Nickel(II) complexes prepared from NNN type ligands and pseudohalogens: Synthesis, structure and thermal decomposition

Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N 3 ) 2 ]·MeOH ( I ) and thiocyanate [Nidmpp(SCN) 2 ·MeOH] ( VI ) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen to be dinuclear as stated in literature, space group P2 1 / n , monoclinic, a =10.503, b =10.681, c =13.291 Å, β=106.56° and Z =2 whereas complex VI was found to be mononuclear, space group P2 1 / n , monoclinic, a =8.646, b =12.614, c =20.697 Å, β=97.18° and Z =2. The Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing complexes, followed by irregular degradation above 300°C.