Syntheses of halogenated ethenyl isocyanide chromium complexes as organometallic precursor molecules for ethenyl and ethynyl isocyanides

Article abstract of DOI:10.1002/1521-3765(20010216)7:4<881::AID-CHEM881>3.0.CO;2-2

The radical alkylation of tetraethylammonium pentacarbonyl(cyano) chromate 1 yielded the halogenated ethyl isocyanide complexes [(CO)₅Cr-(CN-CCIX-CCIYF)] 3 (a. X=Cl, Y= F; b. X=F. Y=F and c. X=Y=Cl). Dehalogenation of 3 using zinc in diethyl ether gave [(CO)₅Cr(CN-CX=CFY)] 4. The compounds 4a, b reacted with various nucleophiles exclusively at the difluoromethylene group. The unstable phosphorane 5, which is formed on reaction of 4b with trimethylphosphane, decomposed thermally and on hydrolysis yielding pentacarbonyl(1,2-difluoroethenyl isocyanide)chromium (6). The cyano substituent can be introduced in the β position of the isocyanide function by reaction of 4a. b with potassium cyanide, leading to the formation of [(CO)₅Cr(CN-CX=CF-CN)] (7). Reactions of 4a, b with organolithium or organomagnesium compounds yielded [(CO)₅Cr(CN-CX=CF-R)] (8) and [(CO)₅Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)₅] (10). The trimethylsilyl group in 8a, b, d could be removed by a solution of potassium carbonate in methanol leading to [(CO)₅Cr(CN-CX=CF-C_n-H)] (11) (n=2, 4). Octacarbonyldicobalt reacted with 8e under coordination of the C-C triple bond to the hexacarbonyldicobalt fragment, resulting in the cluster compound 12. The crystal and molecular structure of 8i, 11a, b, and 12 were elucidated by X-ray crystallography. The alkenyl and alkynyl isocyanides CN-CCl=CF₂ (13a). CN-CF=CF₂ (13b). CN-CCl=CCIF (13c), CN-CF=CFH (14), CN-CC-H (15), CN-CC-CN (16), and CN-CCl=CF-CN (17) were obtained by flash vacuum pyrolysis of 4a, 4b, 4c, 6, and 7a, respectively.

Full text of DOI:10.1002/1521-3765(20010216)7:4<881::AID-CHEM881>3.0.CO;2-2

FULL PAPER
Syntheses of Halogenated Ethenyl Isocyanide Chromium Complexes as
Organometallic Precursor Molecules for Ethenyl and Ethynyl Isocyanides
Marco Balbo-Block, Christoph Bartel, Dieter Lentz,* and Dagmar Preugschat[a]
ˆ
Abstract: The radical alkylation of tet-
raethylammonium pentacarbonyl(cya-
no)chromate 1 yielded the halogenated
ethyl isocyanide complexes [(CO)5Cr-
(CN CClX CClYF)] 3 (a, X ˆ Cl, Yˆ
F; b , X ˆ F, Y ˆ F and c, X ˆ Yˆ Cl).
Dehalogenation of 3 using zinc in dieth-
the b position of the isocyanide function
by reaction of 4a, b with potassium
cyanide, leading to the formation of
CX CF Cn H)] (11) (n ˆ 2, 4). Octa-
carbonyldicobalt reacted with 8e under
coordination of the C C triple bond to
the hexacarbonyldicobalt fragment, re-
sulting in the cluster compound 12. The
crystal and molecular structure of 8i,
11a, b, and 12 were elucidated by X-ray
crystallography. The alkenyl and alkynyl
ˆ
[(CO)5Cr(CN CX CF CN)] (7). Reac-
tions of 4a, b with organolithium or
organomagnesium compounds yielded
ˆ
[(CO)5Cr(CN CX CF R)] (8) and
ˆ
ˆ
ꢀ
ˆ
yl ether gave [(CO)5Cr(CN CX CFY)]
[(CO)5Cr(CN CF CF C C CF CF
NC)Cr(CO)5] (10). The trimethylsilyl
group in 8a, b, d could be removed by
a solution of potassium carbonate in
methanol leading to [(CO)5Cr(CN
ˆ
4. The compounds 4a, b reacted with
various nucleophiles exclusively at the
difluoromethylene group. The unstable
phosphorane 5, which is formed on
reaction of 4b with trimethylphosphane,
decomposed thermally and on hydroly-
sis yielding pentacarbonyl(1,2-difluoro-
ethenyl isocyanide)chromium (6). The
cyano substituent can be introduced in
isocyanides CN CCl CF2 (13a), CN
ˆ
ˆ
CF CF2 (13b), CN CCl CClF (13c),
ˆ
CN CF CFH (14), CN CC H (15),
ˆ
CN CC CN (16), and CN CCl CF
CN (17) were obtained by flash vacuum
pyrolysis of 4a, 4b, 4c, 6, and 7a,
respectively.
Keywords: alkenes ´ alkynes ´ chro-
mium ´ isocyanides ´ interstellar mol-
ecules
[7]
ˆ
[(CO)5Cr(CN CCl CCl(H)]. Shortly after the rotational
constants of this molecule were published, Kawaguchi et al.
Introduction
Ethenyl isocyanide was prepared by Matteson and Bailey[1]
almost 100 years after the synthesis of the first isocyanides,
ethyl isocyanide by Gautier[2] and phenyl isocyanide by
Hofmann.[3] The first fluorinated ethenyl isoycanide,
succeeded in detecting H C C NC in TMC-1 (taurus
ꢀ
molecular cloud) by radioastronomy.[8] H C C NC has been
ꢀ
subsequently studied by HeI and HeII photoelectron spec-
troscopy,[9] millimeter-wave spectroscopy,[10] high-resolution
FTIR spectroscopy,[11] and NMR spectroscopy.[12] Recently
[4]
ˆ
F2C CF NC, was synthesized in 1992 and its structure was
ꢀ
recently elucidated by low-temperature X-ray crystallogra-
phy.[5] Fehlhammer et al. reported on chloroethenyl isocya-
nides synthesized and stabilized by a pentacarbonylchromium
fragment in 1989.[6] Nevertheless, methods for the synthesis of
halogenated ethenyl isocyanides are still rare.
the very unstable CN C C CN molecule which had only
been obtained before in an argon matrix and characterized by
IR spectroscopy[13] was synthesized, and a broad study has
been performed by a collaborative effort.[14] Propynyl iso-
cyanide is the only other alkynyl isocyanide which has been
obtained thus far in preparative quantities and studied by
various spectroscopic methods.[12, 15] Recently, Thaddeus et al.
