Copper(I) and Silver(I) Complexes of 1-alkyl-2-(methyl)-4-(arylazo)imidazole. Synthesis, Spectral Studies and Electrochemistry

2-(Methyl)-4-(arylazo)imidazole (RLH) (1, 2) are new series of azoimidazoles. Upon treatment of alkylhalide in dry THF in presence of NaH has synthesised 1-alkyl-2-(methyl)-4-(arylazo)imidazole (RLR′) (3, 4). They belong to the azoimine family of N,N′-chelating ligand. They stabilize the Cu(I) oxidation state and we have synthesized Cu(RLR′)₂](ClO₄) (5, 6). These complexes show a moderately intense visible band (500–600 nm) which has been assigned to 3d(Cu) → π*(ligand) transition. Ag(I) complexes of RLR′ (7, 8) are also very stable under ambient conditions and show weak transitions in the visible region. The Cu(I)-complexes show high potential Cu(II)/Cu(I) redox couple > 0.4 V vs Ag, AgCl/Cl⁻ reference electrode. All these complexes have been structurally characterized by ¹H NMR spectroscopic data.