Reaction of electron-deficient Group 4 metal s-cis-butadiene

Reaction of Electron-Deficient Group 4 Metal s-c/s-Butadiene. Complexes with CO. Bart Hessen, Joop Blenkers,1 and Jan H. Teuben*. Department of Chemis...
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Organometallics 1989,8, 2809-2812

2809

Reaction of Electron-Deficient Group 4 Metal s-cis-Butadiene Complexes with CO Bart Hessen, Joop Blenkers,' and Jan H. Teuben" Department of Chemistry, Rdksuniversiteit Groningen, Ndenborgh 16, 9747 AG Groningen, The Netherlands

Goran Helgesson and Susan Jagner Department of Inorganic Chemistry, Chalmers University of Technology, S-4 12 96, Giiteborg, Sweden Received April 20, 1989

Electronically unsaturated diene complexes Cp*M(diene)Cl (Cp* = q5-CsMes;M = Zr, Hf;diene = 2,3-dimethyl-l,&butadiene,2-methyl-l,3-butadiene)react with CO through an intermediate adduct to form (di)methylcyclopentadieneand [Cp*M(O)Cl],. Incorporation of the CO carbon atom in the cyclopentadiene was confirmed by 13CO-labelingexperiments. The less oxophilic Ti is unable to perform this CO bond cleavage. Cp*Ti(2,3-dimethy1-1,3-butadiene)Clreacts with CO to form the dimeric titanaoxirane (Cp*Ti[p-OCCH2C(Me)=C(Me)CH2]C1),, which was characterized by X-ray analysis (space group Pi,a = 10.293 (3) A, b = 10.445 (2) A, c = 8.409 ( 3 ) A, a = 103.12 (2)O, p = 101.58 (3)O,y = 68.29 (2)' at 170 K, 2 = 1). The molecule contains a highly symmetrical central Tiz02unit, and the C-0 distance of 1.408 (4) A suggests CO reduction to a single C-0 bond. I

i

Introduction A considerable difference in reactivity can often be observed between the 3d and 4d/5d metal congeners of transition-metal complexes. This can be caused by several factors (e.g. differences in ionic radius, electron pairing energy, different intervals between oxidation state^).^ For reactions of early-transition-metal complexes (in casu, group 4 metal compounds) the difference in oxophilicity of the metal centers can be of great influence on the product formation. For example, the metallacyclopentane complexes ( v ~ - C ~ R ~ ) ~ M ((M C H=~Ti, ) , R = H;, M = Zr, R = Me) react with CO to form CpzTi(CO)2and cyclopentanone for M = Ti: while for M = Zr an enolate-hydride complex is produced, in which a Zr-0 bond is retained., Reactions of CpzZr(l,3-diene)with CO are assumed to form products similar to the latter, from which cyclopentenones can be obtained following acid~lysis.~ In this paper we report the reactions of electronically unsaturated 14e 1,3-diene complexes Cp*M(1,3-diene)Cl (Cp* = $-CsMe5; M = Ti, Zr, Hf; diene = 2,3-dimethyl1B-butadiene;2-methyl-l,3-b~tadiene)~J with CO. For the Zr and Hf complexes complete CO bond cleavage is observed, while for the less oxophilic Ti reduction to a C-0 single bond takes place. Parts of this study have been communicated earliera6