In 1991 we reported on the preparation, microwave
spectroscopic study, and structure of the the first alkynyl
ꢀ
ꢀ
isocyanide, ethynyl isocyanide, H C C NC, by vacuum
pyrolysis of a suitable organometallic precursor molecule,
succeeded in generating H (C C)n NC (n ˆ 2,3) (approxi-
mately 0.1 to 1 picomole) along with large amounts of other
compounds by electrical discharge in a molecular beam of
butadiyne, propynenitrile, or others seeded in Ne.[16, 17] The
detection of the isocyanopolyyne molecules was based solely
on Fourier transform microwave spectroscopy in combination
with ab initio calculations. Fehlhammer et al. successfully
[a] Priv.-Doz. Dr. D. Lentz, M. Balbo-Block, Dr. C. Bartel,
Dr. D. Preugschat
Fachbereich Chemie
Institut für Chemie - Anorganische und Analytische Chemie
Freie Universität Berlin
Fabeckstrasse 34 ± 36, 14195 Berlin (Germany)
Fax : (‡49)30-83852424
ꢀ
ꢀ
synthesized and stabilized H C C NC, Me3Si C C NC,
and C6H5 C C NC in a transition metal complex. How-
ever, no attempt has been made to obtain the free isocyanides.
[18]
ꢀ
E-mail: lentz@chemie.fu-berlin.de
Chem. Eur. J. 2001, 7, No. 4
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881

D. Lentz et al.
FULL PAPER
Thus far all methods for the preparation of halogenated
alkenyl isocyanides were based on the radical halogenation of
tetraethylammonium(pentacarbonyl)chromate in a suitable
halogenated alkane. This method requires suitable halogen-
ated alkanes and therefore is limited to molecules with a
relatively short chain length. Consequently only a few alkenyl
and alkynyl isocyanides could be prepared by pyrolysis of (1,2-
dichloroalkenyl isocyanide)(pentacarbonyl)chromium com-
plexes. Although Fehlhammerꢁs method for the synthesis of
metal complex stabilized alkynyl isocyanides is promising it
has been demonstrated on three examples only and was not
a metal complex framework as outlined in Scheme 2. The
pentacarbonyl chromium fragment fulfils several purposes:
1) It allows the synthesis of the halogenated pentacarbonyl-
(isocyanide)chromium complexes based on the radical
alkylation of pentacarbonyl(cyano)chromate discovered
by Fehlhammer et al.[24]
ꢀ
successful in an attempt to synthesize [(CO)5Cr(CN C C
[19]
tBu)][18] or [(CO)5Cr(CN C C CF3)].
Furthermore, it
ꢀ
requires alkynyl(phenyl)iodonium salts which are not gener-
ally available.[20]
Recently, we observed that pentacarbonyl(trifluoroethenyl
isocyanide)chromium behaves like a fluoroalkene. For exam-
ple, it dimerizes on heating leading to a four-membered
ring.[21] Highly fluorinated alkenes are very electrophilic
systems. Therefore they can be easily attacked by nucleo-
philes resulting in an intermediate carbanion which can
undergo further reactions to the final products.[22] In principle
there are several different possibilities for nucleophilic attack
on pentacarbonyl(trifluoroethenyl isocyanide)chromium (see
Scheme 1) such as at the carbonyl or isocyanide carbon atoms,
Scheme 2. The synthesis of halogenated ethenyl isocyanides on a metal
complex framework.
2) It serves as a protecting group stabilising the halogenated
isocyanides which otherwise tend to polymerize even at
low temperatures,[25] making it possible to modify the
organic moiety.
3) It serves for the dehalogenation of the alkenyl isocyanide
during the pyrolysis.
Reaction of tetraethylammonium(pentacarbonyl)(cyano)-
chromate 1 with phenyldiazonium tetrafluoroborate in the
solvents 1,2,2-trichloro-1,1-difluoroethane (2a), 1,2-dichloro-
1,1,2-trifluoroethane (2b), and 1,1,2,2-tetrachloro-1-fluoro-
ethane (2c) yields the perhalogenated ethyl isocyanide
complexes 3 (Scheme 2) which can be converted to the
corresponding ethenyl isocyanide complexes 4 by dehaloge-
nation using zinc.
As very electrophilic systems highly fluorinated alkenes can
be easily attacked by nucleophiles.[22] On the other hand
carbonyl and isocyanide complexes have other electrophilic
centers such as the carbonyl and isocyanide carbon atoms and
the metal center which might give raise to by-products as
outlined in Scheme 1.
The nucleophilic attack on the complexes 4 occurs exclu-
sively at the difluoromethylene group in the b position to the
isocyanide nitrogen atom. No by-products from the other
possible reaction channels were observed so far, although
pentacarbonyl(trifluoromethyl isocyanide)chromium is read-
ily attacked by nucleophiles resulting in the formation of
carbene complexes.[26]
Scheme 1. Different possible sites for nucleophilic attack on pentacarbo-
nyl(trifluoroethenyl isocyanide)chromium and their outcome.
which would lead to carbene complexes,[23] or at the metal
atom, which would give substitution products. In a recent
communication[14] we have shown that the nucleophilic attack
occurs solely at the CF2 group of pentacarbonyl(trifluoro-
ethenyl isocyanide)chromium and related compounds, which
allows a systematic variation of the substituent in the b
position to the isocyano group. In continuation of our work on
alkynyl isocyanides as molecules of radioastronomical inter-
est, we report herein in detail on the synthesis and structure
determination of halogenated alkenyl isocyanide complexes
as organometallic precursor molecules for the synthesis of
alkenyl and alkynyl isocyanides.
