Synthesis of N-heterocyclic carbene complexes of manganese(I) by coupling isocyanide ligands with propargylamines and propargylic alcohols

Article abstract of DOI:10.1021/om700718x

A variety of N-heterocyclic carbene (NHC) complexes of general formula fac-[Mn(NHC)(CO)₃(bipy)]⁺ have been prepared by reaction of the manganese(I) isocyanide complexes fac-[Mn(CNR)(CO)₃(bipy)] ⁺ with propargylamines and propargylic alcohols and characterized by spectroscopic and X-ray diffraction methods.

Full text of DOI:10.1021/om700718x

Organometallics 2007, 26, 5687-5695
5687
Synthesis of N-Heterocyclic Carbene Complexes of Manganese(I) by
Coupling Isocyanide Ligands with Propargylamines and Propargylic
Alcohols§
Javier Ruiz,*,† Bernabe´ F. Perandones,† Gabriel Garc´ıa,† and Marta E. G. Mosquera‡
Departamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Qu´ımica, UniVersidad de OViedo,
33006 OViedo, Spain, and Departamento de Qu´ımica Inorga´nica, Edificio de Farmacia, UniVersidad de
Alcala´, 28871 Alcala´ de Henares, Spain
ReceiVed July 18, 2007
A variety of N-heterocyclic carbene (NHC) complexes of general formula fac-[Mn(NHC)(CO)3(bipy)]+
have been prepared by reaction of the manganese(I) isocyanide complexes fac-[Mn(CNR)(CO)3(bipy)]+
with propargylamines and propargylic alcohols and characterized by spectroscopic and X-ray diffraction
methods.
Scheme 1. Proposed Mechanism for the Formation of NHC
Complexes
Introduction
No doubt the chemistry of N-heterocyclic carbenes (NHCs)
has been one of the most active areas of research in organo-
metallic chemistry in recent years.1 Isolation by Arduengo et
al. of the first stable, crystalline NHC was a milestone in this
chemistry,2 which was followed soon afterward by the recogni-
tion of the great potential of NHC complexes in transition metal
homogeneous catalysis.3 The synthesis of NHC complexes is
generally accomplished by reaction of the corresponding imi-
dazolium salts with the appropriate metallic fragment, with either
a basic ligand attached to the metal or an external base acting
as the deprotonating agent.1b Alternatively, direct reaction of
free NHC with the metal complex precursor can be employed,1b
as well as transmetalation reaction from NHC complexes of
silver(I).4 A synthetic route to NHC complexes involving four-
component condensation reactions with cyano transition metal
complexes has also been reported.5
Reaction of coordinated isocyanides with amines is a well-
known method for the synthesis of diaminocarbene complexes.6
The extension of this procedure to haloamines leads to the
preparation of cyclic diaminocarbenes.7 Furthermore intramo-
lecular cyclization of amino-functionalized isocyanides leading
to benzannulated NHC complexes has also been described in
the literature.8 In relation with this, we have recently com-
municated a new experimental approach to the synthesis of NHC
complexes based on the metal-assisted coupling of isocyanides
and propargylamine.9 We report now in this paper a detailed
account of the synthesis of manganese(I) complexes bearing
NHC ligands of imidazoline-2-ylidene and imidazolidine-2-
ylidene types and their analogous N,O-heterocyclic carbenes,
by coupling different arylic and alkylic isocyanide ligands with
a variety of propargylamines and propargylic alcohols.
§ Dedicated to the memory of Professor Lorenzo Pueyo.
* Corresponding author. E-mail: jruiz@fq.uniovi.es.
† Universidad de Oviedo.
‡ Universidad de Alcala´.
(1) (a) Arduengo, A. J., III. Acc. Chem. Res. 1999, 32, 913. (b) Bourissou,
D.; Guerret, O.; Gabba¨ı, F. P.; Bertrand, G. Chem. ReV. 2000, 100, 39. (c)
Crabtree, R. H. Coord. Chem. ReV. 2007, 251, 595. (d) Herrmann, W. A.;
Schu¨tz, J.; Frey, G. D.; Herdtweck, E. Organometallics 2006, 25, 2437,
and references therein.
(2) Arduengo, A. J., III; Harlow, R. L.; Kline, M., W. A. J. Am. Chem.
Soc. 1991, 113, 361.
(3) Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41, 1290, and
references therein.
Results and Discussion
(4) Garrison, J. C.; Youngs, W. J. Chem. ReV. 2005, 105, 3978.
(5) (a) Fehlhammer; W. P.; Fritz, M. Chem. ReV. 1993, 93, 1243. (b)
Rieger, D.; Lotz, S. D.; Kernbach, U.; Andre´, C.; Bertran-Nadal, J.;
Fehlhammer, W. P. J. Organomet. Chem. 1995, 491, 135.
(6) (a) Crociani, B. In Reactions of Coordinated Ligands; Braterman, P.
S., Ed.; Plenum Press: New York, 1986; pp 553-638. (b) Singleton, E.;
Oosthuizen, H. E. AdV. Organomet. Chem. 1983, 22, 209.
(7) (a) Michelin, R. A.; Pombeiro, A. J. L.; Guedes da Silva, M. F. C.
Coord. Chem. ReV. 2001, 218, 75. (b) Tamm, M.; Hahn, F. E. Coord. Chem.
ReV. 1999, 182, 175. (c) Belluco, U.; Michelin, R. A.; Ros, R.; Bertani, R.;
Facchin, G.; Mozzon, M.; Zanotto, L. Inorg. Chim. Acta 1992, 198-200,
883.
N,N-Heterocyclic Carbene Complexes. Reaction of the
cationic isocyanide complexes fac-[Mn(CNR)(CO)3(bipy)]+ (1a,
(8) (a) Hahn, F. E.; Langenhahn, V.; Pape, T. Chem. Commun. 2005,
5390. (b) Hahn, F. E.; Langenhahn, V.; Meier, N.; Lu¨gger, T.; Fehlhammer,
W. P. Chem.-Eur. J. 2003, 9, 704. (c) Hahn, F. E.; Plumed, C. G.; Mu¨nder,
M.; Lu¨gger, T. Chem.-Eur. J. 2004, 10, 6285. (d) Liu, C.; Chen, D.; Lee,
G.; Peng, S.; Liu, S. Organometallics 1996, 15, 1055.
(9) Ruiz, J.; Garc´ıa, G.; Mosquera, M. E. G.; Perandones, B. F.; Gonzalo,
M. P.; Vivanco, M. J. Am. Chem. Soc. 2005, 127, 8584.
10.1021/om700718x CCC: $37.00 © 2007 American Chemical Society
Publication on Web 10/13/2007

5688 Organometallics, Vol. 26, No. 23, 2007
Table 1. Selected IR Spectral and H and 13C NMR Spectroscopic Data
IR (CH2Cl2, cm-1)a ν(CO) 1H NMR,b δ
Ruiz et al.
1
compd
13C{1H} NMR,b δ (Ccarbene
)
1a
2050vs, 1990s, 1957s
2175m ν(CN)
1b
1c
1d
1e
1f
2052vs, 1996s, 1962s
2172m ν(CN)
2050vs, 1990s, 1957s
2176m ν(CN)
2050vs, 1989s, 1957s
2171m ν(CN)
2051vs, 1993s, 1959s
2171m ν(CN)
1.97 (6H, s, CH3)
2.14 (3H, s, CH3)
4.78 (2H, s, CH2)
2050vs, 1983s, 1951s
2212m ν(CN)
2034vs, 1955s, 1928s
3b
4.37 (2H, s, NCH2)
222.4
4.23 (1H, d, 3JHH ) 3, dCH2)
3.77 (1H, d, 3JHH ) 3, dCH2)
4.91 (2H, d, 4JHH ) 6, CH2 Bz)
4.40 (1H, s, dCH2)
3f
2032vs, 1951s, 1923s
4.17 (1H, s, dCH2)
3.83 (2H, s, NCH2)
4a
4b
4c
4d
2028vs, 1944s, 1925s
2030vs, 1949s, 1926s
2029vs, 1945s, 1923s
2029vs, 1945s, 1925s
9.76 (1H, s, NH)
6.94 (1H, s, dCH)
1.74 (3H, s, CH3)
9.65 (1H, s, NH)
7.03 (1H, s, dCH)
1.85 (3H, s, CH3)
10.02 (1H, s, NH)
7.02 (1H, s, dCH)
184.7
189.0
184.7
1.79 (3H, s, CH3)
9.60 (1H, s, NH)
7.09 (1H, s, dCH)
1.76 (6H, s, CH3 xylyl)
1.72 (3H, s, CH3)
4e
4f
2029vs, 1946s, 1925s
2031vs, 1949s, 1921s
2035vs, 1957s, 1928s
9.54 (1H, s, NH)
7.08 (1H, d, 4JHH ) 1, dCH)
2.08 (3H, s, CH3 Ph)
1.77 (3H, s, CH3)
9.70 (1H, s, NH)
6.78 (1H, s, dCH)
4.89 (2H, s, CH2 Bz)
1.88 (2H, s, CH3)
4.61 (2H, s, CH2)
5b
217.7
4.22 (1H, s, dCH2)
3.66 (3H, s, NCH3)
3.41 (1H, s, dCH2)
6a
8a
8b
8c
2025vs, 1939s, 1917s
2040vs, 1964s, 1934s
2043vs, 1969s, 1936s
2040vs, 1964s, 1934s
6.35 (1H, s, dCH)
4.02 (3H, s, NCH3)
1.54 (3H, s, CH3)
181.9
241.0
245.9
241.2
5.14 (2H, t, 4JHH ) 3, OCH2)
4.51 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
3.99 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
5.05 (2H, t, 4JHH ) 3, OCH2)
4.51 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
4.07 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
5.18 (2H, t, 4JHH ) 3, OCH2)
4.55 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
4.06 (1H, q, 2JHH ) 4JHH ) 3, dCH2)
1.77 (3H, s, CH3)
9a
9b
2038vs, 1960s, 1933s
2041vs, 1965s, 1935s
215.9
219.0
7.65 (1H, s, dCH)
1.84 (3H, s, CH3)
10b
11a
2043vs, 1969s, 1937s
2038vs, 1960s, 1933s
4.48-4.46 (1H, m, dCH2)
4.15-4.13 (1H, m, dCH2)
1.21 (3H, d, 3JHH ) 7, CH3)
2.08 (2H, s, CH3)
243.2
213.3
241.3
246.4
1.64 (3H, s, CH3)
11b
12a
2043vs, 1969s, 1937s
2039vs, 1962s, 1934s
1.78 (3H, s, CH3), 1.73 (3H, s, CH3)
4.96 (2H, quint, 4JHH ) 5JHH ) 3, OCH2)
4.80 (1H, qt, 3JHH ) 8, 4JHH ) 3, CH)
0.77 (3H, dt, 3JHH ) 8, 5JHH ) 3, CH3)
4.99 (2H, quint, 4JHH ) 5JHH ) 2, OCH2)
4.84 (1H, q, 3JHH ) 7, CH)
0.97 (3H, d, 3JHH )7, CH3)
12b
2042vs, 1968s, 1935s
b
a Abbreviations: v ) very, s ) strong, m ) medium. NMR spectra recorded in CD2Cl2 at rt.
