Fulvene to cyclopentadienyl conversion with homoleptic complexes of zirconium and hafnium

Article abstract of DOI:10.1021/om990402j

The reaction of 6,6-dimethylfulvene with M(CH₂Ph)₄ (M = Zr, Hf) in benzene gives [η⁵-C₅H₄(CMe₂CH ₂Ph)]M(CH₂Ph)₃ (1, M = Zr; 2, M = Hf) without any observable byproducts. A similar reaction for M = Ti is not observed. The single-crystal X-ray study of 1 shows a three-legged piano-stool geometry with an η²-bound benzyl ligand. A second equivalent of 6,6-dimethylfulvene does not react with either 1 or 2. The bulkier 6,6-diphenyfulvene only reacts cleanly with the more Lewis acidic Hf(CH₂Ph)₄ to give [η⁵-C₅H₄(CPh₂CH ₂Ph)]Hf(CH₂-Ph)₃ (3). Using the tetraamido complexes M(NMe₂)₄ and 6,6-dimethylfulvene, one obtains dimethylamine and [η⁵-C₅H₄(CMeCH₂)]M(NMe ₂)₃ (4 for M = Zr) in good yield. These products are formally derived from the deprotonation of a fulvene methyl group and subsequent coordination of the resulting 2-propenylcyclopentadienyl fragment. Reaction of 4 and 6,6-dimethylfulvene affords the bent metallocene [η⁵-C₅H₄(CMeCH₂)] ₂Zr(NMe₂)₂ (5). Excess 8,8-dimethylbenzofulvene and M(NMe₂)₄ provides exclusively the product with only one coordinated indene.

Full text of DOI:10.1021/om990402j

3976
Organometallics 1999, 18, 3976-3980
F u lven e to Cyclop en ta d ien yl Con ver sion w ith
Hom olep tic Com p lexes of Zir con iu m a n d Ha fn iu m
J onathan S. Rogers,† Rene J . Lachicotte,† and Guillermo C. Bazan*,‡
Departments of Chemistry, University of California, Santa Barbara, California 93106, and
University of Rochester, Rochester, New York 14627-0216
Received May 26, 1999
The reaction of 6,6-dimethylfulvene with M(CH2Ph)4 (M ) Zr, Hf) in benzene gives [η5-
C5H4(CMe2CH2Ph)]M(CH2Ph)3 (1, M ) Zr; 2, M ) Hf) without any observable byproducts.
A similar reaction for M ) Ti is not observed. The single-crystal X-ray study of 1 shows a
three-legged piano-stool geometry with an η2-bound benzyl ligand. A second equivalent of
6,6-dimethylfulvene does not react with either 1 or 2. The bulkier 6,6-diphenyfulvene only
reacts cleanly with the more Lewis acidic Hf(CH2Ph)4 to give [η5-C5H4(CPh2CH2Ph)]Hf(CH2-
Ph)3 (3). Using the tetraamido complexes M(NMe2)4 and 6,6-dimethylfulvene, one obtains
dimethylamine and [η5-C5H4(CMeCH2)]M(NMe2)3 (4 for M ) Zr) in good yield. These products
are formally derived from the deprotonation of a fulvene methyl group and subsequent
coordination of the resulting 2-propenylcyclopentadienyl fragment. Reaction of 4 and 6,6-
dimethylfulvene affords the bent metallocene [η5-C5H4(CMeCH2)]2Zr(NMe2)2 (5). Excess 8,8-
dimethylbenzofulvene and M(NMe2)4 provides exclusively the product with only one coor-
dinated indene.
In tr od u ction
MgCp2, etc.). Disadvantages of these procedures include
the need to prepare moisture- and air-sensitive ligand
anions and the sometimes difficult removal of metal
halide byproducts. Several reports are now available
which circumvent these difficulties. A recent report by
J ordan and co-workers describes the use of neutral
reagents for the preparation of racemic bis(indenyl) and
bis(cyclopentadienyl) group 4 complexes.9 Another ex-
ample is the reaction of trimethylsilyl-substituted cy-
clopentadienyls with transition-metal halides.10
In connection to our work with boratabenzene-sup-
ported catalysts,11 we recently reported that the reaction
of homoleptic group 4 tetraalkyls and tetraamides with
borabenzene-Lewis base adducts provides a means to
synthesize boratabenzene complexes.12 For example, as
shown by the reaction of tetrabenzylzirconium with 1
Group 4 complexes containing one or two cyclopen-
tadienyl (Cp) ligands are versatile reagents which find
use in catalytic and stoichiometric reactions. Com-
pounds of this type are effective catalysts for the
polymerization of olefins,1 the asymmetric cyclopoly-
merization of dienes,2 Diels-Alder cycloaddition reac-
tions,3 enantioselective carbomagnesations,4 Pauson-
Khand type cyclocarbonylations,5 and the hydrogenation6
and hydrosilation7 of olefins, among others.8 New
preparative methods for Cp-group 4 metal complexes
therefore make an impact in diverse areas of chemical
synthesis.
