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A computational quest for the effects of fused rings on the stability of Hammick carbenes type remote N ‐heterocyclic carbenes
Author(s) -
Zhao Huan,
Yang DongDong,
Zhou Yuan,
Fang Yu,
Shi Min,
Vessally Esmail
Publication year - 2021
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.202000247
Subject(s) - chemistry , carbene , heteroatom , substituent , thiophene , furan , aromaticity , pyrrole , nucleophile , singlet state , computational chemistry , electrophile , crystallography , stereochemistry , photochemistry , ring (chemistry) , molecule , organic chemistry , catalysis , excited state , physics , nuclear physics
Substituent effects of fused six, and five‐membered aromatic rings are investigated on the stability, aromaticity, charge distribution, nucleophilic ( N ), and electrophilic ( ω ) characters of 20 singlet (s) and triplet (t) Hammick carbenes, at B3LYP/AUG‐cc‐pVTZ and M06‐2X/AUG‐cc‐pVTZ. Results display: (a) The higher thermodynamic and kinetic stability is revealed by carbenes situated between two nitrogen and/or two oxygen heteroatoms of two substituted rings, in a “W” arrangement toward the carbenic center; (b) Regardless of the arrangement, the order of thermodynamical and kinetic stabilization for fused rings is pyrrole > furan > thiophene > phosphole. (c) The substituted Hammick carbenes with two fused heterocyclics, in a given arrangement, show more stability than unsubstituted Hammick carbene; (d) While two five‐membered heterocyclic rings stabilize their corresponding substituted carbenes, two benzene rings destabilize Hammick carbene; (e) In all structures, s species emerges as ground state, exhibiting more stability than its t state; (f) The scrutinized s carbenes show higher N and lower ω than their corresponding t states.