A fulvene route to group 4 metallocene complexes bearing 4,7-bis(dimethylamino)-substituted indenyl ligands

Article abstract of DOI:10.1002/ejic.200300799

N,N,N′,N′-Tetramethylsuccinamide (15) was selectively converted into the functionalized aminofulvene 16. Subsequent treatment with reagent 17, [ZrCl₂(NMe₂)₂(L)₂] (L = THF or 0.5 DME), resulted in the formation of the cyclization product 4,7- bis(dimethylamino)indene (21). Deprotonation with n-butyllithium, followed by the reaction of the resulting substituted indenyllithium reagent 22 with ZrCl₄, gave the metallocene [4,7-bis(dimethylamino)indenyl] ₂ZrCl₂ (23). The reaction of 22 with ZrCl₃Cp furnished the complex [4,7-bis(dimethylamino)indenyl]CpZrCl₂ (24). Fulvene 16, as well as the metallocene dichlorides 23 and 24, were characterized by X-ray diffraction. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200300799

FULL PAPER
A Fulvene Route to Group 4 Metallocene Complexes Bearing
4,7-Bis(dimethylamino)-Substituted Indenyl Ligands
Jesus Cano Sierra,[a] Sierra Gerald Kehr,[a] Roland Fröhlich,[a][‡] and Gerhard Erker*[a]
Keywords: Aminofulvenes / Cyclopentadienide / Zirconium / Ring-closure / Sandwich complexes
N,N,NЈ,NЈ-Tetramethylsuccinamide (15) was selectively con-
verted into the functionalized aminofulvene 16. Subsequent
treatment with reagent 17, [ZrCl2(NMe2)2(L)2] (L = THF or
0.5 DME), resulted in the formation of the cyclization product
4,7-bis(dimethylamino)indene (21). Deprotonation with n-
butyllithium, followed by the reaction of the resulting substi-
cene [4,7-bis(dimethylamino)indenyl]2ZrCl2 (23). The reac-
tion of 22 with ZrCl3Cp furnished the complex [4,7-bis(dime-
thylamino)indenyl]CpZrCl2 (24). Fulvene 16, as well as the
metallocene dichlorides 23 and 24, were characterized by X-
ray diffraction.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
tuted indenyllithium reagent 22 with ZrCl4, gave the metallo- Germany, 2004)
Introduction
Fulvenes are often used as precursors for the preparation
of cyclopentadienyl ligands and related systems. Most of
these syntheses make use of the electrophilicity of the ful-
vene C6 carbon center, which allows the formation of sub-
stituted cyclopentadienides by means of nucleophilic ad-
dition (a) or deprotonation (b) (see Scheme 1).[1Ϫ3]
Scheme 2
Scheme 1
The unsymmetrical 1,4-diketone 8 allowed the selective
preparation of the mono(fulvene) 9 (see Scheme 3). Its
treatment with a cuprate nucleophile yielded the substituted
tetrahydroindenyl ligand precursor 10.[8] Similarly, the mon-
o(fulvene) 12 was derived from 11. In this case the sub-
sequent nucleophilic attack did not result in a related ring-
We have already synthesized substituted indenyl ligands
by a series of related reactions. The reaction of 2,5-hexane-
dione (4) with cyclopentadienide under ‘‘Thiele con-
ditions’’[4] (pathway [a] in Scheme 2) gave the ring-closed
4,7-dimethylindene product 5,[5] whereas the related reac-
tion under ‘‘Stone/Little conditions’’ ([b] in Scheme 2)[6]
furnished the respective bis(fulvene) 6, which was sub-
sequently used as a starting material for the preparation
of the ligand system 7 and of ansa-metallocenes derived
thereof.[7]
[a]
Organisch-Chemisches Institut der Universität Münster
Corrensstr. 40, 48149 Münster, Germany
Fax: (internat.) ϩ 49-251-83-36503
E-mail: erker@uni-muenster.de
[‡]
X-ray crystal-structure analyses.
