SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF OSMIUM CLUSTER COMPLEXESCONTAINING 2-PHENYLAZOPYRIDINE - CRYSTAL-STRUCTURES OF [OS-3(CO)(10)(NC5H4-N=N-C6H5)] AND [OS-3(CO)(10)(MU-H)(NC5H3-N=N(O)-C6H5)]

The reaction of [Os-3(CO)(10)(MeCN)(2)] with 2-phenylazopyridine (2-PA P) affords [Os-3(CO)(10)(NC5H4-N=N-C6H5)] (1), [Os-3(CO)(10)(mu-H) (NC 5H3-N=N(O)-C6H5)] (2) and a violet product 3, which is an isomer of 1. In 1, the 2-PAP moiety acts as the rarely observed six-electron donor . Cluster 2 contains an 'oxidized' 2-PAP moiety bonding in the usual o rtho-metallated mode of pyridine. Both clusters 1 and 2 have been full y characterized in solution by conventional spectroscopic methods and in the solid state by single crystal X-ray diffraction analysis. Cryst als of 1 are orthorhombic, space group P2(1)2(1)2(1), Z=4, with unit c ell dimensions a=9.123(1), b=17.217(2), c=16.168(2) Angstrom. Crystals of 2 are triclinic, space group P (1) over bar, Z=2, with unit cell d imensions a=9.308(2), b=11.250(2), c=12.934(2) Angstrom, alpha=77.23(1 ), beta=72.26(1), gamma=85.21(1)degrees.