Heterooctanuclear cluster complex formation with phosphine participation: Synthesis, structure, and magnetic properties of Co6Ru2(mp)(10)(PBu(3)(n))(6) (H(2)mp=2-mercaptophenol, PBu(3)(n)=tri-n-butylphosphine)

The reaction of CoCl2, RuCl3, Na-2(mp), and PBu(3)(n) (H(2)mp = 2-mercaptophenol, PBu(3)(n) = tri-n-butylphosphine) in ethanol in the molar ratio of 0.75:0.25:1:1 gave the complex Co6Ru2(mp)(10)(PBu(3)(n))(6). The heterooctanuclear complex consists of six cobalt and two ruthenium ions chelated to as well as bridged, by the 2-mercaptophenol ligands in a near-dimeric fashion with two mu(2)-OR groups bridging the two Co3Ru(mp)(5)(PBu(3)(n))(3) fragments without a crystallographic center of symmetry. Each fragment is formed by binding two of the Co(mp)(2)(PBu(3)(n)) structural units and one Co(mp) species to a central Ru(III) ion through the S donors of the five mp ligands, while the sixth coordination site of the octahedral Ru environment is completed by a phosphine ligand in the axial position. The Co6Ru2 moiety exhibits a zigzag assembly constructed by the mu(2)-O and mu(2)-S bridges of the bidentate 2-mercaptophenol ligands in a highly asymmetric fashion. The Co atoms are square pyramidally coordinated with apices that are occupied by the phosphine ligands or an oxygen atom from a mp(2-) ligand. Variable-temperature magnetic susceptibilities that were measured in the temperature range 300-1.6 K reveal that the spin cluster exhibits weak antiferromagnetic exchange interactions. A quantitative interpretation of the magnetic data was carried out by the irreducible tensor operator approach. Crystal data of the complex are as follows: triclinic space group <P(1)over bar>, a = 14.931(3) Angstrom, b = 23.195(5) Angstrom, c = 24.259(5) Angstrom, alpha = 74.91(3)degrees, beta = 74.83(3)degrees, gamma = 78.80(3)degrees, and Z = 2.