title: Synthesis and 1H NMR studies of paramagnetic nickel(II) complexes containing bis(pyrazolyl)methane ligands with dendritic substituents.
abstract: The substituted bis(pyrazolyl)methane ligands RCH(3,5-Me2pz)2(R=SiMe3, CH2Ph, G1, G2, and G3; Gn=Fréchet-type dendritic wedges of generation n) have been prepared starting from H2C(3,5-Me2pz)2. Reaction of these didentate ligands with [NiBr2(DME)] is a straightforward procedure that allows the synthesis of the nickel(II) complexes [NiBr2{RCH(3,5-Me2pz)2}]. The molecular structure of compound (R=CH2Ph) has been determined by X-ray diffraction studies. The nickel centre coordinates two bromine and two nitrogen atoms in a tetrahedral environment, and the metallacycle Ni(NN)2C adopts a boat conformation with the benzyl group in an axial position. 1H NMR studies have been carried out to characterize these paramagnetic nickel compounds in solution. Valuable information about the disposition of the ligands and dendritic wedges in solution has been obtained thanks to the influence of the paramagnetic centre on the proton resonances.
authors.affiliation: Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, 28871, Alcalá de Henares, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Sánchez-Méndez
authors.forename: Jose María
authors.initials: JM
authors.lastname: Benito
authors.forename: Ernesto
authors.initials: E
authors.lastname: de Jesús
authors.forename: F Javier
authors.initials: FJ
authors.lastname: de la Mata
authors.forename: Juan C
authors.initials: JC
authors.lastname: Flores
authors.forename: Rafael
authors.initials: R
authors.lastname: Gómez
authors.forename: Pilar
authors.initials: P
authors.lastname: Gómez-Sal