C,N-Chelated (2-Pyridylmethyl)rhodium(III) Complexes and a Novel Dinuclear Rhodium(III) Complex Containing a 2,6-Dimethylpyridine-α,α′-diyl Group as an η2(C,N) : η3(C,C′,N)-Bridging Ligand

Abstract

Abstract Oxidative-addition reactions of excess 2-(chloromethyl) and 2,6-bis(chloromethyl)pyridines with [RhCl(PPh3)3] in toluene at room temperature afforded (2-pyridylmethyl)- and {2-(6-chloromethyl)pyridylmethyl}rhodium(III) complexes, cis(PP)-[RhCl2{C5H3(6-R)N-2-CH2}(PPh3)2] (R = H, 1-cis; R = CH2Cl, 2-cis), respectively, which isomerized to the corresponding trans(PP) complexes at elevated temperature. In refluxing toluene, the reactions thus resulted in the trans(PP) complexes (R = H, 1-trans; R = CH2Cl, 2-trans) exclusively. A novel dinuclear rhodium(III) complex [Rh2Cl4{C5H3N-2,6-(CH2)2}(PPh3)2], in which the 2,6-dimethylpyridine-α,α′-diyl ligand is C,N-chelated to one rhodium atom and bound to the second one in an η3-pseudo-1-azaallylic fashion, was obtained by reactions of 2,6-bis(chloromethyl)pyridine with [RhCl(PPh3)3] (1 : 2 in mole) and of the 2-cis with [RhCl(PPh3)3] (1 : 1 in mole), both in refluxing toluene. These were characterized by 1H, 13C, and 31P NMR spectroscopy and mass spectrometry as well as an elemental analysis and a molecular-weight determination.