Group 4 metallocene complexes of tris(trimethylsilyl)silylacetylene and related alkynes

Article abstract of DOI:10.1021/om800038h

Oligosilyl-substituted alkyne complexes of group 4 metallocenes have been prepared by reaction of group 4 metallocene dichlorides with magnesium in the presence of the respective alkyne. Depending on the alkyne substitution pattern, either metallacyclopentadienes or metallocene alkyne complexes were formed. In order to suppress the oxidative coupling process, PMe₃ was added to obtain the metallocene alkyne complex base adducts. The reaction of 1,4-bis[tris(trimethylsilyl)silyl]butadiyne with zirconocene caused the formation of a 1,4-bis[tris(trimethylsilyl)silyl]-substituted zirconacyclocumulene. Reactions of zirconacyclopentadienes with iodine proceeded to the expected 1,4-diiodobuta-1,3-dienes.

Full text of DOI:10.1021/om800038h

2570
Organometallics 2008, 27, 2570–2583
Group 4 Metallocene Complexes of Tris(trimethylsilyl)silylacetylene
and Related Alkynes
Michaela Zirngast, Christoph Marschner, and Judith Baumgartner*
Institut für Anorganische Chemie, Technische UniVersität Graz, Stremayrgasse 16, A-8010 Graz, Austria
ReceiVed January 15, 2008
Oligosilyl-substituted alkyne complexes of group 4 metallocenes have been prepared by reaction of
group 4 metallocene dichlorides with magnesium in the presence of the respective alkyne. Depending on
the alkyne substitution pattern, either metallacyclopentadienes or metallocene alkyne complexes were
formed. In order to suppress the oxidative coupling process, PMe3 was added to obtain the metallocene
alkyne complex base adducts. The reaction of 1,4-bis[tris(trimethylsilyl)silyl]butadiyne with zirconocene
caused the formation of a 1,4-bis[tris(trimethylsilyl)silyl]-substituted zirconacyclocumulene. Reactions
of zirconacyclopentadienes with iodine proceeded to the expected 1,4-diiodobuta-1,3-dienes.
extended also to hafnium complexes.6 In this connection an
Introduction
exciting Si-C activation process has been found that points to
Over the last years the chemistry of group 4 metallocenes
has experienced tremendous progress.1 Much of this advance-
ment was stimulated by studies related to novel Ziegler–Natta
catalysts.2 Besides the development of polymerization chemistry
also much fundamental metallocene alkyne complex chemistry
has been explored during this time. By the reaction of zir-
conocene dichloride with 2 equiv of butyl lithium Negishi
established the reagent that now bears his name.3 The weakly
coordinating butene ligand allowed the development of the rich
chemistry of the zirconocene fragment. With the introduction
of bis(trimethylsilyl)acetylene (BTMSA) group 4 metallocenes
recently Rosenthal has also advanced to a leading position in
this area. With these compounds many exciting stoichiometric
and catalytic reactions of titano- and zirconocene chemistry have
been studied.4
some differences in the chemical behavior of zirconium and
hafnium.7
During the past few years we have prepared several examples
of oligosilylalkynes, mainly with the intention to utilize them
for the synthesis of different silyl anions.8 In a recent paper we
have reported first results on the coordination behavior of these
oligosilylalkynes to dicobalt hexacarbonyl clusters.9 The most
interesting property of the obtained compounds was a strongly
enhanced reactivity of Si-Si bonds in the coordination sphere
of the dicobalt unit.
Encouraged by this study and the above-mentioned interaction
of zirconocene with the Si-H moiety attached to an alkyne5 as
well as by the recent example of hafnium Si-C activation7 we
decided to extend our research to the chemistry of group 4
metallocene complexes of oligosilylalkynes.
Our interest in Rosenthal’s chemistry has been raised by a
report about Zr-Si-H interaction in zirconocene complexes
of hydrosilyl-substituted alkynes.5 While most of the bis(trim-
ethylsilyl)acetylene group 4 metallocene chemistry was de-
scribed for titanium and zirconium, recently the field was
Results and Discussion
Tris(trimethylsilyl)silylalkyne Complexes. As has been
pointed out, group 4 metallocenes show a rich chemistry with
different alkynes. However, while numerous examples of
alkynes with different functional groups have been complexed
to titanocene and zirconocene, almost no examples containing
Si-Si bonds are known.10 Initial attempts to react bis[tris(tri-
methylsilyl)silyl]acetylene8 with Cp2MCl2 (M ) Ti, Zr) in the
presence of magnesium did not show any sign of the expected
* Corresponding author. Tel: ++43-316-873-8219. Fax: ++43-316-873-
8701. E-mail: baumgartner@tugraz.at.
(1) For an excellent compilation of recent group 4 metallocene chemistry
see: Titanium and Zirconium in Organic Synthesis; Marek, I., Ed.; Wiley-
VCH: Weinheim, Germany, 2002.
(2) Brintzinger, H. H.; Fischer, D.; Mülhaupt, R.; Rieger, B.; Waymouth,
R. Angew. Chem. 1995, 107, 1255–1283; Angew. Chem. Int. Ed. Engl. 1995,
34, 1143–1170.
(3) Negishi, E. I.; Cederbaum, R. E.; Takahashi, T. Tetrahedron Lett.
1986, 27, 2829–2832.
(6) Beweries, T.; Burlakov, V. V.; Bach, M. A.; Arndt, P.; Baumann,
W.; Spannenberg, A.; Rosenthal, U. Organometallics 2007, 26, 247–249.
(7) (a) Beweries, T.; Burlakov, V. V.; Bach, M. A.; Peitz, S.; Arndt, P.;
Baumann, W.; Spannenberg, A.; Rosenthal, U.; Pathak, B.; Jemmis, E. D.
Angew. Chem. 2007, 119, 7031–7035.
(4) For some reviews covering Rosenthal’s group 4 metallocene
bis(trimethylsilyl)acetylene chemistry see: (a) Rosenthal, U.; Burlakov,
V. V.; Bach, M. A.; Beweries, T. Chem. Soc. ReV. 2007, 36, 719–728. (b)
Rosenthal, U.; Burlakov, V. V.; Arndt, P.; Baumann, W.; Spannenberg, A.
Organometallics 2005, 24, 456–471. (c) Rosenthal, U.; Burlakov, V. V.;
Arndt, P.; Baumann, W.; Spannenberg, A. Organometallics 2003, 22, 884–
900. (d) Rosenthal, U.; Burlakov, V. V. In ref 1, Chapter 10, pp 355–389.
(e) Rosenthal, U.; Pellny, P. M.; Kirchbauer, F. G.; Burlakov, V. V. Acc.
Chem. Res. 2000, 33, 119–129. (f) Ohff, A.; Pulst, S.; Lefeber, C.; Peulecke,
N.; Arndt, P.; Burlakov, V. V.; Rosenthal, U. Synlett 1996, 111–118.
(5) (a) Ohff, A.; Kosse, P.; Baumann, W.; Tillack, A.; Kempe, R.; Görls,
H.; Burlakov, V. V.; Rosenthal, U. J. Am. Chem. Soc. 1995, 117, 10399–
10400. (b) Peulecke, N.; Ohff, A.; Kosse, P.; Baumann, W.; Tillack, A.;
Spannenberg, A.; Kempe, R.; Burlakov, V. V.; Rosenthal, U. Chem.-Eur.
J. 1998, 1852–1861.
(8) (a) Fischer, R.; Frank, D.; Gaderbauer, W.; Kayser, C.; Mechtler,
C.; Baumgartner, J.; Marschner, C. Organometallics 2003, 22, 3723–3731.
(b) Mechtler, C.; Zirngast, M.; Baumgartner, J.; Marschner, C. Eur. J. Inorg.
Chem. 2004, 3254–3261. (c) Mechtler, C.; Zirngast, M.; Gaderbauer, W.;
Wallner, A.; Baumgartner, J.; Marschner, C. J. Organomet. Chem. 2006,
691, 150–158.
(9) Zirngast, M.; Marschner, C.; Baumgartner, J. Organometallics 2006,
25, 4897–4908.
(10) The reactions of 1,2-dialkynyltetramethyldisilanes with zirconocene
are the only examples we are aware of: Kabe, Y.; Sato, A.; Kadoi, S.; Chiba,
K.; Ando, W. Chem. Lett. 2000, 1082–1083.
10.1021/om800038h CCC: $40.75
2008 American Chemical Society
Publication on Web 05/03/2008

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2571
Scheme 1. Reaction of Tris(trimethylsilyl)silylalkyne 1 with Zirconocene Dichloride and Magnesium
Scheme 2. Formation of Group 4 Metallocene Tris(trimethylsilyl)silylalkynyl Complexes
Scheme 3. Reversible Loss of THF Leading to a Dinuclear Zirconocene Vinyl Complex
adduct. Also efforts to react Cp2Ti(BTMSA)11 or Cp2Zr-
coupling product 2 even with only one stoichiometric equivalent
of alkyne present seems to be the higher reactivity of the
intermediately formed alkyne complex toward the alkyne
compared to the rate of reduction of the metallocene dichloride.
In order to avoid formation of the coupling product and to
obtain the zirconocene alkyne complex of 1, the reaction was
carried out in the presence of trimethylphosphane. Blocking the
coordination site thus led to the selective formation of the PMe3
adduct14 of the desired complex (6) (Scheme 2).
The formation of complexes of alkynes with tris(trimethyl-
silyl)silyl and phenyl substituents proceeded with both systems
to the expected complexes 4 and 5 (Scheme 2). In accordance
with Rosenthal’s results12 on BTMSA the zirconocene com-
pound 5 was obtained as the THF adduct.
Base adducts of zirconocene alkyne complexes can undergo
the reversible loss of the Lewis base. In order to avoid
coordinative unsaturation, oxidative addition into a neighboring
Cp-H takes place. This way a dinuclear compound is formed.12
Addition of a base leads to the reversal of the reaction. For the
case of 5 we encountered this reactivity pattern. This was
somewhat surprising, as we expected that oxidative addition of
the relatively weak Si-Si bond would be a possible alternative
to C-H activation. Nevertheless, the dinuclear C-H addition
product 7 was observed exclusively (Scheme 3).
(BTMSA) · THF12 with (Me3Si)3SiCCSi(SiMe3)3 did not lead
to the desired alkyne exchange. Similarly to the situation with
the dicobalt complexes,9 the reason for this failure was thought
to be the high steric demand of the two bulky tris(trimethylsi-
lyl)silyl groups. In order to determine the spatial requirements
of the system, we next investigated the reactivity of the
tris(trimethylsilyl)silyl-monosubstituted alkyne (1). Reaction of
1 with Cp2TiCl2 and magnesium could indeed be observed but
gave a mixture of two compounds, which we could not separate.
On the basis of NMR spectroscopic analysis it can be assumed
that the mixture consists of the alkyne complex and the
respective metallacyclopentadiene. Also the possibility of
formation of a vinylidene complex cannot be ruled out
completely, while formation of compounds containing the
13
structural unit TiCCSi(SiMe3)3 can be ruled out on the basis
of the spectroscopic analysis and independent synthesis. Repeat-
ing the experiment with the analogous zirconocene system led
to formation of the respective zirconacyclopentadiene (2)
exclusively (Scheme 1). The reason for the preference for the
(11) (a) Burlakov, V. V.; Rosenthal, U.; Petrovskii, P. V.; Shur, V. B.;
Vol’pin, M. E. Metalloorg. Khim. 1988, 1, 953–954. (b) Burlakov, V. V.;
Polyakov, A. V.; Yanovsky, A. I.; Struchkov, Yu. T.; Shur, V. B.; Vol’pin,
M. E.; Rosenthal, U.; Görls, H. J. Organomet. Chem. 1994, 476, 197–206.
(12) (a) Rosenthal, U.; Ohff, A.; Michalik, M.; Görls, H.; Burlakov,
V. V.; Shur, V. B. Angew. Chem. 1993, 105, 1228–1230. (b) Rosenthal,
U.; Ohff, A.; Michalik, M.; Görls, H.; Burlakov, V. V.; Shur, V. B.
Organometallics 1993, 12, 5016–5019.
In order to check also for the formation of related germyla-
lkynyl complexes, the reaction of the tris(trimethylsilyl)germyl
(13) (a) Sebald, A.; Fritz, P.; Wrackmeyer, B. Spectrochim. Acta 1985,
41A, 1405–1407. (b) Wood, G. L.; Knobler, C. B.; Hawthorne, M. F. Inorg.
Chem. 1989, 28, 382–384. (c) Lang, H.; Seyferth, D. Z. Naturforsch. B
1990, 45, 212–220.
(14) (a) Binger, P.; Müller, P.; Langhauser, F.; Sandmeyer, F.; Philipps,
P.; Gabor, B.; Mynott, R. Chem. Ber. 1993, 126, 1541–1550. (b) Binger,
P.; Sandmeyer, F.; Krüger, C.; Erker, G. Tetrahedron 1995, 51, 4277–4290.
(c) Erker, G.; Zwettler, R. J. Organomet. Chem. 1991, 409, 179–188.

