Self-assembly of novel manganese (II) compounds based on bifunctional-group ligands: Synthesis, structures, and magnetic properties.

Four manganese (II) compounds are obtained by the reaction of manganese salts, triazole-derivatives and auxiliary reagents in aqueous solution or mix-solvents by routine or hydrothermal reactions. X-ray crystal structure analyses reveal that a neutral 0D compound [Mn(Hmctrz) 2 (H 2 O) 2 ] ( 1 ) (H 2 mctrz = 1 H -1,2,4-triazole-3-carboxylic acid) displays a centro-symmetric mononuclear octahedral entity with two Hmctrz − anions and two water molecules; two neutral 2D clusters [Mn(Hdctrz)(H 2 O) 2 ] n ( 2 ) (H 3 dctrz = 1 H -1,2,4-triazole-3,5-dicarboxylic acid) and [Mn 2 (pbtrz)(btca)] n ·4nH 2 O ( 3 ) (pbtrz = 1,3-bis(1,2,4-triazol-1-yl)-propane&H 4 btca = benzene-1,2,4,5-tetracarboxylic acid) possess layer structures with Hdctrz 2 − linkers ( 2 ) and Mn(II)-pbtrz-Mn(II) building blocks periodically extended by μ -btca 4 − connectors ( 3 ); [Mn(pbtrz)] n ·nOAc·nOH ( 4 ) shows a 3D diamond-shaped cationic framework with the anion void volume of 49.2%. Nitrogenous bases are used as the auxiliary ligand in compound 3 and the temple ligand in compounds 1 , 2 , and 4 . Compounds 1 – 4 show antiferromagnetic coupling that has been fitted by different models with the molecular field approximate with D = − 0.129(1) cm −1 for 1 , J = − 0.354(4) cm −1 for 2 and J = − 0.696(6) cm −1 for 3 , respectively. The magnetic differences can be related to different superexchange interactions transmitted by the crystal lattice and/or the zero field splitting (ZFS) of the 6 A 1g single-ion states of 1 and the syn-anti -COO − of 2 as well as the mixed magnetic bridges of μ 1 -O and μ -pbtrz- μ -COO − of 3 . [ABSTRACT FROM AUTHOR]