Reaction Chemistry of Alkynyl-Functionalized Titanocenes. X-ray Structure Analyses of (η5-C5H4SiMe3) 2Ti(Cl)(CH2SiMe3)and[(η5-C 5H4SiMe3)2Ti(Cl)(C≡CSiMe 3)]CuBr

Article abstract of DOI:10.1021/ic960115x

The synthesis and reaction chemistry of the mono (σ-alkynyl) titanocene chlorides [Ti](Cl)(C≡CR) {[Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 2a, R = Ph; 2b, R = SiMe₃} is described. Treatment of compounds 2a and 2b with ClMgCH_2- SiMe₃ or LiC≡CR' yields [Ti](CH₂SiMe₃)(C≡CSiMe₃) (3) or [Ti](C≡CR)(C≡CR') (5a, R = Ph, R' = SiMe₃; 5b, R = R' = Ph; 5c, R = R' = SiMe₃), respectively. The reaction of compounds 2a, 2b, or Sa with polymeric [CuX]_n (X = Cl, Br, I) produces the heterobimetallic titanium-copper complexes {[Ti](Cl)(C≡CR)}CuX (6a, R = Ph, X = Cl; 6b, R = Ph, X = Br; 6c, R = Ph, X = I; 7a, R = SiMe₃, X = Cl; 7b, R = SiMe₃, X = Br) or {[Ti](C≡CPh)(C≡CSiMe₃)}CuX (8a, X = Cl; 8b, X = Br). While compounds 2a and 2b do not react with [AgX]_n (X = Cl, Br), it is found that the bis(σ-alkynyl)titanocene 5a is able to break down the polymeric structure of [AgX]_n to produce the heterobimetallic compounds {[Ti](C=CPh)(C=CSiMe₃)}AgX (10a, X = Cl; 10b, X = Br). Moreover, compound 8a can be synthesized by treatment of 2a or 2b with [CuC≡CR']_n (R' = SiMe₃, Ph). However, when compound 3 is reacted with [CuCl]_n under appropriate reaction conditions, the formation of {[Ti](C≡CSiMe₃)₂}CuCl (9b), [CuCH₂SiMe₃]₄, [Ti](Cl)(CH₂SiMe₃) (4), and [Ti]Cl₂ (1) is observed; a reaction mechanism for the formation of the latter compounds is discussed. The solid state structures of [Ti](Cl)(CH₂SiMe₃) (4) and {[Ti](Cl)(C≡CSiMe₃)}CuBr (7b) were determined. Crystals of 4 and 7b are monoclinic, space group P2₁/n. 4: C₂₀H₃₇ClSi₃Ti, cell constants a = 6.812(2) A?, b= 11.298(6) A?, c = 33.16(1) A?, β = 92.25(3)°, and Z = 4. 7b: C₂₁H₃₅BrClCuSi₃Ti, cell constants a = 13.257(7) A?,b= 10.470(5) A?, c = 20.39(1) A?, β= 100.91(3)°, and Z = 4.

Full text of DOI:10.1021/ic960115x

6266
Inorg. Chem. 1996, 35, 6266-6272
Reaction Chemistry of Alkynyl-Functionalized Titanocenes. X-ray Structure Analyses of
(η5-C5H4SiMe3)2Ti(Cl)(CH2SiMe3) and [(η5-C5H4SiMe3)2Ti(Cl)(CtCSiMe3)]CuBr
H. Lang,* W. Frosch, I. Y. Wu, S. Blau, and B. Nuber
Anorganisch-Chemisches Institut, Ruprecht-Karls-Universita¨t Heidelberg, Im Neuenheimer Feld 270,
D-69120 Heidelberg, Germany
ReceiVed January 31, 1996X
The synthesis and reaction chemistry of the mono (σ-alkynyl) titanocene chlorides [Ti](Cl)(CtCR) {[Ti] ) (η5-
C5H4SiMe3)2Ti; 2a, R ) Ph; 2b, R ) SiMe3} is described. Treatment of compounds 2a and 2b with ClMgCH2-
SiMe3 or LiCtCR′ yields [Ti](CH2SiMe3)(CtCSiMe3) (3) or [Ti](CtCR)(CtCR′) (5a, R ) Ph, R′ ) SiMe3;
5b, R ) R′ ) Ph; 5c, R ) R′ ) SiMe3), respectively. The reaction of compounds 2a, 2b, or 5a with polymeric
[CuX]n (X ) Cl, Br, I) produces the heterobimetallic titanium-copper complexes {[Ti](Cl)(CtCR)}CuX (6a, R
) Ph, X ) Cl; 6b, R ) Ph, X ) Br; 6c, R ) Ph, X ) I; 7a, R ) SiMe3, X ) Cl; 7b, R ) SiMe3, X ) Br) or
{[Ti](CtCPh)(CtCSiMe3)}CuX (8a, X ) Cl; 8b, X ) Br). While compounds 2a and 2b do not react with
[AgX]n (X ) Cl, Br), it is found that the bis(σ-alkynyl)titanocene 5a is able to break down the polymeric structure
of [AgX]n to produce the heterobimetallic compounds {[Ti](CtCPh)(CtCSiMe3)}AgX (10a, X ) Cl; 10b, X )
Br). Moreover, compound 8a can be synthesized by treatment of 2a or 2b with [CuCtCR′]n (R′ ) SiMe3, Ph).
However, when compound 3 is reacted with [CuCl]n under appropriate reaction conditions, the formation of
{[Ti](CtCSiMe3)2}CuCl (9b), [CuCH2SiMe3]4, [Ti](Cl)(CH2SiMe3) (4), and [Ti]Cl2 (1) is observed; a reaction
mechanism for the formation of the latter compounds is discussed. The solid state structures of [Ti](Cl)(CH2-
SiMe3) (4) and {[Ti](Cl)(CtCSiMe3)}CuBr (7b) were determined. Crystals of 4 and 7b are monoclinic, space
group P21/n. 4: C20H37ClSi3Ti, cell constants a ) 6.812(2) Å, b ) 11.298(6) Å, c ) 33.16(1) Å, â ) 92.25(3)°,
and Z ) 4. 7b: C21H35BrClCuSi3Ti, cell constants a ) 13.257(7) Å, b ) 10.470(5) Å, c ) 20.39(1) Å, â )
100.91(3)°, and Z ) 4.
Introduction
Recently, we have shown that the mono(σ-alkynyl)titanocene
[(η5-C5H2SiMe3)SiMe2]2Ti(Cl)(CtCSiMe3),1 the bis(σ-alkynyl)-
titanocenes [Ti](CtCR)2 {[Ti] ) (η5-C5H4SiMe3)2Ti; R ) Ph,
SiMe3},2,3 and the (σ)-1,3-butadiyn-1-yltitanocenes [Ti](Cl)-
(CtCsCtCR) and [Ti](CtCsCtCR)2 (R ) C2H5, SiMe3)5
can be used as organometallic chelating ligands (organometallic
π-tweezers) for the stabilization of monomeric copper(I) frag-
situations are found for 1,3-butadiyn-1-yltitanocenes.5 More-
over, the organic groups X in type B molecules can easily be
transferred to suitable substrates.4 For enantioselective transfer
reactions the starting material must provide chiral information.
The chiral information can either arise from the bis(alkynyl)
titanocene building block (η5-C5H5)(η5-C5H4R)Ti(CtCR′)-
(CtCR′′) (R ) R′ ) R′′ ) singly bonded organic ligand; R′ *
R′′) or from a single enantiomeric pure alkynyl ligand, giving
rise to optically active organometallic π-tweezer molecules [Ti]-
(CtCR)(CtCR*). For the synthesis of titanocenes, which
contain different alkynyl ligands the selective preparation of
[Ti](Cl)(CtCR) compounds {[Ti] ) (η5-C5H4SiMe3)2Ti; R )
Ph, SiMe3} is necessary at first.
ments CuX (X ) singly bonded organic or inorganic ligand)
(type A and B molecules).
