Chiral Spirocyclic Germanium Thiolates – An Evaluation of Their Suitability for Twin Polymerization based on A Combined Experimental and Theoretical Study. Issue 6 (9th May 2016)

• Record Type: Journal Article
• Authors: Kitschke, Philipp; Rüffer, Tobias; Lang, Heinrich; Auer, Alexander A.; Mehring, Michael
• Is Part Of: ChemistrySelect. Volume 1:Issue 6(2016)
• Page Start: 1184
• Page End: 1191
• Publication Date: 2016-05-09
• Subjects: Spirocyclic germanium thiolates -- twin polymerization -- reactivity study -- organic-inorganic hybrid materials -- X-ray diffraction analysis; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201600314
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: The spirocyclic germanium thiolates, 4 H, 4' H ‐2, 2'‐spirobi[benzo[ d ][1, 3, 2]dithiagermine] (1 ), 4 H, 4' H ‐2, 2'‐spirobi[benzo[ d ][1, 3, 2]oxathiagermine] (2 ) and 4 H, 4' H ‐2, 2'‐spirobi[benzo[ e ][1, 3, 2]oxathiagermine] (3 ) were synthesized and fully characterized. Compound3 crystallizes as racemic conglomerate, whereas1 and2 give racemates in the solid state. Their reactivity towards twin polymerization (TP) was tested. The studies with regard to proton‐assisted TP revealed a significantly reduced reactivity as compared to the recently reported silicon derivative, 4 H, 4' H ‐2, 2'‐spirobi[benzo[ d ][1, 3, 2]dioxasiline] (A ). DFT−D calculations were performed for1–3 and the model compound 4 H, 4' H ‐2, 2'‐spirobi[benzo[ d ][1, 3, 2]dioxagermine] (4 ) to evaluate the first reaction step initiating the processes of proton‐assisted TP. Compound4 with germanium bound to four oxygen atoms proved to be the most reactive precursor, but its synthesis failed. As indicated by the DFT−D calculations, compounds1 and2 are not suitable for TP. Starting from compound3 a germanium and sulfur containing organic‐inorganic hybrid material was obtained by thermal annealing. Abstract : Studies on the reactivity of a whole series of novel spirocyclic germanium thiolates towards thermally induced as well as proton‐ assisted twin polymerization (TP) are presented. A discussion based on experimental results and DFT‐D calculations with regard to their suitability for twin polymerization is given. A hybrid material consisting of phenolic resin, GeO2 and sulfur‐containing species e.g., GeS2, was obtained by thermal annealing of compound3 .