Tris(trichlorosilyl)tetrelide Anions and a Comparative Study of Their Donor Qualities

Abstract

Trichlorosilylated tetrelides [(Cl3Si)3E]− have been prepared by adding 1 equiv of a soluble Cl− salt to (Cl3Si)4Si (E=Si) or 4 Si2Cl6/GeCl4 (E=Ge). To assess their donor qualities, the anions [(Cl3Si)3E]− (E=C, Si, Ge) have been treated with BCl3, AlCl3, and GaCl3. Both BCl3 and GaCl3 give 1:1 adducts with the anionic centers. AlCl3 leads to Cl− abstraction from [(Cl3Si)3E]− with formation of (Cl3Si)4E (E=Si or Ge). (Cl3Si)4Ge is cleanly converted to the perhydrogenated (H3Si)4Ge by use of Li[AlH4]. Another case of Cl− abstraction was observed for [(Cl3Si)3Ge⋅GaCl3]−, which reacts with GaCl3 to afford the neutral dimer [(Cl3Si)3Ge−GaCl2]2.

Building up Strain in One Step: Synthesis of an Edge‐Fused Double Silacyclobutene from an Extensively Trichlorosilylated Butadiene Dianion

“…[26] A 27 Al NMR spectrum recorded on the reaction mixture of [nBu 4 N] 2 [1]and AlCl 3 (1:1) in CD 2 Cl 2 exclusively showed the prominent and sharp signal of the [AlCl 4 ] À anion at 103.8 ppm. [19] Four 13 Ca nd four 29 Si NMR resonances testify to the low symmetry of the organosilicon product obtained (see [ Figure 2).…”

“…Similar to the proton, the Lewis acid AlCl 3 can, in principle, interact both with the carbanion centers and Cl atoms of [ 1 ] 2− . Since Cl − abstraction would produce the stable and weakly coordinating [AlCl 4 ] − anion, no accompanying desilylation should occur.…”

“…These results underscore the prime importance of the choice of acids with either nonnucleophilic (TfO À )o rn ucleophilic (Cl À )c ounter anions for the reaction outcome. [10] Similar to the proton, the Lewis acid AlCl 3 can, in principle,i nteract both with the carbanion centers [19] and Cl atoms of [1] 2À . [20] Since Cl À abstraction would produce the stable and weakly coordinating [AlCl 4 ] À anion, no accompanying desilylation should occur.…”

Unexpected Formation of the Highly Symmetric Borate Ion [B(SiCl3)4]−

“…Trichlorosilyl substituted anions of main group elements have been recently shifted into the focus of research. The following anions have been characterized since 2015: [C(SiCl 3 ) 3 ] À , [13,14,15] [Si(SiCl 3 ) 3 ] À , [16,17] [Ge(SiCl 3 ) 3 ] À , [16] [P(SiCl 3 ) 2 ] À , [18,19] and [S(SiCl 3 )] À . [19] Especially [P(SiCl 3 ) 2 ] À received considerable attention as synthon for the generation of phosphorus chemicals, that had previously only been available from white phosphorus (P 4 ).…”

“…[19] Especially [P(SiCl 3 ) 2 ] À received considerable attention as synthon for the generation of phosphorus chemicals, that had previously only been available from white phosphorus (P 4 ). [20] Neutral molecules like [C(SiCl 3 ) 4 ], [21,22,23,24,25,26] [E(SiCl 3 ) 4 ] (E=Si, Ge), [27,28,29,30] and [N(SiCl 3 ) 3 ] [31,32,33] have been prepared earlier.…”