K⊂{[FeII(Tp)(CN)3]4[CoIII(pzTp)]3[CoII(pzTp)]}: a neutral soluble model complex of photomagnetic Prussian blue analogues.

Straightforward access to a new cyanide-bridged {Fe4Co4} "molecular box" containing a potassium ion, namely K⊂{[FeII(Tp)(CN)3]4[CoIII(pzTp)]3[CoII(pzTp)]} (1) (with Tp and pzTp = tris- and tetrakis(pyrazolyl)borate, respectively), is provided, alongside its full characterisation. A detailed analysis of the molecular structure (X-ray diffraction, mass spectrometry, NMR spectroscopy) and electronic properties (EPR spectroscopy, SQUID magnetometry, UV/Vis spectroscopy, cyclic voltammetry) reveals that 1 shows slow magnetic relaxation and a remarkable photomagnetic effect at low temperature which is reminiscent of some FeCo Prussian Blue Analogues (PBAs), and is ascribed to a photo-induced electron transfer. However, in contrast with these inorganic polymers, the overall neutral compound 1 is soluble and remarkably stable in organic solvents such as CH2Cl2. Moreover, 1 shows interesting redox versatility, with electrochemical experiments revealing the possible access to six stable redox states.

The utilization of classical spin Monte Carlo methods to simulate the magnetic behavior of extended three-dimensional cubic networks incorporating M(II) ions with an S = 5/2 ground state spin.

The numerical simulations of the magnetic properties of extended three-dimensional networks containing M(II) ions with an S = 5/2 ground-state spin have been carried out within the framework of the isotropic Heisenberg model. Analytical expressions fitting the numerical simulations for the primitive cubic, diamond, together with (10-3) cubic networks have all been derived. With these empirical formulas in hands, we can now extract the interaction between the magnetic ions from the experimental data for these networks. In the case of the primitive cubic network, these expressions are directly compared with those from the high-temperature expansions of the partition function. A fit of the experimental data for three complexes, namely [(N(CH(3))(4)][Mn(N(3))] 1, [Mn(CN(4))](n)() 2, and [Fe(II)(bipy)(3)][Mn(II)(2)(ox)(3)] 3, has been carried out. The best fits were those obtained using the following parameters, J = -3.5 cm(-)(1), g = 2.01 (1); J = -8.3 cm(-)(1), g = 1.95 (2); and J = -2.0 cm(-)(1), g = 1.95 (3).

Ferromagnetic Coupling through Spin Polarization in a Dinuclear Copper(II) Metallacyclophane.

First organic radicals, now metal complexes: A successful extension to metal complexes of a well-known organic radical approach to ferromagnetism is exemplified by the triplet ground-state molecule containing two Cu(II) centers connected by a double m-phenylenediamide skeleton of the cyclophane type shown in the scheme.

Synthesis, structural characterisation, and Monte Carlo simulation of the magnetic properties of the 3D-stacked honeycomb Cs(n)

Two new polymeric manganese-azido systems with formula Cs(n)-[[Mn(N3)3]n] (1) and [[N(C2H5)4]n][[Mn2-(N3)5(H2O)]n] (2) were synthesised and structurally characterised. Compound 1 crystallises in the P2(1)/n group and consists of a three-dimensional system with end-to-end and end-on azido bridges with the caesium atoms in the holes of the net. Magnetically, compound 1 is a rare case of a three-dimensional network with alternate ferro-antiferromagnetic interactions. Compound 2 crystallises in the P1 group and consists of double chains of manganese atoms bridged by end-on and, the exceptional, (mu-1,1,1)-azido bridges. Magnetically, compound 2 shows net ferromagnetic behaviour. Exact fit of the magnetic data was performed for the two compounds by means of Monte Carlo simulations based on the Metropolis algorithm on sets of 10 x 10 x 10 (1) and 1 x 1 x 320 (2) S = 5/2 classical spin centres.

Synthesis, structural characterization, and Monte Carlo simulation of the magnetic properties of two new alternating MnII azide 2-D honeycombs. Study of the ferromagnetic ordered phase below 20 K.

Reaction of MnII and pyridine derivatives such as 4-methylpyridine (4-Mepy) and 4-ethylpyridine (4-Etpy) led to the new two-dimensional systems trans-[Mn(4-Mepy)2(N3)2]n (1) and trans-[Mn(4-Etpy)2(N3)2]n (2). Compound 1 crystallizes in the triclinic system, P1 group (a = 9.269(2) A, b = 9.635(3) A, c = 18.860(4) A, Z = 4), and compound 2 crystallizes in the monoclinic system, P2(1)/c group (a = 14.416(3) A, b = 8.515(2) A, c = 15.728(4) A, Z = 4). The two compounds show honeycomb structures based on dinuclear Mn-(mu-N3)2-Mn subunits linked to the four nearest-neighbor similar subunits by four end-to-end single azido bridges, but whereas the subunits of compound 1 show the end-to-end Mn-(mu 1,3-N3)2-Mn kind of bridges, compound 2 prefers the end-on Mn-(mu 1,1-N3)2-Mn fragment. Magnetically, compound 1 is an alternating 2-D system with two different antiferromagnetic interactions, whereas compound 2 corresponds to a two-dimensional ferro-antiferromagnetic system showing spin canting and permanent magnetization below 20 K. The coupling constant parameters J1 = -10.1 cm-1, J2 = -4.7 cm-1, and g = 2.019 for 1 and J1 = -5.3 cm-1, J2 = 2.9 cm-1, and g = 2.016 for 2 have been obtained from calculations using the Monte Carlo method based on the Metropolis algorithm.