Reaction of 4b with trimethylphosphane results in the
formation of a thermally unstable phosphorane 5 via nucle-
ophilic attack of the b-carbon atom followed by fluoride
migration to the phosphorus center (Scheme 3). Similar to the
Results and Discussion
Our synthetic strategy based on the systematic modification
of halogenated ethenyl isocyanides requires their synthesis on
882
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Chem. Eur. J. 2001, 7, No. 4

Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
Several organic substituents could be introduced in the b
position to the isocyanide nitrogen atom (Scheme 5) in
complexes 8 by using various organolithium or -magnesium
compounds as nucleophiles. The organic substituents range
Scheme 5. Introduction of organic substituents into the b position to the
isocyanide nitrogen atom give rise to complexes 8.
Scheme 3. Reaction of 4b to give 5 and the subsequent reaction to give 6.
from methyl to trimethylsilylbutadiynyl and it appears that
this reaction is a quite general and depends only on the
availability of the organolithium or Grignard compound.
previously described phosphoranes F3C CF CF PFR3[27] and
ˆ
F5S CF CF PFR3,[28] 5 could not be isolated but it could be
ˆ
characterized by low-temperature 19F and 31P NMR spectros-
copy of the reaction mixture. The 31P{1H} NMR spectrum
exhibits three resonances at d ˆ 14.7 (t, 1J(19F,31P) ˆ 536 Hz;
ˆ
Consequently, attempts to prepare [(CO)5Cr(CN CF CF
ꢀ
ˆ
ꢀ
C C CN)] and [(CO)5Cr(CN CF CF C C COOMe)] from
ꢀ
ꢀ
HC C CN and HC C COOMe failed. [(CO)5Cr(CN
CF CFOMe)] (8i) was the only product isolated from the
reaction of HC C COOMe with lithium diisopropylamide
1
PF2(CH3)3), 61.4 (s; P(CH3)3), and 77.8 (d, J(19F,31P) ˆ
ˆ
555 Hz, 5). The 19F NMR spectrum shows three resonances in
at d ˆ 19.3 (d, PF), 138.2 (3J(19F,19F) ˆ 128 Hz; CF), and
141.8 which can be assigned to the product 5 besides the
signals of starting material and decomposition products. As
both spectra recorded at 508C exhibit signals of the starting
materials, 5, and the decomposition product 6, no attempts
were made to isolate the phosphorane 5. Thermal decom-
position and hydrolysis with H2O or D2O yields the 1,2-
difluoroethenyl isocyanide complexes 6 and [D]-6, respec-
tively.
ꢀ
(LDA) and 4b. However, 4b reacts with methanol in the
presence of potassium carbonate forming the addition prod-
uct [(CO)5Cr(CN CHF CF2OMe)] (9). Organomagnesium
compounds give higher yields than organolithium compounds.
This might be due to lower fluoride concentrations in the
reaction mixture, as high fluoride concentrations lead to a
complete decomposition of 4a and b to unidentified products.
Deprotonation of ethynyltributylstannane with butyllithium
and subsequent reaction with 4b yields the dinuclear chro-
mium complex 10 (Scheme 6). Removal of the trimethylsilyl
(E/Z)-Pentacarbonyl(1-chloro-2-cyano-2-difluoroethenyl
isocyanide)chromium (7a) and (E/Z)-pentacarbonyl(2-cyano-
1,2-difluoroethenyl isocyanide)chromium (7b) were obtained
from 4a and 4b, respectively, and potassium cyanide in
acetonitrile; this route also provided a facile route to 13C- and
15N-labeled compounds (Scheme 4).
Scheme 6. Reaction of 4b and ethynyltributylstannane and butyllithium to
give 10.
protecting groups in 8a ± d by using potassium carbonate in
methanol (Scheme 7) yields 11a ± c. However, it is extremely
difficult to control the desilylation by using tetrabutylammo-
nium fluoride in THF. After a reaction time of a few minutes
Scheme 4. Reaction of 4a, b with KCN to give 7a, b.
Chem. Eur. J. 2001, 7, No. 4
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883

D. Lentz et al.
FULL PAPER
Scheme 7. Removal of the protecting groups on 8a, b, d to give 11.
Scheme 8. Reaction of [Co2(CO)8] with 8e to give 12.
only traces of the starting materials or products could be
detected by 19F NMR spectroscopy. This observation again
demonstrates the sensitivity of the ethenyl isocyanide com-
plexes towards fluoride ions. Complexes 11a and b can also be
prepared directly from 4a and b, respectively, and HCCMgBr,
however, it is difficult to control the yields and purity of the
products. All nucleophilic substitution reactions of 4a and b
result in mixtures of the E and Z isomers.
The chromium complexes 3 ± 10 are crystalline materials
with low melting points and high volatility. They are very
soluble in most organic solvents. Both the solutions and the
crystals can be handled in air without significant decomposi-
tion for short periods of time. However, they should be kept
under argon in a cold place for longer term storage. The
unprotected alkynyl compounds 11 are much more sensitive
and should be handled in an inert gas atmosphere. (E/Z)-
Pentacarbonyl(1-chloro-2-fluoropent-1-en-3-ynyl isocyani-
de)chromium [(CO)5Cr(CNCClCFC2CH3)] (8e) reacts with
octacarbonyldicobalt to give a typical alkyne complex 12 with
the expected dimetallatetrahedrane structure (Scheme 8) in
the form of dark red air-stable crystals.
carbonyl ligands together with those of smaller fragments.
Although the pentacarbonylchromium fragment possesses
local C4v symmetry, the assignment of the CO vibrations is not
easy due to strong coupling with the CN stretching mode.
