Synthese und Kristallstruktur von SMe3 ⊕[MoBr4(SMe2)2]−

Synthesis and Crystal Structure of SMe₃^⊕ [MoBr₄(SMe₂)₂]^? . The title compound is obtained from MoBr₄ and excess dimethyl sulfide, forming red crystals which are only slightly sensitive to moisture. Whereas the intermediately formed adduct of MoBr₄ and SMe₂ is unstable, the stable adduct [Mo(NO)₂Br₂(SMe₂)₂] can be prepared from Mo(NO)₂Br₂ and SMe₂. According to the structural analysis by X-ray methods, SMe₃ ^⊕[MoBr₄(SMe₂)₂]^? crystallizes orthorhombic in the space group Imma with eight formula units per unit cell, the cell dimensions being a = 1578, b = 2820, c = 856 pm (1303 observed, independent reflexions). The compound consists of S(CH₃)₃^⊕ cations with S? C bond lengths of 180 pm and C? S? C bond angles of 102° and 103° resp., and anions [MoBr₄(SMe₂)₂]^?. The molybdenum atom is coordinated octahedral by four bromine atoms in equatorial positions and the two S atomes of the SMe₂ donor molecules in axial sites with Mo? S bond lengths of 254 pm.     

Ca6GaN5 und Ca6FeN5. Verbindungen mit [CO3]2−-isosteren Anionen [GaN3]c− und [FeN3]6−

Ca₆GaN₅ and Ca₆FeN₅: Compounds Containing [CO₃]^2?-isosteric Anions [GaN₃]^6? and [FeN₃]^6? The isotypic phases Ca₆GaN₅ and Ca₆FeN₅ (hexagonal, P6₃/mem; a = 627.7(3)/ 623,7(1) pm, c = 1219.8(3)/1233.2(6) pm; Z = 2) are prepared by reaction of Ca/Ga mixtures (molar ratio 6:1) and Fe/Ca₃N₂/Ca mixtures (molar ratios from 3:1:13 to 5:2:15) with nitrogen at temperatures of 850°C and 950°C to 1100°C, respectively. The structures contain trigonal-planar anions [MN₃]^6? which are isosteric to carbonate ions (Ga? N: 195,1(28) pm; Fe? N: 177,0(15) pm). The structures are closely related to those compounds of the hydrotalcite group.     

Na(V3−xNbx)Nb6O14 – ein neues Oxoniobat mit [Nb6O12]- und [M2O9]-Clustern

Na(V_3?xNb_x)Nb₆O₁₄ — A Novel Oxoniobate with [Nb₆O₁₂] and [M₂O₉] Clusters Goldcolored single crystals and black powders of Na(V_3?xNb_x)Nb₆O₁₄ have been prepared by heating a pellet containing a mixture of NaNbO₃, NbO₂, NbO, VO₂ and NaF or Na₂B₄O₇ (as mineralizers) at 900°C in a sealed gold capsule. The analytically determined Nb : V ratio is 5 : 1 and means that x is about 1.5. The compound crystallizes in P6₃/m with a = 603.4(1), c = 1807.9(5) pm and Z = 3. The crystal structure can be described in terms of common close packing of sheets of O and Na atoms together with Nb₆ octahedra. Characteristic building groups of the new structure type are [Nb₆O₁₂] clusters, [M₂O₉] clusters and NbO₅ bipyramids. V atoms are distributed only on the positions of the Nb atoms within the trigonal bipyramids or the [M₂O₉] clusters. The [Nb₆O₁₂] clusters show characteristicaly short distances d_Nb-Nb = 279.4 and 281.3 pm, respectively. In the [M₂O₉] units, which are built from two MO₆ octahedra that share a common face, V or Nb atoms form M–M dumbbells with d_M–M = 255.9 pm. The electronic structure is discussed using Extended Hückel calculations.     

