title: Synthesis and coordination chemistry of a new N4-polydentate class of pyridyl-functionalized scorpionate ligands: complexes of Fe(II), Zn(II), Ni(II), V(IV), Pd(II) and use for heterobimetallic systems.
abstract: The new potentially N(4)-multidentate pyridyl-functionalized scorpionates 4-((tris-2,2,2-(pyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy, (1)) and 4-((tris-2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy(Ph), (2)) have been synthesized and their coordination behavior toward Fe(II), Ni(II), Zn(II), Cu(II), Pd(II), and V(III) centers has been studied. Reaction of (1) with Fe(BF(4))(2) x 6 H(2)O yields [Fe(TpmPy)(2)](BF(4))(2) (3), that, in the solid state, shows the sandwich structure with trihapto ligand coordination via the pyrazolyl arms, and is completely low spin (LS) until 400 K. Reactions of 2 equiv of (1) or (2) with Zn(II) or Ni(II) chlorides give the corresponding metal complexes with general formula [MCl(2)(TpmPy*)(2)] (M = Zn, Ni; TpmPy* = TpmPy, TpmPy(Ph)) (4-7) where the ligand is able to coordinate through either the pyrazolyl rings (in case of [Ni(TpmPy)(2)]Cl(2) (5)) or the pyridyl-side (for [ZnCl(2)(TpmPy)(2)] (4), [ZnCl(2)(TpmPy(Ph))(2)] (6) and [NiCl(2)(TpmPy(Ph))(2)] (7)). The reaction of (1) with VCl(3) gives [VOCl(2)(TpmPy)] (8) that shows the N(3)-pyrazolyl coordination-mode. Moreover, (1) and (2) react with cis-[PdCl(2)(CH(3)CN)(2)] to give the disubstituted complexes [PdCl(2)(TpmPy)(2)] (9) and [PdCl(2)(TpmPy(Ph))(2)] (10), respectively, bearing the scorpionate coordinated via the pyridyl group. Compounds (9) and (10) react with Fe(BF(4))(2) to give the heterobimetallic Pd/Fe systems [PdCl(2)(mu-TpmPy)(2)Fe](BF(4))(2) (11) and [PdCl(2)(mu-TpmPy(Ph))(2)Fe(2)(H(2)O)(6)](BF(4))(4) (13), respectively. Compound (11) can also be formed from reaction of (3) with cis-[PdCl(2)(CH(3)CN)(2)], while reaction of (3) with Cu(NO(3))(2) x 2.5 H(2)O generates [Fe(mu-TpmPy)(2)Cu(NO(3))(2)](BF(4))(2) (12), confirming the multidentate ability of the new chelating ligands. The X-ray diffraction analyses of compounds (1), (3), (4), (5), and (9) are also reported.
authors.affiliation: Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TU Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Wanke
authors.forename: M Fátima C
authors.initials: MF
authors.lastname: Guedes da Silva
authors.forename: Stefano
authors.initials: S
authors.lastname: Lancianesi
authors.forename: Telma F S
authors.initials: TF
authors.lastname: Silva
authors.forename: Luísa M D R S
authors.initials: LM
authors.lastname: Martins
authors.forename: Claudio
authors.initials: C
authors.lastname: Pettinari
authors.forename: Armando J L
authors.initials: AJ
authors.lastname: Pombeiro