Reactivity of acetylenes toward the titanocene vinylidene fragment [Cp*2Ti=C=CH2]. Formation of methylenetitanacyclobutenes and vinyltitanium Cp*2TiCR′=CR″C=CH2 (R′ = R″ = CH3; R′ = SiMe3, R″ = C6 H5) and Cp*2Ti(CH=CH2)(C≡CPh)

Article abstract of DOI:10.1021/om950783a

The titanocene vinylidene intermediate [Cp*₂Ti=C=CH₂] (4) (Cp*, C₅(CH₃)₅), formed by ethylene or methane elimination from Cp*₂TiCH₂CH₂C=CH₂ (3) and Cp*₂Ti(CH=CH₂)(CH₃) (11), respectively, reacts with symmetrical alkynes such as acetylene (12a), 2-butyne (12b), 1,2-diphenylacetylene (12c), 1,2-bis(trimethylsilyl)acetylene (12d), and 1,2-bis(tri-n-butylstannyl)acetylene (12e) by a [2 + 2] cycloaddition to give metallacyclobutenes Cp*₂TiCR=CRC=CH₂ (8a-e). When unsymmetrical alkynes are used, such as 2-pentyne (13g), 2,4-hexadiyne (13h), 1,4-diphenyl-1,3-butadiyne (13i), 1-phenyl-1-propyne (13j), or 1-(trimethylsilyl)-2-phenylacetylene (13k), different regioisomers can be isolated. For the reaction products of 4 with 13g and 13j, kinetic and thermodynamic products can be distinguished. In reactions of 1-pentyne (13f) and 4, a 1:1.5 mixture of the [2 + 2] cycloaddition product Cp*₂TiCH=C(nPr)C=CH₂ (17f) and the alkyne C-H bond activation product, Cp*₂Ti(CH=CH₂)(C≡C-nPr) (19f), is formed. By using stronger acidic acetylenes, like phenylacetylene (131), or terminal acetylenes with bulky substituents, such as 2,2-dimethyl-3-butyne (13m) or (trimethylsilyl)acetylene (13n), the vinyl acetylides Cp*₂Ti(CH=CH₂)(C≡CR) [R = Ph (19l), t-Bu (19m), SiMe₃ (19n)] are isolated in high yields. The structures of Cp*₂TiC(CH₃)=C(CH₃)C=CH₂ (8b) and Cp*₂TiC(SiMe₃)=C(Ph)C=CH₂ (17k) were determined. The pseudotetrahedral molecules contain planar cyclobutene rings. The X-ray structure of 191 is presented. The regioselectivity of the formation of 17 and its regioisomer 16, using unsymmetrically substituted acetylenes, is attributed to the polarity of the C≡C bond, on the basis of ¹³C NMR data. The reactivity of the methylenetitanacyclobutenes depends on the substituents of the alkynes. The formation of trans-poly(acetylene) occurs via 8a with an excess of acetylene. Analogous reactions of 8b,c and substituted alkynes are not successful. The isomerization of the titanacyclobutenes 16 → 17 indicates a cycloreversion. Selective insertion reactions of 8b and 8c with C₆H₁₁NC are observed in the TiC(R)=C(R) σ-bond opposite the exo-methylene group, forming five-membered rings Cp*₂TiC(=NC₆H₁₁)C(R)=C(R)C=CH₂ [R = Me (25b), Ph (25c)].

Full text of DOI:10.1021/om950783a

1176
Organometallics 1996, 15, 1176-1187
Rea ctivity of Acetylen es tow a r d th e Tita n ocen e
Vin ylid en e F r a gm en t [Cp *2TidCdCH2]. F or m a tion of
Meth ylen etita n a cyclobu ten es a n d Vin yltita n iu m
Acetylid es. Cr ysta l a n d Molecu la r Str u ctu r es of
Cp *2TiCR′dCR′′CdCH2 (R′ ) R′′ ) CH3; R′ ) SiMe3,
R′′ ) C6H5) a n d Cp *2Ti(CHdCH2)(CtCP h )
Ru¨diger Beckhaus,* J avier Sang, Trixie Wagner, and Beate Ganter
Department of Inorganic Chemistry, Technical University Aachen, Professor-Pirlet-Strasse 1,
D-52062 Aachen, Germany
Received October 4, 1995X
The titanocene vinylidene intermediate [Cp*2TidCdCH2] (4) (Cp*, C5(CH3)5), formed by
ethylene or methane elimination from Cp*2TiCH2CH2CdCH2 (3) and Cp*2Ti(CHdCH2)(CH3)
(11), respectively, reacts with symmetrical alkynes such as acetylene (12a ), 2-butyne (12b),
1,2-diphenylacetylene (12c), 1,2-bis(trimethylsilyl)acetylene (12d ), and 1,2-bis(tri-n-butyl-
stannyl)acetylene (12e) by a [2 + 2] cycloaddition to give metallacyclobutenes
Cp*2TiCRdCRCdCH2 (8a -e). When unsymmetrical alkynes are used, such as 2-pentyne
(13g), 2,4-hexadiyne (13h ), 1,4-diphenyl-1,3-butadiyne (13i), 1-phenyl-1-propyne (13j), or
1-(trimethylsilyl)-2-phenylacetylene (13k ), different regioisomers can be isolated. For the
reaction products of 4 with 13g and 13j, kinetic and thermodynamic products can be
distinguished. In reactions of 1-pentyne (13f) and 4, a 1:1.5 mixture of the [2 + 2]
cycloaddition product Cp*2TiCHdC(nPr)CdCH2 (17f) and the alkyne C-H bond activation
product, Cp*2Ti(CHdCH2)(CtC-nPr) (19f), is formed. By using stronger acidic acetylenes,
like phenylacetylene (13l), or terminal acetylenes with bulky substituents, such as 2,2-
dimethyl-3-butyne (13m ) or (trimethylsilyl)acetylene (13n ), the vinyl acetylides Cp*2Ti-
(CHdCH2)(CtCR) [R ) Ph (19l), t-Bu (19m ), SiMe3 (19n )] are isolated in high yields. The
structures of Cp*2TiC(CH3)dC(CH3)CdCH2 (8b) and Cp*2TiC(SiMe3)dC(Ph)CdCH2 (17k )
were determined. The pseudotetrahedral molecules contain planar cyclobutene rings. The
X-ray structure of 19l is presented. The regioselectivity of the formation of 17 and its
regioisomer 16, using unsymmetrically substituted acetylenes, is attributed to the polarity
of the CtC bond, on the basis of 13C NMR data. The reactivity of the methylenetitanacy-
clobutenes depends on the substituents of the alkynes. The formation of trans-poly(acetylene)
occurs via 8a with an excess of acetylene. Analogous reactions of 8b ,c and substituted
alkynes are not successful. The isomerization of the titanacyclobutenes 16 f 17 indicates
a cycloreversion. Selective insertion reactions of 8b and 8c with C6H11NC are observed in
the TiC(R)dC(R) σ-bond opposite the exo-methylene group, forming five-membered rings
Cp*2TiC(dNC6H11)C(R)dC(R)CdCH2 [R ) Me (25b), Ph (25c)].
In tr od u ction
elimination processes from alkyl derivatives, which are
suitable for the formation of intermediates of type 2,8
are also suitable for alkenyl derivatives in a selective
manner, leading to intermediates 4.9
While much work has been devoted to titanacyclobu-
tanes 11 as efficient starting molecules of a titanium
methylene fragment 2,2 the homologous titana-3 4 or
other metallaallene fragments of electron-poor metals4,5
have attracted less attention. This is all the more
surprising, considering that the titanium vinylidene
species 4 (Ln ) Cp*2) can easily be generated from a
methylenetitanacyclobutane 36 obtained via a Cp*2Ti-
(CHdCH2)2 intermediate in quantitative yield.6c,7 R-H-
In comparing the subsequent products of 2 and 4,
respectively, in contrast to the behavior of 2, by the
reaction of 3 f 4, a large scale yield of [2 + 2]
cycloaddition products can be isolated by using func-
tionalized substrates. First of all, cycloaddition prod-
ucts 5 and 6, synthesized by trapping 4 with cumu-
lenes,6a,10 transition metal carbonyls,9b,11 nitriles, and
phosphaalkynes,12 are of high thermal stability due to
the stabilization effect of the R-exo-methylene group, the
X Abstract published in Advance ACS Abstracts, February 1, 1996.
(1) (a) Feldman, J .; Schrock, R. R. Prog. Inorg. Chem. 1991, 39,
1-74. (b) Bickelhaupt, F. Angew. Chem. 1987, 99, 1020-1035; Angew.
Chem., Int. Ed. Engl. 1987, 26, 990-1005. (c) Straus, D. A.; Grubbs,
R. H. J . Mol. Catal. 1985, 28, 9-25. (d) Grubbs, R. H. Prog. Inorg.
Chem. 1979, 24, 1-50.
2
2
formation of stronger Csp -Csp bonds in the four-
membered ring, and the lowered electrophilicity of the
0276-7333/96/2315-1176$12.00/0 © 1996 American Chemical Society

