Syntheses and structures of doubly tucked-in titanocene complexes with tetramethyl(aryl)cyclopentadienyl ligands

Article abstract of DOI:10.1016/S0022-328X(00)00784-1

Titanocene-bis(trimethylsilyl)ethyne complexes [Ti(η⁵-C₅Me₄R)₂(η ²-Me₃SiC≡CSiMe₃)], where R = benzyl (Bz, 1a), phenyl (Ph, 1b) and p-fluorophenyl (FPh, 1c), thermolyse at 150-160°C to give products of double C-H activation [Ti(η⁵-C₅Me₄Bz){η ³:η⁴-C₅Me₃(CH ₂)(CHPh)}] (2a), [Ti(η⁵-C₅Me₄Bz){η ³:η⁴-C₅Me₂Bz(CH ₂)₂}] (2a′), [Ti(η⁵-C₅Me₄Ph){η ³:η⁴-C₅Me₂Ph(CH ₂)₂}] (2b), and [Ti(η⁵-C₅Me₄FPh){η ³:η⁴-C₅Me₂FPh(CH ₂)₂}] (2c). In the presence of 2,2,7,7-tetramethylocta-3,5-diyne (TMOD) the thermolysis affords analogous doubly tucked-in compounds bearing one η³:η⁴-allyldiene and one η⁵-C₅Me₄R ligand having TMOD attached by its C-3 and C-6 carbon atoms to the vicinal methylene groups adjacent to the substituent R (R = Bz (3a), Ph (3b), and FPh (3c)). Compound 3a is smoothly converted into air-stable titanocene dichloride [TiCl₂{η⁵-C₅Me₂Bz(CH ₂CH(t-Bu)CH=CHCH(t-Bu)CH₂)}(η⁵-C ₅Me₄Bz)] (4a) by a reaction with hydrogen chloride. Yields in both series of doubly tucked-in complexes decrease in the order of substituents: Bz ? Ph > FPh. Crystal structures of 1c, 2a, 2b, and 3b have been determined.

Full text of DOI:10.1016/S0022-328X(00)00784-1

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 620 (2001) 39–50
Syntheses and structures of doubly tucked-in titanocene complexes
with tetramethyl(aryl)cyclopentadienyl ligands
a
a
b
c
c
&
Volkmar Kupfer , Ulf Thewalt , Iva Tisˇlerova´ , Petr Steˇpnicˇka , Ro´bert Gyepes ,
Jirˇ´ı Kubisˇta d, Michal Hora´cˇek d, Karel Mach d,*
a Sektion fu¨r Ro¨ntgen- und Elektronenbeugung, Uni6ersita¨t Ulm, 89069 Ulm, Germany
b Department of Organic Chemistry, Charles Uni6ersity, Hla6o6a 2030, 128 40 Prague 2, Czech Republic
c Department of Inorganic Chemistry, Charles Uni6ersity, Hla6o6a 2030, 128 40 Prague 2, Czech Republic
d J. Heyro6sky´ Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejsˇko6a 3, 182 23 Prague 8, Czech Republic
Received 2 August 2000
Abstract
Titanocene–bis(trimethylsilyl)ethyne complexes [Ti(h5-C5Me4R)2(h2-Me3SiCꢀCSiMe3)], where R=benzyl (Bz, 1a), phenyl (Ph,
1b) and p-fluorophenyl (FPh, 1c), thermolyse at 150–160°C to give products of double CꢁH activation [Ti(h5-C5Me4Bz){h3:h4-
C5Me3(CH2)(CHPh)}] (2a), [Ti(h5-C5Me4Bz){h3:h4-C5Me2Bz(CH2)2}] (2a%), [Ti(h5-C5Me4Ph){h3:h4-C5Me2Ph(CH2)2}] (2b), and
[Ti(h5-C5Me4FPh){h3:h4-C5Me2FPh(CH2)2}] (2c). In the presence of 2,2,7,7-tetramethylocta-3,5-diyne (TMOD) the thermolysis
affords analogous doubly tucked-in compounds bearing one h3:h4-allyldiene and one h5-C5Me4R ligand having TMOD attached
by its C-3 and C-6 carbon atoms to the vicinal methylene groups adjacent to the substituent R (R=Bz (3a), Ph (3b), and FPh
(3c)). Compound 3a is smoothly converted into air-stable titanocene dichloride [TiCl2{h5-C5Me2Bz(CH2CH(t-Bu)CHꢂCHCH(t-
Bu)CH2)}(h5-C5Me4Bz)] (4a) by a reaction with hydrogen chloride. Yields in both series of doubly tucked-in complexes decrease
in the order of substituents: BzꢀPh\FPh. Crystal structures of 1c, 2a, 2b, and 3b have been determined. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Bis(trimethylsilyl)ethyne complexes; CꢁH activation; Crystal structures; Diyne cycloaddition; Thermolysis; Titanium; Titanocenes
under reductive conditions since electron-poor species
formed by the reduction tend, in the absence of other
1. Introduction
ligands, to increase their electron count by oxidative
addition of methyl CꢁH bonds across the electron-defi-
Methyl groups in permethylated metallocene deriva-
tives of early transition metals become readily activated
cient metal centre [1]. The transfer of hydrogen from
one of the methyl groups to titanium was shown by
Bercaw and Brintzinger [2a] to be the main reason of
inherent instability of decamethyltitanocene [Ti(h5-
C5Me5)2]. Elimination of hydrogen from CꢁH-activated
primary product leads to a singly tucked-in perme-
thyltitanocene
[Ti(h5-C5Me5){h1:h5-C5Me4(CH2)}]
[2,3]. Similarly, thermally induced elimination of meth-
ane from [TiMe(h5-C5Me5)2] affords the same product,
and an elimination of two molecules of methane from
[TiMe2(h5-C5Me5)2] gives a doubly tucked-in com-
pound, [Ti(h5-C5Me5){h3:h4-C5Me3(CH2)2}] (2) [4].
This complex is also obtained by thermolysis of [Ti(h5-
C5Me5)2(h2-Me3SiCꢀCSiMe3)] (1) at 130°C, which, be-
sides complex 2, affords a mixture of (E)- and
Scheme 1.
* Corresponding author. Tel.: +420-2-8585367; fax: +420-2-
8582307.
E-mail address: mach@jh-inst.cas.cz (K. Mach).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00784-1

40
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
2. Results and discussion
2.1. Thermolysis 1a–c in the absence of TMOD
Fully cyclopentadienyl-substituted titanocene dichlo-
rides of the type [TiCl2(h5-C5Me4R)2], where R=
CH2C6H5 (Bz), C6H5 (Ph), and p-C6H4F (FPh), were
reduced by magnesium in the presence of
bis(trimethylsilyl)ethyne (BTMSE) to give the corre-
sponding h2-alkyne complexes [Ti(h5-C5Me4R)2(h2-
BTMSE)] (R=Bz, 1a, Ph, 1b, and FPh, 1c), which
were thermolysed with and without addition of TMOD
at 150–160°C in m-xylene solutions. Heating of com-
plex 1a to 150°C for 3 h in the absence of TMOD
affords a mixture of two doubly tucked-in complexes 2a
and 2a% (Scheme 2). The complexes were separated on
the basis of their different solubilities in hexane and
obtained in total 87% isolated yield and ca. 10:1 ratio
(2a:2a%). The volatile residue from the thermolysis con-
Scheme 2.
tained only the solvent and
a
mixture of
Me3SiCHꢂCHSiMe3 isomers (EꢀZ), indicating
a
(Z)-Me3SiCHꢂCHSiMe3 (EꢀZ) as the product of
twofold hydrogen transfer from a titanocene intermedi-
ate onto the alkyne triple bond (Scheme 1) [5]. Com-
pounds [Ti(h5-C5Me4R)2(h2-Me3SiCꢀCSiMe3)], where
R=H or SiMe3, behave differently: at 200°C the for-
mer gave a mixture of isomeric complexes [Ti(h5-
C5Me4H){h3:h4-C5Me2(CH2)2H}] in a very low yield
[5], whereas the latter afforded titanocene [Ti(h5-
C5Me4(SiMe3)}2] in high yield at only 70–80°C [6].
It has been demonstrated that the role of proton
acceptor in CꢁH activation of titanocene methyl groups
is not restricted to s-bonded hydrocarbyls or
Me3SiCꢀCSiMe3. When the thermolysis of 1 is carried
out in the presence of 2,2,7,7-tetramethylocta-3,5-diyne
(TMOD), an unusual cycloaddition of TMOD to vici-
nal methyl groups of the h5-C5Me5 ligand takes place
to afford complex 3 (Scheme 1), bearing two chirality
centres in the annelated ring as the sole detectable
product in nearly quantitative yield. Complex [Ti(h5-
C5Me4H)2(h2-Me3SiCꢀCSiMe3)], similar to the above-
mentioned thermolysis in the absence of TMOD, gave
under similar conditions only a very low yield of the
adduct (3%). In its structure, vicinal pairs of two exo-
methylene groups on the newly formed allyldiene ligand
and TMOD-substituted methylene groups on the cy-
clopentadienyl ring are located in a position adjacent to
the unsubstituted ring-carbon atom [7].
transfer of two hydrogen atoms from the titanocene
moiety to the leaving BTMSE. As follows from spectral
and structural data, the titanium centre in both com-
plexes is coordinated by one h3:h4-allyldiene ligand
(henceforth denoted as Ad) [4] and one unchanged
h5-cyclopentadienyl ligand (or Cp%), similar to the
product of double CꢁH activation of permethylated
complex [Ti(h5-C5Me5)2(h2-BTMSE)] [5].
The diene system of the Ad ligand in the major
product 2a is formed from the benzyl group and vicinal
methyl group, whereas two vicinal methyl groups adja-
cent to the benzyl group take part in its formation in
the case of minor complex 2a%. Both compounds are
easily distinguishable by 13C chemical shifts of the
newly formed sp2 carbon atoms that appear at lC 81.0
(ꢂCH2) and 90.2 (ꢂCHPh) in 2a but at lC 68.19 and
68.29 ppm (both ꢂCH2) in 2a%. The latter values are in
accordance with the NMR data on the doubly tucked-
in complexes obtained by boiling
a
[TiCl2(h5-
C5HMe4)2]–LiAlH4 mixture in toluene [8]: lC 67.24 and
69.91 were found for the vicinal methylene carbon
atoms adjacent to the ring proton (asymmetric isomer),
lC 67.04 was observed for vicinal methylene groups
remote from the ring proton (symmetrical isomer), and
lC 67.64 for [Ti(h5-C5Me5){h3:h4-C5Me3(CH2)2}] [4,9].
Structures assigned to 2a and 2a% are further supported
by NOESY spectra, which for 2a% show peaks due to
through-space interactions between ꢂCH2 protons of
the Ad ring and methyl groups of both Cp% and Ad
ligands (lH 1.0l1.74, 1.75, 1.79, 2.44 and 3.55) and
signals due to interactions of neighbouring methyl
groups of the Ad ring (lH 1.06l1.32). More impor-
tantly, cross peaks at lH 1.32l2.44 and lH 1.79l3.55
assign the signals of the benzylic CH2 protons at lH
2.44/2.69 and lH 3.55 to Ad and Cp% rings respectively.
Because the nature of the substituent R in the [Ti(h5-
C5Me4R)2(h2-Me3SiCꢀCSiMe3)] compounds undoubt-
edly controls the efficiency of their thermolysis, we have
undertaken a thermolytic study on a series of such
complexes containing benzyl, phenyl and p-
fluorophenyl as the substituent R both without any
additive and in the presence of TMOD.

