The Periodic-Table-A Universal Icon: Its Birth 150 Years Ago, and Its Popularization Through Literature Art and Music.

This Essay projects the spark of genius of Mendeleev, whose efforts led to the effective formulation of the periodic table, which has placed the entire world of chemical matter on a palm. The periodic table gave rise to a central paradigm, which did for chemistry what Newton had done for physics and Darwin for biology. Subsequently the Essay recounts the popularization of the Periodic Table through literature by Primo Levi, Oliver Sacks and others, and through music and art by composers and artists, such as Jerry Feldman, the King Crimson band, Tom Lehrer, and George Brecht, Blair Bradshaw, Eugènia Balcells, etc.

Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy.

Transition metal ions with long-lived spin states represent minimum size magnetic bits. Magnetic memory has often been associated with the combination of high spin and strong uniaxial magnetic anisotropy. Yet, slow magnetic relaxation has also been observed in some Kramers ions with dominant easy-plane magnetic anisotropy, albeit only under an external magnetic field.

All-round robustness of the Mn19 coordination cluster system: experimental validation of a theoretical prediction.

Experimental and theoretical studies indicate that achieving the maximum possible ground spin state of ST = 83/2 for the mixed-valent Mn19 coordination cluster is insensitive to replacement of its eight μ3-N3 ligands by μ3-Cl, μ3-Br, μ3-OH or μ3-OMe, substantiating that the ferromagnetic interactions are indeed mediated mainly by the internal (μ4-O) ligands. The robustness of the inorganic {Mn(III)12Mn(II)7(μ4-O)8} core is clear from the molecular structure and ESI-MS studies have shown that the structure of the Mn19 aggregate, and also of its Mn18Y analogue, are stable beyond the solid state.

A MnII6MnIII6 single-strand molecular wheel with a reuleaux triangular topology: synthesis, structure, magnetism, and DFT studies.

The use of the anion of 3-methyl-1,3,5-pentanetriol (mpt(3-)) in manganese carboxylate chemistry has afforded the new Mn(II/III)12 cluster [Mn(II)6Mn(III)6(mpt)6(CH3CO2)12(py)6]·3CH3CN (1·3CH3CN). Complex 1 was isolated in moderate yield by the reaction of Mn(CH3CO2)2·4H2O and H3mpt in a 2.6:1 molar ratio in a solvent mixture of acetonitrile and pyridine.

Huge magnetic anisotropy in a trigonal-pyramidal nickel(II) complex.

The work presented herein shows the experimental and theoretical studies of a mononuclear nickel(II) complex with the largest magnetic anisotropy ever reported. The zero-field-splitting D parameter, extracted from the fits of the magnetization and susceptibility measurements, shows a large value of -200 cm(-1), in agreement with the theoretical value of -244 cm(-1) obtained with the CASPT2-RASSI method.

Spin-polarized transport through single-molecule magnet Mn6 complexes.

The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green's function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six Mn(III) cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state.

Mononuclear single-molecule magnets: tailoring the magnetic anisotropy of first-row transition-metal complexes.

Magnetic anisotropy is the property that confers to the spin a preferred direction that could be not aligned with an external magnetic field. Molecules that exhibit a high degree of magnetic anisotropy can behave as individual nanomagnets in the absence of a magnetic field, due to their predisposition to maintain their inherent spin direction. Until now, it has proved very hard to predict magnetic anisotropy, and as a consequence, most synthetic work has been based on serendipitous processes in the search for large magnetic anisotropy systems.

Synthesis, crystal structure and magnetism of new salicylamidoxime-based hexanuclear manganese(III) single-molecule magnets.

Salicylamidoxime was used to synthesize 13 new polynuclear Mn(III) complexes. We present the crystallographic structures, the magnetic susceptibility and the magnetization measurements of eight of them (1-8) with the general formula [Mn(6)O(2)(H(2)N-sao)(6)(L)(2)(solvent)(4-6)] (L = carboxylate, chloride, 2-cyanophenolate; solvent = H(2)O, MeOH, EtOH, py). These complexes consist of two trinuclear {Mn(III)(3)(μ(3)-O)(H(2)N-sao)(3)}(+) cationic units linked together via two oximate and two phenolate oxygen atoms.

Field and dilution effects on the slow relaxation of a luminescent DyO9 low-symmetry single-ion magnet.

A mononuclear Dy(III) complex with a non-Schiff base compartmental ligand has been prepared and characterised by X-ray crystallography and ac magnetic susceptibility measurements. The complex exhibits SIM behaviour induced by dilution and/or magnetic field with two thermally activated relaxation processes.

Theoretical study of exchange coupling in 3d-Gd complexes: large magnetocaloric effect systems.

Polynuclear 3d transition metal-Gd complexes are good candidates to present large magnetocaloric effect. This effect is favored by the presence of weak ferromagnetic exchange interactions that have been investigated using methods based on Density Functional Theory. The first part of the study is devoted to dinuclear complexes, focusing on the nature and mechanism of such exchange interactions.

Family of carboxylate- and nitrate-diphenoxo triply bridged dinuclear Ni(II)Ln(III) complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): synthesis, experimental and theoretical magneto-structural studies, and single-molecule magnet behavior.

