Alkynylcarbyne(bipyridine)dicarbonyl(triflouroacetato) complexes - Synthesis and detection of reversible association in solution

Article abstract of DOI:10.1016/S0022-328X(02)02115-0

A series of alkynylcarbyne(bipyridine)(dicarbonyl)trifluoroacetato complexes, [CF₃COO(L-L)(CO)₂M≡C-C≡C-R] (M = W, Mo; L-L = 2,2′-bipyridine, 4,4′-dimethyl 2,2′-bipyridine; R = SiMe₃, Ph, p-Tol, t-Bu), has been prepared by sequential reaction of [M(CO)₆] with Li[C≡CR], trifluoroacetic anhydride, and L - L. All complexes were fully characterized. Concentrated solutions of these complexes exhibit two sets of ν(CO) absorptions (instead of the expected one set (A₁/B₁). The ratio A₁/B₁:A₁*/B₁* is concentration-dependent and decreases with increasing concentration of the complexes in solution. This phenomenon is discussed on the basis of a reversible association of complex molecules to form dimers and oligomers prior to precipitation and crystallization.

Full text of DOI:10.1016/S0022-328X(02)02115-0

Journal of Organometallic Chemistry 667 (2003) 16ꢃ23
/
www.elsevier.com/locate/jorganchem
Alkynylcarbyne(bipyridine)dicarbonyl(triflouroacetato) complexes*
/
synthesis and detection of reversible association in solution
Birgit Schwenzer, Helmut Fischer *
Fachbereich Chemie, Universitat Konstanz, Fach M727, 78457 Konstanz, Germany
¨
Received 4 September 2002; accepted 14 October 2002
Abstract
A series of alkynylcarbyne(bipyridine)(dicarbonyl)trifluoroacetato complexes, [CF3COO(LÃ
Mo; LÃLꢀ2,2?-bipyridine, 4,4?-dimethyl 2,2?-bipyridine; RꢀSiMe3, Ph, p-Tol, t-Bu), has been prepared by sequential reaction of
[M(CO)6] with Li[CÅCR], trifluoroacetic anhydride, and LÃL. All complexes were fully characterized. Concentrated solutions of
/
L)(CO)2MÅ
/
CÃ
/
CÅ
/
CÃ
/
R] (MꢀW,
/
/
/
/
/
/
ꢁ
ꢁ
these complexes exhibit two sets of n(CO) absorptions (instead of the expected one set (A1/B1). The ratio A1/B1:A1/B1 is
concentration-dependent and decreases with increasing concentration of the complexes in solution. This phenomenon is discussed
on the basis of a reversible association of complex molecules to form dimers and oligomers prior to precipitation and crystallization.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Carbyne complexes; Infrared spectra; Concentration-dependence; Tungsten; Molybdenum
1. Introduction
complexes with bidentate N-donor co-ligands an unu-
sual dependence of the IR spectra of the complexes on
the concentration was observed.
The synthesis of the first transition metal carbyne
complexes (alkylidyne complexes) was reported by
Fischer et al. in 1973 [1], that of the first transition
metal alkynylcarbyne(tetracarbonyl) complexes (alkyny-
lidyne complexes), X(CO)4WÅ
I), already 1 year later [2]. Ten years later, t-butylethy-
nylcarbyne(dicarbonyl) complexes containing bi- and
/
CÃ
/
CÅ
/
CÃ
/
Ph (XꢀCl, Br,
/
2. Results and discussion
The new alkynylcarbyne dicarbonyl complexes con-
taining bipyridine or 4,4?-dimethyl-2,2?-bipyridine and
trifluoroacetate as co-ligands were prepared by the
reaction sequence shown in the Scheme 1. Addition of
tridentate ligands, L3(CO)2MÅ
/
CÅ
/
CÃ
/
(t-Bu) (MꢀMo,
/
W), were described by Stone et al. [3]. The reactivity and
the electronic properties of these alkynylcarbyne com-
plexes were only marginally explored. Recently, we
reported on the synthesis of several trimethylsilyl- and
phenylethynylcarbyne complexes and on the influence of
various electron-donating tripodal co-ligands on the
spectroscopic properties of the new compounds [4].
When we extended our studies to alkynylcarbyne
Li[CÅ
metallates. Subsequent oxide abstraction with trifluoro-
acetic anhydride at ꢂ80 8C [5] afforded trans-alkynyl-
/
CÃ/R] to [M(CO)6] in THF or Et2O gave acyl
/
carbyne(tetracarbonyl)trifluoroacetato complexes which
were transformed into the alkynylcarbyne(dicarbonyl)
complexes 1a,bꢃ
dimethyl-2,2?-bipyridine, respectively.
The new compounds 1a,bꢃ7a,b are more stable than
/
7a,b by addition of bipyridine and 4,4?-
/
* Corresponding author. Tel.: ꢄ
88-3136.
E-mail address: helmut.fischer@uni-konstanz.de (H. Fischer).
/
49-7531-88-2783; fax: ꢄ49-7531-
/
those alkynylcarbyne(tetracarbonyl) complexes of tung-
sten previously mentioned and are even more stable
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 1 1 5 - 0

B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ
/23
17
Scheme 1.
than the complexes [L3(CO)2WÅ
/
CÃ
/
CÅ
/
CÃ
/
R] (L3ꢀ
30 8C, 1a,bꢃ
/
Tp,
tional n(CO) absorptions appear at lower wave numbers
ꢁ
ꢁ
Tp?, Cp; RꢀSiMe3, Ph, n-Bu) [3,4]. At ꢂ
/
/
/
(A1 and B1 ). With increasing concentration of 1a,bꢃ
/
ꢁ
ꢁ
7a,b can be stored under an inert gas atmosphere for
prolonged periods of time without noticeable decom-
position but they decompose in solution at room
7a,b the relative intensity of A1 and B1 n(CO) absorp-
tions increases and that of A1 and B1 bands simulta-
neously decreases. Conversely, diluting concentrated
temperature within about 2ꢃ
1a,bꢃ7a,b are insoluble in nonpolar solvents and only
moderately soluble in polar solvents.
