Investigating the trans effect on the interaction of complex ions trans-[Ru(NH₃)₄(pyS)(L)]²⁺ on gold surface

Trans-tetraamine coordination compounds exhibit unique electronic properties due to the presence of NH₃ pi-innocent ligands in the equatorial plane. These equatorial ligands do not influence the π-backbonding interactions with the axial ligands in these complexes. Consequently, a series of these compounds facilitates a systematic investigation into how the trans effect influences their electronic and physicochemical properties. Thiol-, thioether-, and other sulfur-containing trans-tetraamine complexes are capable of spontaneously adsorbing onto noble metal surfaces. So, in this study, a series of trans-[Ru(NH₃)₄(pyS)(L)](PF₆)₂ complexes was synthesized and characterized using conventional techniques. DFT quantum calculations were employed to assign vibrational and electronic transitions and to explore the electronic properties associated with ligand L exchange. Surface plasmon resonance (SPR) and electrochemical impedance spectroscopy (EIS) were utilized to monitor the formation of self-assembled monolayers (SAMs). Additionally, the study investigated how ligand L exchange impacts the strength of the Au-S bond through reductive desorption in alkaline media.