Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands

Abstract

The mono-dentate, pyridyl containing, nitro naphthalimide ligands N-(4-pyridyl)-4-nitro-1,8-naphthalimide (L₁) and N-(3-pyridyl)-4-nitro-1,8-naphthalimide (L₂) were prepared and complexed with a selection of copper salts [Cu(OAc)₂, Cu(CF₃SO₃)₂ and Cu(ClO₄)₂]. Crystallographic studies were undertaken and revealed that dinuclear acetate bridged complexes resulted from reactions with Cu(OAc)₂, while mononuclear systems resulted from reactions with Cu(CF₃SO₃)₂ and Cu(ClO₄)₂. Despite the differing coordination environments the naphthalimide based ligands provided a range of interesting π-based interactions in the form of π⋯π, anion⋯π, nitro⋯π, solvent⋯π and CO⋯π associations. Solid state EPR spectra were in agreement with the coordination environments observed from crystallography.