Hydrogen-bonding patterns in oxime/oximato platinum(II) species providing the formation of one-dimensional chains, two-dimensional networks, and cages

Heating cis-[PtCl2(Me2C=OH)(2)] in molten 2-propanone oxime affords the cationic complex [PtCl(Me2C=NOH)(3)]Cl. This compound reacts with 1 equiv of NaOH to give the neutral complex cis-[PtCl(Me2C=NO)(Me2C=NOH)(2)] (1). Further, the reaction of [PtCl(Me2C=NOH)(3)]Cl with 2 equiv of AgNO3 and successive addition of excess oxime and NaSbF6 afford the chloride-free cationic complex [Pt(Me2C=NO)(Me2C=NOH)3](SbF6). When a solution of NaOH, instead of NaSbF6, was added to the reaction mixture, the neutral compound [Pt(Me2C=NO)(2)(Me2C=NOH)(2)] . 2H(2)O (2) was isolated. The homoleptic complex [Pt(Me2C=NOH)(4)]Cl-2 (3) was prepared both by addition of excess HCl to [Pt(Me2C=NO)(2)(Me2C=NOH)(2)] (87% yield) and by prolonged heating of [PtCl(Me2C=NOH)(3)]Cl and excess 2-propanone oxime, although in the latter case the conversion of the starting complex did not exceed 5-10%. 1-3 were characterized by X-ray diffraction. All three compounds display interesting hydrogen-bonding modes. In 1, two crystallographically independent molecules of cis-[PtCl(Me2C=NO)(Me2C=NOH)(2)] form, the repeat unit for a novel type of self-assembly that produces infinite one-dimensional polymeric chains held by strong H-bonds. 2, as compared to vic-dioxime Pt(II) complexes, displays stronger intramolecular hydrogen bonds and shows the absence of columnar stacking. In addition, the solvation H2O molecules connect the Pt(n) building elements by intermolecular H-bonds to form a layered two-dimensional network. In 3, the counterion is involved in (mu(4)-Cl-).cis-[(... H-O-)(2)(... H-CH2-)(2)] hydrogen bonding, thus forming the caged complex. Another interesting structural feature of 3 is the interaction between methyl hydrogens and platinum.