Facile functionalizations of permethyltitanocene dichloride to chiral persubstituted titanocene complexes

Article abstract of DOI:10.1021/om000069f

The new class of compounds arising from unconventinal additions of 1, 4-disubstituted 1, 3-butadiynes to activated permethylmetallocene species of Ti and Zr can be used in facile functionalizations. For example, the chiral product 5, obtained from the addition of tBuC=CC=CtBu to activated permethyltitanocene, has been derivatized by simple means, e.g., hydrogen chloride, bromine, or dihydrogen, affording practically useful functionalized titanocene compounds containing a chiral auxiliary ligand with an intramolecularly coordinated (compound 7) or a free double bond (compounds 8a, b). The new complexes have been characterized spectroscopically. Additionally, X-ray crystal structure analyses were performed for 7 and 8a, b.

Full text of DOI:10.1021/om000069f

2
816
Organometallics 2000, 19, 2816-2819
F a cile F u n ction a liza tion s of P er m eth yltita n ocen e
Dich lor id e to Ch ir a l P er su bstitu ted Tita n ocen e
Com p lexes
†
†,‡
†
Paul-Michael Pellny, Vladimir V. Burlakov, Wolfgang Baumann,
†
§
|
,§
Anke Spannenberg, Michal Hor a´ cˇ ek, Petr Sˇ t eˇ pni cˇ ka, Karel Mach,* and
,
†
Uwe Rosenthal*
Institut f u¨ r Organische Katalyseforschung an der Universit a¨ t Rostock, Buchbinderstrasse 5-6,
D-18055 Rostock, Germany, J . Heyrovsk y´ Institute of Physical Chemistry, Academy of Sciences
of the Czech Republic, Dolej sˇ kova 3, 182 23 Prague 8, Czech Republic, and Department of
Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
Received J anuary 26, 2000
Summary: The new class of compounds arising from
unconventinal additions of 1,4-disubstituted 1,3-buta-
diynes to activated permethylmetallocene species of Ti
and Zr can be used in facile functionalizations. For
example, the chiral product 5, obtained from the addition
of tBuCtCCtCtBu to activated permethyltitanocene,
has been derivatized by simple means, e.g., hydrogen
chloride, bromine, or dihydrogen, affording practically
useful functionalized titanocene compounds containing
a chiral auxiliary ligand with an intramolecularly
coordinated (compound 7) or a free double bond (com-
pounds 8a ,b). The new complexes have been character-
ized spectroscopically. Additionally, X-ray crystal struc-
ture analyses were performed for 7 and 8a ,b.
Another coupling product (6) has been obtained by
thermally induced replacement of the coordinated alkyne
2
in the permethyltitanocene source [Cp* Ti(η -Me SiC -
2
3
2
SiMe )] (2)3 by the butadiyne tBuCtCCtCtBu.2c In this
reaction 5 has to be regarded as an intermediate, since
3
2b
a direct conversion of 5 into 6 is also possible (Scheme
2c
2
).
Here we report on further functionalizations of com-
pounds 5 and 6 with simple reagents, e.g. hydrogen
chloride, bromine, and dihydrogen, affording the novel,
easily applicable chiral derivatives 7 and 8a ,b (Scheme
2
).
Resu lts a n d Discu ssion
All the chemistry depicted in Scheme 2 ensues from
In tr od u ction
the reduction of the commercially available permeth-
yltitanocene dichloride Cp*2TiCl2 (1) by magnesium.
This system in the presence of tBuCtCCtCtBu affords
the coupled alkyne compound 5 (reaction pathway I);2b
the same system in the presence of Me3SiCtCSiMe3
Functionalized chiral metallocenes can successfully
be employed in various stoichiometric and catalytic
reactions, including stereospecific polymerizations of
prochiral olefins. For that reason there is a considerable
demand for facile syntheses of compounds already
known and also for developing new reaction pathways
3
complex 2, on subsequent thermolysis with tBuCtCCt
2
c
1
CtBu, gives the coupled complex 6. Both complexes 5
and 6 react smoothly with 2 equiv of HCl to yield the
olefinic dichloride 8a (reaction pathways IV and V,
respectively). The two protons are added either to the
triple bond of 5 or the two methylene groups of 6.
