Chiral bis(η5:η1-pentafulvene)titanium complexes

Article abstract of DOI:10.1021/om050815m

The series of bis(pentafulvene)titanium complexes (η⁶-C ₅H₄=CR₂)₂Ti (=CR₂ = C(p-tol)₂ (3), adamantyl (4)) and their corresponding bis(benzofulvene) derivatives (η⁶-C₉H ₆=CR₂)₂Ti (=CR₂ = C(p-tol) ₂ (7), adamantyl (8)) have been synthesized by reaction of TiCl ₃·3THF with the pentafulvene ligands (2 equiv) and magnesium as reducing agent (1.5 equiv). The bis(fulvene) complexes 7 and 8 have been obtained as diastereomerically pure compounds. All complexes have been characterized by spectroscopy and by single-crystal X-ray diffraction. The bonding situation is best described as a π-η⁵:σ- η¹ coordination mode. The bis(fulvene) complex 3 is approximately C₂ symmetric, whereas 7 crystallizes as a conglomerate in the monoclinic space group P2₁ and one of the enantiomers was identified as a (S,pS,pR) stereoisomer showing C₁ symmetry. The adamantyl benzofulvene complex 8 crystallizes in the monoclinic space group P2 ₁/c; both benzofulvene ligands are coordinated as optical antipodes, and a (S,pS,pR)/(R,pR,pS) configuration is found in the solid state. Reaction of 3 and 7 with HCl/Et₂O leads to the corresponding bis(cyclopentadienyl)titanium chlorides (η⁵-C₅H ₄-CHR₂)₂TiCl₂ (R = p-tol (9)) and the bis(indenyltitanium) derivative (η⁵-C₉H ₆-CHR₂)₂TiCl₂ (R = p-tol₂ (10)).

Full text of DOI:10.1021/om050815m

Organometallics 2006, 25, 339-348
339
Chiral Bis(η5:η1-pentafulvene)titanium Complexes
Mira Diekmann, Geert Bockstiegel, Arne Lu¨tzen, Marion Friedemann, Wolfgang Saak,
Detlev Haase, and Ru¨diger Beckhaus*
Institute of Pure and Applied Chemistry, UniVersity of Oldenburg, D-26111 Oldenburg, Germany
ReceiVed September 21, 2005
The series of bis(pentafulvene)titanium complexes (η6-C5H4dCR2)2Ti (dCR2 ) C(p-tol)2 (3), adamantyl
(4)) and their corresponding bis(benzofulvene) derivatives (η6-C9H6dCR2)2Ti (dCR2 ) C(p-tol)2 (7),
adamantyl (8)) have been synthesized by reaction of TiCl3‚3THF with the pentafulvene ligands (2 equiv)
and magnesium as reducing agent (1.5 equiv). The bis(fulvene) complexes 7 and 8 have been obtained
as diastereomerically pure compounds. All complexes have been characterized by spectroscopy and by
single-crystal X-ray diffraction. The bonding situation is best described as a π-η5:σ-η1 coordination mode.
The bis(fulvene) complex 3 is approximately C2 symmetric, whereas 7 crystallizes as a conglomerate in
the monoclinic space group P21 and one of the enantiomers was identified as a (S,pS,pR) stereoisomer
showing C1 symmetry. The adamantyl benzofulvene complex 8 crystallizes in the monoclinic space group
P21/c; both benzofulvene ligands are coordinated as optical antipodes, and a (S,pS,pR)/(R,pR,pS)
configuration is found in the solid state. Reaction of 3 and 7 with HCl/Et2O leads to the corresponding
bis(cyclopentadienyl)titanium chlorides (η5-C5H4-CHR2)2TiCl2 (R ) p-tol (9)) and the bis(indenyltitanium)
derivative (η5-C9H6-CHR2)2TiCl2 (R ) p-tol2 (10)).
exchange reaction of bis(η6-toluene)titanium(0) and 6,6-di-
phenylfulvene.8 Additionally, cyclopentadienyltitanium fulvene
complexes of the type (η5-C5R5)Ti(Cl)(η6-C5H4dCR2) are
formed by reductive complexation of pentafulvenes.9 Here, we
report on an efficient route to bis(η6-pentafulvene)titanium
complexes, by reaction of pentafulvenes and titanium halides
with magnesium as reducing agent. Generally, the reductive
dimerization of pentafulvenes is known for various metals.10
This procedure has been used for the syntheses of ansa-
metallocenes of group 4 metals in a direct11 or indirect way.12
Introduction
Pentafulvenes can be bound to transition metals in several
different modes. In unusual examples, fulvenes bind through
selected double bonds of the five-membered ring as well as the
exocyclic double bond. η2 coordination to the exocyclic double
bond was demonstrated for Pd(η2-C5Me4dCH2)(PMe3)2 and
1
Rh(η2-C5H4dCPh2)(CO)2Cl2 or through one of the ring double
bonds, as in Pt(η2-C5H4dCPh2)(PPh3)2.3 An η4 mode was found
in Fe(η4-C5H4dCPh2)(CO)3, (COD)Ni(η4-C5H4dCPh2),4 and
CpCo(η4-C5H4dCPh2).5 More commonly, however, fulvene
ligands act as six-electron donors. In the case of early transition
metals, the bonding situation is best described as a π-η5:σ-η1
coordination mode. The majority of the known fulvene com-
plexes of early transition metals have been generated by thermal
transformations of methyl-substituted cyclopentadienyl com-
plexes.6 Using stronger thermal conditions, 2-fold selective C-H
bond activations of one bis(alkyl)-substituted cyclopentadienyl
ring are observed.7 Alternatively, the direct use of pentafulvenes
as starting materials becomes possible, as shown first for the
(7) (a) Beckhaus, R.; Sang, J.; Oster, J.; Wagner, T. J. Organomet. Chem.
1994, 484, 179-190. (b) Troyanov, S. I.; Mach, K.; Varga, V. Organo-
metallics 1993, 12, 3387-3389. (c) Horacek, M.; Stepnicka, P.; Gyepes,
R.; Cisarova, I.; Polasek, M.; Mach, K.; Pellny, P.-M.; Burlakov, V. V.;
Spannenberg, A.; Rosenthal, U. J. Am. Chem. Soc. 1999, 121, 10638-
10639. (d) Kupfer, V.; Thewalt, U.; Tislerova, I.; Stepnicka, P.; Gyepes,
R.; Kubista, J.; Horacek, M.; Mach, K. J. Organomet. Chem. 2001, 620,
39-50. (e) Pellny, P.-M.; Burlakov, V. V.; Baumann, W.; Spannenberg,
A.; Horacek, M.; Stepnika, P.; Mach, K.; Rosenthal, U. Organometallics
2000, 19, 2816-2819. (f) Horacek, M.; Stepnicka, P.; Kubista, J.; Fejfarova,
K.; Gyepes, R.; Mach, K. Organometallics 2003, 22, 861-869.
(8) Bandy, J. A.; Mtetwa, V. S. B.; Prout, K.; Green, J. C.; Davies, C.
E.; Green, M. L. H.; Hazel, N. J.; Izquierdo, A.; Martin-Polo, J. J. J. Chem.
Soc., Dalton Trans. 1985, 2037-2049.
* To whom correspondence should be addressed. E-mail:
ruediger.beckhaus@uni-oldenburg.de.
(1) Werner, H.; Crisp, G. T.; Jolly, P. W.; Kraus, H.-J.; Kru¨ger, C.
Organometallics 1983, 2, 1369-1377.
(9) Beckhaus, R.; Lu¨tzen, A.; Haase, D.; Saak, W.; Stroot, J.; Becke,
S.; Heinrichs, J. Angew. Chem. 2001, 113, 2112-2115; Angew. Chem.,
Int. Ed. 2001, 40, 2056-2058.
(2) Altman, J.; Wilkinson, G. J. Chem. Soc. 1964, 5654-5658.
(3) Christofides, A.; Howard, J. A. K.; Spencer, J. L.; Stone, F. G. A. J.
Organomet. Chem. 1982, 232, 279-292.
(10) Selected examples for Ca, Mg, Sn and Pb, and Sm and Yb are as
follows. Ca: (a) Sinnema, P.-J.; Ho¨hn, B.; Hubbard, R. L.; Shapiro, P. J.;
Twamley, B.; Blumenfeld, A.; Vij, A. Organometallics 2002, 21, 182-
191. Mg: (b) Collins, S.; Hong, Y.; Taylor, N. J. Organometallics 1990,
9, 2695-2703. Sn and Pb: (c) Tacke, M. Organometallics 1994, 13, 4124-
4125. Sm and Yb: (d) Recknagel, A.; Edelmann, F. T. Angew. Chem. 1991,
103, 720-721; Angew. Chem., Int. Ed. Engl. 1991, 30, 693-694.
