Die Kristall- und Molekülstrukturen von Chlorotrispyridinium-bis-(tetrachloroaluminat(III)) und einer weiteren Modifikation von Pyridiniumchlorid

Crystal- and Molecular Structures of Chlorotrispyridinium-bis-(tetrachloroaluminate(III)) and a New Modification of Pyridinium Chloride The compounds PyHCl and ((PyH)₃Cl)(AlCl₄)₂ are formed by hydrolysis during the synthesis of adducts in the system AlCl₃/pyridine. The second room temperature modification of PyHCl crystallizes in the space group P2₁/c with the lattice constants a = 847.9(3), b = 1770.2(3), c = 801.9(3) pm, β = 95.23(3)°, Z = 8. The atomic parameters were refined from 4471 measured intensities to R(F) = 6,9%. The N? Cl distances are 306.8(7) and 311.0(8) pm. The unit cell of ((PyH)₃Cl)(AlCl₄)₂ is orthorhombic (space group Pbca) and has the lattice constants a = 1306.3(4), b = 1589.4(4), c = 2708.6(7) pm, Z = 8. The crystal structure was refined from 7226 measured intensities to R(F) = 6.7%. The cation shows three pyridinium ions to have NH…?Cl hydrogen bonds to a central positioned chloride ion with N? Cl distances of 301.4(7), 305(1) and 306(1) pm.     

Die Kristall- und MolekülStruktur von (S4N3)2SbCI5

The structure of (S₄N₃)₂SbCI₅ has been determined by X-ray methods using least-squares′ refinement. The compound crystallises monoclinic; C–P2₁/c, a = 9.24 Å, b = 17.77 Å, c = 11.29 Å, β = 110.06°, Z = 4. The antimony atom has a fivefold coordination the geometry being derived from a deformed octahedron, the S₄N-rings retained their planar shape.     

Darstellung und Molekülstrukturen von oligofunktionalen Dirheniumcarbonylderivaten aus Dirheniumnonacarbonylphosphan

Preparation and Molecular Structures of Oligofunctional Dirhenium Carbonyl Derivatives from Dirhenium Nonacarbonylphosphane Starting with dirheniumdecacarbonyl, one CO-Ligand was eliminated oxidatively and substituted by the labile acetonitrile ligand. As an intermediate eq-Re₂(CO)₉NCCH₃ was received. The reaction of this labilised carbonyl with tris(trimethylsilyl)phosphine and subsequent methanolysis gave ax-Re₂(CO)₉PH₃, which was isolated and characterized for the first time. Photochemical and thermal reaction of ax-Re₂(CO)₉PH₃ led to the new bi- and trinuclear complexes Re₂(μ-H)(μ₃-PHRe(CO)₅)(CO)₈, Re₂(μ-PH₂)₂(CO)₈ and Re₂(μ-H) · (μ-PH₂)(CO)₈, which were characterized by IR-, ¹H- and ³¹P-NMR spectroscopy. The structures of ax-Re₂(CO)₉PH₃, Re₂(μ-H)(μ₃-PHRe(CO)₅)(CO)₈ and Re₂(μ-PH₂)₂(CO)₈ were confirmed by single-crystal X-ray analysis. ax-Re₂(CO)₉PH₃ has a very short Re? P bond length of 228(2) pm.     

Darstellung,Eigenschaften und Molekülstrukturen von Alkylaluminiumaminoalkoxidchloriden

Synthesis, Properties, and Molecular Structures of Alkylaluminium Aminoalkoxide Chlorides Alkylaluminium aminoalkoxide chlorides [R(Cl)AlOR*] 1 – 3 have been obtained from the reaction of dialkyl aluminium chlorides R₂AlCl with the respective aminoalkohol HOR* ( 1 : R = Et, OR* = dimethylamino‐1‐propanol; 2 : R = Me, OR* = (+);(–)‐dimethylamino‐2‐propanol; 3 : R = Me, OR* = (S)‐N‐methyl‐2‐pyrrolidinyl‐methanol). The reaction between dimethylaluminium chloride and (S)‐α, α‐diphenyl‐2‐pyrrolidinyl‐methanol (OR* = Dpm) yielded, by contrast, the ionic {[MeAl(OR*)₂AlMe₂]⁺ [MeAlCl₃]^–} complex ( 4 ). 1 – 4 have been characterised by ¹H, ¹³C and ²⁷Al‐NMR spectroscopy. Crystal structures of 1 and of the 1 : 1 solvate of 4 with Et₂O have been determined by X‐ray methods and the absolute structure of 4 was confirmed by refinement of the Flack‐parameter. The dimeric molecules of 1 are composed of two chelating rings linked via an almost planar Al₂O₂ unit and pentacoordination is observed about aluminium. In contrast, each of the two crystallographically independent cation molecules of 4 contains one four‐ and and one five‐coordinate metal centre.     

