Investigation by Chemical Substitution within 2p-3d-4f Clusters of the Cobalt(II) Role in the Magnetic Behavior of [vdCoLn] (vd = Verdazyl Radical).

1,5-Dimethyl-3-(3'-(hydroxymethyl)-2'-pyridine)-6-oxotetrazane (HvdpyCHOH) or its oxidized verdazyl form (vdpyCHOH) reacted with transition metal and/or lanthanide acetates to yield [(vdpyCHO)CoLn(acO)] (Ln = Y(III): ; Gd(III): ), [(vdpyCHO)M(acO)] (M = Zn(II): ; Co(II): ) and [(vdpyCHOH)Zn(acO)] () through self-assembly implying a complex--ligand intermediate. Single-crystal diffraction reveals that are composed of 2p-3d-4f centrosymmetric clusters with verdazyl radicals at the two ends coordinated to the transition-metal ion in a tridentate mode and to the {Ln(acO)} lanthanide central core in a monodentate mode through its alkoxo moiety. In , the transition-metal ions adopt an irregular octahedral environment, and the {Ln(acO)} core adopts a paddlewheel motif, whereas in , the transition metal is pentacoordinated, and the central core contains only two acetate bridges. Going from to , the central {Y(acO)} core is replaced by an axially compressed octahedral cobalt(II) center, whereas the outer parts of the molecule remain still. The magnetic studies revealed that the alternate π-stacking of the verdazyl radicals in led to the formation of alternate antiferromagnetically coupled 1D chains with = -8.2(1) cm and ' = -7.6(1) cm (-2 convention). In , a complex fitting procedure allowed us to retrieve a complete set of magnetic parameters to take into account both the magnetic anisotropy of the cobalt(II) centers and intra- and inter-molecular exchange effects. For , it led to = 2.13(4), = 100(2) cm, = 19.9(5) cm, = +26.5(4) cm, and = -7.95(4) cm. magnetic susceptibility of , and did not reveal any slow relaxation of the magnetization even when a external magnetic field up to 2000 Oe was applied.