A palladacyclic N-heterocyclic carbene system used to probe the donating abilities of monoanionic chelators. Issue 23 (31st May 2018)

• Record Type: Journal Article
• Authors: Yan, Xuechao; Feng, Rui; Yan, Chunhui; Lei, Peng; Guo, Shuai; Huynh, Han Vinh
• Is Part Of: Dalton transactions. Volume 47:Issue 23(2018)
• Page Start: 7830
• Page End: 7838
• Publication Date: 2018-05-31
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt01618f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The donicities of a series of aryl-based monoanionic chelators have been determined and compared using HEP2 for the first time. Abstract : A series of NHC-containing [C^N]- or [C^C′]-type palladacyclic complexes of the general formula [PdBr( i Pr2 -bimy)(L^X)] (5–8, 11, 12, i Pr2 -bimy = 1, 3-diisopropylbenzimidazolin-2-ylidene) have been synthesized and fully characterized. Using these complexes, the donating abilities of monoanionic chelators were probed for the first time. The [C^N]-type palladacycles5–8 were prepared from acetato-bridged dipalladium complexes [Pd(μ-CH3 COO)(C^N)]2 (1–4 ) and i Pr2 -bimy·H + Br − as precursors. In the case of the [C^C′]-type NHC palladacycles (11, 12 ), the hetero-bis(NHC) complexes trans -[PdBr2 ( i Pr2 -bimy)(trz)] (8, 9, trz = 1, 2, 3-triazolin-5-ylidene) containing the i Pr2 -bimy probe were first prepared followed by acetate-assisted cyclopalladations. The 13 Ccarbene NMR signals of the i Pr2 -bimy ligands in all complexes ( i.e. HEP and HEP2 values) are found to rationally reflect the donating abilities of the incorporated trz or [L^X]-type chelators with the exception of the Bzpy ligand (Bzpy = 2-(2-pyridinylmethyl)phenyl- C, N ). This has been attributed to its larger bite angle, the resulting varied coordination geometry and the lack of electronic delocalization between the two donor units. The donicities of [L^X]-type chelators studied in this work were found to surpass those of all other bidentate ligands evaluated by HEP2 thus far.