Synthetic route to dinuclear platinum(II) complexes [{trans-PtCl(NH3)2}2(mu-L)]2+ (L = aliphatic or heterocyclic diamine) as potential antitumor agents, exploiting the mutual activation of hydroxido ligands and ammonium groups

Abstract

A simple and efficient method for the synthesis of potentially antitumor-active dinuclear platinum complexes of the general formula [{trans-PtCl(NH3)2}2(mu-L)]((n+2)+) (L = aliphatic or heterocyclic diamine; n = charge of L) is presented. The procedure is based on the mutual in situ activation of trans-[PtCl(OH)(NH3)2] and the linker L in the form of a diammonium salt. This synthetic pathway yielded the Farrell compound [{trans-PtCl(NH3)2}2{mu-NH2(CH2)6NH2}]Cl2 (BBR3005) in quantitative yield. Using the same procedure, we prepared the new pyrazolate-bridged compound [{trans-PtCl(NH3)2}2(mu-pz)]Cl, determined its X-ray structure, and tested its cytotoxicity against three wild-type and one cisplatin-resistant cell lines.