A high-nuclearity metal-cyanide cluster [Mo6Cu14] with photomagnetic properties.

A high-nuclearity metal-cyanide cluster [Mo6Cu14] has been prepared and its photomagnetic properties investigated. The photoswitchable magnetic phenomenon observed is thermally reversible (T≈ 230 K). In the field of photomagnetism, [Mo6Cu14] represents a unique example of a nanocage and the highest nuclearity observed so far.

Red-light-driven photocatalytic hydrogen evolution using a ruthenium quaterpyridine complex.

A high-temperature, microwave synthesis of [Ru(qpy)3](2+) (qpy = 4,4':2',2'':4'',4'''-quaterpyridine) affords the photosensitiser in quantitative yield. The complex produces H2 photocatalytically in a range extending from the UV region of the spectrum to the red with greater efficiency when compared to [Ru(bpy)3](2+).

First evidence of light-induced spin transition in molybdenum(IV).

Photo-induced spin transition in a molybdenum-zinc complex has been evidenced and fully characterized by Squid magnetometry and several spectroscopies performed under irradiation (IR, EPR, etc.). The phenomenon has been confirmed by X-ray diffraction and DFT calculations yielding a Light-Induced Excited Spin State Trapping Effect (LIESST) on a 4d transition metal ion.

A new family of hetero-tri-metallic complexes [M(CuTb)]n (n = 1, 2, ∞; M = Co, Cr, Fe): synthesis, structure and tailored single-molecule magnet behavior.

A new family of hetero-tri-metallic complexes [M(CuTb)]n (M(III) = Co, Cr, Fe; n = 1, 2, ∞), composed of three series of three compounds (oligo- and poly-nuclear complexes based on [Cu-Tb] subunits), is presented and fully characterized. These nine compounds, viewed as different assemblies of single-molecule magnet (SMM) building blocks, connected to various hexacyanometalate centers, illustrate how the SMM behavior of the [CuTb] moiety can be modulated via the control of intermolecular interactions. Specifically, the combination of the "non-innocent" diamagnetic [Co(III)(CN)6](3-) center with a [Cu-Tb](3+) moiety enabled isolation of the magnetic entities, resulting in an improvement of the SMM behavior (ranging from Ueff = 5-7 cm(-1) to 15-17 cm(-1)).

Understanding the photomagnetic behavior in copper octacyanomolybdates.

The mechanism of photomagnetism in copper octacyanomolybdate molecules is currently under debate. Contrary to the general belief that the photomagnetic transition occurs only due to a photoinduced electron transfer from the molybdenum to the copper atom, recent X-ray magnetic dichroic (XMCD) data clearly indicate that this phenomenon is associated at low temperature to a local low-spin-high-spin transition on the molybdenum atom. In this article we provide theoretical justification for these experimental facts. We show the first simulation of X-ray absorption (XAS) and magnetic circular dichroism (XMCD) spectra at the L(2,3) edges of molybdenum from the joint perspective of density functional theory (DFT) calculations and ligand field multiplet (LFM) theory. The description of electronic interactions seems mandatory for reproducing the photomagnetic state.

Mixed valency and magnetism in cyanometallates and Prussian blue analogues.

Prussian blue (PB) is a well-known archetype of mixed valency systems. In magnetic PB analogues {CxAy[B(CN)6]z}.nH2O (C alkali cation, A and B transition metal ions) and other metallic cyanometallates {Cx(AL)y[B(CN)8]z}.nH2O (L ligand), the presence of two valency states in the solid (either A-B, or A-A' or B-B') is crucial to get original magnetic properties: tunable high Curie temperature magnets; photomagnetic magnets; or photomagnetic high-spin molecules. We focus on a few mixed valency pairs: V(II)/V(III)/V(IV); Cr(II)/Cr(III); Fe(II)-Fe(III); Co(II)-Co(III); Cu(I)-Cu(II); and Mo(IV)/Mo(V), and discuss: (i) the control of the degree of mixed valency during the synthesis, (ii) the importance of mixed valency on the local and long-range structure and on the local and macroscopic magnetization, and (iii) the crucial role of the cyanide ligand to get these original systems and properties.

Exchange coupling in cyano-bridged homodinuclear Cu(II) and Ni(II) complexes: synthesis, structure, magnetism, and density functional theoretical study.

The synthesis and structural characterization of several new cyano-bridged copper(II) and nickel(II) homodinuclear complexes is presented. The measure of magnetic properties for these complexes is complemented with a computational study of the exchange coupling for several model structures representing this family of compounds. The influence of several factors on the coupling constant has been examined, coordination position occupied by the bridging ligand, distortions of the coordination environment, and relative disposition of the cyanide ion with respect to the M-M vector. Comparison of experimental and calculated coupling constants allows for the rationalization of the most relevant features of the exchange interaction between two identical metal ions through a cyano bridge.