Basic tetraaryls

TABLE 3. Mean E—C bond lengths (pm) in Ar4E compounds determined crystal I g raph ically—2 

While not referring directly to Group 14, a review24 on quantification of steric effects tabulates steric effect data such as cone angles for PR 3 and ASR3 species, which are useful comparisons for SiR3 and GeR3 substituents. 

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Porphyrin, 5,10,15,20-tetraphenyl-, 4, 386 Porphyrin, vinyl-synthesis, 4, 278, 279 Porphyrin coenzymes in biochemical pathways, 1, 258-260 Porphyrinogen, mcso-tetraaryl-synthesis, 4, 230 Porphyrinogens, 4, 378, 394 pyrazoles, 5, 228 synthesis, 4, 231 Porphyrins, 4, 377-442 acetylation, 4, 395 aromatic ring current, 4, 385 basicity, 4, 400 biosynthesis, reviews, 1, 99... 

When 2,4,6-tri- or 2,3,4,6-tetraarylated pyrylium tetrafluoroborate is treated with nitromethane under different conditions rearrangement is also observed. No rearrangement occurs when the two components are heated together with an excess of potassium t-butylate in t-butanol (route a). Under strong basic conditions the intermediate 11 probably loses the acidic proton at position 1 to give the aromatic nitro compound 12. 

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