New synthetic routes to cationic rhenium tricarbonyl bipyridine complexes with labile ligands

Article abstract of DOI:10.1021/ic020174c

Triflate abstraction from the complex [Re(OTf)(CO)₃(bipy)] (1) using the salt NaBAr′₄ (Ar′ = 3,5-bis(trifluoromethyl)phenyl) in dichloromethane solution in the presence of L = PPh₃, NCMe, NCPh, imines, ketones, Et₂O, THF, MeOH, and Mel affords cationic complexes [Re(L)(CO)₃(bipy)]⁺ as their BAr′₄-salts. The new complexes have been characterized spectroscopically and, for [Re(η¹-O=C(Me)R)(CO)₃(bipy)]BAr′₄ (R = CH₃, 6a; R = Ph, 6b), and [Re(THF)(CO)₃(bipy)] BAr′₄ (9), also by single-crystal X-ray diffraction. Compared with conventional methodologies, the route reported here allows the coordination of a broader range of weakly coordinating ligands and requires considerably milder conditions. On the other hand, the reactions of lithium acetylides with [Re(THF)(CO)₃(bipy)]BAr′₄ (9) can be used for the high-yield syntheses of rhenium alkynyls [Re(C≡CR)(CO)₃(bipy)] (R = Ph, 12; R = SiMe₃, 13). Complex 9 was found to catalyze the aziridination of benzylideneaniline with ethyl diazoacetate.

Full text of DOI:10.1021/ic020174c

Inorg. Chem. 2002, 41, 4673−4679
New Synthetic Routes to Cationic Rhenium Tricarbonyl Bipyridine
Complexes with Labile Ligands
Eva Hevia, Julio Pe´rez,* and V´ıctor Riera
Departamento de Qu´ımica Orga´nica e Inorga´nica /I.U.Q.O.E.M., Facultad de Qu´ımica,
UniVersidad de OViedo-C.S.I.C., 33071 OViedo, Spain
Daniel Miguel
Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, UniVersidad de Valladolid,
47071 Valladolid, Spain
Scott Kassel† and Arnold Rheingold
Department of Chemistry, UniVersity of Delaware, Newark, Delaware 19716
Received March 4, 2002
Triflate abstraction from the complex [Re(OTf)(CO)3(bipy)] (1) using the salt NaBAr′4 (Ar′ ) 3,5-bis(trifluoromethyl)-
phenyl) in dichloromethane solution in the presence of L ) PPh3, NCMe, NCPh, imines, ketones, Et2O, THF,
-
MeOH, and MeI affords cationic complexes [Re(L)(CO)3(bipy)]+ as their BAr′4 salts. The new complexes have
been characterized spectroscopically and, for [Re(η1-OdC(Me)R)(CO)3(bipy)]BAr′4 (R ) CH , 6a; R ) Ph, 6b),
3
and [Re(THF)(CO)3(bipy)]BAr′4 (9), also by single-crystal X-ray diffraction. Compared with conventional methodologies,
the route reported here allows the coordination of a broader range of weakly coordinating ligands and requires
considerably milder conditions. On the other hand, the reactions of lithium acetylides with [Re(THF)(CO)3(bipy)]-
BAr′4 (9) can be used for the high-yield syntheses of rhenium alkynyls [Re(CtCR)(CO)3(bipy)] (R ) Ph, 12; R )
SiMe3, 13). Complex 9 was found to catalyze the aziridination of benzylideneaniline with ethyl diazoacetate.
Introduction
stance, the reaction of these halocomplexes with lithium
acetylides is not a good method to prepare alkynyl complexes
which have been targeted by Yam because of their interesting
luminiscence behavior.5 Similar difficulties are encountered
with other anionic nucleophiles.6 On the other hand, the
Rhenium tricarbonyl diimine complexes have been the
subject of much attention, mainly because of their photo-
physical and photochemical properties1 and their use in CO2
activation2 and in supramolecular chemistry.3 The starting
materials [ReX(CO)3(N-N)] (X ) Cl, Br) are easily
prepared by the reactions of diimines with [ReX(CO)5]
complexes, in turn obtained by direct [Re2(CO)10] oxidation
with the halogen.4 However, the functionalization of [ReX-
(CO)3(bipy)] compounds may present difficulties. For in-
(2) (a) Collin, J. P.; Sauvage, J. P. Coord. Chem. ReV. 1989, 93, 245-
268. (b) Christensen, P.; Hamnett, A.; Muir, A. V. G.; Timney, J. A.
J. Chem. Soc., Dalton Trans. 1992, 1455-1463. (c) Stor, G. J.; Hartl,
F.; van Outerstep, J. W.; Stufkens, D. J. Organometallics 1995, 14,
1115-1131. (e) Johnson, F. P. A.; George, M. W.; Hartl, F.; Turner,
J. J. Organometallics 1996, 15, 3374-3387. (f) Scheiring, T.; Klein,
A.; Kaim, W. J. Chem. Soc., Perkin Trans. 2 1997, 2569-2571. (g)
Rossenaar, B. R.; Hartl, F.; Stufkens, D. J. Inorg. Chem. 1996, 35,
6194-6203.
(3) (a) Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S. Chem.
ReV. 1996, 96, 759-833. (b) Slone, R. V.; Yoon, D. I.; Calhoun, R.
M.; Hupp, J. T. J. Am. Chem. Soc. 1995, 117, 11813-11814. (c) Slone,
R. V.; Hupp, J. T. Inorg. Chem. 1997, 36, 5422-5424.
(4) Schmidt, S. P.; Trogler, W. C.; Basolo, F. Inorg. Synth. 1990, 28,
160.
* Corresponding author. E-mail: japm@sauron.quimica.uniovi.es.
†
Permanent address: Department of Chemistry, Villanova University,
800 Lancaster Avenue, 320C Mendel Science Center, Villanova, PA 19085.
(1) (a) Lees, A. J. Chem. ReV. 1987, 87, 711-743. (b) Meyer, T. J. Acc.
Chem. Res. 1989, 22, 163-170. (c) Schanze, K. S.; MacQueen, D.
B.; Perkins, T. A.; Caban, L. A. Coord. Chem. ReV. 1993, 122, 63-
89. (d) Stufkens, D. J.; Vlcek, A., Jr. Coord. Chem. ReV. 1998, 177,
127-179. (e) Farrell, I. R.; Vlcek, A., Jr. Coord. Chem. ReV. 2000,
208, 87-101. (f) Striplin, D. R.; Crosby, G. A. Coord. Chem. ReV.
