Activation of Ethers and Sulfides by Organolanthanide Hydrides

Owen T. Summerscales , Cameron M. Moore , Brian L. Scott , Marianne P. Wilkerson ..... Auke Meetsma, Sergei I. Troyanov, Bart Hessen, and Jan H. Teube...
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Organometallics 1995, 14,2306-2317

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Activation of Ethers and Sulfides by Organolanthanide Hydrides. Molecular Structures of (Cp*2Y)2@-OCH2CH20)(THF)2 and (Cp*2Ce)2@-O)(THF)2 Berth-Jan Deelman,? Martin Booij,' Auke Meetsma,? Jan H. Teuben,*>t Huub Kooijman,t and Anthony L. SpektJ Groningen Center for Catalysis and Synthesis, Department of Chemistry, University of Groningen, NGenborgh 4,9747 A G Groningen, The Netherlands, and BGvoet Center for Biomolecular Research, Crystal and Structural Chemistry, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands Received December 27, 1994@ Dialkyl ethers, ROR, are cleaved by hydrides (Cp*zLnH)z (Ln = Y la,La lb,Ce IC)to form alkoxides Cp*ZLnOR (2),Cp*ZLnOR, R H , and RH. The extent to which either of the C-0 bonds of asymmetric substituted dialkyl ethers ROR is attacked strongly depends on the alkyl substituents but is relatively insensitive to the nature of the metal. Ring opening is observed with THF or 1,Cdioxane leading to Cp*zYO"Bu (6a)and (C~*ZY)Z~-OCHZCHZO)(THF)2 (8),respectively. The molecular structure of 8 was determined by X-ra diffraction. Space group Pbcn had unit cell parameters a = 21.7483(12) b = 14.2806(12) c = 16.726(2) and 2 = 4. Least-squares refinement based on 4163 reflections converged to R = 0.063. Unsaturated ethers, vinyl ethyl ether and allyl ethyl ether, are cleaved instantaneously by la to form C P * ~ Y O E ~Also, . the C-0 bonds of Cp*zLnOEt are attacked by (Cp"2LnH)z to give the oxo bridged compound (Cp*,Ln)z@-O) and ethane. The molecular structure of the THF adduct of the cerium analogue (Cp*ZCe)&-O)(THF)2 (12)was determined by X-ray diffraction: spacegroup P i had unit cell parameters a = 13.399(2) b = 14.864(4) c = 15.812(6) a = 70.75(2)", p = 85.15(2)", y = 63.78(2Y, and 2 = 2. Least-squares refinement based on 6294 reflections converged to R = 0.038. In contrast to ethers, organic sulfides R S R are metallated by la to produce products Cp*zYCHzSMe (13,R = R = Me), Cp*2YCH(SMe)Ph (15,R = Me, R = Ph), Cp*2Y(SCdH3) (18,R R = CH=CHCH=CH), and dihydrogen. Only Et2S underwent C-S cleavage to form Cp*ZYSEt (16)and ethane. Reaction of la with allyl methyl sulfide is not clean, but la is a modest catalyst for the hydrogenation of allyl methyl sulfide.

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Introduction Organometallic compounds of group 3 and lanthanide metals are very active catalysts for polymerization' and hydrogenation2 of olefins. Also, cyclization of 1,4-, 1,5-, and 1,6-dienes is very efficiently catalyzed by scandium and yttrium ~omplexes.~ However, in general, these catalytic processes have severe limitations, since they can only be performed with nonfunctionalized olefins. +University of Groningen. University of Utrecht. Address correspondence pertaining to crystallographic studies of compound 8 to this author. Abstract published in Advance ACS Abstracts, April 15, 1995. (1)(a) Thompson, M. E.; Baxter, S. M.; Bulls, A. R.; Burger, B. J.; Nolan, M. C.; Santarsiero, B. D.; Schaefer, W. P.; Bercaw, J. E. J . Am. Chem. SOC.1987,109,203. (b) Watson, P. L.; Parshall, G. W. Acc. 1982, Chem. Res. 1985,18, 51. (c) Watson, P.L. J. Am. Chem. SOC. (e) Jeske, 104,337.(d) Watson, P.L. J . Am. Chem. Soc. 1982,104,6471. G.; Lauke, H.; Mauermann, H.; Swepston, P. N.; Schumann, H.; Marks, 1985,107,8091.(0 Bunel, E.;Burger, B. J.; T. J . J . Am. Chem. SOC. Bercaw, J . E. J. Am. Chem. SOC.1988,110,976.(g) Burger, B. J.; Thompson, M. E.; Cotter, W. D.; Bercaw, J . E. J. Am. Chem. SOC.1990, 112,1566. (2) (a)Jeske, G.; Lauke, H.; Mauermann, H.; Schumann, H.; Marks. T. J . J . Am. Chem. SOC.1985,107,8111.(b) Conticello, V. P.; Brard, L.; Giardello, M. A,; Tsuji, Y.; Sabat, M.; Stern, C. L.; Marks, T. J. J . Am. Chem. SOC. 1992,114,2761. (3) (a) Bunel, E.; Burger, B. J.; Bercaw, J. E. J . Am. Chem. SOC. 1988,110,976.(b) Molander, G. A,; Hoberg, J. 0. J . Am. Chem. SOC. 1992,114,3123. @

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Only very recently have some examples appeared of catalytic conversions of olefins bearing functional groups. For instance, the hydrogenation of olefins with ether the and thioether functions can be a ~ h i e v e d . Also, ~ cyclization of some functionalized dienes starting from Cp*ZYMe(THF)can be performed without severe deactivation of the catalyst.3b The living polymerization of methyl methacrylate (MMA) by organolanthanidesshows that in some cases even carbonyl groups are t ~ l e r a t e d . ~ Some examples of C-X activation have been reported. For instance, the activation of alkyl halides leading to selective dehalogenation has been studiede6 Several authors have reported on C-0 cleavage, which resulted in the formation of Ln-0 bonds.7 The question remains (4)Molander, G.A,; Hoberg, J. 0. J . Org. Chem. 1992,57,3266. (5)Yasuda, H.;Yamamoto, H.; Yokota, K.; Miyake, S.; Nakamura, A. J . Am. Chem. SOC.1992,114,4908. (6)(a) Schumann, H. Angew. Chem. 1984,96,475,and references cited therein. (b) Finke, R. G.; Keenan, S. R. Organometallics 1989,8, 263.(c) Watson, P.L.; Tulip, T. H.; Williams, I. Organometallics 1990, 9, 1999. (d) Burns, C. J.; Andersen, R. A. J . Chem. Soc., Chem. Commun. 1989,136.(e) Deacon, G.B.; MacKinnon, P. I. Tetrahedron Lett. 1984, 25, 783. (0 Yasuda, H.; Yamamoto, H.; Yokota, K.; Nakamura, A. Chem. Lett. 1989,1309. (7)(a) Evans, J . E.; Ullibarri, T. A,; Ziller, Z. W. Organometallics 1991,10,134.(b) Watson, P.L. J . Chem. Soc., Chem. Commun. 1983, 276.(c) Evans, W. J.;Chamberlain, L. R.; Ulibarri, T. A,; Ziller, J. W. J . Am. Chem. SOC.1988,110,6423.(d) Evans, J. W.; Dominguez, R.; Hanusa, T. P. Organometallics 1986,5,1291.

0276-733319512314-23Q6$Q9.QQ/Q 0 1995 American Chemical Society

Activation of Ethers and Sulfides Table 1. Results of the Ether Cleavage Reactions with (Cp*zLnH) (Cp*zLnH)z

ROR

Cp*zLnOR, Cp*zLnOR

2a Cp*zYOEt 3b Cp*zLaOEt(EtzO) 3c Cp"zCeOEt(Etz0)

la lb IC

la la

4 a Cp*zYOMePBuOMe) 2a Cp*zYOEt 5a Cp*zYOtBu (1:U 6a Cp*zYO"Bu 4b Cp*zLaOMe(tBuOMe) 2b Cp*zLaOEt 5b Cp*zLaOtBu (2:3) 6b Cp*zLaO"Bu("BuOEt)

la lb lb lb

why some functional groups are tolerated in catalytic cycles and others are not. To understand the processes involved, we started a program directed to the interaction of some well-known catalytically active lanthanide hydride complexes (Cp*zLnH)z (Ln = Y, La, and Ce) with molecules R-X (X = OR, SR, NR2, PR2, COOR, CONR2, etc.). In this study we focus on C - 0 and C-S-containing molecules. Selective C-0 cleavage by transition metal complexes can have considerable impact on organic synthesis.8 For instance, the zirconium-mediated deprotection of allyl-protected hydroxyl functions was recently C-S bond activation is especially r e p ~ r t e d . Also, ~ interesting because of its relevance t o hydrodesulfurization (HDS).1° Recently we showed that C-H activation can compete effectively with C-X activation in substituted arenes.ll We now direct our attention to nonaromatic and heteroaromatic substrates. In particular, the possible competition between C-C, C-H, and C-X activation is an interesting subject. Results Activation of Ethers. In an exploratory study the interactions of group 3 and lanthanide hydrides (Cp*2LnH)2 (Ln = Y (la),La (lb),Ce (IC))with ethers (ROR) were monitored by lH NMR (0.03-0.08 M, benzene-ds, room temperature). Later, some of the experiments were carried out on a preparative scale. In general, clean reactions were observed with formation of alkoxides Cp*zLnOR, Cp*aLnOR, and alkanes (eq 1, Table 1). ( C P ' ~ L ~ H+ )2~ROR l a : Ln = Y l b : Ln = La IC: Ln = Ce