Kristall- und Molekülstruktur von Bis(pyridin)bis(trifluoromethyl)zink

Crystal and Molecular Structure of Bis(pyridine)bis(trifluoromethyl)zinc Bis(pyridin)bis(trifluoromethyl)zinc 1 has been isolated and characterized by means of single-crystal X-ray diffraction techniques. The title compound represents the first structure determination of a fully fluorinated alkylzinc compound (monoclinic, space group P2₁/c, Z = 4, a = 8.856(3), b = 18.158(3), c = 8.979(3) Å, β = 98.14(2)°, R = 0.054, R_w = 0.035). The zinc atom is in a distorted tetrahedral environment. The molecular structure of [ClZn(CCl₂CF₃) η₂O]₂ 2 was solved, but is not included in a structural comparison due to crystallographic disorder.     

Kristall- und Molekülstruktur von fac-Trichloro-tris(dimethylsulfoxid)bismut(III) BiCl3(DMSO)3

Crystal and Molecular Structure of fac-Trichloro-tris(dimethyl sulfoxide)bismuth(III) BiCl₃(DMSO)₃ Crystals of the known, although structurally not characterized title compound were fortuitously obtained from a reaction mixture containing (CH₃)₃SiN(SO₂CH₃)₂, BiCl₃, DMSO, CH₂Cl₂ and CH₃NO₂. Crystallographic data (at ?130°C): triclinic, space group P1 1, a = 816.1(5), b = 885.1(6), c = 1 360.6(8) pm, α = 77.58(3), β = 77.39(3), γ = 64.42(3)°, U = 0.8569 nm³, Z = 2. The DMSO ligands are bound through oxygen to the Bi atom. Important bond distances and angles in the resulting fac-octahedral complex are as follows: Bi? Cl 258.9, 261.0, 263.0, Bi? O 242.6, 245.7, 246.1 pm; Cl? Bi? O (trans) 170.3, 170.6, 176.9, Cl? Bi? Cl 94.6, 94.7, 96.0, O? Bi? O 81.7, 85.4, 87.9, Cl? Bi? O (cis) in the range 87.2–92.6, Bi? O? S 123.4, 126.1, 129.6°.     

Komplexchemie P-reicher Phosphane und Silylphosphane. VII. Carbonylkomplexe des Heptaphosphans(3) iPr2(Me3Si)P7

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VII Carbonyl Complexes of the Heptaphosphane(3) iPr₂(Me₃Si)P₇ From the reaction of iPr₂(Me₃Si)P₇ 1 with one equivalent of Cr(CO)₅THF the yellow products iPr₂(H)P₇[Cr(CO)₅] 2 and iPr₂(Me₃Si)P₇[Cr(CO)₅] 3 were isolated by column chromatography on silicagel. The P? H group in 2 results from a cleavage of the P? SiMe₃ bond during chromatography. The Cr(CO)₅ group in 2 is linked to an iPr? P^e atom, in 3 to the Me₃Si? P^e atom of the P₇ skeleton. The substituents do not force the formation of a single isomer; nevertheless 3 ist considerably favoured as compared to 2 . From the reaction of 1 with 2 equivalents of Cr(CO)₅THF the yellow iPr₂(H)P₇[Cr(CO)₅]₂ 4 was isolated bearing one Cr(CO)₅ group at an iPr? P^e atom, the other one at a P^b atom of the P₇ skeleton. Compound 3 yields with Cr(CO)₄NBD the red iPr₂(Me₃Si)P₇[Cr(CO)₅][Cr(CO)₄] 5 . Three isomers of 5 appear. Two P^e atoms of 5 are bridged by the Cr(CO)₄ group, the third P^e atom is linked to the Cr(CO)₅ ligand. iPr₂(H)P₇[Fe(CO)₄] was isolated from the reaction of 1 with Fe₂(CO)₉. ³¹P NMR and MS data are reported.     

