Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study

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Title:Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study
Creators:
Havlas, Zdeněk
Bock, Hans
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 66, 3, pp. 473-482
Uncontrolled Keywords:Coupled cluster method, <i>Ab initio</i> calculations, Amines, DFT, MP4, Silanes, MP2, Donor/acceptor complexes

Abstract

For the model organosilicon cation H<sub>3</sub>N···SiH<sub>3</sub><sup>+</sup>, potential curves have been calculated by density functional theory at the B3LYP level, by both MP2 and MP4 perturbation procedures and by a Coupled Cluster approach. Relative to the analogous potential curve for the uncharged adduct, H<sub>3</sub>N···SiH<sub>4</sub>, a considerable increase of the long-range Si···N interaction accompanied by bond shortening is predicted. For chemical comparison, the structure of the "double R<sub>2</sub>N-twister" dication salt, [C<sub>6</sub>H<sub>4</sub>(CH<sub>2</sub>NR<sub>2</sub>)<sub>2</sub>-Si-(R<sub>2</sub>NCH<sub>2</sub>)<sub>2</sub>C<sub>6</sub>H<sub>4</sub>]<sup>++</sup>Cl<sub>2</sub><sup>-</sup>, reported in the literature as a non-crystalline solid, was optimized by DFT calculations and a minimum for the hexacoordinated organosilicon center with each two Si···N bonds of different lengths was located. To test the reliability of the quantum chemical procedure, in addition the analogous and structurally characterized dication salt, [(3-picoline)<sub>4</sub>SiH<sub>2</sub>]<sup>++</sup>[Cl<sup>-</sup>···(HCCl<sub>3</sub>)<sub>2</sub>]<sub>2</sub>, which contains a hexacoordinated Si center with 4 equivalent Si···N interactions, has been selected to reproduce its structure by DFT optimization. Both hexacoordinated, tetra-<i>N</i>-surrounded Si dications, substantiate the increase of long-range Si···N interactions as predicted by the potential curves for the model adduct H<sub>3</sub>N···SiH<sub>3</sub><sup>+</sup> based on highly correlated calculations. <p>

Title:Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study
Creators:
Havlas, Zdeněk
Bock, Hans
Uncontrolled Keywords:Coupled cluster method, <i>Ab initio</i> calculations, Amines, DFT, MP4, Silanes, MP2, Donor/acceptor complexes
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:66
Number:3
Page Range:pp. 473-482
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20010473UNSPECIFIED
ID Code:1803
Item Type:Article
Deposited On:06 Feb 2009 17:12
Last Modified:06 Feb 2009 16:12

Citation

Havlas, Zdeněk; Bock, Hans (2001) Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study. Collection of Czechoslovak Chemical Communications, 66 (3). pp. 473-482. ISSN 0010-0765

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