“…The driving force for the studies on organometallics as reagents to fight cancer has certainly been the promising results already obtained for several organotransition-metal compounds which have been evaluated for their therapeutic properties. Dichloride metallocenes (Cp 2 MCl 2 , M = Ti, V, Nb, Mo, Cp = g 5 -cyclopentadienyl) have shown to exhibit antitumor activity against numerous experimental tumors, e.g., Ehrlich ascites tumor, B 16 melanoma, colon 38 carcinoma and Lewis lung carcinoma, as well as against several human tumors heterotransplanted to athymic mice [2]; titanocene dichloride was already in Phase II clinical trials [3], however it was recently abandoned due to problems of formulation [4,5]. Ferrocene derivatives also showed activity against Rauscher leukemia virus and EAT in CF1 mice [6,7] and in P388 leukemia cells [8] reinoculated tumors [9].…”