Fourier Transform Infrared Studies of Atomic Ti, V, Cr, Fe, Co, Ni, and Cu Reactions with Carbon Dioxide in Low-Temperature Matrices

Article abstract of DOI:10.1021/j100319a020

Titanium, vanadium, chromium, iron, cobalt, nickel, and copper metal atoms were cocondensed with CO2 is neat matrices at 15 K.Even though a large proportion of atoms do not react, new complexes with CO2 are characterized by using FTIR techniques and their infrared absorption bands are assigned.It is clearly shown that CO2 is highly bent in these complexes.The behavior of oxophile metals is different from that of other metals which spontaneously form 1:1 complexes with CO2.For Ti, V, and Cr, we observe first an insertion of metallic atom into a CO bond, leading to the formation of the intermediate (O)M(CO) molecule, followed by the CO2 fixation on this complex, to form (O)M(CO)(CO2).The other identified products in the matrices are CO, M(O), M(CO)n, and possibly a few carbonates.Most complexes are thermally unstable and decompose above 60 K.Only Fe and Ni compounds give rise upon annealing above 80 K to CO2 reduction to CO along with the simultaneous formation of metal carbonyl complexes.Isotopic experiments with 13CO2 and C(18)O2 allows us to conclude that the geometry of complexes is both metal and matrix dependent: in neat CO2 matrices, Fe and Co lead to a C coordination , the others being fixed in a side-on or end-on manner.