The most widely used approach for coordination of Cp,
as well as the many variations of this ligand, requires
use of salts containing the ligand anion (i.e. LiCp, NaCp,
† University of Rochester.
‡ University of California.
(1) (a) Transition Metals and Organometallics as Catalysts for Olefin
Polymerization; Kaminsky, W., Sinn, H., Eds.; Springer-Verlag: Berlin,
1988. (b) Ziegler Catalysts; Fink, G., Mu¨lhaupt, R., Brintzinger, H.-
H., Eds.; Springer-Verlag: Berlin, 1995. (c) Brintzinger, H.-H.; Fischer,
D.; Mu¨lhaupt, R.; Rieger, B.; Waymouth, R. M. Angew. Chem., Int.
Ed. Engl. 1995, 34, 1143.
(2) (a) Coates, G. W.; Waymouth, R. M. J . Am. Chem. Soc. 1991,
113, 6270. (b) Coates, G. W.; Waymouth, R. M. J . Am. Chem. Soc. 1993,
115, 91. (c) Habaue, S.; Sakamoto, H.; Okamoto, Y. Polym. J . 1997,
29, 384.
(3) (a) Hong, Y.; Kuntz, B. A.; Collins, S. Organometallics 1993, 12,
964. (b) Hong, Y.; Norris, D. J .; Collins, S. J . Org. Chem. 1993, 58,
3591. (c) J aquith, J . B.; Guan, J .; Wang, S.; Collins, S. Organometallics
1995, 14, 1079 and references therein.
(4) Hoveyda, A. H.; Morken, J . P. Angew. Chem., Int. Ed. Engl. 1996,
35, 1262.
equiv of borabenzene-PMe3 (C5H5B-PMe3) gives [η6-
C5H5B-CH2Ph]Zr(CH2Ph)3 in excellent yield. It is likely
that the reaction proceeds via coordination of boraben-
(5) (a) Negishi, E.; Holmes, S. J .; Tour, J . M.; Miller, J . A. J . Am.
Chem. Soc. 1985, 107, 2568. (b) Hicks, F. A.; Buchwald, S. L. J . Am.
Chem. Soc. 1996, 118, 11688 and references therein.
(6) For examples see: (a) Couturier, S.; Goutheron, B. J . Organomet.
Chem. 1978, 157, C61. (b) Waymouth, R.; Pino, P. J . Am. Chem. Soc.
1990, 112, 4911. (c) Broene, R. D.; Buchwald, S. L. J . Am. Chem. Soc.
1993, 115, 12569.
(7) (a) Takahashi, T.; Hasegawa, M.; Suzuki, N.; Saburi, M.; Rousset,
C. J .; Fanwick, P. E.; Negishi, E. J . Am. Chem. Soc. 1991, 113, 8564.
(b) Kesti, M. R.; Waymouth, R. M. Organometallics 1992, 11, 1095.
10.1021/om990402j CCC: $15.00 © 1999 American Chemical Society
Publication on Web 08/28/1999

Fulvene to Cyclopentadienyl Conversion
Organometallics, Vol. 18, No. 20, 1999 3977
Sch em e 1
zene-PMe3 to zirconium, followed by intramolecular
nucleophilic attack by one of the metal-bound ligands
onto the boron atom. In the case of zirconium tetraa-
mides the resulting products contain aminoborataben-
zene ligands.
A similar type of reaction can be envisioned by
starting with group 4 homoleptic compounds and ful-
vene derivatives. Coordination of the cis-diene function-
ality to the metal should encourage transfer of the metal
ligands to the exocyclic carbon and give the desired Cp
ligand, as shown in Scheme 1. Such a sequence should
be encouraged with increased electron deficiency at the
metal center and by polarized metal-ligand bonds. In
this contribution we study the scope of the reactivity in
Scheme 1 and focus on the effect of metal, ligand, and
substitution patterns on the periphery of the fulvene
framework.
