Structural and Variable-Temperature NMR Studies of 9-Diisopropylphosphanylanthracenes and 9,10-Bis(diisopropylphosphanyl)anthracenes and Their Oxidation Products
摘要:
The diisopropylphosphanyl-substituted anthracenes i-Pr(2)P(C(14)H(9)) (1a), i-Pr(2)P(C(14)H(8))Br (2a), and (i-Pr(2)P)(2)(C(14)H(8)) (3a) and some of their oxidation products were prepared from 9-bromoanthracene and 9,10-dibromoanthracene, respectively. Low-temperature (1)H NMR spectra of the 9-monophosphanyl-substituted anthracenes la and 2a are in accordance with a staggered conformer, while above room temperature dynamic processes occur. The low-temperature NMR spectrum of the 9,10-diphosphanylanthracene 3a indicates the presence of two different rotational isomers. The rotational barrier for la was determined from variable-temperature (1)H NMR spectra to be 56 kJ mol(-1) (Delta G(298K)). The crystal structure determinations show the solid-state conformers to be consistent with the prevailing conformer at low temperature.
Structural and Variable-Temperature NMR Studies of 9-Diisopropylphosphanylanthracenes and 9,10-Bis(diisopropylphosphanyl)anthracenes and Their Oxidation Products
作者:Gerald Schwab、Daniel Stern、Dietmar Stalke
DOI:10.1021/jo800294e
日期:2008.7.1
The diisopropylphosphanyl-substituted anthracenes i-Pr(2)P(C(14)H(9)) (1a), i-Pr(2)P(C(14)H(8))Br (2a), and (i-Pr(2)P)(2)(C(14)H(8)) (3a) and some of their oxidation products were prepared from 9-bromoanthracene and 9,10-dibromoanthracene, respectively. Low-temperature (1)H NMR spectra of the 9-monophosphanyl-substituted anthracenes la and 2a are in accordance with a staggered conformer, while above room temperature dynamic processes occur. The low-temperature NMR spectrum of the 9,10-diphosphanylanthracene 3a indicates the presence of two different rotational isomers. The rotational barrier for la was determined from variable-temperature (1)H NMR spectra to be 56 kJ mol(-1) (Delta G(298K)). The crystal structure determinations show the solid-state conformers to be consistent with the prevailing conformer at low temperature.