Synthesis, structure and magnetic properties of three CuII2LnIII complexes (Ln = Pr, Nd and Sm) with an unsymmetrical Schiff base ligand

Three heterometallic trinuclear complexes of general formula, [{(CH3CN)CuL}2(µ-NO3)2Ln(NO3)] [Ln = Pr (1), Nd (2) and Sm (3)] have been synthesized by reacting a neutral metalloligand [CuL], derived from a N2O2 donor unsymmetrically di-condensed di-Schiff base, H2L (where H2L = N-α-methylsalicylidene-N΄-salicylidene-1,3-propanediamine) with the respective lanthanide nitrates in 2:1 ratios. X-ray single-crystal structure reveals that these isomorphic complexes (1–3) possess C2-symmetric trinuclear units where two terminal metalloligands are coordinated to the central Ln(III) ion in transoid manner. In all three complexes, distorted tetradecahedron coordination geometry is formed around the Ln(III) ion by four μ2-phenoxido oxygen atoms from two (CuL) units and three chelating nitrato coligands. The two terminal Cu(II) ions possess distorted octahedral geometry. The dc magnetic susceptibilities and field dependent magnetization measurements of all three complexes reveal the occurrence of antiferromagnetic interactions between Cu(II) and Ln(III) ions.