H)B{R-C=CH2}(L)2] ( 2 a- c) and η2-vinylborane complexes [Cp*Ru(R-C=CH2)BH(L)2] ( 3 a- c) ( 2 a, 3 a: R=Ph; 2 b, 3 b: R=COOCH3; 2 c, 3 c: R= p-CH3-C6H4; L=C7H4NS2) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a- c are linked by a unique η4-interaction. Conversions of 1 into 3 a- c proceed through the formation of intermediates 2 a- c. Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ-borane complex [Cp*RuCO(μ-H)BH2L] 4 (L=C7H4NS2) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η4-σ,π-borataallyl complexes [Cp*Ru(μ-H)BH{R-C=CH2}(L)] 5 and [Cp*Ru(μ-H)BH{HC=CH-R}(L)] 6 (R=COOCH3; L=C7H4NS2) by Markovnikov and anti-Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η4-σ,π-borataallyl complex [Cp*Ru(μ-H)BH{R-C=CH-R}(L)] 7 (R=COOCH3; L=C7H4NS2). An agostic interaction was also found to be present in 2 a- c and 5- 7, which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, 1H, 11B, 13C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b, 3 a- c and 5- 7. DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds. [ABSTRACT FROM AUTHOR]

Chloro-rhodaboratrane [(Cp*Rh)(L 2 )BCl] 4 has been synthesized from rhodium N,S-heterocyclic carbene complex [(Cp*Rh)(L 2 )(1-benzothiazol-2-ylidene)], 1 , (L = C 7 H 4 NS 2 ) and borane reagent BHCl 2 .SMe 2 . The Rh B bond in 4 is buttressed between two benzothiazolyl units in [3.3.0] fashion. The presence of B Cl bond allowed us to explore the chemistry of boratrane 4 at the boron centre. The reaction of ethynylmagnesium bromide with 4 yielded η 1 -vinyl complex [Cp*RhBr(C 2 H 2 )L] 5 , containing a five membered metallaheterocycle. In an objective to abstract the chloride, alike borylene synthesis from haloboryl, we performed the reaction of 4 with NaBAr F 4 that resulted the thiolato bridged bimetallic compound [Cp*Rh(μ-L) 3 RhCp*][BAr F 4 ] 6 (Ar F : C 6 H 3 (CF 3 ) 2 -3,5). [ABSTRACT FROM AUTHOR]

A series of novel isocloso-diiridaboranes [(Cp*Ir)2B6H6], 1, 2; [1,7-(Cp*Ir)2B8H8], 4; [1,4-(Cp*Ir)2B8H8], 5; [(Cp*Ir)2B9H9], 8; isonido-[(Cp*Ir)2B7H7], 3; and 10-vertex cluster [5,7-(Cp*Ir)2B8H12], 6 (Cp* = η5-C5Me5) have been isolated and structurally characterized from the pyrolysis of [Cp*IrCl2]2 and BH3·thf. On the other hand, the corresponding rhodium system afforded 10- and 11-vertices clusters [5-(Cp*Rh)B9H13)], 7, and [(Cp*Rh)2B9H9], 9, respectively. Clusters 1 and 2 are topological isomers. The geometry of 1 is dodecahedral, similar to that of its parent borane [B8H8]2-, in which two of the [BH] vertices are replaced by two [Cp*Ir] fragments. The geometry of 2 can be derived from a nine-vertex tricapped trigonal prism by removing one of the capped vertices. Compounds 4 and 5 are 10-vertex isocloso clusters based on a 10-vertex bicapped square antiprism structure. The only difference between them is the presence of a metal-metal bond in 5. The solid-state structures of 8 and 9 attain an 11-vertex geometry in which a unique six-membered B6H6 moiety is bonded to the metal center. In addition, quantum-chemical calculations have been used to provide further insight into the electronic structure and stability of the clusters. All the compounds have been characterized by IR and ¹H, 11B, and 13C NMR spectroscopy in solution, and the solid-state structures were established by X-ray crystallographic analysis. [ABSTRACT FROM AUTHOR]

Based on benzo[e]indolium and dimesitylborylbenzaldehyde a new ratiometric fluorescent chemodosimeter, C41H43BIN (3) has been synthesized and characterized by 1H, 13C NMR spectroscopy, mass spectrometry and single crystal X-ray crystallography. Probe 3 was found to be highly selective and sensitive toward cyanide (CN−) ions in aqueous medium even in the presence of other competing anions like F−, Cl−, Br−, I−, H2PO4−, HCO3− and AcO−. The detection limit was calculated to be 7.1 × 10−9 M, which is much lower than the maximum permissable concentration in drinking water (1.9 μM) set by the World Health Organization (WHO). In addition, the response time of the probe for CN− is less than 5 seconds. The mechanism is based on a nucleophilic addition reaction of cyanide ions at the polarized [＞C=N＜]+ bond of the benzoindolium group thereby blocking the pi-conjugation between the benzoindolium and triarylborane moiety. This was further confirmed by 1H NMR titration, ESI-MS studies and DFT calculations. [ABSTRACT FROM AUTHOR]

In an effort to synthesize supraicosahedral iridaboranes, pyrolysis of [Cp*IrCl2]2 with excess [BH3·THF] was carried out, and this synthesis afforded the isomeric iridaborane [(Cp*Ir)2B6H6] clusters 1 and 2. The geometry of 1 was determined to be dodecahedral, i.e., similar to that of [B8H8]2−, whereas 2 was found to exhibit a cluster shape that can be derived from a nine-vertex tricapped trigonal prism by removing one of the capped vertices. The calculation of a large HOMO–LUMO gap further rationalized the isocloso structures for these isomers. [ABSTRACT FROM AUTHOR]

In a quest for effective synthetic precursors for the preparation of B-agostic complexes of ruthenium, we have shown that the reaction of [Cp*RuCl 2 ] 2 (Cp* = η5-C 5 Me 5 ) with [NaBt] or [NaBo] (Bt = dihydrobis(2-mercaptobenzthiazolyl)borate; Bo = dihydrobis(2-mercaptobenzoxazolyl)borate) led to the formation of B-agostic complexes [Cp*RuBH 2 L 2 ], 1a,b ( 1a : L = 2-mercaptobenzthiazol, 1b : L = 2-mercaptobenzoxazol) and [Cp*RuBH 3 L], 2a,b ( 2a : L = 2-mercaptobenzthiazol, 2b : L = 2-mercaptobenzoxazol) in good yields. In parallel to the formation of 1a,b and 2a,b , this method also allowed the formation of ruthenium hydrotrisborate complexes [Cp*RuBYL 3 ], 3a–c ( 3a : L = 2-mercaptobenzthiazol, Y = H; 3b : L = 2-mercaptobenzoxazol, Y = H; 3c : L = 2-mercaptobenzoxazol, Y = Cl). The key feature of complexes 3a–c is the coordination of one of the 2-mercaptobenzothiazole ligand that connects to the metal and the boron centre through a common sulfur atom. Upon heating, compounds 3a,b change into their corresponding S→N linkage isomers, in which the boron atom is bonded to three nitrogen atoms. The cyclic voltammetric studies on compounds 3a–c and 4a,b suggest that a deviation in coordination of the ligand change the oxidation potential of the metal centre. All the new compounds have been characterized in solution by 1 H, 11 B and 13 C NMR spectroscopy, mass spectrometry and the structural types of 3a–c and 4b were unequivocally established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

