trans-2,2'-Azo-p-cymene

Abstract

. C22H26N2, obtained by reduction of 2‐nitro‐p‐cymene with KOH in triethylene glycol; orthorhombic, Pbca, a = 10.513 (18), b = 16.590 (6), c = 10.174 (12) Å, Z = 4, Dc = 1.10 and Dx = 1.11 g cm−3 (by flotation in aqueous NaBr‐soap solution). The molecules, which possess an essentially planar azobenzene skeleton, occupy centers of symmetry of the space group. The conformation of the molecule is such that N(8′) of the azo function is oriented anti with respect to C(1) of the benzene ring.

Structures of nitrogen-containing aromatic compounds. III. Benzalazine, redetermination and refinement

“…3) for the outer N is almost exactly 3, and the sum for the central N is about 3.3. The structure of azobenzene is, unfortunately for this comparison, disordered (Brown, 1966) but the (ph)C-N bonds in several related compounds are short: 1.42, 1-43 A in 4,4'-azodiphenetole (Galign6, 1970); 1.43,~ in bisphenylazostilbene (Chesick, 1973); 1.42 A in trans-2,2'azo-p-cymene (Wetherington, Holmes & Moncrief, 1974); 1.426, 1.430, 1.438A in the two crystalline forms of hexanitroazobenzene (Graeber & Morosin, 1974); 1.443 A in trans-p,p'-dichloroazobenzene (Hope & Victor, 1969). The N--N length in these compounds lies between 1.243 and 1.255 A.…”

Aromatic imine stereochemistry as studied by 13C and 1H NMR of 15N‐enriched materials

“…Available X-ray data indicate a substantial compression of the angle defined by C-l', C-1 and N upon introduction of the C-2 CH, function, thus rendering the N lone pair for compounds such as 6-12 closer to C-1' than in the systems 1-5. For example, this angle is 120.8" in 4chloro-E-benzaldoxime, 26 whereas in Emesitylacetophenone oxime?' the Cl'-C-l-N angle is compressed to 115.8".…”