CONVERSION OF ACETONITRILE INTO ACETAMIDE IN THE COORDINATION SPHERESOF CIS-M(II)(AMINE)(2) AND TRANS-M(II)(AMINE)(2) (M=PT OR PD) - SOLUTION AND CRYSTAL STRUCTURAL STUDIES

The preparation and solution behaviour, of mono- and bis-acetonitrile complexes of cis-[Pt(NH3)(2)Cl-2], [Pt(en)Cl-2] (en = ethane-1,2-diami ne) and trans-[Pt(NH3)(2)Cl-2] has' been investigated. The nitrile Com plexes are hydrolysed to acetamidate, acetamidate-bridged and mixed ac etamidate-acetonitrile species. It is shown that an essential feature of monomeric acetamidate complexes with cis configuration is their ten dency to dimerize to dinuclear platinum compounds having bridging amid ate ligands. The resulting dimers undergo a facile head-to-tail to hea d-to-head rearrangement without any detectable. intermediate. Solution studies df the mononitrile complex trans-[Pt(NH3)(2)(MeCN)(OH)](+) at around neutral pH reveal the formation of trans-[Pt(NH3)(2)(MeCN)(NHC OMe)](+), suggesting a preceding ligand exchange. The reactions of pla tinum with MeCN are compared with those of the kinetically labile pall adium. The nitrile complex cis-[Pt(NH3)(2)(MeCN)Cl]ClO4 and the mixed- ligand complex trans-[Pt(NH3)(2)(MeCN)(NHCOMe)]ClO4 were characterized by X-ray crystallography: cis-[Pt(NH3)(2)-(MeCN)Cl]ClO4, monoclinic, space group P2(1)/c, a = 10.618(10), b = 10.625(8), c = 9.176(7) Angst rom, beta = 111.20(6)degrees, Z = 4; trans-[Pt(NH3)(2)(MeCN)(NHCOMe)]C lO4, monoclinic, space-group P2(1)/c, a = 8.601 (6), b = 19.508(19), c = 7.625(4) Angstrom, beta = 115.29(5)degrees, Z = 4.