. . . . . . . . . "Cyclopentadienylchromium tricarbonyl dimer" . . "cyclopentadienyl chromium" . "Cyclopentadienylchromium tricarbonyl dimer" . "cyclopentadienylchromium tricarbonyl dimer" . . . "carbonyl dimer" . . "Bis(tricarbonylcyclopentadienylchromium)" . "bis(tricarbonyl[\u03B75-cyclopentadienyl]chromium)(Cr\u2014Cr)" . .