Synthesen und Eigenschaften von Tris(perfluoralkyl)arsen- und -antimon(III,V)-Verbindungen

Preparations and Properties of Tris(perfluoroalkyl) Arsenic and Antimony(III, V) Compounds As(R_f)₃ and Sb(R_f)₃ (R_f?C₂F₅, C₄F₉, C₆F₁₃) are prepared in good yields by the polar reactions of AsCl₃ and SbCl₃ with bis(perfluoroalkyl) cadmium compounds as colourless liquids or solids. The oxidation of As(C₂F₅)₃ and Sb(C₂F₅)₃ with XeF₂ gives the difluorides M(C₂F₅)₃F₂ (M?As, Sb). As(C₂F₅)₃Cl₂ is prepared by chlorination of As(C₂F₅)₃ in the presence of AlCl₃, while Sb(C₂F₅)₃Cl₂ is formed in the reaction of Sb(C₂F₅)₃F₂ with (CH₃)₃SiCl. During the reaction of M(C₂F₅)₃F₂ with (CH₃)₃SiBr ¹⁹F-NMR spectroscopic evidence is found for M(C₂F₅)₃ Br₂. The thermal decompositions of M(C₂F₅)₃F₂ mainly yield C₄F₁₀ and M(C₂F₅)F₂, while the thermal decompositions of M(C₂F₅)₃Cl₂ yield M(C₂F₅)₂Cl and C₂F₅Cl. The properties and spectroscopic data of the new compounds are described.     

Phosphanimin- und Phosphaniminato-Komplexe von Magnesium. Die Kristallstrukturen von [MgBr1,25I0,75(Me3SiNPMe3)(OEt2)], [MgI2(Me3SiNPMe3)2], [Mg2I2(Me3SiNPMe2CH2)Me3SiNPMe2CH2CH(Me)O)(OEt2)] und [MgBr(NPMe3)]4·C7H8

Phosphaneimine and Phosphoraneiminato Complexes of Magnesium. The Crystal Structures of [MgBr_1,25I_0,75(Me₃SiNPMe₃)(OEt₂)], [MgI₂(Me₃SiNPMe₃)₂], [Mg₂I₂(Me₃SiNPMe₂CH₂)(Me₃SiNPMe₂CH₂CH(Me)O)(OEt₂)], and [MgBr(NPMe₃)]₄ · C₇H₈ By reactions of the silylated phosphaneimine Me₃SiNPMe₃ with the Grignard reagents EtMgBr and MeMgI, respectively, the carbanionic phosphoraneiminato derivatives [XMg(CH₂PMe₂NSiMe₃)]_n (X ? Br, I) can be isolated as main products. The by-products of these reactions, [MgBr_1.25I_0.75(Me₃SiNPMe₃)(OEt₂)], [MgI₂(Me₃SiNPMe₃)₂] and [Mg₂I₂(CH₂PMe₂NSiMe₃)(O(Me)CHCH₂PMe₂NSiMe₃)(OEt₂)] were identified by crystal structure determinations. The phosphoraneiminato complex [MgBr(NPMe₃)]₄ · C₇H₈ with hetero cubane structure is formed by a metathesis reaction of [ZnBr(NPMe₃)]₄ with RMgBr (R ? Ph. Mes).     

Basische metalle: LII. Synthese von carbenoid- und ylidcobalt(III)-komplexen aus substitutionslabilen cobalt(I)-vorstufen

