The formation of a stable triacylgermenolate 2 as a decisive intermediate was achieved by using three pathways. The first two methods involve the reaction of KO t Bu or alternatively potassium with tetraacylgermane 1 yielding 2 via one electron transfer. The mechanism involves the formation of radical anions (shown by EPR). This reaction is highly efficient and selective. The third method is a classical salt metathesis reaction toward 2 in nearly quantitative yield. The formation of 2 was confirmed by NMR spectroscopy, UV–vis measurements, and X-ray crystallography. Germenolate 2 serves as a starting point for a wide variety of organo-germanium compounds. We demonstrate the potential of this intermediate by introducing new types of Ge-based photoinitiators 4b – 4f . The UV–vis absorption spectra of 4b – 4f show considerably increased band intensities due to the presence of eight or more chromophores. Moreover, compounds 4d – 4f show absorption tailing up to 525 nm. The performance of these photoinitiators is demonstrated by spectroscopy (time-resolved EPR, laser flash photolysis (LFP), photobleaching (UV–vis)) and photopolymerization experiments (photo-DSC measurements).

The synthesis of stable triacylgermenolates 3 a,b was achieved by using a multiple silyl abstraction methodology. The formation of these new germenolates was confirmed by NMR spectroscopy and UV‐Vis measurements. Moreover, for the triacylgermenolates 2 and 3 a LIFDI mass spectrometry to characterize these new compounds. Germenolates 3 a,b serve as a starting point for a new triaacylgermane 4 a and two octaacyldigermanes 4 c,d. The formation of these acylgermanes was confirmed by NMR spectroscopy, X‐ray crystallography, UV‐Vis measurements and mass spectrometry. The UV‐Vis absorption spectra of 4 c,d show considerably increased band intensities due to the presence of eight chromophores.

The reduction of 1,1-dibromo-cyclopentasilane with a mildly reducing magnesium­(I) dimer [{(MesNacnac)­Mg−}2] was examined, which gave rise to the formation of endocyclic disilene 1. The formation of 1 was further confirmed by a trapping experiment with MeOH. Additionally, 1 was found to dimerize slowly to 1-dimer. Furthermore, the formation of the homocyclic silylene was demonstrated by performing the reduction in the presence of Et3SiH as a trapping agent. To prevent the 1,2-trimethylsilyl shift, which causes a rapid degradation of the silylene, a second synthetic strategy was established. Therefore, two different tetrasilanes 4 and 5 were synthesized. Compounds 4 and 5 were subsequently reacted with 2.1 equiv of trifluoromethanesulfonic acid to corresponding bis­(trifluoromethanesulfonates) 6 and 7. 1,4-Dihalo-tetrasilanes 8a,b and 9 as well as hexasilanes 10 and 11 were obtained by a subsequent nucleophilic substitution of the triflate substituent with X– (X = Cl–, Br–, or R3Si–). Dianionic species 12 and 13 were synthesized by the reaction of corresponding hexasilanes 10 and 11 with 2.1 equiv of KOt-Bu. Surprisingly, the salt metathesis reaction of dianionic compound 13 does not lead to the formation of the expected 1,1-halocyclopentasilanes. Instead the formation of cyclobutasilane 14 was observed. The reaction of 9 with lithium led again to the formation of 14 alongside with the formation of cyclohexasilane 15. Interestingly, 14 underwent a ring-opening formation by the reaction with gaseous HCl in the presence of AlCl3 and compound 16 was formed. The reduction of 16 allowed straightforward access to 17 as a structurally complex hitherto unknown tricyclic polysilane.

Sila-Peterson type reactions of the 1,4,4-tris-( t r i m e t h y l s i l y l ) -1 -m e t a l l o o c t a m e t h y l c y c l o h e x a s i l a n e s (Me 3 Si) 2 Si 6 Me 8 (SiMe 3 )M (2a, M = Li; 2b, M = K) with various ketones were investigated. The obtained products strongly depend on the nature of the ketone component. With 2-adamantanone 2a,b afforded the moderately stable silene 3. 3 is the first example of an Apeloig−Ishikawa−Oehme-type silene with the tricoordinate silicon atom incorporated into a cyclopolysilane framework and could be characterized by NMR and UV spectroscopy as well as by trapping reactions with water, methanol, and MeLi. The reaction of 2b with aromatic ketones also follows a sila-Peterson type mechanism with formation of carbanionic species. With 1,2-diphenylcyclopropenone 2b reacted by conjugate 1,4-addition to give a spirocyclic carbanion. In most cases the underlying reaction mechanism could be elucidated by the isolation and characterization of unstable intermediates and final products after proper derivatization.