The present invention involves the synthesis and use of new platinum compounds. These new platinum compounds are easy to encapsulate in liposomes at high efficiencies. They are further characterized as platinum (II) four coordinate complex having the formula: ##STR1## wherein R.sub.1 and R.sub.2 are carboxylato monoanions bearing a hydrophobic radical function or a single carboxylato dianion bearing a hydrophobic radical function and R.sub.3 is a vicinal diaminoalkane or vicinal diaminocycloalkane. The complex is substantially soluble in methanol or chloroform and substantially insoluble in water. Said complex may be incorporated into phospholipid liposomes. Such platinum complexes encapsulated in phospholipid liposomes are useful for chemotherapy of platinum complex-sensitive tumors.Board of Regents, University of Texas Syste
