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 Co-2(CO)(8) and dbbq in the presence of the ligand bpym in a mixed solvent under an N-2 atmosphere. The magnetic behavior of complex 1 clearly indicates that electron transfer from the catecholate ligand to the Co-III center occurs, which results in valence tautomers of [Co-II(SQ)(2)(bpym)] with a transition temperature (T-1/2) 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.