Coordination bond formation at charge-transfer phase transition in (BDTA)2[Co(mnt)2

The crystal structure of a charge-transfer salt, (BDTA)2Co(mnt)2], where BDTA is 1,3,2-benzodithiazolyl and mnt is maleonitriledithiolate, consisted of an alternating stacking column of a head-to-head BDTA+ dimer and a planar Co(mnt)2]2- dianion at 253 K. Magnetic measurements and structural analyses revealed a phase transition at 190 K, where a partial electron transfer occurred from Co(mnt)2]2- to one of the BDTA+ cations, forming a coordination bond between the two.