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  • 1
    Electronic Resource
    Electronic Resource
    The structure of Mo4Cl8(PEt3)4: How unrecognized disorder previously reduced the quality of the refinement (1991)
    Springer
    Journal of cluster science 2 (1991), S. 121-129 
    Details
    ISSN: 1572-8862
    Keywords: Molybdenum tetranuclear cluster ; rectangular ; triethylphosphine ligand ; preparation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The preparation and structure of the title compound were reported several years ago by McCarly and co-workers ((1978).J. Am. Chem. Soc. 100, 7900). Curiously, it was reported that refinement of the structure converged at exceptionally high figures of merit (R=0.126;R w =0.158), but no reason was given. In view of a recent observation in this laboratory (Chen and Cotton (1991).J. Am. Chem. Soc. 113, 5857) that a similar type of compound, [Re4Cl8(μ-O)2(μ-OMe)2]2− exhibited a subtle but elegant disorder, we reexamined the crystal structure of the title compound. It is found to have 92% of the Mo4 rectangles in one orientation (the only one previously included in the refinement) and 8% in an orientation perpendicular to the main one. In both orientations the ligand positions are approximately the same. The figures of merit are nowR=0.041;R w =0.064. The three structure parameters previously reported are now only slightly different: Mo-Mo=2.210(1) vs. 2.211(3) Å; Mo-Mo'=2.897(1) vs. 2.901(2) Å; angle Mo-Clb-Mo=74.2[8]° vs. 74.4(2)°. We report here the complete structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702953
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  • 2
    Electronic Resource
    Electronic Resource
    Further studies of M3(μ3-O)(μ-X)3(μ-O2CCH3)3L3 (M=Mo, W) type clusters with nine core electrons (1992)
    Springer
    Journal of cluster science 3 (1992), S. 123-144 
    Details
    ISSN: 1572-8862
    Keywords: Molybdenum ; tungsten ; crystal structure ; reduction ; acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Four new compounds having nine cluster electrons and cores of the types Mo3OCl3, Mo3OBr3, and W3OCl3 are reported. Compound (1) prepared by reduction of [Bu4N][Mo3OCl6(OAc)3] in THF with metallic zinc, was shown by X-ray crystallography to be Mo3OCl4(OAc)3 (THF)2 (1). It forms crystals in space groupP21 with unit cell dimensionsa=9.472(2) Å,b=13.546(4) Å,c=9.652(2) Å, β=101.70(2)°,V=1201(1) Å3,Z=2. The [Mo3(μ3-O)(μ-Cl)3]4+ core is surrounded by three μ-O2CCH3 anions, one Cl−, and two THF and has Mo-Mo distances of 2.620(1) Å, 2.613(1) Å, and 2.530(1) Å, with the shortest bond between the two Mo atoms to which the THF molecules are coordinated. Compounds [Bu4N]2 [Mo3OBr6(O2CCH3)3] · Me2CO, (2) and [Mo3OBr3(O2CCH3)3(PMe3)3]3 · BF4, (3) are the first two nine-electron Mo3 species with a [Mo3(μ3-O) Br3]4+ core. Both were obtained by zinc reduction of [Mo3OBr6(O2CCH3)3]− in the presence of (NBu4) Br (2) or PMe3 and NaBF4 (3), and each was characterized crystallographically. Compound (2) crystallized in space group Cc with unit cell dimensionsa=25.037(5) Å,b=12.827(2) Å,c=21.484(4) Å, β=122.96(1)0,V=5790(3) Å3,Z=4. While the anion has no crystallographically required symmetry, its virtual symmetry is C3v . The Mo-Mo distances are 2.619(2) Å, 2.610(3) Å, 2.644(2) Å, with a mean value of 2.624[14] Å. Compound (3) crystallized in space groupP21/c with unit cell dimensionsa=10.846(2) Å,b=25.033(5) Å,c=12.641(5) Å, β=94.74(2)0,V=3420(2) Å3,Z=4. The cation occupies a general position but has virtual C3v