(11) (a) Eisch, J. J.; Shi, X.; Owuor, F. A. Organometallics 1998, 17,
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1331.
(5) Wadepohl, H.; Pritzkow, H. Acta Crystallogr., Sect. C 1991, 47,
2061-2063.
(6) Some examples for M ) Ti, Zr, Hf are as follows. M ) Ti: (a) Lee,
H.; Bonanno, J. B.; Hascall, T.; Cordaro, J.; Hahan, J. M.; Parkin, G. J.
Chem. Soc., Dalton Trans. 1999, 1365-1368. (b) Bercaw, J. E.; Marvich,
R. H.; Bell, L. G.; Brintzinger, H. H. J. Am. Chem. Soc. 1972, 94, 1219-
1238. (c) McDade, C.; Green, J. C.; Bercaw, J. E. Organometallics 1982,
1, 1629-1634. (d) Luinstra, G. A.; Teuben, J. H. J. Am. Chem. Soc. 1992,
114, 3361-3367. M ) Zr: (e) Sun, Y.; Spence, R. E. v. H.; Piers, W. E.;
Parvez, M.; Yap, G. P. A. J. Am. Chem. Soc. 1997, 119, 5132-5143. (f)
Schock, L. E.; Brock, C. P.; Marks, T. J. Organometallics 1987, 6, 232-
241. M ) Hf: (g) Bulls, A. R.; Schaefer, W. P.; Serfas, M.; Bercaw, J. E.
Organometallics 1987, 6, 1219-1226.
(12) Reviews: (a) Ryan, E. J. In ComprehensiVe Organometallic
Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon
Elsevier Science: Oxford, U.K., 1995; Vol. 4, Chapter 9, pp 483-499. (b)
Janiak, C. In Metallocenes; Togni, A., Halterman, R. L., Eds.; Wiley-
VCH: Weinheim, Germany, 1998; Vol. 2, Chapter 9, pp 547-623. (c)
Halterman, R. L. In Metallocenes; Halterman, R. L., Togni, A., Eds.; Wiley-
VCH: Weinheim, Germany, 1998; Chapter 8, pp 455-544.
10.1021/om050815m CCC: $33.50 © 2006 American Chemical Society
Publication on Web 12/06/2005

340 Organometallics, Vol. 25, No. 2, 2006
Diekmann et al.
Scheme 1
Scheme 2
However, to prevent C-C coupling reactions at the exocyclic
position, bulky substituents seem to be necessary in this position.
Additionally, reactions of prochiral 1,2-benzofulvenes will be
presented. Benzofulvenes have also been characterized by an
ambivalent coordination chemistry. Comparable to the case for
fulvene complexes, coordination modes of η2 up to η6 are found,
including the possibility to coordinate through the benzene ring
instead of the five-membered ring.13
°C (8)), respectively (Scheme 2). A lower solubility and higher
sensitivity to air is found compared to the case for 3 and 4.
Again, the mass spectra (EI) show peaks of the molecular ions
at m/z 664 (7) and 545 (8).
X-ray Crystal Structures. Suitable crystals for X-ray
structure determinations of 3, 7, and 8 were obtained from
n-hexane as well as n-hexane/toluene solutions. Unfortunately,
4 forms very thin needle-shaped crystals, which only allowed
collection of low-quality X-ray data sets. However, its con-
nectivity was still confirmed, but no further detailed data will
be discussed.16 The Ortep plots of 3, 7, and 8 are given in
Figures 1-4, and selected bond distances are summarized in
Table 1. The bis(fulvene) complex 3 crystallizes in the ortho-
rhombic space group Pbca. Compound 3 exhibits a typical bent-
metallocene conformation which is approximately C2 symmetric
(Figure 2). 4 shows similar structural features and possesses,
as does 3, a noncrystallographically imposed C2 axis.16
Typical features of a fulvene ligand coordinated to early
transition metals are found for 3, 7, and 8. The molecular struc-
Results and Discussion
Upon reaction of TiCl3‚3THF with 1.5 equiv of magnesium
turnings and 2 equiv of bis-p-tolylfulvene (1) in THF as solvent
at room temperature over a period of 6 h, a dark green solution
is formed. After separation from MgCl2 the bis(fulvene)titanium
complex 3 can be isolated as a dark green solid (mp 154 °C,
75% yield) (Scheme 1). In a similar procedure, using fulvene 2
as ligand, complex 4 is obtained as a turquoise-blue solid (mp
135 °C, 70% yield). Both complexes are easily soluble in ethers
and aromatic solvents but less soluble in aliphatic hydrocarbons.
A more satisfactory solubility is obtained in hot n-hexane (65
°C). On contact with air and moisture, fast decomposition
occurs. The mass spectra (EI) show the peaks of the molecular
ions at m/z 564 (3) and 444 (4).
Instead of TiCl3‚3THF, the use of TiCl4‚2THF as starting
material is possible and similar yields are found for the
formation of 3. However, in the case of 4 only low yields are
found if TiCl4‚2THF is used as starting material. We propose
side reactions of the stronger bipolar fulvene 214 and TiCl4‚
2THF to be responsible for this drop in yield.15 Such side
reactions can be circumvented if the more weakly Lewis acidic
TiCl3 is used.
Using the related prochiral benzofulvenes ligands 5 and 6 in
reactions with TiCl3‚3THF and Mg in THF as solvent, the dark
brown bis(fulvene) complexes 7 and 8 are obtained as pure
diastereomers in 68% and 45% yield (dec pt 139 °C (7), 160
Figure 1. Molecular structure of 3 (50% probability ellipsoids).
Selected bond lengths (Å) and angles (deg): Ti1-C1 ) 2.149(3),
Ti1-C2 ) 2.248(2), Ti1-C3 ) 2.394(2), Ti1-C4 ) 2.431(3),
Ti1-C5 ) 2.299(3), Ti1-C6 ) 2.408(2), C1-C2 ) 1.438(4), C2-
C3 ) 1.422(4), C3-C4 ) 1.399(5), C4-C5 ) 1.407(4), C1-C5
) 1.448(4), C1-C6 ) 1.453(3), Ti1-C21 ) 2.148(2), Ti1-C22
) 2.274(2), Ti1-C23 ) 2.408(3), Ti1-C24 ) 2.394(3), Ti1-C25
) 2.258(3), Ti1-C26 ) 2.392(2), C21-C22 ) 1.448(3), C22-
C23 ) 1.411(3), C23-C24 ) 1.411(4), C24-C25 ) 1.412(4),
C21-C25 ) 1.448(3), C21-C26 ) 1.453(3), Ti1-Ct1 ) 1.964,
Ti1-Ct2 ) 1.953; Ct1-Ti1-Ct2 ) 145.9, C6-Ti1-C26 )
139.25(8). Ct1 ) centroid of C1-C5; Ct2 ) centroid of C21-
C25. All hydrogen atoms and one disordered tolyl ligand are omitted
for clarity.
(13) Examples of different coordination modes of (ηx-1,2-benzofulvene)M
complexes are as follows. x ) 2, M ) Mn: (a) Edelmann, F.; Jens, K.-J.;
Behrens, U. Chem. Ber. 1978, 111, 2895-2900. x ) 5, M ) Cr: (b) Strunin,
B. N.; Bakhmutov, V. I.; Vayukova, N. I.; Trembovler, V. N.; Setkina, V.
N.; Kursanov, D. N. J. Organomet. Chem. 1983, 246, 169-176. x ) 6, M
) Cr: (c) Edelmann, F.; Koch, O.; Behrens, U. J. Organomet. Chem. 1986,
311, 111-123. x ) 1, 5, M ) Fe-Fe: (d) Moriarty, R. M.; Chen, K.-N.;
Flippen, J. L. J. Am. Chem. Soc. 1973, 95, 6489-6490.
(14) Neuenschwander, M. In The Chemistry of Double-Bonded Func-
tional Groups; Patai, S., Ed.; Wiley: Chichester, U.K., 1989; Vol. 2, Chapter
16, pp 1131-1268.
(15) The formation of dark insoluble material is observed. Examples for
Lewis acid initiated polymerization of fulvenes (including TiCl4) are given
in: Rentsch, C.; Slongo, M.; Scho¨nholzer, S.; Neuenschwander, M.
Makromol. Chem. 1980, 181, 19-29.

Chiral Bis(η5:η1-pentafulVene)titanium Complexes
Organometallics, Vol. 25, No. 2, 2006 341
Figure 2. View along the C2 axis of 3 (the R isomer is shown).
