Search

In an effort to establish B‐P coupling reactions without the use of phosphine‐borane dehydrocoupling agent, we have developed a new synthetic methodology employing group 8 metal σ‐borate complex [{κ3‐H,S,S′‐BH2L2}Ru{κ3‐H,H,S‐BH3L}] (L=NC5H4S), 1. Treatment of 1 with chlorodiphenyl phosphine (PPh2Cl) yielded 1,5‐P,S chelated Ru‐dihydridoborate species [PPh2H{κ3‐H,H,S‐BH(OH)L}Ru{κ2‐P,S‐(Ph2P)BH2L}], 2. The insertion of phosphine moiety (PPh2) by the cleavage of 3c–2e σ(Ru...H‐B) bonding interaction led to the formation of B‐P bond. The κ2‐P,S chelated six‐membered ring adopted a boat conformation in complex 2. The heterocycle is made of all different atoms, which is one of the rarest examples of heteroatomic ring systems. Theoretical outcomes demonstrated the electronic insight of B‐P coupling and stabilization through transition metal. In order to explore an alternate route of B‐P bond formation, we have further explored the reaction of 1 and Ru‐bis(dihydridoborate) complex, 5 with secondary phosphine oxide (SPO). Although, thermolysis of 1 with diphenylphosphine oxide yielded analogous σ‐borate complex 3, the similar reaction of 5 at room temperature led to the formation of novel phosphinous(III) acid incorporated Ru(σ‐borate)(dihydridoborate) complex, 6. In a similar fashion, the reaction of 5 with phosphite ligand generated Ru(σ‐borate)(dihydridoborate) complex, 7, which is analogous to 6. [ABSTRACT FROM AUTHOR]

Building upon our earlier results on the chemistry of nido‐1,2‐[(Cp*RuH)2B3H7] (Cp*=ɳ5‐C5Me5) (nido‐1) with different transition metal carbonyls, we continued to investigate the reactivity with group 7 metal carbonyls under photolytic condition. Photolysis of nido‐1 with [Mn2(CO)10] led to the isolation of a trimetallic [(Cp*Ru)2{Mn(CO)3}(μ‐H)(μ‐CO)3(μ3‐BH)] (2) cluster with a triply bridging borylene moiety. Cluster 2 is a rare example of a tetrahedral cluster having hydrido(hydroborylene) moiety. In an attempt to synthesize the Re analogue of 2, a similar reaction was carried out with [Re2(CO)10] that yielded the trimetallic [(Cp*Ru)2{Re(CO)3}(μ‐H)(μ‐CO)3(μ3‐BH)] (3) cluster having a triply bridging borylene unit. Along with 3, a trimetallic square pyramid cluster [(Cp*Ru)2{Re(CO)3}(μ‐H)2(μ‐CO)(μ3,ɳ2‐B2H5)] (4), and heterotrimetallic hydride clusters [{Cp*Ru(CO)2}‐{Re(CO)4}2(μ‐H)] (5) and [{Cp*Ru(CO)}{Re(CO)4}2(μ‐H)3] (6) were isolated. Cluster 4 is a unique example of a M2M′B2 cluster having diboron capped Ru2Re‐triangle. The hydride clusters 5 and 6 have triangular RuRe2 frameworks with one and three μ‐Hs respectively. All the clusters have been characterized by using mass spectrometry, 1H, 11B{1H}, 13C{1H} NMR and IR spectroscopies analyses and the structures of clusters 2–6 have been unambiguously established by XRD analyses. Furthermore, to understand the electronic, structural, and bonding features of the synthesized metal‐rich clusters, DFT calculations have been performed. [ABSTRACT FROM AUTHOR]

The trans‐mer‐[(κ2‐N,S‐NS2C7H4)PR3Ru{κ3‐H,S,S′‐H2B (NS2C7H4)2}], (trans‐mer‐1 a: R=Cy; trans‐mer‐1 b: R=Ph) complexes are kinetically controlled products that upon thermolysis led to the formation of cis‐mer‐[(κ2‐N,S‐NS2C7H4)PR3Ru{κ3‐H,S,S′‐H2B(NS2C7H4)2}], (cis‐mer‐2 a: R=Cy; cis‐mer‐2 b: R=Ph) and cis‐fac‐[(κ2‐N,S‐NS2C7H4)PR3Ru{κ3‐H,S,S′‐H2B(NS2C7H4)2}], (cis‐fac‐3 a: R=Cy; cis‐fac‐3 b: R=Ph) along with complex cis‐[(κ2‐N,S‐NS2C7H4)2Ru(PPh3)2], (cis‐4). One of the main intentions of this study was to examine the flexibility of the borate and hemilabile N,S‐chelating mercapto‐benzothiazole ligands in adapting different spatial arrangements around metal center. Multinuclear spectroscopic analyses have been done to characterize all new complexes and the structures were further confirmed by single‐crystal X‐ray diffraction analysis. Further, Density Functional Theory (DFT) calculations were performed to provide an insight into the bonding of the complexes. [ABSTRACT FROM AUTHOR]

