Structure determination in a new type of amorphous molecular solids with different nonlinear optical properties: a comparative structural analysis.

The microscopic structures of two amorphous molecular solids with extremely nonlinear optical properties have been studied. They consist of organotetrel chalcogenide clusters with the chemical formula [(RSn)4S6]. The basic molecular building blocks are adamantane-like {Sn4S6} cores with organic ligands R attached to the Sn atoms. While the material equipped with R=naphthyl generates frequency doubling upon irradiation with a simple infrared laser diode, the material decorated with R=phenyl responds by emitting brilliant white light. The structural differences were investigated using x-ray scattering and extended x-ray absorption fine structure combined with molecular Reverse Monte Carlo. Transmission electron microscopy and scanning precession electron diffraction were used to examine structural differences from mesoscopic down to microscopic scales. Characteristic differences were found on all scales. While close core-to-core distances between {Sn4S6} cluster cores and molecular distortions are found in the white light emitting material, undistorted molecules and significantly larger core distances characterize the material showing frequency doubling. Here however, results of scanning precession electron diffraction reveal the formation of nanocrystalline structures in the amorphous matrix, which we identify as cause for the suppression of white light emission.

Smallest molecular chalcogenidometalate anions of the heaviest metals: syntheses, structures, and their interconversion.

The syntheses of the first molecular meta-selenidomercurate(ii), ortho-telluridothallate(iii) and a hydrate of an ortho-selenidoplubate(iv) are presented alongside an improved and facile synthesis of the selenidobismuthate(iii) with almost quantitative yields. By means of quantum chemical calculations, the energetics of the interconversions of small metalate anions is discussed and the existence of the heaviest homologues of [NO2](-), [NO3](-), [PO4](2-) and [CO3](2-) are predicted.

Stannaborate transition metal chemistry: ligand properties, reactivity, and density functional theory calculations of platinum and palladium complexes.

Three stannaborate complexes of platinum(II) and a novel stannoborate palladium(II) derivative have been prepared in excellent yield. The tin transition metal bond is formed through nucleophilic substitution and the resulting complexes [Bu3MeN] [trans-[(Et3P)2Pt(SnB11H11)H]] (6), [trans-[(Et3P)2Pt(SnB11H11)(CNtBu)]] (7), [Bu3MeN]2[trans-[(Et3P)2Pt(SnB11H11)2-(CNtBu)]] (8), and [Bu3MeN][(dppe)-Pd(SnB11H11)Me] (12) (dppe = 1,2-bis-(diphenylphosphanyl)ethane) were characterized by NMR spectroscopy and elemental analysis. In the cases of the zwitterion 7, the pentacoordinated complex 9, the palladium salt 12 and [(triphos)Pt(SnB11H11)] (10) (triphos = 1,1,1-tris(diphenylphosphanylmethyl)ethane), their solid-state structures are determined by X-ray crystal structure analyses. The trans influence of the [SnB11H11] ligand is evaluated from the results of the IR spectroscopy and X-ray crystallographic structures of complexes 6, 7, and 12. The dipole moment of the zwitterion 7 is calculated by density functional theory (DFT) methods. The alignment of the dipole moments of the polar molecules 7 and 12 in the solid state is discussed.

A new route into single-crystalline partially oxidized cobalt compounds: reactions with zintl-type hexaselenodistannate(III) K6Sn2Se6 as mild oxidant

Reactions of K6Sn2Se6 (1) with [Cp*CoCl]2 were investigated in order to probe the stability of the formal +3 oxidation state at Sn and possible ligand properties of heteroatomic zintl-type anion "Sn2Se6(6)- ". From these experiments, we obtained the following compounds that are oxidized to different extent as a result of the reaction with SnIII: [Cp2*Co][Cl2Co(mu2-Cl)2Li(thf)2] (2), [(Cp*Co)3(mu-Se)2] (3), [(Cp*Co)3(mu3-Se)2][Cl2Co(mu2-Cl)2Li(thf)2] (4), and [(Cp*Co)4(mu3-Se)4] (5). These compounds were structurally characterized by single-crystal X-ray diffractometry. It shows that the reaction conditions strongly affect the type and oxidation state of the isolated product. Two of the observed compounds, 3 and 4, are closely related both structurally and electronically; this is discussed and further illustrated by cyclovoltammetric measurements. The choice of the terminal Cp* ligand attached to the transition metal in the reactand complex is assumed to be basically dependent for the alignment of unexpected structural details when compared with known compounds of similar compositions. In conclusion, 1 is observed to act as mild oxidant as well as selenide donor, but is not in the position to keep its Sn-Se framework under the given reaction conditions.

Homoleptic lanthanide complexes of chelating phosphanamides-an experimental and theoretical study.

Four chelating ligands are present in the first phosphanamide complexes of Group 3 metals and the lanthanides (see structure shown). However, these ligands coordinate to form a distorted molecular structure. The compounds were characterized by single-crystal X-ray structure analysis and quantum-mechanical investigations with density functional theory and MP2 methods.