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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]

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]

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]

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 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]

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]

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]

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]

The preparation, characterization, and electronic structure of the first heterometallic μ9-boride cluster [(Cp*Rh)2{Co6(CO)I2}(μ-H)(BH)B)] has been reported. The interstitial boron atom in the title cluster is within the bonding contact of eight metal and one boron atom in a unique tricapped trigonal prism geometry. [ABSTRACT FROM AUTHOR]

The reaction of [Cp(n)MCl(4-x)] (M=V: n=2, x=2; M=Nb: n=1, x=0; Cp=η(5)-C(5) H(5)) with LiBH(4)⋅THF followed by thermolysis in the presence of dichalcogenide ligands E(2)R(2) (E=S, Te; R=2,6-(tBu)(2)-C(6)H(2)OH, Ph) and 2-mercaptobenzothiazole (C(7)H(5)NS(2)) yielded dimetallaheteroboranes [{CpV(μ-TePh)}(2)(μ(3) -Te)BH⋅thf] (1), [(CpV)(2)(BH(3)S)(2)] (2), [(CpNb)(2)B(4)H(10)S] (3), [(CpNb)(2)B(4)H(11)S(tBu)(2)C(6)H(2)OH] (4), and [(CpNb)(2)B(4)H(11)TePh] (5). In cluster 1, the V(2)BTe atoms define a tetrahedral framework in which the boron atom is linked to a THF molecule. Compound 2 can be described as a dimetallathiaborane that is built from two edge-fused V(2)BS tetrahedron clusters. Cluster 3 can be considered as an edge-fused cluster in which a trigonal-bipyramidal unit (Nb(2)B(2)S) has been fused with a tetrahedral core (Nb(2)B(2)) by means of a common Nb(2) edge. In addition, thermolysis of an in-situ-generated intermediate that was produced from the reaction of [Cp(2)VCl(2)] and LiBH(4)⋅THF with excess BH(3)⋅THF yielded oxavanadaborane [(CpV)(2)B(3)H(8)(μ(3)-OEt)] (6) and divanadaborane cluster [(CpV)(2)B(5)H(11)] (7). Cluster 7 exhibits a nido geometry with C(2v) symmetry and it is isostructural with [(Cp*M)(2)B(5)H(9+n)] (M=Cr, Mo, and W, n=0; M=Ta, n=2; Cp*=η(5)-C(5)Me(5)). All of these new compounds have been characterized by (1)H NMR, (11)B NMR, and (13)C NMR spectroscopy and elemental analysis and the structural types were established unequivocally by crystallographic analysis of compounds 1-4, 6, and 7., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)