symmetry, with Mo-Mo distances of 2.601(2) Å, 2.610(2) Å, 2.627(2) Å, with a mean value of 2.613[14] Å. Thus the anionic and cationic Mo3 clusters in (2) and (3), respectively, have average Mo-Mo distances that are equal within experimental error. Compound (4), [NEt4]2 [W3OCl6(O2CCH3)3] is the first 9-electron compound of this type containing tungsten. It was prepared by reduction of [Et4N][W3OCl6(OAc)3] in benzene with Na/Hg. It crystallized in space groupP212121 with unit cell dimensionsa=11.076(2) Å,b=14.345(2) Å,c=21.026(3) Å,V=3574(1) Å3,Z=4. The anion resides on a general position but has virtual C3v symmetry, with W-W distances of 2.577(1) Å, 2.612(1) Å, 2.584(1) Å and a mean value of 2.591[15] Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702878
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  • 3
    Electronic Resource
    Electronic Resource
    The W2Cl4(NHCMe3)2(PR 3)2 molecules (R 3=Me3, Et3, Pr n 3, Me2Ph) I. Their isomeric forms, interconversion proeesses, crystalline forms, and detailed molecular structures (1994)
    Springer
    Journal of cluster science 5 (1994), S. 11-36 
    Details
    ISSN: 1572-8862
    Keywords: Tungsten ; isomeric forms ; crystal structure ; triple bonds ; interconversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A thorough study of compounds with the formula W2Cl4(NHCMe3)2(PR3)2, withR 3=Me3, Et3, Prg n 3 Me2,Ph, is reported. In addition to the previously reported crystalline compounds, namely Ia,trans-W2Cl4(NHCMe3)2(PMe3)2 in space group Pmmn;3a,trans-W2Cl4(NHCM3)2(PEt3)2 in space group P21/a (or P21/c); and4,cis-W2Cl4(NHCMe3)2(PMe2Ph)2 in Pna21, we have obtained and structurally characterized the following new substances,1b,trans-W2Cl4,(NHCMe3)2(PMe2)2, space group P21/c,a= 12.233 (4) Å,b= 12.872 (4) Å,c=17.095 (5) Å,β=93.52 (2)°,Z=4,V=2687 (1) Å3 2,cis-W2Cl4(NHCMe3)2(PMe3)2, P21/c,a=9.673 (4) Å,b=17.249 (4) Å,c=16.244 (5) Å,β=99.63 (3),Z = 4 ,V=2669 (1) Å.3b,trans-W2Cl4(NHCMe3)2(PEt3)2, Pl,a=16.850 (3) Å,b=17.797 (3) Å,c= 11.459 (2)Å,α= 101.02 (1),β= 103.13°, y=84.23 (1)°,Z=4,V= 3279 (1) Å5,trans-W2Cl4(NHCM3)2(PMe2Ph)2, Fdd2,a=39.563 (8) Å at 20°C; 39.325 (10) Å at -6O°C,b = 57.543 (17) Å at 20°C; 57.186 (16) Å at -60°C,c= 8.810 (1) Å at 20°C; 8.770 (1) Å at - 60°C ,Z=24,V=20057 (7) Å3 (20°C), 19723 (8) Å3 ( - 60°C) .6,trans-W2Cl4(NHCMe3 2(PPrn 3)2, Pl,a= 17.287 (2) Å (20°C); 17.077 (5) Å (-60°C),b= 19.119 (2) Å (20°C); 18.952 (6) Å (-60°C),c= 12.713 (1) Å (20°C); 12.668 (4) Å (-60°C),Z=4,V= 3980 (1) Å3 (20°C), 3898 (2) ,Å3 ( - 60°C). In addition, the structure of3a was re-determined and refined so that the disorder ratio was a refined parameter, leading to a value of 0.520:0.480 instead of being arbitrarily fixed at 0.50:0.50. In all of the structures the molecules are held in eclipsed (but very distorted) rotational conformations and the W-W distances are all within the range of 2.305-2.330 Å. As will be shown in a later paper, for all phosphines, thecis andtrans isomers are of similar stability and an equilibrium mixture exists in solution. It is also shown that1a and3a do not contain unexpectedly short W-N bonds as previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165490
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  • 4
    Electronic Resource
    Electronic Resource
    A double-bonded niobium(III) compound with a formamidinate core: Nb2(μ-SMe)2(μ-DTolF)2 (η2-DTolF)2.2 toluene, DToIF= di-p-tolylformamidinate (1996)
    Springer
    Journal of cluster science 7 (1996), S. 655-662 
    Details
    ISSN: 1572-8862
