Synthesis, Structure, and Bonding of Novel Homodinuclear Cobalt and Nickel Borylene Complexes

• Published in: Chemistry : a European journal 2009-07, Vol.15 (29), p.7150-7155
• Main Authors: Braunschweig, Holger, Christ, Bastian, Colling-Hendelkens, Miriam, Forster, Melanie, Götz, Kathrin, Kaupp, Martin, Radacki, Krzysztof, Seeler, Fabian
• Format: Article
• Language: English
• Subjects: boron; bridging ligands; cobalt; ELF (electron localization function); nickel
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200900679

Herein we report for the first time full details on the synthesis and structural characterization of novel homodinuclear bridging cobalt and nickel borylene complexes containing bridging carbonyl ligands, an unusual coordination motif rarely before observed for homodinuclear borylene complexes. Furthermore, the homodinuclear nickel complex represents the first instance of a nickel borylene complex. Quantum chemical analyses of charge‐density topology, electron localization function (ELF) and natural charges indicate the absence of direct metal–metal bonds in both the cobalt and nickel systems, in contradiction with electron counting. The topology of the Laplacian of the electron density and of the ELF around the bridging boron atom is consistent with a bis‐metallo‐substituted borane situation for the dicobalt system, but with a three‐center‐bonding borylene for the dinickel complex. Building bridges: Photochemically induced borylene transfer to cobalt and nickel carbonyl complexes, [CpCo(CO)2] and [Cp2Ni2(CO)2] from [(OC)5MBN(SiMe3)2] (M=Cr, W) generates the first instances of homodinuclear bridged cobalt and nickel (see figure) borylene complexes featuring bridging CO ligands.