Chaperone participation in three body ion association reactions. The systems COH++CO=(CO)2H+and N2H++N2=(N2)2H+

摘要

In an earlier study of the reactions (1) COH++CO+H2=(CO)2H++H2and (2) N2H++N2+H2=(N2)2H++H2it was observed that (1) was much faster than (2). On theoretical grounds the reactions are expected to have similar rates. A closer investigation of the reactions reveals that over a wide temperature and concentration range the products (CO)2H+lsqb;respectively, (N2)H+rsqb; are not formed by the normal three body reaction but by a parallel sequence (the chaperone sequence), i.e., COH++2H2=COH3++H2followed by COH3++CO=(CO)2H++H2for the COH+case. Significantly, for a wide range of conditions the chaperone complex COH3+(respectively, N2H3+) is at too low concentrations to be detected, and the rate law is the same as that for the direct three body reactions. Unraveling the kinetics of the reactions led to determination of the rate constants for the direct and chaperone reactions.