Two tetranuclear 3d-4f heterometal complexes Mn2Ln2 (Ln = Dy, Gd): synthesis, structure, magnetism, and electrocatalytic reactivity for water oxidationElectronic supplementary information (ESI) available: PXRD of compounds 1 and 2, crystal structure of complex 2, and the out-of-phase signal of compounds 1 and 2. CCDC 1560827 and 1560828 for 1 and 2. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8nj00149a

In this present study, two Mn/Ln clusters, [Mn 2 Ln 2 (O 2 CMe) 6 (pdmH) 2 L](NO 3 )·H 2 O (Ln = Dy ( 1 ), Gd ( 2 )), have been synthesized and experimentally investigated by X-ray crystallography, PXRD, magneto- and electrochemistry. By X-ray analysis, it is shown that the two complexes are isomorphous, both possessing one [Mn II Mn III Ln III 2 (μ 3 -O) 2 ] 6+ core with four metal atoms in one plane arranged in a butterfly conformation. This is the first time that mixed-valent manganese (Mn II and Mn III ) and Ln III heterometal tetranuclear complexes have been isolated and characterized. Magnetic susceptibility measurements reveal that compounds 1 and 2 both display overall weak ferromagnetic exchanges between the metal ions within the clusters. The temperature dependencies of the out-of-phase ( χ M ′) and in-phase ( χ M ′) ac susceptibility signals exhibit no significant frequency-dependency for compounds 1 and 2 , which suggests that the two complexes may not be SMMs. Electrochemical studies indicate that compounds 1 and 2 can both catalyze water oxidation at a potential of ∼1.70 V with an overpotential of ∼880 mV vs. NHE, which could be due to a cooperative catalytic effect between the manganese and lanthanide ions. The two Mn 2 Ln 2 complexes can catalyze water oxidation, which may arise from the cooperative catalytic effect of the Mn/Ln ions.