Electric dipole moments and molecular conformations of aromatic amines, phosphites, and phosphates

Abstract

The electric dipole moments of diphenylamine, triphenylamine, triphenyl phosphite, and triphenyl phosphate, together with their syrnmetrically-substituted ortho, mefa, and para methyl and chloro-derivatives, have been measured in benzene solution a t 25.0". The results are analysed in terms of probable molecular conformations. STERIC interactions between hydrogen atoms in di-phenylamine twist the phenyl rings about the Ph-N bonds thereby affecting some of the component moments. If the group moments are evaluated from the experimental dipole moments of diphenylamine, di-9-tolylamine and di-(4-chlorophenyl) amine then the dipole moments of di-ortho-and di-meta-substituted diphenylamines can be interpreted in terms of possible alternative molecular conformations and a numerical value for the angle of twist about the Ph-N bonds. Analogous approaches are possible with the other series of compounds studied. EXPERIMENTAL AND RESULTS* Rotation of the rings in opposite directions has not been considered since steric interactions would severely restrict the values for the angle / 3, particularly in the di-ortho-compounds and also for the triphenylamines.

Molecular Structure of Triphenylamine in the Gas Phase

“…According to Knobloch and Stockhausen [12], the dipole moments at 20oC are as follow, D: triphenylarsine 1.18, triphenylphosphine 1.52, triphenylamine 0.66, and triphenylbinzil 0.7. The results for triphenylamine were confirmed by Cumper and Thurston [13], who reported the m value of 0.70 D. Figure 6 shows the potential energy curve of triphenylamine, calculated at the HF/6-31G* level of theory. The barrier between two symmetric conformations is~8 kcal mol !1 .…”

Spectroscopy on triphenylamine and its van der Waals complexes

“…Deconvolution of the experimentally observed Voigt profile yields a Lorentzian contribution to the linewidth of around 36 MHz, implying a lifetime for individual J', K' levels in the vibrationless S, state of TPAof4.520. 5 ns. In the fit to the experimental data the spin statistical weights have not been taken into account, as they are very close to one with five fermions present in each phenyl ring.…”

Arylation of Diarylamines Catalyzed by Ni(II)—PPh3 System.

“…EI-MS: m/z 295 (M + , 100%). 1 H NMR (CDCl 3 , 300 MHz): 6.92 (t, J = 7.2 Hz, 2 H), 7.02 (d, J = 10.8 Hz, 4 H), 7.19 (t, J = 7.7 Hz, 4 H), 7.31-7.49 (m, 4 H), 7.76 (d, J = 8.1 Hz,1 H), 7.87 (d, J = 9.3 Hz, 1 H), 7.93 (d, J = 8.4 Hz, 1 H). CAS Registry No.…”

“…EI-MS: m/z 279 (M + , 100%), 281 (M + +2, 34%). 1 H NMR (CDCl 3 , 400 MHz): 6.99 (d, J = 8.8 Hz, 2 H), 7.02 (t, J = 7.2 Hz, 2 H), 7.05 (d, J = 8.4 Hz, 4 H), 7.17 (d, J = 8.8 Hz, 2 H), 7.24 (t, J = 7.8 Hz, 4H). CAS Registry No.…”

“…EI-MS: m/z 259 (M + , 100%). 1 H NMR (CDCl 3 , 300 MHz): 2.04 (s, 3 H), 6.93 (t, J = 7.5 Hz, 3 H), 6.98 (d, J = 7.8 Hz, 4 H), 7.10-7.25 (m, 8 H). CAS Registry No.…”