Inhibition of reactivity in square planar complexes of Ni(II) with 2,6-disubstituted pyridines. A novel effect in steric hindrance

Pyridine type complexes of transition-metal halides XI.Structural, thermal and spectroscopic studies of aminopyridine complexes of cobalt(II) halides

Crystalline ternary mixed aminopyridine complexes of cobalt(II) chlorides and cobalt(II) bromides have been prepared and analysed by means of thermal (TG, DTG, DTA) methods, UV/VIS spectroscopy, magnetic measurements and X-ray powder diffraction techniques. The symmetry and cell dimensions have been calculated using TREOR 90, a trial-and-error indexing program. One of the compounds, namely the [Co(3-NH2-pyridine)4Cl2] complex has been studied also by X-ray single-crystal diffraction, yielding a propeller-shaped molecule with octahedral co-ordination, exhibiting both molecular and crystallographic inversion symmetry. Crystal data: C20H24N8Cl2Co, Mw = 506.30, triclinic (P-1) unit cell with a = 7.684(1), b = 8.582(1), c = 9.966(2) Å, α = 73.17(1), β= 69.97(1), γ = 70.33(1)°, Vc = 570.0(2) Å3 and Z = 1. The structure model was refined to R = 0.027 and wR = 0.037 for 2680 reflections with I > 3σ(I).