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1177
tained for the first time.6a,10,14 Acidic compounds such
as alcohols, water, or ketones react with the strongly
nucleophilic R-C-atom of the titanium vinylidene 4 in a
selective manner, forming vinyl derivatives 7.15
titanium center by the strongly basic Cp* ligands.13
With cumulenes and heterocumulenes, monomeric met-
allaoxetanes exhibiting planar ring geometry are ob-
(2) (a) Finch, W. C.; Anslyn, E. V.; Grubbs, R. H. J . Am. Chem. Soc.
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K. C.; Grubbs, R. H. J . Am. Chem. Soc. 1982, 104, 7491-7496. (m)
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On the other hand, typical proton shift reactions of
the vinylidene fragment are observed in bimetallic
oxetanes 5b, leading, by a surprising vinylidene-
acetylene rearrangement (10 f 9), to oxatitanacyclo-
pentene complexes,9b illustrating typical transforma-
tions of the vinylidene CdCH2 molecule in the gas
phase.16 The interest in the acetylene-vinylidene rear-
rangement itself can be ascribed to the fact that the
process (9 f 10) is discussed as the first step in the
favorite mechanisms of the formation of poly(acety-
lene)s.17 From this point of view in particular, we will
report the behavior of the intermediate 4 toward
terminal and internal acetylenes and will investigate
the synthesis of complexes of type 8. Metallacy-
clobutenes of the titanium group without the R-meth-
ylene group are known by reaction of cyclopropenes with
low-valent metal complexes,18 by reaction of carbenoid
titanium derivatives, including the Tebbe reagent and
derivatives thereof, with acetylenes,2a,8e,8f,19 or as inter-
mediates in organic synthesis.20 Alternative mecha-
nisms for the formation of poly(acetylene)s are also
discussed via a carbene-metallacyclobutene-vinylcar-
(4) Fermin, M. C.; Bruno, J . W. J . Am. Chem. Soc. 1993, 115, 7511-
7512.
(5) (a) Gibson, V. C.; Parkin, G.; Bercaw, J . E. Organometallics 1991,
10, 220-231. (b) van Asselt, A.; Burger, B. J .; Gibson, V. C.; Bercaw,
J . E. J . Am. Chem. Soc. 1986, 108, 5347-5349.
(6) (a) Beckhaus, R. Methylidenetitanacyclobutane vs. Titanocene-
VinylidenesVersatile Building Blocks. In Organic Synthesis via
Organometallics (OSM 4), Proceedings of the Fourth Symposium in
Aachen, J uly 15, to 18, 1992; Enders, D., Gais, H.-J ., Keim, W., Eds.;
Vieweg Verlag: Braunschweig, 1993; pp 131-149. (b) Beckhaus, R.;
Flatau, S.; Troyanov, S. I.; Hofmann, P. Chem. Ber. 1992, 125, 291-
299. (c) Beckhaus, R. Zur Chemie von Vinylverbindungen elektrone-
narmer U¨ bergangsmetalle (Habilitation Thesis), Fakulta¨t fu¨r Natur-
wissenschaften,
Technische
Hochschule
Leuna-Merseburg,
Mathematisch-Naturwissenschaftliche Fakulta¨t der RWTH Aachen,
1989/1993.
(7) (a) Beckhaus, R. Alkenyl-, Allyl- and Dienyl- Complexes of Main
Group Elements and Transition Metals. In Synthetic Methods of
Inorganic and Organometallic Chemistry; Herrmann, W. A., Ed.;
Georg-Thieme-Verlag: Stuttgart, Germany, 1996, in press. (b) Beck-
haus, R.; Thiele, K.-H.; Stro¨hl, D. J . Organomet. Chem. 1989, 369, 43-
54.
(8) (a) van Doorn, J . A.; van der Heijden, H.; Orpen, A. G. Organo-
metallics 1995, 14, 1278-1283. (b) van Doorn, J . A.; van der Heijden,
H.; Orpen, A. G. Organometallics 1994, 13, 4271-4277. (c) Petasis,
N. A.; Fu, D.-K. J . Am. Chem. Soc. 1993, 115, 7208-7214. (d) Fryzuk,
M. D.; Mao, S. S. H.; Zaworotko, M. J .; MacGillivray, L. R. J . Am.
Chem. Soc. 1993, 115, 5336-5337. (e) Petasis, N. A.; Fu, D.-K.
Organometallics 1993, 12, 3776-3780. (f) Doxsee, K. M.; J uliette, J .
J . J .; Mouser, J . K. M.; Zientara, K. Organometallics 1993, 12, 4682-
4686. (g) Petasis, N. A.; Bzowej, E. I. J . Org. Chem. 1992, 57, 1327-
1330. (h) Petasis, N. A.; Akritopoulou, I. Synlett 1992, 665-667. (i)
Doxsee, K. M.; Farahi, J . B.; Hope, H. J . Am. Chem. Soc. 1991, 113,
8889-8898. (j) Petasis, N. A.; Bzowej, E. I. J . Am. Chem. Soc. 1990,
112, 6392-6394. (k) Bertz, S. H.; Dabbagh, G.; Gibson, C. P.
Organometallics 1988, 7, 563-565.
(12) Beckhaus, R.; Strauss, I.; Wagner, T. Angew. Chem. 1995, 107,
738-740; Angew. Chem., Int. Ed. Engl. 1995, 34, 688-690.
(13) Complexes of type 5, Y ) CR2, Cp instead of Cp*, are postulated
as intermediates in carbonylolefination reactions; however, these were
not detectable by NMR spectroscopy, even at low temperatures.
Buchwald, S. L.; Grubbs, R. H. J . Am. Chem. Soc. 1983, 105, 5490-
5491.
(14) Grubbs describes alternative syntheses of LnTiOC(dCR2)CH2
derivatives, attributing their stability to the puckering of the oxetane
rings. Ho, S. C.; Hentges, S.; Grubbs, R. H. Organometallics 1988, 7,
780-782.
(15) (a) Beckhaus, R.; Sang, J .; Oster, J .; Wagner, T. J . Organomet.
Chem. 1994, 484, 179-190. (b) Beckhaus, R.; Strauss, I.; Wagner, T.
J . Organomet. Chem. 1994, 464, 155-161.
(16) Gallo, M. M.; Hamilton, T. P.; Schaefer, H. F., III J . Am. Chem.
Soc. 1990, 112, 8714-8719.
(17) (a) Ohff, A. Darstellung, Eigenschaften und Reaktionen von
Alkin-Komplexen des Titanocens und Zirconocens. PhD. Thesis,
Mathematisch-Naturwissenschaftliche Fakulta¨t, Universita¨t Rostock,
1995. (b) Szymanska-Buzar, T. J . Mol. Catal. 1994, 93 (2), 137-147.
(c) Alt, H. G.; Engelhardt, H. E.; Rausch, M. D.; Kool, L. B. J .
Organomet. Chem. 1987, 329, 61-67. (d) Landon, S. J .; Shulman, P.
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B.; Langhauser, F.; Kru¨ger, C. Chem. Ber. 1991, 124, 2165-2170.
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501, 321-326. (b) Beckhaus, R.; Oster, J .; Wagner, T. Chem. Ber. 1994,
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(10) Beckhaus, R.; Strauss, I.; Wagner, T.; Kiprof, P. Angew. Chem.
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364.

1178 Organometallics, Vol. 15, No. 4, 1996
Beckhaus et al.
bene route21 or via insertion reactions in transition
Sch em e 1
metal σ-bonds.22
Resu lts a n d Discu ssion
The metallacyclobutane 3 and the vinylmethyl de-
rivative 11, respectively, react with 1 equiv of the
symmetrical acetylenes 12a -e at 80 °C in a few minutes
under liberation of ethylene (from 3) or at room tem-
perature by liberation of methane (from 11) to give the
metallacyclobutenes 8. Complexes 8 are formed in
nearly quantitative yields (NMR) and can be isolated
as dark red crystals of high thermal stability [8b, mp
173 °C (dec); 8c, mp 196 °C (dec)] or in the case of 8a ,d ,e
as waxy solids. These species are interesting in that
each of the metallacyclobutene carbons is sp2 hybridized.
The mass spectra of 8 exhibit the expected molecular
peaks. With the exception of 8d , metatheses-like frag-
mentation behavior similar to that of metallacyclobu-
tanes is not observed in the mass spectrometer.6b
To investigate the regiochemistry of the cycloaddition
between 4 and 12, asymmetrical substituted alkynes 13
were used in reactions of 3 as well as 11 (see Scheme
1). By using 13f-k , mixtures of regioisomers as well
as sterically pure compounds 16/17 are formed via 14
and 15. By using butadiynes 13h and 13i, products
with the acetylide substituent in the R-position (16h ,
16i) are formed without exception. In the reaction of
13k with 4, only the isomer 17 exhibiting the SiMe3
group in the R-position is formed. Yields and product
ratios are summarized in Table 1. 1H and 13C NMR
data of the titanacyclobutenes 8, 16, and 17 are listed
in Table 2.
The formation of 8a and 17f shows that terminal
acetylenes are also able to form metallacyclobutenes.
Types of products and ratios thereof depend on the
nature of the alkyne used. By using the unsubstituted
acetylene 12a in a stoichiometric amount, the metalla-
cyclobutene 8a is the only isolable reaction product. The
alternative possible formation of a vinyltitanium acetyl-
ide 19a is not observed. However, by using 13f, a 1:1.5
mixture of the metallacyclobutene 17f (R′′ ) n-Pr in
â-position) and the alkyne C-H bond activation product
19f is obtained. Reactions of phenylacetylene 13l or
other terminal alkynes (13m , 13n ) with 4 lead to the
vinyl acetylides 19l-n without the formation of any
other products.
The reasons for the exclusive formation of 19l-n in
contrast to 19f and 8a can be explained by the high CH
acidity of the acetylenes used;23 moreover, it can be
proposed that bulky substituents, like tert-butyl (13m )
and trimethylsilyl (13n ) lead to a geometry (18) that
finally results in C-H bond activation. The use of
PhCtCD, which exclusively forms Cp*2Ti(CDdCH2)-
(CtCPh) (19l-D), undoubtedly proves the alkyne to be
the proton source. 1H and 13C NMR data of the
vinyltitanium acetylides 19 are listed in Table 4.
(19) (a) Doxsee, K. M.; J uliette, J . J . J .; Zientara, K.; Nieckarz, G.
J . Am. Chem. Soc. 1994, 116, 2147-2148. (b) Doxsee, K. M.; J uliette,
J . J . J .; Mouser, J . K. M.; Zientara, K. Organometallics 1993, 12, 4742-
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1995, 36, 3619-3622. (b) Doxsee, K. M.; Mouser, J . K. M.; Farahi, J .
B. Synlett 1992, 13-21. (c) Tumas, W.; Suriano, J . A.; Harlow, R. L.
Angew. Chem. 1990, 102, 89-90. (d) Doxsee, K. M.; Shen, G. S.;
Knobler, C. B. J . Am. Chem. Soc. 1989, 111, 9129-9130.
The two different chemical shifts for the protons of
the exo-methylene group of 8, 16, and 17 in the 1H NMR
spectra appear to be a characteristic feature of the new
complexes and similar metallacyclic structures.6b,9,12 The
chemical shifts were assigned through NOE experi-
ments. In all cases, the high-field signal is assigned to
the endo-position H1 and the low-field signal to the exo-
position H2. Moreover, the chemical shifts of the ring
carbon atoms in the 13C NMR spectra are in accordance
with two titanium σ-bonded sp2 carbon atoms. The low-
(21) (a) Wallace, K. C.; Liu, A. H.; Davis, W. M.; Schrock, R. R.
Organometallics 1989, 8, 644-654. (b) Fox, H. H.; Wolf, M. O.; O’Dell,
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1985, 4, 2186-2195. (h) Thoi, H. H.; Ivin, K. J .; Rooney, J . J . J . Chem.
Soc., Faraday Trans 1982, 78, 2227-2232. (i) Katz, T. J .; Lee, S. J .
J . Am. Chem. Soc. 1980, 102, 422-424.
(23) pKa ) 18.3 for 13l,23a similar to alcohols,23b which are able to
form vinyl derivatives via 4,15a pKa ) 25 for 12a .23c (a) Butin, K. P.;
Beletskaya, I. P.; Kashin, A. N.; Reutov, O. A. J . Organomet. Chem.
1967, 10, 197-210. (b) Becker, H. G. O. Elektronentheorie organisch-
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schaften: Berlin, 1974. (c) Vollhardt, K. P. C. Organische Chemie, 1st
ed.; VCH Verlagsgesellschaft mbH: Weinheim, 1990.
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371; Angew. Chem., Int. Ed. Engl. 1981, 20, 361-381.

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1179
Ta ble 1. P r od u ct Ra tios in Rea ction s of 4 w ith Acetylen es
product ratios (%)
Ti
R′
Ti
R′′
Ti
Acetylene
C
CR′′
R′′
16
R′
17
R′CtCR′′
R′
R′′
19
12a
12b
12c
12d
12e
13f
13g
H
CH3
Ph
SiMe3
SnBu3
100a
100a
100a
100a
100a
0
0
0
0
0
H
Me
n-Pr
0
25
5
100
100
43
31
0
40
75
95
0
60
Etb
ratio after 12 h, 80 °C
CtCMe
13h
13i
13j
Me
Ph
Me
CtCPh
0
Phb
57
69
100
0
0
0
ratio after 42 h, 80 °C
13k
13l
13m
13n
SiMe3
Ph
Ph
t-Bu
SiMe3
H
H
H
0
0
0
100
100
100
a
b
Products 8a -e. Measured at room temperature after 1 h.
Ta ble 2. NMR Da ta for th e TiCRdCRCdCH2 Rin g in Meta lla cyclobu ten e Com p lexesa
H2
H1
Ti
C4
C1
C2 R1
1H NMR data (ppm) (J HH (Hz))
13C NMR data
C1 C2 C3
C3
R2
Cp*
1.65 (s) 4.79 (dd,
4.58; 2.24)
1.67 (s) 4.57 (br s)
H1 (endo)
H2 (exo)
5.66 (m)
R1
R2
Cp*
C4
8a
6.68 (ddd, 12.1,
2.52, 1.75)
7.81 (ddd, 12.1,
2.22, 1.15)
2.01 (d, 0.61)
12.0 214.3 100.4 207.0 109.3
118.0
8b
8c
5.65 (dm, 0.62) 1.76 (d, 0.91)
11.9 213.6
118.9
99.4 210.6 101.3
1.73 (s) 4.61 (d, 1.22) 5.69 (d, 1.22)
6.78-7.42b
12.4 211.4 113.3 205.3 106.7
120.8
8d
8e
1.63 (s) 5.12 (s)
1.67 (s) 5.13 (s)
6.14 (s)
5.85 (s)
0.47 (s)
0.53 (s)
0.93-1.68b
12.4 214.5 115.1 212.9 116.3
115.8
11.9 210.4 111.1 199.3 102.4
118.9
17f
16g
17g
16h
16i
16j
17j
17k
1.66 (s) 4.57 (m)
1.67 (s) 4.56 (s)
1.67 (s) 4.54 (s)
5.73 (m)
5.68 (s)
5.66 (s)
1.07; 2.08; 2.23b 7.39 (m)
1.73 (s)
2.51 (q, 7.43)
1.13 (t, 7.48)
1.99 (s)
2.31 (q, 7.63)
1.15 (t, 7.63)
2.10 (s)
11.9 212.0 105.1 210.2 100.8
118.8
11.9 210.5 104.2 185.9 104.8
120.2
12.0 205.4 126.7 182.7 108.4
121.3
12.3 215.2 105.0 204.7 103.8
120.1
12.0 211.8 110.2 210.7 104.3
119.6
12.6 218.0 129.8 215.2 108.6
119.9
1.75 (s) 4.55 (d, 1.53) 5.71 (d, 1.53)
1.78 (s) 4.57 (d, 1.53) 5.98 (d, 1.22)
1.66 (s) 4.62 (d, 0.91) 5.78 (d, 1.22)
1.72 (s) 4.54 (d, 0.61) 5.55 (d, 0.61)
1.75 (s) 4.71 (d, 1.53) 5.37 (d, 1.22)
2.03 (s)
6.83-7.81b
2.10 (s)
6.96-7.46b
7.12-7.38b
2.02 (s)
7.11; 7.24; 7.36b 0.14 (s)
a
b
Listed in ppm vs TMS; solvent was C6D6 and temperature ) 25 °C. For details see the Experimental Section.
field signals are consistent with the C1-atom (205-218
ppm), whereas C3 is shifted to higher fields δC1-δC3:
8, 4-7; 16, 10-25; 17, 2-11 ppm). The largest shift is
observed for the cycloaddition products with butadiynes
exhibiting the C3 signal at 185.9 (16h ) and 182.7 (16i)
ppm.
The structures of 8b and 17k were confirmed by X-ray
structure determination. Ortep plots are shown in
Figures 1 and 2, and relevant bond distances and angles
are given in Table 3. The geometries of 8b and 17k
show a planar titanacyclobutene ring. The greatest
deviations from the mean plane are 0.010(3) Å for 8b
and 0.019(5) Å for 17k . The solid state structural data
for complex 8b are consistent with a metallacycle
formalism. Partial ring opening, suggesting a fragmen-
tation toward titanium vinylidene alkyne structures (14,
15), comparable to trimethylsilyl-substituted titana-
cyclobutenes,19b can be denied for 8b. The Ti-C1 bonds
in 8b and 17k are identical in the range of standard
deviation, but they are longer as in the titanacyclobu-
tane 3 (2.068(6) Å)6b and shorter as in aza- and phos-
phatitanacyclobutenes (6a , 2.134(2); 6b, 2.161(5) Å).12
Alternating bond lengths in the sequence C4-C1-
C2-C3, comparable to a conjugated π-bond system and
similar to free butadiene, are especially observed in 8b.
For the exocyclic C1-C4 distance (1.377(4) Å), the

