Metal-ylide complexes—II[1]: Reactions of some pyridinium ylides with selected salts of cobalt(II), copper(II) and palladium(II)

Abstract

Palladium(II)chloride affords simple coordination compounds with C 5 H 5 N + N - COMe and C 5 H 5 N + N - COEt but the derivative of N-(1-pyridinio)proprionamidate decomposes with evolution of HCl at the melting point. Both C 5 H 5 N + N - SO 2Ph (L) and C 5 H 5 N + N - COPh (L′) give coordination compounds with cobalt(II) and copper(II). The series [ML 4] (CLO 4) 2 (M = Co, Cu, Zn) is isomorphous and evidence is available from spectroscopic measurements (UV and ESR) to support the tetrahedral environment about the metal ions, although in the copper compound some distortion is present. [Co 2L 4X 2]X 2 (X = Cl, Br) and [Cu 2L 4Cl 2]Cl 2 are isomorphous, dimeric and have pseudo tetrahedral stereochemistry; [CuL 2Br 2] and [ZnL 2Cl 2 are isomorphous and tetrahedral. The spectroscopic data are discussed in such depth as the data derived from polycrystalline specimens permit. [CoL 4′] (ClO 4) 2 contains O-bonded C 5 H 5 N + N - COPh and exists in at least two polymorphic forms one of which is magnetically abnormal [Co 2-L 4′Cl 2]Cl 2 is dimeric and contains both O- and N-bonded ylide, [Co 2L 2X 4] are also dimers but contain only the O-bonded ylide. [CuL 3·5′] (ClO 4) 2, which contains copper(II) in a distorted 6-coordinate environment, is contrasted with the well defined [CuL 4] (ClO 4) 2 (above). N-(1-pyridinio)benzamidate undergoes NN bond rupture to give pyridine and phenylisocyanate at 190–200°C, but this decomposition temperature may be lowered by approx. 100°C in the presence of anhydrous copper(II) chloride which is shown to give an N-bonded complex with the ylide.