Synthesis and characterization of (mono)pentamethylcyclopentadienyl lutetium complexes: Formation of bipyridyl-stabilized alkyls, anilides, and terminal acetylides

Article abstract of DOI:10.1021/om0497700

The alkyl complex [Lu(CH₂SiMe₃)₃(THF) ₂] reacts with pentamethylcyclopentadiene (Cp*H), giving [Cp*Lu(CH₂SiMe₃)₂(THF)] (1). Complex 1 reacts with 1,2-dimethoxyethane (DME), affording [Cp*Lu(CH ₂SiMe₃)₂(DME)] (2). Complex 1 also reacts with 2,2′-bipyridine (bipy) to give [Cp*Lu(CH₂SiMe ₃)₂(bipy)] (3). The dialkyl complex 3 reacts with 1.0 equiv of 2,6-diisopropylaniline to give the mixed alkyl-anilide [Cp*Lu(NHAr)(CH₂SiMe₃)(bipy)] (4) (Ar = 2,6-Pr ₂ⁱC₆H₃) and the bis(anilide) [Cp*Lu(NHAr)₂(bipy)] (5) in a 1.0:0.09 ratio. Complex 5 can be independently synthesized in high yield by treatment of 3 with 2.0 equiv of 2,6-diisopropylaniline or 4 with 1.0 equiv of 2,6-diisopropylaniline. Complex 3 also reacts with 2.0 equiv of phenylacetylene to afford dimeric [{Cp*Lu(CCPh)(bipy)}₂(μ-η²:η²- PhC₄Ph)]·2(C₆H₆) (6). Complex 6 reacts with THF and pyridine (py), giving terminal (bis)acetylide complexes [Cp*Lu(CCPh)₂(bipy)(THF)] (7) and [Cp*Lu(CCPh) ₂(bipy)(py)] (8), respectively. The solid-state structures of 1, 2, 4, 5, 6, and 8 are reported.

Full text of DOI:10.1021/om0497700

Organometallics 2004, 23, 2995-3002
2995
Syn th esis a n d Ch a r a cter iza tion of
(Mon o)p en ta m eth ylcyclop en ta d ien yl Lu tetiu m
Com p lexes: F or m a tion of Bip yr id yl-Sta bilized Alk yls,
An ilid es, a n d Ter m in a l Acetylid es
Thomas M. Cameron,* J ohn C. Gordon,† and Brian L. Scott
Chemistry Division, MS J 514, Los Alamos National Laboratory,
Los Alamos, New Mexico 87544
Received March 31, 2004
The alkyl complex [Lu(CH2SiMe3)3(THF)2] reacts with pentamethylcyclopentadiene (Cp*H),
giving [Cp*Lu(CH2SiMe3)2(THF)] (1). Complex 1 reacts with 1,2-dimethoxyethane (DME),
affording [Cp*Lu(CH2SiMe3)2(DME)] (2). Complex 1 also reacts with 2,2′-bipyridine (bipy)
to give [Cp*Lu(CH2SiMe3)2(bipy)] (3). The dialkyl complex 3 reacts with 1.0 equiv of 2,6-
diisopropylaniline to give the mixed alkyl-anilide [Cp*Lu(NHAr)(CH2SiMe3)(bipy)] (4)
(Ar ) 2,6-Pri C6H3) and the bis(anilide) [Cp*Lu(NHAr)2(bipy)] (5) in a 1.0:0.09 ratio. Complex
2
5 can be independently synthesized in high yield by treatment of 3 with 2.0 equiv of 2,6-
diisopropylaniline or 4 with 1.0 equiv of 2,6-diisopropylaniline. Complex 3 also reacts with
2.0 equiv of phenylacetylene to afford dimeric [{Cp*Lu(CCPh)(bipy)}2(µ-η2:η2-PhC4Ph)]‚
2(C6H6) (6). Complex 6 reacts with THF and pyridine (py), giving terminal (bis)acetylide
complexes [Cp*Lu(CCPh)2(bipy)(THF)] (7) and [Cp*Lu(CCPh)2(bipy)(py)] (8), respectively.
The solid-state structures of 1, 2, 4, 5, 6, and 8 are reported.
In tr od u ction
characterized by nonparamagnetic NMR spectroscopy).5
Reports of neutral, mono-Cp Ln complexes bearing
dialkyl groups are limited to [Cp*Gd(CH2Ph)2(THF)]
(Cp* ) pentamethylcyclopentadienyl),6 [(η5-C5Me4Si-
Me2X)Y(CH2SiMe3)2(THF)] (X ) Me, Ph, C6F5),7 [(η5-
C5Me4SiMe2CH2CHCH2) Y(CH2SiMe3)2],8 [Cp*La{CH-
(SiMe3)2}2],9 [Cp*Lu(CH2SiMe3){CH(SiMe3)2}(THF)],10,11
[Cp*Lu(CH2CMe3)2(THF)],11 [Lu{η5:η1-C5Me4SiMe2(C4-
H3O-2)}(CH2SiMe3)2(THF)],12 and [Cp′Lu(CH2SiMe3)2-
(THF)] (Cp′ ) C5Me4SiMe3),13 of which only [Cp*Gd-
(CH2Ph)2(THF)], [Cp*La{CH(SiMe3)2}2], and [Lu{η5:η1-
C5Me4SiMe2(C4H3O-2)}(CH2SiMe3)2(THF)] have been
characterized by X-ray crystallography. Furthermore,
the isolation of [Cp*Lu(CH2SiMe3){CH(SiMe3)2}(THF)]
and [Cp*Lu(CH2CMe3)2(THF)] is complicated by the
formation of “ate” complexes due to the salt elimination
strategy employed, a common problem with this type
of approach to alkyl complexes in Ln chemistry.4 We
herein report the synthesis and characterization of Cp*
lutetium dialkyl complexes generated via a simple
The cyclopentadienyl (Cp) family of ancillary ligands
are common in trivalent organometallic lanthanide (Ln)
chemistry, and examples of bis-Cp Ln derivatives have
been well documented.1 These complexes are important
and have found use, for example, in catalytic hydroami-
nation2 and polymerization.3 When compared with bis-
Cp complexes, the properties of mono-ring compounds
that are desirable include an increased potential for
functionalization at the metal center, a result of having
only one monoanionic ancillary ligand present. Reports
of mono-ring compounds are less prevalent due partially
to the matching of steric requirements between Ln
metal center and Cp ligand needed to inhibit formation
of bis-Cp species.4 We are specifically interested in the
straightforward preparation of lutetium (Lu) mono-ring
dialkyl complexes in order to study the potential chem-
istry of these relatively unexplored species (Lu was
chosen due to the ease with which products can be
* To whom correspondence should be addressed. E-mail: tcameron@
lanl.gov. Fax: 505-667-9905. Tel: 505-667-3588.
