Synthesis, crystal structure and magnetic properties of mer-tricyanidoiron(III) precursor-based 1D heterobimetallic complexes

Three new cyanide-bridged heterometallic complexes {{[Cu(S,S-Chxn)2][Fe(bbp)(CN)3]}2·2 H2O} n (1), {{[Cu(R,R-Chxn)2][Fe(bbp)(CN)3]}2·2 H2O} n (2) and {{[Cu(Cycam)][Fe(bbp)(CN)3]}·CH3OH·2 H2O} n (3) (bbp = bis(2-benzimidazolyl)pyridine dianion, Chxn = 1,2-diaminocyclo hexane, cyclam = 1,4,8,11-tetraazacyclodecane) have been assembled from the rarely used mer-tricyanidoiron(III) building block [PPh4]2[Fe(bbp)(CN)3] and three copper(II) compounds. The complexes have been characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. For the chiral enantiomers 1 and 2, the circular dichroism (CD) spectrum was also investigated. X-ray structural analyses revealed that the structures of the cyanide-bridged Fe-Cu complexes 1 and 2 are characterized by two crystallographically independent but structurally very similar homochiral neutral chains, each consisting of the repeating units {[Cu(S,S-Chxn)2][Fe(bbp)(CN)3]} (1) or {[Cu(R,R-Chxn)2][Fe(bbp)(CN)3]} (2). The crystal structure of 3 likewise is build up of chains consisting of {[Cu(Cyclam)][Fe(bbp)(CN)3]} building blocks. The temperature-dependent magnetic susceptibility and field dependent magnetization of the complexes showed antiferromagnetic interactions in complex 1 between the Fe(III) and Cu(II) ions, while complex 3 is ferromagnetic, indicating that the magnetic coupling through cyanide linkage is very sensitive to the structure parameters around the paramagnetic metal ions. These results have been further confirmed by fitting of the experimental data using a uniform chain model, leading to the coupling constants J = −6.35 cm−1, g = 2.08, R = 4.42 × 10−4 and J = 1.24 cm−1, g = 2.09, R = ∑(χ obsd T − χ cald T)2/∑(χ obsd T)2 = 4.67 × 10−4 for complexes 1 and 3, respectively.

Tunable Assembly and Magnetic Interactions in Two Cyano-bridged FeIII–CoII Bimetallic Complexes

Abstract

Using a new semi-rigid tetradentate ligand and two cyanometalate building blocks with different steric hindrance, a Fe2Co triangular unit [(Tp)FeIII(CN)3]2CoII(bpmb)·2H2O [1; Tp = hydrotris(pyrazolyl)borate; bpmb = 1,2-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzenes] and a Fe2Co2 square unit {[(pzTp)FeIII(CN)3]2[CoII(bpmb)]2}·[(pzTp)FeIII(CN)3]2·4H2O [2; pzTp = tetrakis(pyrazolyl)borate] were synthesized via tunable assembly. Both compounds adopt cis arrangement because of the structural distorted semi-rigid bpmb. Tetranuclear square of 2 was formed due to larger steric hindrance building block of [(pzTp)FeIII(CN)3]− compared with [(Tp)FeIII(CN)3]− in trinculear 1. Magnetic measurements show that antiferromagnetic interactions dominate in 1 and 2. The fitting results of J values suggest a positive correlation between magnetic orbitals overlap of FeIII and CoII ions and Co–N≡C bond angles.

Graphical Abstract

Two cis arrangement cyanometalate [Fe-Co] clusters were synthesized via tunable assembly with a new semi-rigid tetradentate ligand. The tetranuclear cluster was formed because of larger steric hindrance of pzTp. Both compounds exhibit dominant antiferromagnetic couplings. The fitting results of J values suggest a positive correlation between magnetic orbitals overlap of FeIII and CoII ions and Co–N≡C bond angles.

Heterobimetallic complexes from 0D clusters to 3D networks based on various polycyanometallates and [Cu(dmpn)2]2+ (dmpn = 2,2-dimethyl-1,3-diaminopropane): synthesis, crystal structures and magnetic properties

Six new cyanide-bridged complexes (0–3D) have been assembled by employing one copper compound and six cyano precursors. Investigation of the magnetic properties revealed the ferro- or antiferromagnetic coupling between Fe^III/Cr^I ion and Cu^II ion.

Iron molybdenum nitrilotriacetate and iminodiacetate – spectroscopy, structural characterization and CO2 adsorption

The tetranuclear iron molybdate Na₆[(MoO₂)₂O₂Fe₂(nta)₄]·16H₂O (1) and its isomorphous complexes form 2D water layer structures in a modular manner, and a decanuclear heterometallic polymer, [(MoO₄)₂FeII4FeIII4(ida)₈]_n (2), contains an interesting cubic 3D microporous structure with a 3.3 Å diameter hole and can adsorb a small amount of CO₂.

