Cluster chemistry driven by ligand bulk. Significance of the synthesis of nido-1-(.eta.5-C5Me5)Co-2-(.eta.4-C5Me5H)CoB3H8 and its dehydrogenation to nido-2,4-{(.eta.5-C5Me5)Co}2B3H7

Reactions of the Cobaltaborane 2,4-{(η5-C5Me5)Co}2B3H7with Metal Fragments. Synthesis and Characterization ofnido-1-{(η5-C5Me5)Co}-2-{(CO)3Fe}B3H7andarachno-(η5-C5Me5)(CO)CoB3H7

“…Clearly, the structure of 2 is derived from that of B 5 H 9 in which an apical BH fragment is replaced by Cp*Co and a basal BH fragment by Fe(CO) 3 . The compound is most closely related to 1,2-{Fe(CO) 3 } 2 B 3 H 7 ( 2 ‘) and nido -1,2-(Cp*Co)(μ-H){(η 4 -C 5 Me 5 H)Co}B 3 H 7 ( 2 ‘‘) but is also a metal fragment positional isomer of 2,4-(Cp*Co) 2 B 3 H 7 40 and 2-(Cp*Os)-3-{(PPh 3 ) 2 (CO)Rh}B 3 H 7 1 Molecular structure of nido -1-(Cp*Co)-2-{(CO) 3 Fe}B 3 H 7 , 2 , with thermal ellipsoids at 40% probability. 2 Selected Bond Lengths (Å) and Angles (deg) for nido -1-{(η 5 -C 5 Me 5 )Co}-2-{(CO) 3 Fe}B 3 H 7 , 2 Co−Fe 2.4443(4) Fe−H(1) 1.66(3) Co−B(2) 1.975(2) Fe−H(6) 1.67(3) Co−B(3) 1.999(3) B(1)−B(2) 1.785(4) Co−B(1) 2.005(2) B(2)−B(3) 1.778(4) Co−C(2) 2.054(2) B(1)−H(1) 1.29(2) Co−C(3) 2.054(2) B(1)−H(2) 1.28(3) Co−C(1) 2.092(2) B(1)−H(3) 1.01(2) Co−C(4) 2.093(2) B(2)−H(2) 1.21(3) Co−C(5) 2.115(2) B(2)−H(4) 1.24(3) Fe−C(11) 1.770(3) B(2)−H(5) 1.05(3) Fe−C(13) 1.776(3) B(3)−H(4) 1.32(3) Fe−C(12) 1.800(3) B(3)−H(6) 1.29(3) Fe−B(3) 2.243(3) B(3)−H(7) 1.07(3) Fe−B(1) 2.248(3) B(2)−Co−B(3) 53.13(11) H(1)−B(1)−H(3) 105(2) B(2)−Co−B(1) 53.27(11) H(2)−B(1)−H(3) 107(2) B(3)−Co−B(1) 81.07(11) B(3)−B(2)−B(1) 93.9(2) B(2)−Co−Fe 86.36(8) B(3)−B(2)−Co 64.12(11) B(3)−Co−Fe 59.64(8) B(1)−B(2)−Co 64.20(11) B(1)−Co−Fe 59.72(7) B(3)−B(2)−H(2) 114.5(14) B(3)−Fe−B(1) 70.83(10) B(1)−B(2)−H(2) 45.9(13) B(3)−Fe−Co 50.27(7) Co−B(2)−H(2) 110.1(14) B(1)−Fe−Co 50.37(6) B(3)−B(2)−H(4) <...…”

Synthesis and crystal structures of two (cyclopentadienyl)titanium(III) hydroborate complexes, [Cp∗TiCl(BH4)]2 and Cp2Ti(B3H8)

“…A few examples of the reverse reaction have been described: [Mo(CO) 4 (B 3 H 8 ) À ] [15], Cp * ReH 3 (B 3 H 8 ) [16], and WH 3 (B 3 H 8 [17] have been prepared by treating [Mo 2 H(CO) 10 À ], Cp * ReH 6 , and WH 6 (PMe 3 ) 3 with BH 3 Á thf, respectively, and (C 5 H 4 -i-Pr)WH 3 (B 3 H 8 ) has been made by treating (C 5 H 4 -i-Pr)WCl 4 with LiBH 4 [18]. In addition, other B 3 H x fragments (especially those with x = 6 or 7) can be made by adding BH 3 to a transition metal hydride or chloride [19][20][21][22][23][24][25][26][27][28].…”

Effects of metal-centre orbital control on cluster character and electron distribution between borane and hydrocarbon ligands; significance of the structures of [μ-9,10-(SMe)-8,8-(PPh3)2-nido-8,7-IrSB 9H9] and [μ-9,10-(SMe)-8-(η4-C5Me5H)- nido-8,7-RhSB9H9]

“…There is current interest in polyhedral boron-containing cluster compounds that deviate 1 from the dictates of the classical 2, 3 Williams-Wade cluster geometry-electron-counting formalism or which exhibit other unusual cluster behaviour. In this general context there have recently been reports of (a) the unusual incidence of a tetrahapto η 4 -C 5 Me 5 H ligand in [1-(η 5 -C 5 Me 5 )-2-(η 4 -C 5 Me 5 H)-nido-1,2-Co 2 B 3 H 8 ], which is suggested to be sterically driven to form this bidentate η 4 type of co-ordination rather than the η 5 -C 5 Me 5 ligand generally found in metallaborane chemistry, 4 and (b) unusual hydrogen-to-metal agostic interactions in [8-(η 2 -Ph 2 PCH 2 CH 2 Ph 2 )-nido-8,7-RhSB 9 H 10 ] which are proposed 5 in order to convert what can be regarded as a formal Wadian closo electron count into a nido one that would be perhaps interpretable as more consistent with the conventional eleven-vertex nido cluster structure. We now report preliminary results from two compounds that together generate additional significant perspective on these two interesting behavioural modes.…”