title: Ferromagnetic vs. antiferromagnetic coupling in bis(mu2-1,1-azido)dinickel(II) complexes with syn- and anti-conformations of the end-on azide bridges.
abstract: Reaction of a 1 : 1 : 1 molar ratio of NiCl(2), NaN(3) and H(2)L, a tetradentate ligand N-(2-pyridyl)methyl)-N,N-bis(2'-hydroxy-3',5'-dimethylbenzyl)amine in methanol in presence of Et(3)N results in a turquoise precipitate, which affords deep green crystals of [Ni(2)(HL)(2)(N(3))(2)]*1.5CH(2)Cl(2) (1) and [Ni(2)(HL)(2)(N(3))(2)]*H(2)O (2) upon crystallization from CH(2)Cl(2)-MeOH or THF-MeOH, respectively. Both complexes reveal distorted octahedral NiN(4)O(2) coordination environments around the Ni(ii) centers with bis(micro-1,1-azido) bridging ligands. Complex 1 displays an unprecedented small Ni-N-Ni bridge angle of 90.4 degrees , whereas 2 contains the said angle of av. 98.7 degrees lying in the usual range observed for other comparable structures. The variable-temperature magnetic susceptibility together with the variable-field, variable-temperature (VTVH) magnetization measurements discern different ground states of S(t) = 0 for 1 and S(t) = 2 for 2. The magnetic behaviours of these compounds are discussed in the context of the known bis(end-on azido) bridging dinickel(II) complexes.
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470, Mülheim an der Ruhr, Germany. Chaudh@mpi-muelheim.mpg.de
authors.forename: Phalguni
authors.initials: P
authors.lastname: Chaudhuri
authors.forename: Rita
authors.initials: R
authors.lastname: Wagner
authors.forename: Sumit
authors.initials: S
authors.lastname: Khanra
authors.forename: Thomas
authors.initials: T
authors.lastname: Weyhermüller
mesh_terms: D001386:Azides / Q000737:chemistry; D008024:Ligands; D008280:Magnetics; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D001386:Azides; D008024:Ligands; D009942:Organometallic Compounds; D009532:Nickel