Monday, August 16, 2010

Inorganic Chemistry

Separation of Geometric Isomers of a Dicopper Complex by Using a 19F-Labeled Ligand: Dynamics, Structures, and DFT Calculations
Stphanie Durot, Laila H. Hossain, Sylvain Hamman, Hlne Jamet, Maylis Orio, Isabelle Gautier-Luneau, Dominique Luneau, Christian Philouze, Jean-Louis Pierre and Catherine Belle
DOI: 10.1021/ic1006567
Introducing a fluorine group on two pyridines of the HLCH3 ligand (2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol) allows the separation of two geometric isomers after complexation by two copper(II) ions. Methods for isolating the isomers (1meso and 1rac) as a μ-phenoxo,μ-hydroxo dicopper(II) complex as a crystalline product have been developed. Both isomers (1meso and 1rac) have been characterized by X-ray crystallography and 19F NMR. The isomerism is determined by the disposition of the fluorine atoms with respect to the plane containing the Cu2O2 core. Density functional theory calculations using different functionals were performed to provide additional support for the existence of these two forms. Dissolution of 1meso in acetone or acetonitrile causes its spontaneous isomerization into the 1rac form at room temperature. Combined experimental studies (UV−vis, 19F NMR) and theoretical calculations support this process. Paramagnetic 19F NMR appears as a unique and powerful probe for distinguishing the two isomers and supplying direct evidence of this isomerization process in solution.
A Pd6 Molecular Cage via Multicomponent Self-Assembly Incorporating Both Neutral and Anionic Linkers
Arun Kumar Bar, Golam Mostafa and Partha Sarathi Mukherjee
DOI: 10.1021/ic101139s
A Pd6 molecular cage [{(tmen)Pd}6(bpy)3(tma)2](NO3)6 [1; where tmen = N,N,N′,N′-tetramethylethylene diamine, bpy = 4,4′-bipyridyl, and H3tma = trimesic acid] was prepared via the template-free three-component self-assembly of a cis-blocked palladium(II) acceptor in combination with a tricarboxylate and a dipyridyl donor. Complex 1 represents the first example of a 3D palladium(II) cage of defined shape incorporating anionic and neutral linkers. Guest-induced exclusive formation of this cage was also monitored by an NMR study.

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