Isotopic studies, structure and modeling of the nitrous oxide-acetylene complex

The microwave spectra of six isotopomers of HCCH . N2O have been measured. The structure of the complex has been fully determined. The monomers have a planar, nearly parallel orientation. They deviate from parallel by 13.6 de grees, and the tilt moves the oxygen end of the N2O closer to the acetylene , The centers of mass of the two monomers are separated by 3.2961(8) Angstr om. The dipole moment of the HCCH .(N2O)-N-15 isotope has been measured, gi ving mu(a) = 0.0915(7) D, mu(b) = 0.1503(19) D, and mu(tot) = 0.1759(16) D. The conclusions of this work refine previous experimental and semiempirica l studies. New semiempirical calculations using a different model agree wel l with the current results.