1180 Organometallics, Vol. 15, No. 4, 1996
Beckhaus et al.
distance of two Csp centers.25 These structural data
confirm the high thermal stability of 8b and can be
attributed to a discrimination of metathesis-like ring
opening of the metallacyclobutene (vide infra). The
angles are in the expected range for a planar metalla-
2
2
cycle exhibiting Csp -atoms [C1-Ti-C3 angles: 8b, 68.0-
(1)°; 17k , 69.3(2)°; 6a , 67.85(8)°; 6b, 68.2(1)°;12 5a (Y,
CdNC6H11), 67.6(1)°;10 5a (Y, CdC(C6H5)2), 67.5(2)° 24].
A larger value is found in the titanacyclobutane 3 (83.1-
(4)°).6b
However, there are differences in the solid state
structures of 8b and 17k to take into consideration.
While for 8b, characteristic alternating C-C bond
distances in the sequence C4-C1-C2-C3 are discussed
(vide supra), in the case of 17k an elongation of the C1-
C2 bond of 1.502(7) Å is found, which is comparable to
the Csp -Csp in 3 (1.521(10) Å).6b The significantly
longer Ti-C3 distance in the solid state of 17k (2.173-
(6) Å) is in agreement with our observation of a
metathesis-like ring opening (16/17 f 14/15) for the
substituted titanacyclobutenes compared with less sub-
stituted derivatives 8a or 8b.
2
3
F igu r e 1. Ortep drawing of Cp*2TiC(CH3)dC(CH3)CdCH2
(8b) (30% ellipsoids).41
The NMR data of the vinyltitanium acetylides (see
Table 4) are in the expected range of σ-bonded vinyl15a
and σ-bonded acetylide26 ligands. The constitution of
19l was confirmed by X-ray structure determination.
The high thermal parameters of the Cp* carbon atoms
indicate a serious rotational disorder around the C5-axis.
Due to the low diffraction intensity of the crystals, the
data set did not allow for the resolution of this disorder.
Therefore, all bond distances and angles show high
estimated standard deviations and will not be discussed
in this paper. However, the constitution of 19l is
undoubtedly proved by the results of the X-ray structure
determination. A Schakal plot is shown in Figure 3.
The vinyl group is exactly located in the main plane of
the metallocene fragment, exhibiting a orientation of the
R-C-H bond in the direction toward the lateral side of
the molecule.27 For intramolecular R-H-transforma-
tions, as observed by Teuben in a high-temperature
reaction (170 °C) of a single vinyltitanium acetylide,9c
a rotation of the vinyl group is proposed to be the first
step.
F igu r e 2. Ortep drawing of Cp*2TiC(SiMe3)dC(Ph)-
CdCH2 (17k ) (30% ellipsoids).41
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) in Cp *2TiC(CH3)dC(CH3)CdCH2 (8b) a n d in
Cp *2TiC(SiMe3)dC(P h )CdCH2 (17k )
8b
17k
8b
17k
Ti-C1
Ti-C3
Ti-Cp1
Ti-Cp2
2.104(3) 2.102(6) C3-Ti-C1
68.0(1)
69.3(2)
137.9
86.5(3)
2.109(3) 2.173(6) Cp-Ti-Cp 139.8
a
a
2.125
2.120
Ti‚ ‚ ‚C2 2.500
2.135
2.124
Ti-C1-C2
87.8(2)
Rea ctivity of Tita n a cyclobu ten es. Generally the
reactivity of metallacyclobutenes can be explained by
different mechanisms starting from structure B. Cy-
cloreversion processes are discussed by the reaction B
f A;19c,d,20a the participation of a free vinylidene during
the formation of type 8 metallacyclobutenes was proved
by Grubbs in a kinetic study,2b whereas the formation
of vinylcarbenes C and D are proved for tantalum,21a
tungsten,28 or metal complexes of the titanium group.18,29
Ti-C1-C4 146.6(3) 149.0(5)
2.507(6) C1-C2-C3 114.8(2) 116.7(5)
C1-C4
C1-C2
C2-C3
C2-C5
C2-C8
C3-C6
C3-Si
1.377(4) 1.322(8) C2-C3-Ti
89.4(2)
1.434(4) 1.502(7) C6-C3-Ti 145.2(2)
1.365(4) 1.352(8) Si-C3-Ti
87.4(4)
148.2(3)
117.4(5)
1.528(4)
C1-C2-C8
1.511(8)
1.870(6)
1.474(4)
a
Cp1/2, centroids of the cyclopentadienyl ligands.
2
2
(25) Csp -Csp distance expected for dCsCd: 1.474 Å, from the
covalent radii. Bastiansen, O.; Traetteberg, M. Tetrahedron 1962, 17,
147-154.
longest value for all type 5 and 6 complexes is found
[6a , 1.337(3); 6b, 1.326(8);12 5a (Y, CdNC6H11), 1.325-
(4);10 5a (Y, CdC(C6H5)2), 1.318(8);24 3, 1.321(10) Å6b]
in the case of 8b. This observation is in agreement with
the short C1-C2 bond, illustrating a conjugative effect
in the carbocyclic part of the metallacyclobutene ring.
The C1-C2 bond is shorter than expected for the
(26) Lang, H.; Seyferth, D. Z. Naturforsch. 1990, 45b, 212-220.
(27) Different rotamers of the vinyl group are discussed by Gleiter
and Erker: (a) Erker, G.; Zwettler, R.; Kru¨ger, C.; Hyla-Kryspin, I.;
Gleiter, R. Organometallics 1990, 9, 524-530. (b) Hyla-Kryspin, I.;
Gleiter, R.; Kru¨ger, C.; Zwettler, R.; Erker, G. Organometallics 1990,
9, 517-523. (c) Gleiter, R.; Hyla-Kryspin, I.; Niu, S.; Erker, G. Angew.
Chem. 1993, 105, 753-755.
(28) Macomber, D. W. Organometallics 1984, 3, 1589-1591.
(29) Binger, P.; Mu¨ller, P.; Benn, R.; Mynott, R. Angew. Chem. 1989,
101, 647-648.
(24) Beckhaus, R. Unpublished results.

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1181
Ta ble 4. NMR Da ta for th e Vin yltita n iu m Acetylid es 19a
H2
H1
H3
C2 C1
Ti
C3
C4
1H NMR data (ppm) (J HH (Hz))
13C NMR data
R′′
Cp*
1.85
H1
H2
H3
Cp*
C1
C2
C3
C4
19f
19l
4.95 (trm, 11.3)
5.66 (m)
12.8
121.5
12.7b
122.4
117.1
213.9
151.3
117.6
1.85
5.03 (dd, 17.2; 4.7)
5.67 (dd, 14.0; 4.6)
5.61 (dd, 17.4; 14.0)
116.8
214.9
162.0
118.3
19l-D
19m
1.84
5.01 (d, 3.7)
4.47 (dd, 18.0; 4.6)
5.66 (d, 3.9)
5.13 (dd, 14.0; 4.6)
1.85b
5.43 (dd, 18.0; 14.7)
5.49 (dd, 18.0; 14.0)
12.9
121.4
12.8
117.3
117.5
213.9
214.7
149.1
183.4
125.1
119.7
19n
1.81
4.97 (dd, 17.9; 4.4)
5.63 (dd, 14.0; 4.3)
121.9
a
b
Listed in ppm vs TMS; solvent was C6D6 and temperature ) 25 °C. Solvent was THF-d8.
F igu r e 3. Schakal drawing of Cp*2Ti(CHdCH2)(CtCPh)
(19l).42
However, η3-vinylcarbenes E, as discussed during the
reaction course of the Doetz reaction,30 can be ruled out
for metallocene complexes of electron-poor metals due
to steric reasons.
12d occurs in solution followed by intramolecular C-H
bond activation of the Cp* ligand to form the dark green
vinylfulvenetitanium complex, Cp*(Fv)TiCHdCH2,15a
which does not react with additional alkynes either by
cycloaddition or by insertion in the titanium-fulvene
bond. The orientation of the substituents in the cy-
clobutenes can be attributed to the polarity of the alkyne
molecule and the strongly nucleophilic R-C-atom in the
vinylidene 4 [Tiδ+dCδ-dCH2].6b The polarities of the
alkynes can be deduced from the 13C NMR chemical
shift of the carbon atoms, due to the correlation of σp
terms and the orbital expansion.31 The more electron-
rich carbon atoms are shifted to higher fields and the
more electron-poor carbon atoms to lower fields. Due
to the polarity of the titanium vinylidene fragment 4,
the alkyne usually coordinates as expected in 14/15
(Tiδ+‚‚‚Cδ-alkyne). The chemical shifts of the alkynes
used are listed in Table 5. If the differences ∆ are
higher than 7 ppm, only one regioisomer is found at
room temperature (16f, 16h , 16i, 17k ) exhibiting the
carbon atom with higher electron density in the R-posi-
tion.32 If the ∆ value is in the range below 7 ppm, the
formation of mixtures of regioisomers is observed (16/
17g, 16/17j). Only for alkynes exhibiting small differ-
For the titanacyclobutene complexes 8, exhibiting an
R-methylene group, different reaction types are found.
Slow rearrangement at 80 °C of 16g and 16j, forming
the thermodynamic products 17g and 17j, can be
attributed to a ring-opening reaction of the metathesis
type. Attempts to exchange the alkyne during these
rearrangements failed. By heating a mixture of 25%
16g and 75% 17g in the presence of excess 3-hexyne
(12o), only a lowering of the content of 16g and an
increasing of 17g to a 15%:85% ratio occurs, without
the exchange of 2-pentyne by 3-hexyne and additioinal
formation of 8o.
In contrast to the behavior of the titanacyclobutene
Cp2TiCH2C(SiMe3)dCSiMe3, which undergoes a fast
exchange of bis(trimethylsilyl)acetylene by diphenyl-
acetylene,19c in the case of 8d , liberation of the alkyne
(30) (a) Hofmann, P.; Ha¨mmerle, M. Angew. Chem. 1989, 101, 94-
942; Angew. Chem., Int. Ed. Engl. 1989, 28, 908-910. (b) Hofmann,
P.; Ha¨mmerle, M.; Unfried, G. New J . Chem. 1991, 15, 769-789.
(31) Gu¨nther, H. NMR-Spektroskopie, 3rd ed.; Georg Thieme Ver-
lag: Stuttgart, New York, 1992.

