The syntheses of cycloheptadienyl complexes of chromium and molybdenum are described. Addition of potassium triethylborohydride to [(eta(6)-C7H8)M(CO)(3)] (M = Cr or Mo) gave the salts K[(eta(5)-C7H9)M(CO)(3)] (M = Cr or Mo), which reacted with Me(3)SnCl and Ph(3)SnCl to form [(eta(5)-C7H9)M(CO)(3)SnR(3)] (M = Cr or Mo, R = Me, Ph). Treatment of K[(eta(5)-C7H9)M(CO)(3)] with N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) gave [(eta(5)-C7H9)M(CO)(2)(NO)] (M = Cr or Mo).