Synthesis of naphthoquinone-fused cyclobutadiene ruthenium complexes

Article abstract of DOI:10.1021/om049732g

A coordinatively unsaturated ruthenacycle, which was formed from Cp*RuCl(cod) and 1,2-bis(phenylpropiolyl)benzene, was isomerized to a new sandwich complex consisting of a Cp* and a naphthoquinone-fused cyclobutadiene ligand at ambient temperature. On the other hand, the treatment of the same ruthenacycle with excess AgBF₄ at room temperature produced a tetramethylfulvene cyclobutadiene complex. In contrast, a cationic cyclobutadiene complex was formed from the isolated Cp*RuCl(cyclobutadiene) with excess AgBF₄.

Full text of DOI:10.1021/om049732g

3610
Organometallics 2004, 23, 3610-3614
Syn th esis of Na p h th oqu in on e-F u sed Cyclobu ta d ien e
Ru th en iu m Com p lexes
Yoshihiko Yamamoto,* Takayasu Arakawa, and Kenji Itoh
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University,
Nagoya 464-8603, J apan
Received April 12, 2004
A coordinatively unsaturated ruthenacycle, which was formed from Cp*RuCl(cod) and 1,2-
bis(phenylpropiolyl)benzene, was isomerized to a new sandwich complex consisting of a Cp*
and a naphthoquinone-fused cyclobutadiene ligand at ambient temperature. On the other
hand, the treatment of the same ruthenacycle with excess AgBF4 at room temperature
produced a tetramethylfulvene cyclobutadiene complex. In contrast, a cationic cyclobutadiene
complex was formed from the isolated Cp*RuCl(cyclobutadiene) with excess AgBF4.
Sch em e 1
Transition-metal-catalyzed cyclotrimerizations of
alkynes have received continuous attention as a facile
method to obtain aromatic molecules,1 since the first
report of Reppe and co-workers.2 Especially, their in-
tramolecular versions are synthetically useful, because
they give polycyclic products chemoselectively.3 In this
context, we have recently developed the ruthenium(II)-
catalyzed cycloaddition of 1,6-diynes with monoalkynes,
affording bicyclic benzenes chemo- and regioselectively
under mild conditions.4 We have also reported that the
Ru(II)-catalyzed cycloaddition of 1,2-bis(propiolyl)ben-
zenes furnished anthraquinone derivatives in moderate
to high yields.5 During these studies, it was found that
a ruthenium(II) precatalyst, Cp*RuCl(cod) 1 (Cp* )
η5-C5Me5), was treated with diyne 2 or 5 bearing a
terminal phenyl substituent to give rise to ruthenacycle
complex 3 or 6, respectively (Schemes 1 and 2).4b,5 The
Ru(II)-catalyzed cycloaddition of the 1,6-diynes is con-
sidered to proceed via a ruthenacycle intermediate very
similar to 3.4b,6 In fact, 3 reacted with acetylene at 40
°C to afford the expected terphenyl product 4 (Scheme
1).4b In contrast, the naphthoquinone-fused analogue 6
behaved in a totally different manner under the same
reaction conditions to result in the formation of a new
complex. Herein, we report the formation of naphtho-
quinone-fused cyclobutadiene complexes from 6.
Sch em e 2
As previously reported,5 the treatment of 1 with 1.2
equiv of 5 in 1,2-dichloromethane (DCE) at room tem-
perature for 0.5 h gave 6 in 79% yield as dark red
crystals after recrystallization (Scheme 2). The X-ray
crystallographic analysis disclosed that 6 has a naph-
thoquinone-fused ruthenacycle framework. The Ru-C1
and Ru-C4 bond lengths are 1.990(2) and 2.009(2) Å,
which are intermediate between those of the known
ruthenacyclopentatriene-type complexes I and II (1.942-
(6) and 1.969(4) Å, respectively) and the ruthenacyclo-
pentadiene phosphine complex III (2.059(5) and 2.092(4)
Å) (Figure 1).7-9 In striking contrast to the known
ruthenacyclopentatrienes, the C1-C2 and C3-C4 bonds
* Corresponding author. E-mail: yamamoto@apchem.nagoya-u.ac.jp.