The CuX moiety in type A molecules is complexed by the
chloro group and the alkynyl ligand of the titanocene fragment
[Ti](Cl)(CtCR), whereas in compounds of type B the CuX
entity is η2-coordinated by both CtCR groups of the organo-
metallic chelating ligand [Ti](CtCR)2.1-4 Similar bonding
* To whom correspondence should be addressed. Fax: +49-6221-54-
5707. E-mail: bo0@ix.urz.uni-heidelberg.de.
X Abstract published in AdVance ACS Abstracts, September 1, 1996.
(1) Lang, H.; Blau, S; Pritzkow, H.; Zsolnai, L. Organometallics 1995,
14, 1850.
(2) (a) Lang, H.; Ko¨hler, K.; Blau, S. Coord. Chem. ReV. 1995, 143, 113.
(b) Lang, H.; Weinmann, M. Synlett 1996, 1.
Here, we describe the synthesis of mono(σ-alkynyl)titanocene
chlorides, as well as their reaction behavior toward metallated
alkynes and copper(I) compounds.
(3) (a) Lang, H.; Herres, M.; Zsolnai, L.; Imhof, W.; J. Organomet. Chem.
1991, 409, C7. (b) Janssen, M. D.; Herres, M.; Zsolnai, L.; Spek, A.
L.; Grove, D. M., Lang, H.; van Koten, G. Inorg. Chem. 1996, 35,
2476. (c) Lang, H.; Herres, M.; Ko¨hler, K.; Blau, S.; Weinmann, S.;
Weinmann, M.; Rheinwald, G.; Imhof, W. J. Organomet. Chem. 1995,
505, 85.
(4) (a) Janssen, M. D.; Herres, M.; Dedieu, A.; Spek, A. L.; Grove, D.
M.; Lang, H.; van Koten, G. J. Chem. Soc., Chem. Commun. 1995,
925. (b) Janssen, M. D.; Herres, M.; Zsolnai, L.; Grove, D. M.; Lang,
H.; van Koten, G. Organometallics 1995, 14, 1098. (c) Janssen, M.
D.; Ko¨hler, K.; Herres, M.; Dedieu, A.; Spek, A. L.; Grove, D. M.;
Lang, H.; van Koten, G. J. Am. Chem. Soc. 1996, 118, 4817. (d)
Janssen, M. D.; Smeets, W. J. J.; Spek, A. L.; Grove, D. M.; Lang,
H.; van Koten, G. J. Organomet. Chem. 1995, 505, 123. (e) Lang,
H.; Ko¨hler, K.; Bu¨chner, M. Chem. Ber. 1995, 128, 525. (f) Frosch,
W. Diplom Thesis, Universita¨t Heidelberg, 1995.
Experimental Section
General Methods. All reactions were carried out under an
atmosphere of nitrogen using standard Schlenk techniques. Tetrahy-
drofuran (THF) and diethyl ether (Et2O) were purified by destillation
from sodium/benzophenone ketyl; n-pentane was purified by destillation
from calcium hydride. Infrared spectra were obtained with a Perkin-
Elmer 983G spectrometer. 1H NMR spectra were recorded on a Bruker
AC 200 spectrometer operating at 200.132 MHz in the Fourier transform
mode; 13C NMR spectra were recorded at 50.323 MHz. Chemical shifts
are reported in δ units (parts per million) downfield from tetrameth-
ylsilane with the solvent as the reference signal. FD, EI, and FAB
(5) Lang, H.; Weber, C. Organometallics 1995, 14, 4415.
S0020-1669(96)00115-2 CCC: $12.00 © 1996 American Chemical Society

Alkynyl-Functionalized Titanocenes
Inorganic Chemistry, Vol. 35, No. 21, 1996 6267
mass spectra were recorded on a Finnigan 8400 mass spectrometer
operating in the positive-ion mode. Melting points were determined
with use of analytically pure samples, which were sealed in nitrogen-
purged capillaries on a Gallenkamp MFB 595 010 M melting point
apparatus. Microanalyses were performed by the Organisch-Chemi-
sches Institut der Universita¨t Heidelberg.
Synthesis of (η5-C5H4SiMe3)2Ti(Cl)(CtCR) (2a, R ) Ph; 2b, R
) SiMe3). A solution of LiCtCR (10.50 mmol; R ) Ph, 1.14 g; R )
SiMe3, 1.09 g)6,7 in diethyl ether (100 mL) was added at 20 °C to a
suspension of (η5-C5H4SiMe3)2TiCl28 (1) (3.93 g, 10.00 mmol) in diethyl
ether (100 mL) within 2 h. After another 15 min of stirring, all volatiles
were removed in Vacuo. Filtration of the residue through Celite (n-
pentane, 3 × 3 cm) and evaporation of the volatiles in Vacuo yielded
an orange-red powder (2a) or oil (2b). Compound 2a could be
crystallized from n-pentane at -30 °C.
Synthesis of (η5-C5H4SiMe3)2Ti(CtCPh)(CtCSiMe3) (5a).
A
6,7
solution of LiCtCSiMe3 (1.09 g, 10.50 mmol) in diethyl ether (50
mL) was added within 15 min to a solution of 2a (4.60 g, 10.00 mmol)
in diethyl ether (50 mL) at 20 °C and stirred for 1 h. Evaporation of
the volatiles in Vacuo, filtration of the residue with n-pentane through
Celite (3 × 3 cm), and removing the volatiles yielded a red oil.
Yield: 375 mg (0.72 mmol, 72%).
IR (KBr, cm-1): 2067 [νCtCPh]; 2014 [νCtCSiMe ]. MS (FD): m/e
3
520 [M+]. 1H NMR (200 MHz, CDCl3): δ 0.07 (s, 9H, CtCSiMe3);
0.28 (s, 18H, C5H4SiMe3); 6.19 (m, 2H, C5H4); 6.27 (m, 2H, C5H4);
6.67 (m, 2H, C5H4); 6.73 (m, 2H, C5H4); 7.1-7.4 (m, 5H, Ph). 13C-
{1H} NMR (50 MHz, CDCl3): δ 0.3 (CtCSiMe3); 0.4 (C5H4SiMe3);
113.0 (C5H4); 113.5 (C5H4); 122.8 (C5H4); 122.9 (C5H4); 124.8 (C5H4,
Cipso); 125.7 (CtCPh); 126.5 (Ph); 128.0 (Ph); 130.0 (Ph); 131.7 (Ph);
135.6 (CtCSiMe3); 152.8 (TiCtCPh); 171.1 (TiCtCSiMe3). Anal.
Calcd for C29H40Si3Ti (520.79): C, 66.88; H, 7.74. Found: C, 66.80;
H, 7.75.
2a. Yield: 4.13 g (9.00 mmol, 90%). Mp: 101 °C. IR (KBr, cm-1):
2077 [νCtC]. MS (FD): m/e 458 [M+]. 1H NMR (200 MHz,
CDCl3): δ 0.32 (s, 18H, C5H4SiMe3); 6.3 (m, 2H, C5H4); 6.5 (m, 2H,
C5H4); 6.7 (m, 2H, C5H4); 6.8 (m, 2H, C5H4); 7.2-7.3 (m, 5H, Ph).
13C{1H} NMR (50 MHz, CDCl3): δ 0.1 (SiMe3); 114.8 (C5H4); 117.0
(C5H4); 125.0 (C5H4); 125.6 (C5H4); 126.3 (C5H4, Cipso); 122.4
(CtCPh); 126.6 (Ph); 128.0 (Ph); 130.1 (Ph); 131.3 (Ph, Cipso); 148.3
(TiCtC). Anal. Calcd for C24H31ClSi2Ti (459.03): C, 62.80; H, 6.81.
Found: C, 62.78; H, 6.82.
Synthesis of {(η5-C5H4SiMe3)2Ti(Cl)(CtCPh)}CuX (6a, X ) Cl;
6b, X ) Br; 6c, X ) I). 2a (200 mg, 0.44 mmol) was added to a
suspension of [CuX]n (0.45 mmol; X ) Cl, 50 mg; X ) Br, 70 mg; X
) I, 80 mg) in tetrahydrofuran (50 mL) and stirred in the dark for 2 h.
The reaction solution was filtered through a pad of Celite and all volatile
materials were removed in Vacuo. Compounds 6a-6c were obtained
as orange colored solids.
2b. Yield: 3.55 g (7.80 mmol, 78%). IR (KBr, cm-1): 2022 [νCtC].