NMR spectra are an effective analytical tool in character-
3
izing these compounds. The J(19F,19F) coupling constants of
the compounds 4b, 6, 7b, 8b, d, f, h, i, 11a, b allow an easy
assignment of the resonances of the E and Z isomer,
respectively. Selected chemical shift values and 1J(13C,19F)
2
and J(13C,19F) coupling constants are listed in Table 1. From
these values a general trend can be found:
The resonance of the b-fluorine atom of the E isomer with
the fluorine atoms in trans position is observed at about
10 ppm higher field than that of the Z isomer. 13C chemical
shift values of the alkene carbon atoms of the E isomer are
1
observed at lower field than that of the Z isomer. J(13C,19F)
coupling constants of the b-fluorine atom vary but those of the
E isomer are about 10 Hz smaller than those of the Z isomer
for the same compound. The opposite trend is observed for
2
the J(13C,19F) coupling constants of the b-fluorine atom. A
similar trend is observed for the chloro-substituted com-
pounds 4a, 7a, 8a, c, e, g and 11a (Table 1 bottom part); this
allows an assignment of the resonances to the E and Z isomer,
respectively. The correctness of this assignment is proven by
All complexes were fully characterized by spectroscopic
methods. Mass spectra usually exhibit the molecular ion as
well as fragment ions assigned to the successive loss of the five
Table 1. Selected chemical shift values [ppm] and 13C,19F coupling constants [Hz]. b-Fluorine substituents trans to a halogen substituent are labeled E. The
assignment of the resonances in the upper part of this table is unambiguous due to the 19F,19F coupling constant.
d 19F(b)
(Z)
d 13C(b)
(Z)
1JCF
(Z)
d 13C(a)
(Z)
2JC,F
(Z)
(E)
112.5
D
(E)
D
(E)
D
(E)
D
(E)
D
4b
6
7b
8b
8d
8f
101.0
160.2
156.9
134.8
137.2
133.6
126.1
150.2
137.8
138.6
82.3
123.8
105.2
107.3
101.9
93.4
11.5
10.4
9.9
9.5
9.7
9.8
8.3
5.6
9.7
9.9
7.3
7.9
4.6
5.0
4.5
4.5
5.0
170.6
165.8
144.3
146.9
143.4
134.3
155.8
147.5
148.5
89.6
131.7
109.6
112.3
106.4
97.9
138.3
123.7
132.3
132.3
132.8
147.8
151.5
132.2
259
240
237
133.9
137.5
134.8
136.3
134.0
39
45
54
121.3
130.6
130.7
131.0
144.7
150.8
130.5
2.4
1.7
1.6
1.8
3.1
0.7
1.7
251
246
247
245
260
286
246
11
9
135.8
133.1
134.3
132.5
1.7
1.7
2.0
1.5
38
45
45
46
7
9
236
255
277
237
9
5
9
9
55
9
8h
8i
119.0
135.9
118.5
133.7
0.5
2.2
67
53
58
43
9
10
11b
11c
4a
7a
8a
8c
8e
8g
11a
294
256
250
250
251
267
251
300
259
254
252
253
271
254
6
3
4
2
2
4
3
51
46
56
55
57
39
33
43
42
46
12
13
13
13
11
131.9
142.2
142.2
143.4
159.3
142.2
131.3
140.7
140.6
141.4
158.1
140.4
0.6
1.5
1.6
2.0
1.2
1.8
117.5
109.5
111.6
108.2
102.7
110.8
115.2
108.8
110.6
107.7
102.2
109.9
2.3
0.7
1.0
0.5
0.5
0.9
110.5
93.4
52
40
12
884
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Chem. Eur. J. 2001, 7, No. 4

Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
the X-ray crystal structure determination of (E)-8a (see
below). The alkyne proton of 11a and b are observed at d ˆ
4.00 ((E)-11a), 3.97 ((Z)-11a) and 4.11 ((E)-11b), 3.92 ((Z)-
11b), respectively. The signals are split into a doublet and a
doublet of doublets due to scalar coupling with fluorine ((E)-
decomposition of 5 seems to be greater than that obtained by
hydrolysis of 5. Unexpectedly, reaction of 4b with 4-trime-
thylsilylbutadiynyllithium results in an at least sixfold excess
of the Z isomer. Even more striking is the almost exclusive
formation of decacarbonyl[(Z,Z)-1,2,5,6-tetrafluoro-1,6-iso-
cyano-hexa-1,5-dien-3-yne]dichromium ((Z,Z)-10) which
makes it difficult to determine the spectroscopic data of the
other two isomers although the E,Z isomer should be
statistically favored. As the Rf values of the isomers using
different eluents turned out to be very similar, no attempts
were made to separate the isomers by chromatography.
However, in some cases the difference in solubility and
volatility of the E and Z isomer allowed a separation by
fractional crystallization or sublimation.
4
4
4
11a, JH,F ˆ 3 Hz; (Z)-11a, JH,F ˆ 4 Hz; (E)-11b, JH,F ˆ 3 Hz,
4
5
5JH,F ˆ 3 Hz; (Z)-11b, JH,F ˆ 3 Hz, JH,F ˆ 1 Hz), respectively.
6
In 11d even a JH,F coupling is observed.
The 13C NMR spectra give further information, especially
on the ligand properties of the halogenated isocyanides. The
interpretation of the spectra is usually straightforward due to
scalar coupling with fluorine or proton substituents. In the
case of the 13C- or 15N-labeled compounds additional 13C,13C,
15N,19F, and 13C,15N coupling constants can be determined.
Missing information is derived from two-dimensional 19F,13C
1
and H,13C HMQC spectra.