1182 Organometallics, Vol. 15, No. 4, 1996
Beckhaus et al.
Ta ble 5. Selected 13C NMR Da ta of Alk yn es Used
in Cycloa d d ition w ith th e Tita n iu m Vin ylid en e
In ter m ed ia te 4
R′C′tC′′R′′
R′ R′′
13C data
a
δC′
δC′′
∆
ref
13f
13g
13h
13i
13j
13k
H
n-Pr
Et
CtCMe
CtCPh
Ph
66.7
74.2
72.0
83.0
86.1
94.2
81.8
80.3
64.7
75.7
80.5
105.8
15.1
6.1
7.3
7.3
5.6
37
37
38
39
37
37
Me
Me
Ph
Me
SiMe3
Ph
11.6
a
∆ ) |δC′ - δC′′|.
ences in the polarity of the CtC triple bond are
isomerization reactions observed. The ratio of these
isomers depends on the temperature. At higher tem-
peratures, isomers with the more bulky substituent in
the â-position are preferred. Similar behavior is ob-
served by using the heteroalkyne t-BuCtP, forming a
opening reactions with protic agents, similar to zircona-
cyclobutenes18 or titanacyclobutanes,15a failed for 8, 16,
or 17. When nitriles or ketones are used, no insertion
reactions can be observed.8e,34 Whereas titanacy-
clobutenes are of low reactivity toward the substrates
discussed before, fast insertion reactions occur by using
cyclohexane isonitrile, forming the monoinsertion prod-
ucts 25b and 25c in the form of metallic green and light
green solids. The alternative possible insertion into the
TiC(dCH2) σ-bond, forming 26, is not observed. In this
direction the behavior of 8b and 8c is similar to that of
the titanacyclobutane 3.35 From 25, no subsequent
products are observed.36
mixture of two regioisomers, Cp*2TiC(tBu)dPCdCH2
and 6b, as the main product.12
For metallacyclobutenes, the reactivity B f C is also
observed in some cases.19b Heterocyclobutenes like 6a
in particular are able to undergo this type of ring
opening under the formation of allenylideneimido in-
termediates 20, due to the symmetry conform interac-
tion between the lone pair of the nitrogen atom and the
acceptor orbitals of the titanium center, followed by the
formation of 21.12
In general, the titanacyclobutene complexes 8 do not
react with an excess of the alkynes,33 the exception
being the reaction between acetylene 12a and 4 via 4
f 8a forming a low quantity of trans-poly(acetylene)
as a black insoluble solid. In the IR spectra of the poly-
(acetylene), the only band observed at 1014 cm-1
indicates the formation of pure trans-configured poly-
(acetylene) 24. Alt postulated an intermediate similar
to 8a (Cp instead of Cp*) during the polymerization of
acetylene.17c According to the proposed mechanism via
22/23, our isolation of 8a seems to confirm that
TiCHdCHCdCH2 derivatives are the main intermedi-
ates in poly(acetylene) formation. Attempts to stabilize
subsequent products from 8a , like 22 or derivatives
thereof, have failed up to now.
To distinguish between the titanacyclobutene reac-
tivities cycloreversion (B f A) and ring opening (B f
C), respectively, initial reactions were carried out. Ring-
(34) (a) Doxsee, K. M.; Mouser, J . K. M. Tetrahedron Lett. 1991,
32, 1687-1690. (b) Doxsee, K. M.; Mouser, J . K. M. Organometallics
1990, 9, 3012-3014.
(35) Beckhaus, R.; Zimmermann, C.; Wagner, T.; Herdtweck, E. J .
Organomet. Chem. 1993, 460, 181-189.
(36) Grubbs described the formation of vinylketene complexes from
3
titanacyclobutenes and CO by preferred insertion in the Ti-Csp
bond: Meinhart, J . D.; Santarsiero, B. D.; Grubbs, R. H. Grubbs, R.
H. J . Am. Chem. Soc. 1986, 108, 3318-3323.
(32) Ab Initio calculations (3-21G(*)) of 13k show a higher electron
density of the Me3SiC carbon (-0.57, {-0.37}) compared with the PhC
atom (0.02, {-0.15}). For comparison, [values (natural, {mulliken})]:
13f CH2Ct (-0.02, {(0}), tCH (-0.27, {-0.43}); 13g: EtCt (-0.04,
{-0.11}), tCMe (-0.04, {-0.16}).
(33) An alternative reaction is found by using cobaltacyclobutene
complexes, forming η4-cyclopentadiene products: O’Connor, J . M.;
Fong, B. S.; J i, H.-L.; Iliibner, K. J . Am. Chem. Soc. 1995, 117, 8029-
8030.
(37) Happ, B.; Bartik, T.; Zucchi, C.; Rossi, M. C.; Ghelfi, F.; Palyi,
G.; Varadi, G.; Szalontai, G.; Horvath, I. T.; Chiesi-Villa, A.; Guastini,
C. Organometallics 1995, 14, 809-819.
(38) Hesse, M.; Meier, H.; Zeeh, B. Spektroskopische Methoden in
der organischen Chemie, 3rd ed.; Georg Thieme Verlag: Stuttgart, New
York, 1987.
(39) Rosenthal, U.; Pulst, S.; Arndt, P.; Baumann, W.; Tillack, A.;
Kempe, R. Z. Naturforsch. 1995, 50b, 368-376.

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1183
2.52/1.75 Hz, CH), 7.81 (d/d/d, J ) 12.1/2.22/1.15 Hz, 1H,
TisCH) (the chemical shifts were assigned through an NOE
experiment); 13C{1H} NMR (C6D6, 125 MHz) δ 12.0 (C5(CH3)5),
100.4 (CH), 109.3 (dCH2), 118.0 (C5(CH3)5), 207.0 (TisCH),
214.3 (TiCd); EI-MS (85 °C) m/e (Irel) 370 (5) (M+), 353 (3),
337 (1), 318 (5) (Cp*2Ti)+, 290 (1), 270 (1), 218 (1), 200 (5), 188
(9), 173 (16), 162 (18), 152 (79), 137 (94), 121 (62), 105 (37), 91
(43), 86 (30), 77 (21), 67 (11), 57 (100), 43 (71); exact mass m/e
370.2140 (C24H34Ti), calculated m/e 370.2143; IR (KBr) 2970
vs, 2905 vs, 1713 m, 1632 m, 1572 s, 1493 vs, 1436 vs, 1376
w, 1262 m, 1212 s, 1083 vs, 1019 s, 950 m, 895 m, 853 m, 805
Further investigations concerning the reactivity prob-
lems of methylenetitanacyclobutenes are currently in
progress.
Con clu sion s
We have demonstrated that the reaction of the
titanocene vinylidene intermediate [Cp*2TidCdCH2] (4)
with alkynes yields titanacyclobutene complexes (8, 16,
17) and, alternatively, vinyltitanium acetylides (19),
depending on the nature of the alkynes used. By using
unsymmetrical alkynes, different regioisomers can be
isolated, whereas mixtures of different (16g/17g, 16j/
17j, 17f/19f) could not be separated. The regiochemistry
can be explained in accordance with the polarities of
the alkynes. High differences in the partial charge of
the alkyne CtC atoms, determined by 13C NMR mea-
surements, lead to stereochemically pure compounds,
with the more negative carbon bonded to titanium. R,â-
Regioisomers are obtained by using alkynes with small
differences. These can be isomerized by heating over a
prolonged period of time, giving products with the bulky
substituent in the â-position. The methylenetitanacy-
clobutene rings are of high thermal stability. Insertion
reactions occur only in the Ti-C bond opposite the exo-
methylene group. Ring opening of the methyleneti-
tanocene cyclobutene to a titanium allenylidene alky-
lidene complex is not observed, but is proposed during
the reaction course of the formation of trans-poly-
(acetylene) when using C2H2.
vs, 692 s, 619 s, 590 m, 459 m, 407 w cm-1
.
R ea ct ion of Bis(η5-p en t a m et h ylcyclop en t a d ien yl)-
m eth ylvin yltita n iu m (11) w ith Excess Acetylen e 12a . A
solution of 11 (280.2 mg, 0.777 mmol) in 30 mL of toluene was
treated at room temperature with an excess of thoroughly
dried acetylene. After 2 h, the solution color changed from
yellow into dark red with a black precipitation. The solvent
was evaporated under reduced pressure, yielding 8a as a red
oil (0.28 g, 97%) and 20 mg of solid, black poly(acetylene). The
poly(acetylene) was identified as trans-poly(acetylene) by its
IR spectrum, which exhibited only one absorption band at 1014
cm-1
.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
3,4-d im eth yl-2-m eth ylen etita n a cyclobu ten e (8b). To a
solution of 11 (298.2 mg, 0.827 mmol) in 30 mL of hexane was
added 2-butyne (71.4 µL, 0.91 mmol) at -78 °C. The mixture
was slowly warmed to room temperature and stirred overnight.
The hexane was partially removed under reduced pressure
until crystallization took place (0 °C), yielding 8b as red
crystals after decantation that were suitable for X-ray struc-
1
ture determination (0.31 g, 93%): mp 173 °C (dec); H NMR
(C6D6, 500 MHz) δ 1.67 (s, 30H, C5(CH3)5), 1.76 (d, J ) 0.91
Hz, 3H, 3-CH3), 2.01 (d, J ) 0.61 Hz, 3H, 4-CH3), 4.57 (br s,
1H, dCHH), 5.65 (d/m, J ) 0.62 Hz, 1H, dCHH) (the chemical
shifts were assigned through an NOE experiment); 13C{1H}
NMR (C6D6, 125 MHz) δ 6.1 (3-CH3), 11.9 (C5(CH3)5), 20.3 (4-
CH3), 99.4 (C-CH3), 101.3 (dCH2), 118.9 (C5(CH3)5), 210.6
(TiCCH3), 213.6 (TiCd); EI-MS (69 °C) m/e (Irel) 398 (88) (M+),
381 (21), 368 (11), 353 (2), 333 (6), 318 (93) (Cp*2Ti)+, 299 (4),
262 (13), 216 (8), 199 (16), 181 (25), 159 (11), 136 (17), 121
(12), 119 (21), 105 (13), 101 (31), 91 (15), 86 (28), 83 (16), 71
(11), 57 (100); exact mass m/e 398.2453 (C26H38Ti), calculated
m/e 398.2447; IR (KBr) 2899 vs, 2719 w, 1632 m, 1568 m, 1533
w, 1494 m, 1434 s, 1375 s, 1262 w, 1098 w, 1064 m, 1022 s,
Exp er im en ta l Section
Gen er a l Con sid er a tion s. The preparation and handling
of the described compounds were performed under rigorous
exclusion of air and moisture under a nitrogen atmosphere,
using standard vacuum line and Schlenk techniques. All
solvents were dried with the appropriate drying agents and
distilled under a nitrogen atmosphere. Deuterated solvents
were degassed by freeze-pump-thaw cycles and dried over
molecular sieves (3, 4 Å) prior to use. 1H and 13C NMR spectra
were recorded on a Varian Unity 500 or VXR-300 spectrometer.
Chemical shifts are reported in ppm and referenced to residual
protons in deuterated solvents (benzene-d6, δ ) 7.15 ppm;
THF-d8, δ ) 1.78 and 3.58 ppm for 1H NMR spectroscopy;
benzene-d6 δ ) 126.96 ppm for 13C NMR spectroscopy). Mass
spectroscopic analyses were performed on a Finnigan MAT 95
mass spectrometer. Infrared spectra were recorded as KBr
pellets on a Perkin-Elmer 1720X FT-IR spectrometer. El-
emental analyses were carried out at the Analytische Labo-
ratorien in Lindlar, Germany.
844 s, 807 m, 745 w, 597 m, 548 w, 530 m, 451 w, 408 s cm-1
.
Anal. Calcd for C26H38Ti: C, 78.37; H, 9.61. Found: C, 78.10;
H, 9.67.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m eth ylen e-3,4-d ip h en yltita n a cyclobu ten e (8c). To a
solution of 11 (350 mg, 0.971 mmol) in 30 mL of hexane was
added diphenylacetylene (190 mg, 1.066 mmol) at -78 °C. The
mixture was slowly warmed to room temperature and stirred
overnight. The hexane was partially removed under reduced
pressure until crystallization took place (0 °C), yielding 8c after
decantation as a red microcrystalline solid (0.12 mg, 24%): mp
196 °C (dec); 1H NMR (C6D6, 500 MHz) δ 1.73 (s, 30H,
C5(CH3)5), 4.61 (d, J ) 1.22 Hz, 1H, dCHH), 5.69 (d, J ) 1.22
Hz, 1H, dCHH), 6.78 (d/m, J ) 8.40 Hz, 2H, o-H(4)), 6.85 (tr/
m, J ) 7.33 Hz, 1H, p-H(4)), 7.00 (m, 2H, m-H(4)), 7.12 (tr/m, J
) 7.33 Hz, 1H, p-H(3)), 7.25 (tr/m, J ) 7.78 Hz, 2H, m-H(3)),
7.42 (d/m, J ) 8.09 Hz, 2H, o-H(3)) (the chemical shifts were
assigned through an NOE experiment); 13C{1H} NMR (C6D6,
125 MHz) δ 12.4 (C5(CH3)5), 106.7 (dCH2), 113.3 (CPh), 120.8
(C5(CH3)5), 125.0 (p-C(4)), 126.0 (p-C(3)), 127.3 (m-C(4)), 128.6
(m-C(3)), 131.02 (o-C(4)), 131.3 (o-C(3)), 137.4 (ipso-C(4)), 142.4
(ipso-C(3)), 205.3 (TiCPh), 211.4 (TiCd); EI-MS (138 °C) m/e
(Irel) 522 (21) (M+), 505 (2), 439 (2), 398 (28), 377 (5), 353 (58),
332 (9), 318 (85) (Cp*2Ti)+, 317 (89), 267 (9), 242 (6), 218 (43),
178 (100), 162 (15), 147 (30), 136 (51), 121 (69), 119 (56), 105
(40), 91 (29), 84 (52), 77 (15), 65 (6); exact mass m/e 522.2766
(C36H42Ti), calculated m/e 522.2766; IR (KBr) 3063 m, 3048
The titanocene complexes Cp*2Ti(CHdCH2)(CH3) (11)9b and
Cp*2TiCH2CH2CdCH2 (3)7 were prepared by literature pro-
cedures. The reagents HCtCH (9.96% in He), Me3SiCtCSiMe3,
Bu3SnCtCSnBu3, MeCtCPh, Me3SiCtCPh, PhCtCH,
t-BuCtCH, Me3SiCtCH, and PhCtCCtCPh were purchased
from Aldrich. PhCtCPh, MeCtCEt, 2-pentyne, and 3-hexyne
were from Merck, MeCtCMe and 1-pentyne were from Fluka,
and MeCtCCtCMe was from ABCR.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m eth ylen etita n a cyclobu ten e (8a ). A solution of 11 (392.5
mg, 1.089 mmol) in 30 mL of toluene was frozen, and 274 mL
(1.226 mmol) of an acetylene/helium mixture (9.96% acetylene
in helium) was added. The mixture was allowed to warm to
room temperature. The red solution was stirred overnight,
and the solvent was evaporated under reduced pressure,
yielding 8a as a reddish paste (0.38 g, 94%): 1H NMR (C6D6,
500 MHz) δ 1.65 (s, 30H, C5(CH3)5), 4.79 (d/d, J ) 4.58/2.24
Hz, 1H, dCHH), 5.66 (m, 1H, dCHH), 6.68 (d/d/d, J ) 12.1/