R ) phenyl; 1b, R ) 2,6-difluorophenyl; 1c, R ) 2-naphthyl;
1d, R ) xylyl; 1e, R ) 2-chloro-6-methylphenyl; 1f, R )
benzyl)10 with an excess of propargylamine in THF results in
the formation of the carbene complexes 4a-f (Scheme 1). The

N-Heterocyclic Carbene Complexes of Manganese(I)
Organometallics, Vol. 26, No. 23, 2007 5689
Table 2. Crystallographic Data for 3a, 4b, and 8a
3b
4b
8a
formula
fw
C23H16ClF2MnN4O7
588.79
C23H16ClF2MnN4O7
588.79
C23H17ClMnN3O8
553.79
color/habit
yellow/prism
0.58 × 0.30 × 0.30
monoclinic
P21/n
9.5104(9)
19.863(4)
13.515(3)
107.984(9)
2428.3(7)
4
yellow/prism
0.43 × 0.30 × 0.30
monoclinic
P21/n
10.9964(13)
17.422(3)
13.6750(15)
104.356(11)
2538.0(6)
4
yellow/prism
0.58 × 0.42 × 0.17
orthorhombic
Pcab
13.223(4)
14.573(3)
24.6375(16)
90
cryst dimensions, mm3
cryst syst
space group
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
4747.6(18)
8
T, K
200
1.611
0.722
1192
200
1.541
0.691
1192
298
1.550
0.723
2256
D
calcd, g cm-3
µ, mm-1
F(000)
θ range, deg
3.74-27.51
5.04-27.50
3.59-27.49
no. of rflns collected
no. of indep rflns/Rint
no. of obsd rflns (I>2σ(I))
no. of data/restraints/params
R1/wR2 (I>2σ(I))a
R1/wR2 (all data)a
GOF (on F2)a
49 238
49 195
44 718
5581/0.0650
3923
5581/0/351
0.0447/0.0895
0.0804/0.1014
1.028
5786/0.0508
4306
5786/0/347
0.0384/0.0893
0.0635/0.0977
1.037
5432/0.0904
3286
5432/0/333
0.0462/0.0975
0.1021/0.1242
1.023
largest diff peak and hole, e Å-3
+0.473/-0.488
+0.592/-0.468
+0.361/-0.397
2
2
2
2
2
a R1 ) ∑(||Fo| - |Fc||)/∑|Fo|; wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2; GOF ) {∑[w(Fo - Fc )2]/(n - p)}1/2
.
reaction was monitored by IR spectroscopy, which shows the
disappearance of the νCN band of the coordinated isocyanide
ligands (2171-2212 cm-1) once the reaction is finished. In
parallel, the νCO bands of the carbonyl ligands undergo an
appreciable shift to low frequencies (see Table 1). This indicates
that the NHC ligands are better electron donors than their parent
isocyanide ligands. Compounds of type 4 were fully character-
ized by spectroscopic and analytical methods (see Table 1 and
Experimental Section); additionally in the case of 4b an X-ray
diffraction study was undertaken (Figure 1), and the corre-
sponding structural features will be discussed in detail below.
The formation of the new carbene ligands is evidenced by the
presence of a low-field signal around 185 ppm in the 13C{1H}
NMR spectra, corresponding to the carbene carbon atom. In
(9.54-10.02 ppm). Also of note is the presence of the vinyl
proton resonance in the range 6.78-7.09 ppm.
The proposed mechanism for the formation of the NHC
complexes 4 is shown in Scheme 1. As nucleophilic addition
of amines to isocyanides is a typical reaction of isocyanide
complexes,6,7 it seems obvious that the first step of the reaction
involves the nucleophilic attack of propargylamine to this ligand
to afford the acyclic diaminocarbene complexes of type 2. These
species would then undergo an intramolecular hydroamination
to give the cyclic carbenes 3, which in a final step are
transformed to complexes 4 by a 1,3 proton shift from the
endocyclic methylene group to the exocyclic one. Supporting
this mechanism, the intermediate derivatives 3 could be detected
in the course of the reaction and, in the case of 3b and 3f, were
conveniently isolated as pure species by controlling the reaction
time and the amount of propargylamine added. The reaction
time for the formation of derivatives 3 varies from 5 min
(compound 3b) to 2 days (compound 3f), showing that nucleo-
philic attack of propargylamine to the isocyanide is favored for
aryl isocyanides containing electron-withdrawing substituents.
The transformation of complexes of type 3 into 4 is base-
promoted; in fact 3b,f are stable in solution for days and are
not transformed into 4b,f unless a base is added (propargylamine
or triethylamine).
1
the H NMR spectra the new methyl group of the heterocycle
appears as a singlet at about 1.8 ppm, and the proton of the
N-H group displays a typical high-frequency singlet signal
The IR spectra of 3b and 3f show νCO bands at slightly
higher frequencies than 4b and 4f, indicating that the imida-
zolidine-2-ylidene carbenes in 3 are slightly poorer electron
donors than the imidazoline-2-ylidene carbenes in 4. On the
other hand, the carbene-carbon signal in the 13C{1H} NMR
spectrum of 3b is shifted 33 ppm downfield with respect to 4b,
which is a typical trend observed in the literature when
comparing saturated versus unsaturated NHC ligands.11 It is also
worth noting the presence of signals for both the methylene
Figure 1. Molecular structure of 4b, shown with 30% thermal
ellipsoids. Hydrogen atoms of the bipy ligand and 2,6-difluorophe-
nyl substituent are omitted for clarity. Selected interatomic distances
(Å) and angles (deg): Mn1-C2 ) 2.078(2), N1-C2 ) 1.377(3),
C2-N3 ) 1.354(3), N3-C4 ) 1.398(3), C4-C5 ) 1.354(3), C5-
N1 ) 1.417(3), C5-C6 ) 1.501 (3); Mn1-C2-N1 ) 133.3(1),
Mn1-C2-N3 ) 124.3(2), N1-C2-N3 ) 102.3(2), C2-N3-C4
) 113.3(2), N3-C4-C5 ) 106.7(2), C4-C5-N1 ) 105.2(2),
C5-N1-C2 ) 112.5(2).
1
and vinylidene CH2 protons in the H NMR spectra of 3b and
3f in the expected range (see Table 1). Furthermore, in the case
(10) Garc´ıa Alonso, F. J.; Riera, V.; Villafan˜e, F.; Vivanco, M. J.
Organomet. Chem. 1984, 276, 39.
(11) (a) Arduengo, A. J., III; Goerlich, J. R.; Marshall, W. J. J. Am.
Chem. Soc. 1995, 117, 11027. (b) Denk, M. K.; Avinash, T.; Hatano, K.;
Lough, A. J. Angew. Chem., Int. Ed. Engl. 1997, 36, 2607.

5690 Organometallics, Vol. 26, No. 23, 2007
Ruiz et al.