Scheme 3
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200300799
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A Fulvene Route to Group 4 Metallocene Complexes
FULL PAPER
˚
closure reaction but led to the clean formation of the func- C6. The C6ϪN1 bond length amounts to 1.337(2) A, which
˚
tionalized Cp derivative 13 instead, which was used in the is slightly shorter than the C9ϪN2 distance [1.349(2) A] of
metallocene synthesis.[9]
the delocalized pendent ϪCONMe2 functional group
˚
We now used succinamide 15 as the starting material for [C9ϪO 1.222(2) A]. In the crystal, compound 16 attains
a series of related reactions, based on the initial formation a conformation that is characterized by the antiperiplanar
of a substituted 6-(dimethylamino)fulvene. In this case we central section of the substituent chain [dihedral angle
observed a clean ring-closure reaction to yield the corre- θ(C6ϪC7ϪC8ϪC9) ϭ Ϫ173.1(2)°] with a gauche arrange-
sponding 4,7-bis(dimethylamino)indene product 21 upon ment at the junction with the fulvene nucleus
treatment with a mild Lewis acid (see Scheme 4). Details of [θ(C1ϪC6ϪC7ϪC8) ϭ 89.8(2)°].
this reaction series, which complements the family of ful-
vene-to-indene conversions summarized above, are de-
scribed in this account.
Figure 1. View of the carboxamide-functionalized aminopentaful-
˚
vene system 16; selected bond lengths [A] and angles [°]: C1ϪC2
1.450(2), C2ϪC3 1.355(3), C3ϪC4 1.421(3), C4ϪC5 1.357(3),
C5ϪC1 1.438(3), C1ϪC6 1.399(2), C6ϪN1 1.337(2), C6ϪC7
1.511(2), C7ϪC8 1.527(2), C8ϪC9 1.515(2), C9ϪO 1.222(2),
C9ϪN2 1.349(2); C2ϪC1ϪC5 105.1(2), C2ϪC1ϪC6 130.1(2),
C5ϪC1ϪC6 124.7(2), C1ϪC6ϪN1 124.9(2), C1ϪC6ϪN7 118.3(2),
N1ϪC6ϪC7 116.8(2), C6ϪC7ϪC8 112.1(1), C7ϪC8ϪC9 111.5(1),
C8ϪC9ϪO 120.9(1), C8ϪC9ϪN2 117.0(2), OϪC9ϪN2 122.1(2)
Fulvene 16 was treated with
1
mol-equiv. of
[ZrCl2(NMe2)2·DME][11] (17a) in toluene at reflux tempera-
tures for 3 h. Workup and extraction with pentane fur-
nished the metal-free organic product 4,7-bis(dimethylami-
no)indene (21) as a pale yellow liquid in close to 90 % yield.
The product is characterized by a pair of 1H NMR
(NCH3)2 singlets (δ ϭ 2.60 and 2.65 ppm), each rep-
resenting six hydrogen atoms. We monitored a set of four
indene methine-proton resonances (δ ϭ 6.31, 6.77, 6.83,
and 7.21 ppm) and the indene CH2 1H NMR signal at δ ϭ
Scheme 4
Results and Discussion
Our synthetic scheme started from succinyl dichloride 3.31 (2 H) ppm.
