The synthesis of RbHCN2 was carried out by reaction of cyanamide with rubid
ium amide in liquid ammonia. The crystal structure has been determined by x
-ray powder methods (orthorhombic, P2(1)2(1)2(1), a = 7.299(1), b = 9.435(1
), c = 9.420(1) Angstrom; Z = 8). The anion is slightly bent (174 degrees)
and exhibits two different bond lengths (C-N: 1.17, HN-C: 1.31 Angstrom).