(5) Constrained geometry ligands (such as linked amido-cyclopen-
tadienyl ligands) have been used to generate several mono-ring
complexes, but the dianionic nature of these ligands precludes them
from use in the synthesis of neutral Ln dialkyls.
(6) Mandel, A.; Magull, J . Z. Anorg. Allg. Chem. 1996, 622, 1913.
(7) Hultzsch, K. C.; Spaniol, T. P.; Okuda, J . Angew. Chem., Int.
Ed. 1999, 38, 227.
† Currently on temporary assignment: U.S. Department of Energy,
Office of Basic Energy Sciences, Catalysis and Chemical Transforma-
tions Program, SC-14, 1000 Independence Ave., SW, Washington, DC,
20585-1290. E-mail: J ohn.Gordon@science.doe.gov. Fax: 301 903 0271.
Tel: 301 903 2153.
(1) (a) Schaverien, C. J . Adv. Organomet. Chem. 1994, 36, 283. (b)
Schumann, H.; Meese-Marktsscheffel, J . A.; Esser, L. Chem. Rev. 1995,
95, 865. (c) Kilimann, U.; Edelmann, F. T. Coord. Chem. Rev. 1995,
141, 1. (d) Richter, J .; Edelmann, F. T. Coord. Chem. Rev. 1996, 147,
373. (e) Gun’ko, Y. K.; Edelmann, F. T. Coord. Chem. Rev. 1996, 156,
1. (f) Edelmann, F. T.; Gun′ko, Y. K. Coord. Chem. Rev. 1997, 165,
163. (g) Edelmann, F. T.; Lorenz, V. Coord. Chem. Rev. 2000, 209, 99.
(2) Hong, S.; Marks, T. J . J . Am. Chem. Soc. 2002, 124, 7886, and
references therein.
(8) Evans, W. J .; Brady, J . C.; Ziller, J . W. J . Am. Chem. Soc. 2001,
123, 7711.
(9) Klooster, W. T.; Brammer, L.; Schaverien, C. J .; Budzelaar, P.
H. M. J . Am. Chem. Soc. 1999, 121, 1381.
(10) Schaverien, C. J .; van der Heijden, H.; Orpen, A. G. Polyhedron
1989, 8, 1850.
(11) van der Heijden, H.; Pasman, P.; de Boer, E. J . M.; Schaverien,
C. J .; Orpen, A. G. Organometallics 1989, 8, 1459.
(12) Arndt, S.; Spaniol, T. P.; Okuda, J . Organometallics 2003, 22,
775.
(3) Hou, Z.; Wakatsuki, Y. Coord. Chem. Rev. 2002, 231, 1, and
references therein.
(4) Arndt, S.; Okuda, J . Chem. Rev. 2002, 102, 1953.
(13) Tardif, O.; Nishiura, M.; Hou, Z. Organometallics 2003, 22,
1171.
10.1021/om0497700 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 05/07/2004

2996 Organometallics, Vol. 23, No. 12, 2004
Cameron et al.
Ta ble 1. Su m m a r y of Cr ysta llogr a p h ic Da ta a n d Str u ctu r e Refin em en t Deta ils for 1, 2, a n d 4
1
2
4
empirical formula
fw
C
22H45OSi2Lu
C22H47LuO2Si2
574.75
C
36H52N3LuSi‚0.5 THF
556.73
765.92
space group
a (Å)
b (Å)
P21/c
I41/a
17.961(6)
P21/n
18.531(4)
10.112(2)
15.750(3)
112.973(4)
2717.2(9)
1.361
10.837(5)
20.678(9)
16.960(7)
91.214(8)
3800(3)
c (Å)
34.786(15)
â (deg)
Vc (Å3)
11222(7)
1.361
Dc (Mg m-3
)
1.339
Z
4
16
3.617
R1 ) 0.0727
wR2 ) 0.1651 [5032]
0.0550
4
µ(Mo KR) (mm-1
final R indicesa
)
3.729
2.659
R1 ) 0.0329
wR2 ) 0.0733 [5839]
0.0325
R1 ) 0.0790
wR2 ) 0.2346 [22 893]
0.0692
a
R1 ) σ||Fo| - |Fc||/σ|Fo| and wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]1/2. The parameter w ) 1/[σ2(Fo2) + (aP)2].
a
2
Sch em e 1
that others have recently used the protonolysis approach
to mono-ring Ln dialkyl complexes.7,12,13
Resonances for the coordinated THF are observed at
1.11 ppm (4H, â-protons) and 3.46 ppm (4H, R-protons),
and the Cp*Me groups resonate at 2.04 ppm (1H NMR;
C6D6; 25 °C). The alkyl group resonances appear as
singlets at -0.87 ppm (4H, CH2SiMe3) and 0.31 ppm
1
(18H, CH2SiMe3) in the H NMR spectrum of 1. Similar
chemical shifts have been reported for lanthanide
complexes bearing related alkyl groups.7,8,10-13 The
apparent equivalency of the CR-H protons in the 1H
NMR spectrum of 1 at room temperature is interesting,
as the complex, as drawn in Scheme 1, should display
diastereotopic protons. Rapid dissociation of THF from
1 generating a pseudo-three-coordinate THF-free system
could explain these results.15 The variable-temperature
1H NMR spectrum of 1, however, does not change from
25 to -80 °C (C7D8). If there is an exchange process
involving THF, it must still be rapid at -80 °C. A THF
ligand protonolysis7,13 (alkane elimination) procedure.
The use of 2,2′-bipyridine (bipy) as an ancillary ligand
in this system is explored. In contrast to conventional
wisdom, the Ln metal retains its characteristic reactiv-
ity in the presence of this Lewis base (bipy). Further-
more, the chelating bipy has facilitated the isolation and
complete characterization of the first, neutral, bis-
(terminal) acetylide Ln species.
1
exchange process has been observed by H NMR spec-
troscopy for Cp-based lutetium and yttrium complexes.14
Another explanation assumes slow dissociation of THF
on the NMR time scale. In this case the singlet could
be explained by an A2 spin system, the result of the
difference in chemical shift of the CR-H protons in
question being equal to zero over the range of temper-
atures investigated.