(14), which was treated with dimethylamine to yield the cor-
Weingarten et al. have shown that ketene aminals are
responding diamide 15. The bifunctional carboxylic acid formed upon treatment of suitably substituted carboxamide
derivative 15 was then selectively converted into its mono- starting materials with, for example, Zr(NMe2)4.[12] It seems
(fulvene) derivative 16. For this purpose, we applied a that the here observed reaction sequence of the transform-
method that was developed by Hafner et al. for the syn- ation 16 Ǟ 21 is initiated by a similar conversion of the
thesis of amino-substituted pentafulvenes.[10] The succin- N,N-dimethylcarboxamide functional group. We observed
amide 15 was mono-O-alkylated by treatment with that treatment of 16 with a stoichiometric quantity of the
Meerwein’s reagent, [Et3Oϩ][BF4Ϫ], and the resulting, stabi- reagent [ZrCl2(NMe2)2·2THF][11b] (17b) in toluene at room
lized carbenium ion reacted with sodium cyclopentadienide temperature gives the corresponding ketene aminal system
to selectively yield the aminopentafulvene 16, which bears 18. The intermediate 18 was not isolated in a pure form,
a residual ϪCONMe2 functional group (92 % isolated). The but was obtained, after washing with pentane, as a solid
fulvene system 16 was characterized by X-ray diffraction that was probably still admixed with the zirconium-contain-
(see Figure 1). It shows the typical features of an amino- ing reaction product (perhaps ZrOCl2 or a derivative ther-
pentafulvene moiety with alternating double and single eof). Subsequent heating of this mixture in toluene eventu-
bonds (see Figure 1) and a trigonal-planar carbon center, ally gave rise to the formation of 21.
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J. C. Sierra, S. G. Kehr, R. Fröhlich, G. Erker
FULL PAPER
The intermediate 18 was characterized spectroscopically.
Both 23 and 24 were characterized by X-ray crystal struc-
Its 1H NMR spectrum shows four clearly separated fulvene ture analyses. Complex 23 is C2-symmetric in the crystal.
methine-hydrogen resonances at δ ϭ 7.09, 6.97, 6.86 and The symmetry-equivalent indenyl ligands are η5-bound to
6.79 ppm (in [D6]benzene) in addition to the typical ketene the zirconium atom through their five-membered rings, al-
1
3
aminal H NMR resonance at δ ϭ 3.62 (t, J ϭ 6 Hz, 1 H) though in a rather unsymmetrical way: the bonds between
ppm. The adjacent CH2 group gives rise to a 1H NMR the zirconium atom and the ‘‘external’’ CH centers are
doublet (3J ϭ 6 Hz) at δ ϭ 3.38 ppm. Compound 18 gives short [ZrϪC1 2.467(3), ZrϪC2 2.484(3), ZrϪC3 2.540(3)
rise of three different NMe2 1H NMR singlets at δ ϭ 2.68 A], whereas the ZrϪC linkages to the internal indenyl car-
˚
(6 H, ‘‘fulvene’’-NMe2) and δ ϭ 2.48/2.12 [each 6 H, (Z)- bon atoms are markedly longer [see Figure 2; ZrϪC4
˚
and (E)-ketene aminal-NMe2] ppm. The fulvene carbon 2.639(3), ZrϪC9 2.579(3) A]. The ZrϪCl bond length in
center (C4ϪNMe2) gives rise to a 13C NMR feature at δ ϭ complex 23 amounts to 2.417(1) A.
˚
161.2 ppm, whereas the carbon atoms of the ϪCHϭ
C(NMe2)2 ketene aminal show 13C NMR resonances at δ ϭ
1
156.2 (C1) and 88.4 (C2, JC,H ϭ 157 Hz) ppm; the C3 res-
1
onance was found at δ ϭ 32.6 ppm with JC,H ϭ 133 Hz.
We assume that the observed ring-closure reaction that
eventually yields the indene derivative 21 is initiated by acti-
vation of the ketene aminal intermediate 18 by protonation
or addition of a zirconium-based Lewis-acid catalyst at the
C2 carbon atom (see Scheme 4). Intramolecular nucleo-
philic addition of the Me2N-activated cyclopentadienide
ring at the strongly electrophilic incipient amidinium moi-
ety would then give the product framework. Removal of
the Hϩ (or ZrOCl2 Lewis acid) catalyst with concomitant
dimethylamine elimination and tautomerization would di-
rectly lead to the observed product 21.
Treatment of 21 with n-butyllithium results in depro-
tonation and formation of the substituted indenyllithium
1
reagent 22, which exhibits the expected H NMR features
of a C2v-symmetry averaged structure in [D6]benzene/
[D8]THF (10:1) solution at ambient temperature [δ ϭ 6.80
(t, 1 H, 2-H), 6.42 (d, 2 H, 1-H and 3-H), 6.32 (s, 2 H, 5-
H and 6-H), 2.94 (s, 12 H, NMe2) ppm; see Scheme 5].