Figure 4. Molecular structure of 8 (50% probability ellipsoids,
(S,pS,pR) enantiomer shown). Selected bond lengths (Å) and angles
(deg): Ti1-C1 ) 2.146(2), Ti1-C2 ) 2.233(2), Ti1-C3 )
2.257(2), Ti1-C4 ) 2.529(2), Ti1-C9 ) 2.415(2), Ti1-C10 )
2.341(2), C1-C2 ) 1.449(3), C2-C3 ) 1.400(3), C3-C4 )
1.429(3), C4-C9 ) 1.436(3), C4-C5 ) 1.420(3), C5-C6 )
1.372(3), C6-C7 ) 1.412(3), C7-C8 ) 1.374(3), C1-C9 )
1.479(3), Ti1-C20 ) 2.138(2), Ti1-C21 ) 2.259(2), Ti1-C22
) 2.411(2), Ti1-C23 ) 2.4964(18), Ti1-C28 ) 2.345(2), Ti1-
C29 ) 2.363(2), C20-C21 ) 1.440(3), C21-C22 ) 1.403(3),
C22-C23 ) 1.426(3), C23-C28 ) 1.438(3), C23-C24 )
1.429(3), C24-C25 ) 1.362(4), C25-C26 ) 1.406(4), C26-C27
) 1.379(4), C27-C28 ) 1.423(3), Ti1-Ct1 ) 1.988, Ti1-Ct2 )
1.995; Ct1-Ti1-Ct2 ) 143.2, C10-Ti1-C2 )9 120.09(8). Ct1
) centroid of C1-C4, C9; Ct2 ) centroid of C20-C23, C28.
Figure 3. Molecular structure of (S,pS,pR)-7 (50% probability
ellipsoids). Selected bond lengths (Å) and angles (deg): Ti1-C1
) 2.155(3), Ti1-C2 ) 2.225(3), Ti1-C3 ) 2.342(3), Ti1-C4 )
2.488(3), Ti1-C9 ) 2.365(3), Ti1-C10 ) 2.400(2), C1-C2 )
1.445(4), C2-C3 ) 1.407(5), C3-C4 ) 1.420(5), C4-C9 )
1.440(4), C4-C5 ) 1.414(5), C5-C6 ) 1.354(5), C6-C7 )
1.424(4), C7-C8 ) 1.362(4), C1-C9 ) 1.457(4), C1-C10 )
1.456(4), Ti1-C25 ) 2.146(3), Ti1-C26 ) 2.235(3), Ti1-C27
) 2.409(3), Ti1-C28 ) 2.497(3), Ti1-C33 ) 2.328(3), Ti1-C34
) 2.410(3), C25-C26 ) 1.449(4), C26-C27 ) 1.379(5), C27-
C28 ) 1.420(4), C28-C33 ) 1.420(4), C28-C29 ) 1.419(4),
C29-C30 ) 1.359(4), C30-C31 ) 1.397(5), C31-C32 )
1.369(4), C32-C33 ) 1.429(4), C25-C34 ) 1.425(4), Ti1-Ct1
) 1.972, Ti1-Ct2 ) 1.983; Ct1-Ti1-Ct2 ) 142.9, C10-Ti1-
C34 ) 126.64(9). Ct1 ) centroid of C1-C4, C9; Ct2 ) centroid
of C25-C28, C33.
Table 1. Comparison of Selected Bond Lengths (Å) and
Angles (deg) of 3, 7, and 8
3
7
8
Ti-Ct
1.964
1.953
1.972
1.983
1.988
1.995
Ti-Cipso
Ti-Cexo
2.149(3)
2.148(2)
2.408(2)
2.392(2)
1.453(3)
1.453(3)
145.89
34.1
2.155(3)
2.146(3)
2.400(2)
2.410(3)
1.456(4)
1.425(4)
142.94
34.6
2.146(2)
2.138(2)
2.341(2)
2.363(2)
1.447(3)
1.458(3)
143.15
35.4
Cipso-Cexo
Ct1-Ti-Ct2
θa
ture of 3 is comparable with that of the bis(6,6-diphenylfulvene)-
titanium complex prepared from bis(toluene)titanium(0).8 In
such a way the C1-C6 and C21-C26 bonds are elongated to
1.453(3) Å, in comparison to the length in the free ligand 1
(1.359(2) Å).17 The exocylic carbon atom of the fulvene ligand
is bent toward the metal center, leading to bent angles θ of
34.1 and 35.3°, respectively. The Ti-C6 (2.408(2) Å) and Ti-
C26 (2.392(2) Å) distances in 3 are found to be significantly
shorter than those in the fulvene complexes (η5-C5Me5)(η6-
C5H4dC(p-tol)2)TiCl (2.535(5) Å)17 and {(η5-C5Me5)(η6-C5H4d
C(p-tol)2)Ti}2(µ2-η1:η1-N2) (2.601(3), 2.612(3) Å).18 The Ti-
Ct distances (1.964, 1.953 Å) are found to be slightly shorter
35.3
0.282
0.267
32.6
0.309
0.346
34.4
0.316
0.375
a
∆
a The values ∆ and θ are defined as shown:
than those in typical bent titanocenes (2.062 Å19), forming an
Ct-Ti-Ct angle of 145.9°, which is in the expected range for
(16) For details please see the Supporting Information.
(17) Stroot, J.; Friedemann, M.; Lu¨tzen, A.; Saak, W.; Beckhaus, R. Z.
Anorg. Allg. Chem. 2002, 628, 797-802.
(18) Scherer, A.; Kollak, K.; Lu¨tzen, A.; Friedeman, M.; Haase, D.; Saak,
W.; Beckhaus, R. Eur. J. Inorg. Chem. 2005, 1003-1010.
(19) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1-S83.

342 Organometallics, Vol. 25, No. 2, 2006
Diekmann et al.
Figure 6. Chirality of the bis(fulvene) complexes. Ct ) centroid
of the five membered fulvene ring; Cexo ) exocyclic carbon atom
of the fulvene ligand.
Figure 5. Molecular structure of 6 (50% probability ellipsoids).
Selected bond lengths (Å): C1-C2 ) 1.479(2), C2-C3 ) 1.340(2),
C3-C4 ) 1.457(3), C4-C9 ) 1.417(2), C9-C1 ) 1.494(2), C4-
C5 ) 1.384(2), C5-C6 ) 1.379(3), C6-C7 ) 1.393(3), C7-C8
) 1.389(2), C8-C9 ) 1.393(2), C1-C10 ) 1.361(2).
low-valent Cp2-Ti fragments.20 A ring slippage ∆21 of 0.27 Å
(average) toward the Cipso atom of the five-membered ring is
found.
Figure 7. Diastereomers of the bis(benzofulvene) complexes (only
one enantiomer given for each).16
To compare the structural data of the free and coordinated
pentafulvenes, the structure of 6 was determined (Figure 5).
The structural data of 6 are in the expected range for penta-
fulvenes (1,17 2,22 518). The torsion angles C9-C1-C10-C11
(1.71°) and C2-C1-C10-C15 (1.49°) are found to be smaller
than in the p-tolyl-substituted fulvenes 1 (average 9.95°)17 and
5 (average 16.63°),18 illustrating the nearly coplanar arrangement
of the substituents at the exocyclic double bond, leading to an
approximately Cs-symmetric molecule.
The exocyclic C-C bonds in 5 (1.359(2) Å)18 and 6 (1.361(2)
Å) are elongated in the benzofulvene complexes 7 (1.456(4),
1.425(4) Å) and 8 (1.447(3), 1.458(3) Å) in a typical manner.
A slightly stronger elongation is found in the low-coordinated
benzofulvene complex (η5-C5Me5)Ti(η6-C9H6dC(p-tol)2)
(1.465(3) Å).18 Due to the increased aromatic character of the
five-membered fulvene ring, the C2-C3 bond is elongated in
the benzofulvene complexes 7 and 8. On the other hand, the
double bonds in the six-membered ring become more localized,
leading to a shortening of the bonds comparable to those
between C5-C6 and C7-C8 in 7 and 8. The other structural
parameters are in excellent agreement with those of other known
titanium pentafulvene complexes. The exocyclic carbon atoms
are bent out of the fulvene plane by 33.6° (7, average) and 34.9°
(8, average). Ring slippage values ∆ toward the Cipso atom of
0.327 Å (7, average) and 0.345 Å (8, average) are found, and
likewise Ti-Ct distances are also found to be shorter than in
bent metallocenes. In addition, the Ti-Cexo distances in 8
(2.341(2), 2.363(2) Å) are found to be shorter than in 7
(2.400(2), 2.410(3) Å), which are nearly identical with the values
in 3 (2.408(2), 2.392(2) Å).
bonding situation can be regarded as an elongated tetrahedron
whose corners can be assigned to the centroids and the exocyclic
carbon atoms of both fulvene ligands, as schematically repre-
sented in Figure 6. This geometry is best known for suitable
substituted spiranes, and the formation of similar spiro com-
pounds exhibiting bis(cyclopentadienylalkoxide)23 and bis-
(indenylphenoxide)24 ligands as well as further 2-fold-chelated
metallocene systems25 has actually been studied before. For the
stereochemical description one fulvene ligand is arbitrarily given
preference and the substituents are ranked using the Cahn-
Ingold-Prelog rules.26,27 In this case, Ct is given priority 1,
and the Ct on the other side is ranked 2. The Cexo atoms are
then ranked 3 and 4, and now the chirality can be assigned as
R or S, respectively.16
The stereochemistry of the bis(benzofulvene) compounds 7
and 8 is slightly more complicated, however. The monosubsti-
tuted benzofulvenes 5 and 6 exhibit enantiopic faces, leading
to the occurrence of two planar chiral elements per bis-
(benzofulvene) complex. Together with the chiral metal center
as in the bis(fulvene) compounds, this adds up to three
stereogenic elements; thus, there are 23 possible stereoisomers
for the bis(benzofulvene) complexes. However, the (R,pR,pS)/
(S,pS,pR) and (R,pS,pR)/(S,pR,pS) isomers are in a meso
relationship, and therefore, only three pairs of racemic dia-
23
stereomers can be formed (Figure 7).