A single-crystal X-ray study of 1 was carried out on a
crystal grown from a concentrated hexanes solution, and
the crystal details are presented in Table 1. The thermal
ellipsoid plot of 1 is shown in Figure 1 and confirms the
structure of 1 as shown in Scheme 1. Complex 1 adopts
a distorted tetrahedral geometry. The Lu(1)-C(11) and
Lu(1)-C(15) bond lengths of 2.342(4) and 2.322(4) Å,
respectively, are within the expected range for Lu-C
bonds in complexes containing a Lu-CH2SiMe3 func-
tionality.11,12,16 The Lu(1)-Cp*cent (cent ) centroid)
distance of 2.317 Å is also similar to Cp-metal distances
in related lutetium compounds.14a
Resu lts a n d Discu ssion
Syn t h esis a n d Ch a r a ct er iza t ion of Lu Dia lk yl
Com p lexes [Cp *Lu (CH2SiMe3)2(THF )] (1), [Cp *Lu -
(CH2SiMe3)2(DME)] (2), a n d [Cp *Lu (CH2SiMe3)2-
(bip y)] (3). Treatment of a toluene solution of Lu(CH2-
14a
SiMe3)3(THF)2 with an equimolar amount Cp*H over
a 48 h period resulted in the formation of [Cp*Lu(CH2-
SiMe3)2(THF)] (1), as determined by NMR spectroscopy
(Scheme 1). Complex 1 was isolated as an off-white solid
by removal of the toluene solvent under reduced pres-
sure followed by crystallization of the resulting oil/wax
from hexanes in 51% yield. This low isolated yield is
due to the high solubility of 1 in hexanes. This crystal-
lization step is unnecessary, and crude 1 can be used
in subsequent chemistry, thus increasing the isolated
yield. Repeated trituration of the crude oil/wax of 1 with
hexanes results in the solidification of 1, facilitating its
manipulation. We highlight the ease with which this
compound can be generated in contrast to the salt
elimination, anionic complex forming route used to
make similar complexes in the past10,11 and point out
When complex 1 was dissolved in DME, the quantita-
1
tive formation of 2 was observed by H NMR spectros-
(15) Exchange via a rapid associative pathway forming [Cp*Lu(CH2-
SiMe3)2(THF)2] due to adventitious THF could also explain the 1H NMR
spectrum of 1.
(16) (a) Schumann, H.; Freckmann, D. M. M.; Dechert, S. Z. Anorg.
Allg. Chem. 2002, 628, 2422. (b) Arndt, S.; Spaniol, T. P.; Okuda, J .
Chem. Commun. 2002, 896. (c) Schumann, H.; Genthe, W.; Bruncks,
N.; Pickardt, J . Organometallics 1982, 1, 1194. (d) Hogerheide, M. P.;
Grove, D. M.; Boersma, J .; J astrzebski, J . T. B. H.; Kooijman, H.; Spek,
A. L.; van Koten, G. Chem. Eur. J . 1995, 1, 343.
(14) (a) Arndt, S.; Voth, P.; Spaniol, T. P.; Okuda, J . Organometallics
2000, 19, 4690. (b) Hultzsch, K. C.; Voth, P.; Beckerle, K.; Spaniol, T.
P.; Okuda, J . Organometallics 2000, 19, 228.

Pentamethylcyclopentadienyl Lutetium Complexes
Organometallics, Vol. 23, No. 12, 2004 2997
Sch em e 2a
F igu r e 1. Thermal ellipsoid plot of 1 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): Lu(1)-O(1) 2.255(3), Lu(1)-C(11) 2.342(4), Lu(1)-
C(15) 2.322(4), Lu(1)-Cp*cent 2.317, O(1)-Lu(1)-C(11)
99.4(1), C(11)-Lu(1)-C(15) 102.7(1), O(1)-Lu(1)-Cp*cent
117.2.
a
Ar ) 2,6-diisopropyl.
protons appear in the 1H NMR spectrum of 2 as doublets
at -1.11 and -0.96 ppm with a 12.0 Hz geminal
coupling constant. The singlet resonance at 0.36 ppm
has been assigned to the SiMe3 group, and the Cp*Me
1
groups resonate at 2.03 ppm in the H NMR spectrum
of 2.
The reaction of 1 with another potential chelate, bipy,
was explored. Addition of 1.0 equiv of bipy to a toluene
solution of 1 resulted in an immediate color change from
pale yellow to dark red-orange. Concentration of the
solution in vacuo followed by crystallization at -35 °C
gave red-orange crystals that were isolated by filtration
1
and dried under reduced pressure. The H NMR spec-
troscopic data support the structure of 3 as shown in
Scheme 1. The asymmetric nature of the compound
results in diastereotopic CR-H protons that display
doublet resonances at -0.70 and -0.44 ppm (2J H-H
)
11.5 Hz). The silylmethyl resonance at 0.28 ppm and
the Cp* resonance at 1.88 ppm in the 1H NMR also
support the proposed structure for 3.
F igu r e 2. Thermal ellipsoid plot of 2 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): Lu(1)-Cp*cent 2.362, Lu(1)-C(19) 2.40(1), Lu(1)-
C(15) 2.391(9), Lu(1)-O(1) 2.460(6), Lu(1)-O(2) 2.396(7),
Cp*cent-Lu(1)-C(19) 111.5, Cp*cent-Lu(1)-O(2) 110.6,
Cp*cent-Lu(1)-O(1) 108.2, Cp*cent-Lu(1)-C(15) 111.5, O(2)-
Lu(1)-C(19) 87.3(3), O(2)-Lu(1)-O(1) 65.4(2), O(1)-Lu-
(1)-C(15) 83.9(3), C(15)-Lu(1)-C(19) 94.5(4).
Complex 3 is an easily synthesized starting material
that allows for the straightforward reactivity study of
a Lu dialkyl complex containing only one ancillary Cp*
ligand. We have focused our initial study on the reaction
of 3 with compounds containing acidic N-H or C-H
bonds. The results between reaction of 3 and 2,6-
diisopropylaniline and phenylacetylene are shown in
Scheme 2. Reaction of 3 with 1.0 equiv of NH2Ar (Ar )
copy after appropriate workup. An X-ray crystallo-
graphic study was carried out on a single crystal of 2
grown from a DME/hexanes solution at -35 °C. The
crystal data and details of the structure refinement are
summarized in Table 1. The thermal ellipsoid plot of 2
with selected bond lengths and angles is shown in
Figure 2. The geometry around the metal center is best
described as distorted square pyramidal with O(1), O(2),
C(15), and C(19) defining the base of the pyramid. The
Lu(1)-C(19) and Lu(1)-C(15) bond lengths of 2.40(1)
and 2.391(9) Å, respectively, are similar to the analogous
Lu-C lengths in 1. The Lu(1)-Cp*cent distance of 2.362
Å is, as in 1, similar to Cp-metal distances in related
lutetium compounds.14a
1
2,6-diisopropyl) gave 4 as a major product (92% by H
NMR spectroscopy) along with minor amounts (8% by
1H NMR spectroscopy) of 5. Complex 5 was indepen-
dently prepared by treatment of 3 with 2.0 equiv of NH2-
Ar or treatment of 4 with 1.0 equiv of NH2Ar. When 3
was treated with 2.0 equiv of phenylacetylene, the
dimeric complex 6 was formed in good yield. The solid-
state structures of 4, 5, and 6 were confirmed by single-
crystal X-ray structure determination.