2001, 211, 163-175.
(5) Yam, V. W. W. Chem. Commun. 2001, 789-796.
(6) See: Leasure, R. M.; Sacksteder, L. A.; Nesselrodt, D.; Reitz, G. A.;
Demas, J. N.; DeGraff, B. A. Inorg. Chem. 1991, 30, 3722-3728.
10.1021/ic020174c CCC: $22.00 © 2002 American Chemical Society
Published on Web 08/16/2002
Inorganic Chemistry, Vol. 41, No. 18, 2002 4673

Hevia et al.
Scheme 1
substitution of halide by neutral ligands to give cationic
complexes has been effected via the more labile triflato
complexes. Even in this way, triflate substitution requires
forcing conditions. Thus, the preparation of [Re(PPh3)(CO)3-
(bipy)]OTf from [Re(OTf)(CO)3(bipy)] needed the presence
of 100 equiv of the phosphine.2j Substitution of nitrile ligands,
which are typically employed as labile neutral leaving groups,
is also slow in these rhenium compounds: nitrile substitution
in [Re(NCMe)(CO)3(bdz)]+ (bdz ) bidiazine)7 required 10
equiv of PPh3 and 2 h in refluxing THF. This obviously
imposes a serious limitation with regard to the synthesis of
complexes with ligands more labile than nitriles. It would
be desirable to develop a method for the functionalization
of [ReX(CO)3(N-N)] complexes without harsh conditions
or large excesses of ligands.
monitoring showed that these reactions reached completion
in about 10 min. Spectroscopic data, given in the Experi-
mental Section, indicate that the products are [Re(L)(CO)3-
(bipy)]BAr′4 (L ) PPh3,2c 2; MeCN,13 3a; PhCN, 3b)
complexes, as depicted in Scheme 1.
The addition of the equimolar amount of NaBAr′4 to a
solution of [Re(OTf)(CO)3(bipy)] (1)10 in CH2Cl2 resulted
in cloudiness and a shift to higher wavenumbers of the
solution νCO IR bands. This is consistent with generation of
a cationic dichloromethane adduct. However, all our attempts
to isolate or characterize this species beyond the IR spectrum
failed. Nevertheless, its solution reacted instantaneously with
equimolar amounts of PPh3, MeCN, or PhCN to produce
the complexes 2, 3a, and 3b, respectively.
Bergman8 and Caulton9 used the reaction of neutral triflato
complexes with the salt NaBAr′410 (Ar′ ) 3,5-bis(trifluoro-
methyl)phenyl) in CH2Cl2 to generate cationic complexes
having labile ligands. The reaction takes advantage of the
low solubility of sodium triflate in CH2Cl2 and affords salts
of the cationic complexes with the low-coordinating, inert
BAr′4 counterion.11 Here, we report the application of this
method to the preparation of cationic labile complexes of
the fragment {Re(CO)3(bipy)} and the use of one of these
cationic complexes in the synthesis of alkynyls and in the
catalytic synthesis of aziridines.
Results and Discussion
These results encouraged us to apply the synthetic method
outlined here to the preparation of new cationic complexes
[Re(L)(CO)3(bipy)]BAr′4. Thus, when a mixture of 1, benzo-
phenone imine, and NaBAr′4 was dissolved in CH2Cl2, a
reaction immediately ensued, from which a crystalline
product with data consistent with [Re(HNdCPh2)(CO)3-
(bipy)]BAr′4 (4) composition was isolated (see Scheme 1
and Experimental Section). In the 13C NMR of 4, a broad,
weak signal at 179.33 ppm was attributed to the CdN carbon
of the imine ligand. A downfield shift upon coordination
(the corresponding signal of free benzophenone imine
appears at 178.21 ppm) was previously noted for imine
The addition of a slight excess of either triphenylphos-
phine, acetonitrile, or benzonitrile to a solution of [Re(OTf)-
(CO)3(bipy)] (1)12 in dichloromethane at room temperature
did not cause triflate dissociation. Thus, the spectroscopic
(IR and NMR) observation of the resulting solution over 24
h only showed the signals of the reactants. Even when the
mixtures were refluxed in toluene for 5 h, no reaction was
observed.
The addition of 1 equiv of the salt NaBAr′4 (Ar′ ) 3,5-
bis(trifluoromethyl)phenyl)10 to these solutions at room
temperature made them become inmediately cloudy because
of the formation of sodium triflate, insoluble in CH2Cl2. The
IR of the solutions showed that the bands of 1 were replaced
by new ones at higher wavenumbers (see Experimental
Section), as expected for the formation of cationic complexes.
1
carbons.14 The four bipy signals in the H NMR of 4 are
consistent with either the presence of a mirror plane in a
static molecule (the imine would be contained in the plane
of the {Re(CO)3(bipy)} fragment) or with free rotation
around the ResN(imine) bond.
We have recently found that stoichiometric amounts of
arylamines effect the substitution of triflate in complex 1
under mild conditions.15 This difference with the behavior
of PPh3 or NCR (see previous description) can be attributed
to the higher nucleophilicity of amines. We wished to find
whether imines, less nucleophilic, display a similar reactivity.
Complexes of monodentate imines are relatively rare, a fact
ν
CO patterns corresponding to fac-tricarbonyl complexes were
1
observed. The H NMR spectra, with four multiplets in the
bipy region, reflecting the existence of a mirror plane,
showed that a single product was obtained in each case. IR
(7) Klein, A.; Volger, C.; Kaim, W. Organometallics 1996, 15, 236-
244.
(8) Arndtsen, B. A.; Bergman, R. G. Science 1995, 270, 1970-1973.
(9) Huang, D.; Huffman, J. C.; Bollinger, J. C.; Eisenstein, O.; Caulton,
K. C. J. Am. Chem. Soc. 1997, 119, 7398-7399.
(10) (a) Brookhart, M.; Grant, B.; Volpe, A. F. Organometallics 1992, 11,
3920-3922. (b) Reger, D. L.; Wright, T. D.; Little, C. A.; Lamba, J.
A. L.; Smith, M. D. Inorg. Chem. 2001, 40, 3810-3814.
(11) Coordination, hydrolysis, and fluoride transfer have been noted for
more conventional anions, such as tetrafluoroborate or hexafluoro-
phosphate.
(13) This complex has been previously prepared by reaction of complex
[ReCl(CO)3(bipy)] and AgPF6 in MeCN, refluxed for 8 h. See ref 7.
