A hydrogen-bridged adduct 3,4,6,7,8,9-hexa­hydro-2H-pyrimido[1,2-a]pyrimidin-1-ium [1,3-bis­(tert-butyl­dimethyl­sil­yloxy)-1,3-bis­(pyridin-2-yl)propan-2-yl­idene]nitro­nate acetonitrile monosolvate

The title compound, C(7)H(14)N(3) (+)·C(25)H(40)N(3)O(4)Si(2) (−)·CH(3)CN, was obtained by the reaction of 2-nitro-1,3-di(pyridin-2-yl)-1,3-di(tert-butyl­dimethyl­sil­yloxy)propane with 1,3,4,6,7,8-hexa­hydro-2H-pyrimido[1,2-a]pyrimidine. Two hydrogen bonds stabilize the Lewis acid/base pair of the nitro­nate and the guanidinium moiety with N⋯O distances of 2.772 (3) and 2.732 (3) Å. Both hydrogen atoms are more closely bound to the guanidinium [N—H distances of 0.83 (3) and 0.93 (3) Å] than to the nitro­nate moiety. The nitro­nate is double-bonded to the respective carbon with an N=C bond length of 1.316 (3) Å.