Results Reaction of Cp*M(1,3-diene)Cl(M = Zr, Hf) with CO. When the 14-electron diene complexes Cp*M(1,3diene)Cl (M = Zr, diene = 2,3-dimethyl-l,3-butadiene (1); M = Hf, diene = 2,3-dimethyl-1,3-butadiene(2), 2(1)Present address: The Inspectorate for the Environment for North Brabant, P.O. Box 9134,5200MA 's Hertogenbosch, The Netherlands. (2)(a) Cardin, D.J.; Lappert, M. F.; Raston, C. L. Chemistry of Organo-Zirconium and -Hafnium Compounds; Ellis Horwood: Chichester, 1986;pp 18-19. (b) Cotton, F. A,; Wilkinson, G. Aduanced Inorganic Chemistry; Wiley: New York, 1988;pp 776-777. (3)McDermott, J. X.; Wilson, M. E.; Whitesides, G. M. J.Am. Chem. SOC. 1976,98,6529. (4)Manriquez, J. M.; McAllister, D. R.; Sanner, R. D.; Bercaw, J. E. J. Am. Chem. SOC. 1978,100,2716. (5)Erker,. G.: . Ennel.. K.:. Kroner,. C.:. Chiang. -. A.-P. Chem. Ber. 1982, 115,3311. (6)Blenkers.. J.:, de Liefde Meiier. H. J.: Teuben. J. H. Or~anometallics 1983;2,1483. (7)Blenkers, J.; Hessen, B.; van Bolhuis, F.; Wagner, A. J.; Teuben, J. H.Organometallics 1987,6, 459. I

I

-

1

methyl-1,3-butadiene (3)) are reacted with CO (1atm) at ambient conditions in aromatic solvents, an uptake of 1 mol of CO/mol of metal complex is observed. Concomitantly a white solid is formed, which was characterized by elemental analysis and NMR spectroscopy as [Cp*M(O)Cl],. From the solution (di)methyl-substituted cyclopentadienes could be obtained in 70430% yield (eq 1). The organic products were characterized by their 'H and 13C NMR spectra and comparison with authentic samples.8 Cp*M(diene)Cl 1: M =

+

-

*co

Zr,diene = 2,3-dimethyl-l,3-butadiene

2: M = Hf, diene = 2,3-dimethyl-1,3-butadiene 3: M = Hf, diene = 2-methyl-l,3-butadiene

d'

R

l/n[Cp*M(O)Cl],

+

(1)

-%

R = H, Me

Use of 13C-labeledcarbon monoxide in a reaction with

2 showed by a sharp increase in intensity of the I3C NMR resonance at 6 129.4 ppm that the CO carbon atom is incorporated in the 4-position of the formed 1,2-dimethyl-l,3-~yclopentadiene.Subsequent isomerization to [5-13C]-2,3-dimethyl-l,3-cyclopentadiene was observed by a slow decrease in intensity of the mentioned resonance and the appearance of a new resonance a t 6 39.3 ppm (t, 125 Hz). The reaction between 2 and CO was monitored by solution IR spectroscopy. Immediately after the admission of CO a strong sharp absorption was observed at 2114 cm-'. This indicates the formation of an intermediate adduct, Cp*Hf(2,3-dimethyl-l,3-butadiene)ClCO.The adduct is unstable, and the vibration disappears again in several minutes. Simultaneouslyweak absorptions appear at 1589 and 1630 cm-l, which are assigned to the symmetric and asymmetric CC frequencies of the formed 1,2-dimethyl1,3-~yclopentadiene.~ Reaction of Cp*Ti(2,3-dimethyl-l,3-butadiene)C1(4) with CO. When CO (1 atm) is admitted to a toluene solution of 4 at 20 OC, a greenish brown material precipitates, which is very poorly soluble in various organic

I

(8) Skattebd, L. Tetrahedron 1967,23,1107.

0276-7333/89/2308-2809$01.50/00 1989 American Chemical Society

Hessen et al.

2810 Organometallics, Vol. 8, No. 12, 1989

L

Table I. Interatomic Distances (A) and Angles (deg) in

[Cp*Ti(r-OCCH,C(Me)=(Me)CH,)CIl,(5)a Ti-Cl Ti-0 Ti-O(i) Ti-C(1) Ti-Ti (i) Ti-C(8) Ti-C(9) Ti-C(10) Ti-C(11) T i 4 (12) Ti-X O-C(l) C(l)-C(2) C(2)-C(3) C(3)-C(4)

Figure 1. Molecular structure of (Cp*Ti[pOCCH,C(Me)=C7

(Me)CH21C112(5).