-

C P * ~ L ~ O+ R C P * ~ L ~ O+RR' H + RH (1)

For yttrium, splitting of Et20 was quantitative when 1 equiv of Et20 per Y was applied. Addition of an excess

of Et20 resulted in the formation of adduct Cp*zYOEt(Et2O) (3a). For lanthanum and cerium the products Cp*zLnOEt show an increased tendency to complex Et20, resulting in the formation of the adducts Cp*zLnOEt(Et20). Dissociation of Et20 in these adducts appears to be difficult because the complexed ether is (8)Yamamoto, A. Adu. Orgunomet. Chem. 1992, 34, 111. (9) Ito, H.; Taguchi, T.; Hanzawa, Y. J. Org. Chem. 1993, 58, 774. (10)(a) Wiegand, B. C.; Friend, C. M. Chem. Reu. 1992,92,491. (b) Angelici, R. J.;Chol, M.-G. Organometallics 1993,11,3328.(c) Rosoni, G. P.; Jones, W. D. J. Am. Chem. Soc. 1992, 114, 10767.

(11)Booij, M.; Deelman, B.-J., Duchateau, R.; Postma, D. S. Meetsma, A.; Teuben, J. H. Organometallics 1993, 12, 3531.

Organometallics, Vol. 14,No.5, 1995 2307 unavailable for reaction with l b and IC. As a consequence, complete conversion of l b and ICto the alkoxides requires at least 2 equiv of Et20 per Ln. Within a few minutes after addition of a stoichiometric amount of Et20 to l a in benzene-ds, resonances were observed which were assigned t o an intermediate ether adduct Cp*zYD(Etz0).l2 This intermediate was completely converted t o Cp*zYOEt (2a)and ethane as the reaction progressed. In principle, ether splitting is a good synthetic method for the preparation of the ether free alkoxide 2a and ether adducts Cp"zLnOEt(Et20) (Ln = La (3b) and Ce (3c)). However, with increased steric bulk of the ether substituents the rate of cleavage decreased dramatically. The half-lives of l a with different ethers were determined as follows: diethyl ether and n-butyl ethyl ether, 28 (Scheme 2). First the ether molecule is coordinated, forming monomeric Cp*:zLnH(RzO),which renders the a-C atom of the ether molecule susceptible to nucleophilic attack by the hydride ligand in the second step. Our observations for Y, La, and Ce are in good agreement with the results for Sm and Lu, emphasizing the strong similarities between group 3 metals and lanthanides. For yttrium, the intermediate ether hydride adducts Cp*2LnH(ROR) and Cp*2YD(ROR) were observed by lH NMR, which supports the proposed dissociation of dimeric (Cp*zLnH)zin the first step of Scheme 2. This is confirmed by the observed first-order dependence in 7. The reactivity order diethyl ether n-butyl ethyl ether > tert-butyl methyl ether > tert-butyl ethyl ether reflects the increasing steric requirements of the ethers involved. Approach and complexation of ether to (Cp*2LnH)2 become more difficult with increasing steric bulk on the ether molecule. This is in line with the fact that monomeric ether adducts Cp*2YH(R20) and Cp*2YD(R20) could only be observed for the less bulky ethers (EtzO, "BuOEt, and THF). The observation that the bulkiest ether, tert-butyl ethyl ether, reacts slightly faster with lb than with la can be rationalized by the fact that La has a larger ionic radius than Y,29which makes complexation of the ether molecule more favorable. For aliphatic nucleophilic substitution reactions it is well-known that alkyl substituents on the a-C atom of the substrate RX can have an enormous effect on (25)SMe and CHzCHzCHz were not observed, probably due to overlap with other signals in the region 6 = 2.2-1.8 ppm. (26) Evans, J . E.; Ullibarri, T. A,; Ziller, Z. W. Organometallics 1991, 10, 134. (27) Watson, P. L. J. Chem. SOC.,Chem. Commun. 1983, 276. (28) (a)Thompson, M. E.; Bercaw, J . E. Pure Appl. Chem. 1984,56, 1. (b) Steigerwald, M. L.; Goddard, W. A. J. Am. Chem. SOC.1984, 106, 308. ( c ) Rabal, H.; Saillard, J.-Y.; Hoffmann, R. J. Am. Chem. SOC.1986, 108, 4327. (29) Ionic radii for ei ht coordinate complexes: Y3+= 1.16 A, La3+ = 1.30 A, Ce3+ = 1.28 See Shannon, R. D. Acta Crystallogr. 1976, A32, 751.

1.

reactivity.30 In sN2 type substitution, the reactivity order for different R is Me > Et > Pr > Np > Bu, whereas for s N 1 substitution the order Bz x allyl > tertiary C > secondary C > primary C > Me is observed. In sN2 substitution the reactivity is governed by steric characteristics of R, whereas in s N 1 substitution the stabilization of a positive charge on the a-C atom is of dominating importance. Ether cleavage of the sN2 type has been observed with hydrohalic acids (HX) proceeding by sN2 attack of X- on the less hindered C-0 bond.31 Ether cleavage by strong Lewis acids such as boron trihalogenides is an example of a s N 1 type me~hanism.~~ Our systems show similarities with both of these nucleophilic aliphatic substitution reactions. The observation that tert-butyl methyl ether is attacked at the more substituted a-C atom indicates that electronic rather than steric factors are important and suggests an s N 1 mechanism. However, from reaction of tert-butyl ethyl ether, in which both C-0 bonds are cleaved at comparable rates, and from the reaction of n-butyl ethyl ether, which is cleaved at the Et-0 bond, it is clear that steric requirements of the ether molecules are important as well. Only a small effect on the selectivity of ether splitting is found when the results for la are compared with those for lb, although the ionic radii of Y and La are very different.29 From this it is concluded that steric and electronic characteristics of the ether itself and not those of the (Cp*zLnH)zsystem determine the selectivity of the ether splitting. The ring opening observed with 1,gdioxane and THF fits well within the a-bond metathesis scheme described above. Ring opening of THF has also been reported for ( C P * ~ S ~ HWith ) ~ . 1,4-dioxane ~~ the first step is most likely formation of Cp"2YOCH2CH20Et. Formation of 8 requires the selective cleavage of the 0-Et bond in the second step. The complete deoxygenation of ethers by nucleophilic metal hydride complexes is to our knowledge without precedent. There have been some reports, however, concerning formation of p-oxo species which might be attributed to the deoxygenation of THF. For instance, Cp*2Sm@O)SmCp*2 was obtained as a side product in ~~ the ring opening of THF by ( c p * z S m H ) ~ .Another example is the isolation of CpzLu(THF)@-O)(THF)LuCpz from attempted crystallization of CpzLuAsPhz(THF) from THF, which was explained by hydrolysis due to traces of water.32 A more plausible explanation in our opinion is that the p-oxo ligand originates from double C-0 cleavage of THF. This explanation is even more likely when the ring opening of THF by Cp2LuPPhdTHF), leading to CpzLuO(CH2)4PPhz,is con~ i d e r e d The . ~ ~ slower formation of the p-oxo species for Y compared to La and Ce can be understood on the basis of the smaller ionic radius of Y.29 Attack on the C-0 (30) (a) McMurry, J. Organic Chemistry; BrooWCole Publishing: Monterey, 1985. (b) Lowry, T. H.; Richardson, K. S. Mechanism and Theory in Organic Chemistry, 2nd ed.; Harper and Row: New York, 1985. (c) March, J . Advanced Organic Chemistry, 3rd ed.; Wiley: New York, 1985. (31) (a) Bhatt, M. V.; Kulkarni, S. U. Synthesis 1983, 249. (b) Meerwein, H. In Methoden der Organischen Chemie, 4th ed.; Muller, E., Ed.; Thieme Verlag: Stuttgart, 1965; Vol. VI, Part 3, Chapter 1. ( c )Burwell, R. L., Jr. Chem. Reu. 1954, 54, 615. (32) Schumann, H.; Palamidis, E.; Loebel, J. J . Organomet. Chem. 1990,384, C49.

2312 Organometallics, Vol. 14, No. 5, 1995

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Deelman et al.

