Effect of M(CO)₃ (M = Cr, Mn⁺) on Aromatic C−Cl BDE in (η⁶-ArCl)M(CO)₃ Complexes

Abstract

The coordination of Cr(CO)3 to chlorobenzenes significantly reduces the C-Cl bond dissociation energy. Treatment of chloroarene-Cr(CO)3 complexes with SmI2/HMPA at room temperature led to complete dechlorination. Reaction of o-allyloxychlorobenzene-Cr(CO)3 complexes with SmI2 at room temperature resulted in the corresponding dechlorinative cyclization products in good to excellent yields. Competition experiments indicated the following relative reactivities of dehalogenation by SmI2: PhI/PhCl-Cr(CO)3/PhBr/PhCl = 50:1:0.3:<0.001. On the other hand, the coordination of Mn(CO)3(+) to chlorobenzene showed a much smaller activation effect. Density functional theory calculations revealed that the spin delocalization effect of the metal center plays an important role in the C-Cl bond activation.

Structure-activity relationships for a new family of sulfonylurea herbicides

“…Previously published 3D-QSAR analyses of sulfonylurea herbicides [19][20][21][22][23][24][25][26] suffer from several shortcomings. Firstly, the assumed bioactive conformation was based on either the structures of sulfonylureas crystallized as free molecules [20][21][22][23]25] or their low energy conformers calculated theoretically [19,24,26].…”

“…Firstly, the assumed bioactive conformation was based on either the structures of sulfonylureas crystallized as free molecules [20][21][22][23]25] or their low energy conformers calculated theoretically [19,24,26]. However, it is now known that none of these conformations match that observed when a sulfonylurea is bound to its target enzyme [7,8].…”

“…However, it is now known that none of these conformations match that observed when a sulfonylurea is bound to its target enzyme [7,8]. Secondly, most activity data employed in previous QSAR investigations were obtained using in vivo experiments [19][20][21][22][23][24][25][26]. Herbicidal activity depends ultimately upon inhibition of AHAS, but there are differences between in vivo and in vitro effects of these compounds due to barriers between the site of application and the intracellular target, degradation and detoxification by the plant, and so on.…”

The Stereospecific Ligand Exchange at a Pseudo‐Benzylic T‐4 Iridium Centre in Planar‐Chiral Cycloiridium (η6‐Arene)tricarbonylchromium Complexes

“…It was found to obey the general trends already reported by us and other authors in recent articles. [58,60,70,71] Expectedly, in syn isomers the latter monodentate ligand forces the Cr(CO) 3 fragment to slightly shift from its central position with respect to the arene ligand. These trends are readily supported by the results of the EPA.…”

Rapid and quantitative determination of solanesol in Nicotiana tabacum by liquid chromatography–tandem mass spectrometry

“…Many analytical methods including of column chromatography weight, thin-layer chromatography (TLC), coulomb's analysis, gas chromatography (GC) and high performance liquid chromatography (HPLC) have been documented for the determination of solanesol [20][21][22][23][24][25][26][27][28]. All of the methods above suffered from some limitations, such as, column chromatography weight method had low recovery, the precision obtained by TLC was poor, coulomb's analysis had significant error, the GC method was complicated by the interference of solanesenes, produced from the pyrolysis of solanesol at high temperatures in the GC oven and the breakdown of solanesol hindered the direct quantification of solanesol.…”