Figure 2. View of the molecular structure of complex 23 (with un-
˚
systematic atom-numbering scheme); selected bond lengths [A] and
angles [°]: ZrϪCl 2.417(1), ZrϪC1 2.467(3), ZrϪC2 2.484(3),
ZrϪC3 2.540(3), ZrϪC4 2.639(3), ZrϪC9 2.579(3), C1ϪC2
1.393(5), C1ϪC9 1.439(4), C2ϪC3 1.398(5), C3ϪC4 1.427(5),
C4ϪC9 1.444(4), C8ϪC9 1.436(4), C4ϪC5 1.422(4), C8ϪN81
1.422(4), C5ϪN51 1.417(4); ClϪZrϪCl* 98.80(5), C1ϪC2ϪC3
109.9(3), C2ϪC1ϪC9 107.6(3), C2ϪC3ϪC4 108.3(3), C1ϪC9ϪC8
132.9(3),
C3ϪC4ϪC5
132.0(3),
C9ϪC8ϪN81
119.0(3),
C4ϪC5ϪN51 118.0(3)
In the crystal, complex 23 features a chiral metallocene
conformation, in which the indenyl six-membered rings
point to different lateral sides of the bent metallocene
wedge. This leads to a spatial differentiation of the ϪNMe2
substituents at each of the indenyl ligands: the Me2N51
group points toward the open-front side and the Me2N81
substituent is oriented toward the narrow back side of the
bent metallocene wedge (see Figure 2). In solution this dif-
ferentiation is not observed: here rapid rotation about the
zirconiumϪCp(centroid) vector leads to symmetry-aver-
aged NMR spectra (for details see the Exp. Sect.).
Complex 24 shows an η5-Cp ligand that is rather uni-
formly coordinated to the zirconium atom [with ZrϪC(Cp)
bond lengths ranging from 2.483(2) to 2.537(2) A]. The
Scheme 5
˚
bonding features of the substituted indenyl ligand are very
Reagent 22 was used for the preparation of two zir- similar to those found in the related complex 23 (see above
conocene complexes. Treatment of ZrCl4 with 22 in a tolu- and Figure 3). The single η5-bis(4,7-dimethylamino)indenyl
ene suspension gave bis[4,7-bis(dimethylamino)inden- ligand in complex 24 has a similar conformational orien-
yl]ZrCl2 (23). Similarly, the reaction of reagent 22 with tation to that of the ligands in 23. In 24 the indenyl ligand
[13]
CpZrCl3
gave the mixed indenyl/Cp-zirconium complex has its substituted phenylene moiety oriented towards the
24 (isolated in ca. 70 % yield).
lateral side of the bent metallocene wedge.
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A Fulvene Route to Group 4 Metallocene Complexes
FULL PAPER
crystals for X-ray crystal-structure analysis[14] were obtained from
a concentrated solution in diethyl ether (14.8 g, 91 %). 1H NMR
(CDCl3): δ ϭ 3.03 (s, 6 H, NMe), 2.92 (s, 6 H, NMe), 2.64 (s, 4 H,
CH2) ppm. 13C{1H} NMR (CDCl3): δ ϭ 172.1 (CO), 36.9 (NMe),
35.3 (NMe), 28.1 (CH2). C8H16N2O2 (172.22): calcd. C 55.79, H
9.36, N 16.27; found C 55.65, H 9.38, N 15.84.