(1) (a) Shore, N. E. In Comprehensive Organic Synthesis; Trost, B.
M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 5, pp 1129-1162.
(b) Grotjahn, D. B. In Comprehensive Organometallic Chemistry II;
Hegedus, L. S., Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.;
Pergamon: Oxford, 1995; Vol. 12, pp 741-770.
(2) Reppe, W.; Schweckendiek, W. J . J ustus Liebigs Ann. Chem.
1948, 560, 104-116.
(3) Saito, S.; Yamamoto, Y. Chem. Rev. 2000, 100, 2901-2915.
(4) (a) Yamamoto, Y.; Ogawa, R.; Itoh, K. Chem. Commun. 2000,
549-550. (b) Yamamoto, Y.; Arakawa, T.; Itoh, K. J . Am. Chem. Soc.
2003, 125, 12143-12160.
(7) Albers, M. O.; de Waal, D. J . A.; Liles, D. C.; Robinson, D. J .;
Singleton, E.; Wiege, M. B. J . Chem. Soc., Chem. Commun. 1986,
1680-1682.
(5) Yamamoto, Y.; Hata, K.; Arakawa, T.; Itoh, K. Chem. Commun.
2003, 1290-1291.
(8) Ernst, C.; Walter, O.; Dinjus, E. J . Prakt. Chem. 1999, 341, 801-
804.
(6) Kirchner, K.; Calhorda, M. J .; Schmid, R.; Veiros, L. F. J . Am.
Chem. Soc. 2003, 125, 11721-11729.
(9) Yi, C. S.; Torres-Lubian, J . R.; Liu, N. Organometallics 1998,
17, 1257-1259.
10.1021/om049732g CCC: $27.50 © 2004 American Chemical Society
Publication on Web 06/02/2004

Naphthoquinone-Fused Cyclobutadiene Ru Complexes
Organometallics, Vol. 23, No. 15, 2004 3611
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) of 6 a n d 8
6
8
Ru-Cl
2.3279(6)
1.990(2)
2.009(2)
1.395(3)
1.430(3)
1.400(3)
78.43(8)
118.08(15)
113.11(19)
2.365
1.990
1.990
1.402
1.423
1.403
79.960
115.861
113.955
Ru-C1
Ru-C4
C1-C2
F igu r e 1. Precedent ruthenacycle complexes bearing a Cp-
type ligand.
C2-C3
C3-C4
C1-Ru-C4
Ru-C1-C2
C1-C2-C3
Ta ble 2. Selected Bon d Dista n ces (Å) for
Cyclobu ta d ien e Com p lexes 7, 9, a n d 13
7(A)
7(B)
9
13(A)
13(B)
Ru-C1
Ru-C2
Ru-C3
Ru-C4
Ru-X
2.289(8)
2.107(7)
2.128(7)
2.271(7)
2.283(7)
2.125(8)
2.104(6)
2.230(7)
2.492 2.208(7) 2.206(7)
2.143 2.145(8) 2.114(9)
2.095 2.141(7) 2.162(8)
2.340 2.285(7) 2.230(7)
2.3840(19) 2.3839(19) 2.445 2.075(8) 2.040(8)
(Cl or N)
C1-C2
C2-C3
C3-C4
C4-C1
1.485(9)
1.454(9)
1.469(10) 1.474(8)
1.479(10) 1.495 1.542(10) 1.448(10)
1.422(11) 1.456 1.371(11) 1.487(10)
1.484 1.524(10) 1.433(10)
1.472(10) 1.403(11) 1.437 1.495(11) 1.400(10)
F igu r e 2. ORTEP diagram for 7, showing one of two
crystallographically unique molecules in the unit cell.