Scheme 2. Generation of Imidazoline-Functionalized
Diphosphine Ligand; [Mn]+ ) [Mn(CO)4]+
Scheme 3. Preparation of N-Methylated NHC Complexes;
[Mn]+ ) fac-[Mn(CO)3(bipy)]+
Figure 2. Molecular structure of 3b, shown with 30% thermal
ellipsoids. Hydrogen atoms of the bipy ligand and 2,6-difluorophe-
nyl substituent are omitted for clarity. Selected interatomic distances
(Å) and angles (deg): Mn1-C2 ) 2.068(3), N1-C2 ) 1.375(3),
C2-N3 ) 1.338(3), N3-C4 ) 1.458(3), C4-C5 ) 1.481(4), C5-
N1 ) 1.437(3), C5-C6 ) 1.350(4); Mn1-C2-N1 ) 132.2(2),
Mn1-C2-N3 ) 122.6(2), N1-C2-N3 ) 105.1(2), C2-N3-C4
) 114.9(2), N3-C4-C5 ) 102.2(2), C4-C5-N1 ) 104.6(2),
C5-N1-C2 ) 113.1(2).
of 3b an X-ray diffraction study was carried out (Figure 2),
allowing a comparison of the structural parameters of this
complex with those of the corresponding unsaturated hetero-
cyclic carbene 4b (Figure 1). For 3b the distances C2-N1
(1.375(3) Å) and C2-N3 (1.338(3) Å) are intermediate between
single and double bond as a consequence of the implication of
the lone pairs of both nitrogen atoms in those bonds. The slightly
longer value of the C2-N1 bond length with respect to C2-
N3 can be attributed to the conjugation of the N1 lone pair with
the exocyclic double bond, which deviates some electron density
toward that bond; in fact the N1-C5 bond length is slightly
shorter than a single bond (1.437(3) Å). For complex 4b the
different bond lengths within the heterocycle are, in variable
degree, intermediate between single and double bond, reflecting
the existence of electronic delocalization in the heterocycle. The
N1-C2-N3 bond angle for 3b (105.1(2)°) is opened somewhat
relative to the unsaturated analogue 4b (102.3(2)°). Curiously
both angles are in the range of values usually found in free
carbenes of imidazolidine2-ylidene and imidazoline-2-ylidene
types, respectively,11,12 being slightly smaller than those nor-
mally encountered in coordinated carbenes of both types.1b,12,13
Finally, the C2-Mn bond distances for 3b and 4b are 2.068(3)
and 2.078(2) Å, respectively.
intermediacy of the metallic center in the process. Although
the acyclic derivatives 2 have not been detected in the reaction
course, it could also be tentatively proposed a tautomerization
reaction in these species from the terminal alkyne to the
corresponding allene previous to the cyclization process, as
apparently the hydroamination reaction could take place more
easily in the latter, according to related processes described in
the literature.16
It is also worth remarking that we had already observed a
similar cyclization process of propargylamine with coordinated
diphosphinoketenimine ligands to afford imidazoline-function-
alized diphosphines (Scheme 2),17 so that in a certain sense the
isocyanide complexes 1 behave as ketenimine functionalities.
With the aim of preparing unsymmetrically substituted NHC
ligands we extended the reaction above to N-methylpropargy-
lamine. This proved to be much less reactive than propargy-
lamine; in fact in these reactions only the imidazolidine-2-
ylidene complex 5b could be obtained (see Scheme 3) and with
much longer reaction time (1 day) than for 3b (5 min).
Tautomerization of 5b to the corresponding unsaturated carbene
(imidazoline-2-ylidene) complex was not possible in this case
even after adding a great excess of triethylamine as an external
base.
The cyclization process of 2 involving a terminal alkyne
proposed in Scheme 1 is noteworthy, as the hydroamination
reactions of unactivated akynes described in the literature take
place only in a catalytic manner.14 In those reactions, coordina-
tion of the alkyne to metals, such as Rh(I), Pd(II), or Cu(I),
promotes the nucleophilic attack of the amine, allowing the
catalytic hydroamination to occur.15 In our case, the Mn(I) ion
has a closed octahedral coordination sphere, avoiding the direct
The formation of an N-methylated NHC ligand was also
observed by deprotonation of complex 4a with KOtBu and
further treatment of the neutral intermediate with MeI (Scheme
3). In this way complex 6a is obtained and fully characterized
by spectroscopic methods (Table 1), the signal at 4.02 ppm in
the 1H NMR spectrum showing clearly the presence of the new
methyl group added to the molecule.
(12) Herrmann, W. A.; Ko¨cher, C. Angew. Chem., Int. Ed. Engl. 1997,
36, 2162.
N,O-Heterocyclic Carbene Complexes. In a similar process
to that described above complexes 1 reacted with propargylic
alcohol, generating N,O-heterocyclic carbene ligands. In this
(13) (a) Fu¨rsnter, A.; Seidel, G.; Kremzow, D.; Lehmann, C. W.
Organometallics 2003, 22, 907. (b) Huynh, H. V.; Han, Y.; Ho, J. H. H.;
Tan, G. K. Organometallics 2006, 25, 3267.
(14) Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Angew. Chem., Int. Ed.
2004, 43, 3368.
(15) Jonson, J. R.; Bergman, R. G. J. Am. Chem. Soc. 2001, 123, 2923.
(b) Mu¨ller, T. E.; Grosche, M.; Herdtweck, E.; Pleier, A. K.; Walter, E.;
Yan, Y. K. Organometallics 2000, 19, 170. (c) Utsonomiya, M.; Kuwano,
R.; Kawatsura, M.; Hartwig, J. F. J. Am. Chem. Soc. 2003, 125, 5608. (d)
Uchimaru, Y. Chem. Commun. 1999, 1133.
(16) (a) Szmuszkovicz, J.; Musser, J. H.; Laurian, L. G. Tetrahedron
Lett. 1978, 8, 701. (b) Cossy, J.; Poitevin, C.; Salle´, L.; Pardo, G.
Tetrahedron Lett. 1996, 37, 6709.
(17) Ruiz, J.; Mosquera, M. E. G.; Garc´ıa, G.; Marqu´ınez, F.; Riera, V.
Angew. Chem., Int. Ed. 2005, 44, 102.

N-Heterocyclic Carbene Complexes of Manganese(I)
Organometallics, Vol. 26, No. 23, 2007 5691
Scheme 4. Postulated Mechanism for the Formation of
N,O-Heterocyclic Carbene Complexes; [Mn]+
)
fac-[Mn(CO)3(bipy)]+
Figure 3. Molecular structure of 8a, shown with 30% thermal
ellipsoids. Hydrogen atoms of the bipy ligand and phenyl substituent
are omitted for clarity. Selected interatomic distances (Å) and angles
(deg): Mn1-C2 ) 2.042(3), N1-C2 ) 1.335(4), C2-O3 ) 1.340-
(3), O3-C4 ) 1.464(4), C4-C5 ) 1.496(4), C5-N1 ) 1.438(4),
C5-C6 ) 1.319(5); Mn1-C2-N1 ) 135.0(2), Mn1-C2-O3 )
116.5(2), N1-C2-O3 ) 108.5(2), C2-O3-C4 ) 111.5(2), O3-
C4-C5 ) 103.5(2), C4-C5-N1 ) 103.3(2), C5-N1-C2 )
113.0(2).
case however a mixture of HOCH2CtCH and NaOCH2CtCH
must be employed, as the propargylic alcohol itself is not
nucleophilic enough for the reaction to take place. By controlling
the reaction time complexes of type 8 (Scheme 4), containing
an exocyclic carbon-carbon double bond (oxazolidine-2-ylidene
carbenes), were isolated, which were transformed into the
corresponding unsaturated cyclic carbenes 9 (oxazoline-2-
ylidene carbenes) with longer reaction times. The mechanism
proposed in Scheme 4 for the formation of these complexes is
comparable to that described before for the formation of N,N-
heterocyclic carbenes (Scheme 1). The IR spectra of 8 and 9
show νCO bands at higher frequencies than those of 3 and 4,
so that it can be deduced that the N,O-heterocyclic carbenes
feature weaker basic character than the N,N-heterocyclic car-
benes, which is probably due to the higher electronegativity of
oxygen with respect to nitrogen. Moreover, the bands of
compounds 9 in these spectra appear at slightly lower frequen-
cies than those of 8, showing once again the stronger basic
character of the unsaturated carbene ligands with respect to the
saturated ones. The 1H NMR spectra of these complexes (Table
1) display signals of the singlet resonance of the newly formed
methyl group (9a,b) and the two quartet signals for the
methylene and vinylidene CH2 protons (8a-c). Finally, the 13C-
{1H} NMR spectra show the typical low-field signal for the
carbene carbon atom.
synthesis of their transition metal complexes,19 as that described
herein. Related benzoxazol-2-ylidene carbene complexes can
be prepared by intramolecular cyclization of 2-hydroxyphenyl
isocyanide coordinated to transition metals.20 However this
implies a multiple-step process, as free 2-hydroxyphenyl iso-
cyanide is not stable and the hydroxy group must be protected
before coordination.
The use of substituted propargylic alcohol enlarges the
synthetic possibilities of the methodology above. Thus reaction
of complexes 1 with 3-butyn-2-ol allows the synthesis of N,O-
heterocyclic carbene complexes fully substituted on the different
atoms of the heterocycle, as is exemplified with the preparation
1
of complexes 10b, 11a, and 11b (Scheme 5). The H NMR
spectra of 11a,b show the expected signals for the two methyl
groups present as substituents in the new NHC ligands, whereas
that of the isolable intermediate 10b features as most relevant
signals those corresponding to the methyl and vinylidene groups
(Table 1). Analogously, the use of a propargylic alcohol
containing an internal alkyne, such as 2-butyn-1-ol, leads to
the formation of N,O-heterocyclic carbenes with a longer carbon
chain as substituent in the heterocycle (Scheme 5). In this last
case only the complexes containing oxazolidine-2-ylidene
ligands (12a and 12b) were obtained, being not possible to
achieve the transformation of these complexes into the corre-
sponding saturated tautomers.
The structure of complex 8a in the solid state was elucidated
by an X-ray diffraction study (Figure 3). Among the different
structural parameters it is worth pointing out the C2-N1 (1.335-
(4) Å) and C2-O3 (1.340(3) Å) bond lengths, which indicate
some multiple-bond character, showing once more the implica-
tion of the heteroatom lone pair in those bonds. On the other
hand, the Mn-C1 distance (2.042(3) Å) in this oxazolidine-2-
ylidene carbene complex is shorter than the corresponding
distance in the imidazolidine-2-ylidene derivative 3b (2.068(3)
Å), leading to the apparent contradiction that a minor donor
character of the carbene ligand causes a stronger interaction of
the carbene with the metallic center. No doubt much more data
are necessary to ascertain this statement, but it seems clear that
π-back-donation from the metal to the carbene ligand must not
be neglected in these complexes, as it has been pointed out in
recent papers.18
(18) (a) D´ıez-Gonza´lez, S.; Nolan, S. P. Coord. Chem. ReV. 2007, 251,
874. (b) Tafipolsky, M.; Scherer, W.; O¨ fele, K.; Artus, G.; Perdersen, B.;
Herrmann, W. A.; McGrady, G. S. J. Am. Chem. Soc. 2002, 124, 5865. (c)
Hu, X.; Tang, Y.; Gantzel, P.; Meyer, K. Organometallics 2003, 22, 612.
