Kurze Mitteilungen

W2Cl7(CCl), a Polymeric Tungsten Chlorocarbyne Complex

Johannes Beck* and Frank Wolf

Bonn, Institut für Anorganische Chemie der Rheinischen Friedrich-Wilhelms-Universität

Received January 24th, 2002.

Professor Welf Bronger zum 70. Geburtstag gewidmet

Abstract. Black crystals of W2Cl7(CCl) were obtained from the re-action of WCl6 and As in CCl4 at 250 °C under solvothermal con-ditions. The crystal structure (orthorhombic, space group Pbca,a � 1196(1), b � 1215.6(7), c � 1584(1) pm, Z � 8) is built ofinfinite zig-zag chains of dinuclear complexes connected via brid-ging Cl atoms. The individual complexes are face-sharing doubleoctahedra concatenated via bridging Cl ligands. Each W atom isin a distorted octahedral coordination environment of five Clatoms an the carbon atom of the µ2 bridging chloromethylidyne

In the course of studies on the existence of ternary group 6 metal /pentele / halogen compounds we performed solvothermal synthesesin carbon tetrachloride. Equimolar amounts, typically 50 mg Asand 265 mg WCl6 (0.67 mmol each), were filled under argon inglass ampoules of 6 cm length and 0.7 cm diameter. 5 ml CCl4 werecondensed on the solids and the ampoules were flame sealed andplaced in an autoclave which was filled with pentane to establish acounter pressure to prevent bursting of the glass ampoules. In oneof these reactions, after heating to 250° for two days and 6 weeksto 100 °C and cooling to room temperature with 5 °C/h, a darkbrown-red solution had formed from which after prolonged stand-ing black, cube-shaped crystals deposited besides red thin plate-like crystals of WCl6. Under these conditions, elemental arsenic iscompletely converted into AsCl3 which dissolves in the solventCCl4. The formation of W2Cl7(CCl) can thus be explained by thereduction of WCl6 and CCl4 by As:

6 WCl6 � 3 CCl4 � 8 As � 3 W2Cl7(CCl) � 8 AsCl3

Crystal Structure

W2Cl7(CCl) crystallizes orthorhombic, space group Pbca, a �

1196(1), b � 1215.6(7), c � 1584(1) pm, Z � 8. Intensity data werecollected with a STOE IPDS diffractometer, Mo-Kα radiation,room temperature, 9431 reflections collected between 7,6° < 2θ <45° of which were 712 systematically extincted, 1437 unique reflec-tions, 1437 reflections in least squares refinements for 100 param-eters, numerical absorption correction, µ � 217.7 cm�1, R(F2)�0.084, R(�F �) for all reflections 0.049, R(�F �) for 1376 reflections withF > 4σ(F) 0.046. Table 1 contains the positional parameters.

* Prof. Dr. J. BeckInstitut für Anorganische ChemieGerhard-Domagk-Str. 1D-53121 BonnFax Int. �49 228 73 56 60.E-mail j.beck@uni-bonn.de

Z. Anorg. Allg. Chem. 2002, 628, 1453�1454 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 0044�2313/02/628/1453�1454 $ 20.00�.50/0 1453

ligand leading to the formula [{Cl2W(µ-CCl)(µ2-Cl)2 WCl2}(µ-Cl)]n. The short W-W distance of 256 pm indicates a multiple W-W bond, the W-C bonds of 195 pm are in the typical range for µ2-alkylidyne ligands, the C-Cl bond of 167 pm is consistent with asp1 hybridisation on the carbon atom.

Keywords: Tungsten methylidyne complex; µ2-Chloromethylidyneligand; Metal-metal bond; Solvothermal synthesis; Crystal struc-ture

Table 1 Positional parameters and equivalent isotropic displace-ment parameters /104pm2 for W2Cl7(CCl).

x y z Bequiv

W1 0.12844(4) 0.71021(5) 0.17708(3) 2.29(2)W2 �0.07768(4) 0.70582(5) 0.13328(3) 2.37(3)Cl1 �0.2637(3) 0.6372(3) 0.1936(2) 2.83(8)Cl2 �0.0221(3) 0.7589(3) 0.2761(2) 2.81(7)Cl3 0.0177(3) 0.5418(3) 0.1905(3) 3.16(8)Cl4 0.2072(3) 0.8762(3) 0.1971(3) 3.61(9)Cl5 0.2565(3) 0.6245(4) 0.0961(3) 3.63(9)Cl6 �0.1634(3) 0.8691(4) 0.1119(3) 3.64(9)Cl7 �0.1232(4) 0.6080(4) 0.0168(3) 4.21(8)C 0.053(1) 0.765(1) 0.0773(8) 3.0(3)Cl8 0.0831(4) 0.8316(5) �0.0121(3) 6.0(1)

Further details of the crystal structure analysis have been depositedwith the Fachinformationszentrum Karlsruhe, D-76344 Eggen-stein-Leopoldshafen, from where they can the obtained by quotingthe depository number CSD-412384. All calculations were per-formed with the SHELX programs [1,2], graphics were made withDIAMOND [3].

