[WCl4(Me3Si?CC?SiMe3)]2 Synthese,IR-Spektrum und Kristallstruktur

[WCl₄(Me₃Si? C?C? SiMe₃)]₂. Synthesis, I.R. Spectrum, and Crystal Structure The title compound is obtained from tungsten hexachloride and bis-trimethylsilyl acetylene in the presence of C₂Cl₄ in dichloro methane, forming green crystals. The complex is characterized by the mass spectrum, the i.r. spectrum, and by a structural analysis with the aid of X-ray diffraction data. [WCl₄(Me₃Si? C?C? SiMe₃)]₂ crystallizes triclinic in the space group P1 with one dimeric formula unit per unit cell (2 231 observed, independent reflexions, R = 4.6%). The cell dimensions are a = 928, b = 938, c = 1 080 pm; α = 115.3°, β = 91.9°, γ = 100.0°. The complex forms centrosymmetric dimers, the units being linked by chloro bridges of bond lengths W? Cl 244 and 272 pm. The trans-position to the long W? Cl bridge is occupied by the acetylene ligand which is bonded side-on with identical W? C bond lengths of 203 pm. Together with the three terminal chlorine ligands (mean W? Cl distance 231 pm) the tungsten atom achieves coordination number seven.     

Dichloracetylen als stabiler Komplexligand Die Kristallstruktur von PPh4[WCl5(C2Cl2)] · 0,5 CCl4

Dichloro Acetylene as Complex Ligand. Crystal Structure of PPh₄[WCl₅(C₂Cl₂)] · 0.5 CCl₄ Tungsten hexachloride and dichloro acetylenediethyletherate react in boiling CCl₄ in presence of C₂Cl₄ as reducing agent forming [Et₂O · WCl₄(C₂Cl₂)]. In vacuo the complex looses ether giving the dichloro acetylene complex [WCl₄(C₂Cl₂)]₂ which is dimeric with chloro bridges. Both complexes react with tetraphenylphosphonium chloride to form PPh₄[WCl₅(C₂Cl₂)] which is equally prepared by ligand exchange of PPh₄[WCl₅(C₂I₂)] with silver chloride. All dichloro acetylene complexes are red to brown crystalline solids sensitive to moisture, and are thermally and mechanically very stable compared with the highly explosive dichloro acetylene. The compounds are characterized by their i.r. spectra; [Et₂O · WCl₄(C₂Cl₂)] was additionally investigated by ¹³C-nmr spectroscopy. PPh₄[WCl₅(C₂Cl₂)] · 0.5 CCl₄ formes dark brown crystals; according to the structural investigation by X-ray diffraction methods the compound crystallizes orthorhombic in the space group Pbca with 8 formula units per unit cell (1317 observed, independent reflexions, R = 0.049). The cell dimensions are a = 1702 pm, b = 1675 pm and c = 2228 pm. The compound consists of [WCl₅(C₂Cl₂)]? anions and PPh₄⊕ cations including CCl₄ molecules without bonding interactions. The tungsten atoms are seven-coordinated by five chlorine atoms and two carbon atoms. The dichloro acetylene ligand is bonded symmetrically side-on and has a C? C bond length of 128 pm. The W? C distances are 201 pm, the four equatorial Cl atoms have W? Cl bond lengths of 234 pm whereas the chlorine atom in trans-position to the W? C₂ group is situated in a distance of 244 pm.     

Diiodacetylenkomplexe von Wolfram(IV). Die Kristallstruktur von PPh4[WCl5(C2l2)] · 0,5 CH2Cl2

Diiodoacetylene Complexes of Tungsten(IV). Crystal Structure of PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ Tungsten hexachloride and diiodoacetylene react in CCl₄ solution forming [WCl₄(I? C?C? I)]₂ which has a dimer structure with chloro bridges. In CH₂Cl₂, it reacts with PPh₄Cl yielding PPh₄[WCl₅(I? C?C? I)] · 0.5 CH₂Cl₂. In both compounds the C₂I₂ ligands attain a marked increase in thermal stability by their side-one coordination to the tungsten atoms. The crystal structure of the PPh₄^⊕ salt was determined with X-ray diffraction data (3879 observed reflexions, R = 0.050). PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ crystallizes in the space group P2₁/n with 8 formula units per unit cell. The lattice constants are a = 1723.0, b = 1681.2, c = 2214.6 pm and β = 94.38°. There are two crystallographically independent [WCl₅(C₂I₂)]^? ions which differ only slightly from one another. The C₂I₂ ligand has a staggered arrangement relative to the W? Cl groups, with C? C bond lengths of 127 pm. The infrared spectra are discussed.     