X-ray crystal structure determinations
In complexes of the type [(CO)5CrL] the resonances of the
carbonyl ligands give rise to signals around d ˆ 200 in the
13C NMR spectra in an intensity ratio of 4:1. With a few
exceptions the signal of the trans carbonyl carbon atom is
registered at higher frequency than that of the cis carbonyl
ligands. Only for very strong p-acceptor ligands like CS,[29]
CSe,[29] CNCN,[30] and CF3NC,[31] is the resonance of the trans
carbonyl ligand observed at the same frequency or at lower
frequency than the cis carbonyl ligand. The difference in
chemical shift values of the halogenated ethyl isocyanide
complexes 3a ± c decreases with the number of fluorine
substituents (for 3b it is only
The crystallographic data of 11a, 11b, 8i, and 12 are
summarized in Table 3. Selected bond lengths and angles
are compared in Table 4. ORTEP drawings of the molecules
are given in Figure 1, Figure 2, and Figure 3, respectively. In
all of the complexes studied by X-ray crystallography the
chromium atom is coordinated almost octahedrally by the five
carbonyl ligands and the isocyanide ligand. The chromium ±
carbon bond lengths to the carbonyl ligands vary slightly
ranging from 1.895 to 1.918 Š with no significant shortening of
the bond trans to the isocyanide ligand. Cr C bond lengths to
0.1 ppm). Thus the p-acceptor
ability of the 1,2-dichloro-1,2,2-
trifluoroethyl isocyanide ligand
approaches that of the carbonyl
ligand. The differences in
chemical shift values between
cis and trans carbonyl ligands is
much larger for all of the al-
kenyl isocyanide complexes
studied, which is in agreement
with structural data that show
these isocyanides are weaker p-
acceptor ligands.
In most cases the ratio of the
E and Z isomers is very close to
one (Table 2). Depending on
the reaction conditions the 1,2-
difluorethenyl complex
6 is
formed predominantly as the
E isomer. This may be due to
the almost exclusive formation
of (Z)-5 which has the fluorine
substituents in trans position.
The excess (E)-6 in the thermal
Figure 1. Molecular structure (ORTEP[40]) of 11a (left) and 11b (right).
Table 2. Ratio of the E and Z isomers formed as determined by integration of the 19F NMR spectra of the reaction mixtures.
6
6
7a
7b
8a
8b
8c
8d
8e
8 f
8g
8h
8i
E/Z
50[a]
6[b]
0.77
0.77
0.8
0.8
2.0
0.15
1.3
0.8
1.4
0.8
0.71
[a] Obtained by thermal decomposition of 5. [b] Obtained by hydrolysis of 5.
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885

D. Lentz et al.
FULL PAPER
Table 3. Crystal data and structure refinement for 11a, 11b, 8i, and 12.
11a
11b
8i
12
empirical formula
Mr
C10HClCrFNO5
321.57
C10HCrF2NO5
305.12
C9H3CrF2NO6
311.12
C17H3ClCo2CrFNO11
621.51
T [K]
163(2)
123(2)
153(2)
293(2)
l [Š]
0.71073
monoclinic
P21/n
6.7242(12)
11.730(2)
15.359(3)
90
91.615(4)
90
1210.9(4)
4
0.71073
monoclinic
P21/c
7.0088(4)
6.2563(4)
25.7584(15)
90
94.5440(10)
90
1125.93(12)
4
1.800
1.059
600
0.71073
0.71069
monoclinic
C2/c
24.063(5)
9.693(2)
20.680(4)
90
105.650(16)
90
4644.8(17)
8
1.778
2.050
2432
crystal system
space group
a [Š]
b [Š]
c [Š]
a [8]
b [8]
g [8]
V [Š3]
triclinic
Å
P1
6.4969(4)
9.6269(6)
10.2481(6)
81.1150(10)
78.0610(10)8
73.3140(10)
597.60(6)
2
Z
3
1calcd [Mgm
m [mm
F(000)
Crystal size [mm3]
qmax [8]
]
1.764
1.192
632
1.729
1.005
308
1
]
0.40 Â 0.30 Â 0.15
0.30 Â 0.21 Â 0.08
0.5 Â 0.3 Â 0.3
0.38 Â 0.30 Â 0.15
27.53
31.03
31.46
25.00
index ranges
8 ꢁ h ꢁ 8,
0 ꢁ k ꢁ 15,
0 ꢁ l ꢁ 19
11481
9 ꢁ h ꢁ 9,
0 ꢁ k ꢁ 9,
0 ꢁ l ꢁ 36
13436
9 ꢁ h ꢁ 9,
13 ꢁ k ꢁ 14,
14 ꢁ l ꢁ 14
7107
24 ꢁ h ꢁ 28,
6 ꢁ k ꢁ 11,
24 ꢁ l ꢁ 9
4666
reflections collected
independent reflections/Rint 2792/0.1023
3445/0.0304
96.0
empirical SADABS
0.9422/0.7440
3524/0.0144
89.0
empirical SADABS
0.695/0.554
4107/0.0107]
100.0
empirical PSI scan
0.970/0.805
completeness to qmax [%]
absorption correction
Tmax/Tmin
99.9
empirical SADABS
0.96/0.81
refinement method
full-matrix least-squares on F 2 full-matrix least-squares on F 2 full-matrix least-squares on F 2 full-matrix least-squares on F2
data/restraints/parameters 2792/0/176
3445/0/176
1.034
0.0257/0.0677
0.0362/0.0717
0.379/ 0.532
3524/0/184
1.033
0.0235/0.0673
0.0254/0.0684
0.396/ 0.527
4107/0/307
1.018
0.0284/0.0753
0.0619/0.0848
0.263/ 0.248
goodness-of-fit on F 2
R1/wR2 [I > 2s(I)]
0.935
0.0400/0.0623
0.0853/0.0692
0.320 and 0.329
R1/wR2 (all data)
D1max/D1min [e Š
3
]
Table 4. Selected bond lengths [Š] and angles [8] for 11a, 11b, 8i, 12.
to the isocyanide carbon atom,
since the C N bond is part of a
conjugated system. However,
the conjugation effects on the
bond lengths are very small and
seem to be most pronounced
for 11b. As found for most
isocyanide complexes[32] the
C6-N1-C7 bond angles deviate
less than 208 from 1808. Owing
to the coordination to the two
cobalt atoms the C9 C10 bond
in 12 is significantly longer than
the C C triple bond in 11a and
11b. The C8-C9-C10 and C9-
C10-C11 bond angles in 12 are
significantly smaller than 1808.
