Against the Norm: Non Irving–Williams Transmetalation in Transition Metal Dimers

We report the synthesis and characterization of three dinuclear 3d3d′ complexes, CuCu ([Cu2IIL(NO3)2]), MnMn ([Mn2IIL(MeOH)2(NO3)2]), and CuMn ([CuIIMnIIL(NO3)2]), that utilize the ligand, H2L (6,6′-dimethoxy-2,2’-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol). The relative stabilities of these complexes were investigated using experimental and computational techniques, revealing a non-Irving-Williams transmetalation, whereby a MnII ion can displace a CuII ion from its binding pocket in CuCu to yield the more stable CuMn complex. Magnetic characterization of the reported complexes revealed an unexpected ferromagnetic coupling between the two CuII ions of CuCu with J = +63.0 cm–1.