Importantly, complex 5 reacts quantitatively with mo-
lecular hydrogen to give the novel intramolecularly
coordinated titanocene-olefin complex 7 (III). This
compound is also obtained from 8a by the removal of
chlorine by magnesium (VI).
that afford novel metallocene derivatives.
We have recently found out that the reduction of
permethylmetallocene dichlorides [Cp*2MCl2] (M ) Ti
(1), Zr) with magnesium in THF in the presence of
commercially available disubstituted 1,3-butadiynes
RCtCCtCR leads to a metallacyclopropene (M ) Ti,
R ) SiMe3), to some five-membered metallacyclocumu-
lenes (M ) Zr; R ) Ph, Me, SiMe3), or, via C-H
activations and C-C coupling reactions, to coupling
2
products such as 3-5 (Scheme 1).
The reaction of 7 with HCl produces the paraffinic
dichloride 9 (VII) only in a low yield. Instead, complex
*
To whom correspondence should be addressed. U.R.: Tel/Fax,
International code + (49) 381 4669376; E-mail, uwe.rosenthal@ifok.uni-
rostock.de. K.M.: Fax, International code + (4202) 8582307; E-mail,
mach@jh-inst.cas.cz.
(2) (a) Pellny, P.-M.; Kirchbauer, F. G.; Burlakov, V. V.; Baumann,
W.; Spannenberg, A.; Rosenthal, U. J . Am. Chem. Soc. 1999, 121, 8313.
(b) Pellny, P.-M.; Kirchbauer, F. G.; Burlakov, V. V.; Baumann, W.;
Spannenberg, A.; Rosenthal, U. Chem. Eur. J . 2000, 6, 81. (c) Hor a´ cˇ ek,
M.; Sˇ t eˇ pni cˇ ka, P.; Gyepes, R.; C ´ı sa rˇ ov a´ , I.; Pol a´ sˇ ek, M.; Mach, K.;
Pellny, P.-M.; Burlakov, V. V.; Baumann, W.; Spannenberg, A.;
Rosenthal, U. J . Am. Chem. Soc. 1999, 121, 10638.
†
Universit a¨ t Rostock.
Current address: Institute of Organoelement Compounds of the
‡
Russian Academy of Sciences, Moscow, Russia.
§
Academy of Sciences of the Czech Republic.
Charles University.
|
(1) (a) Halterman, R. L. In Metallocenes; Togni, A., Halterman, R.
L., Eds.; Wiley-VCH: Weinheim, Germany, 1998; Vol. 1 (Synthesis and
Reactivity), Chapter 8, pp 455-539. (b) Hoveyda, A. H.; Morken, J . P.
In Metallocenes; Togni, A., Halterman, R. L., Eds.; Wiley-VCH:
Weinheim, Germany, 1998; Vol. 2 (Applications), Chapter 10, pp 625-
(3) (a) Burlakov, V. V.; Rosenthal, U.; Beckhaus, R.; Polyakov, A.
V.; Struchkov, Yu. T.; Oehme, G.; Shur, V. B.; Vol’pin, M. E. Orga-
nomet. Chem. USSR (Engl. Transl.) 1990, 3, 237. (b) Burlakov, V. V.;
Polyakov, A. V.; Yanovsky, A. I.; Struchkov, Yu. T.; Shur, V. B.; Vol’pin,
M. E.; Rosenthal, U.; G o¨ rls, H. J . Organomet. Chem. 1994, 476, 197.
(c) Varga, V.; Mach, K.; Pol a´ sˇ ek, M.; Sedmera, P.; Hiller, J .; Thewalt,
U.; Troyanov, S. I. J . Organomet. Chem. 1996, 506, 241.
6
79. (c) Brintzinger, H.-H.; Fischer, D.; M u¨ lhaupt, R.; Rieger, B.;
Waymouth, R. Angew. Chem. 1995, 107, 1255; Angew. Chem., Int. Ed.
