INOR 342 |
| In recent years, significant efforts have been made in elucidating the structural aspects of anion coordination as coordination chemistry of anions has proven its roles in biological systems, the environmental issues, templated synthesis and catalysis. Present talk addresses some of the important aspects of halide binding based on our recent findings. It has been established that azamacropolycycles upon protonation can become good hosts for halides via (N-H)+•••halide interactions. A number of octaaminocryptands in their different protonation states have been studied extensively for halide encapsulation. A tren capped bicyclic cryptand with p-xylyl spacers L in hexaprotonated state, [H6L]6+ shows monotopic encapsulation of chloride/bromide via six C-H•••halide interactions whereas a unique binding of an acyclic quasiplanar water tetramer is isolated in [H4L]4+ having iodide counter ion. On the other hand, [H7L]7+ encapsulates chloride via one (N-H)+•••Cl- and three O-H•••Cl- (from discrete undecameric water cluster in the lattice) interactions. [H2L]2+ does not show any encapsulation whereas [H3L]3+ receptor encapsulates a molecule of water inside the cavity. Halide binding studies inside the cavity with similar type of cryptands are also presented. In a parallel front, tripodal amine systems are explored for halide encapsulation via a positive electrostatic cloud, anion•••pi and C6F5•••C6F5 interactions. |
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Anion Coordination Chemistry
8:00 AM-12:00 PM, Monday, August 20, 2007 BCEC -- 205C, Oral
Division of Inorganic Chemistry |