Intramolecular Cyclization of Butadiyne Functionalized Ligands coordinated to Triosmium‐Carbonyl Cluster

Abstract

AbstractReactions between diynes and [Os3(CO)11(CH3CN)] in the presence of water give rise to the formation of intriguing hydride triosmium clusters [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐RC2COHC≡CR}] (1a–1c) under mild conditions in high yields. When these allylic alcohol compounds 1a–1c are dissolved in dry polar and donor solvents, an intramolecular cyclization process takes place to give [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐RC2CH=COCR}] (2a–2c) in quantitative yield. The utilization of [Os3(CO)11(CH3CN)] as starting material together with the addition of water can replace the inconvenient use of [Os3(μ‐H)2(CO)10]. This method of synthesis provides a facile pathway for diyne cyclizations and has a clear advantage over those described to date in the literature. Additionally, the analogous cyclized mixed‐metal complex [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐FcC2CH=COCFc}] (2d) (Fc = ferrocenyl), was synthesized in order to carry out a comparative electrochemical study with the related compounds [Os3(CO)11(μ3‐FcC4Fc)] (I) and [Os3(CO)10(μ3‐FcC4Fc)] (II), which were previously reported by R. D. Adams.