
%0 Journal Article
%A Graddon, DP 
%A Siddiqi, IA 
%T Thermodynamics of metal-ligand bond formation. XXIX. Nickel(II) dialkylmonothiocarbamate complexes
%J Australian Journal of Chemistry
%D 1977/10/01
%V 30
%N 10
%P 2133-2141
%K 
%R https://doi.org/10.1071/CH9772133
%U https://www.publish.csiro.au/paper/CH9772133 
%X In benzene solution at concentrations below 10-2 M, measurements of molecular weights, absorption spectra and the enthalpies of reaction with bases are all consistent with Ni(SOCNR2)2 (R = Pr or Bu) existing as an equilibrium between low-spin monomeric and high-spin dimeric, probably five-coordinate, species. Enthalpies of dimerization are about -55 kJ (g-atom Ni)-1 and dimerization constants increase from 250 l. mol-1 at about 5°C to 1000 l. mol-1 at 30°C, which shows that the entropy of dimerization is not temperature-invariant. Addition of bidentate bases to the monomer is quantitative with &#916;H° about -100 kJ mol-1. Addition of pyridine, 4-methylpyridine or piperidine occurs in two steps, giving high-spin adducts, first five-coordinate NiL2B then six-coordinate NiL2B2 with K1 &#8776; K2, &#916;H1° &#8776; -100 and &#916;H2° near zero. Comparisons are made with other low-spin nickel(II) complexes which form high-spin polymers or adducts. 