Building upon our earlier work on low-boron containing molybdaborane arachno -[Cp*Mo(CO) 2 B 3 H 8 ], 1 we continue to investigate the reactivity of the same system with group 8 metal carbonyl compounds. As a result, thermolysis of arachno - 1 in presence of [Ru 3 (CO) 12 ] led to the formation of neutral heterometallic ketenylidene cluster [Cp*Mo(CO) 2 ( μ -H)Ru 2 (CO) 6 ( μ 3 - ɳ 1 -CCO)], 2 , in which the triply bridged ketenylidene fragment (CCO) is lying perpendicular to the plane of the metal triangle (Ru–Mo–Ru). In addition to the formation of cluster 2 , the reaction also yielded a semi-interstitial boride cluster [Cp*Mo(CO) 2 {Ru(CO) 3 } 4 B], 3 and a known bimetallic cluster [Cp*Mo(CO) 3 ] 2 , 4 in moderate yields. The geometry of 3 can be described as a square pyramidal, in which the boron atom caps the square face formed by three Ru and one Mo atoms respectively. All the new compounds have been characterized by multinuclear NMR spectroscopy, IR spectroscopy and mass spectrometry. In addition to these, the solid state structure of 2 and 3 were unequivocally established by single crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A series of agostic σ-borane/borate complexes have been synthesized and structurally characterized from simple borane adducts. A room-temperature reaction of [Cp*Mo(CO)3Me], 1 with Li[BH3(EPh)] (Cp*=pentamethylcyclopentadienyl, E=S, Se, Te) yielded hydroborate complexes [Cp*Mo(CO)2(μ-H)BH2EPh] in good yields. With 2-mercapto-benzothiazole, an N,S-carbene-anchored σ-borate complex [Cp*Mo(CO)2BH3(1-benzothiazol-2-ylidene)] ( 5) was isolated. Further, a transmetalation of the B-agostic ruthenium complex [Cp*Ru(μ-H)BHL2] ( 6, L=C7H4NS2) with [Mn2(CO)10] affords a new B-agostic complex, [Mn(CO)3(μ-H)BHL2] ( 7) with the same structural motif in which the central metal is replaced by an isolobal and isoelectronic [Mn(CO)3] unit. Natural-bond-orbital analyses of 5-7 indicate significant delocalization of the electron density from the filled σBH orbital to the vacant metal orbital. [ABSTRACT FROM AUTHOR]

A combined experimental and quantum-chemical study of a series of homometallic metallaheteroboranes [(Cp*M)2-E6B2H2] (M = Rh or RuH; E = S or Se; Cp* = η5-C5Me5), which are analogues of 1,3-bishomocubane, is reported. The thermolysis of nido-[(Cp*Rh)2B3H7] (1) in the presence of S or Se powder in toluene yielded bishomocubane clusters [(Cp*Rh)2-(μ-E)2(μ3-E)4B2H2], (3: E = S; 4: E = Se). In a similar fashion, the treatment of nido-[(Cp*RuH)2B3H7] (2) with S or Se powder in p-xylene yielded [(Cp*Ru)2(μ-E)2(μ3-E)4B2H2] (5: E = S; 6: E = Se) and [(Cp*Ru)2(μ3-Se)(μ4-Se)B3H5] (7). One of the noteworthy features of 3-6 is the presence of an electronprecise trichalcogenoborato ligand. All of the compounds have been characterized by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy. The structures of 3, 4, 6, and 7 were established unequivocally by Xray crystallographic analysis. Quantum-chemical calculations by DFT methods for 3, 4, and 6 showed reasonable agreement with the experimentally observed structural parameters. The large HOMO-LUMO gaps are consistent with the high stabilities of these complexes. [ABSTRACT FROM AUTHOR]

A combined experimental and quantum-chemical study of a series of homometallic metallaheteroboranes [(Cp*M)2E6B2H2] (M = Rh or RuH; E = S or Se; Cp* = η5-C5Me5), which are analogues of 1,3-bishomocubane, is reported. The thermolysis of nido-[(Cp*Rh)2B3H7] ( 1) in the presence of S or Se powder in toluene yielded bishomocubane clusters [(Cp*Rh)2(μ-E)2(μ3-E)4B2H2], ( 3: E = S; 4: E = Se). In a similar fashion, the treatment of nido-[(Cp*RuH)2B3H7] ( 2) with S or Se powder in p-xylene yielded [(Cp*Ru)2(μ-E)2(μ3-E)4B2H2] ( 5: E = S; 6: E = Se) and [(Cp*Ru)2(μ3-Se)(μ4-Se)B3H5] ( 7). One of the noteworthy features of 3- 6 is the presence of an electron-precise trichalcogenoborato ligand. All of the compounds have been characterized by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy. The structures of 3, 4, 6, and 7 were established unequivocally by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods for 3, 4, and 6 showed reasonable agreement with the experimentally observed structural parameters. The large HOMO-LUMO gaps are consistent with the high stabilities of these complexes. [ABSTRACT FROM AUTHOR]

In an attempt to synthesize a zero valent germanium compound, we have carried out the reaction of [(Cp*RuCO)(GeCl2)]2, 1 with potassium metal that led to the formation of a metallagermoxane [(Cp*Ru(CO)2Ge)4(μ-O)6], 2. Compound 2 is the first example of a tetrametallagermoxane with an exo-{Cp*Ru(CO)2} fragment. DFT calculations were used to examine the key intermediates associated with the formation of 2. [ABSTRACT FROM AUTHOR]

A high-yielding synthetic route for the preparation of group 9 metallaboratrane complexes [Cp*MBH(L)2], 1 and 2 ( 1, M=Rh, 2, M=Ir; L=C7H4NS2) has been developed using [{Cp*MCl2}2] as precursor. This method also permitted the synthesis of an Rh-N,S-heterocyclic carbene complex, [(Cp*Rh)(L2)(1-benzothiazol-2-ylidene)] ( 3; L=C7H4NS2) in good yield. The reaction of compound 3 with neutral borane reagents led to the isolation of a novel borataallyl complex [Cp*Rh(L)2B{CH2C(CO2Me)}] ( 4; L=C7H4NS2). Compound 4 features a rare η3-interaction between rhodium and the B-C-C unit of a vinylborane moiety. Furthermore, with the objective of generating metallaboratranes of other early and late transition metals through a transmetallation approach, reactions of rhoda- and irida-boratrane complexes with metal carbonyl compounds were carried out. Although the objective of isolating such complexes was not achieved, several interesting mixed-metal complexes [{Cp*Rh}{Re(CO)3}(C7H4NS2)3] ( 5), [Cp*Rh{Fe2(CO)6}(μ-CO)S] ( 6), and [Cp*RhBH(L)2W(CO)5] ( 7; L=C7H4NS2) have been isolated. All of the new compounds have been characterized in solution by mass spectrometry, IR spectroscopy, and 1H, 11B, and 13C NMR spectroscopies, and the structural types of 4- 7 have been unequivocally established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