Scheme 3

A / 112 (Cp*2YH)2

Cp'2YCH2CH2CH3

A /

bond of the alkoxide to reach a four-centered transition state will be easier for La and Ce as a result of the larger coordination sphere of these metal ions. The C - 0 activation of vinyl ethyl ether does not necessarily have to follow the same route as proposed in 'Scheme 2. An alternative mechanism involving insertion of the double bond into the Y-H bond followed by P-alkoxide elimination and evolution of ethylene cannot be ruled out a priori. Insertion might also play an important role in the reaction of allyl ethyl ether. However, attempts to observe an insertion product were unsuccessful. The fast formation of ethoxide 2a also kills the polymerization and hydrogenation activity of la since no hydrogenation or polymerization products of vinyl ethyl ether and allyl ethyl ether were observed. This is in remarkable contrast to the very high activity of (Cp*zLnH)a systems in hydrogenation2 and polymerizationl of nonfunctionalized olefins. The formation of propene in the cleavage of allyl ethyl ether by la is most likely the result of direct attack on the allyl-0 bond, although a six-membered transition state has also been suggested for C-0 activation in allyl ethers.8 A plausible explanation for the formation of propane is allylic C-H activation of propene and Cp*2Ln(v3-allyl),which is well-known for Cp"2LnR complexes (Ln = Y,18 Lu,lb La, Ndl). The propene formed by C - 0 activation of allyl ethyl ether reacts with la to form Cph2YCH2CH2CH3 (Scheme 3). Next, propane and Cp*2Y(y3-allyl)are formed by reaction of Cp*,YCHzCHzCH3 with propene. Attempts to observe Cp*2Y(v3-allyl) in the 'H-NMR spectrum were frustrated by overlap with resonances of unidentified material. As shown by Marks and c o - ~ o r k e r s the , ~ ~ driving force for the cleavage of C-X bonds is undoubtedly the formation of very stable Ln-X bonds. The overall ) C-X cleavage in ethers and reaction enthalpies ( W of sulfides with (Cp*2SmH)2 were calculated to be -48 kcal/mol (MezO)and -53 kcallmol (MezS),respectively. These values are significantly more exothermic than those for C-H activation of hydrocarbons. For instance, the reaction enthalpy for metalation of benzene by Cp*2ScH was determined to be slightly endothermic by 6.7(3) kcal/mol.la From this it follows that C-X activation would be the thermodynamically favored process. However, the observed metalation of RX suggests that kinetic parameters are important as well. Both from experimental and from theoretical work it has become clear that o-bond metathesis strongly depends on steric requirements in the transition states. It was found that metalations of hydrocarbons by (Cp*zLnH)z have low activation e n e r g i e ~ . Especially, ~ ~ ~ ~ , ~increasing ~ substi(33)Nolan, S.P.;Stern, D.; Marks, T. J. J.Am. Chem. SOC.1989, 111,7844.

(34)(a) Rappe, A. K. Organometallics 1990, 9, 466.(b) Ziegler, T.; Folga, E.; Berces, A. J. Am. Chem. SOC.1993,115, 636.

X (A)

(B)

Figure 3. Transition states for C-H (A) and C-X activation (B).

tution on the atoms participating in the four-centered transition state leads t o a dramatic increase in activation energy. Since for C-H activation there are two hydrogens participating in the four-centered transition state, whereas for C-X activation only one hydrogen is involved (Figure 3), the steric requirements for C-H activation are expected to be less than for C-X activation. This could explain why, although the thermochemistry for both processes is very different, competition between C-H and C-X activation is possible. In addition, this effect can be enhanced by the increased acidity of the a-Hs compared to hydrogens of hydrocarbons. From a comparison of the activation of ethers and sulfides it is clear that C-X cleavage is more facile for ethers than for sulfides, which could be the result of the lower BDE's of Ln-SR bonds vs Ln-OR bonds and the lower electronegativity of S vs 0.33The result is that C-H activation and formation of metalated species can compete better. The observation of the insertion product and the hydrogenation of allyl methyl sulfide also indicate that deactivation is less important compared to unsaturated ethers. Conclusions

It was shown that C-0 cleavage of ethers (open and cyclic, saturated, and olefin functionalized) with (Cp*2LnH)2 complexes is a general reaction. Only furan was found to react differently because of the facile ortho C-H activation pathway available. The cleavage pattern observed with asymmetric substituted ethers can be explained by a a-bond metathesis mechanism, and in some cases very selective cleavages can be achieved. The unique activation of alkoxide C-0 bonds by (Cp"2LnHh complexes is a good synthetic route to bimetallic (Cp*zLn)z@-O)complexes. As a consequence of the facile formation of alkoxides and oxides, molecules containing ether functions give very fast deactivation of the catalyst in hydrogenation and polymerization. For sulfides, C-S cleavage is less favorable and C-H activation can compete more effectively, allowing the formation of interesting metalation products. The successful hydrogenation of allyl methyl sulfide shows that deactivation of organolanthanide catalysts by C-X activation is less important for sulfur functions in the substrate molecule. Experimental Section General Considerations. All experiments were performed under nitrogen using standard Schlenk, glovebox (BraunMBZOO), and vacuum line techniques. EtzO, pentane, THF, cyclohexane, benzene, benzene-de, toluene& and THFds were distilled from NalK alloy and degassed prior to use. Compounds la-c,35Je,20 Cp*zYCl(LiCl)(Etz0)~,~~ 2-lithiof~ran,~~ and tB~OEt31 were prepared according to published proce-

Activation of Ethers and Sulfides dures. H2 (99.9995%, Hoek-Loos) was used without further purification. tBuOEt, "BuOEt, vinyl ethyl ether, and allyl ethyl ether were distilled twice from Na sand. Other reagents and cyclohexane-dlz were stored over molecular sieves (4 A). NMR spectra were recorded on Bruker WH90 (lH, 90 MHz), Gemini 200 ('H, 200 MHz), and Varian VXR-300 (lH, 300 MHz; 13C, 75.4 MHz) spectrometers at ambient temperatures. GC analyses were carried out on a Hewlett-Packard HP5890-A instrument equipped with a Hewlett-Packard HP 3390 integrator using Porapack Q and Porasil B columns. G C N S analyses were carried out on a Ribermag R 10-10 C instrument using a CP Si1 5 CB column, and MS spectra were recorded on a n AEI MS 902 mass spectrometer. IR spectra were recorded as Nujol mulls between KBr disks on a Mattson Instruments Galaxy 4020 FT-IR spectrophotometer. Elemental analyses were carried out at the Micro-Analytical Department of the University of Groningen. The determinations are the average of at least two independent determinations. NMR Tube Reaction of (Cp*2YH)2(la) with EtzO. In an NMR tube 0.020 g (0.028 mmol) of la was dissolved in a mixture of 5.8 yL (0.056 mmol) of Et20 and 0.5 mL of benzene&. 'H NMR after 10 min at room temperature showed the formation of Cp*2YD(Et20)and 2a (1:3), After 20 min at room temperature, 'H NMR showed the formation of 2a (100%)and ethane (6 0.79). 2a: 'H NMR (300 MHz, benzene-&) 6 4.28 6.9 Hz, ~ 2H, OCHZCH~), 1.93 (s, 30H, CsMes), 1.31 (q, 3 J= ~ (t, 3 J =~6.9~Hz, 3H, OCH2CH3); l3C NMR (75.4 MHz, = 136 Hz, 2 J c ~ benzene-&) 6 118.01 (s, CsMes), 62.10 (td, 'JCH = 6 Hz, OCHZCH~), 22.40 (9, 'JCH = 123 Hz, OCH2CH3), 10.53 (9, 'JCH = 124 Hz, C&fes). Cp*2YD(Et20): lH NMR (300 MHz, benzene-&) 6 3.37 (q, 3 J= ~ 7.0 Hz, ~ 4H, OCH2CH3), 2.08 (9, 30H, CsMes), 0.84 (t, 3 J= 7.0 ~ Hz, ~ 6H, OCH2CH3). Gas Analysis. On a vacuum line 10 mL of Et20 was condensed on 0.129 g (0.18 mmol) of la at -196 "C. The solution was allowed to warm to room temperature and stirred for 15 h. The gasses evolved were pumped off through a cold trap of -80 "C and analyzed as 0.35 mmol of ethane (GC and MS, 0.97 moVmol of Y). The solvent was removed in vacuum, and the white residue was characterized as the diethyl ether adduct of Cp*zYOEt (3a) by 'H NMR.35 Kinetic Measurements. NMR tubes (5 mm with Young valve) were filled with solutions of l a in methylcyclohexaned14of accurately determined concentration. At -196 "C known amounts of Et20 were added and the NMR tubes were sealed under nitrogen atmosphere. The reaction mixtures were allowed to become homogeneous at -30 "C and were quickly inserted in the probe of an NMR spectrometer and warmed to 0 "C. The progress of the reaction was monitored by taking a 'H-NMR spectrum (300 MHz) at constant intervals (at least three spectra per half-life) for more than 5 half-lives. The decrease in intensity of the Cp* and YH signals of 7 were fitted to an exponential decay using a least-squares method. At the end of the measurement it was made sure that no insoluble material was present. 7: 'H NMR (300 MHz, methylcyclohexane-dl4) 6 5.62 (d, ' J H=~83.1 Hz, l H , YH), 1.92 (s, 30H, CsMes). NMR Tube Reaction of (Cp*,LaH)z (lb) with EtnO. In a n NMR tube 0.020 g (0.025 mmol) of lb was dissolved in 0.5 mL of benzene-& and 16 pL (0.16 mmol) of Et20 was added. 'H NMR after 10 min a t room temperature showed the quantitative formation of 3b and ethane (6 0.78). The NMR tube was opened, and volatiles were removed in vacuum. The residue was redissolved in benzene-&. 3b: 'H NMR (300 MHz, benzene-&) 6 4.15 (q, 3 J= 6.8 ~ Hz, ~ 2H, L ~ O C H Z C H ~ ) , ~ Hz, ~ 4H, O(CHzCH&), 2.08 (S,30H, CsMes), 3.28 (9, 3 J= 7.3 (35) Den Haan, K. H.; Wielstra, Y.; Teuben, J. H. Organometallics 1987, 6, 2053. (36) Den Haan, K.

