The reactions of polynuclear cobalt(ii) trimethylacetates [Co(OH) n (OOCCMe3)2–n ] x , Co6(μ3-OH)2(OOCCMe3)10(HOOCCMe3)4, or Co4(μ3-OH)2(OOCCMe3)6(HOEt)6 with an excess of N-phenyl-o-phenylenediamine (1) in toluene followed by treatment with atmospheric oxygen afforded the diamagnetic complex [Co{η2-(NPh)(NH)C6H4}2{η1-(NH2)C6H4(NPhH)}]+(Me3CCOO...H...OOCCMe3)– (3), whose cation contains the CoIII atom. The reaction of Co4(μ3-OH)2(OOCCMe3)6(HOEt)6 with a deficient amount of diamine 1 in acetonitrile under an argon atmosphere gave rise to the antiferromagnetic ionic complex [Co{η2-(NPh)(NH)C6H4}2MeCN]+[Co2(μ2,η2-OOCCMe3)(μ2-OOCCMe3)2(η2-OOCCMe3)2]–·2MeCN (4), whose cation is an isoelectronic analog of the cation in complex 3. The structures of the new compounds were established by X-ray diffraction analysis.