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Abstract: The reactivity of two isoelectronic and isostructural metallaboranes, nido-[(Cp*Rh)2B6H10], 1 and nido-[(Cp*Ru)2B6H12], 2 with alkynes demonstrates that a change in metal from group 9 to group 8 creates difference in the reactivity pattern. Compound 1 catalyzes the cyclotrimerization of a variety of internal and terminal alkynes to yield 1,3,5- and 1,2,4-substituted benzene. In contrast, compound 2 shows no reactivity toward alkynes. A set of alkynes have been verified with nido-1 that yielded several benzene derivatives in satisfactory yields. [Copyright &y& Elsevier]

Abstract: Mild thermolysis of arachno-[(Cp*RuCO)2B2H6], 1 in presence of GeCl2·dioxane yielded di-μ-germylene complex [(Cp*Ru)2(μ-GeCl2)2(CO)2], 2 (Cp* = η5-C5Me5). The molecular structure of 2 exhibits a diruthenium unit bridged by a pair of μ-GeCl2 moieties. The Cp* and the terminal CO ligands are oriented in anti fashion with respect to Ru–Ru bond. In addition, the reaction of 2 with arachno-[CpFe(CO)B3H8] (Cp = η5-C5H5) transformed to germenocene, [Cp2Ge:], 3 via an unstable intermediate [CpFe(CO)B2H5GeCl2], I. The 11B NMR spectroscopy was used as a tool to establish a probable reaction pathway for the formation of germenocene 3. Cluster 2 has been characterized by IR and NMR spectroscopy, and the geometric structure was unequivocally established by crystallographic analysis. [Copyright &y& Elsevier]