cis-Dioxo-tungsten(VI) and -molybdenum(VI) complexes with N₂O₂ tetradentate ligands: synthesis, structure, electrochemistry and oxo-transfer properties

Abstract

Treatment of [WO₂Cl₂(dme)] with N₂O₂ tetradentate ligands [H₂Lⁿ (n = 1–7)] in the presence of 2 equivalents of triethylamine gave the corresponding dioxotungsten(VI) complexes [WO₂Lⁿ] (n = 1–7). The molybdenum counterparts [MoO₂Lⁿ] (n = 1–4) were prepared in good yield by treating ammonium molybdate tetrahydrate with the respective ligands and dilute hydrochloric acid. The molecular structures of four of these complexes, namely [WO₂Lⁿ] (n = 1, 5 or 6) and [MoO₂L²], as determined by single crystal X-ray analysis, revealed that the metal centre exhibits distorted octahedral co-ordination with cis-dioxo ligands. These high-valent oxo complexes are active toward oxygen atom transfer reactions and can catalyse the oxidation of benzoin with dmso. Their reactivity and electrochemical properties are discussed and compared.

References

1. J. A. McCleverty, in Encyclopedia of Inorganic Chemistry, ed. R. B. King, Wiley, Chichester, 1994, vol. 5, (a)pp. 2304–2330; (b)pp. 4240–4268.
2. K. J. Ivin and J. C. Mol, Olefin Metathesis and Metathesis Polymerization, Academic Press, San Diego, 1997; F. J. de la Mata and R. H. Grubbs, Organometallics, 1996, 15, 577; M. B. O'Donoghue, R. R. Schrock, A. M. LaPointe and W. M. Davis, Organometallics, 1996, 15, 1334; Y. Nakayama, N. Ikushima and A. Nakamura, Chem. Lett., 1997, 861.
3. R. A. Sheldon and J. K. Kochi, Metal-catalysed Oxidation of Organic Compounds, Academic Press, New York, 1981.
4. R. Hille, Chem. Rev., 1996, 96, 2757; D. Collison, C. D. Garner and J. A. Joule, Chem. Soc. Rev., 1996, 25.
5. M. J. Johnson, D. C. Rees and M. W. W. Adams, Chem. Rev., 1996, 96, 2817.
6. J. T. Spence, Coord. Chem. Rev., 1983, 48, 59; R. H. Holm, Coord. Chem. Rev., 1990, 100, 183; C. G. Young and A. G. Wedd, in Encyclopedia of Inorganic Chemistry, ed. R. B. King, Wiley, Chichester, 1994, vol. 8, pp. 2330–2346; A. G. Wedd, Coord. Chem. Rev., 1996, 154, 5.
7. (a) S.-b. Yu and R. H. Holm, Inorg. Chem., 1989, 28, 4385; (b) J. P. Donahue, C. Lorber, E. Nordlander and R. H. Holm, J. Am. Chem. Soc., 1998, 120, 3259; (c) G. C. Tucci, J. P. Donahue and R. H. Holm, Inorg. Chem., 1998, 37, 1602.
8. S. Lee, D. L. Staley, A. L. Rheingold and N. J. Cooper, Inorg. Chem., 1990, 29, 4391.
9. (a) N. Ueyama, H. Oku and A. Nakamura, J. Am. Chem. Soc., 1992, 114, 7310; (b) H. Oku, N. Ueyama and A. Nakamura, Inorg. Chem., 1995, 34, 3667; (c) H. Oku, N. Ueyama and A. Nakamura, Chem. Lett., 1995, 621; (d) H. Oku, N. Ueyama and A. Nakamura, Chem. Lett., 1996, 31; (e) H. Oku, N. Ueyama and A. Nakamura, Bull. Chem. Soc. Jpn., 1996, 69, 3139; (f) H. Oku, N. Ueyama and A. Nakamura, Chem. Lett., 1996, 1131.
10. (a) J. H. Enemark and C. G. Young, Adv. Inorg. Chem., 1993, 40, 1; (b) C. G. Young and A. G. Wedd, Chem. Commun., 1997, 1251 and refs. therein; (c) A. A. Eagle, G. N. George, E. R. T. Tiekink and C. G. Young, Inorg. Chem., 1997, 36, 472; (d) A. A. Eagle, E. R. T. Tiekink and C. G. Young, Inorg. Chem., 1997, 36, 6315.
11. A. Cervilla, E. Llopis, A. Ribera, A. Doménech and E. Sinn, J. Chem. Soc., Dalton Trans., 1994, 3511.
12. F. M. Hornung and W. Kaim, J. Chem. Soc., Faraday Trans., 1994, 90, 2909.
13. H. Kawaguchi and K. Tatsumi, J. Am. Chem. Soc., 1995, 117, 3885; H. Kawaguchi, K. Yamada, J.-P. Lang and K. Tatsumi, J. Am. Chem. Soc., 1997, 119, 10346.
14. S. Sarkar and S. K. Das, Proc. Indian Acad. Sci., 1992, 104, 533; S. K. Das, D. Biswas, R. Maiti and S. Sarkar, J. Am. Chem. Soc., 1996, 118, 1387; J. Yadav, S. K. Das and S. Sarkar, J. Am. Chem. Soc., 1997, 119, 4315.
