[Si₄]^4– and [Si₉]^4– Clusters Crystallized from Liquid Ammonia Solution – Synthesis and Characterization of K₈[Si₄][Si₉]·(NH₃)_14.6

Abstract

The extraction of the silicide K 12 Si 17 with liquid ammonia in the presence of a sequestering agent and AuPPh 3 Cl or Zn(Cp*) 2 led to crystals of the solvate compound K 8 [Si 4 ][Si 9 ]·

Silicon Containing Nine Atom Clusters from Liquid Ammonia Solution: Crystal Structures of the First Protonated Clusters [HSi9]3– and [H2{Si/Ge}9]2–

“…However, both the deltahedral clusters present in the solid precursor, Si 9 and Si 4 , are stable in liquid ammonia for long periods, e.g. proven by crystallization of compounds 1 – 6 in this paper or by K 8 (Si 4 )(Si 9 ) · 14.6NH 3 , therefore an activation of at least one of these cluster anions is necessary. The kind of activation remains in the dark: all ingredients have been used in similar experiments, but did never result in a degradation of clusters before.…”

“…Nevertheless, some reactions were observed including a so far unique ammonolysis reaction leading to a hexaaminocyclotrisilazane anion, which is obviously proceeding via cleavage of Si–Si bonds. Which Si containing species from the starting compound, [Si 4 ] 4– or [Si 9 ] 4– , is degraded, remains unclear, but an activation has to occur because both species are stable in liquid NH 3 for longer times . Also the partial oxidation up to [Si 9 ] 3– was found, whereas the firstly assumed oxidized [Si 4.9 Ge 4.1 ] 2– ion turned out to be the twofold protonated [H 2 Si 4.9 Ge 4.1 ] 2– cluster anion.…”

“…Possibly the lower solubility of the A 12 E 17 phases compared to A 4 E 9 causes the relatively small number of compounds known to date. To the best of our knowledge, only a few solvates ((K[2.2.2]crypt) 3 Si 9 · 8NH 3 , (K[2.2.2]crypt) 3 Si 9 · 2.5py, [K(18‐crown‐6)] 2 Si 9 · py, Rb 4 Si 9 · 4.75NH 3 , [Rb(18‐crown‐6)]Rb 3 Si 9 · 4NH 3 , Rb 4 Si 9 · 5NH 3 , Rb 1.2 K 2.8 [Si 4 ] · 7NH 3 , K 8 [Si 4 ][Si 9 ] · 14.6NH 3 ) and even fewer examples for substituted silicide clusters, [PhZn(η 4 ‐Si 9 )] 3– , [Ni(CO) 2 (μ‐Si 9 ) 2 ] 8– ,, [NHC Dipp Cu(η 4 ‐Si 9 )] 3– , and [(MesCu) 2 (η 3 ‐Si 4 )] 4– , have been reported.…”

Anionic Siliconoids from Zintl Phases: R3Si9− with Six and R2Si92− with Seven Unsubstituted Exposed Silicon Cluster Atoms (R=Si(tBu)2H)

“…4À [14] units have been obtained, and subsequent reactions in liquid ammonia as solvent led to the formation of (PhZn)Si 9 3À , [15] ({Ni(CO) 2 } 2 Si 9 ) 2 8À , [16] and (NHC Dipp Cu)Si 9 3À (Dipp = 2,6-diisopropylphenyl). [17] Recently,t he mono-protonated cluster HSi 9 3À [18] was obtained upon the isolation of crystalso fA 12 Si 17 (A = K, Rb) from liquid ammonia with the help of sequestering agents.…”

Crystal Structure of the Protonated Germanide Cluster [HGe9]3−

“…This changed after the introduction of the chelating alkali metal ligand cryptand to these solutions by Corbett [4,5], when the isolation and structural characterization of solvate structures containing Zintl anions was facilitated. At present, for group 14 elements the representative homoatomic cluster anions identified in several solid state and solvate structures are [E 4 ] 4− (E = Si-Pb) [6][7][8][9], [E 5 ] 2− (E = Si-Pb) [10][11][12][13], [E 9 ] x− (x = 4; E = Si-Pb; x = 3, E = Si-Sn; x = 2 E = Si,Ge) [5,[14][15][16][17][18] and [E 10 ] 2− (E = Ge, Pb) [19,20]. For solvation experiments with germanium clusters, A 4 Ge 9 (A = K-Cs) [21,22] or A 12 Ge 17 (A = Na, K, K/Rb, Rb, Cs) [23,24] phases are used as starting materials, which contain the nine-atom germanide cluster or respectively [Ge 9 ] 4− /[Ge 4 ] 4− cage anions in a ratio of 1:2.…”