Engl. 1995, 34, 1625 and references therein.
1
0.1021/om000069f CCC: $19.00 © 2000 American Chemical Society
Publication on Web 06/03/2000

Notes
Organometallics, Vol. 19, No. 14, 2000 2817
Sch em e 1
8
a is formed accompanied by hydrogen liberation (VIII).
bromine analogues of these two complexes are side
products of the formation of complex 8b (VIII).
This implies that the hydrogen addition to the double
bond is less feasible than the hydrogen elimination.
Addition of a stoichiometric amount of elemental bro-
mine to 7 affords the olefinic dibromide 8b (VIII).
Complex 8a , however, is unstable toward an excess
of hydrogen chloride. NMR analysis showed its slow
The yellow complex 7 and the brownish red complexes
8a ,b were prepared according to the described proce-
dure. They are readily soluble in THF, toluene, and
n-hexane. Their spectral data verify the constitutional
formulas shown in Scheme 2. The presence of noncoor-
dinated double bonds in 8a ,b is confirmed by signals in
5
conversion to a mixture of [Cp*TiCl3] and [{η -C5Me3-
1
13
(
-CH2CH(tBu)CHdCHCH(tBu)CH2-}TiCl3], implying
both the H (δ 5.29-5.38) and C NMR spectra (δ 130.4,
131.6), while the complexation of the double bond in 7
acidolysis of Cp* or the modified Cp* ligand. The
Sch em e 2

2
818 Organometallics, Vol. 19, No. 14, 2000
Notes
F igu r e 2. Molecular structure of 8b in the crystal.
Hydrogen atoms are omitted for clarity. The thermal
ellipsoids correspond to 30% probability. Selected bond
lengths (Å) and angles (deg): Ti-Br1 2.516(1), Ti-Br2
F igu r e 1. Molecular structure of 7 in the crystal. Hydro-
gen atoms are omitted for clarity. The thermal ellipsoids
correspond to 30% probability. Selected bond lengths (Å)
and angles (deg): Ti-C30 2.205(2), Ti-C40 2.171(2), C30-
C40 1.462(4), C30-C31 1.541(3), C31-C25 1.534(4), C25-
C20 1.500(4), C40-C41 1.530(3), C41-C26 1.530(4), C26-
C21 1.502(3);C30-Ti-C40 39.03(9),C30-C40-C41 131.3(2),
C40-C41-C26 109.2(2), C41-C26-C21 108.3(2), C40-
C30-C31 125.3(2), C30-C31-C25 110.0(2), C31-C25-
C20 111.3(2).
2
.522(1), C5-C6 1.501(8), C6-C7 1.539(9), C7-C8 1.503-
9), C8-C9 1.318 (8), C9-C10 1.522(8), C11-C1 1.508(8);
Br1-Ti-Br2 91.11(5), C5-C6-C7 112.3(5), C6-C7-C8
(
1
14.8(5), C7-C8-C9 131.3(6), C8-C9-C10 128.0 (6), C9-
C10-C11 109.0(5), C10-C11-C1 116.7(5).
double bonds (8a , C18-C19 ) 1.313(6) Å; 8b, C8-C9
)
1.318(8) Å), whose posture and distance are in good
accordance with that in complex 6 (1.330(9) Å).
1
can be deduced from the corresponding H (δ 1.32, 2.77)
2
c
1
3
and C (δ 119.4, 122.5) NMR signals, which are found
in the region typical for titanacyclopropanes, e.g. [Cp*2-
The bite angles between the functionalized and non-
functionalized pentamethylcyclopentadienyl ligands in
the halogen-free complexes (5, 147°; 7, 146°) are larger
as in the halogen-bearing examples (8a , 138°; 8b, 136°);
the latter are similar to those found for 2 (139°) and
similar compounds.
Complexes 7 and 8a ,b are chiral, each of them
forming one pair of enantiomers, as did compounds 5
2
5
Ti(η -H2C2H2)] (δ 2.02; δ 105.1).
