Oxidative Addition of Carbon−Chloride Bonds to Rhodium(I) Complexes Containing Terdentate Nitrogen Ligands. X-ray Analyses of Rhodium(I) Chloride and Rhodium(III) Chloromethyl Complexes

Abstract

Potentially terdentate hemilabile 2,6-bis(R2-carbaldimino)pyridine and 2,6-bis(R2-ethylidyneimino)pyridine ligands (2,6-(C(R1)NR2)2C5H3N; R1 = H, R2 = i-Pr (1), t-Bu (2), cyclohexyl (3), p-anisyl (4); R1 = Me, R2 = p-anisyl (5), i-Pr (6)) have been used to prepare in high yields the novel and highly nucleophilic complexes [RhCl(2,6-(C(R1)NR2)2C5H3N)] (R1 = H, R2 = i-Pr (7), t-Bu (8), cyclohexyl (9), p-anisyl (10); R1 = Me, R2 = p-anisyl (11), i-Pr (12)) with [RhCl(alkene)2]2 (alkene = ethene, cyclooctene) as starting material. X-ray analyses of 7, 8, and 12 show severe steric interactions between the R2 group and the equatorial chloride atom, leading to out-of-plane bending of the chloride atom. The angle between the NNN plane and the RhCl axis is 5.34(16)° for 7, 11.73(11)° for 8, and 10.04(11)° for 12. Reaction of the Rh(I) complexes with CH2Cl2, CHCl3, benzyl chloride, and α,α-dichlorotoluene led to Rh(III) complexes by CCl bond rupture. The RhC bonds of the chloromethyl complexes [RhCl2(CH2Cl)(2,6-(C(...