Synthesis of β-Imino Carbonyl Enolato Complexes by Reaction of Nickel(II), Palladium(II), and Copper(II) Acetates with the Enaminodiones (MeOCO)(RCO)CC(R‘)NH2 (R = Me, OMe; R‘ = Et, EtOCO)

Nickel(II), palladium(II), and copper(II) acetates undertake exchange reaction with the β-enaminodiones (MeOCO)(RCO)CC(R‘)NH2 (R = Me, OMe; R‘ = Et, EtOCO) in ethanol to give the neutral complexes [M((MeOCO)(RCO)CC(R‘)NH)2] (1−8) [R = Me, R‘ = Et: M = Ni (1), Pd (2a,b), Cu (3); R = Me, R‘ = EtOCO: M = Ni (4), Pd (5), Cu (6); R = MeO, R‘ = Et, M = Pd (7a,b); R = MeO, R‘ = EtOCO, M = Pd (8a,b)]. The trifunctional N,O,O ligands act in all cases as bidentate through the imino and one carbonyl group. Complexes 1−8 are all monomers with a square planar geometry. Nickel and palladium complexes show more than one form in the solid state. For example the palladium complex 2 has been synthesized in two forms a and b, which differ in the conformation of the methoxy carbonyl substituent of the chelate ring, while the third isomer or conformer is obtained by thermal treatment at 120 °C. Complexes 7 and 8 also exhibit two forms which differ in the degree of intermolecular hydrogen bonding. Both 7b and 8b crystallize in monoclinic unit cells [7b: space group P21/n, a = 11.963(2), b = 8.438(1), c = 19.637(2) Å, β = 94.2(1)°. 8b: P21/c, a = 10.698(2), b = 14.902(2), c = 13.918(2) Å, β = 95.2(1)°] containing four molecules linked by intermolecular hydrogen bonding [N−H···OC, 2.14−2.36 Å]. All complexes are thermally stable and volatile. Their mass spectra exhibit intense molecular ion peaks under EI mass conditions.