Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. VI. Thermische Zersetzung von MoCl3 und MoOCl2

The temperature dependence of the thermal decay of α-MoCl₃ was determined and the entropies of MoCl₃ and MoCl₂ calculated. The decomposition behaviour of MoOCl₂ under equilibrium conditions may be described by the equation The decomposition reactions 6 MoOCl₂,s = Mo + MoO₂ + 4 MoOCl₃,g has only inferior importance. From the results the enthalpy and entropy values of MoOCl₂ are derived (data see “Inhaltsübersicht”).     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. IX. Bildungsenthalpie und Sättigungsdruck des MoOBr3

From the enthalpy of solution of MoOBr₃ in NaOH/H₂O₂ the enthalpy of formation ΔH°(MoOBr₃,f,298) = ?109,5(±0,4) kcal/mol was derived. The sublimation of MoOBr₃ is connected with simultaneous decomposition (see “Inhaltsübersicht”). From the temperature function of the saturated vapor pressure the values ΔH°(subl., MoOBr₃, 298) = 36(±1,5) kcal/mol and ΔS°(subl., MoOBr₃, 298) = 56(±3) cl are calculated.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram,VIII. WOBr3, WOBr2-Bildungsenthalpie und thermische Zersetzung

WOBr₃ and WOBr₂ were prepared by chemical transport reactions. From the solution enthalpy of WOBr₃ in NaOH/H₂O₂ the formation enthalpy ΔH°(WOBr₃,f,298) = ?113,2(±0,9) kcal/Mol was calculated. The thermal decomposition of WOBr₃ proceeds primarly according to 2 WOBr₃ = WOBr₂ + WOBr₄. The decomposition of WOBr₂ may be described by the reaction 2 WOBr₂ = WBr₂ + WO₂Br₂. The interpretation of the decomposition equilibrium of WOBr₃ gives the values ΔH°(WOBr₂,f,298) = ?116,9(±5) kcal/Mol, and S°(WOBr₃,f,298) = 46(±5) cl.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. I. Sättigungsdruck und Bildungsenthalpie von MoO2Br2 und MoO2CI2

Molybdenum dioxiddibromide and -dichloride have been prepared from MoO₂, Br₂, und Cl₂, respectively, and their chemical and thermochemival behaviour was studied. Their enthalpies of formation, ΔH°, have been determined from the solution enthalpies of MoO₂Br₂, and MOo₂Cl₂, in aqueous NaOH (data see ?Inhaltsübersicht”?). From their sublimation pressures, p, the enthalpies, ΔH° (subl.), and entropies, ΔS° (subl.), of sublimation have been evaluated (data see above).     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. IV. Der Transport von MoO2 mit J2 und die Existenz von MoO2J2

The possibility to transport MoO₂ with J₂ in a temperature gradient T₂/T₁ suggests the existence of MoO₂J₂. Starting from the reaction MoO₂ + J₂ ? MoO₂J₂ in the consideration of the function of temperature for the rates of chemical transport, the values ΔH^O_R ? 28.8 (±2) kcal/mole and ΔS^O_R ? 9.0 (±2) cl are deduced. From this the values ΔH^O(MoO₂J₂, g, 298) ? ?99.5 (±3.5) kcal/mole and S^O(MoO₂J₂, g, 298) ? 86 (±3) cl are derived. The comparison of the thermodynamic data for MoO₂X₂ and WO₂X₂ (X = Cl, Br, J) leads to the conclusion, that the existence of MoO₂J₂ in the vapour phase is very probable indeed.     

Beiträge zur Chemie der Oxid-halogenide von Molybdän und Wolfram. VII. Thermische Zersetzung und Bildungsenthalpie von WOCl3 und WOCl2

The thermal decomposition of WOCI₃ proceeds in the first decomposition step according to 2 WOCl₃,s = WOCl₂,s + WOCl₄,g. The second decomposition step of WOCI₃ is identical with the thermal decomposition of WOCI₂, equation see “Inhaltsübersicht” The interpretation of the decomposition equilibrium of WOCl₃ gives the heat of formation: ΔH°(WOCl₂,s,298) = ?155(±4) kcal/Mol. The heat of formation δH° (WOCl₃,s,298) = ?174,15(±0,8) kcal/Mol was determined from the solution enthalpy of WOCl₃ in 2n NaOH with 1% H₂O₂.     

Dichlorphosphatokomplexe der Nitridchloride von Molybdän und Wolfram

Dichlorophosphate Complexes of the Nitrido Chlorides of Molybdenum and Tungsten Tetraphenylarsonium dichlorophosphate AsPh₄[PO₂Cl₂], is prepared by the reaction of AsPh₄Cl with P₂O₃Cl₄. The vibrational spectrum is reported as well as the valence force constants of the [PO₂Cl₂]^? ion. The f-values are clearly smaller than those of the isoelectronic SO₂Cl₂ molecule. The dichlorophosphate ion forms complexes with the nitride chlorides MNCl₃ (M ? Mo, W) of the type [MNCl₃(PO₂Cl₂)]₂^2?, which are characterized by their i.r. spectra.     