1H NMR (200 MHz, CDCl3): δ 0.10 (s, 9H, CtSiMe3); 0.27 (s, 18H,
C5H4SiMe3); 6.2 (m, 2H, C5H4); 6.4 (m, 2H, C5H4); 6.6 (m, 2H, C5H4);
6.7 (m, 2H, C5H4). Anal. Calcd for C21H35ClSi3Ti (455.17): C, 55.42;
H, 7.75. Found: C, 55.20; H, 7.86.
6a. Yield: 220 mg (0.40 mmol, 92%). Mp: 180 °C. IR (KBr,
cm-1): 1913 [νCtC]. MS (FD): m/e (%) 560 [M+] (20); 458 [M+
-
CuCl] (100). 1H NMR (200 MHz, CDCl3): δ 0.22 (s, 18H, C5H4-
SiMe3); 6.1 (m, 2H, C5H4); 6.3 (m, 2H, C5H4); 6.5 (m, 2H, C5H4); 6.6
(m, 2H, C5H4); 7.2-7.4 (m, 3H, Ph); 7.7-7.8 (m, 2H, Ph). 13C{1H}
NMR (50 MHz, CDCl3): δ -0.1 (C5H4SiMe3); 117.2 (C5H4); 117.6
(C5H4); 121.1 (C5H4); 121.9 (C5H4); 124.0 (C5H4, Cipso); 127.9 (Ph);
128.3 (CtCPh); 128.4 (Ph); 130.6 (Ph); 135.2 (Ph, Cipso); 145.8
(TiCtC). Anal. Calcd for C24H31Cl2CuSi2Ti (558.03): C, 51.66; H,
5.60. Found: C, 51.86; H, 5.80.
Synthesis of (η5-C5H4SiMe3)2Ti(Cl)(CH2SiMe3) (4). A solution
8a
of ClMgCH2SiMe3 (1.47 g, 10.00 mmol) in diethyl ether (50 mL)
8
was added dropwise at 25 °C to a solution of (η5-C5H4SiMe3)2TiCl2
(1) (3.58 g, 9.00 mmol) in CH2Cl2 (150 mL) and stirred for 2 h.
Afterward the volatiles were removed in Vacuo. The residue was
dispersed in diethyl ether (200 mL) and filtered through a pad of Celite
(diethyl ether, 3 × 3 cm). Concentration of the filtrate yielded 4 as
orange needles. Yield: 3.2 g (7.20 mmol, 80%).
6b. Yield: 220 mg (0.37 mmol, 85%). Mp: 169 °C. IR (KBr,
cm-1): 1933 [νCtC]. MS (FD): m/e 602 [M+]. 1H NMR (200 MHz,
CDCl3): δ 0.22 (s, 18H, C5H4SiMe3); 6.2 (m, 2H, C5H4); 6.3 (m, 2H,
C5H4); 6.5 (m, 2H, C5H4); 6.6 (m, 2H, C5H4); 7.2-7.4 (m, 3H, Ph),
7.7-7.8 (m, 2H, Ph). 13C{1H} NMR (50 MHz, CDCl3): δ -0.1 (C5H4-
SiMe3); 117.3 (C5H4); 117.6 (C5H4); 121.2 (C5H4); 122.0 (C5H4); 124.0
(C5H4, Cipso); 128.1 (Ph); 128.3 (CtCPh); 128.4 (Ph); 130.9 (Ph); 135.4
(Ph, Cipso); 146.2 (TiCtC). Anal. Calcd for C24H31BrClCuSi2Ti
(602.46): C, 47.85; H, 5.19. Found: C, 47.68; H, 5.28.
Mp: 97 °C. MS (EI): m/e (%) 429 [M+ - Me] (3); 401 [M+
-
3Me] (26); 357 [M+ - CH2SiMe3] (100). 1H NMR (200 MHz,
CDCl3): δ 0.04 (s, 9H, CH2SiMe3); 0.29 (s, 18H, C5H4SiMe3); 2.14
(s, 2H, CH2SiMe3); 5.8 (m, 2H, C5H4); 6.1 (m, 2H, C5H4); 6.4 (m, 2H,
C5H4); 7.1 (m, 2H, C5H4). 13C{1H} NMR (50 MHz, CDCl3): δ 0.1
(C5H4SiMe3); 2.9 (CH2SiMe3); 75.6 (CH2SiMe3); 110.9 (C5H4); 117.0
(C5H4); 121.4 (C5H4); 128.0 (C5H4); 129.3 (C5H4, Cipso). Anal. Calcd
for C20H37ClSi3Ti (445.10): C, 53.97; H, 8.38. Found: C, 53.71; H,
8.27.
6c. Yield: 270 mg (0.42 mmol, 95%). Mp: 163 °C. IR (KBr,
cm-1): 1926 [νCtC]. MS (FAB): m/e (%) 521 [M+ - I] (90); 322
[M+ - CuI - C2Ph - Cl] (100). 1H NMR (200 MHz, CDCl3): δ
0.24 (s, 18H, C5H4SiMe3); 6.2 (m, 2H, C5H4); 6.3 (m, 2H, C5H4); 6.5
(m, 2H, C5H4); 6.6 (m, 2H, C5H4); 7.2-7.4 (m, 3H, Ph); 7.7-7.8 (m,
2H, Ph). 13C{1H} NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3); 117.4
(C5H4); 118.0 (C5H4); 121.3 (C5H4); 122.3 (C5H4); 124.2 (C5H4, Cipso);
128.0 (Ph); 128.3 (Ph); 128.5 (CtCPh); 131.3 (Ph); 135.3 (Ph, Cipso);
147.9 (TiCtC). Anal. Calcd for C24H31ClCuISi2Ti (649.48): C, 44.38;
H, 4.81. Found: C, 43.92; H, 4.86.
Synthesis of {(η5-C5H4SiMe3)2Ti(Cl)(CtCSiMe3)}CuX (7a, X )
Cl; 7b, X ) Br). 2b (200 mg, 0.44 mmol) was reacted with [CuX]n
(0.45 mmol; X ) Cl, 50 mg; X ) Br, 70 mg) under appropriate reaction
conditions (see synthesis of compounds 6a-6c), yielding compounds
7a and 7b as orange solids.
Synthesis of (η5-C5H4SiMe3)2Ti(CH2SiMe3)(CtCSiMe3) (3). (η5-
C5H4SiMe3)2Ti(Cl)(CH2SiMe3) (4) (450 mg, 1.00 mmol) was added at
-25 °C in one portion to a solution of LiCtCSiMe36,7 (115 mg, 1.10
mmol) in diethyl ether (100 mL). After 2 h of stirring at 25 °C all
volatiles were removed in Vacuo, the residue was dissolved in n-pentane
(200 mL) and filtered through Celite (n-pentane, 3 × 3 cm). Removal
of the solvent yielded compound 3 as an orange-red oil. Yield: 430
mg (0.85 mmol, 85%).
IR (KBr, cm-1): 2018 [νCtC]. MS (EI): m/e (%) 418 [M+ - CH2-
SiMe3] (100); 322 [M+ - CH2SiMe3 - C2SiMe3] (30). 1H NMR (200
MHz, C6D6): δ 0.07 (s, 9H, CtCSiMe3); 0.24 (s, 9H, CH2SiMe3);
0.37 (s, 18H, C5H4SiMe3); 1.70 (s, 2H, CH2SiMe3); 5.4 (m, 2H, C5H4);
5.9 (m, 2H, C5H4); 6.2 (m, 2H, C5H4); 7.1 (m, 2H, C5H4). 13C{1H}
NMR (50 MHz, C6D6): δ 0.6 (C5H4SiMe3); 0.7 (CtCSiMe3); 3.3 (CH2-
SiMe3); 79.3 (CH2SiMe3); 111.3 (C5H4); 115.8 (C5H4); 120.2 (C5H4);
123.4 (CtCSiMe3); 124.4 (C5H4); 124.9 (C5H4, Cipso); 166.9 (TiCtC).
Anal. Calcd for C25H46Si4Ti (505.86): C, 59.24; H, 9.15. Found: C,
59.17; H, 9.09.