The IR spectra of the complexes 1a,bꢃ
/
3 days. The complex
solutions of 1a,bꢃ
/
7a,b leads to a decrease of the relative
ꢁ
ꢁ
/
intensity of A1 and B1 and simultaneously to an increase
of the intensity of A1 and B1 n(CO) absorptions until
finally only the A1 and B1 absorptions are detectable.
Similar effect are observed when solutions of the trans-
chloro(dicarbonyl)(TMEDA)phenylethynylcarbyne
complex (8a) [4] in diethyl ether or of the bdmpza(di-
carbonyl)phenylethynylcarbyne complexes 9a in diethyl
ether and 10a [4] in THF are concentrated or diluted. In
all cases the additional bands are found at lower wave
numbers.
/7a,b in tetra-
hydrofuran exhibit an unusual behavior: the n(CO)
absorptions are concentration-dependent. The pattern
of two n(CO) absorptions of nearly equal intensity (A1
and B1) as expected for cis-dicarbonyl transition metal
complexes is observed only with very diluted solutions
(in most cases concentration B
/
0.01 mol lꢂ1). When the
concentration of the complexes is increased two addi-

18
B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ23
/
DB1, are within error limits independent of the metal
and of the substituent R, however, depend on the co-
ligand. All dimethyl bipyridine substituted complexes
(5a,bꢃ
corresponding bipyridine substituted complexes 1a,bꢃ
3a,b.
The second set of n(CO) absorptions is only observed
/
7a,b) exhibit smaller DA1 and DB1 values than the
/
when relatively high concentrations (with respect to the
solubility) are employed and when the IR spectra are
measured in solvents in which the complexes exhibit
only poor solubility. For example, solutions of the
complexes 8a and 9a in diethyl ether show four n(CO)
bands but only two in THF.
These observations indicate that the second set of
n(CO) absorptions is due to a reversible association of
complex molecules before nucleation and subsequent
precipitation. In concentrated solutions the molecules
presumably associate in a way similar to that observed
in the solid state. In accord with such an assumption
The change of the n(CO) absorptions when varying
the concentration is shown in Fig. 1 with the example of
[(CF3CO2)(bipy)(CO)2MoÅCÃCÅCÃPh] (2b).
In Fig. 2 these spectra are normalized to the same
amount of absorbing molecules. Two isosbestic points,
one at 2007 cmꢂ1 and one at 1927 cmꢂ1, are observed.
Obviously, the formation of a new species as indicated
by the additional bands is reversible and concentration-
dependent.
ꢁ
ꢁ
solutions exhibiting strong n(CO) A1 and B1 absorp-
/
/
/
/
tions also show light-scattering effects. From the posi-
ꢁ
ꢁ
tion of the A1 and B1 bands at lower wave numbers it
follows that the metal of the dimers are more electron-
rich than that of the monomers very likely caused by
intermolecular interaction of alkynylcarbyne ligands. In
concentrated solution, dimers or oligomers of 1a,bꢃ
and 8aꢃ10a are probably in equilibrium with their
monomers.
/7a,b
ꢁ
The positions of the additional bands A1 and B1 of
ꢁ
/
1a,bꢃ7a,b, 8a, 9a and 10a in general agree well with
/
those of the n(CO) absorptions in the solid state (KBr
pellets). All data are compiled in the Table 1.
The difference in the position of the A1 positions
ꢁ
The structures of 8a and 10a have previously been
established by X-ray structural analyses [4,6]. Complex
8a crystallizes with one equivalent of dichloromethane.
In the crystal of 8a dimeric units with a parallel head to
tail arrangement of the phenylethynylcarbyne fragments
(DA1ꢀ
/
A1ꢂ
/
A1) is significantly smaller than that in the
ꢁ
B1 positions (DB1ꢀ
/
B1ꢂ
/
B1 ). In general both, DA1 and
Fig. 1. IR spectra of various concentrations of 2b in THF [cꢀ
/
0.067 mol lꢂ1 (a), 0.042 mol lꢂ1 (b), 0.037 mol lꢂ1 (c), 0.03 mol lꢂ1 (d), 0.028 mol lꢂ1
(e), 0.020 mol lꢂ1 (f)].

B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ
/23
19
Fig. 2. IR spectra of various concentrations of 2b in THF normalized to the same amount of 2b [cꢀ
/
0.067 mol lꢂ1 (a), 0.042 mol lꢂ1 (b), 0.037 mol
lꢂ1 (c), 0.03 mol lꢂ1 (d), 0.028 mol lꢂ1 (e), 0.020 mol lꢂ1 (f)].
Complex 10a crystallizes with one equivalent of THF.
Again the alkynylcarbyne fragments arrange in a
parallel head-to-tail fashion. However, the separation
of the ‘dimers’ is less pronounced than in 8a.
