Synthesis and structure of titanocene complexes with η2-coordinated internal ferrocenylacetylenes

Article abstract of DOI:10.1021/om980832u

The reduction of (η⁵-C₅H_5-nMe_n) ₂TiCl₂ (n = 0, 4, and 5) complexes by magnesium metal in tetrahydrofuran and in the presence of [(trimethylsilyl)ethynyl]ferrocene (2) or [(phenyl)-ethynyl]ferrocene (3) affords the (η⁵-C₅H_5-nMe_n) ₂Ti(η²-FcC≡CR) complexes [Fc = (η⁵-C₅H₅)-Fe(η⁵-C ₅H₄), R = SiMe₃ (4-6) and Ph (7-9)]. Crystal structures of 5 and 9 show a titanacyclopropene-like mode of coordination of the acetylenes 2 and 3. Bonding of the acetylenes to the titanocene unit results in a remarkable downfield shift of ¹³C NMR resonances of the acetylenic carbon atoms and in a large red shift of the v(C≡C) wavenumbers. Testing the complexes 6 and 9 toward head-to-tail dimerization of HC≡CSiMe₃ showed that compound 9 induces dimerization to give exclusively 2,4-bis(trimethylsilyl)-but-1-en-3-yne (10), whereas complex 6 is inactive.

Full text of DOI:10.1021/om980832u

Organometallics 1999, 18, 627-633
627
Syn th esis a n d Str u ctu r e of Tita n ocen e Com p lexes w ith
η2-Coor d in a ted In ter n a l F er r ocen yla cetylen es
Petr Sˇteˇpnicˇka, Ro´bert Gyepes, and Ivana C´ısarˇova´
Department of Inorganic Chemistry, Charles University, Hlavova 2030,
128 40 Prague 2, Czech Republic
Vojtech Varga,‡ Miroslav Pola´sˇek, Michal Hora´cˇek, and Karel Mach*
J . Heyrovsky´ Institute of Physical Chemistry, Academy of Sciences of the Czech Republic,
Dolejsˇkova 3, 182 23 Prague 8, Czech Republic
Received October 5, 1998
The reduction of (η5-C5H5-nMen)2TiCl2 (n ) 0, 4, and 5) complexes by magnesium metal in
tetrahydrofuran and in the presence of [(trimethylsilyl)ethynyl]ferrocene (2) or [(phenyl)-
ethynyl]ferrocene (3) affords the (η5-C5H5-nMen)2Ti(η2-FcCtCR) complexes [Fc ) (η5-C5H5)-
Fe(η5-C5H4), R ) SiMe3 (4-6) and Ph (7-9)]. Crystal structures of 5 and 9 show a
titanacyclopropene-like mode of coordination of the acetylenes 2 and 3. Bonding of the
acetylenes to the titanocene unit results in a remarkable downfield shift of 13C NMR
resonances of the acetylenic carbon atoms and in a large red shift of the ν(CtC)
wavenumbers. Testing the complexes 6 and 9 toward head-to-tail dimerization of HCtCSiMe3
showed that compound 9 induces dimerization to give exclusively 2,4-bis(trimethylsilyl)-
but-1-en-3-yne (10), whereas complex 6 is inactive.
In tr od u ction
tanocene bis(ferrocenylacetylide) [(η5-C5H4(SiMe3)]2Ti-
(η1-CtCFc)2 and its tweezer complex with an embedded
Ni(CO) group,4 and by titanocene bis(acetylide) com-
plexes (η5-C5H4R)2Ti[η1-(CtC)nFc]2 (n ) 1, 2).5 Recent-
ly, a directly ring-to-ring linked pseudotitanocene-
ferrocene complex, (η5-1,2,5,6-tetrakis(trimethylsilyl)(4-
ferrocenyl)cyclohexa-1,4-dienyl)(η5-cyclopentadienyl)titanium-
(II) [(η5-(Me3Si)4FcC6H2}Ti(η5-C5H5)], was obtained in
a cyclohexadienyl ligand-forming reaction.6
Compounds in which two or more transition metals
are linked by an organic chain are capable of intramo-
lecular electron transfer and may also serve as starting
compounds for synthesis of metal-rich polymers and
other conductive and/or nonlinear optical materials.1 In
contrast to numerous late-late transition metal com-
plexes reported so far,2 the compounds involving early-
late transition metal combinations are relatively rare.3
Moreover, if binuclear early-late complexes are to be
applied as catalysts in C-C bond formation reactions
of olefins and acetylenes, the linking groups should not
contain hard donors (such as O, N) since highly elec-
trophilic early transition metals (Ti, Zr, Hf) are deac-
tivated by forming strong metal-hard donor bonds. As
far as the titanocene and ferrocene moieties are con-
cerned, known combinations are represented by ti-
Herein we describe alternative syntheses of ferroce-
nylacetylenes 2 and 3 and the synthesis and full spectral
characterization (NMR, IR, UV/vis, MS) of their ti-
tanocene complexes (η5-C5H5-nMen)2Ti(η2-FcCtCR) [n
) 0, 4, and 5; Fc ) ferrocenyl (η5-C5H5)Fe(η5-C5H4); R
) SiMe3 (4-6) and Ph (7-9)]. Solid-state structures of
5 and 9 and the catalytic activity of 6 and 9 toward
selective head-to-tail dimerization of (trimethylsilyl)-
acetylene (TMSA) are also reported.
* To whom correspondence should be addressed. E-mail: mach@
jh-inst.cas.cz.
Resu lts a n d Discu ssion
‡ Present address: Synthetic Rubber Research Institute, Kaucˇuk
a. s., 278 42 Kralupy nad Vltavou, Czech Republic.
Lithiation of ethynylferrocene, 1, with n-BuLi followed
by metathesis of the resulting lithioacetylene with
chlorotrimethylsilane gave [(trimethylsilyl)ethynyl]fer-
rocene, 2, in nearly quantitative yield. [(Phenyl)ethynyl]-
ferrocene, 3, was obtained in 89% yield by Pd/Cu-
catalyzed cross-coupling7 of acetylene 1 with iodobenzene
(1) (a) Long, N. J . Angew. Chem., Int. Ed. Engl. 1995, 34, 21. (b)
Colbert, M. C. B.; Lewis, J .; Long, N. J .; Raithby, P. R.; Younus, M.;
White, A. J . P.; Williams, D. J .; Payne, N. N.; Yellowless, L.; Beljonne,
D.; Chawdhurry, N.; Friend, R. H. Organometallics 1998, 17, 3034.
