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Switchable dual bonding nature in silabicyclo[1.1.0]butanes that exhibit bond stretch isomerism
Author(s) -
Chinaroj Siwat,
Iwamoto Takeaki
Publication year - 2020
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.4019
Subject(s) - chemistry , bent bond , sextuple bond , single bond , molecular geometry , covalent bond , bond length , bond order , valence bond theory , crystallography , three center two electron bond , quadruple bond , bond energy , triple bond , computational chemistry , geometry , double bond , molecule , crystal structure , molecular orbital , polymer chemistry , organic chemistry , alkyl , mathematics
Silicon analogues of bicyclo[1.1.0]butanes are known to exhibit a bond stretch isomerism where the bridgehead SiSi bond changes in both length and geometry. The bridgehead silicon atom of long bond (lb) isomers exhibits an unusual geometry where all the bonds are located on the same hemisphere, making the geometry of the bridgehead SiSi bond the so‐called inverted σ bond in contrast with the typical σ bond geometry found in the short bond (sb) isomers. Herein, the bonding nature of bridgehead SiSi bonds was theoretically investigated in detail using valence bond theory calculation at SL‐BOVB/6‐31G(d) level of theory. Our calculation demonstrates that the bond type of the bridgehead bond depends on the geometry around the bridgehead atoms with those in sb and lb isomers classified as covalent (COV) and charge‐shift (CS) bonds, respectively. The different bond types between two bond stretch isomer indicate that the bonding nature is switchable in one molecule. The detailed examination of the bond stretch isomerization in parent 1,3‐disilabicyclo[1.1.0]butane demonstrated that the enhanced CS bond nature in the lb isomer is mainly attributed to the geometry inversion of the σ bond rather than the bond elongation. This switchable dual bonding nature provides an important platform to compare covalent and CS bond on equal footing for both theoretical and experimental investigations.