Chlorthionitrenkomplexe des Wolframs Die Kristallstruktur von [WCl4(NSCl)]2

Chlorothionitrene Complexes of Tungsten. Crystal Structure of [WCl₄(NSCl)]₂ Tungsten hexachloride reacts with trithiazyl chloride, (NSCl)₃, yielding the chlorothionitrene complex [WCl₄(NSCl)]₂, from which AsPh₄[WCl₅(NSCl)] can be obtained by reaction with AsPh₄Cl. Both complexes are characterized by their i.r. spectra. The crystal structure of [WCl₄(NSCl)]₂ was determined and refined with X-ray diffraction data (1059 reflexes, R = 0.055). It crystallizes in the monoclinic space group P2₁/n with the lattice constants a = 1523, b = 904, c = 583 pm and β = 91.35°. In the unit cell there are two centrosymmetric [WCl₄(NSCl)]₂ molecules in which the W atoms are linked via two chloro bridges; short and long W? Cl distances (244 and 265 pm) alternate in the W₂Cl₂ ring, the NSCl groups are found in the trans positions to the longer W? Cl bonds. The WNS bond angle (175°) and short bond distances correspond to a formulation .     

Über die Reaktion von 2,2-Dimethylpropylidinphosphan mit Wolframhexachlorid; die Kristallstrukturen von [(Cl3PO)WCl4(H9C4?CC?C4H9)] und [(H5C6)4As][WCl6]

Reaction of 2,2-Dimethylpropylidynephosphane with Tungsten Hexachloride as well as the Crystal Structures of [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)] and [(H₅C₆)₄As][WCl₆] The reaction of 2,2-dimethylpropylidynephosphane, (CH₃)₃C? C?P|, with tungsten hexachloride suspended in POCl₃ results, with oxidation of the phosphorus atom, in 2,2,5,5-tetramethylhex-3-yne. This compound reacts with tungsten tetrachloride simultaneously formed to give the alkyne complex [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)], which is dark green in colour. A small amount of tungsten hexachloride is reduced merely to tungsten pentachloride; after the addition of tetraphenyl arsonium chloride it can be isolated as [(H₅C₆)₄As][WCl₆]. For this compound, a new and very simple synthesis from WCl₆, [(H₅C₆)₄As]Cl and C₂Cl₄ as reducing agent is described. The structure of [(Cl₃PO)WCl₄(H₉C₄? C?C? C₄H₉)] has been determined from X-ray diffraction data (R = 5.8%). The complex crystallizes in the monoclinic space group P2₁/n with: {a = 1510; b = 1517; c = 849 pm; β = 93.1°; Z = 4}. The tungsten atom is sevenfold coordinated by four equatorial chlorine atoms, by the C°C group of the acetylene ligand and by the oxygen atom of the POCl₃ molecule in trans position. The bulky acetylene ligand which is nearly symmetrically bound shifts the chlorine atoms towards the solvated POCl₃ molecule so that no common plane with the tungsten atom is possible. With 130 pm the C°C bond length of the 2,2,5,5-tetramethyl-3-yne ligand corresponds to a C°C double bond. The i.r. spectrum of [(H₅C₆)As][WCl₆] shows two WCl₆ strectching vibrations and therefore proves a reduction of octahedral symmetry. In agreement with the results of a crystal structure determination (space group P4/n; a = 1301; c = 780 pm; Z = 2.7%) the [WCl₆]^?-anion has nearly exact C_4V symmetry with somewhat shorter W? Cl bond lengths parallel to the fourfold axis of rotation.     