(d) Boehme, C.; Frenking, G. Organometallics 1998, 17, 5801. (e) Ge´rard,
H.; Clot, E.; Eisenstein, O. New J. Chem. 1999, 23, 495. (f) Huang, J.;
Schanz, H.-J; Stevens, E. D.; Nolan, S. P. Inorg. Chem. 2000, 39, 1042.
(19) Reactions of gem-dicyano and cyanocarbethoxy epoxides with
cyanometal acids yield oxazol-2-ylidene complexes: (a) See ref 5a, p 1270.
(b) Kunz, R.; Grel, P. L.; Fehlhammer, W. P. J. Chem. Soc., Dalton Trans.
1996, 3231.
(20) (a) Hahn, F. E.; Tamm M. J. Chem. Soc., Chem. Commun. 1993,
842. (b) Hahn, F. E.; Tamm, M.; Lu¨gger, T. Angew. Chem., Int. Ed. Engl.
1994, 33, 1356. (c) Hahn, F. E.; Tamm, M. J. Organomet. Chem. 1993,
456, C11. (d) Tamm, M.; Hahn, F. E. Coord. Chem. ReV. 1999, 182, 175-
209. (e) Barluenga, J.; Aznar, F.; Weyershausen, B.; Garc´ıa-Granda, S.;
Mart´ın, E. Chem. Commun. 1996, 2455.
It should be noted that, contrary to imidazol-2-ylidene, free
oxazol-2-ylidene carbenes are not isolable, being of special
interest the development of new reaction pathways for the

5692 Organometallics, Vol. 26, No. 23, 2007
Ruiz et al.
Scheme 5. Preparation of N,O-Heterocyclic Carbene
Complexes by Using Substituted Propargylic Alcohols;
[Mn]+ ) fac-[Mn(CO)3(bipy)]+; a, R ) Ph; b, R )
2,6-difluorophenyl
removal of the solvent, the residue was dissolved in 3 mL of CH2-
Cl2. Addition of hexane (15 mL) caused the formation of a yellow
solid, which was filtered off and dried under vacuum. 1b‚ClO4:
yield 0.135 g (95%). Anal. (%) Calcd for C20H11N3ClF2MnO7: C
45.01, H 2.08, N 7.87. Found: C 44.97, H 1.93, N 8.00. IR (CH2-
Cl2): ν 2172 (m) (CN), 2034 (vs), 1955 (s), 1928 (s) cm-1 (CO).
1H NMR (400 MHz, CD2Cl2): δ 9.00 (2H, d, 3JHH ) 5, Ha bipy),
3
3
8.54 (2H, d, JHH ) 8, Hd bipy), 8.28 (2H, t, JHH ) 8, Hc bipy),
3
3
7.71 (2H, d, JHH ) 7, Hb bipy), 7.41 (1H, t, JHH ) 9, C6H3F2),
3
3
7.00 (2H, t, JHH ) JHF ) 8, C6H3F2). 1c‚ClO4: yield 0.141 g
(97%). Anal. (%) Calcd for C24H15N3ClMnO7: C 52.62, H 2.76,
N 7.67. Found: C 52.20, H 2.42, N 7.63. IR (CH2Cl2): ν 2176
(m) (CN), 2050 (vs), 1990 (s), 1957 (s) cm-1 (CO). 1H NMR (400
3
MHz, CD2Cl2): δ 9.08 (2H, d, JHH ) 5, Ha bipy), 8.74 (2H, d,
3JHH ) 8, Hd bipy), 8.30 (2H, t, JHH ) 7, Hc bipy), 7.88-7.83
3
3
(4H, m, C10H7), 7.74 (2H, t, JHH ) 6, Hb bipy), 7.61-7.58 (2H,
m, C10H7), 7.25 (1H, d, 3JHH ) 8, C10H7). 1d‚ClO4: yield 0.112 g
(80%). Anal. (%) Calcd for C22H17N3ClMnO7: C 50.26, H 3.26,
N 7.99. Found: C 49.94, H 3.15, N 7.55. IR (CH2Cl2): ν 2171
(m) (CN), 2050 (vs), 1989 (s), 1957 (s) cm-1 (CO). 1H NMR (400
Conclusion
In this paper we have described a new method for the
generation of N-heterocyclic carbenes, consisting of the coupling
of coordinated isocyanide ligands with propargylamines and
propargylic alcohols. The reaction proceeds through initial
nucleophilic attack of the amine or the alkoxide to the
isocyanide, followed by an intramolecular cyclization process
that implies a formal hydroamination reaction of the alkyne
residue. This approach allows the synthesis of Mn(I) complexes
containing a variety of carbene ligands of imidazoline-2-ylidene
and imidazolidine-2-ylidene types, as well as their analogous
N,O-heterocyclic carbenes. Fine control of the nature of the
carbene can be achieved by choosing the isocyanide ligand and
the substituents on the propargylamine and propargylic alcohol
frameworks.
3
MHz, CD2Cl2): δ 8.99 (2H, d, JHH ) 6, Ha bipy), 8.52 (2H, d,
3JHH ) 8, Hd bipy), 8.22 (2H, t, JHH ) 8, Hc bipy), 7.66 (2H, t,
3
3JHH ) 7, Hb bipy), 7.13 (1H, t, 3JHH ) 8, xylyl), 6.99 (2H, d, 3JHH
) 8, xylyl), 1.97 (6H, s, CH3 xylyl). 1e‚ClO4: yield 0.143 g (98%).
Anal. (%) Calcd for C21H14N3Cl2MnO7: C 46.18, H 2.58, N 7.69.
Found: C 46.35, H 2.27, N 7.74. IR (CH2Cl2): ν 2171 (m) (CN),
2051 (vs), 1993 (s), 1959 (s) cm-1 (CO). 1H NMR (400 MHz, CD2-
Cl2): δ 8.99 (2H, d, 3JHH ) 5, Ha bipy), 8.86 (2H, d, 3JHH ) 8, Hd
3
3
bipy), 8.33 (2H, t, JHH ) 8, Hc bipy), 7.71 (2H, t, JHH ) 7, Hb
bipy), 7.27-7.13 (3H, m, C6H3ClCH3), 2.14 (3H, s, CH3). 1f‚
ClO4: yield 0.115 g (85%). Anal. (%) Calcd for C21H15N3-
ClMnO7: C 49.29, H 2.95, N 8.21. Found: C 49.64, H 3.08, N
8.40. IR (CH2Cl2): ν 2212 (m) (CN), 2050 (vs), 1983 (s), 1951 (s)
cm-1 (CO). 1H NMR (400 MHz, CD2Cl2): δ 8.89 (2H, d, 3JHH
)
)
3
3
5, Ha bipy), 8.61 (2H, d, JHH ) 8, Hd bipy), 8.23 (2H, t, JHH
Experimental Section
7, Hc bipy), 7.61 (2H, t,3JHH ) 7, Hb bipy), 7.34-7.33 (3H, m,
Bz), 7.09-7.06 (2H, m, Bz), 4.78 (2H, s, CH2).
General Remarks. All reactions and manipulations were carried
out under a nitrogen atmosphere using standard Schlenk techniques.
Solvents were distilled over appropriate drying agents under dry
nitrogen prior to use. Compound fac-[Mn(CO)3(CNPh)(bipy)]ClO4
(1a‚ClO4) was prepared according to a reported protocol.10 NMR
spectra were recorded on Bruker 300 and 400 MHz spectrometers.
NMR multiplicities are abbreviated as follows: d ) doublet, t )
triplet, q ) quartet, quint ) quintet, qt ) quartet of triplets, m )
multiplet. Coupling constants J are given in Hz. Propargylamines
and propargylalcohols were purchased from Aldrich and used
without purification.
Safety note: Perchlorate salts of metal complexes with organic
ligands are potentially explosive. Only small amounts of such
materials should be prepared, and these should be handled with
great caution.
For the NMR spectra the atom labeling in the 2,2′-bipyridine
ligand is as follows:
Synthesis of 3b‚ClO4. A solution containing 1b (0.10 g, 0.19
mmol) and propargylamine (0.480 mL, 7.5 mmol) in thf (10 mL)
was stirred at room temperature for 5 min. The solvent was then
evaporated to dryness and the remaining oil dissolved in CH2Cl2
(4 mL). Addition of hexane (12 mL) caused the precipitation of a
yellow solid of the product, which was filtered off and dried under
vacuum. Yield: 0.088 g (80%). Anal. (%) Calcd for C23H16N4-
ClF2MnO7: C 46.92, H 2.74, N 9.52. Found: C 46.85, H 2.90, N
9.56. IR (CH2Cl2): ν 2034 (vs), 1955 (s), 1928 (s) cm-1 (CO). 1H
3
NMR (400 MHz, CD2Cl2): δ 8.80 (2H, d, JHH ) 5, Ha bipy),
3
3
8.35 (2H, d, JHH ) 8, Hd bipy), 8.15 (2H, t, JHH ) 7, Hc bipy),
7.61-7.11 (3H, m, Hb bipy, Hpara C6H3F2), 7.16-7.11 (3H, m, NH,
2
Hmeta C6H3F2), 4.37 (2H, s, N-CH2), 4.23 (1H, d, JHH ) 3, d
CH2), 3.77 (1H, d, 2JHH ) 3, dCH2). 13C NMR (100.7 MHz, CD2-
1
Cl2): δ 222.4 (Ccarbene), 219.3, 212.7 (CO), 160.2 (d, JFC ) 254,
CF), 155.1 (C1 bipy), 153.4 (C2 bipy), 145.9 (Cipso C6H3F2), 139.4
(C3 bipy),132.3 (Carom C6H3F2), 127.3 (C4 bipy), 124.1 (C5 bipy),
2
113.0 (d, JFC ) 20, Cmeta C6H3F2), 84.6 (dCH2), 51.0 (N-CH2).