V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
41
In the case of 2a, NOESY cross-peaks at lH
1.21l2.26, 1.7l3.4 and 0.97l1.10 were observed.
NMR data are thus in keeping with single-crystal X-ray
analysis of 2a (Section 2.5).
with the aromatic ring band at 1600 cm−1. This is
compatible with the CꢁC bond order between one and
two, as it is also indicated by the chemical shift of the
exo-methylene carbon atoms, by the CꢁC bond dis-
1
,
tance close to 1.44 A and the geometry of the Ad
It is also worth noting that in the H-NMR spectra
ligands (see below). The nature of Ti···CH2ꢂCring bond-
ing in 2 was suggested by Teuben and coworkers [4] to
be of p-type, as already expressed by the term ‘allyldi-
ene’. An absence of d2 electrons in ultraviolet pho-
toelectron spectra of 2 was accounted for by their
mixing with empty ligand p-orbitals [12]. The electronic
absorption spectra of bis(exo-methylene) complexes 2a%,
2b, and 2c display an absorption band at 610 nm. In 2a,
containing the methylene/benzylidene diene system, this
band is shifted to 580 nm. Hence, it is obvious that the
aryl substituents in compounds 2a, 2b and 2c do not
affect the bonding. However, they affect the reactivity
of the parent BTMSE complexes; as a result of the
substituent effects, the yields of doubly tucked-in com-
plexes decrease roughly with the decreasing electron
donation effect of the substituents in the order: Me:
BzꢀPh\FPh:H (for Me and H see Ref. [5]).
of 2a% the PhCH2 protons on the Cp% ligand are equiva-
lent (A2 spin system), whereas those of the Ad ligand
appear as a doublet of doublets due to an AB spin
system (2JHH=15.1 Hz) with remarkable anisochronic-
ity (DwAB/JAB=6.7). On the other hand, benzylic pro-
tons in 2a are observed as an AB spin system with large
J value but only small separation of the signals, i.e.
only weak satellites due to scalar coupling are observed
(2JHH=16.4 Hz; DwAB/JAB=0.40). Spectra of both
[TiCl2(h5-C5Me4Bz)2] [10] and [Ti(h5-C5Me4Bz)2(h2-
BTMSE)] [11] exhibit only true singlets corresponding
to the benzylic A2 spin systems.
Under similar conditions, compounds 1b and 1c gave
only low yields of analogous doubly tucked-in com-
pounds 2b and 2c. Increasing the thermolysis tempera-
ture to 160°C did not improve the yields. The
non-equivalence of exo-methylene carbon resonances
(71.3 and 73.2 ppm for 2b and 71.3 and 72.7 ppm for
2c) points to an asymmetric structure similar to 2a% in
both cases. This assumption was further confirmed by
X-ray diffraction measurement of 2b (Section 2.5).
All 2-type complexes are thermally robust, melt
above 100°C and give the molecular ions as the base
peaks in their electron impact mass spectra. Their in-
frared spectra are uninformative with respect to the
exo-methylene bonds because the CꢁH and CꢂC bonds
of aryl substituents may hide their features. The
w(CringꢂCH2) (or ꢂCHPh) absorption band, however, is
very likely shifted below 1500 cm−1, not interfering
2.2. Thermolysis of 1a–c in the presence of TMOD
Thermolysis of 1a–c in the presence of TMOD re-
sults in the formation of doubly tucked-in compounds
3a–c with TMOD attached to the C5Me4R ligand (Cp%)
to give h(1,8-11)-bicyclo[6.3.0]-3,6-bis(2-methyl-2-pro-
pyl) - 9,10 - dimethyl - 11 - aryl - undec - 4 - ene - 1(8),9(10)-
dien-11-yl (Scheme 3). The cycloaddition of TMOD has
apparently no observable influence on the bonding
mode of the allyldiene ligands, as indicated by elec-
tronic absorption spectra being practically identical
with non-annelated analogues 2a–c, and also the yields
of the cycloadducts follow the same order of sub-
stituents. The structures of complexes 3a–c were deter-
mined from their NMR spectra and further
corroborated by X-ray structural analysis of compound
3b. The mass spectra show molecular ions as the base
peaks, with other intensive signals being due to frag-
ments formed by the loss of the t-butyl group and
(TMOD+2H). 1H- and 13C-NMR spectra of com-
plexes 3a–c clearly identified the structure of the Ad
ligands to be identical with the structures of Ad ligands
in 2a, 2b, and 2c respectively. A compound analogous
to 2a% was not detected. NMR features due to the
annelated octene ring are similar to that of 3 and
indicate that the benzyl group is not involved in the
ring formation in 3a. The substitution of the CpTMOD
was not unequivocally determined from the NMR data.
However, it is likely that all the 3-type compounds
behave in a uniform manner, forming structures in
which the substituent R or proton neighbours the meth-
ylene groups of the annelated ring, as observed for the
Scheme 3.

