Stabilization of dichalcogenide ligands in the coordination sphere of a ruthenium system.

The synthesis, structure and electronic properties of tetraruthenium dichalcogenide complexes displaying the exclusive coordination mode of dichalcogenide ligands have been discussed. The reactions of Li[BH2E3] (E = S or Se) with [ClRu(mu-Cl)(p-cymene)](2) (p-cymene = eta(6)-{p-C6H4(Pr-i)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru2Cl2(p-cymene)(2)}(2)(mu(4),eta(2)-E-2)], 1-2 (E = S (1) and Se (2)). The solid-state X-ray structure of 1 shows that two {(p-cymene)RuCl}(2) moieties are bridged by a S-S bond. In addition to 2, the reaction of Li[BH2Se3] with [ClRu(mu-Cl)(p-cymene)](2) also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se-7(BH)(3)}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D-3 symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(mu-Cl)Cl](2) with Li[BH2S3] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)(2){mu-S-n(BH)(2)}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)(2)(mu,eta(2):eta(2)-S-2)(mu,eta(1):eta(1)-S-2)] and [(RuCp*)(2)(mu-SBHS-kappa B-1:kappa S-2:kappa S-2)(mu,eta(1):eta(1)-S-2)]. Complexes 1-5 have been characterized by multi-nuclear NMR, IR, UV-vis spectroscopy, and mass spectrometry and their molecular formulations (except 2) have been determined by single crystal X-ray crystallography. Furthermore, DFT calculations were performed that rationalize the stabilization of the dichalcogenide units (E-2(2-)) by the tetrametallic systems in 1-2.