Ring expansion of a Cp moiety upon CO insertion: Synthesis and characterization of [(η6-C6H5OCo)Co3(CO)9]

Reaction of [(CpV)(2)(B2H6)(2)], 1 (Cp - eta(5)-C5H5) with four equivalents of [Co-2(CO)(8)] or [Co-4(CO)(12)] in hexane at 70 degrees C leads to the isolation of the tetranuclear carbonyl cluster, [(eta(6)-C6H5OCo)Co-3(CO)(9)], 2 in modest yield. The geometry of 2 is similar to that of [Co-4(CO)(12)] where all the four Co atoms are arranged in a tetrahedral geometry. The apical cobalt atom in 2 is coordinated to C6H5O ring in a eta(6)-fashion and the other three cobalt atoms are each coordinated to three carbonyl ligands. Compound 2 has been characterized in solution by IR, H-1, C-13 NMR and mass spectrometry and the structural types were unequivocally established by crystallographic analysis. (C) 2010 Elsevier B. V. All rights reserved.