1987.

H. Thesis, University of Groningen, Groningen,

(37) Wakefield, B. J. Orgunolithium Methods; Academic Press: London, 1988; p 38.

Organometallics, Vol. 14,No.5, 1995 2313 1.27 (t, 3 J= ~ 6.8 HZ, ~ 3H, LaOCH2CH31, 0.87 (t, 3 J= ~ 7.3 ~ Hz, 6H, O(CHzCH3)z. Cp*2YOMe(tBuOMe)(4a). To a solution of 0.58 g (0.80 mmol) of l a in 30 mL of pentane was added 0.40 mL (0.30 g, 3.4 mmol) of tert-butyl methyl ether. Immediately, a clear orange solution was formed and some gas evolution was observed. The reaction mixture was stirred for 15 h, concentrated to 20 mL, and filtered. Cooling at -80 "C afforded 0.42 g (0.90 mmol, 55%)of 4a: IR (cm-l) 2950(s), 2780(s), 2720(w), 2180(w), 1450(s), 1390(m), 1370(s), 1275(m), 1240(m), 1200(m), 1170(sh), 1145(vs), 1040(s), 1005(s),835(s), 805(w), 710(s), 625(w), 590(w),465(m), 430(s); lH NMR (90 MHz, benzene&) 6 4.05 (s, 3H, YOMe), 2.79 (s, 3H, tBuOMe), 2.03 (s, 30H, CsMes), 1.04 (s, 9H, 'BuOMe). Anal. Calcd for C26H4502Y: C, 65.25; H, 9.48. Found: C, 65.07; H, 9.45. NMR Tube Reaction of l a with tBuOEt. In an NMR tube 0.020 g (0.028 mmol) of l a was dissolved in a mixture of 7.6 pL (0.056 mmol) of tBuOEt and 0.5 mL of benzene-&. lH NMR showed the formation of a mixture of 2a (49%) and Sa (43%) together with a small amount of unidentified material (8%)over a period of 4 days at 50 "C. Resonances of isobutane (d, 6 0.85) and ethane (6 0.78) were also observed. 5a: 'H NMR (300 MHz, benzene-&) 6 1.95 (s, 30H, CsMes) 1.41 (s, 9H, 'Bu); 13C NMR (75.4 MHz, benzene-&) 6 118.36 (s, C5Mea), 72.50 (d, 2 J= ~ 6 Hz, ~ CMe3), 35.20 (qsept, 'JCH = 124 Hz, 3 J c = ~ 4 Hz, cMe3), 11.30 (9, 'JCH = 125 Hz, C a e 5 ) . NMR Tube Reaction of l a with "BuOEt. In an NMR tube 0.021 g (0.029 mmol) of l a was dissolved in a mixture of 7.7 pL (0.056 mmol) of "BuOEt and 0.5 mL of benzene-&. 'H NMR after 15 min at room temperature showed the formation of 6a and resonances which were assigned to Cp*zYD("BuOEt) (3:l). After 1h at room temperature, quantitative conversion t o 6a and ethane (6 0.78) had taken place. 6a: lH NMR (300 MHz, benzene-&) 6 4.23 (t, 3 J= 7.0 ~ Hz, ~ 2H, OCHz), 1.95 (s, 7.3 ~ Hz, 2H, YOCHZCHZ), 30 H, CsMes), 1.68 (quint, 3 J= ~ 1.43 (sext, 3 J= ~ 7.3 Hz, ~ 2H, CH2CH2CH31, 1.05 (t, 3 J= ~ ~ 7.3 Hz, 3H, CHzCHzCH3); 13C NMR (75.4 MHz, benzene-&) 6 117.86 (s, CsMes), 67.24 (td, 'JCH = 135 Hz, 2 J= ~ 7 Hz, ~ YOCHz), 39.20 (t, 'JCH = 121 Hz, YOCHZCH~), 19.85 (t, 'JCH = 122 Hz, CHZCH~CH~), 14.73 (q, 'JCH = 124 Hz, CH2CH2CH3), 10.70 (q, 'JCH = 125 Hz, C&fed. NMR Tube Reaction of l b with tBuOMe. In an NMR tube 0.016 g (0.019 mmol) of l b was dissolved in 0.5 mL of cyclohexane-dl2 and 23 yL (0.19 mmol) of tBuOMe was added. lH NMR after 1 day at room temperature showed the quantitative formation of 4b: 'H NMR (300 MHz, benzene-&) 6 3.67 (s, 3H, LaOMe), 3.11 (s, tBuOMe), 1.94 (s, 30H, CsMes), 1.15 (s, 9H, %uOMe). Also, resonances of isobutane (6 0.89, d) were observed. NMR Tube Reaction of l b with *BuOEt. In a n NMR tube 0.014 g (0.017 mmol) of lb was dissolved in 0.5 mL of benzene-& and 25 pL (0.18 mmol) of tBuOEt was added. lH NMR showed that a mixture of 2b (44%) and 5b (56%) had been formed within 2 h at room temperature. Also, resonances of isobutane (doublet at 6 0.85) and ethane (6 0.79) were observed. The NMR tube was opened, and volatiles were removed in vacuum. The residue was redissolved in benzenedg. 5b: 'H NMR (300 MHz, benzene-&) 6 3.95 (9, 3 J= 7.3 ~ ~ Hz, 2H, LaOCH2CH3), 1.97 (s, overlapping CsMes resonances of Cp*zLaOEt and Cp*zLaOtBu),1.38 (s, 9H, %u), 1.25 (t,3 J ~ ~ = 7.3 Hz, 3H, LaOCHzCH3). NMR Tube Reaction of l b with "BuOEt. In an NMR tube 0.016 g (0.019 mmol) of l b was dissolved in 0.5 mL of benzene-& and 25 yL (0.18 mmol) of "BuOEt was added. 'H NMR after 10 min at room temperature showed that 6b had been formed in 87% yield. Volatiles were removed in vacuum, and the residue was redissolved in benzene-&. 6b: 'H NMR (300 MHz, benzene-&) 6 4.11 (t,3&4H = 7.3 Hz, 2H, LaOCHd, 3.30 (m, 4H, "BuOEt), 2.10 (s, 30H, CsMed, 1.67 (quint, 3 J ~ ~ = 7.3 Hz, 2H, LaOCH2CH2), 1.44 (m, 4H, LaO(CH2)2CHzCH3 and "BuOEt), 1.13 (sext, 3&H = 7.3 Hz, 2H, "BuOEt), 1.04 (t,

