Skeletal distortion

MO calculations for simple porphyrins, chlorins, and bacteri-ochlorins show that, within the same series, the LUMOs are nearly isoenergetic, that is, they do not change as the number of n electrons is reduced from 22 to 20 and to 18 along the series. However, the increased Z)2h skeletal distortion destabilizes the HOMOs, and their energies increase systematically (Fig. 3 (10)). 

Prognosis— inability to walk 10 years after onset, with progressive weakness, atrophy, and contracture of muscles leading to skeletal distortion, complete helplessness, and death in the second decade due to inanition or infection. 

V. Electron Rich Clusters Bond Breaking and Skeletal Distortions. 36... 

Recent structural data for (bacterio)chlorophylls and chlorins as isolated molecules and in proteins have demonstrated the skeletal distortions of the chromophores that can be imposed by crystal packing and/or protein constraints. ... 

Katritzky and Topsom have reviewed the information available, largely from infrared and n.m.r. studies, concerning the distortion of the tt-electron system in the benzene ring brought about in the ground state by substituents. Of particular interest is the observation that both n.m.r. studies (of m- F and chemical shifts) and infrared investigations (of the intensities of bands due to certain skeletal vibrations) suggest that the value of Taft s [Pg.226]

The backbone skeletal stretch region is rather ambiguous for /1-sheet assignments. As may be seen in the ROA spectrum of jack bean con-canavalin A (Fig. 4), there are many bands in this region, mostly positive. These bands can be rather variable in intensity, width, and wavenumber in /3-sheet proteins, which may reflect the various types of distortions found in /3-sheet. 

Butterfly. While Tl2Te22- has a (2)(1) + (2)(4) + 2 = 12 skeletal electron count isoelectronic and isolobal with neutral cyclobutadiene, it undergoes a different Jahn-Teller-like distortion to the butterfly structure discussed by Bums and Corbett [81]. 

Oxfendazole, on the other hand, is teratogenic in sheep but not in cattle. Albendazole administered on day 12 in sheep causes exencephaly and on day 17 causes skeletal abnormalities. In sheep, head and face abnormalities tend to occur following exposure from day 12 to 17, spinal column defects from day 16 to 21, and limb distortion from day 22 to 25. 

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