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,

Insertion of carbon monoxide and alkenes in palladium-carbon bonds of complexes containing rigid bidentate nitrogen ligands: the first example of isolated complexes in stepwise successive insertion reactions on the way to polyketones van Asselt, R.; Gielens, E.E.C.G.; Rulke, R.E.; Vrieze, K.; Elsevier, C.J. Published in:Journal of the American Chemical Society DOI:10.1021/ja00082a020Link to publication Citation for published version (APA):van Asselt, R., Gielens, E. E. C. G., Rulke, R. E., Vrieze, K., & Elsevier, C. J. (1994). Insertion of carbon monoxide and alkenes in palladium-carbon bonds of complexes containing rigid bidentate nitrogen ligands: the first example of isolated complexes in stepwise successive insertion reactions on the way to polyketones. Journal of the American Chemical Society, 116, 977-985. DOI: 10.1021/ja00082a020 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. 0002-786319411516-0977$04.50/0complexes of the type PdXZ(L-L) (L-L is a chelating phosphorus or nitrogen ligand, X is a weakly or noncoordinating anion). The reaction is proposed to proceed via a perfectly alternating sequence of carbon monoxide and alkene insertions in palladium-carbon bonds (Scheme 1),4b,h An alternative mechanism involving palladium carbene intermediates, explaining the formation of spiroketals as the initial products,4g." has recently been proposed."A lot of experimental2 and theoretical6 research has been devoted to insertion of carbon monoxide in metal-carbon bonds, which can be regarded as a fundamental step in the copolymerization reactions. Studies on square-planar 16-electron complexes of palladium(I1) or platinum(I1) containing phosphine ligands have revealed that insertion of carbon monoxide occurs Alkenes insert readily into palladium-carbon bonds, as demonstrated by numerous examples of the Heck reaction.Io Furthermore, a variety of complexes formed by insertion of (strained) alkenes in palladium-acyl bonds has been isolated.Il From a theoretical study on alkene insertions in platinum-hydride bonds, it appeared that insertion from a four-coordinate intermediate is the preferred reaction pathway.'* Intramolecular insertions of alkynes and alkenes in palladium-carbalkoxy bonds were shown to proceed via a four-coordinate intermediate,Ila but intramolecul...

Zerovalent palladium and platinum complexes containing rigid bidentate nitrogen ligands and alkenes: synthesis, characterization, alkene rotation and substitution reactions. X-ray crystal structure of [Bis((2,6-diisopropylphenyl)imino)acenaphthene](maleic van Asselt, R.; Elsevier, C.J.; Smeets, W.J.J.; Spek, A.L. Published in: Inorganic Chemistry DOI: 10.1021/ic00085a050Link to publication Citation for published version (APA):van Asselt, R., Elsevier, C. J., Smeets, W. J. J., & Spek, A. L. (1994). Zerovalent palladium and platinum complexes containing rigid bidentate nitrogen ligands and alkenes: synthesis, characterization, alkene rotation and substitution reactions. X-ray crystal structure of [Bis((2, General rights It 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. A number of zerovalent palladium and platinum M(NN)(alkene) complexes, containing the rigid bidentate nitrogen ligands bis(ary1imino)acenaphthene (Ar-BIAN) and bis(pheny1imino)camphane (Ph-BIC) have been synthesized and characterized. Stable complexes were obtained with electron poor alkenes, such as dimethyl fumarate, fumaronitrile, maleic anhydride, and tetracyanoethylene. Complexes bearing asymmetric Ar-BIAN or Ph-BIC ligands occurred as mixtures of isomers. From IR, UV, and 'H and 13C NMR spectroscopy and from substitution reactions it was concluded that the back-donation of electron density from the metal to the alkene is the major factor determining the stability of the complexes. Some of the complexes show fluxional behavior on the NMR time scale, which was explained by rotation of the alkene around the metal-alkene bond. The estimated rotation barriers of 50-69 kJ/mol for Pd and >72 kJ/mol for Pt are high as compared to reported values for other palladium and platinum alkene complexes. IntroductionThere has been considerable interest in the chemistry of palladium and platinum complexes containing *-coordinated unsaturated ligands,*J which may, apart from the interesting structure of and bonding in this type of complexes, be ascribed to the fascinating catalytic reactions involving platinum and palladium $-alkene and +alkyne comple~es.~ In most cases, the active species are divalent complexes, and as a consequence

Stabilization of high oxidation states by rigid bidentate nitrogen ligands: synthesis and characterization of diorgano-and triorganopalladium(IV) and cationic triorganoplatinum(IV) complexes van Asselt, R.; Rijnberg, E.; Elsevier, C.J. Published in: Organometallics DOI:10.1021/om00014a049Link to publication Citation for published version (APA):van Asselt, R., Rijnberg, E., & Elsevier, C. J. (1994). Stabilization of high oxidation states by rigid bidentate nitrogen ligands: synthesis and characterization of diorgano-and triorganopalladium(IV) and cationic triorganoplatinum(IV) complexes. Organometallics, 13, 706-720. DOI: 10.1021/om00014a049 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. Dimethylpalladium(I1) and (di)methylplatinum(II) complexes containing the rigid bidentate nitrogen ligands his@-toly1imino)acenaphthene @Tol-BIAN) and bis(pheny1imino)camphane (Ph-BIC) readily undergo oxidative addition of a variety of (organic) halides, to give the corresponding octahedral diorgano-and triorganopalladium(1V) and -platinum(IV) complexes. The palladium complexes PdMeZ(R)X(NN) (RX = MeI, PhCHZBr; NN = pTol-BIAN, Ph-BIC) were synthesized and isolated a t 20 "C and were fully characterized. Reductive elimination from these complexes in chloroform obeyed first order kinetics and was slower than for other reported triorganopalladium(1V) complexes. The new diorganopalladium(1V) complexes PdMe212(NN), synthesized via oxidative addition of diiodine to PdMeANN) are much less stable than the triorganopalladium(1V) complexes studied. PtMez(R)X@Tol-BIAN) (RX = MeI, PhCHZBr, EtI, PhCH(Me)Br, MeC(O) Cl, 12) and Pt(Me)I(R)X(pTol-BIAN) (RX = MeI, PhCHZBr, 12) were obtained via oxidative addition to PtMez WTol-BIAN) and Pt(Me)I@Tol-BIAN), respectively. Reaction of PtMez(R)X(pTol-BIAN) with AgS03CF3 led to the formation of remarkably stable five-coordinate [PtMe2(R)pTol-BIAN)1SO3CF3 complexes (R = Me, CHzPh, C(O)Me), which were fully characterized and can be isolated and kept at 20 "C. The complexes are very stable toward reductive elimination, e.g. in CDCl3 and CD3CN [PtMedCHZPh)(pTol-BIAN)]SO&F3 was stable for at least 7 days a t 20 "C or 40 h at 50 "C. The analogous complex [PtMe&HzPh)(phen)IS03CF3 was also stable a t 50 "C in CD3CN for a t least 40 h, whereas [PtMez(CHZPh) @T...

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 ...