2314 Organometallics, Vol. 14, No.5, 1995 3 J =~7.3~Hz, 3H, LaO(CHz)&&), 0.96 (t, 3 J =~7.3~ HZ, 3H, "BuOEt), 0.84 (t, 3 J =~7.3~Hz, 3H, "BuOEt); I3C NMR (75.4 MHz, benzene-&) 6 117.83 (s, CsMes), 70.69, (t, 'JCH= 141 Hz, OCH2 of "BuOEt), 68.00 (t, 'JCH= 135 Hz, LaOCHz), 66.65 (t, 'JCH= 142 Hz, OCHz of "BuOEt), 39.30 (t, 'JCH= 124 Hz, L ~ O C H ~ C H Z C H Z31.17 M ~ ) , (t, 'JCH= 124 Hz, CHz of "BuOEt), 19.91 (t, 'JCH= 123 Hz, LaO(CHz)zCHzMe), 19.14 (t, 'JCH= 123 Hz, Me of "BuOEt), 14.69 (9, 'JCH= 126 Hz, LaO(CH2)&fe),14.58 (9, 'JCH= 126 Hz, Me of "BuOEt), 14.00 (9, 'JCH= 124 Hz, Me of "BuOEt), 11.28 (9, 'JCH= 124 Hz, CSMed. NMR Tube Reaction of la with THF. In an NMR tube 4.9 p L (0.060 mmol) of THF was added to a solution of 0.021 g (0.028 mmol) of la in 0.5 mL of cyclohexane-dlz. 'H NMR after 10 min at room temperature showed clean formation of Cp*zYH(THF)which, upon warming to 85 "C, converted to 6a ('H and I3C NMR, 60%)within 1h along with some unidentified products. Cp*zYH(THF): 'H NMR (90MHz, cyclohexanedlz) 6 5.70 (d, 'JHY= 78 Hz, Avllz = 14 Hz, lH, YH), 3.84 (m, 4H, a-THF), 1.94 (s, 30H, CsMes), 1.88 (m, 4H, P-THF). 6a: 'H NMR (300 MHz, cyclohexane-dlz) 6 3.98 (t, 3 J = ~7.3~Hz, 2H, YOCHz), 1.91 (s, 30H, CsMes), 1.48 (quint, 3 J =~7.3~Hz, 2H, OCHzCHz), 1.28 ( s e d , 3 J =~7.3~Hz, 2H, O(CHz)&Hz), 0.92 (t, 3 J =~7.3~Hz, 3H, O(CHz)&fe). (C~*ZY)Z~~-OCH~CH~O)(THF)~ (8). On a vacuum line, a bulb containing 0.242 g (0.336 mmol) of la was evacuated. A mixture of 58 p L (0.68 mmol) of 1,4-dioxane and 5.0 mL of toluene was condensed onto the solid at -196 "C. The reaction mixture was allowed to warm to room temperature and stirred for 15 h. A white precipitate was formed. The gasses evolved were collected by Topler pump and analyzed by GC to be ethane (0.34 mmol, 0.50 mol/mol ofY). Volatiles were removed in vacuum, and the white solid was redissolved in 10 mL of THF. Crystallization at -80 "C yielded 0.184 g (0.20 mmol, 59%)of 8 as white crystals: IR (cm-l) 2900(s), 2799(sh), 2724(m), 2658(m), 2562(w), 1462(s), 1379(s), 1314(m), 1294(m), 1273(m), 1134(vs), 1074(m), 1061(m), 1020(s),914(m), 872(s), 802(w), 723(m), 669(w), 635(vw), 590(w), 421(s); 'H NMR (300 MHz, THF-de) 6 3.90 (s,4H, YOCHzCHzOY), 1.88 (s,60H, CsMe& 13C NMR (75.4 MHz, THF-de) d 115.61 (s, CsMes), 72.23 ~ 5 Hz, 'JYC = 5 Hz, YOCHzCHz(tq, 'JCH= 136.0 Hz, 3 J c = C, OY), 11.28 (s, CsMes). Anal. Calcd for C~OH~OO~YZ(THF): 65.18; H, 8.91; Y, 17.87. Found: C, 65.08; H, 8.99; Y, 17.69. X-ray Structure Determination of (Cp*,Y)&OCH2CH20)(THF)2(8). A colorless, block-shaped crystal was glued to the tip of a glass fiber and transferred into the cold nitrogen stream on an Enraf-Nonius CAD4-Turbo diffractometer on rotating anode. Accurate unit cell parameters and an orientation matrix were determined by least-squares refinement of the setting angles of 25 well-centered reflections (SET41 in the range 10.6" < 0 < 13.8". The unit cell parameters were checked for the presence of higher lattice symmetry.38 Crystal data and details on data collection and refinement are presented in Table 4. All data were collected in w/28 scan mode. Data were corrected for Lp effects and the observed linear decay. An empirical absorption and extinction correction was applied (DIFABS391. The structure was solved by automated Patterson methods and subsequent difference Fourier techniques (DIRDIF-92401. Refinement on F2 was carried out by full-matrix least-squares techniques (SHELXL-9341); no observance criterium was applied during refinement. Hydrogen atoms were included in the refinement on calculated positions (C-H = 0.98 A) riding on their carrier atoms. The Cp* moiety containing atom C11 appeared to be disordered over two positions. The site occupation factor of (38) Spek, A. L. J.Appl. Crystallogr. 1988,21,578. (39) Walker, N.; Stuart, D. Acta Crystallogr. 1983,A39, 158. (40) Beurskens, P. T.; Admiraal, G.; Beurskens, G.;Bosman, W. P.; Garcia-Granda, S.; Gould, R. 0.; Smits, J. M. M.; Smykalla, C. The DIRDIF program system. Technical report of the Crystallography Laboratory, University of Nijmegen, The Netherlands, 1992. (41) Shelldrick, G . M. Program for crystal structure refinement. University of Gottingen, Germany, 1992.

Deelman et al.

Table 4. Details of the X-ray Structure Determinations of (C~*~Y)~O(-OCH~CH~O)(THF)Z (8) and ( C P * ~ C ~ ) Z ~ I - O ~(12) (THF)~ formula

C~OH~OO~Y~C C4eH76Ce203fC4Ha0)2 ~H~O 18) (12) molecular weight 995.10 1125.59 crystal system orthorhombic triclinic space group Pbcn (no. 60) P1 (no. 2) a, A 21.7483(12) 13.399(2) b, A 14.2806(12) 14.864(4) C, A 16.726(2) 15.812(6) a, deg 70.75(2) 85.15(2) .0,. deg 63.78(2) Y ? deg v, A 3 5194.7(8) 2660(2) 1.272 1.405 g~ m - ~ 4 2 z 2120 F(000) 1168 22.8 p, cm-I 17.6 0.5 x 0.5 x 0.5 crystal size, mm 0.10 x 0.22 x 0.25 150 130 T,K 0.94, 24.20 1.37,23.0 0 range, deg 0.71073 ( aphite wa elength (Mo Ka), 0.71073 (graphite monochromator) monocgomat or) scan type 012e ~12e 0.85 0.35 tan 0 scan, deg 0.90 + 0.35 tan 0 2.77,4.00 3.2 + tan 0,4.0 hor, ver aperture, mm X-ray exposure time, 22 169.6 h linear decay, % 1 10 instability constant P 0.029 reference reflections 207, 521, 252 531, -5,l,-1 -25 to 0, -16 to 0, -14 to +14, data set (hkl) -19 to +19 -15 to +16, -1 to +17 total data 8947 8379 unique data 4163, RLnt= 0.08 7421, RLn,= 0.04 DIFABS corr range 0.871, 1.153 no. of refined 332 797 uarameters 0.063 for 2200, 0.038 for 6294, I > 2.50 F, > 4 d F J 0.049 0.144 02(F) + (0.O488Pl2 a(F) 0.995 2.670 0.005, -0.123 0.026, 0.403 -1.43 min esidual density, -0.39 ei-3 1.27 max esidual density, 0.43 e 8;-3 I

w

+

the major component of the disorder model refined to a value of 0.677(9). All non-hydrogen atoms were refined with anisotropic thermal parameters, except for the minor component of the disordered Cp* moiety. The hydrogen atoms were refined with a fured isotropic thermal parameter related t o the value of the equivalent isotropic thermal parameter of their carrier atoms by a factors of 1.5for the methyl hydrogen atoms and 1.2 for the other hydrogen atoms, respectively. Final positional parameters are listed in Table 5. Neutral atom scattering factors and anomalous dispersion corrections were taken from International Tables of Crystallography.42 Geometrical calculations and illustrations were performed with PLATON.43 All calculations were performed on a DECstation 5000/125. NMR Tube Reaction of la with Furan. To a suspension of 0.019 g (0.026 mmol) of la in 0.5 mL of cyclohexane-dlz was added 3.8 pL (0.053 mmol) of furan. Immediately evolution of a gas was observed and la dissolved completely. The solution was transferred to an NMR tube, and lH NMR showed the complete conversion of la to 9: 'H NMR (200 MHz, (42) Wilson, A. J. C., Ed. International Tables of Crystallography; Kluwer Academic Publishers: Dordrecht, The Netherlands, 1992;Vol. C. (43) Spek, A. L. Acta Crystallogr. 1990,A46, C34.