(2) (a) Fe/Rh: Wiedemann, R.; Fleischer, R.; Stalke, D.; Werner, H.
Organometallics 1997, 16, 866. (b) Ru/Pd, Fe/Pd: Lavastre, O.; Plass,
J .; Bachmann, P.; Guesmi, S.; Moinet, C.; Dixneuf, P. H. Organome-
tallics 1997, 16, 184. (c) Fe/Ru: Sˇteˇpnicˇka, P.; Gyepes, R.; Lavastre,
O.; Dixneuf, P. H. Organometallics 1997, 16, 5089. (d) Fe/Ru: Long,
N. J .; Martin, A. J .; de Biani, F. F.; Zanello, P. J . Chem. Soc., Dalton
Trans. 1998, 2017. (e) Fe/Ru: J ones, N. D.; Wolf, M. O.; Giaquinta, D.
M. Organometallics 1997, 16, 1352. (f) Fe/Pt: Sato, M.; Mogi, E.;
Kumakura, S. Organometallics 1995, 14, 3157. (g) Fe/Fe: Sato, M.;
Hayashi, Y.; Kumakura, S.; Shimizu, N.; Katada, M.; Kawata, S.
Organometallics 1996, 15, 721.
(4) Back, S.; Pritzkow, H.; Lang, H. Organometallics 1998, 17, 41.
(5) (a) Hayashi, Y.; Osawa, M.; Kobayashi, K.; Wakatsuki, Y. J .
Chem. Soc., Chem. Commun. 1996, 1617. (b) Hayashi, Y.; Osawa, M.;
Wakatsuki, Y. J . Organomet. Chem. 1997, 542, 241.
(6) Sˇteˇpnicˇka, P.; Podlaha, J .; Hora´cˇek, M.; Pola´sˇek, M.; Mach, K.
J . Organomet. Chem., in press.
(3) (a) Zr/Ru: Lemke, F. R.; Szalda, D. J .; Bullock, R. M. J . Am.
Chem. Soc. 1991, 113, 8466. (b) Hf/Fe: Back, S.; Rheinwald, G.; Zsolnai,
L.; Huttner, G.; Lang, H. J . Organomet. Chem. 1998, 563, 73.
(7) (a) Lavastre, O.; Cabioch, S.; Dixneuf, P. H.; Vohl´ıdal, J .
Tetrahedron 1997, 53, 7595. (b) Lavastre, O.; Ollivier, L.; Dixneuf, P.
H.; Sibandhit, S. Tetrahedron 1996, 52, 5495.
10.1021/om980832u CCC: $18.00 © 1999 American Chemical Society
Publication on Web 01/20/1999

628 Organometallics, Vol. 18, No. 4, 1999
Sˇ teˇpnicˇka et al.
Sch em e 1. Syn th esis of Eth yn ylfer r ocen es 2 a n d 3
Sch em e 2. Syn th esis of η2-Alk yn e Com p lexes 4-9
F igu r e 1. Molecular structure of 5; thermal ellipsoids
correspond to the 30% probability level. All hydrogen atoms
were omitted and only pivot and adjacent carbon atoms
were labeled for clarity.
a wavenumber decrease on increasing the number of
methyl substituents, thus following the same depen-
dence as the mentioned (C5H5-nMen)2Ti(η2-Me3SiCt
CSiMe3) complexes. Furthermore, complexes 4-6 dis-
play a trend of dependence of λmax of the longest
wavelength electronic absorption band on the number
of methyl groups similar to the above-mentioned com-
plexes (1060 nm for n ) 0 and 920 for n ) 4, 5),9
although at shorter wavelengths (880 and 810 nm for n
) 0 and 5, respectively). This band, tentatively assigned
to a CT d(Ti) f π*(alkyne) transition,9 is even more
blue-shifted in the spectra of 8 and 9 (710 and 725 nm,
respectively).
(Scheme 1). The alkynes 2 and 3 were reacted with
methylated titanocene dichlorides (η5-C5H5-nMen)2TiCl2
(n ) 0, 4, and 5) in the presence of magnesium turnings
in tetrahydrofuran to give the corresponding η2-alkyne
complexes (η5-C5H5-nMen)2Ti(η2-FcCtCR) 4-6, 8, and
9 in good yields after purification (Scheme 2). NMR and
MS spectra of the crude products showed the presence
of minor impurities due to reduction of the starting
alkynes (E)-FcCHdCHR and FcCH2CH2R (R ) SiMe3,
Ph). Unfortunately, the crude product resulting from the
reaction of (η5-C5H5)2TiCl2 and 3 was found reproducibly
to contain these reduced byproducts as major compo-
nents. Although the complex 7 was identified in the
mixture by NMR and MS spectra, all attempts to isolate
pure 7 failed. Such a low stability of complex 7 reflects
most likely the absence of methyl groups on the ti-
tanocene cyclopentadienyls, which protect the η2-alkyne
complex from subsequent reduction and/or decomposi-
tion.
Cr ysta l Str u ctu r e Deter m in a tion . The molecule
of 5 exhibits gross features typical for other titanocene
complexes with “organic” η2-alkynes such as Me3SiCt
CSiMe3 and PhCtCSiMe3.10 At variance, coordinated
9
[(trimethylsilyl)ethynyl]ferrocene is slightly shifted from
the plane bisecting the titanocene moiety (Figure 1,
Table 1), as manifested by the dihedral angles of the
TiC2 and (CH3)4C5H least-squares planes of 24.1(1)° and
20.8(1)°. Unlike (C5HMe4)2Ti(η2-Me3SiCtCSiMe3),9 the
hydrogen-bearing carbon atoms of the C5HMe4 ligands
in 5 are not directed to the top of the tilt angle, but one
of them (C(151)) is directed toward the ferrocenyl
moiety. Accordingly, the tilt angle of the cyclopentadi-
enyl rings in 5 is 5.5° lower than that in (C5HMe4)2Ti-
(η2-Me3SiCtCSiMe3). Also, the methyl groups of the
titanocene moiety are disposed from the least-squares
plane of the cyclopentadienyl ring by a maximum of 0.26
Å.