Beiträge zur Chemie und Struktur von Vanadylhalogeniden

Investigations on the Chemistry and Structure of Vanadyl-halogenides Aqueous solutions of VOI₂ can be prepared from VOSO₄ and BaI₂. By concentrating VOI · 3 H₂O is formed; but adducts of VOI₂ with DMSO and DMF can be isolated. The structure of [VO(DMSO)₅]I₂ was determined by X-ray single crystal techniques: Monoclinic; space group P2₁/c; a = 10.696; b = 10.877; c = 24.74 Å; ß = 109.87°; Z = 4. – Other new compounds are VO(OCH₃)Br · 3 pyr and VOBr₂ · 2 H₂O · 2 eth, which can be decomposed to VOBr₂. The structures of VOCl₂ and VOBr₂ were determined from crystal powders (space group I mmm). IR and reflection spectra (4–50 kK) and magnetic moments of all compounds were measured.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXIV. Darstellung und Eigenschaften von Tetrabenzylmolybdän und -uran

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXIV. Preparation and Properties of Tetrabenzyl Molybdenum and Tetrabenzyl Uranium Tetrabenzyl molybdenum, (C₆H₅CH₂)₄Mo, can be obtained by the reaction of MoCl₄ · 2 THF with dibenzyl magnesium. The compound forms darkbrown crystals, which are stable at room temperature. The analogous reaction of UCl₄ · 3 THF with dibenzyl magnesium yields a reddish brown complex of tetrabenzyl uranium of the formula (C₆H₅CH₂)₄U · MgCl₂. The synthesized compounds are characterized more in detail.     

Beiträge zur Chemie der Trifluormethylquecksilber-Verbindungen

Contribution to the Chemistry of Trifluoromethylmercury (II) Compounds CF₃HgI (I) has been obtained in appreciable amount by a newly modified method, The reaction of I with silver salts AgX or AgY₂ (X = CN, NCO, SCN, SeCN, N₃, SCF₃, IO₃; Y = O, C₂O₄, NCN) gives corresponding CF₃HgX derivatives (II–VIII, XI, XII, XVII) mostly in good yield. The synthesis of (CF₃Hg)₂S (IX) has been attained by the reaction of I with Tl₂CS₃, while it gives with Ag₂O (CF₃Hg)₂O (VIII) instead of the hydroxide. VIII reacts in ethereal solution with H₂Se giving (CF₃Hg)₂Se (X). Stable CF₃HgN and (CF₃Hg)₂N derivatives (XIII–XVII) could only be obtained when at least one more substituent on N atom, which reduces its basicity, is present. I.r., ¹⁹F-n.m.r. and mass spectroscopic data for the prepared compounds have been reported.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXXVII. Zur Existenz von 1-Norbornylverbindungen des Wolframs und Molybdäns

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXXVII. About the Existence of 1-Norbornyl Compounds of Tungsten and Molybdenum Reactions of WCl₆, WCl₄, WO₂Cl₂, WOCl₄, MoCl₅, and MoO₂(acac)₂ with 1-Norbornyl lithium (1-NorLi¹)) are described. From WCl₆ and WCl₄ [(1-Nor)₂W]_n is formed, whereas in dependence of the solvent WO₂Cl₂ and WOCl₄ are transformed into the complexes Li₂[1-NorWOCl₄] · THF, Li[WOCl₄], Li[WO₂Cl₂], and Li₂[WO₂Cl₂]. MoCl₅ and MoO₂(acac)₂ are reduced with formation of Li[MoCl₅], Li[MoO₂(acac)₂] and Li₂[MoO₂(acac)₂]. — Stable (1-Nor)₄M-derivatives of molybdenum and tungsten, comparable those of 3d-metals (M = Ti? Co) seem not to exist.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XLI. Darstellung und Thermolyseprodukte von Methyltitanhalogeniden

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XLI. Preparation and Thermolysis Products of Methyl Titanium Halides (CH₃)_nTiX_{4 ? n} derivatives (X = Cl, Br, I) can be prepared by comproportionation reactions of tetramethyl titanium with titanium tetrahalides at deep temperature. Furthermore, the methyl titanium iodides are formed from tetramethyl titanium and iodine. Thermolysis of CH₃TiX₃ derivatives yields titanium(III) halides. At decomposition of the (CH₃)₂TiX₂ compounds in ether solution titanium(II) halides are obtained in a fine-distributed, very reactive form.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. 63. Darstellung und Kristallstruktur von Tetramethyltitan-tetrahydrofuran

Contributions to the Chemistry of Transition Metal Alkyl Compounds. 63. Preparation and Crystal Structure of Tetramethyltitanium Tetrahydrofuran Me₄Ti · 2THF 1 dissoziates partially in n-pentane. The formed Me₄Ti · THF 2 could be isolated. According to X-ray structure determination the molecules of 2 have a trigonalbipyramidal shape with the THF molecule in axial position.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XV. Bildung und Eigenschaften von Phenylvanadindichlorid

