Abstract
Metal‐assisted solvolysis of di‐2,6‐(2‐pyridylcarbonyl)pyridine (pyCOpyCOpy, dpcp) by M(O~2~CMe)~2~·x__H~2~O (M^II^ = Cu^II^, Co^II^) led to complex [Cu~4~{pyC(O)~2~pyC(O)(OEt)py}(O~2~CMe)~5~(EtOH)~2~] (1), when the reaction was carried out in EtOH, and to complex [Co~4~{pyC(O)(OMe)pyC(O)(OMe)py}~2~(O~2~CMe)~2~(N~3~)~2~] (2), when the reaction was carried out in MeOH in the presence of azide anions. Complex 1 consists of four Cu^II^ ions bridged by the hemiacetal‐gem‐diol form of the ligand, which is found in a μ~4~‐η^2^:η^2^:η^2^:η^1^:η^1^:η^1^ coordination mode. It exhibits ferromagnetic couplings among all nearest neighbors and antiferromagnetic next‐nearest‐neighbor interactions (J~12~ = J~1~ = 48.0 cm^–1^, J~23~ = J~2~ = 20.4 cm^–1^, J~34~ = J~3~ = 16.9 cm^–1^, J~24~ = J~4~ = –10.0 cm^–1^, H = –2Σ__J~i~J~j~ spin Hamiltonian formalism), which stabilize an S = 1 ground state and an S = 2 state lying closely above it. Complex 2 consists of four Co^II^ ions bridged by the bis(hemiacetal) form of the ligand, which is found in a μ~3~‐η^2^:η^2^:η^1^:η^1^:η^1^ coordination mode, and by μ~3~‐azido ligands. It also exhibits ferromagnetic interactions due to the μ~3~–1,1,1 bridging mode of the azido ligands, which is known to promote ferromagnetic interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)