In an effort to synthesize metallaheteroborane clusters of higher nuclearity, the reactivity of metallaheteroboranes, nido-[(Cp*M)2B6S2H4(CS3)] (Cp* = C5Me5) (1: M = Co; 2: M = Rh) with various metal carbonyls have been investigated. Photolysis of nido-1 and nido-2 with group 6 metal carbonyls, M'(CO)5.THF (M' = Mo or W) were performed that led to the formation of a series of adducts [(Cp*M)2B6S2H4(CS3){M'(CO)5}] (3: M = Co, M' = Mo; 4: M = Co, M' = W; 5: M = Rh, M' = Mo; 6: M = Rh, M' = W) instead of cluster expansion reactions. In these adducts, the S atom of C=S group of di(thioboralane)thione {B2CS3} moiety is coordinated to M'(CO)5 (M = Mo or W) in η1-fashion. On the other hand, thermolysis of nido-1 with Ru3(CO)12 yielded one fused metallaheteroborane cluster [{Ru(CO)3}3S{Ru(CO)}{Ru(CO)2}Co2B6SH4(CH2S2){Ru(CO)3}2S], 7. This 20-vertex-fused cluster is composed of two tetrahedral {Ru3S} and {Ru2B2}, a flat butterfly {Ru3S} and one octadecahedron {Co2RuB7S} core with one missing vertex, coordinated to {Ru2SCH2S2} through two boron and one ruthenium atom. On the other hand, the room temperature reaction of nido-2 with Co2(CO)8 produced one 19-vertex fused metallaheteroborane cluster [(Cp*Rh)2B6H4S4{Co(CO)}2{Co(CO)2}2(μ-CO)S{Co(CO)3}2], 8. Cluster 8 contains one nido-decaborane {Rh2B6S2}, one butterfly {Co2S2} and one bicapped square pyramidal {Co6S} unit that exhibits an intercluster fusion with two sulfur atoms in common. Clusters 3–6 have been characterized by multinuclear NMR and IR spectroscopy, mass spectrometry and structurally determined by XRD analyses. Furthermore, the DFT calculations have been carried out to gain insight into electronic, structural and bonding patterns of the synthesized clusters. [ABSTRACT FROM AUTHOR]

Treatment of [Cp*RuCl2]2, 1, [(COD)IrCl]2, 2 or [(p‐cymene)RuCl2]2,3 (Cp*=η5‐C5Me5, COD= 1,5‐cyclooctadiene and p‐cymene=η6‐iPrC6H4Me) with heterocyclic borate ligands [Na[(H3B)L], L1 and L2 (L1: L=amt, L2: L=mp; amt=2‐amino‐5‐mercapto‐1,3,4‐thiadiazole, mp=2‐mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L1 and L2 afforded dihydridoborate species [LAM(μ‐H)2BHL] 4–6 (4: LA=Cp*, M=Ru, L=amt; 5: LA=Cp*, M=Ru, L=mp; 6: LA=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L2 yielded cis‐ and trans‐bis(dihydridoborate) species, [Ru{(μ‐H)2BH(mp)}2], cis‐7 and trans‐7. The isolation and structural characterization of fac‐ and mer‐[Ru{(μ‐H)2BH(mp)}{(μ‐H)BH(mp)2}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis‐and trans‐7, they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti‐Markovnikov addition products, 10 a–d. [ABSTRACT FROM AUTHOR]

