1H, 13C, 195Pt and 15N NMR structural correlations in Pd(II) and Pt(II) chloride complexes with various alkyl and aryl derivatives of 2,2'-bipyridine and 1,10-phenanthroline.
ABSTRACT (1)H, (13)C, (195)Pt and (15)N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with such alkyl and aryl derivatives of 2,2'-bipyridine and 1,10-phenanthroline as LL = 6,6'-dimethyl-bpy, 5,5'-dimethyl-bpy, 4,4'-di-tert-butyl-bpy, 2,9-dimethyl-phen, 2,9-dimethyl-4,7-diphenyl-phen, 3,4,7,8-tetramethyl-phen, having the general [M(LL)Cl(2)] formula were performed and the respective chemical shifts (δ(1H), δ(13C), δ(195Pt), δ(15N)) reported. (1)H high-frequency coordination shifts (Δ(coord)(1H) = δ(complex)(1H)-δ(ligand)(1H)) mostly pronounced for nitrogen-adjacent protons and methyl groups in the nearest adjacency of nitrogen, as well as (15)N low-frequency coordination shifts (Δ(coord)(15H) = δ(complex)(15H)-δ(ligand)(15H)) were discussed in relation to the molecular structures.
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ABSTRACT: The reaction of the neutral Pd complex [Pd(CH(3))Cl(cod)] with the potentially terdentate 2-oxazolinyl phenanthroline ligands 1-3 affords the corresponding cationic dinuclear Pd-complexes 1a-3a, which can be isolated in the solid state in good yields. By treatment with AgPF(6) the complexes 1a-3a were converted into the corresponding hexafluorophosphate derivatives 1b-3b, where both the ligand units feature a terdentate coordination around the two Pd-centres with the phenanthroline fragment of each unit displaying a chelate coordination to one Pd-centre, while the corresponding oxazolinyl pendant acts as a bridging ligand towards the second Pd-centre. The persistence of this dimeric structure of 1b-3b in CD(2)Cl(2) solution was confirmed by (15)N-NMR experiments at natural abundance, which clearly show the binding to the metal of all of the nitrogen donors, as well as the overall C(2) symmetry of the compound. In consequence of the different strengths of the relevant ion-pair, the dimeric structure of the complex undergoes partial fragmentation in the case of the chloride derivatives 1a-3a, as evidenced from the (15)N-NMR spectra. Complexes 1b-3b are active catalysts in styrene alternate carbonylation, where, under very mild conditions (30 °C and 1 atm of CO), they provide oligomers with 3-5 repetitive units as the exclusive or prevailing product. When traces of the CO/styrene polyketones are also formed, their (13)C-NMR characterization shows that they are stereochemically homogeneous with a unique syndio-tacticity. This result implies that Pd-complexes able to induce a complete enantioface discrimination in the insertion step of the alkene during the catalytic cycle of the styrene alternate carbonylation have been produced for the first time.Dalton Transactions 05/2012; 41(25):7474-84. · 3.81 Impact Factor
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ABSTRACT: The butyl and isopropyl derivatives (, ) of chiral pool derived bis-imidazolium dehydrohexitol salts have been prepared. The ditopic N-heterocyclic carbenes and form dinuclear Ag(i) and Pt(ii) complexes. All compounds were fully characterised by multinuclear NMR spectroscopy. The bis-imidazolium salt and platinum complexes cis-[Pt(2)(μ-)(dmso)(2)Cl(4)] and cis-[Pt(2)(μ-)(dmso)(2)Cl(4)] were characterised by X-ray crystallography. In the case of the Pt(ii) complexes, the carbene ring is positioned in a sterically preferred orientation, approximately perpendicular to the platinum coordination plane. The (1)H, (13)C, (15)N and (195)Pt NMR spectra of the platinum complexes show the presence of rotamers due to hindered rotation about the carbene-metal bond.Dalton Transactions 09/2012; 41(41):12839-46. · 3.81 Impact Factor