The nature of the AgI...AgI interaction in different Ag(NH3)2 dimers embedded in supramolecular solids |
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Authors: | Zheng Shao-Liang Volkov Anatoliy Nygren Cara L Coppens Philip |
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Institution: | Department of Chemistry, State University of New York at Buffalo, Buffalo, New York, 14260-3000, USA. chem9994@buffalo.edu |
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Abstract: | An isolated silver(I) ammonia monomer, a dimer, and a novel dimer containing an intercalated water molecule have been embedded as guests in supramolecular frameworks, Ag(NH3)2](H2thpe)(H3thpe)].MeCN (1), {Ag(NH3)2}2](H2thpe)2]4.25 H2O (2), and {Ag(NH3)2}-H2O-{Ag(NH3)2}](H2thpe)(2)]benzene (3) (H3THPE=tris(hydroxyphenyl)ethane). The {Ag(NH3)2}2]2+ dimer is not stable as an isolated entity, but is stabilized by hydrogen bonding in the supramolecular framework. The water-intercalated silver(I) ammonia dimer, which constitutes a novel species, is also subject by hydrogen bonding in concentrated solutions. The destabilization energy of the dimer relative to isolated monomers is calculated to be approximately 300 kJ mol(-1) by both perturbation methods and DFT theory. For the water-intercalated dimer it is calculated to be approximately 200 kJ mol(-1) according to the BSSE-corrected MP2 calculation. The different aggregate states show a dramatic variation of absorption and emission properties, in accordance with the concentration dependent red-shift observed in solutions. Natural-bond-orbital analysis shows that the disilver-ammonium-aquo "sandwich" cation in 3 is stabilized by interaction between the pi lone pair orbital on the oxygen atom of the water molecule and Ag(I)--N sigma antibonding molecular orbital. |
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Keywords: | ab initio calculations argentophilicity crystal engineering host–guest systems luminescence |
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