The synthesis, structure and electronic properties of tetraruthenium dichalcogenide complexes displaying the exclusive coordination mode of dichalcogenide ligands have been discussed. The reactions of Li[BH2E3] (E = S or Se) with [ClRu(μ-Cl)(p-cymene)]2 (p-cymene = η6-{p-C6H4(iPr)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru2Cl2(p-cymene)2}2(μ4,η2-E2)], 1–2 (E = S (1) and Se (2)). The solid-state X-ray structure of 1 shows that two {(p-cymene)RuCl}2 moieties are bridged by a S–S bond. In addition to 2, the reaction of Li[BH2Se3] with [ClRu(μ-Cl)(p-cymene)]2 also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se7(BH)3}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D3 symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(μ-Cl)Cl]2 with Li[BH2S3] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)2{μ-Sn(BH)2}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)2(μ,η2:η2-S2)(μ,η1:η1-S2)] and [(RuCp*)2(μ-SBHS-κ1B:κ2S:κ2S)(μ,η1:η1-S2)]. Complexes 1–5 have been characterized by multi-nuclear NMR, IR, UV-vis spectroscopy, and mass spectrometry and their molecular formulations (except 2) have been determined by single crystal X-ray crystallography. Furthermore, DFT calculations were performed that rationalize the stabilization of the dichalcogenide units (E22−) by the tetrametallic systems in 1–2. [ABSTRACT FROM AUTHOR]

Building upon previous work, the chemistry of [(η6‐p‐cymene)Ru{P(OMe)2OR}Cl2], (R=H or Me) has been extended with [H2B(mbz)2]− (mbz=2‐mercaptobenzothiazolyl) using different Ru precursors and borate ligands. As a result, a series of 1,3‐N,S‐chelated ruthenium borate complexes, for example, [(κ2‐N,S‐L)PR3Ru{κ3‐H,S,S'−H2B(L)2}], (2 a–d and 2 a'–d'; R=Ph, Cy, OMe or OPh and L=C5H4NS or C7H4NS2) and [Ru{κ3‐H,S,S'‐H2B(L)2}2], (3: L=C5H4NS, 3': L=C7H4NS2) were isolated upon treatment of [(η6‐p‐cymene)RuCl2PR3], 1 a–d (R=Ph, Cy, OMe or OPh) with [H2B(mp)2]− or [H2B(mbz)2]− ligands (mp=2‐mercaptopyridyl). All the Ru borate complexes, 2 a–d and 2 a'–d' are stabilized by phosphine/phosphite and hemilabile N,S‐chelating ligands. Treatment of these Ru borate species, 2 a'–c' with various terminal alkynes yielded two different types of five‐membered ruthenacycle species, namely [PR3{C7H4S2‐(E)‐N‐C=CH(R')}Ru{κ3‐H,S,S'−H2B(L)2}], (4–4'; R=Ph and R'=CO2Me or C6H4NO2; L=C7H4NS2) and [PR3{C7H4NS‐(E)‐S‐C=CH(R')}Ru{κ3‐H,S,S'−H2B(L)2}], (5–5', 6 and 7; R=Ph, Cy or OMe and R'=CO2Me or C6H4NO2; L=C7H4NS2). All these five‐membered ruthenacycle species contain an exocyclic C=C moiety, presumably formed by the insertion of a terminal alkyne into the Ru−N and Ru−S bonds. The new species have been characterized spectroscopically and the structures were further confirmed by single‐crystal X‐ray diffraction analysis. Theoretical studies and chemical‐bonding analyses established that charge transfer occurs from phosphorus to ruthenium center following the trend PCy3

