CONVERSION OF HYDROXO-BRIDGED DIPLATINUM(II) COMPLEXES TO AMIDO-BRIDGED DIPLATINUM(II) COMPLEXES - X-RAY CRYSTAL-STRUCTURE OF TRANS-[PT2(MU-NH2)2(PH2PO)2(PPH2ME)2].CH3CH2OH

The amido-bridged diplatinum complexes cis- and trans-[Pt2(mu-NH2)2(POPh2)2(PMePh2)2] (1a,b) as a mixture of isomers has been made by treating [PtCl2(dppm-P,P')] with sodium hydroxide in aqueous ammonia or by treatment of [Pt2(mu-OH)2(POPh2)2(PMePh2)2] with aqueous ammonia. The mixture 1a,b has been characterized by H-1, P-31{H-1}, and N-15{H-1} NMR spectroscopy, and the X-ray crystal structure of the trans isomer 1a has been determined (monoclinic, C2/c; a = 25.576 (10) angstrom, b = 14.609 (4) angstrom, c = 26.988 (10) angstrom, beta = 102.73 (4)-degrees, R = 0.045 for 3478 observed reflections (I/sigma-(I) greater-than-or-equal-to 3.0)). The [Pt2N2] ring has a Pt-N bond of 2.114 (7) angstrom and a dihedral angle of 44 (1)-degrees between the Pt coordination planes. Addition of aqueous ammonia to [Pt2(mu-OH)2(PR3)4]2+ complexes gives the corresponding [Pt2(mu-NH2)2(PR3)4]2+ complexes.