As a result of steric interactions of acetylene substit-
uents with titanocene cyclopentadienyls, the acetylene
ligand is bonded unsymmetrically; the CE(1), Ti, CE(2)
plane (CE ) centroid of cyclopentadienyl ring) intersects
the C(1)-C(2) bond only 0.34 Å from the C(2) carbon
atom. The coordinated carbon-carbon triple bond is
markedly lengthened up to the value typical for C-C
1H and 13C NMR spectra of 4-9 are in full accord with
the proposed structures and also compatible with the
solid-state structure of 5 and 9 determined by single-
crystal X-ray diffraction. The 13C NMR signals of both
triple-bond carbons of the ferrocenylacetylenes exhibit
a large downfield shift upon coordination to the ti-
tanocene unit (δC 195-218), thus indicating formation
of η2-alkyne complex.8 A remarkable but significantly
smaller coordination shift was also observed for the ipso
carbon of the substituted ferrocenyl cyclopentadienyl
(Cp) ring (compare δC ca. 85 to δC 65 for the noncoor-
dinated acetylenes). In contrast to analogous complexes
(C5H5-nMen)2Ti(η2-Me3SiCtCSiMe3) (n ) 0-5), where
the δC(CtC) chemical shift increases with the number
of methyl substituents on the rings (δC 245-249),9
complexes 4-6 show only marginal variation of δC(Ct
C). On the other hand, ν(CtC) vibrations in 4-9 show
(8) Burlakov, V. V.; Polyakov, A. V.; Yanovsky, A. I.; Struchkov, Yu.
T.; Shur, V. B.; Vol’pin, M. E.; Rosenthal, U.; Go¨rls, H. J . Organomet.
Chem. 1994, 476, 197.
(9) Varga, V.; Mach, K.; Pola´sˇek, M.; Sedmera, P.; Hiller, J .; Thewalt,
U.; Troyanov, S. I. J . Organomet. Chem. 1996, 506, 241.
(10) Rosenthal, U.; Go¨rls, H.; Burlakov, V. V.; Shur, V. B.; Vol’pin,
M. E. J . Organomet. Chem. 1992, 426, C53-C57.

Titanocene Complexes with Ferrocenylacetylenes
Organometallics, Vol. 18, No. 4, 1999 629
Ta ble 1. Selected Bon d Len gth s [Å], Bon d An gles
[d eg], a n d Dih ed r a l An glesa [d eg] for 5
Ti-C(1)
2.073(2) C(1)-Ti-C(2)
2.115(2) Ti-C(2)-Si
1.303(3) Ti-C(1)-C(11)
1.459(3) C(1)-C(2)-Si
36.24(9)
152.1(1)
146.6(2)
137.8(2)
Ti-C(2)
C(1)-C(2)
C(1)-C(11)
Si-C(2)
1.841(2) C(2)-C(1)-C(11) 139.3(2)
Si-C(31)
Si-C(32)
Si-C(33)
1.868(4) C(31)-Si-C(32)
1.870(4) C(31)-Si-C(33)
1.870(4) C(32)-Si-C(33)
108.4(2)
107.5(2)
107.4(3)
C(11)-C(1)-C(2)-Si -6.8(5)
{(CH3)4C5H}2Ti
3.905(4)
Cp2Fe
3.305(5)
1.652(2), 1.654(2)
2.019(4)-2.077(2)
2.04(2)
CE-CE
M-CE
2.098(2), 2.097(2)
2.347(3)-2.504(2)
2.41(5)
M-C(Cp)
M-C(Cp) av
C-C(Cp) av
(CpTi)-C(CH3) av
(Cp,Cp)
1.405(5)
1.40(2)
1.504(5)
F igu r e 2. Molecular structure of 9 showing the atom-
labeling scheme. Thermal ellipsoids are drawn at the 30%
probability level. For clarity, all hydrogen atoms were
omitted.
44.49(8)
2.21(3)
CE-M-CE
137.2(1)
178.1(2)
a
CE denotes the centroid of the corresponding cyclopentadienyl
ring.
Ta ble 2. Selected Bon d Len gth s [Å], Bon d An gles
[d eg], a n d Dih ed r a l An glesa [d eg] for 9
double bonds (compare C(1)-C(2) 1.303(3) Å vs 1.316
Å for C-CHdCH-C;11 cf. average value for three
crystallographically independent molecules of FcCtCH
in the solid state:12 1.17 Å). This elongation, typical for
titanacyclopropene-like complexes, is accompanied by
bending of the originally linear arrangement of the
C(Cp)-CtC-Si moiety, but without any notable torsion
[C(Cp)-CtC 139.3(2), CtC-Si 137.8(2)°, C(Cp)-CtC-
Si -6.8(5)°]. While the Si atom lies exactly in the TiC2
plane, the ferrocenyl group is bent outward. The dis-
tance of C(11) from the TiC2 plane is 0.118(5) Å, and
the dihedral angle of the TiC2 plane and its adjacent
cyclopentadienyl ring of the ferrocenyl group is 11.6(1)°.
The Cp rings of the ferrocenyl group are almost eclipsed,
with a dihedral angle of their least-squares planes of
only 2.21(3)°.
The overall geometry of complex 9 is similar to that
of 5 (Figure 2, Table 2). The titanocene cyclopentadi-
enyls are in a staggerred conformation and subtend the
dihedral angle of 40.1(2)°. The angle differs from that
of (C5Me5)2Ti(η2-Me3SiCtCSiMe3)8 by only 1.0°. Methyl
groups on the titanocene cyclopentadienyls are bent
outward from the titanium center, the perpendicular
distance of methyl groups from the cyclopentadienyl
plane varying in the range 0.08-0.35 Å. The ferrocene
unit adopts a nearly eclipsed conformation with the ring
tilt angle 5.8(2)°.
Ti-C(1)
2.088(3) C(1)-Ti-C(2)
2.093(3) Ti-C(2)-C(31)
1.312(5) Ti-C(1)-C(11)
1.455(5) C(1)-C(2)-C(31) 138.0(3)
1.419(5) C(2)-C(1)-C(11) 139.4(3)
1.461(5)
36.5(1)
150.5(3)
146.2(2)
Ti-C(2)
C(1)-C(2)
C(1)-C(11)
C(11)-C(12)
C(2)-C(31)
C-C(Ph) av
1.389(9) C-C-C(Ph) av
120(2)
C(11)-C(1)-C(2)-Si 15.8(7)
(C5Me5)2Ti
3.973(2)
Cp2Fe
3.312(2)
1.657(2), 1.657(2)
2.034(4)-2.091(3)
2.05(2)
CE-CE
M-CE
2.110(2), 2.106(2)
2.398(3)-2.453(3)
2.43(2)
M-C(Cp)
M-C(Cp) av
C-C(Cp) av
CCp-CMe av
(Cp,Cp)
1.412(9)
1.42(1)
1.500(8)
40.1(2)
5.3(3)
CE-M-CE
C-C-C(Cp) av
140.8(5)
108.0(4)
176.3(7)
108.0(8)
a
CE denotes the centroid of the corresponding cyclopentadienyl
ring.