Ellipsoids are shown at the 50% probability level. All
hydrogen atoms were omitted for clarity.
The ruthenium cyclobutadiene complexes bearing a
Cp or a Cp* ligand have been obtained directly from
appropriate ruthenium complexes and monoalkynes.11
While the intermediacy of metallacyclopentadienes in
the formation of cyclobutadiene complexes from alkynes
has been well documented,12 the isomerization of the
isolated ruthenacyclopentatrienes to the corresponding
cyclobutadiene complexes has not been observed pre-
viously.4b,7,8 In contrast, the relevant naphthoquinone-
fused analogue 6 was slowly converted to 7 at am-
bient temperature. This unprecedented behavior might
be attributed to its metallacycle moiety being close
to a coordinatively unsaturated metallacyclopentadiene
rather than a metallacyclopentatriene (see I and II in
Figure 1).
On the basis of the exclusive conversion of 6 to 7, the
latter was expected to be more stable than the former.
To know the thermodynamic properties of these com-
pounds, we carried out density functional studies of
model complexes 8 and 9. First, their geometries were
optimized at the B3LYP/LACVP* level (Figure 3). The
obtained geometries were in good agreement with those
of 6 and 7, respectively (Tables 1 and 2). Then, their
energies were evaluated by single-point energy calcula-
tions for the obtained geometries at the B3LYP level
using larger basis sets (see Experimental Section).
Contrary to our expectation, it was found that the
cyclobutadiene complex 9 is thermodynamically less
stable than the ruthenacycle 8 by 1.63 kcal/mol. The
detail of the present isomerization is not clear at this
stage, but the simple reductive elimination mechanism
seems unlikely. The direct transformation of a related
(1.395(3) and 1.400(3) Å, respectively) are shorter than
the C2-C3 bond (1.430(3) Å). Although 6 can be
considered to be a coordinatively unsaturated metalla-
cyclopentadiene in terms of these features, the 13C NMR
spectroscopy showed the characteristic carbene reso-
nance of the C1 and C4 carbons at δ 263.89, as
commonly observed for the previously reported ruth-
enacyclopentatrienes.7,8
The treatment of 6 with acetylene (1 atm) in DCE at
ambient temperature gave no cycloadduct, but instead
a small amount of a new product 7 was formed. In the
absence of acetylene, the reaction of 1 with 5 in CDCl3
1
was monitored by H NMR spectroscopy. The initially
formed ruthenacycle complex 6 decreased gradually and
completely converted to 7 after stirring for 3 days. This
behavior is in striking contrast to the rhodium analogue
of 6, which reacted with monoalkynes to give anthra-
quinones in refluxing xylene.10 After recrystallization,
1
7 was isolated in 83% yield as black crystals. In its H
NMR spectrum, the Cp* ligand was observed as a
singlet peak at δ 1.30. The absence of carbene carbons
was confirmed by 13C NMR spectroscopy. Finally, X-ray
crystallography unambiguously disclosed that 7 is a
ruthenium(II) sandwich complex consisting of the Cp*
and naphthoquinone-fused cyclobutadiene ligands as
shown in Figure 2. The unit cell contains the two
crystallographically unique molecules 7(A) and 7(B). As
summarized in Table 2, no remarkable difference was
found in the C-C bond lengths (1.403(11)-1.485(9) Å)
of the cyclobutadiene ligand, and the Ru-C2 and
Ru-C3 distances are slightly shorter than those of
Ru-C1 and Ru-C4. As a result, the [Cp*RuCl] frag-
ment is tilted toward the naphthoquinone ring. The
cyclobutadiene carbons resonated at δ 94.49 and 71.52
in the 13C NMR spectrum.
(11) (a) Crocker, M.; Green, M.; Orpen, A. G.; Thomas, D. M. J .
