The rotational spectra, potential function, Born–Oppenheimer breakdown, and hyperfine structure of GeSe and GeTe

Heavier congeners of CO and CO2 as ligands: from zero-valent germanium ('germylone') to isolable monomeric GeX and GeX2 complexes (X = S, Se, Te)

The first isolable germanium chalcogenide complexes 2–5 representing heavier congeners of CO and CO₂ were synthesised from the germylone adduct 1.

In contrast to molecular CO and CO₂, their heavier mono- and dichalcogenide homologues, EX and EX₂ (E = Si, Ge, Sn, Pb; X = O, S, Se, Te), are important support materials (e.g., SiO₂) and/or semiconductors (e.g., SiS₂) and exist typically as insoluble crystalline or amorphous polymers under normal conditions. Herein, we report the first successful synthesis and characterisation of an extraordinary series of isolable monomeric GeX and GeX₂ complexes (X = S, Se, Te), representing novel classes of compounds and heavier congeners of CO and CO₂. This could be achieved by solvent-dependent oxidation reactions of the new zero-valent germanium (‘germylone’)–GaCl₃ precursor adduct (bis-NHC)Ge⁰→GaCl₃1 (bis-NHC = H₂C[{NC(H) Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C(H)N(Dipp)}C:]₂, Dipp = 2,6-iPr₂C₆H₃) with elemental chalcogens, affording the donor–acceptor stabilised monomeric germanium(iv) dichalcogenide (bis-NHC)Ge^IV( Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> X) Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> X→GaCl₃ (X = S, 2; X = Se, 3) and germanium(ii) monochalcogenide complexes (bis-NHC)Ge^II Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> X→GaCl₃ (X = Se, 4; X = Te, 5), respectively. Moreover, the reactivity of 4 and 5 towards elemental sulphur, selenium, and tellurium has been investigated. In THF, the germanium(ii) monoselenide complex 4 reacts with activated elemental selenium to afford the desired germanium(iv) diselenide complex 3. Unexpectedly, both reactions of 4 and 5 with elemental sulphur, however, lead to the formation of germanium(iv) disulfide complex 2 under liberation of elemental Se and Te as a result of further oxidation of the germanium centre and replacement of the Se and Te atoms by sulphur atoms. All novel compounds 1–5 have been fully characterised, including single-crystal X-ray diffraction analyses, and studied by DFT calculations.

Theoretical analysis of NMR shieldings in XSe and XTe (X = Si, Ge, Sn and Pb): the spin-rotation constant saga

How the electronic contribution to the spin-rotation constant is close to the paramagnetic contribution of the NMR absolute shielding constant?