Synthesis and crystal structures of dimethylsilylene-bridged (amidocyclopentadienyl)dichlorotitanium(IV) complexes with various substituents on the cyclopentadienyl ligand

Article abstract of DOI:10.1135/cccc20010605

(Amidocyclopentadienyl)dichlorotitanium(IV) complexes of the general formula [TiCl₂[η⁵:η¹(N)-C₅(1-SiMe₂Nt-Bu-2,3,4-Me₃-5-R)]], where R = H (6b), Ph (6c), 4-fluorophenyl (6d) and 1-methylallyl (6e) were synthesized and characterized by spectral methods. Solid-state structure of [TiCl₂{η⁵:η¹(N)-C₅Me₄(SiMe₂Nt-Bu)}] (6a) and 6d determined by single-crystal X-ray diffraction showed that variation of the ring substituent R has only a negligible effect on the molecular structure of the complexes. The NMR spectra indicate that motion of the bulky substituent R in compounds 6c, 6d and 6e is hindered below ca 50°C.

Full text of DOI:10.1135/cccc20010605

(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
605
SYNTHESIS AND CRYSTAL STRUCTURES OF DIMETHYLSILYLENE-
BRIDGED (AMIDOCYCLOPENTADIENYL)DICHLOROTITANIUM(IV)
COMPLEXES WITH VARIOUS SUBSTITUENTS ON THE
CYCLOPENTADIENYL LIGAND
a
b3
Jaroslav ZEMÁNEK , Petr ŠTĚPNIČKAb1, Karla FEJFAROVÁb2, Róbert GYEPES
,
Ivana CÍSAŘOVÁb4, Michal HORÁČEKa1, Jiří KUBIŠTAa2, Vojtech VARGA
c
a3,
and Karel MACH
*
a
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic,
Dolejškova 3, 182 23 Prague 8, Czech Republic; e-mail: horacek@jh-inst.cas.cz,
kubista@jh-inst.cas.cz, mach@jh-inst.cas.cz
Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2,
Czech Republic; e-mail: stepnic@natur.cuni.cz, fejfar@natur.cuni.cz,
gyepes@natur.cuni.cz, cisarova@natur.cuni.cz
Research Institute of Inorganic Chemistry, 400 01 Ústí nadLabem, Czech Republic;
e-mail: vojtech.varga@vuanch.cz
1
2
3
b
c
1
2
3
4
Received March 9, 2001
Accepted April 12, 2001
(Am idocyclopen tadien yl)dich lorotitan ium (IV) com plexes of th e gen eral form ula
[TiCl2{η5:η1(N)-C5(1-SiMe2Nt-Bu-2,3,4-Me3-5-R)}], wh ere R = H (6b), Ph (6c), 4-fluoroph en yl
(6d ) an d 1-m eth ylallyl (6e) were syn th esized an d ch aracterized by spectral m eth ods.
Solid-state structure of [TiCl2{η5:η1(N)-C5Me4(SiMe2Nt-Bu)}] (6a) an d 6d determ in ed by
sin gle-crystal X-ray diffraction sh owed th at variation of th e rin g substituen t R h as on ly a
n egligible effect on th e m olecular structure of th e com plexes. Th e NMR spectra in dicate th at
m otion of th e bulky substituen t R in com poun ds 6c, 6d an d 6e is h in dered below ca 50 °C.
Keyw ord s: Titan ium ; Half-san dwich com plexes; Cyclopen tadien yl ligan ds; (Am idocyclo-
pen tadien yl)dich lorotitan ium (IV) com plexes; Substituen t effects; X-Ray diffraction ; NMR
spectroscopy; Alken e polym erization catalysts.
An in troduction of (tert-butylam ido)dim eth yl(2,3,4,5-tetram eth ylcyclo-
pen tadien yl)silan e as th e η5:η1(N)-dian ion ic ligan d in th e syn th esis of
ansa-(η5:η1(N)-((tert-butylam ido)dim eth yl(2,3,4,5-tetram eth ylcyclopen ta-
dien yl)silan e))ch loroscan dium (III)1 resulted in discovery of a n ew class of
alken e polym erization catalysts called “con strain ed geom etry catalysts”
(CGC)2,3. Active sin gle-site catalysts form ed from th ese ansa-am idocyclo-
pen tadien yl com plexes in th e presen ce of excess m eth ylalum oxan e (MAO)
offer an altern ative to th e well-kn own group 4 m etallocen e catalysts by pro-
Collect. Czech. Chem. Commun. (Vol. 66) (2001)
doi: 10.1135/cccc20010605

606
Zemánek et al.:
vidin g gen erally m ore acidic an d less sterically en cum bered cation ic cen-
tres4 th at display very h igh activities especially in th e copolym erization of
eth en e with term in al alken es5, cycloalken es6 an d styren e7, wh ere both th e
tradition al Ziegler–Natta m ulti-site an d m etallocen e-based sin gle-site cata-
lysts are in effective. Particularly, catalysts based on an arch etypal tita-
n ium (IV) com plex [TiCl2{η5:η1(N)-C5Me4(SiMe2Nt-Bu)}]8 (6a) sh owed
in dustrially explorable properties9. An alogous titan ium com plexes with
un substituted cyclopen tadien yl- (refs9b,10), in den yl- (ref.11) or fluoren yl-
am idosilan e ligan ds11, h owever, were foun d to be precursors of poorer cata-
lyst th an is 6a (refs2–4,12). Sim ilarly, replacem en t of tert-butyl substituen t on
th e am ido n itrogen atom by Me, i-Pr, CH2Ph , CHMePh , cycloh exyl,
1-adam an tyl or cyclododecyl group4,13 as well as attach m en t of a furth er
teth er bearin g n itrogen or oxygen don or atom 14 did n ot im prove th e cata-
lyst perform an ce. On th e oth er h an d, a replacem en t of th e bridgin g
dim eth ylsilylen e group by eth an e-1,2-diyl lin k in th e CGC-type polym er-
ization catalyst precursors suppresses th e catalyst activity towards propen e
wh ile sligh tly en h an cin g th at towards eth en e15
.
To th e best of our kn owledge, a fin e tun in g of properties of th e catalytic
cen tre derived from com poun d 6a by ch an gin g a sin gle substiuen t on oth -
erwise fully m eth ylated cyclopen tadien yl ligan d h as n ot yet been at-
tem pted. Hen ce, in th is work we report th e syn th esis of an alogues of
com plex 6a bearin g various substituen ts in th e position adjacen t to th e
dim eth ylsilylen e bridge.