2572 Organometallics, Vol. 27, No. 11, 2008
Scheme 4. Formation of a Tris(trimethylsilyl)germylalkyne Zirconocene Complex
Zirngast et al.
Scheme 5. No Complex Formation was Observed with Tris(trimethylsilyl)silyl(trimethylsilyl)acetylene (8)
Scheme 6. Complex Formation with Pentamethyldisilanyl-Substituted Alkynes 9 and 15
Scheme 7. Formation of Zirconacyclopentadiene 17
analogue (3a) of 3 was carried out with zirconocene dichloride/
magnesium. The expected product 5a was also obtained as the
THF adduct (Scheme 4).
observed formation of a substantial amount of a side-product
14, which turned out to be the known reduction product of
hafnocene dichloride in the presence of trimethylphosphane.15
Exchange of the phenyl group of 3 for a trimethylsilyl group
(8) did not lead to the formation of the expected complexes.
Apparently this change imposes too much steric demand onto
the system (Scheme 5).
Exchange of the trimethylsilyl group of 9 on one side of the
alkyne for phenyl (15) brought about the expected behavior.
Reaction of 15 with titanocene gave the alkyne complex 16
(Scheme 6). while, similar to the situation above, the reaction
with the zirconcene analogue gave the coupling product 17
exclusively (Scheme 7).
Pentamethyldisilanylalkyne Complexes. As 1-[tris(trimeth-
ylsilyl)silyl]-2-trimethylsilylethyne (8) seems to be too bulky
for complex formation, we settled for only one Si-Si bond and
employed 1-pentamethyldisilanyl-2-trimethylsilylethyne (9).
Reactions of 9 with titanocene and zirconocene dichlorides with
magnesium proceeded smoothly in both cases (10, 11) (Scheme
6). For the zirconium case again the THF adduct 11 was formed.
Loss of the donor during workup can lead to the same reversible
behavior as described above for 5. Also the trimethylphosphane
adduct (12) of the zirconocene was prepared (Scheme 6). As it
is known that hafnocene complexes are not easily formed
without an additional strong donor, we attempted the formation
of the hafnocene complex of 9 in the presence of trimethylphos-
phane.6 While the expected product 13 was obtained, we also
Repetition of the reaction in the presence of trimethylphos-
phane gave the base adduct of the zirconocene complex (18).
In contrast to the situation with 9 the reaction of 15 in the
presence of trimethylphosphane proceeded cleanly with hafnocene
dichloride (19) (Scheme 6).
In order to examine the reactivity of 19, its reaction with
another equivalent of 15 was investigated. While no conversion
could be observed at ambient conditions, raising the temperature
(15) Kool, L. B.; Rausch, M. D.; Alt, H. G.; Herberhold, M.; Thewalt,
U.; Honold, B. J. Organomet. Chem. 1986, 310, 27–34.

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2573
Scheme 8. Formation of Hafnacyclopentadiene 20 from Phosphane Adduct 19
Scheme 9. Formation of Fused Silacyclobutene Titanacyclobutene
Scheme 10. Formation of Oxidative Coupling Product 23 Followed by Reductive Cleavage and Rearrangement to 24
to 65 °C brought about complete formation of the hafnacyclo-
pentadiene 20 (Scheme 8).
would be obtained.18 However, the addition excess of the
zirconocene fragment seems to facilitate the intermediate
formation of a zirconocene alkyne complex, which subsequently
undergoes the same rearrangement process as described above
for the titanium species to give the rearranged product 24 in
analogy to the above-described formation of 22.
Reactions of diynes with group 4 metallocenes can lead to
several different structural motifs.1 One of those, namely, the
metallacyclocumulene structure19 (26) was observed in the
reaction of the 1,4-bis[tris(trimethylsilyl)silyl]butadiyne (25)
with zirconocene dichloride/magnesium (Scheme 11). Interest-
ingly, Rosenthal’s similar reaction of bis(trimethylsilyl)butadiyne
with zirconocene did not give the related metallacyclocumulene,
but its insertion product with bis(trimethylsilyl)butadiyne.19a
However, the change to the Cp* ligand facilitated the formation
Complexes with Other Oligosilylalkynes. The reactions of
1,1-bis(alkynyl)silanes with titanocene16 and zirconocene16b,17
fragments have been studied for several cases. The outcome of
the reaction of 21 with titanocene is characterized by the
formation of the silacyclobutene-annelated titanacyclobutene
complex 22 (Scheme 9). Related chemistry with zirconium was
discussed to involve either a zirconium vinylidene complex,
which would be formed via silyl migration, or a dialkyne
coupling product with a silapropane moiety.16a,17b The fact that
the trisilanyl unit of 21 is still intact after the rearrangement
seems to support the silapropane pathway in our case.
In contrast to the formation of titanacycle 22 the reaction of
21 with the zirconocene dichloride/magnesium system gave the
nonrearranged coupling product 23 (Scheme 10). An attempt
to react 23 further with additional zirconocene dichloride/
magnesium gave a clean product (24). As 23 still contains two
phenylalkynyl units, it was initially assumed that a macrocycle
(18) (a) Mao, S. S. H.; Tilley, T. D. J. Am. Chem. Soc. 1995, 117, 5365–
5366. (b) Mao, S. S. H.; Tilley, T. D. J. Am. Chem. Soc. 1995, 117, 7031–
7032. (c) Mao, S. S. H.; Liu, F.-Q.; Tilley, T. D. J. Am. Chem. Soc. 1998,
120, 1193–1206. (d) Liu, F.-Q.; Harder, G.; Tilley, T. D. J. Am. Chem.
Soc. 1998, 120, 3271–3272.
(19) (a) Rosenthal, U.; Ohff, A.; Baumann, W.; Kempe, R.; Tillack,
A.; Burlakov, V. V. Angew. Chem. 1994, 106, 1678–1680; Angew. Chem.,
Int. Ed. Engl. 1994, 33, 1605–1607. (b) Pellny, P.-M.; Kirchbauer, F. G.;
Burlakov, V. V.; Baumann, W.; Spannenberg, A.; Rosenthal, U. J. Am.
Chem. Soc. 1999, 121, 8313–8323. (c) Choukroun, R.; Donnadieu, B.; Zhao,
J.-S.; Cassoux, P.; Lepetit, C.; Silvi, B. Organometallics 2000, 19, 1901–
1911. (d) Suzuki, N.; Nishiura, M.; Wakatsuki, Y. Science 2002, 295, 660–
663. (e) Burlakov, V. V.; Arndt, P.; Baumann, W.; Spannenberg, A.;
Rosenthal, U. Organometallics 2004, 23, 4160–4165. (f) Burlakov, V. V.;
Arndt, P.; Baumann, W.; Spannenberg, A.; Rosenthal, U. Organometallics
2004, 23, 5188–5192. (g) Suzuki, N.; Watanabe, T.; Yoshida, H.; Iwasaki,
M.; Saburi, M.; Tezuka, M.; Hirose, T.; Hashizume, D.; Chihara, T. J.
Organomet. Chem. 2006, 691, 1175–1182. (h) Beweries, T.; Burlakov,
V. V.; Peitz, S.; Bach, M. A.; Arndt, P.; Baumann, W.; Spannenberg, A.;
Rosenthal, U. Organometallics 2007, 26, 6827–6831.
(16) (a) Horacek, M.; Stepnicka, P.; Gyepes, R.; Cisarova, I.; Kubista,
J.; Lenka Lukesova, L.; Meunier, P.; Mach, K. Organometallics 2005, 24,
6094–6103. (b) Horacek, M.; Bazyakina, N.; Stepnicka, P.; Gyepes, R.;
Cisarova, I.; Bredeau, S.; Meunier, P.; Kubista, J.; Mach, K. J. Organomet.
Chem. 2001, 628, 30–38. (c) Pellny, P.-M.; Peulecke, N.; Burlakov, V. V.;
Baumann, W.; Spannenberg, A.; Rosenthal, U. Organometallics 2000, 19,
1198–1200.
(17) (a) Xi, Z.; Fischer, R.; Hara, R.; Sun, W.-H.; Obora, Y.; Suzuki,
N.; Nakajima, K.; Takahashi, T. J. Am. Chem. Soc. 1997, 119, 12842–
12848. (b) Takahashi, T.; Xi, Z.; Obora, Y.; Suzuki, N. J. Am. Chem. Soc.
1995, 117, 2665–2666. (c) Yu, T.; Sun, X.; Wang, C.; Deng, L.; Xi, Z.
Chem.-Eur. J. 2005, 11, 1895–1902. (d) Liu, J.; Zhang, W.-X.; Guo, X.;
Hou, Z.; Xi, Z. Organometallics 2007, 26, 6812–6820.

