Synthesis, structural characterization and solution dynamics of osmium–rhodium mixed-metal cluster [Os4Rh(μ-H)4(CO)13(η2-NC5H4C2H2)]

Reaction of [Os3Rh(μ-H)3(CO)12] 1 with an excess amount of 2-vinylpyridine in refluxing CHCl3 afforded a new cluster, [Os4Rh(μ-H)4(CO)13(η2-NC5H4C2H2)] 2, in moderate yield. A pair of isomers 2a and 2b, which differ in configuration of the metallated vinylpyridine exist in the solution of 2. Through the variable temperature EXSY experiment, the activation barrier (ΔG≠) for the isomerisation of 2 was determined to be 89.8 kJ mol−1.