Reversible nitro–nitrito inter-conversion in a simple mono-nuclear nickel(II) complex [Ni II{C 6H 4(NH 2) 2} 2(NO 2) 2] in the solid state

Abstract

A simple mono-nuclear nickel(II) complex [Ni II{C 6H 4(NH 2) 2} 2(NO 2) 2] ( 1) has been synthesized from an aqueous solution containing nickel chloride, sodium nitrite and ortho-phenylenediamine (opda). When crystals of compound 1 are heated in the temperature range of 110–120 °C for 5 min, their brown color changes to blue, that is accompanied by the conversion of nitro group (N-coordinated) in compound 1 into nitrito group (O-coordinated) in compound [Ni II{C 6H 4(NH 2) 2} 2(ONO) 2] ( 2). On cooling, the nitrito compound 2 goes back to parent nitro-compound 1.