2574 Organometallics, Vol. 27, No. 11, 2008
Scheme 11. Formation of a 2,5-Bis[tris(trimethylsilyl)silyl]zirconacyclopenta-2,3,4-triene (26)
Zirngast et al.
Scheme 12. Decomplexation of 2 and 17 with Either I2 or HCl, Yielding the Respective Buta-1,3-dienes 27, 28, and 29
Scheme 13. Reaction of 2 with Potassium tert-Butoxide to the Dipotassium Compound 30
Table 1. Selected Distances and Angles of Metallacyclopentadienes 2, 17, 20, and 23
compound
M-C
C-Si
Si-Si
C-Zr-C
2 (M ) Zr)
17 (M ) Zr)
20 (M ) Hf)
23 (M ) Zr)
2.241(8)/2.247(8)
2.248(6)
2.2350(19)
1.893(8)/1.886(9)
1.869(6)
1.879(2)
2.347(3) - 2.363(3)
2.365(3)
2.3547(8)
89.0(3)
84.2(3)
82.14(10)
79.26(14)
2.275(4)/2.271(4)
1.884(4)/1.873(4)
2.363(2) -2.3840(18)
of the structure.19b This seems to indicate that the steric
interaction (which prevents a successive insertion reaction)
between the Cp ligands and the tris(trimethylsilyl)silyl groups
is similar to that between the Cp* ligands and the trimethylsilyl
groups.
Derivatization Reactions. Reactions of the obtained zir-
conacyclopentadienes 2 and 17 with iodine proceeded cleanly
to the respective 1,4-diiodobuta-1,3-dienes (Scheme 12).20
Compound 17 was also converted to butadiene 29 by reaction
with hydrogen chloride.
The tris(trimethylsilyl)silyl groups attached to compounds
such as 2 raised the question whether it is possible to convert
them into silyl anions.21 Therefore, we reacted 2 with 2 equiv
of potassium tert-butoxide. Clean conversion to the respective
dianion 30 was observed (Scheme 13).
structure analysis. Table 1 comprises selected structural data
for the metallacyclopentadienes 2, 17, 20, and 23 (Figures 1, 8,
9, 11). Comparison with related structures in the Cambridge
Crystallographic Data Base22 revealed no unusual structural
properties. Si-Si bond lengths of all investigated compounds
are around 2.36 Å, which is typical for oligosilanes.
Table 2 contains a compilation of selected data of the
metallocene alkyne complexes 4, 6, 12, and 13 (Figures 2, 3,
5, 6) from this study. Again the structural features of the
investigated compounds are consistently within the ranges of
what was found for related compounds.22 It is interesting to
note how much the phosphane ligand influences the M-C bond.
In all cases the phosphane resides on the side of the metallocene,
where the smaller substituent of the alkyne resides. For
compound 6 (Figure 3) we do not observe an elongation of the
M-C bond next to the phosphane. In contrast the same bond
is significantly elongated for compounds 12 and 13. The reason
Crystal Structures. A substantial number of the compounds
described in this paper could be subjected to single-crystal
(20) Buchwald, S. L.; Nielsen, R. B. J. Am. Chem. Soc. 1989, 111, 2870–
2874.
(21) (a) Marschner, C. Eur. J. Inorg. Chem. 1998, 221–226. (b)
Marschner, C. Organometallics 2006, 25, 2110–2125.
(22) Related crystal structures from the Cambridge Crystallographic Data
Base were extracted using the Conquest V1.9 program.

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2575
Figure 1. Molecular structure and numbering of 2. Selected bond
lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(14)
2.241(8),Zr(1)-C(11)2.247(8),Si(1)-C(14)1.893(8),Si(1)-Si(2)
2.356(3), Si(1)-Si(3) 2.358(3), Si(5)-C(11) 1.886(9), Si(5)-Si(6)
2.347(3), C(11)-C(12) 1.364(12), C(12)-C(13) 1.484(12),
C(13)-C(14) 1.364(12), C(14)-Zr(1)-C(11) 89.0(3), C(14)-Si-
(1)-Si(2) 116.0(3), Si(2)-Si(1)-Si(3) 108.30(13), Si(2)-Si(1)-
Si(4)107.79(12),C(12)-C(11)-Si(5)115.2(6),C(12)-C(11)-Zr(1)
97.8(6), Si(5)-C(11)-Zr(1) 147.0(4), C(11)-C(12)-C(13)
127.6(8), C(11)-C(12)-Zr(1) 53.2(5), C(13)-C(12)-Zr(1)
74.4(5), C(14)-C(13)-C(12) 127.6(8), C(13)-C(14)-Si(1)
114.6(6), C(13)-C(14)-Zr(1) 97.9(6), Si(1)-C(14)-Zr(1)
147.4(5).
Figure 3. Molecular structure and numbering of 6. Selected bond
lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(11)
2.243(4),Zr(1)-C(12)2.249(4),P(1)-C(23)1.829(5),Si(1)-C(12)
1.867(5), Si(1)-Si(4) 2.3629(18), Si(2)-C(15) 1.872(5), C(11)-
C(12) 1.307(6), C(11)-Zr(1)-C(12) 33.82(16), C(23)-P(1)-Zr(1)
116.6(2), C(12)-Si(1)-Si(4) 109.40(15), Si(4)-Si(1)-Si(2)
109.64(7), C(12)-Si(1)-Si(3) 116.77(14), Si(4)-Si(1)-Si(3)
106.92(7), Si(2)-Si(1)-Si(3) 108.21(7), C(12)-C(11)-Zr(1)
73.4(3), C(11)-C(12)-Si(1) 134.1(4), C(11)-C(12)-Zr(1)
72.8(3), Si(1)-C(12)-Zr(1) 152.9(2).
Figure 4. Molecular structure and numbering of 7. Selected bond
lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(12)
2.238(3), Si(1)-C(11) 1.904(3), Si(1)-Si(4) 2.3606(13), Si(1)-
Si(3) 2.3618(12), Si(1)-Si(2) 2.3703(13), C(11)-C(12) 1.338(4),
C(12)-C(13) 1.462(4), Si(4)-Si(1)-Si(3) 109.17(5), C(11)-
Si(1)-Si(2) 113.55(10), C(12)-C(11)-Si(1) 137.4(2), C(12)-
C(11)-Zr(1) 58.29(17), Si(1)-C(11)-Zr(1) 164.19(16), C(11)-
C(12)-C(13) 128.7(3), C(11)-C(12)-Zr(1) 91.1(2), C(13)-
C(12)-Zr(1) 139.0(2).
Figure 2. Molecular structure and numbering of 4. Selected bond
lengths [Å] and bond angles [deg] with SDs: Ti(1)-C(12)
2.059(6), Ti(1)-C(11) 2.108(6), Si(1)-C(11) 1.882(6), Si(1)-Si(2)
2.353(3),C(11)-C(12)1.297(7),C(12)-C(13)1.457(8),C(12)-Ti-
(1)-C(11) 36.3(2), Si(2)-Si(1)-Si(4) 107.41(9), C(11)-Si(1)-
Si(3) 113.5(2), C(12)-C(11)-Si(1) 146.1(5), C(12)-C(11)-Ti(1)
69.8(4), Si(1)-C(11)-Ti(1) 143.9(4), C(11)-C(12)-C(13)
140.4(6), C(11)-C(12)-Ti(1) 73.9(4).
bond between the metal and the nonbridging carbon is slightly
longer compared to the bridging one. However, the difference
for the titanocene 22 (Figure 10) is not as pronounced as found
for a related Cp*2Ti system.16a The analogous zirconocene 24
(Figure 12) is structurally close to the compounds obtained from
tetraalkynylsilanes.16b The identity of zirconacyclocumulene 26
(Figure 13) could be established unambiguously, but unfortu-
nately, the poor quality of the structure solution does not allow
much further discussion. Only two 1,4-diiodo-buta-1,3-dienes23
for this is possibly a steric interaction of the PMe3 ligand with
the trimethylsilyl group.
For the dinuclear compound 7 (Figure 4) the structure is very
similar to the analogous compound derived from the THF adduct
of the bis(trimethylsilyl)acetylene zirconocene complex.12a The
vinylic hydrogen atom of 7 could be located. The dihafnium
compound 14 (Figure 7) is similar to the analogous dititanium
compound, which has been structurally characterized previ-
ously.15 The bicyclic compounds 22 and 24 (Figures 10 and
12) are structurally similar to what was found previously. The
(23) Yamamoto, Y.; Ohno, T.; Itoh, K. Chem.-Eur. J. 2002, 8, 4734–
4741.
(24) Erker, G.; Zwettler, R.; Krüger, C.; Hyla-Kryspin, I.; Gleiter, R.
Organometallics 1990, 9, 524–530.
(25) Jones, S. B.; Petersen, J. L. Organometallics 1985, 4, 966–971.

2576 Organometallics, Vol. 27, No. 11, 2008
Zirngast et al.
Figure 7. Molecular structure and numbering of 14. Selected
bond lengths [Å] and bond angles [deg] with SDs: Hf(1)-C(11)
2.283(9), Hf(1)-C(1) 2.358(9), Hf(1)-P(1) 2.652(3), Hf(2)-C(1)
2.294(9), Hf(2)-C(11) 2.359(9), Hf(2)-P(2) 2.664(3), P(1)-C(23)
1.819(10), P(2)-C(26) 1.810(10), C(11)-Hf(1)-C(1) 81.7(3),
C(11)-Hf(1)-P(1) 79.2(2), C(1)-Hf(2)-C(11) 81.4(3), C(11)-
Hf(2)-P(2) 120.4(2), Hf(2)-C(1)-Hf(1) 87.9(3), Hf(1)-C-
(11)-Hf(2) 88.1(3).
Figure 5. Molecular structure and numbering of 12. Selected
bond lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(12)
2.2268(18), Zr(1)-C(11) 2.3140(18), P(1)-C(22) 1.822(2),
Si(1)-C(12) 1.8532(18), Si(1)-Si(2) 2.3637(9), C(11)-C(12)
1.310(3), C(12)-Zr(1)-C(11) 33.46(6), C(12)-Si(1)-Si(2)
113.90(6), C(12)-C(11)-Si(3) 125.85(14), C(12)-C(11)-Zr(1)
69.61(10), Si(3)-C(11)-Zr(1) 163.61(10), C(11)-C(12)-Si(1)
146.36(14), C(11)-C(12)-Zr(1) 76.92(11), Si(1)-C(12)-Zr(1)
136.71(9).
Figure 8. Molecular structure and numbering of 17 (a molecule
of benzene was found to cocrystallize and is not shown). Selected
bond lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(1)
2.248(6), Si(1)-C(1) 1.869(6), Si(1)-C(14) 1.880(6), Si(1)-Si(2)
2.365(3), Si(2)-C(18) 1.886(8), C(1)-C(2) 1.360(8), C(2)-C(8)
1.506(8), C(2)-C(2A) 1.510(11), C(1A)-Zr(1)-C(1) 84.2(3),
C(1)-Si(1)-C(15) 109.9(3), C(1)-Si(1)-Si(2) 113.9(2), C(2)-C-
(1)-Si(1) 126.0(5), C(2)-C(1)-Zr(1) 104.3(4), Si(1)-C(1)-Zr(1)
129.6(3), C(1)-C(2)-C(8) 120.8(5), C(1)-C(2)-C(2A) 123.5(3),
C(8)-C(2)-C(2A) 115.5(3).
NMR Spectroscopy. For the characterization of metallocene
alkyne complexes and also metallacyclopentadienes 13C NMR
spectra are most useful. For the case of oligosilanes also 29Si
NMR spectroscopy provides some insight, as the 29Si NMR
shifts are quite sensitive to the hybridization state of an attached
carbon atom. Tables 3 and 4 contain compilations of some
relevant 13C and 29Si NMR resonances of compounds discussed
in this study as well as of some related compounds. For the
metallacyclopentadienes the 13C NMR shifts of the ring carbons
are within the range of related compounds. The metal connected
carbons resonate around 200 ppm, while Cꢀ shifts are around
150 ppm. Compound 2, which is derived from a monosubstituted
alkyne is different, as the resonances for CR (175 ppm) and Cꢀ
(128 ppm)25 are both shifted some 25 ppm to higher field. For
the metallacyclocumulenes derived from bis(trimethylsilyl)-
butadiyne and Cp*2M fragments 13C NMR resonances at 188.0
ppm (Zr) and 189.3 ppm (Hf) for the CR and 144.5 ppm (Zr)
Figure 6. Molecular structure and numbering of 13. Selected
bond lengths [Å] and bond angles [deg] with SDs: Hf(1)-C(15)
2.211(9), Hf(1)-C(14) 2.281(9), P(1)-C(13) 1.819(10), Si(1)-
C(15) 1.847(9), Si(1)-Si(2) 2.367(4), Si(3)-C(14) 1.856(9),
C(14)-C(15) 1.331(12), C(15)-Hf(1)-C(14) 34.4(3), C(15)-Si-
(1)-Si(2)114.8(3),C(14)-Si(3)-C(21)112.5(4),C(15)-C(14)-Si(3)
124.3(7), C(15)-C(14)-Hf(1) 69.9(5), Si(3)-C(14)-Hf(1)
164.8(5), C(14)-C(15)-Si(1) 146.1(8),C(14)-C(15)-Hf(1)
75.7(6), Si(1)-C(15)-Hf(1) 138.1(5).
have been structurally characterized so far. However, 27 (Figure
14) is different from the known examples, as it allows free
rotation around the bond C(2)-C(2A). The molecule adopts a
planar conformation with an anti-parallel arrangement of the
two C-I bonds.
(26) Lefeber, C.; Ohff, A.; Tillack, A.; Baumann, W.; Kempe, R.;
Burlakov, V. V.; Rosenthal, U.; Görls, H. J. Organomet. Chem. 1995, 501,
179–188.

