Darstellung und Kristallstruktur des ersten polymeren Phosphorselenids catena-(P4Se4)x

Preparation and Crystal Structure of the First Polymeric Phosphorus Selenide catena-(P₄Se₄)_x Catena-(P₄Se₄)_x was prepared in crystalline form from the elements using iodine as a catalyst, and characterized by means of X-ray diffraction and IR spectroscopy. Single-crystal investigations (space group P2₁/c, a = 1 119.2(3), b = 728.2(2), c = 1 142.5(3) pm, β = 115.91(2)°, V = 837.5(7) · 10⁶ pm³) revealed parallel chains of P₄Se₃ hetero-norbornane units linked via Se atoms. Thus, being the first phosphorus selenide which does not contain discrete molecules, catena-(P₄Se₄)_x can be regarded as a polymeric form of α-P₄Se₄ or as a crystalline modification of vitrous phosphorus selenide.     

Über grünes Bis-(2-Iminoisopropyl-thiophenolato)-nickel(II) und weitere, ähnliche NiII-Komplexe

Green Bis-(2-iminoisopropyl-thiophenolato)nickel(II) and other Similar Ni^II Complexes The compounds [Ni^II(iitp)₂] 1 (iitp = 2-iminoisopropyl-thiophenolate), [Ni(imptp)₂] · 2 CH₃OH 2 , a dinuclear compound with an Ni? Ni distance of 276 pm, and [PPh₄] · [Ni^II(imptp)(SCN)] 3 (imptp = 2-(2-iminopentane-4-on)-thiophenolate) have been prepared by the reaction of nickel(II)-acetate-tetrahydrate with 2-iminoisopropyl-thiophenole and 2-(2-iminopentane-4-on)-thiophenole in methanol, respectively. They have been characterized by single-crystal X-ray structure analysis and other physical methods. The redox behaviour of 1–3 has been studied in detail (chemically as well as by cyclovoltammetry and ESR spectroscopy). Particularly interesting are the electronic properties of 1 and its reduction with NaBH₄ and the following reaction of the product with O₂. The complexes are model compounds for some Ni-containing enzymes. For details of the crystal structure determination see “Inhaltsübersicht”.     

Asymptotically independent topological indices on random trees

Topological indices are graph invariants used in computational chemistry to encode molecules. A frequent problem when performing structure-activity studies is that topological indices are inter-correlated. We consider a simple topological index and show asymptotic independence for a random tree model. This continues previous work on the correlation among topological indices. These findings suggest that a size-dependence in a certain class of distance-based topological indices can be eliminated.AMS subject classification: 05C80, 60E10, 92E10     

Synthesis,Spectroscopic and EPR Results and Crystal Structure of Copper(II) Formato Derivatives with Pyrazine and Dimethylpyrazines

The complexes of copper formato with pyrazine and dimethylpyrazines: Cu(HCOO)₂(pyrz) ( 1 ), Cu₂(HCOO)₄(pyrz) ( 2 ), Cu₂(HCOO)₄(2,3‐Me₂pyrz) ( 3 ), Cu₂(HCOO)₄(2,5‐Me₂pyrz) ( 4 ), and Cu₂(HCOO)₄(2,6‐Me₂pyrz)₂ ( 5 ) have been synthesized and characterized by chemical analysis and IR and electronic spectro scopies. The three‐dimensional structure of compound 1 consists of –Cu–pyrz–Cu–pyrz– chains joined by bridging formate groups coordinated, in configuration syn‐anti, to two copper atoms. The coordination around the copper atom is orthorhombic with two Cu–O distances of 2.374(1) Å, two Cu–O of 1.952 Å and two Cu–N of 2.080 Å. Compound 5 is formed by molecular dimers with the [Cu₂(μ‐HCOO)₄] unit, two copper atoms and four syn‐syn fomate groups, and two ligands coordinated to the copper atoms in the axial positions. In compounds 2 and 3 chains of [Cu₂(μ‐HCOO)₄] dimers with pyrz or 2,3‐Me₂pyrz as bridging ligands are formed. The EPR signal of 1 is orthorhombic (g = 2.23, 2.20 and 2.06). In the EPR spectra of 2 – 5 compounds the triplet (S = 1) signals are observed. The g_?, g_∥ and D values are been calculated.     