Synthesis of 3f‚ClO4. A mixture containing 1f (0.10 g, 0.20
mmol) and propargylamine (0.501 mL, 7.82 mmol) in thf (10 mL)
was stirred for 24 h at room temperature. After this period of time
a new amount of propargylamine (0.250 mL, 3.90 mmol) was
added, and the resulting solution was stirred for another 24 h. The
solvent was then evaporated under vacuum, and the oil obtained
was dissolved in CH2Cl2 (5 mL). Some toluene (15 mL) was added,
and the resulting solution concentrated to 7 mL, inducing the
appearance of a brown solid. After filtration, the solid was dissolved
in CH2Cl2 (3 mL) and hexane added (12 mL), causing precipitation
of a solid, which was filtered off and dried under vacuum. Yield:
0.080 g (72%). Anal. (%) Calcd for C24H20N4ClMnO7: C 50.85,
Synthesis of 1b-f‚ClO4. These compounds were obtained
following a similar procedure to that used for the synthesis of 1a
with slight modifications. A mixture of [Mn(CO)3(bipy)Br] (0.10
g, 0.27 mmol) and AgClO4 (0.066 g, 0.32 mmol) in acetone (10
mL) was stirred for 1 h in the dark and then filtered off to remove
the AgBr formed. Then 1.2 equiv of the corresponding isocyanide
was added to the filtrate, and the mixture stirred for 3 h. After

N-Heterocyclic Carbene Complexes of Manganese(I)
Organometallics, Vol. 26, No. 23, 2007 5693
H 3.56, N 9.88. Found: C 50.39, H 3.37, N 9.94. IR (CH2Cl2): ν
2032 (vs), 1951 (s), 1923 (s) cm-1 (CO). 1H NMR (300 MHz, CD2-
Cl2): δ 9.08 (2H, d, 3JHH ) 6, Ha bipy), 8.35 (2H, d, 3JHH ) 8, Hd
bipy), 8.12 (2H, t, JHH ) 9, Hc bipy), 7.58 (2H, t, JHH ) 6, Hb
bipy), 7.30-6.78 (6H, m, Harom, NH), 4.91 (2H, d, 4JHH ) 6, CH2
Bz), 4.40 (1H, s, dCH2), 4.17 (1H, s, dCH2), 3.83 (2H, s, N-CH2).
8, Hd bipy), 8.13 (2H, t, 3JHH ) 8, Hc bipy), 7.58 (2H, t, 3JHH ) 8,
3
3
Hb bipy), 7.38 (1H, t, JHH ) 7, Hpara xylyl), 7.21 (2H, d, JHH
)
7, Hmeta xylyl), 7.09 (1H, s, dCH), 1.76 (6H, s, CH3 xylyl), 1.72
(3H, s, CH3). 13C NMR (100.7 MHz, CD2Cl2): δ 220.9, 213,8 (br,
CO); 155.6 (C1 bipy), 154.2 (C2 bipy), 145.7 (Cipso Xylyl), 139.8
(C3 bipy); 135.3-125.8 (Carom xylyl); 128.2 (C4 bipy), 124.4 (C5
bipy), 119.5 (dCH), 18.3 (CH3 xylyl), 10.0 (CH3).
3
3
Synthesis of 4a‚ClO4. To a solution of 1a‚ClO4 (0.10 g, 0.20
mmol) in thf (10 mL) was added propargylamine (0.533 mL, 8.32
mmol). The resulting mixture was stirred for 4 h. The solvent was
then evaporated to dryness under reduced pressure and CH2Cl2/
toluene (1:4) (16 mL) added to the remaining oil. Then the mixture
was stirred for 30 min. The resulting suspension was filtered off,
affording a yellow solution, which was concentrated to 5 mL.
Addition of hexane (10 mL) gave a yellow solid, which was dried
under vacuum. Yield: 0.098 g (88%). Anal. (%) Calcd for
C23H18N4ClMnO7: C 49.97, H 3.28, N 10.13. Found: C 50.26, H
3.55, N 10.12. IR (CH2Cl2): ν 2028 (vs), 1944 (s), 1925 (s) cm-1
Synthesis of 4e‚ClO4. To a solution of 1e‚ClO4 (0.1 g, 0.18
mmol) in thf (10 mL) was added propargylamine (0.502 mL, 7.32
mmol) and the resulting mixture stirred for 5 h. The solution was
evaporated to dryness, affording a brown oil. CH2Cl2/toluene (1:3)
(16 mL) was added and the mixture stirred for 10 min. The resulting
suspension was filtered off and the solution concentrated to 5 mL.
Addition of hexane (10 mL) gave a yellow solid, which was filtered
off and dried under vacuum. Yield: 0.060 g (55%). Anal. (%) Calcd
for C24H19N4Cl2MnO7: C 47.94, H 3.19, N 9.32. Found: C 47.70,
H 3.25, N 9.49. IR (CH2Cl2): ν 2029 (vs), 1946 (s), 1925 (s) cm-1
1
1
(CO). H NMR (300 MHz, CD2Cl2): δ 9.84 (1H, s, NH), 8.77
(CO). H NMR (300 MHz, CD2Cl2): δ 9.54 (1H, s, NH), 9.01
3
3
3
3
(2H, d, JHH ) 6, Ha bipy), 8.23 (2H, d, JHH ) 8, Hd bipy), 8.05
(1H, d, JHH ) 5, Ha bipy), 8.74 (1H, d, JHH ) 5, Ha bipy), 8.35
3
3
3
(2H, t, JHH ) 8, Hc bipy), 7.54-7.45 (5H, m, Hb bipy, Hmeta Ph,
(1H, d, JHH ) 8, Hd bipy), 8.31 (1H, d, JHH ) 8, Hd bipy), 8.19
(1H, td, 3JHH ) 8, 4JHH ) 1, Hc bipy), 8.10 (1H, td, 3JHH ) 8, 4JHH
) 1, Hc bipy), 7.70 (1H, t, 3JHH ) 6, Hb bipy), 7.54-7.39 (4H, m,
Hb bipy, Harom C7H6Cl), 7.08 (1H, d, 4JHH ) 1, dCH), 2.08 (3H, s,
CH3 C7H6Cl), 1.77 (3H, s, CH3).
3
Hpara Ph), 7.08 (2H, d, JHH ) 7, Horto Ph), 6.94 (1H, s, CdCH),
1.74 (3H, s, CH3). 13C NMR (75.5 MHz, CD2Cl2): δ 221.1, 213.8
(br, CO); 184.7 (Ccarbene), 155.1 (C1 bipy), 153.8 (C2 bipy), 139.3
(C3 bipy), 138.1 (Cipso Ph),132.7 (C-CH3); 129.2, 128.5, 126.9
(Carom);127.8 (C4 bipy), 123.9 (C5 bipy), 117.9 (dCH), 10.4 (CH3).
Synthesis of 4f‚ClO4. To a solution of 1f‚ClO4 (0.1 g, 0.20
mmol) in thf (10 mL) was added propargylamine (0.501 mL, 7.82
mmol) and the mixture stirred for 24 h. After this period of time a
new amount of propargylamine (0.250 mL, 3.90 mmol) was added
and the mixture stirred for another 4 days. The solution was
evaporated to dryness under vacuum and the resulting oil extracted
with CH2Cl2/toluene (1:3) (16 mL), to afford an orange solution,
which was filtered off and concentrated under reduced pressure (5
mL). Addition of hexane (10 mL) afforded an orange solid, which
was filtered off and dried under vacuum. Yield: 0.080 g (72%).
Anal. (%) Calcd for C24H20N4ClMnO7: C 50.85, H 3.56, N 9.88.
Found: C 51.02, H 3.35, N 9.60. IR (CH2Cl2): ν 2031 (vs), 1949
Synthesis of 4b‚ClO4. The procedure is completely analogous
to that described above, using 1b‚ClO4 (0.1 g, 0.19 mmol) and
propargylamine (0.480 mL, 7.50 mmol) and with a stirring time of
24 h. Yield: 0.075 g (68%). Anal. (%) Calcd for C23H16N4ClF2-
MnO7: C 46.92, H 2.72, N 9.52. Found: C 47.17, H 3.05, N 9.63.
IR (CH2Cl2): ν 2030 (vs), 1949 (s), 1926 (s) cm-1 (CO). 1H NMR
3
(400 MHz, CD2Cl2): δ 9.65 (1H, s, NH), 8.85 (2H, d, JHH ) 5,
3
3
Ha bipy), 8.34 (2H, d, JHH ) 8, Hd bipy), 8.14 (2H, t, JHH ) 8,
3
Hc bipy), 7.63-7.55 (3H, m, Harom C6H3F2), 7.18 (2H, d, JHH
)
8, Hb bipy), 7.03 (1H, s, dCH), 1.85 (3H, s, CH3). 13C NMR (100.7
MHz, CD2Cl2): δ 220.8, 214,0 (br, CO); 189.0 (Ccarbene), 159.9 (d,
1JFC ) 254, CF), 155.7 (C1 bipy), 153.9 (C2 bipy), 139.9 (C3 bipy);
133,3, 133.1 (Carom C6H3F2);128.1 (C4 bipy), 124.5 (C5 bipy), 119.1
1
(s), 1921 (s) cm-1 (CO). H NMR (300 MHz, CD2Cl2): δ 9.70
(1H, s, NH), 9.07 (2H, d, 3JHH ) 6, Ha bipy), 8.35 (2H, d, 3JHH
)
2
(dCH), 113.5 (d, JFC ) 20, Cmeta C6H3F2), 9.9 (CH3).