Complex 4 crystallized from THF in a monoclinic unit
cell with two molecules of THF per unit cell. The
thermal ellipsoid plot of 4 is shown in Figure 3 with
selected bond lengths and angles, and the crystal data
and details of the structure refinement are summarized
in Table 1. The coordination environment about Lu(1)
The solution structure of 2 is consistent with the solid-
state structure of 2. The diastereotopic alkyl CR-H

2998 Organometallics, Vol. 23, No. 12, 2004
Cameron et al.
Ta ble 2. Su m m a r y of Cr ysta llogr a p h ic Da ta a n d Str u ctu r e Refin em en t Deta ils for 5, 6, a n d 8
5
6
8
empirical formula
fw
C
44H56N4Lu
C72H66Lu2N4‚2(C6H6)
1493.44
C41H33N3Lu‚C4H8O
814.78
815.90
space group
a (Å)
b (Å)
P21/c
P1h
P1h
22.058(5)
10.368(2)
18.363(4)
10.802(5)
12.607(5)
13.302(5)
86.74(2)
9.485(2)
11.204(2)
22.304(5)
96.360(4)
101.884(4)
98.837(5)
2266.9(9)
1.194
c (Å)
R (deg)
â (deg)
γ (deg)
Vc (Å3)
109.127(4)
77.70(2)
77.47(2)
1727.6(1)
1.435
3967.6(1)
1.366
Dc (Mg m-3
)
Z
4
1
2
µ(Mo KR) (mm-1
final R indicesa
)
2.522
2.888
2.209
R1 ) 0.0773
wR2 ) 0.1567 [29 002]
0.0796
R1 ) 0.0428
wR2 ) 0.1116 [8016]
0.0640
R1 ) 0.0439
wR2 ) 0.1059 [5077]
0.0700
a
R1 ) σ||Fo| - |Fc||/σ|Fo| and wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]1/2. The parameter w ) 1/[σ2(Fo2) + (aP)2].
a
2
F igu r e 3. Thermal ellipsoid plot of 4 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): Lu(1)-Cp*cent 2.340, N(1)-Lu(1) 2.47(1), N(2)-Lu-
(1) 2.48(1), N(3)-Lu(1) 2.22(1), C(21)-Lu(1) 2.40(1), N(1)-
Lu(1)-N(3) 82.8(4), N(3)-Lu(1)-C(21) 100.2(4), C(21)-
Lu(1)-N(2) 83.3(4), N(2)-Lu(1)-N(1) 65.1(3).
F igu r e 4. Thermal ellipsoid plot of 5 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): Lu(1)-Cp*cent 2.344, N(1)-Lu(1) 2.500(7), N(2)-Lu-
(1) 2.472(7), N(3)-Lu(1) 2.208(7), N(4)-Lu(1) 2.209(7),
N(1)-Lu(1)-N(2) 64.7(3), N(2)-Lu(1)-N(4) 82.6(2), N(4)-
Lu(1)-N(3) 101.8(3), N(3)-Lu(1)-N(1) 80.6(3).
is best described as a pseudo-five-coordinate distorted
square pyramid. The Lu(1)-N(3) distance of 2.22(1) Å
is within the expected range for a lutetium anilide
interaction.17 The remainder of the metal to ligand bond
lengths also fall within the expected ranges.
Although separation of 4 from 5 proved difficult, 4
represents a rare example of the preferred formation
of a mixed alkyl anilide containing an anilide NR-H
proton, a possible precursor to a terminal imido complex.
We propose that the high ratio of 4 to 5 is because the
steric bulk at the metal center slows the second pro-
tonation reaction that affords 5. A similar Nacnac-based
scandium complex has recently been reported in the
literature.18
The 1H NMR spectrum of 4 is consistent with the
structure shown in Figure 3. Two doublets (2J H-H ) 10.5
Hz) are observed in the 1H NMR spectrum of 4 at -0.73
and -0.43 ppm for the CR-H protons, while the NR-H
proton resonance for 4 appears at 4.89 ppm. The
resonances for the SiMe3 and Cp* groups fall within the
expected ranges at 0.50 and 1.89 ppm, respectively, in
1
the H NMR spectrum of 4. While the conversion of 3
When 3 or 4 is treated with appropriate amounts of
ArNH2 in benzene at 50 °C, 5 crystallizes from solution.
Red crystals of 5 were isolated in 71% yield by filtration
of the reaction mixture. One of these crystals was
selected for a single-crystal X-ray diffraction study. The
thermal ellipsoid plot of 5 is shown in Figure 4 with
selected bond lengths and angles, and the crystal data
are summarized in Table 2. The geometry around the
metal in 5 is distorted square pyramidal and similar to
that in 4. Other structural parameters in 5 such as the
to 4 was high yielding, samples of 4 were constantly
contaminated with small amounts of 5. Attempts to
purify 4 by recrystallization were not fully successful
due to the poor solubility of 5. The best results obtained
reduced the amount of 5 in the mixture to approxi-
1
mately 1% (by H NMR spectroscopy) after one recrys-
tallization. While subsequent recrystallizations could
reduce the amount of 5 present, this would come with
substantial loss of product.
(17) (a) Cameron, T. M.; Gordon, J . C.; Michalczyk, R.; Scott, B. L.
Chem. Commun. 2003, 2282. (b) Arndt, S.; Voth, P.; Spaniol, T. P.;
Okuda, J . Organometallics 2000, 19, 4690.
(18) Basuli, F.; Tomaszewski, J .; Huffman, J . C.; Mindiola, D. J .
Organometallics 2003, 22, 4705.