solvents. An NMR tube experiment showed that no significant amounts of soluble (organometallic or organic) products are formed. Elemental analysis indicated the presence of one CO per unit of 4 in the product. The IR spectrum contained no CO vibrations above 1300 cm-', suggesting a considerable reduction in CO bond order. When the reaction was performed under controlled conditions, crystalline aggregates were obtained that provided material suitable for X-ray analysis. The X-ray structure determination (Figure 1; bond distances and angles in Table I) showed that the product is the dimeric titanaoxirane (Cp*Ti[p-OCCH2C(Me)=C(Me)CH2]C1J2 (5, eq 2). The molecule is centered around a planar Ti202ring I

i

-

Cl-Ti-O Cl-Ti-O(i) C1-Ti-C( 1) C1-Ti-X 0-Ti-O(i) 0-Ti-C( 1) 0-Ti-X O(i)-Ti-C(1) O(i)-Ti-X C( 1)-Ti-X Ti-0-Ti(i) Ti-O-C(l) C(l)-O-Ti(i) Ti-C( 11-0 Ti-C( 1)-C(2) Ti-C( 1)-C(5) o-C(l)-C(2) O-C(l)-C(5) C(2)-C(l)-C(5) C(1)-c(2)-c(3) C(2)-C(3)-C(4)

2.315 (1) 2.012 i2j 1.996 (2) 2.094 (3) 3.114 (1) 2.357 (3) 2.381 (3) 2.409 (3) 2.393 (3) 2.340 (3) 2.046 1.408 (4) 1.534 (4) 1.512 (4) 1.319 (4) 89.17 (6) 110.21 (6) 102.32 (8) 111.0 78.02 (8) 40.04 (9) 153.8 108.30 (9) 108.5 116.3 101.98 (8) 73.1 (1) 139.8 (2) 66.8 (1) 131.2 (2) 115.7 (2) 115.6 (2) 113.8 (2) 107.2 (2) 103.9 (2) 112.6 (2)

C(4)-C(5)

ci5j-ciij C(3)-C(6) C(4)-C(7) C(8)-CW C(9)-C(lO) C(l0)-C(l1) c(11)-C( 12) C(l2)-C(8) C(8)-C (13) C(9)-C (14) C(lO)-C( 15) C(11)-C( 16) C(12)-C(17)

1.511 (4) 1.532 (4) 1.496 (4) 1.501 (4) 1.419 (4) 1.423 (4) 1.401 (4) 1.438 (4) 1.420 (4) 1.506 (4) 1.494 (4) 1.493 (4) 1.490 (4) 1.493 (4) 119.3 (3) 128.1 (3) 112.1 (2) 128.8 (3) 119.1 (2) 104.2 (2) 107.5 (2) 127.3 (2) 124.6 (2) 108.5 (2) 125.8 (3) 125.6 (3) 108.1 (2) 125.8 (2) 126.0 (2) 108.1 (2) 126.8 (2) 125.1 (2) 107.7 (2) 125.3 (2) 126.9 (2)

Estimated standard deviations are given in parentheses. Symmetry code (i): 1 - x , y, Z. X is the center of gravity of the fivemembered ring C@)-C(lZ).

