Divalent Palladium and Platinum Complexes Containing Rigid Bidentate Nitrogen Ligands and Electrochemistry of the Palladium Complexes¹

Abstract

Divalent palladium and platinum complexes containg rigid bidentate nitrogen ligands and electrochemistry of the palladium complexes van Asselt, R.; Elsevier, C.J.; Amatore, CH.; Jutand, A. Published in: Organometallics DOI:10.1021/om960578aLink to publication Citation for published version (APA):van Asselt, R., Elsevier, C. J., Amatore, C. H., & Jutand, A. (1997). Divalent palladium and platinum complexes containg rigid bidentate nitrogen ligands and electrochemistry of the palladium complexes. Organometallics, 16, 317-328. DOI: 10.1021/om960578a General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The synthesis and characterization of divalent palladium and platinum complexes of the type PdX 2 (Ar-BIAN) (X ) Cl, Br, I, OC(O)Me), PdCl 2 (Ph-BIC) and PtCl 2 (Ar-BIAN) is described. These complexes contain the rigid bidentate nitrogen ligands bis(arylimino)-acenaphthene (Ar-BIAN; Ar ) Ph, p-MeC 6 H 4 , p-MeOC 6 H 4 , o,o′-Me 2 C 6 H 3 , o,o′-i-Pr 2 C 6 H 3 ) or bis(phenylimino)camphane (Ph-BIC), which act as σ-donor ligands to the metal center, as was deduced from the observed shifts in the IR and NMR spectra of the complexes. IntroductionDivalent palladium and platinum complexes are valuable catalyst precursors and have been used in a wide variety of reactions, including carbonylation of alkenes, organic halides, and nitroaromatic compounds, 2 C-C cross coupling, 3 allylic alkylation, 4 and Heck type reactions. 5 A general feature of most of these reactions is the in situ reduction of the catalyst precursor, leading to a formal 14-electron zerovalent complex which undergoes oxidative addition of one of the reacting substrates. In situ reduction of Pd(II) precursors by Al(iBu) 2 H 3h or Li 2 (cyclooctatetraene) 6 prior to further reactions has been reported. The formation of a Pd(0) complex from the Pd(OC(O)Me) 2 /PPh 3 system has been elucidated by electrochemistry. 7 We have recently demonstrated the activity of divalent palladium complexes containing the rigid bidentate nitrogen ligands bis(arylimino)acenaphthene (Ar-BIAN) in catalytic cross coupling reactions of organic halides with organomagnesium and -zinc compounds, whereas similar reactions employing organotin reagents were more effectively catalyzed by zerovalent complexes of the type Pd(Ar-BIAN)(alkene). 8 ...

Microwave-assisted aqueous Suzuki coupling reactions catalyzed by ionic palladium(II) complexes

“…Diagnostic of chelating ligand coordination in these complexes is the downfield shift in the 1 HNMR spectra of the imine signal by 0.3-0.4 ppm upon coordination to the Pd(II) centre. Similar shifts have been observed in related compounds [18,25,[30][31][32]. The imine signals in the 13 CNMR spectra also show a downfield shift of 10.1-16.3 ppm upon metal coordination.…”

Synthesis, Characterization, and Protonation Reactions of Ar‐BIAN and Ar‐BICAT Diimine Platinum Diphenyl Complexes

“…[46] The Ar-BIAN system is a highly stable, rigid bidentate spectator ligand with interesting electronic properties. [47,48] Elsevier and co-workers suggested that Ar-BIAN ligands may act as stronger σ-donors toward the metal when compared to bpy, and also proposed that the rigid Ar-BIAN ligands are rather comparable to open chain R-DAB analogues in electronic properties, which would be the case if the diimine system in the Ar-BIAN ligands is electronically isolated from and has no conjugation with the naphthalene backbone. [35] The capacity of this ligand type to support many oxidation states has been amply demonstrated; for example, Pt Ar-BIAN complexes have been reported in oxidation states ranging from Pt 0 [35] via Pt II [45] to Pt IV .…”

Macrocyclic Double Ferrocenes, Their Stereostructure, and an IR and NMR Spectroscopic, X‐ray Crystallographic, and Conformational and Dynamic Investigation

“…[3] A series of further rigid 1,4-bidentate ligands, [4] diferrocenyl-substituted 1,5-bidentate ligands [5] and non-rigid 1,4-nitrogen ligands with ferrocenyl Schiff-base units, [6] as well as a few interesting mononuclear zinc, copper, [6] nickel, [7] platinum [8] and binuclear palladium and platinum [9] complexes have also been described. The number of known examples of nitrogen-containing macrocycles with two bridged ferrocene units is, however, limited.…”