Pseudoelementverbindungen. VII [1]. Kristall- und Molekülstruktur von Tris(ethylendiamin)nickel(II)-bis(2-methyl-4-chlorphenoxycyanamidoacetat)

Pseudoelement Compounds VII. [1] Crystal and Molecular Structure of Tris(ethylenediamine)nickel(II)-bis(2-methyl-4-chlorophenoxy-cyanamidoacetate) Surprisingly, in the presence of ethylenediamine 2-methyl-4-chlorphenoxy-cyanamidoactetate reacts with nickel(II) and copper(II) ions preferentially under formation of complexes of the type [M(en)₃]X₂. The IR spectra and the X-ray diffraction investigations corresponding to [Ni(en)₃][2-Me-ClC₆H₃OCH₂C(O)NCN]₂ show that two cyanamidocarboxylate ions [RC(O)NCN]^? are bonded to the complex cation through, in each case, two N? H …? O?C hydrogen bonds between NH protons of ethylenediamine ligands and the carbonyl oxygen atoms. Additionally, in the crystal weak N? H …? N?C bridges were found between the nitrile nitrogen atoms of the anions and NH protons of neighbouring complex cations.     

Komplexchemie at P-reicher Phosphane und Silylphosphane. VI. Bildung und Struktur der Chromcarbonylkomplexe des Tris(trimethylsilyl) heptaphosphanortricyclans (Me3Si)3P7

Formation and Structures of Chromium Carbonyl Complexes of Tris(trimethylsily)heptanortricyclane (Me₃Si)₃P₇ (Me₃Si)₃P₇ 1 reacts with one equivalent of Cr(Co)₅THF 2 to give the yellow (Me₃Si)₃P₇[Cr(Co)₅] 4. The Cr(Co)₅group is attached to a P^e atom. Yellow (Me₃Si)₃P₇[Cr(CO)₅]₂ 5 is obtained either from reacting 1 with two equivalents of 2 , or from 4 with one equivalent of 2. One Cr(CO)₅ groups in 5 is coordinated to a P^e atom, the other one to a P,^b atom. Similarly, Yellow (Me₃Si)₃P₇[Cr(CO)₅]₃ 6 results from reacting 5 with one equivalent of 2 . Two Cr(CO)₅ groups in 6 are linked to P^b atoms, and the third one either to a P^e or the P^a atom (assignment not completely clear). Derivatives containing a P^e bridge appear in reactions of 1 with higher amounts of 2 . Such, 5 forms mixtures of the red compounds (Me₃Si)₃P₇ × [Cr(CO)₅]₂[Cr(CO)₄] 8 and (Me₃Si)₃P₇[Cr(CO)₅] × [Cr(CO)₄] 9 , and even preferably 9 with four equivalents of 2 . In 8 , one Cr(CO)₅ group is attached to that p^e atom which is not engaged in the Cr(CO)₄ bridge, and the second to one of the P^b atoms directly adjacent to the bridge. The additional Cr(CO)₅ group in 9 is coordinated to the remaining P^b atom directly adjacent to the bridge. In reactions of 5 with even higher amounts of 2 , four Cr(CO)₅ groups and one Cr(CO)₄ bridge attach to the basic P₇ skeleton to from the less stable Me₃P₇[Cr(CO)₅]₄[Cr(CO)₄]. (Me₃Si)₃P₇ 1 reacts considerably slower with Cr(CO)₅THF 2 than R₃P₇ (R = Et, iPr). Cr(CO)₄NBD 3 reacts with 1 , but it was not possible to isolate (Me₃Si)₃P₇[Cr(CO)₄]. However, 4 with 3 forms (Me₃Si)₃P₇[Cr(CO)₅][Cr(CO)₄] 7 , and 5 with 3 yields (Me₃Si)₃P₇[Cr(CO)₅]₂[Cr(CO)₄] 8 . The structures of 4 , 5 , 7 , 8 or 9 are quite analogous to those of the derivatives of Et₃P₇ but there exist significant differences in stability and reactivity. While Et₃P₇[Cr(CO)₅]₂ in solution rearranges to give the stable Et₃P₇[Cr(CO)₅][Cr(CO)₄], the analogous (Me₃Si)₃P₇[Cr(CO)₅][Cr(CO)₄] 7 is not stable and is not obtained from (Me₃Si)₃P₇[Cr(CO)₅]₂ 5 . Et₃P₇[Cr(CO)5]₃ can just be detected spectroscopically and rearranges easily to give Et₃P₇[Cr(CO)₅]₂ [Cr(CO)₄] whereas (Me₃Si)₃P₇[Cr(CO)₅]₃ 6 can be isolated. These differences are caused by the greater steric requirements of Me₃Si groups. The formation of a P^e–Cr(CO)₄–P^e bridge, e.g., requires a Me₃Si group in 1 to switch from the s to the as position. Whereas many of the complex compounds of R₃P₇ (R = Et, iPr) crystallize easily, the analogous derivatives of (Me₃Si)₃P₇ did not yield crystals. The structures of the products were assigned by evaluating the coordination shift in their ₃₁P NMR spectra and by comparision of these spectra with those of such derivatives of Et₃P₇ which previously had been investigated by single crystal structure determinations.     