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Discussion Complete CO bond cleavage is observed in the reaction 4 of Cp*M(l,S-diene)Cl (M = Zr, Hf) with CO. The CO carbon atom is incorporated into a substituted cyclof/z(Cp*Ti[p-OCCH2C(Me)=C(Me)CH2]C1J2 (2) 5 pentadiene, while the oxygen atom remains bound to the metal center in [Cp*M(O)Cl],. The structure of the latter with the Cp* ligands in a trans arrangement. The Ti202 is probably oligomeric, in view of the poor solubility in ring is highly symmetrical, with nearly equivalent Ti-0 hydrocarbon solvents. The metal centers are likely to be distances ( T i 4 = 2.012 (2) A, Ti-0' = 1.996 (2) A). The linked by p - 0 bridges, as is the case in the cyclotetrameric C(1)-0 distance of 1.408 (4) A is comparable to those in Ti complex [ (C5H4Me)Ti(p-O)C1],." The reaction with Ti alkoxides like Cp2Ti(OEt)C1(1.415 (4) A),9 and demCO is initiated by CO adduct formation. The uco vibration onstrates the reduction to a single C-0 bond. These at 2114 cm-' in 2CO is found at higher wavenumbers than features differ considerably from those in the strongly those in d2Hf(I1) carbonyls like Cp*2Hf(CO)2(1940,1844 asymmetrical [Cp2Ti(p-OCCPh2)12molecule ( T i 4 = 2.037 cm-l)12or ( T ~ - C ~ R ~ ) H ~ ( C O ) ~ C ~ ( M ~(R~= PCH~CH~P (2) A, Ti-0' = 2.250 (3) A, C-0 = 1.311 (4) &,lo the only H,13 1950, 1870 cm-'; R = Me,14 1914, 1801 cm-') but is other known dimeric titanaoxirane complex. Another closer to the vibration observed in the do Hf(1V) adduct prominent feature in the structure of 5 is the dihedral angle Cp*2HfH2(CO)(2036 cm-l).15 This appears to support our between the Ti,O,O' and Ti,O,C(l) planes of 138.7 (l)', earlier finding that the diene complexes Cp*M(l,3-&ene)Cl causing C(1) to move 0.889 (3) A out of the Ti202plane and their Lewis base adducts have a considerable amount toward the Cp* group bound to the same Ti atom. Steric of a2,r-metallacyclopentenecharacter and often behave interaction between the dimethylcyclopentenylgroup with effectively as do Cp*MCl dialkyls.16 the C(13) methyl group of the Cp* ligand is apparent from the displacement of C(13) (0.209 (4) A) out of the C(8)C(l2) least-squares plane, which is much larger than those (11) Petersen, J. L. Inorg. Chem. 1980, 19, 181. (12) Sikora, D. J.; Rausch, M. D.; Rogers, R. D.; Atwood, J. L. J. Am. observed for the other methyl carbon atoms (ranging from Chem. SOC.1981,103, 1265. 0.078 (4) to 0.011 (4) A). (13) Wielstra, Y.; Gambarotta, S.; Roedelof, J. B.; Chiang, M. Y. Or-

Cp*Ti(2,3-dimethyl-1,3-butadiene)Cl + CO

ganometallics 1988, 7, 2177. (14)Stein, B. K.; Frerichs, S. R.; Ellis, J. E. Organometallics 1987, 7 ,

(9) Huffman, J. C.; Moloy, K. G.; Marsella, J. A.; Caulton,K. G. J.Am. Chem. SOC.1980,102, 3009. (10) Fachinetti, G.; Biran, C.; Floriani, C.; Chiesi-Villa, A.; Guastini, C . J.Am. Chem. SOC.1978,100, 1921.

2017.

(15) Marsella, J. A.; Curtis, C. J.; Bercaw, J. E.;Caulton, K. G. J. Am. Chem. SOC.1980,102, 7244. (16) Hessen, B.; Teuben, J. H. J. Organomet. Chem. 1988,358, 135.

Reaction of Metal s-&Butadiene

Organometallics, Vol. 8,No. 12, 1989 2811

Complexes with CO

Scheme I

Table 11. Fractional Coordinates and Equivalent Isotropic Thermal Parameters (Az)for the Non-Hydrogen Atoms in

,

[Cp*Ti(a-OCCH&(Me)=C(Me)CH2)ClII atom Ti C1

0 L

(C)

U

J

(A)

(8)

