Complex catalysis 55 - Oxidative addition reactions of organorhodium(I) complexes containing the tridentate ligand 2,6-bis(diphenylphosphanylmethyl)pyridine [Rh(PNP)R] (R = CH3, C6H5) with iodine and methyl iodide and investigation of the reductive elimination

As part of studies aimed at delineating the mechanism of the rhodium comple x-catalyzed hydroamination of olefins, the model complexes [Rh(PNP)R] (R=CH 3 1a, C6H5 1b) have been investigated with regard to oxidative addition rea ctions. The reaction of I-2 with 1a leads to both trans- and cis-[Rh(PNP)(C H3)I-2] (trans: 2a, cis: 2a '), whereas with 1b only trans-[Rh(PNP)(C6H5)I- 2] (2b) is obtained. The rhodium(III) complexes [Rh(PNP)(CH3)RI] (3a,b) are formed by the reaction of 1a,b with CH3I. The new organo- rhodium(III) com plexes 2a,b and 3a,b have been characterized by P-31-, H-1-, and C-13-NMR s pectrometry, as well as by EI mass spectrometry. The hydrocarbons RCH3 are reductively eliminated in the reaction of [Rh(PNP)(CH,)RI] (3a,b) with TlBF 4 in acetone, while the reaction of 3b and TlBF4 in THF/CH3CN leads to the stable rhodium(III) complex [Rh(PNP)(CH3)(C6H5)(CH3CN)]BF4 (5). Complex 5 h as been characterized by X-ray crystallography.