4
The crystal structure analyses of 7 and 8a ,b (the
molecular structures of 7 and 8b are presented in
Figures 1 and 2) show a bent-sandwich arrangement
with one pentamethylcyclopentadienyl ligand and one
,4,5-trimethylcyclopentadienyl ligand annellated in
,2-positions with 3,6-di-tert-butylcyclooct-4-ene.
7
3
1
2
b,c
and 6.
The key step determining the configuration
In the chlorine-free complex 7, the double bond
6
of the two tBu-substituted stereogenic centers (R,R in
one enantiomer and S,S in the other) is the formation
of complex 5 (step I in Scheme 2). Obtaining only one
of the possible diastereomeric pairs in high yield seems
to be controlled by steric requirements during the
hydrogen transfer and CC bond formation between the
pentamethylcyclopentadienyl ligand and 1,4-di-tert-bu-
tylbuta-1,3-diyne. Once defined, this chirality is pre-
served in all subsequent reactions of 5 and its succes-
sors. For all compounds, a resolution of the two
enantiomers has not been attempted yet.
coordinates to the metal center, forming a titanacyclo-
propane entity (Ti-C30 2.205(2) Å, Ti-C40 2.171(2) Å,
C30-C40 1.462(4) Å). The C-C distance in 7 is similar
to that in the analogous ethylene complex [Cp*2Ti(η -
H2C2H2)] (1.438(5) Å). Altogether the molecular struc-
2
5
ture of 7 can be compared to that of the titanacyclopro-
pene 5, where an interaction of the titanium with a
6
triple bond elongated the C-C bond (1.297(4) Å) close
to the value found in 2 (1.309(4) Å).3
a,b
In contrast, the
halogen-bearing complexes 8a ,b feature noncomplexed
(
4) Crystal data for 7: triclinic, P 1h , a ) 9.371(1) Å, b ) 11.874(2) Å,
The reactions of Scheme 2 represent the first simple
case of derivatization of a new class of compounds
arising from additions of 1,4-disubstituted 1,3-butadiynes
to activated permethylmetallocene species of titanium
and zirconium. Further derivatizations of compounds
involved in Scheme 2 by, for example, thermolysis,
insertion reactions with carbon dioxide and other highly
polar compounds, and acidolyses are under way, prom-
ising a broad spectrum of interesting chiral metallocene
compounds.
c ) 13.434(2) Å, R ) 88.06(1)°, â ) 82.11(1)°, γ ) 70.50(1)°, V ) 1395.5-
3
-3
(
3) Å , Z ) 2, F ) 1.149 g cm , 4901 measured reflections, 4900
symmetry-independent reflections, 4900 of which were considered as
observed (I > 2σ(I)), 498 refined parameters, R1 ) 0.062, wR2 ) 0.171
all data), residual electron density 0.998 e Å . Crystal data for 8a :
-3
(
monoclinic, P2 /c, a ) 10.558(2) Å, b ) 17.869(4) Å, c ) 16.501(3) Å, â
1
3
-
3
)
93.56(3)°, V ) 3107.1(11) Å , Z ) 4, F ) 1.183 g cm , 6171 measured
reflections, 3200 symmetry-independent reflections, 1854 of which were
considered as observed (I > 2σ(I)), 324 refined parameters, R1 ) 0.042,
-3
wR2 ) 0.091 (all data), residual electron density 0.308 e Å . Crystal
data for 8b: monoclinic, P2 /n, a ) 8.622(2) Å, b ) 24.544(5) Å, c )
1
3
1
5.026(3) Å, â ) 100.22(3)°, V ) 3129.3(12) Å , Z ) 4, F ) 1.364 g
-3
cm , 6207 measured reflections, 3309 symmetry-independent reflec-
tions, 2452 of which were considered as observed (I > 2σ(I)), 316 refined
parameters, R1 ) 0.049, wR2 ) 0.137 (all data), residual electron
(7) Hitchcock, P. B.; Kerton, F. M.; Lawless, G. A. J . Am. Chem.
Soc. 1998, 120, 10264.
density 0.855 e Å-
3
.
(
5) Cohen, S. A.; Auburn, P. R.; Bercaw, J . E. J . Am. Chem. Soc.
