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This review summarizes the rich structural variety of copper and silver chalcogenide clusters with protecting ligand shells of phosphane and/or organic ligands that were generated starting out from silylated chalcogenide sources. This route turned out to be fairly selective and thus allows for the isolation of uniform, polynuclear to nanosized cluster molecules that can consist of only a few or up to hundreds of metal atoms, being bridged by the chalcogen atoms. However, all of these clusters are only kinetically stable with respect to the formation of the binary coinage metal chalcogen phases, but do not collapse into the solid M(2)E materials owing to the protection by bulky ligands on the surface. Upon a more detailed analysis of the development of the structural properties with the cluster size, one recognizes differences for the particular M/E combinations: whereas copper chalcogenide and silver selenide clusters show a clear tendency to approach structural patterns of the Cu(2)E bulk, most obvious for the Cu/Se combination, this is not visible for silver sulfide clusters, even not at the largest species with 490 silver and 302 sulfur atoms. Besides the discussion on the structures of title compounds, the review presents insight into the bonding properties, reactivity, thermal and photophysical properties. The latter can be interpreted in terms of the quantum confinement effect, thus demonstrating the clusters to be understood as intermediates between mononuclear complexes and binary bulk phases.

Tripodal facial and meridional Ru(II) complexes comprising three conjugated legs with acetyl-protected thiol end groups are designed, synthesized and isolated for investigation on a gold surface. Preliminary ultrahigh vacuum scanning tunnelling microscopy (UHV STM) measurements of a monolayer of facial isomer deposited on Au(111) are presented.

The mononuclear compound (1) [Fe(II)(L)(2)](BF(4))(2) (L = 4-ethynyl-2,6-bis(pyrazol-1-yl)pyridine) was prepared and structurally as well as magnetically characterised. The crystallisation revealed the formation of two polymorphs--the orthorhombic 1A and the tetragonal form 1B. A third, intermediate phase 1C was found exhibiting a different orthorhombic space group. Reversibility of the phase transition between 1A and 1C was studied by variable-temperature single-crystal and powder X-ray diffraction studies, while an irreversible phase transition was observed for the transition of 1B→1C. The magnetic studies show that the 1A↔1C transition is accompanied by a very abrupt spin transition (ST) with 8 K hysteresis width (T(1/2)(↓) = 337 K, T(1/2)(↑) = 345 K). The ST was confirmed by Mössbauer spectroscopy as well as by DSC studies. In contrast, the 1B polymorph remained low-spin up to 420 K. In conclusion, a full cycle of intertwined phase- and spin-conversions of three polymorphs could be proven following the general scheme 1B→1C↔1A.

