345 Journal of Organometallic Chemisrty, 403 (1991) 345-352 Elsevier Sequoia S.A., Lausanne JOM 21401 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Dimolybdenum oxo-imido complexes: crystal structures of [(MeC,H, 1 2M0202 ( ~-0)( P-NW 1 and [(MeC,H,) MoO( p-NPh)] 2 Joe Fletcher, Graeme Hogarth * and Derek A. Tocher Deparimeni of Chemiwy, University College London, 20 Gordon Street, London WCIH OAJ (UK) (Received August 7th. 1990) Abstract Oxidation of [(MeC,H,)Mo(CO),], zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF (1) by nitrobenzene in refluxing toluene affords three di- molybdenum oxo-imido complexes [(MeC,H,),MqO&-O)@-NPh)] (2). [(MeC,H,)MoO+NPh)]a (3). and [(MeC,H,),Mo@(NPh)@-O)(pNPh)] (4). Complexes 3 and 4 are isomers but do not interconvert. Complex 4 undergoes facile hydrolysis in hydrocarbon solvents giving 2 and aniline. The X-ray crystal structures of compounds 2 and 3 have been determined. Both structures display a rrans-disposition of methylcyclopentadienyl ligands and terminal 0x0 ligands. The Mo+-X), metallacore geometries are rigorously planar with the phenyl substituent(s) of the imido ligands being tilted slightly out of this plane. The MO-MO distances correspond to normal single bonds. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON Introduction The chemistry of transition metal complexes containing 0x0 and imido ligands continues to attract considerable attention [l]. Those containing both 0x0 and imido functionalities are of particular interest since they are potential reagents towards the oxyamination of unsaturated organic compounds. To date such oxyamination has only been achieved using osmium reagents such as OsO,(NR) [2]. We have recently synthesised a number of mixed oxo-imido complexes of molybdenum [3]. In this paper we describe the crystal structures of two of these complexes namely [(MeC,H,),Mo,o,(C1-o)(CL-NPh)l (2) and [(MeC,H,)MoO(p-NPh)], (3) the synthesis of a third new complex [(MeC,H,),Mo@(NPh)(p-O)@-NPh)] (4) and their interconversions. To date, attempts to utilise these complexes towards the oxyamination of alkynes has proved unsuccessful. Experimental General comments. All reactions were carried out under an N2 atmosphere using predried solvents unless otherwise stated. NMR spectra were recorded on a Varian VXR 400 spectrometer. IR spectra were recorded as KBr disks on a Perkin-Elmer 0022-328X/91/$03.50 0 1991 - Blsevier Sequoia S.A.