The crystal and molecular structure of 1,1,2,2-tetracyanocyclopropane

Substituted cyclopropanes. 6. trans-Triethyl 1,2,3-tricyano-1,2,3-cyclopropanetricarboxylate

“…The ring asymmetry pattern with a long bond between C(2) and C(3), which bear two groups each in conjugation with the ring [while C(1) has only one], is in accord with the additivity scheme outlined by Allen (1980). Similar long bonds in highly but unsymmetrically substituted cyclopropane rings have been observed m 1,1,2,2-cyclopropanetetracarbonitrile (1.559 A, Lemley et al, 1976) and in two substituted 1,2,2-tricyanocyclopropanecarboxylic esters (1.542 A; Ramasubbu, Rajaram & Venkatesan, 1982;1.557 A;Ramasubbu & Venkatesan, 1982). The average ring bond length in many cyclopropane derivatives is less than 1.520 A and for most carbonyl-substituted structures as low as 1.505 A or less (Allen, 1980).…”

The crystal and molecular structures of two derivatives of a spiro-oxazolone: a cis vs trans X-ray study

“…So it seems there is no significant difference between the two molecules, within the experimental error; moreover, there seems to exist good agreement between some individual bond distances, the C-C bonds being the more susceptible to variations. The bonds of the cyclopropane rings show a shortening from the normal C(sp3)-C(sp 3) bond because of the triangular bending, which is also reflected in the geometry outside the cyclopropane ring, as is recorded in the literature (Riche & Pascard-Billy, 1975;Lemley, Skarstad & Hughes, 1976;Grant & Speakman, 1958;Carlstr6m, 1975;Schenk, 1971;Beintema, 1976). The differences within the ring have to be referred to the difference in degree of substitution at each corner (Meester, Schenk & MacGillavry, 1971), the effect of which may also be noticed in the areas of the triangles, 0.986 and 0.991 A2, which are between the theoretical values of 0.977 A 2 for cyclopropane and 0.996 A 2 for cyclopropylidene (Lathan, Radon, Hariharan, Hehre & Pople, 1973).…”

The crystal and molecular structure of 3-(N-phenyl-N-tricyanovinyl)amino-1,2,5-triphenylpyrrole

“…The differences are small, less than or equal to 0-010/k, but are very likely indicative of the diminished importance of the valence electrons (Lemley et al, 1976) in the present refinement.…”

“…> 2a(l) also contributed to the refinement. In this (14) 2632 (1) 16 (7) 5245 (3) C (15) 2340 (2) 1002 (6) 5264 (3) C (16) 1952 (1) 1009 (5) 4594 (2) C (2) 1352 (1) 950 (3) 2614 (2) C (21) 1610 (1) 2145 (3) 2538 (2) C (22) 1977 (1) 1870 (4) 2468 (2) C (23) 2209 (1) 3011 (5) 2370 (3) C (24) 2073 (1) 4438 (4) 2322 (2) C (25) 1712 (1) 4725 (4) 2392 (3) C (26) 1482 ( In view of the presence of the tricyanovinyl moiety and the high resolution of the data, additional refinement with a truncated data set to minimize the effects of the delocalized valence electrons (Lemley, Skarstad & Hughes, 1976) was considered. Unfortunately, the quality of the higher-angle data does not appear to (15) 2343 (19) 1746 (71) 5865 (39) 11.2 H (16) 1733 (15) 1655 (56) 4655 (29) 6.3 H (22) 2070 (13) 859 (51) 2475 …”