Microwave spectrum and structure of the (CO2)(2)N2O complex

The structure of the weakly bound complex (CO2)(2)N2O has been determined. The spectra of seven isotopic species have been measured by pulsed nozzle F ourier transform microwave spectroscopy. The rotational constants for the n ormal species are A=1597.458(3) MHz, B = 1232.969(2) MHz and C = 831.095(1) MHz. The structure resembles a cylinder with the three monomers roughly pa rallel to each other and is similar to the observed structures of (CO2)(2)O CS and (OCS)(2)CO2. The CC distance is 3.521(9) Angstrom, and the CN distan ces are 3.427(9) Angstrom and 3.638(8) Angstrom. The dipole moment componen ts for the normal species are mu(a) = 0.16(4) D, mu(b) = 0.14(5)D and mu(c) = 0.130(2) D. The total dipole moment is 0.25(4) D. The structure of the c omplex is predicted quite well with a semi-empirical model that uses distri buted multipole moments to represent the electrostatic charge distribution and atom-atom terms to describe dispersion and repulsion.