Sch em e 3. Ca ta lytic Dim er iza tion of TMSA
In contrast to 5, the CE(1), Ti, CE(2) plane ap-
proximately bisects the coordinated triple bond, and the
torsional deformation at the coordinated triple bond is
more profound. This is docummented by the torsion
angle C(11)-C(1)-C(2)-C(31) of 15.8(7)°, by the dihe-
dral angle of the TiC2 and phenyl planes of 18.3(3)°, and
also by a much larger deviation of the ferrocenyl Cp ring
and the TiC2 plane from the parallel arrangement
[dihedral angle 34.2(2)°; cf. perpendicular distances to
the TiC2 plane C(31) 0.001(8), C(11) 0.259(7) Å]. The
phenyl group is slightly rotated from the TiC2 plane as
follows from the torsion angles C(1)-C(2)-C(31)-C(3n);
18.2(7)° for n ) 2 and -162.2(5)° for n ) 6.
Ca ta lytic Dim er iza tion of TMSA. Since the per-
methyltitanocene-bis(trimethylsilyl)acetylene complex
has been found an excellent catalyst for selective head-
to-tail dimerization of various terminal acetylenes,13,14
its analogues 6 and 9 were also tested for catalytic
activity toward dimerization of TMSA (Scheme 3). When
reacted with an excess of TMSA at 60 °C, compound 9
afforded selectively head-to-tail dimer (TMSA)2, 2,4-bis-
(trimethylsilyl)but-1-ene-3-yne (10), in quantitative yield
with no admixture of isomeric dimers, cyclotrimers, and
linear oligomers of TMSA, while complex 6 showed no
catalytic activity. However, the turnover number of 62.5
mol TMSA/mol 9 is considerably lower than that of (η5-
(11) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1.
(12) Gyepes, R.; Sˇteˇpnicˇka, P. Structure submitted to the Cambridge
Crystallographic Data Centre (reference number 961209L).
(13) Varga, V.; Petrusova´, L.; Cˇ ejka, J .; Hanusˇ, V.; Mach, K. J .
Organomet. Chem. 1996, 509, 235.
(14) Varga, V.; Petrusova´, L.; Cˇ ejka, J .; Mach, K. J . Organomet.
Chem. 1997, 532, 251.

630 Organometallics, Vol. 18, No. 4, 1999
Sˇ teˇpnicˇka et al.
C5Me5)2Ti(η2-Me3SiCtCSiMe3), in which case turnover
numbers up to 1500 were observed.13 Since all men-
tioned complexes bear the permethylated titanocene
moiety, the presence of which is essential for the
selective head-to-tail dimerization of terminal acetyl-
enes, the differences in their reactivity come most likely
from different stereoelectronic properties of the coordi-
nated acetylenes. The inertness of 6 toward TMSA
(proved by UV/vis spectra) allows us to conclude that
different activities of 6 and 9 result plausibly from
different abilities of the parent complexes to release the
coordinated alkyne under TMSA attack, affording the
active species.
[(η5-C5H5)Ti(µ-H)]2.15 THF, hexane, and C6D6 were
stored as solutions of dimeric titanocene on vacuum line.
TMSA (Aldrich, 98%) was carefully degassed in a
vacuum and mixed with dimeric titanocene. After
standing for ca. 2 h, purified TMSA was distilled from
a khaki green solution and stored on a vacuum line. If
the mixture of TMSA and dimeric titanocene turned red,
TMSA was distilled to a batch of fresh dimeric ti-
tanocene. This step was repeated until the resulting
mixture remained green. Ethynylferrocene, 1, was
synthesized from acetylferrocene. Diethylamine (99+%,
Fluka), iodobenzene (Fluka), and magnesium (for Grig-
nard reactions, Fluka) were used as received. In some
cases, activated magnesium was applied. It resulted as
the rest from preparation of titanocene η2-bis(trimeth-
ylsilyl)acetylene complexes and was washed with THF
and dried in a vacuum before use.
Con clu d in g Rem a r k s
The novel titanocene-ferrocene bimetalic complexes
4-6, 8, and 9, possessing the metalocene units joined
through the carbon atoms of the η2-coordinated triple
bond, are accessible in high yields by the magnesium-
reduction method. The yield of complex 7 is poor due to
a competitive reduction of acetylene 3, affording (E)-
FcCHdCHPh and FcCH2CH2Ph. The crystal structures
of 5 and 9 and NMR and IR spectra of all the complexes
indicate a titanacyclopropene-like coordination of the
acetylenes to the titanocene frame with various degrees
of deviation from the regular arrangement due to the
steric requirements of both the alkyne and the ti-
tanocene units. Complexes 6 and 9 were tested as the
catalysts for dimerization of TMSA. The fact that
complex 9 is an efficient catalyst for selective head-to-
tail dimerization of TMSA whereas its analogue 6 is
inactive points to a key role of the alkyne substituents
in determination of catalytic activity. However, further
investigations at steric and electronic properties of
coordinated internal acetylenes which control their
replacement by a terminal acetylene in the first step of
the catalytic cycle are required.
[(Tr im eth ylsilyl)eth yn yl]fer r ocen e, 2. In an argon
atmosphere, the solution of 1 (2.10 g, 10.0 mmol) in dry
diethyl ether (50 mL) was cooled to -20 °C, and n-BuLi
(7.5 mL 1.6 M in hexanes, 12 mmol) was added slowly.
The resulting mixture was stirred at -20 °C for 30 min
and cooled to -50 °C, and neat Me3SiCl (1.6 mL, 13
mmol) was introduced dropwise while stirring. The
mixture was allowed to warm to room temperature with
continuous stirring for 1 h (after 15 min formation of a
white precipitate started). After quenching with satu-
rated aqueous NaHCO3 (20 mL), the organic phase was
separated, washed with water (3 × 20 mL), dried over
MgSO4, and evaporated. The crude product was chro-
matographed on an alumina column with petroleum
ether (bp 40-60 °C) as the eluent. Evaporation of the
first band gave 2 as an orange solid. Yield: 2.75 g (97%).
