Boron containing mono- and bis-carboranethiolate derivatives of respective formula [(bipy)MCl(CBT)] and [(bipy)M(CBT)2] (M = PdII, PtII)

Synthetic procedures are reported of the new “low molecular weight” mononuclear PdII and PtII derivatives of formula [(bipy)MCl(CBT)]⋅0.5CH3CN (M = PdII, PtII) and [(bipy)Pt(CBT)2] (CBT = m-carboranethiolate anion) evaluated of interest as potential anticancer agents in boron neutron capture therapy (BNCT). The structure of all three species has been elucidated by single-crystal X-ray work and further examined by IR and UV–visible spectral behavior. The detailed presentation of the spectral response for all of them in solution of low-donor nonaqueous solvents (CH3CN, DMF, DMSO) evidences the presence of a broad absorption in the region 400–500 nm, already previously observed for the species cis-[(bipy)Pd(CBT)2], this absorption interpreted as due to the presence of one or two metal-CBT environments in the related cis-structurally arranged mono- and bis-CBT derivatives.