Easily electroreducible halogen-free germanium complexes with biologically active pyridines

The Redox Properties of Germylenes Stabilized by N‐Donor Ligands

“…It is known that pyridine has extremely low electron affinity (−0.62 eV [24] ), which makes it difficult to reduce electrochemically (in particular, we found that it is irreversibly reduced at E p red =−2.990 V in acetonitrile). However, the withdrawing of electron density from it in donor‐acceptor bond allows us to expect that its reduction can be significantly facilitated (by analogy, for example, with derivatives of tetravalent germanium bonded to pyridine and its derivatives [25–27] ). Indeed, the CV curve of reduction of 2 shows a chemically irreversible peak at −2.256 V (Figure 2, Table 1), which is by 0.734 V (16.9 kcal mol −1 ) earlier than the reduction of pyridine.…”

Supramolecular D⋯A-layered structures based on germanium complexes with 2,3-dihydroxynaphthalene and N,N′-bidentate ligands

“…Density functional theory (DFT) calculations were performed using the Gaussian 16 program package 44 at the B3LYP/Def2TZVP level. The applied approximation was recently shown 30,31 to give accurate reproduction of the geometry, electronic and energy characteristics of germanium complexes with redox-active ligands. The stationary points on the potential energy surfaces were located by full geometry optimization with the calculation of the force constant matrix and checking for the stabilities of the DFT wave function.…”

“…29 The results obtained can be compared with the electroreduction of chlorogermanes in the presence of 2,2 0 -bipyridine, 10 where the potential shi for various objects was also about 1 V. Comparable values of potential shis are observed in case of nicotinamide and isoniazid and their complexes with 3,5-di-tert-butyl germanium catecholate. 30 In case of nicotinic acid 30 and 3-and 4-cyanopyridines, the potential shi is 0.4-0.6 V. 31 At the same time, in all cases, complete chemical reversibility of electroreduction is not observed.…”

Derivatives of penta-, hexa-, and hepta-coordinated tin with Schiff bases and 1,10-phenanthroline: structure, redox and optoelectronic properties

“…For instance, it is possible to increase their availability, and thus, increase the reactivity of the compound, in particular, impart the desired redox properties, to reduce the band gap, thereby changing the semiconductor and optoelectronic properties, to fine-tune the catalytic behavior. The examples include the dramatic decrease in the reduction potential and the increase in the availability of LUMO of germanium derivatives in the presence of N-donors, 2–4 the preparation of D⋯A-layered structures based on germanium complexes with 2,3-dihydroxynaphthalene and N , N ′-bidentate ligands with a narrow HOMO/LUMO gap (∼2 eV), 5 the fine tuning of the germylene HOMO level in the presence of N, S, P, and O-donor ligands, which determines the ability of germylenes to participate in oxidative addition reactions. 6,7 The key methods in the listed studies of germanium coordination compounds are voltammetry and UV-vis spectroscopy, which, when used in combination, make it possible to experimentally quantify the position of the frontier orbitals of the substrate.…”