(14) (a) Knight, D. A.; Dewey, M. A.; Stark, G. A.; Bennett, B. K.; Arif,
A. M.; Gladysz, J. A. Organometallics 1993, 12, 4523-4534. (b)
Gunnoe, T. B.; White, P. S.; Templeton, J. L. J. Am. Chem. Soc. 1996,
118, 6916-6923.
(12) Guerrero, J.; Pino, O. E.; Wolcan, E.; Feliz, M. R.; Ferraudi, G.; Moya,
S. A. Organometallics 2001, 20, 2842-2853.
(15) Hevia, E.; Pe´rez, J.; Riera, V.; Miguel, D. Organometallics, 2002,
21, 1966-1976.
4674 Inorganic Chemistry, Vol. 41, No. 18, 2002

Cationic Rhenium Tricarbonyl Bipyridine Complexes
Chart 1
that has been attributed to the low basicity of imines and
their vulnerability to nucleophilic attack.16 A mixture of 1
and 3 equiv of benzophenone imine showed (1H NMR
monitoring) a complete transformation of 1 into the complex
[Re(HNdCPh2)(CO)3(bipy)]OTf in 15 h.
The reaction of [Re(OTf)(CO)3(bipy)] (1), NaBAr′4, and
the N-methylimine MeNdCHPh in CH2Cl2 led to the
formation of the compound [Re(MeNdCHPh)(CO)3(bipy)]-
BAr′4 (5) which was isolated as a microcrystalline solid.17
1
Its H and 13C NMR spectra showed the presence of two
species in an approximate 2:1 ratio. In addition to the bipy
1
and aryl signals, the H NMR showed doublets at 3.49
(major) and 3.40 (minor) ppm, with similar coupling
constants (of about 1.5 Hz), assignable to the CH3 groups.
The 13C NMR spectrum showed signals corresponding to
the imine carbons at 178.55 (major) and 175.72 (minor) ppm.
This set of data is consistent with the existence of the two Z
and E isomers of 5 (see Chart 1) in solution, and it can be
assumed that the major species corresponds to the E
diasteromer because, having the bulkier substituents in distant
positions, it must be the most stable.
Figure 1. Thermal ellipsoid (30%) plots of 6a (a) and 6b (b).
Table 1. Selected Bond Distances and Angles for Complexes 6a, 6b,
and 9
6a
6b
9
Re(1)-C(1)
1.911(13)
1.914(12)
1.931(13)
2.154(6)
2.143(6)
2.183(6)
1.124(12)
1.147(12)
1.138(13)
1.181(11)
87.9(5)
86.4(5)
89.5(5)
173.3(4)
95.8(4)
98.2(3)
99.8(4)
172.1(4)
74.4(2)
94.0(4)
95.6(4)
172.5(4)
97.4(3)
80.1(2)
78.9(2)
140.6(7)
120.5(12)
1.913(13)
1.933(13)
1.930(13)
2.153(7)
2.174(7)
2.167(6)
1.137(13)
1.139(13)
1.144(13)
1.218(10)
86.5(5)
88.1(5)
89.5(4)
174.1(4)
92.9(4)
97.8(5)
100.0(4)
170.2(4)
74.2(3)
96.3(4)
99.5(6)
174.0(4)
90.7(4)
81.2(2)
82.6(2)
137.6(6)
121.8(9)
1.818(13)
1.919(12)
1.921(11)
2.162(6)
2.166(6)
2.228(5)
1.175(12)
1.161(12)
1.126(10)
To evaluate the scope of the synthetic method, we aimed
to prepare complexes of ketones, which are very labile
ligands for organometallic fragments.18 The reaction of 1,
NaBAr′4, and acetone or acetophenone afforded the adducts
[Re(η1-OdC(Me)R)(CO)3(bipy)]BAr′4 (R ) CH3, 6a; R )
Ph, 6b, see Scheme 1), which were crystallized by slow
diffusion of hexanes into their CH2Cl2 solutions. Both
compounds were characterized by IR and NMR (1H and 13C)
spectroscopy and by X-ray diffraction (Figure 1 and Table
1 for complex 6a, and Figure 2 and Table 2 for complex
6b). The two compounds showed IR spectra with bands at
1621 (6a) and 1661 (6b) cm-1, corresponding to the CdO
stretchings of the ketone ligands. These values differ little
from those of the free ketones (1712 cm-1 for acetone and
1684 cm-1 for acetophenone). The 13C NMR chemical shifts
of the ketone carbons are also slightly shifted with respect
to the free ketones (228.38 (6a) and 214.97 (6b) ppm).19
Re(1)-C(2)
Re(1)-C(3)
Re(1)-N(1)
Re(1)-N(2)
Re(1)-O(4)
C(3)-O(3)
C(1)-O(1)
C(2)-O(2)
O(4)-C(4)
C(1)-Re(1)-C(2)
C(3)-Re(1)-C(2)
C(1)-Re(1)-C(3)
C(2)-Re(1)-N(1)
C(1)-Re(1)-N(1)
C(3)-Re(1)-N(1)
C(2)-Re(1)-N(2)
C(3)-Re(1)-N(2)
N(2)-Re(1)-N(1)
C(1)-Re(1)-N(2)
C(2)-Re(1)-O(4)
C(1)-Re(1)-O(4)
C(3)-Re(1)-O(4)
N(1)-Re(1)-O(4)
N(2)-Re(1)-O(4)
C(4)-O(4)-Re(1)
O(4)-C(4)-C(5)
89.1(4)
88.7(4)
88.0(4)
171.6(3)
95.7(3)
98.3(3)
98.4(3)
172.9(3)
74.6(2)
92.8(3)
91.5(3)
179.4(3)
92.2(3)
83.7(2)
87.0(2)
(16) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometallics 2000,
19, 5454-5463.
(17) We have found that the triflato complex 1 did not react with MeNd
CHPh (3 equiv of imine, refluxing toluene, 6 h). It was previously
noted by Gladysz (see ref 14a) that the coordination of this imine
required vigorous conditions, because of the decreased nucleophilicity
resulting from the methyl substitution at nitrogen. In our case, the
difference between the reaction with or without NaBAr′4 illustrates
the utility of this salt as a triflate abstractor.
