Azoimidazole gold(III) complexes: Synthesis, structural characterization and self-assembly in the solid state

Abstract

Abstract Preparation of novel triarylazoimidazole trichlorogold(III) complexes is described. The new compounds were characterized using C, H, N elemental analyses, IR, UV/Vis and X-ray diffraction analysis. Structural characterization revealed that the distances N(imidazolic)···Au (2.030 A (4) and 2.037 A (5)) are significantly shorter than N(azo group)···Au (2.853 A (4) and 2.899 A (5)) indicating that the azo group is rather weakly coordinated at the Au(III) metal center. Thus, triarylazoimidazole trichlorogold(III) complexes could be described as square planar gold(III) complexes with weakly binding to the gold(III) center azogroup. Non-covalent chlorine···chlorine interactions were detected for 5 in the solid state and studied by DFT calculations and topological analysis of the electron density distribution within the framework of Bader’s theory (QTAIM method). Theoretical studies demonstrated that short non-covalent Cl···Cl interactions (3.202 A) play crucial role in self-assembly of high-valent Au(III) chloride.