Syntheses, structures, and magnetic properties of low-dimensional heterometallic complexes based on the versatile building block [(Tp)Cr(CN)3]-

[CrIII8NiII6]n+ Heterometallic Coordination Cubes

Three new heterometallic [Cr^III₈Ni^II₆] coordination cubes of formulae [Cr^III₈Ni^II₆L₂₄(H₂O)₁₂](NO₃)₁₂ (1), [Cr^III₈Ni^II₆L₂₄(MeCN)₇(H₂O)₅](ClO₄)₁₂ (2), and [Cr^III₈Ni^II₆L₂₄Cl₁₂] (3) (where HL = 1-(4-pyridyl)butane-1,3-dione), were synthesised using the paramagnetic metalloligand [Cr^IIIL₃] and the corresponding Ni^II salt. The magnetic skeleton of each capsule describes a face-centred cube in which the eight Cr^III and six Ni^II ions occupy the eight vertices and six faces of the structure, respectively. Direct current magnetic susceptibility measurements on (1) reveal weak ferromagnetic interactions between the Cr^III and Ni^II ions, with J_Cr-Ni = + 0.045 cm^-1. EPR spectra are consistent with weak exchange, being dominated by the zero-field splitting of the Cr^III ions. Excluding wheel-like structures, examples of large heterometallic clusters containing both Cr^III and Ni^II ions are rather rare, and we demonstrate that the use of metalloligands with predictable bonding modes allows for a modular approach to building families of related polymetallic complexes. Compounds (1)-(3) join the previously published, structurally related family of [M^III₈M^II₆] cubes, where M^III = Cr, Fe and M^II = Cu, Co, Mn, Pd.

[MIII2MII3] n+ trigonal bipyramidal cages based on diamagnetic and paramagnetic metalloligands

A family of five [MIII2MII3] n+ trigonal bipyramidal cages (MIII = Fe, Cr and Al; MII = Co, Zn and Pd; n = 0 for 1-3 and n = 6 for 4-5) of formulae [Fe2Co3L6Cl6] (1), [Fe2Zn3L6Br6] (2), [Cr2Zn3L6Br6] (3), [Cr2Pd3L6(dppp)3](OTf)6 (4) and [Al2Pd3L6(dppp)3](OTf)6 (5) (where HL is 1-(4-pyridyl)butane-1,3-dione and dppp is 1,3-bis(diphenylphosphino)propane) are reported. Neutral cages 1-3 were synthesised using the tritopic [MIIIL3] metalloligand in combination with the salts CoIICl2 and ZnIIBr2, which both act as tetrahedral linkers. The assembly of the cis-protected [PdII(dppp)(OTf)2] with [MIIIL3] afforded the anionic cages 4-5 of general formula [MIII2PdII3](OTf)6. The metallic skeleton of all cages describes a trigonal bipyramid with the MIII ions occupying the two axial sites and the MII ions sitting in the three equatorial positions. Direct current (DC) magnetic susceptibility, magnetisation and heat capacity measurements on 1 reveal weak antiferromagnetic exchange between the FeIII and CoII ions. EPR spectroscopy demonstrates that the distortion imposed on the {MO6} coordination sphere of [MIIIL3] by complexation in the {MIII2MII3} supramolecules results in a small, but measurable, increase of the zero field splitting at MIII. Complete active space self-consistent field (CASSCF) calculations on the three unique CoII sites of 1 suggest DCo ≈ -14 cm-1 and E/D ≈ 0.1, consistent with the magnetothermal and spectroscopic data.

Cyanide-bridged heterobimetallic magnetic complexes based on metalloporphyrinate and tricyanometalate building blocks

Three novel cyanide-bridged metalloporphyrinate complexes were synthesized and characterized, and their magnetic properties have also been systematically investigated.

Magnetic clusters based on octacyanidometallates

A complete review of all known octacyanide-based clusters with an extensive discussion of their structures, magnetic properties and multifunctionality.

Crystal structures and magneto-structural correlation analysis for several cyano-bridged bimetallic complexes based on MnIII–FeIII systems

The rotation of subunits and its influence on the magnetic coupling in Mn^III–Fe^III systems.