Transition metal complexes with neutral and deprotonated malonamide

Summary New complexes of the general formulae M(LH₂)₂Cl₂] (M = Mn, Fe, Co, Ni, Cu, Zn), Mn(LH₂)₂X₂] (X = Br, I), Cu(LH₂)₂Br₂], Ni(LH₂)₂X₂] (X = Br, NCS, ONO₂), Cu(LH₂)X₂]_n (X = Cl, Br), K₂NiL₂]·2H₂O and K₂-CuL₂]·H₂O, where LH₂ = malonamide, were isolated. The complexes were characterized by elemental analyses, X-ray powder patterns, magnetic susceptibilities and spectroscopic (variable-temperature ⁵⁷Fe-Mössbauer, e.s.r., u.v.-vis., i.r., far-i.r., Raman) studies. Monomeric trans pseudo-octahedral stereochemistries for the neutral 12 complexes and square planar structures of D _2h symmetry for the two ionic complexes are assigned in the solid state. Dimeric or polymeric five-coordinate structures are proposed for the 11 copper(II) compounds. LH₂ and L^2– behave as bidentate chelating ligands binding through oxygen and deprotonated nitrogen atoms, respectively. A detailed comparison of the studied complexes with the corresponding oxamide complexes is also presented.