F igu r e 1. ORTEP view of 1. Thermal ellipsoids are shown
at the 30% probability level; hydrogen atoms are omitted
for clarity. Selected bond distances (Å): Zr(1)-C(1), 2.302-
(5); Zr(1)-C(2), 2.659(5); Zr(1)-C(8), 2.289(5); Zr(1)-C(15),
2.258(5); Zr(1)-C(22), 2.507(5); Zr(1)-C(23), 2.447(5); Zr-
(1)-C(24), 2.449(5); Zr(1)-C(25), 2.511(5); Zr(1)-C(26),
2.575(5). Selected bond angles (deg): Zr(1)-C(1)-C(2),
87.0(3); Zr(1)-C(8)-C(9), 123.1(3); Zr(1)-C(15)-C(16),
101.5(3).
shown in Figure 1. The overall molecular structure of 1
resembles a three-legged piano stool in which the five
carbons of the cyclopentadienyl core form the base of
the seat. The Cp ring is slightly slip distorted such that
the bulky exocyclic substituent is pushed away from the
metal, with Zr-C distances ranging from 2.447(5) Å
(Zr-C(23)) to 2.511(5) Å (Zr-C(25)). The two benzyl
ligands adjacent to the exocyclic 1,1-dimethyl-2-phe-
nylethane fragment are rotated away from the five-
membered ring, and one is η2-bound. This ligand
exhibits a Zr-CH2-C(2) angle of 87.0(3)° and a Zr-C(2)
distance of 2.659(5) Å. In solution at 25 °C the three
benzyl ligands are equivalent by 1H NMR spectroscopy.
With the bulkier 6,6-diphenylfulvene a clean reaction
is only observed with tetrabenzylhafnium. The product
of the reaction, [η5-C5H4(CPh2CH2Ph)]Hf(CH2Ph)3 (3 in
eq 2), can be purified by trituration in pentane to give
Resu lts a n d Discu ssion
Tetrabenzylzirconium reacts with 6,6-dimethylfulvene
at 65 °C in C6D6 to give the desired “insertion” product
[η5-C5H4(CMe2CH2Ph)]Zr(CH2Ph)3 (1), as shown in eq
1
1. The reaction is easily monitored by H NMR spec-
troscopy and proceeds in excellent yield. As the reaction
progresses, two sets of pseudotriplets in a 1:1 ratio grow
at 5.28 and 5.53 ppm at the expense of the methylene
signal of tetrabenzylzirconium (1.52 ppm). A signal,
attributed to the metal-bound benzylic protons, is also
observed at 1.64 ppm for the final product. Formation
of 1 occurs within 22 h, and subsequent crystallization
from pentane provides a bright yellow crystalline solid.
Heating solutions of 6,6-dimethylfulvene and Ti(CH2-
Ph)4 only gave noncharacterizable decomposition prod-
ucts. Use of tetrabenzylhafnium proceeds to give [η5-
C5H4(CMe2CH2Ph)]Hf(CH2Ph)3 (2), as a pale yellow
solid. Neither 1 nor 2 reacts with a second equivalent
of 6,6-dimethylfulvene to provide the bis(cyclopentadi-
enyl) product.
a nearly colorless, microcrystalline solid. Attempts to
repeat the process using Zr(CH2Ph)4 resulted in the
formation of unidentified decomposition products. We
suspect that, since Zr(CH2Ph)4 is a weaker Lewis acid,
the requisite fulvene adduct is less favored.
When the reaction of Zr(NMe)4 with 6,6-dimethylful-
1
vene at 80 °C is followed by H NMR spectroscopy, one
observes a rapid consumption of both starting materials,
together with the appearance of resonances due to
cyclopentadienyl proton resonances. However, in con-
trast to the reactions with the benzyl derivatives, a pair
of olefinic resonances appear at 4.85 and 5.23 ppm.
Integration shows that three dimethylamido ligands
remain coordinated to zirconium. Free dimethylamine
is also observed. These data are consistent with the
Single crystals of 1 suitable for X-ray diffraction
studies were grown from pentane, and the results are

3978 Organometallics, Vol. 18, No. 20, 1999
Rogers et al.
Su m m a r y a n d Con clu sion
In summary, reactions 1-4 show that it is possible
to obtain transition-metal complexes containing cyclo-
pentadienyl-based ligands directly from fulvene and a
suitable homoleptic complex. The M(CH2Ph)4 complexes
give products that can be thought as originating from
nucleophilic attack of a benzyl ligand onto the exocyclic
carbon of the coordinated fulvene. Formally, this se-
quence amounts to an insertion step. We note that a
direct insertion should be disfavored, since the reactive
olefin is tetrasubstituted. For the tetraamides the
resulting cyclopentadienyl ligands contain an exocycylic
propenyl group. Such a process is easily understood by
invoking deprotonation of the methyl group by an amido
ligand followed by coordination of the resulting cyclo-
pentadienyl core. It is an open question at this stage
whether coordination is required prior to deprotonation.
