A reaction of pivalate polymer [Mn(OOCCMe 3 ) 2 (EtOH)] n (1) with 3-hydroxy-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine (2, L) in EtOH solution under inert atmosphere gives rise to an antiferromagnetic 2D-polymer [Mn(μ-N,N′O-3,5-Me 2 C 3 HN 2 C 2 (O)N 4 ) 2 ] n (4). According to the X-ray analysis data, M(L–H) 2 units form a 2D-infinite network in the lattice of compound 4 where L–H is a starting deprotonated hydroxytetrazine. The reaction of 1 with bis[3,5-(dimethylpyrazolyl)]-1,2,4,5-tetrazine (3) in MeCN solution in air results in an antiferromagnetic hexanuclear pivalate cluster Mn 6 (μ 4 -O) 2 (μ-OOCCMe 3 ) 10 (L 1 ) 4 (5) where L 1 is a dimethylpyrazole molecule – product of hydrolytic splitting of initial bispyrazolyltetrazine.