https://doi.org/10.1351/goldbook.P04930
Compounds that resemble the halogen elements, X2, in their chemistry, e.g. (CN)2 cyanogen, (SCN)2 thiocyanogen, ICN iodine cyanide. Certain ions that have sufficient resemblance to halide ions are sometimes referred to as pseudohalide ions, e.g. N3−, SCN−, CN−.