An Uneven Chain-like Ferromagnetic Copper(II) Coordination Polymer Displaying Metamagnetic Behavior and Long-Range Magnetic Ordering

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu3(L)2(N3)4(H2O)3)n (1, HL = 6-hydroxynicotinic acid). It is the first example of one-dimensional (1D) chain-like copper(II) coordination polymer showing both metamagnetic behavior and long-range magnetic ordering (Tc = 6.7 K), thanks to the interchain hydrogen bonds, which make a three-dimensional (3D) supramolecular array of the entire molecular structure and mediate the interchain antiferromagnetic interaction.

Copper(II) Carboxylates with 2,3,4-Trimethoxybenzoate and 2,4,6-Trimethoxybenzoate: Dinuclear Cu(II) Cluster and µ-Aqua-Bridged Cu(II) Chain Molecule

Copper(II) complexes with 2,3,4-trimethoxybenzoic acid (H234-tmbz) and 2,4,6-trimethoxybenzoic acid (H246-tmbz), [Cu2(234-tmbz)4(H2O)2] (6) and [Cu(246-tmbz)2(µ-H2O)2(H2O)2]n (7), were synthesized and characterized by elemental analysis, infrared and UV-vis spectra and temperature dependence of magnetic susceptibilities (1.9–300 K). The X-ray crystal structures revealed that the former 6 is a dinuclear cluster having syn-syn-bridged Cu2(µ-234-tmbz)4 core with Cu···Cu separation of 2.6009(7) Å, while the latter 7 is a µ-aqua-bridged chain molecule consisting of Cu(246-tmb)2(µ-H2O)2(H2O)2 units with Cu···Cu separation of 4.1420(5) Å. Temperature dependence of magnetic susceptibilities showed that an antiferromagnetic interaction with 2J = −272 cm−1 for 6 and a weak antiferromagnetic interaction with J = −0.21 cm−1 for 7, between the two copper(II) ions. The adsorption isotherm of 6 showed Types I behavior having a 125.4 m2g−1 of specific surface area.

Фазовая диаграмма модели Поттса с числом состояний спина q=4 на гексагональной решетке

We have carried out Monte Carlo investigations of the phase transitions, thermodynamic properties and ground-state magnetic structures in two-dimensional 4-state Potts model on a hexagonal lattice with the competing exchange interactions. Researches are carried out for the value of interaction of next-nearest neighbor in the range of 0.0≤r≤1.0. Taking into account of antiferromagnetic interaction of next-nearest neighbor is shown to lead to the violation of the magnetic ordering. The phase diagram of dependence of critical temperature on the value of interaction of next-nearest neighbor is plotted. Of the orders of phase transitions has been carried out. It is established that the phase transition of the first order is observed in the ranges of 0.0≤r≤0.2 and 0.7≤r≤1.0. In the range of 0.3≤r≤0.6 frustration are observed.

Paramagnetic One-dimensional Chain Containing High-spin Manganese Atoms Showing Antiferromagnetic Interaction Through –Pt–Rh–Rh–Pt– Bonds

To exploit the magnetic interactions of multiple metals, heterometallic one-dimensional (1D) chain containing three kinds of metals, Rh, Pt, and Mn, where [Rh2(O2CCH3)4] and [Pt2Mn(piam)4(NH3)4]2+ (piam = pivalamidate) are connected...

From Zero- to Three-Dimensional Heterobimetallic Coordination Polymers with the [Pt{SSC-N(CH2COO)2}2]4– Metalloligand

<br>Heterobimetallic compounds of the type M’2[Pt(L)2] (L = N-dithioato-iminodiacetate, {SSC-N(CH2COO)2}3–) containing different bivalent, oxophilic metals M’ were prepared in a straightforward manner from [Pt(H2L)2] and the respective metal acetates, M’(OAc)2 (M’ = Mg–Ba, M–Cu, Cd). X-ray structure determination revealed that the products exist as zero- (Mg), one- (Mn), two- (Fe, Co, Ni, Cd), or three-dimensional (Sr) assemblies in the solid state. As a result, the water solubilities and thermal stabilities of the products cover much wider ranges than it has been seen with M’2[M(L)2] compounds having different thiophilic metal centers (M = Ni, Pd, Pt). While most of the compounds show a typical diamagnetic (Mg–Ba, Cd) or paramagnetic (Mn, Co, Ni, Cu) behaviour at ambient temperature, for Fe2[Pt(L)2] ·4 H2O an antiferromagnetic interaction of the Fe atoms is assumed. <br>

From Zero- to Three-Dimensional Heterobimetallic Coordination Polymers with the [Pt{SSC-N(CH2COO)2}2]4– Metalloligand

<br>Heterobimetallic compounds of the type M’2[Pt(L)2] (L = N-dithioato-iminodiacetate, {SSC-N(CH2COO)2}3–) containing different bivalent, oxophilic metals M’ were prepared in a straightforward manner from [Pt(H2L)2] and the respective metal acetates, M’(OAc)2 (M’ = Mg–Ba, M–Cu, Cd). X-ray structure determination revealed that the products exist as zero- (Mg), one- (Mn), two- (Fe, Co, Ni, Cd), or three-dimensional (Sr) assemblies in the solid state. As a result, the water solubilities and thermal stabilities of the products cover much wider ranges than it has been seen with M’2[M(L)2] compounds having different thiophilic metal centers (M = Ni, Pd, Pt). While most of the compounds show a typical diamagnetic (Mg–Ba, Cd) or paramagnetic (Mn, Co, Ni, Cu) behaviour at ambient temperature, for Fe2[Pt(L)2] ·4 H2O an antiferromagnetic interaction of the Fe atoms is assumed. <br>

(Pyrrole-2,5-Diyl)-Bis(Nitronyl Nitroxide) and-Bis(Iminonitroxide): Specific Features of the Synthesis, Structure, and Magnetic Properties

In contrast to diradicals connected by alternant hydrocarbons, only a few studies have addressed diradicals connected by nonalternant hydrocarbons and their heteroatom derivatives. Here, the synthesis, structure, and magnetic properties of pyrrole-2,5-diyl–linked bis(nitronyl nitroxide) and bis(iminonitroxide) diradicals are described. The diradicals show characteristic electron spin resonance spectra in dilute glassy solutions, from which conclusions about the presence of distinct conformations, their symmetry, and interspin distance were made. X-ray diffraction analysis of the diradicals revealed that paramagnetic moieties lie in the plane of the pyrrole ring, because of the formation of an intramolecular hydrogen bond, ONO…H−N, with O…H distances of 2.15–2.23 Å. The N–O groups participating in the formation of H-bonds have greater bond lengths (~1.29 Å) as compared with nonparticipating groups (~1.27 Å). The nitronyl nitroxide and iminonitroxide diradicals showed an intramolecular antiferromagnetic interaction, with J = −77.3 and −22.2 cm−1, respectively (H = −2JS1⋅S2).