ABINITIO VIBRATION-ROTATION COUPLING-CONSTANTS AND THE EQUILIBRIUM GEOMETRIES OF NCCN AND CNCN

The equilibrium geometries of NCCN and CNCN were calculated from experimental ground-state rotational constants and ab initio values for the vibration-rotation coupling constants. For NCCN, R1e(NC) = 1.1578(5) angstrom and R2e(CC) = 1.3839(5) angstrom were obtained, where estimated error bars are given in parentheses. The calculated equilibrium bond lengths of CNCN are R1e(CN) = 1.1813(5) angstrom, R2e(NC) = 1.3116(5) angstrom and R3e(CN) = 1.1581(5) angstrom. Ground-state rotational and centrifugal distortion constants are predicted with high accuracy for various isotopomers of NCCN.