Table 1
n(CO) absorptions of the complexes 1ꢃ
and 10a in THF, 8a and 9a in Et2O), and in KBr pellets
/
10 ( in cmꢂ1) in solution (1ꢃ
7
/
These crystal structures support the assumption that
dimeric units (and at higher concentration presumably
oligomeric units) are the source of the second set of
n(CO) absorptions. Assuming formation of dimers,
In solution
KBr pellet
ꢁ
A1
ꢁ
B1
A1
B1
A1
B1
1a
1b
2a
2b
3a
3b
4a
5a
5b
6a
6b
7a
7b
8a
9a
10a
2000
2014
1997
2010
1995
2009
1993
1998
2013
1995
2009
1994
2007
1993
1995
1992
1918
1937
1915
1934
1914
1933
1910
1916
1935
1913
1932
1912
1931
1909
1912
1910
1998
2010
1990
2002
1989
2001
1992
1998
2012
1995
2010
1901
1922
1895
1917
1894
1913
1893
1904
1925
1915
1939
1999
2014
1991
2004
1989
2003
1993
2000
2014
1992
2010
1990
2006
1985
1989
1982
1904
1925
1895
1917
1894
1915
1893
1904
1925
1902
1928
1908
1926
1895
1903
1906
equilibrium constants (Kꢀ
/
[dimer]/[monomer]2) for
some complexes could be estimated from the IR spectra:
Kꢀ27 (2a), 10 (2b), 28 (3a), and 36 (10a), all values
/
determined at 0.020 mol lꢂ1 ‘total’ concentration of
complexes.
Recently the pressure tuning of IR and Raman
spectra of some dicarbonyl carbyne complexes of the
type
[{Cl(CO)2(LÃ
/
L)WÅ
/
CC6H4Ã
/
(CÅ
/
CC6H4)nÃ
/
NÅ
/
C}2M] (Mꢀ
/
PdI2 or ReCl(CO)3, LÃ
/
Lꢀ
/
TMEDA,
DPPE) was reported by Xu et al. [7] and a pressure
induced phase-transition in the solid state of these
compounds was observed. In the solid state the
1981
1982
1983
1871
1893
1905
Cl(CO)2(TMEDA)W
[{Cl(CO)2(TMEDA)WÅ
group
of
the
C}2Re(CO)3]
complex
was
/
CC6H4NÅ
/
found to exhibit four instead of the expected two
n(CO) absorptions [7]. The appearance of multiple
absorptions was ascribed to the solid-state packing of
the molecules. However, to the best of our knowledge
the formation of dimers (and oligomers) in solution
when increasing the concentration and approaching
saturation concentration has not been observed before
in carbene and carbyne complex chemistry. Obviously,
this association is the first step in the formation of
crystals and in precipitation. The detection of associa-
are present (Fig. 3). The ‘dimers’ are separated by
dichloromethane molecules. Very likely in concentrated
solution similar dimers are reversibly formed giving rise
to the shift in the n(CO) absorptions. The extent of the
electronic interaction of both molecules is among other
factors determined by the distance within the ‘dimers’
thus readily explaining the smaller DA1 and DB1 values
of dimethyl bipyridine substituted complexes compared
with those of the bipyridine substituted complexes.

20
B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ23
/
Fig. 3. View along the crystallographic a (left) and b axis (right) of the crystal structure of complex 8a. The hydrogen atoms of 8a are omitted for
clarity. The ‘dimeric units’ separated by dichloromethane molecules from neighboring units are highlighted by a circle each.
tion was facilitated by the rather poor solubility of the
complexes 1ꢃ10. Other carbyne complexes such as
arylcarbyne complexes may exhibit similar effects,
however, the usually high solubility of these complexes
renders the detection of a similar association difficult.
Good candidates for a detection are those complexes
that incorporate solvent molecules into the solid state
1H-NMR, 13C-NMR: Bruker AC 250, Bruker DRX
600. Unless specifically mentioned, NMR spectra were
recorded at room temperature (r.t.) at 250 MHz (1H)
and 151 MHz (13C). Chemical shifts are reported in ppm
/
relative to the residual solvent peaks [CD3COCD3: dꢀ
2.04 (1H) and dꢀ29.8 (13C), CDCl3: dꢀ7.24 (1H) and
dꢀ
79.0 (13C)]. MS: Finnigan MAT 312 (EI) or
/
/
/
/
structure [8ꢃ
/
10].
Finnigan MAT 312/AMD5000 (FAB).
3. Experimental
3.2. General procedure for the synthesis of the complexes
(1a,bꢃ
/
7a,b)
3.1. General
At ꢂ
/
30 8C, 5.0 mmol of the respective acetylene
All operations were carried out under either nitrogen
or argon by using conventional Schlenk techniques.
Solvents were dried by refluxing over sodium-benzo-
phenone ketyl or CaH2 and were freshly distilled prior
to use. The silica gel used for chromatography (J.T.
Baker, silica gel for flash chromatography) was satu-
rated with argon. The yields refer to analytically pure
compounds and were not optimized. [Cl(tmeda)-
derivative (trimethylsilylacetylene, phenylacetylene, p-
tolylacetylene and t-butylacetylene) in 30 ml of Et2O
was lithiated with n-BuLi (15% solution in hexane).
After 0.5 h, 5.0 mmol of [M(CO)6] (MꢀW, Mo) and 5
/
ml of THF were added. The resulting suspension
immediately turned orange. When it was stirred for 1
h at r.t. a clear orange solution was formed. The
solution was cooled to ꢂ
(CF3CO)2O was added. Evolution of CO was observed.
