Syntheses, Structures, and Magnetic Properties of Unusual Nonlinear Polynuclear Copper(II) Complexes Containing Derivatives of 1,2,4-Triazole and Pivalate Ligands

Orthogonal magnetic orbitals in high spin Cu-VO units: structure, magnetism and EPR study of anisotropic heterometallic complexes

Molecular-based magnetic materials are expected to serve as building blocks for quantum bits. To realize high-dimensional Hilbert space and addressability, we constructed anisotropic multi-level systems based on CuII and VIV with orthogonal magnetic orbitals. The crystal structures and intramolecular magnetic couplings of four CuIIVOII complexes [{CuVO(appen)2}2], [{CuVO(fhma)2EDA}2], [{CuVO(hfca)2EDA}2] and [CuVO(hfca)2DPEDA]n are characterized. Due to the orthogonal magnetic orbitals of CuII and VIV, the Cu-V pairs in the four complexes have strong ferromagnetic couplings, and the coupling strength is linearly related to the dihedral angle between the two equatorial planes of the two coordination polyhedra. Because of the triplet ground state, the system can be described by an effective Hamiltonian model consisting of two S = 1 spins coupled together. The anisotropy parameters of [{CuVO(hfca)2EDA}2] and [CuVO(hfca)2DPEDA]n were obtained by the simulation of X-band continuous wave electron paramagnetic resonance (cw-EPR) spectra, confirming that both complexes have zero-field splitting addressable on the relative energy scale. The results indicate that constructing multi-centre complexes based on orthogonal magnetic orbitals is a promising strategy for designing multidimensional quantum bits.

Single and Double-Stranded 1D-Coordination Polymers with 4'-(4-Alkyloxyphenyl)-3,2':6',3"-terpyridines and {Cu2(μ-OAc)4} or {Cu4(μ3-OH)2(μ-OAc)2(μ3-OAc)2(AcO-κO)2} Motifs

Five coordination polymers formed from combinations of copper(II) acetate and 4'-(4-alkyloxyphenyl)-3,2':6',3''-terpyridines with methoxy (1), n-butoxy (2), n-pentyloxy (3) and n-heptyloxy (4) substituents are reported. Reaction of 1 with Cu(OAc)2∙H2O leads to the 1D-polymer [Cu2(μ-OAc)4(1)]n in which {Cu2(-OAc)4} paddle-wheel units are connected by ligands 1, or [{Cu4(μ3-OH)2(μ-OAc)2(μ3-OAc)2(AcO-κO)2(1)2}.2MeOH]n in which centrosymmetric tetranuclear clusters link pairs of ligands 1 to give a double-stranded 1D-polymer. Layering solutions of Cu(OAc)2∙H2O (in MeOH) over 2, 3 or 4 (in CHCl3) leads to the assembly of the 1D-polymers [2{Cu2(μ-OAc)4(2)}.1.25MeOH]n, [Cu2(μ-OAc)4(3)]n and [{Cu2(μ-OAc)4(4)}.0.2CHCl3]n. In all compounds, the 3,2':6',3''-tpy unit coordinates only through the outer pyridine rings, but the conformation of the 3,2':6',3''-tpy responds to changes in the length of the alkyloxy tails leading to changes in the conformation of the polymer backbone and in the packing of the chains in the crystal lattice in the chains featuring {Cu2(-OAc)4} paddle-wheel linkers.

Charge-assisted hydrogen bond and nitrile⋯nitrile interaction directed supramolecular associations in Cu(ii) and Mn(ii) coordination complexes: anticancer, hematotoxicity and theoretical studies

Charge-assisted H-bonds and nitrile⋯nitrile interactions directed assemblies in Cu(ii) and Mn(ii) complexes have been analyzed by MEP surface and NCI plot index. Anticancer activities and hematotoxictiy have been investigated.

A macrocyclic silver polycarbene complex based on 1,2,4-triazole units: synthesis and postsynthetic modification

A method for the synthesis of a new rectangular 1,2,4-triazole-containing macrocycle via photochemical [2 + 2] cycloaddition with a metal–carbene template was developed.

A series of Cd(ii) coordination polymers based on flexible bis(triazole) and multicarboxylate ligands: topological diversity, entanglement and properties

Eight Cd(ii) coordination polymers with diverse topologies based on 1,4-bis(1,2,4-triazol-4-ylmethyl)benzene and multicarboxylate ligands were synthesized and characterized. The 3D topologies of 1, 2 and 3 are unprecedented.