1184 Organometallics, Vol. 15, No. 4, 1996
Beckhaus et al.
m, 3004 m, 2985 s, 2950 s, 2908 s, 2718 w, 1938 w, 1880 w,
1799 w, 1716 w, 1631 w, 1589 s, 1560 m, 1486 m, 1471 w,
1436 s, 1375 s, 1261 m, 1178 w, 1151 w, 1070 m, 1026 s, 953
w, 905 w, 855 s, 841 w, 808 w, 779 s, 765 s, 721 s, 700 vs, 648
w, 623 w, 611 m, 591 w, 528 m, 502 w, 477 m, 445 m, 425 m,
δ 1.78 (s, 30H, C5(CH3)5), 4.57 (d, J ) 1.53 Hz, 1H, dCHH),
5.98 (d, J ) 1.22 Hz, 1H, dCHH), 6.83-6.90 (m, 1H, p-H(4)),
6.94-6.90 (tr/m, J ) 7.48 Hz, 1H, p-H(3)), 7.02 (tr/m, J ) 7.63
Hz, 2H, m-H(4)), 7.34 (tr/m, J ) 7.63 Hz, 4H, o-H(4), m-H(3)),
7.81 (d/d, J ) 8.24/1.22 Hz, 2H, o-H(3)) (the chemical shifts were
assigned through an NOE experiment); 13C{1H} NMR (C6D6,
125 MHz) δ 12.0 (C5(CH3)5), 94.6 (CtCPh), 108.4 (dCH2), 109.1
(CtCPh), 121.3 (C5(CH3)5), 124.7 (ipso-C(4)), 126.4 (p-C(4)), 126.7
(CPh), 126.8 (p-C(3)), 128.3 (m-C(4)), 128.4 (m-C(3)), 130.2 (o-
C(4)), 131.1 (o-C(3)), 135.6 (ipso-C(3)), 182.7 (TiCCt), 205.4
(TiCd); EI-MS (177 °C) m/e (Irel) 546 (7) (M+), 452 (8), 364
(100), 349 (25), 316 (83), 286 (8), 230 (13), 202 (14), 178 (10),
136 (12), 121 (20), 119 (18), 105 (13), 91 (18); exact mass m/e
546.2766 (C38H42Ti), calculated m/e 546.2766; IR (KBr) 3075
m, 3052 m, 3010 s, 2983 s, 2956 s, 2901 vs, 2719 w, 2139 vs,
1939 w, 1870 w, 1735 w, 1636 w, 1593 s, 1567 m, 1559 m,
1488 vs, 1473 s, 1449 s, 1439 s, 1377 vs, 1261 w, 1213 w, 1155
w, 1100 w, 1069 m, 1021 s, 993 w, 907 w, 863 m, 838 w, 806
w, 776 m, 754 vs, 717 m, 698 vs, 690 vs, 620 w, 601 w, 550 w,
408 m cm-1
. Anal. Calcd for C36H42Ti: C, 82.74; H, 8.10.
Found: C, 82.85; H, 7.89.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m eth ylen e-3,4-bis(tr im eth ylsilyl)titan acyclobu ten e (8d).
To a solution of 11 (480.8 mg, 1.334 mmol) in 40 mL of hexane
was added bis(trimethylsilyl)acetylene (333 µL, 1.467 mmol)
at -78 °C. The mixture was slowly warmed to room temper-
ature and stirred overnight. The hexane was removed under
reduced pressure, yielding 8d as a dark red oil (95%): 1H NMR
(C6D6, 500 MHz) δ 0.47 (s, 9H, SiMe3), 0.53 (s, 9H, SiMe3),
1.63 (s, 30H, C5(CH3)5), 5.12 (s, 1H, dCHH), 6.14 (s, 1H,
dCHH); SIMS-MS (Cs+, 20 kV, 3,4-dimethoxybenzyl alcohol)
positive ions m/e (Irel) 514 (4) (M+), 423 (2), 380 (8), 362 (15),
345 (7), 335 (6), 318 (100) (Cp*2Ti)+, 217 (6), 200 (15), 181 (8),
151 (37), 135 (3); negative ions m/e (Irel) 514 (24) (M+), 393 (7),
380 (19), 361 (100), 226 (39), 209 (13), 203 (21), 195 (12), 135
(14).
530 s, 507 w, 475 m, 434 s cm-1
.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
3-et h yl-4-m et h yl-2-m et h ylen et it a n a cyclob u t en e (17g).
Thermodynamic product, 75%. To a solution of 11 (257.0 mg,
0.713 mmol) in 30 mL of hexane was added 2-pentyne (75 µL,
0.784 mmol) at -78 °C. The mixture was slowly warmed to
room temperature and stirred overnight. The hexane was
removed under reduced pressure, yielding 17g and 16g in a
3:1 ratio as red crystals: 1H NMR (C6D6, 500 MHz) δ 1.15 (tr,
J ) 7.63 Hz, 3H, CH2CH3), 1.67 (s, 30H, C5(CH3)5), 1.99 (s,
3H, 4-CH3), 2.31 (q, J ) 7.63 Hz, 2H, CH2CH3), 4.54 (s, 1H,
dCHH), 5.66 (s, 1H, dCHH); 13C{1H} NMR (C6D6, 125 MHz)
δ 11.9 (C5(CH3)5), 15.1 (CCH2CH3), 19.8 (4-CH3), 27.9 (CCH2-
CH3), 100.8 (dCH2), 105.1 (CCH2CH3), 118.8 (C5(CH3)5), 210.2
(TiCCH3), 212.0 (TiCd); EI-MS (76 °C) m/e (Irel) 412 (39) (M+),
395 (5), 382 (4), 362 (4), 337 (5), 318 (43) (Cp*2Ti)+, 291 (3),
270 (12), 262 (4), 228 (8), 213 (10), 200 (29), 181 (21), 162 (32),
152 (40), 147 (76), 135 (100), 119 (86), 105 (48), 91 (46), 77
(22), 57 (22); exact mass m/e 412.2610 (C27H40Ti), calculated
m/e 412.2607.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
3 ,4 -b i s (t r i -n -b u t y l s t a n n y l )-2 -m e t h y l e n e t i t a n a c y -
clobu ten e (8e). To a solution of 11 (266.1 mg, 0.783 mmol)
in 40 mL of hexane was added bis(tri-n-butylstannyl)acetylene
(427.7 µL, 0.8121 mmol) at -78 °C. The mixture was slowly
warmed to room temperature and stirred overnight. The
hexane was removed under reduced pressure, yielding 8e as
a dark violet oil (94%): 1H NMR (C6D6, 500 MHz) δ 0.93 (tr,
J ) 7.33 Hz, 18H, Sn(CH2)3CH3), 0.99 (tr/m, J ) 8.09 Hz, 6H,
Sn(CH2)2CH2CH3), 1.04 (q/m, J ) 6.31 Hz, 6H, Sn(CH2)2CH2-
CH3), 1.39 (q/m, J ) 7.43 Hz, 12H, SnCH2CH2CH2CH3), 1.54
(tr/m, J ) 6.41 Hz, 6H, SnCH2(CH2)2CH3), 1.68 (m, J ) 7.18
Hz, 6H, SnCH2(CH2)2CH3), 1.67 (s, 30H, C5(CH3)5), 5.13 (s, 1H,
dCHH), 5.85 (s, 1H, dCHH); 13C{1H} NMR (C6D6, 125 MHz)
δ 11.7 (CH3), 12.4 (C5(CH3)5), 12.6 (CH2), 13.0 (CH3), 15.0
(CH2), 28.2 (CH2), 28.3 (CH2), 30.1 (SnCH2), 30.2 (SnCH2),
116.3 (dCH2), 115.1 (CSn(n-Bu)3), 115.8 (C5(CH3)5), 212.9
(TiCSn(nBu)3), 214.5 (TiCd).
Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-4-eth yl-3-m eth -
yl-2-m eth ylen etita n a cyclobu ten e (16g): 25%, kinetic prod-
uct; 1H NMR (C6D6, 500 MHz) δ 1.13 (tr, J ) 7.48 Hz, 3H,
CH2CH3), 1.67 (s, 30H, C5(CH3)5), 1.73 (s, 3H, 3-CH3), 2.51 (q,
J ) 7.43 Hz, 2H, CH2CH3), 4.56 (s, 1H, dCHH), 5.68 (s, 1H,
dCHH).
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2 -m e t h y l e n e -3 -m e t h y l -4 -( 1 -p r o p y n y l ) t i t a n a c y -
clobu ten e (16h ). To a solution of 11 (261.9 mg, 0.727 mmol)
in 30 mL of hexane was added 2,4-hexadiyne (62.4 mg, 0.8
mmol) at -78 °C. The mixture was slowly warmed to room
temperature and stirred overnight. The hexane was partially
removed under reduced pressure until crystallization took
place (0 °C), yielding 16h after decantation as red crystals
(207.3 mg, 67.5%): mp 153 °C (dec); 1H NMR (C6D6, 500 MHz)
δ 1.75 (s, 30H, C5(CH3)5), 2.03 (s, 3H, tCCH3), 2.10 (s, 3H,
dCCH3), 4.55 (d, J ) 1.53 Hz, 1H, dCHH), 5.71 (d, J ) 1.53
Hz, 1H, dCHH) (the chemical shifts were assigned through
an NOE experiment); 13C{1H} NMR (C6D6, 125 MHz) δ 5.7
(CCH3), 11.5 (CtCCH3), 11.9 (C5(CH3)5), 84.0 (CtCCH3), 104.2
(CCH3), 104.8 (dCH2), 114.7 (CtCCH3), 120.2 (C5(CH3)5), 185.9
(TiCt), 210.5 (TiCd); EI-MS (76 °C) m/e (Irel) 422 (12) (M+),
407 (5), 337 (5), 318 (47), (Cp*2Ti)+, 270 (2), 239 (6), 200 (12),
181 (7), 162 (8), 152 (15), 147 (19), 135 (29), 119 (31), 105 (16),
86 (23), 57 (100); exact mass m/e 422.2453 (C28H38Ti), calcu-
lated m/e 422.2456; IR (KBr) 3018 w, 2981 s, 2904 vs, 2722 w,
2169 m, 2037 w, 1714 m, 1627 w, 1565 m, 1492 s, 1433 vs,
1379 vs, 1261 w, 1165 w, 1065 m, 1023 s, 964 w, 853 s, 806 m,
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
4-m et h yl-2-m et h ylen e-3-p h en ylt it a n a cyclobu t en e (17j)
(57%). To a solution of 11 (233.6 mg, 0.648 mmol) in 30 mL
of hexane was added methylphenylacetylene (89.2 µL, 0.713
mmol) at -78 °C. The mixture was slowly warmed to room
temperature and stirred overnight. The hexane was removed
under reduced pressure, yielding 17j and 16j as a dark red
oil: 1H NMR (C6D6, 500 MHz) δ 1.72 (s, 30H, C5(CH3)5), 2.02
(s, 3H, 4-CH3), 4.54 (d, J ) 0.61 Hz, 1H, dCHH), 5.55 (d, J )
0.61 Hz, 1H, dCHH), 7.12 (m, 1H, p-H), 7.32 (tr/m, 2H, m-H),
7.38 (d/m, 2H, o-H); 13C{1H} NMR (C6D6, 125 MHz) δ 12.0 (C5-
(CH3)5), 21.1 (4-CH3), 104.3 (dCH2), 110.2 (CPh), 119.6 (C5-
(CH3)5), 125.5 (p-, m-C), 131.3 (o-C), 144.1 (ipso-C), 210.7
(TiCCH3), 211.8 (Ti-Cd).
Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-3-m eth yl-2-m e-
1
th ylen e-4-p h en yl)tita n a cyclobu ten e (16j): 43%; H NMR
(C6D6, 500 MHz) δ 1.66 (s, 30H, C5(CH3)5), 2.10 (s, 3H, 3-CH3),
4.62 (d, J ) 0.91 Hz, 1H, dCHH), 5.78 (d, J ) 1.22 Hz, 1H,
dCHH), 6.96 (m, 1H, p-H), 7.24 (tr/m, 2H, m-H), 7.46 (d/m,
2H, o-H); 13C{1H} NMR (C6D6, 125 MHz) δ 10.5 (3-CH3), 12.3
(C5(CH3)5), 103.8 (dCH2), 105.0 (CCH3), 120.1 (C5(CH3)5), 124.4
(p-, m-C), 130.3 (o-C), 136.1 (ipso-C), 204.7 (TiCPh), 215.2
(TiCd).
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m eth ylen e-3-p r op yltita n a cyclobu ten e (17f). Cycload-
dition product, 40%. To a solution of 11 (273.7 mg, 0.759
mmol) in 30 mL of hexane was added 1-pentyne (82 µL, 0.835
597 m, 573 w, 548 w, 506 m, 480 w, 416 s cm-1
.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m et h ylen e-3-p h en yl-4-(2-p h en yl-1-et h yn yl)t it a n a cy-
clobu ten e (16i). To a solution of 11 (268.8 mg, 0.746 mmol)
in 30 mL of hexane was added 1,4-diphenylbutadiyne (150.8
mg, 0.746 mmol) at -78 °C. The mixture was slowly warmed
to room temperature and stirred overnight. The hexane was
partially removed under reduced pressure until crystallization
took place (0 °C), yielding 16i after decantation as red crystals
1
(350.5 mg, 86%): mp 134 °C (dec); H NMR (C6D6, 500 MHz)