RESULTS AND DISCUSSION
Synthesis and Spectroscopy
Syn th esis of (am idocyclopen tadien yl)dich lorotitan ium (IV) com plexes
[TiCl2{η5:η1(N)-C5(1-SiMe2NCMe3-2,3,4-Me3-5-R)}] largely follows th e gen -
eral procedure described for th e syn th esis of com plex 6a (R = Me,
Sch em e 1)9b. Th e startin g trim eth ylcyclopen tadien es C5H2Me3R (R = H, Ph ,
4-fluoroph en yl an d CH(Me)CH=CH2) were obtain ed by iodin e-catalyzed de-
h ydration of alcoh ols syn th esized from 2,3,4-trim eth ylcyclopen t-2-en -
1-on e an d th e appropriate R– source (LiAlH4 for 6b an d th e correspon din g
Grign ard reagen ts for 6c–6e)16. Th e cyclopen tadien es C5H2Me3R were
deproton ated by on e equivalen t of BuLi an d th e form ed m on oan ion s (1)
were reacted with on e equivalen t of dich lorodim eth ylsilan e to give th e cor-
respon din g ch loro(cyclopen tadien yl)dim eth ylsilan es (C5HMe3R)SiMe2Cl
(2). Th e latter were added directly to on e equivalen t of lith ium tert-butyl-
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
607
am ide (prepared by m ixin g stoich iom etric am oun ts of tert-butylam in e an d
BuLi) sin ce th is protocol proved to be less tim e con sum in g th an th e gen er-
ally used refluxin g of th e silan es with an excess of tert-butylam in e9b. Th e re-
sultin g cyclopen tadien yl(tert-butylam in o)dim eth ylsilan es (3) were isolated
R
R
R
H
H
(i)
(ii)
H
Li+
Si
Si
Cl
N
H
1a-1e
2a-2e
3a-3e
(iii)
R
R
R
(v)
(iv)
Si
Si
-
2Li+
Si N( )
Cl
Cl
Ti
Cl
Ti
N
N
4a-4e
6a-6e
5a-5e
R
1-6
a
Me
H
(i) Me2SiCl2, THF
(ii) LiNHCMe3, Et2O
b
Ph
c
(iii) 2 BuLi, THF-hexane
(iv) [TiCl3(THF)3], THF
(v) 1/2 PbCl2, THF
4-FC6H4
d
CH(Me)CH=CH2
e
SCHEME 1
as yellow fluorescen t oily liquids by h exan e extraction in th e absen ce of air
(rem oval of LiCl), evaporation of th e extracts an d distillation of th e resi-
dues in vacuum . Th e silan es 3 were furth er con verted to dian ion s by react-
in g with 2 equivalen ts of BuLi an d th e obtain ed lith ium salts 4 were m ixed
with a slurry of on e equivalen t [TiCl3(THF)3] in THF. After refluxin g for 6 h ,
on e h alf of m olar equivalen t of PbCl2 was added17 to oxidize a titan ium (III)
in term ediates 5. Th ereupon th e in itially green reaction m ixtures turn ed yel-
low (after 3 h at room tem perature) an d black m etallic lead deposited at th e
bottom of reaction vessels. Th e solven ts were evaporated in vacuo an d th e
residues were extracted with dry h exan e. After evaporation , th e extracted
products were sublim ed in vacuo at tem perature in creasin g up to 210 °C.
Fin ally, th e (am idocyclopen tadien yl)dich lorotitan ium com plexes 6b–6e
Collect. Czech. Chem. Commun. (Vol. 66) (2001)

608
Zemánek et al.:
were separated from organ ic byproducts by crystallization from h exan e.
Pure titan ium (IV) com plexes were th us obtain ed as in ten se yellow crystal-
lin e m aterials in yields n ot exceedin g 19%. Th e paren t com poun d of th is
series, com plex 6a was also syn th esized by th is procedure as th e referen ce.
1
Com poun ds 6a–6e were ch aracterized by H an d 13C NMR, m ass an d IR
spectra. Th e NMR spectra of 6b–6e are un exception al, differin g from th e
spectra of 6a m ain ly by sign als of th e substituen ts R. More in terestin gly,
com poun ds with bulky arom atic substituen ts 6c an d 6d exh ibit broad reso-
n an ces due to th e substituen t R (Ph or 4-C6H4F) in both 1H an d 13C NMR
1
spectra. As in dicated by a variable tem perature H NMR study, th e broaden -
in g results from a h in dered m otion of th ese substituen ts (Fig. 1). At room
tem perature an d in ben zen e-d6 solution , a m ovem en t of th e ph en yl group
in 6c is slow on th e NMR tim e scale an d results in a separation of ph en yl
reson an ces so th at th ey con sist of a sh arp m ultiplet (3 H) an d two well sep-
1
arated broad sign als (2 × 1 H). Exam in ation of H NMR spectra in a tem per-
ature ran ge of 0–60 °C sh owed th e coalescen ce tem perature of th is two-site
exch an ge to be ca 45 °C.
Sim ilarly to its n on -fluorin ated an alogue, com plex 6d exh ibits in its NMR
spectra a typical two-site exch an ge of th e arom atic CH groups adjacen t to
th e cyclopen tadien yl rin g with coalescen ce tem perature of ca 45 °C. Upon
lowerin g tem perature to 0 °C, furth er sign als of th e 4-fluoroph en yl
substituen t, wh ich are well-resolved at room tem perature, becom e broad.
It appears likely th at a m otion of th e 1-m eth ylallyl substituen t in 6e is
h in dered as well sin ce th is com poun d features un resolved broad reson an ces
due to th e CH(Me)CH=CH2 m oiety in 1H NMR spectra. However, as th e
com plex 6e is obtain ed as a m ixture of two diastereisom ers, th e observed
broaden in g of NMR sign als m ay be also attributed to overlappin g of two
sign als sets.
Mass spectra of com plexes 6a–6e display on ly poorly abun dan t m olecular
ion s wh ich fragm en t by a loss of on e m eth yl group with subsequen t elim i-
n ation of t-Bu group (6c–6e) or by an elim in ation of 2-m eth ylpropen e (6a
an d 6b). In in frared spectra of th e CGC com plexes, typical absorption
ban ds of th e ph en yl an d 4-fluoroph en yl groups at 1 600 cm –1 an d in th e re-
gion 3 000–3 100 cm –1 as well as th e ν(C=C) ban d of th e 1-m eth ylallyl
group at 1 640 cm –1 are well observable. Th e com m on fram ework of th e
com plexes gives rise to stron g sin gle ban ds at 984 ± 4 an d 1 181 ± 3 cm –1
wh ose position s are virtually in depen den t of th e substituen ts R on th e
cyclopen tadien yl rin g. On th e oth er h an d, th e ban ds due to th e dim eth yl-
silylen e group are in fluen ced by th e varyin g substituen ts: com poun ds
6c–6e sh ow a ban d at 850 ± 1 cm –1 an d doublets 1 258/1 262 cm –1 for 6c,
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
609
Collect. Czech. Chem. Commun. (Vol. 66) (2001)

610
Zemánek et al.:
1 251/1 260 cm –1 for 6d an d 1 252/1 259 cm –1 for 6e, wh ile com plexes 6a
an d 6b exh ibit on ly sin gle ban ds at 841 an d 1 253 cm –1, an d at 838 an d
1 255 cm –1, respectively. Th e splittin g of th e ban d at 1 250–1 260 cm –1 in
in frared spectra of 6c–6e can be related to a steric h in dran ce im posed by
th e bulky substituen ts R wh ose h in dered rotation h as been establish ed by
NMR spectroscopy (vide supra).