Cp*Ti(1,3-diene)Cldoes not perform CO bond cleavage but forms a titanaoxirane in which the CO linkage is reduced to a single C-0 bond. This reduction appears to be more efficient than that observed in the Cp,Ti oxirane [CpzTi(p-OCCPhz)]z,10 and the structure of 5 resembles more the zirconaoxirane complexes [Cp,Zr(p-OCPh,)]z (C-O = 1.425 (4) A)" and {(~8-C8H~Zr[~-OC(C,Me3H2)21)2 (C-0 = 1.45 (1)A)18 in this respect. The reactivity of group 4 1,3-diene/metallacyclopentene complexes with CO can be described according to Scheme I. After initial adduct formation insertion of CO into the metal-diene bond takes place to give an acyl/oxycarbene intermediate. Insertion of the oxycarbene into the remaining M-C bond produces a metallaoxirane (A). @-Htransfer converts this into an enolate-hydride (B). If thermodynamically favorable, apparently a kinetic pathway exists that exchanges the M-H and the C-0 bond in B for a C-H and a second M-O bond. It appears possible by modifying the L,M fragment to stop this reaction sequence in the various stages: A (L,M = Cp*TiCl),B (L,M = Cp*,Zr), or C (L,M = Cp*MCl; M = Zr, Hf).

Experimental Section General Considerations. All manipulations were carried out under nitrogen by using Schlenk, glovebox, and vacuum line techniques. All solvents (except CDC13,which was dried over 4-A molecular sieves and vacuum transferred) were distilled from Na/K alloy under nitrogen before use. Compounds 1-4 were prepared according t o ref 7. CO (Matheson) and 13C0 (MSD) were used as purchased. Gas uptakes were measured with a gas burette equipped with a photosensor and an automatic relay control circuit for maintaining constant pressure in the system by use of a motor-driven gastight syringe. NMR spectra were recorded at 200 MHz ('H) or 50.3 MHz on a Nicolet NT-200 spectrometer and a t 60 MHz ('H) on a Perkin-Elmer R-24B spectrometer. IR spectra were recorded (unless stated otherwise) from Nujol mulls between KBr disks on a Pye-Unicam SP3-300 spectrophotometer. For monitoring the reaction between 2 and CO this was equipped with a (high-pressure) liquid cell designed by W. R. Beukema and H. Tams. Elemental analyses were performed a t the microanalytical department of the chemical laboratories, Groningen University, Groningen, The Netherlands. All values are the average of a t least two independent determinations.

('v)

Reaction of Cp*M(l,S-diene)Cl(M = Zr, Hf;1-3) with CO. A suspension of 0.37 g (0.89 mmol) of 3 in 0.6 mL of benzene-d6 was exposed t o CO (1atm) at room temperature. The color of the suspension changed from yellow to white. The gas uptake (17) Erker, G.; Dorf, U.; Czisch, P.; Petersen, J. L. Organometallics

1986,5,668.

(18)Stella, S.;Floriani, C. J . Chem. SOC.,Chem. Commun. 1986, 1053.

C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(l0) C(11) C(l2) C(13) C(14) C(15) C(l6) C(17)

X

Y

2

0.41468 (5) 0.45592 (7) 0.6141 (2) 0.6063 (3) 0.6561 (3) 0.7627 (3) 0.7786 (3) 0.6847 (3) 0.8334 (4) 0.8707 (4) 0.3155 (3) 0.2689 (3) 0.1809 (3) 0.1726 (3) 0.2581 (3) 0.3932 (4) 0.2980 (4) 0.1038 (4) 0.0884 (3) 0.2769 (4)

0.15953 (5) 0.22228 (7) 0.0251 (2) 0.1344 (3) 0.0894 (3) 0.1607 (3) 0.2359 (3) 0.2309 (3) 0.1425 (4) 0.3244 (4) 0.3041 (3) 0.3972 (3) 0.3271 (3) 0.2271 (3) 0.2326 (3) 0.4000 (4) 0.5180 (3) 0.3605 (4) 0.1325 (3) 0.1441 (4)

