PT(IV)-MEDIATED REDOX COUPLING OF 2-PROPANONE OXIMES IN CIS-[PT(ME2C=NOH)2CL4] - CRYSTAL-STRUCTURE OF [PT(N(=O)CME2ONCME2)CL2]

The complex cis-[Pt(Me2C=NOH)2Cl2], 1, isomerizes into trans-[Pt(Me2C=NOH)2Cl2], 2, upon heating in the solid phase at 140-degrees-C. Isomerization of 1 into 2 was also performed in acetonitrile or acetone solutions, containing catalytic amounts of Me2C=NOH; in the DMF-DMSO mixture, a 2-propanone oxime is displaced by DMSO in formation of cis-, 3, and trans-[Pt(Me2C=NOH)(DMSO)Cl2], 4. An excess of dimethyl sulfoxide results in the formation of the well-known complex cis-[Pt(DMSO)2Cl2]. Complex 4 has also been obtained from K[Pt(DMSO)Cl3] and Me2C=NOH in water, and complex 3 results from the solid-phase thermal isomerization of 4. The oxidation of 1 and 2 by molecular chlorine in CHCl3 or in MeNO2 produces cis-, 5, and trans-[Pt(Me2C=NOH)2Cl4], 6. Complex 6 is relatively stable in a water-acetone mixture, but complex 5 in this mixture at 20-25-degrees-C is converted within 3 h into a product containing an unusual redox coupling of 2-propanone oximes, [Pt(N(=O)CMe2ONCMe2)Cl2], 7. All the complexes were characterized by elemental analysis, IR spectra, and H-1, C-13, and Pt-191 NMR spectra; X-ray structure analysis was performed for 7. The compound crystallizes in the orthorhombic space group Pn2(1)a. The unit cell dimensions are a = 8.860 (3), b = 8.022 (2), c = 15.744 (4) angstrom, V = 1119.0 (6) angstrom3, Z = 4, and rho(calcd) = 2.43 g cm-1. Complex 1 is decomposed under X-ray irradiation, but crystallographic parameters have been determined (monoclinic, space group B2/b, a = 11.074 (3), b = 16.114 (4), c = 8.177 (1) angstrom, gamma = 111.76 (1)-degrees, V = 1355.0 (5) angstrom3, Z = 4).