CeO2—LnO1.5固溶体的表征及其甲烷催化燃烧性能

向CeO2中引入Ln3 离子后形成的CeO2－LnO1.5（Ln=La，Nd，Sm，Gd）固溶体（n（Ce）：n（Ln）=1：1）是一种无贵金属的新型高效甲烷燃烧催化剂．比表面、XRD、Raman、TEM等分析证实，这类固溶体具有部分畸变的萤石结构，Ln3 进入晶格后诱发的结构变化使得团溶体的表面和本体能同时参与氧化还原反应．实验表明，该固态溶液体系是甲烷催化燃烧的良好催化剂．     

Preparation and structural characterization of a hexanuclear molybdenum (II) cluster containing carboxylate ligands (Bu4N)2[Mo6(μ3-Cl)8(O2CMe)6]

The hexamolybdenum cluster complex [Mo₆(₃-Cl)₈(O₂CMe)₆]^2–, 1 was isolated as the Bu₄N⁺ salt in 71% yield from the reaction of (Bu₄N)₂[Mo₆(₃-Cl)₈Cl₆] with AgO₂CMe in CH₂Cl₂ solvent. The compound was characterized by single crystal X-ray diffraction analysis. The cluster contains an octahedral arrangement of six molybdenum atoms with eight chloride ligands bridging the eight trianglar faces and six carboxylate ligands terminally coordinated through one oxygen atom to each of the six molybdenum atoms. Crystal data: space group =P2₁/n,a=10.713(3)Å,b=14.43(1)Å,c=21.919(4)Å, =94.37(2)°,Z=2, 1965 reflections,R=0.036.     

三核簇合物(Et4N)2[(CO)4MoS2MoS2Mo(CO)4]和(Et4N)2[(CO)4MoS2WS2Mo(CO)4]的合成及晶体结构

合成了含Mo(0)的三核化合物(Et₄N)₂[(CO)₄Mo(μ-S)₂Mo(μ-S)₂Mo(CO)₄](Ⅰ)和(Et₄N)₂[(CO)₄Mo(μ-S)₂W(μ-S)₂Mo(CO)₄](Ⅱ),测定了(Ⅰ)的晶体结构.Ⅰ属单斜晶系,空间群P2相似文献   

Hydrothermal synthesis and crystal structure of a layered vanadium oxide with an interlayer metal coordination complex: [Co(phen)3][V10O26]·H2O

A novel compound, [Co(phen)₃][V₁₀O₂₆]·H₂O, was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic space group Ccca with a=13.447(3), b=29.936(6), c=23.252(5) Å, V=9360(3) Å³, Z=8 and R=0.0285. Data were collected on a Rigaku R-AXIS RAPID IP diffractometer at 293 K in the range of 1.36<θ<24.99°. The structure of the compound consists of vanadium oxide layers, which are built up from the infinite VO₄ chains by corners and edges sharing. The [Co(phen)₃]²⁺ complexes occupy the interlayer space and contact each other via π−π stacking interactions of the phen groups to form infinite one-dimensional chains.     

Structural Studies of Bis(cyclopentadienyl)molybdenum‐Amino Acid Complexes

The crystal structures of molybdocene‐amino acid compounds of the type [Cp₂Mo^IV(κN, κO‐AA)]⁺Cl^—·xH₂O with AA = D ‐phenylalaninato (x = 1.5), DL ‐leucinato (x = 2) and DL ‐valinato (x = 1) have been determined (Cp = η⁵‐C₅H₅). The compounds feature an almost planar, five‐membered chelate ring of the aminocarboxylate moiety (deprotonated amino acid) with the molybdenum atom. In the phenylalaninato complex π‐stacking between the phenyl rings is found. The complexes were proven kinetically stable at pH < 1 for at least 24 h.     

As12Se44—: ein neuartiges Selenoarsenatanion mit einem Polyarsenkäfig in der Verbindung [Co(NH3)6]2As12Se4 · 12 NH3

As₁₂Se₄^4—: a New Selenoarsenate Anion with a Polyarsenic Cage in the Compound [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ Orange coloured crystals of [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ were prepared by the reduction of As₄Se₄ with a solution of sodium in liquid ammonia and subsequent precipitation with CoBr₂. The X‐ray structure determination shows them to contain the selenoarsenate anion As₁₂Se₄^4—, which consists of a central As₁₂‐cage with four exo‐bonded, formally negatively charged Se atoms. The structure of the As₁₂‐cage is equivalent to the main polyphosphorus building unit of a known organopolyphosphane and of tubular P₁₂ in the compound (CuI)₃P₁₂.