[RuCl3ind3] and [RuCl2ind4]: Two new ruthenium complexes derived from the tumor-inhibiting RuIII compound HInd (OC-6-11)-[RuCl4ind2] (ind = indazole)

Indazolium (OC-6-11)-tetrachlorobis(indazole) ruthenate(III), HInd (OC-6-11)-[RuCl4ind2], exhibits excellent results in different tumor models in vitro and in vivo. Substitution reactions of this ruthenium(III) complex are of special interest for a deeper understanding of its interactions with biologically occurring targets and its mode of action. The indazolium complex salt can be transformed to the neutral, meridionally configurated trisindazole complex (OC-6-21)-[RuCl3ind3] in solvents like tetrahydrofuran. The X-ray crystal structure of this complex could be solved (monoclinic space group P2(1)/n, a = 12.441(3), b = 10.415(3), c = 21.635(4) A°, ß = 105.02(1)°). In spite of the paramagnetic RuIII atom most of the coordinated indazole protons could be assigned with the help of two-dimensional NMR experiments. Additionally, a reduced reaction product of HInd (OC-6-11)-[RuCl4ind2] in the physiological solubilizer 2-pyrrolidone could be isolated and the X-ray crystal structure of this RuII complex, (OC-6-12)-[RuCl2ind4], crystallized with two 2-pyrrolidones, could be solved (monoclinic space group P2(1)/n, a = 12.139(2), b = 10.426(2), c = 14.426(3) A°, ß = 100.06(3)°). Œ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001.