摘要:
NUMBER 17, 1966 605 React ion of Oxomolybdenum(v) Complexes with Hydrogen Sulphide and Thiols By R. N. JOWITT and P. C. H. MITCHELL (Department of Chemistry, The University, Reading, Berks.) As part of a general investigation of molybdenum- preparing thio-analogues of oxomolybdenum com- sulphur complexes, we have studied the reactions of plexes and to prepare complexes containing the compounds Mo,O,(xan), (xan = ethylxanthate molybdenum fully co-ordinated with sulphur. anion, EtOCS,-) and Mo,O,(dtp), [dtp = diethyl- The complexes Mo,O,(xan),l and M~,O,(dtp),~ dithiophosphate anion, (EtO) ,PS,-] with hydrogen were prepared by published methods and by new sulphide and thiols, RSH (R = Et, Ph, PhCH,). methods which will be reported elsewhere.s The The objects were to investigate the possibility of molecular structure of the xanthate complex hasCHEMICAL COMMUNICATIONS been determined by X-ray crystallography4 and we have evidence that the structure of the dithio- phosphate complex is similar.3 Hydrogen sulphide was passed into a solution of Mo,O,(xan), in a 1: 1 mixture of benzene and ethanol at room temperature yielding a black precipitate of empirical formula MoS,(xan) .Mole- cular-weight determinations were frustrated by the general insolubility of the compound. The mag- netic moment (0.5 B.M. at 20") is much less than the spin-only value for molybdenum(v) indicating that the compound is a dimer (or polymer). The infrared spectrum shows the absence of terminal and bridging oxygen atoms and of SH groups. Hydrogen sulphide and Mo,O,(dtp), similarly give the corresponding black dithiophosphate complex.We are not able to suggest structures for these complexes at this stage although they are certainly polymeric. We note that other complexes of similar empirical formulae have been described : MoS,(acetylacetonate) ,6 MoO,(acetylacetonate) .6 Reaction of the xanthate complex with thiols was carried out at room temperature by adding the complex to the pure liquid thiol under nitrogen. During 24 hr. the deep purple solutions darkened and deposited black crystals of empirical formulae MoS(RS) (xan) . Molecular-weight determinations were again frustrated by the low solubilities of the compounds. The magnetic moments (ca. 0-5 B.M. a t 20") were much below the spin-only value for molybdenum(1v) indicating polymerisation and/or spin-pairing in the distorted ligand field.Reaction of the dithiophosphate complex with thiols is quite different from that of the xanthate complex. The product is a pale pink oxomolyb- denum(1v) complex, MoO(dtp),. This compound has been fully characterised by elemental analysis, molecular-weight determination, infrared, ultra- violet and visible, and proton magnetic resonance spectroscopy. It is diamagnetic. We believe that this compound is the first authentic example of a square-pyramidal, low-spin, oxomolybdenum(1v) complex. It oxidises readily in air to Mo,O,(dtp),. Livingstone et al.7 claim to have prepared a similar compound from the reaction in air of K,MoCl, and di-isopropyl dithiophosphate but their description of the compound, the high reported molecular weight, and the method of preparation suggest to us that their material was a mixture of the molybdenum-(Iv) and - (v) complexes.The major organic products of the thiol reactions are disulphides, R,S,. They were isolated from the reaction mixtures and characterised by their melting points and infrared spectra. We suggest that in these reactions the thiols initially reduce the oxomolybdenum(v) dithiophosphate and xanthate complexes to oxomolybdenum(1v) complexes. With the xanthate complex (which is less stable with respect to ligand dissociation than the dithio- phosphate complex3) further reaction occurs involving dissociation and decomposition of a xanthate molecule (of which one sulphur atom is retained by the molybdenum) and co-ordination of a thiol anion: Mo2O3L, + 2RSH + ZMoOL, + R,S, + H,O MoOL, + RSH --f MoS(SR)L + H,O + decomposition products of L. Reactions of the type described here have not previously been reported. Our preliminary results with other oxomolybdenum complexes indicate that the reactions are general. (Received, July 26th, 1966; Corn. 542.) L. Malatesta, Guzzettu, 1939, 69, 408. G. Spengler and A. Weber, Chem. Ber., 1959, 92, 2163. R. N. Jowitt and P. C. H. Mitchell, to be published. A. B. Blake, F. A. Cotton, and J . S. Wood, J . Amer. Chem. SOC., 1964,86, 3024. British Petroleum Co. Ltd., Neth. Pat. 6,409,570, 1966. S. E. Livingstone, L. F. Lindoy, and T. N. Lockyer, Austral. J . Chem., 1965, 18, 1649. * G. T. Morgan and R. A. S. Castell, J . Chem. SOG., 1928, 2742.
ISSN:0009-241X
DOI:10.1039/C19660000605
出版商:RSC
年代:1966
数据来源: RSC