A novel hexanuclear silver(i) cluster containing a regular Ag6 ring with short Ag-Ag distances and an argentophilic interaction
- Barreiro, E. 2
- Casas, J.S. 2
- Couce, M.D. 3
- Laguna, A. 4
- López-De-Luzuriaga, J.M. 1
- Monge, M. 1
- Sánchez, A. 2
- Sordo, J. 2
- Vázquez López, E.M. 3
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1
Universidad de La Rioja
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2
Universidade de Santiago de Compostela
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3
Universidade de Vigo
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4
Instituto de Nanociencia y Materiales de Aragón
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ISSN: 1477-9226
Année de publication: 2013
Volumen: 42
Número: 16
Pages: 5916-5923
Type: Article
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Résumé
The hexanuclear complex [HQ][Ag(p-mpspa)] (H2-p-mpspa = 3-(4-methoxyphenyl)-2-sulfanylpropenoic acid) was prepared by reacting the precursor [Ag(H-p-mpspa)] with diisopropylamine (Q). The complex was characterized by spectroscopic techniques and the structure was solved by a single crystal X-ray diffraction study. The crystal contains hydrogen-bonded diisopropylammonium cations and [Ag6(p-mpspa)6] 6- anions that are based on a regular Ag6 ring with each S-donor atom of the sulfanylcarboxylate ligand bridging two Ag atoms. The Ag-Ag bond distances, 2.8036(6) Å, are very short and suggest a closed shell d10⋯d10 argentophilic interaction. To analyze the relative role of this interaction and that of the S-bridging atom the anionic [Ag6(p-mpspa)6]6- moiety has been studied theoretically at the Hartree-Fock (HF) and 2nd order Møller-Plesset perturbation theory (MP2) levels on a very simple [Ag 6(SH)6] A model system. A large model system [Ag 6(p-mpspa)6]6-B has also been studied by applying the ONIOM (QM/MM) approach using HF/UFF and MP2/UFF combinations as levels of theory. The six experimentally observed Ag(i)⋯Ag(i) supported interactions are reproduced when dispersion-type interactions are considered in the theory levels MP2 and ONIOM MP2/UFF for models A and B, respectively. The use of HF and ONIOM HF/UFF levels led to a similar hexanuclear structure but displayed a large hexagonal disposition without argentophilic contacts for both models A and B. The steric hindrance exerted by the ligands did not preclude the formation of argentophilic interactions, as observed experimentally. © 2013 The Royal Society of Chemistry.