Synthesis, experimental and theoretical investigation of a new type nickel dithiolene complex

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(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-S_n(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 (E₂^2-) by the tetrametallic systems in 1-2.

Role of Metals and Thiolate Ligands in the Structures and Electronic Properties of Group 5 Bimetallic-Thiolate Complexes

Syntheses, structures, and electronic properties of group 5 metal-thiolate complexes that exhibit unusual coordination modes of thiolate ligands have been established. Room-temperature reaction of [Cp*VCl₂]₃ (Cp* = η⁵-C₅Me₅) with Na₅[B(SCH₂S)₄] led to the formation of [Cp*VO{(SCH₂)₂S}] (1). The solid-state X-ray structure of 1 shows the formation of six-membered l,3,5-trithia-2-vanadacyclohexane that adopted a chair conformation. In a similar fashion, reactions of heavier group 5 precursors [Cp*MCl₄] (M = Nb or Ta) with Na₅[B(SCH₂S)₄] yielded bimetallic thiolate complexes [(Cp*M)₂(μ-S){μ-C(H)S₃-κ²S:κ²S',S″}{μ-SC(H)S-κ²C:κ²S‴,S''''}] (3a: M = Nb and 3b: M = Ta). One of the key features of molecules 3a and 3b is the presence of square-pyramidal carbon, which is quite unusual. The reactions also yielded bimetallic methanedithiolate complexes [(Cp*Nb)₂(μ-S)(μ-SCH₂S-κ²S,S')(μ,η²:η²-BH₃S)] (2) and [(Cp*Ta)₂(μ-O)(μ-SCH₂S-κ²S,S')(μ-H){μ-S₂C(H)SCH₂S-κ²S″:κ²S‴,S''''}] (4). Complex 2 contains a methanedithiolate ligand that stabilizes the unsaturated niobaborane species. On the other hand, one ((mercaptomethyl)thio)methanedithiolate ligand {C₂H₄S₃} is present in 4, which is coordinated to metal centers and exhibits the {μ-κ²S″:κ²S‴,S''''} bonding mode. Along with the formation of 3b and 4, the reaction of [Cp*TaCl₄] with Na₅[B(SCH₂S)₄] yielded [(Cp*Ta)₂(μ-S){μ-(SBS)S(CH₂S)₂(BH₂S)-κ²B:κ²S:κ⁴S',S″,S‴,S''''}] (5) containing a trithiaborate unit (BS₃). Complex 5 consists of pentacoordinate boron that resides in a square-pyramidal environment. All the complexes have been characterized by multinuclear NMR, UV-vis spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies.

Structure-dependent electronic transition in a new type of π-electron delocalized multi-sulfur bis(dithiolene)nickel complex

Four new nickel bis(dithiolene) complexes were synthesized and characterized. The UV-vis-NIR spectra and DFT calculations indicate that their HOMO and LUMO energy levels are highly depended on the donating/withdrawing abilities of their substituents.