Cycloheptatrienetricarbonylchromium Cycloheptatrienetricarbonylchromium (0) cykloheptatrientrikarbonylchromium pi-Cycloheptatrienetricarbonylchromium tricarbonyl((1,2,4,5,6-eta)-1,3,5-cycloheptatriene)-chromiu Tricarbonyl(eta-1,3,5-cycloheptatriene)chromium tricarbonyl-pi-cycloheptatrinylchromium tropilidenechromium tricarbonyl