The synthesis and reactivity of ruthenium complexes containing an anionic boron based ligand, supported by mercapto-benzothiazolyl heterocycles are presented. Specifically, the reaction of [(η6-p-cymene)Ru{P(OMe)2OR}Cl2], (1a: R = Me; 1b: R = H) with [H2B(mbz)2]− (mbz = 2-mercaptobenzothiazolyl) at room temperature afforded a series of borate complexes, namely [(L)Ru{κ3-H,S,S′-H2B(L)2}P(O)(OMe)(HL)], 2, [Ru{κ3-H,S,S′-H2B(L)2}2], 3 and [(κ2-N,S-L)P(OMe)3Ru{κ3-H,S,S′-H2B(L)2}], 4a; (L = C7H4NS2). The pivotal feature of 2 is the coordination of the Ru centre with a phosphorus atom of secondary phosphine oxide and mercapto-benzothiazolyl ligands. On the other hand, 3 features dual Ru…H–B interactions between Ru and B–H bonds of [H2B(mbz)2]−. Interestingly, along with 3, compound [(κ2-N,S-L)P(OPh)3Ru{κ3-H,S,S′-H2B(L)2}], 4b (L = C7H4NS2), was isolated upon treatment of the same borate with [(η6-p-cymene)RuCl2P(OPh)3], 1c, which is stabilized by δ-B–H interactions and one phosphite ligand. Furthermore, compound 3 promptly reacts with P(OR)3 to generate [(OR)3PRu-{κ2-S,S′-H2B(L)2}{κ3-H,S,S′-H2B(L)2}], (5a: R = Me, 5b: R = Ph; L = C7H4NS2) by breaking one of the Ru…H–B interactions. Upon heating, compound 5a converts into [(OMe)2OPRu{κ2-S,S′-HB(L)2}{κ3-H,S,S′-H2B(L)2}], 6a (L = C7H4NS2) by release of methane gas. Compound 6a is a unique example wherein the boron atom of the borate ligand is bound to an oxygen atom of the phosphite unit. In contrast, the thermolysis of 3 with PR2R′ yielded [Ru{κ3-H,S,S′-H2B(L2)}(PR2R′)2(L)], (7a: R = Me, R′ = Ph; 7b: R = Ph; R′ = Me; L = C7H4NS2), respectively, revealing the incorporation of two triphosphine ligands in the coordination sphere of ruthenium. Density functional theory (DFT) calculations were undertaken to provide an insight into the electronic structures of the complexes. [ABSTRACT FROM AUTHOR]

A number of heterometallic boride clusters have been synthesized and structurally characterized using various spectroscopic and crystallographic analyses. Thermolysis of [Ru3(CO)12] with [Cp*WH3(B4H8)] (1) yielded [{Cp*W(CO)2}2(μ4-B){Ru(CO)3}2(μ-H)] (2), [{Cp*W(CO)2}2(μ5-B){Ru(CO)3}2{Ru(CO)2}(μ-H)] (3), [{Cp*W(CO)2}(μ5-B){Ru(CO)3}4] (4) and a ditungstaborane cluster [(Cp*W)2B4H8Ru(CO)3] (5) (Cp*=η5-C5Me5). Compound 2 contains 62 cluster valence-electrons, in which the boron atom occupies the semi-interstitial position of a M4-butterfly core, composed of two tungsten and two ruthenium atoms. Compounds 3 and 4 can be described as hetero-metallic boride clusters that contain 74-cluster valence electrons (cve), in which the boron atom is at the basal position of the M5-square pyramidal geometry. Cluster 5 is analogous to known [(Cp*W)2B5H9] where one of the BH vertices has been replaced by isolobal {Ru(CO)3} fragment. Computational studies with density functional theory (DFT) methods at the B3LYP level have been used to analyze the bonding of the synthesized molecules. The optimized geometries and computed 11B NMR chemical shifts satisfactorily corroborate with the experimental data. All the compounds have been characterized by mass spectrometry, IR, 1H, 11B and 13C NMR spectroscopy, and the structural architectures were unequivocally established by crystallographic analyses of clusters 2-5. [ABSTRACT FROM AUTHOR]

In a quest for efficient precursors for the synthesis of boratrane complexes of late transition metals, we have developed a useful synthetic method using [L′M(μ-Cl)Clx]2 as precursors (L′=η6-p-cymene, M=Ru, x=1; L′=COD, M=Rh, x=0 and L′=Cp*, M=Ir or Rh, x=1; COD=1,5-cyclooctadiene, Cp*=η5-C5Me5). For example, treatment of Na[(H3B)bbza] or Na[(H2B)mp2] (bbza=bis(benzothiazol-2-yl)amine; mp=2-mercaptopyridyl) with [L′M(μ-Cl)Clx]2 yielded [(η6-p-cymene)RuBH{(NCSC6H4)(NR)}2] (2; R=NCSC6H4), [{N(NCSC6H4)2}RhBH{(NCSC6H4)(NR)}2] (3; R=NCS-C6H4), [(η6-p-cymene)RuBH(L)2] (5; L=C5H4NS), and [Cp*MBH(L)2] (6 and 7; L=C5H4NS, M=Ir or Rh). In order to delineate the significance of the ligands, we studied the reactivity of [(COD)Rh(μ-Cl)]2 with Na[(H3B)bbza], which led to the formation of the isomeric agostic complexes [(η4-COD)Rh(μ-H)BHRh(C14H8N3S2)3], 4 a and 4 b, in parallel to the formation of 16-electron square-pyramidal rhodaboratrane complex 3. Compounds 4 a and 4 b show two different geometries, in which the Rh−B bonds are shorter than in the reported Rh agostic complexes. The new compounds have been characterized in solution by various spectroscopic analyses, and their structural arrangements have been unequivocally established by crystallographic analyses. DFT calculations provide useful insights regarding the stability of these metallaboratrane complexes as well as their M→B bonding interactions. [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]

