Specially designed hexachlorine-containing cobalt(II) tris-dioximate clathrochelates were found to efficiently electrocatalyze the production of molecular hydrogen from H⁺ ions without the overpotential of this process.

The cycloaddition of the mono- and dichloroglyoximes to the cobalt(II) bis-α-benzyldioximate afforded the cobalt(II) mono- and dichloroclathrochelates in moderate yields (40–60%). These complexes undergo nucleophilic substitution of their reactive chlorine atoms with aliphatic amines, alcohols and thiolate anions. In the case of ethylenediamine and 1,2-ethanedithiol, only the macrobicyclic products with α,α′-N₂- and α,α′-S₂-alicyclic six-numbered ribbed fragments were obtained. The cobalt(II) cage complexes with terminal mercapto groups were synthesized using aliphatic dithiols. The crystal and molecular structures of the six cobalt(II) clathrochelates were obtained by X-ray diffraction. Their CoN₆-coordination polyhedra possess a geometry intermediate between a trigonal prism and a trigonal antiprism, and the encapsulated cobalt(II) ions are shifted from their centres due to the structural Jahn–Teller effect with the Co–N distances varying significantly (by 0.10–0.26 Å). The electrochemistry of the complexes obtained was studied by cyclic voltammetry (CV). The anodic waves correspond to the quasi-reversible Co^2+/3+ oxidations, whereas the cathodic ranges contain the quasi-reversibile waves assigned to the Co^2+/+ reductions; all the cobalt(I)-containing clathrochelate anions formed are stable in the CV time scale. The electrocatalytic properties of the cobalt complexes obtained were studied in the production of hydrogen from H⁺ ions: the addition of HClO₄ resulted in the formation of the same catalytic cathodic reduction Co^2+/+ waves. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H₂ in high Faraday yields. The efficiency of this electrocatalytic process was enhanced by an immobilization of the complexes with terminal mercapto groups on a surface of the working gold electrode.

The reactions of tetrachloroauric(III) acid (HAuCl₄) with the thioamides; 2-mercapto-benzothiazole (mbztH) and 5-ethoxy-2-mercapto-benzimidazole (EtmbzimH) lead to the desulfuration of the ligands and the formation of the ionic complexes {[AuCl₄]⁻[bztH₂]⁺} (1), and {[AuCl₄]⁻[EtbzimH₂]⁺(H₂O)} (2) (where bztH₂ ⁺ and EtbzimH₂ ⁺ are the desulfurated cations of the starting ligands). The reaction of HAuCl₄ with 2-mercapto-nicotinic acid (mnaH₂), however results in the formation of 2-sulfonate-nicotininc acid (C₆H₅NO₅S) (3) with the simultaneous oxidation of the sulfur atom. On the other hand, the reactions of the gold(I) complex [Au(tpp)Cl] (4) (tpp = triphenylphosphine (Ph₃P)) with the thioamides; 2-mercapto-thiazolidine (mtzdH), 2-mercapto-benzothiazole (mbztH) and 5-chloro-2-mercapto-benzothiazole (ClmbztH) in the presence of potassium hydroxide resulted in the formation of the gold(I) complexes of formulae [Au(tpp)(mtzd)] (5), [Au(tpp)(mbzt)] (6) and [Au(tpp)(Clmbzt)] (7) without ligand desulfuration. All complexes have been characterized by elemental analysis, FT-IR, far-FT-IR,¹H-NMR, spectroscopic techniques and X-Ray crystallography. The electrochemical behavior of 1, 2 and 4-7 complexes and the ligands EtmbzimH, mbztH and mnaH₂ was also studied in acetonitrile and DMF using cyclic voltammetry. The results are in support of a mechanism of desulfuration of the ligands by Au(III), involving a first oxidation of S to -SO₃ ⁻, followed by a C-S bond cleavage. This is also supported by PM6 calculations of bond dissociation energies of the various compounds involved. Complexes 1, 2 and 4-7 were tested for in vitro cytotoxicity against leiomyosarcoma cells and the results are discussed in relation with the geometry of the complexes and compared with those of cisplatin and other metals. Complexes 1 and 5 showed higher activity than that of cisplatin, while HAuCl₄ was inactive against sarcoma cells.

The nucleophilic substitution of six chlorine atoms of the n-butylboron-capped clathrochelate iron and cobalt(II) precursors with perfluoroarylthiolate anions afforded the hexaperfluoroarylsulfide macrobicyclic iron and cobalt(II) tris-dioximates. The complexes obtained are soluble in aromatic and aliphatic hydrocarbons as well as in polar aprotonic solvents due to the presence of the superhydrophobic fluorine-containing molecular periphery. As it follows from the X-ray data for five iron and cobalt mono- and bis-clathrochelates, the geometry of their macrobicyclic frameworks is affected by both the nature of an encapsulated metal ion and that of the ribbed substituents. Bis-capping fragment Co^IIO₆ of the Co^IIICo^IICo^III bis-clathrochelate possesses a trigonal antiprismatic geometry, all the Co^IIN₆ coordination polyhedra are trigonal-prismatic, and those of the encapsulated iron(II) and cobalt(III) ions are intermediate between them. The wide range of Co–N distances as well as the significant shifts of the encapsulated cobalt(II) ions from the centres of their N₆-coordination polyhedra were explained by the Jahn–Teller distortion. The EPR and magnetometry data are also characteristic of the low-spin cobalt(II) complexes with this distortion. The parameters of the ⁵⁷Fe Mössbauer spectra of the iron macrobicycles are characteristic of the low-spin iron(II) complexes. The cyclic voltammograms (CVs) for the complexes studied contain the one-electron oxidation and reduction waves assigned to metal-centered redox-processes. The Fe^{2+ /3+} and Co^{2+ /3+}oxidations are quasi-reversible or irreversible. The anionic clathrochelate species resulting from the reversible Co^{2+ /+}reductions are stable on the CV time scale, whereas their iron(I)-containing analogs are unstable.