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Article: Substituent-dependent structures and catalysis of benzimidazole-tethered N-heterocyclic carbene complexes of Ag(i), Ni(ii) and Pd(ii)
Title | Substituent-dependent structures and catalysis of benzimidazole-tethered N-heterocyclic carbene complexes of Ag(i), Ni(ii) and Pd(ii) |
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Authors | |
Issue Date | 2010 |
Citation | Dalton Transactions, 2010, v. 39, n. 22, p. 5231-5241 How to Cite? |
Abstract | Homoleptic cationic benzimidazole-imidazolin-2-ylidene N-heterocyclic carbene (NHC = L) complexes of NiII and PdII have been prepared directly from the ligand precursor in salt form [H.L]Cl and from the transmetallation route via AgI. The N-tether of the imidazolinylidene ring imposes a significant influence on the nuclearity of the intermediate Ag(i)-NHC complexes and the geometric isomer outcome of the d8 products. Use of a benzyl-substituted NHC gives [Ag4(L Bn)2Cl4], 2a (from [HLBn]Cl, 1a, and Ag2O) (Bn = benzyl), which shows an alignment of four silver atoms bridged by the difunctional C-N ligands and chlorides. Its transmetallation with NiCl2(PPh3)4 and PdCl2(MeCN) 2 results in double-metal salts 2[M(LBn)2] 2+[Ag4Cl8]4- (M = Ni (3a) and Pd (4a)). The nuclearity of the Ag4 aggregate is maintained in the transmetallation process. Their Ag-free forms [M(LBn) 2]Cl2 (M = Ni (5) and Pd (6)) were prepared by direct deprotonation of 1a with M(OAc)2. The two carbenic carbon donor are cis- to each other in both 3a and 4a, thus imposing the weaker σ-benzimidazole nitrogen donor to be trans to them. A sterically demanding mesityl pendant however gives the dinuclear dissymmetic [Ag2(L Mes)2Cl2], 2b (Mes = mesityl) that shows a 12-membered metallomacrocyclic ring with a 2-coordinated [AgI(NHC) 2] and 4-coordinated [AgI(Imd)2Cl2] (Imd = imidazole). Transmetallation of the latter, or direct metallation from [HLMes]Cl, 1b, gives [M(LMes)2]Cl2 (M = Ni (3b) and Pd (4b)) with the two carbonic carbon trans to each other. The catalytic potential of 3b and 4b, which are more effective than 5 and 6, has been demonstrated by their high activities in Ni-catalyzed Kumada at room temperature and Pd-catalyzed Heck couplings of aryl and/or heteroaryl halides, respectively. © 2010 The Royal Society of Chemistry. |
Persistent Identifier | http://hdl.handle.net/10722/219631 |
ISSN | 2023 Impact Factor: 3.5 2023 SCImago Journal Rankings: 0.697 |
ISI Accession Number ID | |
Errata |
DC Field | Value | Language |
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dc.contributor.author | Li, Fuwei | - |
dc.contributor.author | Hu, Jian Jin | - |
dc.contributor.author | Koh, Lip Lin | - |
dc.contributor.author | Hor, T. S Andy | - |
dc.date.accessioned | 2015-09-23T02:57:34Z | - |
dc.date.available | 2015-09-23T02:57:34Z | - |
dc.date.issued | 2010 | - |
dc.identifier.citation | Dalton Transactions, 2010, v. 39, n. 22, p. 5231-5241 | - |
dc.identifier.issn | 1477-9226 | - |
dc.identifier.uri | http://hdl.handle.net/10722/219631 | - |
dc.description.abstract | Homoleptic cationic benzimidazole-imidazolin-2-ylidene N-heterocyclic carbene (NHC = L) complexes of NiII and PdII have been prepared directly from the ligand precursor in salt form [H.L]Cl and from the transmetallation route via AgI. The N-tether of the imidazolinylidene ring imposes a significant influence on the nuclearity of the intermediate Ag(i)-NHC complexes and the geometric isomer outcome of the d8 products. Use of a benzyl-substituted NHC gives [Ag4(L Bn)2Cl4], 2a (from [HLBn]Cl, 1a, and Ag2O) (Bn = benzyl), which shows an alignment of four silver atoms bridged by the difunctional C-N ligands and chlorides. Its transmetallation with NiCl2(PPh3)4 and PdCl2(MeCN) 2 results in double-metal salts 2[M(LBn)2] 2+[Ag4Cl8]4- (M = Ni (3a) and Pd (4a)). The nuclearity of the Ag4 aggregate is maintained in the transmetallation process. Their Ag-free forms [M(LBn) 2]Cl2 (M = Ni (5) and Pd (6)) were prepared by direct deprotonation of 1a with M(OAc)2. The two carbenic carbon donor are cis- to each other in both 3a and 4a, thus imposing the weaker σ-benzimidazole nitrogen donor to be trans to them. A sterically demanding mesityl pendant however gives the dinuclear dissymmetic [Ag2(L Mes)2Cl2], 2b (Mes = mesityl) that shows a 12-membered metallomacrocyclic ring with a 2-coordinated [AgI(NHC) 2] and 4-coordinated [AgI(Imd)2Cl2] (Imd = imidazole). Transmetallation of the latter, or direct metallation from [HLMes]Cl, 1b, gives [M(LMes)2]Cl2 (M = Ni (3b) and Pd (4b)) with the two carbonic carbon trans to each other. The catalytic potential of 3b and 4b, which are more effective than 5 and 6, has been demonstrated by their high activities in Ni-catalyzed Kumada at room temperature and Pd-catalyzed Heck couplings of aryl and/or heteroaryl halides, respectively. © 2010 The Royal Society of Chemistry. | - |
dc.language | eng | - |
dc.relation.ispartof | Dalton Transactions | - |
dc.title | Substituent-dependent structures and catalysis of benzimidazole-tethered N-heterocyclic carbene complexes of Ag(i), Ni(ii) and Pd(ii) | - |
dc.type | Article | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1039/c000722f | - |
dc.identifier.pmid | 20440424 | - |
dc.identifier.scopus | eid_2-s2.0-77953497712 | - |
dc.identifier.volume | 39 | - |
dc.identifier.issue | 22 | - |
dc.identifier.spage | 5231 | - |
dc.identifier.epage | 5241 | - |
dc.identifier.eissn | 1477-9234 | - |
dc.identifier.isi | WOS:000278099800006 | - |
dc.relation.erratum | doi: 10.1039/c0dt90099k | - |
dc.relation.erratum | eid: eid_2-s2.0-78649702742 | - |
dc.identifier.issnl | 1477-9226 | - |