Effect of Ancillary Ligands in Hydrolysis of 1,8‐Naphthalic Anhydride for Synthesis of Metallacycles of Co 2+ , Ni 2+ , and Zn 2+

Di‐, tetra‐ and hexanuclear metallacycles of Zn 2+ , Co 2+ , and Ni 2+ prepared by ring‐opening reactions of 1,8‐naphthalic anhydride with corresponding metal acetate in the presence of 2,2′‐bipyridine or 1,10‐phenanthroline, namely [Co 4 (bpy) 4 (naphDA) 4 (H 2 O) 4 ] · 12H 2 O ( I ), [Co 6 (phn) 6 (naphDA) 6 (H 2 O) 12 ] · 20H 2 O ( II ), [Ni 6 (phn) 6 (naphDA) 6 (H 2 O) 12 ] · 20H 2 O ( III ), [Zn 4 (bpy) 4 (naphDA) 4 (H 2 O) 4 ] · 2H 2 O ( IV ), and [Zn 2 (phn) 2 (naphDA) 2 (H 2 O) 2 ] · H 2 O ( V ) (H 2 naphDA = 1,8‐naphthalene dicarboxylic acid, bpy = 2,2′‐bipyridine, phn = 1,10‐phenanthroline) were structurally characterized. In the case of the reaction of nickel(II) acetate with 1,8‐naphthalic anhydride in the presence of bpy a mononuclear complex [Ni(bpy)(naphDA)(H 2 O) 3 ] · H 2 O ( VI ) was observed. Both the Co 2+ ‐metallacycles on heating to 420 °C resulted in the formation of CoO. The magnetic properties of the metallacycles containing Co 2+ and Ni 2+ ions were investigated. Dominant antiferromagnetic interactions in the tetra‐ and hexanuclear Co 2+ ‐metallacycles were observed. The hexanuclear Ni 2+ ‐metallacycle III with a spin state S = 3 showed intramolecular ferromagnetic interactions. For the metallacycle III , the magnetic susceptibility data above 50 K could be reproduced with the parameters of g = 2.26 and J Ni–Ni = +1.2 cm –1 using single J ‐model based on Hamiltonian H = –2 J ( S 1 · S 2 + S 2 · S 3 + S 3 · S 4 + S 4 · S 5 + S 5 · S 6 + S 6 · S 1 ).