Two new nickel(II) cubane compounds derived from pyridine-2-methoxide (Pym): {Ni_4(Pym)_4Cl_4(CH_3OH)_4} and {Ni_4(Pym)_4(N_3)_4(CH_3OH_3). Crystal structures and magnetic properties}

摘要

The pyridine-2-methoxide anion (Pym) allows the two new nickel(II) cubane compounds: {Ni_4(Pym)_4Cl_4(CH_3OH)_4} (1) and {Ni_4(Pym)_4(N_3)_4(CH_3OH)_4} (2), to be easily synthesized. 1 and 2 are structurally characterised. Complexes 1 and 2 crystallise in the tetragonal system. 1 and 2 have similar structures that consist of tetrameric cubane complexes with the alkoxide oxygen atoms of the pyridine-2-methoxide ligand and octahedrally co-ordinated nickel(II) atoms placed alternately at the corners of the cube. Magnetic susceptibility data, measured from 2 to 260 K show ferromagnetic behaviour for 1 and 2. These data were fitted by using the equation derived from the Hamiltonian H = -2J_1(S_1S_2 + S_3S_4)-2J_2(S_1S_3 + S_2S_3 + S_2S_4) including the Zero Field Splitting for the ground state S = 4, giving the parameters J_1 = 0.43. J_2 = 5.28, D = -0.47 cm~(-1), g = 2.11 for 1 and J_1 = 9.78, J_2 = 2.42, D = -0.01 cm~(-1), g = 2.21 for 2.