The Co Co bond length of
2.4573(7) Š compares well with
other hexacarbonyl(m2-h2-alky-
ne)dicobalt complexes structur-
ally studied.[33]
11a
11b
8i
12
Cr1 C1
Cr1 Ccis
Cr1 C6
N1 C6
N1 C7
Cl1 C7
F1 C7
1.897(3)
1.897(3) ± 1.917(3)
1.942(3)
1.170(3)
1.374(3)
1.9108(13)
1.9082(13) ± 1.9184(13)
1.9338(13)
1.1753(16)
1.3562(16)
1.9048(11)
1.9058(12) ± 1.9158(12)
1.9466(11)
1.1683(15)
1.3603(14)
1.895(3)
1.901(3) ± 1.916(4)
1.959(3)
1.165(4)
1.369(3)
1.719(3)
1.725(3)
1.3376(14)
1.3449(13)
F1 C8
1.365(3)
1.349(3)
F2 C8
C7 C8
C8 C9
1.3503(15)
1.3356(18)
1.4181(18)
1.3352(14)
1.3225(16)
1.318(4)
1.415(4)
1.332(4)
1.421(4)
C8 O6
C9 C10
Co2 Co3
Co C9(10)
1.3222(13)
1.173(4)
1.1859(19)
1.339(4)
2.4573(7)
1.949(3) ± 1.966(3)
C6-N1-C7
N1-C7-Cl1
N1-C7-F1
F1-C8-C9
F2-C8-C9
C10-C9-C8
175.3(3)
116.3(2)
167.66(13)
114.90(11)
176.91(12)
114.40(10)
165.0(3)
114.9(2)
116.8(3)
178.1(4)
115.6(3)
116.47(11)
177.74(15)
the isocyanide ligand range from 1.934 to 1.959 Š. The
substituent at the isocyanide nitrogen atoms are in an almost
eclipsed position to one of the carbonyl ligands; the C-Cr-C7-
X (X ˆ Cl, F) torsion angles lie between 5.4 and 16.48. This is
the only conformation that allows an effective p back bonding
Pyrolysis experiments
Pyrolysis experiments in which the compounds 4a, b, c, 6, 7a,
8e, and 11a were used to obtain the free isocyanides were
886
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Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
Figure 2. Molecular structure (ORTEP[40]) of 8i.
Scheme 9.
trifluoroethenyl isocyanide 13b and its isomer trifluoracrylo-
nitrile were determined recently by X-ray crystallography.[5]
All attempts to obtain fluoroethynyl isocyanide by pyrolysis
of 4a, 4b, or 4c failed. According to the IR spectra (n(NC)
ˆ
ˆ
2111 vs, n(C C) 1744 vs and n(NC) 2104 vs, n(C C)
1
ˆ
ˆ
1654 s cm ) CN CCl CF2 (13a) and CN CCl CClF (13c)
are formed on pyrolysis of 4a and 4c at 2508C, respectively.
Figure 3. Molecular structure (ORTEP[40]) of 12.
partially successful. Flash vacuum pyrolysis of 4b yields the
first perfluorinated alkenyl isocyanide 13b as a colorless gas
(Scheme 9). Compound 13b is stable at low temperature, in
the gaseous phase at low pressure, or in dilute solution. It
decomposes readily even below 08C in concentrated solution
or as a neat substance. Vapor pressure measurements between
189 K and 225 K result in lnp ˆ 24736/RT‡17.13 and an
extrapolated boiling point of 188C.
Figure 4. 19F NMR spectrum of 13. 2J(19Fa,19Fb) ˆ 53 Hz, 3J(19Fa,19Fc) ˆ
2
50 Hz, 3J(19Fb,19Fc) ˆ 113 Hz, J(14N,19Fc) ˆ 10 Hz.
The mass spectrum of 13b exhibits the molecular ion and
smaller fragment ions. The IR spectrum shows absorption at
1
ˆ
2111 and 1801 cm due to NC and C C stretching modes. The
As expected pyrolysis of 6 yields the ethenyl isocyanide 14
as a mixture of the E and Z isomers. The ratio of the isomers is
equivalent to that of the precursor complex 6. All spectro-
scopic data are consistent with 6. The 19F NMR spectrum
exhibits additional splitting due to coupling to the nitrogen
isotope 14N. Nevertheless the product contained a more
volatile material which was easily identified as ethynyl
isocyanide 15 by comparing the mass and IR spectra with
those of previously prepared samples (Scheme 9).[7] Although
19F NMR spectrum of 13b (Figure 4) consists of an ABC
pattern similar to 4. However, an additional splitting into 1:1:1
triplet is observed for the resonance of the fluorine atom in
the geminal position to the nitrogen atom. Generally, free
isocyanides although quite unsymmetrical can have small
electric field gradients at the nitrogen atom which allows the
observation of the H,14N or 19F,14N coupling and results in
small line width in the 14N NMR spectra.[34] The structures of
1
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D. Lentz et al.
FULL PAPER
tetrachlorofluoroethane (PCR) were used as received. The chlorofluoro-
ethanes employed were purified by distillation using a spinning band
column for reuse.
this undesired side reaction made the purification of 6
difficult, this result was important because it clearly demon-
strated the possibility of alkyne formation by a defluorination
reaction.
