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SUMMARY:Coordination and activation of aminoboranes - Dr Simon Aldridge\, 
 University of Oxford
DTSTART:20111020T130000Z
DTEND:20111020T140000Z
UID:TALK32435@talks.cam.ac.uk
CONTACT:Sian Bunnage
DESCRIPTION:The activation of BH bonds by late transition metal centres pl
 ays a central role in a number of key synthetic methodologies\, including 
 metal-catalysed hydroboration and alkane/arene C-H functionalization/boryl
 ation protocols. Within this sphere\, aminoboranes\, H2BNRR'\, are the sub
 ject of significant additional interest not only as the first-formed produ
 cts in the dehydrogenation of a class of BN-containing hydrogen storage ma
 terials\, but also as the monomeric building blocks from which a number of
  novel well-defined inorganic polymers can be constructed. The fundamental
  mode(s) of interaction of monomeric aminoboranes with catalytically relev
 ant late transition metal systems are therefore of significant interest. T
 he intrinsic two-electron donor capabilities of these compounds have been 
 probed through coordination at 16-electron [CpRu(PR3)2]+ fragments. In con
 trast to the side-on binding of isoelectronic alkene donors\, an alternati
 ve mono(σ-BH) mode of aminoborane ligation is established for H2BNCy2 (e.
 g. I)\, with binding energies only ~8 kcal mol-1 greater than those for an
 alogous dinitrogen complexes.[1] Variations in ground state structure and 
 exchange dynamics as a function of the phosphine ancillary ligand set are 
 consistent with chemically significant back-bonding into an orbital of B H
  σ* character.\n\n                          \n	I	II	III\n\nThe use of cat
 ionic 14-electron ruthenium\, rhodium or iridium metal systems allows an a
 lternative κ2 mode of coordination to be accessed\, featuring significant
 ly tighter ligand binding (e.g. II).[2] Moreover\, by systematic variation
  in the electronic properties of the metal centre\, varying degrees of B-H
  bond activation can be induced\, leading to the formation of primary bory
 l species LnM{B(H)NR2} (by oxidative addition of a single B-H bond)\, or e
 ven of borylene dihydride complexes via additional B-to-M α-hydride trans
 fer (see III and Scheme).[3]\n\n \n\n[1] Vidovic\, D.\; Addy\, D.A.\; Krä
 mer\, T.\; McGrady\, J.\; Aldridge\, S. J. Am. Chem. Soc. 2011\, 133\, 849
 4.\n[2] (a) Tang\, C.Y.\; Thompson\, A.L.\; Aldridge\, S. Angew. Chem.\, I
 nt. Ed. 2010\, 49\, 921-925\; (b) Tang\, C.Y.\; Thompson\, A.L.\; Aldridge
 \, S. J. Am. Chem. Soc. 2010\, 132\, 10578-10591.\n[3] O’Neill\, M.\; Ad
 dy\, D.A.\; Riddlestone\, I.\; Kelly\, M.\; Phillips\, N.\; Aldridge\, S. 
 J. Am. Chem. Soc. 2011\, 133\, 11500. \n
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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