The cyclopentadienylcobalt(I) compounds C₅H₅Co(PMe₃)P(OR)₃ (R = Me, Et, Prⁱ) and C₅H₅Co(C₂H₄)L (L = PMe₃, P(OMe)₃, CO) are prepared by ligand substitution starting from C₅H₅Co(PMe₃)₂ and C₅H₅Co(C₂H₄)₂. Whereas the reaction of C₅H₅Co(PMe₃)P(OMe)₃ with CH₂Br₂ mainly gives [C₅H₅CoBr(PMe₃)P(OMe)₃]Br, the dihalogenocobalt(III) complexes C₅H₅CoX₂(PMe₃) (X = Br, I) are obtained from C₅H₅Co(CO)PMe₃ and CH₂X₂. Treatment of C₅H₅Co(CO)PMe₃ or C₅H₅Co(C₂H₄)PMe₃ with CH₂ClI at low temperatures produces a mixture of C₅H₅CoCH₂Cl(PMe₃)I and C₅H₅CoCl(PMe₃)I, which can be separated due to their different solubilities. The same reaction in the presence of ligand L gives the carbenoidcobalt(III) compounds [C₅H₅CoCH₂Cl(PMe₃)L]PF₆ in nearly quantitative yields. If NEt₃ is used as the Lewis base, the ylide complexes [C₅H₅Co(CH₂PMe₃)(PMe₃)X]PF₆ (X = Br, I) are obtained. The PF₆ salts of the dications [C₅H₅Co(CH₂PMe₃)(PMe₃)L]²⁺ (L = PMe₃, P(OMe)₃, CNMe) and [C₅H₅Co(CH₂PMe₃)(P(OMe)₃)₂]²⁺ are prepared either from [C₅H₅Co(CH₂PMe₃)(PMe₃)X]⁺ and L, or more directly from C₅H₅Co(CO)PMe₃, CH₂X₂ and PMe₃ or P(OMe)₃, respectively. The synthesis of C₅H₅CoCH₂OMe(PMe₃)I is also described.     

Estimation of average heat capacities of condensed phase transformation products in the Y−Ba−Cu−O system

A method of calculation of average heat capacities of phase transformation products of complex oxides is suggested. The method takes into account the physical state of products and the increase in the heat capacities of products due to the change of entropy at a phase transformation. Average heat capacities of products formed in a congruous melting of compounds (YCuO₂ and Y₄Ba₃O₉), in an incongruous melting of compounds (Y₂Cu₂O₅, BaCuO₂, BaCu₂O₂, Y₂BaCuO₅, YBa₂Cu₃O₇, YBa₂Cu₃O₆) and in a decomposition in a crystalline state of compounds (Y₂BaO₄, Y₂Ba₂O₅, Y₂Ba₄O₇, Ba₂CuO₃, Ba₃Cu₅O₈, YBa₂Cu_3.5O_7.5, YBa₂Cu₄O₈, YBa₂Cu₅O₉) was estimated by using three methods.     

Pentafluorophenylcompounds of polyvalent iodine

The oxidation of C₆F₅I by oxidizers containing positive chlorine was investigated with the intention to prepare pentafluorophenyliodine (III) compounds: C₆F₅IX₂, where X are halides or oxoderivatives. Using ClF, ClOCF₃, Cl₂/AlCl₃ or Cl₂O as oxidizers C₆F₅ IF₂, C₆F₅ I Cl₂ and C₆F₅I (OCl)₂ - all thermally unstable - could be prepared and characterized.In contrast to these compounds the perfluoroaromatic carboxylates: C₆F₅I [O(O)C R_F]₂ are crystalline solids thermally stable up to 200 °C. Single crystal investigations show T-coordinated iodine with significant secondary bonding between iodine and the keto oxygens. C₆F₅ IO-formed by hydrolysis of C₆F₅IX₂ - changes if stored at RT forming (C₆F₅)₂I IO₃.(C₆F₅)₂I⁺ - formation is also observed when C₆F₅ IO is heated in inert (C₆F₅I, C₆H₆, CCl₄ …), protic (H₂O, CH₃OH, …) and strong acidic (FSO₃H …) dilution medium.C₆F₅IO reacts with acids, acid anhydrides and acid halides as could be shown by the preparation of C₆F₅ ICl₂ and C₆F₅ ICl (NO₃).Starting with C₆F₅ IX₂ different preparative ways for (C₆F₅)₂ I⁺ - compounds were successful. Principly (C₆F₅)₂ IX - compounds decompose thermally forming C₆F₅I + C₆F₅X.C₆F₅ IX₄ - compounds can be obtained from C₆F₅ IF₄ which is the specific displacement product of IF₅ with Si (C₆F₅)₄. By nucleophilic displacement it is possible to prepare C₆F₅ IF₂O, C₆F₅ IO₂, C₆F₅ IO (OAc_F)₂ and C₆F₅ I [OC(CH₃)₂  C(CH₃)₂O]₂,wich are all white, thermally stable solids.For the fluorine-ligand-exchange we used silycompounds as reagents. If the ligand is oxidable by C₆F₅ I(V) a stepwise reduction via C₆F₅I(III) to C₆F₅I could be shown by NMR-measurements.     

