Pentagonal Bipyramidal 3 d‐Metal Complexes Derived from a Dimethylcarbamoyl‐Substituted Pentadentate‐[N 3 O 2 ] Ligand: Aiming for Increased Solubility

International audienceA pentadentate-[N3O2] ligand, H2LNMe2, formed by condensation of diacetyl pyridine and dimethylcarbamoyl hydrazide (i. e. Me2NCONHNH2), is reported to yield mononuclear pentagonal bipyramidal (PBP) metal complexes with CrIII, MnII, FeII, CoII, and NiII, that exhibit good solubility in a wide range of solvents as compared to the classically used H2LR ligands. With CuII, dinuclear complexes were obtained. The potassium salt of the deprotonated ligand, K2LNMe2, was also characterized. The reported complexes consist of [CrH2LNMe2Cl2] ⋅ Cl; Cat[CrLNMe2(CN)2] (Cat=K+ or PNP+); [MH2LNMe2(H2O)2] ⋅ (ClO4)2 with M=MnII, CoII, or NiII; [FeH2LNMe2(MeCN)2] ⋅ (PF6)2 ⋅ MeCN; [FeH2LNMe2(MeOH)X] ⋅ X (X=Br or I); [{CuH2LNMe2}2(MeOH)(ClO4)] ⋅ (ClO4)3 ⋅ 1H2O⋅1.75H2O; [CuHLNMe2]2 ⋅ (ClO4)2 ⋅ H2O; and [CuH2LNMe2(H2O)]2 ⋅ (ClO4)4 ⋅ 5H2O. The magnetic behaviors of the PBP derivatives were assessed, especially the zero-field splitting (ZFS) characteristics for the CrIII, FeII, CoII, and NiII derivatives. The ZFS characteristics were also determined from ab initio theoretical calculations. The obtained values confirm those extracted from magnetic measurements