中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | N,N'-bis(2,3-dimethoxybenzoyl)-1,4-phenylenediamine | 194469-97-1 | C24H24N2O6 | 436.464 |
with unit cell dimensions a = 14.283(2) Angstrom, c = 42.966(2) Angstrom, V = 7591 Angstrom(3), and Z = 2. Variable-temperature H-1 NMR experiments demonstrate that the configuration inversion of the enantiomers of K6Ga2(L-4)(3) (L-4 = N,N-bis(2,3-dihydroxy-4-(isopropylcarbamoyl)benzoyl) 1,4-phenylenediamine) and K6Ga2(L-5)(3) (L-5 = N-(2,3-dihydroxy-4-(isopropylcarbamoyl)benzoyl)-N'-(2,3-dimethoxy-4-(methylcarbamoyl)benzoyl)-1,4-phenylenediamine) is facile in D2O Or DMSO-d(6). The mechanism of inversion has been probed by dynamic NMR spectroscopy, using the complex K6Ga2(L-5)(3) which exists in two isomeric forms in solution, cis- and trans. The intramolecular inversion of the dinuclear helicates occurs without cis-trans isomerization and proceeds by independent trigonal twisting of each metal center, affording the heterochiral meso complex as an intermediate. The free energy of activation for the inversion of K6Ga2(L-4)(3) in D2O at p[D] = 12.1 is Delta G(298)(double dagger) = 79(2) kJ mol(-1), with Delta H = 75(2) kJ mol(-1) and Delta S-double dagger = -12(6) J mol(-1) K-1. Under slightly acidic conditions a proton-assisted pathway becomes dominant and the rate of inversion shows a second-order dependence in [D+]. The heterochiral meso complex of Ga-2(L-4)(6)(3-) is shown to be a transient kinetic intermediate in the (Lambda,Lambda) <-> (Delta,Delta) inversion process of the helicate complex.