Dinuclear Cobalt(III) Complexes Showing a Co 2 O 2 Metallacycle

The heptadentate Schiff base H 3 L reacts with cobalt(II) acetate in methanol to form the discrete dinuclear complex Co 2 L(OAc) 2 (OMe)(H 2 O) 2 ( 1 ·2H 2 O). The reaction of 1 ·2H 2 O with NMe 4 OH·5H 2 O in methanol gives rise to displacement of the acetate by methanolate groups, yielding Co 2 L(OMe) 3 (H 2 O) ( 2 ·1H 2 O). Recrystallizations of the Schiff base, 1 ·2H 2 O and 2 ·H 2 O in different solvents, produce single crystals of H 3 L, 1 ·2.5H 2 O and 2 ·2MeOH, respectively. The crystal structures of 1 ·2.5H 2 O and 2 ·2MeOH show the cobalt atoms double bridged by and endogenous phenol oxygen atom and an exogenous methanolate oxygen donor, giving rise to Co 2 O 2 cores with Co···Co distances of ca. 2.87 Å.