Organometallic chemistry of the transition metals: XXXIII. Some new reactions of cyclopentadienyltetracarbonylniobium

Photolysis of C₅H₅Nb(CO)₄ with excess cycloheptatriene gives the dark brown tetrahapto complex C₅H₅Nb(CO)₂C₇H₈ but no C₅H₅NbC₇H₇ analogous to the corresponding reaction of C₅H₅V(CO)₄ with cycloheptatriene. Photolysis of C₅H₅Nb(CO)₄ with cyclooctatetraene gives the dark green tetrahapto complex C₅H₅Nb(CO)₂C₈H₈, the C₈H₈ ring in this complex remains fluxional below -86° C. Reaction of C₅H₅Nb(CO)₄ with I₂ gives re-brown C₅H₅Nb(CO)₃I₂ in which the carbonyl groups are relatively labile. Thus reaction of C₅H₅Nb-(CO)₃I₂ with (CH₃)₂PCH₂CH₂P(CH₃)₂ under ambient conditions results in the rapid replacement of two CO groups to give C₅H₅Nb(CO)[(CH₃)₂PCH₂CH₂ -P(CH₃)₂]I₂. Treatment of C₅H₅V(CO)₄ with I₂ at room temperature gives the carbonyl-free complex C₅H₅VI₂ with no evidence for any cyclopentadienyl-vanadium carbonyl iodide intermediates.     

Ruthenium NNN complexes with a 2‐hydroxypyridylmethylene fragment for transfer hydrogenation of ketones

Four NNN tridentate ligands L₁–L₄ containing 2‐methoxypyridylmethene or 2‐hydroxypyridylmethene fragment were synthesized and introduced to ruthenium centers. When (HOC₅H₃NCH₂C₅H₃NC₅H₇N₂) (L₂) and (HOC₅H₃NCH₂C₅H₃NC₆H₆N₃) (L₄) reacted with RuCl₂(PPh₃)₃, two ruthenium chloride products Ru(L₂)(PPh₃)Cl₂ ( 1 ) and Ru(L₄)(PPh₃)Cl₂ ( 2 ) were isolated, respectively. Reactions of (MeOC₅H₃NCH₂C₅H₃NC₅H₇N₂) (L₁) and (MeOC₅H₃NCH₂C₅H₃NC₆H₆N₃) (L₃) with RuCl₂(PPh₃)₃ in the presence of NH₄PF₆ generated two dicationic complexes [Ru(L₁)₂][PF₆]₂ ( 3 ) and [Ru(L₃)₂][PF₆]₂ ( 4 ), respectively. Complex 1 reacted with CO to afford product [Ru(L₂)(PPh₃)(CO)Cl][Cl]. The catalytic activity for transfer hydrogenation of ketones was investigated. Complex 1 showed the highest activity, with a turnover frequency value of 1.44 × 10³ h^?1 for acetophenone, while complexes 3 and 4 were not active.     

