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Synthetic Routes to Methylpalladium(II) and Dimethylpalladium(II) Chemistry and the Synthesis of New Nitrogen Donor Ligand Systems

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Byers, PK and Canty, AJ (1990) Synthetic Routes to Methylpalladium(II) and Dimethylpalladium(II) Chemistry and the Synthesis of New Nitrogen Donor Ligand Systems. Organometallics, 9 (1). pp. 210-220. ISSN 0276-7333

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Abstract

Convenient and widely applicable synthetic routes to methylhalogenopalladium(II), PdXMe(L2), and dimethylpalladium(II) complexes, PdMe2(L2), have been developed, including complexes of triphenylphosphine and a wide range of bidentate nitrogen donor ligands. These routes involve either the generation of Pd"Me, species at low temperature from methyllithium reagents and trans-PdCl2(SMe2)2 followed by addition of ligand, PdIMe(2,2'-bipyridyl) being synthesized through the oxidative-addition reactivity of Pd2(dba)3(CHCl3), or the facile synthesis of complexes with the reagents [PdIMe(SMe2)]2 and [PdMe2(pyridazine)], in organic solvents at ambient temperature. These reagents are particularly suitable for ligands sensitive to MeLi reagents, and [PdIMe(SMe2)]2 is also a suitable substrate for the synthesis of chloro and bromo complexes, PdXMe(L2), including PPh3 complexes. Several new nitrogen donor bidentate ligands are described, containing 1-methylimidazol-2-y1(mim) and pyridin-2-y1 (py) groups in (mim)2C=CH2 and (py)(mim)C=CH2 as relatives of planar ligands such as 2,2'-bipyridyl and mim, py, and pyrazol-1-yl (pz) groups in (py)(mim)CH2, (py)(mim)CHMe, (mim)2CH2, (mim)2CHMe, and (pz)(mim)CH2 as relatives of ligands such as (py)2CH2 and (pz)2CH2. Methylpalladium(II) complexes of unsymmetrical bidentate ligands exhibit isomerism; e.g., isomers of PdIMe[(py)(mim)C=O] occur in the ratio 9:1, where the dominant isomer has the pyridine ring trans to methyl. The ligands with methane bridges, e.g. (pz)(py)CH2, ethane bridges, e.g. (pz)2CHMe, and propane bridges, e.g. (py)CMe2, form complexes PdMe2(L2) and PdIMe(L2) that exhibit variable-temperature NMR spectra indicating boat-to-boat inversion of the chelate ring, but complexes of (mim)2CHMe and (py)(mim)CHMe appear to adopt only the conformation with the methyl group axial and adjacent to palladium.

Item Type: Article
Keywords: Platinoid Complexes ; Transition metal Complexes ; Divalent metal Complexes ; Halo complex ; Palladium Organic compounds ; Organic ligand ; Nitrogen heterocycle ; Five membered ring ; Six membered ring ; Ketone ; NMR spectrum ; Conformation ; Palladium II Complexes ;
Journal or Publication Title: Organometallics
Page Range: pp. 210-220
ISSN: 0276-7333
Identification Number - DOI: 10.1021/om00115a033
Date Deposited: 26 Mar 2008 21:23
Last Modified: 18 Nov 2014 03:27
URI: http://eprints.utas.edu.au/id/eprint/2896
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