The exact mechanistic details responsible for deter-
mining the reaction outcome are not understood at this
stage. We point out that there is ample precedence for
both the Brønsted acidity and the Lewis acidity of 6,6-
dimethylfulvene. In fact, the two competing paths
provide a sensitive probe for the electronic structure of
reactive organic anions in the gas phase.14 More rel-
evant to the reactivity reported here is the fact that
different products are observed by reaction of 6,6-
dimethylfulvene with different lithium reagents:
formation of [η5-C5H4(CMeCH2)]Zr(NMe2)3 (4 in eq 3),
which contains a cyclopentadienyl ligand with an exo-
cyclic 2-propenyl group. Further reaction of 4 with an
additional 1 equiv of 6,6-dimethylfulvene gives bis(2-pro-
penylcyclopentadienyl)bis(dimethylamido)zirconium (5
in eq 3). 1H NMR spectroscopy shows that reactions
starting with Hf(NMe2)4 give similar results. Com-
pounds 4 and 5, as well as their hafnium analogues,
are isolated as highly air- and moisture-sensitive yellow
oils. Related to compound 5 is the work by Erker and
co-workers, who studied complexes of the type (alkenyl-
Cp)2MCl2 (M ) Zr, Hf) and their intramolecular [2 + 2]
cycloaddition chemistry.13
Only 1 equiv of 8,8-dimethylbenzofulvene reacts with
Zr(NMe2)4 to give the (2-propenyl)indene complex 6 in
eq 4 as an air-sensitive yellow oil. Compound 6 is stable
Nucleophilic addition (path a ) is observed with LiAlH4,15
MeLi,15 PhLi,15 C9H7Li,16 and C13H9Li.17 The closely
related amide reagents NaNH215 and LiNiPr218 serve as
deprotonating agents (path b). The dual function of Ph2-
PCH2Li (path a or b), depending on choice of solvent,
has also been discussed.19 Also relevant to this discus-
sion is the recent report that Bu2ZrCl2 reacts with 6,6-
dimethylfulvene to give bis(isopropylcyclopentadienyl)-
zirconium dichloride.20 While the exact reaction sequence
with Bu2ZrCl2 remains to be resolved, the overall
process reduces to path a , where hydride plays the role
of the nucleophile.
to further reaction with 8,8-dimethylbenzofulvene, even
when heated to 80 °C for 2 days. No reaction is observed
with Zr(NMe2)4 and 6,6-diphenylfulvene, which lacks
acidic hydrogens.
(8) (a) Metallocenes; Togni, A., Halterman, R. L., Eds.; Wiley-VCH
Verlag: Weinheim, Germany, 1998. (b) Comprehensive Organometallic
Chemistry; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Hegedus,
L. S., Vol. Ed.; Elsevier: Oxford, U.K., 1995; Vol. 12.
(9) (a) Diamond, G. M.; Rodewald, S.; J ordan, R. F. Organometallics
1995, 14, 5. (b) Diamond, G. M.; J ordan, R. F.; Petersen, J . L.
Organometallics 1996, 15, 4030. (c) Christopher, J . N.; Diamond, G.
M.; J ordan, R. F.; Petersen, J . L. Organometallics 1996, 15, 4038. (d)
Diamond, G. M.; J ordan, R. F.; Petersen, J . L. Organometallics 1996,
15, 4045.
(10) For examples see: (a) Cardoso, A. M.; Clark, R. J . H.; Moor-
house, S. J . Chem. Soc., Dalton Trans. 1980, 1156. (b) Lund, E. C.;
Livinghouse, T. Organometallics 1990, 9, 2426. (c) Winter, C. H.; Zhou,
X.; Dobbs, D. A.; Heeg, M. J . Organometallics 1991, 10, 210.
(11) (a) Bazan, G. C.; Rodriguez, G.; Ashe, A. J ., III; Al-Ahmad, S.;
Mu¨ller, C. J . Am. Chem. Soc. 1996, 118, 2291. (b) Bazan, G. C.;
Rodriguez, G.; Ashe, A. J ., III; Al-Ahmad, S.; Kampf, J . W. Organo-
metallics 1997, 16, 2492. (c) Rogers, J . S.; Bazan, G. C.; Sperry, C. K.
J . Am. Chem. Soc. 1997, 119, 9305. (d) Barnhart, R. W.; Bazan, G. C.;
Mourey, T. J . Am. Chem. Soc. 1998, 120, 1082. (e) Rogers, J . D.;
Lachicotte, R. J ., Bazan, G. C. J . Am. Chem. Soc. 1999, 121, 1288.
(12) Putzer, M. A.; Rogers, J . S.; Bazan. G. C. J . Am. Chem. Soc., in
press.
Exp er im en ta l Section
Gen er a l Rem a r k s. All manipulations were performed an
under inert atmosphere using standard glovebox and Schlenk
techniques.21 Tetrabenzylzirconium,22 tetrabenzylhafnium,23
(14) Brickhouse, M. D.; Squires, R. R. J . Am. Chem. Soc. 1988, 110,
2706.
