Bis(diphenylphosphino)methane copper(I) tetrahydroborate was synthesized by ligands exchange in bis(triphenylphosphine) copper(I) tetrahydroborate, and characterized by XRD, FTIR, NMR spectroscopy. According to XRD the title compound has dimeric structure, [(μ₂-dppm)₂Cu₂(η₂-BH₄)₂], and crystallizes as CH₂Cl₂ solvate in two polymorphic forms (orthorhombic, 1, and monoclinic, 2) The details of molecular geometry and the crystal-packing pattern in polymorphs were studied. The rare Twisted Boat-Boat conformation of the core Cu₂P₄C₂ cycle in 1 is found being more stable than Boat-Boat conformation in 2.

A series of phenylsilsesquioxane-benzoate heptacopper complexes 1–3 were synthesized and characterized by X-ray crystallography. Two parallel routes of toluene spontaneous oxidation (into benzyl alcohol and benzoate) assisted the formation of the cagelike structure 1. A unique multi-ligation of copper ions (from (i) silsesquioxane, (ii) benzoate, (iii) benzyl alcohol, (iv) pyridine, (v) dimethyl-formamide and (vi) water ligands) was found in 1. Directed self-assembly using benzoic acid as a reactant afforded complexes 2–3 with the same main structural features as for 1, namely heptanuclear core coordinated by (i) two distorted pentameric cyclic silsesquioxane and (ii) four benzoate ligands, but featuring other solvate surroundings. Complex 3 was evaluated as a catalyst for the oxidation of alkanes to alkyl hydroperoxides and alcohols to ketones with hydrogen peroxide and tert-butyl hydroperoxide, respectively, at 50 °C in acetonitrile. The maximum yield of cyclohexane oxidation products as high as 32% was attained. The oxidation reaction results in a mixture of cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone. Upon the addition of triphenylphosphine, the cyclohexyl hydroperoxide is completely converted to cyclohexanol. The specific regio- and chemoselectivity in the oxidation of n-heptane and methylcyclohexane, respectively, indicate the involvement of of hydroxyl radicals. Complex 3 exhibits a high activity in the oxidation of alcohols.

Two novel ruthenocene-based pincer palladium tetrahydroborates were characterized by XRD, NMR and FTIR. The alcoholysis of Pd(II) tetrahydroborate LPd(BH₄) (L = κ³-[{2,5-(^tBu₂PCH₂)₂C₅H₂}Ru(C₅H₅)]) yields the dinuclear cationic Pd(II) tetrahydroborate with the bridging BH₄ ⁻ ligand [(LPd)₂(μ,η^1,2:η^1,2-BH₄)]⁺. The bifurcate dihydrogen-bonded complexes are the active intermediates of the first proton transfer in the step-wise alcoholysis of LPd(BH₄), yielding eventually [(LPd)₂(μ,η^1,2:η^1,2-BH₄)]⁺. According to the X-ray and DFT/M06 geometry analysis, the BH₄ ⁻ ligand in both palladium tetrahydroborates has a mixed coordination mode η^1,2. The possibility of BH₃-group abstraction from LPd(BH₄) by an excess of organic base (THF, Py) with the formation of hydride LPd^IIH is shown. This Pd(II) hydride is a very reactive compound able to rapidly capture CO₂ (ca. 15 min) converting into the formate complex LPd^II(η¹-OC(O)H). The hydrolysis of LPdH with subsequent CO₂ insertion yields a hydrocarbonate complex LPd^II(η¹-OC(O)OH). The hydrocarbonate complex forms hydrogen-bonded dimers in the crystal due to hydrogen bonds between the OC(O)OH fragments.

Driven by the growing threat of cancer, many research efforts are directed at developing new chemotherapeutic agents, where the central role is played by transition metal complexes. The proper ligand design serves as a key factor to unlock the anticancer potential of a particular metal center. Following a recent trend, we have prepared unsymmetrical pincer ligands that combine benzothiazole and thiocarbamate donor groups. These compounds are shown to readily undergo direct cyclopalladation, affording the target S,C,N-type Pd(II) pincer complexes both in solution and in the absence of a solvent. The solid-phase strategy provided the complexes in an efficient and ecologically friendly manner. The resulting palladacycles are fully characterized using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy and, in one case, by single-crystal X-ray diffraction (XRD). The solvent-free reactions are additionally analyzed by powder XRD. The pincer complexes exhibit remarkable cytotoxicity against several solid and blood cancer cell lines, including human colorectal carcinoma (HCT116), breast cancer (MCF7), prostate adenocarcinoma (PC3), chronic myelogenous leukemia (K562), multiple plasmacytoma (AMO1), and acute lymphoblastic leukemia (H9), with the dimethylamino-substituted derivative being particularly effective. The latter also induced an appreciable level of apoptosis in both parental and doxorubicin-resistant cells K562 and K562/iS9, vindicating the high anticancer potential of this type of palladacycles.

Platinum-based drugs are commonly recognized as a keystone in modern cancer chemotherapy. However, intrinsic and acquired resistance as well as serious side effects often caused by the traditional Pt(II) anticancer agents prompt a continuous search for more selective and efficient alternatives. Today, significant attention is paid to the compounds of other transition metals, in particular those of palladium. Recently, our research group has suggested functionalized carboxamides as a useful platform for the creation of cytotoxic Pd(II) pincer complexes. In this work, a robust picolinyl- or quinoline-carboxamide core was combined with a phosphoryl ancillary donor group to achieve hemilabile coordination capable of providing the required level of thermodynamic stability and kinetic lability of the ensuing Pd(II) complexes. Several cyclopalladated derivatives featuring either a bi- or tridentate pincer-type coordination mode of the deprotonated phosphoryl-functionalized amides were selectively synthesized and fully characterized using IR and NMR spectroscopy as well as X-ray crystallography. The preliminary evaluation of the anticancer potential of the resulting palladocycles revealed a strong dependence of their cytotoxic properties on the binding mode of the deprotonated amide ligands and demonstrated certain advantages of the pincer-type ligation.