0.02160 (6) -0.20566 0.0404 (2) (8) 0.1757 (3) 0.3454 (3) 0.4244 (3) 0.3278 (3) 0.1651 (3) 0.5954 (4) 0.3623 (4) 0.2335 (3) 0.0858 (3) -0.0205 (3) 0.0597 (3) 0.2174 (3) 0.3859 (4) 0.0526 (5) -0.1846 (4) -0.0029 (4) 0.3425 (4)

4" 1.59 (1) 2.32 (2) 2.03 (6) 2.06 (8) 2.37 (9) 2.38 (9) 2.12 (8) 2.24 (9) 3.3 (1) 3.0 (1) 2.15 (8) 2.15 (8) 2.17 (8) 1.95 (8) 2.00 (8) 3.0 (1) 3.0 (1) 3.0 (1) 2.7 (1) 2.7 (1)

aB, = ( 8 ~ ~ / 3 ai*aj*ai.ai. ) ~ ~ ~ ~ U ~ ~ was monitored with an automatic gas burette, and a consumption of 0.85 mmol (0.96 mol/mol of 3) of CO was observed. After 4 h the volatile5 were collected in a cold trap. This solution contained a 1:l mixture of 1-methyl- and 2-methyl-1,3-cyclopentadiene (total 0.71 mmol, 80%, analyzed by GC and NMR spectroscopy, and comparison with an authentic sample). The residual white solid was washed with pentane, dried in vacuo, and identified as [Cp*Hf(O)Cl],; yield 0.25 g (80%); 'H NMR (60 MHz, 34 "C, CDClJ 6 2.15 (8). Anal. Calcd for CloH16C10HE C, 32.89; H, 4.14; C1,9.80; Hf, 48.87. Found: C, 33.08; H, 4.19; C1,9.71; Hf, 48.31. A similar procedure was used in the carbonylation of 1 and 2, resulting in [Cp*M(O)Cl], (70-80%) and 1,2-dimethyl-1,3cyclopentadiene (60-75%). The latter was characterized by ita NMR and mass spectra and comparison with an authentic sample? 'H NMR (200 MHz, benzene-& 20 "C) 6 6.25 (m, 2 H, =CH), 2.76 (br, 2 H, CH,), 1.87 (s,6 H, Me); *%NMR (50.3 MHz, benzene-d6, 20 "C) 6 136.9 (d, 160 Hz, CH2CH=CH), 135.6 (s, =CMe), 134.7 (s,=CMe), 129.4 (d, 165 Hz,CH&H==CH),45.8 (t, 124 Hz, CH2), 13.1 (9,127 Hz, Me), 12.6 (9,127 Hz, Me); MS m / e 94 (M+). The reaction between 2 and CO was monitored by IR spectroscopy in a specially designed IR liquid cell in which 12 mL of an 0.1 M solution of 2 in pentane was continuously circulated under 1 atm of CO. The reaction of 2 with I3CO was performed in benzene-d6 in a sealed NMR tube and monitored by 13C NMR.

Reaction of Cp*Ti(2,3-dimethyl-1,3-butadiene)C1(4)with CO. 4 (0.28 g, 0.93 mmol) was dissolved in 10 mL of toluene. On a vacuum line 0.99 mmol of CO was admitted t o the solution, which was then allowed t o stand a t 20 "C for 16 h (no stirring or other disturbance). A brown solution with dark brown crystalline aggregates had formed. The mother liquor was decanted, and the crystals were washed twice with 5 mL of pentane. After the product was dried 0.10 g (0.15 mmol, 32%) of analytically pure 5 was isolated. This procedure does not produce an optimal yield but enables the isolation of crystalline material, suitable for X-ray analysis: IR 2730 (vw),2720 (vw),1498 (vw),1310 (w), 1290 (mw), 1212 (w), 1183 (sh), 1172 (s), 1087 (vs), 1057 (mw), 1025 (mw), 1010 (w), 825 (vs), 760 (s), 653 (m), 505 (sh), 490 (s), 462 (m), 405 (s) cm-l. Anal. Calcd for CUH&l2O2Ti2: C, 62.11; H, 7.67; C1, 10.78; Ti, 14.57. Found: C, 62.42; H, 7.84; C1, 10.82; Ti, 14.50. X-ray Structure Determination of 5. Crystal Data and Data Collection. A crystal with maximum dimensions 0.27 X 0.22 X 0.44 mm, obtained as described above, was moun_ted in epoxy resin. 5 crystallizes in the triclinic space group P1, a = 10.293 (3) A, b = 10.445 (2) A, c = 8.409 (3) A, a = 103.12 (2)", fl = 101.58 (3)", y = 68.29 (2)", 2 = 1, de+ = 1.35 g cm-', and ~ ( MK o a ) = 7.05 cm-'. Diffracted intensities (+h,hk,hl)were measured in a stream of nitrogen of approximately 170 K for 3.5