These data indicate a σ-coordination (larger differences to
lower values with respect to the free ketones are observed
both for νCO values and for 13C chemical shifts in π-coor-
dinated ketones).20 The 1H NMR of the acetone complex 6a
shows a single signal for the two methyl groups, consistent
(18) (a) Garner, C. M.; Quiro´s-Me´ndez, N.; Kowalczyk, J. J.; Ferna´ndez,
J. M.; Emerson, K.; Larsen, R. D.; Gladysz, J. A. J. Am. Chem. Soc.
1990, 112, 5146-5160. (b) Caldarelli, J. L.; Wagner, L. E.; White, P.
S.; Templeton, J. L. J. Am. Chem. Soc. 1994, 116, 2878-2888. (c)
Huang, Y. H.; Gladysz, J. A. J. Chem. Educ. 1988, 65, 298-303 and
references therein.
(19) The 13C NMR chemical shifts of the ketone carbons are 206.71 and
198.08 ppm for free acetone and free acetophenone, respectively.
Inorganic Chemistry, Vol. 41, No. 18, 2002 4675

Hevia et al.
bulkier substituents), the occurrence of a similar lability for
the acetone complex 6a makes us favor the former hypo-
thesis.
The only Re(I) cationic complexes with ketone ligands
previously characterized by X-ray diffraction are of the kind
[ReCp(η1-OdC(Me)R)(NO)(PPh3)]+.18a These species show
Re-O distances shorter (R ) Me, 2.099(5) Å; R ) Ph,
2.080(5) Å) than in 6a (2.183(6) Å) and 6b (2.167(6) Å).
This can be due, at least in part, to the different geometry;
thus, unlike the cyclopentadienyl compounds, [Re(η1-Od
C(Me)R)(CO)3(bipy)]BAr′4 complexes are octahedral and
have the ketone ligand trans to a CO ligand, with a strong
trans influence.21
Alcohols and ethers, which are usually even poorer ligands
than ketones,22 can also be coordinated to the cationic
fragment {Re(CO)3(bipy)}+ employing the method outlined
previously. Thus, the reactions of 1, NaBAr′4, and methanol,
diethyl ether, or tetrahydrofuran (THF) in CH2Cl2 afforded
the compounds [Re(MeOH)(CO)3(bipy)]BAr′4 (7), [Re-
(Et2O)(CO)3(bipy)]BAr′4 (8), and [Re(THF)(CO)3(bipy)]-
BAr′4 (9), respectively (Scheme 1). These compounds were
characterized spectroscopically (see Experimental Section)
and, in the case of 9, by X-ray diffraction (Figure 2 and
Table 1).
Figure 2. Thermal ellipsoid (30%) plot of 9.
Table 2. Crystal Data and Refinement Details for Complexes 6a, 6b,
and 9
6a
6b
9
formula
C
48H26BF24
-
C
53H28BF24
N2O4Re
-
C
49H28BF24
N2O4Re
-
N2O4Re
fw
1347.72
1409.78
1361.74
cryst syst
space group
a, Å
b, Å
c, Å
orthorhombica
Pna2(1)
16.820(4)
16.663(4)
18.351(5)
90
orthorhombic
Pna2(1)
17.181(6)
15.957(6)
20.129(7)
90
90
90
5518(3)
4
orthorhombic
Pna2(1)
16.849(4)
16.734(4)
18.467(5)
90
R, deg
â, deg
90
90
5143(2)
4
90
90
5207(2)
4
299(2)
1.737
γ, deg
V, Å3
Z
The Re-O distance (2.228(5) Å) in 9 is nearly identical
to that found for the complex [{Re(CO)3(THF)}2(µ-Cl)2],23
which also features an octahedral geometry around each
rhenium, and a CO trans to the THF ligand.
T, K
293(2)
1.741
2624
293(2)
1.697
2572
Dc, g cm-3
F(000)
2656
0.71073
λ(Mo KR), Å
cryst size, mm3
µ, mm-1
scan range, deg
no. reflns
measured
no. independent
reflns
0.71073
0.71073
0.1 × 0.15 × 0.3 0.13 × 0.15 × 0.3 0.08 × 0.11 × 0.11
Equimolar amounts of [Re(OTf)(CO)3(bipy)] and NaBAr′4
were dissolved in CD2Cl2, and after filtration to remove
NaOTf, 6 equiv of Et2O was added. The 1H NMR monitoring
of the resulting solution showed the complete formation of
[Re(Et2O)(CO)3(bipy)]BAr′4 (8) in 1 h. The Et2O ligand of
8 displayed signals at 3.66 (quartet) and 1.05 (triplet) ppm.
The presence of separate signals for free and coordinated
Et2O indicates that a fast exchange is not taking place.24
As found for the ether complex 8, also the complex [Re-
(MeOH)(CO)3(bipy)]BAr′4 (7) crystallizes with one molecule
of methanol, and also in this case, the free coordinated
2.495 2.330 2.466
1.65 e θ e 23.37 1.63 e θ e 23.28 1.64 e θ e 23.29
32465
34647
32702
7439
7941
7496
data/restraints/
7439/1/723
7941/1/767
7496/1/731
params
GOF on F2
R1/wR2
[I > 2σ(I)]
1.019
0.0384/0.0884
1.020
0.0405/0.1007
1.004
0.0366/0.0819
R1/wR2 (all data) 0.0487/0.0951
0.0529/0.1090
0.0508/0.0863
a In the structure of 6a, the close proximity of the values of the unit cell
parameters a and b suggested the possibility of a tetragonal cell. However,
the attempt to merge the reflections in tetragonal symmetry gave Rint > 0.5
(cf. Rint 0.0462 for the orthorhombic cell). Therefore, the solution and
refinement were carried out in the orthorhombic space group Pna2(1) with
successful results (see data in Table 1).
1
methanol gives separated signals in the H NMR spectrum
(see Experimental Section), indicating the absence of a fast
exchange process.
with a rapid dissociation-recoordination process of the
ketone. For complex 6b, only one methyl signal is seen the
1H NMR, and only one methyl group and one phenyl group
appear in 13C NMR. This can be attributed to the lability of
the ketone. Although for the asymmetric ketone it could also
be due to the large preponderance of one of the geometric
isomers (in the solid state the disposition of the Ph and {Re-
(CO)3(bipy)} groups is trans with respect to the double bond,
presumably to minimize steric interaction between these
(21) Anderson, K. H.; Orpen, A. G. Chem. Commun. 2001, 2682-2683
and references therein.
(22) Agbossou, S. K.; Smith, W. W.; Gladysz, J. A. Chem. Ber. 1990,
123, 1293-1299.
