π-Bonded Dithiolene Complexes: Synthesis, Molecular Structures, Electrochemical Behavior, and Density Functional Theory Calculations

Abstract

The synthesis and X-ray molecular structure of the first metal-stabilized o-dithiobenzoquinone [Cp*Ir-o-(η(4)-C(6)H(4)S(2))] (2) are described. The presence of the metal stabilizes this elusive intermediate by π coordination and increases the nucleophilic character of the sulfur atoms. Indeed, the π-bonded dithiolene complex 2 was found to react with the organometallic solvated species [Cp*M(acetone)(3)][OTf](2) (M = Rh, Ir) to give a unique class of binuclear dithiolene compounds [Cp*Ir(C(6)H(4)S(2))MCp*][OTf](2) [M = Rh (3), Ir (4)] in which the elusive dithiolene η-C(6)H(4)S(2) acts as a bridging ligand toward the two Cp*M moieties. The electrochemical behavior of all complexes was investigated and provided us with valuable information about their redox properties. Density functional theory (DFT) calculations on the π-bonded dithiobenzoquinone ligand and related bimetallic systems show that the presence of Cp*M at the arene system of the dithiolene ligand increases the stability compared to the known monomeric species [Cp*Ir-o-(C(6)H(4)S(2)-κ(2)-S,S)] and enables these complexes Cp*Ir(C(6)H(4)S(2))MCp*][OTf](2) (3 and 4) to act as electron reservoirs. Time-dependent DFT calculations also predict the qualitative trends in the experimental UV-vis spectra and indicate that the strongest transitions arise from ligand-metal charge transfer involving primarily the HOMO-1 and LUMO. All of these compounds were fully characterized and identified by single-crystal X-ray crystallography. These results illustrate the first examples describing the coordination chemistry of the elusive o-dithiobenzoquinone to yield bimetallic complexes with an o-benzodithiolene ligand. These compounds might have important applications in the area of molecular materials.

A Convenient Approach to Luminescent Cyclometalated Platinum(II) Complexes with Organometallic π‐Bonded Benzenedithiolate

“…Indeed in a previous work we investigated the electrochemistry properties of [Cp*Ir‐ o ‐(C 6 H 4 S 2 ‐κ 2 ‐ S , S )] and the related dinuclear complex [Cp*Ir(η‐C 6 H 4 S 2 )IrCp*][OTf] 2 containing a π‐bonded bdt unit. The results demonstrated that the binuclear system becomes more stable and the bdt ligand is less easily oxidized when compared to the mononuclear iridium species [Cp*Ir‐ o ‐(C 6 H 4 S 2 ‐κ 2 ‐ S , S )] . We also notice that higher the conjugation in the C ^ N ligand in complexes 3 – 5 , the easier their reduction is (Table , entries 2–4).…”

Arene Ruthenium(II) Complexes as Low-Toxicity Inhibitor against the Proliferation, Migration, and Invasion of MDA-MB-231 Cells through Binding and Stabilizing c-myc G-Quadruplex DNA

“…The clear characterization of the structure of the complexes supported the elucidation of its possible anticancer mechanisms. 23 Inhibitory Activities of Arene Ru Complexes in Vitro. The antiproliferative activities of the synthetic Ru(II) complexes against various human cancer cell lines and normal MCF-10A human cells were evaluated by using the MTT assay.…”

“…The Ru­(II) atom was bound to the benzene ring, with an average Ru–C distance of 2.183(7) and 2.181(7) Å, whereas the average distance of Ru­(II) to the two chelating nitrogen atoms was 2.089(5) and 2.082(5) Å, respectively. The clear characterization of the structure of the complexes supported the elucidation of its possible anticancer mechanisms …”

Intramolecular CH Activation and Metallacycle Aromaticity in the Photochemistry of [FeFe]‐Hydrogenase Model Compounds in Low‐Temperature Frozen Matrices

“…The recognitiono fa romaticm etallacycle stationary points, although unexpected, is not necessarily surprising given the diversec hemistry of aromaticd ithiolene complexes. [40][41][42][43] This is, however,arare example of an aromatic dithiolenem etallacycle coordinating to another metal through its p structure.…”