2812

Organometallics 1989, 8, 2812-2816

< 28 < 50° with a Synthex P2, diffractometer,using graphitemonochromated Mo Ka radiation and the w-2B scan mode with a variable 28 scan rate of 2.5-15.0° min-*. A 96-step profile was recorded for each reflection, and intensities were calculated according to ref 19 and 20. Of the 2866 independent reflections measured, 2395 had I > 30(I) and were regarded as observed. Monitoring two reference reflections at regular intervals (after every 48 reflections measured) showed no decay of the crystal. Intensity data were corrected for Lorentz and polarization effects but not for absorption. Unit-cell parameters were obtained from diffractometer setting angles for 15 reflections. Structure Determination and Refinement. The coordinates of the titanium and chlorine atoms were obtained from the Patterson function and those of the carbon and oxygen atoms from a subsequent electron-densitymap. Full-matrix least-squares refinement of positional and isotropic thermal parameters and, subsequently, anisotropic thermal parameters yielded R = 0.063 (181parameters). Inclusion of positional and thermal parameters for the hydrogen atoms, located from the difference maps, gave a final R of 0.038 and R, of 0.044 for 281 parameters and 2395 reflections. Atomic scattering factors were taken from ref 21, and (19) Lehmann, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974, 30, 580. (20) Lindqvist, 0.; Ljungstrom, E. J. Appl. Crystallogr. 1979,12,134.

the F,,values were weighted according to w = [02(Fo) + 0.0009F~]-1.A final difference map showed a maximum residual density of 0.50 e .k3.The computer programs used are described in ref 22 and 23. Fractional coordinates and equivalent isotropic thermal parameters are listed in Table 11.

Acknowledgment. This work was supported by the Netherlands Foundation for Chemical Research (SON) with financial aid from the Netherlands Organization for Scientific Research (NWO). Supplementary Material Available: Tables of anisotropic thermal parameters for the non-hydrogen atoms, thermal and positional parameters, and bond distances for the hydrogen atoms for 5 (3pages);a listing of observed and calculated structure factors for 5 (14 pages). Ordering information is given on any current masthead page. (21) International Tables for X-ray Crystallography; Kynoch Press: Birmingham, 1974; Vol. IV. (22) Lindgren, 0. Ph.D. Thesis, Department of Inorganic Chemistry, Chalmers University of Technology and University of Gbteborg, Goteborg, Sweden, 1977. (23) Andersen, L. Ph.D. Thesis, Department of Inorganic Chemistry, Chalmers University of Technology and University of Gbteborg, Goteborg, Sweden, 1985.