Activation of Ethers a n d Sulfides

Organometallics, Vol. 14, No. 5, 1995 2315

yellow. lH NMR after 20 min at room temperature showed the formation of 2a in quantitative yield. Reaction of l a with Vinyl Ethyl Ether: Gas Analysis (CP*,Y)~~I-OCH~CH~O)(THF)~ (8) and GC/MS Analysis. A mixture of 210 pL (2.20 mmol) of vinyl ethyl ether and 4.3 mL of toluene was condensed onto atom X Y 2 u,,a (A21 0.270 g (0.375 mmol) of l a at -196 "C. The mixture was Y(1) 0.12314(3) 0.19694(4) 0.09224(3) 0.0292(2) allowed to reach room temperature with stirring, during which 0.1611(3) 0.1665(2) 0.0333(17) 0.0524(2) 0!1) the solution turned yellow. After stirring for 15h, gasses were 0.3325(3) 0.1730(3) 0.0440(17) 0.1425(2) O(2) collected by Topler pump and analyzed by GC: 0.03 mmol of 0.0360(5) 0.1477(4) 0.031(2) 0.1674(3) C(1) ethylene (0.04 mol/mol of Y). The remaining volatiles were 0.1043(5) 0.1918(4) 0.043(3) 0.1964(3) C(2) removed in vacuum and identified as toluene and vinyl ethyl 0.1525(5) 0.1413(5) 0.047(3) 0.2384(3) C(3) 0.1127(5) 0.0662(4) 0.044(3) 0.2337(3) C(4) ether by GC. The yellow residue was identified as 2a by 'H 0.0404(5) 0.0687(4) 0.035(3) 0.1903(3) C(5) NMR. The solid was dissolved in 10 mL of toluene, and then 0.1781(5) 0.067(3) 0.1233(4) -0.0336(5) C(6) 250 pL of methanol and 150 pL of water were added. The 0.2794(4) 0.085(4) 0.1864(4) 0.1221(7) C(7) liquid was dried over MgS04 and filtrated. GCMS analysis 0.2227(6) 0.1692(8) 0.116(6) C(8) 0.2850(4) showed the presence of C16-C22 alkanes with exclusively even 0.1345(6) -0.0006(6) 0.089(4) 0.2798(4) C(9) numbers of carbon atoms. -0.0290(5) 0.0049(5) 0.087(4) 0.1754(5) C(10) NMR Tube Reaction of l a with Allyl Ethyl Ether. l a 0.2328(12) -0.0077(9) 0.062(7) *C(llA)b 0.0257(7) 0.2989(18) -0.0404(13) O.OOl(5) (18.0 mg, 0.025 mmol) was dissolved in 0.5 mL of benzene-&, 0.1329(9) *C(11B) *C(12A) 0.0622(11) 0.3158(13) 0.0037(10) 0.071(8) and 64 pL (0.56 mmol) of allyl ethyl ether was added, upon -0.064(3) 0.09(2) 0.0966(16) 0.219(2) *C(12B) which the solution turned yellow. After 5 min at room 0.1158(9) 0.3078(16) -0.0386(13) 0.083(9) *C(13A) temperature, 'H NMR showed that la had completely been 0.0450(12) 0.2149(19) -0.0174(19) 0.021(8) *C(13B) converted to the allyl ethyl ether adduct of 2a (57%) and some 0.1204(8) 0.2173(7) -0.0678(6) 0.029(4) *C(14A) unidentified products. 0.3028(16) 0.0162(16) 0.013(6) *C(14B) 0.0356(9) Reaction of la with Allyl Ethyl Ether: Gas Analysis. 0.1766(7) -0.0496(6) 0.033(4) 0.0654(5) *C(15A) On a vacuum line 10 mL of toluene and 50 pL (0.44 mmol) of 0.0879(10) 0.3512(13) O.OOlO(14) 0.019(7) *C(15B) allyl ethyl ether were condensed onto 0.133 g (0.185 mmol) of 0.2179(16) 0.0188(8) 0.161(14) *C(16A) -0.0349(6) -0.0841(17) 0.073(10) *C(16B) 0.1839(11) 0.334(2) l a at -196 "C. The reaction mixture was stirred at room 0.0391(12) 0.4077(13) 0.0417(12) 0.240(16) *C(17A) temperature for 15 min, and the gasses evolved were pumped -0.1249(19) 0.115(14) 0.1117(16) 0.141(2) *C(17B) off through a cold trap at -80 "C and analyzed as 0.046 mmol 0.3797(11) -0.0494(9) 0.130(9) 0.1689(9) *C(18A) of propane (0.12 moVmol ofY) and 0.162 mmol of propene (0.44 0.1411(18) -0.0237(18) 0.083(10) *C(18B) -0.0067(13) moVmol of Y) by GC. 0.1768(10) -0.1286(6) 0.068(6) 0.1644(6) *C(19A) (Cp*2Y)2@-0) (lla). On a vacuum line, a bulb containing 0.3371(18) 0.0645(15) 0.057(8) *C(19B) -0.0174(10) 0.986 g (1.37 mmol) of l a was evacuated. Next, 20 mL of 0.0809(8) -0.0821(7) 0.081(6) *C(20A) 0.0446(7) cyclohexane and 140 p L (1.35 mmol) of Et20 were condensed "C(20B) 0.1007(10) 0.4527(13) 0.0258(13) 0.040(6) 0.1485(5) 0.2057(4) 0.049(3) -0.0017(4) on the solid at -196 "C. After stirring for 0.5 h at room C(21) 0.1690(7) 0.095(5) 0.1850(4) 0.4084(6) C(22) temperature, the gasses evolved were collected by Topler pump 0.4542(8) 0.2455(6) 0.117(6) 0.1858(5) C(23) and analyzed by GC: 1.34 mmol of ethane (0.49 mol/mol of 0.4132(8) 0.2930(5) 0.106(5) 0.1350(5) C(24) Y). After stirring for 4 days a t 80 "C, the gasses evolved were 0.069(3) 0.3545(6) 0.2367(5) 0.1022(4) C(25) collected and analyzed: 1.29 mmol of ethane (0.47 mol/mol of 0.293(15) 0.5594(10) 1/4 0 O(3) Y). Volatiles were removed in vacuum, and crystallization 0.1838(9) 0.242(15) 0.0068(11) 0.6163(9) C(26) from THF afforded 0.703 g (0.957 mmol, 70%) of colorless 0.7013(9) 0.2120(6) 0.157(8) 0.0155(8) C(27) crystals. lla: IR (cm-'1 2900(s), 2726(w), 1460(s), 1377(s), Starred a UY = one-third of the trace of the orthogonalized U. 1306(w), 1150(m), 1067(w), 1020(m),723(m), 658(s), 625(m), atom sites have a population less than 1.0. 590(w); 'H NMR (300 MHz, benzene-&) 6 2.02 (s, C5Me5); I3C NMR (75.4 MHz, benzene-&) 6 117.6 (s, CsMes), 12.06 (9, ~ J C H cyclohexane-dlz) 6 7.49 (m, l H , H5), 6.27 (broad s, 2H, H3 and = 124 Hz, CsMe5). Anal. Calcd for CloHsoOY2: C, 65.39; H, H4), 1.79 (s, 30H, CsMed. 8.23; Y, 24.20. Found: C, 65.05; H, 8.36; Y, 23.21. MS (EI, Cp*zY(2-OC&)(THF)z (10). To a stirred suspension of 70 eV): m l e 734 (M+). 1.50 g (2.56 mmol) of Cp*2Cl(LiCl)(EtaO)zin 35 mL of Et20 NMR Tube Reaction: (Cp*zLa)&-O) (llb). In an NMR was added 4.10 mL of a 0.620 M solution (2.54 mmol) of tube 0.014 g (0.017 mmol) of lb was dissolved in 0.5 mL of 2-lithiofuran in THF. The reaction mixture turned yellow cyclohexane-d12, and 1.8 pL (0.017 mmol) of Et20 was added. within several minutes. After 1.5 h, volatiles were removed In 24 h at 80 "C colorless crystals were formed. In the 'Hunder vacuum and the solid was stripped with pentane. NMR spectrum resonances of l l b and ethane (6 0.84) were Extraction with 20 mL of pentane, concentration, and cooling observed. llb: 'H NMR (300 MHz, cyclohexane-dl2) 6 1.95 to -30 "C gave 0.354 g (0.620 mmol, 24%) of yellow crystals: (s, C5Me5);the NMR tube was opened, volatiles were removed IR (cm-') 1543(w), 1173(m),1117(m), 1045(s), 1003(s), 916(s), in vacuum, and the residue was dissolved completely in THF891(s), 831(m), 795(m), 710(s), 590(s); 'H NMR (300 MHz, dg; lH NMR (300 MHz, THF-dg) 6 1.99 (s, C5Med. benzene&) 6 7.48 (m, lH, H5), 6.51 (m, lH, H3 or H4), (pseudo NMR Tube Reaction: (Cp*2Ce)&-O)(THF)Z(12). In an d, J = 2.9 Hz, lH, H3, or H4), 3.41 (m, 8H, a-THF), 2.16 (s, NMR tube 0.021 g (0.025 mmol) of ICwas dissolved in 0.5 mL 30H, CsMes), 1.29 (m, 8H, P-THF); I3C NMR (75.4 MHz, of cyclohexane-dlz and 3.5 pL (0.034 mmol) of Et20 was added. benzene-&) 6 210.09 (d, 'Jcy = 62 Hz, C2), 142.35 (ddd, 'JCH The reaction was monitored by 'H NMR spectroscopy. After = 193 Hz, J =13 Hz, J =6 Hz, C5), 119.55 (d, 'JCH = 166 Hz, 24 h at room temperature, the Et20 was completely converted C3), 116.50 (s, CsMes), 110.05 (ddd, 'JCH= 170 Hz, J = 14 Hz, to 2c and ethane (6 0.84) was observed. 2c: 'H NMR (90 MHz, J = 6 Hz, C4), 68.21 (t, 'JCH= 147 Hz, a-THF), 25.32 (t, 'JCH cyclohexane-dl2) 6 26.9 (s, Avll2 = 150 Hz, 2H, CeOCHd, 7.62 = 133 Hz, P-THF), 11.89 (9, 'JCH= 126 Hz, CsMe5). It was (s, Avll2 = 100 Hz, 3H, CeOCH2CHd, 1.93 (s, AYUP= 50 Hz, 30 not possible to obtain satisfactory elemental analysis data due H, CsMes). In 24 h at 80 "C green crystals were formed. t o THF dissociation. Volatiles were removed in vacuum, and the residue was redissolved in THF-dg, upon which a yellow solution formed. NMR Tube Reaction of l a with Vinyl Ethyl Ether. In 'H NMR showed resonances which were assigned to Cp*r an NMR tube 0.030 g (0.042 mmol) of l a was added to a CeOEt(THF-ds) and (Cp*2Ce)zOl-O)(THF-ds)z (1.l:l.O). mixture of 8.0 pL (0.083 mmol) of vinyl ethyl ether and 0.5 Cp*,CeOEt(THF-dg): 'H NMR (300 MHz, THF-dg) 6 22.48 (s, mL of benzene-&. Upon addition of l a the solution turned

Table 5. Final Fractional Atomic Coordinates and Equivalent Isotropic Thermal Parameters of the Non-Hydrogen Atoms for

2316 Organometallics, Vol. 14, No. 5, 1995

Deelman et al.

