Ein einkerniger Cobalt‐Komplex mit einem neuartigen fünfzähnigen Liganden (siehe Bild) katalysiert die Entwicklung von Wasserstoff in ausschließlich wässriger Lösung. Der Komplex könnte als Elektro‐ sowie als Photokatalysator zur effizienten Bildung von Wasserstoff verwendet werden.

The synthesis, characterization, and water oxidation activity of mononuclear ruthenium complexes with tris(2-pyridylmethyl)amine (TPA), tris(6-methyl-2-pyridylmethyl)amine (Me(3)TPA), and a new pentadentate ligand N,N-bis(2-pyridinylmethyl)-2,2'-bipyridine-6-methanamine (DPA-Bpy) have been described. The electrochemical properties of these mononuclear Ru complexes have been investigated by both experimental and computational methods. Using Ce(IV) as oxidant, stoichiometric oxidation of water by [Ru(TPA)(H(2)O)(2)](2+) was observed, while Ru(Me(3)TPA)(H(2)O)(2)](2+) has much less activity for water oxidation. Compared to [Ru(TPA)(H(2)O)(2)](2+) and [Ru(Me(3)TPA)(H(2)O)(2)](2+), [Ru(DPA-Bpy)(H(2)O)](2+) exhibited 20 times higher activity for water oxidation. This study demonstrates a new type of ligand scaffold to support water oxidation by mononuclear Ru complexes.

Early intermediates of catalytic water reduction by a Co(II)-polypyridyl species have been characterized. Electrochemical detection of the Co(III)-hydride and time-resolved spectroscopic detection of the Co(I)-ligand intermediates provide an understanding of their reactivity in electrolytic or light-driven reduction of protons to hydrogen.

On the sunny side: A homogeneous system for H2 production and hydrocarbon oxidation was developed in the absence of any sacrificial reagent. This system consists of [Ru(TPA)(H2O)2]2+ and [Fe3(CO)12] as catalysts and [Ru(bpy)3]2+ and [Ir(bpy)(ppy)2]+ as photosensitizers (PS). Water is the oxygen source as well as the source for H2 formation (see picture; Sub=organic substrate).

Two iron(II) complexes with tetraazadentate ligands have been synthesised, characterised and evaluated as water oxidation catalysts. The two ligands, N,N′-diisopropyl-N,N′-bis(2-pyridylmethyl)-1,2-diaminoethane (1), and N-methyl-N-(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine (2), both give iron(II) complexes (1Fe and 2Fe, respectively) with an octahedral coordination geometry with two labile triflate ligands in a cis configuration in the crystal structures. When treated with cerium(IV)