This work describes the synthesis, structural characterizations, and electronic structures of a series of novel homometallic cubane clusters [(Cp*Ru)2{Ru(CO)2}2BH(μ3-E)(μ-H)B(μ-H)3M], (2, M = Cp*Ru, E = CO; 3, M = Ru(Cp*Ru)2(μ-CO)3(μ-H)BH), E = BH), [(Cp*Ru)3(μ3-CO)(BH)3(μ3-H)3], 4, and [(Cp*Ru)2(μ3-CO){Ru(CO)3}2(BH)2(μ-H)B], 5 (Cp* = η5-C5Me5). These cubane clusters have been isolated from a thermally driven reaction of diruthenium analogue of pentaborane(9) [(Cp*RuH)2B3H7], 1, and [Ru3(CO)12]. Structural and spectroscopic studies revealed the existence of triply bridged hydrogen (μ3-H) atoms that participate as a vertex in the cubane core formation for compounds 2, 3, and 4. In addition, the crystal structure of these clusters clearly confirms the presence of an electron precise borane ligand (borylene fragment) which is triply bridged to the trimetallic units. Bonding of these novel complexes has been studied computationally by DFT methods, and the studies demonstrate that the cubane clusters 2 and 3 possess 60 cluster valence electrons (cves) with six metal-metal bonds. All the new compounds have been characterized in solution by mass spectrometry; IR; and ¹H, 11B, and 13C NMR studies, and the structural types were unequivocally established by crystallographic analysis of compounds 2-5. [ABSTRACT FROM AUTHOR]

Room temperature photolysis of [Cp*Mo(CO) 3 Me], 1 with excess of [BH 3 ·THF] led to the isolation of hydrogen-rich arachno -[Cp*Mo(CO) 2 B 3 H 8 ], 2 in good yield. The geometry of arachno - 2 consists of a butterfly core similar to that of 7 skeletal electron pairs tetraborane(10). Further, the metal fragment addition reaction of arachno - 2 with [Fe 2 (CO) 9 ] yielded a nido -[Cp*Mo(CO) 2 B 3 H 6 Fe(CO) 3 ], 3 that plays a pivotal role in bringing a change in the geometry from arachno - 2 to nido - 3 . The reaction of arachno - 2 with [Ru 3 (CO) 12 ], however, yielded known metal carbonyl compound [Cp*Mo(CO) 3 ] 2 , 4 . All the new compounds have been characterized in solution by mass spectrometry, IR, 1 H, 11 B, 13 C NMR spectroscopy and the solid state X-ray structures of 2 and 3 were unequivocally established by X-ray diffraction analysis. Additionally, we have studied the bonding nature of compounds 2 and 3 with the help of density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Reaction of [(η5-C5Me5)CoCl]2 with a two-fold excess of [LiBH4·thf] followed by heating with an excess of Se powder produces the dicobaltaselenaborane species [{(η5-C5Me5)Co}2B2H2Se2], 1, in good yield. The geometry of 1 resembles a nido pentagonal [Co2B2Se2] bipyramid with a missing equatorial vertex. It can alternatively be seen as an open cage triple-decker cluster. Isolation of 1 permits its reaction with [Fe2(CO)9] to give heterometallic diselenametallaborane [{(η5-C5Me5)Co}Fe(CO)3B2H2Se2], 2. The geometry of 2 is similar to that of 1 with one of the [(η5-C5Me5)Co] groups replaced by the isolobal, two-electron fragment [Fe(CO)3]. Both new compounds have been characterized by mass spectrometry, and by 1H, 11B and 13C NMR spectroscopy. The structural architectures have been unequivocally established by crystallographic analysis. In addition, density functional theory calculations were performed to investigate the bonding and electronic properties. The large HOMO–LUMO gaps computed for both clusters are consistent with their thermodynamic stability. Natural bond order calculations predict the absence of metal–metal bonding interaction. [ABSTRACT FROM AUTHOR]

Building upon previous studies on the synthesis of bis(sigma)borate and agostic complexes of ruthenium, the chemistry of nido-[(Cp*Ru)2B3H9] ( 1) with other ligand systems was explored. In this regard, mild thermolysis of nido- 1 with 2-mercaptobenzothiazole (2-mbzt), 2-mercaptobenzoxazole (2-mbzo) and 2-mercaptobenzimidazole (2-mbzi) ligands were performed which led to the isolation of bis(sigma)borate complexes [Cp*RuBH3L] ( 2 a- c) and β-agostic complexes [Cp*RuBH2L2] ( 3 a- c; 2 a, 3 a: L=C7H4NS2; 2 b, 3 b: L=C7H4NSO; 2 c, 3 c: L=C7H5N2S). Further, the chemistry of these novel complexes towards various diphosphine ligands was investigated. Room temperature treatment of 3 a with [PPh2(CH2) nPPh2] ( n=1-3) yielded [Cp*Ru(PPh2(CH2) nPPh2)-BH2(L2)] ( 4 a- c; 4 a: n=1; 4 b: n=2; 4 c: n=3; L=C7H4NS2). Mild thermolysis of 2 a with [PPh2(CH2) nPPh2] ( n=1-3) led to the isolation of [Cp*Ru(PPh2(CH2) nPPh2)(L)] (L=C7H4NS2 5 a- c; 5 a: n=1; 5 b: n=2; 5 c: n=3). Treatment of 4 a with terminal alkynes causes a hydroboration reaction to generate vinylborane complexes [Cp*Ru(RCCH2)BH(L2)] ( 6 and 7; 6: R=Ph; 7: R=COOCH3; L=C7H4NS2). Complexes 6 and 7 can also be viewed as η-alkene complexes of ruthenium that feature a dative bond to the ruthenium centre from the vinylinic double bond. In addition, DFT computations were performed to shed light on the bonding and electronic structures of the new compounds. [ABSTRACT FROM AUTHOR]

Building upon our earlier results on the chemistry of diruthenium analogue of pentaborane (9) with heterocumulenes, we continued to investigate the reactivity of arachno-[(Cp*Ru)2(B3H8)(CS2H)], 1, (Cp* = η5-C5Me5) towards group 7 and 8 transition metal carbonyl compounds under photolytic and thermolytic conditions. The metal carbonyl compounds show diverse reactivity pattern with arachno-1. For example, the photolysis of arachno-1 with [Re2(CO)10] yielded [(Cp*Ru)2B3H5(CH2S2){Re(CO)4}2], 2, [(Cp*RuCO)2(μ-H)2(CH2S2){Re(CO)4}{Re(CO)3}], 3 and [(Cp*Ru)2(μ-CO)(μ-H)(CH2S2){Re(CO)3}], 4. The geometry of 2 with a nearly planar eight-membered ring containing heavier transition metals rhenium, ruthenium is unprecedented. Compounds 3 and 4 can be considered as M4-quadrilateral and M3-triangle with a methylenedithiolato ligand attached to the metal centres, respectively. [Mn2(CO)10], on the other hand, reacts with arachno-1 to yield heterometallic binuclear [(Cp*RuCO){Mn(CO)4}(μ-H)(SCH3)], 5 and homocubane [(Cp*Ru)2{Mn(CO)3}-(CS2H2)B3H4], 6. In an attempt to generate group 8 analogues of 2–5, we performed the reaction of arachno-1 with [Fe2(CO)9] and [Ru3(CO)12]. Although, the objective of isolating analogous compounds was not achieved, the reaction with [Fe2(CO)9] led to novel tetrahedral cluster [(Cp*RuCO){(Fe(CO)3}2S(μ-H)], 7. [Ru3(CO)12], in contrast, yielded known compounds [{Cp*Ru(CO)}2B2H6], 9 and [Cp*Ru(CO)2]2, 10. All the cluster compounds have been characterized by mass spectrometry, IR, and 1H, 11B, and 13C NMR spectroscopy, and the geometric structures were unequivocally established by crystallographic analysis of 2–5 and 7. [ABSTRACT FROM AUTHOR]

