N,N,N′,N′,N′′,N′′-Hexa­methyl­guanidinium 1,1,3,3-tetra­cyano­prop-2-en-1-ide

The asymmetric unit of the title salt, C7H18N3+·C7HN4−, comprises one cation and one anion. The N,N,N′,N′,N′′,N′′-hexa­methyl­guanidinium ion shows orientational disorder and two sets of N- and C-atom positions were found, with an occupancy ratio of 0.535 (3):0.465 (3). The C—N bond lengths in the guanidinium ion range from 1.339 (16) to 1.35 (2) A, indicating partial double-bond character pointing towards charge delocalization within the NCN planes. The negative charge in the 1,1,3,3-tetra­cyano­prop-2-en-1-ide ion is delocalized within the CCC planes with the C—C bonds ranging in length from 1.379 (3) to 1.427 (3) A, also indicating partial double-bond character.