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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 recent developments in the field of transition metal (TM) borate complexes have been a landmark in modern coordination chemistry. The structural diversities of these complexes play an important role in several catalytic processes. Generally, polypyrazolyl borate ligands, [BHn(pz)4‐n]− (n=1, 2; pz=pyrazolyl), popularly known as scorpionates have been used extensively for the preparation of TM borate complexes. The presence of multiple donor atoms in the flexible borate proligands led to several coordination modes. Based on the electronic and steric properties of these ligands and the metals, the denticity of borate ligands in TM complexes varied from κ0 to κ6. The presence of different bonding modes of these borate ligands made them very interesting in main group organometallic chemistry. In addition, cooperative activation of boranes by TM complexes containing metal‐nitrogen or metal‐sulfur bonds has become an alternative to the utilization of borate proligands for the synthesis of TM borate complexes. This review summarizes the advancements of the chemistry of TM borate complexes focusing exclusively on the synthetic methods and various bonding scenarios. [ABSTRACT FROM AUTHOR]

Azametallacyclopropane‐containing base stabilized borane complexes of group 5 transition metals have been synthesized and their structural aspects have been described. Treatment of Cp* based Ta and Nb chlorides, Cp*TaCl4 and Cp*NbCl4 with [LiBH4 ⋅ THF] followed by addition of ligands, such as 2‐mercaptobenzothiazole, MBT, (C7H5NS2) and 2‐mercaptobenzoxazole, MBO (C7H5NSO) led to the formation of complexes [Cp*M‐[BHS(CH2ENC6H4)(C7H4NSE)] (1: M=Ta, E=S; 2; M=Nb, E=S; 3: M=Ta, E=O; 4; M=Nb, E=O, Cp*=pentamethyl‐η5‐cyclopentadienyl). By means of UV‐vis absorption spectra, the electronic properties of these complexes associated with central metal atoms and heteroatoms (S or O) have been evaluated. In contrast, treatment of Cp*TaCl4 with 2‐mercaptopyridine, MP, (C5H5NS) under the same reaction conditions yielded the agostic σ‐borane Ta complex, [Cp*Ta(H3BNC5H4) (C5H4NS)(η2‐S2)], 5. Unlike 1–4, where the metals interact with boron through bridging sulphur, 5 shows a notable σ‐B−H bond interaction with Ta. All spectroscopic data of 1–5 along with the X‐ray diffraction studies suggest complexes 2, 4, and 5 are base (amine) stabilized borane species. Computational studies based on Density Functional Theory (DFT) also supported this conclusion. [ABSTRACT FROM AUTHOR]

The reactivity of κ2‐N,S‐chelated ruthenium borate complexes, [Ru(PPh3)(κ2‐N,S‐(NC7H4S2)Ru{κ3‐H,S,S′‐H2B (NC7H4S2)2}] (1 a) and [Ru(PPh3)(κ2‐N,S‐(NC5H4S){κ3‐H,S,S′‐H2B(NC5H4S)2}] (1 b) with monoboranes have been explored. The prolonged room temperature reaction of [Ru(PPh3){κ2‐N,S‐(NC7H4S2)}{κ3‐H,S,S′‐H2B(NC7H4S2)2}], 1 a with an excess of [BH3 ⋅ THF] led to the formation of hydrogen‐rich complex, arachno‐[PPh3(κ2‐B3H8)Ru{κ3‐H,S,S′‐H2B(NC7H4S2)2] (2). In a similar fashion, the isomeric ruthenatetraborane complexes of [Ru(PPh3)(κ2‐N,S‐(B3H8){κ3‐H,S,S′‐H2B(NC5H4S)2}], 4 and 5 were isolated from the room temperature reaction of 1 b with [BH3 ⋅ THF]. In complex 2, the borate ligand, [H2B(NC5H4S)2] and the PPh3 occupy the endo and exo sites of the butterfly‐shaped RuB3 core, respectively. In contrast, the borate unit [H2B(NC5H4S)2] in 4 sits on the exo position of the butterfly core, while the phosphine ligand occupies the endo site. Multinuclear spectroscopic analyses were done to characterize all new complexes and the structures were further confirmed by single‐crystal X‐ray diffraction analysis. Density functional theory (DFT) calculations were performed to probe into the bonding modes of these complexes. [ABSTRACT FROM AUTHOR]