42
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
outlined for compound 3, requiring a transfer of two
pairs of hydrogen atoms from methylene groups of Ad
and Cp% ligands to triple bonds of TMOD [7].
2.3. Deri6atization of 3a
As has been shown recently for compound 3 [13], this
highly air-sensitive compound can be converted into an
air-stable titanocene dichloride by simply reacting with
two equivalents of HCl. This method of derivatization
was also shown to be feasible for compound 3a, which
is accessible in high yield. Its hexane solution reacted
smoothly with gaseous HCl to give a red finely crys-
talline titanocene dichloride 4a, which is stable in air
(Scheme 3). Its structure was deduced from mass spec-
1
tra, H- and 13C-NMR spectra and elemental analysis.
The mass spectra, although not showing the peaks of
the molecular ion, display fragments arising from losses
of Cl, Cp% and CpTMOD thereof. NMR spectra clearly
indicate the replacement of the Ad ligand by the h5-
C5Me4Bz ligand, whereas signals due to the CpTMOD
ligand remain.
Fig. 1. ORTEP drawing of 1c with 30% probability ellipsoids and atom
numbering scheme.
Table 1
,
Selected bond lengths (A) and bond angles (°) for 1c
Bond distances
TiꢁCE(1)a
TiꢁCE(2)b
TiꢁC(1)
TiꢁC(3)
TiꢁC(5)
2.139(2)
2.137(2)
2.418(2)
2.458(2)
2.448(2)
2.484(2)
2.428(2)
1.480(3)
1.353(3)
1.860(2)
1.874(4)
TiꢁC(31)
TiꢁC(32)
TiꢁC(2)
TiꢁC(4)
TiꢁC(6)
2.114(2)
2.121(2)
2.448(2)
2.507(2)
2.511(2)
2.449(2)
1.303(3)
1.485(3)
1.360(3)
1.874(2)
1.875(4)
2.4. Molecular structure of 1c
The only crystal structure in the series of p-
fluorophenyl-substituted titanocene derivatives was ob-
tained for the starting compound 1c. Its molecular
structure is shown in Fig. 1 and selected geometrical
parameters are given in Table 1. The p-fluorophenyl
substituents occupy positions vicinal to the hinge posi-
tions at the opposite sides of the plane defined by the
centroids of the Cp% rings CE(1) and CE(2) and the
titanium atom, as in [TiCl2(h5-C5Me4Ph)2] [14]. The
values of the CE(1)ꢁTiꢁCE(2) angle and the angle
between the least-squares planes of the cyclopentadi-
enyl rings are very close to those found in 1 [5,15,16].
Also, within the precision of measurement, the geome-
try of the h2-coordinated BTMSE (with the CꢁC dis-
tance close to that of a double bond and the silicon
atoms deviated from linear arrangement at an angle of
ca. 135°) is identical with those of 1 and similar
BTMSE complexes. The carbon atoms of methyl
groups in the hinge position of the Cp% rings show a
maximum deviation from the least-squares planes of
TiꢁC(7)
TiꢁC(8)
TiꢁC(10)
C(5)ꢁC(19)
C(22)ꢁF(1)
C(31)ꢁSi(1)
C(31)ꢁC(32)
C(10)ꢁC(25)
C(28)ꢁF(2)
C(32)ꢁSi(2)
(Si(1)ꢁCMe av
)
(Si(2)ꢁCMe)av
Bond and dihedral angles
CE(1)ꢁTiꢁCE(2) 138.9(1)
C(31)ꢁC(32)ꢁTi
C(31)ꢁC(32)
C(31)ꢁTiꢁC(32)
C(32)ꢁC(31)ꢁTi
C(32)ꢁC(31)
35.85(8)
72.40(13)
136.35(18)
71.76(13)
135.24(18)
ꢁSi(2)
ƒ(1)b
ƒ(3)d
ƒ(5)f
ꢁSi(1)
ƒ(2)c
ƒ(4)e
41.49(12)
22.47(21)
48.68(13)
19.06(21)
54.86(10)
a CE(1): centroid of the Cp% ring defined by C(1)ꢁC(5) atoms;
CE(2): centroid of the Cp% ring defined by C(6)ꢁC(10) atoms.
b Dihedral angle between the least-squares planes defined by the
C(1)ꢁC(5) and C(6)ꢁC(10) atoms.
c Dihedral angle between the least-squares plane defined by the
C(1)ꢁC(5) and the plane defined by the C(31), C(32), and Ti atoms.
d Dihedral angle between the least-squares plane defined by the
C(6)ꢁC(10) and the plane defined by the C(31), C(32), and Ti atoms.
e Dihedral angle between the least-squares planes defined by the
C(1)ꢁC(5) and C(19)ꢁC(24) atoms.
,
the Cp% rings (above 0.3 A), as is common to structures
of analogous complexes [5,6,16]. Other carbon atoms,
including the ipso-carbon atom of FPh substituents,
deviate less. The p-fluorophenyl substituents thus prob-
ably do not impose a higher steric strain than methyl
groups. However, they decrease the overall electron-do-
nating ability of the Cp% ligand and, hence, affect the
reactivity of 1c compared with that of 1 or other
compounds, e.g. [Ti{h5-C5Me4(SiMe3)}2(h2-Me3SiCꢀ
CSiMe3)] [6].
f Dihedral angle between the least-squares planes defined by the
C(6)ꢁC(10) and C(25)ꢁC(30) atoms.
C5Me4H analogue 3% [7] and in the crystal structure of
3b (vide infra). Hence, the mechanism of the formation
of 3a–c can also be expected to be the same as that

V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
43
Fig. 3. ORTEP drawing of 2b with 30% probability ellipsoids and atom
numbering scheme.
Table 3
Fig. 2. ORTEP drawing of 2a with 30% probability ellipsoids and atom
numbering scheme.
,
Selected bond lengths (A) and bond angles (°) for 2b
Bond distances
TiꢁCE(1)a
TiꢁCE(2)b
TiꢁCE(3)c
TiꢁC(1)
TiꢁC(2)
TiꢁC(3)
TiꢁC(4)
TiꢁC(5)
TiꢁC(7)
TiꢁC(9)
1.963(3)
1.783(3)
2.047(3)
2.117(3)
2.316(4)
2.107(3)
2.252(3)
2.381(3)
2.550(3)
2.389(3)
1.514(5)
C(1)ꢁC(2)
C(1)ꢁC(3)
C(3)ꢁC(4)
C(3)ꢁC(5)
C(5)ꢁC(7)
C(7)ꢁC(9)
C(1)ꢁC(9)
C(5)ꢁC(6)
C(7)ꢁC(8)
C(9)ꢁC(10)
C(24)ꢁC(25)
1.439(4)
1.458(4)
1.447(4)
1.469(4)
1.416(4)
1.417(4)
1.458(4)
1.477(4)
1.525(4)
1.503(5)
1.480(4)
Table 2
a
,
Selected bond lengths (A) and bond angles (°) for 2a
Bond distances
TiꢁCE(1)b
TiꢁCE(2)c
TiꢁCE(3)d
TiꢁC(1)
TiꢁC(2)
TiꢁC(3)
TiꢁC(4)
TiꢁC(5)
TiꢁC(7)
TiꢁC(9)
1.932(4)
1.738(4)
2.026(4)
2.086(4)
2.298(4)
2.072(4)
2.228(4)
2.364(4)
2.522(4)
2.347(4)
2.343(4)
2.350(4)
2.356(4)
2.375(4)
C(1)ꢁC(2)
C(1)ꢁC(3)
C(3)ꢁC(4)
C(3)ꢁC(5)
C(5)ꢁC(7)
C(7)ꢁC(9)
C(1)ꢁC(9)
C(5)ꢁC(6)
C(7)ꢁC(8)
C(9)ꢁC(10)
C(2)ꢁC(11)
C(20)ꢁC(21)
C(21)ꢁC(30)
CringꢁCMe(Cp%)av
1.438(5)
1.464(5)
1.432(6)
1.448(6)
1.412(6)
1.400(6)
1.445(5)
1.499(6)
1.501(6)
1.502(6)
1.476(5)
1.512(5)
1.515(5)
1.509(5)
CringꢁCMe(Cp)
Bond and dihedral angles
CE(1)ꢁTiꢁCE(3)
TiꢁC(2)ꢁC(1)
C(1)ꢁC(3)ꢁC(5)
C(5)ꢁC(7)ꢁC(9)
C(7)ꢁC(5)ꢁC(6)
156.9(1)
C(2)ꢁTiꢁC(4)
TiꢁC(4)ꢁC(3)
C(3)ꢁC(5)ꢁC(7)
C(7)ꢁC(9)ꢁC(1)
C(3)ꢁC(5)ꢁC(6)
ƒ(1)d
75.9(1)
76.2(2)
108.7(2)
109.4(3)
124.9(2)
8.3(3)
63.7(2)
106.9(2)
108.5(2)
126.3(2)
C(22)ꢁC(24)ꢁC(25) 125.8(3)
C(26)ꢁC(24)ꢁC(25) 126.3(2)
ƒ(2)e
43.0(3)
TiꢁC(20)
TiꢁC(22)
TiꢁC(24)
TiꢁC(26)
a CE(1)-centroid of the Cp% ring defined by the C(1), C(3), C(5),
C(7) and C(9) atoms.
b CE(2)-centroid of the ring defined by atoms C(1), C(2), C(3) and
C(4).
Bond and dihedral angles
CE(1)ꢁTiꢁCE(3)
TiꢁC(2)ꢁC(1)
C(1)ꢁC(3)ꢁC(5)
C(5)ꢁC(7)ꢁC(9)
C(1)ꢁC(2)ꢁC(11)
C(20)ꢁC(21)ꢁC(30)
ƒ(2)f
153.7(2)
C(2)ꢁTiꢁC(4)
TiꢁC(4)ꢁC(3)
C(3)ꢁC(5)ꢁC(7)
C(7)ꢁC(9)ꢁC(1)
C(9)ꢁC(1)ꢁC(3)
ƒ(1)e
79.5(2)
64.8(2)
108.1(4)
109.1(4)
106.2(3)
12.4(4)
c CE(3)-centroid of the Cp% ring defined by atoms C(20), C(22),
C(24), C(26) and C(28).
63.0(2)
107.1(3)
109.3(4)
126.6(4)
114.5(3)
44.0(4)
d Dihedral angle between the least-square planes defined by the
C(1), C(3), C(5), C(7), C(9) and C(20), C(22), C(24), C(26) and C(28)
atoms.
e Dihedral angle between the least-square planes defined by the
C(1), C(3), C(5), C(7), C(9) and C(1), C(2), C(3) and C(4) atoms.
a One molecule of n-hexane of crystallization is placed in the centre
of unit cell: C(36), C(37) and C(38); symmetry operation used to
generate equivalent atoms: (1−x, 1−y, −z).
2.5. Molecular structures of doubly tucked-in
complexes
b CE(1): centroid of the Cp% ring defined by atoms C(1), C(3), C(5),
C(7) and C(9).
Molecular structures of 2a, 2b, and 3b commonly
contain the central titanium atom bonded to one Ad
and one Cp% ligand; however, they differ in some re-
markable features. The Ad ligand in 2a bears one
exo-methylene and one benzylidene group in vicinal
positions (Fig. 2, Table 2), the structure of 2b contains
two phenyl groups directed into the same direction
c CE(2): centroid of the ring defined by atoms C(1), C(2), C(3) and
C(4).
d CE(3): centroid of the Cp% ring defined by atoms C(20), C(22),
C(24), C(26) and C(28).
e Dihedral angle between the least-squares planes defined by the
C(1), C(3), C(5), C(7) and C(9) and C(20)ꢁC(28) atoms.
f Dihedral angle between the least-squares planes defined by the
C(1), C(3), C(5), C(7) and C(9) and C(1), C(2), C(3) and C(4) atoms.

