ESR and ab initio theoretical studies of the cation radicals 12C216O+2, 12,13C216O+2,13C216O+2, 12C216,17O+2, 12C217O+2, and 12,13C216,17O+2 isolated in neon matrices at 4 K. The use of matrix isolation for trapping ion-neutral reaction products
Knight, L. B.; Steadman, J.; Miller, P. K.; Bowman, D. E.; Davidson, E. R.; Feller, D. ESR and ab initio theoretical studies of the cation radicals 12C216O+2, 12,13C216O+2,13C216O+2, 12C216,17O+2, 12C217O+2, and 12,13C216,17O+2 isolated in neon matrices at 4 K. The use of matrix isolation for trapping ion-neutral reaction products. J. Chem. Phys. 1984, 80, 4593-4593.
An experimental procedure for generating and trapping the products of ion-“neutral reactions has been developed. The method has been applied to a neon matrix ESR study of the C2O+ 2 radical (X-‰ 2 B u ) formed during deposition at 4 K by the reaction CO++CO. Six different isotopic combinations of C2O+ 2 were studied which allowed a complete characterization of the 1 3C and 1 7O nuclear hyperfine structure. The experimental Atensors were compared with the results of an extensive SCF and CI theoretical calculation. A full discussion of the theoretical procedure utilized is presented. The electronic ground state was determined by a CI calculation to be the planar t r a n s configuration with a CCO bond angle of 141Â°. A description of the MO containing the unpaired electron is presented and compared with CO+ and the isoelectronic anion radical C2Nâˆ’ 2. The effects of noncoincidence between the g and Atensors are considered in detail for this powder sample of C2O+ 2 which exhibited relatively narrow ESR lines in a neon matrix at 4 K. The observed g values were g x =2.0034(2), g y =2.0019(2), and g z =1.9912(2). The effective 1 3C A parameters observed in the principal gtensor axis system were A x =577(1), A y =606(1), and A z =583(1) MHz. Experimental estimates of A y z varied from about 7 to 32 MHz. The 1 7O Atensor had components of A x â‰Š0, --A y --=74(1) MHz and A z â‰Š0. Analysis of the gtensor for C2O+ 2 indicates the presence of a low lying excited electronic state (2 A u ) which is predicted at â‰Š18-‰000 cmâˆ’ 1 by an SCF theoretical calculation.
Journal of Chemical Physics