Structures of com poun ds 6a an d 6d were determ in ed by X-ray diffraction
of sin gle crystals. We h ave redeterm in ed th e crystal structure of 6a because
th e data reported previously are accessible on ly with difficulty8,10c
.
Crystal Structures of 6a and 6d
Molecular structure 6a is largely dictated by th e sym m etry of un it cell sin ce
th e m olecule is located so th at a crystallograph ic m irror plan e passes th e Ti,
C1, Si, N, C7 an d C9 atom s (Fig. 2). Th e m olecule of 4-fluoroph en yl deriva-
tive 6d (Fig. 3) sh ows plan ar ch irality due to th e presen ce of th e n on -
m eth yl substituen t on th e cyclopen tadien yl rin g. Hen ce, th e racem ic un it
cell con sists of two pairs of en an tiom eric m olecules. Th e bon d len gth s an d
an gles for 6a an d 6d (Table I) in dicate th at th e 4-fluoroph en yl substituen t
h as alm ost n o effect on th e geom etry of th e m olecular skeleton . Th e bite
an gles N–Ti–Cg (Cg den otes cen troid of th e cyclopen tadien yl rin g) in 6a
FIG. 2
Structure of com poun d 6a drawn at th e 30% probability level with th e atom labellin g
sch em e. All h ydrogen atom s are om itted for clarity
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
611
(107.8(2)°) an d 6d (107.6(2)°) do n ot differ with in th e precision of m easure-
m en t an d th eir values are on ly sligh tly larger th an th e bite an gle in
[TiCl2{η5:η1(N)-C5H4(SiMe2Nt-Bu)}] (107.0°)10c. Sim ilarly, oth er skeletal an -
gles, N–Si–C1 an d Si-N–Ti, are virtually equal in both com poun ds. Th e
asym m etry in duced by th e 4-fluoroph en yl substituen t results in a sligh t ro-
tation of th e η5-cyclopen tadien yl ligan d from an arran gem en t perpen dicu-
lar to a plan e defin ed by Ti, N an d Si atom s. Th e correspon din g dih edral
an gle is 86.9(2)°, th e side bearin g th e arom atic substituen t bein g m ore dis-
tan t from th e titan ium atom . Th e least-squares 4-fluoroph en yl an d cyclo-
pen tadien yl plan es subten d an an gle 52.7(2)° an d th e arom atic group is
disposed out of th e latter plan e: th e C15 ipso-carbon atom is sh ifted
0.200(7) Å from th e cyclopen tadien yl-rin g plan e away from th e titan ium
cen tre. Th e asym m etry of 6d is also m an ifested by dih edral an gles between
th e Ti, Cl1, Cl1′ an d Ti, Cl1, Cl2 plan es, respectively, an d th e least-squares
cyclopen tadien yl plan e: 47.8(1)° for 6a an d 52.7(2)° for 6d . Sim ilarly, th e
an gle between th e Ti, Cl1, Cl2 an d Ti, N, Si plan es in 6d (88.4(1)°) differs
sligh tly from th e perpen dicular an gle in com poun d 6a wh ich reflects crys-
tallograph ic sym m etry.
FIG. 3
Structure of com poun d 6d drawn at th e 30% probability level sh owin g th e atom labellin g
sch em e. All h ydrogen atom s are om itted for clarity
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612
Zemánek et al.:
Th ese results sh ow th at th e substituen ts on th e cyclopen tadien yl rin g do
n ot affect th e skeleton of th e studied CGC com plexes, particularly th e m ag-
n itude of th e N–Ti–Cg bite an gle wh ich is believed to determ in e polym er-
ization activity of th e catalysts prepared th ereof9b. Th e m agn itude of th e
bite an gle is som ewh at m ore affected by substituen ts on th e n itrogen atom s
as th eir stereoelectron ic effect in stan tly in fluen ces th e Ti–N bon d3,9b
.
TABLE I
Selected bon d len gth s (in Å) an d an gles (in °) for com plexes 6a an d 6d
Atom s
6a
6d
Len gth s
Ti–C1
Ti–C2
Ti–C3
Ti–C4
Ti–C5
Ti–Cga
Crin g–Crin g
Ti–N
2.264(4)
2.329(3)
2.445(3)
–
2.284(4)
2.373(4)
2.452(4)
2.425(4)
2.316(4)
2.040(4)
–
2.033(3)
1.405–1.430(4)
1.910(4)
1.745(4)
1.866(4)
2.265(1)
–
1.409–1.432(6)
1.910(3)
Si–N
1.744(4)
Si–C1
1.875(4)
Ti–Cl1
Ti–Cl2
2.269(2)
2.274(2)
An gles
Cg–Ti–N
107.8(2)
114.55
107.6(2)
Cg–Ti–Cl1
Cg–Ti–Cl2
Cl1–Ti–Cl1′(Cl2)b
N–Si–C1
115.94
–
114.87
103.17(8)
90.4(2)
100.68(6)
90.8(2)
105.6(2)
Si–N–Ti
105.3(2)
a
b
Cen troid of th e C1-C5 cyclopen tadien yl rin g. Position of th e Cl1′ atom is gen erated by
th e (x, 1/2 + y, z) sym m etry operation .
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
613
EXPERIMENTAL
Gen eral Com m en ts
Syn th eses of cyclopen tadien es from keton es an d LiAlH4 or Grign ard reagen ts were per-
form ed un der n itrogen ; th e reaction s of lith ium cyclopen tadien ides or lith ium tert-butyl-
am ide were carried out in argon atm osph ere. All m an ipulation s with th e (am idocyclo-
pen tadien yl)titan ium com plexes were carried out on a h igh vacuum -argon lin e operated by
glass-to-m etal sealed valves (Hoke) in all-sealed glass devices equipped with breakable seals.
NMR sam ples were prepared in evacuated all-glass devices from wh ich th e NMR tubes were
sealed off by flam e. Th e adjustm en t of sin gle crystals in to Lin dem an n glass capillaries for
X-ray an alyses as well as th e preparation of sam ples for IR an d MS m easurem en ts was m ade
un der n itrogen in a glovebox (m Braun , O2 an d H2O con cen tration s lower th an 2.0 ppm ).
