CONVERSION OF ACETONITRILE INTO ACETAMIDE IN THE COORDINATION SPHERES OF 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-diamine) and trans-[Pt(NH3)(2)Cl-2] has' been investigated. The nitrile Complexes are hydrolysed to acetamidate, acetamidate-bridged and mixed acetamidate-acetonitrile species. It is shown that an essential feature of monomeric acetamidate complexes with cis configuration is their tendency to dimerize to dinuclear platinum compounds having bridging amidate ligands. The resulting dimers undergo a facile head-to-tail to head-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)(NHCOMe)](+), suggesting a preceding ligand exchange. The reactions of platinum with MeCN are compared with those of the kinetically labile palladium. 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) Angstrom, beta = 111.20(6)degrees, Z = 4; trans-[Pt(NH3)(2)(MeCN)(NHCOMe)]ClO4, 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.