Chem. Soc., Chem. Commun. 1984, 1141-1144. (b) Campion, B. K.;
Heyn, R. H.; Tilley, T. D. Organometallics 1990, 9, 1106-1112. (c)
Braun, T.; Steinert, P.; Werner, H. J . Organomet. Chem. 1995, 488,
169-176. (d) Gemel, C.; LaPense´e, A.; Mauthner, K.; Mereiter, K.;
Schmid, R.; Kirchner, K. Monatsh. Chem. 1997, 128, 1189-1199. (d)
Ru¨ba, E.; Mereiter, K.; Schmid, R.; Sapunov, V. N.; Kirchner, K.;
Schottenberger, H.; Calhorda, M. J .; Veiros, L. F. Chem. Eur. J . 2002,
8, 3948-3961.
(10) Mu¨ller, E. Synthesis 1974, 761-774.
(12) Efraty, A. Chem. Rev. 1977, 77, 691-744.

3612 Organometallics, Vol. 23, No. 15, 2004
Yamamoto et al.
F igu r e 4. ORTEP diagram for 13, showing one of two
crystallographically unique molecules in the unit cell.
Ellipsoids are shown at the 50% probability level. All
-
hydrogen atoms and BF4 were omitted for clarity.
Sch em e 3
F igu r e 3. DFT-optimized structures of model complexes
8 and 9.
cobaltacyclopentadiene, CpCo(C4H4), into the corre-
sponding cyclobutadiene complex was reported to be a
symmetrically forbidden process due to the HOMO-
LUMO crossing.13 Vollhardt and co-workers, therefore,
proposed the cyclopropenylcarbene complex 10 as an
intermediate for the interconversion between the cy-
clobutadiene complexes and the cobaltacyclopenta-
dienes.14,15 The mechanism involving such an elusive
intermediate could reasonably explain the formation of
cyclobutadiene complexes from monoalkynes. However,
a highly strained bicyclic species such as 11 is not
conceivable for the cases involving diynes.16
its 1H NMR spectrum, the singlet signal of the Cp*
ligand of 6 disappeared, but instead, three singlet
signals were observed at δ 3.65, 1.08, and 1.00 with the
integral ratio of 1:2:2. These observations suggest that
the Cp* ligand was converted to a tetramethylfulvene
ligand. Its methyl and methylene carbons are assigned
to signals at δ 71.8, and 7.87 and 6.79, respectively, by
the 13C DEPT study. In addition, the sp2 carbons of the
cyclobutadiene and the fulvene ligands appeared at δ
105.35, 104.56, 95.90, 86.47, and 73.35 in the 13C NMR
spectrum. Whereas a single crystal suitable for X-ray
study was not obtained, these spectral data allowed us
to assign 12 to a tetramethylfulvene cyclobutadiene
complex. The elemental and the FAB mass analyses also
supported this structural assignment.
The lack of the reactivity of 6 toward the cycloaddition
with acetylene might be attributed to the steric crowd-
ing around the ruthenium center. To open the coordina-
tion site, we attempted chlorine ligand abstraction with
a silver salt (Scheme 3). In the presence of excess
1-hexyne, 6 was treated with 4 equiv of AgBF4 in THF
at room temperature to give rise to a new product. In
In the absence of 1-hexyne, the yield of 12 was
decreased to 19%. The role of the alkyne additive for
this transformation is unclear. The formation of the
fulvene ligand probably occurs prior to the formation
of the cyclobutadiene, because the treatment of 7 with
excess AgBF4 gave rise to a cationic cyclobutadiene
complex instead of 12 (Scheme 3). After recrystallization
from CH3CN-Et2O, 13 bearing a coordinated acetonitrile
was isolated in 37% yield. The remaining Cp* ligand
(13) Hardesty, J . H.; Koerner, J . B.; Albright, T. A.; Lee, G.-Y. J .
Am. Chem. Soc. 1999, 121, 6055-6067.
