| Abstrakt: |
Ground-state rotational spectra of the seven isotopomers H[sub 2]O...[sup 35]Cl[sub 2], H[sub 2]O...[sup 37]Cl[sup 35]Cl, H[sub 2]O...[sup 35]Cl[sup 37]Cl, D[sub 2]O...[sup 35]Cl[sub 2], D[sub 2]O...[sup 37]Cl[sup 35]Cl, HDO...[sup 35]Cl[sub 2], and HDO...[sup 37]Cl[sup 35]Cl of the complex formed between water and dichlorine were observed by pulsed-jet, Fourier-transform microwave spectroscopy. Rotational constants B[sub 0] and C[sub 0], centrifugal distortion constants Δ[sub J] and Δ[sub JK], and Cl nuclear quadrupole coupling constants χ[sub aa](Cl[sub x]) and {χ[sub bb](Cl[sub x])-χ[sub cc](Cl[sub x])}, where x=i (inner) or o (outer), were obtained via spectral analyses. The spectroscopic constants were interpreted, on the basis of models for the complex, to give the geometry, the binding strength, and the extent of inter- and intramolecular electron transfer on complex formation. The zero-point geometry is defined in terms of the effective values r(O...Cl[sub i])=2.8479(3) Å and φ=43.4(3)°, where φ is the angle made by the bisector of the HOH angle with the O...Cl internuclear line. The intermolecular stretching force constant k[sub σ]=8.0(1) N m[sup -1]. Fractions δ[sub i]=0.005(5) and δ[sub p]=0.034(3) of an electron were estimated to be transferred from O to Cl and from Cl[sub i] to Cl[sub o], respectively. The geometrical conclusions are supported by ab initio calculations at the aug-cc-pVDZ/MP2 level of theory, with good agreement for φ and r(O...Cl[sub i]). A comparison of the properties of H[sub 2]O...Cl[sub 2] with those of H[sub 2]O...HCl provides evidence in support of a recent proposal of a halogen bond B...XY that is the analog of the hydrogen bond B...HX, where X and Y are halogen atoms. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
