Chloromethane–Water Adduct: Rotational Spectrum,Weak Hydrogen Bonds,and Internal Dynamics |
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| Authors: | Dr Qian Gou Lorenzo Spada Prof Juan Carlos Lòpez Prof Jens‐Uwe Grabow Prof Walther Caminati |
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| Institution: | 1. Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39)?0512099456;2. Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Belén, 7, 47011, Valladolid (Spain);3. Institut für Physikalische Chemie und Elektrochemie, Gottfried‐Wilhelm‐Leibniz‐Universt?t, Callinstr. 3?A, 30167 Hannover (Germany) |
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| Abstract: | 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, O? H???Cl (RH???Cl=2.638(2) Å) and C? H???O (RH???O=2.501(2) Å), forming a five‐membered ring. All transitions display the hyperfine structure due to the 35Cl (or 37Cl) 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, V2=320(10) cm?1. Finally, an unexpected small value of the inertial defect (?0.96 uÅ2 rather than ?3.22 uÅ2) allowed the estimation of the barrier to the internal rotation of the CH3 group, V3≈8 cm?1. |
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| Keywords: | atmospheric chemistry hyperfine structure internal dynamics molecular complex rotational spectroscopy weak hydrogen bond |
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