At ꢂ50 8C, 5.0 mmol of 2,2?-bipyridine or 4,4?-
/
80 8C and 5.0 mmol of
(CO)2WÅ
/
CÃ
/
CÅ
/
CÃ
/
Ph], [(bdmpza)(CO)2WÅ
/
CÃ
/
CÅ
/
CÃ
/
Ph] and [(bdmpza)(CO)2WÅ
/
CÃCÅCÃSiMe3] were pre-
/
/
/
/
pared as described previously [4]. Trimethylsilylacety-
lene, p-tolylacetylene, 2,2?-bipyridine (Fluka), phenyl-
acetylene (Merck), n-butyllithium (Chemetall), tungsten
hexacarbonyl, trifluoroacetic anhydride, t-butylacety-
lene, and 4,4?-dimethyl-2,2?-bipyridine (Aldrich) were
commercial products and were used without further
purification. IR: FTIR spectrophotometer, Bio-Rad.
dimethyl-2,2?-bipyridine, respectively, was added. Then
solution was slowly warmed to r.t. CO evolution
gradually ceased and a red precipitate was formed. To
complete precipitation, pentane was added to the dark
red solution. The precipitate was decanted and
[M(CO)6] and [M(bipy)(CO)4] (Mꢀ
/
W, Mo) were
removed from the crude product by repeatedly washing

B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ
/23
21
with pentane and pentaneꢃ
orange to red product was then dried in vacuo.
/
CH2Cl2 (3:1). The resulting
N, 4.36. Calc. for C23H13F3N2O4W (622.2): C, 44.40; H,
2.11; N, 4.50%.
3.2.1. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(trimethylsilylpropynylidyne)tungsten (1a)
Yield: 2.19 g (71% relative to [W(CO)6]). Dec.
3.2.4. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(phenylpropynylidyne)molybdenum (2b)
Yield: 1.66 g (62% relative to [Mo(CO)6]). Dec.
ꢀ
/
194 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2057 vw, n(CO)
ꢀ
/
180 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2097 w, n(CO)
O) 1684 m. 1H-NMR
7.50 (m, 5H, Ph), 7.82 (dt,
2000 s, 1918 s, n(CÄ
(CD3C(O)CD3): dꢀ
5.1 Hz, 2H, C4-H), 8.45 (dt, Jꢀ
/
O) 1689 m. 1H-NMR
0.08 (s, 9H, SiMe3), 7.89 (t, Jꢀ
2010 s, 1934 s, n(CÄ
(CD3C(O)CD3): dꢀ7.25ꢃ
1.1 Hz, 2H, C3-H), 8.39 (dt, Jꢀ
/
3
/
/
/
/
3
4
4
3
/
6.6 Hz, Jꢀ
3.4 Hz, 2H, C3-H), 9.35 (d,
/0.6 Hz,
3Jꢀ
/
6.4 Hz, Jꢀ
/
/6.5
3
4
3
2H, C5-H), 8.78 (d, Jꢀ
3Jꢀ2.1 Hz, 2H, C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
0.4 (SiMe3), 76.6 (Cb), 120.7 (Ca), 124.6 (C3, bipy),
128.4 (C5, bipy), 142.2 (C4, bipy), 155.8 (C6, bipy),
156.3 (C2, bipy), 160.6 (q, CF3CO2), 225.0 (1J(WC)ꢀ
171 Hz, CO), 246.3 (WÅC). MS (EI): m/z (%)ꢀ590
(0.4) [MꢄꢂCO], 562 (1) [Mꢄꢂ2CO], 505 (0.4) [Mꢄꢂ
/
Hz, Jꢀ
C4-H), 9.25 (d, 3Jꢀ
(CD3C(O)CD3): dꢀ64.3 (Cb), 100.7 (C1, Ph), 121.2
/
1.4 Hz, 2H, C5-H), 8.72 (d, Jꢀ
/8.1 Hz, 2H,
/
/
/
4.1 Hz, 2H, C6-H). 13C-NMR
ꢂ
/
/
(Ca), 124.1 (C3, bipy), 127.5 (C5, bipy), 129.6, 130.4,
133.8 (Ph), 141.8 (C4, bipy), 155.3 (C6, bipy), 155.6 (C2,
/
/
/
bipy), 160.4 (q, CF3CO2), 226.4 (CO), 251.8 (MoÅ
MS (FAB, THF/NBA): m/z (%)ꢀ
480 (0.5) [Mꢄꢂ
2CO], 423 (0.7) [MꢄꢂCF3CO2], 367 (0.7) [Mꢄꢂ
CF3CO2ꢂ2CO], 154 (100) [C10H8N2ꢂ2]. Anal. Found:
/C).
/
/
/
/
/
CF3CO2], 156 (100) [C10H8N2]. Anal. Found: C, 38.33;
H, 2.94; N, 4.17. Calc. for C20H17F3N2O4SiW (618.3):
C, 38.85; H, 2.77; N, 4.53%.
/
/
/
/
C, 51.31; H, 2.58; N, 5.07. Calc. for C23H13F3MoN2O4
(534.3): C, 51.70; H, 2.45; N, 5.24%.
3.2.2. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(trimethylsilylpropynylidyne)molybdenum (1b)
Yield: 2.02 g (64% relative to [Mo(CO)6]). Dec.
3.2.5. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(p-tolylpropynylidyne)tungsten (3a)
Yield: 2.23 g (70% relative to [W(CO)6]). Dec.