Controllable assembly of Cu(ii) coordination compounds based on a flexible zwitterionic benzimidazole–dicarboxylate ligand: synthesis, structural diversity, reversible SCSC transformation and magnetic properties

The reversible SCSC transformation of a paddle-wheel cluster to a 1D linear polymer could be accomplished.

A new strategy to obtain tetranuclear cobalt(ii) metal–organic frameworks based on the [Co4(μ3-OH)2] cluster: synthesis, structures and properties

Three MOFs based on [Co₄(μ₃-OH)₂] with 4-, 6- and 8-connected frameworks exhibit antiferromagnetic interactions and are good photocatalysts.

Four linear Cu(II)3 subunit-based coordination polymers with various inter-subunit connections, spin ground-states and intra-/inter-subunit magnetic couplings

Four new 4-amino-1,2,4-triazole (atr)-based coordination polymers, {[Cu2(atr)(H2O)(μ-OH)2(pa)]·H2O}n (), {[Cu3(atr)2(H2O)2(μ-OH)2(npa)2]·2H2O}n (), {[Cu3(atr)5(dca)(μ-OH)(ClO4)2](ClO4)2}n () and {[Cu3(atr)2(H2O)(μ3-OH)(μ-OH)2(spa)]·1.5H2O}n () (pa(2-) = phthalate, npa(2-) = 3-nitrophthalate, dca(-) = dicyanamide and spa(3-) = 4-sulfophthalate), were successfully obtained by varying the carboxylate- and cyanide-modified magnetic bridges. Structural determinations reveal that the former three samples are bent one-dimensional chains constructed from linear Cu(II)3 subunits and different inter-subunit connections. In , linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+) and {Cu3(μ-COO)2(μ-OH)2}(4+) subunits are alternately connected in a sharing-vertex manner to give a ferrimagnetic S = 1/2 spin ground-state. The linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+) building block of is repeatedly bridged by pairs of single-atom bridging carboxylate groups of the npa(2-) ligand leading to a paramagnetic S = 1/2 spin ground-state. By contrast, each linear {Cu3(μ-N1,N2-atr)4}(6+) core in is periodically propagated by four-fold heterobridges (μ-OH(-), μ-ClO4(-), μ-N1,N2-atr and μ-dca(-)) to generate an overall diamagnetic S = 0 spin ground-state. Complex is a three-dimensional pillared-layer framework composed of linear {Cu3(μ-N1,N2-atr)2(μ-OH)2}(4+)-based layers and ditopic spa(3-) connectors, which exhibits a ferrimagnetic S = 1/2 spin ground-state and a metamagnetic transition resulting from the competition between the weak interchain/interlayer antiferromagnetic interaction and the enhanced external magnetic field. In addition, different intra- and inter-subunit magnetic strengths are observed in with the coupling constants 182 < -Jintra < 43 and -127 < Jinter < 51.2 cm(-1). These interesting magnetostructural results are significant and helpful for the cyclic polyazolate-based magnetic materials.

Hydrothermal synthesis, structure and magnetic properties of a three-dimensional cobalt(ii) – aminophenyltetrazolate coordination polymer

The three-dimensional [Co₃(OH)₂(H₂O)₂(aptet)₄] exhibits magnetic properties consistent with a ferrimagnetic chain with the non-compensating resultant moment of one Co(ii) per trinuclear Co(ii) subunit and ac magnetic susceptibility indicative of glassy-like magnetic behavior.

New mononuclear Cu(II) complexes and 1D chains with 4-amino-4H-1,2,4-triazole

The crystal structures of two mononuclear Cu(II) NH₂trz complexes [Cu(NH₂trz)₄(H₂O)](AsF₆)₂ (I) and [Cu(NH₂trz)₄(H₂O)](PF₆)₂ (II) as well as two coordination polymers [Cu(μ₂-NH₂trz)₂Cl]Cl·H₂O (III) and [Cu(μ₂-NH₂trz)₂Cl] (SiF₆)_0.5·1.5H₂O (IV) are presented. Cationic 1D chains with bridging bis-monodentate μ₂-coordinated NH₂trz and bridging μ₂-coordinated chloride ligands are present in III and IV. In these coordination polymers, the Cu(II) ions are strongly antiferromagnetically coupled with J = −128.4 cm⁻¹ for III and J = −143 cm⁻¹ for IV (H = −J∑S_iS_i+1), due to the nature of the bridges between spin centers. Inter-chain interactions present in the crystal structures were taken into consideration, as well as g factors, which were determined experimentally, for the quantitative modeling of their magnetic properties.