1H NMR (400 MHz, CDCl3, Me4Si; cf. ref 17): δ 0.22 (s,
9 H, Me3Si), 4.16 (apparent t, 2 H, C5H4), 4.17 (s, 5 H,
Cp), 4.42 (apparent t, 2 H, C5H4). 13C (100 MHz, CDCl3,
Me4Si): δ 0.2 (Me3Si), 64.8 (Cipso, C5H4), 68.7 (CH; C5H4),
70.1 (CH; Cp), 71.7 (CH; C5H4), 90.5, 104.2 (CtC). IR
(KBr, cm-1): 3098 (w), 3087 (w), 2953 (m), 2139 (vs),
1409 (m), 1258 (s), 1248 (vs), 1104 (s), 1060 (m), 1037
(m), 1019 (s), 1002 (s), 923 (s), 860 (sh), 850 (vs), 840
(sh), 825 (vs), 759 (s), 722 (m), 699 (m), 539 (m), 506
(m), 487 (m), 476 (s), 455 (m). EI MS (65 °C): m/z
(relative abundance) 284 (6), 283 (23), 282 (M•+, 100),
280 (6), 267 ([M - Me]+, 20), 133.5 ([M - Me]2+, 13),
121 ([C5H5Fe]+, 7), 73 (Me3Si+, 4), 56 (Fe•+, 7). UV/vis
Exp er im en ta l Section
Gen er a l Com m en ts. NMR spectra were recorded at
room temperature in C6D6 or CDCl3 solutions on Varian
Unity 200 (1H, 200.06 MHz), Varian Unity 500 (13C,
125.70 MHz), or Varian Unity Inova 400 instruments
(1H, 399.95 MHz; 13C, 100.58 MHz). Chemical shifts (δ,
ppm) are given relative to the solvent signal (C6D6: δH
7.15, δC 128.0 ppm) or to internal tetramethylsilane. 29Si
NMR spectra were obtained by using the standard
DEPT pulse sequence (79.46 MHz) and are referenced
to external tetramethylsilane. Mass spectra were mea-
sured on VG 7070E and J EOL HX-110 instruments (EI,
70 eV, direct inlet at the temperature given below). IR
spectra in Nujol mulls were obtained on an FT IR ATI
Mattson Genesis instrument; those in KBr pellets or in
hexane solutions were recorded on a Specord 75 IR
spectrometer (Carl Zeiss, J ena, Germany). UV/vis spec-
tra were measured on a Varian Carry 17D spectrometer
using a pair of all-sealed quartz cells (Hellma; d ) 0.1
and 1.0 cm). All manipulations with titanocene com-
plexes 4-9 were performed using all-sealed glass de-
vices on an all-glass high-vacuum line equipped with
breakable seals. Diethyl ether was freshly distilled from
potassium. Hexane and THF were refluxed with LiAlH4
and distilled onto dimeric titanocene, (µ-η5:η5-C10H8)-
(hexane, nm): 330 (sh) ∼ 440. Anal. Calcd for C15H18
-
FeSi: C, 63.83; H, 6.43. Found: C, 64.05; H, 6.52.
[P h en yl(eth yn yl)]fer r ocen e, 3. Complex [Pd(PPh3)2-
Cl2] (72 mg, 0.1 mmol), CuI (21 mg, 0.1 mmol), and
iodobenzene (2.10 g, 10 mmol) were suspended in
diethylamine (50 mL) and carefully degassed by several
vacuum-argon cycles. To the resulting clear solution was
added 1 (2.11 g, 10 mmol), and the mixture was stirred
at room temperature for 16 h. Excess amine was
evaporated under reduced pressure, and the solid
residue was chromatographed on a silica column using
20% (v/ v) diethyl ether in hexane as the eluent.
Evaporation of the first colored band afforded 3 as a
(15) Antropiusova´, H.; Dosedlova´, A.; Hanusˇ, V.; Mach, K. Transition
Met. Chem. 1981, 6, 90.
(16) (a) Rosenblum, M.; Brawn, N.; Papenmeier, J .; Applebaum, M.
J . Organomet. Chem. 1966, 6, 173. (b) Rosenblum, M.; Brawn, N. M.;
Ciappenelli, D.; Tancrede, J . J . Organomet. Chem. 1970, 24, 469.
(17) Pudelski, J . K.; Callstrom, M. R. Organometallics 1994, 13,
3095.

Titanocene Complexes with Ferrocenylacetylenes
Organometallics, Vol. 18, No. 4, 1999 631
1
rusty-brown solid. Yield: 2.55 g (89%). H NMR (400
120.8, 123.8, 126.4 (C, Me4C5H); 210.9, 217.8 (η2-CtC).
EI-MS (direct inlet, 70 eV, 160 °C): m/z (relative
abundance) 572 (M•+, 0.04), 290 (87), 282 (100), 267 (16),
133.5 (15), 121 (12), 73 (8), 56 (13). IR (hexane, cm-1):
1644 (m), 1625 (m, sh), 1237 (s), 1103 (m), 1018 (m),
997 (m), 924 (m), 846 (vs), 825 (vs), 811 (vs), 746 (m),
662 (m), 540 (s), 492 (m), 480 (m), 468 (m), 420 (m). UV/
vis (hexane, nm): 475 (sh) . 805 (br). Anal. Calcd for
C33H44FeSiTi: C, 69.23; H, 7.75. Found: C, 69.54; H,
7.79.