ꢀ
/
156 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2050 w, n(CO)
O) 1685 m. 1H-NMR
2014 s, 1937 s, n(CÄ
(CD3C(O)CD3): dꢀ
6.5 Hz, Jꢀ
4Jꢀ
1.6 Hz, 2H, C5-H), 8.70 (dd, Jꢀ
Hz, 2H, C3-H), 9.21 (dd, Jꢀ
C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
/
ꢀ
/
166 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2091 w, n(CO)
O) 1687 m. 1H-NMR
2.29 (s, 3H, C6H4-Me-p), 7.05ꢃ
3
/
0.09 (s, 9H, SiMe3), 7.82 (dt, Jꢀ
1.2 Hz, 2H, C4-H), 8.38 (dt, Jꢀ
/
1995 s, 1914 s, n(CÄ
(CD3C(O)CD3): dꢀ
7.35 (m, 4H, C6H4-Me-p), 7.90 (dt, Jꢀ
4
/
4
3
/
/
7.5 Hz,
/
/
3
4
3
4
/
/
8.2 Hz, Jꢀ
/
0.9
0.8 Hz, 2H,
0.4 (SiMe3),
/
6.5 Hz, Jꢀ
/
3
4
3
/
4.5 Hz, Jꢀ
/
1.1 Hz, 2H, C3-H), 8.46 (dt, Jꢀ
/
7.9 Hz, Jꢀ
8.3 Hz, 2H, C4-H), 9.38 (d,
5.5 Hz, 2H, C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
/1.4 Hz,
3
/
ꢂ
/
2H, C5-H), 8.80 (d, Jꢀ
/
72.4 (Cb), 113.7 (Ca), 124.2 (C3, bipy), 127.5 (C5, bipy),
141.8 (C4, bipy), 155.3 (C6, bipy), 155.5 (C2, bipy),
3Jꢀ
/
/
21.5 (C6H4-Me-p), 68.9 (Cb), 106.9 (C1, C6H4-Me-p),
160.8 (q, CF3CO2), 226.1 (CO), 253.5 (MoÅ
(FAB, THF/NBA): m/z (%)ꢀ 2CO], 419
476 (7) [Mꢄꢂ
(11) [MꢄꢂCF3CO2], 363 (9) [Mꢄꢂ
CF3CO2ꢂ2CO].
Anal. Found: C, 45.31; H, 3.49; N, 5.16. Calc. for
C20H17F3N2MoO4Si (530.4): C, 45.29; H, 3.23; N,
5.28%.
/
C). MS
118.9 (Ca), 124.6 (C3, bipy), 128.3 (C5, bipy), 130.3,
133.3, 140.3 (C6H4-Me-p), 142.1 (C4, bipy), 155.8 (C6,
/
/
2
/
/
/
bipy), 156.3 (C2, bipy), 160.7 (q, Jꢀ
/
35 Hz, CF3CO2),
C). MS (FAB,
CF3CO2], 467 (1)
2CO]. Anal. Found: C, 45.52; H, 2.60;
225.3 (1J(WC)ꢀ
THF/NBA): m/z (%)ꢀ
[Mꢄꢂ
CF3CO2ꢂ
/
170 Hz, CO), 244.6 (WÅ
/
/
523 (1) [Mꢄꢂ
/
/
/
N, 3.72. Calc. for C24H15F3N2O4W (636.0): C, 45.31; H,
2.38; N, 4.40%.
3.2.3. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(phenylpropynylidyne)tungsten (2a)
Yield: 1.90 g (61% relative to [W(CO)6]). Dec.
3.2.6. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(p-tolylpropynylidyne)molybdenum (3b)
Yield: 1.51 g (55% relative to [Mo(CO)6]). Dec.
ꢀ
/
183 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2102 w, n(CO)
O) 1688 m. 1H-NMR
7.45 (m, 5H, Ph), 7.90 (dt,
1997 s, 1915 s, n(CÄ
(CD3C(O)CD3): dꢀ7.30ꢃ
1.0 Hz, 2H, C3-H), 8.49 (dt, Jꢀ
/
/
/
ꢀ
/
143 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2110 w; 2084 w,
O) 1703 m. 1H-NMR
2.30 (s, 3H, C6H4-Me-p), 7.10ꢃ
3Jꢀ
/
4.9 Hz, Jꢀ
/
/
6.2
n(CO) 2009 s, 1933 s, n(CÄ
(CD3C(O)CD3): dꢀ
7.40 (m, 4H, C6H4-Me-p), 7.83 (dt, Jꢀ
/
4
3
4
3
Hz, Jꢀ
C4-H), 9.38 (d, 3Jꢀ
(CD3C(O)CD3): dꢀ
/
1.6 Hz, 2H, C5-H), 8.80 (d, Jꢀ
/
8.0 Hz, 2H,
5.5 Hz, 2H, C6-H). 13C-NMR
/
/
3
4
/
/
6.4 Hz, Jꢀ
/
3
4
/
68.5 (Cb), 107.1 (C1, Ph), 122.1
1.0 Hz, 2H, C3-H), 8.39 (dt, Jꢀ
/
7.9 Hz, Jꢀ
8.0 Hz, 2H, C4-H), 9.24 (dd,
1.8 Hz, 2H, C6-H). 13C-NMR
(CD3C(O)CD3): dꢀ21.5 (C6H4-Me-p), 64.6 (Cb),
/1.7 Hz,
3
(Ca), 124.6 (C3, bipy), 128.3 (C5, bipy), 129.5, 129.8,
133.2 (Ph), 142.1 (C4, bipy), 155.8 (C6, bipy), 156.3 (C2,
2H, C5-H), 8.72 (d, Jꢀ
/
3Jꢀ5.7 Hz, 4Jꢀ
/
/
bipy), 160.8 (q, CF3CO2), 225.2 (1J(WC)ꢀ
/170 Hz,
/
CO), 244.1 (WÅ
509 (1) [MꢄꢂCF3CO2], 453 (1) [Mꢄꢂ
154 (100) [C10H8N2ꢂ
/
C). MS (FAB, THF/NBA): m/z (%)ꢀ
/
100.6 (C1, C6H4-Me-p), 118.0 (Ca), 124.2 (C3, bipy),
127.5 (C5, bipy), 130.3, 133.8, 141.1 (C6H4-Me-p), 141.8
(C4, bipy), 155.3 (C6, bipy), 155.6 (C2, bipy), 226.5
/
/
CF3CO2ꢂ
/
2CO],
/2]. Anal. Found: C, 43.92; H, 2.25;

22
B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ23
/
(CO), 252.2 (MoÅ
/
C). MS (FAB, THF/NBA): m/z
Hz, CF3CO2), 226.3 (CO), 253.1 MoÅ
THF/NBA): m/z (%)ꢀ
504 (4) [Mꢄꢂ
[MꢄꢂCF3CO2], 391 (17) [Mꢄꢂ
CF3CO2ꢂ
(40) [C12H12N2ꢄH], 73 (76) [SiMe3]. Anal. Found: C,
/
C). MS (FAB,
2CO], 447 (8)
2CO], 185
(%)ꢀ
/
494 (1) [Mꢄꢂ
/
2CO], 435 (2) [Mꢄꢂ
/CF3CO2].