2H,CeOCH2),6.26 ( S , ~ H , C ~ O C H & H ~ ) , ~ . ~ ~ ( S , ~ O H , C6. ~ MFinal ~~). Table Fractional Atomic Coordinates and Equivalent Isotropic Thermal Parameters of the (Cp*,Ce)z~-O)(THF-ds)z: 'H NMR (300 MHz, THF-ds) 6 3.54 Non-Hydrogen Atoms for (Cp*&e)2@-O)(THF)2 (12) (s, A w 2 = 15 Hz, C5Me5); I3C NMR (75.4 Mhz, THF-ds) 6 128.45 (s, CsMes), 5.01 (9, ~ J C = H 121.5 Hz, C a e 5 ) . Crystals of 12 were obtained by slow diffusion of pentane into a THF Residue 1 solution of llc. 0.17242(3) 0.22134(2) 0.31961(2) 0.0125(1) X-ray Structure Determination of (Cp*&e)2(lc-O)0.27758(3) 0.47499(3) 0.24100(2) 0.0134(1) (THF)2(12). A suitable yellow block-shaped crystal was glued -0.0025(3) 0.2856(3) 0.4096(3) 0.022(1) 0.1310(3) 0.6270(3) 0.1134(3) 0.022(1) on the top of a glass fiber in a drybox and transferred into the 0.2189(3) 0.3524(3) 0.2783(3) 0.017(1) cold nitrogen stream of the low-temperature unit mounted on 0.1139(5) 0.2854(5) 0.1349(4) 0.017(2) a n Enraf-Nonius CAD-4F diffractometer interfaced to a PDP0.0090(5) 0.3 132(5) 0.1735(4) 0.016(2) 11/23 computer. Unit cell dimensions and their standard -0.0008(5) 0.2200(5) 0.2221(4) 0.019(2) deviations were determined from the setting angles of 2 1 0.0975(5) 0.1331(5) 0.2132(4) 0.020(2) reflections in the range 12.01" 0 19.99'. Reduced cell 0.1700(5) 0.1725(5) 0.1609(4) 0.017(2) A calculations did not indicate any higher lattice 0.1525(5) 0.3619(5) 0.0745(4) 0.020(2) search of a limited hemisphere of reciprocal space yielded a -0.0802(5) 0.4239(5) 0.1636(4) 0.023(2) -0.1033(5) 0.2128(5) 0.2608(5) set of reflections that showed no evidence of symmetry or 0.028(2) 0.1115(6) 0.0206(5) 0.2392(5) 0.032(3) systematic extinction. The unit cell was identified as triclinic, 0.2777(5) 0.1093(5) 0.1289(5) 0.026(2) space group Pi. This choice was confirmed by the solution 0.2422(5) 0.0300(5) 0.4756(4) 0.020(2) and the successful refinement of the structure in this space 0.3151(5) 0.4104(4) 0.020(2) -0.0019(5) group. Two reference reflections measured every 3 h of X-ray 0.3828(5) 0.3930(4) 0.0517(5) 0.020(2) exposure indicated a linear decay of 10% over 169.6 h of X-ray 0.3546(5) 0.4494(4) 0.1148(5) 0.021(2) exposure time. The net intensities of the data were corrected 0.2660(5) 0.1024(5) 0.5006(4) 0.022(2) for the scale variation and Lorentz and polarization effects, 0.1675(5) 0.5223(5) 0.029(3) -0.0207(5) but not for absorption. Standard deviation a(I) in the intensi0.3359(5) 0.3829(5) 0.029(2) -0.0954(5) 0.4816(5) 0.3363(5) 0.024(2) 0.0293(5) ties was increased according to an analysis of the excess 0.4148(5) 0.4572(5) 0.1758(5) 0.024(2) variance of the reference reflection: Variance was calculated 0.2149(5) 0.5728(5) 0.1483(5) 0.027(2) based on counting statistics and the term (P212) where P 0.3940(5) 0.0836(4) 0.021(2) 0.4630(5) (=0.029) is the instability constant45as derived from the excess 0.4413(5) 0.1438(4) 0.020(2) 0.3570(5) variance in the reference reflections. The structure was solved 0.5049(5) 0.2137(4) 0.3516(5) 0.018(2) by Patterson methods and subsequent partial structure expan0.4990(5) 0.1983(4) 0.022(2) 0.4534(5) sion (SHELXS86461. Refinement with isotropic temperature 0.4297(5) 0.1173(4) 0.022(2) 0.5222(5) factors and subsequent Fourier synthesis revealed the three 0.3276(5) 0.026(2) 0.5021(5) -0.0033(5) 0.4359(5) 0.025(2) 0.2649(5) 0.1304(5) remaining non-hydrogen atoms and the two solvent molecules. 0.5834(5) 0.2523(5) 0.2843(5) 0.030(2) It was obvious from the Fourier synthesis that the THF solvent 0.5757(6) 0.4735(5) 0.2452(5) 0.030(2) groups [04-C521 and [05-C561 show some degree of disorder. 0.4097(5) 0.6357(5) 0.0734(5) 0.029(2) Refinement using anisotropic thermal parameters followed by 0.2118(5) 0.4961(5) 0.4093(4) 0.017(2) difference Fourier synthesis resulted in the location of all the 0.3147(5) 0.5040(5) 0.022(2) 0.4035(4) nonsolvent hydrogen atoms. The solvent hydrogen atoms were 0.2968(5) 0.022(2) 0.6017(5) 0.3397(4) introduced on calculated positions by using sp3 hybridization 0.1848(5) 0.021(2) 0.6574(5) 0.3053(4) at the C atom as appropriate and a fured C-H distance of 1.0 0.1309(5) 0.5916(5) 0.019(2) 0.3482(4) 0.1872(5) A included in the refinement in the riding mode. The C 1 atom 0.020(2) 0.4101(5) 0.4708(4) 0.4188(6) 0.4243(5) 0.029(2) 0.4612(5) converged to nonpositive definite thermal parameters when 0.3759(6) 0.6527(6) 0.3249(5) 0.034(3) allowed to vary anisotropically. Weights were introduced in 0.1272(6) 0.7703(5) 0.2474(5) 0.034(3) the final refinement cycles. Refinement on F, by block0.0090(5) 0.6241(5) 0.026(2) 0.3341(5) diagonal least-squares techniques with anisotropic thermal -0.0655(5) 0.3953(5) 0.4064(5) 0.025(2) parameters for the non-hydrogen atoms and one common -0.1853(5) 0.4138(5) 0.4028(5) 0.030(2) isotropic thermal parameter for the hydrogen atoms converged -0.1801(6) 0.3087(6) 0.4642(5) 0.034(3) at R = 0.038 (wR= 0.049). A final difference Fourier synthesis -0.0585(6) 0.2284(5) 0.030(2) 0.4699(5) reveals residual densities between -1.43 and 1.27 e/As. 0.0261(6) 0.6260(6) 0.0977(5) 0.032(3) -0.0578(5) 0.7394(5) 0.032(3) 0.0749(5) Crystal data and experimental details of the structure deter0.0056(6) 0.7985(6) 0.041(3) 0.0200(5) mination are listed in Table 4. The final fractional atomic 0.1263(6) 0.7241(5) 0.032(3) 0.0479(5) coordinates and equivalent isotropic thermal parameters for the non-hydrogen atoms are given in Table 6. Scattering Residue 2 0.4632(9) 0.173(1) 0.8151(8) 0.171(6) factors were taken from Cromer and M a n r ~ .Anomalous ~~ 0.3786(9) 0.259(1) 0.7382(9) 0.115(6) dispersion factors were taken from Cromer and L i b e r m a r ~ . ~ ~ 0.278(1) 0.306(1) 0.767(1) 0.22(1) All calculations were carried out on a CDC-Cyber 170/760 0.313(1) 0.280(1) 0.862(1) 0.23(2) computer with the program packages XTAL,49 EUCLID50 0.413(1) 0.205(1) 0.8914(9) 0.17(1) (calculation of geometric data), and ORTEPS1(preparation of Residue 3 illustrations). (44) Le Page, Y. J . Appl. Crystallogr. 1982,15, 255. (45) McCandlish, L. E.; Stout, G. H.; Andrews, L. C. Acta Crystallogr. 1976,A31, 245. (46) Sheldrick, G . M. SHELXS86, Program for crystal structure solution. University of Giittingen, Germany, 1986. (47) Cromer, D. T.; Mann, J . B. Acta Crystallogr. 1969,A24,321. (48) Cromer, D. T.; Liberman, D. J . Chem. Phys. 1970,53, 1891. (49) Hall, S. R.; Stewart, J . H. XTAL2.2 User's Manual; Computer Science Center: University of Maryland, College Park, MD, 1987. (50)Spek, A. L. In Computational Crystallography; Sayre, D., Ed.; Clarendon Press: Oxford, England, 1982; p 528. (51) Johnson, C. K. ORTEP. Report ORNL-3794, Oak Ridge National Laboratory, Oak Ridge, TN, 1965.