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2577
Figure 11. Molecular structure and numbering of 23. Selected
bond lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(14)
2.271(4), Zr(1)-C(11) 2.275(4), Si(1)-C(33) 1.877(5), Si(1)-
C(11) 1.884(4), Si(1)-Si(2) 2.3753(19), Si(1)-Si(3) 2.3840(18),
C(9)-C(10) 1.331(11), C(11)-C(12) 1.355(5), C(12)-C(13)
1.504(5),C(13)-C(14)1.359(5),C(13)-C(21)1.496(6),C(14)-Zr-
(1)-C(11) 79.26(14), Si(2)-Si(1)-Si(3) 110.24(7), Si(1)-
C(11)-Zr(1) 125.8(2), Si(4)-C(14)-Zr(1) 124.8(2).
Figure 9. Molecular structure and numbering of 20. Selected
bond lengths [Å] and bond angles [deg] with SDs: Hf(1)-C(11)
2.2350(19), Si(1)-C(11) 1.879(2), Si(1)-Si(2) 2.3547(8),
C(11)-C(12)1.363(3),C(12)-C(12A)1.518(4),C(11)-Hf(1)-C(11A)
82.14(10), C(11)-Si(1)-C(16) 111.84(9), C(11)-Si(1)-Si(2)
118.92(6), C(16)-Si(1)-Si(2) 110.47(8), C(12)-C(11)-Si(1)
126.21(14), C(12)-C(11)-Hf(1) 107.57(13), Si(1)-C(11)-Hf(1)
126.21(10), C(11)-C(12)-C(12A) 121.36(11).
lylated cyclocumulene (176.2/131.4 ppm) 26 are again shifted
about 12 ppm to higher field. The similarity of the 13C NMR
resonances of 2 and 26 even for Cꢀ is somewhat surprising.
The 13C NMR resonances of alkyne complexes listed in Table
4 are in accordance with what has been found for other group
4 metallocene alkyne complexes. As found previously, the shifts
of the coordinated alkynes to lower field are strongest for
titanocene complexes. Accordingly the resonances of the
coordinated carbon atoms of compound 10 are as expected very
close to the shift of the analogous bis(trimethylsilyl)acetylene
complex. Also the zirconocene THF complex 11 resembles very
much the related THF BTMSA complex. The same is true for
the PMe3 complexes 12, 13, 18, and 19, which correspond to
the BTMSA and trimethylsilylphenylacetylene complexes. The
comparison of the zirconocene complexes 12 and 18 to the
analogous hafnocenes 13 and 19 shows that the latter exhibits
a downfield shift for both alkyne carbons of about 7 ppm. Finally
the disilanylphenylacetylene titanocene complex 16 resembles
the analogous trimethylsilylphenylacetylene complex.
The complexes containing tris(trimethylsilyl)silylalkynes (4,
5, 6) exhibit a similar behavior to the trimethylsilyl alkyne
complexes. However, the influence of the tris(trimethylsilyl)silyl
substituent on the shift of CR of the alkyne was found to be
weaker and that on Cꢀ to be stronger than that of the
trimethylsilyl group.8b Given for example the 13C NMR
resonances of 4, a comparison to 16 and the analogous
titanocene trimethylsilylphenylacetylene complex shows that a
similar effect of about the same size is also present for the
observed complexes.
The rearrangement products derived from 1,1-bis(phenyl-
ethynyl)silanes give a distinct pattern for the former alkynyl
carbons of resonances around 265, 210, 155, and 80 ppm for
the Cp2Ti fragment16 and 255, 210, 160, and 100 ppm for
Cp2Zr.17 Compounds 22 (Ti) and 24 (Zr) of this study also fall
into these ranges.
Figure 10. Molecular structure and numbering of 22. Selected bond
lengths [Å] and bond angles [deg] with SDs: Ti(1)-C(11) 2.030(7),
Ti(1)-C(20) 2.081(7), Ti(1)-C(19) 2.261(7), Si(1)-C(12) 1.939(8),
Si(1)-Si(2) 2.346(3), Si(1)-C(11) 2.377(7), C(11)-C(12) 1.317(9),
C(11)-C(19) 1.579(10), C(12)-C(13) 1.461(10), C(19)-C(20)
1.282(10), C(20)-C(21) 1.524(10), C(11)-Ti(1)-C(20) 76.8(3),
C(11)-Ti(1)-C(19) 42.8(3), C(20)-Ti(1)-C(19) 34.0(3),
C(19)-Si(1)-C(12) 75.1(3), C(19)-Si(1)-Si(2) 112.0(2),
C(12)-Si(1)-Si(2) 117.4(2), C(19)-Si(1)-Si(3) 117.5(2),
C(12)-Si(1)-Si(3) 111.1(2), C(19)-Si(1)-C(11) 41.5(3),
C(12)-Si(1)-C(11) 33.6(3), Si(3)-Si(1)-C(11) 119.75(18),
C(12)-C(11)-C(19) 107.0(7), C(12)-C(11)-Ti(1) 174.3(6),
C(19)-C(11)-Ti(1) 76.4(4), C(12)-C(11)-Si(1) 54.6(4),
C(19)-C(11)-Si(1) 52.4(4), Ti(1)-C(11)-Si(1) 128.8(4),
C(20)-C(19)-C(11) 126.0(7), C(20)-C(19)-Si(1) 147.6(6),
C(11)-C(19)-Si(1) 86.1(5), C(20)-C(19)-Ti(1) 65.3(4),
C(11)-C(19)-Ti(1) 60.8(3), Si(1)-C(19)-Ti(1) 146.8(5),
C(19)-C(20)-C(21) 128.0(7), C(19)-C(20)-Ti(1) 80.7(5).
Conclusion
and 144.9 ppm (Hf) for Cꢀ have been reported.19a,h Compared
to this, the respective resonances for the tris(trimethylsilyl)si-
The first examples of oligosilyl-substituted alkyne complexes
of group 4 metallocenes have been prepared by reaction of group

2578 Organometallics, Vol. 27, No. 11, 2008
Zirngast et al.
Table 2. Selected Distances and Angles of Metallocene Alkyne Complexes 4, 6, 12, and 13
compound
M-C(Si/C)
C-Si
Si-Si
C-Zr-C
4 (M ) Ti)
6 (M ) Zr)
12 (M ) Zr)
13 (M ) Hf)
2.108(6)/2.059(6)
2.249(4)/2.243(4)
2.2268(18)/2.3140(18)
2.211(9)/2.281(9)
1.882(6)
1.867(5)
1.8532(18)/1.8484(18)
1.847(9)/1.856(9)
2.353(3) - 2.361(3)
2.3629(18) - 2.3685(19)
2.3637(9)
36.3(2)
33.82(16)
33.46(6)
34.4(3)
2.367(4)
argon using either Schlenk techniques or a glovebox. Solvents were
dried using a column solvent purification system.28 Potassium tert-
butanolate was purchased from Merck. All other chemicals were
bought from different suppliers and were used without further
purification.
4 metallocene dichlorides with magnesium in the presence of
the respective alkyne. Depending on the alkyne substitution
pattern, either metallacyclopentadienes or metallocene alkyne
complexes were formed. In order to suppress the oxidative
coupling process, PMe3 was added to obtain the metallocene
alkyne complex base adducts. Despite some precedence indicat-
ing interaction of the metal with Si-H groups attached to the
alkyne, no Si-Si bond activation was observed during the study.
This was surprising, as intermolecular C-H activation was
observed in the cases of base loss of THF-stabilized zirconocene
complexes without any participation of Si-Si bonds. The
reaction of a 2,2-bis(alkynyl)trisilane led to a rearrangement
process, which again did not involve the polysilane moiety. The
reaction of 1,4-bis[tris(trimethylsilyl)silyl]butadiyne with zir-
conocene caused the formation of a 1,4-bis[tris(trimethylsilyl)-
silyl]-substituted zirconacyclocumulene. Reactions of two ex-
amples of zirconacyclopentadienes with iodine proceeded to the
expected 1,4-diiodobuta-1,3-dienes.
1H (300 MHz), 13C (75.4 MHz), 29Si (59.3 MHz), and 31P (124.4
MHz) NMR spectra were recorded on a Varian INOVA 300
spectrometer. If not noted otherwise for all samples, C6D6 was used
as solvent. To compensate for the low isotopic abundance of 29Si,
the INEPT pulse sequence was used for the amplification of the
signal.29 Completeness of conversion of the reactions was checked
by 29Si NMR spectroscopy using aliquots of the reactions mixture
Experimental Section
General Remarks. All reactions involving air-sensitive com-
pounds were carried out under an atmosphere of dry nitrogen or
Figure 13. Molecular structure and numbering of 26. Selected
bond lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(7)
2.270(15),Zr(1)-C(8)2.353(15),Si(1)-C(8)1.880(15),Si(1)-Si(4)
2.358(6), C(7)-C(7A) 1.27(3), C(7)-C(8) 1.32(2), C(7A)-
Zr(1)-C(7)32.5(7),C(7A)-Zr(1)-C(8A)33.1(5),C(7)-Zr(1)-C(8A)
65.6(5), C(7A)-Zr(1)-C(8) 65.6(5), C(7)-Zr(1)-C(8) 33.1(5),
C(8A)-Zr(1)-C(8) 98.7(8), Si(4)-Si(1)-Si(2) 110.4(2), Si(4)-
Si(1)-Si(3) 109.1(3), Si(2)-Si(1)-Si(3) 112.3(2), C(7A)-
C(7)-C(8) 150.6(9), C(7A)-C(7)-Zr(1) 73.7(4), C(8)-C(7)-Zr(1)
76.9(9), C(7)-C(8)-Si(1) 134.2(12), C(7)-C(8)-Zr(1) 70.0(9),
Si(1)-C(8)-Zr(1) 155.7(8).
Figure 12. Molecular structure and numbering of 24. Selected
bond lengths [Å] and bond angles [deg] with SDs: Zr(1)-C(11)
2.150(7),Zr(1)-C(13)2.184(7),Zr(1)-C(12)2.393(7),Si(1)-C(20)
1.876(7), Si(1)-C(12) 1.910(7), Si(1)-Si(3) 2.346(3), Si(1)-C(11)
2.381(7), C(11)-C(20) 1.354(9), C(11)-C(12) 1.583(10),
C(12)-C(13)1.328(9),C(13)-C(14)1.480(9),C(11)-Zr(1)-C(13)
73.7(3), C(11)-Zr(1)-C(12) 40.3(2), C(13)-Zr(1)-C(12) 33.3(2),
C(20)-Si(1)-C(12) 76.1(3), C(20)-Si(1)-Si(3) 117.9(2), C(12)-Si-
(1)-Si(3) 111.3(2), C(20)-Si(1)-Si(2) 112.0(2), C(12)-Si(1)-Si(2)
116.8(2), Si(3)-Si(1)-Si(2) 116.58(11), C(20)-Si(1)-C(11) 34.6(3),
C(12)-Si(1)-C(11) 41.5(3), Si(3)-Si(1)-C(11) 122.87(19),
Si(2)-Si(1)-C(11) 120.51(18), C(20)-C(11)-C(12) 105.0(6),
C(20)-C(11)-Zr(1) 174.6(6), C(12)-C(11)-Zr(1) 78.1(4), C(20)-
C(11)-Si(1)51.9(4),C(12)-C(11)-Si(1)53.1(3),Zr(1)-C(11)-Si(1)
131.2(3), C(13)-C(12)-C(11) 126.1(6), C(13)-C(12)-Si(1)
148.1(6), C(11)-C(12)-Si(1) 85.4(4), C(13)-C(12)-Zr(1) 64.7(4),
C(11)-C(12)-Zr(1) 61.5(3), Si(1)-C(12)-Zr(1) 146.8(4), C(12)-
C(13)-Zr(1) 82.0(4).
Figure 14. Molecular structure and numbering of 27. Selected
bond lengths [Å] and bond angles [deg] with SDs: Si(1)-C(1)
1.887(12), Si(1)-Si(4) 2.350(6), Si(1)-Si(3) 2.355(5), Si(1)-Si(2)
2.368(4), I(1)-C(1) 2.135(10), C(1)-C(2) 1.343(17), C(2)-
C(2A) 1.41(2), Si(4)-Si(1)-Si(3) 114.82(19), C(1)-Si(1)-Si(2)
106.9(4), Si(4)-Si(1)-Si(2) 111.18(19), Si(3)-Si(1)-Si(2)
107.98(17), C(2)-C(1)-Si(1) 126.9(9), C(2)-C(1)-I(1) 118.1(8),
Si(1)-C(1)-I(1) 115.0(6), C(1)-C(2)-C(2A) 130.2(15).