Tribrom-methylnitren-Komplexe des Wolframs Die Kristallstruktur von PPh3Me[WBr5(NCBr3)]

Tribromomethylnitrene Complexes of Tungsten. Crystal Structure of PPh₃Me[WBr₅(NCBr₃)] Tungsten hexabromide reacts with BrCN in boiling bromine under formation of the BrCN adduct of tribromomethylnitrene tungsten, [BrCN? WBr₄(NCBr₃)]. This reacts with triphenylmethylphosphonium bromide in dibromomethane forming the tribromomethylnitrene pentabromowolframate, PPh₃Me[WBr₅(NCBr₃)]. Both compounds form brown-black, moisture sensitive crystal powders that were characterized by their IR spectra. The crystal structure of PPh₃Me[WBr₅(NCBr₃)] was determined by X-ray diffraction (3 664 observed reflexions, R = 0.066). Crystal data: a = 1 401.6, b = 1 243.3, c = 884.6 pm, α = 90.82, β = 110.74, γ = 90.67°, space group P1 , Z = 2. The compound consists of PPh₃Me^⊕ cations and [WBr₅(NCBr₃)]^? anions in which the tungsten atoms have a distorted octahedral coordination by five bromine atoms and the N atom of the nitrene ligand. The WN bond length of the nitrene ligand (175 pm) corresponds approximately to a triple bond; the W?N? C group is linear and shows a strong trans effect.     

Diphenylacetylen-Komplexe von Niob,Molybdän,Wolfram und Rhenium Die Kristallstruktur von [NbCl3(Ph?CC?Ph)]4

Diphenylacetylene Complexes of Niobium, Molybdenum, Tungsten, and Rhenium. Crystal Structure of [NbCl₃(Ph? C?C? Ph)]₄ Syntheses and i.r. spectra of the following diphenylacetylene complexes are reported: The chloro complexes 1, 2, 4, 7 and 8 are formed in the pentachlorides of niobium, molybdenum, rhenium, and tungsten hexachloride, respectively, with diphenyl acetylene. The bromo and iodo complexes 3, 5 and 6 are obtained by halogen exchange with boron halides, and the derivatives 9, 10 and 11 are obtained by reactions of PPh₄Cl or AsPh₄Cl and PPh₃ with the corresponding starting materials. The crystal structure of 1 was determined by the aid of X-ray diffraction data (R = 5.9% for 1548 independent, observed reflexions). The complex crystallizes triclinic in the space group P1 with one tetrameric molecule [NbCl₃(Ph? C?C? Ph)]₄ per unit cell. The cell dimensions at 20°C are a = 1074 pm, b = 1390 pm, c = 1299 pm, α = 104.3°, β = 108.0°, γ = 108.7°. 1 occurs as a centrosymmetric tetramer, which can be regarded as a distorted double hexahedron with two corners missing. Association is effected by chloro bridges in which the chlorine atoms have coordination number two and three. The diphenylacetylene ligands are bonded to the niobium atoms side-on with almost equal Nb? C bond lengths of average value 205 pm. Thus the Nb atoms achieve coordination number seven.     

Diphenyl-diacetylen-Komplexe von Molybdän(IV) und Wolfram(IV). Die Kristallstrukturen von PPh4[WCl5(Ph?CC?CC?Ph)] · CCI4 und von PPh4[WCl5(Ph?CC?C(Br)C(Br)?Ph)] · CCl4

Diphenyldiacetylene Complexes of Molybdenum (IV) and Tungsten (IV). Crystal Structures of PPh₄[WCl₅(Ph? C?C? C?C? Ph)] · CCl₄ and PPh₄[WCl₅(Ph? C?C? C(Br)?C(Br)? Ph)] · CCl₄ Syntheses and i.r. spectra of the following diphenyldiacetylene complexes are reported: [MoCl₄(Ph? C?C? C?C? Ph)]₂( 1 ), [WCl₄(Ph? C?C? C?C? Ph)]₂ ( 2 ), PPh₄[WCl₅(Ph? C?C? C?C? Ph)] · CCl₄ ( 3 ). 1 is formed in the reaction of MoCl₅ with excess diphenyldiacetylene. 2 is prepared from WCl₆ and excess diphenylacetylene with additional C₂Cl₄ as a reducing agent. Reaction of 2 with PPh₄Cl in CH₂Cl₂ solution in the presence of CCl₄ yields 3 . The complexes contain one of the acetylene functions bonded in a metallacyclopropene ring; the metal atoms are seven-coordinated. 2 reacts with bromine to from the dibromide [WCl₄(Ph? C?C? C(Br)? Ph)]₂ (4). In CH₂Cl₂ solution and in presence of ccl₄ 4 is turned into the ionic complex PPh₄[Ph? C?C? C(Br)? Ph] · CCl₄ (5) by PPh₄Cl. The complexes 3 and 5 are characterized by structural analyses on the basis of X-Ray diffraction data. 3 crystallized monoclinic in the space group p2₁/n with four formula units per unit cell (2623 observed, independent reflexions, R = 5.4%). 5 crystallized in the same space group, set P2₁/c, the unit cell containing four formula units (2537 observed, independent reflexions, R = 5.4%). Both complexes consist of tetraphenylphosphonium cations and anions, in which the tungsten atoms are coordinated by five chlorine and two carbon atoms, the latter bonding side-on, in an approximately symmetrical way. In addition the lattices contain one molecule CCl₄ per formula unit. The acetylene ligand causes a strong trans-effect. As a result the W? Cl bond lengths in trans-position are by 10 pm longer than those in cis-position. Bromination of the second acetylene function of 3 leads to addition in trans-position (5).     