Preparation of Fulvene 16: A CH2Cl2 solution of [Et3Oϩ][BF4
]
Ϫ
(14.71 g, 77.4 mmol) was added to a CH2Cl2 solution of 15
(13.31 g, 77.4 mmol) at Ϫ30 °C. The orange solution was allowed
to warm to room temperature and stirred for 2 h. The solvent was
removed under vacuum, leading to an oily product. The brown
oil was frozen with liquid nitrogen, a solution of NaCp (6.81 g,
77.4 mmol) in THF, cooled to Ϫ40 °C, was immediately added and
the solution was stirred overnight. The THF was evaporated to
dryness and the residue extracted and recrystallized with diethyl
ether to yield 16, as a crystalline solid. Suitable crystals for X-
ray crystal-structure analysis were obtained from a concentrated
solution in diethyl ether (15.7 g, 92 %). 1H NMR (CDCl3): δ ϭ
6.60, 6.56, 6.43, 6.31 (each broad, each 1 H, fulvene), 3.35 (s, 6 H,
4-NMe), 3.18 (m, 2 H, CH2), 2.96, 2.95 (each s, each 3 H, 1-NMe),
2.63 (m, 2 H, CH2) ppm. 13C{1H} NMR (CDCl3): δ ϭ 170.8 (C1),
161.3 (C4), 122.3, 119.9, 119.7, 117.0 (fulvene), 117.1 (C5), 43.7 (4-
NMe), 37.0, 35.5 (1-NMe), 33.8 (C2), 28.6 (C3) ppm. C13H20N2O
(220.31): calcd. C 70.87, H 9.15, N 12.72; found C 70.56, H 9.27,
N 12.49.
Figure 3. Molecular structure of complex 24; selected bond lengths
˚
[A] and angles [°]: ZrϪCl1 2.440(1), ZrϪCl2 2.441(1), ZrϪC1
2.477(2), ZrϪC2 2.508(2), ZrϪC3 2.527(2), ZrϪC4 2.601(2),
ZrϪC9 2.577(2), ZrϪC10 2.494(2), ZrϪC11 2.537(2), ZrϪC12
2.514(2), ZrϪC13 2.483(2), ZrϪC14 2.492(2), C1ϪC2 1.404(3),
C1ϪC9 1.440(3), C2ϪC3 1.403(3), C3ϪC4 1.439(3), C4ϪC9
1.438(3), C8ϪC9 1.433(3), C4ϪC5 1.427(3), C8ϪN81 1.411(3),
C5ϪN51 1.421(3); Cl1ϪZrϪCl2 96.98(2), C1ϪC2ϪC3 109.9(2),
C2ϪC1ϪC9 107.5(2), C2ϪC3ϪC4 107.6(2), C1ϪC9ϪC8 132.4(2),
C3ϪC4ϪC5 131.5(2), C9ϪC8ϪN81 118.7(2), C4ϪC5ϪN51
118.1(2)
Conclusion
X-ray Crystal-Structure Analysis of 16: Empirical formula
C13H20N2O, M ϭ 220.31, yellow-orange crystal 0.20 ϫ 0.15 ϫ
We conclude that treatment of the functionalized fulvene
system 16 with the zirconium reagent 17 provides a very
convenient and selective synthetic pathway to 4,7-bis(dialk-
ylamino)indene systems. We have also shown that these can
be easily attached at electrophilic transition-metal centers
to yield the respective metallocene systems. The specific in-
fluence of the nucleophilic ϪNR2 substituents on the
properties of such organometallic compounds will be inves-
tigated in the future.
˚
0.10 mm, a ϭ 10.390(1), b ϭ 13.607(1), c ϭ 8.946(1) A, β ϭ
3
90.54(1)°, V ϭ 1264.7(2) A , Dcalcd. ϭ 1.157 g cmϪ3, µ ϭ 5.79 cmϪ1
,
˚
no absorption correction (0.893 Յ T Յ 0.944), Z ϭ 4, monoclinic,
˚
space group P21/c (No. 14), λ ϭ 1.54178 A, T ϭ 223 K, ω/2θ scans,
2731 reflections collected (Ϯh, Ϫk, Ϫl), [(sinθ)/λ] ϭ 0.62 AϪ1, 2562
˚
independent (Rint. ϭ 0.035) and 1763 observed reflections [I Ն
2σ(I)], 150 refined parameters, R ϭ 0.047, wR2 ϭ 0.133, max. re-
sidual electron density 0.18 (Ϫ0.16) e·AϪ3, hydrogen atoms calcu-
˚
lated and refined as riding atoms.