Synthesis, bonding and chemistry of mono‐ and bimetallic complexes supported by chelating thiolato ligands have been established. Treatment of [Cp*VCl2]3 (1) with [LiBH4 ⋅ THF] followed by the addition of ethane‐1,2‐dithiol led to the formation of an EPR active bimetallic vanadium thiolato complex [(Cp*V){μ‐(SCH2CH2S)‐κ2S,S′)2{V(SCH2CH2S‐SH)}] (2). In complex 2, two ethane‐1,2‐dithiolato ligands are symmetrically coordinated to two vanadium atoms through μ‐S atoms. Interestingly, when similar reactions were carried out with heavier group 5 metal precursors, such as [Cp*NbCl4] (3 a), it afforded monometallic thiolato complex [Cp*Nb(SCH2CH2S)(SCH2CH2S−CH2S)] (4 a). On the other hand, the Ta‐analogue [Cp*TaCl4] (3 b) yielded thiolato species [Cp*Ta(SCH2CH2S)(SCH2CH2S−CH2S)] (4 b) and [Cp*Ta(SCH2CH2S) (SCH2CH2S−S)] (5). In complexes 4 a and 4 b, one ethane‐1,2‐dithiolato and one trithiolato ligand are coordinated to Nb and Ta centers, respectively. Whereas, in complex 5, one ethane‐1,2‐dithiolato and one 2‐disulfanylethanethiolato is coordinated to the Ta center. Moreover, the photolytic reaction of 5 with [Mo(CO)5 ⋅ THF] yielded heterobimetallic thiolato complex [(Cp*Ta){μ‐(SCH2CH2S)‐κ2S,S′}{μ‐(SCH2CH2S−CH2(CH3)S)κ2S′′ : κ1S‐′′′′ : κ1S′′′′′}{Mo(CO)3}] (6). All the complexes have been characterized by multinuclear NMR spectroscopy and single crystal X‐ray diffraction studies. Further, computational analyses were performed to provide an insight into the bonding of these complexes. [ABSTRACT FROM AUTHOR]

A series of triborane and tetraborane analogues have been isolated and structurally characterized utilizing chalcogenatoborate ligands Li[BH3(EPh)] (E=S or Se). Thermolysis of [Cp*TaCl4] in the presence of Li[BH3(SPh)] afforded bimetallic tantallaheteroborane [(Cp*Ta)2(μ‐η3:η3‐B2H4S)(μ‐η2:η2‐SBH3)] (1) and hexasulfido trimetallic complex [(Cp*Ta)3(μ‐S)4(μ‐SPh)2] (2). Compound 1 is a fused ditantallaheteroborane, in which both di‐ and triborane analogues are stabilized by two tantalum atoms. In an attempt to synthesize the selenium analogues of 1 and 2, room‐temperature reaction of [Cp*TaCl4] with Li[BH3(SePh)] was carried out, which afforded bimetallic tantallaheteroborane [(Cp*Ta)2{μ‐η3:η3‐B3H6(SePh)}{μ‐SePh}2] (3), monometallic tantallaheteroboranes [Cp*Ta(SePh)2{B4H8‐n(SePh)n}] (4: n=0, 5: n=1), and trimetallic species [(Cp*Ta)3(μ‐Se)4{μ‐Se2(Se)}] (6). Compound 3 is the rarest example of triborane analogue {B3H6(SePh)} in the coordination sphere of two tantalum atoms. Whereas compounds 4 and 5 are examples of unsaturated metallaheteroboranes, in which the tetraborane analogues are stabilized in the coordination sphere of tantalum. One of the unique features of 3 and 5 is the presence of terminal B‐SePh. Compound 6 has similar Ta3Se6 trisbutterfly core as that of 2 with additional bridging selenide unit. All the compounds have been characterized by NMR spectroscopy, mass spectrometry, IR spectroscopy and single‐crystal X‐ray diffraction studies. [ABSTRACT FROM AUTHOR]