(PPh4)2[MoN(N3)3Cl]2; Synthese,IR-Spektrum und Kristallstruktur

(PPh₄)₂[MoN(N₃)₃Cl]₂; Synthesis, IR Spectrum, and Crystal Structure The title compound is formed in the reaction of molybdenum (II) benzoate with trimethylsilyl azide and PPh₄Cl in dichloro methane forming dark red single crystals. A PPh₃Me⊕ salt of the ion [MoN(N₃)₃Cl]₂^2? is obtained from (PPh₃Me)₂MoNCl₄] treated with silver azide in CH₂Cl₂ suspension. The solvent CH₂Cl₂ participates in both reactions as oxidizing agent. (PPh₄)₂[MoN(N₃)₃Cl₂ is characterized by a structural analysis based upon X-ray data: space group P1 , Z = 1, a = 1050.7 pm; b = 1185.4 pm; c = 1190.8 pm; α = 98.90°; β = 106.87°; γ = 103.97° (4505 independent, observed reflexions, R = 0.039). The compound consists of PPh₄⊕ cations and centrosymmetric anions [MoN(N₃)₃Cl₂^2? in which the molybdenum atoms are bridged by the N_α atoms of two azide groups; the resulting Mo? N bond lengths are 208 pm and 260 pm. In trans position to the long Mo? N bond the terminal nitrido ligand is situated, the Mo?N distance of 164 pm corresponds to a triple bond. Two terminal azido ligands and the chloro ligand are filling up the coordination sphere of the molybdenum atoms to a coordination number of six. The i.r. spectrum is reported and assigned.     

Die Kristallstrukturen von [ReCl4(PhCCPh)]2 · 2 CH2Cl2 und von PPh4[ReOCl4]

Crystal Structures of [ReCl₄(PhC?CPh)]₂ · 2 CH₂Cl₂ and PPh₄[ReOCl₄] Single crystals of [ReCl₄(PhC?CPh)]₂ · 2 CH₂Cl₂ were obtained by chilling dilute solutions of the solvate [ReCl₄(PhC?CPh)POCl₃] in CH₂Cl₂. PPh₄[ReOCl₄] was formed by the reaction of the diphenyl acetylene complex [ReCl₅(PhC?CPh)] with PPh₄Cl · H₂O in CH₂Cl₂ solution. [ReCl₄(PhC?CPh)]₂ · 2 CH₂Cl₂: space group P2₁/c, Z = 2, 2244 observed independent reflexions, R = 0.038. Lattice parameters (19°C): a = 987.2 pm; b = 1533.9 pm; c = 1193.8 pm; β = 90.17° The compound forms centrosymmetrical dimeric molecules with ReCl₂Re bridges with Re? Cl distances of 241.2 and 267.6 pm. The longer Re? Cl bond is situated in trans-position to the equatorial, side-on coordinated diphenyl acetylene ligand with mean Re? C distances of 200 pm. PPh₄[ReOCl₄]: space group P4/n, Z = 2, 1487 observed, independent reflexions, R = 0.047. Lattice parameters (19°C): a = b = 1272.0 pm; c = 771.3 pm. The compound crystallizes in the AsPh₄[RuNCl₄] type; it consists of [ReOCl₄]^? anions and PPh₄⁺ cations. The anions are tetragonal with C_4v symmetry and bond lengths Re? O = 165.4 pm and Re? Cl = 232.6 pm; the bond angle OReCl is 106.7°.     