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]

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]

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]

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]

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]

Room temperature photolysis of a triply-bridged borylene complex, [(μ3-BH)(Cp*RuCO)2(μ-CO)Fe(CO)3] ( 1 a; Cp*=C5Me5), in the presence of a series of alkynes, 1,2-diphenylethyne, 1-phenyl-1-propyne, and 2-butyne led to the isolation of unprecedented vinyl-borylene complexes ( Z)-[(Cp*RuCO)2(μ-CO)B(CR)(CHR′)] ( 2: R, R′=Ph; 3: R=Me, R′=Ph; 4: R, R′=Me). This reaction permits a hydroboration of alkyne through an anti -Markovnikov addition. In stark contrast, in the presence of phenylacetylene, a metallacarborane, closo-[1,2-(Cp*Ru)2(μ-CO)2{Fe2(CO)5}-4-Ph-4,5-C2BH2] ( 5 a), is formed. A plausible mechanism has been proposed for the formation of vinyl-borylene complexes, which is supported by density functional theory (DFT) methods. Furthermore, the calculated 11B NMR chemical shifts accurately reflect the experimentally measured shifts. All the new compounds have been characterized in solution by mass spectrometry and IR, 1H, 11B, and 13C NMR spectroscopies and the structural types were unequivocally established by crystallographic analysis of 2, 5 a, and 5 b. [ABSTRACT FROM AUTHOR]

Abstract: DFT calculations were carried out on compound Cp*2Ru2(B8H14) that suggests a strong link with the pentalene complex Cp*2Fe2(C8H6). Both compounds exhibit similar bonding modes and qualitatively related electronic structures. There are however, differences which are related to the weaker B–B bond in the B8H14 ligand as compared to the C–C bond in the pentalene ligand. [Copyright &y& Elsevier]

Heterometallic cubane-type clusters were synthesized from the reaction of group 6 and 8 metallaboranes using transition-metal carbonyl compounds. Structural and spectroscopic study revealed the existence of novel "capped-cubane" geometry. In addition, the crystal structure of these clusters distinctly confirms the presence of boride unit as one of the vertices. These clusters possess 60 cluster valence electrons (cve) and six metal--metal bonds. A plausible pathway for the formation of ruthenium-capped cubane has been described. [ABSTRACT FROM AUTHOR]

The reaction of nido-[1,2-(Cp*RuH)2B3H7] ( 1 a, Cp*=η5-C5Me5) with [Mo(CO)3(CH3CN)3] under mild conditions yields the new metallaborane arachno-[(Cp*RuCO)2B2H6] ( 2). Compound 2 catalyzes the cyclotrimerization of a variety of internal- and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivities of nido- 1 a and arachno- 2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne-insertion to catalytic cyclotrimerization, respectively. Density functional calculations have been used to evaluate the reaction pathways of the cyclotrimerization of alkynes catalyzed by compound 2. The reaction involves the formation of a ruthenacyclic intermediate and the subsequent alkyne-insertion step is initiated by a [2+2] cycloaddition between this intermediate and an alkyne. The experimental and quantum-chemical results also show that the stability of the metallacyclic intermediate is strongly dependent on the nature of the substituents that are present on the alkyne. [ABSTRACT FROM AUTHOR]

Correction for ‘Mercapto-benzothiazolyl based ruthenium(ii) borate complexes: synthesis and reactivity towards various phosphines’ by Mohammad Zafar, et al., Dalton Trans., 2019, DOI: 10.1039/c9dt00498j. [ABSTRACT FROM AUTHOR]