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1185
mmol) at -78 °C. The mixture was slowly warmed to room
temperature and stirred overnight. The hexane was removed
under reduced pressure, yielding 17f and 19f in a 1:1.5 ratio
as a red microcrystalline solid: 1H NMR (C6D6, 500 MHz δ
1.07 (tr, J ) 7.33 Hz, 3H, CH2CH2CH3), 1.66 (s, 30H, C5(CH3)5),
2.08 (m, 2H, CH2CH2CH3), 2.23 (tr/d, J ) 1.53 Hz, 2H, CH2-
CH2CH3), 4.57 (m, 1H, dCHH), 5.73 (m, 1H, dCHH), 7.39 (m,
1H, TiCH); 13C{1H} NMR (C6D6, 125 MHz) δ 11.9 (C5(CH3)5),
15.2 (CH2CH2CH3), 21.7 (CH2CH2CH3), 23.7 (CH2CH2CH3),
102.4 (dCH2), 111.1 (dCsCH2), 118.9 (C5(CH3)5), 199.3 (TiCH),
210.4 (TiCd).
Bis(η5-p en t a m et h ylcyclop en t a d ien yl)-1-p en t yn ylvi-
n yltita n iu m (19f): 60%, C-H activation product; 1H NMR
(C6D6, 500 MHz) δ 0.95 (tr, J ) 7.33 Hz, 3H, CH2CH2CH3),
1.50 (q, J ) 7.22 Hz, 2H, CH2CH2CH3), 1.85 (s, 30H, C5(CH3)5),
2.25 (tr, J ) 7.02 Hz, 2H, CH2CH2CH3), 4.95 (tr/m, J ) 11.3
Hz, 1H, dCHH), 5.66 (d/d, J ) 11.1/1.68 Hz, 2H, dCHH/R-
H); 13C{1H} NMR (C6D6, 125 MHz) δ 12.8 (C5(CH3)5), 14.1 (CH2-
CH2CH3), 23.5 (CH2CH2CH3), 30.0 (CH2CH2CH3), 117.1 (dCH2),
117.6 (tCCH2CH2CH3), 121.5 (C5(CH3)5), 151.3 (TiCt), 213.9
(TiCd).
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-m e t h y le n e -4-(t r i m e t h y ls i ly l)-3-p h e n y lt i t a n a c y -
clobu ten e (17k ). To a solution of 11 (416.7 mg, 1.156 mmol)
in 40 mL of hexane was added 1-(trimethylsilyl)-2-pheny-
lacetylene (0.25 mL, 1.271 mmol) at -78 °C. The mixture was
slowly warmed to room temperature and stirred overnight. The
hexane was partially removed under reduced pressure until
crystallization took place (-25 °C), yielding 17k after decanta-
tion as small red crystals suitable for X-ray structure deter-
mination (485.0 mg, 51%, mp 175 °C (dec)): 1H NMR (C6D6,
500 MHz) δ 0.14 (s, 9H, SiMe3), 1.75 (s, 30H, C5(CH3)5), 4.71
(d, J ) 1.53 Hz, 1H, dCHH), 5.37 (d, J ) 1.22 Hz, 1H, dCHH),
7.11 (tr/m, J ) 7.48 Hz, 1H, p-H), 7.24 (tr/m, J ) 7.63 Hz, 2H,
m-H), 7.36 (d/m, J ) 6.41 Hz, 2H, o-H) (the chemical shifts
were assigned through an NOE experiment); 13C{1H} NMR
(C6D6, 125 MHz) δ 4.8 (SiMe3), 12.6 (C5(CH3)5), 108.6 (dCH2),
119.9 (C5(CH3)5), 126.0 (p-C), 127.7 (m-C), 129.8 (CPh), 131.1
(o-C), 141.0 (ipso-C), 215.2 (TiCSiMe3), 218.0 (TiCd); EI-MS
(112 °C) m/e (Irel) 518 (3) (M+), 382 (7), 362 (26), 344 (10), 335
(13), 317 (52) (Cp*2TiH)+, 268 (8), 211 (3), 200 (100), 181 (12),
159 (26), 136 (45), 121 (57), 105 (30), 91 (18), 77 (8), 65 (3);
exact mass m/e 518.2845 (C30H38Ti), calculated m/e 518.2848;
IR (KBr) 3079 m, 3055 m, 2958 s, 2893 s, 2717 w, 1937 w,
1734 w, 1629 w, 1592 m, 1559 w, 1490 s, 1455 s, 1436 s, 1375
s, 1259 m, 1240 s, 1196 w, 1175 w, 1100 w, 1071 m, 1020 m,
964 w, 907 w, 860 vs, 831 s, 772 s, 755 m, 701 vs, 675 m, 625
w, 601 w, 472 m, 451 w, 424 s, 403 s cm-1. Anal. Calcd for
1567 s, 1540 m, 1483 vs, 1436 s, 1377 s, 1291 w, 1219 m, 1201
s, 1171 w, 1067 m, 1021 s, 959 w, 907 w, 889 s, 810 w, 783 m,
755 vs, 691 vs, 597 w, 546 m, 533 m, 509 m, 448 m, 424 m,
. Anal. Calcd for C30H38Ti: C, 80.70; H, 8.58.
Found: C, 80.18; H, 8.88.
P r ep a r a tion of P h en yla cetylen e-d . Phenylacetylene (2
mL) was dissolved in 10 mL of hexane, cooled to -78 °C, and
treated with butyllithium. The suspension was warmed to
room temperature and hydrolyzed with D2O. The organic
phase was dried over Na2SO4 and distilled. According to the
NMR spectrum, the phenylacetylene was deuterated to at least
96%.
409 m cm-1
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
(2-p h en yl-1-eth yn yl)vin yltita n iu m -vin yl-d (19l-D). To a
solution of 11 (152.9 mg, 0.424 mmol) in 20 mL of hexane was
added phenylacetylene-d (0.048 mg, 0.466 mmol) at -78 °C.
The mixture was slowly warmed to room temperature and
stirred overnight. The hexane was partially removed under
reduced pressure until crystallization took place (0 °C), yield-
ing 19l-D after decantation as light red crystals (mp 136 °C
(dec)): 1H NMR (C6D6, 500 MHz) δ 1.84 (s, 30H, C5(CH3)5),
5.01 (d, J ) 3.66 Hz, 1H, dCHH), 5.66 (d, J ) 3.96 Hz, 1H,
dCHH), 6.97 (tr/m, J ) 7.48 Hz, 1H, p-H), 7.09 (tr/m, J )
7.63 Hz, 2H, m-H), 7.45 (d/m, J ) 8.24 Hz, 2H, o-H); IR (KBr)
3072 m, 3048 w, 3005 s, 2982 s, 2901 vs, 2720 w, 2119 m [ν-
(C-D)], 2067 m, 1956 w, 1940 m, 1884 w, 1813 w, 1786 m,
1746 w, 1663 w, 1592 s, 1566 m, 1530 m, 1483 vs, 1436 vs,
1389 w, 1376 vs, 1290 w, 1201 vs, 1171 m, 1109 s, 1066 s,
1023 vs, 958 w, 907 w, 893 vs, 810 m, 782 s, 755 vs, 691 vs,
597 m, 546 s, 533 s, 519 w, 497 s, 409 s cm-1
.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
(3,3-d im eth yl-1-bu tyn yl)vin yltita n iu m (19m ). To a solu-
tion of 11 (301.1 mg, 0.835 mmol) in 30 mL of hexane was
added 3,3-dimethyl-1-butyne (113 µL, 0.919 mmol) at -78 °C.
The mixture was slowly warmed to room temperature and
stirred overnight. The hexane was partially removed under
reduced pressure until crystallization took place (0 °C), yield-
ing 19m after decantation as orange crystals (0.34 g, 95.4%,
mp 70 °C (dec >140 °C)): 1H NMR (THF-d8, 500 MHz) δ 1.12
(s, 9H, C(CH3)3), 1.85 (s, 30H, C5(CH3)5), 4.47 (d/d, J ) 18.0/
4.58 Hz, 1H, dCHH), 5.13 (d/d, J ) 14.0/4.58 Hz, 1H, dCHH),
5.43 (d/d, J ) 18.0/14.0 Hz, 1H, R-H); 13C{1H} NMR (C6D6,
125 MHz) δ 12.9 (C5(CH3)5), 28.2 (C(CH3)3), 31.8 (C(CH3)3),
117.3 (dCH∞), 121.4 (C5(CH3)5), 125.1 (tCC(CH3)), 149.1
(TiCt), 213.9 (TiCd); EI-MS (72 °C) m/e (Irel) 426 (9) (M+),
344 (7), 318 (59) (CP*2Ti)+, 291 (5), 270 (17), 248 (11), 181 (10),
164 (4), 159 (9), 152 (12), 147 (22), 136 (100), 119 (42), 105
(28), 91 (23), 77 (16), 67 (12), 57 (30); exact mass m/e 426.2769
(C28H42Ti), calculated m/e 426.2766; IR (KBr) 3077 w, 2959
vs, 2938 s, 2898 vs, 2861 s, 2719 w, 2071 s, 1784 w, 1634 br
m, 1541 m, 1492 m, 1451 s, 1435 s, 1377 s, 1356 m, 1261 w,
1241 s, 1217 w, 1200 w, 1066 m, 1020 s, 891 m, 793 s, 727 m,
C
30H38Ti: C, 76.42; H, 8.94. Found: C, 75.87; H, 8.98.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
(2-p h en yl-1-eth yn yl)vin yltita n iu m (19l). To a solution of
11 (330 mg, 0.916 mmol) in 30 mL of hexane was added
phenylacetylene (111 µL, 1.01 mmol) at -78 °C. The mixture
was slowly warmed to room temperature and stirred overnight.
The hexane was partially removed under reduced pressure
until crystallization took place (0 °C), yielding 19l after
decantation as light red crystals suitable for X-ray structure
determination (365.0 mg, 89%, mp 144 °C (dec)): 1H NMR
(C6D6, 500 Mhz) δ 1.85 (s, 30H, C5(CH3)5), 5.03 (d/d, J ) 17.2/
4.73 Hz, 1H, dCHH), 5.61 (d/d, J ) 17.4/14.0 Hz, 1H, R-H),
5.67 (d/d, J ) 14.0/4.58 Hz, 1H, dCHH), 6.97 (tr/m, J ) 7.48
Hz, 1H, p-H), 7.08 (tr/m, J ) 7.79 Hz, 2H, m-H), 7.46 (d/m, J
) 7.02 Hz, 2H, o-H); 13C{1H} NMR (THF-d8, 125 MHz) δ 12.7
(C5(CH3)5), 116.8 (dCH2), 118.3 (tCPh), 122.4 (C5(CH3)5), 126.3
(p-C), 127.8 (ipso-C), 128.5 (m-C), 130.8 (o-C), 162.0 (TiCt),
214.9 (TiCd); EI-MS (121 °C) m/e (Irel) 446 (13) (M+), 438 (2),
419 (2), 380 (7), 362 (3), 353 (31), 344 (6), 337 (24), 318 (100)
(Cp*2Ti)+, 284 (25), 264 (3), 249 (5), 218 (37), 200 (21), 181
(16), 162 (8), 147 (19), 136 (29), 129 (47), 119 (37), 105 (22), 91
(23), 77 (14); exact mass m/e 446.2453 (C30H38Ti), calculated
m/e 446.2453; IR (KBr) 3072 m, 3047 w, 3007 m, 2982 m, 2901
vs, 2861 s, 2721 w, 2067 w, 1940 w, 1780 w, 1636 w, 1592 m,
678 w, 615 w, 596 w, 549 w, 540 w, 506 m, 462 m, 419 m cm-1
.
Anal. Calcd for C28H42Ti: C, 78.85, H, 9.93. Found: C, 78.94;
H, 9.30.
P r ep a r a tion of Bis(η5-cyclop en ta d ien yl)[2-(tr im eth -
ylsilyl)-1-eth yn yl]vin yltita n iu m (19n ). To a solution of 11
(263.7 mg, 0.732 mmol) in 30 mL of hexane was added
(trimethylsilyl)acetylene (114 µL, 0.805 mmol) at -78 °C. The
mixture was slowly warmed to room temperature and stirred
overnight. The hexane was removed under reduced pressure,
yielding 19n as an orange powder (291 mg, 89.9%, mp 68 °C
(dec >120 °C)): 1H NMR (C6D6, 500 MHz) δ 0.27 (s, 9H, SiMe3),
1.81 (s, 30H, C5(CH3)5), 4.97 (d/d, J ) 17.9/4.43 Hz, 1H,
dCHH), 5.49 (d/d, J ) 18.0/14.0 Hz, 1H, R-H), 5.63 (d/d, J )
14.0/4.28 Hz, 1H, dCHH); 13C{1H} NMR (C6D6, 125 MHz) δ
0.74 (SiMe3), 12.8 (C5(CH3)5), 117.5 (dCH2), 119.7 (tCSiMe3),
121.9 (C5(CH3)5), 183.4 (TiCt), 214.7 (TiCd); EI-MS (101 °C)
m/e (Irel) 442 (17) (M+), 247 (3), 415 (3), 318 (100) (Cp*2Ti)+,
280 (25), 204 (5), 182 (17), 159 (7), 136 (6), 119 (6), 83 (6), 73
(7); exact mass m/e 442.2535 (C27H42TiSi), calculated m/e
442.2535; IR (KBr) 3014 w, 2983 m, 2951 s, 2899 s, 2719 w,