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2579
Table 3. Selected NMR Data of Metallacyclopentadienes Cp2M(RCCR′)2
compound (M, R, R′)a
13C M-C (δ, ppm)
13C Cp (δ, ppm)
29Si C-Si-Si (δ, ppm)
2 (Zr, Si4, H)
17 (Zr, Si2, Ph)
20 (Hf, Si2, Ph)
175.7/128.1
203.2/149.0
202.0/149.1
195.9/157.0
176.2/131.4
204.6/150.1
194.5/143.4
190.8/118.8
201.1/157.0
188.0/144.5
110.2
111.6
111.0
113.5
104.7
-76.9/–14.0
-33.7/–18.9
-31.8/–18.4
-76.0/–15.1
-82.4/–12.4
23 (Zr, Si3CC, Ph)
26 (Zr, Si4, cumulene))
(Zr, Si, Ph)24
(Zr, Ph, Ph),25,b
(Zr, Ph, H),25,c
(Zr, SiMe2CC, Ph)17d
(Zr, Si, cumulene)19b
112.6
a Si4 ) Si(SiMe3)3, Si3CC ) Si(SiMe3)2Ct CPh, Si2 ) SiMe2SiMe3, Si ) SiMe3. b Cp′ instead of Cp compounds listed. c Cp* instead of Cp
compound listed.
Table 4. Selected NMR Data of Metallocene Alkyne Complexes Cp2M(RCCR′)D
compound (M, R, R′, D)a
13C M-C (δ, ppm)
13C Cp (δ, ppm)
29Si C-Si-Si (δ, ppm)
29Si C-SiMe3(δ, ppm)
4 (Ti, Si4, Ph)
199.0/221.1
116.6
107.7
103.0
118.0
106.6
102.6
101.7
116.6
103.0
102.2
116.6
121.9
107.0
103.1
-84.2/–13.5
-85.6/–14.1
-85.2/–14.1
-33.2/–19.9
-28.5/–20.0
-27.9/–20.1
-25.9/–19.3
-32.9/–19.0
-26.9/–20.4
-25.2/–20.1
5 (Zr, Si4, Ph, THF)
6 (Zr, Si4, H, PMe3)
10 (Ti, Si2, Si)
11 (Zr, Si2, Si, THF)
12 (Zr, Si2, Si, PMe3)
13 (Hf, Si2, Si, PMe3)
16 (Ti, Si2, Ph)
185.4/195.9
172.7/170.6
243.8/241.9
214.3/208.8
202.0/175.5
210.4/182.5
212.0/219.8
180.2/176.4
187.0/181.7
213.0/219.6
248.5
-15.0
-11.5
-8.5
-6.6
18 (Zr, Si2, Ph, PMe3)
19 (Hf, Si2, Ph, PMe3)
(Ti, Si, Ph)26
(Ti, Si, Si)26
(Zr, Si, Si, THF12
(Zr, Si, Si, PMe3)14a
(Zr, Si, Ph, PMe3)14
(Ti, Ph, Ph)27
212.9
205.7/177.3
181.0/177.414c 182.5/177.614a
196.0
103.114c 103.614a
115.9
a Si4 ) Si(SiMe3)3, Si2 ) SiMe2SiMe3, Si ) SiMe3.
Table 5. Crystallographic Data for Compounds 2, 4, 6, 7, and 12
2
4
6
7
12
empirical formula
Mw
ZrSi8C32H66
766.79
TiSi4C27H42
526.87
ZrPSi4C24H47
570.17
Zr2Si8C54H84
1140.37
ZrPSi3C23H43
526.03
temperature [K]
size [mm]
cryst syst
space group
a [Å]
100(2)
100(2)
100(2)
100(2)
100(2)
0.33 × 0.26 × 0.18
monoclinic
C2/c
38.848(9)
9.374(2)
29.955(2)
90
123.61(2)
90
9058(4)
8
0.35 × 0.22 × 0.18
monoclinic
P2(1)
11.335(4)
10.597(3)
12.796(4)
90
94.356(5)
90
1532.6(8)
2
0.28 × 0.22 × 0.20
monoclinic
P2(1)/c
17.927(4)
11.581(2)
17.288(3)
90
118.57(3)
90
3152(2)
4
0.36 × 0.28 × 0.24
monoclinic
P2(1)/n
16.088(3)
10.731(2)
17.823(4)
90
105.34(3)
90
2967(2)
0.33 × 0.28 × 0.22
monoclinic
P2(1)/c
18.106(4)
10.444(2)
15.295(3)
90
98.92(3)
90
2857(2)
b [Å]
c [Å]
R [deg]
ꢀ [deg]
γ [deg]
V [Å3]
Z
2
6
Fcalc [g cm-3
]
1.121
0.472
3280
1.142
0.448
564
1.201
0.562
1208
1.276
0.545
1200
1.223
0.574
1112
absorp coeff [mm-1
F(000)
]
θ range
1.63 < θ < 23.50
1.80 < θ < 25.00
10 876/5284
2.18 < θ < 24.50
19 904/5235
1.52 < θ < 26.37
23 040/6050
2.26 < θ < 26.37
22 190/5831
no. of reflns collected/ 27 802/6727
unique
completeness to θ [%] 99.9
no. of data/restraints/ 6727/18/388
params
99.7
5284/1/299
99.8
5235/0/283
99.9
6050/0/302
99.8
5831/0/264
goodness of fit on F2 1.04
0.83
1.01
1.23
1.04
final R indices [I >
R1 ) 0.104, wR2 ) 0.251 R1 ) 0.068, wR2 ) 0.084 R1 ) 0.061, wR2 ) 0.135 R1 ) 0.050, wR2 ) 0.107 R1 ) 0.027, wR2 ) 0.067
2σ(I)]
R indices (all data)
R1 ) 0.133, wR2 ) 0.277 R1 ) 0.119, wR2 ) 0.095 R1 ) 0.079, wR2 ) 0.146 R1 ) 0.054, wR2 ) 0.109 R1 ) 0.031, wR2 ) 0.068
largest diff peak/hole 4.74/-1.24
0.43/-0.49
0.79/-0.89
0.85/-0.49
0.57/-0.24
[e–/Å3]
and D2O capillaries. Elementary analyses were carried out using a
Heraeus Vario Elementar with the addition of WO3 to suppress
SiC formation.
corrected for absorption effects with SAINT30 and SADABS,31
respectively. The structures were solved by direct methods and
refined by full-matrix least-squares method (SHELXL97).32 If
not noted otherwise, all non-hydrogen atoms were refined with
anisotropic displacement parameters. All hydrogen atoms were
located in calculated positions to correspond to standard bond
lengths and angles. All diagrams were drawn with 30% prob-
ability thermal ellipsoids, and all hydrogen atoms were omitted
X-Ray Structure Determination. For X-ray structure analyses
the crystals were mounted onto the tip of glass fibers, and data
collection was performed with a Bruker-AXS SMART APEX
CCD diffractometer using graphite-monochromated Mo KR
2
radiation (0.71073 Å). The data were reduced to Fo and

