Starting from fluoridosilicate precursors in neat cyanotrimethylsilane, Me3Si−CN, a series of different ammonium salts [R3NMe]+ (R=Et, nPr, nBu) with the novel [SiF(CN)5]2− and [Si(CN)6]2− dianions was synthesized in facile, temperature controlled F−/CN− exchange reactions. Utilizing decomposable, non‐innocent cations, such as [R3NH]+, it was possible to generate metal salts of the type M2[Si(CN)6] (M+=Li+, K+) via neutralization reactions with the corresponding metal hydroxides. The ionic liquid [BMIm]2[Si(CN)6] (m.p.=72 °C, BMIm=1‐butyl‐3‐methylimidazolium) was obtained by a salt metathesis reaction. All the synthesized salts could be isolated in good yields and were fully characterized.

Although pure hydrogen cyanide can spontaneously polymerize or even explode, when initiated by small amounts of bases (e.g. CN−), the reaction of liquid HCN with [WCC]CN (WCC=weakly coordinating cation=Ph4P, Ph3PNPPh3=PNP) was investigated. Depending on the cation, it was possible to extract salts containing the formal dihydrogen tricyanide [CN(HCN)2]− and trihydrogen tetracyanide ions [CN(HCN)3]− from liquid HCN when a fast crystallization was carried out at low temperatures. X‐ray structure elucidation revealed hydrogen‐bridged linear [CN(HCN)2]− and Y‐shaped [CN(HCN)3]− molecular ions in the crystal. Both anions can be considered members of highly labile cyanide‐HCN solvates of the type [CN(HCN)n]− (n=1, 2, 3 …) as well as formal polypseudohalide ions.

Functionalized imidazolium cations were combined with the hexacyanidosilicate anion, [Si(CN) 6 ] 2-, by salt metathesis reactions with K 2 [Si(CN) 6 ], yielding novel ionic compounds of the general formula [R-Ph(nBu)Im] 2 [Si(CN) 6 ] {R = 2-Me (1), 4-Me (2), 2,4,6-Me = Mes (3), 2-MeO (4), 2,4-F (5), 4-Br (6); Im = imidazolium}. All synthesized imidazolium hexacyanidosilicates decompose upon thermal treatment above 95°C (96-164°C).

Several pseudohalide containing ionic liquids with quarternary ammonium counter cations of the general formula [R3MeN]X [R = ethyl (1X), n‐butyl (2X) with X– = CN–, N3–, OCN–, and SCN–] were synthesized by decomposition of the corresponding trialkylammonium methylcarbonate in the reaction with Me3Si–X. We also treated 2CN with OP(OMe)3, yielding [nBu3MeN][O2P(OMe)2] and acetonitrile (Me‐CN). The double salt [nBu3MeN]2{[B(OMe)3(CN)](CN)} was obtained from the reaction of 2CN with B(OMe)3, featuring the formation of the monocyanotrimethoxyborate anion, [B(OMe)3(CN)]–, co‐crystallized with [nBu3MeN]CN. [nBu3MeN]2{[B(OMe)3(CN)](CN)} was fully characterized including structure elucidation.

The trapping of classical hydrogen pseudohalides (HX, X = pseudohalogen = CN, N3, NCO, NCS, and PCO) utilizing a phosphorus-centered cyclic biradicaloid, [P(μ-NTer)]2, are reported. These formal Brønsted acids were...