Structural and magnetic properties of the binuclear [Co2{(OPPh2)2N}4] complex: Ferromagnetic coupling between the two S = 3/2 Co(II) ions

The reaction between Co(II) and the deprotonated tetraphenylimidodiphosphinic acid, [(OPPh2)2N]−, afforded a binuclear [Co2{(OPPh2)2N}4] complex, as revealed by X-ray crystallography. The structure contains two monometallic biconnective [(OPPh2)2N]− ligands, with an averaged Co−O bond length of 2.008 Å. The other two [(OPPh2)2N]− act as bimetallic triconnective ligands, forming two oxygen atom bridges, with the four Co−O(bridging) distances averaged at 2.155 Å, and the two Co−O(non-bridging) distances at 1.973 Å. The two approximately trigonal bipyramidal Co(II) ions are at a Co⋯Co distance of 3.301 Å. The analysis of the magnetic properties of [Co2{(OPPh2)2N}4] is consistent with an unusual ferromagnetic interaction, in a binuclear Co(II) system, between the two S = 3/2 Co(II) ions.