Cis-trans isomerism among the octahedral diaquabis(N-substituted ethylenediamine) nickel(II) complexes and their thermal reaction products: the mechanism of the thermal trans-diaqua-to-cis-dihalogeno configurational change

Article abstract of DOI:10.1016/0040-6031(94)02059-W

The thermochemical changes in the coordination structure of diaquabis(N-substituted ethylenediamine) nickel(II) complexes ([Ni(H2O)2(diamine)2]X2) were investigated by means of TG and DTA, and electronic spectroscopy, where diamine is N-methyl-(N-men), N-ethyl-(N-een), N-isopropyl-(N-ipen), N-phenyl-(N-phen), or N,N-di-n-butylethylenediamine(N,N,-dben), and X is Cl(1-) or Br(1-). The diaqua complexes prepared were all trans. Thetrans complexes with N-mono-substituted ethylenediamines brought about a deaquation-anation on heating, retaining the original trans configurat ions. Only the complex chloride with NN-dben transformed into the cis-dichloro complex upon thermal dehydration. The mechanism of the trans-to-cis configurational change of the complex chloride with NN-dben was proposed, and the effects of N-substituent group(s) upon their thermal structural changes were discussed.