Supramolecular Silanol Chemistry in the Gas Phase. Topological (AIM) and Population (NBO) Analyses of Hydrogen-Bonded Complexes between H 3 SiOH and Selected O- and N-Acceptor Molecules

Beckmann, Jens; Grabowsky, Simon (2007). Supramolecular Silanol Chemistry in the Gas Phase. Topological (AIM) and Population (NBO) Analyses of Hydrogen-Bonded Complexes between H 3 SiOH and Selected O- and N-Acceptor Molecules. Journal of physical chemistry. A, 111(10), pp. 2011-2019. American Chemical Society 10.1021/jp0672712

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Hydrogen bonding of the type SiO−H···A (A = O, N) has been studied in the gas phase for simple H3SiOH·acceptor complexes with the acceptor molecules being O(H)SiH3, OH2, O(H)CH3, O(CH3)2, O(CH3)SiH3, O(SiH3)2, NH3, N(CH3)H2, N(CH3)2H, N(CH3)3, N(CH3)2C6H5, and NC5H5, respectively, at the B3LYP/6-311+(2d,p) level of theory, using Bader's atoms in molecules (AIM) and Weinhold's natural bond orbital (NBO) methodology. For all complexes (except H3SiOH·N(CH3)2C6H5) the complex energy Eadd. is a good estimate for the hydrogen bond energy EHB, which is generally higher in N-acceptor complexes (−5.52 to −7.17 kcal mol-1) than in O-acceptor complexes (−2.09 to −5.06 kcal mol-1). In case of H3SiOH·N(CH3)2C6H5, EHB and Eadd. differ by the energy associated with the loss of n(N)→π conjugation in N(CH3)2C6H5 upon complex formation. EHB shows no correlation with O···A distances and the red shifts Δν(OH) of the OH-stretching vibrations when different acceptors are compared, although both parameters are commonly used to estimate the strength of the hydrogen bond from spectroscopic and diffraction data. A good linear correlation of the hydrogen bond energy EHB has been established with parameters derived from the AIM and NBO analyses, namely, the electron densities ρ(HA) and ρ(OH) at the H···A and O−H bond critical points (BCPs) and the NLMO bond orders BONLMO(HA) of the H···A bonds of the H3SiOH·acceptor complexes as well as the change of natural charges ΔqNPA(O) at the O-donor atom upon H3SiOH·acceptor complex formation. Hydrogen bonding of the type SiO−H···A (A = O, N) has been also studied in the related cyclic multiple H3SiOH·acceptor complexes (H3SiOH)3, (H3SiOH)2·NC5H5, and (H3SiOH)4, respectively, at the same level of theory. Cooperative hydrogen bonding is evident for all cyclic multiple H3SiOH·acceptor complexes, whereby the strongest concomitant strengthening of the hydrogen bonds is observed for (H3SiOH)4 and (H3SiOH)2·NC5H5.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Grabowsky, Simon

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

1089-5639

Publisher:

American Chemical Society

Language:

English

Submitter:

Simon Grabowsky

Date Deposited:

29 Jan 2020 16:03

Last Modified:

29 Jan 2020 16:03

Publisher DOI:

10.1021/jp0672712

PubMed ID:

17305322

BORIS DOI:

10.7892/boris.138131

URI:

https://boris.unibe.ch/id/eprint/138131

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