The synthesis of the dinuclear sulfide derivative [Ti(η⁵-C₅Me₅)Cl(μ-S)]₂ led to the formation of a series of dimetallic alkyl/aryl/amide sulfide-bridged complexes of titanium, [Ti(η⁵-C₅Me₅)R(μ-S)]₂. Hydrogenolysis, using phenyl and trimethylsilyl moieties, resulted in the quantitative generation of the Ti(III) tetrametallic sulfide cluster [Ti(η⁵-C₅Me₅)(μ₃-S)]₄. Alternatively, the treatment of the dimethylamide complex with SiH₃Ph, and the reaction of [Ti(η⁵-C₅Me₅)Cl(μ-S)]₂ with MgCl(C₃H₅), led to the formation of mixed-valence dinuclear systems.

Abstract

A series of dinuclear sulfur-bridged titanium derivatives [Ti(η⁵-C₅Me₅)R(μ-S)]₂ (R=NMe₂ (1), Ph (2), CH₂Ph (3), CH₂SiMe₃ (4)) has been synthesized from the reaction of [Ti(η⁵-C₅Me₅)Cl(μ-S)]₂ with the corresponding lithium salt or Grignard reagent. Formulation of 1–4 as symmetric dimers has been confirmed by crystallographic studies. The analogous reaction with Mg(C₃H₅)Cl afforded the paramagnetic mixed-valence Ti(III)/Ti(IV) compound [{Ti(η⁵-C₅Me₅)(μ-S)}₂(μ-C₃H₅)] (5). Contrasting with complexes 1–4, compound 5 exhibits a bridging μ-CH₂CHCH₂ fragment between the titanium atoms, which prevents the formation of a planar Ti₂S₂ core in the solid-state structure. Complex 1 reacts with SiH₃Ph to give [{Ti(η⁵-C₅Me₅)(μ-S)}₂(μ-NMe₂)] (6), a paramagnetic mixed-valence Ti(III)/Ti(IV) compound, structurally and electronically similar to 5. Under mild conditions, treatment of compounds 3 and 4 with H₂ (1 atm) generates quantitatively the Ti(III) tetrametallic sulfide cluster [Ti(η⁵-C₅Me₅)(μ₃-S)]₄, along with the corresponding alkane.

In this report, a Cu(II) complex Cu-L4 containing a new tetradentate benzotriazole-appended bipyridine ligand was synthesized and characterized fully via spectroscopic and crystallographic techniques. The crystal structure of the complex revealed that the ligand is bound to copper in a tetradentate fashion in a plane and the axial positions are occupied by an anion and a solvent molecule, resulting in a distorted octahedral geometry of the complex in solid-state. This air-stable complex was utilized as homogeneous precatalyst for the synthesis of several propargylamine derivatives by 3-component A3 coupling reactions of aldehydes, amines, and alkynes under aerial atmosphere.

The cytotoxicity, protein binding affinity, interactions with DNA, spectral and structural features of two new Ru(II) compounds, [RuCl(η⁶-p-cymene)(3-DNPH)] chlorido(η⁶-p-cymene)(3-nitrophenylhydrazine-k² N,N′)ruthenium(II) and [RuCl(η⁶-p-cymene)(3-CNPH)] chlorido(3-chlorophenylhydrazine-k² N,N′)(η⁶-p-cymene)ruthenium(II), are examined experimentally and theoretically.

Abstract

Ru(II)-arene compounds are being investigated as anticancer agents due to the biocompatibility of ruthenium and their structural diversity. Two newly synthesized Ru(II) complexes, [RuCl(η⁶-p-cymene)(3-DNPH)] (chlorido(η⁶-p-cymene)(3-nitrophenylhydrazine-k² N,N′)ruthenium(II)) (1) and [RuCl(η⁶-p-cymene)(3-CNPH)] (chlorido(3-chlorophenylhydrazine-k² N,N′)(η⁶-p-cymene)ruthenium(II)) (2), are experimentally (IR, NMR) and theoretically (B3LYP/6-31+G(d,p)(H,C,N,Cl)/LanL2DZ(Ru)) characterized. Experimental and theoretical values of ¹H and ¹³C chemical shifts and position of the most intense vibrational bands showed high correlation coefficients and low mean absolute errors, proving the predicted structure and applicability of the selected level of theory. Cell viability studies performed on MDA-MB-468, BT-474, and PC3 cells using MTT and CV assay indicated the activity of the second complex similar to the activity of cisplatin towards BT-474 breast cancer cells. The spectrofluorimetric measurements of Bovine Serum Albumin showed the binding process‘s spontaneity of complexes and protein, with a binding energy of around −30 kJ mol⁻¹. Detailed molecular docking analysis allowed the elucidation of the binding mechanism through specific intermolecular interactions. Both compounds showed a higher affinity towards BSA than naproxen and cisplatin. Molecular docking simulations proved the spontaneity of the complexes binding to DNA. Based on these promising results, further biological examinations of these compounds are advised.

The Front Cover shows a conceptual approach to the production of organophosphorus compounds in accordance with the main principles of “green chemistry” based on atom-economic click reactions of intermolecular insertion of various organic molecules into the phosphorus−phosphorus bond. The scope of the elaborated method is represented by a chamomile flower with organic substrates on the petals painted in the colors of the national flags of the international research team. The hard-working bees and butterflies bringing organic substrates represent the scientists who developed this type of unique chemistry. The ample opportunities of this powerful and environmentally friendly tool for the preparation of organophosphorus derivatives are shown by the great Volga River on the main background of the image. More information can be found in the Review by E. Hey-Hawkins, D. Yakhvarov, and co-workers.