Synthesis, spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of bis(aminoalkyl)-oxamides (= LH2) including the crystal structure of Cu2L(NO3)2

The synthesis of the NiII, PdII and CuII complexes of N, N′-bis(aminoalkyl)oxamides (LH2) is described and structures are proposed on the basis of their physical and spectroscopic properties. With NiII and PdII only one complex is formed with general formula NiL or PdL, characterised by coordination through two deprotonated amide N-atoms and two terminal NH2 groups. With CuII it proved possible to obtain three structurally different compounds, depending on the pH, with general formulae Cu(LH2)X2, Cu2(L)X2 and CuL in which X=Cl, Br or NO3. The structure of [Cu2(C8O2N4H16](NO3)2 was solved by means ofx-ray diffraction; Mr=451.33, monoclinic, space group P21/n, a=9.503(4), b=7.614(1), c=10.407(3) A, β=98.43(3)°, V=744.3(7)A3, Z=2, Dx=1.202 g cm−3, μ=1.33 cm−1, γ(MoKα)=0.71073 A, F(000)=520, room temperature, R=0.043, wR=0.047 for 1080 observed [I>-3σ(I)] not systematically absent reflections out of 1423 measurements and 137 variables. The compound has a conformational chair/boat disorder with 82% in the more stable chair form.