(14) Ville, G. A.; Vollhardt, K. P. C.; Winter, M. J . Organometallics
1984, 3, 1177-1187.
(15) For interconversion between cyclobutadiene and acetylene via
cyclopropenylcarbene, see: Kollmar, H.; Carrion, F.; Dewar, M. J . S.;
Bingham, R. C. J . Am. Chem. Soc. 1981, 103, 5292-5303.
(16) For cyclobutadiene complexes derived from cyclic diynes, see:
(a) King, R. B.; Efraty, A. J . Am. Chem. Soc. 1970, 92, 6071-6073. (b)
King, R. B.; Efraty, A. J . Am. Chem. Soc. 1972, 94, 3021-3025. (c)
Gleiter, R.; Merger, R.; Nuber, B. J . Am. Chem. Soc. 1992, 114, 8921-
8927. (d) Gleiter, R.; Merger, R.; Irngartinger, H.; Nuber, B. J . Org.
Chem. 1993, 58, 2025-2028. (e) Gleiter, R.; Merger, R.; Treptow, B.;
Witter, W.; Pfla¨sterer, G. Synthesis 1993, 558-560.
1
was observed in its H NMR spectrum as a singlet at δ
1.44. The structure of 13 was unambiguously confirmed
by X-ray crystallography as shown in Figure 4.

Naphthoquinone-Fused Cyclobutadiene Ru Complexes
Organometallics, Vol. 23, No. 15, 2004 3613
Ta ble 3. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
In conclusion, we found that the coordinatively un-
saturated ruthenacycle 6, which was formed from
Cp*RuCl(cod) and the diketodiyne 5, was isomerized to
the naphthoquinone-fused cyclobutadiene complex 7 at
ambient temperature. On the other hand, the treatment
of 6 with excess AgBF4 at room temperature produced
the tetramethylfulvene cyclobutadiene complex 12. In
contrast, the cationic cyclobutadiene complex 13 was
formed from 7 upon treatment with AgBF4 at room
temperature.
for 7‚CHCl3 a n d 13‚CH3CN
7‚CHCl3
13‚CH3CN
empirical formula
fw
cryst syst
space group
unit cell dimens
a (Å)
C
70H60Cl8O4Ru2
C
76H70B2F8N4O4Ru2
1450.92
triclinic
P1
1479.12
triclinic
P1
9.63035(5)
10.0871(5)
17.2611(9)
104.3550(10)
93.7220(10)
106.2240(10)
1539.12(14)
1
9.8491(9)
12.1189(11)
14.7018(14)
99.005(2)
100.104(2)
102.127(2)
1654.6(3)
1
b (Å)
c (Å)
R (deg)
â (deg)
Exp er im en ta l Section
γ (deg)
volume (Å3)
Z
1
Gen er a l Con sid er a tion s. H and 13C NMR spectra were
obtained for samples in CDCl3 solution. Flash chromatography
was performed with a silica gel column (Merck Silica gel 60)
eluted with mixed solvents (hexane/AcOEt). Elemental analy-
ses were performed by the Microanalytical Center of Kyoto
University. Melting points were obtained in sealed capillary
tubes and are uncorrected. 1,2-Dichloroethane was distilled
from CaH2 and degassed. RuCl3‚xH2O was purchased from N.
E. Chemcat Corporation. Cp*RuCl(cod) was obtained according
to the literature procedures.16 1,2-Bis(phenylpropiolyl)benzene
5 was reported in the literature.17
density(calcd)
25.046
22.266
(Mg/m3)
absorp coeff (mm-1
F(000)
cryst size (mm)
index ranges
)
14.217
11776
0.1 × 0.4 × 0.8
-6 e h e 13,
-13 e k e 13,
-23 e l e 23
8.006
11340
0.1 × 0.5 × 0.6
-13 e h e 13,
-16 e k e 13,
-20 e l e 14
12 987
no. of reflns collected 12 208
no. of indep reflns
[R(int)]
9790 [0.0199]
10 443 [0.0244]
no. of data/restraints/ 9790/3/767
params
10 443/3/879
Syn th esis of Ru th en a cycle 6. To a solution of Cp*RuCl-
(cod) (130.2 mg, 0.343 mmol) in degassed 1,2-dichloroethane
(1 mL) was added a solution of a diketodiyne 5 (140.2 mg, 0.419
mmol) in degassed 1,2-dichloroethane (3 mL) at 0 °C. The
solution was further stirred at room temperature for 30 min.
