INOR 471 |
| While a large component of our work deals with the synthesis of polyfunctional Lewis acids, it is our ultimate intent to harness and utilize the cooperative effects occurring in such systems for the discovery of unusual structures, bonding modes, supramolecules and reactivities. Starting from the Li(THF)4 salt of dimesityl-1,8-naphthalenediylborate and C6F5HgCl, we have been able to prepare a heteronuclear bidentate Lewis acid (1) in which a Mes2B moiety and a C6F5Hg moiety coexist at the peri-positions of a naphthalene backbone. Similar reactions have allowed us to synthesize the tetranuclear derivatives 2 and 3. In addition to studying these polydentate Lewis acids as anion receptors, we have also investigated their reduction chemistry. The cyclic voltammogram of 1 in THF shows a reversible reduction wave at E1/2 -2.16 V (vs Fc/Fc+) corresponding to the formation of a boron-centered radical anion. In the case of diborane 2, two distinct waves are observed at E1/2 -2.24 V and -2.44 V. The relatively large potential difference between these two waves suggests that the boron centers are electronically coupled via a direct B-Hg-Hg-B σ-interaction involving the boron 2-p and mercury 6-p orbitals. This proposal is reinforced by DFT calculations on model compounds which suggest that the LUMO of 2 bears large a contribution from the σ-conjugated boron and mercury p-orbitals.
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Polyfunctional Organoboranes: From Molecules to Materials
1:30 PM-5:40 PM, Monday, 11 September 2006 Moscone Center -- Room 302, Oral
Division of Inorganic Chemistry |
