Arsenic tricyanide

Like boron, most other metalloids are potential Lewis acids. Therefore, it is reasonable that simple cyanides Ge(CN)4, As(CN)3, Sb(CN)3 and Bi(CN), 2Cl i are insoluble in organic solvents and presumably polymeric (Bither, Knoth, Lindsey and Sharkey, 1958 also, Menzer, 1958). The unusually low volatility of phosphorus tricyanide and arsenic tricyanide prompted Emerson and Britton (1964, 1963) to determine the structures of these compounds. Phosphorus tricyanide is composed of pyramidal molecules which appear to associate through N---P interactions. The nitrogen-phosphorus distances, 2.85 to 2.97 A, are shorter than the esti-... 

Emerson, K. and D. T. Britton The Crystal and Molecular Structure of Arsenic Tricyanide. Acta Cryst. 16, 113 (1963). 

The action of CNI on metallic arsenic gives a mixture of ASI3 and As(CN)3, from which the iodide can be separated by extraction with CS2. The arsenic tricyanide hydrolyzes to AS2O3 and HCN on exposure to moisture. 

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