(23) Wong, A. C.; Wilkinson, G.; Hussain, B.; Montevalli, M.; Hurthouse,
M. Polyhedron 1988, 7, 1363-1367.
(24) In contrast with the stability of [Re(Et2O)(CO)3(bipy)]BAr′4 (8) in
dichloromethane solution, Gladysz found that the reaction of [ReCp-
(CH3)(NO)(PPh3)] with HBF4‚Et2O in dichloromethane in the presence
of 20-25 equiv of Et2O afforded [ReCp(ClCH2Cl)(NO)(PPh3)]BF4
as a single product: Agbossou, S. K.; Ferna´ndez, J. M.; Gladysz, J.
A. Inorg. Chem. 1990, 29, 476-480. An analogous preference for
CH2Cl2 over Et2O was found by Kubas for the complexes of the
fragment {PtH(PiPr3)2}+: Huhmann-Vincent, J.; Scott, B. L.; Kubas,
G. J. Inorg. Chem. 1999, 38, 115-124. The difference between 8 and
these compounds can be attributed to the presence of bulky phosphine
ligands in the latter, a feature that should disfavor the coordination of
the more sterically demanding molecule of Et2O. The lower steric
profile of the {Re(CO)3(bipy)}+ fragment (the bipy ligand is planar
and lacks bulky substituents), on the other hand, favors the coordination
of the stronger donor Et2O against dichloromethane.
(20) (a) Mayer, J. M.; Bercaw, J. E. J. Am. Chem. Soc. 1982, 104, 2157-
2165. (b) Erker, G.; Dorf, U.; Czisch, P.; Petersen, J. L. Organome-
tallics 1986, 5, 668-676. (c) Klein, D. P.; Dalton, D. M.; Me´ndez,
N. Q.; Arif, A. M.; Gladysz, J. A. J. Organomet. Chem. 1991, 412,
C7-C10. (d) Hill, J. E.; Fanwick, P. E.; Rothwell, I. P. Organome-
tallics 1992, 11, 1771-1773. (e) Barry, J. T.; Chacon, S. T.; Chisholm,
M. H.; Huffman, J. C.; Streib, W. E. J. Am. Chem. Soc. 1995, 117,
1974-1990.
4676 Inorganic Chemistry, Vol. 41, No. 18, 2002

Cationic Rhenium Tricarbonyl Bipyridine Complexes
Scheme 2
Scheme 4
Scheme 3
Scheme 5
Protonation of methoxo ligands has been used to generate
methanol complexes.25 We investigated the protonation of
the complex [Re(OMe)(CO)3(bipy)]26 using the commercially
available acids HOTf or HBF4‚Et2O as an alternative
synthesis of the cationic complex present in 7. However, the
triflato complex [Re(OTf)(CO)3(bipy)] (1) and the ether
adduct [Re(OEt2)(CO)3(bipy)]BF4 (see Experimental Sec-
tion), respectively, were obtained instead (see Scheme 2).
As mentioned previously, the dichloromethane adduct
proposed as an intermediate in the described triflate substitu-
tion eluded our isolation attempts. Given that alkyl iodides
are known to be better ligands than chlorides,27 we thought
that an iodoalkane adduct could be stable enough to permit
isolation. As a matter of fact, the reaction of 1 and NaBAr′4
in neat iodomethane yielded the compound [Re(IMe)(CO)3-
(bipy)]BAr′4 (10), which could be crystallized and character-
ized by spectroscopy and C, H, N analysis (see Experimental
Section). In contrast with the reaction of PPh3 and the in
situ generated [Re(ClCH2Cl)(CO)3(bipy)]BAr′4 species, which
led to phosphine coordination, the reaction of PPh3 with 10
afforded the complex [ReI(CO)3(bipy)], as a result of
phosphine attack on the methyl group (see Scheme 3). This
difference is due to the higher electrophilicity and better
ligating properties of the iodoalkane. The activation of
haloalkanes toward nucleophilic attack by coordination to
cationic metal centers has been previously found.28
The lability of the cationic compounds described here can
be taken advantage of to prepare neutral [ReX(CO)3(bipy)]
complexes. Thus, the reaction of equimolar amounts of
lithium acetylides LiCtCR (R ) Ph, SiMe3) with [Re(THF)-
(CO)3(bipy)]BAr′4 (9) at -78 °C instantaneously afforded
the alkynyls [Re(CtCPh)(CO)3(bipy)] (12) and [Re(Ct
CSiMe3)(CO)3(bipy)] (13), respectively (see Scheme 4),
which could be isolated as pure materials after a simple
workup procedure (see Experimental Section). It should be
noted that the synthesis of these alkynyls by the reaction of
[ReCl(CO)3(bipy)] with lithium acetylides fails to yield the
desired alkynyls.5
We mentioned previously that the labile cationic com-
plexes reported here are strong Lewis acids. This, and the
fact that both the BAr′4 anion and the {Re(CO)3(bipy)}
fragment are usually robust (neither the carbonyl nor the bipy
ligands dissociate facilely), led us to study the catalytic
activity of these compounds in the synthesis of aziridines
from ethyldiazoacetate (EDA) and benzylideneaniline. Thus,
when 1% of 9 (along with 2,6-di-tert-butylpyridine as acid
scavenger) was added to an equimolar mixture of EDA and
the imine in CH2Cl2, full conversion to a mixture of the cis-
(carboxyethyl)-1,3-diphenylaziridine A (see Scheme 5) and
the enamines B and C (aziridine/enamines ratio ) 5:2) was
observed in 12 h at room temperature. The absence of diethyl
maleate/fumarate in the crude mixtures obtained as products
indicates that the metal complex acts as a Lewis acid to
which the imine coordinates rather than as a carbene transfer
reagent.31
When the complex [ReI(CO)3(bipy)] was allowed to react
with methyl triflate, [Re(OTf)(CO)3(bipy)] (1) was obtained
as a single product. This indicates that the iodo ligand is
methylated (this kind of reaction has been used for synthesis
of iodoalkane adducts)29 and that the triflate anion substituted
the resulting CH3I ligand. This contrasts with the isolability
of [Re(IMe)(CO)3(bipy)]BAr′4 (10) and, once again, shows
the importance of using low coordinating counterions in the
synthesis of labile cationic complexes.30
(25) See for instance: Caldarelli, J. L.; Wagner, L.; White, P. S.; Templeton,
J. L. J. Am. Chem. Soc. 1994, 116, 2878-2888.
(26) (a) Gibson, D. H.; Sleaad, B. A.; Yin, X.; Vij, A. Organometallics
1998, 17, 2689-2691. (b) Hevia, E.; Pe´rez, J.; Riera, L.; Riera, V.;
Miguel, D. Organometallics, 2002, 21, 1750-1752.