(15) Knox, G. R.; Pauson, P. L. J . Chem. Soc. 1961, 4610.
(16) Mallin, D. T.; Rausch, M. D.; Lin, Y.; Dong, S.; Chien, J . C. W.
J . Am. Chem. Soc. 1990, 112, 2030.
(17) (a) Ewen, J . A.; J ones, R. L.; Razavi, A.; Ferrara, J . D. J . Am.
Chem. Soc. 1988, 110, 6255. (b) Razavi, A.; Ferrara, J . J . Organomet.
Chem. 1992, 435, 299. (c) Razavi, A.; Atwood, J . L. J . Organomet.
Chem. 1993, 459, 117.
(18) Macomber, D. W.; Hart, W. P.; Rausch, M. D. J . Am. Chem.
Soc. 1982, 104, 884.
(19) Schore, N. E.; LaBelle, B. E. J . Org. Chem. 1981, 46, 2306.
(20) Eisch, J . J .; Owuor, F. A.; Shi, X. Organometallics 1999, 18,
1583.
(21) Burger, B. J .; Bercaw, J . E. In Experimental Organometallic
Chemistry; Wayda, A. L., Darensbourg, M. Y., Eds.; ACS Symposium
Series 357; American Chemical Society: Washington, DC, 1987.
(22) Zucchini, U.; Albizzati, E.; Giannini, U. J . Organomet. Chem.
1971, 26, 357.
(13) (a) Erker, G.; Aul, R. Chem. Ber. 1991, 124, 1301 and references
therein. (b) Erker, G.; Wilker, S.; Kruger, C.; Nolte, M. Organometallics
1993, 12, 2140.

Fulvene to Cyclopentadienyl Conversion
Organometallics, Vol. 18, No. 20, 1999 3979
6,6-dimethylfulvene,24 6,6-diphenylfulvene,24 8,8-dimethylben-
Ta ble 1. Su m m a r y of Cr ysta llogr a p h ic Da ta for 1
zofulvene,25 and Zr(NMe2)4 were prepared according to
9a
Crystal Parameters
literature methods. Benzene, pentane, and diethyl ether were
distilled from sodium benzophenone ketyl. NMR spectra were
obtained using a Varian Unity 400 or 500 spectrometer. 1H
and 13C{1H} NMR spectra were calibrated using signals from
the solvent and are reported downfield from SiMe4. Elemental
Analyses were performed by Desert Analytics, Inc., Tucson,
AZ. Mass spectroscopic analyses were obtained using a VG-
70E double-focusing magnetic sector instrument operated with
an OPUS/SIOS data system with an electron ionization source.
[η5-C5H4(CMe2CH2P h )]Zr (CH2P h )3 (1). 6,6-Dimethylful-
vene (33 mg, 0.31 mmol) and tetrabenzylzirconium (125 mg,
0.275 mmol) were placed in a 100 mL round-bottom flask with
4 mL of benzene and a stir bar. The resulting mixture was
heated to 65 °C for 22 h. The excess fulvene and benzene were
removed in vacuo. The product was extracted with pentane,
and the extracts were filtered. Cooling to -35 °C overnight
gave bright yellow crystals of 1 (90 mg, 0.16 mmol, 58%
isolated yield). 1H NMR (C6D6, 400 MHz): δ 1.09 (s, 6H,
C5H4C(CH3)2), 1.64 (s, 6H, Zr(CH2Ph)3), 2.61 (s, 2H, C5H4-
chem formula
fw
C41H48Zr
632.01
monoclinic
P21/c
4
10.9433(2)
10.7916(2)
26.9377(3)
97.9830(10)
3150.40(9)
1.333
cryst syst
space group
Z
a, Åa
b, Å
c, Å
â, deg
V, Å3
F
calcd, mg/mm3
cryst dimens, mm3
temp, °C
0.12 × 0.14 × 0.16
-80
Measurement of Intensity Data and Refinement Parameters
radiation (λ, Å)
2θ range, deg
Mo KR (0.710 73)
3-46.6
12 511
total no. of data
no. of unique data
4414
4.17, 5.15
3602
350
0.377
R
int, Rsigma (%)b
no. of obsd data (I > 2σ(I))
no. of params varied
µ, mm-1
3
CMe2(CH2Ph)), 5.28 (t, 2H, Cp, J HH ) 3 Hz), 5.54 (t, 2H, Cp,
3
3J HH ) 3 Hz), 6.55 (d, 6H, Zr(CH2CCHCHCH)3, J HH ) 7 Hz),
abs cor
empirical (SADABS)c
0.928-0.802
1.150
4
3
3
6.77 (dd, 2H, J HH ) 2 Hz, J HH ) 8 Hz), 6.95 (t, 6H, J HH ) 8
Hz), 7.05-7.12 (m, 6H, Ph-H). 13C{1H} NMR (C6D6, 100
MHz): δ 27.8 (C5H4C(CH3)2(CH2Ph)), 37.3 (C5H4CMe2(CH2-
Ph)), 53.2 (C5H4CMe2(CH2Ph)), 67.0 (Zr(CH2Ph)3), 110.0, 111.9,
123.4, 126.4, 128.5, 129.8, 130.9, 138.6, 140.2, 144.1, 145.6.