Die Kristall- und Molekülstruktur von Dicäsium- μ-Oxodekafluorodiarsenat

Crystal and Molecular Structure of Dicaesium-μ-Oxodecafluorodiarsenate, Cs₂(As₂F₁₀O) The crystal structure of Cs₂(As₂F₁₀O) has been determined from three-dimensional data. The compound crystallizes in the monoclinic space group P2₁/m, the lattice constants being a = 9.175(4), b = 10.690(5), c = 5.619(3)(Å); β = 105,50(5)°. The anion (As₂F₁₀O)^2– with the point symmetry C_s contains a As? O? As-bridge, whose partial π-bonding is to be discussed. The bond lengths and angles are: As? O: 1.77(2) and 1.68(2) Å, resp., As? O? As: 139(1)°; As…As: 3.225(4) Å, the numbers in parantheses being the standard deviation of the last figure.     

Beiträge zum thermischen Verhalten von Sulfaten. VIII. Zum chemischen Transport von FeSO4 mit NH4Cl und von von Fe2(SO4)3 mit Cl2 oder NH4Cl. Experimente und Modellrechnungen

Contributions on the Thermal Behaviour of Sulfates. VIII. The Chemical Vapour Transport of FeSO₄ with NH₄Cl and Fe₂(SO₄)₃ with Cl₂ or NH₄Cl. Experiments and Calculations Well shaped crystals of FeSO₄ and Fe₂(SO₄)₃ can be grown by CVT (T₁? 650°C). We investigated the dependence of the transport rate on the concentration of the transport agent (Fe₂(SO₄)₃/Cl₂ and Fe₂(SO₄)₃/NH₄Cl) as well as on the temperature (FeSO₄/NH₄Cl and Fe₂(SO₄)₃/Cl₂). Using Δ_fH(FeSO₄) = ?220 kcal/ mol, C^p(T) = 30.1 + 9.9 · 10^?3 ×T and Δ_fH(Fe₂(SO₄)₃) = ?615.4 kcal/mol a satisfying agreement between thermodynamical calculations and experimental results can be reached     

Beiträge zum thermischen Verhalten von Sulfaten. XVI. Zum chemischen Transport von Ga2(SO4)3 mit Cl2 und mit HCl. Experimente und Modellrechnungen

Contributions on the Thermal Behaviour of Sulphates. XVI. The Chemical Vapour Transport of Ga₂(SO₄)₃ with Cl₂ and HCl. Experimental Results and Calculations Crystals of anhydrous Ga₂(SO₄)₃ can be grown by means of CVT (e. g. 525°C → 475°C) in the less hot region of a closed silica ampoule. We investigated the dependance of the deposition rate on the concentration of the transport agent (Cl₂, HCl) and the transport temperature (475°C ≤ T ≤ 750°C; T₂ > T₁; ΔT = 50°C; T = 0.5(T₁ + T₂)). Experimental results and thermodynamic calculations on the basis of Δ_FH ${}_{\text{298}}^{\text{º}}$ (Ga₂(SO₄)₃) = ?686.5 kcal/mol show a good agreement.     

Die Kristall- und Molekülstruktur von (CH3)2SnSAB (SAB = Dianion von 2-Hydroxy-N-(2-hydroxybenzyliden)-anilin)