44
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
parallel to each other (Fig. 3, Table 3), and the Cp%
ligand in 3b is modified by the annelated eight-mem-
bered ring arising from the cycloaddition of TMOD
(Fig. 4, Table 4). Independently of the various sub-
stituents on the cyclopentadienyl ligands (Bz, Ph or
Ph/TMOD), the least-squares planes of their rings are
perpendicular to the TiꢁCE(1) vectors within the preci-
sion of the measurements (i.e. no ring slippage is ob-
served). The Ad ligand can be imagined as consisting of
two planar systems (or two half-planes): the original
cyclopentadienyl ring (now formally the allylic donor
system) and a four-membered 1,3-diene p-system. The
allyldiene C5-ring is slipped in such a way that the TiꢁC
distance increases from the shortest for the carbon
atoms common to the both planes (2.072(4)–
Fig. 4. ORTEP drawing of 3b with 30% probability ellipsoids and atom
numbering scheme.
,
2.117(3) A), to the exo-methylene carbon atoms
,
2.228(4)–2,316(4) A), outer allyl carbon atoms
,
,
(2.347(4)–2.389(3) A) and internal allyl carbon atoms
(2.522(4)–2.561(4) A). The distances of the titanium
atom from the allyldiene C5-ring least-squares plane are
Table 4
,
,
,
1.873(3) A (2a), 1.906(3) A (2b) and 1.889(2) A (3b),
and those from the diene least-squares plane are
,
Selected bond lengths (A) and bond angles (°) for 3b
,
,
,
1.710(4) A (2a), 1.762(3) A (2b) and 1.717(3) A (3b).
The angles subtended by these Ad half-planes are
44.0(2)° (2a), 43.0(1)° (2b) and 42.9(2)° (3b). The allyl-
diene C5-ring declines from an arrangement parallel to
the Cp% ring plane by an angle of 12.4(2)° for 2a, 8.3(1)°
for 2b and 9.1(2)° for 3b, the allyl part of the allyldiene
C5-ring being located at the top of the angle. The
deviations of methyl and other carbon atoms attached
to the Cp% and Ad C5-rings from their least-squares
Bond distances
TiꢁCE(1)a
TiꢁCE(2)b
TiꢁCE(3)c
TiꢁC(28)
1.956(4)
1.743(4)
2.029(4)
2.561(4)
2.382(4)
2.081(4)
2.257(5)
2.088(3)
2.234(4)
2.376(3)
1.458(5)
1.431(6)
1.434(6)
1.442(6)
1.421(5)
1.409(5)
C(1)ꢁC(2)
C(1)ꢁC(3)
C(3)ꢁC(4)
C(3)ꢁC(5)
C(5)ꢁC(6)
C(5)ꢁC(12)
C(1)ꢁC(9)
C(1)ꢁC(27)
C(12)ꢁC(27)
C(12)ꢁC(13)
C(26)ꢁC(27)
C(19)ꢁC(20)
C(28)ꢁC(29)
C(36)ꢁC(37)
C(30)ꢁC(31)
C(30)ꢁC(32)
1.504(5)
1.409(5)
1.526(5)
1.419(5)
1.486(5)
1.439(5)
1.458(4)
1.430(5)
1.410(5)
1.513(5)
1.522(5)
1.325(6)
1.500(6)
1.498(5)
1.510(5)
1.446(6)
TiꢁC(30)
TiꢁC(32)
TiꢁC(33)
TiꢁC(34)
TiꢁC(35)
TiꢁC(36)
C(32)ꢁC(34)
C(32)ꢁC(33)
C(34)ꢁC(35)
C(34)ꢁC(36)
C(28)ꢁC(36)
C(28)ꢁC(30)
,
planes are a maximum 0.133(6) A for C(23) in 2a,
,
,
0.166(5) A for C(23) in 2b, and 0.179(6) A for C(13)
,
and 0.192(6) A for C(29) in 3b. The angles between the
least-squares planes of the Cp and phenyl rings in 2b
are slightly different, 36.3(2)° and 45.0(2)°, but the
difference is approximately equal to the declination of
the Cp rings from the parallel arrangement and, hence,
the phenyl rings are parallel. The distance between the
carbon atoms of these phenyl rings exceeds 4.0 A, and
is larger than the shortest intermolecular distances (ca.
3.7 A). In 3b, the dihedral angles of phenyl rings and
Bond and dihedral angles
CE(1)ꢁTiꢁCE(3)
TiꢁC(33)ꢁC(32)
C(1)ꢁC(3)ꢁC(5)
C(30)ꢁC(32)ꢁC(34) 107.0(4)
C(34)ꢁC(36)ꢁC(28) 108.9(3)
155.4(2)
64.2(2)
106.9(2)
C(33)ꢁTiꢁC(35)
TiꢁC(35)ꢁC(34)
C(28)ꢁC(30)ꢁC(32) 108.8(4)
C(32)ꢁC(34)ꢁC(36) 106.7(3)
C(34)ꢁC(36)ꢁC(37) 124.7(3)
77.71(19)
65.2(2)
,
,
C(3)ꢁC(5)ꢁC(6)
126.7(3)
C(5)ꢁC(12)ꢁC(13)
126.0(3)
their adjacent C5-rings are similar: Cp%/Ph 50.4(1)° and
Ad/Ph 34.8(2)°. However, the phenyl rings are placed
on opposite sides of the molecule. The geometrical
parameters of the Ad ligands, annelated cyclooctene
substituent, and common parts of the doubly tucked-in
complexes differ only marginally from those of the only
known structures of this type in compound 3 and its
tetramethyl-substituted analogue 3% (see Fig. 5) [7]. The
bond distances of the exo-methylene groups and their
adjacent carbon atoms to the titanium centre are essen-
tially the same as those found for the single tucked-in
C(12)ꢁC(27)ꢁC(26) 126.0(3)
C(14)ꢁC(19)ꢁC(20) 131.2(4)
C(13)ꢁC(12)ꢁC(27) 125.4(3)
C(19)ꢁC(20)ꢁC(21) 128.6(4)
ƒ(1)d
9.1(2)
ƒ(2)e
42.9(2)
a CE(1)-centroid of the Cp% ring defined by C(28), C(30), C(32),
C(34) and C(36) atoms.
b CE(2)-centroid of the ring defined by atoms C(32), C(33), C(34)
and C(35).
c CE(3)-centroid of the Cp% ring defined by C(1), C(3), C(5), C(12)
and C(27) atoms.
d Dihedral angle between the least-square planes defined by the
C(28), C(30), C(32), C(34) and C(36) and C(1), C(3), C(5), C(12) and
C(27) atoms.
complex
[Ti{h5:h1-C5Me4(CH2)}(h5-C5Me5)]
[17],
e Dihedral angle between the least-square planes defined by the
C(28), C(30), C(32), C(34), C(36) and C(32), C(33), C(34) and C(35)
atoms.
which is a paramagnetic d1 system having its exo-methyl-
ene carbon s-bonded to titanium [12]. The geometric

V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
45
Fig. 5.
Table 5
Ring-puckering coordinates for 3b and related complexesa
,
,
,
,
Compound
Q2 (A)
Q3 (A)
Q4 (A)
Q (A)
ƒ
(°)
Refs.
2
3b
3
3%
5
5%
6
7
1.389(4)
1.262(8)
1.246(3)
1.342(5)
1.347(6)
1.449(3)
1.508(3)
1.412(7)
0.066(4)
0.023(8)
0.052(3)
0.063(5)
0.043(7)
0.099(3)
0.066(3)
0.019(7)
0.185(4)
1.404(4)
1.281(8)
1.280(3)
1.362(5)
1.366(6)
1.461(3)
1.517(3)
1.420(7)
69.3(2)
335.6(4)
168.1(1)
162.4(2)
343.5(3)
146.9(1)
147.7(1)
147.0(3)
This work
[7]
[7]
[13]
[13]
[13]
[13]
[19]
−0.219(8)
0.284(3)
0.227(5)
−0.231(7)
0.158(3)
0.162(3)
0.155(7)
[PdBr2(h4-C8H12)]
a See Fig. 5.
parameters, however, seem to be insufficient to extend
this conclusion and to suggest s-TiꢁC bonds, and,
hence, the Ti(IV) valence, in the doubly tucked-in com-
plexes, too.
BzꢀPh\FPh. The benzyl group takes part preferably
in the formation of the allyldiene ligand in the absence
of TMOD and exclusively in the presence of TMOD.
The cycloaddition of TMOD involves two vicinal
methyl groups adjacent to the phenyl group in 3b; the
placement of the annelating cyclooctene ring in a posi-
tion adjacent to the non-methyl substituent is very
likely a common feature of this reaction. It has to be
noted that our attempts to carry out analogous cy-
cloadditions of other 1,4-substituted 1,3-butadiynes,
e.g. the phenyl and trimethylsilyl derivatives, to the
above BTMSE complexes of type 1 were unsuccessful.
However, these diynes, as well as TMOD, form a
number of products with CꢁH-activated permethylated
titanocenes generated in situ by the reduction of the
titanocene dichlorides with magnesium [20,21].
Another feature worth mentioning is the conforma-
tion of the cyclooctene ring in the structure of 3b. Table
5 provides a comparison of its ring-puckering coordi-
nates [18] with some related complexes. It is obvious
that the conformation of the free eight-membered ring
in all the cases mentioned is best described as a twisted
boat–boat conformation (ideal values: Q2\0, Q3=
Q4=0 and ƒ2=k×90°). On the other hand, upon
p-coordination of either its central double or triple
bond the conformation changes to a boat conformation
(ideal values: Q2\0, Q3=Q4=0 and ƒ2=k×90°+
45°), similar to that of h4-coordinated 1,5-cyclooctadi-
ene, for example, as demonstrated by the last entry in
Table 5. In this regard, the annelating cyclooctene
moiety can be regarded as a rather unique diene system
capable of flexible h4-coordination.
4. Experimental
4.1. General
3. Concluding remarks
All manipulations, including spectroscopic measure-
ments, were performed in vacuum using all-sealed glass
devices equipped with breakable seals. 1H-
(399.95 MHz) and 13C{1H}-NMR (100.58 MHz) spec-
tra were recorded on a Varian UNITY Inova 400
spectrometer in C6D6 solutions at 25°C. Chemical shifts
(l/ppm) are given relative to the solvent signal (l/H
7.15, l/C 128.0). Assignment of the data is based on 1H,
Substituted analogues of the doubly tucked-in ti-
tanocene complex [Ti(h5-C5Me5){h3:h4-C5Me3(CH2)2}]
[4,5] can be prepared by thermally induced CꢁH activa-
tion of the complexes [Ti(h5-C5Me4R)2(h2-BTMSE)]
(R=benzyl, phenyl and p-fluorophenyl) in the presence
and the absence of TMOD. However, their yields de-
crease strongly in the order of substituents R: Me:
1
13C{1H}, 13C-APT, H,1H-COSY-90 and 13C-HSQC ex-