A single-chain magnet (SCM) was constructed from manganese(III) 5,10,15-tris(pentafluorophenyl)corrole complex [Mn(III) (tpfc)] through supramolecular π-π stacking without bridging ligands. In the crystal structures, [Mn(tpfc)] molecules crystallized from different solvents, such as methanol, ethyl acetate, and ethanol, exhibit different molecular orientations and intermolecular π-π interaction or weak Mn⋅⋅⋅O interaction to form a supramolecular one-dimensional motif or dimer. These three complexes show very different magnetic behaviors at low temperature. Methanol solvate 1 shows obvious frequency dependence of out-of-phase alternating-current magnetic susceptibility below 2 K and a magnetization hysteresis loop with a coercive field of 400 Oe at 0.5 K. It is the first example of spin-canted supramolecular single-chain magnet due to weak π-π stacking interaction. By fitting the susceptibility data χ(M) T (20-300 K) of 1 with the spin Hamiltonian expression H = -2J Σ(i=1)(n-1) S(Ai) S(Ai+1) + D Σ(i) S((iZ)(2)), the intrachain magnetic coupling parameter transmitted by π-π interaction of -0.31 cm(-1) and zero field splitting parameter D of -2.59 cm(-1) are obtained. Ethyl acetate solvate 2 behaves as an antiferromagnetic chain without ordering or slow magnetic relaxation down to 0.5 K. The magnetic susceptibility data χ(M) T (20-300 K) of 2 was fitted by assuming the spin Hamiltonian H = -2JΣ(i=1)(n-1) S(Ai) S(Ai+1), and the intrachain antiferromagnetic coupling constant of -0.07 cm(-1) is much weaker than that of 1. Ethanol solvate 3 with a dimer motif shows field-induced single-molecule magnet like behavior below 2.5 K. The exchange coupling constant J within the dimer propagated by π-π interaction is -0.14 cm(-1) by fitting the susceptibility data χ(M) T (20-300 K) with the spin Hamiltonian H = -2J S(A) S(B) + β(S((A)g(A)) + S((B)g(B)))H. The present studies open a new way to construct SCMs from anisotropic magnetic single-ion units through weak intermolecular interactions in the absence of bridging ligands., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two 2,6-bispyrazolylpyridine ligands (bpp) were functionalized with pyrene moieties through linkers of different lengths. In the ligand 2,6-di(1H-pyrazol-1-yl)-4-(pyren-1-yl)pyridine (L1) the pyrene group is directly connected to the bpp moiety via a C-C single bond, while in the ligand 4-(2,6-di(1H-pyrazol-1-yl)pyridin-4-yl)benzyl-4-(pyren-1-yl)butanoate (L2) it is separated by a benzyl ester group involving a flexible butanoic chain. Subsequent complexation of Fe(II) salts revealed dramatic the influence of the nature of the pyrene substitution on the spin-transition behaviour of the resulting complexes. Thus, compound [Fe(L1)(2)](ClO(4))(2) (1) is blocked in its high spin state due to constraints caused by a strong intermolecular π-π stacking in its structure. On the other hand, the flexible chain of ligand L2 in compounds [Fe(L2)(2)](ClO(4))(2) (2) and [Fe(L2)(2)](BF(4))(2)·CH(3)CN·H(2)O (3) prevents structural constraints allowing for reversible spin transitions. Temperature-dependent studies of the photophysical properties of compound 3 do not reveal any obvious correlation between the fluorescence of the pyrene group and the spin state of the spin transition core.

A mononuclear ruthenium(II) polypyridyl complex with an enlarged terpyridyl coordination cage was synthesized by the formal introduction of a carbon bridge between the coordinating pyridine rings. Structurally, the ruthenium(II) complex shows an almost perfect octahedral N6 coordination around the central Ru(II) metal ion. The investigation of the photophysical properties reveals a triplet metal-to-ligand charge transfer emission with an unprecedented quantum yield of 13% and a lifetime of 1.36 mus at room temperature and in the presence of air oxygen. An exceptional small energy gap between light absorption and light emission, or Stokes shift, was detected. Additionally, time-dependent density functional theory calculations were carried out in order to characterize the ground state and both the singlet and triplet excited states. The exceptional properties of the new compound open the perspective of exploiting terpyridyl-like ruthenium complexes in photochemical devices under ambient conditions.

The experimental and theoretical study of the electron spin dynamics in the anionic form of a single-ion molecule magnet (SIMM), the bis-phthalocyaninato terbium (III) molecule [Pc(2)Tb](-)[TBA](+), has been addressed by means of solid state (1)H NMR spectroscopy. The magnetic properties of the caged Tb(3+) metal center were investigated in a series of diamagnetically diluted preparations, where the excess of tetrabutylamonium bromide ([TBA]Br)(n) salt was used as diamagnetic matrix complement. We found that a high temperature activated spin dynamics characterizes the systems, which involved phonon-assisted transitions among the crystal field levels in qualitative agreements with literature results. However, the activation barriers in these processes range from 641 cm(-1) for the diamagnetically diluted samples to 584 cm(-1) for those undiluted; thus, they exhibit barriers 2-3 times larger than witnessed in earlier (230 cm(-1)) reports (e.g., Ishikawa, N.; Sugita, M.; Ishikawa, T.; Koshihara, S.; Kaizu, Y. J. Am. Chem. Soc. 2003, 125, 8694-8695). At cryogenic temperatures, fluctuations are driven by tunneling processes between the m = +6 and -6 low-energy levels. We found that the barrier Delta and the tunneling rates change from sample to sample and especially the diamagnetically diluted [Pc(2)Tb](-) molecules appear affected by the sample's magneto/thermal history. These observations emphasize that matrix arrangements around [Pc(2)Tb](-) can appreciably alter the splitting of the crystal field levels, its symmetry, and hence, the spin dynamics. Therefore, understanding how small differences in molecular surroundings (as for instance occurring by depositing on surfaces) can trigger substantial modifications in the SIMM property is of utmost importance for the effective operation of such molecules for single-molecule data storage, for example.

