Chrome compounds have been discovered which demonstrate impressive cytotoxicity as well as a remarkable ability to inhibit tubulin polymerization. Such compounds as well as related derivatives are excellent clinical candidates for the treatment of cancer in humans. In addition, certain of these ligands, as pro-drugs, may well prove to be tumor selective vascular targeting chemotherapeutic agents or to have vascular targeting activity resulting in the selective prevention and/or destruction of nonmalignant proliferating vasculature.