Reactivity of 1‐Nitroso‐2‐naphthol Towards the Carbonyl Complexes XRe(CO) 5 (X = Cl, Br, I): Molecular Structures of cis ‐[η 2 ‐{ N , O ‐C 10 H 6 ON(O)}Re(CO) 4 ] and fac ‐[η 2 ‐{ N , O ‐C 10 H 6 ON(H)}Re(CO) 3 X]

The halogeno complexes (CO) 5 ReX ( 1a – c ) (X = Cl, Br, I) react with 1‐nitroso‐2‐naphthol C 10 H 6 N(O)OH ( 2 ) in refluxing CH 2 Cl 2 to give the substitution product cis ‐(CO) 4 Re{C 10 H 6 ON(O)} ( 3 ) via HX and CO elimination in good yield. Compound 3 is coordinated to the Re centre by the bidentate chelate ligand via the N‐atom of the nitroso and O‐atom of the naphtholato groups. The same reaction in refluxing toluene, however, gave no HX elimination but instead, the fac ‐(CO) 3 XRe{C 10 H 6 ON(H)} ( 4 – 6 ) complexes are formed, which contain the rare, N , O ‐chelating ligand 1,2‐naphthaquinone‐2‐imine. The nitroso function of 2 has been reduced to the imine function by an intermolecular redox process, which was confirmed by the detection of CO 2 generated during the reaction. The new compounds 3 – 6 have been characterised by their IR, 1 H and 13 C NMR, UV/Vis and mass spectra, as well as by X‐ray structure analyses. The Re I centres show a distorted octahedral coordination of the CO and X (in 4 – 6 ) ligands and the almost planar aromatic ( 3 ) or quinoid ( 4 – 6 ) N , O chelating ligands. (© Wiley‐VCH Verlag GmbH & Co. KgaA, 69451 Weinheim, Germany, 2005)