Premium
Boron Tunneling in the “Weak” Bond‐Stretch Isomerization of N−B Lewis Adducts
Author(s) -
Nandi Ashim,
Tarannam Naziha,
Rodrigues Silva Daniela,
Fonseca Guerra Célia,
Hamlin Trevor A.,
Kozuch Sebastian
Publication year - 2021
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202100505
Subject(s) - chemistry , isomerization , covalent bond , boron , van der waals force , crystallography , matrix isolation , computational chemistry , bond order , bond energy , adduct , bond length , chemical physics , molecule , organic chemistry , crystal structure , catalysis
Some nitrile‐boron halide adducts exhibit a double‐well potential energy surface with two distinct minima: a “long bond” geometry (LB, a van der Waals interaction mostly based on electrostatics, but including a residual charge transfer component) and a “short bond” structure (SB, a covalent dative bond). This behavior can be considered as a “weak” form of bond stretch isomerism. Our computations reveal that complexes RCN−BX 3 (R=CH 3 , FCH 2 , BrCH 2 , and X=Cl, Br) exhibit a fast interconversion from LB to SB geometries even close to the absolute zero thanks to a boron atom tunneling mechanism . The computed half‐lives of the meta‐stable LB compounds vary between minutes to nanoseconds at cryogenic conditions. Accordingly, we predict that the long bond structures are practically impossible to isolate or characterize, which agrees with previous matrix‐isolation experiments.