The development of efficient water oxidation catalysts (WOCs) is of key importance in order to drive sustainable reductive processes aimed at producing renewable fuels. Herein, two novel dinuclear complexes, [(Cp*Ir)₂(μ-κ³-O,N,O-H₄-EDTMP)] (Ir-H₄-EDTMP, H₄-EDTMP⁴⁻ = ethylenediamine tetra(methylene phosphonate)) and [(Cp*Ir)₂(μ-κ³-O,N,O-EDTA)] (Ir-EDTA, EDTA⁴⁻ = ethylenediaminetetraacetate), were synthesized and completely characterized in solution, by multinuclear and multidimensional NMR spectroscopy, and in the solid state, by single crystal X-Ray diffraction. They were supported onto rutile TiO₂ nanocrystals obtaining Ir-H₄-EDTMP@TiO₂ and Ir-EDTA@TiO₂ hybrid materials. Both molecular complexes and hybrid materials were found to be efficient catalysts for WO driven by NaIO₄, providing almost quantitative yields, and TON values only limited by the amount of NaIO₄ used. As for the molecular catalysts, Ir-H₄-EDTMP (TOF up to 184 min⁻¹) exhibited much higher activity than Ir-EDTA (TOF up to 19 min⁻¹), likely owing to the higher propensity of the former to generate a coordination vacancy through the dissociation of a Ir–OP bond (2.123 Å, significantly longer than Ir–OC, 2.0913 Å), which is a necessary step to activate these saturated complexes. Ir-H₄-EDTMP@TiO₂ (up to 33 min⁻¹) and Ir-EDTA@TiO₂ (up to 41 min⁻¹) hybrid materials showed similar activity that was only marginally reduced in the second and third catalytic runs carried out after having separated the supernatant, which did not show any sign of activity, instead. The observed TOF values for hybrid materials are higher than those reported for analogous systems deriving from heterogenized mononuclear complexes. This suggests that supporting dinuclear molecular precursors could be a successful strategy to obtain efficient heterogenized water oxidation catalysts.

开发高效的水氧化催化剂 (WOC) 对于推动旨在生产可再生燃料的可持续还原过程至关重要。在此，两个新型双核络合物，[(Cp*Ir) ₂ (μ- κ ³ -O,N,OH ₄ -EDTMP)] ( Ir-H ₄ -EDTMP , H ₄ -EDTMP ⁴⁻ = 乙二胺四(亚甲基膦酸盐) )) 和 [(Cp*Ir) ₂ (μ- κ ³ -O,N,O-EDTA)] ( Ir-EDTA , EDTA ⁴⁻= 乙二胺四乙酸盐)，在溶液中通过多核和多维核磁共振光谱法以及在固态下通过单晶 X 射线衍射进行了合成和完全表征。将它们负载到金红石TiO ₂纳米晶体上获得Ir-H ₄ -EDTMP@TiO ₂和Ir-EDTA@TiO ₂杂化材料。发现分子复合物和杂化材料都是由 NaIO ₄驱动的 WO 的有效催化剂，提供几乎定量的产率，并且 TON 值仅受所用 NaIO ₄的量限制。至于分子催化剂，Ir-H ₄ -EDTMP（TOF 高达 184 分钟^-1) 表现出比Ir-EDTA更高的活性（TOF 长达 19 分钟^-1），可能是由于前者更倾向于通过 Ir-OP 键的解离产生配位空位（2.123 Å，比 Ir 长得多–OC, 2.0913 Å)，这是激活这些饱和复合物的必要步骤。Ir-H ₄ -EDTMP@TiO ₂（长达 33 分钟^-1）和Ir-EDTA@TiO ₂（长达 41 分钟^-1) 混合材料显示出类似的活性，在分离上清液后进行的第二和第三次催化运行中仅略微降低，而没有显示任何活性迹象。观察到的杂化材料的 TOF 值高于针对衍生自异质化单核复合物的类似系统所报告的值。这表明支持双核分子前体可能是获得高效多相水氧化催化剂的成功策略。