(27) Kulawiec, R. J.; Crabtree, R. H. Coord. Chem. ReV. 1990, 89, 89-
115.
(28) (a) Czech, P. T.; Gladysz, J. A.; Fenske, R. F. Organometallics 1989,
8, 1806-1810. (b) Winter, C. H.; Veal, W. V.; Garner, C. M.; Arif,
M. A.; Gladysz, J. A. J. Am. Chem. Soc. 1989, 111, 4766-4776. (c)
Igau, A.; Gladysz, J. A. Organometallics 1990, 10, 2327-2334.
(29) Kulawiec, R. J.; Crabtree, R. H. Organometallics 1988, 7, 1891-
1893.
(30) Strauss, S. H. Chem. ReV. 1993, 93, 927-942.
Inorganic Chemistry, Vol. 41, No. 18, 2002 4677

Hevia et al.
7.74 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.57 [m, 4H H-Cp
BAr′4], 2.09 [s, 3H, CH3]. 13C{1H} NMR: 193.32 [2CO], 189.46
[CO], 156.04, 154.18. 141.24, 128.80, 124.20 [bipy], 121.77
[CH3CN], 3.78 [CH3CN]. Anal. Calcd for C46H23BF24N3O3Re: C,
41.89; H, 1.75; N, 3.18. Found: C, 41.67; H, 1.62; N, 3.28.
[Re(PhCN)(CO)3(bipy)]BAr′4 (3b). Yield: 0.040 g, 80%. IR:
1
2044, 1946. H NMR: 9.10 [m, 2H, bipy], 8.20 [m, 4H, bipy],
Figure 3. Hydrogen/carbon labeling atoms scheme of the BAr′4 anion.
7.74 [m, 8H H-Co BAr′4], 7.69 [m, 2H, bipy], 7.55 [m, 4H H-Cp
BAr′4], 7.42 [m, 5H, Ph]. 13C{1H} NMR: 193.30 [2CO], 189.83
[CO], 156.09, 154.28. 141.31 [bipy], 136.10, 133.54, 129.96 [Ph],
128.87 [bipy], 122.53 [PhCN], 123.16 [bipy], 107.97 [Ph]. Anal.
Calcd for C52H25BF24N3O3Re: C, 44.84; H, 1.80; N, 3.01. Found:
C, 44.71; H, 1.90; N, 3.18.
Experimental Section
General Procedures. General procedures have been given
elsewhere.15 [ReBr(CO)3(bipy)] was prepared in quantitative yield
by refluxing the equimolar amount of [ReBr(CO)5]4 and bipy in
toluene for 4 h. [Re(OTf)(CO)3(bipy)] (1) was prepared by the
reaction of equimolar amounts of [ReBr(CO)3(bipy)] with AgOTf
in CH2Cl2 in the dark, followed by filtration through diatomaceous
earth to remove AgBr. 13C NMR signals of the BAr′4 anion are
almost identical in all complexes and are given only for 2 (Figure
3).
Crystal Structure Determination for Compounds 6a, 6b, and
9. A Bruker AXS SMART 1000 diffractometer with CCD area
detector was used. Raw frame data were integrated with the
SAINT32 program. The structure was solved by direct methods with
SHELXTL.33 A semiempirical absorption correction was applied
with the program SADABS.34 All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were set in calculated positions
and refined as riding atoms, with a common thermal parameter.
All calculations and graphics were made with SHELXTL.
Preparation of [Re(L)(CO)3(bipy)]BAr′4 (2-10). General
Description. Dichloromethane (15 mL) was added to a mixture of
[Re(OTf)(CO)3(bipy)] (1) (0.050 g, 0.036 mmol) and NaBAr′4
(0.077 g, 0.036 mmol).35 The ligand L was added,36 and the resulting
solution was stirred 1 h and then filtered with a cannula tipped
with filter paper. Diffusion of hexanes into these solutions37 afforded
crystals of the [Re(L)(CO)3(bipy)]BAr′4 complexes (2-10). All the
new complexes are yellow. IR spectra are given in CH2Cl2, and
NMR spectra in CD2Cl2.
[Re(N(H)CPh2)(CO)3(bipy)]BAr′4 (4). Yield: 0.041 g, 78%.
1
IR: 2034, 1930. H NMR: 9.03 [m, 3H, 2H bipy and 1H NH],
8.24 [m, 4H, bipy], 7.74 [m, 10H, 8H H-Co BAr′4 and 2H bipy],
7.57 [m, 4H H-Cp BAr′4], 7.53 [m, 6H, 2Ph], 6.28 [m, 4H, 2Ph].
13C{1H} NMR: 194.90 [2CO], 190.07 [CO], 188.42 [CdN],
155.58, 153.92. 141.12 [bipy], 137.00, 136.53, 134.28, 132.36.
130.37, 129.90 [2Ph], 129.64 [bipy], 124.59, 124.40 [2Ph], 123.99
[bipy]. Anal. Calcd for C58H31BF24N3O3Re: C, 47.36; H, 2.12; N,
2.85. Found: C, 47.29; H, 2.25; N, 2.87.
[Re(N(Me)CHPh)(CO)3(bipy)]BAr′4 (5). Yield: 0.048 g, 84%.
1
IR: 2038, 1929. H NMR:38 8.66 [m, 2H bipy], 8.11 [m, 5H, 4H
bipy and NdCH], 7.74 [m, 10H, 8H H-Co BAr′4 and 2H bipy],
7.57 [m, 4H H-Cp BAr′4], 7.37 [m, 3H, Ph], 7.08 [m, 2H, Ph],
3.49 [d(1.5 Hz), 3H, CH3]. 13C{1H} NMR: 195.40 [2CO], 189.83
[CO], 179.33 [CdN], 155.83, 153.97. 140.77 [bipy], 133.08, 131.76,
[Ph], 129.01 [bipy], 128.31, 127.72 [Ph], 124.06 [bipy], 56.80
[CH3]. Anal. Calcd for C52H29BF24N3O3Re: C, 44.71; H, 2.09; N,
3.00. Found: C, 44.83; H, 2.15; N, 3.07.
[Re(MeCOMe)(CO)3(bipy)]BAr′4 (6a). Yield: 0.043 g, 88%.