(23) Possible stereoisomers of bis(alkoxycyclopentadienyl)zirconium
systems: Christoffers, J.; Bergman, R. G. Angew. Chem. 1995, 107, 2423-
2425; Angew. Chem., Int. Ed. Engl. 1995, 34, 2266-2267.
(24) Turner, L. E.; Thorn, M. G.; Fanwick, P. E.; Rothwell, I. P.
Organometallics 2004, 23, 1576-1593.
(25) (a) Herrmann, W. A.; Morawietz, M. J. A.; Priermeier, T. Angew.
Chem. 1994, 106, 2025-2028; Angew. Chem., Int. Ed. Engl. 1994, 33,
1946-1949. (b) du Plooy, K. E.; Moll, U.; Wocadlo, S.; Massa, W.; Okuda,
J. Organometallics 1995, 14, 3129-3131. (c) Duda, L.; Erker, G.; Fro¨hlich,
R.; Zippel, F. Eur. J. Inorg. Chem. 1998, 1153-1162. (d) Zhang, K.; Zhang,
W.; Wang, S.; Sheng, E.; Yang, G.; Xie, M.; Zhou, S.; Feng, Y.; Mao, L.;
Huang, Z. J. Chem. Soc., Dalton Trans. 2004, 1029-1037.
Chirality. The chirality of the bis(fulvene) complexes 3 and
4 arises from the fact that they bear two bidendate fulvene
ligands. Chelation via the exocyclic carbon atoms of the ligands
is possible in two stereochemical arrangements, making the
titanium complex become chiral. In a simplified approach the
(20) Beckhaus, R. Titanocenes. In Metallocenes; Halterman, R. L., Togni,
A., Eds.; VCH: Weinheim, Germany, 1998; Chapter 4, pp 153-239.
(21) O’Connor, J. M.; Casey, C. P. Chem. ReV. 1987, 87, 307-318.
(22) Garcia, J. G.; McLaughlin, M. L.; Fronczek, F. R. Acta Crystallogr.,
Sect. C 1989, 45, 1099-1100.
(26) Eliel, E. L.; Wilen, S. H.; Mander, L. N. Stereochemistry of Organic
Compounds; Wiley: New York, 1994.
(27) Nicolaou, K. C.; Boddy, C. N. C.; Siegel, J. S. Angew. Chem. 2001,
113, 723-726; Angew. Chem., Int. Ed. 2001, 40, 701-704.

Chiral Bis(η5:η1-pentafulVene)titanium Complexes
Organometallics, Vol. 25, No. 2, 2006 343
1
Table 2. Selected H (ppm; C6D6, 500 MHz, 300 K) and 13C
NMR Data (ppm; C6D6, 125 MHz, 300 K) of 117 and 2,28,18
Compared with Those of 3 and 4
1
3
2
4
Figure 8. 1H NMR spectrum of 7 in THF-d8 (275 K, 500.1 MHz).
The asterisks denote THF.
1H NMR Data
4.96
Ha
Hb
Hc
Hd
6.57
6.65
6.65 (Hb)
6.57 (Ha)
6.66
6.61
6.61 (Hb)
6.66 (Ha)
4.63
4.84
6.06
6.55
4.20
5.88
6.53
1
Table 3. Selected H (ppm; 500 MHz, 300 K) and 13C NMR
Data (ppm; 125 MHz, 300 K) of 8 and 7 Compared with
Those of 6 and 518
13C NMR Data
108.8
Ca
124.8
119.8
110.8
Cb
Cc
Cd
Cipso
Cexo
132.4
110.0
121.7
116.5
132.6
131.0
111.9
116.9
115.0
133.4
113.3
132.4 (Cb)
124.8 (Ca)
144.2
131.0 (Cb)
119.8 (Ca)
136.9
152.2
112.0
164.8
The benzofulvene complex 7 crystallizes as a conglomerate
in the monoclinic space group P21, and one of the enantiomers
was identified as (S,pS,pR)-7. The central titanium atom lies in
a highly distorted pseudotetrahedral coordination sphere and is
π-η5:σ-η1-bound to each of the benzofulvene ligands. The
isomers (S,pS,pR)-7 and (R,pR,pS)- 7 have no symmetry
elements and show C1 symmetry.
The adamantyl-substituted benzofulvene complex 8 crystal-
lizes in the monoclinic space group P21/c. The X-ray structure
determination of 8 established that, similar to 7, both benzo-
fulvene ligands are coordinated as optical antipodes and,
accordingly, 8 possesses a (S,pS,pR)/(R,pR,pS) configuration in
the solid state.
518
C6D6
7
6
8
solvent
THF-d8
C6D6
C6D6
1H NMR Data
5.17
Ha
6.75
6.94
6.84
6.73
4.81
7.13
3.07
5.37
H′a
Hb
H′b
7.28
2.94
4.19
13C NMR Data
121.9
Ca
C′a
Cb
C′b
Cc
130.7
130.7
136.0
138.2
144.2
147.3
127.0
128.5
145.4
136.6
131.3
159.9
122.5
116.6
107.3
106.2
124.0
126.6
126.5
126.6
133.4
127.1
117.3
120.4
116.4
109.4
110.6
123.3
127.9
126.6
125.6
131.7
NMR Investigations. 1H and 13C NMR spectroscopic
measurements showed that the 2-fold symmetry of 3 and 4 is
retained in solution; thus, for both fulvene ligands a single set
of signals is found. For 3 the chemical shifts of the fulvene
ring protons appear as four separated multiplets at δ 4.20 (Hb),
4.96 (Ha), 5.88 (Hc), and 6.53 ppm (Hd), all signals being shifted
upfield by nearly 2.4 ppm compared to the those in the spectrum
of the corresponding fulvene 1 (Table 2). The chemical shifts
of the fulvene ring protons of 4 at δ 4.63 (Ha), 4.84 (Hb), 6.06
(Hc), and 6.55 ppm (Hd), respectively, exhibit very similar
patterns, and an upfield shift up to 2 ppm is found. The strongest
shift differences are found for Ha and Hb, comparing free and
complexed ligands. Analogous to the 1H NMR data, the signals
of the C atoms of the fulvene ligand do also experience a
significant upfield shift upon coordination to the titanium center.
This is particularly true for the Cexo atoms, which show
differences of 51.5 (4/2) and 40.2 ppm (3/1), indicating a
remarkable electron transfer from the titanium center to the
ligand.
C′c
Cd
C′d
Cipso
C′ipso
Cexo
C′exo
125.6
114.3
114.6
each found as doublets with a coupling constant of 3JHH ) 3.4
Hz (comparable values are also found for C6D6 solutions at δ
5.27 (Ha), 7.52 (H′a), 2.97 (Hb), and 4.47 (H′b)). For 8 resonances
occur at δ 4.81 (Ha), 7.13 (H′a), 3.07 (Hb), and 5.37 (H′b) (JHH
not resolved). As in the solid-state structure, compound 7
exhibits a proton (H3 ()Hb)) lying directly above the arene ring
of the opposite benzofulvene ligand, which thus is strongly
influenced by the arene’s anisotropy cone (Figure 9). Therefore,
H3 ()Hb) is most effectively shielded, and in consequence, its
resonance shows an unusual upfield shift at 2.94 ppm. In 8, H3
()Hb) is similarly oriented and shows a comparable shift (3.07
ppm). Vice versa, the most deshielded signals at δ 7.28 (7) and
7.13 (8) ppm can be assigned to the coordinatively less affected
protons H26 (7) and H21 (8), respectively.
