PLATINUM(II) AMINOPHOSPHINE AND AMIDOPHOSPHINE PHOSPHINITE COMPLEXES - SYNTHESIS, STRUCTURE, AND USE IN CATALYTIC ASYMMETRIC HYDROFORMYLATION OF STYRENE - CRYSTAL-STRUCTURE OF PHINO)OXY)-METHYL)PYRROLIDINE]DICHLOROPLATINUM(II)

The optically active complexes [PtCl2(AMPP)] (2a-g; AMPP = aminophosph ine- and amidophosphine-phosphinite chelates derived from (S)-2-(hydro xymethyl)pyrrolidine and (S)-2-(hydroxymethyl)-5-pyrrolidinone) have b een prepared in high yields from the corresponding ligands (la-g) and Pt(COD)Cl-2 (COD = 1,5-cyclooctadiene). The structure of [PtCl2((S)-Ph ,Ph-ProNOP)] ([(S)- l-(diphenylphosphino)-2-(((diphenylphosphino) oxy) methyl)-pyrrolidine]dichloroplatinum(II), (2a)) has been determined. T he compound crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a 10.933(6) Angstrom, b = 15.646(10) Angstrom, c = 16.512(4) Ang strom, and Z = 4. The platinum atom has a cis square-planar coordinati on, with angular distortions due to steric factors. H-1, C-13{H-1}, an d P-31{H-1} NMR spectra of the complexes are also reported. Complexes 2a-g in combination with SnCl2 .2H(2)O catalyze the asymmetric hydrofo rmylation of styrene into (S)-2-phenylpropanal with quite slow catalyt ic rates (100 turnovers in 15-200 h). Various branched/normal (b/n) ra tios (0.4-0.8) and enantiomeric excess (ee) values (40-56%) were obtai ned. The results suggest that the catalytic activity of the [PtCl2(AMP P)] complexes is mainly affected by the aminophosphino moiety of the l igand (highest catalytic activities observed with N-diphenylphosphino substituents), whereas the enantioselectivity depends;on the nature of :the phosphinite part (best optical yields observed with (dicyclohexyl phosphino)oxy substituents).