/
/
Anal. Found: C, 52.48; H, 2.92; N, 4.97. Calc. for
C24H15F3MoN2O4 (548.3): C, 52.57; H, 2.76; N, 5.11%.
/
/
/
/
47.09; H, 3.75; N, 4.91. Calc. for C22H21F3N2O4SiW
(558.4): C, 47.32; H, 3.79; N, 5.02%.
3.2.7. 2,2?-Bipyridyl(dicarbonyl)(trifluoroacetato)-
(t-butylpropynylidyne)tungsten (4a)
Yield: 2.38 g (79% relative to [W(CO)6]). Dec.
3.2.10. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)-
(trifluoroacetato)(phenylpropynylidyne)tungsten (6a)
Yield: 1.79 g (55% relative to [W(CO)6]). Dec.
ꢀ
/
214 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2133 w, n(CO)
O) 1690 m. 1H-NMR
1993 s, 1910 s, n(CÄ
(CD3C(O)CD3): dꢀ
5.5 Hz, Jꢀ
4Jꢀ
1.7 Hz, 2H, C5-H), 8.76 (dd, Jꢀ
Hz, 2H, C4-H), 9.32 (dd, Jꢀ
C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
/
3
/
1.13 (s, 9H, CMe3), 7.87 (dt, Jꢀ
1.2 Hz, 2H, C3-H), 8.43 (dt, Jꢀ
/
ꢀ
n(CÄ
/
162 8C. IR (THF, cmꢂ1): n(CO) 1995 s, 1913 s,
4
3
1
/
/
8.6 Hz,
/
O) 1704 m. H-NMR (CD3C(O)CD3): dꢀ
/
2.65 (s,
3
4
3
/
/
8.6 Hz, Jꢀ
/
1.2
0.8 Hz, 2H,
30.6 (CMe3),
6H, C4-Me), 7.25ꢃ
Hz, 2H, C5-H), 8.64 (s, 2H, C3-H), 9.18 (d, 3Jꢀ
2H, C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
/
7.45 (m, 5H, Ph), 7.69 (d, Jꢀ
/5.3
3
4
/
4.6 Hz, Jꢀ
/
/5.6 Hz,
/
/21.2 (C4-
1
81.7 (Ca), 98.1 (Cb), 124.5 (C3, bipy), 128.2 (C5, bipy),
142.0 (C4, bipy), 155.6 (C6, bipy), 156.3 (C2, bipy),
Me), 67.9 (Cb), 106.6 (C1, Ph), 116.0 (q, Jꢀ290 Hz,
/
CF3CO2), 121.7 (Ca), 124.5 (C3, bipy), 128.3 (C5, bipy),
129.0, 129.2, 132.8 (Ph), 154.3 (C4, bipy), 154.6 (C6,
225.3 (CO), 247.8 (WÅ
(%)ꢀ
489 (1) [Mꢄꢂ
CF3CO2ꢂ2CO]. Anal. Found: C, 41.75; H, 3.02; N,
/
C). MS (FAB, THF/NBA): m/z
2
/
/
CF3CO2], 433 (1) [Mꢄꢂ
/
bipy), 155.6 (C2, bipy), 160.1 (q, Jꢀ
/
36 Hz, CF3CO2),
C). MS (FAB,
622 (1) [Mꢄꢂ
CO], 594 (3)
2CO], 537 (5) [Mꢄꢂ
CF3CO2ꢂ2CO], 185 (100) [C12H12N2ꢄ
/
225.0 (1J(WC)ꢀ
THF/NBA): m/z (%)ꢀ
[Mꢄꢂ
/
170 Hz, CO), 243.4 (WÅ
/
4.15. Calc. for C21H17F3N2O4W (602.2): C, 41.88; H,
2.85; N, 4.65%.
/
/
/
/
CF3CO2], 481 (4) [Mꢄꢂ
/
/
/1]. Anal.
3.2.8. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)-
(trifluoroacetato)(trimethylsilylpropynylidyne)Ã
tungsten (5a)
Yield: 2.65 g (82% relative to [W(CO)6]). Dec.
Found: C, 45.37; H, 3.06; N, 3.94. Calc. for
C25H17F3N2O4W (650.3): C, 46.18; H, 2.64; N, 4.31%.
/
3.2.11. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)(tri-
fluoroacetato)(phenylpropynylidyne)molybdenum (6b)
Yield: 2.05 g (73% relative to [Mo(CO)6]). Dec.