Reactions of metal carbonyl derivatives X. The synthesis and reactivity of some dinuclear derivatives of iron containing both bridging carbonyls and bridging phosphido or sulphido groups

The tertiary phosphine π-C₅H₅Fe(CO)₂P(C₆H₅)₂ reacts with a suspension of Fe₂(CO)₉ in benzene to give the dinuclear complex π-C₅H₅Fe₂P(C₆H₅)₂(CO)₆. This compound is also obtained by nucleophilic attack of [π-C₅H₅Fe(CO)₂]⁻ on Fe(CO)₄-[P(C₆H₅)₂Cl] in tetrahydrofuran. Irradiation of a benzene solution of π-C₅H₅Fe₂-P(C₆H₅)₂(CO)₆ with ultraviolet light affords π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅ which contains both a bridging carbonyl and a bridging phosphido group. The unstable bridged sulphido derivatives π-C₅H₅Fe₂SR(CO)₆ (R = CH₃ and C₆H₅) and π-C₅H₅Fe₂(t-C₄H₉S)(CO)₅ are similarly obtained employing π-C₅H₅Fe(CO)₂SR as ligand. The reactions of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅ with tertiary phosphines and phosphites yield three types of products depending on the reaction conditions and the ligand involved. Examples include π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄P(C₆H₅)₃, a mono-substituted derivative of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅, and π-C₅H₅Fe₂P(C₆H₅)₂(CO)₅P(C₂H₅)₃ and π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄[P(OCH)₃)₃]₂, mono- and bis-substituted derivatives of π-C₅H₅Fe₂P(C₆H₅)₂(CO)₆, respectively. The reaction of π-C₅H₅Fe₂P(C₆H₅₂(CO)₅ with (C₆H₅)₂PCH₂P(C₆H₅)₂ in benzene under reflux affords [π-C₅H₅Fe₂P(C₆H₅)₂(CO)₄](C₆H₅)₂PCH₂P(C₆H₅)₂ in which the ditertiary phosphine bridges two iron atoms.     

Solid phase reactivity of sodium oxosalts of manganese

The observed relationships are presented of the solid phase reactivity of the following salts: NaMnO₄, Na₂MnO₄, Na₃MnO₄, Na₄MnO₄, Na₂MnO₃, Na₂Mn₂O₅, Na₅MnO₄, Na₄Mn₂O₅, NaMnO₂, Na₄MnO₃, Na₂MnO₂ and Na₂Mn₂O₃.     

Untersuchung der Phasengleichgewichte in den Systemen Sb2O3?SO3?H2O und Bi2O3?SO3?H2O

Investigation of Phase Equilibria in the Systems Sb₂O₃? SO₃? H₂O and Bi₂O₃? SO₃? H₂O Phase equilibria in the systems Sb₂O₃? SO₃? H₂O and Bi₂O₃? SO₃? H₂O within the concentration range of 1 up to 98.5% H₂SO₄ at 100°C are studied. In the system Sb₂O₃? SO₃? H₂O crystallization fields of five compounds depending on the H₂SO₄ concentration were determined: 5Sb₂O₃ · Sb₂(SO₄)₃ · 3H₂O; 7Sb₂O₃ · 2Sb₂(SO₄)₃; 2Sb₂O₃ · Sb₂(SO₄)₃; Sb₂O₃ · Sb₂(SO₄)₃ and Sb₂(SO₄)₃. The obtained compounds are identified by chemical and derivatographic analysis.     

The reactivity of tributyltin oxygen compounds with CCl4: Implications for its use as an extraction/reaction solvent

A variety of tributyltin oxygen compounds,(nC₄H₉)₃SnOX where X = Sn(nC₄H₉)₃, C₂H₅, nC₄H₉, C₈H₁₇, CH₂C₆H₅, COCH₃, have been studied in refluxing CCI₄. A reaction was observed to occur where X = C₂H₅, C₄H₉, C₈H₁₇, CH₂C₆H₅, leading to the formation of (nC₄H₉)₃SnCl, CHCl₃ and an aldehyde. Possible reaction pathways are suggested. These reactions have implications for the use of CCl₄ as an extraction/reaction solvent.     

