Synthese von 4-Trichlorsilylmethylbenzonitril und 4-(2-Trichlorsilyläthyl)pyridin zur Oberflächenmodifikation von Zinndioxid

Synthesis of 4-Trichlorosilylmethylbenzonitrile and 4-(2-Trichlorosilylethyl)pyridine for Surface Modification of Tin Dioxide We describe the synthesis of 4-(trichlorosilylmethyl)benzonitrile and 4-(2-trichlorosilylethyl)pyridine, starting from 4-(bromomethyl)benzonitrile and trichlorosilane or vinylpyridine and trichlorosilane. Trimethoxysilanes are obtained by reaction of the trichlorosilyl compounds with methyl orthoformate. 4-(Trichlorosilylmethyl)benzonitrile and 4-(2-trichlorosilylethyl)pyridine are used to modify the surface of tin dioxide.     

Die Reaktionen von Dimethylsulfoxid mit Molybdäntetrabromid und Molybdändibromid-dinitrosyl Die Kristallstruktur von [MoBr2(NO)2(OSMe2)2]

Reactions of Dimethyl Sulfoxide with Molybdenum Tetrabromide and Molybdenum Dibromide Dinitrosyl. Crystal Structure of [MoBr₂(NO)₂(OSMe₂)₂] In the cold molybdenum tetrabromide reacts with an equivalent amount of dimethyl sulfoxide forming the solvate [MoBr₄(OSMe₂)₂]; excess dimethyl sulfoxide yields [MoO₂Br₂(OSMe₂)₂] which is also obtained by other methods. Molybdenum dibromidedinitrosyl forms the solvate [MoBr₂(NO)₂(OSMe₂)₂] in the reaction with dimethyl sulfoxide. According to the i.r. spectra all complexes display O-coordination of the OSMe₂ molecules. [MoBr₂(NO)₂(OSMe₂)₂] crystallizes monoclinic in the space group P2₁/c with four formula units per unit cell. The cell dimensions are a = 1236, b = 892, c = 1305 pm, β = 95.2°. 1662 independent observed reflexions were used for refinement; R = 3.8%. The molybdenum atoms are six-coordinated, the O atoms of the dimethyl sulfoxide molecules are in trans-position to the nitrosyl ligands, which form linear groups Mo? N? O.     

Cyclothiazenokomplexe von Molybdän(V) und (VI), sowie von Wolfram(VI) Die Kristallstruktur von (PPh4)2[MoCl3(N3S2)]2 · 2 CH2Cl2

Cyclothiazeno Complexes of Molybdenum(V), Molybdenum(VI), and Tungsten(VI). Crystal Structure of (PPh₄)₂[MoCl₃(N₃S₂)]₂ · 2 CH₂Cl₂ . From excess trithiazylchloride and molybdenum or tungsten hexacarbonyl, respectively, the cyclothiazeno complexes [MCl₃(N₃S₂)]₂(S₂N₂) are obtained. They possess metal atoms linked via a planar S₂N₂ ring. The corresponding bromo compounds [MBr₃(N₃S₂)]₂(S₂N₂) can be obtained in liquid bromine from S₄N₄ and MoBr₄ or WBr₆, respectively, or from S₄N₄ with the corresponding metal hexacarbonyls in the presence of bromine. Thermolysis of [WBr₃(N₃S₂)]₂(S₂N₂) yields [WBr₃(N₃S₂)]₂ which is dimerized via nitrogen bridges. When [MoCl₃(N₃S₂)]₂(S₂N₂) reacts with tetraphenylphosphonium chloride in dichloromethane, the S₂N₂ acts as reducing agent, and the paramagnetic molybdenum(V) complex (PPh₄)₂[MoCl₃(N₃S₂)]₂ · 2 CH₂Cl₂ is obtained (μ_eff = 1.2 B.M.). The i.r. spectra are reported. The crystal structure of (PPh₄)₂[MoCl₃(N₃S₂)]₂ · 2 CH₂Cl₂ was determined by X-ray diffraction (2524 independent reflexions, R = 0.052). It crystallizes in the space group P1 with the lattice con- stants a = 943.9, b = 1209.6, c = 1469.2 pm, α = 69.27, β = 72.20 and γ = 82.08°, Z = 1. There are tetraphenylphosphonium cations and centrosymmetric, dimeric anions [MoCl₃(N₃S₂)]₂^2?. The molybdenum atoms are part of six-membered cyclothiazeno rings MoN₃S₂ with MoN bond lengths of 177 and 197 pm; the N atom with the longer MoN bond is linked to the second Mo atom, so that a planar Mo₂N₂ ring results; this ring is nearly coplanar with the two MoN₃S₂ rings. Furthermore, each molybdenum atom is linked with three chlorine atoms with MoCl bond lengths of 240–242 pm, so that the Mo atoms possms a distorted octahedral coordination.     