MHz, CDCl3, Me4Si; cf. ref 18): δ 4.23 (apparent t, 2 H,
C5H4), 4.24 (s, 5 H, Cp), 4.50 (apparent t, 2 H, C5H4),
7.27-7.35 (m, 3 H, Ph), 7.46-7.51 (m, 2 H, Ph). 13C (100
MHz, in CDCl3, Me4Si): δ 65.2 (Cipso, C5H4), 68.8 (CH,
C5H4), 69.9 (CH, Cp), 71.4 (CH, C5H4), 85.7, 88.3 (Ct
C); 123.9 (Cipso, Ph), 127.6, 128.3, 131.4 (CH, Ph). IR
(KBr, cm-1): 3090 (w), 3050 (w), 2220 (m), 2204 (m),
1594 (m), 1490 (s), 1437 (s), 1407 (m), 1202 (m), 1100
(s), 1066 (m), 1023 (s), 996 (s), 921 (m), 820(vs), 811 (s),
754 (vs), 694 (s), 543 (s), 514 (m), 498 (vs), 485 (s). EI
MS (120 °C): m/z (relative abundance) 287 (21), 286
(M•+, 100), 284 (7), 228 (8), 165 ([M - C5H5Fe]+, 16),
[(η5-C5Me5)2Ti(η2-F cCtCSiMe3)], 6. The procedure
described for synthesis of 5 was followed starting from
(η5-C5Me5)2TiCl2 (0.389 g, 1 mmol), 2 (0.282 g, 1 mol),
and activated Mg (0.2 g, 8.3 mmol). Isolation as de-
scribed above afforded orange-brown crystalline complex
164 (5), 152 (5), 143(7), 121 ([C5H5Fe]+, 17), 56 (Fe•+
18). UV/vis (hexane, nm): 443. Anal. Calcd for C18H14
Fe: C, 75.55; H, 4.93. Found: C, 75.14; H, 4.91.
,
-
1
6. Yield: 0.51 g (84%). H NMR (200 MHz, C6D6): δ
[(η5-C5H5)2Ti(η2-F cCtCSiMe3)], 4. Complex (η5-
C5H5)2TiCl2 (0.249 g, 1 mmol), magnesium turnings
(0.024 g, 1 mmol), and 2 (0.282 g, 1 mmol) were charged
into the reaction ampule equipped with breakable seals
and evacuated, and THF (20 mL) was added on a
vacuum line. The mixture was stirred at room temper-
ature for 3 days to give a red-brown solution, while all
the magnesium had dissolved. THF was evaporated in
a vacuum at finally 60 °C to leave a brown solid. This
was extracted by hexane to remove MgCl2 until the
extract remained pale yellow. Cooling of the concen-
trated extract to -10 °C afforded 0.35 g (77%) of 4 as
red-brown crystals. 1H NMR (200 MHz, C6D6): δ -0.15
(s, 9 H, Me3Si), 3.10, 3.86 (2 × aparent t, 2 H, C5H4Fe);
4.17 (s, 5 H, C5H5Fe), 6.35 (s, 10 H, C5H5Ti). 13C NMR
(125 MHz, C6D6): δ -0.1 (Me3Si), 68.2 (CH, C5H4Fe),
69.5 (CH, C5H5Fe), 70.0 (CH, C5H4Fe), 85.8 (Cipso, C5H4-
Fe), 113.3 (CH, C5H5Ti), 208.6, 218.4 (η2-CtC). EI MS
(direct inlet, 70 eV, 130 °C): m/z (relative abundance)
460 (M•+, 1), 282 (75), 267 (12), 178 (100), 133.5 (11),
121 (13), 113 (19), 73 (8), 56 (14). IR (hexane, cm-1):
1713 (m, sh), 1685 (m), 1237 (s), 1216 (m), 1102 (m),
1010 (s), 927 (m), 848 (vs), 831 (vs), 810 (vs), 788 (vs),
745 (m), 682 (m), 655 (m), 646 (m), 532 (m), 488 (m),
480 (m), 470 (m), UV/vis (hexane, nm): 450 (sh) . 880
(br).
[(η5-C5HMe4)2Ti(η2-F cCtCSiMe3)], 5. Complex (η5-
C5HMe4)2TiCl2 (0.361 g, 1.0 mmol) and 2 (0.282 g, 1
mmol) were charged into an ampule and evacuated on
a vacuum line. THF (20 mL) and activated Mg (0.2 g,
8.3 mmol) were added, and the mixture was stirred at
room temperature. The color of the solution rapidly
turned from brown to blue and then, within 10 min, to
orange-brown. After standing overnight, the solution
was separated from excess magnesium and the THF
was evaporated. The brown residue was extracted by
hexane to give an orange-brown solution. Slow evapora-
tion of the solvent gave brown crystals of 5. They were
washed with a small amount of hexane and dried in a
vacuum. Yield: 0.49 g (87%). 1H NMR (200 MHz,
C6D6): δ 0.17 (s, 9 H, Me3Si), 1.32, 1.49, 2.08, 2.09 (4 ×
s, 6 H, Me4C5H); 3.28, 3.90 (2 × aparent t, 2 H, C5H4);
4.16 (s, 5 H, C5H5), 5.31 (s, 2 H, Me4C5H). 13C NMR (125
MHz, C6D6): δ -0.1 (Me3Si), 13.1, 13.2, 13.4, 13.8
(Me4C5H); 67.3 (CH, C5H4Fe), 69.4 (CH, C5H5), 70.1 (CH,
C5H4), 86.3 (Cipso, C5H4), 112.4 (CH, Me4C5H), 120.1,
0.22 (s, 9 H, Me3Si), 1.81 (s, 30 H, Me5C5), 3.98 (s, 5 H,
C5H5Fe), 4.02, 4.28 (2 × apparent t, 2 H, C5H4Fe). 13C
NMR (125 MHz, C6D6): δ 0.3 (Me3Si), 11.4 (Me5C5), 69.2,
69.3 (2 × CH, C5H4Fe); 69.4 (CH, C5H5Fe), 85.0 (Cipso
,
C5H4Fe), 121.1 (Me5C5), 212.6, 218.3 (η2-CtC). EI MS
(direct inlet, 70 eV, 200 °C): m/z (relative abundance)
600 (M•+, 0.01), 318 (73), 282 (100), 267 (16), 133.5 (13),
121 (6), 56 (6). IR (hexane, cm-1): 3093 (m, b), 1627 (s,
b), 1258 (s), 1241 (s), 1208 (m), 1107 (s), 1073 (s), 1022
(s), 1001 (m), 928 (m), 851 (vs), 831 (vs), 816 (vs), 545
(s), 495 (m), 472 (m), 431 (s). UV/vis (hexane, nm): 480
. 810 (br).