8, Hd bipy), 8.12 (2H, t, 3JHH ) 8, Hc bipy), 7,63 (2H, t, 3JHH ) 8,
Hb bipy), 7.26-7.24 (5H, m, Harom Bz), 6,78 (1H, s, dCH), 4.89
(2H, s, CH2 Bz), 1.88 (3H, s, CH3).
Synthesis of 4c‚ClO4. This was similarly prepared from 1c (0.10
g, 0.18 mmol) and propargylamine (0.501 mL, 7.30 mmol).
Reaction time: 3 h. Yield: 0.070 g (64%). Anal. (%) Calcd for
C27H20N4ClMnO7: C 53.79, H 3.34, N 9.29. Found: C 54.42, H
3.77, N 9.15. IR (CH2Cl2): ν 2029 (vs), 1945 (s), 1923 (s) cm-1
Synthesis of 5b‚ClO4. To a solution of 1b‚ClO4 (0.10 g, 0.19
mmol) in thf (10 mL) was added N-methylpropargylamine (0.624
mL, 7.49 mmol) and the mixture stirred for 24 h. The solution was
evaporated to dryness, and the resulting brown oil extracted with
CH2Cl2/toluene (1:3) (16 mL). The resulting yellow solution was
filtered off and concentrated to 5 mL. Addition of hexane (10 mL)
gave a yellow solid, which was filtered off and dried under vacuum.
Yield: 0.060 g (53%). Anal. (%) Calcd for C24H18N4ClF2MnO7:
C 47.82, H 3.01, N 9.29. Found: C 47.98, H 3.09, N 9.33. IR
1
(CO). H NMR (400 MHz, CD2Cl2): δ 10.02 (1H, s, NH), 8.72
3
3
(1H, d, JHH ) 5, Ha bipy), 8.68 (1H, d, JHH ) 5, Ha bipy), 8.21
(2H, d, 3JHH ) 8, Hd bipy), 8.04 (2H, t, 3JHH ) 8, Hc bipy), 7.96-
3
4
7.92 (2H, m, Harom C10H7), 7.67 (2H, td, JHH ) 7, JHH ) 1, Hb
4
3
bipy), 7.53 (1H, d, JHH ) 2, Harom C10H7), 7.37 (1H, t, JHH ) 6,
H
arom C10H7), 7.25-7.13 (3H, m, Harom C10H7), 7.02 (1H, s, dCH),
1.79 (3H, s, CH3). 13C NMR (100.7 MHz, CD2Cl2): δ 221.1, 213.6
(br, CO); 184.7 (Ccarbene), 155.0 (C1 bipy), 153.8 (C2 bipy), 139.1
(C3 bipy); 135.3, 133.7, 133.5, 130.3, 128.7, 128.4, 128.2, 127.2,
125.8 (C10H7); 127.7 (C4 bipy), 123.6 (C5 bipy), 118.1 (dCH), 10.3
(CH3).
(CH2Cl2): ν 2035 (vs), 1957 (s), 1928 (s) cm-1 (CO). H NMR
1
3
(400 MHz, CD2Cl2): δ 8.77 (2H, d, JHH ) 5, Ha bipy), 8.11-
3
8.08 (4H, m, Hd bipy, Hc bipy), 7.57 (2H, t, JHH ) 5, Hb bipy),
3
4
3
7.28 (1H, quint, JHH ) JHF ) 7, Hpara C6H3F2), 6.49 (2H, t, JHH
3
) JHF ) 7, Hmeta C6H3F2), 4.61 (2H, s, N-CH2), 4.22 (1H, s, d
CH2), 3.66 (3H, s, N-CH3), 3.41 (1H, s, dCH2). 13C NMR (100.7
MHz, CD2Cl2): δ 221.8, 212,3 (br, CO); 217.7 (Ccarbene), 159.7 (d,
1JFC ) 255, CF), 156.1 (C1 bipy), 154.5 (C2 bipy), 145.7 (Cipso
C6H3F2), 140.2 (C3 bipy), 133,1 (Carom C6H3F2), 127.7 (C4 bipy),
124.4 (C5 bipy), 113.2 (d, 2JFC ) 19, Cmeta C6H3F2), 85,3 (dCH2),
58.5 (N-CH2), 40.4(N-CH3).
Synthesis of 4d‚ClO4. To a solution of 1d‚ClO4 (0.1 g, 0.19
mmol) in thf (10 mL) was added propargylamine (0.487 mL, 7.60
mmol) at rt. After 24 h of stirring a second amount of propargy-
lamine (0.244 mL, 3.81 mmol) was added. The resulting solution
was stirred for another 3 days; after this period of time a yellow
solid appeared. The solid was filtered off and dissolved in CH2Cl2
(5 mL). Addition of hexane (15 mL) and cooling (0 °C) gave a
yellow solid, which was dried under vacuum. Yield: 0.080 g (72%).
Anal. (%) Calcd for C25H22N4ClMnO7: C 51.69, H 3.82, N 9.65.
Found: C 51.81, H 3.99, N 9.29. IR (CH2Cl2): ν 2029 (vs), 1945
Synthesis of 6a‚ClO4. To a solution of 4a‚ClO4 (0.10 g, 0.18
mmol) in thf (10 mL) was added NaOtBu (0.018 g, 0.19 mmol).
The mixture was stirred for 10 min, after which the color of the
solution changed from yellow to red. Then the solution was filtered
off and MeI (0.022 mL, 0.35 mL) added dropwise; the mixture
was stirred for 3 h. The solution was concentrated to 3 mL and a
1
(s), 1925 (s) cm-1 (CO). H NMR (400 MHz, CD2Cl2): δ 9.60
(1H, s, NH), 8.81 (2H, d, 3JHH ) 5, Ha bipy), 8.30 (2H, d, 3JHH
)

5694 Organometallics, Vol. 26, No. 23, 2007
Ruiz et al.
(1H, t, JHH ) 6, Harom C10H7), 7.19-7.11 (2H, m, Harom C10H7),
3
mixture of solvents hexane/ether (1:1) (15 mL) added dropwise,
affording a yellow solid, which was filtered off and dried under
reduced pressure. Yield: 0.080 g (78%). Anal. (%) Calcd for
C24H20N4IMnO3: C 48.51, H 3.39, N 9.43. Found: C 48.27, H
3.61, N 9.65. IR (CH2Cl2): ν 2025 (vs), 1939 (s), 1917 (s) cm-1
(CO). 1H NMR (300 MHz, CD2Cl2): δ 8.82 (2H, d, 3JHH ) 6, Ha
4
2
4
5.18 (2H, t, JHH ) 3, O-CH2), 4.55 (1H, q, JHH ) JHH ) 3,
2
4
dCH2), 4.06 (1H, q, JHH ) JHH ) 3, dCH2). 13C NMR (75.5
MHz, CD2Cl2): δ 241.2 (Ccarbene), 220.2, 213,1 (br, CO); 155.9
(C1 bipy), 154.0 (C2 bipy), 146.0 (Cipso C10H7), 140.0 (C3 bipy),
134.3 (Cquater C10H7), 134.1 (Cquater C10H7), 131.5-125.5 (m, C4
bipy, C10H7), 124.1 (C5 bipy), 90.9 (dCH2), 75,6 (O-CH2).
3
3
bipy), 8.19 (2H, d, JHH ) 8, Hd bipy), 8.09 (2H, t, JHH ) 7, Hc
bipy), 7.64-6.91 (7H, m, Hb bipy, Harom Ph), 6.35 (1H, s, dCH),
4.02 (3H, s, N-CH3), 1.54 (3H, s, CH3). 13C NMR (75.5 MHz,
CD2Cl2): δ 221.6, 212,2 (br, CO); 181.9 (Ccarbene), 155.1 (C1 bipy),
153.1 (C2 bipy), 139.3 (C3 bipy), 136,4 (Cipso Ph), 133.2 (dC(CH3));
129.6, 128.8, 126.8 (Carom Ph); 127.0 (C4 bipy), 124.2 (C5 bipy),
122.1 (dCH), 39.6 (N-CH3), 9.7 (CH3).
Synthesis of 9a‚ClO4. The procedure was completely analogous
to that for the synthesis of 8a‚ClO4, using 1a‚ClO4 (0.10 g, 0.20
mmol), propargylic alcohol (1 mL, 17.18 mmol), and Na (0.04 g,
1.74 mmol), but with a longer reaction time (5 h). Yield: 0.078 g
(70%). Anal. (%) Calcd for C23H17N3ClMnO8: C 49.88, H 3.09,
N 7.59. Found: C 49.62, H 2.98, N 7.92. IR (CH2Cl2): ν 2038
(vs), 1960 (s), 1933 (s) cm-1 (CO). 1H NMR (300 MHz, CD2Cl2):
δ 8.71 (2H, d, 3JHH ) 5, Ha bipy), 8.37 (2H, d, 3JHH ) 7, Hd bipy),
8.13 (2H, t, 3JHH ) 7, Hc bipy), 7.64-7.32 (6H, m, Hb bipy, Harom
Synthesis of 8a‚ClO4. To a suspension of 1a‚ClO4 (0.10 g, 0.20
mmol) in propargylic alcohol (1 mL, 17.18 mmol) was added
metallic sodium (0.04 g, 1.74 mmol). The mixture was stirred at
room temperature for 3 h to give a dark red solution, and then
some CH2Cl2 (15 mL) was added. The solution was washed with
6 × 15 mL of water; then the organic layer was dried over Na2-
CO3 and the solvent was reduced to 3 mL. Hexane (15 mL) was
slowly added with continuous stirring to gave a yellow solid, which
was filtered off and dried under vacuum. Yield: 0.080 g (72%).
