2131-84-2Relevant academic research and scientific papers
Efficient heck reactions catalyzed by palladium(0) and -(II) complexes bearing n-heterocyclic carbene and amide functionalities
Lee, Jhen-Yi,Cheng, Pi-Yun,Tsai, Yi-Hua,Lin, Guan-Ru,Liu, Shih-Pu,Sie, Ming-Han,Lee, Hon Man
experimental part, p. 3901 - 3911 (2010/12/25)
A palladium(0) NHC complex Pd0(LH1)2(MA) (MA = maleic anhydride) was prepared from the amide-imidazolium salt [LH 1H2]Cl (H1 = NH proton; H2 NCHN proton). The X-ray diffraction studies confirmed that a η2-MA ligand and two monodentate NHC ligands with the H1 protons remaining intact are coordinated. These NH protons are involved in intra- or intermolecular hydrogen bonds stabilizing the solid-state structure. Degradation of Pd(LH1)2(MA) in air leads to the formation of the chelate complex trans-PdIIL2 and other unidentified products. Negative-ion electrospray mass spectrometry revealed some intriguing Pd(0) species, including a 14-electron [Pd0L]- species that bears only a bidentate NHC/amido ligand. The anionic amido group imparts a high electron density on a palladium center, as shown by X-ray photoelectron study. The palladium(0) precatalyst is highly efficient in catalyzing Heck reactions with activated aryl chlorides in ionic liquid. For deactivating aryl chlorides and bulky aryl bromides, cis-PdIIL2 is more effective. A range of Heck-coupled products can be prepared by Pd 0(LH1)2(MA) and cis-PdIIL 2. The latter complex also successfully mediates one-pot sequential Heck/Heck and Suzuki/Heck coupling reactions with 4-bromochlorobenzene as substrate.
Fluorescence of Distyrylbenzenes and Distyrylstilbenes
Erckel, R.,Fruehbeis, H.
, p. 1472 - 1480 (2007/10/02)
Absorption, corrected emission spectra, fluorescence quantum yields, and preparation are reported for distyrylbenzene, distyrylstilbene and substituted derivatives.The Stokes shifts measured in three solvents and correlated with quantum chemical calculations. - Key words: Fluorescence, Distyrylbenzenes