In frared spectra of sam ples in KBr pellets were recorded on a Specord IR-75 spectrom eter
(Carl Zeiss, Jen a, Germ an y) in a closed cell un der n itrogen (waven um bers in cm –1). 1H
(399.95 MHz) an d 13C (100.58 MHz) NMR spectra were m easured on a Varian UNITY In ova
400 spectrom eter in C6D6 solution s at 298 K. Ch em ical sh ifts (δ, ppm ) are given relative to
th e solven t sign al (δH 7.15, δC 128.0). Couplin g con stan ts (J) are given in Hz. Mass spectra
were m easured on a VG 7070E spectrom eter at 70 eV usin g a direct in let probe (sam ples in
sealed capillaries were open ed an d in serted in to th e probe in an argon flow). GC an alyses
were perform ed on a CHROM 5 gas ch rom atograph (Laboratory In strum en ts, Prague, Czech
Republic) equipped with a 10% SE-30/Ch rom aton N-AW-DMCS colum n . GC-MS an alyses
were carried out on a Hewlett–Packard gas ch rom atograph (5890 series II; capillary colum n
SPB-1 (Supelco)) in terfaced to a m ass spectrom etric detector (5791 A). Meltin g poin ts were de-
term in ed for sam ples in n itrogen -filled sealed capillaries on a Kofler apparatus an d are un -
corrected.
Dieth yl eth er an d tetrah ydrofuran (THF) used for th e syn th esis of (tert-butylam in o)-
(cyclopen tadien yl)dim eth ylsilan es were dried by refluxin g over LiAlH4 in argon atm osph ere.
THF an d h exan e for th e syn th esis an d purification of (am idocyclopen tadien yl)titan ium com -
plexes were refluxed with LiAlH4 in argon atm osph ere, carefully degassed an d stored as solu-
tion s of green dim eric titan ocen e [(µ-η5:η5-C10H8){(η5-C5H5)Ti(µ-H)} ] (ref.18) on a vacuum
2
lin e. C6D6 for NMR spectroscopy was degassed an d stored as a solution of green dim eric
titan ocen e on a vacuum lin e.
Th e startin g trim eth ylcyclopen tadien es were obtain ed from 2,3,4-trim eth ylcyclopen t-
2-en -1-on e by reduction with LiAlH4 (refs16,19) or, in th e case of C5Me3RH2 derivatives (R =
Ph , 4-fluoroph en yl an d CH(Me)CH=CH2), from alkylation with correspon din g Grign ard re-
agen ts, an d subsequen t iodin e-catalyzed deh ydration of th e resultin g alcoh ols16. Th is proce-
dure is an alogous to th e syn th esis of C5Me4RH, wh ere R = Ph (ref.20), 4-fluoroph en yl (ref.21
)
or CH(Me)CH=CH2 (ref.22). Titan ium tetrach loride (In tern ation al En zym es) was degassed,
refluxed over copper turn in gs, an d distilled in vacuo in to am poules. Crude [TiCl3(THF)3] was
obtain ed by reduction of TiCl4 with equim olar am oun t of BuLi in THF (ref.23). Lead
dich loride (powder, Aldrich ) was h eated to 100 °C in vacuo an d th en stored un der argon .
Butyllith ium (1.6 M solution in h exan es), tert-butylam in e, brom oben zen e, 4-fluorobrom o-
ben zen e an d dich lorodim eth ylsilan e (all Aldrich ) were used as received.
Collect. Czech. Chem. Commun. (Vol. 66) (2001)

614
Zemánek et al.:
Syn th esis of {η5:η1(N)-1-[(tert-Butylam ido)dim eth ylsilyl)]-2,3,4-trim eth yl-
cyclopen tadien yl}dich lorotitan ium (IV) (6b)
Butyllith ium (31.3 m l 1.6 m ol l–1, 50.0 m m ol) was added to a stirred solution of isom eric
1,2,3-trim eth ylcyclopen tadien es19 (5.4 g, 50.0 m m ol) in THF (300 m l) in a th ree-n ecked
flask equipped with a m agn etic stirrin g bar an d a reflux con den ser. A volum in ous wh ite
precipitate of lith ium cyclopen tadien ide, wh ich separated im m ediately, was stirred at
room tem perature for 2 h . Th en , it was treated with n eat dich lorodim eth ylsilan e (6.3 m l,
52.0 m m ol) an d th e reaction m ixture was refluxed for 1 h . Th e reaction volum e was reduced
to ca 20 m l by distillation at n orm al pressure an d th e rem ain in g volatiles were distilled off
at room tem perature in oil-pum p vacuum . Fin ally, ch lorodim eth yl(1,2,3-trim eth ylcyclo-
pen ta-1,3-dien -5-yl)silan e (2b) was obtain ed by distillation from boilin g water bath at 15 Pa
as a yellowish liquid (8.5 g, 85%). Th is product was stored un der argon prior to use.
Sim ultan eously, BuLi (26.0 m l of 1.6 M solution in h exan e, 42.0 m m ol) was slowly added
to a vigorously stirred solution of tert-butylam in e (4.7 m l, 42.0 m m ol) in dry THF (200 m l)
in a th ree-n ecked flask equipped with a m agn etic stirrin g bar an d a reflux con den ser. Th e
colourless solution was stirred at room tem perature for 2 h an d th e ch lorosilan e 2b (8.5 g,
42.3 m m ol) was slowly in troduced. A wh ite precipitate slowly form ed overn igh t. Most of
THF was distilled off an d h exan e (50 m l) was added to th e rem ain in g 20 m l of th e reaction
m ixture. Th e solution was separated from th e precipitated LiCl an d th e extraction was re-
peated by an oth er 50 m l of h exan e. Com bin ed h exan e extracts were evaporated at reduced
pressure on a rotary evaporator an d th e rem ain in g liquid was distilled at 10 Pa from boilin g
water bath to provide silan e 3b as a yellow viscous liquid sh owin g green fluorescen ce. Yield
8.7 g (88%). GC-MS, m/z (relative abun dan ce): 237 (M• +, 12), 222 ([M – Me]+, 6), 165 (13),
131 (18), 130 ([Me2SiNH(t-Bu)]+, 100), 114 (32), 105 (11), 100 (12), 93 (14), 91 (41), 79 (13),
77 (15), 75 (12), 74 (82), 73 (71), 59 (26), 58 (33), 41 (26). IR (n eat): 3 043 (w), 2 953 (vs),
2 924 (sh ), 2 900 (s), 2 854 (s), 1 612 (w), 1 533 (w), 1 460 (m ), 1 440 (m ), 1 393 (m ), 1 373
(vs), 1 357 (s), 1 247 (vs), 1 223 (vs), 1 148 (w), 1 120 (m ), 1 090 (w), 1 014 (vs), 977 (s), 937
(m ), 896 (w), 847 (vs), 824 (vs), 767 (s), 720 (w), 687 (w), 673 (w), 637 (w), 540 (w), 500 (m ),
483 (m ), 450 (w).