Anal. (%) Calcd for C23H17N3ClMnO8: C 49.88, H 3.09, N 7.59.
Found: C 49.47, H 2.80, N 7.56. IR (CH2Cl2): ν 2040 (vs), 1964
Ph, dCH), 7.11 (2H, d, 3JHH ) 7, Horto Ph), 1.77 (3H, s, CH3). 13
C
NMR (75.5 MHz, CD2Cl2): δ 219.8, 212,4 (br, CO), 215.9
(Ccarbene), 155.2 (C1 bipy), 153.2 (C2 bipy), 145.2 (Cipso Ph), 139.3
(C3 bipy), 133.7-130.7 (Carom Ph, dCH, CCH3), 127.0 (C4 bipy),
123.5 (C5 bipy), 7.6 (CH3).
Synthesis of 9b‚ClO4. The procedure was analogous to the
synthesis of 8b‚ClO4 using 1b‚ClO4 (0.10 g, 0.19 mmol), propar-
gylic alcohol (1 mL, 17.18 mmol), and Na (0.04 g, 1.74 mmol),
but with a longer reaction time (3 h). Yield: 0.070 g (63%). Anal.
(%) Calcd for C23H15N3ClF2MnO8: C 46.84, H 2.56, N 7.12.
Found: C 46.51, H 2.51, N 6.98. IR (CH2Cl2): ν 2041 (vs), 1965
1
(s), 1934 (s) cm-1 (CO). H NMR (300 MHz, CD2Cl2): δ 8.56
3
3
(2H, d, JHH ) 5, Ha bipy), 8.46 (2H, d, JHH ) 8, Hd bipy), 8.11
(2H, t, 3JHH ) 7, Hc bipy), 7.54-7.37 (5H, m, Harom Ph, Hb bipy),
3
4
1
(s), 1935 (s) cm-1 (CO). H NMR (400 MHz, CD2Cl2): δ 8.80
7.17 (2H, t, JHH ) 7, Harom Ph), 5,14 (2H, t, JHH ) 3, O-CH2),
4.51 (1H, q, 2JHH ) 4JHH ) 3, dCH2), 3.99 (1H, q, 2JHH ) 4JHH
)
3
3
(2H, d, JHH ) 5, Ha bipy), 8.40 (2H, d, JHH ) 8, Hd bipy), 8.19
(2H, t, 3JHH ) 7, Hc bipy), 7.76-7.70 (1H, m, Hpara C6H3F2), 7.65
3, dCH2). 13C NMR (75.5 MHz, CD2Cl2): δ 241.0 (Ccarbene); 221.6,
212,2 (br, CO); 156.0 (C1 bipy), 154.1 (C2 bipy), 145.9 (Cipso Ph),
140.1 (C3 bipy), 134.2-129.2 (Carom Ph), 127.7 (C4 bipy), 124.2
(C5 bipy), 90.8 (dCH2), 75.5 (O-CH2).
(1H, s, dCH), 7.56 (2H, t, 3JHH ) 7, Hb bipy), 7.23 (2H, t, 3JHH
)
3JHF ) 8, Hmeta C6H3F2), 1.84 (3H, s, CH3). 13C NMR (100.7 MHz,
1
CD2Cl2): δ 220.7, 212.6 (br, CO), 219.0 (Ccarbene), 158.4 (d, JFC
) 255, CF), 155.5 (C1 bipy), 153.3 (C2 bipy), 141.6 (Cipso C6H3F2),
139.8 (C3 bipy), 134.1 (dCH), 131.2 (CCH3), 127.2 (C4 bipy), 123.7
(C5 bipy), 113.3 (d, JFC ) 19, Cmeta C6H3F2), 6.9 (CH3).
Synthesis of 8b‚ClO4. The procedure was completely analogous
to that described above, using 1b‚ClO4 (0.10 g, 0.19 mmol),
propargylic alcohol (1 mL, 17.18 mmol), and Na (0.04 g, 1.74
mmol). Reaction time: 30 min. Yield: 0.060 g (54%). Anal. (%)
Calcd for C23H15N3ClF2MnO8: C 46.84, H 2.56, N 7.12. Found:
C 46.43, H 2.72, N 7.41. IR (CH2Cl2): ν 2043 (vs), 1969 (s), 1936
(s) cm-1 (CO). 1H NMR (300 MHz, CD2Cl2): δ 8.67 (2H, d, 3JHH
) 5, Ha bipy), 8.33 (2H, d, 3JHH ) 8, Hd bipy), 8.12 (2H, dd, 3JHH
2
Synthesis of 10b‚ClO4. To a cold (0 °C) suspension of 1b‚ClO4
(0.10 g, 0.19 mmol) in d,L-3-butyn-2-ol (1 mL, 12.76 mmol) was
added some Na (0.04 g, 1.74 mmol). The resulting mixture was
stirred at 0 °C for 30 min and then warmed to room temperature.
CH2Cl2 (20 mL) was added and the solution washed with 6 × 10
mL of water. The organic layer was dried over Na2CO3 and the
solvent reduced to 3 mL. Finally hexane (15 mL) was added to
gave a brown solid, which was filtered off and dried under vacuum.
Yield: 0.060 g (53%). Anal. (%) Calcd for C24H17N3ClF2MnO8:
C 47.74, H 2.84, N 6.96. Found: C 47.50, H 2.78, N 6.85. IR
3
) 6, JHH ) 7, Hc bipy), 7.66-7.56 (1H, m, Hpara C6H3F2), 7.49
(2H, dd, 3JHH ) 5, 3JHH ) 6, Hb bipy), 7.11 (2H, m, Hmeta C6H3F2),
4
2
4
5.05 (2H, t, JHH ) 3, O-CH2), 4.51 (1H, q, JHH ) JHH ) 3,
dCH2), 4.07 (1H, q, JHH ) JHH ) 3, dCH2). 13C NMR (75.5
MHz, CD2Cl2): δ 245.9 (Ccarbene); 218.8, 212.4 (br, CO); 159.2 (d,
1JFC ) 256, CF), 155.9 (C1 bipy), 153.7 (C2 bipy), 142.4 (Cipso
C6H3F2), 140.2 (C3 bipy), 134,3 (Carom C6H3F2), 127.6 (C4 bipy),
124.0 (C5 bipy), 113.8 (d, 2JFC ) 19, Cmeta C6H3F2), 89,5 (dCH2),
75.7 (O-CH2).
2
4
1
(CH2Cl2): ν 2039 (vs), 1962 (s), 1934 (s) cm-1 (CO). H NMR
(300 MHz, CD2Cl2): δ 8.78 (1H, d, 3JHH ) 5, Ha bipy), 8.72 (1H,
3
3
d, JHH ) 5, Ha bipy), 8.42 (2H, d, JHH ) 8, Hd bipy), 8.20 (2H,
t, 3JHH ) 8, Hc bipy), 7.73-7.54 (3H, m, 3JHH ) 5, Harom C6H3F2,
Hb bipy), 7.23-7.13 (2H, m, Hmeta C6H3F2), 4.48-4.46 (1H, m,
Synthesis of 8c‚ClO4. To 1 mL of propargylic alcohol (17.18
mmol) at 0 °C was slowly added butyl lithium (1.141 mL, 6.85
mmol, 6 M in hexane). The mixture was stirred for 5 min at room
temperature. Then 1c‚ClO4 (0.10 g, 0.18 mmol) was added and
the suspension stirred for 1 h. Afterward, CH2Cl2 (15 mL) was
added and the resulting solution washed with 6 × 15 mL of water.
The organic layer was dried over Na2CO3 and the solution
concentrated to 2 mL. Finally, some hexane (10 mL) was added to
give a yellow solid, which was filtered off and dried under reduced
pressure. Yield: 0.073 g (66%). Anal. (%) Calcd for C27H19N3-
ClMnO8: C 53.76, H 3.17, N 6.96. Found: C 53.83, H 3.37, N
7.07. IR (CH2Cl2): ν 2040 (vs), 1964 (s), 1934 (s) cm-1 (CO). 1H
3
dCH2), 4.15-4.13 (1H, m, dCH2), 1.21 (3H, d, JHH ) 7, CH3).
13C NMR (100.7 MHz, CD2Cl2): δ 243.2 (Ccarbene), 218.3, 212.8
1
(br, CO), 158.5 (d, JFC ) 257, CF), 155.3 (C1 bipy), 152.9 (C2
bipy), 146.6 (Cipso C6H3F2), 139.5 (C3 bipy), 133.6 (Carom C6H3F2),
2
126.9 (C4 bipy), 123.3 (C5 bipy), 113.1 (d, JFC ) 19, Cmeta
C6H3F2),111.1 (s, CdCH2), 89.1 (dCH2), 83.4 (O-CH), 21.0
(CH3).
Synthesis of 11a‚ClO4. To a suspension of 1a‚ClO4 (0.10 g,
0.20 mmol) in D,L-3-butyn-2-ol (1 mL, 12.76 mmol) was added
some Na (0.04 g, 1.74 mmol). The mixture was stirred for 3 days.