The solution was concentrated in vacuo, and the residue was
recrystallized from CHCl3/ether to afford 6‚CHCl3 (196.3 mg,
78.9%) as dark red crystals: mp 178.5-178.9 °C; IR (CHCl3)
goodness-of-fit on F2
final R indices
1.094
1.070
R1 ) 0.0302,
wR2 ) 0.0818
R1 ) 0.0323,
wR2 ) 0.0879
R1 ) 0.0367,
wR2 ) 0.0979
R1 ) 0.0392,
wR2 ) 0.1005
[I > 2σ(I)]a
R indices (all data)a
largest diff peak and
0.809 and -0.996 1.361 and -0.637
hole (e‚Å-3
)
1
1656 cm-1; H NMR (300 MHz, CDCl3) δ 1.03 (s, 15 H), 7.01
a
2 1/2
R1 ) ∑|(Fo - Fc)|/∑(Fo). wR ) ∑[(w(Fo - Fc)2)]/∑(wFo
) .
(d, J ) 7.2 Hz, 4 H), 7.20 (t, J ) 7.2 Hz, 4 H), 7.46 (tt, J ) 7.5,
1.5 Hz, 2 H), 7.64 (dd, J ) 6.0, 3.3 Hz, 2 H), 8.05 (dd, J ) 6.0,
3.3 Hz, 2 H); 13C NMR (75 MHz, CDCl3) δ 10.20, 108.45,
125.63, 127.04, 127.07, 127.62, 133.19, 133.71, 148.59, 155.67,
178.28, 263.89; MS (FAB) m/z (%): 606 (39) [M+], 571 (100)
[M+ - Cl]. Anal. Calcd (%) for C35H30Cl4O2Ru (725.49): C,
57.94; H, 4.17. Found: C, 58.07; H, 4.15.
(dd, J ) 5.7, 3.3 Hz, 2 H); 13C NMR (75 MHz, CDCl3) δ 6.79
(CH3), 7.87 (CH3), 71.82 (CH2), 73.35, 86.47, 95.90, 104.56,
105.35, 125.30, 126.66, 127.21, 128.10, 131.59, 134.20, 134.87,
180.60; MS (FAB) m/z (%) 570 (100) [MH+]. Anal. Calcd (%)
for C34H28Cl4O2Ru (569.65): C, 71.69; H, 4.95. Found: C, 71.66;
H, 4.98.
Syn th esis of Cyclobu ta d ien e Com p lex 7. To a solution
of Cp*RuCl(cod) (376.9 mg, 0.993 mmol) in degassed CDCl3
(1 mL) was added a solution of diketodiyne 5 (410.0 mg, 1.23
mmol) in degassed CDCl3 (4 mL) at 0 °C. The solution was
further stirred at room temperature for 3 days. The solution
was concentrated in vacuo, and the residue was recrystallized
from CHCl3/ether to afford 7‚CHCl3 (601.8 mg, 83.5%) as black
crystals: mp 221.3-222.2 °C; IR (CHCl3) 1654 cm-1; 1H NMR
(300 MHz, CDCl3) δ 1.30 (s, 15 H), 7.30-7.40 (m, 6 H), 7.61
(dd, J ) 6.0, 3.6 Hz, 2 H), 7.81 (dd, J ) 8.1, 1.8 Hz, 4 H), 8.04
(dd, J ) 6.0, 3.6 Hz, 2 H); 13C NMR (75 MHz, CDCl3) δ 8.91,
71.52, 94.49, 101.77, 126.15, 127.85, 128.83, 129.96, 130.45,
132.81, 134.87, 183.81; MS (FAB) m/z (%) 606 (84) [M+], 571
(100) [M+ - Cl]. Anal. Calcd (%) for C35H30Cl4O2Ru (725.49):
C, 57.94; H, 4.17. Found: C, 57.93; H, 4.18.
