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Origin of significant solvent effects on 1 J (CC) spin–spin coupling in some acetylenes: hydrogen bonding and solvent polarity
Author(s) -
Biedrzycka Zenobia,
KamieńskaTrela Krystyna,
Witanowski Michał
Publication year - 2010
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.1626
Subject(s) - phenylacetylene , chemistry , solvent , acetylene , moiety , hydrogen bond , photochemistry , solvent effects , acceptor , polarity (international relations) , crystallography , inorganic chemistry , stereochemistry , organic chemistry , molecule , catalysis , condensed matter physics , biochemistry , physics , cell
Abstract It is demonstrated that some acetylenes, those of the RCCH structure, display anomalously high sensitivity to solvent effects of their 1 J (CC) coupling while RCCR acetylenes fail to show that. The solvent‐induced variation in the latter coupling does not exceed 3 Hz; this seems to be the upper limit of variation of any J (CC) and J (CH) coupling in the molecular system studied which included: acetylene (in 13 solvents), phenylacetylene (in 12 solvents), 1‐phenylpropyne, and 2‐hexyne (two solvents each), and the only exceptions are 1 J (CC) in acetylene, which is shown to vary within about 13 Hz, and that in phenylacetylene where the range amounts to about 8 Hz. These apparent anomalies are explained in the present study in terms of two effects of prime importance, solvent polarity and the solute‐to‐solvent hydrogen bonds where the CH moiety in RCCH acetylenes acts as a donor of hydrogen bonds to acceptor sites in the solvent concerned. Copyright © 2009 John Wiley & Sons, Ltd.