Homo and heterometallic rhomb-like Ni4 and Mn2Ni2 complexes.

Abstract: Two new polynuclear complexes with hydroxyl-rich Schiff base ligand 3-[(2-Hydroxy-benzylidene)-amino]-propane-1,2-diol (H3L), namely [NiII 2(HL)(H2L)(SCN)]2·DMF (1) and [MnIII 2NiII 2(HL)2(L)2] (2) have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, FTIR, UV–Vis spectroscopy and variable temperature magnetic susceptibility measurements. The X-ray refinements reveal that both compounds present defective rhomb-like dicubane central cores (Ni4 in 1 and Mn2Ni2 in 2). Magnetic susceptibility measurements indicate the presence of overall antiferromagnetic exchange interactions in 1 along the side connected by a N and O atoms (J 1 =−43.6cm−1) and along the short diagonal of the rhomb (J 3 =−3.9cm−1) and a weak ferromagnetic coupling (J 2 =+5.8cm−1) along the side of the rhomb connected by a double O-bridge. In 2 the three exchange interactions are negative (J 1 = J 2 =−0.3cm−1 and J 3 =−0.7cm−1). A magneto-structural correlation with the ratio between the Ni–O–Mn bond angle and the Mn–O bond length is also discussed for double O-bridged Mn–Ni pairs. [Copyright &y& Elsevier]