ESR investigation of the cation radicals 14N2 13CO+, 15N2 12CO+, and 15N2 13CO+: The trapping of ion–neutral reaction products in neon matrices at 4 K

Abstract

ESR results are reported for the cation radicals 15 N212 CO+ , 15 N213 CO+ and 14 N213 CO+ trapped as isolated ions in neon matrices at 4 K. The N2CO+ radical was generated by codepositing N2 and CO into a neon matrix under ionizing conditions (both photoionization at 16.8 eV, and 50 eV electron bombardment). A complete resolution of the 14 N, 15 N, and 13 C A tensors reveal that the radical is planar and nonlinear (NNC O). Electronic structure changes that occur as N+2 and CO (or CO+ with N2) combine to form N2CO+ are analyzed by comparing the nuclear hfs of the diatomic reactants with that of the product radical. The 13C hfs is extremely large with Ax =1376(1); Ay =1407(1), and Az =1403(1) MHz. The A tensor for the inner 14 N atom is: Ax,y =200.2(6) and Az =226.6(3) MHz. The outer 14 N has ‖Ax,y‖ =4(1) and Az =9.4(2) MHz. The nuclear g tensor appears axially symmetric with gx,y=2.0007(3) and gz =2.0002(3). SCF calculations also show N2 CO+ to be nonlinear and yield A values in reasonably good agreement with experiment. These ESR results for N2CO+ are compared with similar measurements for the isoelectronic ions C2O+2, N+4, and C2N−2.