    Keywords: Niobium(III) ; edge-sharing bioctahedra ; di-p-tolylformamidinato ; thiomethoxide ; double-bond ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of NaEt3BH with Nb2(μ-SMe2)3Cl6 results in the transfer of a hydride ion to dimethylthioether with concomitant production of methane. Further reaction with potassium di-p-tolylformamidinate, KDTolF, yields Nb2(μ-SMe)2(μ-DTolF)2η2-DTolF:)2.2 toluene, 1. In the latter, two thiomethoxide ions and two DTolF groups bridge the trivalent niobium atoms. Each of the other two DTolF groups chelate a metal atom to give the molecule an edge-sharing bioctahedral structure, The niobium-niobium distance of 2.655(2) A is consistent with the presence of a double bond between the metal atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165807
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  • 5
    Electronic Resource
    Electronic Resource
    A Novel Cluster Consisting of Seven Fused MX6 Octahedra, Li14(THF)8[Ni7Cl17(μ-formamidinate)3(μ-Cl)]2 (2000)
    Springer
    Journal of cluster science 11 (2000), S. 87-94 
    Details
    ISSN: 1572-8862
    Keywords: nickel cluster ; fluorinated formamidine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract When a THF solution made from equimolar amounts of methyllithium and N,N′-bispentafluorophenyl formamidine, C6F5NC(H)N(H)C6F5, was added to a suspension of NiCl2 in THF and the mixture refluxed for 12 h, a bright yellow-green solution was formed, from which a bright green crystalline compound was obtained in 〉60% yield upon partial evaporation of the solvent. This compound, Li14(THF)8[Ni7Cl17(μ-formamidinate)3(μ-Cl)]2·9.4THF, crystallizes in the tetragonal space group P4 2/mnm (No. 136) with Z=2. The core consists of two Ni7 units bridged by two Cl atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009008630342
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  • 6
    Electronic Resource
    Electronic Resource
    New synthetic routes for the preparation of the triangular trinuclear clusters of tungsten-containing bromine atoms as terminal ligands: Structural characterization of [W3S4Br3(depe)3]PF6·0.5C7 H8 and [W3S4Br3(depe)3]Br·2CH3OH (1990)
    Springer
    Journal of cluster science 1 (1990), S. 287-305 
    Details
    ISSN: 1572-8862
    Keywords: Tungsten ; clusters ; preparation ; triangular ; trinuclear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Synthetic methods are reported for the preparation of compounds containing the trinuclear triangular cluster [W3S4Br3(depe)3[+. These involve reactions between WBr5 and NaB(C2 H5)3H or NaBH4 as reducing agent in THF, and subsequent addition of methanolic solutions of NaHS and depe ligand. Both compounds, [W3S3Br3(depe)3]PF6·0.5C7H8,1, and [W3S4Br3(depe)3]Br·2CH3OH,2, are characterized by x-ray single crystal studies. Compounds1 and2 crystallize in space group $$P\bar 1$$ . For1,a=10.427 (3) Å,b=15.415(4) Å,c=18.140(5) Å, α=79.36(2)°, β=73.59(2)°, γ=81.54(2)°, andV=2734.8(2) Å3;R=0.050 and for 2a=10.491(3) Å,b=15.074(3) Å,c=18.246 Å, α=95.76(2)°, β=105.82(2)°, γ=98.18(2)°, andV=2718.4(3) Å3;R=0.081. The two cations in1 and2 possess C3 symmetry. The W-W distances are in the range 2.783−2.891 Å (for1) and 2.778−2.785 Å (for2) and the average W-Br distances in1 and2 are 2.616[2] Å and 2.594[4] Å, respectively. Each metal atom in the [W3S4Br3(depe)3]+ ions is attached to one capping sulfur atom, two bridging sulfur atoms, one bromine atom, and one chelating depe ligand. One P atom in depe ligand istrans to μ3-S and the otherP atom istrans to a μ2-S atom. UV-Vis and NMR spectra for these compounds are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032274
