A Switchable Complex Ligand Exhibiting Photoinduced Valence Tautomerism

The crystal of a valence tautomeric cobalt complex, [Co(dbbq)2(bpym)](1) (dbbq = 3,6-di-tert-butyl-1,2-benzoquinone and bpym = 2,2′-bipyrimidine), have been obtained by reaction between Co2(CO)8 and dbbq in the presence of the ligand bpym in a mixed solvent under an N2 atmosphere. The magnetic behavior of complex 1 clearly indicates that electron transfer from the catecholate ligand to the CoIII center occurs, which results in valence tautomers of [CoII(SQ)2(bpym)] with a transition temperature (T1/2) of 232(1) K. Photomagnetic studies show that complex 1 exhibits photoinduced valence tautomerism. The complex has the ability to coordinate and can be used as a photoswitchable building block.