7a. Yield: 230 mg (0.42 mmol, 95%). Mp: 167°C. IR (KBr,
cm-1): 1901 [νCtC]. MS (FD): m/e 552 [M+]. 1H NMR (200 MHz,
CDCl3): δ 0.23 (s, 18H, C5H4SiMe3); 0.32 (s, 9H, CtCSiMe3); 6.1
(m, 2H, C5H4); 6.2 (m, 2H, C5H4); 6.4 (m, 2H, C5H4); 6.5 (m, 2H,
C5H4). Anal. Calcd for C21H35Cl2CuSi3Ti (554.12): C, 45.52; H, 6.37.
Found: C, 45.14; H, 6.51.
7b. Yield: 250 mg (0.42 mmol, 94%). Mp: 150 °C. IR (KBr,
(6) Lang, H.; Keller, H.; Imhof, W.; Martin, S. Chem. Ber. 1990, 123,
427 and references cited therein.
cm-1): 1899 [νCtC]. MS (FAB): m/e (%) 598 [M+] (6); 517 [M+
-
Br] (75); 418 [M+ - CuBr - Cl] (10); 357 [M+ - CuBr - C2SiMe3]
(50); 322 [M+ - CuBr - Cl - C2SiMe3] (100). 1H NMR (200 MHz,
CDCl3): δ 0.25 (s, 18H, C5H4SiMe3); 0.34 (s, 9H, CtCSiMe3); 6.1
(m, 2H, C5H4); 6.2 (m, 2H, C5H4); 6.4 (m, 2H, C5H4); 6.5 (m, 2H,
C5H4). 13C{1H} NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3); 0.2
(CtCSiMe3); 116.9 (C5H4); 118.3 (C5H4); 120.8 (C5H4); 121.8 (C5H4);
(7) Brandsma, L.; Verkruijsse, H. PreparatiVe Polar Organometallic
Chemistry 1; Springer Verlag: Berlin, 1987, and literature cited therein.
(8) (a) Lappert, M. F.; Pickett, C. J.; Riley, P. I.; Yarrow, P. I. W. J.
Chem. Soc., Dalton Trans. 1981, 805. (b) Lappert, M. F.; Riley, P. I.;
Yarrow, P. I. W.; Atwood, J. L.; Hunter, W. E.; Zaworotho, M. J. J.
Chem. Soc., Dalton Trans. 1981, 814. (c) Klouras, N.; Nastopoulos,
V. Monatsh. Chem. 1991, 122, 551.

6268 Inorganic Chemistry, Vol. 35, No. 21, 1996
Lang et al.
Table 1. Crystallographic Parameters for Compounds 4 and 7b
127.5 (C5H4, Cipso); 133.5 (CtCSiMe3), 176.6 (TiCtC). Anal. Calcd
for C21H35BrClCuSi3Ti (598.55): C, 42.14; H, 5.89. Found: C, 42.14;
H, 5.91.
Synthesis of {(η5-C5H4SiMe3)2Ti(CtCPh)(CtCSiMe3)}CuX (8a,
X ) Cl; 8b, X ) Br). 5a (150 mg, 0.29 mmol) was reacted with
[CuX]n (0.30 mmol; X ) Cl, 30 mg; X ) Br, 40 mg) in the above
described manner (see synthesis of compounds 6a-6c), yielding
compounds 8a and 8b as orange colored solids.
4
7b
empirical formula
fw
space group
a, Å
b, Å
c, Å
C20H37ClSi3Ti
445.10
P21/n
6.812(2)
11.298(6)
33.16(1)
92.25(3)
2550.1(8)
1.16
C21H35BrClCuSi3Ti
598.55
P21/n
13.257(7)
10.470(5)
20.39(1)
100.91(3)
2779.0(9)
1.43
8a. Yield: 165 mg (0.27 mmol, 92%). Mp: 186 °C. IR (KBr,
â, deg
volume, Å3
cm-1): 1984, 1956 [νCtCPh]; 1917 [νCtCSiMe ]. MS (FD): m/e 583 [M+
3
F
calc, g cm-3
Z
- Cl]. 1H NMR (200 MHz, CDCl3): δ 0.22 (s, 18H, C5H4SiMe3);
0.33 (s, 9H, CtCSiMe3); 6.01 (m, 2H, C5H4); 6.04 (m, 2H, C5H4);
6.14 (m, 2H, C5H4); 6.20 (m, 2H, C5H4); 7.2-7.4 (m, 3H, Ph); 7.5-
7.7 (m, 2H, Ph). 13C{1H} NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3);
0.4 (CtCSiMe3); 113.6 (C5H4); 113.9 (C5H4); 116.7 (C5H4); 116.9
(C5H4); 122.7 (C5H4, Cipso); 123.5 (CtCPh); 128.0 (Ph); 128.5 (Ph);
131.9 (Ph); 135.5 (Ph, Cipso); 138.0 (CtCSiMe3); 144.5 (TiCtCPh);
169.1 (TiCtCSiMe3). Anal. Calcd for C29H40ClCuSi3Ti (619.79): C,
56.20; H, 6.50. Found: C, 55.89; H, 6.27.
4
4
radiation (λ, Å)
temp, K
Mo KR (0.710 73)
295
Mo KR (0.710 73)
295
no. of unique reflns
no. of data
5000
2217
5942
3521
with I g 2.5σ(I)
a
R1
0.064
0.051
0.058
0.048
b
Rw
a R1 ) [∑||Fo| - |Fc||/∑|Fo|] only for observed reflections. b Rw
)
8b. Yield: 190 mg (0.28 mmol, 96%). Mp: 190 °C. IR (KBr,
2
2
[∑[Fo - Fc2)2]/∑[w(Fo )2]]0.5 for all reflections.
cm-1): 1984, 1958 [νCtCPh]; 1913 [νCtCSiMe ]. MS (FAB): m/e (%)
3
583 [M+ - Br] (60); 322 [M+ - CuBr - C2Ph - C2SiMe3] (100). 1H
NMR (200 MHz, CDCl3): δ 0.22 (s, 18H, C5H4SiMe3); 0.35 (s, 9H,
CtCSiMe3); 6.0 (m, 2H, C5H4); 6.1 (m, 2H, C5H4); 6.15 (m, 2H, C5H4);
6.2 (m, 2H, C5H4); 7.2-7.4 (m, 3H, Ph); 7.5-7.6 (m, 2H, Ph). 13C{1H}
NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3); 0.4 (CtCSiMe3); 113.8
(C5H4); 114.1 (C5H4); 116.9 (C5H4); 117.1 (C5H4); 122.9 (C5H4, Cipso);
123.8 (CtCPh); 128.0 (Ph); 128.8 (Ph); 132.4 (Ph); 135.5 (Ph); 138.4
(CtCSiMe3); 145.0 (TiCtCPh); 169.8 (TiCtCSiMe3). Anal. Calcd
for C29H40BrCuSi3Ti (664.24): C, 52.44; H, 6.07. Found: C, 51.96;
H, 5.80.
Synthesis of {(η5-C5H4SiMe3)2Ti(CtCPh)(CtCSiMe3)}AgX (10a,
X ) Cl; 10b, X ) Br). 5a (100 mg, 0.19 mmol) was reacted with
[AgX]n (0.20 mmol; X ) Cl, 30 mg; X ) Br, 40 mg) under appropriate
reaction conditions (see synthesis of compounds 6a-6c), yielding
compounds 10a and 10b as orange solids.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Compound 4
bond lengths
bond angles
Ti(1)-Cl(1)
2.316(2)
2.209(6)
1.865(6)
2.115
Cl(1)-Ti(1)-C(19)
Ti(1)-C(19)-Si(3)
D1-Ti(1)-D2a
93.5(2)
133.9(3)
131.8
Ti(1)-C(19)
C(19)-Si(3)
Ti(1)-D1a
Ti(1)-D2a
2.071
a D1, D2 ) Centers of the cyclopentadienyl ligands.
subsequent difference Fourier techniques (SHELXS 8610 ). Refinement
on F was carried out by full-matrix least-squares techniques (SHELX
7611 ) using reflections with I g 2.5σ(I) during refinement. Hydrogen
atoms were included in calculated positions, riding model. Non-
hydrogen atoms were refined with anisotropic displacement parameters.