Ein- und zweikernige Dinitrosylkomplexe von Molybdän und Wolfram. Die Kristallstrukturen von (PPh3Me)2[WCl4(NO)2], (PPh3Me)2[MoCl3(NO)2]2 und von (PPh3Me)2[WCl3(NO)2]2

Mono- and Binuclear Dinitrosyl Complexes of Molybdenum and Tungsten. Crystal Structures of (PPh₃Me)₂[WCl₄(NO)₂], (PPh₃Me)₂[MoCl₃(NO)₂]₂, and (PPh₃Me)₂[WCl₃(NO)₂]₂ The complexes (PPh₃Me)₂[MCl₄(NO)₂] (M = Mo, W), and (PPh₃Me)₂[MCl₃(NO)₂]₂, respectively, are prepared by reactions of the polymeric compounds MCl₂(NO)₂ with triphenylmethylphosphonium chloride in CH₂Cl₂, forming green crystals. According to the IR spectra the nitrosyl groups are in cis-position in all cases. The tungsten compounds as well as (PPh₃Me)₂[MoCl₃(NO)₂]₂ were characterized by structure determinations with X-ray methods. (PPh₃Me)₂[WCl₄(NO)₂]: space group C2/c, Z = 4. a = 1874, b = 1046, c = 2263 pm, β = 119.99°. Structure determination with 3492 independent reflexions, R = 0.057. The compound consists of PPh₃Me^⊕ ions, and anions [WCl₄(NO)₂]^2? with the nitrosyl groups in cis-position (symmetry C_2v). (PPh₃Me)₂[WCl₃(NO)₂]₂: Space group C2/c, Z = 4. Structure determination with 2947 independent reflexions, R = 0.059. (PPH₃Me)₂[MoCl₃(NO)₂]₂: Space group P1 , Z = 1. a = 989, b = 1134, c = 1186 pm; α = 63.25°, β = 80.69°, γ = 69.94°. Structure determination with 3326 independent reflexions, R = 0.046. The compounds consist of PPh₃Me^⊕ ions, and centrosymmetric anions [MCl₃(NO)₂]₂^2?, in which the metal atoms are associated via MCl₂M bridges of slightly different lengths. One of the NO groups is in an axial position, the other one in equatorial position (symmetry C_2h).     

Synthese und Kristallstrukturen der Wolfram(VI)-Alkin-Komplexe [W2(O)(OMe)6(Et?Se?CC?Se?Et)2] und Li[W(OMe)5(Et?Te?CC?Te?Et)]

Synthesis and Crystal Structures of the Tungsten(VI)-alkyne Complexes [W₂(O)(OMe)₆(Et? Se? C?C? Se? Et)₂] and Li[W(OMe)₅(Et? Te? C?C? Te? Et)] The title compounds have been prepared by reactions of lithium methanolate with [WCl₄(Et? Se? C?C? Se? Et)(THF)] and [WCl₄(Et? Te? C?C? Te? Et)(THF)], respectively, in diethylether suspensions. Both complexes were characterized by crystal structure determinations. [W₂(O)(OMe)₆(Et? Se? C?C? Se? Et)₂]: Space group P1 , Z = 2, structure determination with 4 320 observed unique reflections, R = 0.041. Lattice dimensions at ?70°C: a = 949.3, b = 1 225.3, c = 1 285.0 pm, α = 82.48°; γ = 82.44°; β = 81.44°. The tungsten atoms are bridged by three μ₂-O-atoms of the OMe groups; the alkyne ligands are coordinated side-on in a metallacyclopropene-like fashion. Li[W(OMe)₅(Et? Te? C?C? Te? Et)]: Space group P1 , Z = 2, structure determination with 9 381 observed unique reflections, R = 0.038. Lattice dimensions at ?70°C: a = 983.4, b = 1606.9, c = 1971.5 pm, α = 66.09°, β = 84.29°, γ = 79.83°. The lithium ions link the [W(OMe)₅(Et? Te? C?C? Te? Et)]^? anions to a trimeric ion ensemble via the O atoms of three OMe groups of each anion.     

