Iodination of cisplatin adduct of Vitamin B12 [{B12}-CN-{cis-PtCl(NH3)2}]+

The reaction of the cisplatin-vitamin B12 adduct [{B12}-CN-{cis-PtCl(NH3)2}]+ with iodide results in the rapid substitution of one chloride and one ammonia ligand by iodide and the formation of [{B12}-CN-{trans-PtI2(NH3)}]. The analogues reaction with 131I gave only mono-substitution and represents a straight forward way for platinum mediated radiolabeling of B12.