Tetraazidodiammincobaltate(III): Cis-[Co(N3)4(NH3)2]− und [Co(N3)4en]−

Tetra-azidodiamminecobaltates(III): cis-[Co(N₃)₄(NH₃)₂]^? and [Co(N₃)₄en]^? The preparation and the properties of complexes containing the anions cis-[Co(N₃)₄(NH₃)₂]^? and [Co(N₃)₄en]^? are described. The compounds [Co(NH₃)₆][Co(N₃)₄(NH₃)₂ · H₂O], [Co(N₃)₂(NH₃)₄][Co(N₃)₄(NH₃)₂], [As(C₆H₅)₄][Co(N₃)₄en], cis- and trans-[Co(N₃)₂en₂][Co(N₃)₄en] have been isolated.     

Synthese und Struktur des μ-Sulfido-μ-disulfido-octabromodiwolframat(V)-Ions [W2S3Br8]2−

Synthesis and Structure of μ-Sulfido-μ-disulfido-octabromoditungstate(V), [W₂S₃Br₈]^?2 Tungsten hexabromide reacts with H₂S in dichloromethane yielding a brown product which, by addition of tetraphenylphosphonium bromide in CH₂Cl₂, is converted to brown, crystalline (PPh₄)₂[Br₄W(μ-S)(μ-S₂)WBr₄] · CH₂Cl₂ · CH₂S. Its IR spectrum is reported, its crystal structure was determined by X-ray diffraction (2330 reflexions, R = 0.097). Crystal data: orthorhombic, Pnma, a = 1 766.5, b = 2 412.7, c = 1 416.3 pm, Z = 4. In the diamagnetic [W₂S₃Br₈]^2? ions the two W atoms are linked via a sulfido and a disulfido bridge and by a W? W bond.     

Ti9Se2 – Eine Verbindung mit kolumnaren [Ti9]-Baueinheiten

The Metal-Rich Titanium Selenide Ti₉Se₂ The new compound Ti₉Se₂ has been prepared as hitherto most metal-rich phase in the system titanium-selenium. It crystallizes in the orthorhombic space group Pbam (No. 55) with a = 691.7(2), b = 1 550.5(9), c = 345.4(2) pm. The structure consists of [Ti₉]-strings which are described within the concept of condensed clusters. The Se atoms are coordinated by tricapped trigonal prisms of Ti atoms.     

Die Feinstruktur in den Schwingungs- und elektronischen Absorptionsspektren von [CrO4]2− und [MnO4]−

Finestructure in the Vibrational and Electronic Absorption Spectra of [CrO₄]^2? and [MnO₄]^? The ir and ra spectra of Tl₂[CrO₄] and (C₂H₅)₄N[MnO₄] are measured and assigned. Details of the preresonance- and resonance-Raman effect are discussed. The exact knowledge of the vibrational spectrum enables the understanding of the complicated vibrational finestructure in the electronic absorption spectrum of (C₂H₅)₄N[MnO₄]. For the states of the charge-transfer t₁ → e* bands are found at 15 000, 15 170 cm^?1 for ¹T₁(I), at 17 646, 17 708, 17 809 cm^?1 for ¹T₂(II) and at 17 920, 17 992 and 18 080 cm^?1 for ³T₂(III). The electronic origin for the states of the t₂ → e* chargetransfer is at 24 661 for ¹T₁(IV) and 30 230 cm^?1 for ¹T₂(V). The vibrational coupling is only with the totally symmetric Mn? O-stretching-vibration. Bands at 29 500 cm^?1 and 44 450 cm^?1 are assigned to the ¹T₂-states of the t₁, t₂ → t₂* charge-transfer.     

Synthese und Kristallstrukturen von [Ti(NPh2)4] und [Ti2(μ-O)(NPh2)6]

Crystal Structures of [Ti(NPh₂)₄] and [Ti₂(μ-O)(NPh₂)₆] [Ti(NPh₂)₄] has been prepared from TiCl₃(THF)₃ and LiNPh₂, the μ-oxo complex [Ti₂(μ-O)(NPh₂)₆] results from partial hydrolysis of [Ti(NPh₂)₄] in toluene solution. Both complexes are characterized by crystal structure determinations. In [Ti(NPh₂)₄] the titanium atom is coordinated by the four nitrogen atoms in a distorted tetrahedral fashion with Ti–N bond lengths of 193.8 pm in average. In [Ti₂(μ₂-O)(NPh₂)₆] the μ-oxo ligand forms a linear symmetric TiOTi bridge with rTiO = 181.2 pm and TiN = 193.4 pm in average.