Abstract: | The synthesis and characterization of a new unsymmetrical dinucleating N,O‐donor ligand, 2‐N,N‐bis(2‐pyridylmethyl)aminomethyl]‐6‐N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridylamino)aminomethyl]‐4‐methylphenol (H2Ldtb), as well as the X‐ray crystal structure of its corresponding mixed‐valence diacetate‐bridged manganese complex, di‐μ‐acetato‐μ‐{2‐N,N‐bis(2‐pyridylmethyl)aminomethyl]‐6‐N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridylamino)aminomethyl]‐4‐methylphenolato}dimanganese(II,III) tetraphenylborate, MnIIMnIII(C42H49N5O2)(C2H3O2)2](C24H20B), are reported. The complex may be regarded as an interesting structural model for the mixed‐valence MnII–MnIII state of manganese catalase. |