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

Abstract

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(μ-Cl)(p-cymene)]2 (p-cymene = η6-{p-C6H4(iPr)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru2Cl2(p-cymene)2}2(μ4,η2-E2)], 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(μ-Cl)(p-cymene)]2 also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se7(BH)3}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D3 symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(μ-Cl)Cl]2 with Li[BH2S3] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)2{μ-Sn(BH)2}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)2(μ,η2:η2-S2)(μ,η1:η1-S2)] and [(RuCp*)2(μ-SBHS-κ1B:κ2S:κ2S)(μ,η1:η1-S2)]. 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 (E22−) by the tetrametallic systems in 1–2.