Correction for ‘Chemistry of group 9 dimetallaborane analogues of octaborane(12)’ by Subrat Kumar Barik, et al., Dalton Trans., 2015, 44, 669–676. [ABSTRACT FROM AUTHOR]

A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}2] (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with LiBH4 ⋅thf at −78 °C, followed by room-temperature reaction with three equivalents of [Mn2(CO)10] yielded a manganese hexahydridodiborate compound [{(OC)4Mn}(η6-B2H6){Mn(CO)3}2(μ-H)] ( 1) and a triply bridged borylene complex [(μ3-BH)(Cp*Co)2(μ-CO)(μ-H)2MnH(CO)3] ( 2). In a similar fashion, [Re2(CO)10] generated [(μ3-BH)(Cp*Co)2(μ-CO)(μ-H)2ReH(CO)3] ( 3) and [(μ3-BH)(Cp*Co)2(μ-CO)2(μ-H)Co(CO)3] ( 4) in modest yields. In contrast, [Ru3(CO)12] under similar reaction conditions yielded a heterometallic semi-interstitial boride cluster [(Cp*Co)(μ-H)3Ru3(CO)9B] ( 5). The solid-state X-ray structure of compound 1 shows a significantly shorter boron-boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using 1H, 11B, 13C NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant BHMn, a weak BBMn interaction, and an enhanced BB bonding in 1. [ABSTRACT FROM AUTHOR]

The first example of a homometallic neutral zirconaborane, [(Cp2Zr)2B5H11], 1, has been prepared through the thermolysis of [Cp2Zr(BH4)2], generated from the fast metathesis reaction of [Cp2ZrCl2] and LiBH4·thf with BH3·thf. The solid-state structure of 1 shows an open geometry with a planar B3 ring. The bonding between the Zr center and the central B3 ring was studied computationally by DFT methods, and based on the combined experimental and computational results compound 1 can be defined as a metal-stabilized arachno-B3H9. Further, in an attempt to synthesize a hybrid analogue of 1 by introducing two electron fragments into arachno-[(Cp2Zr)(Cp*Ir)B4H10], 2, we have performed the reaction of 2 with [Ru3(CO)12]. However, the reaction led to the formation of a hybrid metallaborane, [(Cp*Ir){Ru3(CO)8}B4H10], 3. [ABSTRACT FROM AUTHOR]

An unprecedented, 22-valence-electron triple-decker sandwich complex [(Cp*Mo)2{μ-η6:η6-B4H4Ru2(CO)6}], 2, has been prepared. In an effort to generate analogous triple-deckers with group 6 metal carbonyl fragments in the middle deck, we have isolated [(Cp*MoCO)2(μ-H)2B4H4], 3, that provides the first direct evidence for the missing link between [(Cp*MoCl)2B3H7] and [(Cp*Mo)2B5H9] clusters. [ABSTRACT FROM AUTHOR]

Building upon our earlier results on the synthesis of electron-precise transition-metal-boron complexes, we continue to investigate the reactivity of pentaborane(9) and tetraborane(10) analogues of ruthenium and rhodium towards thiazolyl and oxazolyl ligands. Thus, mild thermolysis of nido-[(Cp*RuH)2B3H7] ( 1) with 2-mercaptobenzothiazole (2-mbtz) and 2-mercaptobenzoxazole (2-mboz) led to the isolation of Cp*-based (Cp*=η5-C5Me5) borate complexes 5 a, b [Cp*RuBH3L] ( 5 a: L=C7H4NS2; 5 b: L=C7H4NOS)) and agostic complexes 7 a, b [Cp*RuBH2(L)2], ( 7 a: L=C7H4NS2; 7 b: L=C7H4NOS). In a similar fashion, a rhodium analogue of pentaborane(9), nido-[(Cp*Rh)2B3H7] ( 2) yielded rhodaboratrane [Cp*RhBH(L)2], 10 (L=C7H4NS2). Interestingly, when the reaction was performed with an excess of 2-mbtz, it led to the formation of the first structurally characterized N,S-heterocyclic rhodium-carbene complex [(Cp*Rh)(L2)(1-benzothiazol-2-ylidene)] ( 11) (L=C7H4NS2). Furthermore, to evaluate the scope of this new route, we extended this chemistry towards the diruthenium analogue of tetraborane(10), arachno-[(Cp*RuCO)2B2H6] ( 3), in which the metal center possesses different ancillary ligands. [ABSTRACT FROM AUTHOR]

Thermolysis of an in situ generated intermediate [(Cp*Ta)2(BH3)2Cl2], 1 generated from the reaction of [Cp*TaCl4], (Cp* = η5-C5Me5) and [LiBH4·thf], in presence of [Ru3(CO)12] yielded pileo-[Cp*TaCl(μ-Cl)-B2H4Ru3(CO)8], 2 having two electrons fewer than seven pairs required for the observed square pyramidal geometry. Cluster 2 is the first example of an unsaturated cluster comprising early and late transition metals in a square pyramid core. This reaction also yielded [(Cp*Ta)2(B2H6)(B2H4Cl2)], 3 as a by-product. In addition, the reaction of [Cp*MoCl4] (Cp* = η5-C5Me5) with [LiBH4.thf] in presence of excess [MeI] at mild condition led to the isolation of periodinated dimolybdatetraborane [(Cp*Mo)2B4H3I5], 4 that hints a possible existence of [(Cp*Mo)2B4H8]. After the isolation of periodinated 4, we extended this chemistry towards the late transition metallaborane [(Cp*Rh)3B4H4], 5 using [PtBr2] as brominating source. Although all the attempts to isolate perbrominated rhodaborane failed, we have isolated partially brominated rhodaborane clusters [(Cp*Rh)3(BH)-(BBr)3], 6 and [(Cp*Rh)3(BH)3(BBr)], 7. All the compounds were characterized by IR and 1H, 11B and 13C NMR spectroscopy in solution, and the solid-state structures of 2, 4 and 6 were established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

The reaction of metal carbonyl compounds with group 6 and 8 metallaboranes led us to report the synthesis and structural characterization of several novel mixed-metal chalcogenide tetrahedral clusters. Thermolysis of arachno-[(Cp*RuCO)2B2H6], 1, and [Os3(CO)12] in the presence of 2-methylthiophene yielded [Cp*Ru(CO)2(μ-H){Os3(CO)9}S], 3, and [Cp*Ru(μ-H){Os3(CO)11}], 4. In a similar fashion, the reaction of [(Cp*Mo)2B5H9], 2, with [Ru3(CO)12] and 2-methylthiophene yielded [Cp*Ru(CO)2(μ-H){Ru3(CO)9}S], 5, and conjuncto-[(Cp*Mo)2B5H8(μ-H){Ru3(CO)9}S], 6. Both compounds 3 and 5 can be described as 50-cve (cluster valence electron) mixed-metal chalcogenide clusters, in which a sulfur atom replaces one of the vertices of the tetrahedral core. Compounds 3 and 5 possess a [M3S] tetrahedral core, in which the sulfur is attached to an exo-metal fragment, unique in the [M3S] metal chalcogenide tetrahedral arrangements. All the compounds have been characterized by mass spectrometry, IR, and 1H, 11B and 13C NMR spectroscopy in solution, and the solid state structures were unequivocally established by crystallographic analysis of compounds 3, 5 and 6. [ABSTRACT FROM AUTHOR]