In th e n ext step, th e silan e 3b (8.5 g, 36.0 m m ol) was dissolved in THF (300 m l), BuLi
(45.0 m l of 1.6 M solution in h exan es, 72.0 m m ol) was added with stirrin g an d th e resultin g
yellow solution was stirred for 2 h . A suspen sion of [TiCl3(THF)3] (prepared from TiCl4
(4.0 m l, 36.0 m m ol) an d BuLi (22.5 m l 1.6 m ol l–1, 36.0 m m ol)) was added to th e solution
of th e lith ium salt an d th e m ixture was refluxed for 8 h . Th e solven ts were distilled off to
reduce th e reaction volum e to about 50 m l an d, after coolin g to room tem perature, dry
PbCl2 (5.0 g, 18.0 m m ol) was added in to th e reaction m ixture an d stirrin g was con tin ued at
40 °C for 2 h . Th e reaction vessel was th en attach ed to a vacuum -argon lin e un der argon
wh ere th e rem ain in g volatiles were rem oved in vacuum an d th e reaction products were ex-
tracted in to h exan e (100 m l portion s; h exan e was added by distillation on th e vacuum -
argon lin e). Com bin ed brown extracts were con cen trated to approxim ately 30 m l an d dis-
tributed in to 3 am poules, wh ose con ten ts were distilled on a h igh -vacuum lin e. Th e
volatiles distillin g up to 70 °C were collected in a cooled trap but discarded. Tem perature
was successively in creased to about 210 °C an d a red oil wh ich partly solidified at room tem -
perature was collected in a trap cooled with liquid n itrogen at a pressure of 2 Pa. After cool-
in g to room tem perature, h exan e (10 m l) was distilled in to th e trap to dissolve th e distillate
an d to separate a sm all am oun t of a wh ite in soluble solid. Th e volum e of th e clear h exan e
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
615
solution was reduced to 5 m l an d cooled to –18 °C overn igh t. Yellow crystals th at separated
from a brown -red solution were isolated an d recrystallized from h exan e. After an alogous
workup of all th e th ree parts a total yield of brigh t yellow crystallin e 6b was 2.41 g (19%).
Data for 6b: M.p. 124 °C. MS (115 °C, m /z (relative abun dan ce)): 353 (M• +, 0.5), 342 (16),
341 (18), 340 (73), 339 (32), 338 ([M – Me]+, 100), 337 (11), 336 (10), 284 (9), 283 (6), 282
([M – Me – Me2C=CH2]+, 13), 162 (6). 1H NMR (C6D6): 0.29, 0.38 (2 × s, 3 H, SiMe2); 1.41 (s,
1
9 H, CMe3); 1.95, 1.96, 2.09 (3 × s, 3 H, Me3C5); 5.90 (Me3C5H). 13C{ H} NMR (CDCl3): 0.89,
3.04 (SiMe2); 12.3, 15.1, 16.0 (Me3C5); 32.7 (CMe3); 62.8 (CMe3); 105.9 (C-Si, Me3C5); 127.0
(CH, Me3C5); 138.0, 139.0, 141.0 (C-Me, Me3C5). IR (KBr): 3 060 (w), 2 958 (vs), 2 912 (s),
2 860 (m ), 1 466 (m ,b), 1 400 (vw), 1 389 (vw), 1 373 (w), 1 363 (m ), 1 359 (m ), 1 340 (w),
1 282 (vw), 1 255 (s), 1 231 (vw), 1 213 (w), 1 180 (s), 1 135 (m ), 1 032 (m ), 987 (s), 922
(w,b), 837 (vs), 812 (m ), 780 (s), 767 (vs), 685 (vw), 657 (w), 539 (vw), 506 (w), 497 (m ), 486
(w), 426 (m ).
Syn th esis of {η5:η1(N)-1-[(tert-butylam ido)dim eth ylsilyl)]-2,3,4-trim eth yl-
5-ph en ylcyclopen tadien yl}dich lorotitan ium (IV) (6c)
1,2,3-Trim eth yl-4-ph en ylcyclopen tadien e (a m ixture of isom ers) was obtain ed by th e reac-
tion of ph en ylm agn esium ch loride with 2,3,4-trim eth ylcyclopen t-2-en -1-on e followed by de-
h ydration catalyzed with iodin e accordin g to th e gen eral procedure24. Recrystallization from
h exan e afforded sligh tly yellow crystals of th e cyclopen tadien es in 61% yield. GC-MS, m/z
(relative abun dan ce): 185 (16), 184 (M• +, 100), 183 (10), 170 (12), 169 (79), 168 (10), 167
(14), 165 (16), 155 (17), 154 (34), 153 (22), 152 (18), 141 (32), 129 (18), 128 (30), 127 (10),
115 (27), 105 (11), 91 (38), 78 (10), 77 (24), 76 (11), 65 (11), 63 (14), 51 (22), 43 (12), 41
(11). IR (KBr): 3 066 (vw), 3 040 (w), 3 021 (w), 2 980 (vw), 2 952 (m ), 2 930 (w), 2 905 (m ),
2 880 (w), 2 867 (w), 2 847 (m ), 1 947 (vw), 1 887 (vw), 1 635 (vw), 1 593 (m ), 1 585 (w),
1 560 (w), 1 485 (m ), 1 435 (s), 1 373 (m ), 1 363 (s), 1 180 (m ), 1 115 (w), 1 095 (w), 1 081
(w), 1 060 (m ), 1 025 (w), 973 (w), 913 (w), 860 (w), 754 (vs), 703 (vs), 561 (w), 529 (m ).
Th e cyclopen tadien e (7.37 g, 40.0 m m ol) was con verted to th e lith ium salt 1c with BuLi
(26.0 m l of 1.6 M solution in h exan e, 41 m m ol), th e salt was stirred for 2 h an d treated with
dich lorodim eth ylsilan e (4.85 m l, 40.0 m m ol). Th e m ixture was refluxed for 1 h , THF an d
h exan e were distilled off an d th e product was distilled at 126 °C/4 Pa an d stored un der ar-
gon . Yield of 1,2,3-trim eth yl-4-ph en ylcyclopen tadien yldim eth ylch lorosilan e (2c) 8.5 g (87%).
