6533b7d9fe1ef96bd126c104

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Ferromagnetism in Cu II 4 and Co II 4 Complexes Derived from Metal‐Assisted Solvolysis of Di‐2,6‐(2‐pyridylcarbonyl)pyridine: Syntheses, Structures, and Magnetic Properties

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Metal-assisted solvolysis of di-2,6-(2-pyridylcarbonyl)pyr-idine (pyCOpyCOpy, dpcp) by M(0 2 CMe) 2 ·xH 2 O (M II = Cu II , CO II ) led to complex [Cu 4 {pyC(O) 3 pyC(O)(OEt )py}(O 2 CMe )5-(EtOH) 2 ] (1), when the reaction was carried out in EtOH, and to complex [Co4{pyC(O)(OMe )pyC(O)(OMe )py} 2 (02CMe)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 =-2ΣJ 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.