Consequently, we have synthesized 7, 8, and 11 as potential
precursor molecules for cyanoisocyanoacetylene and isocya-
nopolyynes. However, the results of the pyrolysis experiments
of 7, 8, and 11 are different. Apart from the fact that the
pyrolysis of 7 is less efficient than that of [(CO)5Cr(CN
Pentacarbonyl(1,1,2-trichloro-2,2-difluoroethyl isocyanide)chromium (3a):
Tetraethylammonium pentacarbonyl(cyano)chromate (9.40 g, 27.0 mmol)
was suspended in 1,1,2-trichloro-2,2-difluoroethane (80 mL). Phenyldiazo-
nium tetrafluoroborate (25 mmol) was added at 788C. On warming to
ambient temperature the light yellow suspension turned to dark brown,
while nitrogen gas was evolved. After 2 h at ambient temperature the
solvent was removed in vacuum into a trap kept at 1968C for reuse. The
residue was extracted several times with pentane. The solvent was removed
in vacuum. The remaining product was purified by column chromatography
(silica/pentane). Sublimation in vacuum (358C/0.1 Pa) yielded 3a as a
yellow solid. Yield: 5.52 g (14.3 mmol, 53%); m.p. 628C; elemental analysis
for C8Cl3CrF2NO5 (%): calcd: C 24.86, N 3.62; found: C 24.94, N 3.94; MS
(EI, 80 eV): m/z: 385, 329, 301, 273, 245 (100%), 210, 175, 52; IR (pentane):
nÄ ˆ 2005 sh, 1985 vs, 1956 sh cm 1; IR (KBr): nÄ ˆ 2185 m, 2120 s, 1955 vs,
1190 s, 1160 s, 1100 s, 1018 s, 1002 m, 841 s, 773 s, 676 vs, 648 vs, 545 s, 522 w,
441 s cm 1; Raman: nÄ ˆ 2184 vw, 2110 w, 2002 vs, 1942 w, 1101 w, 1018 w,
ˆ
CCl CClH)] it yields cyanoisocyanoacetylene 16 in amounts
sufficient to record all necessary spectroscopic data
(Scheme 9). As the cyano group is introduced in the final
step, isotopic labeling of the cyano group by 15N or 13C can be
performed easily, and this provides a sufficient number of
rotational constants of the isotopomers for a reliable structure
determination.[14] The expected by-product 1-chloro-2-cyano-
2-fluoroethenyl isocyanide (2-chloro-3-fluoro-3-isocyanopro-
pennitrile) (17) was purified by fractional condensation under
vacuum and identified by mass, IR, and NMR spectra. Again
a mixture of the E and Z isomers was obtained. In almost all
pyrolysis experiments using 11a an explosive decomposition
of the chromium complex was observed, leading to the
formation of a dark brown material which filled the complete
1001 vw, 841 vw, 774 vw, 679 vw, 648 vw, 625 vw, 545 vw, 526 vw, 500 vw, 454
1
w, 442 w, 388m, 551 w, 312 vw, 293 vw, 252vw, 229 vw, 169 vw, 105 m cm
;
13C NMR: d ˆ 84.8 (t, 2JC,F ˆ 37 Hz; CCl2), 124.6 (t, 1JC,F ˆ 303 Hz; CClF2),
202.5 (s; NC), 212.1 (s; COcis), 212.6 (s; COtrans); 19F NMR: d ˆ 66.82 (s;
CClF2).
Pentacarbonyl(1,2-dichloro-1,2,2-trifluoroethyl isocyanide)chromium (3b):
The compound 3b was prepared similarly to 3a using 1,2-dichloro-1,2,2-
trifluoroethane (100 mL). Yield: 4.3 g (11.6 mmol, 46.4%) as a yellow
solid; m.p. 398C; elemental analysis for C8Cl2CrF3NO5 (%): calcd C 25.97,
ꢀ
ꢀ
ꢀ
vacuum line. Occasionally HC C C C C N could be de-
tected by comparison of the IR spectrum with literature
values[35] and by millimeter-wave spectroscopy.[36] Attempts
using 8e were equally unsuccessful.
N 3.79; found C 27.28, N 3.77; MS (EI, 80 eV): m/z: 369, 306, 257, 229, 194
1
(100%), 52; IR (pentane): nÄ ˆ 2010 w, 1983 vs, 1952 m cm
;
13C NMR: d ˆ
1
2
1
101.5 (dt, JC,F ˆ 270 Hz, JC,F ˆ 38 Hz; CClF), 122.7 (dt, JC,F ˆ 303 Hz,
2JC,F ˆ 38 Hz; CClF2), 208.1 (s; NC), 211.8 (s; COcis), 211.9 (s; COtrans); 19F
NMR : d ˆ 83.0 (dd, 3JC,F ˆ 9 Hz, 3JC,F ˆ 10 Hz; CFCl), 70.1 (dd, 2JC,F
ˆ
3
2
3
165 Hz, JC,F ˆ 10 Hz; CF2Cl),
69.3 (dd, JC,F ˆ 165 Hz, JC,F ˆ 9 Hz;
CF2Cl).
Conclusion
Pentacarbonyl(1,1,2,2-tetrachloro-2-fluoroethyl
isocyanide)chromium
(3c): The compound 3c was prepared similarly to 3a using 1,1,2,2-
tetrachloro-2-fluoroethane (100 mL). Yield: 0.79 g (2.0 mmol, 34%) as a
yellow solid; m.p. 718C; elemental analysis for C8Cl4CrFNO5 (%): calcd: C
23.85, N 3.48; found: C 23.86, N 3.38; MS (EI, 80 eV): m/z: 403, 291, 263,
The cross-coupling reaction of pentacarbonylchromium-pro-
tected halogenated ethenyl isocyanides with various carbon
nucleophiles is a very effective method for the synthesis of
various isocyanides. Vacuum pyrolysis of some of these
complexes is still the only preparative route for alkynyl
isocyanides. To generalize our synthesis strategy it is necessary
to develop more facial dehalogenation methods as well as
easier methods for the removal of the pentacarbonylchromi-
um protecting group.
1
2
191, 52; IR (pentane): nÄ ˆ 1978 vs br cm
;
13C NMR: d ˆ 88.95 (d, JC,F
ˆ
1
35 Hz; CCl2), 120.6 (d, JC,F ˆ 310 Hz; CCl2F, major conformer), 121.6 (d,
1JC,F ˆ 311 Hz; CCl2F, minor conformer), 199.9 (s; NC), 212.3 (s; COcis),
212.9 (s; COtrans); 19F NMR : d ˆ 64.4 (major conformer), 52.9 (minor
conformer).
