STRUCTURES OF 2,3-DIETHYL-6,7-DIHYDRO-5H-2A-LAMBDA-4-SELENA-2,3,4A,7A-TETRAAZA-CYCLOPENT[CD]INDENE-1(2H),4(3H)-DISELONE AND 1,4-BIS(ETHYLIMINO)-5,6-DIHYDRO-2,2A-LAMBDA-4,3-TRISELENA-4A,6A-DIAZACYCLOPENTA[CD]PENTALENE

2,3-Diethyl-6,7-dihydro-5H-2alambda4-selena 2,3,4a,7a-tetraazacyclopent[cd]indene-1(2H),4(3H)-diselone (7), C10H16N4Se3, M(r) = 429.146, monoclinic, P2(1), a = 5.322 (2), b = 10.531.(3), c = 12.939 (2) angstrom, beta = 99.20 (2)degrees, V = 715.85 angstrom3, Z = 2, D(x) = 1.99 g cm-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 74.84 cm-1, F(000) = 412, T = 295 K, R = 0.055 for 1568 reflections with F greater-than-or-equal-to 3 sigma(F). 1,4-Bis(ethylimino)-5,6-dihydro-2,2alambda4,3-triselena-4a,6a-diazacyclopenta[cd]pentalene (8), C9H14N4Se3, M(r) = 415.199, monoclinic, P2(1)/a, a = 8.005 (1), b = 13.717 (2), c = 11.950 (1) angstrom, beta = 93.42 (1)degrees, V = 1309.76 angstrom3, Z = 4, D(x) = 2.10 g cm-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 81.78 cm-1, F(000) = 792, T = 295 K, R = 0.053 for 1793 reflections with F greater-than-or-equal-to 3 sigma(F). Compound (7) was found to contain elongated Se-N bonds, while compound (8) contains elongated Se-Se bonds in its fused ring system. In both structures evidence was found for some conjugation in the fused ring systems of the molecules.