6-Amino-5-(1-amino-2,2-dicyanovinyl)-3,3a,4,5-tetrahydro-2<i>H</i>-indene-4-spiro-1′-cyclopentane-3a,7-dicarbonitrile–thiophene-2-carbaldehyde (1/0.5)

In each of the two independent indene-4-spiro-pentane mol-ecules in the asymmetric unit of the title 2:1 adduct, C(19)H(18)N(6)·0.5C(5)H(4)OS, the cyclo-hexene ring adopts a half-chair conformation and the cyclo-pentene and cyclo-pentane rings adopt envelope conformations. The mean plane through the cyclo-hexene/cyclo-pentene fused system is aligned at a dihedral angle of 77.9 (1)° with respect to the mean plane through the cyclo-pentane ring in one mol-ecule and 87.0 (1)° in the other. In the crystal, adjacent indene-4-spiro-pentane mol-ecules are linked by N-H⋯N hydrogen bonds into a three-dimensional network. The spaces within the network are occupied by the thio-phene-2-carbaldehyde mol-ecules. The thio-phene-2-carbaldehyde unit is disordered over two positions of equal occupancy. The crystal studied was found to be a non-morohedral twin with two minor twin components of 18.4 and 9.7%.