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An octahedral {DyIII6} cage within a diamagnetic {ZnII4} rectangle is reported, with magnetic relaxation studies revealing single-molecule magnet behaviour for the complex under zero external dc field with Ueff = 43 K and τo = 1 × 10-5 s.

A family of heterometallic Anderson-type 'wheels' of general formula [MIII2MII5(hmp)12](ClO4)4 (where MIII = Cr or Al and MII = Ni or Zn giving [Cr2Ni5] (1), [Cr2Zn5] (2), [Al2Ni5] (3) and [Al2Zn5] (4); hmpH = 2-pyridinemethanol) have been synthesised solvothermally. The metallic skeleton common to all structures describes a centred hexagon with the MIII sites disordered around the outer wheel. The structural disorder has been characterised via single crystal X-ray crystallography, 1-3D 1H and 13C solution-state NMR spectroscopy of the diamagnetic analogue (4), and solid-state 27Al MAS NMR spectroscopy of compounds (3) and (4). Alongside ESI mass spectrometry, these techniques show that structure is retained in solution, and that the disorder is present in both the solution and solid-state. Solid-state dc susceptibility and magnetisation measurements on (2) and (3) reveal the Cr-Cr and Ni-Ni exchange interactions to be JCr-Cr = -1 cm-1 and JNi-Ni,r = -5 cm-1, JNi-Ni,c = 10 cm-1. Fixing these values allows us to extract JCr-Ni,r = -1.2 cm-1, JCr-Ni,c = 2.6 cm-1 for (1), the exchange between adjacent Ni and Cr ions on the ring is antiferromagnetic and between Cr ions on the ring and the central Ni ion is ferromagnetic.

ortho-Vanillin in the presence of nickel and lanthanide ions yields three types of heteronuclear Ni

The syntheses, structures, magnetic and thermodynamic properties of three related triethanolamine-based Gd

The employment of 2-amino-isobutyric acid, Haib, and 2-hydroxy-1-naphthaldehyde, Hnaphth, in Ni

The use of pyridine-2-amidoxime (pyaoxH

Two new infinite coordination chain compounds [Gd(CH3CO2)3(dmf)]∞ (1) and {[Gd(HO(CH2)3CO2)3(H2O)]·H2O}∞ (2) have been obtained attempting to modify a prototype molecular cooler. The structures of both compounds as determined by single-crystal X-ray diffraction are reported, together with a detailed study of their magnetic and thermal properties, describing for both compounds a large magneto-caloric effect. The dominant ferromagnetic interaction present in 2 clearly favours this material at low applied magnetic fields, with respect to 1 that exhibits antiferromagnetic interactions. Magneto-structural correlations of the sign and strength of the magnetic interactions are derived for carboxylato-bridged Gd(III) systems., This work has been supported by the Spanish MINECO and FEDER through grants MAT2011-24284 and MAT2012-38318-C03-01 and by an EU Marie Curie IEF (PIEF-GA-2011-299356 toG. L.).

The solid-state structure of the known complex [Et4N][U(NCS)5(bipy)2] has been re-determined and a detailed spectroscopic and magnetic study has been performed in order to confirm the oxidation states of both metal and bipy ligand. Electronic absorption and infrared spectroscopy suggest that the uranium is in its +4 oxidation state and this has been corroborated by emission spectroscopy and variable temperature magnetic measurements, as well as theoretical calculations. Therefore the bipy ligands are neutral, innocent ligands and not, as would be inferred from just a solid state structure, radical anions., We thank TCD and MINECO (MAT2012-38318-C03), and EC for a Marie Curie-IEF (PIEF-GA-2011-299356 to GL) for funding this work.

The trifluorido complex mer-[CrF3(py)3] (py = pyridine) reacts with 1 equiv. of [Ln(hfac)3(H2O)2] and depending on the solvent forms the tetranuclear clusters [Cr2Ln2(μ-F)4(μ-OH)2(py)4(hfac)6], 1Ln, and [Cr2Ln2(μ-F)4F2(py)6(hfac)6], 2Ln, in acetonitrile and 1,2-dichloroethane, respectively (Ln = Y, Gd, Tb, Dy, Ho, and Er; hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone). Reaction with [Dy(hfac)3(H2O)2] in dichloromethane produces the dinuclear cluster [CrDy(μ-F)F(OH2)(py)3(hfac)4], 3Dy. All the clusters feature fluoride bridges between the chromium(III) and lanthanide(III) centres. Fits of susceptibility data for 1Gd and 2Gd reveal the fluoride-mediated chromium(III)–lanthanide(III) exchange interactions to be 0.43(5) cm−1 and 0.57(7) cm−1, respectively (in the H = JS1 . S2 convention). Heat capacity measurements on 2Gd reveal a moderate magneto-caloric effect (MCE) reaching −ΔSm(T) = 11.4 J kg−1 K−1 for ΔB0 = 9 T → 0 T at T = 4.1 K. Out-of-phase alternating-current susceptibility (χ′′) signals are observed for 1Dy, 2Dy and 2Tb, demonstrating slow relaxation of the magnetization., M.E. thanks Spanish MINECO (contracts MAT2009-13977-C03 and CSD2007-00010) for funding and S.P. the Danish Natural Science Research Council (FNU) for a Sapere Aude Fellowship (10-081659).

Molecular nanomagnets are considered valid candidates for magnetic refrigeration at low temperatures. Designing these materials for enhanced cooling requires the control and optimization of the quantum properties at the molecular level, in particular: spin ground state, magnetic anisotropy, and presence of low-lying excited spin states. Herein, we present the theoretical framework together with a critical review of recent results, and perspectives for future developments., This work is partially funded by the Spanish Ministry for Science and Innovation through grants MAT2009-13977-C03 and CSD2007- 00010, and in the UK through the generous contributions of The Leverhulme Trust and the EPSRC.

We report the synthesis of a series of mixed valence Mn(II/IV) tetranuclear clusters [Mn(II)2Mn(IV)2O2(heed)2(EtOH)6Br2]Br2 (1), [Mn(II)2Mn(IV)2O2(heed)2(H2O)2Cl4].2EtOH.H2O (2.2EtOH.H2O), [Mn(II)2Mn(IV)2O2(heed)2(heedH2)2](ClO4)4 (3), [Mn(II)2Mn(IV)2O2(heed)2(MeCN)2(H2O)2(bpy)2](ClO4)4 (4) and [Mn(II)2Mn(IV)2O2(heed)2(bpy)2Br4].2MeOH (5.2MeOH). Clusters 1-5 are constructed from the tripodal ligand N,N-bis(2-hydroxyethyl)ethylene diamine (heedH2) and represent rare examples of tetranuclear Mn clusters possessing the linear trans zig-zag topology, being the first Mn(II/IV) mixed-valent clusters of this type. The molecular clusters can then be used as building blocks in tandem with the (linear) linker dicyanamide ([N(CN)2]-, dca-) for the formation of a novel extended network {[Mn(II)2Mn(IV)2O2(heed)2(H2O)2(MeOH)2(dca)2]Br2}n (6), which exhibits a rare form of the 2D herring bone topology.