RHODIUM AND PALLADIUM COMPLEXES OF A 3,5-LUTIDINE-BASED PHOSPHINE LIGAND

The chelating bis(phosphine) 3,5-bis((diphenylphosphino)methyl)pyridin e (dppLH, 9) was synthesized from 3,5-lutidine by radical chlorination , followed by reaction with LiPPh(2). Compound 9 was used to prepare P h and Pd complexes. The three complexes (dppL)RhL (L = (PPr3)-Pr-r (11 ), PPh(3) (12), and CO (13)) are obtained from Rh-2-Cl-2(COE)(4) (COE = cyclooctene) and HRh(PPh(3))(4). Compound 9 reacts with (PhCN)(2)PdC l2 to form the Pd(II) complex (dppL)PdCl (14). All complexes are fully characterized. The X-ray crystal structure of 11 has been determined. It crystallizes in the triclinic space group <P(1)over bar> (No. 2) w ith a = 12.242(3) Angstrom, b = 14.384(3) Angstrom, c = 11.653(2) Angs trom, alpha = 98.61(2)degrees, beta = 96.88(2)degrees, gamma = 106.38( 2)degrees, V = 2023.3(8) Angstrom(3), Z = 2, R = 0.045, and R(W) = 0.0 52. The Rh(I) center is in a square-planar coordination environment wi th the two phosphines of the dppL Ligand framework being trans to each other. The pyridine nitrogen is unobstructed and available for bindin g to other metal centers. Compound 14 acts as a metalloligand toward P d(II) centers to form the trinuclear complex {(dppL)PdCl}2PdCl2 (16). N-coordination of a metal moiety and of a Lewis acid influences the el ectronic properties on the Pd center.