Si₉^4– Anions in Solution – Structures of the Solvates Rb₄Si₉·4.75NH₃ and [Rb(18‐crown‐6)]Rb₃Si₉·4NH₃, and Chemical Bonding in Si₉^4–

Abstract

Dissolving the ternary material K 6 Rb 6 Si 17 together with chelating ligands such as 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane), dibenzo-18-crown-6 (2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadecane) ]Rb 3 Si 9 ·4NH 3 . Single-crystal X-ray diffraction analysis reveals the presence of Si 9 4-anions, the existence of which in solution has been a matter of discussion until now. In both compounds, the Si 9 4-cages display slightly

Dissolving Silicides: Syntheses and Crystal Structures of New Ammoniates Containing Si5 2– and Si9 4– Polyanions and the Role of Ammonia of Crystallisation

“…Here we report about an ammoniate structure containing the rare Si 9 4− anion, which further consolidates the fact that this prototypical cluster may be [10], where, similar to the solid-state structure of Rb 12 Si 17 , four crystallographically independent Si 9 4− anions are present in the asymmetric unit, the compound discussed here only contains one crystallographically independent nonasilicide anion ( Fig. 1).…”

“…The [2.2.2]-cryptand, choline chloride, PPh 3 and Pt(PPh 3 ) 4 were dried in vacuo before use. K 6 Rb 6 Si 17 was prepared in glass ampoules according to the known procedure [10,11].…”

“…All these reaction options of bare tetrelide clusters have in common that the E 9 4− anions must be extractable from the solid state into solution without changing their electron count. A short time ago, we were able to show that this is also possible for the nonasilicide cluster Si 9 4− [10]. In the resulting solutions, a ligand exchange reaction leading to the first transition metal complex of a silicide could be performed [11].…”

“…Based on this observation and after comparing all relevant bond lengths and angles, the Si 9 4− anion in the new compound Rb 4 Si 9 · 5NH 3 can also be assigned approximately C 4v symmetry. Table 1 shows Si-Si distances of the Si 9 4− anions in the known ammoniate crystal structures of Rb 4 Si 9 · 4.75NH 3 [10], [Rb(18-crown-6)]Rb 3 Si 9 · 4NH 3 [10], and Rb 4 Si 9 · 5NH 3 presented here. The ratio of the diagonals of the non-capped quadrangular face, which ideally is one for a monocapped square antiprism, gives an indication of the degree of distortion.…”

Chemie mit substituentenfreien Silicium‐Clustern in Lösung – ein Übergangsmetallkomplex eines Polysilicid‐Anions

“…[21] Eine der größten Hürden für die Entwicklung einer Lö-sungschemie mit Silicium-Clusterionen ist die geringe Lös-lichkeit der M I 12 Si 17 -Phasen. Bisher ist das einzige geeignete Lösungsmittel flüssiger Ammoniak, [17][18][19] [25] [{1,2-C 6 H 4 (SiH 2 )-(SiH)} 2 Ni 2 (Me 2 PCH 2 CH 2 PMe 2 ) 2 ] 2.210-2.304 , [26] [{1,2-C 6 H 4 (SiH 2 )} 2 Ni(Me 2 PCH 2 CH 2 PMe 2 )] 2.252 und 2.290 . [27] Erste quantenchemische Berechnungen des zentralen…”