Darstellung und Eigenschaften von Kupfer(II)-Hypophosphit

Thermal Behaviour of the Mixtures Na₂S? P₄S₁₀ and Na₄Ge₄S₁₀? P₄S₁₀ of the System Na₂S? GeS₂? P₄S₁₀ The mixtures of Na₂S? P₄S₁₀ and Na₄Ge₄S₁₀? P₄S₁₀ were investigated by DTA and DSC. In the system Na₂S? P₄S₁₀ the congruently melting compounds Na₃PS₄ and (NaPS₃)_x and the peritectic phase Na₄P₂S₇ were found. The IR-spectra are given. Glassy, anhydrous and hydrated Na₄Ge₄S_l0 were prepared and thermochemically characterized. The section Na₄Ge₄S₁₀? P₄S₁₀ is not quasibinary, the mixed cage-anion Ge_4?xP_xS₁₀^(4?x)? thus cannot be prepared by heating and annealing mixtures of Na₄Ge₄S₁₀ and P₄S₁₀.     

Alcoholysis of (2-methoxycarbonyl)ethyltin compounds

Under acid or base catalysis, di(2-alkoxycarbonylethyl)tin dichlorides of various R groups, (ROCOCH₂CH₂)₂SnCl₂, can be prepared conveniently in high yield by alcoholysis of (CH₃OCOCH₂CH₂)₂SnCl₂ in various alcohols, ROH (R = C₂H₅, C₄H₉, iso-C₄H₉, C₅H₁₁, C₆H₅CH₂, C₄H₉CH(C₂H₅)CH₂). When excess acid or base is present in the aqueous solution, (ROCOCH₂CH₂)₂SnCl₂ eliminate ROH and precipitate as C₆H₈O₄Sn regardless of the R group. C₆H₈O₄Sn can be converted into various (ROCOCH₂CH₂)₂SnCl₂ derivatives on dissolving in alcoholic HCl solutions.     

Basische metalle : XXXV. Neutrale rhodium-carbenoid-verbindungen und ihre umwandlung in kationische und neutrale rhodium-ylid-komplexe

The reaction of C₅H₅Rh(PMe₃)C₂H₄ or C₅H₅Rh(PMe₃)CO with CH₂I₂ affords the compound C₅H₅RhCH₂I(PMe₃)I from which stable cationic ylide-rhodium complexes [C₅H₅RhCH₂L(PMe₃)I]X (L = PPh₃, PPrⁱ₃, AsPh₃, SMe₂, NEt₃; X = I, PF₆) are prepared. In the presence of NEt₃, C₅H₅RhCH₂I(PMe₃)I also undergoes isomerisation to yield C₅H₅Rh(CH₂PMe₃)I₂. C₅H₅RhCH₂I(PMe₃)I reacts with NaOMe and NaSMe to give C₅H₅RhCH₂OMe(PMe₃)I and C₅H₅RhCH₂SMe(PMe₃)SMe, respectively.     

Synthesis and mesomorphism of mixed ether-ester tail triphenylene discotic liquid crystals with long alkyloxy peripheral chains