The lower symmetry complexes 7 and 8 exhibit the expected
1
separated set of signals for each benzofulvene group in the H
and 13C NMR spectra, diagnostic for the complexes’ C1
symmetry.16 Due to severe signal crowding in benzene-d6 the
detailed NMR studies of 7 were performed with THF-d8
solutions. The most characteristic features are again the chemical
Analysis of variable-temperature NMR data and NOE experi-
ments revealed that three of the four phenyl rings (A-C) of 7
undergo a fast rotation on the time scale of the NMR experiment
at 275 K. Thus, only averaged signals for the corresponding
1
shifts for the nuclei of the fulvene skeleton; especially, the H
signals vary over a wide range (Figure 8). For 7 they are located
at δ 5.17 (Ha), 7.28 (H′a), 2.94 (Hb), and 4.19 (H′b) (Table 3),

344 Organometallics, Vol. 25, No. 2, 2006
Diekmann et al.
1
Figure 9. Assignment and chemical H NMR shifts of selected protons in 5-8.
atoms in 7 resonate almost equally (δ 114.3/114.6 ppm) and
are at slightly higher field than the Cexo shifts of 8 (δ 117.3/
120.4 ppm). They all show considerable shift differences up to
39.5 ppm with regard to the parent fulvenes (δ 147.3 (5), 159.9
ppm (6)), indicating their increased sp3 character.
Saturation transfer phenomena showed that the benzofulvene
ligands in 7 apparently exchange their positions. Even at lower
temperatures a considerable ligand exchange still occurs. For 8
a similar fluxional behavior is not observed. However, a rotation
of the benzofulvene ligand comparable to the fulvene rotation
around the Ti-Ct axis in Cp*{η6-C5H4dC(p-tolyl)2}TiCl is not
observed.17
Figure 10. Variable-temperature 1H NMR spectra of 7 in THF-d8
(300.1 MHz). The asterisks mark the resonances of the protons
from ring D, and the circles denote the C-H resonances of ring C
(two of them are overlapped by the aromatic region).
Reactions with HCl. Due to the general nucleophilic
character of the exocyclic carbon of the pentafulvene complexes
of early transition metals, subsequent reactions with electrophiles
can be expected, as shown for monofulvene titanium deriva-
tives.9,29 For bis(diphenyl) pentafulvene titanium a reversible
coordination of carbon monoxide is described as the first
reaction of bis(fulvene)titanium complexes.8 On treatment of a
hexane solution of 3 and a toluene solution of 7 with 2 equiv
of a 1 M solution of HCl/Et2O an immediate color change from
green (3) and brown (7) to red (9) and dark red (10),
respectively, occurs (Scheme 3). Whereas the crystalline
ortho and meta nuclei are observed. However, the ring rotation
of phenyl group D is already so restricted that it can be
spectroscopically monitored and distinct signals are found (1H,
δ 4.36, 6.20, 6.96-7.02, and 7.69 ppm; 13C, δ 134.3, 133.0,
128.6, 141.7, 128.5, and 129.1 ppm). As shown in Figure 10,
these resonances are found to be broadened at 303 K but become
sharpened when the temperature is lowered. Additionally, the
restricted motion of a second ring (C) can be observed at 213
K.
Compounds 7 and 8 also feature the typical 13C resonances
of the nonannelated fulvene frameworks, with slight deviations
of the two chelating ligands. Namely, the resonances of the
tertiary carbons Ca/C′a and Cb/C′b occur at δ 121.9/116.4 and
109.4/110.6 ppm (7) and at δ 122.5/116.6 and 107.3/106.2 ppm
(8), respectively. As observed for 3 and 4, they show similar
upfield shifts in comparison with the signals for the free ligands.
The Cipso/C′ipso shifts are found in a comparable range (δ 131.7/
125.6 (7) and δ 133.4/127.1 ppm (8)). The exocyclic carbon
(28) Olah, G. A.; Prakash, G. K. S.; Liang, G. J. Org. Chem. 1977, 42,
661-666.
(29) Examples of different electrophiles used are as follows. Ketones:
(a) Stroot, J.; Beckhaus, R.; Saak, W.; Haase, D.; Lu¨tzen, A. Eur. J. Inorg.
Chem. 2002, 1729-1737. Nitriles: (b) Stroot, J.; Saak, W.; Haase, D.;
Beckhaus, R. Z. Anorg. Allg. Chem. 2002, 628, 755-761. H2O: (c) Stroot,
J.; Haase, D.; Saak, W.; Beckhaus, R. Z. Kristallogr.-New Cryst. Struct.
2002, 217, 47-48. HCl: (d) Stroot, J.; Haase, D.; Saak, W.; Beckhaus, R.
Z. Kristallogr.-New Cryst. Struct. 2002, 217, 49-50.

Chiral Bis(η5:η1-pentafulVene)titanium Complexes
Organometallics, Vol. 25, No. 2, 2006 345
Scheme 3
substituted titanocene dichloride 9 is precipitated directly from
the reaction solution, the bis(indenyl) derivative 10 can be
isolated after adding n-hexane.
1
The H NMR spectrum of 9 shows, as expected, one set of
signals which can be attributed to the exocyclic CH group (δ
5.98 ppm) and the typical cyclopentadienyl protons (δ 6.01,
5.65 ppm). In the case of 10 the exocyclic CH proton is located
at δ 6.55 ppm, whereas the protons of the five-membered ring
are found at δ 6.23 and 4.34 ppm, respectively. As for 9, both
η5 ligands are also found to be equivalent in 10. A consistent
behavior is found in the 13C NMR spectra of 9 and 10.
The molecular structures of 9 and 10 are given in Figures 11
and 12. The substituted titanocene halide 9 crystallizes in the
triclinic space group P1h with 0.5 equiv of n-hexane per
molecule, whereas 10 crystallizes in the monoclinic space group
Figure 12. Molecular structure of 10 (50% probability ellipsoids).
Selected bond lengths (Å) and angles (deg): Ti1-C1 ) 2.493(2),
Ti1-C2 ) 2.355(2), Ti1-C3 ) 2.308(2), Ti1-C4 ) 2.552(2),
Ti1-C9 ) 2.626(2), Ti1-C25 ) 2.450(2), Ti1-C26 ) 2.373(2),
Ti1-C28 ) 2.494(2), Ti1-C33 ) 2.521(2), C1-C10 ) 1.512(3),
C25-C34 ) 1.508(3), Ti1-Cl1 ) 2.3026(6), Ti1-Cl2 ) 2.3192(6),
Cl1-Ti-Cl2 ) 97.61(3), Ct1-Ti-Ct2 ) 131.69(2). Ct1 )
centroid of C1-C4, C9; Ct2 ) centroid of C25-C28, C33.
P21/n with 1 equiv of toluene per molecule. Both substituted
indenyl ligands in 10 are arranged as optical antipodes, leading
to a meso-like form. The terminal Ti-Cl bond lengths (2.3506(5),
2.3397(5) Å, 9; 2.3026(6), 2.3192(6) Å, 10) are comparable to
those of other titanocene chlorides.30 Also, the typical pseudo-
tetrahedral coordination features are found, when the Ct-Ti-
Ct (132.6, 131.69(2)°) and Cl-Ti-Cl angles (95.32, 97.61(3)°)
of 9 and 10 are compared with those of other titanocene
derivatives.31
Using the classification of Cp2MX2 conformations,32 the
bis(fulvene) complexes 3 and 7 can be attributed to class I
compounds, where the five-membered rings of the fulvene
ligands are essentially staggered and one carbon atom of each
ring lies over the Cexo-Ti-Cexo fragment. On the other hand,
the bis(indenyl) complex 10 can be attributed to class II
compounds (Cp rings staggered, three carbons over MX2).
Additionally, the coordination mode of indenyl ligands was
classified using different parameters to explain distortions in
the metal-indenyl bond.33 A detailed discussion of comparable
parameters has been given for indenylthorium complexes,34
which seems to be useful to apply to the titanium complexes
given here. The slip distortion ∆M-Ca of 0.121 Å (∆M-Ca
)
0.5[M-Cc + M-Cd] - 0.5[M-Cipso + M-Cb])34 and the
Figure 11. Molecular structure of 9 (50% probability ellipsoids).
Selected bond lengths (Å) and angles (deg): Ti1-C1 ) 2.4475(15),
Ti1-C2 ) 2.4149(15), Ti1-C3 ) 2.3532(16), Ti1-C4 )
2.3416(15), Ti1-C5 ) 2.3977(15), Ti1-C21 ) 2.4117(16), Ti1-
C22 ) 2.4279(16), Ti1-C23 ) 2.4152(16), Ti1-C24 ) 2.3386(17),
Ti1-C25 ) 2.3632(17), Ti1-Cl1 ) 2.3506(5), Ti1-Cl2 )
2.3397(5), C1-C6 ) 1.507(2), C21-C26 ) 1.510(2), Ti1-Ct1
) 2.070, Ti1-Ct2 ) 2.070; Ct1-Ti1-Ct2 ) 132.6, Cl1-Ti1-
Cl2 ) 95.32. Ct1 ) centroid of C1-C5; Ct2 ) centroid of C21-
C25.
