Reactions of Co(OAc) 2 ·4H 2 O with NaQ (sodium salt of 8-quinolinol) in methanol in absence and presence of NaN 3 give the mononuclear complex mer-CoQ 3 ·MeOH (1) and a linear trinuclear mixed valence complex [Co 3 (N 3 ) 4 Q 4 (OH 2 ) 2 ]·2H 2 O (2). Presence of N3- ions prevents the formation of tris chelate leading to an aggregation to 2. Four N3- anions bridges three cobalt ions all in μ-1,1 coordination mode, resulting in a trinuclear structure with a center of inversion. The complex contains a high-spin Co II and two terminal low-spin Co III .