Weights were optimized in final refinement cycles. Neutral atom
scattering factors and anomalous dispersion corrections for structure
refinements of compounds 4 and 7b were taken from ref 12. Crystal
data and numerical details of structure determinations and refinements
are collected in Table 1. Selected geometrical details of structures of
4 and 7b are listed in Tables 2 and 3.
10a. Yield: 90 mg (0.17 mmol, 81%). Mp: 143 °C. IR (KBr,
cm-1): 2015 [νCtCPh]; 1939 [νCtCSiMe ]. MS (FAB): m/e (%) 629 [M+
3
- Cl] (45); 322 [M+ - AgCl - C2Ph - C2SiMe3) (100). 1H NMR
(200 MHz, CDCl3): δ 0.25 (s, 18H, C5H4SiMe3); 0.34 (s, 9H,
CtCSiMe3); 6.32 (pt, JHH ) 2.4 Hz, 4H, C5H4); 6.37 (pt, JHH ) 2.4
Hz, 4H, C5H4); 7.3-7.4 (m, 3H, Ph); 7.6-7.8 (m, 2H, Ph). 13C{1H}
NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3); 0.4 (CtCSiMe3); 115.7
(C5H4); 116.2 (C5H4); 119.0 (C5H4); 119.1 (C5H4); 122.1 (TiCtCPh);
125.0 (C5H4, Cipso); 128.3 (Ph); 128.5 (Ph); 131.2 (Ph); 132.0
(TiCtCPh, JCAg ) 16.4 Hz); 139.9 (Ph, Cipso); 143.7 (TiCtCSiMe3);
154.8 (TiCtCSiMe3, JCAg ) 16.4 Hz). Anal. Calcd for C29H40AgClSi3-
Ti (664.10): C, 52.45; H, 6.07. Found: C, 52.31; H, 5.97.
Results
Synthesis of Compounds [Ti](Cl)(CtCR) (2). The mono-
(σ-alkynyl)-substituted compounds [Ti][Cl)(CtCR) {[Ti] ) (η5-
C5H4SiMe3)2Ti; 2a, R ) Ph; 2b, R ) SiMe3} are obtained in
90% (2a) or 78% (2b) yield when titanocene dichloride [Ti]-
Cl2 (1) is reacted with equimolar amounts of LiCtCR (R )
Ph, SiMe3) in diethyl ether or tetrahydrofuran solutions at 25
°C. The bis(σ-alkynyl)titanocenes [Ti](CtCR)2 (5b, R ) Ph;
5c, R ) SiMe3) were formed as byproducts in 5-10% yield,
depending on the reaction conditions used.
10b. Yield: 120 mg (0.17 mmol, 88%). Mp: 151 °C. IR (KBr,
cm-1): 2015 [νCtCPh]; 1939 [νCtCSiMe ]. MS (FAB): m/e (%) 708 [M+]
(2); 629 [M+ - Br] (45); 322 [M+ -3AgBr - C2Ph - C2SiMe3] (100).
1H NMR (200 MHz, CDCl3): δ 0.26 (s, 18H, C5H4SiMe3); 0.35 (s,
9H, CtCSiMe3); 6.32 (pt, JHH ) 2.2 Hz, 2H, C5H4); 6.38 (pt, JHH
)
2.2 Hz, 6H, C5H4); 7.2-7.4 (m, 3H, Ph); 7.6-7.8 (m, 2H, Ph). 13C{1H}
NMR (50 MHz, CDCl3): δ 0.0 (C5H4SiMe3); 0.5 (CtCSiMe3); 115.7
(C5H4); 116.3 (C5H4); 119.1 (C5H4); 119.3 (C5H4); 122.0 (TiCtCPh);
125.0 (C5H4, Cipso); 128.3 (Ph); 128.7 (Ph); 131.5 (Ph); 133.1 (Ph,
(1)
C
ipso); 140.2 (TiCtCSiMe3); 144.2 (TiCtCPh, JCAg ) 16.4 Hz); 155.6
(TiCtCSiMe3, JCAg ) 16.4 Hz). Anal. Calcd for C29H40AgBrSi3Ti
(708.55): C, 49.16; H, 5.69. Found: C, 49.44; H, 5.69.
Structure Determination and Refinement of Compounds 4 and
7b. X-ray data were collected on a Siemens (Nicolet) R3m/V
diffractometer for orange crystals sealed in a glass capillary. Accurate
unit cell parameters and an orientation matrix were derived from the
setting angles of 37 well-centered reflections in the range 13° e 2θ e
26°. The unit cell parameters were checked for the presence of the
higher lattice symmetry.9 Data were corrected for Lorentz polarization
effects. An empirical absorption correction was applied based on five
reflections in the range 3° e 2θ e 52.5°, ω-scan 8.4° e ω˘ e 22.8°,
and ∆ω ) 1.2°. The structures were solved by direct methods and
After appropriate purification product 2a gave orange-red
crystals, which are stable for months in the solid state. In
contrast, compound 2b is obtained as an orange oil. In solution
(10) Sheldrick, G. M. SHELX 86. Program for crystal structure determi-
nation. University of Go¨ttingen, Go¨ttingen, Germany 1986.
(11) Sheldrick, G. M. SHELX 76. Program for crystal structure analysis.
University of Cambridge, U.K. 1976.
(12) Wilson, A. J. C., Ed. International Tables of Crystallography; Kluwer
Academic Publishers: Dordrecht, The Netherlands, 1993; Vol. C.
(9) Spek, A. L.; J. Appl. Crystallogr. 1988, 21, 578.

Alkynyl-Functionalized Titanocenes
Inorganic Chemistry, Vol. 35, No. 21, 1996 6269
Scheme 1. Synthesis of Compounds 5-9
both compounds slowly redistribute their ligands, thus forming
[Ti](CtCR)2 (5)13 and [Ti]Cl2 (1).8 Complexes 2 readily
dissolve in most common organic solvents.
Reaction of [Ti](Cl)(CtCR) (2) with Organic Nucleo-
philes. Reaction of [Ti](Cl)(CtCSiMe3) (2b) with equimolar
amounts of ClMgCH2SiMe3 in diethyl ether, after appropriate
workup, gave air-stable deep orange [Ti](CH2SiMe3)(CtCSiMe3)
(3) in 80% yield. Likewise, the preparation of compound 3
can be effected by treatment of [Ti](Cl)(CH2SiMe3) (4)8 with 1
molar equiv of LiCtCSiMe3 in diethyl ether solutions at -25
°C.
(2)
When compound 2a or 2b is reacted with LiCtCR′ (R′ )
Ph, SiMe3) in diethyl ether solution at 25 °C, the bis(σ-alkynyl)-
titanocenes [Ti](CtCR)(CtCR′) (5a-5c) are cleanly formed
in 90-95% yield. 5a is the first example of an organometallic
π-tweezer molecule, which contains two different σ-bonded
alkynyl ligands (route a, Scheme 1).
Compounds 3 and 5 are soluble in e.g. n-pentane and toluene
and can be precipitated as orange (3, 5c) or orange-red (5a,
5b) solids by cooling their n-pentane solutions to -50 °C.
Compounds 3 and 5a tend to melt when their crystals are
warmed to 25 °C.
Reaction of [Ti](Cl)(CtCR) (2) and [Ti](CtCPh)-
(CtCSiMe3) (5a) with Copper(I) Compounds. Equimolar
addition of [Ti](Cl)(CtCR) (2a, R ) Ph; 2b, R ) SiMe3) to a
suspension of polymeric [CuX]n (X ) Cl, Br, I) in tetrahydro-
furan at 25 °C resulted in the formation of the heterobimetallic
titanium-copper complexes {[Ti](Cl)(CtCR)}CuX (6, R ) Ph;
7, R ) SiMe3) in quantitative yield (route b, Scheme 1). These
compounds feature a monomeric CuX moiety, which is stabi-
lized by the alkynyl ligand CtCR and the chloro group of the
[Ti](Cl)(CtCR) fragment.
Compounds 6-9 are soluble in toluene, tetrahydrofuran and
acetone and can be precipitated as orange to red solids by
cooling their tetrahydrofuran/n-pentane solutions to -30 °C. In
the solid state 6 and 7 can be handled in air for a short period
of time while 8 and 9 are stable to air for months.