Reactions of the CS2 and CO2 heterocumulene ligands with nido-ruthenaborane cluster [1,2-(Cp*Ru)2(μ-H)2B3H7], 1, were explored (Cp* = pentamethylcyclopentadienyl). Compound 1 when treated with CS2 underwent metal-assisted hydroboration to yield arachno-ruthenaborane [(Cp*Ru)2(B3H8)(CS2H)], 2, with a dithioformato ligand attached to it. The chemistry of 2 was then explored with various transition metal carbonyl compounds under photolytic and thermolytic conditions. Thermolysis of 2 with [Mn2(CO)10] resulted in the formation of an unprecedented cubane-type cluster [(Cp*Ru)2Mn(CO)3(CS2H2)B3H4], 3, with a rare [M3E5] formulation (E = B, S). On the other hand, when compound 2 was photolyzed in the presence of [Mn2(CO)10], it yielded an incomplete cubane-type cluster [(Cp*Ru)2Mn(CO)3BH2(CS2H2)], 4. The room-temperature reaction of 2 with [Fe2(CO)9] yielded heterometallic arachno clusters [(Cp*Ru)(CO)2{Fe(CO)3}2S2CH3], 6 and [(Cp*Ru)2(B3H8)(CO){Fe(CO)3}2(CS2H)], 7. In contrast, photolysis of 2 with [Fe2(CO)9] yielded a tetrahedral cluster [(Cp*Ru)(CO)2S(μ-H){Fe(CO)3}3], 8, tethered to an exo-polyhedral moiety [(Cp*Ru)(CO)2]. Compound 6 provides an unusual bonding pattern by means of fusing the wing-tip vertex (S) of the [Fe2S2] butterfly core by an exo-polyhedral [(Cp*Ru)(CO)2] unit. Density functional theory calculations were carried out to provide insight into the mechanistic pathway, electronic structure, and bonding properties. [ABSTRACT FROM AUTHOR]

Recently we described the synthesis and structural characterization of various dimetallaherteroborane clusters, namely nido-[(CpMo)BEClH], 1- 3; ( 1: E = S, x = 0; 2: E = Se, x = 0; 3: E = Te, x = 1). A combined theoretical and experimental study was also performed, which demonstrated that the clusters 1- 3 with their open face are excellent precursors for cluster growth reaction. In this investigation process on the reactivity of dimetallaheteroboranes with metal carbonyls, in addition to [(CpMo)BHEFe(CO)] ( 4: E = S, 6: E = Te) reported earlier, reaction of 2 with [ Fe(CO)] yielded mixed-metallaselenaborane [(CpMo)BHSeFe(CO)], 5 in good yield. The quantum chemical calculation using DFT method has been carried out to probe the bonding, NMR chemical shifts and electronic properties of dimolybdaheteroborane clusters 4- 6. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Cluster expansion reactions of cobaltaboranes were carried out using mono metal-carbonyls, metal halides and dichalcogenide ligands. Thermolysis of an in situ generated intermediate, obtained from the reaction of [Cp*CoCl]2 (Cp* = C5Me5) and [LiBH4·thf ], with three equivalents of [Mo(CO)3(CH3CN)3] followed by the reaction with methyl iodide yielded isocloso-[(Cp*Co)3B6H7Co(CO)2] (1) and closo-[(Cp*Co)2B2H5Mo2(CO)6I] (2). Cluster 1 is ascribed to the isocloso structure based on a 10-vertex bicapped square antiprism geometry. In a similar manner, the reaction of [Cp*CoCl]2 with [LiBH4·thf ] and the dichalcogenide ligand RS-SR (R = 1-OH-2,6-(tBu)2-C6H2) yielded nido cluster [(Cp*Co)2B2H2S2] (3). In parallel with the formation of the compounds 1-3, these reactions also yielded known cobaltaboranes [(Cp*Co)2B4H6] (4) and [(Cp*Co)3B4H4] in good yields. After the isolation of compound 4 in good yield, we verified its reactivity with PtBr2, which yielded closo-[(Cp*Co)2B4H2Br4] (5). To the best of our knowledge this is the second perhalogenated metallaborane cluster which has been recognized. All the new compounds were characterized by elemental analysis, IR, ¹H, 11B, and 13C NMR spectroscopy, and the geometric structures were unequivocally established by the X-ray diffraction analysis of compounds 1, 2, 3 and 5. Geometries obtained from the electronic structure calculations employing density functional theory (DFT) are in close agreement with the solid state X-ray structures. In addition, we analyzed the variation in the stability of the model compounds 1' (1': Cp analogue of 1, Cp = C5H5), [(CpCo)4B6H6] (1a) and [(CpRh)4B6H6] (1b). [ABSTRACT FROM AUTHOR]

We have synthesized and structurally characterized two new borate complexes of early transition metals utilizing chalcogen based borate ligand Li[BH 3 (SPh)]. [Display omitted] • Two unique chalcogen stabilized borate complexes of Ta were isolated. • Complex 1 has two unique borate ligands, i.e., {BH 3 (SPh)} and {BH 3 (S)}. • Compound 2 has another unique borate ligand {BH 3 (C 6 H 4)S} and triborane analog. • The DFT calculations revealed the σ-donation of B-H bonds of borates to Ta atoms. In an attempt to isolate some electron precise early transition metal borate complexes, we have explored the reactions of [Cp*TaCl 4 ] (Cp* = η 5-C 5 Me 5) with chalcogen-based borate ligand Li[BH 3 (SPh)]. The room-temperature reaction yielded bimetallic borate complex [(Cp*Ta) 2 (μ -SPh){S(BH 3)}{SPh(BH 3)}] (1) that present two types of borate ligands, i.e., {BH 3 (SPh)} and {BH 3 (S)} ligands having unique coordination with the tantalum atoms. Interestingly, the {BH 3 (S)} ligand is coordinated to both the Ta centers in µ-η1:η2 fashion. On the other hand, thermolysis of [Cp*TaCl 4 ] in the presence of Li[BH 3 (SPh)] yielded a bimetallic borate species [(Cp*Ta) 2 (µ - η 3: η 3-B 2 H 4 S){ µ - η 2: η 2-S(C 6 H 4)BH 3 }] (2). Compound 2 contains a triborane analog and a borate ligand, which are coordinated to two Ta atoms. This can also be considered as a notable example of C H activated molecule, in which a B-C bond formation took place. Both the borate species have been characterized by mass spectrometry, IR spectroscopy, NMR spectroscopy, and single-crystal X-ray diffraction studies. The density functional theory (DFT) calculations further provided insights into the bonding and electronic structures of these bimetallic borate species. [ABSTRACT FROM AUTHOR]

