Abstract
Nine polyphenyls, including six new compounds, 3'-phenyl-o-quaterphenyl (3), 2, 6-diphenyl-m- (4), 2, 6-diphenyl-p-terphenyl (5), 2, 6, 5'-triphenyl-m-terphenyl (6), 2', 2"-diphenyl-m-quaterphenyl (8), and 2'-(phenyl-d5)-m-terphenyl (9), were synthesized by the Ullmann coupling reaction of aryl iodide (s) or by the Kharash-type coupling reaction of deuterated aryl Grignard reagent with aryl iodide catalyzed by bis (acetylacetonato)-nickel (II). Infrared studies of the polyphenyls showed that the range of 730-770 cm-1, generally accepted as the position of the C-H out-of-plane bending bands of phenyl rings, should be widened slightly to 730-781 cm-1. The high frequency bands were found to be correlated closely to the sterically overcrowded structure of terminal rings. Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1, 2, 3-trisubstituted ring (s) were fully consistent with their conformational aspects deduced from stereomodels. Ultraviolet spectral data suggested that the most probable conformation of the highly crowded 3', 6"-diphenyl-o-quaterphenyl (1) is one in which the interplanar angles of the pivot bonds between the 1, 2, 3-trisubstituted ring and three benzene rings are rather smaller than those of the less crowded 2'-phenyl-m-terphenyl (2).