All th is silan e was reacted with t-BuNHLi (from tert-butylam in e (3.67 m l, 35.0 m m ol) an d
BuLi (21.8 m l of 1.6 M solution in h exan es, 35.0 m m ol)) to give, after distillation at 125
°C/2 Pa, th e silan e 3c as a yellow fluorescen t oily liquid. Yield 8.4 g (81%). GC-MS m/z (rela-
tive abun dan ce): 313 (M• +, 6), 167 (9), 165 (9), 152 (6), 131 (15), 130 ([Me2SiNHt-Bu]+, 100),
114 (8), 75 (7), 74 (55), 73 (35), 59 (8), 58 (14), 41 (8). IR spectrum (n eat): 3 067 (vw), 3 047
(w), 3 015 (w), 2 958 (vs), 2 904 (s), 2 857 (m ), 1 933 (vw), 1 867 (vw), 1 800 (vw), 1 741
(vw), 1 700 (w), 1 593 (m ), 1 570 (vw), 1 540 (w), 1 483 (m ), 1 460 (m ), 1 440 (s), 1 398 (m ),
1 376 (vs), 1 355 (s), 1 247 (vs), 1 223 (vs), 1 147 (w), 1 113 (w), 1 087 (w), 1 058 (m ), 1 013
(vs), 970 (s), 903 (w), 843 (vs), 817 (vs), 779 (s), 758 (m ), 697 (vs), 633 (w), 520 (w), 492 (w),
457 (w).
Th e syn th esis of 6c was carried out as given above for 6b startin g from th e above silan e
3c (36.0 m m ol). Distillation of th e crude product in vacuo an d crystallization from h exan e at
low tem perature afforded 6c as a yellow crystallin e solid (2.02 g, 13%).
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616
Zemánek et al.:
Data for 6c: M.p. 143 °C. MS (125 °C, m /z (relative abun dan ce)): 429 (M• +, n ot observed),
418 (19), 417 (25), 416 (78), 415 (39), 414 ([M – Me]+, 100), 413 (12), 412 (10), 359 (13),
357 ([M – Me – t-Bu]+, 16), 342 (7), 324 (10), 323 (16), 322 (25), 321 (27), 320 (7), 223 (8),
209 (9), 73 (8), 59 (9), 58 (19), 57 (23), 43 (12). 1H NMR (C6D6): –0.23, 0.44 (2 × s, 3 H,
SiMe2); 1.38 (s, 9 H, CMe3); 2.01, 2.03, 2.14(Me3C5); 7.00–7.13 (m , 3 H, Ph ); 7.19, 7.92 (2 ×
1
br s, 1 H, Ph ). 13C{ H} NMR (C6D6): 4.1, 4.8 (SiMe2); 13.1, 13.3, 16.8 (Me3C5); 32.7 (CMe3);
63.0 (CMe3); 104.3, 135.9, 137.2, 137.6, 142.3, 147.9 (Cipso, Me3C5 an d Ph ); 128.4, 130.7
(br), 132.7 (br) (CH, Ph ). IR (KBr): 3 050 (m ), 2 958 (vs), 2 910 (sh ), 2 855 (s), 1 600 (w),
1 572 (vw), 1 497 (w), 1 463 (m ), 1 443 (s), 1 402 (m ), 1 390 (sh ), 1 378 (s), 1 360 (s), 1 323
(m ), 1 309 (w), 1 255 (vs), 1 229 (m ), 1 214 (m ), 1 180 (vs), 1 094 (m ,b), 1 075 (m ), 1 024
(s), 981 (vs), 926 (sh ), 918 (m ), 847 (vs), 822 (s), 805 (s), 792 (sh ), 769 (vs), 702 (vs), 681
(m ), 641 (w), 589 (w), 547 (s), 500 (m ), 480 (s), 430 (s).
Syn th esis of {η5:η1(N)-1-[(tert-Butylam ido)dim eth ylsilyl)]-2-(4-fluoroph en yl)-
3,4,5-trim eth ylcyclopen tadien yl}dich lorotitan ium (IV) (6d )
1-(4-Fluoroph en yl)-2,3,4-trim eth ylcyclopen tadien e (a m ixture of isom ers) was syn th esized
from (4-fluoroph en yl)m agn esium ch loride an d 2,3,4-trim eth ylcyclopen t-2-en -1-on e accord-
in g to th e gen eral procedure21. Recrystallization from h exan e afforded sligh tly yellow crys-
tals of th e cyclopen tadien e in th e yield of 82%. GC-MS, m/z (relative abun dan ce): 203 (16),
202 (M• +, 100), 188 (15), 187 (99), 185 (9), 183 (14), 173 (14), 172 (31), 171 (19), 170 (17),
167 (23), 166 (14), 165 (27), 159 (26), 153 (9), 152 (24), 147 (12), 146 (21), 133 (22), 109
(21), 91 (15), 41 (10), 39 (16). IR (KBr): 3 051 (vw), 3 032 (vw), 2 967 (m ), 2 933 (w), 2 907
(s), 2 850 (m ), 1 893 (vw), 1 637 (vw), 1 598 (w), 1 585 (m ), 1 561 (m ), 1 500 (vs), 1 440
(m ), 1 403 (w), 1 377 (s), 1 325 (w), 1 297 (w), 1 227 (vs), 1 177 (m ), 1 154 (s), 1 117 (w), 1 103
(m ), 1 073 (m ), 1 007 (w), 981 (w), 860 (m ), 830 (vs), 810 (s), 730 (w), 713 (w), 573 (m ), 560
(m ), 527 (m ), 474 (w).
Subsequen t reaction s follow th e sam e protocol as given for th e syn th esis of com poun d
6b. Th us, usin g th e cyclopen tadien e (12.4 g, 49.0 m m ol), th e correspon din g ch lorosilan e 2d
was obtain ed (11.1 g, 77%) an d im m ediately con verted to th e am in osilan e 3d (9.6 g, 78%).
GC-MS, m/z (relative abun dan ce): 331 (M• +, 4), 202 (7), 201 (6), 200 (6), 185 (10), 184 (5),
183 (10), 165 (16), 131 (19), 130 ([Me2SiNHt-Bu]+, 100), 114 (11), 74 (52), 73 (32), 58 (14),
41 (8). IR (n eat): 3 037 (w), 2 973 (vs), 2 907 (s), 2 860 (m ), 1 887 (vw), 1 600 (w), 1 547
(m ), 1 500 (s), 1 467 (w), 1 447 (m ), 1 400 (w), 1 387 (s), 1 360 (m ), 1 247 (s), 1 230 (vs), 1 153
(m ), 1 117 (w), 1 073 (w), 1 017 (s), 973 (m ), 953 (w), 839 (vs), 824 (s), 776 (m ), 747 (vw),
733 (vw), 633 (w), 580 (w), 567 (m ), 527 (w), 500 (m ), 427 (w).
