A tetranuclear nickel(II) heterocubane complex of a bidentate N,O-hydroxymethyl-oxazoline ligand. Synthesis, characterization, magnetic measurements and DFT investigations.

Synthesis, structural, and magnetochemical characterization of the tetranuclear [Ni4O4] heterocubane cluster [NiCl(L1)(MeOH)]4,1, employing the bidentateN,O-ligand 2-hydroxymethyl-2-oxazoline,HL1, is reported. In the solid state, each nickel(II) is coordinated in a distorted octahedral environment, located on four corners of a [Ni4(μ3-O)4] cubane core motif. Measurements of the magnetic susceptibility in solution (Evans method) as well as in the solid state (magnetic susceptibility balance) gave values of 5.74 and 6.08 unpaired electrons, respectively, indicating a spin ground state ofS = 3. At maximum spin degeneracy (S = 4), eight unpaired electrons would be expected. Magnetic properties were further evaluated by SQUID measurements of1, confirming the spin ground state of1to beS = 3. The observed deviation is caused by antiferromagnetic coupling between the four Ni atoms. In addition, broken-symmetry DFT calculations confirmed an overlap of magnetic orbitals resulting in exchange coupling between the four nickel(II) ions of1. [ABSTRACT FROM AUTHOR]