Journal of Chemical Crystallography, Vol. 29, No. 2, 1999

Note

Molecular structure of ThBr4(DME)2

(DME 5 1,2-dimethoxyethane)

Daniel Rabinovich,(1,2)* Brian L. Scott,(1) Jon B. Nielsen,(1) and Kent D. Abney(1)

Received May 15, 1998

The molecular structure of ThBr4(DME)2 (DME 5 1,2-dimethoxyethane), the first structur-ally characterized thorium complex containing a simple bidentate ether ligand, is described.The eight-coordinate complex presents a distorted dodecahedral geometry, with ThUBrand ThUO bond lengths in the ranges 2.8516(13)–2.8712(13) A and 2.564(8)–2.620(8) A,respectively. ThBr4(DME)2 is monoclinic, space group P21/n, a 5 7.672(1), b 5 14.581(1),c 5 15.847(2) A, b 5 102.24(1)8, V 5 1732.4(3) A3, and Z 5 4.

KEY WORDS: Thorium; dimethoxyethane; crystal structure.

Introduction

Discrete Lewis base adducts of the thoriumtetrahalides ThX4Ln, where XuCl, Br, or I and Lis typically a unidentate (n 5 2, 3 or 4) or bidentate(n 5 2) nitrogen- or oxygen-based donor ligand,are synthetically attractive complexes because oftheir increased solubility and enhanced reactivitycompared to the polymeric base-free species ThX4.A number of such derivatives have been preparedand structurally characterized in recent years, forexample ThBr4[OC(NEt2)2]2,1 ThCl4(OPPh3)3,2

ThBr4(THF)4,3 and ThCl4(TMEDA)2.4 We reportherein the single crystal X-ray structure of thebis(dimethoxyethane) complex ThBr4(DME)2, thefirst thorium compound containing a simple, neutralbidentate ether ligand to be structurally charac-terized.

(1) Los Alamos National Laboratory, Chemical Science and Tech-nology Division, CST-11, Mail Stop J514, Los Alamos, NewMexico 87545.

(2) Current address: Department of Chemistry, The University ofNorth Carolina at Charlotte, Charlotte, North Carolina 28223.

* To whom correspondence should be addressed.

243

1074-1542/99/0200-0243$16.00/0 1999 Plenum Publishing Corporation

Experimental

The preparation of ThBr4(DME)2 by treating asuspension of ThBr4(THF)4 in toluene with an excessof DME was reported by Clark et al. in 1992.3 Thecolorless crystal of ThBr4(DME)2 used in the struc-ture determination described in this paper was se-lected from a batch obtained directly from a concen-trated solution of ThBr4(THF)4 in dimethoxyethaneat 2308C. The crystal was mounted on a thin glassfiber using silicone grease and immediately placedunder the cold nitrogen stream on a Siemens P4/PCdiffractometer (Mo Ka radiation, l 5 0.71073 A).Lattice determination and data collection were car-ried out using XSCANS Version 2.10b software.5 Alldata reduction, including Lorentz and polarizationcorrections and structure solution and graphics, wereperformed using SHELXTL PC Version 4.2/360 soft-ware.5 The structure refinement was performed usingSHELXL93 software.5 The data were corrected forabsorption using the ellipsoid option in the XEMPfacility of SHELXTL PC. The crystal data and struc-ture refinement, and the final atomic coordinates andequivalent isotropic displacement parameters, aregiven in Tables 1 and 2, respectively.

244 Rabinovich, Scott, Nielsen, and Abney

Table 1. Crystal Data and Structure Refinement for ThBr4(DME)2

Empirical formula C8H20Br4O4ThCCDC deposit no. CCDC-1003/5515Formula weight 731.92Temperature 173 KWavelength 0.71073 ACrystal system MonoclinicSpace group P21/nUnit cell dimensions

a 5 7.672(1) Ab 5 14.581(1) Ac 5 15.847(2) Ab 5 102.24(1)8

Volume 1732.4(3) A3

Z 4Density (calc.) 2.806 Mg/m3

Absorption coefficient 17.833 mm21

Absorption correction Semi-empiricalMin./max. transmission 0.272/0.981F(000) 1320Crystal color; habit Colorless parallelepipedCrystal size (mm) 0.12 3 0.25 3 0.37u range for data collection 2.63 to 22.508

Index ranges 21 # h # 8, 21 # k # 15, 217 # l # 16Reflections collected 3101Independent reflections 2249Rint 0.0407Observed reflections [Fo . 4s(Fo)] 1776Refinement method Full-matrix least-squares on F 2

Data/restraints/parameters 2249/0/154Goodness-of-fit on F 2 0.972Final R indices R1 5 0.0360, wR2 5 0.0864R indices (all data) R1 5 0.0533, wR2 5 0.0947Largest diff. peak and hole 1.634 and 21.469 e A23

Table 2. Atomic Coordinates (3 104) and Equivalent IsotropicDisplacement Parameters (A2 3 103) for ThBr4(DME)2

x y z U(eq)a

Th(1) 226(1) 2553(1) 1050(1) 12(1)Br(1) 1836(2) 3219(1) 2311(1) 22(1)Br(2) 2435(2) 3931(1) 2029(1) 24(1)Br(3) 23208(2) 1926(1) 184(1) 29(1)Br(4) 2209(2) 1121(1) 2224(1) 29(1)O(1) 21693(11) 3955(6) 494(5) 24(2)O(2) 21553(12) 3276(6) 2094(5) 28(2)O(3) 3274(11) 1752(5) 1531(5) 18(2)O(4) 782(11) 1139(5) 121(5) 20(2)C(1) 22366(21) 4155(11) 2422(8) 47(4)C(2) 23087(20) 4204(10) 967(9) 39(4)C(3) 22304(22) 4171(10) 1894(8) 41(4)C(4) 21002(21) 3218(10) 3034(7) 39(4)C(5) 4402(24) 1783(10) 2398(8) 51(5)C(6) 3495(19) 848(9) 1197(7) 28(3)C(7) 2645(16) 864(9) 241(7) 22(3)C(8) 264(20) 1037(9) 2789(7) 35(4)

a U(eq) is defined as one third of the trace of the orthogonalizedUij tensor.

