TY - JOUR
T1 - Overcrowded twisted bi-4H-cyclopenta[def]-phenanthren-4-ylidene versus bi-9H-fluorenylidene, syn pyramidalization
AU - Stezowski, John J.
AU - Hildenbrand, Thomas
AU - Suissa, M. Rachel
AU - Agranat, Israel
PY - 1990/1
Y1 - 1990/1
N2 - A crystal structure determination for bi-4 H-cyclopenta[def]-phenanthren-4-ylidene, 1, reveals a molecular conformation rather like that reported earlier for bifluorenylidene, 2. However, unexpectedly, the twist angle about the ethylenic linkage is substantially smaller in 1 (average values are 30.8 and 40.7°, respectively). Comparison of bonding geometry, combined with the results of molecular mechanics calculations for 1, demonstrates that syn pyramidalization can play an important role in determining a stable conformation for overcrowded, twisted aromatic enes. The average out-of-plane bending angles for the ethylenic carbon atoms of 1 and 2 are 8.6 and 4.4°, respectively.
AB - A crystal structure determination for bi-4 H-cyclopenta[def]-phenanthren-4-ylidene, 1, reveals a molecular conformation rather like that reported earlier for bifluorenylidene, 2. However, unexpectedly, the twist angle about the ethylenic linkage is substantially smaller in 1 (average values are 30.8 and 40.7°, respectively). Comparison of bonding geometry, combined with the results of molecular mechanics calculations for 1, demonstrates that syn pyramidalization can play an important role in determining a stable conformation for overcrowded, twisted aromatic enes. The average out-of-plane bending angles for the ethylenic carbon atoms of 1 and 2 are 8.6 and 4.4°, respectively.
UR - http://www.scopus.com/inward/record.url?scp=0000173102&partnerID=8YFLogxK
U2 - 10.1007/BF00675791
DO - 10.1007/BF00675791
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AN - SCOPUS:0000173102
SN - 1040-0400
VL - 1
SP - 123
EP - 126
JO - Structural Chemistry
JF - Structural Chemistry
IS - 1
ER -