Komplexkatalyse. XIX. Zur Synthese von Nitrosylkomplexen des Wolframs und deren Eignung als Präkatalysatoren für die Olefinmetathese

Complex Catalysis. XIX. Synthesis of Nitrosyl Complexes of Tungsten and their Usefulness as Precatalysts for Olefin Metathesis Nitrosylating reduction of WCl₆ with NO leads to WCl₃(NO)₄ that on addition of different donor ligands L yields complexes of the types WCl₃(NO)L₂ (L = OOh₃, HMPT, pyridine) and WX₂(NO)₂ L₂ (L = PPh₃, X = Cl; XL = acac) or mixtures of products (L = Dipy, RCN, Et₄NCl), respectively. Whereas by carbonylation of WCl₃(NO)(OPPh₃)₂ in the presence of EtAlCl₂ only chloro carbonyl tungsten complexes are formed, the reaction of W(CO)₆ with NOAlCl₄ and subsequent addition of PPh₃ gives, in analogy to molybdenum, the nitrosyl carbonyl complexes W(NO)(CO)₄(AlCl₄) and WCl(NO)(CO)₂(PPh₃)₂. All the nitrosyl tungsten complexes in combination with EtAlCl₂ catalyze the metathesis of pent-2-ene, however, with a significantly lower activity than the corresponding nitrosyl molybdenum systems.     

3-Chloro-1,2,3,4-tetraphenylcyclobutenyl-Ennea-chloro-μ-Oxo-di-Niobat(V),[C4Cl(Ph)4]⊕[Nb2OCl9]⊖ Synthese und Kristallstruktur

3-Chloro-1,2,3,4-tetraphenylcyclobutenyl-Ennea-chloro-μ-Oxo-di-Niobate(V), [C₄Cl(Ph)₄]^⊕[Nb₂OCl₉]^?. Synthesis and Crystal Structure The title compound yields from a one step reaction of niobium pentachloride and niobium oxide trichloride with diphenyl acetylene in dichloro methane, forming dark green crystals. The new complex is characterized by the i.r. spectrum and a crystal structure determination by X-ray methods. The compound crystallizes triclinic in the space group P1 with two formula units per unit cell (2253 independent observed reflexions, R = 4.7%). The lattice dimensions are a = 1199, b = 1034, c = 1453 pm; α = 87.0°, β = 108.6°, γ = 96.6°. The cyclobutenyl cation forms an almost planar C₄-ring with two pairs of neighbouring C? C bonds of 139 pm and 153 pm. The anion [Nb₂OCl₉]^? displays a nearly linear NbONb axis (bond angle 174°) in which the NbO bond lengths are 176 pm and 208 pm. Two anions are linked via asymmetric chloro bridges with Nb? Cl bond lengths of 248 pm and 270 pm to form a centrosymmetric dimer.     

Synthese und Kristallstruktur von (PPh4)2[Mo2NCl9]2, einem μ-Nitridokomplex mit Molybdän(V), und -(VI)

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂NCl₉]₂, a μ-Nitrido Complex with Molybdenum (V) and (VI) The title compound is formed as a by-product in the partial oxidation of Mo₂NCl₇ with chlorine in POCl₃ solution, when the reaction mixture is treated with PPh₄Cl. The crystals, which are sensitive to moisture, are black in reflectance and red in transmittance. A more effective synthesis is the direct reaction of PPh₄[MoNCl₄] with MoCl₅ in dichloro methane. (PPh₄)₂[Mo₂NCl₉]₂ was characterized by the i.r. spectrum and by a structural analysis with X-ray data. The compound crystallizes triclinic in the space group P1 with two formula units per unit cell (9225 independent observed reflexions, R = 0.058). The cell parameters are (20°C): a = 1144 pm, b = 1517 pm, c = 2000 pm, α = 79.8°, β = 80.1°, γ = 72.1°. (PPh₄)₂[Mo₂NCl₉]₂ consists of PPh₄⊕ cations and the anions [Mo₂NCl₉]₂^22?, which dimerize via chloro bridges with Mo? Cl bons lengths of 243 pm and 287 pm. In the [Mo₂NCl₉]₂^2? units the molybdenum atoms are linked by Mo^VI?N? Mo^V bridges (bond angles 179° and 174°, resp.) with Mo? N bond lengths of 167 pm and 212 pm.     