Syn th esis of Tetr a m eth ylfu lven e Com p lex 12. To a
solution of AgBF4 (67.5 mg, 0.347 mmol) and 1-hexyne (79.9
mg, 0.973 mmol) in degassed THF (5 mL) was added a solution
of 6‚CHCl3 (66.5 mg, 0.0917 mmol) in degassed THF (35 mL)
at room temperature. The solution was further stirred at room
temperature overnight. The solution was concentrated in
vacuo, and the residue was purified by silica gel flash column
chromatography (hexane/AcOEt, 7:1) to give 12 (17.8 mg,
34.1%) as red solids: mp 190.8-191.3 °C; IR (CHCl3) 1638
cm-1; 1H NMR (300 MHz, CDCl3) δ 1.00 (s, 6 H), 1.08 (s, 6 H),
3.65 (s, 2 H), 7.17-7.22 (m, 2 H), 7.33 (t, J ) 7.2 Hz, 4 H),
7.48 (dd, J ) 5.7, 3.3 Hz, 2 H), 7.70 (d, J ) 7.2 Hz, 4 H), 7.96
Syn th esis of Ca tion ic Cyclobu ta d ien e Com p lex 13. To
a solution of AgBF4 (180.7 mg, 0.928 mmol) in degassed THF
(5 mL) was added a solution of 7‚CHCl3 (142.2 mg, 0.196 mmol)
in degassed THF (35 mL) at room temperature. The solution
was further stirred at room temperature overnight. The
solution was concentrated in vacuo, and the residue was
recrystallized from CH3CN/ether to afford 13‚CH3CN (53.9 mg,
37.2%) as black crystals: mp 201.9-202.5 °C; IR (CHCl3) 2349,
2273, 1663 cm-1; 1H NMR (300 MHz, CDCl3) δ 1.44 (s, 15 H),
2.07 (s, 3 H), 2.16 (s, 3 H), 7.45-7.48 (m, 6 H), 7.70-7.76 (m,
6 H), 8.07 (dd, J ) 5.7, 3.3 Hz, 2 H); 13C NMR (75 MHz, CDCl3)
δ 2.10, 4.25, 8.62, 73.39, 96.52, 104.15, 126.59, 127.76, 128.89,
129.94, 130.34, 132.17, 133.59, 134.08, 181.92; MS (FAB) m/z
(%) 612 (19) [M+], 571 (100) [M+ - CH3CN]. Anal. Calcd (%)
for C38H35BF4N2O2Ru (739.57): C, 61.71; H, 4.77; N, 3.79.
Found: C, 61.96; H, 4.89; N, 3.42.
Cr yst a llogr a p h ic St r u ct u r a l Det er m in a t ion of 7‚
CHCl3 a n d 13‚CH 3CN. Single crystals of 7‚CHCl3 and
13‚CH3CN suitable for X-ray analysis were obtained by
recrystallization from CHCl3/ether and CH3CN/ether, respec-
tively. Single crystals were mounted on a quartz fiber, and
diffraction data were collected in the θ range of 1.23-29.15°
for 7‚CHCl3 and 1.44-29.19° for 13‚CH3CN at 173 K on a
Brucker SMART APEX CCD diffractometer with graphite-
monochromated Mo KR radiation (λ ) 0.71073 Å). An absorp-
tion correction was made using SADABS. The structure was
solved by direct methods and refined by full-matrix least
squares on F2 by using SHELXTL. All non-hydrogen atoms
were refined with anisotropic displacement parameters. All
(17) Oshima, N.; Suzuki, H.; Moro-oka, Y. Chem. Lett. 1984, 1161-
1164.