Theregioselective 1,3-dipolar cycloaddition reaction of alkoxyalkynyl Fischer carbene complex 1with azidomethyl ferrocene 2and with azidomethyl pyrene 4under solvent-freeconditions yielded the triazolyl Fischer carbene complexes 3(C27H21O6N3FeW) and 5(C33H21O6N3W),respectively. The cation complexation properties of these receptorshave been systematically studied using electrochemical and spectroscopictechniques. The exceptional structural feature existing in these receptorsis the presence of a Fischer carbene moiety, connected to the ferroceneor pyrene moiety through a 1,2,3-triazole ring. Receptor 3contains a redox-active ferrocene moiety and is highly selectivetoward Pb2+ion, whereas receptor 5, havinga fluorescent pyrene unit, selectively recognizes Zn2+andCu2+ions. The binding ability of receptor 3can be inferred either from the redox shift (the anodic shift ΔE1/2= 55 mV) or the highly visual output responsefor Pb2+ion. Receptor 5displays considerablechelation-enhanced fluorescence (CHEF) upon binding with Zn2+and Cu2+ions in an aqueous environment. Further, theproposed binding modes of these receptors and their metal cation complexationproperties have been supported by 1H NMR titration andMALDI-MS and a DFT study. [ABSTRACT FROM AUTHOR]

The photolysis of [M2(CO)10] (M=Re or Mn) with BH3⋅thf at room temperature yields arachno -1 and 2, [(CO)8M2B2H6] ( 1: M =Re, 2: M =Mn). Both the compounds show a butterfly structure with seven skeletal electron pairs and 42 valence electrons. This result presents a new method for general access to low-boron-content metal-boron compounds without the cyclopentadienyl ligand at the metal centers. This new synthetic route is superior to the existing procedures because it avoids the use of [LiBH4] and metal polychlorides, for which the synthesis is very tedious. Compound 1 catalyzes the cyclotrimerization of a series of internal and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivity of 1 with alkynes demonstrates for the first time that the introduction of the [B2H6] moiety into the [Re2(CO)10] framework significantly enhances the catalytic activity. Note that [Re2(CO)10] catalyzes the same set of alkynes under harsh conditions over a prolonged period of time. Quantum-chemical calculations using DFT methods are applied to afford further insight into the electronic structure, stability, and bonding of 1 and 2. All the compounds are characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometry of 1 is established unambiguously through crystallographic analysis. [ABSTRACT FROM AUTHOR]

A series of novel Cp*-based (Cp*=η5-C5Me5) agostic, bis(σ-borate), and boratrane complexes have been synthesized from diruthenium and dirhodium analogues of pentaborane(9). The synthesis and structural characterization of the first neutral ruthenadiborane(6) analogue are also reported. This new route offers a very efficient method for the isolation of bis(σ-borate) and agostic complexes from diruthenapentaborane(9). [ABSTRACT FROM AUTHOR]

A series of novel Cp*-based (Cp*=η5-C5Me5) agostic, bis(σ-borate), and boratrane complexes have been synthesized from diruthenium and dirhodium analogues of pentaborane(9). The synthesis and structural characterization of the first neutral ruthenadiborane(6) analogue are also reported. This new route offers a very efficient method for the isolation of bis(σ-borate) and agostic complexes from diruthenapentaborane(9). [ABSTRACT FROM AUTHOR]

Abstract: Reaction of [Cp∗MoCl4] (Cp∗ = η5-C5Me5) with excess of [LiBH4·thf] followed by pyrolysis with NaI yielded B–I inserted [(Cp∗Mo)2B5H9−n I n ], 1–3 (1: n = 1; 2: n = 2; 3: n = 3). In parallel to the formation of 1–3, the reaction also produced known [(Cp∗Mo)2B5H9] and [(Cp∗Mo)2(μ-I)4] in good yields. Under the similar reaction conditions, dimolybdathiaborane [(Cp∗Mo)2B4H4S2] yielded iodine substituted dimolybdathiaboranes, [(Cp∗Mo)2B4S2H4−n I n ], 4 and 5 (4: n = 2; 5: n = 3) in good yields. All the new compounds have been characterized in solution by IR, 1H and 11B NMR as simple substituted derivatives of [(Cp∗Mo)2B5H9] and [(Cp∗Mo)2B4H4S2]. The solid state structures were established unambiguously by crystallographic analysis of compounds 1–5. [Copyright &y& Elsevier]

Reaction of [Cp∗CoCl]2 (Cp∗ = η5-C5Me5) with [LiBH4·THF] in toluene at −70 °C, followed by thermolysis with 2-mercaptobenzothiazole (C7H5NS2) in boiling toluene led to the isolation of a range of cobaltaborane clusters, [(Cp∗Co)2B7H6OMe], 1; [(Cp∗Co)3B8H7R], 2a, b (2a: R = H; 2b: R = Me); [(Cp∗Co)3B8H8S], 3 and [(Cp∗Co)2B4H4RR′], 4a–d (4a: R, R′ = H; 4b: R = Me, R′ = H; 4c: R = H, R′ = Me and 4d: R, R′ = Me). In parallel to the formation of compounds 1–4, the reaction also yielded known [(Cp∗Co)3B4H4] in good yield. Compound 1 may be considered as 9-vertex hypoelectronic cluster with C1 symmetry, where cobalt atoms occupy the degree 5 vertices. All the dicobaltaboranes 4a–d contains two μ3-H protons and found to be very reactive. As a result, one of them (4a) when reacted with Fe2(CO)9 and sulfur powder yielded, almost immediately, [(Cp∗Co)2B4H5SFe3(CO)9], 5 and [(Cp∗Co)2B3H3(μ-CO)Fe(CO)3], 6. All the new compounds have been characterized in solution by mass, 1H, 11B, 13C NMR spectroscopy and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 1–6. Density functional theory (DFT) calculations on the model compounds 1′ and 2′ (1′, and 2′ are the Cp analog of 1, and 2a respectively, Cp = C5H5) yield geometries in agreement with the structure determinations. The existence of large HOMO–LUMO gap of these molecules rationalizes the isocloso description for 2a. Bonding patterns in the structure have been analyzed on the grounds of DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of group 5 metal polychlorides such as [Cp n MCl4−x ] (M = Nb: n = 1, x = 0; M = V: n, x = 2), (Cp = η5−C5H5) with [LiBH4·THF] followed by thermolysis in presence of diphenyl dichalcogenide ligands, E2Ph2 (E = Se or Te) yielded dimetallaheteroborane clusters [(CpNb)2BH(Se)4], 1 and [(CpV)2B3H9(μ3-Te)], 2 in modest yields. Compound 1 can be considered as an edge fused cluster in which a trigonal bipyramidal unit [Nb2Se2B] has been fused with a tetrahedral core [Nb2Se2] by means of a common [Nb2] edge. Compound 2 can be described as a dimetallaheteroborane built from two edge-fused V2B2 tetrahedra, in which one of the BH3 units is replaced by an isoelectronic Te ligand. All the compounds have been characterized by mass spectrometry, 1H, 11B, 13C, 51V and 77Se NMR spectroscopy. In addition the geometry of compound 1 has been established by crystallographic analysis. [Copyright &y& Elsevier]

