Chemistry of bimetallic hexaborane(10) analogues: A combined experimental and theoretical study

Cluster nido-[3,6-{(OC)3Mn}2(B4H8·THF)], 1, (THF = tetrahydrofuran), has been synthesized from the irradiation of [Mn2(CO)10] with [BH3·THF] at 255 nm along with [{(OC)4Mn}(η6-B2H6){Mn(CO)3}2(µ-H)], 2. Cluster 1 represents the new structural analogue of nido-homobimetallahexaborane(10) where the metal centers are arranged symmetrically in the non-adjacent basal positions of a pentagonal pyramid core. Theoretical calculation suggests that nido-1 is thermodynamically more stable as compared to the other hypothetical possible isomer nido-[4,5-{(OC)3Mn}2(B4H8·THF)], II. Further, the reactivity of another homobimetallahexborane(10), nido-[1,2-(Cp*Ru)2(µ-H)B4H9], 3 has been explored with borane that led to cluster build-up reaction to yield bimetallaoctaborane(12) analogues, nido-[(Cp*Ru)2B6H10(OH)2], 4 and nido-[(Cp*Ru)2B6H11(OH)], 5. All the clusters have been characterized by multinuclear NMR and IR spectroscopies as well as by mass spectrometric analysis. The structural types of 1 and 4 were unequivocally established by crystallographic analysis.