3614 Organometallics, Vol. 23, No. 15, 2004
Yamamoto et al.
hydrogen atoms were placed in calculated positions. Final
refinement details are compiled in Table 3.
Wadt (LanL2 ECP)23 for Ru and the 6-31G(d) basis sets24 for
other elements. The vibrational frequencies and zero-point
energy (ZPE) were calculated at the same level of theory. The
obtained structures were characterized by the number of
imaginary frequencies (one or zero for transition or ground
states, respectively). Visual inspection of imaginary vibrational
modes was also performed with the Spartan ’02 software
package. The energy calculations were performed at the
B3LYP level using the basis sets consisting of a [6s5p3d2f1g]
contracted valence basis set with the Stuttgart-Dresden-
Bonn energy-consistent pseudopotential25 for Ru and the
6-311++G(d,p) basis sets26 for other elements.
The supplementary crystallographic data for this paper
[CCDC 235937 (7‚CHCl3) and CCDC 235938 (13‚CH3CN)] can
be obtained free of charge via www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44
1223 336033; or deposit@ccdc.cam.ac.uk).
Com p u ta tion a l Meth od s. The Q-chem 2.0 program19 in
the Spartan ’02 software package20 was used for geometry
optimizations, and the single-point energy calculations for the
obtained geometries were performed with the Gaussian 98
program package.21 All geometries of intermediates and
transition states were fully optimized at the B3LYP22/LACVP*
level of theory. The LACVP* basis set uses a double-ú basis
set with the relativistic effective core potential of Hay and
(18) Mu¨ller, E.; Beissner, C.; J a¨kle, H.; Langer, E.; Muhn, H.;
Odenigbo, G.; Sauerbier, M.; Segnitz, A.; Streichfuss, D.; Thomas, R.
Liebigs Ann. Chem. 1971, 754, 64-89.
(19) Kong, J .; White, C. A.; Krylov, A. I.; Sherrill, D.; Adamson, R.
D.; Furlani, T. R.; Lee, M. S.; Lee, A. M.; Gwaltney, S. R.; Adams, T.
R.; Ochsenfeld, C.; Gilbert, A. T. B.; Kedziora, G. S.; Rassolov, V. A.;
Maurice, D. R.; Nair, N.; Shao, Y.; Besley, N. A.; Maslen, P. E.;
Dombroski, J . P.; Daschel, H.; Zhang, W.; Korambath, P. P.; Baker,
J .; Byrd, E. F. C.; Voorhis, T. V.; Oumi, M.; Hirata, S.; Hsu, C.-P.;
Ishikawa, N.; Florian, J .; Warshel, A.; J ohnson, B. G.; Gill, P. M. W.;
Head-Gordon, M.; Pople, J . A. J . Comput. Chem. 2000, 21, 1532-1548.
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(21) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Salvador, P.; Dannenberg, J . J .; Malick, D. K.; Rabuck,
A. D.; Raghavachari, K.; Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.;
Baboul, A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.: Piskorz, P.;
Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J .; Keith, T.; Al-
Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill,
P. M. W.; J ohnson, B.; Chen, W.; Wong, M. W.; Andres, J . L.; Gonzalez,
C.; Head-Gordon, M.; Replogle, E. S.; Pople, J . A. Gaussian 98, revision
A.11; Gaussian, Inc.: Pittsburgh, PA, 2001.
Ack n ow led gm en t. We gratefully acknowledge fi-
nancial support (14750677) from the Ministry of Educa-
tion, Culture, Sports, Science and Technology, J apan.
Su p p or tin g In for m a tion Ava ila ble: CIF files for 7‚
CHCl3 and 13‚CH3CN. This material is available free of charge
via the Internet at http://pubs.acs.org.
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