title: Isolation of a pentadentate ligand and stepwise synthesis, structures, and magnetic properties of a new family of homo- and heterotrinuclear complexes.
abstract: A neutral pentadentate ligand, di(pyrazolecarbimido)amine (Hdcadpz), and its adduct with HClO4, [H2dcadpz]+[ClO4]-, were for the first time isolated from our previously reported [Cu3(dcadpz)2(Hpz)2(ClO4)2](ClO4)2.H2O by the use of (NH4)2S to remove the CuII ions and characterized by IR, EA, UV, NMR, MS, and X-ray crystallography. Reactions of copper(II) or nickel(II) nitrate with Hdcadpz in a 1:2 molar ratio generated two mononuclear precursors of [Cu(dcadpz)2] (1) and [Ni(dcadpz)2].2/3DMF (2). Furthermore, three new linear homo- and heterotrinuclear complexes of the same motif [M{M'(dcadpz)2}M] (M=CoII, NiII, M'=CuII, NiII), [{Co(pdm)}2{Cu(dcadpz)2}](NO3)4 (3), [{Ni(pdm)}2{Cu(dcadpz)2}](NO3)4 (4), and [{Ni(MeOH)(H2O)2}2{Ni(dcadpz)2}](NO3)4 (5), were synthesized from these two precursors (pdm=2,6-pyridinedimethanol) and characterized by X-ray crystallography. Magnetic studies show that the central Cu(dcadpz)2 motif is antiferromagnetically coupled with both the terminal Co(II) atoms via the dcadpz- ligand in 3 with a J value of -5.27 cm(-1) and ferromagnetically coupled with both the terminal Ni(II) atoms in 4 with a J value of 2.50 cm(-1), while 5 behaves only as a Curie paramagnet between 2 and 300 K due to the diamagnetic character of the central square-planar Ni(II) atom.
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Zheng
authors.forename: Wei-Xiong
authors.initials: WX
authors.lastname: Zhang
authors.forename: Lian-Jing
authors.initials: LJ
authors.lastname: Qin
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Leng
authors.forename: Jun-Xian
authors.initials: JX
authors.lastname: Lu
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Tong
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008024:Ligands; D008280:Magnetics; D008958:Models, Molecular; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D008024:Ligands