Symmetrical and asymmetrical triphenylene discotic liquid crystals with two kinds of different peripheral chains, sym-TP(OC₁₁H₂₃)₃(O₂CR)₃ and asym-TP(OC₁₁H₂₃)₃(O₂CR)₃, (R=CH₂OC₂H₅, CH₂OC₃H₇, CH₂OC₄H₉, CH₂OC₅H₁₁, C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, C₇H₁₅) were synthesized. Their thermotropic liquid crystalline properties were studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The results showed that the asymmetrical compounds had higher melting and clearing points than that of their corresponding symmetrical compounds. For the same series of compounds, TP(OC₁₁H₂₃)₃(O₂CR)₃, their melting points decrease and clearing points increase gradually with the lengthening of ester chains. Most of the β-oxygen containing esters of triphenylene derivatives, TP (OC₁₁H₂₃)₃(O₂CR)₃, (R=CH₂OC₂H₅, CH₂OC₃H₇, CH₂OC₄H₉, CH₂OC₅H₁₁), symmetrically or asymmetrically attached on triphenylene cores, have higher melting and clearing points than those of triphenylene derivatives, TP(OC₁₁H₂₃)₃(O₂CR)₃, (R=C₄H₉, C₅H₁₁, C₆H₁₃, C₇H₁₅), with the same length of peripheral chains. The triphenylene derivatives with longer peripheral chains have shown mesophase at room temperature. __________ Translated from Chemical Research and Application, 2007, 19(10) (in Chinese)     

Komplexe mit kohlenstoffsulfiden und -seleniden als liganden: XIII. Reaktionen der metall-basen C5H5M(PR3)2 und C5H5M(PR3)L (M = Co,Rh) mit CSSe und CSe2: synthese und eigenschaften von cyclopentadienylcobalt- und rhodium- komplexen mit CS,CSe, CSSe,CSe2, CSSe22−, CSe32−, C2S2Se22−- und C2Se42−- als liganden

C₅H₅Co(PMe₃)₂ (I) reacts with CSSe to give C₅H₅Co(η²-CSSe)PMe₃ (IV) and C₅H₅Co(CS)PMe₃ (V). The thiocarbonyl complex V is formed in an almost quantitative yield by Se abstraction from IV and PPh₃. The corresponding compounds C₅H₅Co(CS)PMe₂Ph (VII) and C₅H₅Co(CS)[P(OMe)₃] (VIII) are obtained as the main products directly from CSSe and C₅H₅Co(PMe₂Ph)₂ or C₅H₅Co[P(OMe)₃]₂. In the reaction of C₅H₅Co(PR₃)₂ (PR₃ = PMe₃, PMe₂Ph) with CSe₂, the carbon diselenide complexes C₅H₅Co(η²-CSe₂)PMe₃ (XI) and C₅H₅Co(η²-CSe₂)PMe₂Ph (XIV) are formed. XI reacts with PPh₃ to give C₅H₅Co(CSe)PMe₃ (XII). Cyclopentadienylcobalt compounds containing CSSe₂^2?, CSe₃^2? and C₂Se₄^2? as ligands are isolated as side products in the; reactions of C₅H₅Co(PR₃)₂ and C₅H₅Co(CO)PR₃ (PR₃ = PMe₃, PMe₂Ph) with CSSe and CSe₂, respectively. Displacement of ethylene from C₅H₅Rh(C₂H₄)PMe₃ by CSSe yields the complex C₅H₅Rh(η²-CSSe)PMe₃ (XVIII) which reacts with PPh₃ to give C₅H₅Rh(CS)PMe₃ (XIX) and with excess CSSe to give C₅H₅RhC₂S₂Se₂(PMe₃) (XX). Besides small amounts of C₅H₅Rh(η²CSSe)PMe₂Ph (XXI), the corresponding metallaheterocycle C₅H₅RhC₂S₂Se₂(PMe₂Ph) (XXII) is formed as the main product from C₅H₅Rh(C₂H₄)PMe₂Ph and CSSe.     

