Osmium-carbonyl complexes of naphthylazoimidazoles. Single crystal X-ray structure of [Os(H)(CO)(PPh3)(2)(alpha-NaiEt)](PF6) {alpha-NaiEt=1-ethyl-2-(naphthyl-alpha-azo)imidazole}

1-Alkyl-2-(naphthyl-alpha/beta-azo)imidazole (alpha-NaiR 1; beta-NaiR, 2) react with [Os(H)(Cl)(CO)(PPh3)(3)] in THF and synthesise [Os(H)-(CO)(PPh3)(2)(alpha/beta-NaiR)](PF6) (3, 4). The X-ray structure of [Os(H)(CO)(PPh3)(2)(alpha-NaiEt)](PF6) (3c) shows a distorted octahedral geometry. Other spectroscopic studies (IR, UV-Vis, NMR) support the stereochemistry of the complexes. Addition of Cl, in MeCN to 3 or 4 gives [Os(Cl)(CO)(alpha/beta-NaiR)(PPh3)(2)](PF6) (5, 6), which were characterized by spectroscopic studies. The redox properties of the complexes show Os(III)/Os(II), Os(IV)/Os(III) and azo reductions. (c) 2006 Elsevier Ltd. All rights reserved.