Then CH2Cl2 (15 mL) was added, and the resulting solution was
washed with 3 × 10 mL of water. The organic layer was dried
over Na2CO3 and reduced to 5 mL under vacuum. Addition of
hexane/diethyl ether (1:1) (20 mL) under vigorous stirring afforded
an orange solid, which was filtered off and dried under reduced
pressure. Yield: 0.070 g (61%). Anal. (%) Calcd for C24H19N3-
3
NMR (300 MHz, CD2Cl2): δ 8.57 (1H, d, JHH ) 5, Ha bipy),
3
3
8.51 (1H, d, JHH ) 5, Ha bipy), 8.34 (2H, d, JHH ) 8, Hd bipy),
8.11 (1H, td, 3JHH ) 7, 4JHH ) 1, Harom C10H7), 8.03-7.95 (3H, m,
Hc bipy, Harom C10H7), 7.82 (1H, d, 3JHH ) 9, Harom C10H7), 7.73-
4
7.63 (2H, m, Hb bipy), 7.59 (1H, d, JHH ) 2, Harom C10H7), 7.33

N-Heterocyclic Carbene Complexes of Manganese(I)
Organometallics, Vol. 26, No. 23, 2007 5695
ClMnO8: C 50.77, H 3.37, N 7.40. Found: C 51.01, H 3.50, N
(1 mL, 13.18 mmol), and butyl lithium (0.586 mL, 6 M in hexane).
Yield: 0.075 g (66%). Anal. (%) Calcd for C24H17N3ClF2MnO8:
C 47.74, H 2.84, N 6.96. Found: C 47.85, H 2.79, N 6.80. IR
7.32. IR (CH2Cl2): ν 2036 (vs), 1958 (s), 1932 (s) cm-1 (CO). 1H
3
NMR (300 MHz, CD2Cl2): δ 8.71 (2H, d, JHH ) 5, Ha bipy),
3
3
1
8.34 (2H, d, JHH ) 7, Hd bipy), 8.12 (2H, t, JHH ) 7, Hc bipy),
7.61-7.34 (5H, m, Hb bipy, Ph), 7.03 (2H, d, 3JHH ) 7, Ph), 2.08
(3H, s, OCCH3), 1.64 (3H, s, NCCH3). 13C NMR (75,5 MHz, CD2-
Cl2): δ 220.8, 213.7 (br, CO), 213.3 (Ccarbene), 155.9 (C1 bipy),
153.9 (C2 bipy), 150.3 (Cipso Ph), 140.0 (C3 bipy), 135.1-124.2
(Ph,C4,C5 bipy), 10.6 (CH3), 8.2 (CH3).
(CH2Cl2): ν 2042 (vs), 1968 (s), 1935 (s) cm-1 (CO). H NMR
(300 MHz, CD2Cl2): δ 8.73 (2H, d, 3JHH ) 5, Ha bipy), 8.41 (2H,
3
3
d, JHH ) 8, Hd bipy), 8.18 (2H, t, JHH ) 7, Hc bipy), 7.69-7.53
3
(3H, m, Harom C6H3F2, Hb bipy), 7.15 (2H, m, JHH ) 8, Hmeta
4
3
C6H3F2), 4.99 (2H, t, JHH ) 2, O-CH2), 4.84 (1H, q, JHH ) 7,
dCH), 0.97 (3H, d, JHH ) 7, CH3). 13C NMR (75,5 MHz, CD2-
3
1
Synthesis of 11b‚ClO4. To a cold (0 °C) suspension of 1b‚ClO4
(0.10 g, 0.19 mmol) in d,L-3-butyn-1-ol (1 mL, 12.76 mmol) was
added some Na (0.04 g, 1.74 mmol). The resulting mixture was
stirred at 0 °C for 30 min and then at room temperature for 1 day.
Then CH2Cl2 (10 mL) was added and the solution was washed with
3 × 10 mL of water. The organic layer was dried over Na2CO3
and the solvent reduced to 3 mL. Addition of hexane (15 mL) gave
an orange solid, which was filtered off and dried under vacuum.
Yield: 0.080 g (72%). Anal. (%) Calcd for C25H19N3Cl3F2MnO8
(11b‚CH2Cl2): C 43.60, H 2.78, N 6.10. Found: C 43.67, H 2.89,
N 6.01. IR (CH2Cl2): ν 2043 (vs), 1969 (s), 1937 (s) cm-1 (CO).
1H NMR (300 MHz, CD2Cl2): δ 8.77 (2H, d, 3JHH ) 5, Ha bipy),
8.40 (2H, d, 3JHH ) 8, Hd bipy), 8.18 (2H, td, 3JHH ) 8, 4JHH ) 1,
Cl2): δ 246.4 (Ccarbene), 219.0, 212.6 (br, CO), 159.9 (d, JFC
)
255, CF), 155.9 (C1 bipy), 153.7 (C2 bipy), 140.2 (C3 bipy), 134.4
(Cipso C6H3F2), 133.0 (Carom C6H3F2), 127.6 (C4 bipy), 124.0 (C5
2
bipy), 113.5 (d, JFC ) 20, Cmeta C6H3F2), 101.5 (s, dCH), 76.5
(O-CH2), 10.5 (CH3).
Single-Crystal X-ray Structure Determination of Compounds
3b, 4b, and 8a. Suitable yellow single crystals of 3b, 4b, and 8a
for the X-ray diffraction study were selected. For compound 8a
data collection was carried out at 293 K, whereas data collection
for 3b and 4b was performed at 200(2) K, the crystals being covered
with perfluorinated ether for 3b and 4b. The crystals were mounted
on a Bruker-Nonius Kappa CCD single-crystal diffractometer
equipped with graphite-monochromated Mo KR radiation (λ )
0.71073 Å). Multiscan21 absorption correction procedures were
applied to the data. The structures were solved, using the WINGX
package,22 by direct methods (SHELXS-97) and refined by using
full-matrix least-squares against F2 (SHELXL-97).23 All non-
hydrogen atoms were anisotropically refined. Hydrogen atoms were
geometrically placed and left riding on their parent atoms except
for the hydrogen atoms on C6 in compound 3b, N1 in compound
4b, and C4 in compound 8a. Full-matrix least-squares refinements
were carried out by minimizing ∑w(Fo2 - Fc2)2 with the SHELXL-
97 weighting scheme and stopped at shift/err < 0.001. The final
residual electron density maps showed no remarkable features.
3
4
Hc bipy), 7.56 (2H, td, JHH ) 5, JHH ) 1, Hb bipy), 7.46 (1H, t,
3JHH ) 8, Hpara C6H3F2), 7.26 (2H, d, JHH
C6H3F2), 1.78 (3H, s, CH3), 1.73 (3H, s, CH3).
)
3JHF ) 8, Hmeta
3
Synthesis of 12a‚ClO4. To 1 mL of 2-butyn-1-ol (13.37 mmol)
at 0 °C was slowly added butyl lithium (0.628 mL, 6 M in hexane).
The resulting mixture was stirred for 5 min at room temperature.
Then 1a‚ClO4 (0.10 g, 0.20 mmol) was added and the suspension
stirred for 20 h. CH2Cl2 (15 mL) was added and the solution washed
with 6 × 15 mL of water. The organic layer was dried over Na2-
CO3, and then the solvent reduced to 2 mL. Addition of hexane
(10 mL) afforded a yellow solid, which was filtered off and dried
under reduced pressure. Yield: 0.060 g (53%). Anal. (%) Calcd
for C24H19N3ClMnO8: C 50.77, H 3.37, N 7.40. Found: C 50.39,
H 3.23, N 7.89. IR (CH2Cl2): ν 2039 (vs), 1962 (s), 1934 (s) cm-1
(CO). 1H NMR (300 MHz, CD2Cl2): δ 8.64 (2H, d, 3JHH ) 5, Ha
Acknowledgment. This work was supported by the Spanish
Ministerio de Educacio´n y Ciencia (PGE and FEDER funding,
Project CTQ2006-10035) and the Principado de Asturias
(Project IB05-110). B.F.P. thanks the Universidad de Oviedo
for a grant.
3
3
bipy), 8.38 (2H, d, JHH ) 8, Hd bipy), 8.14 (2H, t, JHH ) 8, Hc
bipy), 7.59 (1H, d, 3JHH ) 7, Hpara Ph), 7.51-7.45 (4H, m, Hb bipy,
3
4
Harom Ph), 7.23 (2H, t, JHH ) 8, Harom Ph), 4.96 (2H, q, JHH
)
Supporting Information Available: Crystallographic data in
CIF format of complexes 3b, 4b, and 8a. This material is available
free of charge via the Internet at http://pubs.acs.org.
5JHH ) 3, O-CH2), 4.80 (1H, qt, 3JHH ) 8, 4JHH ) 3, dCH), 0.77
(3H, dt, 3JHH ) 8, 5JHH ) 3, CH3). 13C NMR (75,5 MHz, CD2Cl2):
δ 241.3 (Ccarbene); 220.1, 213.2 (br, CO), 155.9 (C1 bipy), 154.0
(C2 bipy), 140.0 (C3 bipy), 136.7 (Cipso Ph), 135.4 (dCoxaz), 131.1-
129.4 (Carom Ph), 127.4 (C4 bipy), 123.9 (C5 bipy), 101.3 (dCH),
76.3 (O-CH2), 10.3 (CH3).
OM700718X
(21) SOTARV: Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(22) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(23) Sheldrick, G. M. SHELXL97: Program for the Refinement of Crystal
Structures; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.
Synthesis of 12b‚ClO4. The procedure was analogous to that
described above, using 1b‚ClO4 (0.10 g, 0.19 mmol), 2-butyn-1-ol