(30) Ti-Cl ) 2.352(1), 2.346(1) Å in Cp*2TiCl2: (a) McKenzie, T. C.;
Sanner, R. D.; Bercaw, J. E. J. Organomet. Chem. 1975, 102, 457-466.
Ti-Cl ) 2.364(3) Å in Cp2TiCl2: (b) Clearfield, A.; Warner, D. K.;
Saldarriaga-Molina, C. H.; Ropal, R.; Bernal, I. Can. J. Chem. 1975, 53,
1622-1629.
(31) Cozak, D.; Melnik, M. Coord. Chem. ReV. 1986, 14, 53-99.
(32) Zachmanoglou, C. E.; Docrat, A.; Bridgewater, B. M.; Parkin, G.;
Brandow, C. G.; Bercaw, J. E.; Jardine, C. N.; Lyall, M.; Green, J. C.;
Keister, J. B. J. Am. Chem. Soc. 2002, 124, 9525-9546.

346 Organometallics, Vol. 25, No. 2, 2006
Diekmann et al.
THF was added, and the reaction mixture was stirred at room
temperature for 6 h. The solvent was removed in vacuo, and the
resulting residue was extracted with 75 mL of hot n-hexane (65
°C). Filtration and solvent removal yielded 570 mg (75%) of 3 as
a green solid. X-ray-quality crystals were obtained upon slow
cooling of a saturated hot n-hexane/toluene (50/50) solution of 3
to room temperature. Mp: 154 °C. IR (KBr): V˜ 3016 (m), 2916
(m), 2861 (w), 1504 (s), 1437 (m), 1186 (w), 1110 (m), 1019 (m),
807 (s), 760 (m), 573 (s) cm-1. MS (70 eV): m/z (relative intensity)
564 (5) [M]+, 258 (100) [(p-tolyl2)fv]+. Anal. Calcd for C40H36Ti:
planar indenyl ring systems of 10 are consistent with a
η5-coordinated indenyl ligand. For a perfect η5 coordination,
the “slip parameter” ∆M-C ) 0, while for η3-bonded complexes
∆
ranges from 0.69 to 0.79 Å.35 The conformational
M-C
preference of the substituted indenyl ligand in 10 can be
described by the dihedral angle (C2-Ct-Ct′-C26) of 104.9°.
This conformation allows sufficient distances between the
sterically demanding substituents on adjacent indenyl rings.
Similar values are found in the case of bulky substituted bis-
(indenyl)zirconium halides.36
1
C, 85.09; H, 6.41. Found: C, 84.79; H, 6.46. H NMR (benzene-
d6, 300 K): δ 2.09 (s, 6H, CH3), 2.09 (s, 6H, CH3), 4.20 (m, 2H,
Hb), 4.96 (m, 2H, Ha), 5.88 (m, 2H, Hc), 6.53 (m, 2H, Hd), 6.53
(m, 4 H, tolyl CH), 6.62 (m, 4 H, tolyl CH), 6.84 (m, 4 H, tolyl
CH), 7.31 (m, 4 H, tolyl CH). 13C NMR (C6D6, 300 K): δ 20.9,
21.0 (CH3), 108.8 (Ca), 110.0 (Cb), 112.0 (Cexo), 116.5 (Cd), 121.7
(Cc), 127.5, 128.5, 128.8, 129.8 (tolyl CH), 132.6 (Cipso), 133.9,
134.9, 140.3, 143.0 (tolyl C).
Conclusions
An efficient procedure for the synthesis of bis(fulvene)-
titanium complexes based on the reaction of TiCl3‚3THF, with
magnesium as reducing agent and exocyclic bulky substituted
pentafulvenes could be established. In comparison with the
known pathway using bis(toluene)titanium(0) this reductive
approach employs common starting materials and makes this
protocol a very attractive way for the preparation of chiral bis-
(fulvene)titanium complexes. Using prochiral benzofulvene
ligands, this approach also offers the possibility to prepare group
4 metal complexes in a diastereoselective manner. Due to the
nucleophilic character of the exocyclic carbon of the bis-
(pentafulvene) complexes subsequent products can be expected
in reactions with electrophiles, as shown for the formation of
the corresponding titanocene chlorides.
Compound 4. A 0.535 g (2.698 mmol) portion of 2, 0.5 g of
TiCl3‚3THF (1.349 mmol), and 0.049 g of magnesium turnings
(2.024 mmol) were placed in a Schlenk tube. A 30 mL amount of
THF was added, and the reaction mixture was stirred at room
temperature for 6 h. The solvent was removed in vacuo, and the
resulting residue was extracted with 75 mL of hot n-hexane (65
°C). Filtration and solvent removal yielded 417 mg (70%) of 4 as
a turquoise-blue solid. Mp: 135 °C. IR (KBr): V˜ 2897 (s), 2842
(m), 1441 (m), 1262 (m), 1096 (s), 1044 (m), 943 (w), 799 (m),
779 (s), 690 (m), 582 (w) cm-1. MS (70 eV): m/z (relative intensity)
444 (25) [M]+, 198 (100) [adamantylfv]+. Anal. Calcd for
C30H36Ti: C, 81.07; H, 8.16. Found: C, 80.93; H, 8.32. 1H NMR
(benzene-d6, 300 K): δ 0.57-2.52 (m, 28H, adamantyl CH/CH2),
4.63 (m, 2H, Ha), 4.84 (m, 2H, Hb), 6.06 (m, 2H, Hc), 6.55 (m, 2H,
Hd). 13C NMR (benzene-d6, 300 K): δ 28.42, 30.28, 32.00, 33.18,
36.98, 37.15, 38.51, 43.60, 43.89 (adamantyl CH/CH2), 110.8 (Ca),
111.9 (Cb), 113.3 (Cexo), 115.0 (Cd), 116.9 (Cb), 133.4 (Cipso).
Experimental Section
General Considerations. Unless otherwise noted, all reactions
were carried out under an inert atmosphere of argon or nitrogen
using standard glovebox and Schlenk techniques. Solvents were
dried according to standard procedures. H and 13C NMR spectra
1
were recorded on a Bruker AVANCE 500 spectrometer (1H, 500.1
MHz; 13C 125.8 MHz). Variable-temperature 1H NMR experiments
were conducted on a Bruker Avance 300.1 MHz spectrometer. The
1H NMR chemical shifts were referenced to residual protons of
the solvent. The 13C NMR spectra were referenced to benzene-d6
or THF-d8, respectively (signal assignment based upon NOE
measurements). Electron impact (EI) mass spectra were taken on a
Finnigan-MAT 95 spectrometer. IR spectra were recorded on a Bio-
Rad FTS-7 spectrometer using KBr pellets. Elemental analyses were
carried out by the Analytischen Laboratorien in Lindlar (Lindlar,
Germany). TiCl3‚3THF was prepared according to the literature
method.37 The fulvenes were prepared according to literature
procedures (1,38 2,39 518).
Compound 6. A 9.5 mL (0.082 mol) portion of freshly distilled
indene was dissolved in 150 mL of THF, and 51.3 mL of n-BuLi
(1.6 M solution in n-hexane, 0.082 mol) was added dropwise at 0
°C. Over 0.5 h the reaction mixture was stirred at 0 °C, cooled to
-78 °C, and 12.32 g (0.082 mol) of 2-adamantanone, dissolved in
120 mL of THF, was added. After the mixture was stirred for 8
days at room temperature, the resulting suspension was treated with
water, followed by extraction with ether (3 × 150 mL). The
combined organic layers were washed neutral with H2O and dried
over Na2SO4, and the solvents were removed under reduced
pressure. The residue was dissolved in 200 mL of n-hexane, and
crude 6 was precipitated by rapidly cooling with liquid nitrogen
for a few seconds. Pure 6 was obtained after chromatography of
the crude material on silica gel (eluent n-hexane) as a pale yellow
microcrystalline solid (yield 9.99 g (49%)). Mp: 121 °C. IR
(KBr): V˜ 3096 (w), 3059 (w), 3031 (w), 2962 (w), 2912 (s), 2847
(s), 1620 (s), 1450 (s), 1344 (m), 1182 (m), 1085 (m), 1021 (m),
Compound 3. A 0.697 g (2.698 mmol) portion of 1, 0.5 g of
TiCl3‚3THF (1.349 mmol), and 0.049 g of magnesium turnings
(2.024 mmol) were placed in a Schlenk tube. A 30 mL amount of
(33) (a) Westcott, S. A.; Kakkar, A. K.; Stringer, G.; Taylor, N.; J. M.