Results and discussion

Although a number of thorium complexes withpolydentate glycolate, oxydiacetate, and related li-gands are known,6 ThBr4(DME)2 appears to be thefirst thorium compound containing a simple, neutralbidentate ether ligand to be structurally character-ized. Moreover, a search of the Cambridge StructuralDatabase (version 5.16, October 1998)7 revealed onlyfour structurally characterized actinide complexesbearing bidentate neutral ether ligands, all of whichare DME derivatives of uranium.8

The eight-coordinate complex ThBr4(DME)2

consists of a central Th atom surrounded by the fourO atoms of two dimethoxyethane ligands and fourBr ligands, located in the A and B sites of an idealizeddodecahedron, respectively.9 The molecular structureof ThBr4(DME)2 is shown in Fig. 1, with selectedbond lengths and angles given in Table 3. The ThUBrdistances in ThBr4(DME)2 [in the range 2.8516(13)–2.8712(13) A] are similar to those observed in other

Structure of ThBr4(DME)2 245

Fig. 1. Molecular structure of ThBr4(DME)2.

Table 3. Selected Bond Lengths (A) and Angles (8) for ThBr4(DME)2

Th(1)UO(1) 2.564(8) Th(1)UO(2) 2.582(8)Th(1)UO(3) 2.581(8) Th(1)UO(4) 2.620(8)Th(1)UBr(1) 2.8712(13) Th(1)UBr(2) 2.8628(12)Th(1)UBr(3) 2.8516(13) Th(1)UBr(4) 2.8633(13)O(1)UTh(1)UO(2) 63.4(2) O(3)UTh(1)UO(4) 64.2(2)Br(1)UTh(1)UBr(3) 104.36(4) Br(1)UTh(1)UBr(2) 82.55(4)Br(1)UTh(1)UBr(4) 149.59(4) Br(2)UTh(1)UBr(3) 150.03(4)Br(2)UTh(1)UBr(4) 107.25(4) Br(3)UTh(1)UBr(4) 81.69(4)

Table 4. Structurally Characterized Complexes with Terminal ThUBr Bonds

Compound d(ThUBr)/A Referencea

ThBr4[OC(Me)NPri2]2 2.829(3) a

ThBr4[OC(NEt2)2]2 2.834(4) aThBr4(THF)4 2.833(2)–2.876(3) bCp*

2Th(THF)Br2 2.895(2) cCp*ThBr(O-2,6-But

2C6H3)2 2.821(2) dCp*

2ThBr2 2.800(2) e[Li(THF)4]2[Th(h5-C2B9H11)2Br2] 2.863(1) & 2.874(1) fThBr4(DME)2 2.8516(13)–2.8712(13) This work

a (a) Al-Daher, A.G.M.; Bagnall, K.W.; Benetollo, F.; Polo, A.; Bombieri, G. J. LessCommon Met. 1986, 122, 167; (b) Clark, D.L.; Frankcom, T.M.; Miller, M.M.;Watkin, J.G. Inorg. Chem. 1992, 31, 1628; (c) Edelman, M.A.; Hitchcock, P.B.; Hu,J.; Lappert, M.F. New J. Chem. 1995, 19, 481; (d) Butcher, R.J.; Clark, D.L.; Grum-bine, S.K.; Scott, B.L.; Watkin, J.G. Organometallics 1996, 15, 1488; (e) Rabinovich,D.; Schimek, G.L.; Pennington, W.T.; Nielsen, J.B.; Abney, K.D. Acta Crystallogr.1997, C53, 1794; (f) Rabinovich, D.; Chamberlin, R.M.; Scott, B.L.; Nielsen, J.B.;Abney, K.D. Inorg. Chem. 1997, 36, 4216.

complexes containing terminal ThUBr groups, assummarized in Table 4. Similarly, the ThUO dis-tances [in the range 2.564(8)–2.620(8) A] are compa-rable to the corresponding values observed in tho-rium complexes bearing oxygen-donor (i.e., ether)ligands.3,6,10 The CUO and CUC bond distances inThBr4(DME)2 [in the ranges 1.44(2)–1.48(2) and1.46(2)–1.52(2) A, respectively] are all unexceptionalfor dimethoxyethane ligands coordinated to metalcenters. There are no unusual intermolecular con-tacts.

Acknowledgments

This work was performed under the auspices ofthe Divisions of Chemical Science and Technologyand Materials Science and Technology, Los AlamosNational Laboratory, which is operated by the Uni-

246 Rabinovich, Scott, Nielsen, and Abney

versity of California for the U.S. Department of En-ergy under contract W-7405-ENG-36. We also thankDrs. Steven K. Grumbine and John G. Watkin(LANL) for a generous gift of ThBr4(THF)4.

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