Homodinuclear group 4 complexes

Homodinuclear Group 4 Complexes Metal-Metal Bonding or Not ... 

Homodinuclear group 4 metal complexes containing unsupported metal—metal bonds remain elusive despite many attempts to synthesize such species. In this sense, direct evidence for the M—M bonds as structurally determining features is still missing. 

Only a few examples of porphyrin compounds containing metal-metal interactions have been published. In addition to the conducting polymeric porphyrins described by Ibers and Hoffman < , only two classes of metal-metal bonded porphyrin complexes are known. These are porphyrins with donor-acceptor bonds and those with a-bonds. The latter series consists of both homodinuclear porphyrins such as in [(P)M]2 where H = Ru, and Os, and heterodinuclear derivatives such as in the (P)MIT(L) series where H In or T1 and M (L) is one of several different metalate groups. 

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