2580 Organometallics, Vol. 27, No. 11, 2008
Zirngast et al.
Table 6. Crystallographic Data for Compounds 13, 14, 17, 20, and 22
14 17 20
13
HfPSi3C23H43
613.30
22
empirical formula
Mw
Hf2P2C26H36
767.47
ZrSi4C42H56
764.45
HfSi4C36H50
773.61
TiSi3C32H38
554.79
temperature [K]
size [mm]
cryst syst
space group
a [Å]
100(2)
100(2)
100(2)
100(2)
100(2)
0.34 × 0.28 × 0.22
monoclinic
P2(1)/c
18.106(4)
10.445(2)
15.257(3)
90
99.06(3)
90
2849(2)
4
0.38 × 0.30 × 0.22
0.34 × 0.22 × 0.18
monoclinic
C2/c
19.608(4)
11.116(2)
19.047(4)
90
97.32(3)
90
4118(2)
4
0.34 × 0.26 × 0.22
monoclinic
C2/c
20.769(4)
11.323(2)
15.923(3)
90
103.04(3)
90
3648(2)
4
0.34 × 0.26 × 0.22
monoclinic
P2(1)/c
9.301(2)
31.000(6)
11.056(2)
90
108.86(3)
90
3017(2)
4
orthorhombic
Pccn
17.472(4)
22.229(4)
12.832(3)
90
90
90
7679(2)
8
2.046
8.466
2928
b [Å]
c [Å]
R [deg]
ꢀ [deg]
γ [deg]
V [Å3]
Z
Fcalc [g cm-3
]
1.430
3.851
1240
1.233
0.411
1616
1.409
3.014
1576
1.222
0.422
1176
absorp coeff [mm-1
F(000)
]
θ range
1.14 < θ < 25.00
1.48 < θ < 25.00
34 163/4394
2.09 < θ < 24.99
14 493/3624
2.01 < θ < 26.35
14 125/3699
2.05 < θ < 25.00
21 572/5295
no. of reflns collected/ 19 751/5009
unique
completeness to θ [%] 99.9
no. of data/restraints/ 5009/0/264
params
100
4394/0/277
99.8
3624/2/218
99.6
3699/0/202
99.9
5295/0/332
goodness of fit on F2 1.26
1.13
1.29
1.05
1.01
final R indices [I >
R1 ) 0.062, wR2 ) 0.111 R1 ) 0.047, wR2 ) 0.083 R1 ) 0.091, wR2 ) 0.171 R1 ) 0.017, wR2 ) 0.042 R1 ) 0.085, wR2 ) 0.153
2σ(I)]
R indices (all data)
R1 ) 0.072, wR2 ) 0.114 R1 ) 0.063, wR2 ) 0.089 R1 ) 0.108, wR2 ) 0.178 R1 ) 0.018, wR2 ) 0.042 R1 ) 0.186, wR2 ) 0.193
largest diff peak/hole 1.71/-4.05
1.91/-1.17
0.86/-1.62
0.71/-0.42
1.13/-0.61
[e–/Å3]
Table 7. Crystallographic Data for Compounds 23, 24, 26, and 27
23 24 26
27
empirical formula
Mw
ZrSi6C54H66
974.83
ZrSi3C32H38
598.11
ZrSi8C32H64
764.77
Si8I2C22H56
799.19
temperature [K]
size [mm]
cryst syst
space group
a [Å]
100(2)
100(2)
100(2)
200(2)
0.30 × 0.25 × 0.20
0.33 × 0.26 × 0.18
0.36 × 0.22 × 0.18
0.30 × 0.20 × 0.15
monoclinic
monoclinic
orthorhombic
triclinic
j
P2(1)/c
19.039(4)
P2(1)/c
9.2332(2)
Ama2
28.738(6)
P1
8.7389(2)
b [Å]
9.6121(2)
31.118(6)
16.791(6)
9.4834(2)
c [Å]
30.102(6)
11.252(2)
9.5167(2)
13.512(3)
R [deg]
90
93.73(3)
90
5497(2)
90
109.38(3)
90
3050(2)
90
90
90
4592(2)
97.87(3)
92.04(3)
117.03(3)
982(4)
ꢀ [deg]
γ [deg]
3
V [Å
]
Z
4
4
4
1
Fcalc [g cm-3
]
1.178
0.363
2056
1.303
0.497
1248
1.106
0.467
1632
1.351
1.856
406
absorp coeff [mm-1
F(000)
]
θ range
1.67 < θ < 25.38
39 551/10 032
99.2
10 032/0/562
0.96
2.03 < θ < 26.31
18 254/5910
95.4
5910/0/331
0.98
2.43 < θ < 23.00
13 467/3271
99.9
3271/37/200
1.20
2.45 < θ < 24.49
no. of reflns collected/unique
completeness to θ [%]
5945/3184
97.5
3184/0/145
1.00
no. of data/restraints/params
goodness of fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
R1 ) 0.061, wR2 ) 0.126
R1 ) 0.121, wR2 ) 0.149
0.40/-0.33
R1 ) 0.082, wR2 ) 0.146
R1 ) 0.162, wR2 ) 0.173
0.84/-1.15
R1 ) 0.135, wR2 ) 0.285
R1 ) 0.144, wR2 ) 0.291
1.13/-1.97
R1 ) 0.085, wR2 ) 0.201
R1 ) 0.135, wR2 ) 0.226
2.27/-2.09
largest diff peak/hole [e-/Å3]
for clarity. Unfortunately the obtained crystal quality of some
substances was poor. This fact is reflected by quite high R and
low θ values.
Pentamethyl(trimethylsilylethynyl)disilane (9),33 pentameth-
yl(phenylethynyl)disilane (15),34 tris(trimethylsilyl)silylethyne (1),35
Crystallographic data (excluding structure factors) for the
structures of compounds 2, 4, 6, 7, 12, 13, 14, 17, 20, 22, 23, 24,
26, and 27 reported in this paper have been deposited with the
Cambridge Crystallographic Data Center as supplementary publica-
tion nos. CCDC-664708 (2), 668145 (4), 664709 (6), 664710 (7),
664714 (12), 664712 (13), 664713 (14), 664706 (17), 666457 (20),
664711 (22), 664707 (23), 670068 (24), 670067 (26), and 664715
(27). Copies of the data can be obtained free of charge from
www.ccdc.cam.ac.uk/products/csd/request.
(28) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518–1520.
(29) (a) Morris, G. A.; Freeman, R. J. Am. Chem. Soc. 1979, 101, 760–
762. (b) Helmer, B. J.; West, R. Organometallics 1982, 1, 877–879.
(30) SAINTPLUS: Software Reference Manual, Version 6.45; Bruker-
AXS: Madison, WI, 1997–2003.
(31) Blessing, R. H. Acta Crystallogr. A 1995, 51, 33–38; SADABS,
Version 2.1; Bruker AXS, 1998.
(32) Sheldrick, G. M. Acta Crystallogr. A 2008, 64, 112–122.
(33) Kerst, C.; Rogers, C. W.; Ruffolo, R.; Leigh, W. J. J. Am. Chem.
Soc. 1997, 119, 466–471.
(34) Ishikawa, M.; Sugisawa, H.; Fuchikami, T.; Kumada, M.; Yamabe,
T.; Kawakami, H.; Fukui, K.; Ueki, Y.; Shizuka, H. J. Am. Chem. Soc.
1982, 104, 2872–2878.
(27) Shur, V. B.; Burlakov, V. V.; Vol’pin, M. E. J. Organomet. Chem.
1988, 347, 77–83.