The synthesis, structural characterization, and reactivity of new bridged borylene complexes are reported. The reaction of [{Cp*CoCl}2] with LiBH4 ⋅THF at −70 °C, followed by treatment with [M(CO)3(MeCN)3] (M=W, Mo, and Cr) under mild conditions, yielded heteronuclear triply bridged borylene complexes, [(μ3-BH)(Cp*Co)2(μ-CO)M(CO)5] ( 1- 3; 1: M=W, 2: M=Mo, 3: M=Cr). During the syntheses of complexes 1- 3, capped-octahedral cluster [(Cp*Co)2(μ-H)(BH)4{Co(CO)2}] ( 4) was also isolated in good yield. Complexes 1- 3 are isoelectronic and isostructural to [(μ3-BH)(Cp*RuCO)2(μ-CO){Fe(CO)3}] ( 5) and [(μ3-BH)(Cp*RuCO)2(μ-H)(μ-CO){Mn(CO)3}] ( 6), with a trigonal-pyramidal geometry in which the μ3-BH ligand occupies the apical vertex. To test the reactivity of these borylene complexes towards bis-phosphine ligands, the room-temperature photolysis of complexes 1- 3, 5, 6, and [{(μ3-BH)(Cp*Ru)Fe(CO)3}2(μ-CO)] ( 7) was carried out. Most of these complexes led to decomposition, although photolysis of complex 7 with [Ph2P(CH2) nPPh2] ( n=1-3) yielded complexes 9- 11, [3,4-(Ph2P(CH2) nPPh2)- closo-1,2,3,4-Ru2Fe2(BH)2] ( 9: n=1, 10: n=2, 11: n=3). Quantum-chemical calculations by using DFT methods were carried out on compounds 1- 3 and 9- 11 and showed reasonable agreement with the experimentally obtained structural parameters, that is, large HOMO-LUMO gaps, in accordance with the high stabilities of these complexes, and NMR chemical shifts that accurately reflected the experimentally observed resonances. All of the new compounds were characterized in solution by using mass spectrometry, IR spectroscopy, and 1H, 13C, and 11B NMR spectroscopy and their structural types were unequivocally established by crystallographic analysis of complexes 1, 2, 4, 9, and 10. [ABSTRACT FROM AUTHOR]

Room temperature photolysis of [(Cp*RuCO)2BH4(Bcat)], 3, generated from the reaction of arachno-[(Cp*RuCO)2B2H6], 1, with HBcat (cat = 1,2-O2C6H4), yielded a rare homodinuclear bridged-boryl complex, [(Cp*Ru)2(μ-H)(μ-CO)(μ-Bcat)], 4, confirmed by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Metal assisted borane condensationmethod has been employed forthe preparation of novel metallaborane cluster containing group 4metal. Pyrolysis of [Cp*IrB3H9], 1, with in situ generated zirconium bisborohydrate [Cp2Zr(BH4)2], produced from the fast metathesisreaction of [Cp2ZrCl2] and LiBH4,and excess of BH3·THF yielded arachno-[(Cp2Zr)(Cp*Ir)B4H10], 2, in 56% yield. Compound 2constitutes the first crystallographicstructure determination of hexaborane(12) metal analogue containingzirconium. The observed geometry of 2can be generatedfrom a dodecahedron by removing two vertices and an edge. Anticipatinga straight metal fragment substitution/addition reaction, mild thermolysisof 2with [Fe2(CO)9] was carriedout. However, the reaction led to the formation of known trimetallic[Cp*IrFe2(CO)9] cluster via cluster degradation.In addition, density functional theory (DFT) calculations have beencarried out for 2and other hypothetical early–latecombinations of hexaborane(12) metal analogues to reveal the electronicstructures. [ABSTRACT FROM AUTHOR]

We have synthesized and structurally characterized several dimetallaheteroborane clusters, namely, nido-[(Cp*Mo)2B4SH6], 1; nido-[(Cp*Mo)2B4SeH6], 2; nido-[(Cp*Mo)2B4TeClH5], 3; [(Cp*Mo)2B5SeH7], 4; [(Cp*Mo)2B6SeH8], 5; and [(CpW)2B5Te2H5], 6 (Cp* = η5-C5Me5, Cp = η5-C5H5). In parallel to the formation of 1-6, known [(CpM)2B5H9], [(Cp*M)2B5H9], (M = Mo, W) and nido-[(Cp*M)2B4E2H4] compounds (when M = Mo; E = S, Se, Te; M = W, E = S) were isolated as major products. Cluster 6 is the first example of tungstaborane containing a heavier chalcogen (Te) atom. A combined theoretical and experimental study shows that clusters 1-3 with their open face are excellent precursors for cluster growth reactions. As a result, the reaction of 1 and 2 with [Co2(CO)8] yielded clusters [(Cp*Mo)2B4H4E(μ3-CO)Co2(CO)4], 7-8 (7: E = S, 8: E = Se) and [(Cp*Mo)2B3H3E(μ-CO)3Co2(CO)3], 9-10 (9: E = S, 10: E = Se). In contrast, compound 3 under the similar reaction conditions yielded a novel 24-valence electron triple-decker sandwich complex, [(Cp*Mo)2{μ-η6:η6-B3H3TeCo2(CO)5}], 11. Cluster 11 represents an unprecedented metal sandwich cluster in which the middle deck is composed of B, Co, and Te. All the new compounds have been characterized by elemental analysis, IR, 1H, 11B, 13C NMR spectroscopy, and the geometric structures were unequivocally established by X-ray diffraction analysis of 1, 2, 4--7, and 9--11. Furthermore, geometries obtained from the electronic structure calculations employing density functional theory (DFT) are in close agreement with the solid state structure determinations. We have analyzed the discrepancy in reactivity of the chalcogenato metallaborane clusters in comparison to their parent metallaboranes with the help of a density functional theory (DFT) study. [ABSTRACT FROM AUTHOR]

Treatment of [Cp*TaCl SB 4 sb ] with chalcogen-ligated monoborate nucleophiles, [BH SB 3 sb (EPh)] SP - sp (E = S or Se) yielded various smaller borane analogues. Cover Feature: Metal Coordinated Tri- and Tetraborane Analogues (Eur. J. Inorg. Keywords: Boranes; Chalcogens; Metallaheteroboranes; Tantalum; Structure elucidation EN Boranes Chalcogens Metallaheteroboranes Tantalum Structure elucidation 4407 4407 1 11/24/21 20211122 NES 211122 B The Cover Feature b shows triborane and tetraborane analogues which are stabilized in the coordination sphere of tantalum atom(s). [Extracted from the article]

• We have synthesized a triple-decker complex of molybdenum with a planar middle-deck [(Cp*Mo) 2 { µ - η 6: η 6-B 4 H 4 Co 2 (CO) 5 }(H) 2 ], 1. Compound 1 is a rare example of 24-valence-electron (ve) triple-decker sandwich complex having bridging hydrogen atoms. • Further, we have synthesized an octahedral cluster of tungsten, [{Cp*W(CO) 2 } 2 (µ -H) 2 B 3 H 3 Co 2 (CO) 4 ] 2 , along with the formation of the bimetallic cluster [(Cp*W) 2 B 3 H 3 (µ -H) 2 Co 2 (CO) 4 (µ -CO) 2 ] 3. The cage geometry of compound 2 is based on an octahedron with one additional vertex capping a trigonal face. [Display omitted] Recent isolation and structural characterization of a planar triple-decker metallaborane complex of tungsten prompted us to synthesize its molybdenum analogue. Therefore, we have explored the thermolysis reaction of the intermediates obtained from the low-temperature reaction of [Cp*MoCl 4 ] (Cp* = η 5-C 5 Me 5) and LiBH 4 with Co 2 (CO) 8. The reaction indeed produced the analogous triple-decker complex of molybdenum with a planar middle-deck [(Cp*Mo) 2 { µ - η 6: η 6-B 4 H 4 Co 2 (CO) 5 }(H) 2 ], 1 , along with the formation of the reported [(Cp*Mo) 2 B 5 H 9 ] metallaborane. In an effort to isolate multi-decker complexes with a different geometries, we have also further explored the thermolysis reaction of the intermediates obtained from the low-temperature reaction of [Cp*WCl 4 ] and LiBH 4 with Co 2 (CO) 8. The reaction afforded an octahedral cluster, [{Cp*W(CO) 2 } 2 (µ -H) 2 B 3 H 3 Co 2 (CO) 4 ], 2 , along with the formation of the bimetallic cluster [(Cp*W) 2 B 3 H 3 (µ -H) 2 Co 2 (CO) 4 (µ -CO) 2 ], 3. The cage geometry of compound 2 is based on an octahedron with one additional vertex capping a trigonal face. That of compound 3 is a bicapped trigonal-bipyramidal analogue to the parent compound [(Cp*W) 2 B 5 H 9 ]. While compound 1 has been characterized by various spectroscopic analyses, compounds 2 and 3 have been characterized by multiple spectroscopic and single-crystal X-ray diffraction analyses. Density-functional theory (DFT) calculations account for their stability and structural variation. [ABSTRACT FROM AUTHOR]

