Electronic, geometrical, and thermochemical studies on group-14 element-diruthenaborane cluster compounds: a theoretical investigation

Density functional theory (DFT) calculations were used to probe the reaction of the diruthenaborane nido-[1,2-(Cp*RuH)2B3H7] (Cp* = η5-C5Me5), (1) with MeC ≡ CMe to form the major product nido-[1,2-(Cp*Ru)2(μ-H)(μ-BH2)-4,5-Me2-4,5-C2B2H4] (2) along with minor product nido-(Cp*Ru)2-4,5-Me2-4,5-C2B2H6 (3). The structural features of the other related diruthenacarboranes, nido-(Cp*Ru)2-4,5-Me2-4,5-C2B2H6 (4) and closo-1,2-(Cp*RuH)2-4,5-Me2-4,5-C2B3H3 (5), were also studied. Since metallaheteroboranes with p-block group-14 elements are rare, we extend our DFT studies to explore the reaction of 1 with heavier group-14 alkyne analogs, RE ≡ ER (E = Si, Ge, and Sn; R = alkyl or aryl groups). The geometrical and electronic structures of the products nido-[1,2-(Cp*Ru)2(μ-H)(μ-BH2)-4,5-Me2-4,5-E2B2H4] (E = Si (6), Ge (7), Sn (8)) are described and compared with the ruthenacarborane analog, nido-[1,2-(Cp*Ru)2(μ-H)(μ-BH2)-4,5-Me2-4,5-C2B2H4] species, 2. The computed energetics and the geometries support the feasibility of the reaction and the stability of the products. NBO analysis was performed to delve further into the nature of the bonding in this kind of clusters.