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

Abstract

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)(H₂CCFc) (Fc = ferrocenyl) (4S), (p-cymene)Os(S₂C₂B₁₀H₉)(H₂CCFc) (5S), Cp*Ir(S₂C₂B₁₀H₉)(H₂CCFc) (6S) and Cp*Ir(Se₂C₂B₁₀H₉)(H₂CCFc) (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 carboranevia the metal center to the inserted alkyne, and the generation of a M–B bond. In all complexes the S-η²-(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.