Modeling the effect of H-bonding interactions and molecular packing on the molecular structure of [Ag(ethylnicotinate) 2
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ORIGINAL PAPER
Modeling the effect of H-bonding interactions and molecular packing on the molecular structure of [Ag(ethylnicotinate)2]NO3 complex Saied M. Soliman
Received: 20 June 2012 / Accepted: 19 September 2012 / Published online: 9 October 2012 # Springer-Verlag Berlin Heidelberg 2012
Abstract The gas phase molecular structure of a single isolated molecule of [Ag(Etnic)2NO3];1 where Etnic 0 Ethylnicotinate was calculated using B3LYP method. The Hbonding interaction between 1 with one (complex 2) and two (complex 3) water molecules together with the dimeric formula [Ag(Etnic)2NO3]2;4 and the tetrameric formula [Ag (Etnic)2NO3]4;5 were calculated using the same level of theory to model the effect of intermolecular interactions and molecular packing on the molecular structure of the titled complex. The H-bond dissociation energies of complexes 2 and 3 were calculated to be in the range of 12.220–14.253 and 30.106–31.055 kcalmol−1, respectively, indicating the formation of relatively strong H-bonds between 1 and water molecules. The calculations predict bidentate nitrate ligand in the case of 1 and 2, leading to distorted tetrahedral geometry around the silver ion with longer Ag–O distances in case of 2 compared to 1, while 3 has a unidentate nitrate ligand leading to a distorted trigonal planar geometry. The packing of two [Ag(Etnic)2NO3] complex units; 4 does not affect the molecular geometry around Ag(I) ion compared to 1. In the case of 5, the two asymmetric units of the formula [Ag (Etnic)2NO3] differ in the bonding mode of the nitrate group, where the geometry around the silver ion is distorted tetrahedral in one unit and trigonal planar in the other. The calculations predicted almost no change in the charge densities at the different atomic sites except at the sites involved in the C–
Electronic supplementary material The online version of this article (doi:10.1007/s00894-012-1598-6) contains supplementary material, which is available to authorized users. S. M. Soliman (*) Department of Chemistry, Faculty of Science, Alexandria University, PO Box 426, Ibrahimia, 21525 Alexandria, Egypt e-mail: [email protected]
H⋯O interactions as well as at the coordinated nitrogen of the pyridine ring. Keywords H-bonding . Packing . Silver . Ethylnicotinate . DFT
Introduction Intermolecular interactions such as hydrogen bonds between molecules have attracted the attention of many researchers [1–4]. Hydrogen bonding is considered the principal mode of noncovalent interaction, not only affecting the activities of many biological molecules but also playing an important role in stabilizing and determining their structure and shape [5]. In recent years, silver compounds have attracted much attention due to their antimicrobial activity; silver ions do not show toxicity and carcinogenic activities in the range of concentrations applied [6–9]. As a result, there is increased interest in discovering more potential uses of silver(I) as a therapeutic agent for different antimicrobial applications [10–16]. Silver (I) comp
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