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2581
tris(trimethylsilyl)silylphenylacetylene (3),8b and 2,2-bis(phenyla-
lkynyl)hexamethyltrisilane (21)8b were prepared according to
published procedures.
ppm): 195.9; 185.4; 156.9; 127.6; 123.3; 122.2; 107.7 (Cp); 75.3
(THF); 25.7 (THF); 2.5 (SiMe3). Anal. Calcd for C31H50OSi4Zr
(642.29): C 57.97, H 7.85. Found: C 57.92, H 7.83.
As a result of THF dissociation in the NMR solution, colorless
crystals of compound 7 precipitated. If the removal of THF was
forced by subjecting a vacuum to a solution of 5, the dimerization
product 7 was formed quantitatively. Addition of THF caused
regeneration of 5.
Due to the very poor solubility of 7 in noncoordinating solvents,
only proton NMR data could be obtained. 7: 29Si NMR (δ ppm):
-14.3 (SiMe3); -88.6. 1H NMR (δ ppm): 7.20-6.90 (m, 12H,
2× Ph and dCH); 6.24 (s, 10H, Cp); 6.00 -5.70 (m, 8H, C5H4);
0.26 (s, 54H, SiMe3). Anal. Calcd for C54H84Si8Zr2 (1140.38): C
56.87, H 7.42. Found: C 56.67, H 7.31.
Preparation of Starting Materials. Tris(trimethylsilyl)-
germylphenylacetylene (3a). At -70 °C methyl lithium (5% in
Et2O, 59 mg, 2.702 mmol) was added to a solution of phenylacety-
lene (276 mg, 2.702 mmol) in Et2O (15 mL). After complete
addition the reaction was stirred at rt for 18 h, and a precipitate
was formed. The formed suspension was added dropwise at -70
°C to a solution of tris(trimethylsilyl)germyl chloride (843 mg, 2.573
mmol) in Et2O (30 mL). Stirring was continued for 2 days at rt
before the reaction was complete. The mixture was poured onto
degassed ice-cold 0.5 M H2SO4 for workup. After drying with
sodium sulfate and evaporation of the solvent 3a (907 mg, 90%)
1
was afforded as a light yellow oil. 29Si NMR (δ ppm): -4.9. H
Reaction of Tris(trimethylsilyl)germylphenylacetylene with
Cp2ZrCl2 (5a): Reaction was done analogously to the preparation
of 2 using tris(trimethylsilyl)germylphenylacetylene (3a) (100 mg,
0.254 mmol), Cp2ZrCl2 (74 mg, 0.254 mmol), and Mg turnings (7
mg, 0.288 mmol). 5a (81 mg, 47%) was obtained as a red solid
(using pentane instead of heptane). 29Si NMR (δ ppm): -8.1
NMR (δ ppm): 7.45 (m, 2H); 7.30 (m, 3H); 0.37 (s, 27H, 3xSiMe3).
13C NMR (δ ppm): 132.0; 128.3; 127.4; 125.5; 106.8; 89.6; 1.4.
Anal. Calcd for C17H32GeSi3 (393.30): C 51.91, H 8.20. Found: C
51.33, H 8.18.
1,4-Bis[tris(trimethylsilyl)silyl]butadiyne (25). To a solution
of 1,4-bis(trimethylsilyl)butadiyne (833 mg, 4.28 mmol) in THF
(10 mL) was added at once potassium tert-butoxide (1.00 g, 8.91
mmol). After 30 min the reaction mixture was cooled to -50 °C
and chlorotris(trimethylsilyl)silane (2.42 g, 8.54 mmol) in THF (10
mL) was added dropwise. Stirring was continued for 12 h at 0 °C
and a further 48 h at rt. The solvent was removed and the residue
extracted with toluene (30 mL). After evaporation of the solvent
and flash chromatography with heptane 25 (1.68 g, 73%) was
obtained as a slight yellow solid (mp: 148-150 °C). 29Si NMR (δ
ppm): -11.5; -100.5. 1H NMR (δ ppm): 0.16 (s, 54H). 13C NMR
(δ ppm): 93.4; 79.2; 0.4. Anal. Calcd for C22H54Si8 (543.35): C
48.63, H 10.02. Found: C 48.27, H 9.89.
1
(SiMe3). H NMR (δ ppm): 7.20 (m, 2H); 6.94 (m, 3H); 5.76 (s,
10H, Cp); 3.21 (m, 4H, THF); 1.08 (m, 4H, THF); 0.39 (s, 27H,
SiMe3). Anal. Calcd for C31H50GeOSi3Zr (686.82): C 54.21, H 7.34.
Found: C 53.69, H 7.41. The removal of the solvent under vacuum
from a solution of 5a also caused formation of the dimerization
product 7a.
Reaction of Tris(trimethylsilyl)silylethyne with Cp2ZrCl2
and PMe3 (6). Reaction was done analogously to the preparation
of 2 using tris(trimethylsilyl)silylethyne (1) (150 mg, 0.550 mmol),
Cp2ZrCl2 (161 mg, 0.550 mmol), PMe3 (42 mg, 0.550 mmol), and
Mg turnings (14 mg, 0.576 mmol). Green crystals of 6 (163 mg,
52%) were obtained. 29Si NMR (δ ppm): -14.1; -85.2 (d, J )
5.6 Hz). 1H NMR (δ ppm): 8.76 (d, J ) 3.4 Hz, 1H); 5.24 (d, J )
1.8 Hz, 10H, Cp); 0.93 (d, J ) 5.9 Hz, 9H, PMe3); 0.41 (s, 27H,
SiMe3). 13C NMR (δ ppm): 172.7 (d, J ) 8.9 Hz); 170.6 (d, J )
27.4 Hz); 103.0 (Cp); 16.6 (d, J ) 17.9 Hz, PMe3); 1.7 (SiMe3)
31P NMR (δ ppm): 4.8. Anal. Calcd for C24H47PSi4Zr (570.17): C
50.56, H 8.31. Found: C 50.62, H 8.57.
Reaction of Pentamethyl(trimethylsilylethynyl)disilane with Cp2-
TiCl2 (10). Reaction was done analogously to the preparation of 2
using pentamethyl(trimethylsilylethynyl)disilane (9) (150 mg, 0.656
mmol), Cp2TiCl2 (163 mg, 0.656 mmol), and Mg turnings (16 mg,
0.658 mmol). 10 (157 mg, 59%) was obtained as a red oil. 29Si
NMR (δ ppm): -15.0 (C-SiMe3); -19.9 (Me3SiSiMe2-); -33.2
(SiMe2). 1H NMR (δ ppm): 6.44 (s, 10H, Cp); 0.09 (s, 9H, SiMe3);
-0.36 (s, 9H, C-SiMe3); -0.44 (s, 6H, SiMe2). 13C NMR (δ ppm):
243.8; 241.9; 118.0; 0.6; -1.6; -1.7. Anal. Calcd for C20H34Si3Ti
(406.61): C 59.08, H 8.43. Found: C 58.47, H 8.42.
Reaction of Pentamethyl(trimethylsilylethynyl)disilane with Cp2-
ZrCl2 (11). Reaction was done analogously to the preparation of 2
using pentamethyl(trimethylsilylethynyl)disilane (9) (100 mg, 0.875
mmol), Cp2ZrCl2 (256 mg, 0.875 mmol), and Mg turnings (22 mg,
0.905 mmol). A turquoise oil of 11 (68%, 312 mg) was obtained.
29Si NMR (THF/D2O, δ ppm): -11.5 (SiMe3); -20.0 (SiMe3);
-28.5 (SiMe2). 1H NMR (δ ppm): 5.69 (s, 10H, Cp); 3.78 (m,
THF); 1.90 (m, THF); 0.32 (s, 6H, SiMe2); 0.25 (s, 9H, SiMe3);
0.19 (s, 9H, SiMe3). 13C NMR (δ ppm): 214.3; 208.8; 106.6; 67.8;
25.8; 2.0; 0.3; -1.1. Anal. Calcd for C24H42OSi3Zr (522.07): C
55.21, H 8.11. Found: C 54.50, H 8.17.
Metallocene Complexes. Reaction of Tris(trimethylsilyl)-
silylethyne with Cp2ZrCl2 (2). To a solution of tris(trimethylsi-
lyl)silylethyne (1) (200 mg, 0.733 mmol) and Cp2ZrCl2 (214 mg,
0.733 mmol) in THF (4 mL) were added Mg turnings (18 mg, 0.740
mmol). The reaction mixture was stirred for 18 h, after which the
precipitate was removed by centrifugation. After evaporation of
the solvent the residue was treated with heptane, and again the
precipitate was removed by centrifugation. Cooling to -70 °C
afforded yellow-green crystals of 2 (298 mg, 53%; mp: 151-155
°C). 29Si NMR (δ ppm): -14.0 (SiMe3); -76.9. 1H NMR (δ ppm):
5.98 (s, 10H, Cp); 5.87 (s, 2H); 0.34 (s, 54H, SiMe3). 13C NMR (δ
ppm): 175.7; 128.1; 110.2 (Cp); 2.0 (SiMe3). Anal. Calcd for
C32H66Si8Zr (766.77): C 50.12, H 8.68. Found: C 49.73, H 8.81.
Reaction of Tris(trimethylsilyl)silylphenylacetylene with
Cp2TiCl2 (4). Reaction was done analogously to the preparation
of 2 using tris(trimethylsilyl)silylphenylacetylene (3) (100 mg, 0.287
mmol), Cp2TiCl2 (71 mg, 0.287 mmol), and Mg turnings (7 mg,
0.288 mmol), and stirring was continued for 3 days. Orange crystals
of 4 (43 mg, 28%) were obtained (using pentane instead of heptane).
29Si NMR (δ ppm): -13.5 (SiMe3), -84.2. 1H NMR (δ ppm): 7.03
(m, 2H); 6.83 (m, 1H); 6.48 (m, 2H); 6.33 (s, 10H, Cp); 0.12 (s,
27H, SiMe3). 13C NMR (δ ppm): 222.1; 199.0; 143.8; 127.8; 125.0;
125.4; 116.6 (Cp); 1.8 (SiMe3). Anal. Calcd for C27H42Si4Ti
(526.86): C 61.55, H 8.04. Found: C 60.82, H 8.15.
Reaction of Tris(trimethylsilyl)silylphenylacetylene with
Cp2ZrCl2 (5, 7). Reaction was done analogously to the preparation
of 2 using tris(trimethylsilyl)silylphenylacetylene (3) (200 mg, 0.573
mmol), Cp2ZrCl2 (152 mg, 0.521 mmol), and Mg turnings (13 mg,
0.535 mmol). Yellow crystals of 5 (274 mg, 82%) were obtained
from benzene. 29Si NMR (δ ppm): -14.1 (SiMe3); -85.6. 1H NMR
(δ ppm): 7.20 (m, 2H); 6.93 (m, 3H); 5.77 (s, 10H, Cp); 3.12 (m,
4H, THF); 0.95 (m, 4H, THF); 0.35 (s, 27H, SiMe3). 13C NMR (δ
Reaction of Pentamethyl(trimethylsilylethynyl)disilane with Cp2-
ZrCl2 and PMe3 (12). Reaction was done analogously to the
preparation of 2 using pentamethyl(trimethylsilylethynyl)disilane
(9) (100 mg, 0.438 mmol), Cp2ZrCl2 (128 mg, 0.438 mmol), PMe3
(33 mg, 0.438 mmol), and Mg turnings (11 mg, 0.453 mmol).
Orange crystals of 12 (163 mg, 71%) were obtained (using pentane
instead of heptane). 29Si NMR (δ ppm): -8.5 (t C-SiMe3); -20.1
(SiMe3); -27.9 (d, J ) 3.8 Hz, -SiMe2-). 1H NMR (δ ppm):
(35) Fischer, R.; Frank, D.; Gaderbauer, W.; Kayser, C.; Mechtler, C.;
Baumgartner, J.; Marschner, C. Organometallics 2003, 22, 3723–3731.