Crystal and Molecular Structure of (CH₃)₂SnSAB. (SAB = Dianion of 2-Hydroxy-N-(2-hydroxybenzylidene)-aniline) (CH₃)₂SnSAB, C₁₅H₁₅NO₂Sn (SAB = tridentate dianion of 2-hydroxy-N-(2-hydroxybenzylidene)-aniline in SCHIFF base form) crystallizes in the space group Pben (D) with a = 19.271(5), b = 10.508(2), c = 13.379(1) Å and Z = 8. The structure has been solved using 1307 symmetrical independent reflections and applying the heavy atom method; the position of all atoms, except the H atoms, has been determined. As interatomic distances have been found: Sn? C: 2.117(14), Sn? O:2.112(9), Sn? N:2.229(11) N? C 10 (phenyl group II): 1.462(16), C9-N (SCHIFF base bridging group): 1.257(18), C 9? C8 (phenyl group I): 1.441(18) Å; mean C? C distances in the phenyl groups: 1.403(18) Å. Two molecules at a time have a centre of symmetry and weakly coordinate through two loose Sn? O bridges (intermolecular Sn? O distance: 2.881(8) Å). The individual molecules essentially form a distorted trigonal bipyramid with N and both methyl-C atoms in the equatorial plane; ? CSnC = 138.52(50)°; ? OSnO = 158.58(35)°.     

Beiträge zum thermischen Verhalten von Sulfaten. XII. Zum chemischen Transport von In2(SO4)3 mit Cl2 und mit HCl. Experimente und Modellrechnungen

Contributions on the Thermal Behaviour of Sulfates XII. The Chemical Vapour Transport of In₂(SO₄)₃ with Cl₂ and HCl. Experimental Results and Calculations By means of CVT (T₁ between 500°C and 825°C; ΔT = 50°C), well shaped crystals of anhydrous In₂(SO₄)₃ can be grown in the less hot region of a closed silica ampoule. We investigated the dependence of the deposition rate on the variation of the concentration of the transport agent (system In₂(SO₄)₃/Cl₂) and on the variation of the transport temperature (In₂(SO₄)₃/Cl₂ as well as In₂(SO₄)₃/HCl). A comparison of the experimental results with thermodynamical calculations shows a satisfying agreement. The influence of the variation of some additional parameters (H₂O from the wall of the ampoule; Δ_BH(In₂(SO₄)₃)) on the deposition rate is discussed.     

Die Kristall- und MolekularStruktur von Antimontetrachloridazid (SbCl4N3)2

Antimony tetrachloride azide (SbCl₄N₃)₂ crystallizes in the monoclinic space group P2₁/n; the lattice parameters are: a = 8.051, b = 9.353, c = 10.124 Å; β = 93.75°; Z = 2. The crystal structure was solved with the aid of a Patterson synthesis and was refined by the method of least-squares to R = 4.9% for the 922 observed reflexions. The structure is built up from centrosymmetrical (SbCl₄N₃)₂ molecules (idealized point symmetry 2/m) which are arranged in the way of a body centered lattice. The linear azido groups are inclined against the planar (Sb–αN)₂ ring of the molecule by an angle of 24°. Each Sb atom is coordinated by two N and four Cl atoms in a distorted octahedral arrangement.     

Die Kristall- und Molekülstruktur von CuBr · (C2H5)4P2 (monokline Form)

Crystal and Molecular Structure of CuBr · (C₂H₅)₄P₂ (Monoclinic Form) The crystal structure of the copper(I) complex CuBr · (C₂H₅)₄P₂ has been determined by X-ray structure analysis. The substance crystallizes monoclinic, space group C–P2₁/n with a = 10.78, b = 15.74, c = 7.54 Å, β = 84.6° and 4 formula units in the unit cell. The structure was solved by conventional heavy atom methods and has been refined to a final R-value of 0.14. The structure is characterized by continous chains, the copper atoms are tetrahedrally coordinated and linked together by alternating double bridges of two bromine atoms and two biphosphine molecues, respectively.     

Synthese der Silatetraphospholane (tBuP)4SiMe2, (tBuP)4SiCl2 und (tBuP)4Si(Cl)SiCl3 Molekül- und Kristallstruktur von (tBuP)4SiCl2

Synthesis of the Silatetraphospholanes (tBuP)₄SiMe₂, (tBuP)₄SiCl₂, and (tBuP)₄Si(Cl)SiCl₃ Molecular and Crystal Structure of (tBuP)₄SiCl₂ The reaction of the diphosphide K₂[(tBuP)₄] 7 with the halogenosilanes Me₂SiCl₂, SiCl₄ or Si₂Cl₆ in a molar ratio of 1:1 leads via a [4 + 1]-cyclocondensation reaction to the silatetraphospholanes (tBuP)₄SiMe₂ 1,1-dimethyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 1 , (tBuP)₄SiCl₂, 1,1-dichloro-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 2 , and (tBuP)₄Si(Cl)SiCl₃, 1-chloro-1-trichlorsilyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 3 , respectively, with the 5-membered P₄Si ring system. The reaction leading to 1 is accompanied with the formation of the by-product Me₂(Cl)-Si–(tBuP)₄–Si(Cl)Me₂ 1a (5:1), which has a chain structure. On warming to 100°C 1a decomposes to 1 and Me₂SiCl₂. The compounds 2 and 3 do not react further with an excess of 7 due to strong steric shielding of the ring Si atoms by the t-butyl groups. 1, 2 and 3 could be obtained in a pure form and characterized NMR spectroscopically; 2 was also characterized by a single crystal structure analysis. 1a was identified by NMR spectroscopy only.     

