The Redox Properties of Germylenes Based on Alkyl- and Aryl-Substituted Diethylenetriamines

In this work, a series of novel germylenes, RN(CH2CH2NR’)2Ge R′ = Ph, R = Et (1); R′ = Ph, R = Bn (2); R′ = Ph, R = t-Bu (3); R′ = R = Ph (4); R′ = Bn, R = Et (5); R′ = Bn, R = Bn (6); R′ = Et, R = Et (7); R′ = Et, R = Bn (8), based on 1,4,7-triazaheptanes have been obtained. The compositions and structures of the novel compounds were established by elemental analysis and 1H and 13C NMR in the solid state by X-ray diffraction analysis (1–4), and it has been shown that germylenes are monomeric. The redox properties of compounds 1–4 and previously obtained germylene 10 (R′ = C6F5, R = Bn) in acetonitrile were studied by cyclic voltammetry (CV), and their optoelectronic properties were studied by UV–vis absorption spectroscopy. The easily oxidizing properties of the presented germylenes have been determined. An analysis of frontier molecular orbitals was carried out for compounds 1–8, 10 (R′ = C6F5, R = Bn), 11 (R′ = C6F5, R = Me), and Lappert’s germylene, Ge[N(SiMe3)2]2. It has been established that the nature of the substituents on the nitrogen atoms covalently bonded to the germanium atom has a significant effect on the energy of the frontier molecular orbitals.