Chromous carbonates containing a square-grid layer of {Cr2(CO3)4}n4n- based on a dichromium(II,II) paddlewheel core

Polymeric coordination compounds based on Cr2n+ paddle-wheel building blocks with non-carboxylate O,O-donor ligands chelating and bridging the Cr-Cr centers have been underexplored hitherto. This paper reports the synthesis and crystal structure of a new homo-valent chromium(ii,ii) compound, Na3HCr2(CO3)4·10H2O (1). It has a two-dimensional structure in which the paddlewheel chromium(ii,ii) units of Cr2(CO3)44- are cross-linked through the carbonate groups. The layers are stacked along the [100] direction, and Na ions fill the intra and interlayer spaces with a neighboring layer distance of about 11.3 Å. The investigation of the primary magnetic properties and theoretical studies with density functional theory (DFT) reveal the partial paramagnetic properties of compound 1 arising from the Boltzmann distribution between a ground state σ2π4δ2 with S = 0 and a low-lying excited state σ2π4δδ* with S = 1 for the Cr2(ii,ii) dimer. According to Raman spectra measurements combined with theoretical calculations, the two Raman bands in the small-wavenumber region at 335 and 297 cm-1 were assigned to the vibration of the Cr-O bonds and the band at 371 cm-1 was assigned to the stretching of the Cr-Cr quadruple bond.

A spin-1/2 gapped compound CdCu2(SeO3)2Cl2 with a ladder structure

The exploration of two-leg spin-ladder materials is a great challenge to the chemical community since it is one of the most ideal models for the study of low-dimensional magnetism and high-Tc superconductivity. Herein, we report on a successful synthesis of a new Cu2+-based two-leg ladder compound constructed by CuO4Cl2 octahedra along the [101] direction. The magnetic results exhibit a broad peak at Tmax ∼ 265 K, and suggest that CdCu2(SeO3)2Cl2 has a spin singlet ground state. The fitting of the isolated two-leg spin-ladder model shows J⊥/kB = 429 K and J‖/kB = 21 K, leading to a large spin gap of ∼409 K.

Structure and properties of a novel staircase-like decanuclear [CuII10] cluster supported by carbonate and carboxylate bridges

A novel staircase-like decanuclear copper(ii) cluster composed of a pair of [CuII5] pentameric units that are linked together exclusively by two μ₂:η²:η¹carbonate ligands is reported. The cluster also shows a rare μ₃:η²:η¹:η¹bridging coordination mode of benzoate groups of the ligand.

Single-crystal-to-single-crystal (SCSC) transformation and dissolution–recrystallization structural transformation (DRST) among three new copper(ii) coordination polymers

Three new copper(ii) complexes with single-crystal-to-single-crystal (SCSC) transformation and dissolution–recrystallization structural transformation (DRST) have been synthesized and fully characterized.

Spin-singlet Quantum Ground State in Zigzag Spin Ladder Cu(CF3 COO)2

The copper salt of trifluoroacetic acid, Cu(CF₃ COO)₂ , offers a new platform to investigate the quantum ground states of low-dimensional magnets. In practice, it realizes the ideal case of a solid hosting essentially isolated magnetic monolayers. These entities are constituted by well-separated two-leg half-integer spin ladders organized in a zigzag fashion. The ladders are comprised of dimeric units of edge-sharing tetragonal pyramids coupled through carbon ions. The spin-gap state in this compound was revealed by static and dynamic magnetic measurements. No indications of long range magnetic ordering down to liquid helium temperature were obtained in specific heat measurements. First principles calculations allow estimation of the main exchange interaction parameters, J_⊥ =176 K and J_∥ =12 K, consistent with the weakly interacting dimers model.

Two S = 1/2 one-dimensional barium copper phosphates showing antiferromagnetic and ferromagnetic intrachain interactions

Two barium copper phosphates, BaCu2(PO4)2(H2O) (1) and Ba2Cu(HPO4)(PO4)(OH) (2), were synthesized under mild hydrothermal conditions. The Cu cation in 1 adopts a CuO4(H2O) square pyramidal coordination configuration, forming alternating chains along the b axis through alternative corner and edge sharing, while the geometry of the Cu center in 2 is a CuO4(OH)2 octahedron which further connects each other by edge sharing to constitute uniform chains along the b axis. Magnetic behaviors of both compounds were analyzed by susceptibility, magnetization and heat capacity measurements. The dominant intrachain couplings are antiferromagnetic in 1 with a long-range ordering at 14 K and ferromagnetic in 2 without long-range ordering above 2 K. The first principles calculations indicate that the intrachain ferromagnetic couplings in 2 originate from Cu(1)-O(7)H-Cu(1) dpσ correlation superexchanges. The susceptibility data of compounds 1 and 2 are fitted by using suitable antiferromagnetic chain and ferromagnetic chain models, respectively. In addition, we report the results of the infrared and thermal measurements of both the compounds.

Three Zn(ii)/Cd(ii)/Mn(ii) coordination polymers based on a 2-hydroxy-N-(1H-tetrazol-5-yl) benzamide ligand: structures, and magnetic and photoluminescence properties

Three transition metal complexes of the amide decorated tetrazolate are reported that include an interdigitated 3-D structure with 1-D channels.