Process for the preparation of an anti-tumor platinum (II)-complex

We disclose here processes for making Platinum complex of general formula (I) where in, the conformation of 1,2-diaminocyclohexane is cis, trans-l or trans-d isomer and R1 and R2 combinedly make dicarboxylic acid having formulae (II), (III) and (IV), here in, the two carboxylic acid groups are on the same or on vicinal carbon atoms, n is zero or an integer ranging from 1 to 5 and R3 is either hydrogen or a substituent with electron withdrawing or electron releasing effects exemplified by alkoxy, halo, and nitro groups by reacting a compound of formula M2PtX4 wherein X represents halogen atom such as Cl or Br or thiocyanate with (i) 1,2-diaminocyclohexane (ii) source of silver ion selected from a silver compound containing divalent anion in presence of a corresponding carboxylic acid of formula (II) or (III) or (IV) to get the compound of formula (I), purifying the said compound by treating with alkali metal iodide and isolating the title compound by any conventional methods. The preparation of the said compound involves, for the first time, the intermediate formation of cis-Diiodo-trans-l-1,2-diaminocyclohexane platinum(II) and biscarboylato-trans-l-1,2-diaminocyclohexane platinum(II).