Experimental and theoretical study on the structure and formation mechanism of [C6H5Cum](-) (m=1-3)

The important intermediate phenyl-copper metal complexes [C6H5Cum](-) (m = 1-3), which are produced from the reactions between copper metal clusters formed by laser ablation and the benzene molecules seeded in argon carrier gas, are studied by photoelectron spectroscopy(PES) and density functional theory (DFT). Their structures and bonding patterns are investigated, which results in the conclusion that C6H5 groups bond perpendicularly on copper clusters through Cu-C sigma bond. The formation mechanism of these complexes has been studied at B3LYP//6-311G(d, p)/Lanl2dz level. Direct insertion reaction between [Cu-m](-) and C6H6 yields intermediate complex [C6H5CumH](-), and then eliminates the H atom, or releases the H atom to other neutral Cu atoms or anionic Cu ions via H abstraction reaction. The first step is the rate-limiting step with C-H activation and cleavage, and H abstraction by neutral Cu atom is the most energetically favorable pathway for the final step. Moreover, the complex [C6H5Cu2](-) is ascertained to be easier to be generated than [C6H5Cu3](-) and [C6H5Cu](-), which are in excellent agreement with the experimental results