SYNTHESIS OF NEW PHOSPHINO AMINO ALCOHOL LIGANDS VIA ORTHO-ALKYLLITHIATION REACTIONS - VERSATILE COORDINATION BEHAVIOR TOWARD COPPER(I) ANDPALLADIUM(II)

2-[Methyl(2-methylphenyl)amino]ethanol undergoes an ortho-alkyllithiat ion reaction with n-butyllithium to lead to a new mixed benzyllithium- lithium alkoxide. This organolithium species reacts with PPh2Cl, with selective P-C bond formation, to afford the ligand (2-((diphenylphosph ino)methyl)phenyl)amino]ethanol L-1. The coordination of the ligand L- 1 to copper(I) leads to the complex [Cu(L-1)(2)](BF4), whose structure has been determined by an X-ray diffraction study. In the solid state , one of the ligands acts as a monodentate phosphine while the other a dopts a tridentate P,N,O coordination mode. A variable-temperature P-3 1 NMR study demonstrated the existence of an equilibrium between the t wo modes in solution, with a coalescence temperature of ca. 0 degrees C, indicating a double-hemilabile behavior for the nitrogen and the ox ygen functions. L-1 reacts with [Pd(Me)(Cl)(COD)] to give a dinuclear complex in which the ligand appears to behave as a bridging anionic P, O ligand. Such a complex could serve as a model for a key intermediate in the proposed mechanism for the homogeneous catalysis of the methox ycarbonylation of propyne by certain palladium(II) complexes containin g P,N ligands. L-1 can undergo a second ortho-alkylmetalation reaction with n-butyllithium which, after addition of PPh2Cl, provides the new ligand 2-{methyl[2-(bis( diphenylphosphino)methyl)phenyl]amino}ethano l (L-2) in high yield.