In order to study the effects of a number of CO group on the Mo(CO)_n-C_6H_6 interactions,the structures of(η~x-C_6H_6)Mo(CO)_n (χ=1-6;n=1-5) complexes were studied by using the density functional theory B3LYP method with LANL2DZ basis set.Nature bond orbital(NBO) analyses were also performed to explain the nature of the Mo(CO)_n-C_6H_6 interactions.The conclusions can be drawn as follows:(1) the most stable geometries of Mo(CO)_n-C_6H_6 complexes are the configuration of(η~6-C_6H_6)Mo(CO)_n when n value is from 1 to 5.T...