Pentamethylcyclopentadienyl Lutetium Complexes
Organometallics, Vol. 23, No. 12, 2004 2999
Sch em e 3
Lu(1)-C(2) and Lu(1)-C(2A) bond lengths of 2.569(6)
and 2.743(6) Å are considerably longer than expected
for Lu-C single bonds, implying weakening Lu-C
interactions upon progression from the end to the center
of the butatrienediyl fragment. Similar trends have been
noted for the aforementioned Ln complexes.19-21 The
acetylide fragment Lu(1)-C(29) bond length of 2.376-
(7) Å is within the range of a lutetium carbon single
bond. The acetylide C(29)-C(30) bond length of 1.212-
(9) Å is comparable to the usual carbon-carbon bond
distance of 1.20 Å for alkynes, meaning there is a
considerable amount of triple bond character between
C(29) and C(30).22 Having both terminal acetylide and
bridging butatrienediyl fragments in the same molecule
allows for a direct comparison of the carbon-carbon
bond lengths. It is clear that there is little remaining
triple bond character within the butatrienediyl frag-
ment, as the C(1)-C(2) (1.301(9) Å) and C(2)-C(2A)
(1.33(1) Å) bond lengths are considerably longer than
the acetylide C(29)-C(30) (1.212(9) Å) bond distance.
Complex 6 is unique among neutral, trivalent, lan-
thanide carbyls. Solid-state structures of complexes
containing bridging butatrienediyl fragments have been
reported,19-21 as have those that contain terminal
acetylide ligands.23 To our knowledge, 6 is the first
example of a neutral, trivalent, structurally character-
ized, Ln complex containing both butatrienediyl and
terminal acetylide ligands.24,25
F igu r e 5. Thermal ellipsoid plot of 6 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): C(1)-C(2) 1.301(9), C(2)-C(2A) 1.33(1), Lu(1)-C(1)
2.388(6), Lu(1)-C(2) 2.569(6), Lu(1)-C(2A) 2.743(6), Lu-
(1)-N(1) 2.431(5), Lu(1)-N(2) 2.464(6), Lu(1)-Cp*cent 2.343,
Lu(1)-C(29) 2.376(7), C(29)-C(30) 1.212(9), C(1)-C(2)-
C(2A) 150.1(8).
Lu(1)-N(1) through N(4) bond lengths and the Lu(1)-
Cp*cent bond length are comparable to similar interac-
tions in 4.
The formulation of 5 as a bis(anilide) is also borne
out by 1H NMR spectroscopy. The two inequivalent 2,6-
Pri C6H3 methyl groups resonate at 0.83 and 1.02 ppm,
2
while the equivalent 2,6-Pri C6H3 methine protons
2
appear as a septet at 2.99 ppm. The Cp* and anilide
NR-H proton resonances show up at 1.77 and 4.09 ppm,
respectively, and all aromatic proton resonances in the
1H NMR spectrum of 5 have been assigned.
When benzene solutions of 3 were treated with
phenylacetylene, single crystals of 6 formed and were
isolated in 40% yield. An X-ray study was carried out
on a single crystal of 6. The summary of crystallographic
data and structure refinement details for 6 are included
in Table 2, and the thermal ellipsoid plot of 6 is shown
in Figure 5. Complex 6 crystallizes with two benzene
molecules of solvate in a triclinic unit cell, and the
molecule sits on an inversion center. The Lu metal
centers are bridged through a butatrienediyl fragment.
The bond lengths C(1)-C(2) and C(2)-C(2A), within the
butatrienediyl fragment, of 1.301(9) and 1.33(1) Å,
respectively, are comparable to corresponding bond
lengths in the related Sm,19 Ce,20 and La21 bis((penta-
methyl)cyclopentadienyl) systems.22 The closest metal-
to-butatrienediyl carbon contact is between Lu(1) and
C(1) (2.388(6) Å). This is within the range expected for
a Lu-C single bond and compares well with the Lu-C
single bond lengths of 2.40(1) and 2.391(9) Å in 2. The
Crystals of 6 either are insoluble (C6D6, C6D5Cl, C7D8,
CH3CN) or react with (CD2Cl2, CD3NO2, OC(CD3)2) most
conventional NMR solvents. While crystals of complex
1
6 do dissolve in d8-THF, the H NMR spectrum of the
resulting solution is not consistent with the structure
1
of 6 as shown in Figure 5. The H and 13C NMR data
are consistent with the formation of a terminal bis-
(acetylide) THF complex (7), as shown in Scheme 3.
(23) (a) Evans, W. J .; Keyer, R. A.; Ziller, J . W. Organometallics
1993, 12, 2618. (b) Evans, W. J .; Ulibarri, T. A.; Chamberlain, L. R.;
Ziller, J . W.; Alvarez, D., J r. Organometallics 1990, 9, 2124. (c)
Duchateau, R.; Brussee, E. A. C.; Meetsma, A.; Teuben, J . H. Orga-
nometallics 1997, 16, 5506. (d) Lin, G.; McDonald, R.; Takats, J .
Organometallics 2000, 19, 1814.
(19) Evans, W. J .; Keyer, R. A.; Ziller, J . W. Organometallics 1990,
9, 2628.
(20) Heeres, H. J .; Nijhoff, J .; Teuben, J . H.; Rogers, R. D. Organo-
metallics 1993, 12, 2609.
(24) An example of a related La complex with terminal and bridging
acetylides has recently been reported: Tazelaar, C. G. J .; Bambirra,
S.; van Leusen, D.; Meetsma, A.; Hessen, B.; Teuben, J . H. Organo-
metallics 2004, 23, 936.
(21) Forsyth, C. M.; Nolan, S. P.; Stern, C. L.; Marks, T. J .;
Rheingold, A. L. Organometallics 1993, 12, 3618.
(22) For comparison the usual carbon-carbon distance in an alkene
is 1.34 Å: Handbook of Chemistry and Physics, 67th ed.; CRC Press:
Boca Raton, FL, 1986; Table F-158.
(25) A somewhat related complex, [CpLu(DME)]2[1,1-µ-4,4-µ-(Ph)C-
(Ph)CdC(Ph)C(Ph)], containing a tetracharged bridging ligand formed
by the coupling of diphenylacetylene has been reported: Bochkarev,
M. N.; Protchenko, A. V.; Zakharov, L. N.; Fukin, G. K.; Struchkov, Y.
T. J . Organomet. Chem. 1995, 501, 123.

3000 Organometallics, Vol. 23, No. 12, 2004
Cameron et al.
crystallized from the resulting solution over the course
of approximately 3 h. Solid samples of 6 isolated from
the above two processes could be converted back to 7
by addition of THF. Attempts to study this potential
equilibrium in more detail were hindered by the insolu-
bility of 6; however a similar process has been reported
in the literature.20
The facile synthesis of (mono)pentamethylcyclopen-
tadienyl lutetium dialkyl complexes as described herein
allows for easy access to a variety of reactive molecules
with only one anionic ancillary ligand (Cp*). We have
structurally characterized many interesting derivatives
including dialkyl complexes 1 and 2, mixed alkyl-anilide
4, and bis(anilide) 5. We have also structurally charac-
terized the first monomeric bis(acetylide) complex (8).
