The mixed-metal carbonyl cluster anion [Os 3Ir(CO) 13] −: synthesis, structure, reactivity and catalytic activity in the carbonylation of methanol

Abstract

The cluster anion [Os 3Ir(CO) 13] − ( 1) was prepared in 50% yield by reaction of Os 3(CO) 12 with [Ir(CO) 4] −. The single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt shows 1 to consist of a tetrahedral metal core with one of the 13 carbonyl ligands being bridging. Protonation of 1 led to the neutral cluster HOs 3Ir(CO) 13 ( 2), whereas the hydrogenation gave the cluster anion [H 2Os 3Ir(CO) 12] − ( 3). The catalytic activity of 1 for the carbonylation of methanol was studied. Using CH 3I as co-catalyst, catalytic turnover numbers up to 1800 were obtained (140°C, 30 bar) within 14 h.