46
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
periments. NOESY spectra were used to distinguish
between isomers 2a and 2a%. EI-MS spectra were ob-
tained on a VG-7070E double-focusing mass spectrom-
eter at 70 eV. The crystalline samples in sealed
capillaries were opened and inserted into the direct inlet
under argon. The spectra are represented by the peaks
of relative abundance higher than 6% and by important
peaks of lower intensity. GC–MS analyses were per-
formed on a Hewlett Packard gas chromatograph (5890
series II) equipped with a capillary column SPB-1
(length 30 m; Supelco) and a mass spectrometric detec-
tor (5971 A). UV–near-IR spectra were measured in
the range 280–2000 nm on a Varian Cary 17D spec-
trometer in all-sealed quartz cuvettes (Hellma). IR spec-
tra were recorded in an air-protecting cuvette on a
Specord IR-75 (Carl Zeiss, Jena, Germany) infrared
spectrometer. Samples in KBr pellets were prepared in
a Labmaster 130 glovebox (mBraun) under purified
nitrogen (concentrations of oxygen and water below
2.0 ppm).
−0.11 (s, 9H, Me3Si), 1.77, 1.88 (2×s, 6H, Me4C5);
6.06 (apparent dd, J%=5.4, 8.3 Hz, 2H, C6H4F), 6.65
(apparent t, J%:8.7 Hz, 2H, C6H4F). 13C{1H}-NMR: l
3.7 (Me3Si), 13.3 (lH 1.77), 14.6 (lH 1.88) (Me4C5);
114.7 (d, 2JFC=21 Hz, C6H4F g-CH), 123.1, 125.2,
125.7 (Me4C5, CꢁMe); 130.6 (d, 3JFC=7 Hz, C6H4F
4
b-CH), 133.7 (d, JFC=3 Hz, C6H4F a-Cipso), 161.5 (d,
1JFC=245 Hz, C6H4F d-CF), 251.6 (h2-CꢀC). Note:
n
the JFC (n=1–4) agree with those reported for simple
monofluorobenzene derivatives p-FC6H4X [24]. EI-MS
(direct inlet, 70 eV, 165°C): complex 1c dissociates to
give m/z (relative abundance) 478 ([M−BTMSE]+·; 9)
and fragment ions of BTMSE 170 (5), 157 (9), 156 (18),
155 (100), 73 (20). IR (KBr, cm−1): 3046 (w), 2947 (vs),
2894 (vs), 2853 (sh), 1880 (vw), 1634 (w), 1598 (s), 1560
(s), 1510 (s), 1480 (m), 1440 (m), 1374 (s), 1293 (w),
1240 (vs), 1220 (vs), 1156 (s), 1094 (m), 1014 (m), 988
(w), 832 (vs), 748 (s), 680 (m), 660 (s), 620 (m), 590 (s),
560 (s), 518 (m), 448 (s), 414 (m). UV–near-IR (hexane,
23°C): 400ꢀ930 nm.
4.2. Chemicals
4.4. Thermolysis of complexes 1a–c
The solvents THF, hexane, and toluene were dried by
refluxing over LiAlH4 and stored as solutions of
m-Xylene (4.0 ml) was added to 1a (0.64 g, 1.0 mmol)
and the solution was heated in a sealed ampoule to
150°C for 3 h, whereupon the initially yellow mixture
turned turquoise. All volatiles were distilled off in
vacuo and were subjected to GC–MS analysis. The
residue was dissolved in 30 ml of warm hexane and left
standing overnight to crystallize. A green mother liquor
was separated from a turquoise crystalline solid. This
solid was dissolved in warm hexane (20 ml) and, after
standing overnight, a crystalline solid was separated
from the solution. The solid was separated and recrys-
tallized from hexane to give turquoise crystals of 2a as
the major product. The mother liquors were combined,
their volumes reduced to 10 ml, and this solution was
left to crystallize at ambient temperature. A blue solid
crystallized out from a green mother liquor, which was
separated and discarded. The blue solid was purified by
recrystallization from a minimum amount of warm
hexane to give pure 2a% as a minor product. The
volatiles from the thermolysis contained a mixture of
(E)- and (Z)-1,2-bis(trimethylsilyl)ethene and only a
trace of BTMSE.
dimeric
titanocene
[(m-h5:h5-C10H8)(m-H)2{Ti(h5-
C5H5)}2] [22]. Bis(trimethylsilyl)ethyne (BTMSE,
Fluka) was degassed, stored as a solution of dimeric
titanocene for 4 h, and finally distilled into ampoules on
a
vacuum line. 2,2,7,7-Tetramethyl-3,5-octadiyne
(TMOD) (Aldrich) was used directly after degassing.
Magnesium turnings (Fluka, purum for Grignard reac-
tions) were initially used in large excess for the prepara-
tion of [Ti(h5-C5Me5)2(h2-BTMSE)] [5]. Unreacted
highly active magnesium was washed with THF, sepa-
rated in vacuum and used in subsequent reductions.
Compounds 1a [11], 1b [11] and [TiCl2(h5-C5Me4FPh)2]
[10] were prepared by literature procedures.
4.3. Preparation of [TiCl2(p5-C5Me4FPh)2(p2-BTMSE)]
(1c)
Following the general procedure [23], complex
[TiCl2(h5-C5Me4FPh)2] (1.0 g, 1.8 mmol) was degassed
and mixed with activated magnesium (ca. 0.5 g,
20 mmol), BTMSE (1.0 ml, 4.5 mmol) and THF
(40 ml). The mixture was stirred at 60°C until the red
colour of the solution turned yellow and then it was
heated to 60°C for another 30 min. The resulting yellow
solution was separated from unreacted magnesium,
THF and BTMSE were distilled off in vacuum and the
residue was extracted by 50 ml of hexane. After stand-
ing overnight, a grey powder (largely MgCl2) separated
from a clear yellow solution. The solution was concen-
trated and crystallized at ambient temperature to give
yellow crystals of 1c. Yield 1.0 g, 86%. 1H-NMR: l
[Ti(h5-C5Me4Bz)(h3:h4-C5Me3(CH2)(CHPh)]
(2a).
Turquoise crystals, yield 0.37 g (79%). M.p. 108°C.
2
1H-NMR: l 0.97 (d, 1H, JHH=4.9 Hz, AB of ꢂCH2),
2
1.08 (s, 3H, MeꢁC), 1.10 (d, 1H, JHH=4.9 Hz, AB of
ꢂCH2), 1.21, 1.31, 1.64, 1.65, 1.67, 1.71 (6×s, 3H,
MeꢁC), 2.26 (s, 1H, ꢂCHPh), 3.41 and 3.43 (2×d, 1H,
2JHH=16.4 Hz, AB of PhCH2(Cp)), 6.82–7.33 (m,
10H, Ph). 13C-NMR (all signals singlets): l 10.3, 10.7
(2C), 11.5, 11.6, 11.8, 11.9 (7×MeꢁC), 32.7 (CH2Ph),
81.0 (ꢂCH2), 90.2 (ꢂCHPh), 120, 120.2 (2C), 120.3,
122.3, 122.7 (Cipso(Ph), MeꢁC, CꢂCH2 and/or