IR: 2040, 1934, 1621(CdO). 1H NMR: 9.11 [m, 2H, bipy], 8.25
[m, 4H, bipy], 7.73 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.54
[m, 4H H-Cp BAr′4], 2.28 [s, 6H, CH3]. 13C{1H} NMR: 228.38
[CdO], 195.30 [2CO], 190.98 [CO], 156.23, 153.99. 141.62,
129.11, 123.14 [bipy], 31.95 [CH3]. Anal. Calcd for C48H26-
BF24N2O4Re: C, 42.77; H, 1.94; N, 2.07. Found: C, 42.55; H,
1.98; N, 2.12.
[Re(PPh3)(CO)3(bipy)]BAr′4 (2). Yield: 0.042 g, 75%. IR:
1
2041, 1957, 1928. H NMR: 8.57 [m, 2H, bipy], 7.99 [m, 4H,
bipy], 7.77 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.58 [m, 4H
H-Cp BAr′4], 7.29-7.13 [m, 15H, PPh3]. 13C{1H} NMR: 195.05
[2CO], 186.70 [d (58.14), CO], 162.16 [q (49.79), CI BAr′4], 155.37,
154.03, 140.17 [bipy], 135.19 [s, Co BAr′4], 134.78 [d (10.7), PPh3],
133.25 [d (54.7), PPh3], 130.95 [d (2.8), PPh3], 129.49 [bipy],
128.68 [d (10.4), PPh3], 128.18 [q (31.1), Cm BAr′4], 124.94 [q
(272.59), CF3], 123.91 [bipy], 117.87 [Cp BAr′4]. Anal. Calcd for
C63H35BF24N2O3PRe: C, 48.75; H, 2.27; N, 1.80. Found: C, 48.87;
H, 2.34; N, 1.68.
[Re(MeCOPh)(CO)3(bipy)]BAr′4 (6b). Yield: 0.042 g, 84%.
IR: 2040, 1934, 1661(CdO). 1H NMR: 9.07 [m, 2H, bipy], 8.25
[m, 4H, bipy], 7.72 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.54
[m, 4H H-Cp BAr′4], 7.28 [m, 5H, Ph], 2.89 [s, 3H, CH3]. 13C-
{1H} NMR: 214.97 [CdO], 196.85 [2CO], 192.67 [CO], 157.65,
155.56. 143.12 [bipy], 138.90, 136.04, 131.08, 129.85 [Ph], 129.49,
123.48 [bipy], 29.32 [CH3]. Anal. Calcd for C53H28BF24N2O4Re:
C, 45.15; H, 2.00; N, 1.98. Found: C, 45.29; H, 2.15; N, 1.87.
[Re(MeOH)(CO)3(bipy)]BAr′4 (7). Yield: 0.030 g, 61%. IR:
[Re(MeCN)(CO)3(bipy)]BAr′4 (3a). Yield: 0.039 g, 82%. IR:
1
1
2044, 1943. H NMR: 9.01 [m, 2H, bipy], 8.20 [m, 4H, bipy],
2037, 1928. H NMR: 9.08, 8.26 [m, 2H each, bipy], 7.73 [m,
10H, 8H H-Co BAr′4 and 2H bipy], 7.69 [m, 2H, bipy], 7.56 [m,
4H H-Cp BAr′4], 5.81 [q (4.04 Hz), 1H, OH], 3.39 [d, 3H, CH3],
3.24 [m, CH3, free methanol]. 13C{1H} NMR: 195.49 [2CO],
189.92 [CO], 156.44, 154.11. 141.87, 128.87, 124.27 [bipy], 58.60
[CH3], 51.37 [free methanol]. Anal. Calcd for C47H28BF24N2O5Re:
C, 41.82; H, 1.79; N, 2.07. Found: C, 41.75; H, 1.85; N, 2.16.
[Re(Et2O)(CO)3(bipy)]BAr′4 (8). Yield: 0.045 g, 86%. IR:
(31) (a) Casarrubios, L.; Pe´rez, J. A.; Brookhart, M.; Templeton, J. L. J.
Org. Chem. 1996, 61, 8358-8360. (b) Morales, D.; Pe´rez, J.; Riera,
L.; Riera, V.; Corzo-Sua´rez, R.; Garc´ıa-Granda, S.; Miguel, D.
Organometallics, 2002, 21, 1540-1545.
(32) SAINT+. SAX area detector integration program, version 6.02; Bruker
AXS, Inc.: Madison, WI, 1999.
(33) Sheldrick, G. M. SHELXTL, An integrated system for solVing, refining,
and displaying crystal structures from diffraction data; version 5.1;
Bruker AXS, Inc.: Madison, WI, 1998.
(34) Sheldrick, G. M. SADABS, Empirical Absorption Correction Program;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(35) To prepare complex [Re(MeI)(CO)3(bipy)]BAr′4 (10), neat io-
domethane was employed as solvent.
1
2041, 1935. H NMR: 9.05 [m, 2H, bipy], 8.25 [m, 4H, bipy],
7.74 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.54 [m, 4H H-Cp
BAr′4], 3.66 [q (7.7 Hz), 4H, CH2], 3.40 [q (7.3 Hz), 4H, CH2,
free ether], 1.05 [t (7.7), 6H, CH3], 1.01 [t (7.3), 6H, CH3, free
ether]. 13C{1H} NMR: 195.55 [2CO], 189.86 [CO], 156.23, 154.08.
(36) Stoichiometric amounts of PPh3 and nitriles, and 5 equiv of the
remaining ligands used.
(37) The ether complex 8 was crystallized from hexane diffusion into a
diethyl ether solution.
(38) NMR data are given for the major isomer.
4678 Inorganic Chemistry, Vol. 41, No. 18, 2002

Cationic Rhenium Tricarbonyl Bipyridine Complexes
141.82, 129.49, 124.24 [bipy], 67.75. [CH2], 66.10 [CH2, free ether],
17.16 [CH3], 14.86 [CH3, free ether]. Anal. Calcd for C53H40-
BF24N2O5Re: C, 44.27; H, 2.80; N, 1.94. Found: C, 44.35; H,
2.85; N, 1.86.
hexane into a THF solution. Yield: 0.014 g, 68%. IR (THF): 2096
(νCtC); 2006, 1902 (νCO).1H NMR: 9.06, 8.21, 7.81, 7.52 [m, 2H
each, bipy], 6.96 [m, 3H, Ph], 6.84 [m, 2H, Ph]. 13C{1H} NMR:
199.03 [2CO], 192.03 [CO], 156.01, 153.41 [bipy], 148.75 [Ph],
138.81 [bipy], 131.51 [Ph], 128.04 [bipy], 127.20, 125.29 [Ph],
123.39 [bipy], 117.81, 105.80 [CtCPh]. Anal. Calcd for C21H13N2O3-
Re: C, 47.81; H, 2.48; N, 5.31. Found: C, 47.79; H, 2.52; N, 5.51.
