Salts of HCN‐Cyanide Aggregates: [CN(HCN)₂]⁻ and [CN(HCN)₃]⁻

Abstract

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.

Pseudohalogen Chemistry in Ionic Liquids with Non‐innocent Cations and Anions

“…From the complex reaction mixture, only two formed products could be assigned by 31 P NMR and (ESI-TOF)-MS. One was the adamantane-like [P 4 S 9 N] À anion [135,136] (δ[ 31 P] = 67 and 33 ppm; m/z = 426) and the second was the [(SCN) 2 PS 2 ] À anion [134] (δ[ 31 As the products could neither be extracted from the mixture nor crystallized in different mixtures of solvents, e. g. acetonitrile/benzene or acetonitrile/diethyl ether, no further investigations with other ILs [nBu 3 MeN]X (X = N 3 , OCN, SCN) were carried out. [125,137,138] When attempting the synthesis of [PPN]SCN from [PPN]Cl and KSCN in H 2 O, we surprisingly obtained crystals of [PPN][H (NCS) 2 ]. [137] A direct method for the synthesis of this compound was achieved when [PPN]SCN was treated with in situ formed HNCS, generated from MeOH and Me 3 SiÀ NCS (Scheme 6).…”

“…[141] Thus motivated, we tried to synthesize salts containing the [CN(HCN ). [125] In an initial study the salts were suspended in Me 3 Si-CN and then MeOH was added to generate HCN in situ, but no crystallization could be achieved when cooling the solutions. Therefore, the [WCC]CN were dissolved directly in an excess of 15 equivalents of HCN, which was cooled to 0 °C.…”

“…In a subsequent reaction we synthesized the pseudohalides of the type [R 3 MeN]X (R=Et, n Bu: X=CN, N 3 , OCN, SCN; [123] R=nPr: X=CN) [124] and [Ph 3 MeP]CN, [125] by nucleophilic desilylation of trimethylpseudohalosilanes Me 3 Si–X with the reactive and non‐innocent [CO 3 Me] − anion (Scheme 2), a reaction developed by Sundermeyer et al [129] . Besides the pseudohalide salt, Me 3 Si–OMe and CO 2 were formed, whereby the latter can be removed from the reaction solution, which shifted the reaction equilibrium in favor of the products.…”

Salze von HCN‐Cyanid‐Aggregaten: [CN(HCN)2]− und [CN(HCN)3]−

“…Nur das Hauptisomer, das thermodynamisch günstigste Isomer, wird dargestellt. [87] Abbildung 2. , h N8-C4 3.602(3). [87] Beide Salze, sowohl [73,74] Daher war es sehr schwierig, weitere analytische Daten zu erhalten.…”

“…[87] Abbildung 2. , h N8-C4 3.602(3). [87] Beide Salze, sowohl [73,74] Daher war es sehr schwierig, weitere analytische Daten zu erhalten. NMR-Daten in flüssiger Phase (mit reinem HCN als Lçsungsmittel) bei À12 8C zeigten eine Resonanz im 13 [72] für die n C-D Streckschwingung beobachtet werden, die nicht weiter aufgelçst werden konnten.…”