F igu r e 6. Thermal ellipsoid plot of 8 (50% probability
thermal ellipsoids). Selected bond lengths (Å) and angles
(deg): Lu(1)-N(1) 2.453(6), Lu(1)-N(2) 2.455(5), Lu(1)-
N(3) 2.580(8), Lu(1)-C(26) 2.397(7), Lu(1)-C(34) 2.383(7),
C(26)-C(27) 1.19 (1), C(34)-C(35) 1.21(1), Lu(1)-Cp*cent
2.374, N(1)-Lu(1)-N(2) 66.4(2), N(2)-Lu(1)-C(26) 85.3-
(2), C(26)-Lu(1)-C(34) 106.8(2), C(34)-Lu(1)-N(1) 89.2-
(2), N(3)-Lu(1)-Cp*cent 175.6.
Exp er im en ta l Section
Gen er a l Meth od s. All reactions were conducted under a
dry argon atmosphere using standard Schlenk techniques or
in an argon-filled drybox. All solvents were distilled under
argon from sodium or sodium benzophenone ketyl or passed
over activated alumina, stored over molecular sieves, and
degassed prior to use. The Lu(CH2SiMe3)3(THF)2 used was
prepared according to a literature procedure.14a All NMR
spectra were obtained on a Bruker AV300 instrument with
C6D6, C7D8, CD2Cl2, or d8-THF as solvent and referenced to
residual solvent peaks. Elemental analyses were performed
by the Micro-Mass Facility, University of California, Berkeley.
In many cases the results obtained were not satisfactory and
were inconsistent from run to run. Difficulties in character-
izing organolanthanide compounds by elemental analysis have
also been encountered by other researchers.14a,27
Growing single crystals of 7 proved to be difficult;
however single crystals of the corresponding pyridine
adduct (8) were grown from a THF/pyridine solution,
allowing for a single-crystal X-ray study. The thermal
ellipsoid plot of 8 is shown in Figure 6 with selected
bond lengths and angles. The crystal parameters and
structure refinement details appear in Table 2. Complex
8 crystallizes in a monoclinic unit cell with the ligands
adopting a distorted octahedral geometry around Lu-
(1). The Lu(1)-C(26) and Lu(1)-C(34) acetylide bond
lengths of 2.397(7) and 2.383(7) Å, respectively, are
comparable to the Lu-acetylide bond length (Lu(1)-
C(29)) of 2.376(7) Å in 6. The multiple bond interaction
between C(26)-C(27) and C(34)-C(35) in 8 is best
described as a triple bond interaction with C(26)-C(27)
and C(34)-C(35) distances of 1.19(1) and 1.21(1) Å,
respectively. A similar interaction between C(29) and
C(30) in complex 6 was discussed above. While some
monomeric lanthanide complexes containing one ter-
minal acetylide ligand have been synthesized,23,24 to our
knowledge, 8 represents the first structurally character-
ized neutral, monomeric, lanthanide, bis(acetylide) spe-
cies.
Complexes 7 and 8 were fully characterized by NMR
spectroscopy (HMQC and HMBC, the full assignments
are included in the Experimental Section).26 The proton
and carbon chemical shifts of analogous fragments of 7
and 8 are very similar. Of interest are the acetylide
resonances in the 13C NMR spectra. The acetylide CR
and Câ resonances appear at 159.8 and 108.6 ppm for 7
and 159.9 and 108.6 ppm for 8, respectively. The
similarity in chemical shifts between 7 and 8 is consis-
tent with analogous solution structures for the two
molecules.
Cr ysta llogr a p h y. The crystal structures of all compounds
were determined as follows, with exceptions noted below: A
crystal was mounted onto a glass fiber using a spot of silicone
grease. Due to air sensitivity, the crystal was mounted from a
pool of mineral oil under argon gas flow. The crystal was placed
on a Bruker P4/CCD diffractometer and cooled to 203 K using
a Bruker LT-2 temperature device. The instrument was
equipped with a sealed, graphite-monochromatized Mo KR
X-ray source (λ ) 0.71073 Å). A hemisphere of data was
collected using æ scans, with 30 s frame exposures and 0.3°
frame widths. Data collection and initial indexing and cell
refinement were handled using SMART software.28 Frame
integration, including Lorentz-polarization corrections, and
final cell parameter calculations were carried out using SAINT
software.29 The data were corrected for absorption using the
SADABS program.30 Decay of reflection intensity was moni-
tored via analysis of redundant frames. The structure was
solved using direct methods and difference Fourier techniques.
All hydrogen atom positions were idealized and rode on the
atom they were attached to. The final refinement included
anisotropic temperature factors on all non-hydrogen atoms.
Structure solution, refinement, graphics, and creation of
publication materials were performed using SHELXTL NT.31
Additional details of data collection and structure refinement
are listed in Tables 1 and 2. Compound 2: The methylene
hydrogen atom positions were found on the difference map and
refined with their temperature factors fixed at 0.08 Å2.
The potential reversibility involving the conversion
of 6 to 7 was explored and found to depend on THF.
When samples of 7, dissolved in THF, were diluted with
benzene or toluene, crystals of 6 formed over the course
of 12 h, as determined by X-ray crystallography. Simi-
larly when solid samples of 7, isolated from THF
solutions, were taken up in benzene or toluene, 6
(27) Mitchell, J . P.; Hajela, S.; Brookhart, S. K.; Hardcastle, K. I.;
Henling, L. M.; Bercaw, J . E. J . Am. Chem. Soc. 1996, 118, 1045.
(28) SMART-NT 4; Bruker AXS, Inc.: Madison, WI 53719, 1996.
(29) SAINT-NT 5.050; Bruker AXS, Inc.: Madison, WI 53719, 1996.
(30) Sheldrick, G. SADABS, first release; University of Go¨ttingen:
Germany.
(26) (a) Hurd, R. E.; J ohn, B. K. J . Magn. Reson. 1991, 91, 648. (b)
Bax, A.; Summers, M. F. J . Am. Chem. Soc. 1986, 108, 2093.
(31) SHELXTL NT Version 5.10; Bruker AXS, Inc.: Madison, WI
53719, 1997.