Synthesis and characterization of a macrocyclic copper complex containing the 14-membered 1,3,5,8,10,12-hexaazacyclotetradecane unit

In this work, a new macrocyclic copper complex, [Cu(ACE)(SCN)2]; ACE: 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane, was prepared and characterized by elemental analysis, FT-IR, Raman spectroscopy and single-crystal X-ray diffraction. X-ray analysis of [Cu(ACE)(SCN)2] reveals an elongated octahedral geometry around the copper atom in a centrosymmetric CuN6 environment.

Synthesis, crystal structures and magnetic properties of mer-cyanideiron(iii)-based 1D heterobimetallic cyanide-bridged chiral coordination polymers

Two pairs of 1D cyanide-bridged heterometallic chiral enantiomer complexes have been synthesized, structurally characterized and magnetically investigated.

Hydrogen bonding-based 3D supramolecular architecture of [Cu(CHA)2][TCM]·11H2O

Reaction of Na4TCM (1) (H4TCM = tetra[4-(carboxyphenyl)oxamethyl]methane) with [Cu(CHA)](ClO4)2 (2)(CHA = 1,3,6,8,11,14-hexaaz atricyclo[12.2.1.1.8,11] octadecane) in a DMF-water mixture yields [Cu(CHA)]2[TCM] (3). Structural analysis of [Cu(CHA)]2[TCM]·11H2O (3·11H2O) by single crystal X-ray diffraction reveals strong copper-oxygen bonds between two complex cations and the tetraanion leading to a 3D coordination network (zwitterionic structure), consolidated through additional NH...O=C hydrogen bonding within the cation/anion association. The resulting coordination geometry around a copper atom is a distorted square pyramidal with an oxygen atom of the anionic ligand in the apical position. A 3D supramolecular network is developed in the crystal based only on NH...OC hydrogen bonds between the macrocyclic metallic tecton and the carboxylate groups of neighboring 3D coordinated (zwitterionic) moieties. The pseudotetrahedral TCM4− tetraanionic ligand induces a diamondoid architecture formed of large distorted adamantanoid cages.

Heterobimetallic metal-complex assemblies constructed from the flexible arm-like ligand 1,1'-bis[(3-pyridylamino)carbonyl]ferrocene: structural versatility in the solid state

The bidentate ferrocenyl sandwich molecule 1,1'-bis[(3-pyridylamino)carbonyl]ferrocene (3-BPFA) has been employed as an organometallic ligand in reactions with a series of transition metal salts to construct heterobimetallic architectures. X-ray crystallographic characterization reveals that the crystal packing of free ligand 3-BPFA induces spontaneous resolution of helical chains via intermolecular hydrogen bonds. By combining the flexibility from the arm-like molecule (3-BPFA) with the variation of the coordination property from different metal ions and/or the different counteranions, five different types of architectures are prepared: one octahedral coordination cage (copper(II) complex 1); two discrete pseudocapsules for combination of chlorine anions (nickel(II) complex 2 and cobalt(II) complex 3); two dimers with metal-metal interactions (silver(I) complexes 4 and 5); one macrocyclic complex (mercury(II) complex 6); and five two-dimensional mixed-metal-organic frameworks (M'-MOFs) (zinc(II), cadmium(II), and mercury(II) complexes 7-11). The structures of all complexes are characterized in detail by IR, elementary analysis, and single-crystal X-ray diffraction analysis. The factors inducing the structure variation among the complexes are discussed by taking account of the coordination geometry of different metal ions, the span angle between the two "arms", and the coordination mode of the 3-BPFA ligand.

Azido-(methanol)[N,N'-(o-phenyl-ene)bis-(pyridine-2-carboxamidato)]manganese(III)

In the title complex, [Mn(C₁₈H₁₂N₄O₂)(N₃)(CH₄O)], the Mn^III ion is in a distorted octa­hedral coordination environment. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds connect mol­ecules into centrosymmetric dimers.

Robust and efficient molecular catalysts with a M–O–M′ framework

Heterodimetallic systems are the most interesting among the heteropolynuclear compounds. The importance of these molecules is mainly due to their catalytic properties. Although various types of heterodimetallic systems are known the framework with a M-O-M' arrangement is of particular importance. This stems from its ability to catalyze various transformations. The improved catalytic ability is due to the oxygen bridge that makes the metal centres more electrophilic which is an essential criteria for a system to function as a catalyst. Therefore, the present article focuses on the synthesis of the M-O-M' system and explores the application of such materials as catalysts in olefin polymerization, ring opening polymerization of caprolactone, olefin epoxidation, and olefin hydroformylation reactions.