T. B. J. Organomet. Chem. 1990, 394, 777-794. (b) Cadierno, V.; Diez,
J.; Pilar Gamasa, M.; Gimeno, J.; Lastra, E. Coord. Chem. ReV. 1999, 193-
195, 147-205. (c) Faller, J. W.; Crabtree, R. H.; Habib, A. Organometallics
1985, 4, 929-935. (d) Grimmond, B. J.; Corey, J. Y.; Rath, N. P.
Organometallics 1999, 18, 404-412.
1
951 (m), 896 (m), 744 (s), 725 (s) cm-1. H NMR (benzene-d6,
300 K): δ 1.71-1.82 (m, 12H, adamantyl CH/CH2), 3.15 (m, 1H,
adamantyl CH), 3.89 (m, 1H, adamantyl CH), 6.73 (m, 3JH,H ) 5.5
Hz, 1H, Hb), 6.84 (m, 3JH,H ) 5.5 Hz, 1H, Ha), 7.12 (m, 2H, benzo
CH), 7.16 (m, 1H, benzo CH), 7.31 (m, 1H, benzo CH), 7.81 (m,
1H, benzo CH). 13C NMR (benzene-d6, 300 K): δ 28.3, 35.1, 37.0,
37.4, 39.4, 40.2 (adamantyl CH/CH2), 121.4, 124.0, 125.0, 126.2
(benzo CH), 127.0 (Ca), 128.5 (Cb), 131.3 (Cipso), 136.6 (Cd), 145.5
(Cc), 159.9 (Cexo).
(34) Trnka, T. M.; Bonanno, J. B.; Bridgewater, B. M.; Parkin, G.
Organometallics 2001, 20, 3255-3264.
(35) Calhorda, M. J.; V. L. F. Coord. Chem. ReV. 1999, 186, 37-51.
(36) Bradley, C. A.; Flores-Torres, S.; Lobkovsky, E.; Abrun˜a, H. D.;
Chirik, P. J. Organometallics 2004, 23, 5332-5346.
(37) Herrmann, W. A.; Salzer, A. Synthetic Methods of Organometallic
and Inorganic Chemistry. In Herrmann/Brauer; Herrmann, W. A., Ed.;
Thieme: Stuttgart, Germany, 1996; Vol. 1.
Compound 7. A 0.832 g (2.698 mmol) portion of 5, 0.5 g of
TiCl3‚3THF (1.349 mmol), and 0.049 g of magnesium (2.024 mmol)
were placed in a Schlenk tube. A 30 mL amount of THF was added,
and the reaction mixture was stirred at room temperature for 8 h.
The solvent was removed in vacuo, and the resulting residue was
extracted with 60 mL of toluene. After filtration and removal of
(38) Jeffery, J.; Probitts, E. J.; Mawby, R. J. J. Chem. Soc., Dalton Trans.
1984, 2423-2427.
(39) (a) Abrams, M. B.; Yoder, J. C.; Loeber, C.; Day, M. W.; Bercaw,
J. E. Organometallics 1999, 18, 1389-1401. (b) Miller, S. A.; Bercaw, J.
E. Organometallics 2002, 21, 934-945.

Chiral Bis(η5:η1-pentafulVene)titanium Complexes
Organometallics, Vol. 25, No. 2, 2006 347
Table 4. Crystal Structure Data for Compounds 3 and 6-10
3
6
7
8
9
10
empirical formula
fw
C40H36Ti
564.59
C19H20
248.35
C48H40Ti
664.70
C38H40Ti
544.60
C43H45Cl2Ti
680.59
C55H50Cl2Ti
829.75
color habit
cryst dimens, mm
cryst syst
space group
a, Å
green needles
pale yellow plates
dark brown plates
dark brown prisms red needles
red needles
1.00 × 0.36 × 0.11 0.45 × 0.22 × 0.03 0.40 × 0.25 × 0.25 0.40 × 0.13 × 0.09 1.10 × 0.37 × 0.21 0.83 × 0.15 × 0.09
orthorhombic
Pbca
16.7551(7)
21.3806(5)
16.9183(4)
90
90
90
6060.7(3)
8
1.238
monoclinic
C2/c
18.9376(13)
6.8725(3)
21.8990(16)
90
103.008(9)
90
2777.0(3)
8
monoclinic
P21
12.1107(7)
11.2973(6)
14.1304(9)
90
109.870(7)
90
1818.20(18)
2
monoclinic
P21/c
triclinic
P1h
monoclinic
P21/n
8.1551(3)
15.8776(7)
34.2942(14)
90
93.593(5)
90
4431.8(3)
4
9.9273(3)
12.9692(5)
21.7517(7)
90
93.293(3)
90
10.8634(5)
11.7578(5)
16.4825(9)
71.487(5)
81.618(6)
63.231(5)
1782.40(15)
2
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
2795.89(16)
4
Z
D
calcd, g cm-3
1.188
0.067
193(2)
1.214
0.268
193(2)
1.294
1.268
1.244
0.350
153(2)
µ, mm-1
0.309
193(2)
0.332
0.419
T, K
193(2)
193(2)
θ range, deg
no. of rflns collected
no. of indep rflns
2.25-26.00
2.21-26.04
2.54-25.96
2.45-26.00
2.20-25.91
2.20-26.02
50 825
11 875
19 323
23 431
21 874
36 443
5683 (R(int) )
0.0645)
2618 (R(int) )
0.0765)
6821 (R(int) )
0.0767)
5159 (R(int) )
0.0773)
6474 (R(int) )
0.0423)
8209 (R(int) )
0.0669)
no. of rflns with I > 2σ(I) 3776
1462
none
0.9980 and
0.9707
5215
3186
none
0.9707 and
0.8786
4953
none
0.9171 and
0.6554
5832
none
0.9692 and
0.7598
abs cor
numerical
numerical
0.9360 and
0.9003
max, min transmissn
0.9668 and
0.7474
final R indices (I > 2σ(I)) R1 ) 0.0454,
R1 ) 0.0383,
wR2 ) 0.0762
R1 ) 0.0842,
wR2 ) 0.0870
R1 ) 0.0416,
wR2 ) 0.0867
R1 ) 0.0591,
wR2 ) 0.0917
-0.02(2)
R1 ) 0.0359,
wR2 ) 0.0633
R1 ) 0.0741,
wR2 ) 0.0706
R1 ) 0.0285,
wR2 ) 0.0691
R1 ) 0.0427,
wR2 ) 0.0728
R1 ) 0.0412,
wR2 ) 0.0891
R1 ) 0.0672,
wR2 ) 0.0973
wR2 ) 0.1176
R1 ) 0.0724,
wR2 ) 0.1282
R indices (all data)
absolute struct param
the solvent crude 7 was washed with a minimum amount of
n-hexane, leading to 610 mg (68%) of pure 7 as a dark brown solid.
Single crystals suitable for X-ray diffraction were obtained upon
recrystallization from n-hexane at room temperature. Mp: 139 °C
dec. IR (KBr): V˜ 3011 (m), 2909 (m), 2857 (w), 1603 (w), 1503
(s), 1422 (m), 793 (s), 766 (s), 735 (s), 567 (s) cm-1. MS (70 eV):
m/z (relative intensity) 664 (10) [M]+, 308 (100) [(p-tolyl)2benzofv]+.
Anal. Calcd for C48H40Ti: C, 86.73; H, 6.07. Found: C, 85.99; H,
6.72. 1H NMR (THF-d8, 275 K): δ 2.20 (s, 3H, CH3), 2.21 (s, 3H,
776 (s), 740 (m) cm-1. MS (70 eV): m/z (relative intensity) 545
(10) [M]+, 248 (100) [adamantylbenzofv]+. Anal. Calcd for
C38H40Ti: C, 83.81; H, 7.40. Found: C, 83.41; H, 7.59. 1H NMR
(benzene-d6, 300 K): δ -0.15 to 2.79 (m, 28H, adamantyl CH/
CH2), 3.07 (m, 1H, Hb), 4.81 (m, 1H, Ha), 5.37 (m, 1H, H′b), 7.13
(m, 1H, H′a), 6.48-7.92 (m, 8H, benzo H). 13C NMR (benzene-d6,
300 K): 27.8, 28.1, 30.0, 30.2, 32.3, 33.2, 34.3, 34.8, 35.6, 36.2,
36.8, 37.7, 38.4, 38.5, 43.8, 44.2, 44.6, 45.2 (adamantyl CH/CH2),
106.2 (C′b), 107.3 (Cb), 116.6 (C′a), 117.3 (Cexo), 120.4 (C′exo), 121.2
(benzo CH), 122.5, 123.8 (Ca), 124.0 (Cc), 125.8 (benzo CH), 126.5
(Cd, C′c, or C′d (assignment could be interchanged)), 126.6 (Cd,
C′c, or C′d (assignment could be interchanged)), 127.1 (C′ipso), 124.6,
124.6, 127.1, 130.8 (benzo CH), 133.4 (Cipso) 133.7 (benzo CH).