A further method for the preparation of the tweezer-like
molecules 8 and 9 is given by treatment of the mono(σ-alkynyl)-
substituted complex [Ti](CH2SiMe3)(CtCSiMe3) (3) with
equimolar amounts of [CuCl]n in diethyl ether at 25 °C. Besides
dinuclear {[Ti](CtCSiMe3)2}CuCl (9b),3 the titanocene dichlo-
ride [Ti]Cl2 (1),8 the neosilyl-substituted titanocene chloride [Ti]-
(Cl)(CH2SiMe3) (4),8 and tetrameric [CuCH2SiMe3]415 could be
isolated.
When [CuCtCR′]n (R′ ) SiMe3, Ph)14 is used instead of
[CuX]n (X ) Cl, Br, I), the heterobimetallic tweezer molecules
{[Ti](CtCR)(CtCR′)}CuCl (8a, R ) Ph, R′ ) SiMe3; 9a, R
) R′ ) Ph; 9b, R ) R′ ) SiMe3) are formed (route c, Scheme
1).
The latter molecules feature a monomeric copper(I) chloride
entity with the copper atom in a trigonal-planar environment.
The formation of compounds 8 and 9 by reaction of 2 with
(1/n)[CuCtCR′]n plausibly can be explained by taking an
intermediate such as {[Ti](Cl)(CtCR)}CuCtCR′ into account.
Intramolecular rearrangement of this complex affords the
tweezer-like molecules 8 and 9.
(3)
Moreover, the latter compounds can be synthesized by the
reaction of e.g. [Ti](CtCPh)(CtCSiMe3) (5a) with [CuX]n
(X ) Cl, Br) in tetrahydrofuran at 25 °C (route d, Scheme 1).
(13) (a) Lang, H.; Seyferth, D. Z. Naturforsch. 1990, 45b, 212. (b) for
related synthesis of (η5-C5H5)2Ti(CtCSiMe3)2 see: Wood, G. L.;
Knobler, C. B.; Hawthorne, M. F. Inorg. Chem. 1989, 28, 382.
(14) (a) Nast, R. Coord. Chem. ReV. 1982, 47, 89. (b) Corfield, P. W. R.;
Shearer, H. M. M. In Organometallic Compounds; Coates, G. E.,
Green, M. L. H., Wade, K., Eds.; Chapman and Hall: London, 1977;
Vol. 2. (c) Coates, G. E.; Perkin, C. J. Inorg. Nucl. Chem. 1961, 22,
59. (d) Haszeldine, R. W. J. Chem. Soc. 1951, 588.
Possible reaction pathways for the formation of the corre-
sponding products obtained by treatment of [Ti](CH2SiMe3)-
(CtCSiMe3) with [CuCl]n are given in Scheme 2.
(15) Jarvis, J. A. J.; Pearce, R.; Lappert, M. F. J. Chem. Soc., Dalton Trans.
1977, 999.

6270 Inorganic Chemistry, Vol. 35, No. 21, 1996
Lang et al.
Scheme 2. Possible Reaction Pathways for the Reaction of [Ti](CtCSiMe3)(CH2SiMe3) (3) with [CuCl]n
The ability of main-group element16-18 and organometallic
substituted alkynes1-5 to break down the polynuclear structure
of copper(I) compounds into discrete [CuX]n (n ) 1, 2, 3, ...)
aggregates is well-known. Therefore, we assume that the
alkynyl ligand Me3SiCtC in compound 3, as initial step,
coordinates in an η2-fashion to a copper(I) center, thus forming
the intermediate C (route a, Scheme 2). C either eliminates
1/4[CuCtCSiMe3]4 to produce [Ti](Cl)(CH2SiMe3) (4) (route
Another possibility to prepare molecule 9b is given by routes
f and g (Scheme 2). The reaction of [Ti](Cl)(CtCSiMe3) (2b)
with the earlier formed [CuCtCSiMe3]4 (route b, Scheme 2)
generates a molecule of composition D, which undergoes an
intramolecular rearrangement, thus yielding dinuclear 9b. This
reaction sequence could independently be evidenced by treat-
1
ment of 2b with equimolar amounts of /4[CuCtCSiMe3]4 in
diethyl ether at 25 °C (route c, Scheme 1).
1
b, Scheme 2) or eliminates /4[CuCH2SiMe3]4 to afford [Ti]-
When copper(I) halides are used instead of copper(I) acetyl-
ides, type D molecules could be isolated (see above). Since
the reaction sequence (a) f (c) f (f) f (g) (Scheme 2) gives
no rise to the formation of titanocene dichloride (1) we consider
this sequence to be of minor importance. As a final conclusion
the formation of the products obtained by the reaction of [Ti]-
(CH2SiMe3)(CtCSiMe3) (3) and [CuCl]n can best be explained
by the synthetic sequence (a) f (c) f (d) f (e) (Scheme 2).
(Cl)(CtCSiMe3) (2b) (route c, Scheme 2). This compound
exchanges its ligands under the reaction conditions applied to
yield [Ti]Cl2 (1) and [Ti](CtCSiMe3)2 (5c) (route d, Scheme
2). The final step of the proposed mechanism is the formation
of {[Ti](CtCSiMe3)2}CuCl (9b) on treatment of 5c with
[CuCl]n (route e, Scheme 2), the synthetic approach to the
tweezer-like molecules of type {[Ti](CtCSiMe3)2}CuCl most
commonly used.2,3
Structure of the Neosilyl-Substituted Titanocene Chloride
4. The molecular structure of compound 4 has been determined
by X-ray diffraction (Figure 1). Crystallographical parameters
are given in Table 1; selected bond lengths and angles are listed
in Table 2.
(16) For example: (a) Gambarotta, S.; Floriani, C.; Chiesi-Villa, A.;
Guastini, C. J. Chem. Soc., Chem. Commun. 1983, 1156. (b) Lenders,
B.; Grove, D. M.; Smeets, W. J. J.; van der Sluis, P.; Spek, A. L.; van
Koten, G. Organometallics 1991, 10, 786. (c) Knotter, D. M.; Smeets,
W. J. J.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1990, 112,
5895.
Compound 4 crystallizes in the monoclinic space group P21/
n. The geometrical environment of the Ti(1) center is fixed by
the arrangement of the chloro group Cl(1), the CH2SiMe3 unit
and the η5-coordinated cyclopentadienyl ligands. The Ti(1)-
C(19) distance at 2.209(6) Å is similar to those titanium-to-
carbon bonds involving sp3-hybridized carbon atoms as found
in e.g. (η5-C5H5)2TiMe2 [2.170(2), 2.181(2) Å],19 (η5-C9H7)2-
TiMe2 [2.21(2) Å],20 and (η5-C5H5)2Ti(CH2Ph)2 [2.239(6),
2.210(5) Å].21 In accordance with this, the Ti(1)-Cl(1) distance
at 2.316(2) Å in 4 corresponds to other titanocene chloride
compounds described.1,8,22
(17) For example: (a) Coan, P. S.; Folting, K.; Huffman, J. C.; Caulton,
K. G. Organometallics, 1989, 8, 2724. (b) Gambarotta, S.; Strologo,
S.; Floriani, C.; Chiesi-Villa, A.; Guastini, C. Organometallics 1984,
3, 1444. (c) He, X.; Olmstead, M. M.; Power, P. P. J. Am. Chem.
Soc. 1992, 114, 9668. d) Uson, R.; Laguna, A.; Uson, A.; Jones, P.
G.; Meyer-Base, K. J. Chem. Soc., Dalton Trans. 1988, 341.
(18) (a) Stephan, D. W. Coord. Chem. ReV. 1989, 95, 41. (b) Nadasdi, T.
T.; Stephan, D. W. Organometallics 1992, 11, 116. (c) Maelger, H.;
Olbrich, F.; Kopf, J.; Abeln, D.; Weiss, E. Z. Naturforsch. 1992, 47B,
1276. (d) Ku¨ppers, H. J.; Wieghart, K.; Tsay, Y. H.; Kru¨ger, C.; Nuber,
B.; Weiss, J. Angew. Chem. 1987, 99, 583. (e) Braterman, P. S.;
Wilson, V. A. J. Organomet. Chem. 1971, 31, 131. (f) Thompson, J.