Pentamethylcyclopentadienyl Lutetium Complexes
Organometallics, Vol. 23, No. 12, 2004 3001
Compound 4: The electron density of a disordered THF
molecule was removed from the unit cell using PLATON/
SQUEEZE.32 This resulted in four THF molecules per cell
being removed (89 e-/cell and 450 Å3). Compound 6: A benzene
solvent molecule was found on the difference map and refined
with anisotropic temperature factors and idealized hydrogen
atom positions. Compound 8: One of the CCPh ligand phenyl
groups, C36 to C41, was disordered and refined as two one-
half occupancy phenyl groups (C36 to C41 and C36′ to C41′).
Each ring was constrained to be rigid with fixed C-C bond
distances. The anisotropic temperature factors were con-
strained to be equivalent on corresponding disordered atoms.
Hydrogen atom positions were not refined on the disordered
rings. The electron density of a disordered THF molecule was
removed from the unit cell using PLATON/SQUEEZE.32 This
resulted in two THF molecules per cell being removed (147
e-/cell and 742 Å3).
4.89 (1H, NHArPri), 6.26 (1H, d, 6.5 Hz, aromatic), 6.51 (1H,
d, 6.5 Hz, aromatic), 6.7-7.1 (7H, ov, mult, aromatic), 8.71
(1H, d, 5.0 Hz, aromatic), 9.00 (1H, d, 5.5 Hz, aromatic). 13C
NMR (C6D6; 25 °C): δ 6.3, 12.1, 23.9, 25.7, 30.7, 32.5, 114.2,
116.0, 120.7, 120.9, 123.7, 125.1, 125.8, 133.4, 138.8, 139.5,
152.4, 153.2, 153.7, 154.0, 154.5.
Syn t h esis of [Cp *Lu (NH Ar )2(b ip y)] (5) (Ar ) 2,6-
P r i2C6H3). To a benzene solution of 4 (0.042 g, 0.058 mmol)
was added 1.0 equiv of NH2Ar (Ar ) 2,6-Pri C6H3) (0.010 g,
2
0.058 mmol). The solution was heated at 50 °C in a sealed
vessel for 10 h. During the heating period crystals of 5 formed.
These crystals were isolated by filtration in 71% yield. The
procedure for the synthesis of 5 from 3 uses 2.0 equiv of NH2-
Ar but is otherwise identical. 1H NMR (CD2Cl2; 25 °C): δ 0.83
(12H, d, 6.5 Hz, NHArPri Me), 1.02 (12H, d, 7.0 Hz, NHArPri
Me), 1.77 (15H, Cp*Me), 2.99 (4H, sept, 6.5 Hz, NHArPri CH),
4.09 (2H, NHArPri), 6.25 (2H, t, 7.5 Hz, NHArPri aromatic),
6.70 (4H, d, 7.5 Hz, NHArPri aromatic), 7.55 (2H, d of d of d,
7.5 Hz, 5.5 Hz, 1.0 Hz, bipy), 8.09 (2H, “t of d”, 8.0 Hz, 1.5 Hz,
bipy), 8.25 (2H, d, 8.0 Hz, bipy), 8.99 (2H, mult, bipy). 13C NMR
(CD2Cl2; 25 °C): δ 11.5, 24.3, 24.7, 29.5, 113.1, 116.5, 122.0,
122.9, 125.7, 134.1, 140.5, 153.0, 153.4, 154.4. Anal. Calcd for
Syn th esis of [Cp *Lu (CH2SiMe3)2(THF )] (1). To a stirring
solution of Lu(CH2SiMe3)3(THF)2 (1.20 g, 2.07 mmol) in toluene
was added Cp*H (0.32 mL, 0.28 g, 2.07 mmol). The reaction
was left to stir at 25 °C for 48 h and was then concentrated
under reduced pressure, affording crude 1 in 77% yield.
Complex 1 can be crystallized at -35 °C from concentrated
C
44H59LuN4: C, 64.53; H, 7.26; N, 6.84. Found: C, 63.06; H,
1
hexanes solutions. H NMR (C6D6; 25 °C): δ -0.87 (4H, CH2-
6.92; N, 6.50.
SiMe3), 0.31 (18H, CH2SiMe3), 1.11 (4H, br, THF â-protons),
Syn th esis of [{Cp *Lu (CCP h )(bip y)}2(µ-η2:η2-P h C4P h )]‚
2(C6H6) (6). To a benzene solution of 3 (0.100 g, 0.156 mmol)
was added 2.0 equiv of phenylacetylene (0.032 g, 0.312 mmol).
After 12 h with no stirring dark red single crystals of 6 formed
and were isolated by filtration in 40% yield. The X-ray
crystallographic study was carried out on one of these single
crystals. Complex 6 is extremely insoluble in most nonreactive
NMR solvents. These include d6-benzene, d8-toluene, d5-
pyridine, d8-THF, d3-nitromethane, and d3-acetonitrile. Fur-
thermore, 6 reacts with CD2Cl2 over the course of several hours
to give an unidentified product. Due to the insoluble nature
2.04 (15H, Cp*Me), 3.46 (4H, br, THF R-protons). 13C{1H} NMR
1
(C6D6; 25 °C): δ 5.1 (q, J C-H ) 117 Hz, SiMe3), 11.8 (q,
1
1J C-H ) 125 Hz, Cp*Me), 25.2 (t, J C-H ) 134 Hz, THF
1
â-carbon), 39.2 (t, J C-H ) 100 Hz, CH2SiMe3), 71.1 (t,
1J C-H ) 152, THF R-carbon), 117.4 (Cp* ipso). Anal. Calcd for
C
22H45LuOSi2: C, 47.46; H, 8.14. Found: C, 44.94; H, 7.97.
Syn th esis of [Cp *Lu (CH2SiMe3)2(DME)] (2). Complex 1
(0.200 g, 0.348 mmol) was added to 5 mL of DME at room
temperature. Removal of the solvent under reduced pressure
afforded 2 in quantitative yield. Single crystals of 2 were grown
1
from a DME/hexanes solution at -35 °C. H NMR (C6D6; 25
of 6, NMR data cannot be collected. Anal. Calcd for C72H66
-
°C): δ -1.11 (2H, br, d, 12.0 Hz, CH2SiMe3), -0.96 (2H, br, d,
12.0 Hz, CH2SiMe3), 0.36 (18H, CH2SiMe3), 2.03 (15H, Cp*Me),
2.55 (4H, br, DME), 2.98 (6H, br, DME). 13C{1H} NMR (C6D6;
Lu2N4‚C6H6: C, 66.19; H, 5.12; N, 3.95. Found: C, 65.88; H,
5.11; N, 3.86.