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  • 7
    Electronic Resource
    Electronic Resource
    Solid solutions of a Jahn-Teller compound in an undistorted host. 2. High-Spin, Six-Coordinate Cr2+ without Jahn-Teller DistortionDedicated to Professor Hans-Georg von Schnering on his 60th Birthday (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 598 (1991), S. 53-70 
    Details
    ISSN: 0044-2313
    Keywords: Mixed chromium zinc nicotinates ; preparation ; x-ray diffraction ; Jahn-Teller distortion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Feste Lösungen einer Jahn-Teller-Verbindung in einem ungestörten Wirt. 2. High-Spin, sechsfach koordiniertes Cr2+ ohne Jahn-Teller-EffektEine Reihe von festen Lösungen der allgemeinen Zusammensetzung [CrxZn1-x(nic)2(H2O)4] (mit nic = C6H4NO2-, konjugierte Base von Nikotinsäure) wurden als Einkristalle dargestellt und röntgenkristallographisch charakterisiert. Der reine Chrom-Komplex (x = 1) kristallisiert in der triklinen Raumgruppe P1 mit einem Zellvolumen (V) von 360,5(2) Å3. Die Verbindung zeigt eine Jahn-Teller-Verzerrung. Der reine Zink-Komplex (x = 0) zeigt keinen Jahn-Teller-Effekt und kristallisiert in der monoklinen Raumgruppe C2/m mit V = 728,0(1) Å3. Acht feste Lösungen mit dem Chrom-Molenbruch von 0,145(12) bis 0,777(12) haben die ungestörte Struktur des Zinknikotinats (Raumgruppe C2/m). Die Zellvolumina variieren nur zwischen 731,1(4) Å3 und 740,6(3) Å3 (bei 20°C), jeweils für den niedrigsten und höchsten Molenbruch. Die Besetzung der Metallatomlagen wurde für jede Probe mit Hilfe von Röntgendaten bestimmt. Es wird über die Homogenität in der Kristallprobe und die Signifikanz der bei der Verfeinerung ermittelten Besetzungen diskutiert. Eine nichtstrenge geometrische Konkordanz besteht zwischen triklinen und monoklinen Endgliedern. Das ausgedehnte Netzwerk von Wasserstoffbrückenbindungen im Gitter der „Zink-Verbindung“ verleiht dem Mischsystem, in dem das high-spin d4-Chromzentrum ohne Jahn-Teller-Verzerrung existiert, Stabilität.
    Notes: A series of solid solutions of the type [CrxZn1-x(nic)2(H2O)4], in which nic represents C6H4NO2-, the conjugate base of nicotinic acid, have been prepared as single crystals and characterized by X-ray diffraction. The pure chromium end member is triclinic, space group P1, with a cell volume V of 360.5(2) Å3. The compound has a Jahn-Teller distortion. The pure zinc end member, which has no Jahn-Teller distortion, crystallizes in the monoclinic system, space group C2/m, with V = 728.0(1) Å3. Eight solid solutions with chromium mole fractions in the range of 0.145(12) to 0.777(12) all adopt the structure of the undistorted zinc nicotinate host, with space group C2/m and V ranging only from 731.1(4) Å3 to 740.6(3) Å3 (at 20°C) for the lowest and highest Cr mole fractions, respectively. The population at the metal-atom site was established for each sample by X-ray diffraction. The questions of homogeneity in the crystalline samples and of the significance of the population refinement are discussed. A non-rigorous geometrical concordance exists between the triclinic and monoclinic end members. An extensive hydrogen bonding network in the zinc-type lattice confers stability on the mixed systems, in which high-spin, d4 chromium centers exist without Jahn-Teller distortion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915980106
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