Heterogeneous reactions of solid nickel(II) complexes, VI

Abstract

The kinetics of the thermal decomposition of square-planar complexes of the type Ni(NCS)2L2 (L=α-picoline; 2,6-lutidine and quinoline) was studied by following the loss of weight and using the isothermal method, in the temperature range of 72–147°. The reaction order found wasn=2/3; this together with macroscopic observations indicates that it is the proper chemical process which is the controlling factor of the total decomposition rate. The values of the activation energies decrease in the following order: Ni(NCS)2 Q2 > Ni(NCS)2(2,6-lut)2 > Ni(NCS)2(α-pic)2; this points to the reaction course according to the associative activation. Except for Ni(NCS)2Q2,ΔH was found to be >E a. This experimental result may be explained by a multi-step mechanism. Possible intermediates are discussed.