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XV Preparation and Properties of Phenyl Vanadium Dichloride Vanadium(IV) chloride reacts with diphenyl zinc forming extremely air sensitive, at room temperature stable phenyl vanadium dichloride. The diffuse reflectance spectrum indicates an octahedral structure of the vanadium compound which is to regard as a coordination polymer. – Diethyl ether causes a cleavage of the V – C bond with formation of a vanadium dichloride etherate.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XVIII. Darstellung und Eigenschaften von Vanadintetrabenzyl und von Benzyltantalchloriden

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XVIII. On the Preparation and Properties of Tetrabenzyl Vanadium and Benzyl Tantalum Chlorides Pure tetrabenzyl vanadium was isolated and characterized by elementary analyses, EPR and ¹H-NMR spectra, by hydrolysis and thermal decomposition. — Experiments for the preparation of tetra or pentabenzyl compounds of niobium and tantalum failed, but we could prepare C₆H₅CH₂TaCl₄, (C₆H₅CH₂)₂TaCl₃, and (C₆H₅CH₂)₃TaCl₂, the last two in form of bipyridyl complexes.     

Beiträge zur Chemie der Halogensilan-Addukte. XII. 1,10-Phenanthrolin-N-Oxid-Komplexe von Halogensilanen

On Perovskite Phases in the Systems AO? SE₂O₃? UO_2,x with A =Alkaline Earth Metal and SE = Rare Earths, La and Y. X. The Systems Ba₂CaUO₆? Ba₂CaUO₆? Ba₂Lu_0.67UO₆ and Ba₂SrUO₆? Ba₂Lu_0.67UO₆ In the systems Ba₂B_1?xLu_0,67x UO₆ with B^II = Ca, Sr at the B-rich side rhombic and at the Lu-rich side monoclinic perovskites are formed. The transition is discontinuous and accompanied by order-disorder phenomena.     

Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen. XCI. Dekamethylcyclotetrasilazan

Decamethylcyclotetrasilazane (I) was prepared starting with 1,3-dichloropentamethyldisilazane (II), 1.3-dichlorotetramethyldisilazane (III) and 1,3-bis-(methylamino)tetramethyldisilazane (IV). respectively, according to scheme 1, equ. (1), (2) and (3) in the text. (I) does not form, as given in the literature (equ. 4)⁵, by thermal transformation of bis(methylaminodimethylsilyl)-tetramethylcyclodisilazane (V); in this case exclusively – in equ. (2) and (3) only in side steps – the reaction products are a mixture of N-methylcyclotrisilazanes (scheme 2, VI–IX).     

Beiträge zur Chemie der Schwefelhalogenide. 7. Trifluormethyliodsulfan

Contributions to the Chemistry of Sulfur Halides. 7. Trifluoromethyliodosulfane The preparation of CF₃SI is reported. The molecule is characterized by vibrational, nuclear magnetic resonance, UV/VIS, and mass spectra. CF₃SI chemically behaves like the interhalogen compound ICl. At higher temperatures the compound completely decomposes in CF₃SSCF₃ and I₂.     

Beiträge zur Chemie der Silicium-Schwefel-Verbindungen. XLIII. Alkoholyse von Silicium-Schwefel-Verbindungen mit Alkoxyethanolen und 2-Mercaptoethanol

Contributions to the Chemistry of Silicon-Sulphur Compounds. XLIII. Alcoholysis Reaction of Silicon-Sulphur Compounds with Alkoxyethanols and 2-Mercaptoethanol The reactions of 2-alkoxyethanols und 2-mercaptoethanol with (RO)₃SiSH, (RO)₂Si(SH)₂, cyclo-[(t-BuO₂)SiS]₂, and SiS₂ were investigated. Besides of mixed esters of orthosilicic acid a new group of mixed trialkoxysilanethiols – (RO)₂(R′O)SiSH – was obtained. Informations about the hydrolytic splitting of the Si? S bond of these Si? S compounds were obtained by thiomercurimetric titration with HMB.     

Beiträge zur Chemie der Schwefelhalogenide. 14. Die Kinetik des Zerfalls von Diioddisulfan und Perfluormethyliodsulfan

Contribution to the Chemistry of Sulfur-Halogen Compounds. 14. Decomposition Kinetics of Diiododisulfane and Perfluoromethaneiodosulfane Due its bifunctional character, S₂I₂ decomposes by inter- as well as intramolecular iodine formation. A system of competing parallel and secondary reactions results. The main decomposition phase follows first order rate law and is strongly temperature dependent, on the other hand, perfluoromethaneiodosulfane decomposes obeying second order rate law, where K = 2.74 ± 0.03 × 10^?4 l mol^?1s^?1 at 40°C.