2582 Organometallics, Vol. 27, No. 11, 2008
Zirngast et al.
5.14 (d, J ) 1.2 Hz, 10H, Cp); 1.05 (d, J ) 5.5 Hz, 9H, PMe3);
123.4; 122.0; 102.2 (Cp); 17.5 (d, J ) 18.3 Hz, PMe3), -0.3
(SiMe2); -1.5 (SiMe3). 31P NMR (δ ppm): -8.7. Anal. Calcd for
C26H39HfPSi2 (617.22): C 50.59, H 6.37. Found: C 50.55, H 6.28.
Repeating the experiment at rt after 3 days the solution contained
a mixture of complex 19 and pentamethyl(phenylethynyl)disilane
in a 1:1 ratio, and also some 14 could be observed. The solution
was then heated to reflux for 14 h and cooled to rt, and the solvent
was removed. The residue was twice treated with pentane and the
precipitate removed by centrifugation. Slight yellow crystals of 20
(65 mg, 39%) were obtained from the pentane solution at rt. 29Si
NMR (δ ppm): -18.4 (SiMe3); -31.8 (SiMe2). 1H NMR (δ ppm):
6.82 (m, 4H); 6.72 (m, 2H); 6.64 (m, 2H); 6.11 (s, 10H, Cp); 0.09
(s, 18H, SiMe3); -0.07 (s, 12H, SiMe3). 13C NMR (δ ppm): 202.0
149.1; 147.0; 132.1; 129.9; 127.1; 111.0 (Cp); 1.6 (SiMe2); -0.5
(SiMe3). Anal. Calcd for C36H50HfSi4 (773.61): C 55.89, H 6.51.
Found: C 55.60, H 6.52.
0.59 (s, 6H, SiMe2); 0.29 (s, 9H, SiMe3); 0.28 (s, 9H, SiMe3). 13
C
NMR (δ ppm): 202.0 (d, J ) 4.0 Hz); 175.5 (d, J ) 11.2 Hz);
102.6 (Cp); 18.7 (d, J ) 15.6 Hz, PMe3); 3.2; 1.3; -0.5. 31P NMR
(δ ppm): 2.1. Anal. Calcd for C23H43PSi3Zr (526.05): C 52.51, H
8.24. Found: C 52.01, H 8.14.
Reaction of Pentamethyl(trimethylsilylethynyl)disilane with Cp2-
HfCl2 and PMe3 (13 and Hf complex 14). Reaction was done
analogously to the preparation of 2 using pentamethyl(trimethyl-
silylethynyl)disilane (9) (150 mg, 0.656 mmol), Cp2HfCl2 (249 mg,
0.656 mmol), PMe3 (50 mg, 0.656 mmol), and Mg turnings (16
mg, 0.658 mmol). Yellow crystals of 13 (84 mg, 21%) were
obtained together with red crystals of 14. 13: 29Si NMR (δ ppm):
-6.6 (d, J ) 2.8 Hz, SiMe3); - 19.3 (SiMe3); -25.9 (d, J ) 4.0
1
Hz, SiMe2). H NMR (δ ppm): 5.05 (d, J ) 1.6 Hz, 10H, Cp);
1.12 (d, J ) 5.8 Hz, PMe3); 0.60 (s, 6H); 0.28 (s, 9H); 0.26 (s,
9H). 13C NMR (δ ppm): 210.4 (d, J ) 5.2 Hz); 182.5 (d, J ) 8.2
Reaction of 2,2-Bis(phenylalkynyl)hexamethyltrisilane with
Cp2TiCl2 (22). Reaction was done analogously to the preparation
of 2 using 2,2-bis(phenylalkynyl)hexamethyltrisilane (21) (150 mg,
0.398 mmol), Cp2TiCl2 (99 mg, 0.398 mmol), and Mg turnings
(10 mg, 0.411 mmol). Orange crystals of 22 (117 mg, 53%) were
obtained. 29Si NMR (δ ppm): -15.7 (SiMe3); -58.3. 1H NMR (δ
ppm): 7.93 (m, 24H); 7.67 (m, 28H); 7.43 (m, 3H); 7.36 (m, 3H);
5.38 (s, 10H, Cp); 0.21 (s, 36H, SiMe3). 13C NMR (δ ppm): 256.3;
212.0; 146.0; 141.5; 140.9; 129.3; 128.9; 128.6; 127.8; 126.8; 126.7;
105.8; 72.0; -0.1. Anal. Calcd for C32H38Si3Ti (554.77): C 69.28,
H 6.90. Found: C 68.81, H 6.82.
Hz); 101.7 (Cp); 19.6 (d, J ) 18.6 Hz, PMe3); 3.4; 1.6; -0.4. 31
P
NMR (δ ppm): -8.9. Anal. Calcd for C23H43HfPSi3 (613.31): C
45.04, H 7.07. Found: C 44.49, H 7.13.
Reaction of Pentamethyl(phenylethynyl)disilane with Cp2TiCl2
(16). Reaction was done analogously to the preparation of 2 using
pentamethyl(phenylethynyl)disilane (15) (100 mg, 0.430 mmol),
Cp2TiCl2 (107 mg, 0.430 mmol), and Mg turnings (11 mg, 0.452
mmol). 16 (83 mg, 47%) was obtained as a red oil. 29Si NMR (δ
ppm): -19.0 (SiMe3); -32.9 (SiMe2). 1H NMR (δ ppm): 7.00 (m,
2H); 6.87 (m, 1H); 6.32 (s, 10H, Cp); 6.18 (m, 2H); 0.11 (s, 9H,
SiMe3); -0.21 (s, 6H, SiMe2). 13C NMR (δ ppm): 219.8; 212.0;
142.5; 128.7; 126.6; 126.0; 116.6 (Cp); -1.4 (SiMe3); -1.8 (SiMe2).
Anal. Calcd for C23H30Si2Ti (410.52): C 67.29, H 7.37. Found: C
66.90, H 7.44.
Reaction of 2,2-Bis(phenylalkynyl)hexamethyltrisilane with
Cp2ZrCl2 (23). Reaction was done analogously to the preparation
of 2 using 2,2-bis(phenylalkynyl)hexamethyltrisilane (21) (150 mg,
0.398 mmol), Cp2ZrCl2 (58 mg, 0.199 mmol), and Mg turnings (5
mg, 0.205 mmol). Yellow crystals of 23 (120 mg, 62%) were
obtained. 29Si NMR (δ ppm): -15.1 (SiMe3); -76.0. 1H NMR (δ
ppm): 7.48 (m, 4H); 7.04 (m, 8H); 6.78 (m, 8H); 6.61 (s, 10H,
Cp); 0.29 (s, 36H, SiMe3). 13C NMR (δ ppm): 195.9; 157.0; 147.9;
131.7; 128.9; 128.8; 127.8; 125.5; 124.9; 113.5 (Cp); 110.1; 100.2;
0.8 (SiMe3). Anal. Calcd for C54H66Si6Zr (974.84): C 66.53, H 6.82.
Found: C 65.94, H 6.88.
Reaction of Pentamethyl(phenylethynyl)disilane with Cp2ZrCl2
(17). Reaction was done analogously to the preparation of 2 using
pentamethyl(phenylethynyl)disilane (15) (200 mg, 0.860 mmol),
Cp2ZrCl2 (229 mg, 0.782 mmol), and Mg turnings (21 mg, 0.864
mmol). Orange crystals of 17 were obtained (224 mg, 76%) (using
pentane instead of heptane). 29Si NMR (δ ppm): -18.9 (SiMe3);
1
-33.7. H NMR (δ ppm): 6.82 (m, 4H); 6.71 (m, 2H); 6.62 (m,
4H); 6.18 (s, 10H, Cp); 0.08 (s, 18H, SiMe3); -0.09 (s, 12H, SiMe2).
13C NMR (δ ppm): 203.2; 149.0; 146.4; 129.7; 127.1; 125.1; 111.6
(Cp); 1.4 (SiMe2); -0.6 (SiMe3). Anal. Calcd for C36H50Si4Zr
(686.35): C 63.00, H 7.34. Found: C 62.58, H 7.57.
Reaction of 2,2-Bis(phenylalkynyl)hexamethyltrisilane with
3 equiv of Cp2ZrCl2 (24). Reaction was done analogously to the
preparation of 2 using 2,2-bis(phenylalkynyl)hexamethyltrisilane
(200 mg, 0.531 mmol), Cp2ZrCl2 (466 mg, 1.593 mmol), and Mg
turnings (39 mg, 1.605 mmol). A red crystalline solid of 24 (165
mg, 52%) was obtained. 29Si NMR (δ ppm): -16.1 (SiMe3); -48.3.
1H NMR (δ ppm): 7.98 (m, 2H); 7.62 (m, 2H); 7.39 (m, 4H); 7.20
(m, 2H); 5.64 (s, 10H, Cp); 0.21 (s, 18H, SiMe3). 13C NMR (δ
ppm): 246.9; 203.5; 154.5; 143.0; 141.7; 129.4; 128.7; 128.4; 127.1;
127.9; 126.7; 106.4 (Cp); 91.9; -0.3 (SiMe3). Anal. Calcd for
C32H38Si3Zr (598.12): C 64.26, H 6.40. Found: C 64.29, H 6.21.
Reaction of Pentamethyl(phenylethynyl)disilane with Cp2ZrCl2
and PMe3 (18). Reaction was done analogously to the preparation
of 2 using pentamethyl(phenylethynyl)disilane (15) (100 mg, 0.430
mmol), Cp2ZrCl2 (126 mg, 0.430 mmol), PMe3 (33 mg, 0.430
mmol), and Mg turnings (11 mg, 0.453 mmol). Orange crystals of
18 (155 mg, 68% yield) were obtained. 29Si NMR (δ ppm): -20.4
(SiMe3); -26.6 (d, J ) 3.2 Hz, SiMe2). 1H NMR (δ ppm): 7.15 (t,
2H); 6.92 (t, 1H); 6.67 (d, 2H); 5.33 (d, J ) 1.7 Hz, 10H, Cp);
0.77 (d, J ) 6.0 Hz, 9H, PMe3); 0.45 (s, 6H, SiMe2); 0.08 (s, 9H,
SiMe3). 13C NMR (δ ppm): 180.2 (d, J ) 18.2 Hz); 176.4 (d, J )
7.3 Hz); 157.8; 127.5; 123.3; 122.0; 103.0 (Cp); 17.2 (d, J ) 16,1
Hz, PMe3), -0.5 (SiMe2); -1.6 (SiMe3). 31P NMR (δ ppm): -0.2.
Anal. Calcd for C26H39PSi2Zr (529.96): C 58.93, H 7.42. Found: C
59.07, H 7.36.
Reaction of 1,4-Bis[tris(trimethylsilyl)silyl]butadiyne (25)
with Cp2ZrCl2 (26). Reaction was done analogously to the
preparation of 2 using 1,4-bis[tris(trimethylsilyl)silyl]butadiyne (25)
(50 mg, 0.092 mmol), Cp2ZrCl2 (27 mg, 0.092 mmol), and Mg
turnings (3 mg, 0.123 mmol). A red crystalline solid of 26 (34 mg,
48%) was obtained. 29Si NMR (δ ppm): -12.4 (SiMe3); -82.4.
1H NMR (δ ppm): 5.24 (s, 10H, Cp); 0.40 (s, 54H, SiMe3). 13C
NMR (δ ppm): 176.2; 131.4; 104.7 (Cp); 1.0 (SiMe3). Anal. Calcd
for C32H64Si8Zr (764.76): C 50.26, H 8.44. Found: C 50.63, H 8.66.
Reaction of Pentamethyl(phenylethynyl)disilane with Cp2HfCl2
and PMe3 (19, 20): Reaction was done at 40 °C analogously to the
preparation of 2 using pentamethyl(phenylethynyl)disilane (15) (100
mg, 0.430 mmol), Cp2HfCl2 (163 mg, 0.430 mmol), PMe3 (33 mg,
0.430 mmol), and Mg turnings (11 mg, 0.453 mmol). An orange
oil of 19 (125 mg, 47%) was obtained. 29Si NMR (δ ppm): -20.1
Derivatization Reactions. Reaction of 2 with I2: 1,4-Diiodo-
1,4-bis[bis(trimethylsilyl)silyl]butadiene (27). In a J-Young tube
2 (42 mg, 0.055 mmol) and I2 (28 mg, 0.110 mmol) were dissolved
in 3 mL of THF. After 1 h the orange suspension was diluted with
5 mL of pentane and then poured onto an aqueous Na2S2O3 solution.
The layers were separated and the organic layer treated once again
with brine. After drying with NaSO4 27 (14 mg, 32%) was obtained
1
(SiMe3); -25.2 (d, J ) 3.3 Hz, SiMe2). H NMR (δ ppm): 7.15
(m, 2H); 6.91 (m, 2H); 6.63 (m, 1H); 5.26 (dd, J ) 0.4 Hz; J )
2.3 Hz, 10H, Cp); 0.82 (d, J ) 6.2 Hz, 9H, PMe3); 0.44 (s, 6H,
SiMe2); 0.07 (s, 9H, SiMe3). 13C NMR (δ ppm): 187.0 (d, J )
15.3 Hz); 181.7 (d, J ) 7.7 Hz); 159.9 (d, J ) 1.6 Hz); 127.4;

Complexes of Tris(trimethylsilyl)silylacetylene
Organometallics, Vol. 27, No. 11, 2008 2583
1
as a semicrystalline solid. 29Si NMR (δ ppm): -11.2; -53.0. H
NMR (δ ppm): 7.34 (s, 2H); 0.34 (s, 54H). Anal. Calcd for
C22H56I2Si8 (799.17): C 33.06, H 7.06. Found: C 32.73, H 7.12.
Reaction of 17 with I2: 1,4-Diiodo-1,4-pentamethyldisilanyl-
2,3-diphenyl-butadiene (28). Reaction was carried out analogously
to the preparation of 27 with 17 (100 mg, 0.146 mmol) and I2 (74
mg, 0.291 mmol). 28 (54 mg, 37%) was obtained as a yellow oil.
129.8; 128.6; 128.5; -1.7; -3.1. Anal. Calcd for C26H42Si4
(466.95): C 66.88, H 9.07. Found: C 66.11, H 8.89.
Reaction of 2 with KOtBu (30). Compound 2 (70 mg, 0.09
mmol) was solved in 3 mL of THF, and KOtBu (21 mg, 0.183
mmol) was added. After stirring for 4 h the reaction was complete
and the solvent was removed, yielding 30 as an oily residue (46
1
mg, 73%). 29Si NMR (δ ppm): -16.1; -89.4. H NMR (δ ppm):
1
29Si NMR (δ ppm): -10.4; -17.5. H NMR (δ ppm): 7.44 (m,
6.26 (s, 2H); 5.87 (s, 10H, Cp); 0.37 (s, 36H, SiMe3).
4H); 6.92 (m, 6H); 0.41 (s, 12H); 0.25 (s, 18H). Anal. Calcd for
C26H40I2Si4 (718.75): C 43.45, H 5.61. Found: C 42.91, H 5.59.
Reaction of 17 with HCl: 1,4-Pentamethyldisilanyl-2,3-diphe-
nylbutadiene (29). A solution of 17 (300 mg, 0.437 mmol) in
pentane (2 mL) was added dropwise to a stirred 6 M solution of
aqueous HCl (3 mL) at 0 °C. After 1 h the organic layer was
separated and washed with saturated NaHCO3. 29 (140 mg, 68%)
was obtained as a colorless oil after drying with NaSO4 and
evaporation of the solvent. 29Si NMR (δ ppm): -18.6; -26.7. 1H
NMR (δ ppm): 7.35 (m, 6H); 7.05 (m, 4H); 5.62 (s, 2H); -0.01
(s, 18H); -0.24 (s, 12H). 13C NMR (δ ppm): 159.3; 142.6; 133.2;
Acknowledgment. This study was supported by the
Austrian Fonds zur Förderung der Wissenschaften (FWF)
via the project P18382-N11.
Supporting Information Available: X-ray crystallographic
information for compounds 2, 4, 6, 7, 12, 13, 14, 17, 20, 22, 23,
24, 26, and 27 in CIF format are available free of charge via the
Internet at http://pubs.acs.org.
OM800038H