Cation-pi interactions of bare and coordinatively saturated metal ions: contrasting structural and energetic
A Srinivas Reddy1, Hendrik Zipse, G Narahari Sastry
1Molecular Modeling Group, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India.
Abstract:
In the present work, we address an apparent disparity in the structural parameters of the X-ray structures and theoretical models of cation-pi complexes in biological and chemical recognition. Hydrated metal ion (Li+, Na+, K+, Mg2+, Ca2+) complexes with benzene (cation-pi) are considered as model systems to perform quantum mechanical calculations in evaluating the geometrical parameters and interaction energies of these complexes. The computations disclose that there is a variation in the structural parameters as well as in the interaction energies of these complexes with the multiple additions of water molecules. The distance between the cation and the pi-system increases with the addition of water molecules, delineating the influence of solvent or the neighborhood atoms on the structural parameters of cation-pi systems present in crystal structures.
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