Examples of transition metal boryl complexes featuring different types of boryl ligand. [Display omitted] • A detailed overview on the recent advances in the field of transition metal boryl complexes has been provided. • Structure and bonding of transition metal boryl complexes and their reactivity have been discussed. • Various organic/organometallic reactions of these species reported by others and us have been summarized. Transition metal (TM) complexes of boron comprising two-center two-electron (2c–2e) bond/s are systematically developed over the decades. Among them, TM boryl complexes (i.e. L n M–BR 2) featuring tri-coordinated boron have been studied extensively because of their unique bonding pattern and diverse reactivity towards organic substrates. These TM boryl complexes were found to be the key intermediates in many catalytic cycles, for example, diboration, hydroboration and C–H borylation reactions. As a result, this field has drawn immense attention in the recent years to develop new molecules. Synthesis and structural characterization of various TM boryl complexes implicitly directed to the isolation of TM complexes containing hitherto unknown structural motif, which could not be isolated in pure main group chemistry. The present review gives a summary of the contemporary progresses for the synthesis and reactivity of various TM boryl complexes reported by others and us. This review offers a detailed discussion on the structure and bonding of the TM boryl complexes. In addition, some of the potential applications of these species in various organic transformations are discussed. [ABSTRACT FROM AUTHOR]

Syntheses and structural characterization of supraicosahedral rhodaborane clusters are reported. Reaction of [(Cp*RhCl2)2], (Cp* = η5-C5Me5) with [LiBH4·thf] followed by thermolysis with excess of [BH3·thf] afforded 16-vertex closo-[(Cp*Rh)3B12H12Rh{Cp*RhB4H9}], 1, 15-vertex [(Cp*Rh)2B13H13], 2, 12-vertex [(Cp*Rh)2B10Hn(OH)m], (3a: n = 12, m = 0; 3b: n = 9, m = 1; 3c: n = 8, m = 2) and 10-vertex [(Cp*Rh)3B7H7], 4, and [(Cp*Rh)4B6H6], 5. Cluster 1 is the unprecedented 16-vertex cluster, consists of a sixteen-vertex {Rh4B12} with an exo-polyhedral {RhB4} moiety. Cluster 2 is the first example of a carbon free 15-vertex supraicosahedral metallaborane, exhibits icosihexahedron geometry (26 triangular faces) with three degree-six vertices. Clusters 3a-c have 12-vertex isocloso geometry, different from that of icosahedral one. Clusters 4 and 5 are attributed to the 10-vertex isocloso geometry based on 10-vertex bicapped square antiprism structure. In addition, quantum-chemical calculations with DFT methods at the BP86 level of theory have been used to provide further insight into the electronic structure and stability of the optimized structures which are in satisfactory agreement with the structure determinations. All the compounds have been characterized by IR, 1H, 11B, 13C NMR spectroscopy in solution, and the solid state structures were established by crystallographic analysis of compounds 1-5. [ABSTRACT FROM AUTHOR]

Thermolysisof [(Cp*RuCO)2B2H6] (1; Cp* = η5-C5Me5) with [Ru3(CO)12] yielded the trimetallaborane[(Cp*RuCO)3(μ3-H)BH] (2)and a number of homometallic boride clusters: [Cp*RuCO{Ru(CO)3}4B] (3), [(Cp*Ru)2{Ru2(CO)8}BH] (4), and [(Cp*Ru)2{Ru4(CO)12}BH] (5). Compound 2is isoelectronic and isostructural with the triply bridgedborylene compounds [(μ3-BH)(Cp*RuCO)2(μ-CO){Fe(CO)3}] (6) and [(μ3-BH)(Cp*RuCO)2(μ-H)(μ-CO){Mn(CO)3}] (7), where the [μ3-BH] moiety occupies the apicalposition. To test if compound 2undergoes hydroborationreactions with alkynes, as observed with 6, we performedthe reaction of 2with the same set of alkynes underphotolytic conditions. However, neither 2nor 7undergoes hydroboration to yield a vinyl–borylene complex.On the other hand, thermolysis of 6with trimethylsilylethyleneyielded the novel diruthenacarborane [1,1,7,7,7-(CO)5-2,3-(Cp*)2-μ-2,3-(CO)-μ3-1,2,3-(CO)-5-(SiMe3)-pileo-1,7,2,3,4,5-Fe2Ru2C2BH] (8). The solid-state X-ray diffractionresults suggest that 8exhibits a pentagonal -bipyramidalgeometry with one additional CO capping one of its faces. Cluster 3is a boride cluster where boron is in the interstitial positionof a square-pyramidal geometry, whereas compound 4canbe described as a tetraruthenium boride in which the Ru4butterfly skeleton has an interstitial boron atom. Electronic structurecalculations of compound 2employing density functionaltheory (DFT) generate geometries in agreement with the structure determinations.The existence of a large HOMO–LUMO gap in 2isin agreement with its high stability. Bonding patterns in the structurehave been analyzed on the grounds of DFT calculations. Furthermore,the B3LYP-computed 11B and 1H chemical shiftsfor compound 2precisely follow the experimentally measuredvalues. All the compounds have been characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometriesof the structures were unambiguously established by crystallographicanalyses of 2–4and 8. [ABSTRACT FROM AUTHOR]

Abstract: Mild thermolysis of arachno-[(Cp*RuCO)2B2H6], 1 in presence of GeCl2·dioxane yielded di-μ-germylene complex [(Cp*Ru)2(μ-GeCl2)2(CO)2], 2 (Cp* = η5-C5Me5). The molecular structure of 2 exhibits a diruthenium unit bridged by a pair of μ-GeCl2 moieties. The Cp* and the terminal CO ligands are oriented in anti fashion with respect to Ru–Ru bond. In addition, the reaction of 2 with arachno-[CpFe(CO)B3H8] (Cp = η5-C5H5) transformed to germenocene, [Cp2Ge:], 3 via an unstable intermediate [CpFe(CO)B2H5GeCl2], I. The 11B NMR spectroscopy was used as a tool to establish a probable reaction pathway for the formation of germenocene 3. Cluster 2 has been characterized by IR and NMR spectroscopy, and the geometric structure was unequivocally established by crystallographic analysis. [Copyright &y& Elsevier]