Thermal Investigation of Nickel(II) Diamine Complexes in Solid State

Abstract

Abstract Three tris(ethylenediamine)nickel(II) chloride dihydrate having identical composition, apparently similar in color, magnetic moment and spectral properties showed differences in thermal profile. Thermal investigations of [Ni(en)3]Br2·2H2O, [Ni(tn)3]Cl2·2H2O, and [Ni(tn)3]Br2·H2O where en=ethylenediamine and tn=1,3-propanediamine were carried out. Several bis and mono(diamine) complexes were synthesized in solid state from the corresponding tris complexes. All the bis and mono(diamine) complexes were found to be Oh hand Td symmetry respectively. All tris(diamine) complexes generate cis bis(diamine) species upon heating. But only one tris(ethylenediamine)nickel(II) chloride dihydrate generates cis bis species by the isomerization from the trans species temporarily formed. Monodiamine complexes decomposed through [Ni2(diamine)Cl4] species which showed unusually high magnetic moment. The probable mechanistic path for each step of decomposition was also reported.