Die komplexchemie polyfunktioneller liganden : XXVIII. Über die selektive spaltung von arsenphenyl-bindungen mit jodwasserstoff in nichtwässrigen systemen

The phenylalkyl arsines (CH₃)₂AsC₆H₅, CH₃As(C₆H₅)₂, C₂H₅As(C₆H₅)₂, (CH₂)_n [As(C₆H₅)₂]₂ (n = 1, 2), and C[CH₂As(C₆H₅)₂]₄ react with liquid or gaseous HI in nonaqueous solvents by selective cleavage of the arsenicphenyl bonds yielding (CH₃)₂AsI, CH₃AsI₂, C₂H₅AsI₂, (CH₂)_n(AsI₂)₂ and C(CH₂AsI₂)₄. The latter forms the tetradentate ligand C[CH₂As(CH₃)₂]₄ with CH₃MgI. The electron impact mass spectra of these compounds show clear fragmentation patterns resulting mainly from the formation of fragments with AsAs bonds or (As)_n clusters (_n = 3, 4). From CH₃AsI₂ and C₂H₅AsI₂ the iodine-free cycloarsines (AsCH₃)₃, (AsC₂H₅)₃, (AsC₂H₅)₄, As₃(C₂H₅)₂CH₃ and As₄(C₂H₅)₃CH₃ are formed by thermal secondary reactions in the high temperature inlet systems of the mass spectrometer. The fragmentations of the cycloarsines and the other compounds are discussed. The infrared spectral absorptions of all the alkyl iodoarsines can be completely assigned in the range of 4000 – 250 cm^?1. The IR data of C₂H₅AsI₂ indicate the existence of trans and gauche rotational isomers.     

Schwingungsspektren von β-P4S5 und P4S7

Vibrational Spectra of β-P₄S₅ and P₄S₇ The vibrational spectra of the solid and liquid cage compounds β-P₄S₅ and P₄S₇ have been recorded. The assignments of the frequencies are proposed mainly based on polarization data. β-P₄S₅ decomposes during melting into P₄S₃ α-P₄S₇ and β-P₄S₆. Molten α-P₄S₇ dissociates to some extent into β-P₄S₆ and sulphur. An association of β-P₄S₆ with α-P₄S₇ is discussed for the molten state. All reactions in molten P₄S₇ are reversible.     

Untersuchungen zum chemischen Transport der Vanadiumoxide V2O5, V3O7 und V6O13

Chemical transport of the vanadium oxides V₂O₅, V₃O₇, and V₆O₁₃ The suitability of water and some halogenating transport agents (NH₄Cl, NH₄Br, I₂) for the chemical transport (temperature gradient 850/750 K) of V₂O₅, V₃O₇, and V₆O₁₃ has been investigated. Transport rates for V₂O₅ and V₆O₁₃ could be measured and reproduced. The best transport agent for V₂O₅ is NH₄Cl or H₂O. For V₃O₇ a combination of the transport agents I₂/H₂O give the best results and for V₆O₁₃ the combination of NH₄Br/H₂O was most appropriate.     

Synthesis and characterization of new sulfide aggregates of the type [{Pt2(μ3-S)2(P-P)2}M(C6F5)2] (M=Ni, Pd, Pt; P-P=2PPh3, 2PMe2Ph, dppf)

The reaction of [Pt₂(μ-S)₂(P-P)₂] (P-P=2PPh₃, 2PMe₂Ph, dppf) [dppf=1,1^′-bis(diphenylphosphino)ferrocene] with cis-[M(C₆F₅)₂(PhCN)₂] (M=Ni, Pd) or cis-[Pt(C₆F₅)₂(THF)₂] (THF=tetrahydrofuran) afforded sulfide aggregates of the type [{Pt₂(μ₃-S)₂(P-P)₂}M(C₆F₅)₂] (M=Ni, Pd, Pt). X-ray crystal analysis revealed that [{Pt₂(μ₃-S)₂(dppf)₂}Pd(C₆F₅)₂], [{Pt₂(μ₃-S)₂(PPh₃)₂}Ni(C₆F₅)₂], [{Pt₂(μ₃-S)₂(PPh₃)₂}Pd(C₆F₅)₂] and [{Pt₂(μ₃-S)₂(PMe₂Ph)₂}Pt(C₆F₅)₂] have triangular M₃S₂ core structures capped on both sides by μ₃-sulfido ligands. The structural features of these polymetallic complexes are described. Some of them display short metal-metal contacts.