A1 Journal article (refereed)
Ab Initio MO Study of Silver Ion Complexation in [2.2.2]Cyclophane pii-Prismands. (2000)


Saarenketo, P., Suontamo, R., Jödicke, T., & Rissanen, K. (2000). Ab Initio MO Study of Silver Ion Complexation in [2.2.2]Cyclophane pii-Prismands.. Organometallics, 19(12), 2346-2353. https://doi.org/10.1021/om000190m


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Publication details

All authors or editors: Saarenketo, Pauli; Suontamo, Reijo; Jödicke, Tim; Rissanen, Kari

Journal or series: Organometallics

ISSN: 0276-7333

eISSN: 1520-6041

Publication year: 2000

Volume: 19

Issue number: 12

Pages range: 2346-2353

Publisher: American Chemical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1021/om000190m

Publication open access: Not open

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Abstract

Ab initio Hartree−Fock and DFT MO calculations have been used to study the conformations of [2.2.2]cyclophane π-prismands and the formation of π-complexes with silver ion and [2.2.2]cyclophanes. The lowest energy cyclophane conformations have been calculated up to the HF/6-31+G* level of theory. The silver π-complexes of the lowest energy conformations have been calculated with HF/3-21G* and B3LYP/3-21G* levels of theory. The nature of bonding in silver ion π-complexes has been studied with natural bond orbital analysis (NBO). Energies of the calculated cyclophanes and complexes, together with formation energies of those complexes, have also been discussed. The results obtained have been compared to X-ray crystal structures whenever such structures were available. Calculated and experimental X-ray structures agreed reasonably well given provision to the rather small 3-21G* basis set and the omission of triflate anion in the calculation model. The NBO analysis showed that when Ag+ is bonded to the cyclophane cavity, the bonds are formed by σ-donation and d−π*-back-donation between the silver ion and the hydrocarbon skeleton, resulting in hexahapto (3×η2) overall π-bonding. This is in agreement with the well-known “bonding−back-bonding” scheme in transition metal carbonyl complexes. In this case the σ-donation from hydrocarbon to silver ion is the main contribution to the metal−cyclophane bonding. One dihapto (η2) bonding to one aromatic ring in the present π-prismands relates by strength to a single strong hydrogen bond, which is up to 100 kJ/mol; thus the strength of this 3×η2 bonding in these [2.2.2]cyclophane π-prismands can be compared to three simultaneous strong hydrogen bonds.


Free keywords: ab initio MO laskut; prismandit; NBO analyysi


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