Treatment of a dirhodium analogue of pentaborane(9), [(Cp*Rh)2B3H7] (nido‐1; Cp* = η5‐C5Me5), with [Fe2(CO)9] at room temperature led to the formation of [(Cp*Rh)2Fe(CO)3(µ‐CO)B3H2Cl] (2) and the metal‐rich metallaborane [(Cp*Rh)2Fe(CO)3Fe(CO)2(µ‐CO)2B2H2] (3). When the same reaction was carried out at moderate temperature, two metal‐rich metallaboranes, [(Cp*Rh)3Fe(CO)2(µ3‐CO)2B2HX] 4 (X = H) and 5 (X = Cl), and a heterometallic µ9‐boride cluster, [(Cp*Rh)3(RhCO)3Fe(CO)3(µ‐CO)3B3H2] (6), were obtained. Compounds 4 and 5 can be viewed as cubane clusters with 62 cluster valence electrons (cves) and five metal–metal bonds. In another reaction, the treatment of nido‐1 with [Mn2(CO)10] yielded the heterometallic µ9‐boride cluster [(Cp*Rh)3Rh(CO)2{Mn(CO)3}2B4H3] (7). The cluster cores of both 6 and 7 are comprised of tricapped trigonal prisms containing a µ9‐B atom bonded to seven/six metals and two/three boron atoms, respectively. All the new compounds have been characterized by mass spectrometry, IR, 1H, 11B{1H}, and 13C{1H} NMR spectroscopy, and X‐ray crystallographic analysis. [ABSTRACT FROM AUTHOR]

Building upon our earlier studies of cobaltaheteroboranes, we explore the chemistry with heavier group 9 metals. Reaction of [Cp*M(µ‐Cl)Clx]2 (Cp* = η5‐C5Me5; M = Co, x = 0; M = Rh or Ir, x = 1) with [LiBH4·THF], followed by thermolysis with an excess of chalcogen powders (S or Se), affords dimetallaheteroboranes nido‐[(Cp*M)2B2H2E2], 1–4 (1: E = S; 2: E = Se, M = Co; 3 and 4: E = Se, M = Rh and Ir, respectively) in moderate‐to‐good yields. The solid‐state structures of these compounds show open‐cage triple‐decker clusters. Attempts to isolate the Te analogue have failed; however, in the case of cobalt, we have isolated an 11 skeletal‐electron‐pair nido‐[(Cp*Co)2B5H5Te2], 5. The X‐ray diffraction structure of 5 shows monocapped square antiprismatic geometry, with two Te atoms in the core. To close the central four‐membered B2E2 open ring of nido‐1 and nido‐2, we have performed a reaction with [Ru3(CO)12], which leads to the formation of closo‐[(Cp*Co){µ‐η5:η5‐B2H2E2M}M{µ‐Ru(CO)4}], 6 and 7 [6: E = S; 7: E = Se; M = Ru(CO)2]. In contrast, the reactions of nido‐2 and nido‐3 with [Fe2(CO)9] result in heterometallic clusters nido‐[(Cp*M)Fe(CO)3B2H2Se2], 8 and 9 (8: M = Co; 9: M = Rh), [(Cp*Co)Fe3(CO)8Se2], 10, and [(Cp*Co)Fe2(CO)7Se], 11. As nido‐8 also contains a four‐membered open ring B2Se2, we have treated this with [Ru3(CO)12], which yields closo‐[(Cp*Co){µ‐η5:η5‐B2H2Se2M}M{µ‐Fe(CO)4}], 12 [M = Ru(CO)2], which is analogous to that of 7. In addition, we have analyzed the divergence in the reactivity of nido‐[(Cp*M)2B2H2E2], 2–4, with the help of density functional theory calculations. [ABSTRACT FROM AUTHOR]

