Novel Reactivity Mode of Hydroxamic Acids: A Metalla-Pinner Reaction

The reaction between the nitrile complex trans-[PtCl4(EtCN)2] and benzohydroxamic acids RC6H4C(O)NHOH (R = p-MeO, p-Me, H, p-Cl, o-HO) proceeds smoothly in CH2Cl2 at ∼45 °C for 2−3 h (sealed tube) or under focused 300 W microwave irradiation for ∼15 min at 50 °C giving, after workup, good yields of the imino complexes [PtCl4{NHC(Et)ONC(OH)(C6H4R)}2] which derived from a novel metalla-Pinner reaction. The complexes [PtCl4{NHC(Et)ONC(OH)(C6H4R)}2] were characterized by elemental analyses (C, H, N), FAB mass spectrometry, and IR and 1H and 13C{1H} spectroscopies, and [PtCl4{NHC(Et)ONC(OH)(Ph)}2] (as the bis-dimethyl sulfoxide solvate), by X-ray single-crystal diffraction. The latter disclosed its overall trans-configuration with the iminoacyl species in the hydroximic tautomeric form in E-configuration which is held by NH···N hydrogen bond between the imine NH atom and the hydroximic N atom.