Iminoacylation. 1. Addition of Ketoximes or Aldoximes to Platinum(IV)-Bound Organonitriles

The metal-mediated iminoacylation reaction of ketoximes or aldoximes upon treatment with the organonitrile platinum(IV) complexes trans-[PtCl4(RCN)2] proceeds under relatively mild conditions in acetonitrile (R = Me) or in chloroform (R = CH2Ph, Ph) to give trans-[PtCl4(NHC(R)ONCR1R2)2] (R1 = R2 = Me; R1R2 = C4H8, R1R2 = C5H10, R1R2 = (H)Ph, R1R2 = (H)C6H4(OH)-o; 1−14) in 90−95% yield. All these compounds were characterized by elemental analyses (C, H, N, Cl, Pt), FAB mass spectrometry, and IR and 1H, 13C{1H}, and 195Pt NMR spectroscopies. X-ray structure determinations of [PtCl4(NHC(Me)ONCMe2)2] (1) and [PtCl4{NHC(Me)ONC(C5H10)}2] (3) disclosed their overall trans-configuration and the amidine one-end rather than N,N-bidentate coordination mode of the N-donor ligands. The iminoacyl species are in E-conformation which is held by a rather weak N−H···N hydrogen bond between the amidine NH atom and the oxime nitrogen with the following observed distances and angles for 1 and [3]: N(1)···N(2), and N(1)−H, N(1)H···N(2) are 2.605 [2.592], 0.74 [0.71], and 2.20 [2.25] Å; N(1)−H···N(2) is 115° [111°]. No evidence of the Z-conformation in solution was obtained by NMR spectroscopy. Compounds trans-[PtCl4(NHC(R)ONCR1R2)2] are unexpectedly stable toward hydrolysis both in the solid state and in solutions.