S.; Whitney, J. F.; Inorg. Chem. 1984, 23, 2813. (g) Manukata, M.;
Kitagawa, S.; Kawada, I.; Maekawa, M.; Shimono, H. J. Chem. Soc.,
Dalton Trans. 1992, 2225. (h) Reger, D. L.; Huff, M. F. Organome-
tallics 1992, 11, 69. (i) Lenders, B.; Kla¨ui, W. Chem. Ber. 1990, 123,
2233. (j) Ferrara, J. D.; Tessler-Youngs, C.; Youngs, W. J. Organo-
metallics 1987, 6, 676.
Structure of the Heterobimetallic Titanium-Copper Com-
plex 7b. In order to establish the solid state structure of
(19) Thewalt, U.; Wo¨hrle, T. J. Organomet. Chem. 1994, 464, C17.

Alkynyl-Functionalized Titanocenes
Inorganic Chemistry, Vol. 35, No. 21, 1996 6271
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Compound 7b
bond lengths
bond angles
Ti(1)-Cu(1)
2.958(3)
2.445(3)
2.107(9)
2.012(9)
2.102(8)
2.296(2)
2.314(3)
1.23(1)
2.072
Ti(1)-C(11)-Cu(1)
Ti(1)-C(11)-C(12)
Br(1)-Cu(1)-Cl(1)
Br(1)-Cu(1)-C(11)
Br(1)-Cu(1)-C(12)
Cl(1)-Cu(1)-C(12)
Cl(1)-Ti(1)-C(11)
C(11)-C(12)-Si(3)
D1-Ti(1)-D2a
91.8(3)
167.5(8)
108.8(1)
152.1(3)
117.7(3)
133.5(3)
92.4(2)
Ti(1)-Cl(1)
Ti(1)-C(11)
Cu(1)-C(11)
Cu(1)-C(12)
Cu(1)-Br(1)
Cu(1)-Cl(1)
C(11)-C(12)
D1-Ti(1)a
165.0(8)
132.3
D2-Ti(1)a
2.030
a D1, D2 ) Centers of the cyclopentadienyl ligands.
Figure 3. Comparison of interatomic bond lengths [Å] in compounds
[(η5-C5H4SiMe3)2Ti(Cl)(CtCSiMe3)]CuBr (7b) (left) and {[Me2Si(η5-
C5H2SiMe3)]2Ti(Cl)(CtCSiMe3)}CuCl (right).
Figure 1. ORTEP drawing (drawn at 50% probability level) of the
molecular geometry of compound 4 (with exclusion of the hydrogen
atoms) with the atom numbering scheme (Tables 1 and 2).
alkynyl titanocene chloride fragment. As a result of the dative
Cl(1)-Cu(1) bonding the Ti(1)-Cl(1) distance is significantly
lengthened from approximately 2.30 Å in titanocene chlo-
rides18,22 to 2.445(3) Å in 7b. A molecule that can be taken
into account for comparison is the doubly Me2Si-bridged
heterobimetallic titanium-copper complex {[Me2Si(η5-C5H2-
SiMe3)]2Ti(Cl)(CtCSiMe3)}CuCl.1 In this compound the
interatomic titanium-chloro distance is at 2.357(4) Å consider-
ably shorter than that in compound 7b (Figure 3). Reversed
bonding situations were observed for the copper-to-chloro
distances [7b, 2.314(3) Å; {[Me2Si(η5-C5H2SiMe3)]2Ti(Cl)-
(CtCSiMe3)}CuCl, 2.344(2) Å1] (Figure 3). The established
facts point to a stronger dative interaction between the chloro
and the copper atom in compound 7b.
The Cu(1)-Br(1) bond length at 2.296(2) Å in compound
7b is decisively shorter than the according distances in other
copper(I) bromide containing molecules [2.40-2.46 Å].3,23 As
a result of the η2-coordination of the CtCSiMe3 ligand to the
copper atom the Ti(1)-C(11)-C(12) [167.5(8)°], as well as the
C(11)-C(12)-Si(3) [165.0(8)°] units deviate from linearity.
Thereby, the TisCtCsSi entity is trans bent, which is typical
for heterobimetallic compounds of the type {[Ti](CtCSiMe3)2}-
CuR in which both alkynyl ligands are η2-bonded to a CuR
moiety.1-4 Through this deformation different copper-to-carbon
bond lengths are observed [Cu(1)-C(11) ) 2.012(9) Å and
Cu(1)-C(12) ) 2.102(8) Å; Table 3]. Similar bonding situa-
tions are found in molecules of type {(η5-C5H4SiMe3)2Ti-
(CtCR)2}MX [M ) Ag, X ) halide, pseudohalide,2,3b,24 X )
organic ligand;2,4a,c MX ) Ni(CO), Ni(PR3), Ni[P(OR)3];2,25 MX
) Co(CO);2,26 MX ) FeCl2, CoCl2, NiCl22,3a,4,27].
Figure 2. ORTEP drawing (drawn at 50% probability level) of the
molecular geometry of compound 7b (with exclusion of the hydrogen
atoms) with the atom numbering scheme (Tables 1 and 3).
compounds 6 and 7 a X-ray diffraction study was exemplarly
carried out on single crystals of 7b (Figure 2, Table 3).
The molecular structure of compound 7b comprises a
trigonally planar coordinated copper atom, which is η1-bonded
by the bromo ligand, datively bonded by the chloro atom Cl(1)
and η2-bonded by the CtC triple bond of the CtCSiMe3 ligand.
The atoms Ti(1), Cu(1), Br(1), Cl(1), C(11), and C(12) form a
plane (maximum atomic deviation: 0.059 Å). Compound 7b
represents the first example in copper(I) chemistry for which
the monomeric structure of the CuBr moiety is caused by the
(22) For example: (a) Lang, H.; Ko¨hler, K.; Herres, M.; Emmerich, Chr.
Z. Naturforsch. 1995, 50B, 923 and literature cited therein. (b) Royo,
P. New J. Chem. 1990, 14, 553. (c) Wolff von Gudenberg, D.; Kang,
H. C.; Massa, W.; Dehnicke, K.; Maichle-Mo¨ssmer, C.; Stra¨hle, J. Z.
Anorg. Allg. Chem. 1994, 620, 1719. (d) Cano, A.; Cuenca, T.; Gomez-
Sal, P.; Royo, B.; Royo, P. Organometallics 1994, 13, 1688. (e)
Bursten, B. E.; Callstrom, M. R.; Jolly, C. A.; Paquette, L. A.; Sivik,
M. R.; Tucker, R. S.; Wartchow, C. A. Organometallics 1994, 13,
127.
(23) (a) Aleksandrov, G. G.; Golding, I. R.; Sterlin, S. R.; Sladkov, A. M.;
Struchkov, Y. T.; Garbuzova, I. A.; Aleksanyan, V. T. IzV. Akad. Nauk
SSR, Ser. Khim. 1980, 2679. (b) Macomber, D. W.; Rausch, M. D. J.
Am. Chem. Soc. 1983, 105, 5325. (c) Maier, G.; Hoppe, M.;
Reisenauer, P. Angew. Chem. Suppl. 1982, 1061. (d) International
Tables for X-ray Crystallography, The Kynoch Press: Birmingham,
U.K., 1986; Vol. III, p 260. (e) Gill, J. T.; Mayerle, J. J.; Welcker, P.
S.; Lewis, D. F.; Ucko, D. A.; Barton, D. J.; Stowens, D.; Lippard, S.
J. Inorg. Chem. 1976, 15, 1155.
(20) Atwood, J. L.; Hunter, W. E.; Hrncir, D. C.; Samuel, E.; Alt, H.;
Rausch, M. D. Inorg. Chem. 1975, 14, 1757.
(21) Scholz, J.; Rehbaum, F.; Thiele, K. H.; Goddard, R.; Belz, P.; Kru¨ger,
K. H. J. Organomet. Chem. 1993, 443, 93.

6272 Inorganic Chemistry, Vol. 35, No. 21, 1996
Lang et al.
