Synthesis, structure and physicochemical properties of the boron rich PtII complexes [(CN)2dppPtCl(CBT)] and [(CN)2dppPt(CBT)2] (CBT = m-carborane-1-thiolate)

Abstract

The present report deals with the synthesis of the two PtII complexes of respective formula cis-[(CN)2dppPtCl(CBT)]ˑ0.5(CH3)2CO and cis-[(CN)2dppPt(CBT)2] (dpp = 2,3-di(2-pyridyl)pyrazine; CBT = m-carborane-1-thiolate anion) the structure of both of them elucidated by single-crystal X-ray work and further examined by IR spectral behavior. These “low-molecular weight” mono- and bis-CBT derivatives may represent members of the restricted area of potential anticancer agents in BNCT (boron neutron capture therapy). Although insoluble in water, these new species are enough soluble in organic low-donor solvents like DMSO, CH3CN, THF, and solution studies in these solvents have allowed their physicochemical characterization by UV–visible and NMR measurements. Of relevant interest is the observed absorption present in the UV–visible spectrum of both species in the three solvents positioned in the region 400–500 nm, intimately related to the presence of CBT in both the cis-arranged species, similarly to what observed in previously published strictly related analogs.