Atomic Scale Evidence of the Switching Mechanism in a Photomagnetic CoFe Dinuclear Prussian Blue Analogue.

Molecular complexes based on Prussian Blue analogues have recently attracted considerable interest for their unique bistable properties combined to ultimately reduced dimensions. Here, we investigate the first dinuclear FeCo complex exhibiting both thermal and photomagnetic bistability in the solid state. Through an experimental and theoretical approach combining local techniques-X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), and ligand field multiplet calculations-we were able to evidence the changes occurring at the atomic scale in the electronic and magnetic properties.

Structural Diversities in Heterometallic Mn-Ca Cluster Chemistry from the Use of Salicylhydroxamic Acid: {MnCa}, {MnCa}, {MnCa}, and {MnCa} Complexes with Relevance to Both High- and Low-Valent States of the Oxygen-Evolving Complex.

One-pot reactions between the [MnO(OCPh)(py)] triangular precursors and either CaBr·xHO or CaCl·6HO, in the presence of salicylhydroxamic acid (shaH), have afforded the heterometallic complexes [MnCa(OCPh)(shi)(HO)(MeCO)] (1) and (pyH)[MnMnCaCl(OCPh)(shi)(py)] (2), respectively, in good yields. Further reactions but using a more flexible synthetic scheme comprising the Mn(NO)·4HO/Ca(NO)·4HO and Mn(OCPh)·2HO/Ca(ClO)·4HO "metal blends" and shaH, in the presence of external base NEt, led to the new complexes (NHEt)[MnMnCa(OEt)(shi)(EtOH)] (3) and (NHEt)[MnCa(CO)(shi)] (4), respectively. In all reported compounds, the anion of the tetradentate (N,O,O,O)-chelating/bridging ligand salicylhydroxime (shi), resulting from the in situ metal-ion-assisted amide-iminol tautomerism of shaH, was found to bridge both Mn and Ca atoms.

Large Orbital Magnetic Moment Measured in the [TpFe(III)(CN)3](-) Precursor of Photomagnetic Molecular Prussian Blue Analogues.

Photomagnetism in three-dimensional Co/Fe Prussian blue analogues is a complex phenomenon, whose detailed mechanism is not yet fully understood. Recently, researchers have been able to prepare molecular fragments of these networks using a building block synthetic approach from mononuclear precursors. The main objective in this strategy is to isolate the smallest units that show an intramolecular electron transfer to have a better understanding of the electronic processes.

Switchable Fe/Co Prussian blue networks and molecular analogues.

With the long term objective to build the next generation of devices from the molecular scale, scientists have explored extensively in the past two decades the Prussian blue derivatives and their remarkable physico-chemical properties. In particular, the exquisite Fe/Co system displays tuneable optical and magnetic behaviours associated with thermally and photo-induced metal-to-metal electron transfer processes. Recently, numerous research groups have been involved in the transfer of these electronic properties to new Fe/Co coordination networks of lower dimensionality as well as soluble molecular analogues in order to facilitate their manipulation and integration into devices.

Metal-to-metal electron transfer in Co/Fe Prussian Blue molecular analogues: the ultimate miniaturization.

Co/Fe Prussian Blue analogues are known to display both thermally and light induced electron transfer attributed to the switching between diamagnetic {Fe(II)LS(μ-CN)Co(III)LS} and paramagnetic {Fe(III)LS(μ-CN)Co(II)HS} pairs (LS = low spin; HS = high spin). In this work, a dinuclear cyanido-bridged Co/Fe complex, the smallest {Fe(μ-CN)Co} moiety at the origin of the remarkable physical properties of these systems, has been designed by a rational building-block approach. Combined structural, spectroscopic, magnetic and photomagnetic studies reveal that a metal-to-metal electron transfer that can be triggered in solid state by light, temperature and solvent contents, is observed for the first time in a dinuclear complex.

2-Pyrrolyloximes in high-nuclearity transition-metal cluster chemistry: Fe10 and Fe12.

The employment of 2-pyrrolyloximes in high-nuclearity transition-metal cluster chemistry has provided access to unprecedented decanuclear and dodecanuclear Fe(III) cagelike clusters bearing the anion of pyrrole-2-carboxaldehyde oxime (praoH(2)), the simplest member of this new family of ligands; the identity of the products depends on the nature of the counteranion present in the starting materials.

First palladium(II) and platinum(II) complexes from employment of 2,6-diacetylpyridine dioxime: synthesis, structural and spectroscopic characterization, and biological evaluation.

Employment of the monoanion of 2,6-diacetylpyridine dioxime (dapdoH(2)) as a tridentate chelate in palladium(II) and platinum(II) chemistry is reported. The syntheses, crystal structures, spectroscopic and physicochemical characterization, and biological evaluation are described of [PdCl(dapdoH)] (1) and [PtCl(dapdoH)] (2). Reaction of PdCl(2) with 2 equivs of dapdoH(2) in MeOH under reflux gave 1, whereas the same reaction with PtCl(2) in place of PdCl(2) gave 2 in comparable yields (70-80%).

Towards models of the oxygen-evolving complex (OEC) of photosystem II: a Mn4Ca cluster of relevance to low oxidation states of the OEC.

Synthetic access has been achieved into high oxidation state Mn/Ca chemistry with the 4 : 1 Mn : Ca stoichiometry of the oxygen-evolving complex (OEC) of plants and cyanobacteria; the anion of (Et(3)NH)(2)[Mn(III)(4)Ca(O(2)CPh)(4)(shi)(4)] has a square pyramidal metal topology and an S = 0 ground state.

Alpha-benzoin oxime in higher oxidation state 3d metal cluster chemistry: structural and magnetic study of a new Mn(III)(9) complex.

The initial employment of alpha-benzoin oxime (bzoxH(2)) in higher oxidation state 3d metal cluster chemistry has provided access to a new enneanuclear Mn(III) complex with an unprecedented metal-core topology consisting of two triangular [Mn(3)(mu(3)-Omicron(2-))(mu-OmicronNu)(3)](4+) fragments connected by a linear [Mn(3)(mu-OmicronNu)(6)](3+) unit. The Mn(III)(9) cluster is antiferromagnetically coupled and has an S = 3 spin ground state.