[(η5-C5H5)2Ti(η2-F cCtCP h )], 7. Complex (η5-C5H5)2-
TiCl2 (0.249 g, 1.0 mmol), 3 (0.286 g, 1.0 mmol),
magnesium (0.024 g, 1.0 mmol), and THF (20 mL) were
heated in a sealed ampule to 60 °C for 10 h. THF was
removed in a vacuum, and the resulting brown residue
was extracted with hexane. Evaporation of the hexane
extract gave only a mixture of (E)-FcCHdCHPh and
FcCH2CH2Ph containing 7 as the minor component. All
1
attempts to obtain pure 7 were unsuccessful. H NMR
(400 MHz, C6D6): δ 2.83, 3.80 (2 × apparent t, 2 H,
C5H4); 4.04 (s, 5 H, C5H5Fe), 6.42 (s, 5 H, C5H5Ti), 6.96-
7.20 (m, 5 H, Ph). EI MS (direct inlet, 70 eV, 120 °C):
m/z 464 (M•+), 178 ([C10H10Ti]+), 286 (3•+) observed after
evaporation of volatile FcCHdCHPh and FcCH2CH2Ph
from the sample directly in the probe.
[(η5-C5HMe4)2Ti(η2-F cCtCP h )], 8. Complex (η5-C5-
HMe4)2TiCl2 (0.361 g, 1.0 mmol), 3 (0.286 g, 1 mmol),
and activated Mg (0.2 g, 8.3 mmol) were reacted in THF
(20 mL) at 60 °C for 30 min. THF was evaporated in a
vacuum, and the orange-brown residue was extracted
by hexane. Evaporation of hexane afforded a yellow-
1
brown waxy solid. Yield: 0.53 g (92%). H NMR (400
MHz, C6D6): δ 1.46, 1.47, 2.02, 2.07 (4 × s, 6 H,
Me4C5H); 3.67, 4.00 (2 × br apparent t, 2 H, C5H4); 4.23
(s, 5 H, C5H5), 5.16 (s, 2 H, Me4C5H), 6.97-7.24 (m, 5
H, Ph). 13C NMR (100 MHz, C6D6): δ 13.3, 13.3, 13.5,
13.7 (Me4C5H); 67.3, 68.9 (CH, C5H4); 69.2 (C5H5), 86.6
(Cipso, C5H4), 111.9 (CH, Me4C5H), 120.5, 120.9 (C,
Me4C5H); 125.1 (CH, Ph), 126.0, 126.0 (C, Me4C5H);
130.6 (CH, Ph), 140.1 (Cipso, Ph), 195.7, 199.1 (η2-Ct
C); one of the CH carbons of the phenyl group is
overlapped by the solvent signal. EI MS (140 °C): m/z
(relative abundance) 576 (M•+, 0.7), 290 (100), 286 (9).
IR (hexane, cm-1): 3087 (m), 1757 (w), 1661 (m, b), 1589
(s), 1329 (w), 1309 (w), 1252 (m), 1107 (s), 1071 (m), 1025
(s), 1000 (s), 974 (w), 930 (w), 913 (w), 896 (m), 860 (w),
(18) Rausch, M. D.; Siegel, A.; Klemann, L. P. J . Org. Chem. 1966,
31, 2703.

632 Organometallics, Vol. 18, No. 4, 1999
Sˇ teˇpnicˇka et al.
Ta ble 3. Cr ysta llogr a p h ic Da ta , Da ta Collection ,
a n d Str u ctu r e Refin em en t for 5 a n d 9a
827 (sh), 815 (vs), 759 (m), 700 (vs), 493 (s), 422 (m).
UV/vis (hexane, nm): 470(sh) . 710.
[(η5-C5Me5)2Ti(η2-F cCtCP h )], 9. Following the pro-
cedure for preparation of 8, (η5-C5Me5)2TiCl2 (0.389 g,
1 mmol), 3 (0.286 g, 1 mmol), and activated magnesium
(0.2 g, 8.3 mmol) gave crude 9 as a brown residue after
evaporation of THF. The residue was extracted by 50
mL of hexane to afford a brown-yellow solution, which
deposited brown crystals of pure 9 after cooling to -18
°C. Yield: 0.51 g (85%), mp 101 °C. 1H NMR (400 MHz,
C6D6): δ 1.25 (s, 30 H, Me5C5), 3.21, 3.52 (2 × apparent
t, 2 H, C5H4); 3.76 (s, 5 H, C5H5), 6.62-6.75 (m, 5 H,
Ph). 13C (100 MHz, C6D6): δ 12.4 (Me5C5), 67.1, 68.9
(CH, C5H4); 69.3 (C5H5), 87.4 (Cipso, C5H4), 121.8 (Me5C5),
124.9, 127.9, 130.8 (CH, Ph); 140.4 (Cipso, Ph), 195.1,
198.5 (η2-CtC). EI MS (180 °C): m/z (relative abun-
dance) 604 (M•+, 0.07), 318 (100), 286 (15). IR (KBr,
cm-1): 3092 (w), 2970 (m), 2897 (s), 2848 (m), 1651 (m),
1585 (s), 1435 (s, b), 1375 (vs), 1106 (s), 1025 (s), 1001
(s), 812 (vs), 760 (s), 698 (vs), 600 (m), 587 (m), 500 (m),
488 (s), 480 (s), 464 (m). UV/vis (hexane, nm): 520 (sh)
. 725. Anal. Calcd for C38H44FeTi: C, 75.50; H, 7.34.
Found: C, 75.43; H, 7.29.