V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
47
CꢂCHPh), 123.0, 123.9 (CH(Ph)), 124.4 (Cipso(Ph),
MeꢁC, CꢂCH2 and/or CꢂCHPh), 126.2, 128.4, 128.7
(CH(Ph)), 135.3, 141.3, 143.7, 146.7, 147.2 (Cipso(Ph),
MeꢁC, CꢂCH2 and/or CꢂCHPh). One of the CH(Ph)
resonances is masked by the solvent signal, (lC ca.
128.2) as follows from a comparison of 13C{1H}- and
13C-APT-NMR spectra. EI-MS (direct inlet, 70 eV,
145°C): m/z (relative abundance) 470 (15), 469 (41), 468
(M·+, 100), 467 (15), 466 (13), 452 (5), 453 (11), 259
(7), 258 (11), 253 (9), 252 (7), 181 (6), 178 (8). IR (KBr,
cm−1): 3073 (vw), 3044 (w), 3000 (w), 2890 (m,vb),
2832 (m,b), 1582 (vs,b),1476 (vs,b), 1437 (vs,b), 1372
(s), 1332 (s), 1279 (m), 1260 (w), 1214 (m), 1170 (w),
1150 (vw), 1069 (m), 1023 (s), 993 (w), 927 (w), 897 (w),
887 (m), 839 (m), 823 (m), 794 (m), 760 (s), 724 (vs),
692 (vs), 647 (w), 627 (vw), 612 (w), 592 (vw), 578 (m),
559 (vw), 536 (vw), 517 (s), 455 (w), 440 (m). UV–vis
(toluene, nm): 360(sh)ꢀ590.
singlets): l 10.6 (lH 1.13), 11.6 (lH 1.54), 11.9 (lH 1.66),
12.2 (lH 1.70), 13.1 (lH 1.85), 13.6 (lH 1.98) (6×Me);
71.3 (lH 1.01 and 1.05), 73.2 (lH 1.07 and 1.16) (ꢂCH2);
119.3, 119.9, 120.6, 121.2, 124.1 (CꢁMe, CꢁPh and Ph
Cipso); 126.3, 126.4, 128.9, 130.4 (Ph, CH; two signals
are overlapped by the solvent resonance); 133.4, 135.6,
137.1 (CꢁMe, CꢁPh and Ph Cipso); 142.9, 146.7
(CꢂCH2). EI-MS (direct inlet, 70 eV, 130°C; m/z (%)):
442 (15), 441 (43), 440 (M·+; 100), 439 (16), 438 (13),
425 ([M−Me]+, 9), 423 (5), 242 ([M−Cp%]+, 6), 241
(8), 240 (10), 239 (7), 238 (7), 237 (10), 181 (5), 165 (8),
41 (5). IR (KBr) (cm−1): 3074 (w), 3034 (m), 2966 (s),
2933 (sh), 2900 (vs), 2847 (s), 1596 (s), 1568 (w), 1500
(s), 1474 (m), 1447 (s), 1426 (s), 1366 (s), 1353 (m), 1260
(w), 1214 (vw), 1173 (vw), 1153 (vw), 1093 (w), 1073
(m), 1020 (s), 980 (w), 914 (w), 894 (m), 847 (m), 832
(s), 820 (s), 800 (m), 773 (m), 754 (vs), 724 (s), 700 (vs),
660 (w), 644 (w), 626 (w), 610 (w), 586 (m), 575 (m),
498 (m), 440 (m). UV–vis (hexane, nm): 320(sh)\
390(sh)ꢀ610.
[Ti(h5-C5Me4Bz)(h3:h4-C5Me2Bz(CH2)2)] (2a%). Blue
crystalline solid, yield 37 mg (8%). M.p. 103°C. 1H-
2
NMR: l 0.98, 1.00 (2×d, 1H, JHH=4.7 Hz, AB of
[Ti{h5 - C5Me4(p - C6H4F)}{h3:h4 - C5Me2(p - C6H4F)-
(CH2)2}] (2c). Blue crystals, yield 90 mg (19%). M.p.
ꢂCH2); 1.00, 1.01 (2×d,1H, 2JHH=4.5 Hz, AB of
ꢂCH2); 1.06, 1.32 (2×s, 3H, MeꢁC(Ad)); 1.74, 1.75
(2×s, 3H, MeꢁC(Cp)); 1.79 (s, 6H, MeꢁC(Cp)); 2.44,
1
2
123°C. H-NMR: l 0.98, 1.01 (2×d, 1H, JHH=4.4,
ꢂCH2 A); 1.02 (s, 2H, ꢂCH2 B), 1.09, 1.44, 1.57, 1.68,
1.73, 1.92 (6×Me); 6.59–6.96 (m, 8H). 13C{1H}-NMR
(singlets if not stated otherwise): l 10.5 (lH 1.09), 11.4
(lH 1.44), 11.6 (lH 1.57), 12.1 (lH 1.68), 13.0 (lH 1.73),
13.5 (lH 1.92) (6×Me); 71.3 (ꢂCH2 A), 72.7 (ꢂCH2 B),
2
2.69 (2×d, 1H, JHH=15.1 Hz, AB of PhCH2(Ad));
3.55 (s, 2H, PhCH2(Cp)), 7.07–7.53 (m, 10H, Ph).
13C-NMR (all signals singlets):
l
10.18, 10.58
(MeꢁC(Ad)); 11.95, 12.31 (MeꢁC(Cp)); 31.06
(PhCH2(Ad)), 33.26 (PhCH2(Cp)), 68.19, 68.29 (ꢂCH2);
119.74, 119.76, 120.00, 120.02 (MeꢁC(Cp)); 122.59,
123.81 (MeꢁC(Ad) or Cipso(Ph)); 126.16, 126.34
(CH(Ph)); 126.71 (MeꢁC(Ad) or Cipso(Ph)), 128.47,
128.73, 128.75, 128.77 (CH(Ph)); 134.01 (MeꢁC(Ad) or
Cipso(Ph)), 141.59, 142.01 (CH2ꢁC(Cp and Ad)); 144.32,
145.50 (CꢂCH2(Ad)). EI-MS (direct inlet, 70 eV,
145°C): m/z (relative abundance) 470 (16), 469 (41), 468
(100), 467 (16), 466 (17), 454 (12), 453 (30), 259 (9), 258
(15), 254 (5), 253 (9), 252 (7), 181 (6), 180 (5), 179 (6),
178 (8) 91 (5). There is no remarkable difference be-
tween the two isomers in the mass spectra. UV–vis
(hexane, nm): 310(sh)ꢀ610.
An analogous thermolysis of 1b and 1c and the
workup of products afforded blue, poorly crystallizing
compounds 2b and 2c in moderate and low yield re-
spectively. Repeated attempts to isolate other products
from dirty-green hexane mother liquors of the thermol-
ysis failed. Volatiles from thermolytic mixtures con-
2
2
114.8 (d, JFC=21 Hz, C6H4F g-CH), 115.0 (d, JFC
=
22 Hz, C6H4F g-CH), 119.0, 120.1, 120.4, 121.2, 124.2,
126.6, 128.9, 129.3 (CꢁMe, CꢁC6H4F and C6H4F Cipso),
3
3
130.4 (d, JFC=7 Hz, C6H4F b-CH), 131.8 (d, JFC
=
8 Hz, C6H4F b-CH), 142.9, 146.7 (CꢂCH2); 161.6,
161.8 (2×d, JFC=245 Hz, C6H4F a-CH). EI-MS (di-
1
rect inlet, 70 eV, 120°C): m/z (relative abundance) 478
(16), 477 (42), 476 (M+·; 100), 475 (17), 474 (13), 461
([M−Me]+; 8), 260 (9), 259 (8), 258 (7), 165 (7). IR
(KBr) (cm−1): 3053 (w), 3037 (w), 2965 (m), 2940 (m),
2904 (s), 2854 (m), 1877 (vw), 1600 (m), 1509 (vs), 1475
(s), 1445 (m,b), 1404 (w), 1375 (s), 1348 (m), 1293 (w),
1260 (w), 1224 (vs), 1156 (s), 1096 (m), 1026 (s), 1015
(s), 900 (m), 843 (s), 825 (vs), 794 (m), 764 (m), 748 (w),
722 (w), 698 (w), 661 (vw), 620 (w), 589 (s), 580 (m),
560 (m), 520 (sh), 514 (s), 467 (m), 435 (m).
tained
minor
amounts
of
(E)-
and
4.5. Thermolysis of complexes 1a–c in the presence of
(Z)-1,2-bis(trimethylsilyl)ethene in addition to major
BTMSE.
TMOD
[Ti(h5-C5Me4Ph){h3:h4-C5Me2(C6H5)(CH2)2}] (2b).
Compound 1a (0.64 g, 1.0 mmol) was dissolved in
m-xylene (4.0 ml) and the solution was added to de-
gassed TMOD (0.17 g, 1.05 mmol). The resulting mix-
ture was heated in a sealed ampoule to 150°C for 3 h.
The yellow colour of the solution turned turquoise. All
volatiles were distilled off in vacuo and analysed by
Blue crystals, yield 0.15 g (34%). M.p. 124°C. 1H-
2
NMR: l 1.01, 1.05 (2×d, 1H, JHH=4.2, ꢂCH2); 1.07
(d, 1H, 2JHH=4.4, ꢂCH2), 1.13 (Me), 1.16 (d, 1H,
2JHH=4.4, ꢂCH2), 1.54, 1.66, 1.70, 1.85, 1.98 (5×Me);
6.87–7.23 (m, 10H). 13C{1H}-NMR (all signals are