Synthesis and Spectral Properties of Bis(alkyltelluro)ethynes, RTeC=CTeR (R = Me, Et) Robert W. Gedridge, Jr.," Kelvin T. Higa, Daniel C. Harris, Robin A. Nissan, and Melvin P. Nadler Chemistry Division, Research Department, Na Val Weapons Center, China Lake, California 93555 Received February 28, 1989

The reaction of equimolar amounts of (EDA)LiC=CH (EDA = ethylenediamine) and Te metal in tetrahydrofuran (THF) followed by treatment with RI (R = Me and Et) produces MeTeCECTeMe and EtTeCECTeEt in 71% and 62% yields, respectively, based on Te (or 36% and 31% yields, respectively, based on (EDA)LiC=CH) from an aqueous ammonium chloride workup. Gas chromatographic analysis of the reaction atmosphere of (EDA)LiC=CH with Te metal in a 1:l molar ratio indicated that approximately half of the (EDA)LiC=CH was converted to HC=CH. In order to avoid the loss of half of the (EDA)LiCECH reagent, MeTeCECTeMe was produced in 61% yield based on Te (or 59% yield based on (EDA)LiC=CH) from the reaction of equimolar amounts of (EDA)LiCECH, n-BuLi, and EDA in THF followed by treatment with 2 equiv of Te and MeI. (EDA)LiTeC=CTeLi(EDA) is the postulated species that yields bis(alkyltel1uro)ethynes when treated with an alkyl iodide. The bis(alkyltel1uro)ethynes were characterized by 'H, 13C, and 12TeNMR, IR, Raman, ultraviolet, and mass spectroscopies as well as the reaction with vanadocene.

Introduction Organotellurium compounds have useful applications in organic synthesis' and the growth of semiconductor Volatile organotellurium compounds, which py(1)(a) Irgolic, K. J. The Organic Chemistry of Tellurium; Gordon and Breach Science: New York, 1974. (b) Engman, L. Acc. Chem. Res. 1985, 18, 274. (c) Petragnani, N.; Comasseto, J. V. Synthesis 1986, 1. (d) Suzuki, H.; Hanazaki, Y. Chem. Lett. 1986, 549. (2) (a) Hoke, W. E.; Lemonias, P. J.; Traczewski,R. Appl. Phys. Lett. 1984,44,1046. (b) Hoke, W. E.; Lemonias, P. J. Appl. Phys. Lett. 1985, 46,398. (c) Hoke, W. E.; Lemonias, P. J. Appl. Phys. Lett. 1986,48,1669. (d) Kisker, D. W.; Steigerwald, M. K.; Kometani, T. Y.; Jeffers, K. S. Appl. Phys. Lett. 1987,50, 1681. (e) Lichtmann, L. S.; Parsons, J. D.; Cirlin, E.-H. J. Cryst. Growth 1988,86, 217. (0 Parsons, J. D.; Lichtmann, L. S. J. Cryst. Growth 1988,86, 222. (g) Hoke, W. E.; Lemonias, P. J.; Korenstein, R. J. Mater. Res. 1988, 3, 329.

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rolytically or photolytically decompose to tellurium metal at lower temperatures, are essential in the growth of high-quality mercury cadmium telluride semiconductor films. Lower film growth temperatures can be achieved by using alternative organotellurium source compounds2 and photoassisted metal-organic chemical vapor depo~ i t i o n .Our ~ research has focused on developing photosensitive organotellurium source compounds with sufficient (3) (a) Inine, S. J. C.; Mullin,J. B. J. Cryst. Growth 1981,55,107. (b) Mullin, J. B.; M e , S. J. C. J. Vac. Sci. Technol. 1982,21,178. (c) M e , S. J. C.; Tunnicliffe, J.; Mullin, J. B. J.Cryst. Growth 1983,65,479. (d) Morris, B. J. Appl. Phys. Lett. 1986,48,867. (e) Ahlgren, W. L.; Smith, E. J.; James, J. B.; James, T. W.; Ruth, R. P.; Patten, E. A.; Knox, R. D.; Staudenmann, J.-L. J. Cryst. Growth 1988,86, 198. (0 Irvine, S. J. C.; Mullin, J. B.; Hill, H.; Brown, G. T.; Barnett, S. J. J. Cryst. Growth 1988, 86, 188.

0 1989 American Chemical Society