Unusual reactivity mode of coordinated oximes: Platinum(IV)-assisted ring closure by reaction with acetone

The platinum(II) complexes trans-[PtCl2(RR'C=NOH)(2)], where R = R' = Me, RR' = (CH2)(4) and (CH2)(5), react with m-chloroperoxybenzoic acid in Me(2)CO to give the platinum(IV) complexes [PtCl2(OCMe(2)ON=CRR')(2)] in 50-60% yields. The complexes [PtCl2(OCMe(2)ON=CRR')(2)] were characterized by elemental analysis, EI-MS, and IR and Raman spectroscopies; X-ray structure analyses were performed for both trans-[PtCl2(OCMe(2) ON=CC4H8)(2)] and trans-[PtCl2(OCMe(2)ON=CC5H10)(2)]. The former compound crystallizes in the triclinic space group <P(1)over bar > with a = 8.088(2) Angstrom, b = 8.327(2) Angstrom, c = 8.475(2) Angstrom, alpha = 103.54(3)degrees, beta = 102.15(3)degrees, gamma = 108.37(3)degrees, group C2/c with a = 12.5260(10) Angstrom. b = 9.3360(10) Angstrom, c = 18.699(2) Angstrom, beta = 98.328(10)degrees, V = 2163.7(4) Angstrom(3), Z = 4, and rho(calcd) = 1.862 g cm(-3). The structures of [PtCl2(OCMe(2)ON=CC4H8)(2)] and [PtCl2(OCMe(2)ON=CC5H10)(2)] show an octahedron of Pt where two Cl atoms and two chelate ligands are mutually trans, respectively.