Di-μ-halo-bis{[tris(2-pyridylmethyl)amine-κ4N]nickel(II)} bis(triethylammonium) tetraperchlorate: Magnetostructural studies

[{Ni(TPA)Br}2](ClO4)2·2HNEt3ClO4, where TPA is tris-(2-pyridylmethyl)amine, crystallizes in the monoclinic space group P21/c with Z=2, a=11.531(3) Å, b=22.141(3) Å, c=12.511(2) Å and β=107.44(1)°. The structure was determined at ambient temperature from 5519 reflections (2937 observed) with R=0.0426 and Rw=0.0404. The [{Ni(TPA)Br}2]2+ core is centrosymmetric with unsymmetrical bridges (NiBr=2.504(1) and 2.662(1) Å). Each Ni atom is pseudo-octahedral six-coordinate. Triethylammonium perchlorate cocrystallizes with the metal complex. Magnetic susceptibility studies (fit to the Ginsberg model) indicate the Ni centers are ferromagnetically coupled with J/k=10.0(5) cm−1. The chloro complex ([{Ni(TPA)Cl}2](ClO4)2·2HNEt3ClO4) is also ferromagnetically coupled with J/k=7.6(1) cm−1.