1186 Organometallics, Vol. 15, No. 4, 1996
Beckhaus et al.
Ta ble 6. Cr ysta l Da ta a n d P a r a m eter s of
Str u ctu r e Refin em en t for 8b, 17k , a n d 19l
Ta ble 8. P osition a l P a r a m eter s a n d Estim a ted
Sta n d a r d Devia tion s for 17k a
8b
17k
19l
atom
x
y
z
B (Å2)
formula
fw
space group (no.)
crystal data
a (Å)
C26H38Ti
398.49
P21/n (14)
C33H46SiTi
518.72
P21/n (14)
C30H38Ti
446.54
P21/c (14)
Ti
Si
C1
C2
C3
C4
C5
C6
0.1592(1)
0.1594(2)
-0.0314(5)
-0.0069(5)
0.1087(5)
-0.1423(6)
0.0548(7)
0.1423(8)
0.3428(6)
-0.1123(6)
-0.1116(7)
-0.2065(7)
-0.2989(7)
-0.3026(7)
-0.2084(6)
0.0097(6)
0.0114(6)
0.1453(7)
0.2285(6)
0.1434(6)
-0.1130(6)
-0.1112(7)
0.1743(8)
0.3712(7)
0.1834(8)
0.2430(6)
0.3549(6)
0.3917(6)
0.3070(6)
0.2161(5)
0.1715(7)
0.4416(7)
0.5137(6)
0.3310(7)
0.1239(6)
0.18324(5)
0.36211(8)
0.2173(3)
0.2833(3)
0.2861(3)
0.2046(3)
0.3702(3)
0.4469(3)
0.3559(3)
0.3408(3)
0.3820(3)
0.4369(3)
0.4503(3)
0.4097(3)
0.3545(3)
0.1431(3)
0.0897(3)
0.0625(3)
0.1000(3)
0.1491(3)
0.1809(3)
0.0587(3)
-0.0048(3)
0.0819(4)
0.1910(3)
0.1482(3)
0.1383(3)
0.2039(3)
0.2549(3)
0.2206(3)
0.0949(3)
0.0763(3)
0.2186(4)
0.3318(3)
0.2542(3)
-0.12605(5)
-0.01181(9)
-0.1783(3)
-0.1294(3)
-0.0794(3)
-0.2267(3)
0.0852(3)
2.86(2)
3.87(4)
3.1(1)
3.0(1)
2.8(1)
4.2(1)
5.2(2)
6.2(2)
5.7(2)
3.4(1)
4.9(2)
5.7(2)
5.4(2)
5.5(2)
4.4(1)
3.4(1)
4.0(1)
4.5(1)
3.9(1)
3.7(1)
5.9(1)
7.1(2)
8.5(2)
7.3(2)
6.8(2)
4.2(1)
4.3(1)
4.3(1)
4.1(1)
3.8(1)
6.3(2)
7.3(2)
6.4(2)
5.8(2)
5.2(1)
8.680(2)
17.702(5)
14.997(4)
90.85(2)
2304(2)
4
1.149
3.73
25
9.671(2)
19.239(2)
15.849(1)
91.77(1)
2947(1)
4
1.169
29.79
25
9.222(2)
10.495(2)
26.73(2)
101.54(4)
2535(3)
4
1.170
3.46
-20
Mo KR
0.7107
0.35 × 0.50
× 0.55
4860
3 e θ e 25
(h, k, (l)
b (Å)
c (Å)
â (deg)
-0.0685(4)
0.0260(4)
V (Å3)
C7
C8
C9
Z
d
-0.1413(3)
-0.2121(3)
-0.2214(4)
-0.1607(4)
-0.0904(4)
-0.0796(4)
-0.0140(3)
-0.0745(3)
-0.0758(3)
-0.0175(3)
0.0215(3)
calc (g cm-3
)
µ (cm-1
)
C10
C11
C12
C13
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
temperature (°C)
radiation
Mo KR
0.7107
Cu KR
1.5418
λ (Å)
crystal dimensions
0.40 × 0.30 0.70 × 0.50
× 0.50 × 0.40
measured reflections 8973 10684
3 e θ e 30 5 e θ e 65
(mm-3
)
scan range (deg)
Ewald spere
sec. ext coeff
observed indep
reflns
(h, k, (l)
(h, k, (l)
not refined E ) 1.96 × 10-7 not refined
0.0168(4)
4250
2667
2004
-0.1207(4)
-0.1201(4)
0.0163(4)
I >
1σ(I)
252
1σ(I)
317
0.5σ(I)
214
parameters refined
agreement factors
R
0.0978(3)
-0.2620(3)
-0.2054(3)
-0.1718(3)
-0.2135(3)
-0.2684(3)
-0.3179(3)
-0.2005(4)
-0.1141(4)
-0.2096(4)
-0.3348(3)
0.091
0.067
1.483
0.58
0.061
0.064
1.113
0.67
0.134
0.100
1.884
0.64
Rw
GOF
res el density (e Å-3
)
Ta ble 7. P osition a l P a r a m eter s a n d Estim a ted
Sta n d a r d Devia tion s for 8ba
atom
x
y
z
B (Å2)
Ti
C1
C2
C3
C4
C5
C6
0.16821(6)
0.0435(4)
0.1839(4)
0.3079(4)
-0.0958(4)
0.1914(6)
0.4626(5)
0.3300(4)
0.1864(4)
0.0801(4)
0.1613(4)
0.3147(4)
0.4813(4)
0.1577(5)
-0.0859(5)
0.1007(5)
0.4515(4)
0.1491(4)
0.0037(4)
0.0133(4)
0.1664(5)
0.2501(4)
0.1829(6)
-0.1428(4)
-0.1240(5)
0.2226(7)
0.4185(5)
0.86619(3)
0.8791(2)
0.9038(2)
0.9068(2)
0.8700(2)
0.9235(3)
0.9342(3)
0.7576(2)
0.7400(2)
0.7353(2)
0.7476(2)
0.7630(2)
0.7546(2)
0.7192(2)
0.7122(2)
0.7265(2)
0.7679(2)
1.0026(2)
0.9732(2)
0.9260(2)
0.9283(2)
0.9746(2)
1.0612(2)
0.9983(3)
0.8913(3)
0.9031(3)
0.9954(3)
0.24208(3)
0.3603(2)
0.4027(2)
0.3479(2)
0.4019(2)
0.5018(2)
0.3738(3)
0.2738(2)
0.3076(2)
0.2371(2)
0.1577(2)
0.1806(2)
0.3238(3)
0.4035(2)
0.2430(3)
0.0658(2)
0.1193(3)
0.2207(2)
0.2025(2)
0.1263(2)
0.0972(2)
0.1559(2)
0.2902(3)
0.2452(3)
0.0784(3)
0.0067(3)
0.1464(4)
2.490(8)
3.77(7)
4.25(7)
3.99(7)
5.98(9)
7.5(1)
a
Anisotropically refined atoms are given in the form of the
isotropic equivalent displacement parameter, defined as (4/3)[a2â11
+ b2â22 + c2â33 + ac(cos â)â13].
in 20 mL of hexane, cooled to -30 °C, and treated with
cyclohexaneisonitrile (58.5 µL, 0.47 mmol). The mixture was
warmed to room temperature within 5 min, and after 2 h the
solvent was removed under reduced pressure. After the
remaining liquid was cooled to -78 °C, green metallic crystals
were formed (205 mg, 86%, mp 146 °C (dec)): 1H NMR (C6D6,
500 MHz) δ 1.07-1.18 (q/tr, J ) 12.8/3.70 Hz, 1H), 1.20-1.31
(q/tr, J ) 13.0/3.36 Hz, 3H), 1.42-1.51 (q/d, J ) 12.3/2.98 Hz,
3H), 1.57-1.63 (m, 2H), 1.95-1.97 (m, 1H), all signals CH2
ring protons 1.74 (s, 30H, C5(CH3)5), 1.92 (d, J ) 0.61 Hz, 3H,
CH3), 1.98 (s, 3H, CH3), 3.40 (d, J ) 0.92 Hz, 1H, dCHH),
3.72 (tr/tr, J ) 11.0/3.66 Hz, 1H, NCH), 5.98 (d, J ) 0.92 Hz,
1H, dCHH); 13C{1H} NMR (C6D6, 125 MHz) δ 13.0 (C5(CH3)5),
15.0 (CH3), 17.0 (CH3), 26.2, 26.3, 36.8, all signals CH2 ring
carbons 61.8 (dNCH), 112.1 (dCH2), 120.0 (C5(CH3)5), 137.8
(dC(CH3)CdC), 161.9 (dC(CH3)CdN), 208.0 (TiCdCH2), 225.1
(TiCdN); EI-MS (151 °C) m/e (Irel) 507 (0.23) (M+), 505 (0.31),
424 (6), 398 (14), 353 (8), 318 (100) (Cp*2Ti)+, 181 (8), 119 (6),
107 (7), 55 (6); exact mass m/e 507.3345 (C33H49NTi), calculated
m/e 507.3343; IR (KBr) 3017 m, 2988 s, 2932 vs, 2851 vs, 2715
w, 1592 s, 1560 s [ν(CdN)], 1494 m, 1450 s, 1433 s, 1373 s,
1341 m, 1282 m, 1229 m, 1180 w, 1159 w, 1142 w, 1086 w,
1063 m, 1021 s, 970 w, 923 w, 901 w, 880 m, 857 w, 842 w,
809 w, 664 w, 636 w, 617 w, 596 w, 545 w, 505 w, 463 m, 432
m, 421 m cm-1. Anal. Calcd for C33H49NTi: C, 78.08; H, 9.73;
N, 2.76. Found: C, 77.91; H, 9.58; N, 2.86.
7.3(1)
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
3.52(6)
3.60(6)
3.88(7)
3.89(7)
3.49(6)
7.3(1)
7.1(1)
8.0(1)
7.7(1)
7.0(1)
4.21(7)
4.27(7)
5.20(8)
5.39(9)
5.12(8)
7.8(1)
7.9(1)
10.2(1)
11.3(2)
9.7(1)
a
Anisotropically refined atoms are given in the form of the
isotropic equivalent displacement parameter, defined as (4/3)[a2â11
+ b2â22 + c2â33 + ac(cos â)â13].
2016 s, 1803 w, 1735 w, 1707 w, 1702 w, 1697 w, 1686 w, 1677
w, 1654 w, 1629 m, 1561 w, 1556 w, 1541 w, 1492 m, 1434 s,
1377 s, 1253 w, 1242 vs, 1216 w, 1065 w, 1016 m, 900 m, 854
vs, 836 vs, 755 m, 692 vs, 606 w, 597 w, 510 w, 448 w, 413 w
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-(cycloh exylim in o)-5-m eth ylen e-3,4-d ip h en yltita n a cy-
clop en ten e (25c). 8c (99.8 mg, 0.191 mmol) was dissolved
in 20 mL of hexane, cooled to -30 °C, and treated with
cyclohexaneisonitrile (23.8 µL, 0.191 mmol). The mixture was
warmed to room temperature within 15 min, and after 1 h
the solvent was removed under reduced pressure, yielding pale
cm-1
. Anal. Calcd for C27H42Ti: C, 73.27; H, 9.56. Found:
C, 73.04; H, 9.48.
P r ep a r a tion of Bis(η5-p en ta m eth ylcyclop en ta d ien yl)-
2-(cycloh exylim in o)-3,4-d im eth yl-5-m eth ylen etita n a cy-
clop en ten e (25b). 8b (187.4 mg, 0.47 mmol) was dissolved