Anal. Calcd (C36H38Zr): C, 76.95; H, 6.82. Found: C, 77.02;
H, 7.09.
range of transmissn factors
GOFd
R1(Fo), wR2(F02)b (%)e
R1(Fo), wR2(F02)b all (%)
5.46, 12.70
7.38, 13.49
a
b
d
See ref 27. See ref 26. c See ref 28. See ref 30. e See ref 31.
(under solvent peak, corresponds to a methine resonance in
APT spectra), 128.1, 128.3, 129.0, 130.4, 131.8, 138.0, 141.5,
144.9,146.4. Anal. Calcd. (C46H42Hf): C, 71.45; H, 5.47.
Found: C, 69.99; H, 5.30.
[η5-C5H4(CMe2CH2P h )]Hf(CH2P h )3 (2). 6,6-Dimethylful-
vene (57 mg, 0.54 mmol) and tetrabenzylhafnium (242 mg,
0.446 mmol) were placed in a 100 mL round-bottom flask with
4 mL of benzene and a stir bar. The resulting mixture was
heated to 65 °C for 20 h. Benzene and the excess fulvene were
removed in vacuo. Pentane was added and removed in vacuo
twice, giving a pale yellow microcrystalline powder. The
product was extracted with 4 mL of diethyl ether, and the
extracts were filtered and cooled to -35 °C overnight. Pale
yellow plates were isolated and dried under vacuum (187 mg,
0.288 mmol, 64% isolated yield). 1H NMR (C6D6, 400 MHz): δ
1.06 (s, 6H, C5H4C(CH3)2), 1.69 (s, 6H, Hf(CH2Ph)3), 2.54 (s,
2H, C5H4CMe2(CH2Ph)), 5.36 (t, 2H, Cp, 3J HH ) 3 Hz), 5.51 (t,
2H, Cp, 3J HH ) 3 Hz), 6.71 (dd, 6H, Hf(CH2CCHCHCH)3, 4J HH
) 1 Hz, 3J HH ) 8 Hz), 6.72 (d, 2H, under 6.71 ppm peak), 6.92
[η5-C5H4(CMeCH2)]Zr (NMe2)3 (4). 6,6-Dimethylfulvene
(90 mg, 0.85 mmol) and Zr(NMe2)4 (228 mg, 0.854 mmol) were
placed in a 100 mL round-bottom flask with a stir bar and 4
mL of benzene. The resulting mixture was heated to 80 °C for
2 h in the absence of light and cooled and the volatiles were
removed in vacuo. The resulting yellow oil was extracted with
pentane, and the extracts were filtered and placed under
vacuum, giving a highly air sensitive, bright yellow oil (244
mg, 0.743 mmol, 87% isolated yield). 1H NMR (C6D6, 400
4
MHz): δ 1.92 (m, 3H, C5H4C(CH3)dCH2, J HH ) 1 Hz), 2.91
(s, 18H, Zr(N(CH3)2)3), 4.85 (m, 1H, C5H4C(Me)dCHendoHexo
,
2J HH ) 1 Hz), 5.23 (m, 1H, C5H4C(Me)dCHendoHexo, J HH ) 1
2
4
3
3
3
(tt, 3H, Ph H, J HH ) 1 Hz, J HH ) 7 Hz), 7.07-7.17 (m, 9H,
Ph H). 13C{1H} NMR (C6D6, 100 MHz): δ 27.7 (C5H4C(CH3)2-
CH2Ph), 53.0 (C5H4CMe2CH2Ph), 65.9 (C5H4CMe2CH2Ph), 79.4
(Hf(CH2Ph)3), 110.2, 112.9, 123.3, 124.6, 126.5, 129.2, 130.9,
137.3, 138.3, 141.8, 144.7. Anal. Calcd (C36H38Hf): C, 66.61;
H, 5.90. Found: C, 65.90; H, 5.86.
Hz), 6.02 (t, 2H, Cp, J HH ) 3 Hz), 6.16 (t, 2H, Cp, J HH ) 3
Hz). 13C{1H} NMR (C6D6, 100 MHz): δ 21.6 (C5H4C(CH3)d
CH2), 44.8 (Zr(N(CH3)2)3), 94.4 (dCH2), 107.4 (Cp), 109.9
(C5H4C(CH3)dCH2), 110.7 (Cp), 137.9 (Cp). MS: calcd (C14H27N3-
Zr), 327.1243; found, 327.1252.