983, 105, 1136.
6) Beckhaus, R. In Metallocenes; Togni, A., Halterman, L. R., Eds.;
(8) Structure refinement details: STOE-IPDS diffractometer, graph-
ite-monochromated Mo KR radiation, structure solution by direct
methods (Sheldrick, G. M. SHELXS-86. Acta Crystallogr., Sect. A 1990,
1
(
Wiley-VCH: Weinheim, Germany, 1998; Vol. 1 (Synthesis and Reactiv-
ity), Chapter 4, pp 153-230, and references therein.
46, 467) and refined by full-matrix least-squares techniques against
2
F
(SHELX-93); structure representation by XP (Siemens).

Notes
Organometallics, Vol. 19, No. 14, 2000 2819
Exp er im en ta l Section
evaporated under vacuum to yield 0.39 g (95%) of pure 8a (by
NMR). Recrystallization of 8a from n-hexane afforded red-
All research was carried out under the exclusion of oxygen
and moisture. Compounds 5 and 6 were prepared according
to methods given in ref 2c. NMR data were recorded on a
Bruker ARX-400 spectrometer at T ) 297 K in solutions of
C D . X-ray crystal structure investigations were conducted
6 6
according to ref 8.
Syn th esis of 7. F r om 5. The argon atmosphere over a
solution of 5 (0.88 g, 1.83 mmol) in 30 mL of n-hexane was
carefully replaced by hydrogen, and the solution was stirred
under hydrogen for 3 h at room temperature, while the color
slightly darkened from yellow to brownish yellow. Filtration,
concentration to about 5 mL, and crystallization at -78 °C
for 1 day gave yellow crystals of 7 (0.79 g, 90%).
F r om 8a . A suspension of 8a (0.30 g, 0.54 mmol), magne-
sium (0.1 g, 4.0 mmol), and bis(trimethylsilyl)acetylene (1.0
mL, 4.5 mmol) in 20 mL of THF was stirred at 60 °C for 4 h.
Within 0.5 h the starting red suspension turned yellow. The
resulting solution was filtered, all volatile material was
removed under vacuum, and the residue was extracted with
brown crystals. Mp: 210-211 °C. Anal. Calcd for C32
H50TiCl
2
(
553.52): C, 69.44; H, 9.10. Found: C, 69.48; H, 9.16. MS (70
+
+
+
eV): m/z 552 ([M] ), 517 ([M - Cl] ), 417 ([M - Cp*] ), 290
+
-1
(
(
(
(
(
(
[M - Cp*TiCl ] ); IR (KBr, cm ): 3004 (m), 2952 (vs, b), 2900
2
vs), 2863 (s), 1470 (s, b), 1433 (m), 1391 (m), 1375 (s), 1363
s), 1278 (vw), 1260 (vw), 1226 (m), 1107 (w), 1063 (w), 1014
m), 940 (vw), 920 (w), 866 (w), 824 (w), 794 (m), 709 (m), 680
1
vw), 604 (vw), 467 (vw). H NMR: δ 0.97, 1.00 (2 × s, 9 H,
CH
3
)
3
C), 1.74 (s, 3 H, CH
3
), 1.91 (s, 15 H, (CH
3
)C
5
), 2.00 (2 ×
3
s, 3 H, CH
1
)
CH
3
), 2.02-2.10 (m, 1 H, CH B), 2.33 (dd, 1 H, J HH
)
2
3
2
2.6, J HH ) 15.9 Hz, CH
2
A), 2.88 (dd, 1 H, J HH ) 5.2, J HH
3
2
14.0 Hz, CH
2
B), 2.91 (dd, 1 H, J HH ) 5.2, J HH ) 15.9 Hz,
3
2
2
A), 3.27-3.35 (m, 1 H, CH A), 3.46 (dd, 1 H, J HH ≈ J HH
13
1
≈
14.0 Hz, CH
2
B), 5.29-5.38 (m, 2 H, CHdCH A,B). C{ H}
1.74), 12.9 (δ ), 13.2
2.00) (2 × CH
, δ 2.00), 27.6 (δ 0.97), 28.2 (δ 1.00)
C), 29.1 (CH B), 30.0 (CH
A), 33.3, 35.3 (2 ×
C), 45.4 (CH A), 52.3 (CH B), 124.9 (CCH ), 128.1
), 128.3, 129.5 (2 × CCH ), 130.4, 131.6 (CHdCH
).
