Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 3901-3911 |
| Number of pages | 11 |
| Journal | Organometallics |
| Volume | 29 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - 2010 Sep 13 |
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All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
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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.
In: Organometallics, Vol. 29, No. 17, 13.09.2010, p. 3901-3911.Research output: Contribution to journal › Article
TY - JOUR
T1 - Efficient heck reactions catalyzed by palladium(0) and -(II) complexes bearing n-heterocyclic carbene and amide functionalities
AU - Lee, Jhen Yi
AU - Cheng, Pi Yun
AU - Tsai, Yi Hua
AU - Lin, Guan Ru
AU - Liu, Shih Pu
AU - Sie, Ming Han
AU - Lee, Hon Man
PY - 2010/9/13
Y1 - 2010/9/13
N2 - 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.
AB - 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.
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U2 - 10.1021/om1006402
DO - 10.1021/om1006402
M3 - Article
AN - SCOPUS:77956417732
VL - 29
SP - 3901
EP - 3911
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 17
ER -