Addition of ethynylferrocene to transition-metal complexes containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand-in vitro cooperativity of a ruthenium compound on cellular uptake of an anticancer drug

The addition reactions of the 16e half-sandwich complexes (p-cymene) M(S2C2B10H10) (1S, M = Ru; 2S, M = Os) and Cp*Ir(E2C2B10H10) (3S, E = S; 3Se, E = Se) with ethynylferrocene lead selectively to the 18e complexes (p-cymene) Ru(S2C2B10H9)(H(2)CCFc) (Fc = ferrocenyl) (4S), (p-cymene) Os(S2C2B10H9)(H(2)CCFc) (5S), Cp*Ir(S2C2B10H9)(H(2)CCFc) (6S) and Cp*Ir(Se2C2B10H9)(H(2)CCFc) (6Se), in which the alkyne is regio-and stereoselectively inserted into one of the M-E bonds that may further lead to metal-induced B-H activation, hydrogen atom transfer from the carborane via the metal center to the inserted alkyne, and the generation of a M-B bond. In all complexes the S-eta(2)-(Fc) C-C and C-B(M) moieties occupy a cisoid position. The four new complexes are characterized by IR, MS, NMR spectroscopy and microanalysis, and the X-ray structural analysis of 4S is performed. 4S was observed to promote the uptake of anticancer drug daunorubicin in drug-resistant leukemia K562 cells.