The reaction of [(AuCl)2dppm] (dppm=Ph2PCH2PPh2) with PhP(SiMe3)2 and P(SiMe3)3 leads to the formation of the gold cluster compound [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3 (1). The crystal structure investigation shows a central Au7P2 unit formed by two P centered gold tetrahedra sharing the central gold corner. This central unit is surrounded by a 10-membered Au5P5 ring which, together with the remaining six gold atoms, builds two Au4P rectangular and two Au3P trigonal pyramids. The different structure motifs are connected by the phosphine ligands. The compound has been characterized using microanalysis, IR spectroscopy, ESI-MS, and 31P NMR techniques. Luminescence measurements have also been carried out.

A series of spin transition (ST) iron(II) compounds of the type [FeII2](X)2.{S}2 (where is 4'-(4'''-cyanophenyl)-1,2':6'1''-bispyrazolylpyridine, X=ClO4- or BF4-, and S is acetonitrile) was synthesized and magnetically investigated. The effects of the removal of the lattice-solvent molecules and of their different positions relative to the iron(II) cations on the ST process were investigated. Crystallization yields orange block (A.{S}2) crystals of the composition [FeII()2](ClO4)2.{S}2, and two polymorphic compounds of the stoichiometry [FeII()2](BF4)2.{S}2 as red coffin (B.{S}2) and orange block (C.{S}2) crystals. The Fe-N bond distances of A.{S}2 (from 1.921(9) to 1.992(3) A; at 150 K), B.{S}2 (from 1.943(2) to 2.017(2) A; at 180 K) and C.{S}2 (from 1.883(3) to 1.962(3) A; at 180 K) indicate low spin (LS) states of the respective iron(II) ions. Notably, the observed small difference in the Fe-N distances at 180 K for the two polymorphs B.{S}2and C.{S}2 are due to different positions of the acetonitrile molecules in the crystal lattices and illustrate the sensitivity of the spin transition properties on lattice-solvent effects. Variable-temperature single crystal X-ray studies display single-crystal thermochroism (red (LS)<-->orange (HS)) for A.{S}2 and B.{S}2 and ca. 3.6% decrease in the unit cell volume of A.{S}2 from 4403 A3 at 300 K to 4278 A3 at 150 K. The temperature dependent magnetic susceptibilities of A.{S}2 and B.{S}2 demonstrate systematic increase of the spin transition temperatures (T1/2) and continuous decreases of the hysteresis loop width (DeltaT1/2) upon slow lattice-solvent exclusion.

By use of a metallo-supramolecular concept, a linear iron(ii) coordination chain [Fe(II)(L)](n)(BF(4))(2n) (L = 1,4-bis(1,2':6',1''-bispyrazolylpyridin-4'-yl)benzene) was rationally designed and synthesized. The molecular chain shows a reversible spin transition at 323 K with a ca. 10 K wide hysteresis loop.

A one-dimensional supramolecular head-to-tail N+ -H...N-type hydrogen-bonded chain of the complex [FeII(L)2H](ClO4)3.MeOH [L = 4'-(4'''-pyridyl)-1,2':6'1''-bis(pyrazolyl)pyridine] exhibits a reversible, thermally driven spin transition at 286 K with a hysteresis loop of ca. 2 K.

Several ways to synthesize solvated and desolvated calcium tetrahydroaluminate by wet-chemical and mechanochemical methods are presented. The products were characterized by elemental analysis, X-ray diffraction (XRD), and infrared spectroscopy (FTIR). The crystal structure of Ca(AlH(4))(2).4THF was determined. After desolvation, an ultrafine powder was obtained. IR data and the mass balance suggest a compound with the composition Ca(AlH(4))(2), containing tetrahedral [AlH(4)] groups.

Mg(AlH(4))(2) was produced as a nanocrystalline powder by metathesis of NaAlH(4) and MgCl(2). Starting with a structure estimation which was developed from an evaluation of FTIR data and comparison of structural properties of two solvent adducts, quantum chemical calculations were performed on the density functional theory (DFT) level. The calculated atomic positions were used to simulate an X-ray powder diffraction pattern, based on a trigonal unit cell. The simulated pattern was congruent to experimental data. Thus, magnesium alanate exhibits a CdI(2) layer structure, the layers being formed by Mg atoms occupying the Cd sites and AlH(4) tedrahedra occupying the sites of the iodine atoms in CdI(2).