Two manganese phosphonates Mn3（4-piH）2（H2O）3·H2O （1） and Mns（4-piH）2（4-piH2）2（phen）2（H2O）4 （2） （4-pill4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline） have been synthesized under hydrothermal conditions in the pres- ence of organic co-ligand. Both compounds exhibit layer structures but with different topologies. In compound 1, a complicated ＂ladder-like＂ chain of {Mn3O3}O2 which contains three- and six-member rings made up of triangular shaped {Mn3O3} tri- mers is found. The chains are linked by the PO3C groups to form an inorganic layer. The phenyl and protonated carboxylate groups are pendent between the layers with extensive hydrogen bonds. In compound 2, tetramers of {MnnO6 } are connected by the { MnO6 } octahedra through corner-sharing to form an infinite chain, which is further bridged by 4-pill3- ligands into a thick hybrid layer. Magnetic measurements reveal that antiferromagnetic interactions are dominant in both compounds. Metamag- netism is observed in compound 1 at low temperature, while no long range ordering is found in compound 2 down to 1.8 K.
JIN HaoJunWANG PengFeiBAO SongSongZHENG LiMinYAO Cheng
The reactions of 6-phosphononicotinic acid (pnaH3) and metal salts result in three new compounds, namely, M(pnaH)-(H2O)3·H2O [M = Co(Ⅱ) (1), Ni(Ⅱ) (2), Zn(Ⅱ) (3)]. These compounds are isostructural and contain 21 helical chains made up of corner-sharing {MO5N} octahedra and {PO3C} tetrahedra. The chains are further connected by extensive hydrogen bonds to form a three-dimensional supramolecular structure. Magnetic studies reveal that dominant antiferromagnetic interactions are mediated in both 1 and 2. Interestingly the dehydrated compound 1 shows metamagnetic behavior at low temperature.
WANG PengFei, DUAN Yan & ZHENG LiMin State Key Laboratory of Coordination Chemistry