Th e titan ium (IV) com plex 6d was prepared from silan e 3d (11.9 g, 36 m m ol) by th e
procedure described above. Yield: 2.25 g (14%), yellow crystallin e solid. M.p. 170 °C. MS
(135 °C, m/z (relative abun dan ce)): 447 (M• +, 1), 437 (6), 436 (20), 435 (26), 434 (85), 433
(46), 432 ([M – Me]+, 100), 431 (13), 430 (11), 377 ([M – Me – t-Bu]+, 98), 375 (9), 342 (8),
341 (12), 340 (19), 339 (19), 191 (7), 58 (66), 57 (16), 55 (7), 43 (10), 42 (9), 41 (33).
1H NMR (C6D6): –0.29, 0.42 (2 × s, 3 H, SiMe2); 1.36 (s, 9 H, Me3C); 1.98, 2.00, 2.11 (3 × s,
3 H, Me3C51); 6.68–8.00 (m con sistin g of sh arp m ultiplets (2 H) an d a broad doublet (2 H),
C6H4). 13C{ H} NMR (C6D6): 4.1, 4.8 (SiMe2); 13.1, 13.2, 16.8 (Me3C5); 32.7 (Me3C); 63.0
2
4
(Me3C); 104.3 (Cipso, C5Me3); 114.9 (d, JFC = 21, γ-CH); 131.7 (d, JFC = 3, α-C); 133.4 (br d,
1
∆ν1/2 ≈ 250, β-CH); 137.2, 137.7, 142.2, 146.3 (Cipso, C5Me3); 163.0 (d, JFC = 248, δ-CF). IR
(KBr): 3 040 (w), 2 964 (vs), 2 916 (s), 2 860 (m ), 1 913 (vw), 1 662 (vw), 1 602 (s), 1 511
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(Amidocyclopentadienyl)dichlorotitanium(IV) Complexes
617
(vs), 1 464 (m ), 1 439 (w), 1 402 (m ), 1 388 (s), 1 375 (m ), 1 360 (s), 1 312 (w), 1 260 (s), 1 251
(s), 1 228 (vs), 1 179 (vs), 1 157 (m ), 1 093 (m ), 1 033 (w), 1 014 (w), 980 (s), 916 (w), 848
(vs,b), 820 (m ), 790 (vs), 780 (vs), 767 (vs), 726 (w), 682 (w), 642 (vw), 627 (vw), 587 (w),
577 (m ), 545 (m ), 507 (s), 465 (m ), 434 (s).
Syn th esis of {η5:η1(N)-1-[(tert-Butylam ido)dim eth ylsilyl)]-2,3,4-trim eth yl-
5-(1-m eth ylallyl)cyclopen tadien yl}dich lorotitan ium (IV) (6e)
Grign ard reagen t prepared from 3-ch lorobut-1-en e was reacted with 2,3,4-trim eth ylcyclo-
pen t-2-en -1-on e in dieth yl eth er an d th e alcoh ol obtain ed was in stan tly deh ydrated with a
catalytic am oun t of iodin e accordin g to th e gen eral procedure22. A m ixture of isom eric
1,2,3-trim eth yl-4-(1-m eth ylallyl)cyclopen tadien es was obtain ed as a colourless liquid in 80%
yield (based on th e keton e). GC-MS, m/z (relative abun dan ce): 162 (M• +, 12), 147 (18), 133
(6), 119 (20), 107 (18), 106 (8), 105 (38), 93 (14), 91 (74), 79 (34), 77 (44), 65 (32), 63 (10),
55 (51), 53 (36), 51 (36), 41 (94), 40 (11), 39 (100). IR (n eat): 3 067 (m ), 2 960 (vs), 2 907
(vs), 2 852 (s), 1 812 (w), 1 650 (sh ), 1 630 (s), 1 440 (vs), 1 408 (m ), 1 372 (s), 1 330 (w), 1 158
(m ), 1 087 (m ), 993 (s), 903 (vs), 850 (m ), 773 (w), 682 (m ), 508 (w).
Subsequen t reaction of C5H2Me3(CHMeCH=CH2) (8.5 g, 53.0 m m ol) with equim olar
am oun t of dich lorodim eth ylsilan e afforded ch lorosilan e 2e (8.5 g, 68%) an d fin ally, upon
reactin g with t-BuNHLi, th e silan e 3e (8.3 g, 79%) as a yellow fluorescen t liquid distillin g at
120 °C/2 Pa. Data for 3e: GC-MS, m/z (relative abun dan ce): 290 (M• +, 1), 132 (5), 131 (19),
130 ([Me2SiNHt-Bu]+, 100), 128 (6), 115 (6), 114 (9), 91 (9), 75 (9), 74 (81), 73 (65), 60 (7),
59 (21), 58 (12), 57 (15), 55 (32), 53 (8), 46 (15), 45 (11), 44 (13), 42 (11), 41 (29). IR (n eat):
3 072 (w), 2 953 (vs), 2 927 (s), 2 907 (sh ), 2 860 (m ), 1 630 (m ), 1 450 (s), 1 400 (m ), 1 380
(vs), 1 360 (s), 1 250 (vs), 1 229 (vs), 1 017 (vs), 980 (m ), 962 (w), 906 (s), 847 (vs), 828 (s),
798 (m ), 773 (s), 680 (w), 634 (w), 513 (vw), 472 (w).
Th e reaction of 3e (10.5 g, 36.0 m m ol) with [TiCl3(THF)3] (from 4.0 m l (36.0 m m ol)
TiCl4), PbCl2 oxidation an d workup as given above gave 6e (1.32 g, 9%) as a yellow crystal-
lin e solid. M.p. 112 °C. MS (90 °C, m/z (relative abun dan ce)): 407 (M• +, 4), 396 (18), 395
(23), 394 (76), 393 (37), 392 ([M – Me]+, 100), 391 (12), 390 (10), 376 (8), 339 (12), 338 (13),
337 (47), 336 (22), 335 ([M – Me – t-Bu]+, 66), 334 (8), 333 (7), 322 (7), 320 (10), 319 (6),
301 (7), 300 (13), 299 (12), 285 (7), 73 (17), 59 (21), 57 (21), 41 (25). 1H NMR (C6D6): 0.39,
0.43 (2 × s, 3 H, SiMe2); 1.37 (s, 9 H, Me3C); 2.01, 2.07, 2.08 (3 × s, 3 H, Me3C5); 1.49 (dq,
JHH = 5.6, 1.1, 3 H, CH(Me)CH=CH2); 3.24–3.33 (br m , 1 H, CH(Me)CH=CH2); 5.12 (q, JHH
=
1.6, 1 H, CH(Me)CH=CH2); 5.35–5.39 (m , 1 H, CH(Me)CH=CH2); 5.41 (qq, 1 H, JHH = 1.5,
1
6.7, CH(Me)CH=CH2). 13C{ H} NMR (C6D6): 5.0 (SiMe2); 13.1, 13.2, 16.8 (Me3C5); 13.9
(CH(Me)CH=CH2); 32.8 (Me3C); 62.8 (Me3C); 70.8 (CH(Me)CH=CH2); 103.5 (Cipso, C5Me3);
117.4 (CH(Me)CH=CH2); 128.6 (CH(Me)CH=CH2); 131.4, 136.5, 141.6, 152.2 (Cipso, C5Me3).
