Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2-Methylisothiazol-3(2H)-one in Its Metal Complexes

Abstract

Five metal complexes of 2-methylisothiazol-3(2H)-one (MIO), [Co(III)(NH3)5(MIO)](3+), [Ru(II)(NH3)5(MIO)](2+), [Ru(III)(NH3)5(MIO)](3+), [Pt(II)Cl3(MIO)](-), and trans-[U(VI)O2(NO3)2(MIO)2], were synthesized, and their structures were determined by single-crystal X-ray crystallography. MIO is an ambidentate ligand and coordinates to metal centers through its oxygen atom in the cobalt(III), ruthenium(III), and uranium(VI) complexes and through its sulfur atom in the ruthenium(II) and platinum(III) complexes. This result suggests that MIO shows preferential behavior on its donating atoms. We also studied the electron-donor abilities of the oxygen and sulfur atoms of MIO. Various physical measurements on the conjugate acid of MIO and the MIO complexes allowed us to determine an acid dissociation constant (pKa) and donor number (DN) for the oxygen atom of MIO and Lever's electrochemical parameter (EL) and a relative covalency parameter (kL) for the sulfur atom.

Exploring the boundaries of direct detection and characterization of labile isomers – a case study of copper(ii)–dipeptide systems

“…Since natural copper(II) chloride was used for the measurements, the calculated spectra were composed from the spectra of 63 Cu and 65 Cu by taking into account the ratio of hyperfine couplings according to the magnetic moments and the respective components were weighed by their natural abundances. The copper (referring to 63 Cu) and nitrogen hyperfine couplings and relaxation para-meters are given in field dimensions (gauss [G] = 10 −4 T). The EPR parameters at a given temperature Q(T ) can be calculated by a power expansion containing no more than four terms:…”

“…All metal complexes formed with multidentate ligands may exhibit linkage isomers. [60][61][62][63] By means of a "two-dimensional" approach to electron paramagnetic resonance (EPR) evaluation, 64 we have previously suggested the presence of linkage isomers in a number of copper(II) complex systems. [65][66][67][68][69] This method defines EPR intensity as a function of the magnetic field, pH and the concentration of the metal complex.…”