PD(II) AND PT(II) COMPLEXES WITH MIXED PHOSPHORUS-OXYGEN DONOR LIGANDS

A series of new complexes have been synthesized from reactions of [M(N CCH3)(4)][BF4](2) (M = Pd, Pt) with the mixed donor ligand,tris(2,4,6- trimethoxyphenyl) phosphine (TMPP). Reaction of [Pd(NCCH3)(4)][BF4](2) with two equivalents of TMPP in acetone produces the ether-phosphine complex [Pd(TMPP)(2)][BF4](2), 1. In this molecule the Pd atom is situ ated at the center of a pseudo-octahedron, with the phosphorus atoms i n a cis orientation. The complex was also characterized by infrared, e lectronic, and NMR spectroscopies as well as by cyclic voltammetry. Re action of [Pd(NCCH3)(4)][BF4](2) with four equivalents of TMPP in acet one yields the neutral phosphino-phenoxide compound Pd(TMPP-O)(2), 2, where TMPP-O is the demethylated form of TMPP. H-1 and P-31{H-1} NMR s tudies of 2 support the assignment of a solution structure that involv es free rotation of the uncoordinated phenyl rings of the TMPP ligands . Reaction of [Pt(NCCH3)(4)][BF4](2) with two equivalents of TMPP in a cetonitrile yields [PT(NCCH3)(2)(TMPP)(2)][BF4](2), 3. Structural and spectroscopic data for 3 indicate that free rotation of the arene ring s in solution is restricted due to steric influences of the two CH3CN co-ligands. Reaction of PtCl2(NCCH3)(2) with two equivalents of TMPP i n acetone or reaction of [Pt(NCCH3)(4)][BF4](2) with four equivalents of TMPP in acetone gives Pt(TMPP-O)(2), 4. Reaction of PtCl2(NCCH3)(2) with two equivalents of TMPP in tetrahydrofuran yields the neutral co mpound PtCl(TMPP)(TMPP-O), 5. Although suitable single crystals were n ot obtained, the structure of compound 5 was deduced from infrared and NMR spectroscopies to be a square planar molecule with one neutral TM PP ligand coordinated in an eta(1) fashion and a demethylated TMPP gro up bound as an eta(2)-P,O ligand where the phosphorus atoms are trans and the other two coordination sites are occupied by a phenoxide oxyge n and a Cl atom. (C) 1998 Elsevier Science Ltd. All rights reserved.