[Au(Et2dtc)2][TcNCl4] – Darstellung und Struktur

[Au(Et₂dtc)₂][TcNCl₄] – Synthesis and Structure [Au(Et₂dtc)₂][TcNCl₄] (Et₂dtc^– = N,N‐diethyldithiocarbamate) is formed by the reaction of [Au(CO)Cl] with [TcN(Et₂dtc)₂] in dichloromethane. The solid state structure of the compound is characterized by a large triclinic unit cell (space group, P1, a = 9.422(2), b = 22.594(5), c = 32.153(7) Å, α = 72.64(1), β = 85.19(1), γ = 86.15(1)°, Z = 12) and shows an unusual arrangement due to long‐range contacts between the technetium atoms and sulfur atoms of the [Au(Et₂dtc)₂]⁺ units (3.45–3.56 Å) which assemble two anions and one cation to {[TcNCl₄][Au(Et₂dtc)₂] · [TcNCl₄]}^– moieties.     

[Hg8(μ‐n‐C3H7Te)12(μ‐Br)Br3] — Synthesis and Structure

The novel mercury‐tellurium cluster [Hg₈(μ‐n‐C₃H₇Te)₁₂(μ₂‐Br)Br₃] is formed during the reaction of HgBr₂ and (n‐C₃H₇Te)₂Hg in DMSO. Its crystal structure has been elucidated showing [Hg₈(μ‐n‐C₃H₇Te)₁₂(μ₂‐Br)]³⁺ units with a bromine‐centered distorted Hg₈ cube. The mercury atoms are bridged by n‐C₃H₇Te^— ligands and the resulting clusters are linked to a three‐dimensional network by bromine atoms. The close packing of the cluster is mainly determined by the flexible n‐propyl residues of the telluride building blocks.     

[Tc(NBCl2Ph)Cl2(Me2PhP)3] und [Tc(NBH3)Cl2(Me2PhP)3] – die ersten Technetium‐Komplexe mit Nitridobrücken zwischen Technetium und Bor

[Tc(NBCl₂Ph)Cl₂(Me₂PhP)₃] and [Tc(NBH₃)Cl₂(Me₂PhP)₃] – the First Technetium Complexes with Nitrido Bridges between Technetium and Boron [TcNCl₂(Me₂PhP)₃] reacts with BCl₂Ph or BH₃ · THF at low temperatures under formation of complexes containing a nitrido bridge between technetium and boron. The compounds are instable and decompose at room temperature under cleavage of the N–B bonds. The pale‐purple [Tc(NBCl₂Ph)Cl₂(Me₂PhP)₃] crystallizes in the orthorhombic space group Fdd2. The Tc≡N bond is only slightly lengthened by the formation of the N–B bond of 1.564(4) Å. However, a considerable lengthening of the Tc–Cl bond in trans position to the nitrido ligand is observed which can be attributed to an decreasing of the structural trans influence of the nitrido moiety. A similar structural feature can be found in [Tc(NBH₃)Cl₂(Me₂PhP)₃] which is the first structurally characterized transition metal complex containing a nitrido bridge to unsubstituted borane.     

Structures of Iodophenyltellurium(II) and Diiododi-(β-naphtyl)tellurium(IV)

The reactions between diphenyl ditelluride, (PhTe)₂, or di(β-naphtyl)ditelluride, (β-naphtylTe)₂, with equivalent amounts of iodine have been reinvestigated and the crystal and molecular structures of iodophenyltellurium(II), (PhTeI)₄, and diiododi-(β-naphtyl)tellurium(IV), (β-naphtyl)₂TeI₂, have been determined. The structure of iodophenyltellurium(II) (space group Cc, a = 13.850(5) Å, b = 13.852(3) Å, c = 16.494(6) Å and β = 101.69(2)°, Z = 4) is built up by four PhTeI units which are linked by weak Te–Te interactions with Te–Te distances between 3.152(5) Å and 3.182(4) Å. The angles between the tellurium atoms are approximately 90° giving an almost perfect square. Long range secondary bonds (Te–I: about 4.2 Å) link the tetrameric units to give an infinite two-dimensional network. Iodo(β-naphtyl)tellurium(II) is less stable than the phenyl derivative. Solutions of this compound decompose under formation of elemental tellurium and (β-naphtyl)₂TeI₂. (β-Naphtyl)₂TeI₂ crystallises in the monoclinic space group C 2/c (a = 21.198(6) Å, b = 5.8921(8) Å, c = 16.651(5) Å, β = 114.77(2)°). The tellurium atom is situated on a two-fold crystallographic axis and Te–I and Te–C bond lengths of 2.899(1) and 2.108(7) Å have been determined.     

Synthesis and Structure of (NH4)2[(AuI4)(MI4)] (M = Ga,In)

The compounds (NH₄)₂[(AuI₄)(MI₄)] (M = Ga, In) were obtained in sealed glass ampoules by reaction of I₂, NH₄I, Au and Ga or In as air‐sensitive black crystals. Both compounds crystallize in the orthorhombic space group Pnma (No. 62) and are isotypic: (NH₄)₂[(AuI₄)(GaI₄)], a = 12.619(2), b = 20.625(5) and c = 7.693(2) Å; (NH₄)₂[(AuI₄)(InI₄)], a = 12.587(2), b = 20.606(5) and c = 7.696(2) Å. The structures can be described as constituted of NH₄⁺ cations and anionic zig zag chains of alternating tetrahedral MI₄^– (M = In, Ga) and square planar AuI₄^– units running along [010]. Within the chains, the MI₄^– ions form weak interactions with two of their I atoms to the AuI₄^– ions resulting in strongly elongated AuI₆ octahedra.     

(Bu4N)[Re{NB(C6F5)3}Cl4(OH2)] – Struktur und EPR-Spektren

(Bu₄N)[Re{NB(C₆F₅)₃}Cl₄(OH₂)] – Structure and EPR Spectra The title compound represents the first structurally characterized rhenium(VI) complex with a bridging nitrido ligand. It has been prepared by the reaction of (Bu₄N)[ReNCl₄] with B(C₆F₅)₃ in CH₂Cl₂. An almost linear (170.5(3)°) nitrido bridge with a Re≡N bond length of 1.672(4) Å is formed. The coordination position trans to the multiple bond is occupied by a molecule of water. The EPR parameters of the title complex are reported and discussed with those of [ReNCl₄]^– concerning the spin-density distribution in the ‘‘ReNCl₄”︁”︁ unit.     

Density distributions in nuclei

Density distribution across the nuclear surface is obtained in the approximation of relatively sharp nuclear edge. It is used to determine dynamical parts of the density relevant to density vibration resonances. Results of the simple calculations are in close agreement with detailed microscopic theories.     

Variance inequalities for functions of Gaussian variables

LetX be a standard Gaussian random variable andG an absolutely continuous function. The inequality $$Var G(X) \leqslant E(G'(X))^2 $$ was proved in Nash and later rediscovered in Brascamp and Lieb as a special case of a general inequality and in Chernoff. All the proofs are based on properties of the Gaussian density. By using the characteristic function rather than the density, generalizations with higher order derivatives are obtained. The method also establishes potentially useful connections with Karlin's total positivity.