Synthesis, Characterization, and Redox Behavior of Mixed 1,3-Diyne Dicobalt/Triosmium and Dicobalt/Triruthenium Carbonyl Clusters

Abstract

The reaction between [Co 2 (μ−η 2 -HC⋮CC 2 SiMe 3 )(μ-dmpm)(CO) 4 ] ( 1 ) and [Os 3 (CO) 10 (MeCN) 2 ] gives rise to the formation of three new products: [Os 3 (μ-H){μ 3 -η 1:η 2;μ-η 2 -C 2 C 2 SiMe 3 [Co 2 (μ-dmpm)(CO) 4 ]}(CO) 9 ] ( 3 ), [Os 3 (μ-H){μ-η 1;μ-η 2 -C 2 C 2 SiMe 3 [Co 2 (μ-dmpm)(CO) 4 ]}(CO) 10 ] ( 4 ), and [Os 3 {μ 3 -η 1:η 2;μ-η 2 -HC 2 C 2 SiMe 3 [Co 2 (μ-dmpm)(CO) 4 ]}(μ-CO)(CO) 9 ] ( 5 ). These complexes adopt three different coordination modes: μ 3 -η 2 perpendicular, μ-η 1 edge-bridged, and μ 3 -η 2 parallel mode, respectively. When the reaction is carried out with [Ru 3 (CO) 12 ], only one product is obtained, [Ru 3 (μ-H){μ 3 -η 1:η 2;μ-η 2 -C 2 C 2 SiMe 3 [Co 2 (μ-dmpm)(CO) 4 ]}(CO) 9 ] ( 6 ), in which the triruthenium cluster is coordinated in a perpendicular mode. However, the reaction of [Co 2 (μ-η 2 -HC 2 (C⋮C) 2 C 2 SiMe 3 )(μ-dppm)(CO) 4 ] ( 2 ), stericaly more congested, with [Os 3 (CO) 10 (Me 3 CN) 2 ] yields only one product, the edge-bridged-coordinated [Os 3 (μ-H){μ-η 1;μ-η 2 -C 2 C 2 SiMe 3 [Co 2 (μ-dppm)(CO) 4 ]}(CO) 10 ] ( 7 ). [Os 3 (CO) 10 (MeCN) 2 ] reacts with HC⋮CSiMe 3, giving rise to the known parallel and perpendicular complexes and the new edge-bridged [Os 3 (μ-H){μ-η 1 -C 2 SiMe 3 (CO) 10 ]. All products were characterized by analytical and spectroscopic data (IR, 1 H, 13 C, and 31 P NMR, and MS). Crystals of 3, 6, and 7 suitable for single-crystal X-ray diffraction were grown, and the molecular structures of these compounds are discussed. A comparative electrochemical study of all these complexes is presented by means of the cyclic and square-wave voltammetry techniques.