(N2O)(2)center dot SO2: Rotational spectrum and structure of the first van der Waals trimer containing sulfur dioxide

摘要

The trimer (N2O)(2). SO2 has been studied by Fourier transform microwave spectroscopy. The rotational constants for the normal species are A=1369.1014(11) MHz, B=1115.5816(11) MHz, and C=730.5790(4) MHz. Five isotopomers of the complex have been studied, allowing a determination of its structure. The configuration aligns the centers-of-mass of the three monomers in an approximate equilateral triangle. The monomers twist relative to this plane so that the two N2O's are intermediate between T-shaped and crossed rather than the usual slipped-parallel planar. The SO2 is oriented so that its oxygens are straddling one N2O (similar to the N2O . SO2 dimer), while its sulfur is closest to the oxygen end of the other N2O. The dipole moment of ((N2O)-N-15)(2). SO2 was measured, giving mu(a)=0.606(1) D, mu(b)=1.256(2) D, mu(c)=0.058(2) D, and mu(total)=1.396(2) D. A semiempirical model has been used to predict the trimer structure, and comparison is made with this model as well as with the dimer N2O . SO2. (C) 2000 American Institute of Physics. [S0021-9606(00)01520-8]. [References: 39]