Metal-metal bonded compounds. V. Compounds with Ir (Rh)-Hg bonds containing a bridging and a chelating triazenido group which interconvert intramolecularly

Abstract

The compounds [(Diene)(RN{3}R'){2}MHgCl]{2} (M = Ir; Diene = COD; R = CH{3}, C{2}H{5}; R' = p-CH{3}C{6}H{4} and M = Rh; Diene = COD, NOR; R = CH{3}, C{2}H{5}, p-CH{3}-C{6}H{4}; R' = p-CH{3}C{6}H{4} have been prepared by reaction of [(Diene)MCl]{2} with [Hg(RN{3}R'){2}] and by reaction of [{(Diene)MCl}(HgCl{2})]{2} with [Ag(RN{3}R')]{n}. A crystal structures study of [(COD)(EpTT){2}IrHgCl]{2} shows that the complex is dimeric with two chloride atoms bridging the two mercury atoms. In each half of the dimer there is one triazenido group chelating to the Ir atom and one triazenido group bridging an iridium-mercury bond (2.62 @9). The complexes are monomeric in solution but have otherwise a configuration around the Ir(Rh)atom similar to that in the solid state. Fluxional processes, which occur for M = Rh but not for M = Ir, involve a novel dynamic process consisting of interchange of the bridging and chelating triazenido groups via monodentate intermediates.