Facile synthesis and structural properties of (diamine)tetracarboxylatoplatinum(IV) complexes

Abstract

(Diamine)tetracarboxylatoplatinum(IV) complexes, A(2)Pt(OOCR)(4) (A(2) = trans-(+/-)-1,2-diaminocyclohexane (dach), 2,2-dimethyl-1,3-propanediamine (dmpda), ethylenediamine (en), 2 NH3, 2 cyclopropylamine (cpa); R = CH3, C2H5), have been facilely synthesized by reacting (diamine)tetrahydroxoplatinum(Iv) with carboxylic anhydrides in dichloromethane, and their structural properties were examined by X-ray analysis and H-1 NMR spectroscopy. The reactant (dach)Pt(OH)(4) crystallizes in the triclinic space group P (1) over bar (No. 2) with two molecules in an asymmetric unit and the local geometry around the platinum(IV) atom is a regular octahedron, but the carboxylated product (dach)Pt(O2CCH3)(4) crystallizes in monoclinic space group P2(1)/c (No. 14) and the platinum(IV) atom is in a distorted octahedral environment. The most interesting structural aspect of the title complexes is that the equatorial Pt(IV)-carboxylate bonds are slightly longer than the axial ones, probably due to the difference in trans influence of the nitrogen and oxygen donating atoms. The H-1 NMR spectra also show that the axial and equatorial acetate groups are not equivalent. (C) 1999 Elsevier Science S.A. All rights reserved.