Formation of the Ketene Aminal Intermediate 18: Toluene (100 mL)
was added to a Schlenk flask containing 16 (0.28 g, 1.3 mmol) and
[Zr(NMe2)2Cl2·THF2] (17b) (0.51 g, 1.3 mmol). The resulting solu-
tion was stirred at room temperature for 1 h, concentrated to dry-
ness and washed with pentane to give 18 as a light brown solid
Experimental Section
General Remarks: All reactions were carried out under dry argon
in Schlenk-type glassware or in a glove box. Solvents, including
deuterated solvents used for NMR spectroscopy, were dried and
distilled prior to use. For additional general conditions, including
a list of instruments used for physical characterization of the com-
pounds, see reference.[9]
1
(0.59 g). H NMR (C6D6): δ ϭ 7.09 (m, 1 H, 6-H), 6.97 (m, 1 H,
8-H), 6.86 (m, 1 H, 7-H), 6.79 (m, 1 H, 9-H), 3.62 (t, JH,H ϭ 6.3 Hz,
1 H, 2-H), 3.39 (d, JH,H ϭ 6.3 Hz, 2 H, 3-H), 2.68 (s, 6 H, 4-NMe),
2.48 [s, 3 H, 1-NMe(Z)], 2.12 [s, 6 H, 1-NMe(E)] ppm. 13C{1H}
NMR (C6D6): δ ϭ 161.2 (C4), 156.2 (C1), 123.3 (C8), 121.4 (C6),
120.3 (C7), 119.0 (C5), 118.1 (C9), 88.4 (C2, 1JC,H ϭ 157 Hz), 42.8
(NMe-4), 40.6 [NMe(Z)], 40.6 [NMe(E)], 32.6 (C3) ppm. 1H-13C
GHSQC (C6D6): δ(13C)/δ(1H) ϭ 123.3/6.97 (8-CH), 121.4/7.09 (6-
CH), 120.3/6.86 (7-CH), 118.1/6.79 (9-CH), 88.4/3.62 (2-CH), 42.8/
Preparation of C2H4(CONMe2) (15): Succinyl dichloride (14.7 g,
94 mmol) was added dropwise to a solution of NMe2H (24 g,
520 mmol) in diethyl ether at Ϫ78 °C. The mixture was allowed to
warm to room temperature, stirred for 15 min, and filtered to sep-
2.68 (4-NMe), 40.6/2.48 [1-NMe(Z)], 40.6/2.12 [1-NMe(E)], 32.6/3.39
1
arate the ammonium salt. The residue was extracted with THF (2 (3-CH2). H-13C GHMBC (C6D6): δ(13C)/δ(1H) ϭ 161.2/3.39, 2.68
ϫ 200 mL) and the solvent was removed under vacuum. The re-
sulted solid was recrystallized from diethyl ether (5 mL) and cooled
to Ϫ35 °C to give 15 as a light white crystalline solid. Suitable
(C4/3-H, 4-NMe), 156.2/3.39, 2.48, 2.12 [C1/3-H, 1-NMe(Z), 1-
NMe(E)], 119.0/3.39 (C5/3-H). 1D TOCSY (C6D6): δ(1Hirr)/
δ(1Hres) ϭ 7.09/6.97, 6.86, 6.79 (6-H/8-H, 7-H, 9-H), 3.62/3.39 (2-
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J. C. Sierra, S. G. Kehr, R. Fröhlich, G. Erker
FULL PAPER
H/3-H). NOE (C6D6): δ(1Hirr)/δ(1Hres) ϭ 2.12/2.48, 3.62 [1-NMe(E)
/
temperature for 12 h. After filtration, the solvent was removed un-
1-NMe(Z), 2-H]; 2.48/2.12, 3.39 [1-NMe(Z)/1-NMe(E), 3-H]; 2.68/
der vacuum and the residue was washed with pentane (2 ϫ 50 mL)
3.39, 3.62, 6.79 (4-NMe/3-H, 2-H, 9-H); 3.39/2.48, 2.68, 3.62, 7.09 to give 24 as a red crystalline solid (0.61 g, 71 %). 1H NMR
[3-H/1-NMe(Z), 4-NMe, 2-H, 6-H]; 3.62/2.12, 3.39 [2-H/1-NMe(E)
3-H].
