Formation of Ternary Complexes of Iron(III) Cations in Solution and Gas Phase

Abstract

Formation of labile 1 : 1 : 1 ternary mononuclear complexes of iron(iii) cation with η3-terdentate meridional binders was studied using electrospray ionisation mass spectrometry (ESI-MS) titration and UV-Vis titration in solution phase. Low selectivities towards formation of ternary heteroleptic complexes in the solution phase vs. symmetric 2 : 1 complexes were obtained with combinations of dianionic 2,6-bis[hydroxy(methyl)amino]-1,3,5-triazine (BHT) ligands with monoanionic terdentate ligands such as 2-[(2-pyridinylmethylene)amino]phenol. Moderate selectivities were observed in formation of ternary iron(iii) complexes of iron(iii) between BHT ligands and neutral terdentate ligands such as pyridin-2-ylmethylpyridin-2-ylmethyleneamine. Results obtained by MS titrations were in a reasonable agreement with UV titration data indicating that quantitative ESI MS spectrometry can be applied to these labile iron(iii) complexes.