Synthesis and characterization of rigid bidentate nitrogen ligands and some examples of coordination to divalent palladium. X‐ray crystal structures of bis (p‐tolylimino) acenaphthene and methylchloro [bis(o,o′‐diisopropylphenyl‐imino) acenaphthene] palladium (II)

Abstract

Abstract. The synthesis and characterization of the rigid bidentate nitrogen ligands bis4phenylim-ino)camphane (Ph-BIC) and a series of bis(ary1imino)acenaphthenes (Ar-BIAN) is described. These ligands were synthesized by the reaction of camphorquinone or acenaphthenequinone with the corresponding (substituted) aniline in the presence of ZnCI, or NiBr,, followed by removal of the metal salt in a subsequent step. NDDO calculations on pTol-BIAN showed that the electronic properties of this ligand are comparable to the open-chain analogue Ph-DAB (DAB = 1,4-diaza-1,3-butadiene). The aromatic group on the imine N atom of Ar-BIAN ligands is orientated out of the bis(imin0)acenaphthene plane, leading to the formation of syn and anti isomers for the ortho-substituted derivatives o-MeC6H4-BIAN and o-iPrC6H,-BIAN. In solution one isomer is observed for these ligands, but upon coordination to a Pd(Me)CI fragment both syn and anti forms are present, as two isomers are formed. Furthermore, the attempted synthesis of bis(isopropy1imino)cyclohexane is described, but it was found that a tautomeric imine-enamine compound is formed which coordinates to palladium(I1) in a monodentate fashion, which could not be converted to a chelating ligand. The structures of pTol-BIAN and Pd(Me)Cl (o,o'-iPr,C,H,-BIAN) in the solid state were determined by X-ray diffr2ction. pTol-BIAN is monoclinic, space group C2,

Stepwise Successive Insertion of Carbon Monoxide and Allenes into Palladium−Carbon Bonds of Complexes Containing the Rigid Bidentate Nitrogen Ligand Bis(p-anisylimino)acenaphthene

“…The angles between the plane of the acenaphthene backbone and the aromatic substituents on the nitrogen atoms are 77.3(4) and 77.8-(4)°, which is larger than found for free p-Tol-BIAN (55-60°) 24 but smaller than the angles observed for Pd(Me)-Cl(o,o′-iPr 2 C 6 H 3 -BIAN) (about 84°), 24 in which two ortho isopropyl substituents are present on the aromatic groups. Successive Insertion of CO and Allenes.…”

Catalyst activity or stability: the dilemma in Pd-catalyzed polyketone synthesis

“…For Ar-BIANs, (E,E) and (E,Z) isomers are possible regarding to the relative configuration of the aryl rings with respect to the C=N imine bonds. In general, only the E,E isomer is observed for symmetrical Ar-BIANs, 19 but a variable amount of the E,Z isomer is always found in the case of nonsymmetrical Ar,Ar′-BIAN derivatives [16][17][18]20 and for alkyl-BIANs. 22,23 For both ligands 3 and 7, the 1 H NMR spectrum recorded at room temperature in CDCl 3 and CD 2 Cl 2 , respectively, indicated the presence in solution of the E,E isomer only.Though this was expected for the latter, it is surprising for the former.…”

“…The synthetic methodology for ligand 7 is based on the well known condensation reaction of acenaphthenequinone with 3,5-difluoro aniline in the presence of ZnCl 2 as templating agent. 19,20 The synthesis of the new nonsymmetrical Ar,Ar′-BIAN 3 was performed by the transimination reaction between the zinc derivative of ligand 7 and 3,4,5-trimethoxy aniline (Scheme 1), similarly to what was previously described by some of us for other nonsymmetrical Ar,Ar'-BIAN derivatives. 16 The reaction proceeds quickly and the mixed ligand could be isolated in 52 % yield after chromatographic purification.…”

Combined Low Temperature Rapid Scan and1H NMR Mechanistic Study of the Protonation and Subsequent Benzene Elimination from a (Diimine)platinum(II) Diphenyl Complex Relevant to Arene C−H Activation

“…The Ar-BIAN ligands, 138,161,171 the Ar-BICAT precursor 172 Ar'N=C(Cl)-C(Cl)=NAr' with Ar' = 4-MeC 6 H 4 , and Ph 2 Pt(SMe 2 ) 2 120 were prepared according to published procedures.…”