The quadruply bridged bimetallic dithiolato complex [(Cp*W)2(µ-S)2(µ,η2-S2CH2)] (3) and the open-cage triple-decker complex [(Cp*W)2(µ-S)(µ-η4:η4-B2H2S2)] (2) have been prepared by treatment of CS2 with in situ generated [(Cp*W)2(B2H6)2] (1) obtained by the reaction of [Cp*WCl4] with [LiBH4·thf]. The solid-state X-ray diffraction structures of these complexes show the presence of doubly bridging η2-S2B2H2 and η2-S2CH2 ligands with a short W–W bond. While many dimolybdenum–sulfur compounds are known, examples of the tungsten–dithilato complexes are relatively few, and in this respect, the isolation of [(Cp*W)2(µ-S)2(µ,η2-S2CH2)] represents a rare example of this type. Electronic-structure analysis, on the grounds of density functional theory (DFT), together with X-ray diffraction studies, has rationalized the presence of short W–W and B–B bonds. Large HOMO–LUMO gaps have been observed for both compounds, which is consistent with their thermodynamic stability. All of the compounds have been characterized by mass spectrometry, IR spectroscopy, and 1H NMR, 11B NMR, and 13C NMR spectroscopy in solution, and the structural architectures have been unambiguously established by X-ray diffraction crystallographic analysis. [ABSTRACT FROM AUTHOR]

Several early-late heterodimetallaborane clusters have been isolated and structurally characterized through spectroscopic and crystallographic analysis. The thermolysis of [Cp2Zr(BH4)2] (Cp = η5-C5H5) with [Cp*IrB3H9] (Cp* = η5-C5Me5) and [(Cp*Rh)2B2H6] yielded arachno-[(Cp2Zr)(Cp*Ir)B3H9] ( 2) and arachno-[(Cp2Zr)(Cp*Rh)B4H10] ( 4), respectively. In a similar fashion, the reaction of [Cp2Hf(BH4)2] was performed with the same set of group 9 metallaboranes that led to the formation of arachno-[(Cp2Hf)(Cp*M′)B4H10] ( 5: M′ = Ir; 6: M′ = Rh). To the best of our knowledge, 2 is the first structurally characterized pentaborane(11) analogue containing zirconium, while the clusters 5 and 6 are the first examples with Hf in a hexaborane(12) core. The bonding between the Zr atoms and the boron ring was studied computationally by DFT methods, and 2 can be defined as a dimetallic analogue of arachno-B5H11 on the basis of the combined experimental and computational results. [ABSTRACT FROM AUTHOR]

The syntheses and structural characterization of the CS2-metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] ( 1: M = Mo; 2: M = W), which feature partially and fully reduced CS2, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η5-C5Me5Mo)2(µ-S2CH2S)2] ( 3- cis and 4- trans) are described. The [Mo2S4] cores of 3- cis and 4- trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and 1H and 13C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′- 4′- trans showed good agreement with the experimentally observed structural parameters. The large HOMO-LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal-metal cross-cluster bonds in the X-ray structures of 3- cis and 4- trans is supported by natural bond order (NBO) calculations. [ABSTRACT FROM AUTHOR]

Treatment of [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) with Li[BH3(SePh)] at room temperature led to the isolation of a dimetala analogue of hexaborane(10), nido-[(Cp*Ir)(µ-SePh)2Ir{(Cp*Ir)SePh}B4H8] ( 1). Solid-state X-ray structure analysis of 1 showed an extended sandwich molecule with two iridium atoms between Cp* and a [B4Ir] ring. Further, in an effort to synthesize the Rh analogue of 1 under similar reaction conditions, we isolated arachno-[{(Cp*Rh)(µ-SePh)3}Rh(µ-SePh)B3H6] ( 2), a rhodium analogue of tetraboarane(10) in which the {RhB3} unit shows geometric equivalence with a metal π-allyl {MC3} species. Ir complex 1, having an Ir-Ir bond, can be considered similar to the dizinc sandwich complex [Cp*Zn-ZnCp*] in terms of the valence electron count at the metal centers. [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]

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]