The crystal structure consists of dinuclear complexesW2Cl7(CCl) which are linked by bridging Cl atoms to infinitechains of zig-zag shape (Fig. 1). The individual complexes are face-sharing double octahedra with two bridging Cl ligands and a µ2-bridging chloromethylidyne ligand. Each tungsten atom is in a dis-torted octahedral environment and is coordinated by five Cl atomsand the carbon atom of the bridging CCl ligand. The W1-W2 dis-tance of 256 pm indicates a multiple metal-metal bond. The W-Cdistances of 195 pm are symmetrical within standard deviations,the C-Cl distance of 167 pm is slightly longer than the typical val-ues for C(sp1)-Cl bonds (157 pm in Cl-CN [4], 163 pm in Cl-CC-CN [5] ). In the molybdenum chloromethylidyne complex[Mo(CCl)(CO)2{B(C3H3N2)4}] the CCl ligand is bound terminallyto the metal atom and a Mo-C bond of 189 pm and a C-Cl bond of155 pm are present [6]. In [PPh4][WCl4(Cl-CC-Cl)] a dichloroethinemolecule is π-bound to the metal center and has a C-Cl bondlength of 178 pm [7]. In the structure of W2Cl7(CCl) the four atomsW1, W2 C, and Cl8 form an essentially planar arrangement. The

J. Beck, F. Wolf

Fig. 1 An individual complex with atom labeling and displacementellipsoids (50 % probability) as a section of the concatenated com-plexes in the structure of W2Cl7(CCl) (top) and a longer section ofthe chain of binuclear complexes (bottom).Distances / pm: W1-Cl1I 257.8(4), W1-Cl2 246.0(4), W1-Cl3 244.8(4), W1-Cl4 225.0(4), W1-Cl5 225.2(4), W1-C 194(1), W2-Cl1 256.1(4), W2-Cl2244.5(4), W2-Cl3 246.9(4), W2-Cl6 226.0(4), W2-Cl7 226.0(4), W2-C 194(2),C-Cl8 167(2), W1-W2 256.1(3); Angles /°: W1-C-W2 82.7(6), W1-C-Cl8139.5(8), W2-C-Cl8 137.8(9); Symmetry operation I � 0.5 � x, y, 0.5 � z.

W-Cl bonds between W and the terminal Cl atoms Cl4, Cl5, Cl6and Cl7 have an averaged length of 226 pm, the µ2-W-Cl-W bondswithin the dinuclear complexes a length of 245 pm. The longest W-Cl bonds of 257 pm are observed between W and Cl1 in trans-position to the methylidyne C atom. These bonds link the com-plexes to chains catena-poly[(µ-chloromethylidyne)-di-µ-chloro-tetrachloroditungsten(W-W)]), [{Cl2W(µ-CCl)(µ2-Cl)2WCl2}(µ-Cl)]n. The type of linkage of dinuclear face sharing dioctahedral

Z. Anorg. Allg. Chem. 2002, 628, 1453�14541454

complexes found in W2Cl7(CCl) shows close similarities to the link-ing of Re2Cl8 complexes in the structure of β-ReCl4 [8].

A close relationship is present between W2Cl7(CCl) andW2(OEt)7(CSiMe3) which forms dimers of dinuclear complexes[W2(OEt)7(CSiMe3)]2 [9]. The individual dinuclear complexes ofboth compounds, however, are essentially isostructural. Countingthe charges of Cl and OEt as �1, CCl and CSiMe3 as �3, oneobtains for W the oxidation state �5. In simple Lewis formula thebonding situation can be written in resonance structures with theconsequence of electron delocalisation and a bond order betweenone and two for the W-W bond.

Theoretical studies on the bonding situation for the eight elec-trons in the central W2C triangle of [W2H6(µ-CH)(µ-OH)2]� as asimplified model resulted in four bonding molecular orbitals ofsymmetry 1a1, b2, b1, 2a1. Of these 1a1 (a W2C three center bond)and 2a1 (dz2 overlap along the W-W axis) are mainly bonding be-tween W atoms. So a σ2π2 W-W double bond was interpreted forthe W(µ2-CH)W moiety [9]. The topic of alkylidene and alkylidynecomplexes of transition metals in high oxidations states has recentlybeen reviewed [10].

Acknowledgement. The support of our work by the Deutsche For-schungsgemeinschaft and the Fonds der Chemischen Industrie isgratefully acknowledged.

[1] G. M. Sheldrick, SHELXS-97, Program for Crystal StructureSolution, University of Göttingen, 1997.

[2] G. M. Sheldrick, SHELXS-93, Program for Crystal StructureRefinemet, University of Göttingen, 1993.

[3] DIAMOND, Visual Information System for Crystal Structures,Crystal Impact Co., Bonn, Germany, 1996.

[4] R. B. Heiart, G. B. Carpenter, Acta Crystallogr. 1956, 9, 889.[5] T. Bjorvatten, Acta Chem. Scand. 1968, 22, 410[6] T. Desmond, F. J. Lalor, G. Ferguson, M. Parvez, J. Chem.

Soc. Chem. Comm. 1983, 457.[7] K. Stahl, F. Weller, K. Dehnicke, Z. Anorg. Allg. Chem. 1986,

533, 73.[8] F. A. Cotton, B. G. DeBoer, Z. Mester, J. Am. Chem. Soc.

1973, 95, 1159.[9] M. H. Chisholm, K. Folting, J. A. Heppert, D. M. Hoffman,

J. C. Huffman, J. Am. Chem. Soc. 1985, 107, 1234.[10] R. R. Schrock, Chem. Rev. 2002, 102, 145; J. W. Herndon,

Coord. Chem. Rev. 2002, 227, 1.