[η5-C5H4(CMeCH 2)]2Zr (NMe2)2 (5). 6,6-Dimethylfulvene
(187 mg, 1.76 mmol) and Zr(NMe2)4 (236 mg, 0.883 mmol) were
placed in a 100 mL round-bottom flask with a stir bar and 4
mL of benzene. The resulting mixture was heated to 90 °C for
21 h in the absence of light, cooled, and removed of volatiles
in vacuo. The resulting orange-yellow oil was extracted with
pentane, and the extracts were filtered and placed under
vacuum, giving the product as a highly air sensitive orange-
[η5-C5H4(CP h 2CH2P h )]Hf(CH2P h )3 (3). 6,6-Diphenylful-
vene (133 mg, 0.577 mmol) and tetrabenzylhafnium (313 mg,
0.577 mmol) were placed in a 100 mL round-bottom flask with
4 mL of benzene and a stir bar. The resulting mixture was
heated to 65 °C for 29 h. Volatiles were removed in vacuo,
yielding a pale yellow microcrystalline powder (371 mg, 0.479
mmol, 83% isolated yield). Purification by trituration in
pentane for 5 h and filtration gave the product as a tan powder.
1H NMR (C6D6, 400 MHz): δ 1.46 (s, 6H, Hf(CH2Ph)3), 3.81
(s, 2H, C5H4CPh2(CH2Ph)), 5.36 (t, 2H, Cp, 3J HH ) 3 Hz), 5.90
1
yellow oil (282 mg, 0.724 mmol, 82% isolated yield). H NMR
4
(C6D6, 400 MHz): δ 1.86 (m, 6H,, J HH ) 1 Hz), 2.83 (s, 12H,
2
Zr(N(CH3)2)2), 4.85 (m, 2H, C5H4C(Me)dCHendoHexo, J HH ) 2
3
2
(t, 2H, Cp, J HH ) 3 Hz), 6.66 (dd, 6H, Hf(CH2CCHCHCH)3,
Hz), 5.14 (m, 2H, C5H4C(Me)dCHendoHexo, J HH ) 2 Hz), 5.91
3
4
4J HH ) 1 Hz, J HH ) 7 Hz), 6.74 (dd, 2H, Ph H, J HH ) 1 Hz,
3J HH ) 7 Hz), 6.90-7.18 (m, 22H, Ph H). 13C{1H} NMR (C6D6,
125 MHz): δ 45.3 (C5H4CPh2(CH2Ph)), 55.7 (C5H4CPh2(CH2-
Ph)), 80.3 (Hf(CH2Ph)3), 111.5, 113.7, 123.2, 126.6, 127.0, 128.0
3
3
(t, 4H, Cp, J HH ) 3 Hz), 6.17 (t, 4H, Cp, J HH ) 3 Hz). 13C-
{1H} NMR (C6D6, 100 MHz): δ 21.5 (C5H4C(CH3)dCH2), 49.3
(Zr(N(CH3)2)2), 109.6 (dCH2), 109.9 (C5H4C(CH3)dCH2), 110.9
(Cp), 123.7 (Cp), 138.4 (Cp). MS: calcd (C20H30N2Zr), 388.1451;
found, 388.1456.
[η5-C9H6(CMeCH2)]Zr (NMe2)3 (6). 8,8-Dimethylbenzoful-
vene (162 mg, 1.04 mmol) and Zr(NMe2)4 (277 mg, 1.03 mmol)
were placed in a 100 mL round-bottom flask with a stir bar
and 4 mL of benzene. The flask was heated to 85 °C for 22 h
(23) Felten, J . J .; Anderson, W. P. J . Organomet. Chem. 1972, 36,
87.
(24) Yates, P.; Kronis, J . D. Can. J . Chem. 1984, 62, 1751.
(25) 8,8-Dimethylbenzofulvene was prepared in the exact manner
as 6,6-diphenylfulvene.15

3980 Organometallics, Vol. 18, No. 20, 1999
Rogers et al.
in the absence of light and cooled and the volatiles were
removed in vacuo. The resulting orange-yellow oil was ex-
tracted with pentane, and the extracts were filtered and placed
under vacuum, yielding a highly air sensitive, orange-yellow
molybdenum-target X-ray tube operated at 2.0 kW (50 kV, 40
mA). A total of 1321 frames of data (1.3 hemispheres) were
collected using a narrow frame method with scan widths of
0.3° in ω and exposure times of 30 s/frame using a detector-
to-crystal distance of 5.09 cm (maximum 2θ angle of 56.5°).
