Layered manganese 4-phosphonoisophthalates (4-piH4) embedding Mn-O chains with metamagnetism in Mn3(4-piH)2(H2O)3·H2O

Two manganese phosphonates Mn 3 (4-piH) 2 (H 2 O) 3 ·H 2 O ( 1 ) and Mn 5 (4-piH) 2 (4-piH 2 ) 2 (phen) 2 (H 2 O) 4 ( 2 ) (4-piH 4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions in the presence of organic co-ligand. Both compounds exhibit layer structures but with different topologies. In compound 1 , a complicated “ladder-like” chain of {Mn 3 O 3 }O 2 which contains three- and six-member rings made up of triangular shaped {Mn 3 O 3 } trimers is found. The chains are linked by the PO 3 C 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 {Mn 4 O 6 } are connected by the {MnO 6 } octahedra through corner-sharing to form an infinite chain, which is further bridged by 4-piH 3 − ligands into a thick hybrid layer. Magnetic measurements reveal that antiferromagnetic interactions are dominant in both compounds. Metamagnetism is observed in compound 1 at low temperature, while no long range ordering is found in compound 2 down to 1.8 K.