A New Thiolate‐Bound Dimanganese Cluster as a Structural and Functional Model for Class Ib Ribonucleotide Reductases

Abstract In class Ib ribonucleotide reductases (RNRs) a dimanganese(II) cluster activates superoxide (O 2 ⋅ − ) rather than dioxygen (O 2 ), to access a high valent Mn III −O 2 −Mn IV species, responsible for the oxidation of tyrosine to tyrosyl radical. In a biomimetic approach, we report the synthesis of a thiolate‐bound dimanganese complex [Mn II 2 (BPMT)(OAc) 2 ](ClO) 4 (BPMT=(2,6‐bis{[bis(2‐pyridylmethyl)amino]methyl}‐4‐methylthiophenolate) ( 1 ) and its reaction with O 2 ⋅ − to form a [(BPMT)MnO 2 Mn] 2+ complex 2 . Resonance Raman investigation revealed the presence of an O−O bond in 2 , while EPR analysis displayed a 16‐line S t =1/2 signal at g =2 typically associated with a Mn III Mn IV core, as detected in class Ib RNRs. Unlike all other previously reported Mn−O 2 −Mn complexes, generated by O 2 ⋅ − activation at Mn 2 centers, 2 proved to be a capable electrophilic oxidant in aldehyde deformylation and phenol oxidation reactions, rendering it one of the best structural and functional models for class Ib RNRs.