The thermolysis of arachno-1 [(Cp*Ru)2(B3H8)(CS2H)] in the presence of tellurium powder yielded a series of ruthenium trithia-borinane complexes: [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 2, [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3B(SMe)}] 3, and [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 4. Compounds 2–4 were considered as ruthenium trithia-borinane complexes, where the central six-membered ring {C2BS3} adopted a boat conformation. Compounds 2–4 were similar to our recently reported ruthenium diborinane complex [(Cp*Ru){(η2-SCHS)CH2S2(BH2)2}]. Unlike diborinane, where the central six-membered ring {CB2S3} adopted a chair conformation, compounds 2–4 adopted a boat conformation. In an attempt to convert arachno-1 into a closo or nido cluster, we pyrolyzed it in toluene. Interestingly, the reaction led to the isolation of a capped butterfly cluster, [(Cp*Ru)2(B3H5)(CS2H2)] 5. All the compounds were characterized by 1H, 11B{1H}, and 13C{1H} NMR spectroscopy and mass spectrometry. The molecular structures of complexes 2, 3, and 5 were also determined by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Reactivity of borate ligand derived from CS 2 with κ2- N,S -chelated ruthenium borate complexes, [Ph 3 P(κ2- N,S -L)Ru{κ3- H,S,S ′-H 2 B(L) 2 }], (L = C 7 H 4 NS 2 , C 5 H 4 NS) has been demonstrated that led to the formation of ruthenium dithioformate and trithia-borinane complexes. [Display omitted] The reactivity of κ2 - N,S -chelated ruthenium borate complexes, [Ph 3 P(κ2 - N,S -L)Ru{ κ3 - H,S,S ′-H 2 B(L) 2 }], (L = C 5 H 4 NS, C 7 H 4 NS 2) 1 and 3 with borate ligand derived from CS 2 has been investigated. The thermolysis of [Ph 3 P(κ2 - N,S -C 5 H 4 NS)Ru{ κ3 - H,S,S ′-H 2 B(C 5 H 4 NS) 2 }], 1 with Na[BH 3 (SCHS)] led to the formation of ruthenium dithioformate complexes, [PPh 3 (κ3 - H,S,S ′-H 2 B(C 5 H 4 NS)}Ru{(η 2-SCHS)}], trans- 2 and [PPh 3 (κ3 - H,S,S ′-H 2 B(C 5 H 4 NS)}Ru{(η 2-SCHS)}], cis- 2. Further, to study the reactivity of the same borate ligand derived from CS 2 , we have performed the reaction of [Ph 3 P(κ2 - N,S -C 7 H 4 NS 2)Ru{ κ3 - H,S,S ′-H 2 B(C 7 H 4 NS 2) 2 }], 3 with Na[BH 3 (SCHS)] that yielded ruthenium dithioformate, [Ph 3 P(κ2 - N,S -C 5 H 4 NS)Ru{(η 2-SCHS)}], cis- 4 and 1,3,5-trithia-2-borinane, [PPh 3 Ru{ κ3 - H,S,S′ -H 2 B(NC 7 H 4 S 2) 2 }]{(SCH 2) 2 SBH}], 5 complexes. All these studies show that cis- 4 is analogous to trans- 2 and cis- 2. The solid-state X-ray structure of 5 shows that the ruthenium center is stabilized by diborate, phosphine and six-membered ruthenacycle [RuSBNCS] ring that is fused with a {C 2 S 3 B} ring. The synthesized complexes have been thoroughly characterized by various spectroscopic techniques and single-crystal X-ray diffraction analysis of trans- 2 , cis- 2 and 5. Density functional theory (DFT) calculations further provided an insight into the electronic structures of the complexes. [ABSTRACT FROM AUTHOR]

In an objective to synthesize metallaheteroboranes containing heavier chalcogen atoms, we performed the reaction of dimetallaborane analogues of pentaborane(9) with various chalcogen sources. As a result, the thermolysis of nido -[1,2-(Cp*RuH) 2 B 3 H 7 ], 1 (Cp* = η 5 -C 5 Me 5 ) with mixture of S and Se powder was carried out, that led to the isolation of half sandwich dimetallaheteroborane arachno -[(1,2-Cp*Ru) 2 B 2 H 6 S 2 ], 2 . On the other hand, the reaction of nido - 1 with diorganyldichalcogenide ligands, [Ph 2 E 2 ] afforded chalcogen bridged half sandwich complexes [(2,3-Cp*Ru) 2 B 3 H 6 (μ-η 1 -EPh)], 4a-c ( 4a : E = S; 4b : E = Se and 4c : E = Te). Compound 2 can be derived from a closo- snub disphenoid by removing a 5-connect vertex followed by the removal of a 3-connect vertex. Compound 4a – c can be described as nido -square pyramidal structures, isoelectronic and isostructural with nido - 1 . All the compounds have been characterized by mass spectrometry, 1 H, 11 B and 13 C spectroscopy. Further, the geometry of compounds 2 , 3 , 4b and 4c were unequivocally established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