[WNCl3 · 0,5 HN3]4; Kristallstruktur und IR-Spektrum

[WNCl₃ · 0.5 HN₃]₄: Crystal Structure and I.R. Spectrum [WNCl₃ · 0.5 HN₃]₄ is formed from tungsten hexachloride and iodine azide in dichloro methane solution yielding dark red and needleshaped crystals. The crystal structure was determined by aid of X-ray diffraction data. The compound crystallises in the triclinic space group P1 with one formula unit per unit cell (R = 0.08, 2 811 independent reflexions). The four metal atoms are arranged in a square, the edges being formed by almost linear W?N? W bridge bonds of alternating length (168 and 210 pm). Two opposite tungsten atoms are coordinated by theαN atom of a HN₃ molecule and by three terminal chloro ligands. The other tungsten atoms achieve coordination number 6 by two terminal and two bridging Cl atoms, linking the tetrameric units to bands along [010]. The i.r. spectrum is reported and assigned.     

Thiochlorowolframate von Wolfram(V) und -(VI). Die Kristallstrukturen von PPh4[WSCl4] und (PPh4)2[WS2Cl4] · 2 CH2Cl2

Thiochlorowolframates with Tungsten(V) and (VI). Crystal Structures of PPh₄[WSCl₄] and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂ Diamagnetic (NEt₄)₂[WSCl₄]₂, having tungsten atoms linked via sulfur atoms, is obtained by the reaction of WCl₅ with NEt₄SH as well as by the reduction of WSCl₄ with NEt₄I in dichloromethane. If the reduction is performed with PPh₄I, PPh₄[WSCl₄] with monomer anions is formed. Reaction of WCl₆ with H₂S in dichloromethane yields brown, insoluble WS₂Cl₂ which has terminal W?S groups and bridging W? S? W groups according to its IR spectrum. WS₂Cl₂ and PPh₄Cl react to afford PPh₄[WS₂Cl₃] · 2 CH₂Cl₂ and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂. IR spectra are reported. The crystal structures of PPh₄[WSCl₄] and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂ were determined by X-ray diffraction. PPh₄[WSCl₄]: tetragonal, space group P4/n, Z = 2, a = 1292.3 pm, c = 763.2 pm; R = 0.054 for 898 observed reflexions. The [WSCl₄]^? ion has the structure of a square pyramid with a rather short W?S bond of 206 pm length. (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂: triclinic, space group P1 , a = 1017.7, b = 1114.5, c = 1243.4 pm, α = 70.61, β = 79.73, γ = 80.80°; R = 0.076 for 1804 reflexions. The [WS₂Cl₄]^2? has cis configuration; as it is situated on an inversion center it shows positional disorder.     

Über die Reaktionen von N-Chloracetonimin mit Molybdänpentachlorid und Wolframhexachlorid Die Kristallstruktur von Me2CNH2[MoOCl4]

Reactions of N-Chloroacetoneimine with Molybdenum Pentachloride and Tungsten Hexachloride. Crystal Structure of Me₂C?NH₂[MoOCl₄] WCl₆ reacts with N-chloroacetoneimine under elimination of chlorine and formation of pentachloro-isopropylideneimino-tungsten(VI), Cl₅W?N?CMe₂, a brown-black crystal powder, which was characterized by i.r. spectroscopy. MoCl₅ reacts in a similar way, although only a product mixture can be obtained. Partial hydrolysis of this mixture yields isopropylideneiminium-tetrachlorooxomolybdate(V), Me₂C?NH₂⁺[MoOCl₄]^?, of which the crystal structure was determined (2323 unique observed reflexions, R = 0.049). Space group P2₁/c, Z = 4, a = 878.6, b = 907.2, c = 1252.2 pm, β = 91.29°. The compound consists of Me₂C?NH₂⁺ ions with a planar arrangement of the skeletal atoms and a CN bond length of 126.7 pm and of dimeric, centrosymmetric anions [MoOCl₄]₂^2? having Mo atoms linked via asymmetric chloro bridges (MoCl distances 238.4 and 307.6 pm). The longer Mo? Cl contacts are located in the trans-positions of the terminal oxoligands (MoO distance 164 pm).     