Das erste Hexaoxoselenat (VI) – Synthese und Charakterisierung von Na12(SeO6)(SeO4)3

The First Hexaoxoselenate(VI) – Synthesis and Characterization of Na₁₂(SeO₆)(SeO₄)₃ Pure Na₁₂(SeO₆)(SeO₄)₃ has been prepared by solid state reaction at 500 °C from a mixture of Na₂O and Na₂SeO₄ in silver crucibles. The crystal structure has been determined from single crystal data (Pnma, a = 1577.2(7), b = 781.7(3), c = 1475.5(7) pm, Z = 4, R1 = 0.030, wR2 = 0.058, 2480 observed reflections [I_o ≥ 2σ(I_o)]). Na₁₂(SeO₆)(SeO₄)₃ contains novel SeO₆^6– anions. There exists an unexpected topological relationship between the SeO₆Naⁱ₈Na^a₂Na^a_4/2 part of the structure and the MoCl₂ structure type (Mo₆Clⁱ₈Cl^a₂Cl^a_4/2). The crystal structure as determined is consistent with spectroscopic data (IR, Raman, ⁷⁷Se‐MAS‐NMR).     

Reaktion von cyclopentadienyl-substituierten Molybdän(V)-tetrachloriden mit LiPH(2,4,6-BuC6H2) und KPPh2(Dioxan)2. Molekülstrukturen von [Cp0Mo(μ-Cl)2]2 und [CpMo2(μ-Cl)3(μ-PPh2)] (Cp0 = C5Me4Et)

Reaction of Cyclopentadienyl Substituted Molybdenum(V) Tetrachlorides with LiPH(2,4,6-Bu C₆H₂) and KPPh₂(Dioxane)₂. Crystal Structures of [Cp⁰Mo(μ? Cl)₂]₂ and [Cp Mo₂(μ? Cl)₃(μ? PPh₂)] (Cp⁰ = C₅Me₄Et) The reaction of [Cp⁰Mo(CO)₃]₂ (Cp⁰ = C₅Me₄Et) and [Cp′Mo(CO)₃]₂ (Cp′ = C₅H₄Me) with PCl₅ in CH₃CN furnishes the Mo(V) complexes Cp⁰MoCl₄(CH₃CN) 1 and Cp′MoCl₄(CH₃CN) 2 in good yields. While 1 and 2 are reduced by LiPH(2,4,6-BuC₆H₂) to the Mo(III) complexes [Cp⁰Mo(μ? Cl)₂]₂ 3 and [Cp′Mo(μ? Cl)₂]₂ 4 , the reaction of 1 with KPPh₂(dioxane)₂ yields the reduction/substitution product [CpMo₂(μ? Cl)₃(μ? PPh)] 5 in low yield. 1 – 4 were characterized spectroscopically (i.r., mass, 3 and 4 also n.m.r.). An X-ray crystal structure determination was carried out on 3 and 5. 3 crystallizes in the triclinic space group P1 (No. 2) with a = 8.278(4), b = 12.508(7), c = 12.826(7) Å, α = 86.78(5), β = 81.55(2), γ = 75.65(4)°, V = 1 272.4 ų and two formula units in the unit cell (data collection at ? 67°C, 4 255 independent observed reflections, R = 2.9%); 5 crystallizes in the triclinic space group P1 (No. 2) with a = 11.536(8), b = 12.307(9), c = 13.157(9) Å, α = 91.41(6), β = 100.42(5), γ = 112.26(6)°, V = 1 688.7 ų and two formula units in the unit cell (data collection at ? 60°C, 6 147 independent observed reflections, R = 4.9%). The crystal structure of 3 shows the presence of centrosymmetric dimeric molecules with four bridging chloro ligands. In 5, two Mo atoms are bridged by three chloro ligands and one PPh₂ ligand. The Mo? Mo bond length in 3 and 5 (2.600(2), 2.596(2) Å and 2.6388(8) Å) is in agreement with a Mo? Mo bond.