Molecular geometries of H2S center dot center dot center dot ICF3 and H2O center dot center dot center dot ICF3 characterised by broadband rotational spectroscopy

作者：Stephens Susanna L; Walker Nicholas R^*; Legon Anthony C

来源：Physical Chemistry Chemical Physics, 2011, 13(47): 21093-21101.

DOI：10.1039/c1cp22339a

The rotational spectra of three isotopologues of H2S center dot center dot center dot ICF3 and four isotopologues of H2O center dot center dot center dot ICF3 are measured from 7-18 GHz by chirped-pulse Fourier transform microwave spectroscopy. The rotational constant, B-0, centrifugal distortion constants, D-J and D-JK, and nuclear quadrupole coupling constant of I-127, chi(aa)(I), are precisely determined for H2S center dot center dot center dot ICF3 and H2O center dot center dot center dot ICF3 by fitting observed transitions to the Hamiltonians appropriate to symmetric tops. The measured rotational constants allow determination of the molecular geometries. The C-2 axis of H2O/H2S intersects the C-3 axis of the CF3I sub-unit at the oxygen atom. The lengths of halogen bonds identified between iodine and sulphur, r(S center dot center dot center dot I), and iodine and oxygen, r(O center dot center dot center dot I), are determined to be 3.5589(2) angstrom and 3.0517(18) angstrom respectively. The angle, phi, between the local C-2 axis of the H2S/H2O sub-unit and the C-3 axis of CF3I is found to be 93.7(2)degrees 1 in H2S center dot center dot center dot ICF3 and 34.4(20)degrees 1 in H2O center dot center dot center dot ICF3. The observed symmetric top spectra imply nearly free internal rotation of the C-2 axis of the hydrogen sulphide/water unit about the C-3 axis of CF3I in each of these complexes. Additional transitions of (H2O)-O-16 center dot center dot center dot ICF3, (D2O)-O-16 center dot center dot center dot ICF3 and (H2O)-O-18 center dot center dot center dot ICF3 can be assigned only using asymmetric top Hamiltonians, suggesting that the effective rigid-rotor fits employed do not completely represent the internal dynamics of H2O center dot center dot center dot ICF3.

• 出版日期2011