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Not Carbon s-p Hybridization, but Coordination Number Determines C-H and C-C Bond Length.

ABSTRACT: A fundamental and ubiquitous phenomenon in chemistry is the contraction of both C-H and C-C bonds as the carbon atoms involved vary, in s-p hybridization, along sp³ to sp² to sp. Our quantum chemical bonding analyses based on Kohn-Sham molecular orbital theory show that the generally accepted rationale behind this trend is incorrect. Inspection of the molecular orbitals and their corresponding orbital overlaps reveals that the above-mentioned shortening in C-H and C-C bonds is not determined by an increasing amount of s-character at the carbon atom in these bonds. Instead, we establish that this structural trend is caused by a diminishing steric (Pauli) repulsion between substituents around the pertinent carbon atom, as the coordination number decreases along sp³ to sp² to sp.

SUBMITTER: Vermeeren P

PROVIDER: S-EPMC8248318 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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Not Carbon s-p Hybridization, but Coordination Number Determines C-H and C-C Bond Length.

Vermeeren Pascal P van Zeist Willem-Jan WJ Hamlin Trevor A TA Fonseca Guerra Célia C Bickelhaupt F Matthias FM

Chemistry (Weinheim an der Bergstrasse, Germany) 20210303 24

A fundamental and ubiquitous phenomenon in chemistry is the contraction of both C-H and C-C bonds as the carbon atoms involved vary, in s-p hybridization, along sp<sup>3</sup> to sp<sup>2</sup> to sp. Our quantum chemical bonding analyses based on Kohn-Sham molecular orbital theory show that the generally accepted rationale behind this trend is incorrect. Inspection of the molecular orbitals and their corresponding orbital overlaps reveals that the above-mentioned shortening in C-H and C-C bonds ...[more]

PMID: 33513281

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