Oligosilanylsilatranes

Abstract

Oligosilanes with attached silatranyl units were obtained by reactions of potassium oligosilanides with a silatranyl triflate. Interaction between Si and N atoms was observed in the 29Si NMR spectra (upfield-shifted SiO3 resonances) and in the solid-state structures (Si–N distances between 2.29 and 2.16 Å). The Si–N interaction can be “switched off” either by protonation of the nitrogen lone pair or by potassium silanide formation caused by trimethylsilyl group cleavage in the presence of potassium tert-butoxide.

Electron Transfer and Modification of Oligosilanylsilatranes and Related Derivatives

“…As our previous studies on oligosilanes and germanes have relied on the facile trimethylsilyl group abstraction using KO t Bu, we were pleased to find that compounds 1 and 1a smoothly undergo reactions with KO t Bu in the presence of 18-crown-6 to form the respective silanide 2 (17) and germanide 2a (Scheme 2). Again 2 and 2a are very similar with respect to their spectroscopic properties.…”

“…Again the structures of 2 and 2a are very similar, both crystallizing in the monoclinic space group P 2 1 / n with nearly identical cell parameters. 17 …”

“…14 After the first studies by Zaitsev et al, addressing germylated germatranes, 15 and Yamamoto et al, studying the potential of silylated silatranes as silyltransfer regents, 16 we have disclosed our initial studies on oligosilylated silatranes including some derivatization chemistry. 17 In the current account we wish to extend this.…”

Incorporating Methyl and Phenyl Substituted Stannylene Units into Oligosilanes. The Influence on Optical Absorption Properties

“…From our studies on the σ-bond electron delocalization of oligosilanes and germaoligosilanes [14,15,16,17,18,19,20,21] we have learned that that tris(trimethylsilyl)silyl terminated methyloligosilanes exibit a strong preference for transoid conformations in the solid state and in solution. Increasing the lengths of the main chain results in bathochromic shifts of the low-energy (σ→σ*) transition indicating extension of the delocalized system.…”

“…Our group and others have shown that oligosilanes with large end groups exhibit a preference to acquire a transoid conformation as long as the end groups are not too far apart from each other [14,15,16,17,18,19,20]. In a recent study we reported on the influence of the formal replacement of silicon atoms in oligosilanes by germanium atoms on the σ-electron delocalization properties, which was found to be rather negligible [21].…”