Yuvaraj, K., Roy, Dipak Kumar, Geetharani, K., Mondal, Bijan, Anju, V. P., Shankhari, Pritam, Ramkumar, V., and Ghosh, Sundargopal
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]