Syn th esis of 8b. F r om 7. A freshly prepared solution of
in n-hexane (0.39 M, 1.40 mL, 0.55 mmol) was added to a
NMR: δ 12.4 (δ
H
H
3
(
(
(
(
(CH
3
)
5
C
5
), 13.8 (CH
3
H
H
H
2 × (CH
3
)
3
2
2
CH
(CH
3
)
3
3
3
)
5
C
5
3
3
0 mL of n-hexane. Concentration to about 3 mL and crystal-
lization at -78 °C for 2 days afforded yellow crystals. Decant-
ing, recrystallizing from n-hexane, and drying under vacuum
A,B); 131.3, 133.8 (2 × CCH
3
Br
2
yielded 7 (0.23 g, 88%). Mp: 163 °C. Anal. Calcd for C32H50Ti
solution of 7 (0.26 g, 0.55 mmol) in 10 mL of n-hexane. The
color of the mixture changed quickly from yellow to brown,
and within 5-10 min dark crystals started to precipitate. After
(
(
482.62): C, 79.64; H, 10.44. Found: C, 79.67; H, 10.45. MS
+
+
70 eV, 230 °C): m/z 483 ([M ]), 426 ([M - tBu] ). IR (KBr,
-
1
cm ): 3004 (m), 2940 (vs, b), 2894 (vs, b), 2856 (vs), 2813 (m),
467 (s), 1460 (vs), 1440 (m), 1387 (s), 1373 (s), 1358 (vs), 1300
3
h the crystalline material was separated from the mother
1
(
(
8
liquor, washed with cold n-hexane, and dried in vacuo (154
mg). The mother liquor was cooled to -30 °C to afford a second
fraction of 118 mg of 8b. Total yield: 0.27 g (78%). Mp: 186-
s), 1285 (vw), 1260 (vw), 1227 (m), 1200 (m), 1127 (vw), 1075
vw), 1060 (w), 1020 (s), 967 (vw), 853 (vw), 840 (vw), 826 (vw),
00 (w), 785 (m), 754 (m), 673 (vw), 640 (w), 620 (vw), 587
1
87 °C. Anal. Calcd for C32
H
50TiBr
2
(642.44): C, 59.83; H, 7.84.
(
m), 540 (w), 507 (w), 447 (sh), 430 (s). UV-near-IR (n-hexane,
+
Found: C, 59.88; H, 7.97. MS (70 eV): m/z 642 ([M] ), 563
1
nm): 300 (sh) > 380 (sh) . 1055. H NMR: δ 0.13 (ddd, 1 H,
+
+
+
1
(
[M - Br] ), 507 ([M - Cp*] ), 299 ([M - Cp*TiBr
NMR: δ 0.97, 1.02 (2 s, 9 H each, (CH C), 1.76 (s, 3 H, CH
.99 (s, 15 H, (CH )C ), 2.12 (2 s, 3 H each, CH ), 2.11 (m, 1
H, CH B), 2.36 (dd, 1 H, J HH ) 12.5, J HH ) 15.8 Hz, CH A),
A), 2.99 (dd, 1
2
] ). H
3
J
HH ) 3.2, 8.7, 12.9 Hz, CH B), 0.42, 0.76 (2 × s, 9 H, (CH
3 3
) C),
3
)
3
3
),
3
0
.78, 0.83 (2 s, 3 H, CH
3
), 1.32 (dd, 1 H, J HH ) 2.7, 12.5 Hz,
1
3
5
3
2
η -CHdCH A), 1.39 (s, 3 H, CH
3
), 1.61 (s, 15 H, (CH
3
)C
5
), 2.64
3
2
2
3
2
(
dd, 1 H, J HH ) 9.8, J HH ) 13.7 Hz, CH A), 2.77 (dd, 1 H,
2
3
2
2
.84 (dd, 1 H, J HH ) 5.4, J HH ) 15.8 Hz, CH
2
3
2
3
J
J
J
HH ) 3.2, 12.5 Hz, η -CHdCH B), 3.50 (ddd, 1 H, J HH ) 8.7,
