title: NiII, CuII and ZnII complexes with a sterically hindered scorpionate ligand (TpmsPh) and catalytic application in the diasteroselective nitroaldol (Henry) reaction.
abstract: The Ni(II) and Zn(II) complexes [MCl(Tpms(Ph))] (Tpms(Ph) = SO3C(pz(Ph))3, pz = pyrazolyl; M = Ni 2 or Zn 3) and the Cu(II) complex [CuCl(Tpms(Ph))(H2O)] (4) have been prepared by treatment of the lithium salt of the sterically demanding and coordination flexible tris(3-phenyl-1-pyrazolyl)methanesulfonate (Tpms(Ph))(-) (1) with the respective metal chlorides. The (Tpms(Ph))(-) ligand shows the N3 or N2O coordination modes in 2 and 3 or in 4, respectively. Upon reaction of 2 and 3 with Ag(CF3SO3) in acetonitrile the complexes [M(Tpms(Ph))(MeCN)](CF3SO3) (M = Ni 5 or Zn 6, respectively) were formed. The compounds were obtained in good yields and characterized by analytic and spectral (IR, (1)H and (13)C{(1)H} NMR, ESI-MS) data, density functional theory (DFT) methods and {for 4 and [(n)Bu4N](Tpms(Ph)) (7), the latter obtained upon Li(+) replacement by [(n)Bu4N](+) in Li(Tpms(Ph))} by single crystal X-ray diffraction analysis. The Zn(II) and Cu(II) complexes (3 and 4, respectively) act as efficient catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehydes and nitroethane to the corresponding β-nitroalkanols (up to 99% yield, at room temperature) with diastereoselectivity towards the formation of the anti isomer, whereas the Ni(II) complex 2 only shows a modest catalytic activity.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. fatima.guedes@tecnico.ulisboa.pt pombeiro@tecnico.ulisboa.pt.
authors.forename: Bruno G M
authors.initials: BG
authors.lastname: Rocha
authors.forename: Tatiana C O
authors.initials: TC
authors.lastname: Mac Leod
authors.forename: M Fátima C
authors.initials: MF
authors.lastname: Guedes da Silva
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Luzyanin
authors.forename: Luísa M D R S
authors.initials: LM
authors.lastname: Martins
authors.forename: Armando J L
authors.initials: AJ
authors.lastname: Pombeiro
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D008024:Ligands; D008698:Mesylates / Q000737:chemistry; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; D008024:Ligands; D008698:Mesylates; D009574:Nitro Compounds; C560828:nitroaldol; C045880:methanesulfonic acid; D003300:Copper; D009532:Nickel; D015032:Zinc