Reactivity of the 16eCp*Co half-sandwich complex containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand towards alkynes

Abstract

The 16e half-sandwich complex Cp*Co(S₂C₂B₁₀H₁₀)(1, Cp* = pentamethylcyclopentadienyl) reacts with N-1-naphthylpropargylamide to afford two 18e complexes (2) and (3). 2 is a 1 : 1 adduct containing a four-membered metallacycle. In 3 the alkyne is twofold inserted into one Co–S bond in a head–head mode. Reactions of 1 with 1-(2-furyl)-2-propyn-1-one and 1-ferrocenyl-2-propyn-1-one lead to two types of alkyne twofold inserted products (4)/(5) and (6)/(7), respectively. The reaction of 1 with phenylacetylene gives rise to the sole complex (8) of the same structural type as 3, 4 and 6, whereas the reaction of 1 with dimethyl acetylene dicarboxylate affords the sole 1 : 1 adduct (9). Complexes 2–9 have been characterized by IR, NMR, elemental analysis and mass spectrometry, and 3–9 have also been determined by single-crystal X-ray diffraction analysis.