An investigation of the molecular geometry and electronic structure of nitryl chloride by a combination of rotational spectroscopy and ab initio calculations

摘要

The ground-state rotational spectra of the six isotopomers (O2NCl)-O-16-N-14-Cl-35, (O2NCl)-O-16-N-14-Cl-37, (OONCl)-O-18-O-16-N-14-Cl-35, (O2NCl)-O-18-N-14-Cl-35, (O2NCl)-O-16-N-15-Cl-35, and (O2NCl)-O-16-N-15-Cl-37 of nitryl chloride were observed with a pulsed-jet, Fourier-transform microwave spectrometer to give rotational constants, Cl and N-14 nuclear quadrupole coupling, and spin-rotation coupling constants. These spectroscopic constants were interpreted to give r(0), r(s), and r(m)((2)) versions of the molecular geometry and information about the electronic redistribution at N when nitryl chloride is formed from NO2 and a Cl atom. The r(m)((2)) geometry has r(N-Cl)=1.8405(6) A, r(N-O)=1.1929(2) A, and the angle ONO=131.42(4)degrees, while the corresponding quantities for the r(s) geometry are 1.8489 A, 1.1940 A, and 131.73 degrees, respectively. Electronic structure calculations at CCSD(T)/cc-pVXZ (X=T, Q, or 5) levels of theory were carried out to give a r(e) geometry, vibration-rotation corrections to equilibrium rotational constants, and values of the Cl-35 and N-14 nuclear hyperfine (quadrupole and spin-rotation) coupling constants in good agreement with experiment. The equilibrium geometry at the CCSD(T)/cc-pV5Z level of theory has r(N-Cl)=1.8441 A, r(N-O)=1.1925 A and the angle ONO=131.80 degrees. The observed rotational constants were corrected for the vibration-rotation effects calculated ab initio to yield semiempirical equilibrium constants which were then fitted to give the following semiempirical equilibrium geometry: r(N-Cl)=1.8467(2) A, r(N-O)=1.1916(1) A, and the angle ONO=131.78(3)degrees. (C) 2008 American Institute of Physics.