Heterogeneous reactions of solid nickel(II) complexes XXIII

Abstract

The thermal decompositions of the following compounds were studied: Ni(NCO)2(3-Etpy)~ (I), Ni(NCO)2(3-Clpy)4 (II), Ni(NCO)2(3-Brpy)4 (III), Ni(NCO)2(3-NH2py), (IV), Ni(NCO)2(3-Clpy)2.2H20 (V) and Ni(NCO)2(3-Brpy)2.2H20 (VI). The release of volatile ligands (3-Rpy and H20 ) is a two-step process, Ni(NCO)2(3-Etpy)2 (VII), Ni(NCO)2(3-Clpy)2 (VIII), Ni(NCO)2(3-Brpy)2 (IX) and Ni(NCO)2(3-NH2py)2 (X) being formed as intermediate complexes. The loss of the last molecules of volatile 3-Rpy ligands is accompanied by NCO ligand decomposition. The spectral and magnetic data indicated pseudooctahedral configuration for all complexes I-X.

Thermochemical investigation

“…All possess a small positive Weiss constant (Table 3). In agreement with the results of the other authors [1 (3] the absorption bands at 8.200 cm -~ and ~, 11.000 cm -~ can be assigned to the transition 3Bns~3E ~ and SBlg---~SB2g respectively in a weak tetragonal field of D4h symmetry. Observed lowest temperatures (T<20 K) informed that the doublet level lies above the singlet and the zero field splitting (ZFS) parameter D is positive.…”