Multinuclear copper complexes of pyridylmethylamide ligands

Abstract

Copper complexes of a family of pyridylmethylamide ligands HL^Ph, HL^Me3 and HL^Ph3 were synthesized and characterized [HL^Ph = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL^Me3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL^Ph3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide]. The reaction of copper(II) salts with the HL family and triethylamine in methanol yields copper(II) complexes [Cu₄(L^Ph)₄(OH)₂](ClO₄)₂ (1), [Cu₂(HL^Me3)₂(OMe)₂(MeOH)₂](OTf)₂ (2) and [Cu₂(HL^Ph3)₂(OMe)₂(MeOH)₂](OTf)₂ (3). The complexes have different nuclearity owing to varying steric properties of the ligands used. Complex 1 self-assembles in the presence of excess base to form a tetranuclear complex. Complexes 2 and 3 are binuclear and are bridged by a pair of methoxide ligands. Steric encumbrance of the ligands in 2 and 3 prevent cluster formation.