Disulfidoverbrückte Halogenokomplexe von Molybdän(V) Kristallstrukturen von (PPh3Me)2[Cl4Mo(μ-S2)2MoCl4] · 2 CH2Cl2 und (PPh4)2[Br4Mo(μ-S2)2MoBr4] · 3 CH2Br2

Disulfido-Bridged Halo Complexes of Molybdenum (V). Crystal Sructures of (PPh₃Me)₂ [Cl₄Mo (μ-S₂)₂MoCl₄]. 2 CH₂Cl₂ and (PPh₄)₂[Br₄Mo(μ-S₂)₂MoBr₄]. 3CH₂Br₂ . Mo(S₂)Cl₃ is prepared by an improved method; the i.r. spectrum is reported. In dichloro methane solution it reacts with (PPh₃Me)Cl forming the complex (PPh₃Me)₂[Cl₄Mo(μ-S₂)₂MoCl₄] · 2 CH₂Cl₂. The bromo complex (PPh₄)₂[Br₄Mo(μ-S₂)₂MoBr₄] · 3 CH₂Br₂ is obtained by reaction of MoBr₄ with S₇NH and subsequent treatment of the reaction mixture with PPh₄Br in CH₂Br₂ solution. Both complexes are characterized by i.r. spectra and structural analyses by X-ray methods. (PPh₃Me)₂[Cl₄Mo(μ-S₂)₂MoCl₄] · 2 CH₂Cl₂ crystallizes monoclinic in the space group P2₁/c with two formula units per unit cell (5268 observed independent reflexions, R = 4.0%). The lattice dimensions are: a = 1097 pm, b = 1510 pm, c = 1591 pm, β = 104.4°. (PPh₄)₂[Br₄Mo(μ-S₂)₂MoBr₄] · 3 CH₂Br₂ crystallizes triclinic in the space group P&1macr; with two formula units per unit cell and the lattice constants a = 1328 pm, b = 1573 pm, c = 1719 pm, α = 95.8°, β = 96.3°, γ = 74.1°. Both compounds are of ionical structure with PPh₃Me^⊕ and PPh₄^⊕ cations, respectively, and anions [X₄MO(μ-S₂)₂MoX₄]^2? very similar to each other. The molybdenum atoms are bridged by two disulfido ligands and are bonded directly with a bond length of 286 pm. The terminal halogen atoms add up to coordination number nine at the molybdenum.     

Struktur und ausgewählte Reaktionen von ReCl4(PPh3)2

ReCl₄(PPh₃)₂ – Reactions and Structure The compounds ReCl₄(PPh₃)₂ and Re₂OCl₃(C₂H₅COO)₂(PPh₃)₂ resulting from the reaction of ReOCl₃(PPh₃)₂ with PPh₃ in boiling propionic acid and HCl atmosphere were characterized by their VIS-spectra and structural data. Ligand exchange reactions with acetylacetone gave ReCl₂(acac)₂ as well as ReCl₂(acac)(PPh₃)₂. Crystallographic data see “Inhaltsübersicht”.     

Röntgenographische Kristallstrukturuntersuchung von Magnesiumperrhenat-tetrahydrat Mg(ReO4)2 · 4 H2O

Crystal Structure of Magnesium Perrhenate Tetrahydrate Mg(ReO₄)₂ · 4 H₂O The crystal structure of Mg(ReO₄)₂ · 4 H₂O was determined from single-crystal X-ray diffractometer data. The compound is triclinic, space group P1, with lattice parameters a = 769.2, b = 702.6, c = 646.9 pm, α = 108.279, β = 92.388, γ = 120.418°, Z = 1, ?_calcd. = 3.58 g · cm^?3, ?_exp. = 3.62 g · cm^?3. The structure was solved in anisotropic approximation from 2990 observed reflections and refined to an index R of 7.4%. The rhenium atom is tetrahedrally, the magnesium atom octahedrally coordinated.     

Butatrien durch Thermolyse von Propiolsäure-(2-propinyl)ester

Flow thermolysis of 2-propynyl propiolate (5) at 580° afforded butatriene (6) (ca. 50%) and, as by-products, 4-methylene-2-cyclobuten-1-one (7) , 2-ethynylpropenal (8) , 1-penten-4-yn-3-one (9) , 4-penten-2-ynal (10) (total ca. 10%), along with some propynal, acetylene, CO₂ and CO. In the same way, propiolic acid (1,1-D₂)-2-propynyl propiolate (11) led to (1,1-D₂)-butatriene (12) and a little 4-((D₂)methylene)-2-cyclobuten-1-one (13). A mechanism is proposed for the transformation of 5 into 6 and of 11 into 12 , which also accounts for the formation of 7,8,9 and 10 , as well as 13. The position of one of the published ¹³C-NMR signals of butatriene (6) must be revised. Thermolysis of methyl- (1) and ethyl propiolate (2) resulted in small yields of 2-buten-4-olide (3) and 2-penten-4-olide (4).     