,
(CD2Cl2): δ ϭ 6.73 (t, JH,H ϭ 3.2 Hz, 1 H, 2-H), 6.71 (d, JH,H ϭ
3.2 Hz, 2 H, 1,3-H), 6.52 (s, 2 H, 5,6-H), 6.24 (s, 5 H, Cp), 2.92 (s,
6 H, NMe) ppm. 13C{1H} NMR (CD2Cl2): δ ϭ 145.0 (C4,7), 123.9
(C3a,7a), 123.5 (C2), 118.7 (Cp), 113.3 (C5,6), 105.2 (C1,3), 44.8
(NMe) ppm. C18H22Cl2N2Zr (428.50): calcd. C 50.45, H 5.17, N
6.54; found C 50.67, H 5.37, N 6.48.
X-ray Crystal-Structure Analysis of 24: Formula C18H22Cl2N2Zr,
M ϭ 428.50, red crystal 0.15 ϫ 0.15 ϫ 0.05 mm, a ϭ 7.919(1), b ϭ
3
˚
˚
13.135(1), c ϭ 17.552(1) A, V ϭ 1825.7(3) A , Dcalcd. ϭ 1.559 g
cmϪ3, µ ϭ 8.95 cmϪ1, empirical absorption correction with SOR-
TAV (0.877 Յ T Յ 0.957), Z ϭ 4, orthorhombic, space group
Preparation of the Substituted Indene 21: Toluene (100 mL) was ad-
ded to a Schlenk flask containing 16 (1.06 g, 4.6 mmol) and
[Zr(NMe2)2Cl2·DME] (17a) (2.10 g, 4.6 mmol) and the mixture vig-
orously stirred at room temperature for 3 h. The resulting red solu-
tion was filtered, the solvent removed under vacuum and the resi-
due extracted with pentane to yield 19 as a yellow liquid (0.82 g,
88 %). 1H NMR (C6D6): δ ϭ 7.21, 6.31 (each dt, JH,H ϭ 5.6,
1.9 Hz,·each 1 H, 2,3-H), 6.83, 6.77 (AB JH,H ϭ 8.7 Hz,·each 1 H,
5,6-H), 3.31 (t, JH,H ϭ 1.9 Hz, 2 H, CH2), 2.65, 2.60 (each s, each
6 H, NMe) ppm. 13C{1H} NMR (C6D6): δ ϭ 145.1, 143.1 (C4,7),
139.5, 137.1 (C3a,7a), 132.3, 130.9 (C2,3), 116.0, 114.9 (C5,6), 44.6,
43.6 (NMe2), 39.3 (CH2) ppm. C13H18N2 (202.29): calcd. C 77.18,
H 8.97, N 13.85; found C 76.73, H 9.20, N 13.86.
˚
P212121 (No. 19), λ ϭ 0.71073 A, T ϭ 198 K, ω and ϕ scans, 12933
reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] ϭ 0.65 AϪ1, 4158 inde-
˚
pendent (Rint ϭ 0.034) and 3879 observed reflections [I Ն 2 σ(I)],
213 refined parameters, R ϭ 0.024, wR2 ϭ 0.052, max. residual
electron density 0.24 (Ϫ0.57) e·AϪ3, refined as a racemic twin with
˚
a ratio of 0.67(3):0.33, hydrogen atoms calculated and refined as
riding atoms.