ꢀ
/
201 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2055 w, n(CO)
O) 1694 m. 1H-NMR
0.07 (s, 9H, SiMe3), 2.64 (s, 6H,
1998 s, 1916 s, n(CÄ
(CD3C(O)CD3): dꢀ
C4-Me), 7.68 (d, Jꢀ
C3-H), 9.14 (d, 3Jꢀ
(CD3C(O)CD3): dꢀ
/
/
ꢀ
/
135 8C. IR (THF, cmꢂ1): n(CÅ
2009 s, 1932 s, n(CÄ
(CD3C(O)CD3): dꢀ
/
C) 2096 w, n(CO)
3
/
5.3 Hz, 2H, C5-H), 8.62 (s, 2H,
5.6 Hz, 2H, C6-H). 13C-NMR
/
O) 1699 m. 1H-NMR
/
/
2.62 (s, 6H, C4-Me), 7.25ꢃ
/
7.50
5.4 Hz, 2H, C5-H), 8.55 (s,
5.5 Hz, 2H, C6-H). 13C-NMR
3
/1.9 (SiMe3), 21.6 (C4-Me), 76.3
(m, 5H, Ph), 7.63 (d, Jꢀ
2H, C3-H), 9.04 (d, Jꢀ
/
3
(Cb), 120.7 (Ca), 125.1 (C3, bipy), 128.8 (C5, bipy), 155.3
/
(C4, bipy), 155.5 (C6, bipy), 156.0 (C2, bipy), 160.6 (q,
(CD3C(O)CD3, 62.9 MHz): dꢀ21.5 (C4-Me), 64.1 (Cb),
/
2J(CF)ꢀ
CO), 245.9 (1J(WC)ꢀ
CH2Cl2/NBA): m/z (%)ꢀ
(36) [MꢄꢂCF3CO2], 477 (17) [Mꢄꢂ
185 (100) [C12H12N2ꢄH]. Anal. Found: C, 40.38; H,
/
36 Hz, CF3CO2), 225.2 (1J(WC)ꢀ
/
134 Hz,
C). MS (FAB,
590 (4) [Mꢄꢂ
2CO], 533
CF3CO2ꢂ2CO],
100.7 (C1, Ph), 119.2 (Ca), 124.7 (C3, bipy), 128.1 (C5,
bipy), 129.6, 130.3, 133.7 (Ph), 154.2 (C4, bipy), 154.6
/
197 Hz, WÅ
/
/
/
(C6, bipy), 155.4 (C2, bipy), 160.9 (q, 2Jꢀ
/
35 Hz,
C). MS (FAB,
508 (10) [Mꢄꢂ
2CO], 451 (12)
CF3CO2], 395 (17) [Mꢄꢂ
CF3CO2ꢂ2CO], 185
(88) [C12H12N2ꢂ1], 78 (60) [SiMe3ꢄ1]. Anal. Found: C,
/
/
/
CF3CO2), 226.6 (CO), 251.3 (MoÅ
THF/NBA): m/z (%)ꢀ
[Mꢄꢂ
/
/
/
/
3.28; N, 4.04. Calc. for C22H21F3N2O4SiW (646.4): C,
40.88; H, 3.27; N, 4.33%.
/
/
/
/
/
53.16; H, 3.25; N, 4.73. Calc. for C25H17F3MoN2O4
(562.4): C, 53.40; H, 3.05; N, 4.98%.
3.2.9. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)-
(trifluoroacetato)(trimethylsilylpropynylidyne)Ã
/
molybdenum (5b)
Yield: 1.87 g (67% relative to [Mo(CO)6]). Dec.
3.2.12. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)-
(trifluoroacetato)(p-tolylpropynylidyne)tungsten (7a)
Yield: 2.23 g (67% relative to [W(CO)6]). Dec.
ꢀ
/
163 8C. IR (THF, cmꢂ1): n(CÅ
/
C) 2050 w, n(CO)
O) 1706 m. 1H-NMR
0.09 (s, 9H, SiMe3), 2.62 (s, 6H,
2013 s, 1935 s, n(CÄ
(CD3C(O)CD3): dꢀ
/
ꢀ
n(CÄ
/
173 8C. IR (THF, cmꢂ1): n(CO) 1994 s, 1912 s,
1
/
/
O) 1708 m. H-NMR (CD3C(O)CD3): dꢀ
/
2.28 (s,
7.30 (m, 5H,
3
C4-Me), 7.62 (d, Jꢀ
C3-H), 9.01 (d, 3Jꢀ
(CD3C(O)CD3): dꢀ
(Cb), 113.6 (Ca), 116.1 (q, J(CF)ꢀ
124.6 (C3, bipy), 128.0 (C5, bipy), 154.2 (C4, bipy),
154.6 (C6, bipy), 155.3 (C2, bipy), 161.1 (q, 2J(CF)ꢀ
38
/
5.2 Hz, 2H, C5-H), 8.55 (s, 2H,
3H, C4H6-Me-p), 2.65 (s, 6H, C4Me), 7.05ꢃ
C6H4-Me-p), 7.69 (d, Jꢀ
2H, C3-H), 9.17 (d, Jꢀ
(CD3C(O)CD3): dꢀ21.5 (C4Me), 21.6 (C6H4-Me), 68.8
(Cb), 106.9 (C1, C6H4-Me-p), 117.2 (q, 1Jꢀ
290 Hz,
CF3CO2), 119.0 (Ca), 125.0 (C3, bipy), 128.8 (C5, bipy);
/
3
/
5.5 Hz, 2H, C6-H). 13C-NMR
/
4.2 Hz, 2H, C5-H), 8.63 (s,
3
/
ꢂ
/
0.5 (SiMe3), 21.4 (C4-Me), 72.1
/
5.7 Hz, 2H, C6-H). 13C-NMR
1
/292 Hz, CF3CO2),
/
/
/

B. Schwenzer, H. Fischer / Journal of Organometallic Chemistry 667 (2003) 16ꢃ
/23
23
130.2, 133.2, 140.2 (C6H4-Me-p), 154.7 (C4, bipy), 155.0
(C6, bipy), 156.1 (C2, bipy), 160.7 (q, 2Jꢀ
36 Hz,
CF3CO2), 225.6 (1J(WC)ꢀ
170 Hz, CO), 244.3
(1J(WC)ꢀ
198 Hz, WÅC). MS (FAB, THF/NBA): m/
z (%)ꢀ 2CO], 551 (5)
636 (2) [MꢄꢂCO], 608 (2) [Mꢄꢂ
[MꢄꢂCF3CO2], 495 (4) [Mꢄꢂ
CF3CO2ꢂ2CO], 185
(45) [C12H12N2ꢄ1]. Anal. Found: C, 47.21; H, 2.65; N,
absorptions were analyzed using the computer program
‘
/
PEAKFIT’ (Jandel Scientific). The intensity of the B1 and
ꢁ
/
B1 absorption thus obtained was used in the calculation
of the equilibrium constants K. The initial formation of
/
/
/
/
/
dimers was assumed: (Kꢀ
[dimer]/[monomer]2).
