Synthesis of cis- and trans-ReOMe₂(bipy)Cl and related cationic oxorhenium(V) complexes

Abstract

The purpose of this study was to prepare high oxidation-state rhenium oxomethyl complexes, including cationic compounds, and test selected examples for olefin polymerization activity. Reaction of ReOMe₂(PMe₃)₂Cl with pyridine N-oxide and 2,2′-bipyridine (bipy) gave cis-ReOMe₂(bipy)Cl. Conversely, treatment of ReO(bipy)Cl₃ with AlMe₃ gave trans-ReOMe₂(bipy)Cl. The compound cis-ReOMe₂(bipy)Cl isomerized quantitatively to trans-ReOMe₂(bipy)Cl upon heating in benzene (ΔH  ^‡ = 29(3) kcal mol^–1, ΔS  ^‡ = 6(9) e.u.; at 79 °C, k_obs = 1.34(9) × 10^–2 min^–1 and t_1/2 = 52 min). Reaction of cis-ReOMe₂(bipy)Cl with AgX (X^– = PF₆^–, BF₄^–, or BPh₄^–) in acetonitrile gave the cationic acetonitrile adducts [ReOMe₂(bipy)(CH₃CN)]X. Treatment of the PF₆^– salt with PR₃ (PR₃ = PMe₃, P(OMe)₃, PMe₂Ph, P(n-Bu)₃, and PMePh₂) yielded the cationic PR₃ adducts cis-[ReOMe₂(bipy)(PR₃)][PF₆]. The BF₄^– salt of the PMe₃ adduct, cis-[ReOMe₂(bipy)(PMe₃)][BF₄], was prepared by the reaction of ReOMe₂(PMe₃)₂Cl with [Ag(CH₃CN)₂][BF₄] in acetonitrile followed by treatment with bipy in CH₂Cl₂. Single crystal X-ray crystallographic analyses of cis-ReOMe₂(bipy)Cl, trans-ReOMe₂(bipy)Cl, and cis-[ReOMe₂(bipy)(PMe₃)][BF₄] revealed that they have distorted octahedral structures. Analogs of cis-ReOMe₂(bipy)Cl, trans-ReOMe₂(bipy)Cl, and cis-[ReOMe₂(bipy)(PMe₃)][BF₄] were also prepared in which the bipy ligand was replaced with 1,10-phenanthroline (phen). An additional analog of cis-[ReOMe₂(bipy)(PMe₃)][BF₄] was prepared in which the bipy ligand was replaced by 4,4′-dimethyl-2,2′-bipyridine. In preliminary experiments, ethylene was polymerized using both cis-ReOMe₂(bipy)Cl and trans-ReOMe₂(bipy)Cl as catalyst precursors.

References

1. R. F. Jordan, Adv. Organomet. Chem., 1991, 32, 325.
2. M. Bochmann, J. Chem. Soc., Dalton Trans., 1996, 255.
3. T. C. Chung, Macromolecules, 1988, 21, 865.
4. T. C. Chung and D. Rhubright, Macromolecules, 1993, 26, 3019.
5. M. R. Kesti, G. W. Coates and R. M. Waymouth, J. Am. Chem. Soc., 1992, 114, 9679.
6. R. R. Schrock, Polyhedron, 1995, 14, 3177.
7. R. Toreki and R. R. Schrock, J. Am. Chem. Soc., 1990, 112, 2448.
8. R. Toreki, G. A. Vaughan and R. R. Schrock, J. Am. Chem. Soc., 1993, 115, 127.
9. J. C. Mol, J. Mol. Catal., 1982, 15, 35.
10. C. M. Killian, D. J. Temple, L. K. Johnson and M. Brookhart, J. Am. Chem. Soc., 1996, 118, 11664.
11. L. K. Johnson, S. Mecking and M. Brookhart, J. Am. Chem. Soc., 1996, 118, 267.
12. L. K. Johnson, C. M. Killian and M. Brookhart, J. Am. Chem. Soc., 1995, 117, 6414.
13. B. L. Small, M. Brookhart and A. M. A. Bennett, J. Am. Chem. Soc., 1998, 120, 4049.
14. B. L. Small and M. Brookhart, J. Am. Chem. Soc., 1998, 120, 7143.
15. G. J. P. Britovsek, V. C. Gibson, B. S. Kimberley, P. J. Maddox, S. J. McTavish, G. A. Solan, A. J. P. White and D. J. Williams, Chem. Commun., 1998, 849.
16. D. M. Hoffman, in Comprehensive Organometallic Chemistry II, ed. E. W. Abel, F. G. A. Stone and G. Wilkinson, Pergamon, New York, 1995, vol. 6, ch. 10.
17. D. M. Hoffman and D. A. Wierda, Polyhedron, 1989, 8, 959.
18. D. M. Hoffman, J. C. Huffman, D. Lappas and D. A. Wierda, Organometallics, 1993, 12, 4312.
19. S. Cai, D. M. Hoffman, J. C. Huffman, D. Lappas and H. G. Woo, Organometallics, 1987, 6, 2273.
20. C. C. Romao, F. E. Kuhn and W. A. Herrmann, Chem. Rev., 1997, 97, 3197.
21. A. M. Arif, T. A. Bright and R. A. Jones, J. Coord. Chem., 1987, 16, 45.
22. M. F. N. N. Carvalho, A. J. L. Pomberiro, D. L. Hughes and R. L. Richards, J. Organomet. Chem., 1987, 335, C23.
23. T. I. A. Gerber, J. Bruwer, G. Bandoli, J. Perils and J. G. H. Preez, J. Chem. Soc., Dalton Trans., 1995, 2189.
24. J. C. Bryan, R. E. Stenkamp, T. H. Tulip and J. M. Mayer, Inorg. Chem., 1987, 26, 2283.
25. T. Yamamoto, A. Yamamoto and S. Ikeda, Bull. Chem. Soc. Jpn., 1972, 45, 1104.
26. H. A. Tolman, Chem. Rev., 1977, 77, 313.
27. C. Bolzati, F. Tisato, F. Refosco, G. Bandoli and A. Dolmella, Inorg. Chem., 1996, 35, 6221.
28. A. Anderson, H. G. Cordes, J. Herwig, W. Kaminsky, A. Merk, R. Mottweiler, J. H. Sinn and H. J. Vollmer, Angew. Chem., Int. Ed. Engl., 1976, 15, 630.
29. A. Ravve, Principles of Polymer Chemistry, Plenum, New York, 1995.
30. P. J. T. Tait and N. D. Watkins, in Comprehensive Polymer Science, ed. S. G. Allen and J. C. Bevington, Pergamon, New York, 1989, vol. 4, ch. 2.
31. E. W. Fawcett, O. R. Gibson, M. W. Perrin, J. G. Paton and E. G. Williams, Br. Pat., 571 690, 1937.
32. J. C. Miller and J. N. Miller, Statistics for Analytical Chemistry, Wiley, New York, 1988, ch. IV.