A cyanide-bridged FeIII–MnII heterobimetallic one-dimensional coordination polymer: synthesis, crystal structure, experimental and theoretical magnetism investigation

A new cyanide-bridged Fe III –Mn II heterobimetallic coordination polymer (CP), namely catena -poly[[[ N , N ′-(1,2-phenylene)bis(pyridine-2-carboxamidato)-κ 4 N , N ′, N ′′, N ′′′]iron(III)]-μ-cyanido-κ 2 C : N -[bis(4,4′-bipyridine-κ N )bis(methanol-κ O )manganese(II)]-μ-cyanido-κ 2 N : C ], {[FeMn(C 18 H 12 N 4 O 2 )(CN) 2 (C 10 H 8 N 2 ) 2 (CH 3 OH) 2 ]ClO 4 } n , ( 1 ), was prepared by the self-assembly of the trans -dicyanidoiron(III)-containing building block [Fe(bpb)(CN) 2 ] − [bpb 2− = N , N ′-(1,2-phenylene)bis(pyridine-2-carboxamidate)], [Mn(ClO 4 ) 2 ]·6H 2 O and 4,4′-bipyridine, and was structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis shows that CP 1 possesses a cationic linear chain structure consisting of alternating cyanide-bridged Fe–Mn units, with free perchlorate as the charge-balancing anion, which can be further extended into a two-dimensional supramolecular sheet structure via inter-chain π–π interactions between the 4,4′-bipyridine ligands. Within the chain, each Mn II ion is six-coordinated by an N 6 unit and is involved in a slightly distorted octahedral coordination geometry. Investigation of the magnetic properties of 1 reveals an antiferromagnetic coupling between the cyanide-bridged Fe III and Mn II ions. A best fit of the magnetic susceptibility based on the one-dimensional alternating chain model leads to the magnetic coupling constants J 1 = −1.35 and J 2 = −1.05 cm −1 , and the antiferromagnetic coupling was further confirmed by spin Hamiltonian-based density functional theoretical (DFT) calculations.