X-ray Crystallographic Study: Data sets were collected with
EnrafϪNonius CAD4 and Nonius KappaCCD diffractometers;
the latter was equipped with a rotating anode generator, Nonius
FR591. Programs used: data collection EXPRESS (Nonius B. V.,
1994) and COLLECT (Nonius B. V., 1998), data reduction MolEN
(K. Fair, EnrafϪNonius B. V., 1990) and Denzo-SMN (Z. Ot-
winowski, W. Minor, Methods Enzymol. 1997, 276, 307Ϫ326), ab-
sorption correction for CCD data SORTAV (R. H. Blessing, Acta
Crystallogr., Sect. A 1995, 51, 33Ϫ37; R. H. Blessing, J. Appl. Crys-
tallogr. 1997, 30, 421Ϫ426), structure solution SHELXS-97 (G. M.
Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467Ϫ473), structure
refinement SHELXL-97 (G. M. Sheldrick, Universität Göttingen,
1997), graphics SCHAKAL (E. Keller, Universität Freiburg, 1997).
CCDC-220797, -220798 and -220799 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223/336-
033; E-mail: deposit@ccdc.cam.ac.uk].
Preparation of the Indenyllithium Reagent 22: BuLi (1.6 ) was ad-
ded to a solution of 19 (0.56 g, 2.77 mmol) in pentane (150 mL),
cooled to Ϫ78 °C. The white suspension formed was warmed
slowly to room temperature and stirred for 12 h. Filtration and
removal of the solvent at reduced pressure gave 22 as a white solid
(0.55 g, 95 %). 1H NMR (C6D6, TDF): δ ϭ 6.80 (t, JH,H ϭ 3.4 Hz,
1 H, 2-H), 6.42 (d, JH,H ϭ 3.4 Hz, 2 H, 1,3-H), 6.32 (s, 2 H, 5,6-
H), 2.94 (s, 12 H, NMe) ppm. 13C{1H} NMR (C6D6, TDF): δ ϭ
142.1 (C4,7), 122.9 (C3a,7a), 112.7 (C2), 101.8 (C5,6), 92.2 (C1,3),
44.0 (NMe) ppm.
Preparation of the Zirconium Complex 23: ZrCl4 (0.156 g,
0.67 mmol) was added to a suspension of 22 (0.28 g, 1.34 mmol) in
toluene (100 mL) at Ϫ40 °C. The cooling bath was removed and
the reaction mixture stirred at room temperature for 12 h. After
filtration, the solvent was removed under vacuum and the residue
washed with pentane (2 ϫ 50 mL) to give 23 as a red crystalline
solid (0.21 g, 57 %). 1H NMR (CD2Cl2): δ ϭ 6.77 (d, JH,H
ϭ
3.0 Hz, 2 H, 1,3-H), 6.50 (s, 2 H, 5,6-H), 6.08 (t, JH,H ϭ 3.0 Hz, 1
H, 2-H), 2.90 (s,·12 H, NMe) ppm. 13C{1H} NMR (CD2Cl2): δ ϭ
143.2 (C4,7), 123.4 (C3a,7a), 118.8 (C2), 111.9 (C5,6), 104.3 (C1,3),
43.3 (NMe) ppm. C26H34Cl2N4Zr (564.70): calcd. C 55.30, H 6.07,
N 9.92; found C 55.15, H 6.14, N 9.72.
Acknowledgments
Financial support from the Fonds der Chemischen Industrie and
the Deutsche Forschungsgemeinschaft is gratefully acknowledged.
J. C. S. thanks the Alexander-von-Humboldt-Stiftung for a fellow-
ship.
X-ray Crystal-Structure Analysis of 23: Empirical formula
C26H34Cl2N4Zr, M ϭ 564.69, red crystal 0.15 ϫ 0.05 ϫ 0.03 mm,
3
˚
˚
a ϭ 41.733(1), b ϭ 7.036(1), c ϭ 17.528(1) A, V ϭ 5146.8(8) A ,
Dcalcd. ϭ 1.458 g cmϪ3, µ ϭ 6.57 cmϪ1, empirical absorption cor-
rection with SORTAV (0.908 Յ T Յ 0.981), Z ϭ 8, orthorhombic,
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space group Fdd2 (No. 43), λ ϭ 0.71073 A, T ϭ 198 K, ω and ϕ
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www.eurjic.org
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2265