Opposing magnetic communications in two dinuclear Ni(II) complexes: Ferromagnetic Ni-N-Ni and antiferromagnetic Ni-O-Ni moiety

Abstract

Two dinuclear Ni(II) complexes [Ni2(L)2(N3)2(H2O)]·2H2O (1) and [Ni2(L)2(NCS)2(H2O)] (2) [HL = 2-methoxy-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol] have been synthesized and characterized by single crystal X-ray crystallography and FT-IR spectroscopy. The complexes 1 and 2 are dinuclear and structurally close comparable with metals doubly bridged by a pseudohalide anion (μ1,1-azido and N,N-thiocyanato, respectively) and a μ-(phenoxido). The two HL ligands behave differently with N2O2 and N2O donor set towards the octahedral metal centres. Magnetic studies indicate an overall ferromagnetic interaction between nickel(II) centers in both the complexes. The experimental data can be simulated using the isotropic exchange Hamilton operator Ĥ = −2JS1S2 with following parameters J = +7.9(4) cm−1, g1,2 = 2.246(5), D1,2 = 2.35(10) cm−1 for complex 1 and J = +13.3(5) cm−1, g1,2 = 2.102(4), D1,2 = 4.18(12) cm−1, for complex 2. The structures of the complexes were theoretically optimized in their ground state and the experimental UV–vis electronic absorption spectral data have been compared with the theoretical results obtained from TD-DFT calculation.