Moreover, it is found that upon η2-coordination the CtC
triple bond is lengthened as compared to non-coordinated
alkynyl-substituted titanocene derivatives.1,2,24b The bite angle
Cl(1)-Ti(1)-C(11) at 92.4(2)° in compound 7b accords with
that found in {[Me2Si(η5-C5H2SiMe3)2]Ti(Cl)(CtCSiMe3)}-
CuCl [94.9(2)°].1 As compared to mono(σ-alkynyl)- or bis(σ-
alkynyl)-substituted titanocenes these bite angles significantly
are reduced in size [(η5-C5H4SiMe3)2Ti(CtCSiMe3)2, 102.8°;
[Me2Si(η5-C5H2SiMe3)2]Ti(Cl)(CtCSiMe3), 99.8(4)°], a phe-
nomenon typical for tweezer-like molecules.2
The mono(σ-alkynyl)titanocene chlorides (2) as well as the
bis(alkynyl)titanocenes (5) have a pronounced preference for
binding to only one copper halide entity, and it is interesting to
compare characteristic features of the new complexes with
known examples of alkyne-coordinated copper compounds.2 The
monoanionic bromine in 7b is η1-bonded to the copper(I) center,
dative bonded by the chloro atom and η2-coordinated by the
CtC triple bond of the [Ti](Cl)(CtCSiMe3) entity. This way
of stabilizing a monomeric copper(I) bromide is the first example
in copper(I) chemistry.
Reaction of [Ti](Cl)(CtCR) (2) and [Ti](CtCPh)-
(CtCSiMe3) (5a) with Silver(I) Compounds. While the
mono(σ-alkynyl)titanocene chlorides [Ti](Cl)(CtCR) (2) readily
react with polymeric copper(I) halides [CuX]n to produce the
heterobimetallic titanium-copper molecules {[Ti](Cl)(CtCR)}-
CuX (6a, R ) Ph, X ) Cl, Br, I; 7, R ) SiMe3, X ) Cl, Br),
no reaction is observed on treatment of compounds 2 with silver-
(I) halides [AgX]n (X ) Cl, Br). However, the polymeric
structure of [AgX]n can be broken down to monomeric AgX
moieties by making use of the chelating effect of the organo-
metallic π-tweezer [Ti](CtCPh)(CtCSiMe3) (5a).
The copper-bromine bond length at 2.296(2) Å is shorter
than according distances in for example dimeric [η2-Me3-
SiCtCSiMe3)CuBr]2 [2.407(1) Å]2,23 or polymeric [CuBr]n
[2.46 Å].23 In fact for the η1-chloro and η2-alkyne interaction
in combination with the geometric constraints of the mono(σ-
alkynyl)titanocene chloride fragment in compound 7b a relative
short Ti-Cu distance [2.958(3) Å] is observed.2,28
Besides the X-ray structure analysis hints on the composition
of compounds 6-9 are given by NMR and IR spectroscopic
measurements. Due to the η2-coordination of the CtCR units
(R ) Ph, SiMe3) to the copper atom in compounds 6-9, the
CtC stretching vibration is shifted from 2077 cm-1 in 2a, 2022
cm-1 in 2b, or 2067 cm-1 (CtCPh) and 2014 cm-1 (CtCSiMe3)
in 5a to 1926-1935 cm-1 in 6, 1900 cm-1 in 7, or 1956 cm-1
(CtCPh) and 1915 cm-1 (CtCSiMe3) in compounds 8 and 9,
respectively. This shifting indicates a weaker CtC bond in
the mono- or bis(σ-alkyne)copper(I) halide complexes 6-9, a
phenomenon typical for π-bonding of organic and organome-
tallic alkyne-copper(I) moieties.2a
When compound 5a is reacted with equimolar amounts of
[AgX]n in tetrahydrofuran at 25 °C the complexes {[Ti]-
(CtCPh)(CtCSiMe3)}AgX (10a, X ) Cl; 10b, X ) Br) are
obtained in 81% or 88% yield, respectively.
(4)
In the 13C{1H} NMR spectra it is found that upon η2-
coordination of the CtC triple bonds to the copper atom in
complexes 6-9 the resonance signals of the CR atoms in the
TiCtCR entity are slightly shifted upfield, whereas resonance
signals of the Câ atoms are shifted downfield. This is in
agreement with an observation generally made by changing from
noncoordinated to η2-coordinated alkynyl substituted ti-
tanocenes.
Complexes 10a and 10b are isostructural with the appropriate
copper(I) species {[Ti](CtCPh)(CtCSiMe3)}CuX. As in these
compounds, the silver atom possesses a trigonal-planar environ-
ment and the bis(η2-alkyne)AgX unit represents a 16-valence-
electron entity.2,4a,c,24 Compounds 10a and 10b show solubility
similar to that of the isostructural copper(I) compounds. As
expected, the silver(I) species are somewhat lightsensitive.
The asymmetric environment around the titanium atom in
compounds 6-8 results in the appearance of ABXY resonance
patterns for the cyclopentadienyl protons in the region 6.0-6.8
1
ppm. For the SiMe3 and Ph groupings the H NMR spectra
show the expected simplicity with the resonance signals of the
SiMe3 groups at around 0.3 and 0.1 ppm, as well as for the
phenyl protons in the 7.1-7.8 ppm region.
Discussion
The 1H and 13C NMR spectra of solutions of compounds 6-9
in toluene-d8 remain essentially unchanged in the temperature
region of 193-353 K. Moreover, cryoscopic molecular weight
determinations in benzene showed that these complexes exist
as monomeric species in solution. These data are consistent
with a monomeric structure established for those molecules in
the solid state (see above).
The organometallic mono(σ-alkynyl)titanocene chlorides [Ti]-
(Cl)(CtCR) (2) as well as the bis(alkynyl)titanocenes [Ti]-
(CtCR)(CtCR′) (5) can be used to dissolve monomeric units
of polymeric copper(I) halides [CuX]n.
The copper atom in compounds {[Ti](Cl)(CtCR)}CuX (6,
7) and {[Ti](CtCR)(CtCR′)}CuX (8, 9) is σ-bonded by the
inorganic ligands X. Moreover, in compounds 6 and 7 the
copper atom is complexed by the chloro group as well as the
CtC triple bond of the CtCR substituent, whereas in com-
plexes 8 and 9 the CuX unit is embedded between two
η2-coordinating alkynyl ligands. Therefore, these complexes
are predestinated for a detailed study of monomeric copper(I)
halides. The same is expected for the isostructural molecules
{[Ti](CtCPh)(CtCSiMe3)} AgX (10).
Acknowledgment. This work was supported by the Deutsche
Forschungsgemeinschaft, Fonds der Chemischen Industrie,
Volkswagen-Stiftung, and Deutscher Akademischer Aus-
tauschdienst (I.Y.W.). We thank Dr. Chr. Limberg and Mrs.
S. Ahrens for many discussions.
Supporting Information Available: Tables of crystal data and
details of the structure determinations, final coordinates and equivalent
isotropic thermal parameters of the non-hydrogen atoms, hydrogen atom
positions and isotropic thermal parameters, anisotropic thermal param-
eters, bond distances and bond angles for compounds 4 and 7b (13
pages). Ordering information is given on any current masthead page.
(24) (a) Lang, H.; Ko¨hler, K.; Schiemenz, B. J. Organomet. Chem. 1995,
495, 135. (b) Lang, H.; Herres, M.; Zsolnai, L. Organometallics 1993,
12, 5008.
(25) (a) Lang, H.; Blau, S.; Nuber, B.; Zsolnai, L. Organometallics 1995,
14, 3216. (b) Lang, H.; Imhof, W. Chem. Ber. 1992, 125, 1307.
(26) (a) Lang, H.; Herres, M.; Imhof, W. J. Organomet. Chem. 1994, 465,
283. (b) Lang, H.; Herres, M.; Zsolnai, L. Bull. Chem. Soc. Jpn. 1993,
66, 429. (c) Lang, H.; Zsolnai, L. J. Organomet. Chem. 1991, 406,
C5.
IC960115X
(28) Ko¨hler, K.; Zsolnai, L.; Driess, A.; Silverio, S.; Hyla-Kryspin, I.;
(27) Herres, M.; Lang, H. J. Organomet. Chem. 1994, 480, 235.
Gleiter, R.; Lang, H. Organometallics, manuscript in preparation.