Halogen-free GeO2 conversion: electrochemical reduction vs. complexation in (DTBC)2Ge[Py(CN)n] (n = 0…2) complexes

Abstract

3,5-di-tert-Butylcatecholate (DTBC) germanium complexes (DTBC)₂Ge[Py(CN)_n]₂ (n = 0…2) have been synthesized from GeO₂, 3,5-di-tert-butylcatechol and cyano-substituted pyridines Py(CN)_n and characterized by elemental analysis, NMR, IR and UV-VIS spectroscopy. The structure of 1 (with 4-cyanopyridine) has been determined by X-ray single crystal analysis. UV-VIS spectra have shown that these complexes are stable in CH₃CN, toluene and CH₂Cl₂ solutions; in contrast, they are rapidly decomposed by dimethylformamide and tetrahydrofuran. Complexes 1 and 2 (with 4-cyano and 3-cyanopyridine) are electrochemically reducible in toluene/1 M Bu₄NPF₆ at E = −1.3…−1.7 V vs. AgCl. The quantum-chemical study of these complexes is in accordance with the unsuccessful attempts to obtain analogous derivatives with 2-cyanopyridine and 2,6-dicyanopyridine.