Spectroscopic and solid state evaluations of tetra-aza macrocyclic cobalt complexes with parallels to the classic cobalt(II) chloride equilibrium

Complex 1 exhibits solution behavior similar to the classic cobalt(II) chloride equilibrium. When 1 is dissolved in water, the solution is pink and this complex exists as 1a , which consists of a cobalt(III) bound to L1 and two cis chlorides with a perchlorate counter-ion to balance the complex charge ([ L1 Co III Cl 2 ][ClO 4 ]).

In contrast, when 1 is dissolved in DMF or other organic solvents the solution is blue and is observed as 1b . The 1b complex salt contains two cobalt centers. One cobalt(III) is bound to L1 , Cl - , and DMF.