Modular bimetallic complexes with a sulfonamido-based ligand

摘要

A series of bimetallic complexes prepared with the ligands N,N,N,N-tetramethylethane-1,2-diamine (TMEDA) and N,N,N-[2,2,2-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST](3-)) is described. Four diiron compounds of the formulation (TMEDA)Fe-II(X)-(-OH)-(FeMST)-M-III were prepared, in which the X- ligands are the anions OTf-, Br-, SCN-, or N-3(-). Additionally, two heterobimetallic compounds of the formulation (TMEDA)M-II(OTf)-(-OH)-(FeMST)-M-III (M-II = Co-II or Ni-II) were synthesized. All these compounds have similar spectroscopic and structural properties. The diiron compounds exhibit perpendicular-mode electron paramagnetic resonance spectra consistent with S = 1/2 spin ground states, which is expected for high-spin Fe-II and Fe-III centres that are antiferromagnetically coupled. The heterobimetallic (TMEDA)Ni-II(OTf)-(-OH)-(FeMST)-M-III complex had a spin state of S = 3/2 that also resulted from antiferromagnetic coupling between the high-spin Ni-II and Fe-III centres. The modularity of this system is further demonstrated by the substitution of the TMEDA ligand with ethylenediamine (en); for this species two equivalents of en coordinate to the Fe-II centre to form [(en)(2)Fe-II-(-OH)-(FeMST)-M-III]OTf. These results demonstrate that a modular bimetallic system has been developed in which the key components can be modified.