5
9
formula
M
T (K)
C
33H44FeSiTi
C38H44FeTi
604.48
150.0(1)
monoclinic, P21/c
(No. 14)
572.52
296(1)
monoclinic, P21/n
cryst syst, space group
(No. 14)
a (Å)
15.342(3)
16.617(3)
b (Å); â (deg)
c (Å)
11.162(3); 105.57(2) 12.494(2); 98.51(1)
18.501(3)
3052(1); 4
1.246
14.892(2)
3057.7(8); 4
1.313
V (Å3); Z
D
calc (g mL-1
)
µ (mm-1
color, habit
cryst dimens (mm3)
)
0.795
0.761
orange-brown, bar red-brown, prism
0.39 × 0.50 × 0.61 0.29 × 0.43 × 0.50
no. of diffractions collected; 7005; 2θ e 50.0
4982; 2θ e 48.0
2θ range (deg)
h, k, l range
(h +k (l
5368
(h (k (l
4784
4368
no. of unique diffractions
no. of observed diffractions; 4045
|Fo| > 4σ(Fo)
F(000)
1216
501
0.00
5.99, 9.19; 1.03
1280
418
0.00
5.18, 12.90; 1.05
no. of refined params
(∆/σ)max
R(F), wR(F2) (%); S for
all diffractions
R(F), wR(F2) (%) for
observed diffractions
R(σ) (%)
3.33, 8.13
4.26, 11.71
3.32
0.23; -0.25
1.88
0.37; -0.47
∆F (e Å-3
)
Rea ctivity of 6 a n d 9 tow a r d TMSA. Compounds
6 and 9, respectively (0.1 g, 0.16 mmol), were dissolved
in hexane (2 mL), TMSA (1.5 mL, 10 mmol) was added,
and the mixture was kept at 60 °C in a vessel equipped
with an all-sealed quartz cell (Hellma, 0.2 cm). The
course of the reaction was monitored by UV/vis-NIR
spectroscopy every ca. 4 h in order to check the
concentrations of 6 (λ 810 nm) and 9 (λ 725 nm),
respectively, and the concentration of unreacted TMSA
(λ 1540 nm; 2 × ν(C-H)). Upon additon of TMSA to
complex 6, the concentration of the titanocene complex
decreased by ca. 10%, and the content of TMSA re-
mained unchanged even after heating to 60 °C for 100
h. For 9, the band of the starting titanocene complex
disappeared completely after 8 h at 60 °C, the acetylene
being completely consumed within 20 h. The volatiles
from reaction of 9 with excess TMSA were separated
by vacuum distillation at ambient temperature and
collected in a trap cooled by liquid nitrogen (overnight).
GC-MS and NMR analysis of the distillation product
revealed the presence of 2,4-bis(trimethylsilyl)but-1-en-
3-yne, Me3SiCtCC(SiMe3)dCH2 (10), as the sole prod-
uct. 1H NMR (400 MHz, C6D6): δ 0.13, 0.18 (2 × s, 9 H,
R(F) ) ∑||Fo| - |Fc||/∑|Fo|, wR(F2) ) [∑(w(Fo - Fc2)2)/
a
2
(∑w(Fo2)2)]1/2, S ) [∑(w(Fo - Fc2)2)/(Ndiffrs - Nparams)]1/2, R(σ) )
2
2
∑σ(Fo2)/∑Fo
.
automatically centered diffractions with 15° e θ e 16°
(5) and 13° e θ e 13.5° (9).
The structure of 5 was solved by direct methods
(SIR92, ref 19), yielding the positions of all non-
hydrogen atoms. Hydrogen atoms were identified on the
difference electron density map and freely isotropically
refined. The full-matrix least-squares refinement was
carried out by minimization of the function ∑w(|Fo| -
|Fc|)2 (SHELXL93, ref 20), where w ) [σ2(Fo2) +
2
2
(0.0487P)2 + 0.9775P]-1 and P ) (Fo + 2Fc )/3.
The crystal of 9 used for the collection of diffraction
data suffered from nonmerohedral twinning, therefore
the correction according to the method of Pratt21 et al.
and J ameson22 et al. was included in the refinement.
From the twin law,
hII
kII
lII
hI
-1
0 -1
0
0
1/3
0
kI
)( )
lI
)
( ) (
0 -1
2
Me3Si); 5.54, 6.13 (2 × d, 1 H, J HH ) 3.4 Hz, dCH2).
it follows that the two domains contribute to the
diffractions with l ) 3n. The refined fractions of these
domains were 0.635 and 0.365. The structure was solved
by direct methods (SIR92) followed by least-squares
13C NMR (100 MHz, C6D6): δ -2.2, 0.2 (Me3Si); 98.7,
107.2 (CtC); 134.9 (dCH2), 135.3 (dC(SiMe3)-). 29Si
DEPT (C6D6): -18.5 (s, CtCSiMe3), -2.2 (s, Cd
CSiMe3).
refinement on F2 (SHELXL97, ref 23); the weighting
Cr ysta l Str u ctu r e Deter m in a tion . X-ray-quality
crystals of 5 and 9 were grown by a slow evaporation of
their hexane solutions. For both complexes, the selected
specimen was inserted into a Lindenmann-glass capil-
lary and sealed by wax in a glovebox. The diffractions
were measured on a four-circle diffractometer, CAD4-
MACHIII, at 296(1) and 150.0(1) K for 5 and 9,
respectively, using graphite-monochromated Mo KR
radiation (λ ) 0.710 73 Å) and θ-2θ scan. Three
standard diffractions monitored every 1 h showed no
significant intensity variation (e4%). The lattice pa-
rameters were refined by least-squares fitting from 25
scheme applied was ∑w(|Fo| - |Fc|)2, where w ) [σ2(Fo
)
2
2
2
+ (0.0730P)2 + 4.2468P]-1 and P ) (Fo + 2Fc )/3. All
(19) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giaco-
vazzo, C.; Guagliardi, A.; Polidori, G. J . Appl. Crystallogr. 1994, 27,
435.
(20) Sheldrick, G. M. SHELXL93. Program for Crystal Structure
Refinement from Diffraction Data; University of Go¨ttingen: Go¨ttingen,
Germany, 1993.
(21) Pratt, C.; Coyle, B. A.; Ibers, J . A. J . Chem. Soc. 1971, 2146.
(22) J ameson, G. B.; Schneider, R.; Dubler, E.; Oswald, H. R. Acta
Crystallogr., Sect. B 1982, B38, 3016.
(23) Sheldrick, G. M. SHELXL97. Program for Crystal Structure
Refinement from Diffraction Data; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.

Titanocene Complexes with Ferrocenylacetylenes
Organometallics, Vol. 18, No. 4, 1999 633
the non-hydrogen atoms were refined anisotropically.
Aromatic hydrogens (phenyl, ferrocenyl) were found on
difference electron density maps and isotropically re-
fined. Methyl hydrogen atoms were included in theo-
retical positions and assigned C-H 0.96 Å and Uiso(H)
) 1.2Ueq(C). Further details on data collection and
refinement as well as relevant crystallographic data are
given in Table 3.
Agency of the Czech Republic (Grant No. 203/96/0111)
also sponsored access to the Cambridge Crystallographic
Data Centre.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal-
lographic data, atomic coordinates, thermal parameters, in-
tramolecular distances and angles, dihedral angles of least-
squares planes, and packing diagrams for 5 and 9. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Ack n ow led gm en t. Support for this research was
provided by the Grant Agency of the Czech Republic
(Grant Nos. 203/96/0948 and 203/97/0242). The Grant
OM980832U