15. C. J. Hinshaw, G. Peng, R. Singh, J. T. Spence, J. H. Enemark, M. Bruck, J. Kristofzski, S. L. Merbs, R. B. Ortega and P. A. Wexler, Inorg. Chem., 1989, 28, 4483.
16. R. Uma, R. Viswanathan, M. Palaniandavar and M. Lakshminarayanan, J. Chem. Soc., Dalton Trans., 1994, 1219.
17. K. Dreisch, C. Andersson and C. Stålhandske, Polyhedron, 1991, 10, 2417.
18. D. T. Sawyer, A. Sobkowiak, J. L. Roberts, jun., Electrochemistry for Chemists, Wiley, New York, 2nd edn., 1995, ch. 6.
19. J. Tanner and K. Krause, Rigaku J., 1994, 11, 4; 1990, 7, 28; K. L. Krause and G. N. Phillips, jun., J. Appl. Crystallogr., 1992, 25, 146; M. Sato, M. Yamamoto, K. Imada, Y. Katsube, N. Tanaka and T. Higashi, J. Appl. Crystallogr., 1992, 25, 348.
20. T. Higashi, ABSCOR, An empirical absorption correction based on Fourier coefficient fitting, Rigaku Corporation, Tokyo, 1995.
21. SHELXL PC v5.0 Reference Manual, Siemens Analytical X-ray Instruments, Inc., Madison, WI, 1995.
22. G. M. Sheldrick, SHELXL 93, Program for Crystal Structure Refinement, University of Göttingen, 1993; in Crystallographic Computing 6: A Window on Modern Crystallography, eds. H. D. Flack, L. Parkanyi and K. Simon, Oxford University Press, New York, 1993.
23. (a) K. Yamanouchi and S. Yamada, Inorg. Chim. Acta, 1974, 11, 223; (b) A. C. McDonell, S. G. Vasudevan, M. J. O'Connor and A. G. Wedd, Aust. J. Chem., 1985, 38, 1017; (c) A. A. Eagle, E. R. T. Tiekink and C. G. Young, J. Chem. Soc., Chem. Commun., 1991, 1746; (d) A. A. Eagle, C. G. Young and E. R. T. Tiekink, Organometallics, 1992, 11, 2934.
24. M. R. Maurya, M. N. Jayaswal, V. G. Puranik, P. Chakrabarti, S. Gopinathan and C. Gopinathan, Polyhedron, 1997, 16, 3977.
25. J. J. Cruywagen and E. A. Rohwer, J. Chem. Soc., Dalton Trans., 1995, 3433 and refs. therein; S. Djebbar-Sid and O. Benali-Baitich, Synth. React. Inorg. Metal-Org. Chem., 1993, 23, 1693.
26. B. J. Brisdon, Inorg. Chem., 1967, 6, 1791.
27. K. Dreisch, C. Andersson and C. Stålhandske, Polyhedron, 1992, 11, 2143; 1993, 12, 303, 1355; K. Dreisch, C. Andersson, M. Håkansson and S. Jagner, J. Chem. Soc., Dalton Trans., 1993, 1045.
28. W. P. Griffith, T. Y. Koh and D. J. Williams, J. Chem. Soc., Dalton Trans., 1993, 3459.
29. R. M. Silverstein, G. C. Bassler and T. C. Morrill, Spectrometric Identification of Organic Compounds, Wiley, New York, 5th edn., 1991, p. 127.
30. (a) J. M. Mayer, Inorg. Chem., 1988, 27, 3899; (b) W. A. Nugent and J. M. Mayer, Metal–Ligand Multiple Bonds, Wiley, New York, 1988; (c) A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G. Watson and R. Taylor, J. Chem. Soc., Dalton Trans., 1989, S1.
31. M. H. Chisholm, D. M. Hoffman and J. C. Huffman, Inorg. Chem., 1983, 22, 2903; M. H. Chisholm, K. Folting, J. A. Heppert, D. M. Hoffman and J. C. Huffman, J. Am. Chem. Soc., 1985, 107, 1234.
32. R. Greef, R. Peat, L. M. Peter, D. Pletcher and J. Robinson, Instrumental Methods in Electrochemistry, Ellis Horwood, New York, 1990, p. 188.
33. C. A. Rice, P. M. H. Kroneck and J. T. Spence, Inorg. Chem., 1981, 20, 1996; J. R. Bradbury, A. F. Masters, A. C. McDonell, A. A. Brunette, A. M. Bond and A. G. Wedd, J. Am. Chem. Soc., 1981, 103, 1959; G. Backes-Dahmann and K. Wieghardt, Inorg. Chem., 1985, 24, 4049.
34. R. H. Holm, Chem. Rev., 1987, 87, 1; M. L. Listemann, R. R. Schrock, J. C. Dewan and R. M. Kolodziej, Inorg. Chem., 1988, 27, 264; K. Piepgrass and M. T. Pope, J. Am. Chem. Soc., 1989, 111, 753; J. M. Mayer, in Advances in Transition Metal Coordination Chemistry, ed. C.-M. Che, JAI Press, New York, 1996, vol. 1, pp. 105–157 and refs. therein.