1
Syn th esis of [Cp *Lu (CCP h )2(bip y)(THF )] (7). H NMR
1
1
25 °C): δ 5.6 (q, J C-H ) 117.0 Hz, SiMe3), 12.2 (q, J C-H
)
(d8-THF; 25 °C; assigned by HMQC and HMBC): δ 1.78 (15H,
Cp*Me), 7.02 (2H, t of t, 7.0 Hz, 1.5 Hz, acetylide para proton),
7.13 (4H, t, 7.0 Hz, acetylide meta proton), 7.33 (4H, d, 7.0
Hz, acetylide ortho proton), 7.70 (2H, d of d of d, 7.5 Hz, 5.0
Hz, 1.0 Hz, bipy 5 and 5′ protons), 8.12 (2H, t of d, 8.0 Hz, 2.0
Hz, bipy 4 and 4′ protons), 8.41 (2H, d, 8.0 Hz, bipy 3 and 3′
protons), 9.67 (2H, d of d of d, 5 Hz, 1.5 Hz, 1.0 Hz, bipy 6 and
6′ protons) (THF resonances not observed). The 1H NMR
spectrum of 7 remains unchanged from 25 to -100 °C. 13C
NMR (d8-THF; 25 °C; assigned by HMQC and HMBC): δ 12.5
(Cp*CH3), 108.6 (LuCCPh), 116.3 (Cp* ipso), 122.7 (bipy 3 and
3′ carbons), 125.4 (acetylide para carbons), 126.2 (bipy 5 and
5′ carbons), 128.5 (acetylide meta carbons), 130.1 (acetylide
ipso carbons), 132.1 (acetylide ortho carbons), 140.4 (bipy 4
and 4′ carbons), 153.3 (bipy 6 and 6′ carbons), 154.3 (bipy 2
and 2′ carbons), 159.8 (LuCCPh).
Syn th esis of [Cp *Lu (CCP h )2(bip y)(p y)] (8). 1H NMR (d8-
THF; 25 °C; assigned by HMQC and HMBC): δ 1.59 (15H,
Cp*Me), 6.83 (2H, t of d, 7.0 Hz, 2.5 Hz, acetylide para proton),
6.93 (4H, t, 7.0 Hz, acetylide meta protons), 7.02 (2H, d of d,
8.0 Hz, 5.0 Hz, pyridine meta protons), 7.12 (4H, d, 7.0 Hz,
acetylide ortho protons), 7.43 (1H, ov, pyridine para proton),
7.48 (2H, “t”, 6.5 Hz, bipy 5 and 5′ protons), 7.92 (2H, t of d,
8.0 Hz, 1.5 Hz, bipy 4 and 4′ protons), 8.17 (2H, d, 8.0 Hz,
bipy 3 and 3′ protons), 8.36 (2H, br, pyridine ortho protons),
9.46 (2H, d of d, 5.0 Hz, 1.0 Hz, bipy 6 and 6′ protons). 13C
NMR (d8-THF; 25 °C; assigned by HMQC and HMBC): δ 12.6
(Cp*CH3), 108.6 (LuCCPh), 116.3 (Cp* ipso), 122.7 (bipy 3 and
3′ carbons), 124.4 (pyridine meta carbons), 125.5 (acetylide
para carbons), 126.2 (bipy 5 and 5′ carbons), 128.5 (acetylide
1
124.0 Hz, Cp*Me), 34.7 (t, J C-H ) 98.0 Hz, LuCH2), 62.8 (q,
1J C-H ) 147.0 Hz, DME, CH3), 70.5 (t, 1J C-H ) 147.0 Hz, DME,
CH2), 116.3 (Cp* ipso carbon). Anal. Calcd for C22H44LuO2Si2:
C, 45.98; H, 8.24. Found: C, 45.93; H, 8.00.
Syn th esis of [Cp *Lu (CH2SiMe3)2(bip y)] (3). To a stirring
solution of 1 (1.09 g, 1.96 mmol, toluene solution) was added
1.0 equiv of bipy (0.30 g, 1.96 mmol). The reaction was left to
stir for 10 h, at which point the toluene solution was layered
with hexanes and placed at -35 °C for 12 h. Crystals of 3 were
1
isolated from this cold mixture by filtration in 68% yield. H
NMR (C6D6; 25 °C): δ -0.70 (2H, d, 11.5 Hz, CH2SiMe3), -0.44
(2H, d, 11.5 Hz, CH2SiMe3), 0.28 (18H, CH2SiMe3), 1.88 (15H,
Cp*Me), 6.64 (2H, mult, bipy), 6.90 (4H, mult, bipy), 8.88 (2H,
d, 5.0 Hz, bipy). 13C NMR (CDCl3; 25 °C): δ 4.7, 11.6, 34.9,
115.8, 121.9, 125.8, 140.5, 153.1, 153.5. Anal. Calcd for C28H45
-
LuN2Si2: C, 52.48; H, 7.07; N, 4.37. Found: C, 50.88; H, 6.65;
N, 4.21.
Syn t h esis of [Cp *Lu (NH Ar )(CH2SiMe3)(b ip y)] (4)
(Ar ) 2,6-P r i2C6H3). To a stirring toluene solution of 3 (0.100
g, 0.156 mmol) was added 1.0 equiv of NH2Ar (Ar ) 2,6-
Pri C6H3) (0.027 g, 0.156 mmol). After 10 h of stirring the
2
solution was layered with hexanes and placed at -35 °C for
12 h. Solid 4 was isolated from this cold mixture by filtration
1
in 75% yield. H NMR (C6D6; 25 °C): δ -0.73 (1H, d, 10.5 Hz,
CH2SiMe3), -0.43 (1H, d, 10.5 Hz, CH2SiMe3), 0.50 (9H, CH2-
SiMe3), 0.82 (6H, br, NHArPri Me), 1.45 (6H, d, 6.5 Hz,
NHArPri Me), 1.89 (15H, Cp*Me), 3.06 (2H, br, NHArPri CH),
(32) Spek, A. L. Acta. Crystallogr. 1990, A46, C34.

3002 Organometallics, Vol. 23, No. 12, 2004
Cameron et al.
meta carbons), 130.1 (acetylide ipso carbons), 132.0 (acetylide
ortho carbons), 136.4 (pyridine para carbon), 140.4 (bipy 4 and
4′ carbons), 151.0 (pyridine ortho carbons), 153.2 (bipy 6 and
6′ carbons), 154.3 (bipy 2 and 2′ carbons), 159.9 (LuCCPh).
work. T.M.C. thanks the LDRD office for a Directors
Funded Postdoctoral Fellowship.
Su p p or tin g In for m a tion Ava ila ble: CIF files for the
structures of 1, 2, 4, 5, 6, and 8. This material is available
free of charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. We thank the Los Alamos Na-
tional Laboratory LDRD program for support of this
OM0497700