IR (KBr): 3 055 (vw), 3 020 (sh ), 2 957 (s), 2 940 (sh ), 2 902 (m ), 2 860 (w), 1 640 (w), 1 465
(m ), 1 453 (w), 1 439 (m ), 1 404 (w), 1 389 (m ), 1 373 (m ), 1 360 (s), 1 333 (vw), 1 306 (m ),
1 260 (s), 1 252 (s), 1 229 (w), 1 215 (m ), 1 182 (vs), 1 107 (vw), 1 052 (w), 1 034 (w), 1 022
(vw), 983 (s), 908 (w), 850 (vs), 817 (m ), 791 (s), 770 (vs), 687 (w), 639 (w), 627 (vw), 594
(vw), 549 (m ), 497 (m ), 466 (w), 432 (s).
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Zemánek et al.:
TABLE II
Crystal an d structure refin em en t data for 6a an d 6d
Param eter
6aa
6d
Form ula
C
15H27Cl2NSiTi
C20H28Cl2NSiTi
448.32
Form ula weigh t, g m ol–1
368.27
Crystal system
Space group
a, Å
orth orh om bic
Pnma (No. 62)
11.608(5)
13.500(5)
12.181(5)
90
m on oclin ic
P21/c (No. 14)
13.620(3)
8.5715(9)
20.183(3)
90
b, Å
c, Å
α, °
β, °
90
107.033(15)
90
γ, °
90
V, Å3; Z
1 909(1); 4
1.281
2 253.0(6); 4
1.322
d
calc, g cm –3
µ(MoKα), m m –1
F(000)
0.783
0.683
776
936
Crystal size, m m 3
Ran ge of θ, °
0.6 × 0.4 × 0.2
2.86–25.02
–1→30, –16→15, 0→14
3 183
0.5 × 0.3 × 0.2
1.56–24.94
Ran ge of h,k an d l
Reflection s collected
In depen den t reflection s
No. of data/param eters
S
–16→15, 0→10, 0→23
4 051
1 754
3 924
1 754/118
1.059
3 924/314
1.006
R, wR (all data)
R, wR (observed diffraction s)b
∆ρm ap, eÅ–3
0.0686, 0.1472
0.0492, 0.1340
0.493; –0.329
0.1304, 0.1321
0.0469, 0.1080
0.435; –0.316
R(F) = 3|Fo| – |Fc||/Σ|Fo|, wR(F2) = [Σ(w(F2 − F2)2)/(Σw(F2)2)]2, S = [Σ(w(F2 − F2)2)/(Ndiffrs – Nparams)]1/2
.
o
c
o
o
a
bc
Crystallograph ic data for 6a agree with th ose publish ed earlier10c
.
I > 2σ(I).
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619
{η5:η1(N)-1-[(tert-Butylam ido)dim eth ylsilyl]-2,3,4,5-tetram eth ylcyclopen tadien yl}-
dich lorotitan ium (IV) (6a)
MS (115 °C, m/z (relative abun dan ce)): 367 (M• +, 0.4), 356 (18), 355 (20), 354 (73), 353 (34),
352 ([M – Me]+, 100), 351 (11), 350 (10), 298 (9), 297 (7), 296 ([M – Me – Me2C=CH2]+, 12),
295 (7), 169 (5), 73 (7), 59 (10), 58 (7), 57 (6), 41 (10). 1H NMR (C6D6): 0.43 (s, 6 H, SiMe2);
1
1.42 (s, 9 H, CMe3); 1.99, 2.00 (2 × s, 6 H, Me4C5). 13C{ H} NMR (C6D6): 5.4 (SiMe2); 13.0,
13.1 (Me4C5); 32.7 (CMe3); 62.1 (CMe3); 104.0 (Me4C5, C-Si); 137.9, 140.6 (Me4C5, C-Me)
(cf. ref.9c). IR (KBr): 2 954 (vs), 2 900 (s), 2 860 (s), 1 466 (s), 1 390–1 360 (s,b), 1 320 (s), 1 254
(vs), 1 230 (w), 1 214 (m ), 1 180 (vs), 1 087 (m ), 1 020 (s), 986 (vs), 920 (m ), 840 (vs), 814 (s),
793 (s), 766 (vs), 687 (m ), 660 (m ), 540 (w), 514 (vs), 497 (m ).
Crystal Structure An alysis of 6a an d 6d
Fragm en ts of yellow crystals of com plexes 6a an d 6d were in serted in to Lin dem an n glass
capillaries in a glove box. Diffraction data for 6a were collected on a Non ius KappaCCD
diffractom eter with CCD area detector an d th ose for 6d on an En raf–Non ius CAD-4 MACH
III diffractom eter usin g graph ite m on och rom ated MoKα radiation (λ = 0.71069 Å), both at
room tem perature. Th e structures were solved by direct m eth ods (SIR-92, ref.25). Th e n on -
h ydrogen atom s were refin ed an isotropically. All h ydrogen atom s in 6a were in cluded in
calculated position s. Hydrogen atom s in 6d were iden tified on differen ce Fourier electron
den sity m aps an d isotropically refin ed with th e exception of h ydrogen atom s of th e
tert-butyl group wh ich were fixed in calculated position s. Refin em en t by full-m atrix
least-squares on F2 was perform ed usin g th e SHELXL97 program 26. Crystallograph ic data, de-
tails of th eir collection an d th e structure refin em en t are given in Table II. Crystallograph ic
data for th e structures reported in th is paper h ave been deposited with th e Cam bridge Crys-
tallograph ic Data Cen tre as supplem en tary publication n um bers: CCDC-158989 (for 6a) an d
CCDC-158988 (for 6d ). Copies of th e data can be obtain ed free of ch arge on application to
CCDC, e-m ail: deposit@ccdc.cam .ac.uk.
This investigation was supported by the Council for Research and Development of Academy of
Sciences of the Czech Republic (project No. S4040017), and is a part of a long-term research plan of
the School of Sciences, Charles University (MSM 11310001). The authors also thank Unipetrol Com-
pany, Prague for financial support. Grant Agency of the Czech Republic sponsored access to Cambridge
Structure Database (grant No. 203/99/0067).
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