Three-Coordinate Zinc Methyl Complexes with Sterically Demanding Formazanate Ligands

A series of heteroleptic three-coordinate mono(formazanate)zinc methyl complexes were synthesized, and the influence of the ligand on the structure as well as redox and optical properties of these complexes was investigated. The heteroleptic mono(formazanate)zinc methyl complexes were found to show ligand redistribution in solution, reminiscent of the Schlenk equilibrium, to generate an equilibrium mixture containing the corresponding homoleptic complexes as well. Monitoring the approach to equilibrium by NMR spectroscopy in benzene-d(6) allowed determination of the forward and backward rate constants. A correlation was found between the steric environment around the zinc center and equilibrium concentration of (formazanate)zinc methyl compounds, whereas the kinetics for approach to equilibrium are also dependent on the electronic properties.

Automated summary

A series of heteroleptic three-coordinate mono(formazanate)zinc methyl complexes were synthesized and their behavior in solution was studied, revealing ligand redistribution reminiscent of the Schlenk equilibrium. The steric environment around the zinc center was found to correlate with the equilibrium concentration of (formazanate)zinc methyl compounds, while the kinetics for approaching equilibrium were shown to be dependent on electronic properties.