Die Kristallstruktur von MgHg(SCN)4 · 2 H2O

Crystal Structure of MgHg(SCN)₄ · 2 H₂O The crystal structure of the monoclinic MgHg(SCN)₄ · 2 H₂O (a ? 1 335.1(6) pm, b ? 531.6(5) pm, c ? 1 867.0(14) pm, β ? 92.3(1)°, Z ? 4, space group C2/c) contains nearly tetrahedral Hg(SCN)₄ and octahedral Mg(OH₂)₂(NCS)₄ groups. These groups are joined together with Hg? SCN? Mg bridges and are forming a network of layers.     

Ligandenaustauschreaktionen von Bis(acetylacetonato)dioxo-molybdän(VI). Kristallstrukturen von [Salicylaldehyd-benzoylhydrazonato(2–)]dioxo-methanol-molybdän(VI) und [Benzoylaceton-benzoylhydrazonato(2–)] dioxo-triphenylphosphanoxid-molybdän(VI)

Ligand Exchange Reactions of Bis(acetylacetonato)dioxo-molybdenum(VI). Crystal Structures of [Salicylaldehyde-benzoylhydrazonato(2–)]dioxo-methanol-molybdenum(VI) and [Benzoylacetone-benzoylhydrazonato(2–)]dioxo-triphenylphosphaneoxide-molybdenum(VI) The products of ligand exchange reactions between bis(acetylacetonato)dioxo-molybdenum(VI) and tridentate diacidic ligands H₂L in the presence of triphenylphosphane were found by mass spectrometry to be complexes of the type MoO₂L. In the case of salicylaldehyde 2-hydroxyanil MoL₂ could also be identified. The compounds MoO₂L were crystallized as complexes with methanol or triphenylphosphane oxide. Crystallographic data see “Inhaltsübersicht”.     

Synthese und Kristallstrukturen von α‐ und β‐Ba3(PS4)2 sowie von Ba3(PSe4)2

Synthesis and Crystal Structures of α‐, β‐Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ were prepared by heating mixtures of the elements at 800 °C for 25 h. Both compounds were investigated by single crystal X‐ray methods. The thiophosphate is dimorphic and undergoes a displacive phase transition at about 75 °C. Both modifications crystallize in new structure types. In the room temperature phase (α‐Ba₃(PS₄)₂: P2₁/a; a = 11.649(3), b = 6.610(1), c = 17.299(2) Å, β = 90.26(3)°; Z = 4) three crystallographically independent Ba atoms are surrounded by ten sulfur atoms forming distorted polyhedra. The arrangement of the PS₄ tetrahedra, isolated from each other, is comparable with the formation of the SO₄^2? ions of β‐K₂SO₄. In β‐Ba₃(PS₄)₂ (C2/m; a = 11.597(2), b = 6.727(1), c = 8.704(2) Å; β = 90.00(3)°; Z = 2) the PS₄ tetrahedra are no more tilted along [001], but oriented parallel to each other inducing less distorted tetrahedra and polyhedra around the Ba atoms, respectively. Ba₃(PSe₄)₂ (P2₁/a; a = 12.282(2), b = 6.906(1), c = 18.061(4) Å; β = 90.23(3)°; Z = 4) is isotypic to α‐Ba₃(PS₄)₂ and no phase transition could be detected up to about 550 °C.     

Die Reaktion von Molybdänpentachlorid mit (SCN)2, (SeCN)2 und ICN

Reaction of Molybdenum Pentachloride with (SCN)₂, (SeCN)₂, and ICN By reaction of MoCl₅ with (SCN)₂, (SeCN)₂, and ICN in CCl₄ or H₂CCl₂ the compounds MoCl₅(NCS)₂, MoCl₅(NCSe)₂, and MoCl₅NCI were obtained. They are very sensitive towards hydrolysis and decompose on heating. The compounds are characterized by their vibrational and EPR spectra which indicate that the pseudohalogen is bonded via a nitrogen atom.     

Zur polarographischen Reduktion von Molybdän(VI) und Molybdän(V) in Gegenwart von Citronensäure

According to the ratio of citric acid to molybdenum different citratomolybdenum(VI) complexes exist at pH <2. Only one citratomolybdenum(VI) complex exists in solutions with a great excess of citric acid (20:1). In such solutions the polarographic reduction of Mo^VI proceeds in two waves: First Mo^VI → M^V, then Mo^V → Mo^IV, which disproportionates into Mo^V and Mo^III however. Furthermore, it is possible that the Mo^IV reacts with Mo^VI forming Mo^V, so that also a catalytic character can be attributed to the second wave besides a kinetic one.