Chelatkomplexe von Rheniumtetrachlorid. Die Kristallstrukturen von ReCl4(DME) und ReCl4(DPPE) · Tolan

Chelate Complexes of Rhenium Tetrachloride. The Crystal Structures of ReCl₄(DME) and ReCl₄(DPPE) · Tolan Bright green crystals of ReCl₄(DME) have been prepared by the reaction of rhenium pentachloride with dimethoxyethane (DME) in dichloromethane. ReCl₄(DPPE) · tolan was obtained in form of red crystals by the reaction of the alkyne complex [ReCl₄(Ph? C?C? Ph)(POCl₃)] with bis(diphenylphosphino)ethane (DPPE) in dichloromethane. The complexes were characterized by X-ray structure determinations. ReCl₄(DME): Space group I4 2d, Z = 8, 829 observed unique reflexions, R = 0.022. Lattice dimensions at 19.5°C: a = b = 960.60(6), c = 2337.2(6) pm. The complex forms monomeric molecules with DME as chelating ligand; the Re? O bond lengths are 213.1 pm. The chlorine atoms, arranged in trans position to the chelating ligand, have slightly shorter Re? Cl bonds than the chlorine atoms in cis position (232,1 pm). ReCl₄(DPPE) · tolan: Space group P2₁/n, Z = 4,4313 observed unique reflexions, R = 0.040. Lattice dimensions at ?80°C: a = 1095.7(1), b = 1764.2(2), c = 1898.0(2) pm, β = 99.229(8)°. The compound consists in form of monomeric molecules [ReCl₄(DPPE)] and diphenylacetylene molecules, which are incorporated in the lattice. The two phenyl rings of the tolan molecules are twisted towards each other along the C? C axis with a dihedral angle of 21°. The DPPE molecules are bonded to the rhenium atom in a chelating fashion with medium Re? P lengths of 250.4 pm. The chlorine atoms, arranged in trans position to this ligand, with Re? Cl bond lengths of 234.5 pm are slightly longer than the Re? Cl bonds in cis position with 232.3 pm.     

Phosphaniminato-Komplexe des Schwefels. Synthese und Kristallstrukturen von [SO(Cl)(NPPh3)], [SO2(Cl)(NPPh3)] und [SCl(NPPh3)2]Cl

Phosphorane Iminato Complexes of Sulfur. Synthesis and Crystal Structures of [SO(Cl)(NPPh₃)], [SO₂(Cl)(NPPh₃)], and [SCl(NPPh₃)₂]Cl The title compounds have been prepared by the reaction of Me₃SiNPPh₃ with SOCl₂, SO₂Cl₂, and SCl₂, respectively. They form colourless, moisture sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. [SO(Cl)(NPPh₃)]: Space group P2₁/n, Z = 4, structure determination with 2 434 observed unique reflections, R = 0.047. Lattice dimensions at 19°C: a = 1 304.8, b = 996.5, c = 1 339.5 pm, β = 93.75°. The compound forms monomeric molecules with a remarkably long S? Cl bond of 234.2 pm and distances SN and PN of 154.6 and 161.6 pm, respectively, which agree with double bonds. [SO₂(Cl)(NPPh₃)]: Space group P2₁/n, Z = 4, structure solution with 2 872 observed, unique reflections, R = 0.047. Lattice dimensions at 20°C: a = 956.9, b = 1 909, c = 1 002.0 pm, β = 106.06°. The compound forms monomeric molecules with distances S? Cl of 207.1 pm, SN of 154.5 pm, and PN of 161.6 pm. [SCl(NPPh₃)₂]Cl: Space group P2₁/c, Z = 4, structure solution with 5 224 observed, unique reflections, R = 0.042. Lattice dimensions at 20°C: a = 1 108.6, b = 1 603.8, c = 1 840.5 pm, β = 99.98°. The compound forms ions [SCl(NPPh₃)₂]⁺ and Cl^?. In the cation the sulfur atom is φ-tetrahedrally coordinated with a long S? Cl distance of 248.5 pm and SN bond lengths of 154.5 and 156.0 pm.