• Synthesis and structural characterization of tri-niobium cluster with a trithiaborate ligand. • Synthesis and structural characterization of three nido -ruthenium clusters. • Theoretical investigations have been performed to understand the electronic structure and bonding scenario in these clusters. In an effort to synthesize niobaheteroboranes and ruthenaheteroboranes, two different synthetic methods are developed. The reactions of [Cp*NbCl 4 ] (1) with chalcogenaborate ligands [LiBH 2 E 3 ] (E = S , Se) were carried out under reflux conditions. The reaction with sulfur yielded a triniobium polysulfide cluster [(Cp*Nb) 3 (μ 3 -S) 3 {B(OCH 3)}(μ -S) 3 ] (2) in which a trithiaborate ligand [S 3 B(OCH 3)]− is coordinated to Nb 3 framework in a cubane-type geometry. While the reaction with selenium generated a diniobium polyselenide cluster [(Cp*NbCl) 2 (μ -Se 2 -κ 1Se: κ 2Se') 2 (μ -O)] (3) in which two diselenide ligands {[Se 2 ]2−} are coordinated with both the metal centres in an unsymmetrical κ 1: κ 2 fashion. On the other hand, efforts were directed towards expliciting the coordinative sulfur centres of a preformed arachno ‑ruthenaborane [(Cp*Ru) 2 (B 3 H 8)(CS 2 H)] (arachno ‑ 4) , by carrying out the pyrolysis of arachno ‑ 4 with excess [BH 3 ⋅THF]. The reaction led to the formation of sulfido stabilized pileo cluster nido ‑ruthenathiaborane [2,3-(Cp*Ru) 2 (μ -H)(B 3 H 6)S] (5) , nido ‑ruthenaborane [2,3-(Cp*Ru) 2 (μ -H)(B 4 H 5 Me)] (6) and thiomethyl bridged nido ‑ruthenaborane [2,3-(Cp*Ru) 2 (μ -SMe)(B 3 H 6)] (7). One of the key features of complex 5 is the presence of an unusual pentacoordinated sulfido ligand(μ 5 -S). All the complexes have been characterized by multinuclear NMR, mass spectrometry and their structural architectures have been unambiguously established by single-crystal X-ray diffraction studies. In addition, theoretical investigations provided valuable insights into the electronic structures and bonding of these clusters. [ABSTRACT FROM AUTHOR]

In an effort to synthesize trithiocarbonate complexes of molybdenum and ruthenium, we carried out the reaction of CS 2 with the intermediates, obtained from the reaction of [Cp # ML 3 X], ( 1 : Cp # = C 5 Me 5, M = Mo, L 1 = L 2 = L 3 = CO, X = Me; 2 : Cp # = C 5 H 5, M = Ru, L 1 = L 2 = PPh 3 , X = Cl and 3 : Cp # = C 5 H 5, M = Fe, L 1 = L 2 = CO, X = I) and [LiBH 4 ⋅thf]. The reactions led to formation of the trithiocarbonate complexes [Cp*Mo(CO) 2 (μ-ɳ 2 :ɳ 1 -CS 3 )(CO) 3 MoCp*] ( 4 ) [Cp*Mo(CO) 2 (ɳ 2 -S 2 CSMe)] ( 5 ) and [Cp*Mo(CO) 2 (ɳ 2 -S 2 CMe)] ( 6 ) in moderate yields. Treatment of [CpRu(PPh 3 ) 2 Cl] ( 2 ) with [LiBH 4 ⋅thf] followed by mild pyrolysis of CS 2 yielded the trithiocarbonate ruthenium complex [CpRuPPh 3 (ɳ 2 -S 2 CSMe)] ( 7 ). All the new compounds have been characterized by various spectroscopic techniques and the structures of compounds 4 , 5 and 7 were unequivocally established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