/
/
/
/
/
4.48. C26H19F3N2O4W (664.3): C, 47.01; H, 2.88; N,
4.22%.
Acknowledgements
Support of these investigations by the Fonds der
Chemischen Industrie is gratefully acknowledged.
3.2.13. Dicarbonyl(4,4?-dimethyl-2,2?-bipyridyl)(tri-
fluoroacetato)(p-tolylpropynylidyne)molybdenum (7b)
Yield: 1.79 g (62% relative to [Mo(CO)6]). Dec.
ꢀ
/
156 8C. IR (THF, cmꢂ1): n(CÅ
vw, n(CO) 2007 s, 1931 s, n(CÄ
(CD3C(O)CD3): dꢀ2.30 (s, 3H, C4H6-Me-p), 2.62 (s,
6H, C4Me), 7.05ꢃ7.35 (m, 5H, C6H4-Me-p), 7.63 (d,
3Jꢀ
5.2 Hz, 2H, C5-H), 8.56 (s, 2H, C3-H), 9.04 (d,
3Jꢀ5.6 Hz, 2H, C6-H). 13C-NMR (CD3C(O)CD3): dꢀ
21.5 (C4Me), 21.5 (C6H4-Me-p), 64.5 (Cb), 100.6 (C1,
C6H4-Me-p), 116.9 (q, 1Jꢀ
290 Hz, CF3CO2), 118.1
/
C) 2110 vw, 2083
1
/
O) 1700 m. H-NMR
References
/
/
[1] (a) E.O. Fischer, G. Kreis, C.G. Kreiter, J. Muller, G. Huttner, H.
¨
Lorenz, Angew. Chem. 85 (1973) 618;
/
/
/
(b) E.O. Fischer, G. Kreis, C.G. Kreiter, J. Muller, G. Huttner, H.
¨
Lorenz, Angew. Chem. Int. Ed. Engl. 12 (1973) 564.
[2] E.O. Fischer, H.J. Kalder, F.H. Kohler, J. Organomet. Chem. 81
¨
(1974) C23.
/
(Ca), 124.7 (C3, bipy), 128.0 (C5, bipy), 130.3, 133.7,
141.0 (C6H4-Me-p), 154.2 (C4, bipy), 154.6 (C6, bipy),
[3] (a) I.J. Hart, A.F. Hill, F.G.A. Stone, J. Chem. Soc. Dalton
Trans. (1989) 2261.;
2
155.4 (C2, bipy), 160.8 (q, Jꢀ/35 Hz, CF3CO2), 226.7
(b) S.J. Dossett, I.J. Hart, F.G.A. Stone, J. Chem. Soc. Dalton
Trans. (1990) 3481.
(CO), 251.8 (MoÅ
(%)ꢀ
522 (2) [Mꢄꢂ
409 (3) [Mꢄꢂ
CF3CO2ꢂ
/
C). MS (FAB, THF/NBA): m/z
2CO], 465 (3) [Mꢄꢂ
CF3CO2],
2CO]. Anal. Found: C, 52.28;
[4] B. Schwenzer, J. Schleu, N. Burzlaff, C. Karl, H. Fischer, J.
Organomet. Chem. 641 (2002) 134.
/
/
/
/
/
[5] A. Mayr, G.A. McDermott, A.M. Dorries, Organometallics 4
(1985) 608.
H, 3.43; N, 4.41. Calc. for C26H19F3MoN2O4 (576.4): C,
54.18; H, 3.32; N, 4.86%.
[6] Crystallographic data for 8a and 10a may be obtained free of
charge from the Cambridge Crystallographic Data Centre, CCDC
nos. 166389 (8a) and 166390 (10a) [The Director, CCDC, 12
3.3. Determination of equilibrium constants
Union Road, Cambridge CB2 1EZ, UK (Fax: ꢄ
/
44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk)].
Solutions obtained by dissolving the appropriate
0.27
mmol) in 0.5 ml of THF were stepwise diluted with
THF. The amount of complex depended on the solubi-
lity in THF. The concentration of each solution was
calculated and an IR spectrum taken. Partially over-
[7] Z. Xu, A. Mayr, I.S. Butler, J. Organomet. Chem. 648 (2002) 93ꢃ
/
amount of the complexes (0.03ꢃ
/
0.12 g, 0.05ꢃ
/
98.
[8] M. Pui Yin Yu, A. Mayr, K.-K. Cheung, J. Chem. Soc. Dalton
Trans. (1998) 475.
[9] E.O. Fischer, W. Roll, N. Hoa Tran Huy, K. Ackermann, Chem.
¨
Ber. 115 (1982) 2951.
[10] F.-W. Lee, M.C.-W. Chan, K.-K. Cheung, C.-M. Che, J.
Organomet. Chem. 563 (1998) 191.
ꢁ
lapping absorptions of A1 and A1 (B1 and B1 ) n(CO)
ꢁ