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Chloromethane–Water Adduct: Rotational Spectrum, Weak Hydrogen Bonds, and Internal Dynamics
Author(s) -
Gou Qian,
Spada Lorenzo,
Lòpez Juan Carlos,
Grabow JensUwe,
Caminati Walther
Publication year - 2015
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201500013
Subject(s) - chloromethane , adduct , hydrogen bond , hydrogen , chemistry , dynamics (music) , spectrum (functional analysis) , rotational dynamics , photochemistry , physics , catalysis , molecule , organic chemistry , quantum mechanics , acoustics
The rotational spectra of four isotopologues of the 1:1 complex between chloromethane and water revealed the presence of only one rotamer in a pulsed jet expansion. The two subunits are linked through two weak hydrogen bonds, OH⋅⋅⋅Cl ( R H⋅⋅⋅Cl =2.638(2) Å) and CH⋅⋅⋅O ( R H⋅⋅⋅O =2.501(2) Å), forming a five‐membered ring. All transitions display the hyperfine structure due to the 35 Cl (or 37 Cl) nuclear quadrupole effects. Dynamical features in the spectrum are caused by two large‐amplitude motions. Each component line appears as an asymmetric doublet with a relative intensity ratio of 1:3. The splittings led to the determination of barrier to internal rotation of water around its symmetry axis, V 2 =320(10) cm −1 . Finally, an unexpected small value of the inertial defect (−0.96 uÅ 2 rather than −3.22 uÅ 2 ) allowed the estimation of the barrier to the internal rotation of the CH 3 group, V 3 ≈8 cm −1 .