Transition metal complexes of 1,3-dihydrobenzo[c]tellurophene: synthesis, spectroscopy and crystal structures

Abstract

Reaction of 1,3-dihydrobenzo[c]tellurophene (L) with [Cu(MeCN)₄]PF₆ or AgBF₄ yielded [CuL₄]PF₆ and [AgL₄]BF₄ respectively, which adopt distorted tetrahedral structures at the metal centre, with the tellurophene ligated via a Te-based lone pair, Cu–Te 2.587(2)–2.596(2) Å; Ag–Te 2.7676(7)–2.8104(8) Å. With palladium(II) and platinum(II) chlorides the neutral species [PdCl₂L₂] and [PtCl₂L₂] were formed readily. Infrared, ¹²⁵Te-{¹H} and ¹⁹⁵Pt NMR spectroscopic studies showed that the former is the trans isomer, whereas the latter is the cis isomer. The ¹²⁵Te-{¹H} NMR spectra showed that in solution [RhCl₃L₃] is a mixture of mer and fac isomers in approximately 3∶2 ratio, whereas RuCl₃ reacted with L in EtOH and hypophosphorous acid to give trans-[RuCl₂L₄] exclusively. The carbonyl derivatives fac-[MnCl(CO)₃L₂], [Mo(CO)₅L], cis-[Mo(CO)₄L₂] and fac-[Mo(CO)₃L₃] have also been characterised through IR spectroscopy, ¹H, ¹³C-{¹H}, ⁵⁵Mn, ⁹⁵Mo and ¹²⁵Te-{¹H} NMR spectroscopy. For the molybdenum species δ(⁹⁵Mo) and δ(¹²⁵Te-{¹H}) shift to high frequency with increasing substitution of the carbonyl ligands. The crystal structure of [Mo(CO)₄L₂] confirms the cis geometry and shows the Mo–CO bond lengths trans to L are about 0.10 Å shorter than those trans to CO. The ¹H NMR spectra of these complexes typically reveal AB quartets for the methylene protons, indicative of co-ordination through a Te-based lone pair in each case. The ¹²⁵Te-{¹H} NMR studies reveal a high frequency co-ordination shift except for the copper and silver species which show δ(¹²⁵Te-{¹H}) to low frequency of that for free L.

References

1. R. F. Ziolo and W. H. H. Gunther, J. Organomet. Chem., 1978, 146, 245.
2. A. Z. Al-Rubaie, W. R. McWhinnie, P. Granger and S. Chapelle, J. Organomet. Chem., 1982, 234, 287.
3. K. Badyal, W. R. McWhinnie, H. L. Chen and T. A. Hamor, J. Chem. Soc., Dalton Trans., 1997, 1579.
4. K. Badyal, W. R. McWhinnie, J. Homer and M. C. Perry, J. Organomet. Chem., 1998, 555, 279.
5. H. Higuchi, T. Otsubo, F. Ogura, H. Yamaguchi, Y. Sahata and S. Misumi, Bull. Chem. Soc. Jpn., 1982, 55, 182.
6. J. R. Black, N. R. Champness, W. Levason and G. Reid, J. Chem. Soc., Dalton Trans., 1995, 3439; Inorg. Chem., 1996, 35, 1820, 4432.
7. J. R. Black and W. Levason, J. Chem. Soc., Dalton Trans., 1994, 3225.
8. W.-F. Liaw, C.-H. Lai, S.-J. Chiou, Y.-C. Horng, C.-C. Chou, M.-C. Liaw, G.-S. Lee and S.-M. Peng, Inorg. Chem., 1995, 34, 3755.
9. T. Kemmitt, W. Levason, R. D. Oldroyd and M. Webster, Polyhedron, 1992, 11, 2165.
10. T. Kemmitt and W. Levason, Inorg. Chem., 1990, 29, 731.
11. T. Kemmitt, W. Levason and M. Webster, Inorg. Chem., 1989, 28, 692.
12. N. R. Champness, W. Levason, S. R. Preece and M. Webster, Polyhedron, 1994, 13, 881.
13. J. Connolly, G. W. Goodban, G. Reid and A. M. Z. Slawin, J. Chem. Soc., Dalton Trans., 1998, 2225; J. Connolly, M. K. Davies and G. Reid, J. Chem. Soc., Dalton Trans., submitted; W. Levason, S. D. Orchard and G. Reid, unpublished work.
14. O. Lutz, A. Nolle and P. Kronek, Z. Naturforsch., Teil A, 1976, 31, 454.
15. F. A. Cotton, D. J. Darensbourg, S. Klein and B. W. S. Kilthammer, Inorg. Chem., 1982, 21, 2661.
16. PATTY, The DIRDIF Program System, P. T. Beurskens, G. Admiraal, G. Beurskens, W. P. Bosman, S. Garcia-Granda, R. O. Gould, J. M. M. Smits and C. Smykalla. Technical Report of the Crystallography Laboratory, University of Nijmegen, 1992.
17. TEXSAN, Crystal Structure Analysis Package, Molecular Structure Corporation, The Woodlands, TX, 1995.
18. N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 1983, 39, 158.