Reactivity of Acetylenes with [Cp*2TidCdCH2]
Organometallics, Vol. 15, No. 4, 1996 1187
Ta ble 9. P osition a l P a r a m eter s a n d Estim a ted
Sta n d a r d Devia tion s for 19la
166.1 (dC(Ph)CdN), 210.8 (TiCdCH2), 215.1 (TiCdN); EI-MS
(27 °C) m/e (Irel) 522 (100) (M - C6H11NC)+, 518 (11), 505 (12),
440 (6), 386 (10), 377 (8), 353 (9), 340 (21), 318 (97) (Cp*2Ti)+,
242 (9), 230 (61), 203 (27), 181 (47), 178 (26), 134 (18), 119
(43), 105 (23), 91 (36), 77 (18), 67 (78), 57 (71); IR (KBr) 3041
w, 3012 w, 2923 vs, 2989 vs, 2849 s, 2717 w, 2602 w, 2358 w,
1942 w, 1636 m, 1598 m, 1572 w [ν(CdN)], 1535 m, 1484 m,
1440 s, 1375 s, 1340 m, 1294 m, 1261 w, 1233 w, 1176 w, 1069
m, 1023 m, 928 w, 892 w, 839 w, 807 m, 757 m, 740 s, 698 vs,
682 w, 620 w, 590 w, 520 w, 484 w, 464 w, 439 w cm-1. Anal.
Calcd for C43H53NTi: C, 81.75; H, 8.46; N, 2.22. Found: C,
81.36; H, 8.43; N, 2.14.
X-r a y Str u ctu r e Deter m in a tion of 8b, 17k , a n d 19l. For
all compounds geometry and intensity data were collected on
Enraf-Nonius CAD4 diffractometers equipped with graphite
monochromators. A summary of crystallographic data, data
collection, and refinement parameters is given in Table 6. The
structures of 8b and 19l were solved and refined with the SDP
package40a and 17k with MolEN.40b All non-hydrogen atoms
were refined (full matrix) anisotropically, and all hydrogen
atoms were treated as riding with idealized geometry [C-H
) 0.98 Å, Biso(H) ) 1.3Biso(C)]. For 8b the hydrogen atoms at
the exo-methylene group were refined isotropically. A statisti-
cal weighting scheme, w-1 ) σ2(Fo), was used for all reflections.
No absorption corrections were applied. Further details of the
crystal structure investigations are available on request from
the Fachinformationszentrum Karlsruhe, D-76344 Eggenstein-
Leopoldshafen (FRG), on quoting the depository numbers CSD-
404519 (8b), -404520 (17k ), and -404521 (19l).
atom
x
y
z
B (Å2)
Ti
C1
C2
C3
0.0904(2)
-0.165(1)
-0.028(1)
-0.0889(9)
-0.1944(9)
0.176(1)
0.025(1)
-0.039(1)
0.077(1)
0.210(1)
0.277(2)
-0.064(2)
-0.196(1)
0.064(2)
0.358(1)
0.308(1)
0.327(1)
0.232(1)
0.136(1)
0.193(1)
0.411(1)
0.466(1)
0.237(2)
0.024(1)
0.142(2)
-0.3187(9)
-0.384(1)
-0.505(1)
-0.555(1)
-0.493(1)
-0.374(1)
0.2306(2)
0.047(1)
0.092(1)
0.2582(9)
0.268(1)
0.344(1)
0.336(1)
0.405(1)
0.4556(9)
0.419(1)
0.290(1)
0.284(1)
0.435(1)
0.547(1)
0.480(1)
0.210(1)
0.132(1)
0.037(1)
0.053(1)
0.164(1)
0.308(1)
0.135(2)
-0.082(1)
-0.040(1)
0.214(2)
0.275(1)
0.165(1)
0.171(1)
0.282(1)
0.391(1)
0.390(1)
0.38972(7)
0.4087(5)
0.4242(4)
0.3288(3)
0.2940(3)
0.4684(4)
0.4619(4)
0.4218(5)
0.4002(3)
0.4315(4)
0.5164(5)
0.4992(5)
0.4006(6)
0.3574(6)
0.4349(6)
0.3533(4)
0.3942(4)
0.3874(4)
0.3385(5)
0.3180(4)
0.3398(6)
0.4383(5)
0.4211(6)
0.3147(6)
0.2633(4)
0.2511(3)
0.2305(4)
0.1886(5)
0.1699(4)
0.1891(4)
0.2302(4)
4.01(4)
7.5(4)
5.2(3)
4.1(2)
4.6(2)
6.9(3)
7.4(3)
7.4(4)
5.8(3)
6.1(3)
18.4(7)
21.3(5)
20.1(5)
17.5(8)
15.3(5)
6.0(3)
6.2(3)
6.8(3)
7.3(3)
6.5(3)
15.6(6)
13.6(5)
16.7(6)
19.5(5)
16.0(6)
4.9(3)
6.3(3)
8.4(4)
8.1(4)
7.6(4)
6.5(3)
C4
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C41
C42
C43
C44
C45
C46
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie. We thank Prof. Dr. G. E.
Herberich for his continuing interest. Ab initio calcula-
tions of alkynes by Dr. U. Bo¨hme, University of Freiberg,
are gratefully acknowledged.
a
Anisotropically refined atoms are given in the form of the
isotropic equivalent displacement parameter, defined as (4/3)[a2â11
+ b2â22 + c2â33 + ac(cos â)â13].
green crystals (110 mg, 91%, mp 201 °C (dec)): 1H NMR (C6D6,
300 MHz) δ 0.6-0.8 (q/m, 2H), 0.85-1.05 (m, 2H), 1.2-1.4 (m,
4H), 1.6-1.8 (m, 2H), all signals CH2 ring protons 1.87 (s, 30H,
C5(CH3)5), 3.05 (tr/tr, J ) 10.9/3.80 Hz, 1H, NCH), 3.51 (d, J
) 2.02 Hz, 1H, dCHH), 5.44 (d, J ) 2.01 Hz, 1H, dCHH),
6.85 (m, p-CH), 6.95 (tr/m, J ) 7.39 Hz, m-CH), 7.03 (tr/m, J
) 7.73 Hz, m-CH), 7.11 (d/m, J ) 6.05 Hz, o-CH); 13C{1H} NMR
(C6D6, 75 MHz) δ 13.3 (C5(CH3)5), 26.0, 26.2, 36.1, all signals
CH2 ring carbons 61.8 (dNCH), 119.6 (dCH2), 121.5 (C5(CH3)5),
125.6, 125.7 (both p-C), 127.3, 127.4 (both m-C), 129.5, 129.7
(both o-C), 141.8 (ipso-C), 142.3 (dC(Ph)CdC), 143.9 (ipso-C),
OM950783A
(40) (a) Frenz, B. Z. Enraf-Nonius, SDP, Version 5.0; Enraf-
Nonius: Delft, The Netherlands, 1988. (b) MolEN, An Interactive
Structure Solution Procedure, Enraf-Nonius: Delft, The Netherlands,
1990.
(41) J ohnson, C. K. Ortep, Oak Ridge Thermal Ellipsoid Program;
Oak Ridge National Laboratory ORNL-5138 (3rd revision); Oak Ridge
National Laboratory: Oak Ridge TN, 1975.
(42) Keller, E. Schakal 88, Program for the Graphical Representation
of Crystallographic and Molecular Models; University of Freiburg:
Freiburg, Germany, 1988.