0.699( 1) 0.748( 1) 0.796( 1) 0.828(1) 0.749(1)

a

-0.004( 1) -0.021(1) 0.043(2) 0.066(1) 0.0636(9)

0.085(1) 0.1693(9) 0.158(1) 0.076(1) 0.026(1)

0.25(1) 0.16(1) 0.32(2) 0.24(1) 0.16(1)

U,, = 1/3C,CJJ,Ja,aJai.aj. Nonpositive definite temperature

factors.

NMR Tube Reaction of la with Me& To a suspension of 30.4 mg (0.0422 mmol) of la in 0.5 mL of cyclohexane-dlz was added 6.2 pL (0.085 mmol) of Me&. Immediately after addition, gas evolution was observed and la dissolved. The reaction mixture was transferred to an NMR tube, and the

Organometallics, Vol. 14, No. 5, 1995 2317

Activation of Ethers and Sulfides tube was sealed under vacuum. The 'H NMR spectrum after 0.5 h at room temperature showed that 13 (75%) and an unidentified compound had been formed. When performed with an excess of MezS (Me2S:Y = lo), this unidentified product was absent. 13: 'H NMR (200 MHz, cyclohexanedl2) 6 2.21 (s, 3H, SMe), 1.91 (s, 30H, CsMes), 1.33 (broad s, 2H, YCHz). Unidentified compound: 'H NMR (200 MHz, cyclohexane-dlz) 6 1.94 (s, CsMes). Cp*zYCH2SMe(THF)(14). To a stirred suspension of 0.53 g (0.74 mmol) of (Cp*zYH)z in 20 mL of pentane was added 108 pL (1.5 mmol) of MeZS. Gas evolution was observed, and (Cp*2YH)z dissolved completely. After 10 min at room temperature, the orange solution was cooled to -30 "C, affording 0.50 g of pink crystals. The pink material was recrystallized from and washed with pentane:THF (2:1), affording 0.31 g (0.63 mmol, 43%) of white crystals. 14: IR (in cm-') 2726(m), 2672(w),1303(m),1169(w),1157(w),1015(m),970(w),864(m), 839(m), 721(m); 'H NMR (200 MHz, benzene-&) 6 3.44. (m, 4H, a-THF), 2.27 (s, 3H, SMe), 2.03 (s, 30H, CsMes), 1.23 (m, 4H, P-THF), 1.19 (d, z J =~2.6 Hz, 2H, YCHz); I3C NMR = (75.4 MHz, benzene-&) 6 116.88 (s, CsMed, 69.79 (t, 'JCH 149 Hz, a-THF), 37.69 (td, 'JCH= 123 Hz, 'Jcy = 46 Hz, YCHz), 25.97 (q, SMe, overlaps with P-THF), 25.27 (t, 'JCH= 131 Hz, P-THF), 11.37 (9, 'JCH= 126 Hz, C&e& Anal. Calcd for Cz6H430SY C, 63.40; H, 8.80; Y, 18.05. Found: C, 63.40; H, 8.77; Y, 18.25. NMR Tube Reaction of la with Benzyl Methyl Sulfide. To a solution of 0.015 g (0.020 mmol) of la was added 5.5 pL (0.040 mmol) of benzyl methyl sulfide. Immediately gas evolution was observed as was a color change t o yellow. 'H NMR after 40 min at room temperature showed the essentially quantitative formation of 15: 'H NMR (300 MHz, cyclohexanedlz) 7.21 (m, l H , aryl H), 6.94 (m, 3H, aryl H), 6.64 (m, l H , aryl H), 3.43 (d, 2 J= 3.0 ~ Hz, l H , YCH), 2.19 (s, 3H, SMe), 2.03 (s, 15H, C5Me5),1.74 (s, 15H, CsMes). Cp*zYSEt(THF) (17). To a stirred suspension of 1.50 g (2.08 mmol) of l a in 50 mL of pentane was added 0.95 mL (8.8 mmol) of Et&. After 6 days a t room temperature, a red solution with a yellow precipitate had been formed. The volatiles were removed in vacuum, and the solid was washed with 50 mL of pentane. The residue was dissolved in 5 mL of THF and cooling afforded 0.550 g (1.12 mmol, 27%) of 17 as white crystals: IR (cm-l) 2724(w), 1244(s), 1014(s), 959(w), 918(w), 860(s), 766(w), 665(m), 592(w); 'H NMR (200 MHz, THF-da) 6 2.70 (9, 3 J =~7.3~ Hz, 2H, SCHd, 1.96 (s, 30H, CsMes), 1.19 (t, 3 J =~7.3~Hz, 3H, CH2CH3); l3cNMR (75.4 MHz, THF-da) 6 119.09 (s, CsMes), 24.99 (t, 'JCH= 136 Hz, SCHZCH~), 23.20 (9, 'JCH= 125 Hz, SCHZCH~), 12.85 (9, 'JCH = 125 Hz, Cfle5). Anal. Calcd for C26H430SY C, 63.40; H, 8.80; Y, 18.05. Found: C, 63.30; H, 8.81; Y, 18.14.

CP*~Y(~-SC~H~)(THF) (19). (Cp*zYH)2 (0.876 g, 1.22 mmol) was suspended in 30 mL of pentane, and 200 pL (2.38 mmol) of thiophene was added with stirring. Immediately gas evolution was observed along with the formation of a white solid. Volatiles were removed in vacuum, and the pink residue was washed three times with 5 mL of pentane. Recrystallization from THF afforded 0.900 g (1.75 mmol, 72%) of white crystals. 19: IR (cm-') 3084(m), 3050(s), 2957(s), 2926(s), 2917(s), 2857(s), 2722(m), 1759(w), 1559(w), 1458(s), 1377(s), 1343(m),1316(w), 1294(m),1246(w),1188(m), 1144(w),1063(m), 1017(s),955(w), 920(m), 864(s), 843(sh), 820(m), 812(m), 729(m), 683(s), 615(w), 592(m), 476(m); 'H NMR (300 MHz, THF-da) 6 7.38 (d, 3 J =~4.4~Hz, 1H, H5), 7.04 (dd, 3 5= ~ ~ 4.2 Hz, 3 J =~3.1~Hz, 1H, H4), 6.81 (d, 3 5 = ~ 2.9 ~ Hz, 1H, H3), 1.79 (s, 30H, CsMes); I3C NMR (75.4 MHz, THF-da) 6 180.24 (d, 'Jcy = 62 Hz, C2),133.68 (ddd, 'JCH = 159 Hz, 3 J c ~ = 12 Hz, 2 J =~6 Hz, ~ C3), 128.24 (dt, 'JCH= 180 Hz, 'JCH= 3 J c= ~ 9 Hz, C5), 127.16 (dt, 'JCH= 143 Hz, 2 J= 7~Hz,~C4), 118.05 (s, CsMes), 11.72 (9, 'JCH = 126 Hz, C5Me5). Anal. Calcd for CzaH410SY C, 65.35; H, 8.03; S, 6.23; Y, 17.28. Found: C, 65.46; H, 8.08; S, 5.32; Y, 17.28. NMR Tube Reaction of l a with Allyl Methyl Sulfide. To a suspension of 0.016 g (0.022 mmol) of la in 0.5 mL of cyclohexane-dl2 was added 5.0 pL (0.046 mmol) of allyl methyl sulfide. 'H NMR (300 MHz) after 5 min at room temperature showed that 53% of 20 had been formed along with some unidentified products and unreacted allyl methyl sulfide. For NMR data see text. Hydrogenation of Allyl Methyl Sulfide. To a suspension of 0.016 g (0.022 mmol) of la in 0.5 mL of cyclohexane-dl2 under HZ(1bar) was added 50 pL (0.46 mmol) of allyl methyl sulfide. 'H NMR after stirring for 4 days at room temperature showed that 30% of the allyl methyl sulfide had been converted t o n-propyl methyl sulfide (3.1 mollmol of Y), while the remaining allyl methyl sulfide was present unreacted.

Acknowledgment. This investigation was supported by the Netherlands Organization for Chemical Research (SON) with financial aid from the Netherlands Foundation for the Advancement of Scientific Research (NWO). Supplementary Material Available: Lists of atom coordinates and U values, all bond lengths and angles, torsion angles, and thermal parameters for 8 and 12 (40 pages). Ordering information is given on any current masthead page. OM940986J