Synthesis and Crystal Structure of a Tetranuclear Mn(III)-Ni(II) Heterometal Complex of <i>N</i>-(2-oxymethylphenyl)salicylideneimine

Abstract

Hetero-metal complexes assembled by bridging polydentate ligands have been of great interest in magnetochemistry.1–4 We have reported on the structure and magnetic properties of a hetero-metal tetranuclear complex, [MnNi(L1-H)2Cl(H2O)]2 (A) [H2L1-H = N-(2-oxymethylphenyl)salicylideneimine], which has a rather strong ferromagnetic interaction.5 The magnetic behaviors of A might depend on the Mn–O–Ni angles and axial ligands. While attempting to prepare a new complex with simple coordinating anions instead of chloride anions in A, we obtained single crystals of a new hetero-metal complex, [MnNi(L1-H)2(OAc)]2·2CH3OH (1). Here, we report on the synthesis and the crystal structure of 1. The Schiff-base ligand H2L1-H was obtained by a literature method.6 A mixture of H2L1-H (0.114 g, 0.5 mmol), manganese acetate tetrahydrate (0.122 g, 0.5 mmol), and triethylamine (0.102 g, 1.0 mmol) in dry methanol (4 ml) was stirred for 30 min. To the resulting dark-brown solution was added a dry methanol solution (2 ml) of nickel acetate tetrahydrate (0.127 g, 0.5 mmol). The mixture was stirred for 5 min. The obtained dark-brown solution was filtered, and the filtrate was allowed to stand overnight to give brown single crystals suitable for X-ray crystallography. [MnNi(L1-H)2(OAc)]2·2CH3OH (Yield, 0.050 g, 30.5%). C31H29MnN2NiO7 (655.22): calcd. C 55.27, H 4.44, N 4.19%; found C 55.30, H 4.64, N 4.16%. X-ray diffraction measurements were made on a Rigaku Saturn CCD diffractometer with graphite monochromated Mo Ka radiation at 113 K. The structure was solved by direct methods (SHELX2013) and expanded using Fourier techniques.7 The non-hydrogen atoms were refined anisotropically. All hydrogen atoms were located on the calculated positions, and refined using the riding model. The final cycle of a full-matrix least-squares refinement on F2 using SHELXL2013 was based on observed reflections and variable parameters, and converged with unweighted and weighted agreement factors of R and Rw. Details of the X-ray structure determination are listed in Table 1. Synthesis and Crystal Structure of a Tetranuclear Mn(III)-Ni(II) Heterometal Complex of N-(2-oxymethylphenyl)salicylideneimine