988. Physical properties and chemical constitution. Part XLII. The electric dipole moments of nitrophenylpyridines

Abstract

The electric dipole moments of eight nitrophenylpyridines have been calculated from measurements of the dielectric constants, specific volumes, and refractive indices of their solutions in pure benzene a t 25-00'. In the para-and meta-isomers the planes of the pyridine and benzene rings are probably inclined a t about 40', but this angle is greater in o-nitrophenylpyridines. The 2-m-, 3-m-, and 3-o-nitrophenylpyridines favour a transconformation but in the 2-o-isomer a cis-configuration is preferred.THE electric dipole moments of phenylpyridines and of some phenyl-substituted 2-phenylpyridines have been considered previously. These molecules are not planar, and in many phenyl-substituted phenylpyridines the substituent can have a cis-or a trans-configuration with respect to the pyridine nitrogen atom. Information concerning conjugation between the pyridine and benzene rings in nitrophenylpyridines, analysed in relation to nitrobenzene and pyridine, is provided by the dipole moments; further information on the extent of conjugation is furnished by the ultraviolet (u.v.) spectra of these compounds.EXPERIMENTAL AND RESULTSPreparation and PuriBcation of Nitropheny1pyridines.-The dipole moment of each compound was measured immediately it had been purified and its infrared (i.r.) and U.V. spectra recorded.The compounds were prepared by the method of Haworth, Heilbron, and Hey,3 in which a diazotised nitroaniline is decomposed in the presence of pyridjne.

Cyclometalated Ru Complexes of Type [RuII(N∧N)2(C∧N)]z: Physicochemical Response to Substituents Installed on the Anionic Ligand

“…An alternative method to a previously reported synthesis is provided . A THF/EtOH (20 mL) solution (THF:EtOH, 3:1 v:v) containing 501 mg (3.00 mmol) of 3-nitrophenylboronic acid, 966 mg (7.00 mmol) of K 2 CO 3 and 173 mg (0.150 mmol) of Pd(PPh 3 ) 4 was charged with 0.26 mL (2.7 mmol) of 2-bromopyridine and then heated at reflux for 65 h. The suspension was then filtered to obtain an orange filtrate that afforded a dark red-orange oil upon removal of solvent in vacuo.…”