10.1021/ic401673z.s001 Masaru Kato Masaru Kato Kei Unoura Kei Unoura Toshiyuki Takayanagi Toshiyuki Takayanagi Yasuhisa Ikeda Yasuhisa Ikeda Takashi Fujihara Takashi Fujihara Akira Nagasawa Akira Nagasawa Preferential Behavior on Donating Atoms of an Ambidentate Ligand 2‑Methylisothiazol-3(2<i>H</i>)‑one in Its Metal Complexes American Chemical Society 2013 MIO sulfur atom EL DN oxygen atom Metal ComplexesFive metal complexes 2013-12-02 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Preferential_Behavior_on_Donating_Atoms_of_an_Ambidentate_Ligand_2_Methylisothiazol_3_2_i_H_i_one_in_Its_Metal_Complexes/2348215 Five metal complexes of 2-methylisothiazol-3­(2<i>H</i>)-one (MIO), [Co<sup>III</sup>(NH<sub>3</sub>)<sub>5</sub>(MIO)]<sup>3+</sup>, [Ru<sup>II</sup>(NH<sub>3</sub>)<sub>5</sub>(MIO)]<sup>2+</sup>, [Ru<sup>III</sup>(NH<sub>3</sub>)<sub>5</sub>(MIO)]<sup>3+</sup>, [Pt<sup>II</sup>Cl<sub>3</sub>(MIO)]<sup>−</sup>, and <i>trans</i>-[U<sup>VI</sup>O<sub>2</sub>(NO<sub>3</sub>)<sub>2</sub>(MIO)<sub>2</sub>], 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 (p<i>K</i><sub>a</sub>) and donor number (DN) for the oxygen atom of MIO and Lever’s electrochemical parameter (<i>E</i><sub>L</sub>) and a relative covalency parameter (<i>k</i><sub>L</sub>) for the sulfur atom.