Die Tetracyanoborate M[B(CN)4], M = [Bu4N]+, Ag+, K+

Erstmals wird das Tetracyanoborat-Anion in Form seines Tetrabutylammonium-Salzes durch Umsetzung von [NBu4]BX und BX3 (X = Br, Cl) in Toluol mit KCN erhalten. Nach Aufarbeitung des Rohproduktes und Umkristallisation aus CHCl3 fallen farblose, stäbchenförmige Einkristalle [Bu4N][B(CN)4] an. Die Metathese mit AgNO3 ergibt das Silbersalz und aus diesem mit KBr schließlich das Kaliumsalz. Die drei Salze werden durch Röntgenbeugung an Einkristallen (Ag[B(CN)4] P 43m, a = 5.732(1) Å, V = 188.3 Å3, Z = 1, R1 = 0.75%; K[B(CN)4] I41/a, a = 6.976(1), c = 14.210(3) Å, V = 691.5 Å3, Z = 4, R1 = 1.90%; [Bu4N][B(CN)4] Pnna, a = 17.765(3), b = 11.650(2), c = 11.454(2) Å, V = 2370.5 Å3, Z = 4, R1 = 6.09%) und NMR-, IR-, Raman- sowie UV-Spektroskopie charakterisiert. The Tetracyanoborates M[B(CN)4], M = [Bu4N]+, Ag+, K+ The tetracyanoborate anion is prepared for the first time as the tetrabutylammonium salt by the reaction of [NBu4]BX and BX3 (X = Br, Cl) in toluene with KCN. After purification and recrystallization of the product from CHCl3 colorless and needle size single crystals of [Bu4N][B(CN)4] are formed. After metathesis with AgNO3 the silver salt and subsequently with KBr the potassium salt is prepared. The three salts are characterized by single crystal X-ray diffraction (Ag[B(CN)4] P 43m, a = 5.732(1) Å, V = 188.3 Å3, Z = 1, R1 = 0.75%; K[B(CN)4] I41/a, a = 6.976(1), c = 14.210(3) Å, V = 691.5 Å3, Z = 4, R1 = 1.90%; [Bu4N][B(CN)4] Pnna, a = 17.765(3), b = 11.650(2), c = 11.454(2) Å, V = 2370.5 Å3, Z = 4, R1 = 6.09%) and by NMR-, IR-, Raman- as well by UV-spectroscopy.