• Various ruthenium-incorporated tris- and bishomocubane analogues have been synthesised and their reactivity with metal carbonyls has been explored that allowed isolation of heterometallic Fe/Se clusters. • The experimental results have been accompanied and rationalized using DFT studies. Various ruthenium-incorporated tris- and bishomocubane analogues have been documented. The reaction between [Cp*RuCl 2 ] 2 (Cp* = η5-C 5 Me 5) and [BH 2 Se 3 ]Li at room temperature yielded bimetallic trishomocubane, [(Cp*Ru) 2 (μ 3 -Se) 4 (μ-Se) 3 (BH) 2 ], 1 ; and bishomocubane, [(Cp*Ru) 2 (μ 3 -Se) 5 (μ-Se) 2 (BH)], 2. To the best of our knowledge, compound 1 is the first Se analogue of trishomocubane that has been isolated as a 1,2,3-isomer. With an objective of replacing the B–H vertex of compound 2 with an isolobal {Fe(CO) 3 } fragment, the reaction of compound 2 with [Fe 2 (CO) 9 ] was carried out under photolytic conditions. Although the aim of obtaining a homocubane core compound was not achieved, the reaction yielded interesting heterometallic chalcogenide compounds, [{μ-Se(Cp*Ru(CO) 2)} 2 {Fe(CO) 3 } 4 (μ 4 -Se)], 3 , and [{Cp*Ru(CO) 2 }(μ 4 -Se){(μ-H)(Fe(CO) 3) 3 }], 4. Compound 3 is a unique example of vertex-fused cluster, in which two butterfly {Fe 2 Se 2 } moieties are fused together through a common Se vertex and a {Cp*Ru(CO) 2 } unit is attached to each of the terminal Se atoms. In compound 4 , the Se atom of a {Fe 3 Se} tetrahedron is connected to a {Cp*Ru(CO) 2 } fragment. Multinuclear NMR, infrared and UV–Vis spectroscopy, mass spectrometry as well as single crystal X-ray diffraction studies were performed for the characterization of compounds 1 – 4. Density functional theory methods were also employed for elucidating the bonding in these compounds. [ABSTRACT FROM AUTHOR]

The chemistry of ruthenium–borane complex, [Cp ∗ RuCO(μ-H)BH 2 L] (Cp ∗ = η 5 -C 5 Me 5 ; L = C 7 H 4 NS 2 ), 1 with various alkynes has been explored. Photolysis of 1 with alkynyl-Grignard, [HC CMgBr] in toluene led to the isolation of vinyl hydroborate complex [Cp ∗ Ru(μ-H)BH{HC CH 2 }L], 2a as a sole product. Compound 2a can be viewed as a ruthenium–borate complex with an ethylene moiety. Further, the chemistry of 1 with various internal and terminal alkynes has been performed in photolytic conditions. Photolysis of 1 with [RC CR] (R = CO 2 Me) yielded vinyl hydroborate complex [Cp ∗ Ru(μ-H)BCl{RC CR}L], 2b . Terminal alkynes [HC CR] (R = Ph or CO 2 Me) under the same reaction conditions led to the isolation of metal vinyl complexes [Cp ∗ Ru(CO)(C 2 HR)(L)], 3a and 3b ( 3a : R = Ph; 3b : R = CO 2 Me). In addition, DFT calculations were carried out to analyze the bonding and electronic structures of these new compounds. [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]

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 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]

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]

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]

Room temperature photolysis of a triply-bridged borylene complex, [(μ3-BH)(Cp*RuCO)2(μ-CO)Fe(CO)3] ( 1 a; Cp*=C5Me5), in the presence of a series of alkynes, 1,2-diphenylethyne, 1-phenyl-1-propyne, and 2-butyne led to the isolation of unprecedented vinyl-borylene complexes ( Z)-[(Cp*RuCO)2(μ-CO)B(CR)(CHR′)] ( 2: R, R′=Ph; 3: R=Me, R′=Ph; 4: R, R′=Me). This reaction permits a hydroboration of alkyne through an anti -Markovnikov addition. In stark contrast, in the presence of phenylacetylene, a metallacarborane, closo-[1,2-(Cp*Ru)2(μ-CO)2{Fe2(CO)5}-4-Ph-4,5-C2BH2] ( 5 a), is formed. A plausible mechanism has been proposed for the formation of vinyl-borylene complexes, which is supported by density functional theory (DFT) methods. Furthermore, the calculated 11B NMR chemical shifts accurately reflect the experimentally measured shifts. All the new compounds have been characterized in solution by mass spectrometry and IR, 1H, 11B, and 13C NMR spectroscopies and the structural types were unequivocally established by crystallographic analysis of 2, 5 a, and 5 b. [ABSTRACT FROM AUTHOR]