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DOI: 10.1039/A607440E (Paper) Reference Section for: J. Chem. Soc., Dalton Trans., 1997, 839-846

Lewis-base adducts of the diborane(4) compounds B2(1,2-E2C6H4)2 (E = O or S)

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William Clegg, Chaoyang Dai, Fiona J. Lawlor, Todd B. Marder, Paul Nguyen, Nicholas C. Norman, Nigel L. Pickett, William P. Power and Andrew J. Scott

Abstract

The reactivity of the diborane(4) compounds B2(1,2-E2C6H4)2 (E = O or S) have been studied with respect to their ability to co-ordinate Lewis bases, specifically 4-methylpyridine (mpy) and the phosphines PMe2Ph and PEt3. Four monoadducts have been characterised by X-ray crystallography, namely B2(1,2-O2C6H4)2 (mpy), B2(1,2-S2C6H4)2 (mpy), B2(1,2-S2C6H4)2 (PMe2Ph) and B2(1,2-S2C6H4)2 (PEt3), together with three bis adducts B2(1,2-O2C6H4)2 (mpy)2, B2(1,2-S2C6H4)2 (mpy)2 and B2(1,2-S2C6H4)2 (PMe2Ph)2. In the former set of compounds the one base is co-ordinated to one boron centre which adopts a tetrahedral geometry, the remaining boron being trigonal planar as in the structure of the parent compound. For the bis adducts each of the two borons is co-ordinated to a mpy or phosphine with both borons tetrahedral. Bond-length changes associated with ligand co-ordination are discussed. Multinuclear solution-state NMR studies have also been performed for solutions containing B2(1,2-O2C6H4)2 and mpy, B2(1,2-S2C6H4)2 and mpy and B2(1,2-S2C6H4)2 and PEt3. All of these studies indicate that intermolecular exchange of base between the parent compound, the mono- and the bis-adducts occurs in solution together with intramolecular exchange between the two boron centres in the monoadducts. The various rates of these processes, inasmuch as they have been determined accurately, are discussed and rationalised. The monoadducts B2(1,2-O/S2C6H4)2 (mpy) are nominally isoelectronic with the phenonium cation.

References

  1. J. A. Morrison, Chem. Rev., 1991, 91, 35 CrossRef CAS; A. G. Massey, Adv. Inorg. Chem. Radiochem., 1983, 26, 1 Search PubMed and refs. therein.
  2. R. T. Baker, P. Nguyen, T. B. Marder and S. A. Westcott, Angew. Chem., Int. Ed. Engl., 1995, 34, 1336 CrossRef CAS; P. Nguyen, G. Lesley, N. J. Taylor, T. B. Marder, N. L. Pickett, W. Clegg, M. R. J. Elsegood and N. C. Norman, Inorg. Chem., 1994, 33, 4623 CrossRef CAS; R. T. Baker, J. C. Calabrese, S. A. Westcott, P. Nguyen and T. B. Marder, J. Am. Chem. Soc., 1993, 115, 4367 CrossRef CAS.
  3. T. Ishiyama, N. Matsuda, N. Miyaura and A. Suzuki, J. Am. Chem. Soc., 1993, 115, 11 018 CrossRef CAS; T. Ishiyama, N. Matsuda, M. Murata, F. Ozawa, A. Suzuki and N. Miyaura, Organometallics, 1996, 15, 713 CrossRef; C. N. Iverson and M. R. Smith, J. Am. Chem. Soc., 1995, 117, 4403 CrossRef CAS; G. Lesley, P. Nguyen, N. J. Taylor, T. B. Marder, A. J. Scott, W. Clegg and N. C. Norman, Organometallics, 1996, 15, 5137 CrossRef; C. N. Iverson and M. R. Smith, Organometallics, 1996, 15, 5155 CrossRef CAS.
  4. T. Ishiyama, M. Murata and N. Miyaura, J. Org. Chem., 1995, 60, 7508 CrossRef CAS.
  5. (a) F. J. Lawlor, N. C. Norman, N. L. Pickett, E. G. Robins, P. Nguyen, G. Lesley, T. B. Marder, J. A. Ashmore and J. C. Green, Inorg. Chem., in the press Search PubMed; (b) W. Clegg, M. R. J. Elsegood, F. J. Lawlor, N. C. Norman, N. L. Pickett, E. G. Robins, A. J. Scott, P. Nguyen, N. J. Taylor and T. B. Marder, Inorg. Chem., in the press Search PubMed.
  6. H. Nöth, Z. Naturforsch., Teil B, 1984, 39, 1463 Search PubMed.
  7. P. Nguyen, C. Dai, N. J. Taylor, W. P. Power, T. B. Marder, N. L. Pickett and N. C. Norman, Inorg. Chem., 1995, 34, 4290 CrossRef CAS.
  8. W. van Dooren, A. W. Cordes and G. W. Hunt, Inorg. Chem., 1973, 12, 1686 CrossRef.
  9. Q. Johnson, J. Kane and R. Schaeffer, J. Am. Chem. Soc., 1970, 92, 7614 CrossRef.
  10. C. P. Brock, M. K. Das, R. P. Minton and K. Niedenzu, J. Am. Chem. Soc., 1988, 110, 817 CrossRef CAS.
  11. W. Haubold, J. Hrebicek and G. Z. Sawitzki, Z. Naturforsch., Teil B, 1984, 39, 1027 Search PubMed; W. Keller, L. G. Sneddon, W. Einholz and A. Gemmler, Chem. Ber., 1992, 125, 2343 CAS; W. Haubold, U. Kraatz and W. Einholz, Z. Anorg. Allg. Chem., 1991, 592, 35 CrossRef CAS.
  12. Mechanism in Organic Chemistry, eds. R. W. Alder, R. Baker and J. M. Brown, Wiley, New York, 1971 Search PubMed.
  13. G. M. Sheldrick, SHELXTL version 5, Siemens Analytical X-Ray Instruments, Madison, WI, 1994.
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