48
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
GC–MS. The solid residue was twice crystallized by
dissolving in warm hexane (15 ml) and allowing the
solution to crystallize overnight; a turquoise crystalline
solid separated from a green mother liquor. The solid
was recrystallized from toluene to give turquoise crys-
tals of 3a as the only isolated product. The volatiles
from the thermolysis contained BTMSE without ad-
mixture of hydrogenated products.
yellowish-green mother liquor. The solid product was
recrystallized from a warm hexane to give blue crystals
of 3b. Yield 0.14 g (23%). M.p. 195°C. 1H-NMR: l
2
0.80, 0.83 (2×s, 9H, Me3C); 0.86 (d, 1H, JHH
=
=
3.9 Hz, ꢂCH2 A), 1.18 (s, 3H, Me), 1.19 (d, 1H, 2JHH
2
3.9 Hz, ꢂCH2 A), 1.20, 1.30 (2×d, 1H, JHH=4.4 Hz,
ꢂCH2 B); 1.67, 1.70, 1.87 (3×s, 3H, Me); 1.90 (dd, 1H,
3JHH=5.5, 2JHH=15.6 Hz, CH2 A), 2.03 (ddd, 1H,
3
[Ti{(h5 - C5Me2(PhCH2)(CH2CH(t - Bu)CHꢂCHCH-
3JHH=4.8, 6.6, 12.8 Hz, CH B), 2.44 (dd, 1H, JHH
=
:
(t-Bu)CH2)}{h3:h4-C5Me3(CH2)(CHPh)}]
(3a).
12.7, JHH=15.6 Hz, CH2 A), 2.83 (dd, 1H, JHH
2
3
Turquoise crystals, yield 0.46 g (73%). M.p. 168°C.
2JHH:13.4 Hz, CH2 B), 2.96 (dd, 1H, 3JHH=4.8,
2JHH=13.8 Hz, CH2 B), 3.03 (ddd, 1H, 3JHH=5.5, 9.6,
12.7 Hz, CH A), 5.52 (dd, 1H, 3JHH=9.6, 12.0 Hz,
CH= B), 5.64 (dd, 1H, 3JHH=6.6, 12.0 Hz, CH= A),
6.92–7.43 (m, 10H, Ph). {13C}1H-NMR: l 10.7 (lH
1.18), 11.9 (lH 1.67), 12.3 (lH 1.70), 13.4 (lH 1.87)
(4×Me); 27.5 (Me3C, lH 0.80), 27.5 (CH2 A), 28.1
(Me3C, lH 0.83), 28.8 (CH2 B), 33.1, 34.7 (2×Me3C);
45.9 (CH A), 53.6 (CH B), 70.8 (ꢂCH2 A), 72.4 (ꢂCH2
B), 120.1, 120.4, 124.2, 124.3, 124.7 (Cipso of Cp, Ad
and Ph rings); 126.4, 126.5, 127.9, 128.3, 128.9
(CH(Ph)); 129.9 (Cipso of Cp, Ad and Ph rings), 130.9
(CH(Ph)); 131.3 (CH= A), 131.6 (CH= B), 133.4,
136.0, 137.3, 142.4, 146.7 (Cipso of Cp, Ad and Ph
rings). One Cipso signal was not observed. EI-MS (direct
inlet, 70 eV, 155°C): m/z (relative abundance) 607 (8),
606 (26), 605 (60), 604 (M+·; 100), 603 (23), 602 (19),
549 (15), 548 (34), 547 ([M−t-Bu]+; 71), 546 (17), 545
(22), 544 (12), 490 (8), 440 (7), 264 (7), 243 (8), 242 (20),
241 (15), 240 (14), 239 (10), 238 (9), 237 (9), 196 (8), 195
(8), 181 (7), 169 (7), 165 (7), 131 (7), 121 (8), 119 (13),
105 (11), 97 (7), 95 (10), 91 (17), 85 (8), 83 (10), 81 (11),
71 (12), 69 (39), 57 (50), 56 (14), 55 (20). IR (KBr,
cm−1): 3080 (vw), 3047 (w), 3008 (w), 2950 (vs), 2903
(m), 2861 (m), 1600 (s), 1573 (vw), 1502 (s), 1473 (s),
1466 (s), 1452 (m), 1433 (m), 1392 (m), 1367 (s), 1259
(m), 1227 (m), 1094 (sh,b), 1072 (m), 1022 (s,b), 940
(vw), 911 (w), 896 (vw), 847 (w), 835 (m), 825 (m), 795
(m), 760 (s), 724 (m), 705 (vs), 647 (vw), 631 (vw), 612
(vw), 576 (w), 500 (w), 440 (m). UV–vis (hexane, nm):
390(sh)ꢀ610.
1H-NMR: l 0.83, 0.86 (2×s, 9H, (CH3)3C); 1.03 (d,
2
1H, JHH=4.7 Hz, ꢂCH2), 1.18 (s, 3H, CH3), 1.20 (d,
2
1H, JHH=4.7 Hz, ꢂCH2), 1.27, 1.39 (2×s, 3H, CH3);
1.63–1.69 (m, 1H, signal overlapped by a methyl reso-
nance), 1.66, 1.74 (2×s, 3H, CH3); 2.22 (dd, 1H,
3JHH=4.8, 2JHH=15.9 Hz, CH2 B), 2.30 (dd, 1H,
3JHH=5.5, 2JHH=13.8 Hz, CH2 A), 2.37 (s, 1H,
ꢂCHPh), 2.61 (dd, 1H, 3JHH=13.0, 2JHH=15.9 Hz,
3
CH2 B), 2.71 (dd, 1H, JHH:2JHH:13.8 Hz, CH2 A),
3
3.01 (ddd, 1H, JHH=4.8, 9.2, 13.0 Hz, CH B), 3.38,
3.47 (2×d, 2JHH=16.7 Hz, PhCH2); 5.50 (dd, 1H,
3
3JHH=6.6, 12.0 Hz, CH= A), 5.56 (dd, 1H, JHH
=
9.2, 12.0 Hz, CH= B), 6.82–7.37 (m, 10H, PhCH2).
{13C}1H-NMR: l 10.4 (lH 1.18), 10.8 (lH 1.27), 10.8
(lH 1.39), 11.6 (lH 1.66), 12.1 (lH 1.74) (5× CH3); 27.6
((CH3)3C, lH 0.86), 27.7 (CH2 A), 28.1 ((CH3)3C, lH
0.83), 29.3 (CH2 B), 32.1 (PhCH2), 34.1, 34.9 (2×
(CH3)3C); 45.4 (CH B), 52.6 (CH A), 81.0 (ꢂCH2),
90.2 (ꢂCHPh), 120.2, 120.8, 122.3, 122.4 (Cipso of Cp,
Ad and Ph rings); 123.0, 123.9 (CH(Ph)); 124.3, 124.4,
125.2 (Cipso of Cp, Ad and Ph rings); 126.2, 127.6,
128.4, 128.5 (CH(Ph)); 130.8 (CH= A), 132.0 (CH=
B), 135.3, 142.4, 143.8,146.4, 147.1 (Cipso of Cp, Ad and
Ph rings). EI-MS (direct inlet, 70 eV, 155°C): m/z (rela-
tive abundance) 636 (10), 635 (15), 634 (37), 633 (57),
632 (M+·; 100), 631 (18), 629 (13), 617 (9), 576 (26),
575 ([M−t-Bu]+; 53), 574 (11), 573 (11), 470 (13), 469
(26), 468 ([M−(TMOD+2H)]+; 55), 467 (11), 466
(10), 454 (7), 453 (16), 258 (20), 257 (20), 256 (8), 254
(11), 252 (24), 251 (15), 250 (8), 249 (10), 180 (12), 179
(9), 178 (10), 177 (13), 91 (15). IR (KBr, cm−-1): 3066
(vw), 3050 (w), 3017 (m), 3000 (m), 2941 (vs), 2898 (s),
2858 (s), 1595 (vs), 1493 (vs), 1456 (s), 1391 (m), 1379
(m), 1363 (s), 1336 (m), 1282 (w), 1260 (w), 1218 (m),
1173 (w), 1153 (vw), 1100 (w), 1072 (m), 1027 (s), 891
(w), 841 (w), 826 (m), 796 (m), 762 (m), 733 (s), 701
(vs), 651 (w), 613 (w), 593 (vw), 580 (m), 520 (m), 461
(w), 433 (m). UV–vis (hexane, nm): 580.
[Ti{(h5-C5Me2FPh)(CH2CH(t-Bu)CHꢂCHCH(t-Bu)-
CH2)}{h3:h4-C5Me2FPh(CH2)2}] (3c). Compound 1c
(0.65 g, 1.0 mmol) and TMOD (0.17 g, 1.05 mmol) in
m-xylene (4.0 ml) were heated to 160°C for 6 h to give
a yellow–green solution. After replacement of all
volatiles by hexane, a small amount of blue crystalline
material separated from a yellowish-green mother
liquor. The solid product was recrystallized from a
warm toluene to give a blue crystalline 3c. Yield 50 mg
(8%). M.p. 195°C. A very poor solubility of the com-
plex in benzene-d6 prevented satisfactory recognition
[Ti{(h5 - C5Me2Ph)(CH2CH(t - Bu)CHꢂCHCH(t - Bu)-
CH2)}{h3:h4-C5Me2Ph(CH2)2}] (3b). In an analogous
experiment, 1b (0.61 g, 1.0 mmol) and TMOD (0.17 g,
1.05 mmol) in m-xylene (4.0 ml) were heated to 150°C
for 3 h and then to 160°C for another 3 h to give a
green solution. After replacement of all volatiles by
hexane, a blue crystalline material separated from a
1
and analysis of all the complex H-NMR resonances.
13C{1H}-NMR: l 10.6, 11.8, 12.1, 13.1 (Me); 27.4, 28.0
(Me3C); 27.5, 28.7 (CH2); 33.1, 34.7 (Me3C); 45.8, 53.6
(CH); 70.8, 72.0 (ꢂCH2); 131.1, 131.6 (CHꢂCH); 115.1,