Compound 9. A 0.400 g (0.708 mmol) portion of 3 was
dissolved in 40 mL of n-hexane, and while this mixture was stirred,
1.42 mL of a 1 M HCl/diethyl ether solution (1.416 mmol) was
added via syringe at ambient temperature. Immediately a color
change from green to red occurred and after a few minutes 9 started
to precipitate as red needle-shaped crystals. After 6 h 9 (0.110 g,
24%) was filtered off, rinsed with a minimum amount of n-hexane,
and dried in vacuo. A second crop of amorphous 9 (0.090 g, 20%)
was obtained after concentrating the mother liquor to 10 mL and
cooling to -20 °C for 12 h. X-ray-quality crystals were obtained
from a saturated n-hexane solution of 9. Mp: 123-125 °C. IR
(KBr): V˜ 3021 (w), 2920 (m), 2854 (w), 1510 (s), 821 (s), 762 (s)
cm-1. MS (70 eV): m/z (relative intensity) 601 (40) [M - HCl]+,
656 (5) [M - 2 HCl]+, 377 (100) [M - C20H19]+. Anal. Calcd for
C40H38Cl2Ti: C, 75.45; H, 6.01. Found: C, 75.65; H, 6.78. 1H NMR
(C6D6, 300 K): δ 2.07 (s, 12H, CH3), 5.65 (m, 4H, C5H4), 5.98 (s,
2H, CexoH), 6.01 (m, 4H, C5H4), 6.91 (m, 8H, tolyl CH), 7.09 (m,
8H, tolyl CH). 13C NMR (benzene-d6, 300 K): δ 20.9 (CH3), 52.0
(Cexo), 118.6, 120.9 (C5H4), 129.3, 129.5 (tolyl CH), 136.3 (tolyl
C), 140.3 (Cipso), 141.3 (tolyl C).
3
CH3), 2.18 (s, 3H, CH3), 2.29 (s, 3H, CH3), 2.94 (d, JH,H ) 3.4
Hz, 1H, Hb), 4.19 (d, 3JH,H ) 3.4 Hz, 1H, H′b), 4.36 (m, 1 H, benzo
3
CH), 5.17 (d, JH,H ) 3.4 Hz, 1H, Ha), 6.20 (m, 1 H, benzo CH),
6.26 (d, 3JH,H ) 8.7 Hz, 1H, benzo CH), 6.37 (dd, 3JH,H ) 8.7 and
6.7 Hz, 1H, benzo CH), 6.65 (d, 3JH,H ) 8.7 Hz, benzo CH), 6.72
3
(d, JH,H ) 8.7 Hz, 1H, benzo CH), 6.81 (m, 4H, tolyl CH), 6.87
3
(m, 7H, aryl CH), 6.96-7.02 (m, 2H, aryl CH), 7.11 (d, JH,H
)
3
8.0 Hz, 1H, benzo CH), 7.28 (d, JH,H ) 3.4 Hz, 1H, H′a), 7.32
(dd, JH,H ) 8.0 and 7.3 Hz, benzo CH), 7.69 (m, 1H, tolyl CH).
3
13C NMR (THF-d8, 275 K): δ 20.0, 20.1, 20.2, 20.2 (CH3), 109.4
(Cb), 110.6 (C′b), 114.3 (Cexo), 114.6 (C′exo), 116.4 (C′a), 120.7
(benzo CH), 121.9 (Ca), 123.0 (benzo CH), 123.3 (Cc), 124.2 (benzo
CH), 125.6 (C′ipso), 125.6 (C′d), 125.7 (benzo CH), 126.6 (Cd),
126.6, 127.0 (benzo CH), 127.9 (C′c and 7 tolyl CH), 128.3, 128.5,
128.6, 128.9, 128.9, 128.9, 128.9, 129.1 (tolyl CH), 130.6 (benzo
CH), 131.7 (Cipso), 133.0 (tolyl CH), 133.1, (benzo CH), 133.1 (tolyl
C), 133.6, 134.3, 134.6, 140.4, 141.7, 143.2, 143.8 (tolyl C).
Compound 8. A 0.670 g (2.698 mmol) portion of 6, 0.5 g of
TiCl3‚3THF (1.349 mmol), and 0.049 g of magnesium (2.024 mmol)
were placed in a Schlenk tube. A 30 mL amount of THF was added,
and the reaction mixture was stirred at room temperature for 8 h.
The solvent was removed in vacuo, and the resulting residue was
extracted with 60 mL of toluene. After filtration and removal of
the solvent crude 8 was washed with a minimum amount of
n-hexane, leading to 330 mg (45%) of pure 8 as a dark brown solid.
Single crystals suitable for X-ray diffraction were obtained upon
recrystallization from n-hexane (-20 °C). Mp: 160 °C dec. IR
(KBr): V˜ 3079 (w), 3030 (w), 2898 (s), 2842 (m), 1442 (s), 1416
(m), 1338 (m), 1213 (m), 1096 (m), 1045 (m), 952 (m), 839 (m),
Compound 10. To a solution of 0.150 g of 7 (0.226 mmol) in
15 mL of toluene was added 0.45 mL of a 1 M HCl/diethyl ether
solution (0.451 mmol) at room temperature. After it was stirred
for 0.5 h, the reaction mixture was concentrated to 8 mL and
covered with a layer of n-hexane. After 3 days 10 could be isolated

348 Organometallics, Vol. 25, No. 2, 2006
Diekmann et al.
as dark red needle-shaped crystals (0.085 g, 51%), which were
suitable for X-ray diffraction. Mp: 147-149 °C dec. IR (KBr): V˜
3023 (w), 2915 (m), 2857 (w), 1509 (s), 1435 (w), 1261 (w), 1211
(m), 1188 (w), 1110 (m), 1201 (m), 822 (m), 800 (s), 786 (m), 765
(m), 733 (m), 574 (m), 488 (m) cm-1. MS (70 eV): m/z (relative
intensity) 700 (4) [M - HCl]+, 392 (10) [M - HCl - (p-
tolyl)2benzofv]+, 309 (100) [(p-tolyl)2benzofv + H]+, 195 (65) [(p-
tolyl)2CH]+. Anal. Calcd for C48H42Cl2Ti: C, 78,16; H, 5.74.
techniques against F2 with the SHELXL-97 program system.40
Crystallographic details are given in Table 4.
Acknowledgment. This work was supported by the Bayer
AG Leverkusen (G.B.) and by the Fonds der Chemischen
Industrie.
Supporting Information Available: Figures and tables giving
stereochemical assignments and detailed NMR data and CIF files
giving crystallographic data for 3 and 6-10. This material is
available free of charge via the Internet at http://pubs.acs.org.
Additional crystallographic data for the structures 3 and 6-10 have
been deposited with the Cambridge Data Centre as Supplementary
Publication Nos. CCDC 284301 (3), CCDC 284297 (6), CCDC
284298 (7), CCDC 284299 (8), CCDC 284300 (9), and CCDC
284296 (10). Copies of the data can be obtained free of charge on
application to the CCDC, 12 Union Road, Cambridge CB21EZ,
U.K. (fax, (+44) 1223-336-033; e-mail, deposit@ccdc.cam.ac.uk).
1
Found: C, 77.99; H, 5.66. H NMR (benzene-d6, 300 K): δ 1.97
(s, 6H, CH3), 2.08 (s, 6H, CH3), 4.34 (m, 2H, Ha or Hb), 6.23 (m,
2H, Ha or Hb), 6.55 (s, 2H, CexoH), 6.76 (m, 6H, aryl CH), 6.82
(m, 4H, aryl CH), 6.98 (m, 8H, aryl CH), 7.40 (m, 4H, aryl CH),
7.48 (m, 2H, aryl CH). 13C NMR (benzene-d6, 300 K): δ 20.8
(CH3), 21.0 (CH3), 50.9 (Cexo), 106.4 (Ca or Cb), 122.1 (Ca or Cb),
126.5 (aryl CH), 126.6 (aryl CH), 128.9 (aryl CH), 129.3 (aryl CH),
129.4 (aryl CH), 130.4 (aryl CH), 135.1, 135.8, 136.4, 139.4, 141.6,
(all quat C).
X-ray Diffraction. Single-crystal experiments were carried out
on a Stoe IPDS diffractometer with graphite -monochromated Mo
KR radiation (λ ) 0.710 73 Å). The structures were solved by direct
phase determination and refined by full-matrix least-squares
OM050815M
(40) Sheldrick, G. M. SHELXS97, Program for Structure Solutions;
University of Go¨ttingen, Go¨ttingen, Germany, 1997.