The total data collection time was approximately 12 h. Frames
were integrated to a maximum 2θ angle of 46.6° with the
Siemens SAINT program to yield a total of 12 511 reflections,
1
oil (348 mg, 0.920 mmol, 89% isolated yield). H NMR (C6D6,
4
400 MHz): δ 2.11 (m, 3H, Ha, J HH ) 1 Hz), 2.76 (s, 18H, Zr-
2
(N(CH3)2)3), 5.20 (m, 1H, Hb, J HH ) 2 Hz), 5.47 (m, 1H, Hc,
3
2J HH ) 2 Hz), 6.18 (d, 1H, Hd, J HH ) 3 Hz), 6.50 (d, 1H, He,
3J HH ) 3 Hz), 6.92 (td, 1H, Hg, 4J HH ) 2 Hz, 3J HH ) 8 Hz), 6.96
of which 4414 were independent (Rint ) 4.17%, Rsigma )
4
3
4
(td, 1H, Hh, J HH ) 2 Hz, J HH ) 8 Hz), 7.52 (dd, 1H, Hf, J HH
5.15%)26 and 3602 were above 2σ(I). Laue symmetry revealed
a monoclinic crystal system, and the final unit cell parameters
(at -80 °C) were determined from the least-squares refinement
of three-dimensional centroids of 6181 reflections.27 Data were
corrected for absorption with the SADABS28 program.
3
4
3
) 1 Hz, J HH ) 8 Hz), 7.94 (dd, 1H, Hi, J HH ) 1 Hz, J HH ) 8
Hz).
Assignments were made according to
The space group was assigned as P21/c, and the structure
was solved by using direct methods and refined employing full-
matrix least squares on F2 (Siemens, SHELXTL,29 version
5.04). For a Z value of 4, there is one molecule, and a
disordered partially occupied pentane was located in the
asymmetric unit. All of the non-H atoms, except those of
pentane, were refined with anisotropic thermal parameters,
and hydrogen atoms were included in idealized positions giving
a data to parameter ration of greater than 10:1. H atoms were
not included for the pentane. The structure was refined to a
goodness of fit (GOF)30 of 0.952 and final residuals31 of R1 )
5.46% (I > 2σ(I)) and wR2 ) 12.7% (I > 2σ(I)).
13C{1H} NMR (C6D6, 100 MHz): δ 23.9 (IndC(CH3)dCH2),
44.0 (Zr(N(CH3)2)3), 97.1 (dCH2), 111.4, 114.7, 115.7, 122.6,
123.2, 123.3, 125.0, 126.4, 127.4, 139.5. MS: calcd (C18H29N3-
Zr), 377.1418; found, 377.1409.
Str u ctu r e Deter m in a tion for 1. Crystal data are sum-
marized in Table 1. A yellow crystal of approximate dimensions
0.12 × 0.14 × 0.16 mm3 was mounted under Paratone-8277
onto a glass fiber and immediately placed in a cold nitrogen
stream at -80 °C on the X-ray diffractometer. The X-ray
intensity data were collected on a standard Siemens SMART
CCD area detector system equipped with a normal focus
Ack n ow led gm en t. G.C.B. is an Alfred Sloan Fellow
and a Henry and Camille Dreyfus Teacher-Scholar. We
are grateful to the donors of the Petroleum Research
Fund (administered by the American Chemical Society)
and the Department of Energy (Contract No. DE-FG03-
98ER14910) for financial assistance and to Dr. J ames
Pavlovich for assistance with mass spectrometry mea-
surements.
2
(26) Rint ) |Fo - Fo2(mean)/[Fo2]; Rsigma ) [σ(Fo2)]/[Fo2].
(27) It has been noted that the integration program SAINT produces
cell constant errors that are unreasonably small, since systematic error
is not included. More reasonable errors might be estimated at 10×
the listed value.
(28) The SADABS program is based on the method of Blessing;
see: Blessing, R. H. Acta Crystallogr., Sect A 1995, 51, 33.
(29) SHELXTL: Structure Analysis Program, version 5.04; Siemens
Industrial Automation Inc., Madison, WI, 1995.
Su p p or tin g In for m a tion Ava ila ble: Tables and a figure
giving complete details for the crystallographic structure
analysis of 1. This material is available free of charge via the
Internet at http://pubs.acs.org.
(30) GOF ) [∑[w(Fo - Fc2)2]/(n - p)]1/2, where n and p denote the
2
number of data and parameters.
(31) R1 ) ∑(||Fo| - |Fc||)/∑|Fo|; wR2 ) [∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]]1/2
,
where w ) 1/[σ2(Fo2) + (aP)2 + bP] and P ) [(Max;0, Fo2) + 2Fc2]/3.
OM990402J