Magnetic Bistability and Single-Crystal-to-Single-Crystal Transformation Induced by Guest Desorption

An iron(II) complex with ferrocenyl groups, [Fe(dppFc)2](BF4)2·2Et2O (1·2Et2O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1·2Et2O underwent a single-crystal-to-single-crystal transformation with the release of crystal solvent molecules. In magnetic susceptibility measurements, a reversible conversion between paramagnetism and spin-crossover induced by solvent molecules was observed

A Ferromagnetic Interaction between Cu²⁺ Centers through a [CrO₄]^2- Bridge: Crystal Structures and Magnetic Properties of [{Cu(acpa)}₂(μ-MO₄)] (M = Cr, Mo) (Hacpa = <i>N</i>-(1-Acetyl-2-propyridene)(2-pyridylmethyl)amine)

The reaction of [Cu(acpa)]+ with [MO4]2- (Hacpa = N-(1-acetyl-2-propyridene)(2-pyridylmethyl)amine and M = Cr and Mo) in water−methanol or water−acetonitrile solution affords dinuclear copper(II) complexes with metalate bridges, [{Cu(acpa)}2(μ-CrO4)]·4CH3OH·4H2O (1) and [{Cu(acpa)}2(μ-MoO4)]·4H2O (2), respectively. The crystal structures and the magnetic properties have been studied. Complexes 1 and 2 are isomorphous and the structures are made up of discrete dimers in which two copper(II) ions are bridged by the [MO4]2- anion. The coordination geometry about the copper(II) ions is square planar with a N2O chelate group from acpa and an oxygen atom from [MO4]2-. Magnetic susceptibility measurements for 1 revealed that a ferromagnetic interaction between copper(II) ions is propagated through the [CrO4]2- bridge and the coupling constant (2J) was evaluated to be 14.6(1) cm-1 (H = −2JS1·S2). In 2, two copper(II) ions bridged by [MoO4]2- anion are antiferromagnetically coupled with the 2J value of −5.1(4) cm-1. The ferromagnetic interaction in 1 is explained by means of the orbital topology of frontier orbitals. Crystal data:  1, monoclinic, space group P21/m, a = 8.349(2) Å, b = 17.616(3) Å, c = 10.473 Å, β = 107.40(2)°, Z = 2; 2, monoclinic, space group P21/m, a = 8.486(2) Å, b = 18.043(3) Å, c = 9.753(2) Å, β = 95.82(2)°, Z = 2

Superparamagnetic Behavior in an Alkoxo-Bridged Iron(II) Cube

Superparamagnetic Behavior in an Alkoxo-Bridged Iron(II) Cub

Superparamagnetic Behavior in an Alkoxo-Bridged Iron(II) Cube

Superparamagnetic Behavior in an Alkoxo-Bridged Iron(II) Cub

Cyanide-Bridged Molecular Squares with Ferromagnetically Coupled dπ, dσ, and pπ Spin System

Cyanide-bridged molecular squares of [FeII2CuII2(μ-CN)4(dmbpy)4(impy)2](ClO4)4·4CH3OH·C6H6 (1) and of [FeIII2CuII2(μ-CN)4(dmbpy)4(impy)2](ClO4)6·4CH3OH·4H2O (2) (dmbpy = 4,4‘-dimethyl-2,2‘-bipyridine; impy = 2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy) were prepared. In the squares of 1 and 2, the Fe(II/III) (low spin) and Cu(II) ions are alternately bridged by the cyanide groups, in which the cyanide carbon atoms coordinated to the Fe(II) ions and Cu(II) ions are coordinated by imino nitroxide. Magnetic susceptibility measurements for 1 and 2 revealed that the Cu(II) ion and imino nitroxide are ferromagnetically coupled with a fairly strong coupling constant (JCu-radical > 300 K) and act as triplet species. In 1 the Cu(II)−radical moieties are magnetically separated by the Fe(II) ions. In the square of 2, dπ (Fe(III)), dσ (Cu(II)), and pπ (imino nitroxide) spins are alternately assembled, and this situation allowed the square to have an S = 3 spin ground state. The exchange coupling constant of Fe(III) and the Cu(II)−radical moiety in 2 was estimated to be J = 4.9 cm-1 (H = −2J∑SFe·SCu-radical)

Magnetic Bistability and Single-Crystal-to-Single-Crystal Transformation Induced by Guest Desorption

An iron(II) complex with ferrocenyl groups, [Fe(dppFc)2](BF4)2·2Et2O (1·2Et2O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1·2Et2O underwent a single-crystal-to-single-crystal transformation with the release of crystal solvent molecules. In magnetic susceptibility measurements, a reversible conversion between paramagnetism and spin-crossover induced by solvent molecules was observed

Magnetic Bistability and Single-Crystal-to-Single-Crystal Transformation Induced by Guest Desorption

An iron(II) complex with ferrocenyl groups, [Fe(dppFc)2](BF4)2·2Et2O (1·2Et2O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1·2Et2O underwent a single-crystal-to-single-crystal transformation with the release of crystal solvent molecules. In magnetic susceptibility measurements, a reversible conversion between paramagnetism and spin-crossover induced by solvent molecules was observed

Magnetic Bistability and Single-Crystal-to-Single-Crystal Transformation Induced by Guest Desorption

An iron(II) complex with ferrocenyl groups, [Fe(dppFc)2](BF4)2·2Et2O (1·2Et2O, dppFc = 1-ferrocenyl-2-{(2,6-bis(pyrazolyl)pyridyl}ethylene), was prepared. X-ray crystallographic analyses revealed that 1·2Et2O underwent a single-crystal-to-single-crystal transformation with the release of crystal solvent molecules. In magnetic susceptibility measurements, a reversible conversion between paramagnetism and spin-crossover induced by solvent molecules was observed

Radical Double Helicates of Silver Imino Nitroxides, [Ag₂(pyrd-im2)₂](PF₆)₂·2CH₃OH and [Ag₂(bpy-im2)₂](PF₆)₂·CH₃OH

Radical Double Helicates of Silver Imino Nitroxides, [Ag2(pyrd-im2)2](PF6)2·2CH3OH and [Ag2(bpy-im2)2](PF6)2·CH3O