Decoding the role of encapsulated ions in the electronic and magnetic properties of mixed-valence polyoxovanadate capsules {X@V22O54} (X = ClO4-, SCN-, VO2F2-): a combined theoretical approach

The electronic structure and magnetism of mixed-valence, host-guest polyoxovanadates {X@VO₅₄} with diamagnetic (X =) ClO₄^- (T_d, 1) and SCN^- (C_∞v, 2) template anions are assessed by means of two theoretical methods: density functional theory and effective Hamiltonian calculations. The results are compared to those obtained for another member of this family with X = VO₂F₂^- (C_2v, 3) (see P. Kozłowski et al., Phys. Chem. Chem. Phys., 2017, 19, 29767-29771), for which complementary data are also acquired. It is demonstrated that the X guest anions strongly influence the electronic and magnetic properties of the system, leading to various valence states of vanadium and modifying V-O-V exchange interactions. Our findings are concordant with and elucidate the available experimental data (see K. Y. Monakhov et al., Chem. - Eur. J., 2015, 21, 2387-2397).

Molecular design of a novel ligand for Menshutkin complexation of Bi(iii) from aqueous acidic copper sulfate electrolyte solutions and experimental investigations

A novel silica functionalised phen–arene adsorbent exhibits reversible and highly selective adsorption of Bi(iii) over Cu(ii) ions by Menshutkin complexation from an aqueous acidic copper electrolyte solution.

Carboxylate free μ-oxo bridged ferric wheel with a record exchange coupling

An oxo-bridged, carboxylate free ‘ferric wheel’ was isolated with the molecular formula [FeIII8(μ-O)₄(L²⁻)₈] (1). The strength of antiferromagnetic interaction between the Fe(iii) ions is revealed by magnetic simulation (J₁ = −26.4 and J₂ = −170 cm⁻¹). The exchange value of −170 cm⁻¹ is the largest exchange value known for any homometallic or heterometallic wheels reported to date.

A comparative synthetic, magnetic and theoretical study of functional M₄Cl₄ cubane-type Co(II) and Ni(II) complexes

We describe the synthesis, structures, and magnetochemistry of new M4Cl4 cubane-type cobalt(II) and nickel(II) complexes with the formula [M(μ3-Cl)Cl(HL·S)]4 (1: M = Co; 2: M = Ni), where HL·S represents a pyridyl-alcohol-type ligand with a thioether functional group, introduced to allow subsequent binding to Au surfaces. Dc and ac magnetic susceptibility data of 1 and 2 were modeled with a full spin Hamiltonian implemented in the computational framework CONDON 2.0. Although both coordination clusters 1 and 2 are isostructural, with each of their transition metal ions in a pseudo-octahedral coordination environment of four Cl atoms and N,O-donor atoms of one chelating HL·S ligand, the substantially different ligand field effects of Co(II) and Ni(II) results in stark differences in their magnetism. In contrast to compound 1 which exhibits a dominant antiferromagnetic intramolecular coupling (J = -0.14 cm(-1)), 2 is characterised by a ferromagnetic coupling (J = +10.6 cm(-1)) and is considered to be a single-molecule magnet (SMM), a feature of special interest for future surface deposition studies. An analysis based on density functional theory (DFT) was performed to explore possible magnetostructural correlations in these compounds. Using a two-J model Hamiltonian, it revealed that compound 1 has four positive and two (small) negative J(Co···Co) isotropic interactions leading to a S(HS) = 6 ground state. Taking into account the magnetic anisotropy, one would recover a M(S) = 0 ground state since D > 0 from computations. In 2, all the J constants are positive and, in this framework, the zero-field splitting energy characterising the axial anisotropy was estimated to be negative (D = -0.44 cm(-1)). The computational results are consistent with compound 2 being an SMM.