3
2
3
H, J HH ) 5.0, J HH ) 14 Hz, CH
2.5/8.6/5.4 Hz, CH A), 3.64 (t, 1 H, J HH ≈ J HH ≈ 14 Hz, CH
B), 5.34 (m, 1 H, dCH A), 5.36 (m, 1 H, dCH B). C{ H} NMR:
δ 13.1 (δ 1.76), 14.1 (δ 2.12), 14.2 ((CH ), 14.8 (δ 2.12),
0.97), 28.2 (δ 1.02), 30.4 (CH B and CH A), 33.4,
C), 45.4 (CH A), 52.4 (CH B), 128.8 ((CH ),
), 130.6 (dCH B),
2
B), 3.33 (ddd, 1 H, J HH )
2
2
3
HH ) 12.9, J HH ) 1.1 Hz, CH
2
B), 4.15 (dd, 1 H, J HH ) 7.4,
3
2
1
2
3
HH ) 13.7 Hz, CH A), 4.24 (ddd, 1 H, J HH ) 2.7, 7.4, 9.8
2
13
1
3
2
13
Hz, CH A), 4.37 (dd, 1 H, J HH ≈ J HH ≈ 12.9 Hz, CH
2
B). C-
H
H
3
)
5
C
5
H
1
{
H} NMR: δ 8.7 (δ
H
0.83), 9.3 (δ
H
0.78), 11.0 (δ
H
1.39) (3 ×
2
3
1
1
7.6 (δ
H
H
2
2
CH
2
6
(
1
3
);, 11.3 ((CH
8.7 ((CH C, δ
2.7 (CH A), 65.6 (CH B), 115.9, 119.4, 119.4 (3 × CCH
)C ), 122.5 (η -CHdCH B), 139.0,
3
)
5
C
5
), 27.1 ((CH
3
)
3
C, δ
H
0.42), 27.2 (CH
2
B),
5.4 (2 × (CH
3
)
3
3 5 5
) C
3
)
3
H
0.76), 32.1 (CH
2
A), 34.4, 36.4 (2 × (CH
3
)
3
C),
25.5, 129.4, 129.5, 131.6, 135.1 (5 × CCH
31.4 (dCH A).
3
3
), 119.4
2
2
η -CHdCH A), 119.7 ((CH
40.9 (2 × CCH ).
Syn th esis of 8a . F r om 6. Gaseous HCl (about 3 mmol) was
3
5
2
Ack n ow led gm en t. This work was supported by the
Max-Planck-Gesellschaft, the Fonds der Chemischen
Industrie, the Grant Agency of Academy of Sciences of
the Czech Republic (Grant No. A404004), and the Grant
Agency of the Czech Republic (Grant No 203/99/0846).
condensed into a cooled solution (-30 °C) of 6 (0.5 g, 1.04
mmol) in 30 mL of n-hexane. When the solution was warmed
to room temperature, the color changed from blue to red. After
concentration to about 3 mL and crystallization at -5 °C for
2
days, complex 8a formed fine brownish red needles, which
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement details, atomic coordinates,
bond lengths and angles, anisotropic displacement parameters,
and hydrogen coordinates for 7 and 8a ,b. This material is
available free of charge via the Internet at http://pubs.acs.org.
were filtered and dried under vacuum. Yield: 0.51 g (92%).
F r om 5. Complex 5 (0.36 g, 0.74 mmol) was dissolved in 25
mL of n-hexane under argon. After filtration of the yellow
solution it was treated with a solution of HCl in 1,4-dioxane
(
0.8 mL, 0.32 mmol). The color of the mixture rapidly changed
from yellow to red-brown. After 10 min the solvent was
OM000069F