V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
49
2
114.7 (2×d, JFC=21 Hz, C6H4F g-CH); 130.4, 132.4
(dd, 1H, 3JHH=5.5, 2JHH=14.3 Hz, CH2 A), 3.39
(2×3JFC=7 Hz C6H4F b-CH); 142.2, 146.5 (CꢂCH2);
161.9, 161.9 (2×d, JFC=245 Hz, C6H4F d-CF). Of
the ten resonances due to CꢁMe and Cipso C6H4F, only
four were identified: 119.8, 120.3, 124.3 and 124.9.
UV–vis (hexane, nm): 390(sh)ꢀ610.
(ddd, 1H, JHH=5.4, 9.8, 12.6 Hz, CH B), 3.52 (dd,
3
1
3
1H, JHH:2JHH:14.0 Hz, CH2 B), 4.18 (d, 1H,
2JHH=17.1 Hz, AB of PhCH2), 4.20 (s, 2H, PhCH2),
2
4.25 (d, 1H, JHH=17.1 Hz, AB of PhCH2), 5.35 (dd,
3
3JHH=7.0, 11.8, ꢂCH A), 5.46 (dd, JHH=9.8, 11.8,
ꢂCH B), 6.91–7.24 (m, 10H, PhCH2). 13C{1H}-NMR:
l 12.7 (lH 1.88), 13.0 (lH 1.96), 13.6 (lH 2.06), 13.8 (lH
2.09) (4×Me); 27.3 (Me3C), 27.6 (lH 1.07, Me3C), 27.8
(Me3C), 28.1 (lH 0.91, Me3C), 29.8 (CH2 A), 30.1 (CH2
B), 34.0 (PhCH2, lH 4.20), 34.4 (PhCH2, lH 4.18 and
4.25), 45.3 (CH B), 51.5 (CH A), 124.5 (Cp and Ph;
Cipso), 126.2 (2C), 128.3, 128.4, 128.5, 128.7 (Ph, CH);
129.3, 129.4, 130.2, 130.7 (Cp and Ph; Cipso); 131.0
(CH= A), 131.4 (CH= B), 131.7, 132.3, 136.0, 140.7,
141.4 (Cp and Ph; Cipso). EI-MS (direct inlet, 70 eV,
155°C): m/z (relative abundance) 704 (M+·; not ob-
served), 671 (15), 670 (31), 669 (M−Cl]+; 64), 505
(11), 495 (19), 493 ([M−Cp]+; 21), 458 ([M−Cp−
Cl]+; 16), 403 (12), 401 ([M−Cp−Cl−t-Bu]+; 26),
330 (21), 329 ([M−CpTMOD]+; 38), 328 (19), 296 (38),
295 (34), 294 ([M−CpTMOD−Cl]+; 100), 293 (30), 292
(15), 212 (20), 211 (42), 210 (21), 209 (17), 119 (51), 91
(76). IR (KBr, cm−1): 3098 (vw), 3075 (w), 3052 (w),
3016 (m), 2998 (m), 2944 (vs), 2897 (s), 2858 (s), 1600
(s), 1580 (w), 1494 (vs), 1474 (s), 1460 (sh), 1450 (vs),
1432 (sh), 1392 (s), 1375 (sh), 1364 (vs), 1283 (w), 1227
4.6. Reaction of 3a with HCl to gi6e 4a
To a turquoise solution of 3a (0.27 g, 0.42 mmol) in
hexane (30 ml) was admitted excess gaseous HCl
[evolved from degassed NaCl (0.10 g, 1.7 mmol) and
H2SO4 (98%, 5.0 ml)]. The colour turned immediately
to red and a brown–red solid precipitated on the walls
of the reaction ampoule. After shaking for 1 h, unre-
acted HCl and about half of the hexane volume were
distilled off and the remaining mixture was put into
refrigerator overnight. A light-red solution was poured
away; the solid was dried in vacuum and dissolved in
toluene (10 ml).
[TiCl2{h5-C5Me2Bz(CH2CH(t-Bu)CHꢂCHCH(t-Bu)-
CH2)}(h5-C5Me4Bz)] (4a). Yield 0.27 g (92%). M.p.
1
180°C. H-NMR: l 0.91, 1.07 (2×s, 9H, Me3C); 1.88
(s, 3H, Me), 1.96 (s, 6H, Me), 2.06 (s, 3H, Me), 2.09 (s,
3
6H, Me), 1.67 (ddd, 1 H, JHH=5.5, 7.0, 13.6 Hz, CH
3
2
A), 2.46 (dd, 1H, JHH=12.6, JHH=15.8 Hz, CH2 B),
3
2
3.02 (dd, 1H, JHH=5.4, JHH=15.8 Hz, CH2 B), 3.05
Table 6
Crystallographic data, data collection and structure refinement for 1c, 2a, 2b and 3ba
1c
2a
2b
3b
Chemical formula
Molecular weight
Crystal system
Space group
C38H50F2Si2Ti
648.87
C32H36Ti
468.52
Triclinic
C30H32Ti
440.46
C42H52Ti
604.76
Triclinic
Monoclinic
P21/n (no. 14)
17.4380(4)
12.9870(4)
17.7950(4)
90.0
116.5790(15)
90.0
3604.09(16)
4
Monoclinic
P21/n (no. 14)
8.7274(14)
28.153(3)
9.7255(12)
90.0
90.977(15)
90.0
2389.2(5)
4
(
(
P1 (no. 2)
P1 (no. 2)
,
a (A)
8.702(2)
10.9192(11)
11.8159(13)
14.9834(14)
81.210(12)
87.733(12)
64.220(11)
1719.5(3)
2
,
b (A)
11.580(4)
15.055(3)
91.07(3)
99.549(19)
103.53(4)
1451.9(7)
2
,
c (A)
h (°)
b (°)
g (°)
3
,
V (A )
Z
Dcalc (g cm−3
)
1.196
0.339
1.170
0.315
1.224
0.372
1.168
0.276
v (mm−1
)
Crystal description
Crystal size (mm3)
q range (°)
Yellow prism
0.5×0.4×0.3
2.02–27.49
0/22; 0/16; −23/20
8183
Turquoise prism
0.7×0.6×0.2
3.01–25.01
−10/10; −13/13; 0/17
5482
Blue prism
0.8×0.2×0.1
2.22–25.84
−10/9; −34/34; −11/11
17 010
Blue prism
0.46×0.38×0.19
1.94–26.00
−13/13; −14/14; −18/18
9002
hkl range
Diffractions collected
Unique diffractions
F(000)
8183
1384
5096
550
4341
936
4570
652
Number of parameters
R(F); wR(F2) (%)
GOF (F2) all data
588
6.94; 14.99
1.131
4.85; 12.73
0.303; −0.291
329
9.85; 16.78
1.193
6.22; 14.34
0.277; −0.255
280
7.63; 13.94
1.027
5.07; 12.88
0.673; −0.571
412
11.36; 10.03
0.853
4.93; 8.62
0.244; −0.205
R(F); wR(F2) [I\2|(I)]
Dz (e−
)
−3
,
A
a Definitions: R(F)=S ꢀFoꢁ−ꢁFcꢀ/S ꢁFoꢁ, wR(F2)={S [w(F2o−Fc2)2]/[S w(F2o)2]}1/2, GOF={S [w(Fo2−Fc2)2]/(Ndiffrs−Nparams)}1/2
.

50
V. Kupfer et al. / Journal of Organometallic Chemistry 620 (2001) 39–50
(m), 1176 (vw), 1151 (vw), 1107 (vw), 1073 (w), 1029
(s), 1017 (m), 820 (vw), 793 (m), 750 (sh), 732 (s), 699
(vs), 676 (w), 460 (m).
References
[1] (a) N.J. Long, Metallocenes, Blackwell, Oxford, UK, 1998. (b)
R. Beckhaus, in: A. Togni, R.L. Halterman (Eds.), Metallocenes,
vol. 1, Wiley–VCH, Weinheim, Germany, 1998, Ch. 4, p. 153.
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4.7. Crystal structure determination
Fragments of crystals of 1c, 2a, 2b and 3b were fixed
in Lindemann glass capillaries under purified nitrogen
in a glovebox and closed with a sealing wax. The X-ray
measurements were carried out at room temperature.
Diffraction data for 1c were collected on an Enraf–No-
nius CAD-4 MACH III diffractometer, those for 2a
were collected on a Philips PW1100 four-circle diffrac-
tometer upgraded by STOE, and those for 2b and 3b on
a STOE IPDS Imaging Plate System at room tempera-
ture using graphite-monochromated Mo–Ka radiation
&
&
,
(u=0.710 73 A). The structures of 1c, 2a and 2b were
solved by direct methods [25] and that of 3b by the
Patterson method [26]. The structures were refined by
full-matrix least-squares methods based on F2 using a
variance-based weighting scheme in the final stages [27].
The non-hydrogen atoms were refined anisotropically.
All hydrogen atoms in 1c, at C(2) in 2a, and at C(19),
C(20), C(33) and C(35) in 3b were determined from
difference Fourier maps and were refined isotropically.
All other hydrogen atoms were included at their calcu-
lated positions and refined isotropically. Compound 2a
contained one molecule of n-hexane of crystallization in
the unit cell located on the inversion centre. Crystal
data, details of data collection and refinement are given
in Table 6.
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&
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&
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5. Supplementary material
Crystallographic data, excluding structure factors,
have been deposited at the Cambridge Crystallographic
Data Centre as supplementary publication nos CCDC-
147448 (1c), CCDC-144792 (2a), CCDC-144793 (2b),
and CCDC-144794 (3b). Copies of the data can be
obtained free of charge on application to The Director,
CCDC, Union Road, Cambridge CD12 1EZ, UK (fax:
+44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk).
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&
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[27] G.M. Sheldrick, SHELXS97, Program for Crystal Structure Deter-
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Structures, University of Go¨ttingen, Germany, 1997.
Acknowledgements
This work was supported by the Grant Agency of the
Czech Republic (project no. 203/99/0846), by the Coun-
cil for Research and Development of Academy of Sci-
ences of the Czech Republic (project no. S4040017),
and by Volkswagen Stiftung.