Preparation of [Re(CtCSiMe3)(CO)3(bipy)] (13). To a solu-
tion of [Re(THF)(CO)3(bipy)]BAr′4 (9) (0.054 g, 0.040 mmol) in
THF cooled to -78 °C was added a LiCtCSiMe3 solution prepared
in situ by reaction of HCtCSiMe3 (5.6 µL, 0.040 mmol) and nBuLi
(25 µL of a 1.6 M solution in hexane, 0.040 mmol) in THF at -78
°C. The mixture was stirred for 15 min, and the workup was as
described for 12. Compound 13 was obtained as an orange solid.
Yield: 0.015 g, 71%. IR (THF): 2038 (νCtC); 2000, 1903 (νCO).
1H NMR: 9.01, 8.21, 7.81, 7.52 [m, 2H each, bipy], -0.30 [s, 3H,
SiMe3]. Anal. Calcd for C18H17N2O3ReSi: C, 41.28; H, 3.27; N,
5.34. Found: C, 41.41; H, 3.32; N, 5.41.
[Re(THF)(CO)3(bipy)]BAr′4 (9). Yield: 0.039 g, 80%. IR:
1
2039, 1932. H NMR: 9.11 [m, 2H, bipy], 8.25 [m, 4H, bipy],
7.73 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.54 [m, 4H H-Cp
BAr′4], 3.51 [m, 4H, CH2-O, THF], 1.71 [m, 4H, CH2, THF]. 13C-
{1H} NMR: 195.89 [2CO], 189.47 [CO], 156.20, 154.11. 142.02,
129.11, 123.14 [bipy], 77.41 [CH2O, THF], 25.81 [CH2, THF].
Anal. Calcd for C49H28BF24N2O4Re: C, 43.21; H, 2.07; N, 2.05.
Found: C, 43.34; H, 2.12; N, 2.11.
[Re(MeI)(CO)3(bipy)]BAr′4 (10). Yield: 0.035 g, 68%. IR:
1
2042, 1937. H NMR: 9.07 [m, 2H, bipy], 8.25 [m, 4H, bipy],
7.72 [m, 10H, 8H H-Co BAr′4 and 2H bipy], 7.56 [m, 4H H-Cp
BAr′4], 2.26 [s, 3H, CH3I]. 13C{1H} NMR: 195.01 [2CO], 189.45
[CO], 156.19, 154.33. 142.02, 129.01, 123.13 [bipy], 1.14 [CH3I].
Anal. Calcd for C46H23BF24IN2O3Re: C, 38.59; H, 1.65; N, 1.95.
Found: C, 38.47; H, 1.72; N, 1.81.
Aziridination Reaction. To a solution of [Re(THF)(CO)3(bipy)]-
BAr′4 (9) (0.026 g, 0.019 mmol) in CH2Cl2 (20 mL) was added
2,6 di-tert-butylpyridine (10 µL, 0.038 mmol), benzylideneaniline
(0.345 g, 1.903 mmol), and EDA (0.2 mL, 1.903 mmol). The
mixture was stirred under nitrogen for 8 h, and the volatiles were
removed under vacuum. The 1H NMR spectrum showed full
conversion to a mixture of the cis-(carboxyethyl)-1,3-diphenylaziri-
Reaction of [Re(OMe)(CO)3(bipy)] with HBF4‚Et2O. [Re-
(OMe)(CO)3(bipy)]26 (0.050 g, 0.109 mmol) was dissolved in CH2-
Cl2 (10 mL), and the solution was cooled at -78 °C. The
stoichiometric amount of HBF4‚Et2O (8 µL, 0.109 mmol) was
added. The color of the solution changed from red to yellow.
Volatiles were removed under vacuum, and the yellow solid was
disolved in CH2Cl2 (5 mL). Slow diffusion of hexanes into this
solution afforded crystals of [Re(OEt2)(CO)3(bipy)]BF4‚(11).
1
dine A (72%, H NMR integration) and the enamines B and C
(Scheme 5). cis-(Carboxyethyl)-1,3-diphenylaziridine (A). 1H NMR
(CDCl3): 1.03 [t, 3H, J ) 7.05 Hz, CH3]; 3.25 [d, 1H, J ) 6.8 Hz,
CHPh]; 3.63 [d, 1H, J ) 6.8 Hz, CHCO]; 3.97-4.13 [m, 2H, CH2];
6.90-7.58 [m, 10H, C6H5].
1
Yield: 0.039 g, 62%. IR: 2041, 1935. H NMR: 9.04, [m, 2H,
bipy], 8.31 [m, 4H, bipy], 7.68 [m, 2H, bipy], 3.64 [q (7.7 Hz),
4H, CH2], 1.10 [t (7.7), 6H, CH3]. 19F{1H} NMR: -155.8. Anal.
Calcd for C17H18BF4N2O4Re: C, 34.76; H, 3.08; N, 4.76. Found:
C, 34.67; H, 3.12; N, 4.80
Acknowledgment. We thank Ministerio de Ciencia y
Tecnolog´ıa and Ministerio de Educacio´n, Cultura y Deporte
for support of this work (Projects MCT-00-BQU-0220,
PB97-0470-C02-01, and PR-01-GE-7) and a predoctoral
fellowship (to E.H.)
Preparation of [Re(CtCPh)(CO)3(bipy)] (12). To a solution
of phenylacetylene (4.5 µL, 0.040 mmol) in THF (10 mL) cooled
n
to -78 °C was added BuLi (25 µL of 1.6 M solution in hexane,
0.040 mmol), and the resulting solution of LiCtCPh was transferred
via cannula into a solution of [Re(THF)(CO)3(bipy)]BAr′4 (9) (0.054
g, 0.040 mmol) in THF (10 mL). The mixture was allowed to reach
room temperature and stirred for 15 min. The resulting orange
solution was evaporated in vacuo, and the residue was extracted
with toluene cooled at 0 °C (3 × 10 mL) and filtered with a cannula
tipped with filter paper. Pure 12 was obtained by slow diffusion of
Supporting Information Available: CIF file giving positional
and thermal parameters, bond distances, and bond angles for 6a,
6b, and 9. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC020174C
Inorganic Chemistry, Vol. 41, No. 18, 2002 4679