Seven acetate-diphenoxo triply bridged M(II)-Ln(III) complexes (M(II) = Ni(II) and Ln(III) = Gd, Tb, Ho, Er, and Y; M(II) = Zn(II) and Ln(III) = Ho(III) and Er(III)) of formula [M(μ-L)(μ-OAc)Ln(NO(3))(2)], one nitrate-diphenoxo triply bridged Ni(II)-Tb(III) complex, [Ni(μ-L)(μ-NO(3))Tb(NO(3))(2)]·2CH(3)OH, and two diphenoxo doubly bridged Ni(II)-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H(2)O)(μ-L)Ln(NO(3))(3)]·2CH(3)OH have been prepared in one pot reaction from the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H(2)L). Moreover, Ni(II)-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(μ-L)(μ-BzO)Dy(NO(3))(2)] and [Ni(μ-L)(μ-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(μ-O(2))Ln bridging fragment of ~22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ~13° and ~2°, respectively.

S(T) = 22 [Mn10] supertetrahedral building-block to design extended magnetic networks.

The controlled organization of high-spin complexes, eventually single-molecule magnets, is a great challenge in molecular sciences to probe the possibility to design sophisticated magnetic systems to address a large quantity of magnetic information. The coordination chemistry is a tool of choice to make such materials. In this work, high-spin S(T) = 22 [Mn(10)] complexes, such as [Mn(III)(6)Mn(II)(4)(L(1))(6)(μ(4)-O)(4)(μ(3)-N(3))(4)(CH(3)CN)(11)(H(2)O)]·(ClO(4))(2)·(CH(3)CN)(8.

Mononuclear Fe(II) single-molecule magnets: a theoretical approach.

The single-molecule magnet behavior found in mononuclear tetracoordinate Fe(II) complexes with trigonal monopyramidal coordination due to large magnetic anisotropy has been analyzed using theoretical methods based on CASSCF-RASSI calculations. We focus our study on the dependence of such magnetic properties on the geometrical parameters of the complexes (asymmetry of the ligands and the out-of-plane shift of the Fe(II) cation with respect to the three equatorial nitrogen atoms) and the influence of the basicity of the N ligands. Low basicity, larger shifts, and larger distortions of the FeN(4) central framework decrease the D value and increase the E value.

Magnetic properties of largest-spin single molecule magnets: Mn17 complexes--a density functional theory approach.

The exchange coupling constants of two Mn(17) complexes have been analyzed; one of them has the second largest ground-state spin value reported up to now, being the largest-spin single-molecule magnet. The two complexes show a two-edge-sharing supertetrahedra structural motif, Mn(II)(6)Mn(III)(11), and similar ligands, but they show different total spin values. One of them has the highest possible, S = 37, while for the second complex, the S value is lower and equal to 28 ± 1.

The trigonal prism in coordination chemistry.

Herein we analyze the accessibility of the trigonal-prismatic geometry to metal complexes with different electron configurations, as well as the ability of several hexadentate ligands to favor that coordination polyhedron. Our study combines i) a structural database analysis of the occurrence of the prismatic geometry throughout the transition-metal series, ii) a qualitative molecular orbital analysis of the distortions expected for a trigonal-prismatic geometry, and iii) a computational study of complexes of several transition-metal ions with different hexadentate ligands. Also the tendency of specific electron configurations to present a cis bond-stretch Jahn-Teller distortion is analyzed.

A new family of oxime-based hexanuclear manganese(III) single molecule magnets with high anisotropy energy barriers.

A magneto-structural study of two salicylamidoxime-based {Mn(6)} single-molecule magnets revealed that their anisotropy energy barriers, which can reach the current record for d-transition metal complexes, are strongly dependent upon the precise arrangement of ligands and the solvation state.

Theoretical methods enlighten magnetic properties of a family of Mn(6) single-molecule magnets.

Magnetic properties of the family of Mn(6) complexes with oximato bridging ligands, some of them showing the highest anisotropy energy barriers known to date, have been studied using theoretical methods based on density functional theory. The different magnetic behaviors, total spin values from 4 to 12, are well reproduced by the calculated exchange coupling constants. The analysis of the magnetostructural correlations indicates that the Mn-N-O-Mn torsion angles play a crucial role, with the out-of-plane shift of the central oxo bridging ligand involved to a lesser degree.

Can theoretical methods go beyond the experimental data? The case of molecular magnetism.

The complexity of polynuclear transition metal complexes with the most appealing magnetic properties makes it impossible to extract the values of exchange interactions between the paramagnetic centers using experimental techniques. Hence, theoretical methods based on density functional theory are used because they allow the accurate estimation of such values. Three Mn(6) complexes were studied and the calculated exchange coupling constants used to plot a magnetic susceptibility curve that can be compared with the experimental ones.

Jahn-Teller distortions of six-coordinate CuII compounds: cis or trans?

Unlike their octahedral analogues, copper(II) compounds with trigonal prismatic stereochemistry undergo an elongation of two bonds in cis positions due to a Jahn-Teller effect, a behavior that can also occur in slightly twisted octahedra.

Covalent radii revisited.

A new set of covalent atomic radii has been deduced from crystallographic data for most of the elements with atomic numbers up to 96. The proposed radii show a well behaved periodic dependence that allows us to interpolate a few radii for elements for which structural data is lacking, notably the noble gases. The proposed set of radii therefore fills most of the gaps and solves some inconsistencies in currently used covalent radii.