Three coordinate copper (I) complexes. Synthesis, spectral, and structural study of copper (I) complexes of 4-benzoylpyridine and X-ray crystal structure of the dimer [CuCl (4-benzoylpyridine) ] 2

Abstract

Yellow to red–brown copper (I) complexes of the type CuXL for X=Cl, Br,I, CN, SCN and N 3 and CuXL 2 for X−NO 3 and ClO 4, where L=4-benzoylpyridine, have been synthesized and characterized. All complexes exhibit MLCT bands in the visible region and the neutral complexes gave non-conducting solutions in DMF. The IR and Raman spectral data suggest monodentate 4-Bzpy, bridging halides or pseudohalides, bidentate nitrate and perchlorate in the respective complexes in the solid state. The structure of the 1:1 chloride complex, as determined by X-ray crystallography, features a discrete centrosymmetric [CuCl (4-benzoylpyidine) ] 2 molecule with a Cu···Cu distance of 2.953 Å. Each copper atom in the dimeric molecule is trigonally planar coordinated by two μ-chlorine atoms and the nitrogen atom of 4-benzoylpyridine. All the isolated complexes display emission spectra in the solid state at room temperature. The neutral halide or pseudohalide complexes show one emission band with λ em max in the range 586–642 nm which is independent of the excitation wavelength and is related to MLCT or XLCT excited state. The 1:2 nitrate and perchlorate complexes exhibit their λ em max around 468–504 nm.