Pentacarbonyl(1-chloro-2-difluoroethenyl isocyanide)chromium (4a): A
solution of 3a (3.80 g, 9.8 mmol) in diethyl ether was cooled to 08C and zinc
powder (6.40 g, 98.0 mmol) and acetic acid (2 mL) were added. The
reaction mixture was stirred for 6 h at ambient temperature. After filtration
the solvent was removed in vacuum at 208C. The residue was purified by
column chromatography (silica, pentane). Sublimation in vacuum (358C/
0.1 Pa) yielded 4a as yellow crystals. Yield: 2.47 g (7.8 mmol, 80%); m.p.
608C; elemental analysis for C8ClCrF2NO5 (%): calcd: C 30.45, N 4.44;
found: C 30.58, N 4.68; MS (EI, 80 eV): m/z: 315, 287, 259, 231, 203, 175
(100%), 78, 52; IR (KBr): nÄ ˆ 2125 m, 2051 s, 1942 br, vs, 1733 s, 1336 s, 1187
m, 1145 vw, 1029 s, 685 s, 650 vs, 572 vw, 539 w, 507 vw, 490 vw, 464 w, 445
m cm 1; IR(pentane): nÄ ˆ 2116 w, 2029 m, 1977 vs, 1946 w, 1902 vw, 1731
m cm 1; Raman (solid): nÄ ˆ 2370 vw, 2119 m, 2027 s, 1997 s, 1968 w, 1942 vw,
Experimental Section
General: All reactions were carried out under dry argon by using standard
Schlenck and vacuum techniques. Volatile materials were handled in a
conventional glass vacuum line and amounts were determined by PVT
techniques. Moisture-sensitive compounds were handled in an automatic
1
2
dry box (Braun) under dry argon. H, D, 13C, and 15N NMR spectra were
recorded by using a JEOL FX 90Q or JEOL LAMBDA 400 instrument
with TMS or solvent signals (1H, 2D, 13C), nitromethane (15N) and CFCl3
(19F) as standards. Infrared spectra were taken on a Perkin Elmer 883,
Nicolet 5SXC or a Bruker Vector 22 instrument. Raman spectra were
recorded by using a Bruker RFS 100 or SPEX1403 instrument. Mass
spectra were obtained on a Varian MAT 711 (80 eV) or a Balzers QMS 200
instrument. Tetraethylammonium pentacarbonyl(cyano) chromate 1 was
prepared following the literature procedure;[37] however, sublimed hex-
acarbonyl chromium and freshly sublimed sodium bis(trimethylsilyl)amide
were used to get a maximum yield of 95% and to avoid the formation of
pyrophoric by-products. K[Cr(CO)5(C15N)] was prepared according to
literature procedures.[38] 1,2-Dichlorotrifluoroethane (Hoechst and Du-
Pont), 1,1,2-trichlorodifluoroethane (Hoechst and DuPont), and 1,1,2,2-
1734 w, 1188 m, 1145 vw 1029 vw, 683 m, 647 vw, 572 m, 537 w, 506 vw, 464
1
vw, 435 w, 390 vs, 345 vw, 326, vw, 270 w, 191 w, 166 m cm
;
13C NMR: d ˆ
2
2
1
1
86.3 (dd, JCF ˆ 51 Hz, JC,F ˆ 39 Hz; CCl), 156.8 (dd, JC,F ˆ 300 Hz, JC,F
ˆ
294 Hz; CCF2), 191.2 (s; NC), 213.2 (s; COcis), 214.6 (s; COtrans); 19F NMR:
2
2
d ˆ 89.63 (d, JF,F ˆ 11 Hz), 82.31 (d, JF,F ˆ 11 Hz).
Pentacarbonyl(trifluoroethenyl isocyanide)chromium (4b): The compound
4b was prepared similarly to 4a using 3b (Yield: 0.78 g (2.6 mmol, 89%) as
yellow crystals; m.p. 388C; elemental analysis for C8CrF3NO5 (%): calcd: C
32.12, N 4.68; found: C 33.41, N 4.55; MS (EI, 80 eV): m/z: 299, 271, 243,
215, 187, 159 (100%), 52; IR (pentane): nÄ ˆ 2114 w, 2020 m, 1973 vs, 1944 m,
1
1
2
1774m cm
;
13C NMR: d ˆ 117.1 (dt, JC,F ˆ 297 Hz, JC,F ˆ 49 Hz; CF),
152.3 (1JC,F ˆ 286 Hz, JC,F ˆ 293 Hz, JC,F ˆ 49 Hz; CF2), 199.3 (s; NC),
1
2
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Chem. Eur. J. 2001, 7, No. 4

Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
1
4
213.0 (s; COcis), 214.2 (s; COtrans); 19F NMR: d ˆ 152.9 (dd, 2JC,F ˆ 46.4 Hz,
131.3 (d, JC,F ˆ 259 Hz; CF), 203.8 (d, JC,F ˆ 6 Hz, NC), 212.0 (s; COcis),
3JC,F ˆ 112 Hz; CClF),
111.6 (dd, JC,F ˆ 46 Hz, JC,F ˆ 53.7 Hz; CF2),
212.8 (s; COtrans); 19F NMR : d ˆ 123.80 (s; CF).
2
3
3
3
100.5 (dd, JC,F ˆ 112 Hz, JC,F ˆ 53.7 Hz; CF2).
(E/Z)-Pentacarbonyl(1,2-difluoro-2-cyanoethenyl isocyanide)chromium
(7b): The compound 7b was prepared similarly to 7a using 4b. Yield:
16 mg (0.05 mmol, 20%); m.p. 358C; elemental analysis for C9CrF2N2O5
(%): calcd: C 35.31, N 9.15; found: C 35.02, N 8.76; MS (EI, 80 eV): m/z:
306, 278, 250, 222, 194, 166 (100%), 52; IR (hexane): nÄ ˆ 2015 w, 1986 vs,
1964 sh m cm 1; IR (KBr): nÄ ˆ 2227 w, 2115 w, 1966 vs, 1684 w, 1311 m, 1264
m, 1240 m, 1110 w, 1079 m, 1022 w, 865, vw, 804 w, 728 m, 650 s, 613 vw, 599
vw, 522 w, 436 m, 382 vw, 305 vw cm 1; Raman (solid): nÄ ˆ 2229 w, 2115 vw,
2024 w, 2004 m 1978 vw 1961 vw, 1691 w, 1677 sh, 1314 m 1262 w, 727 vw, 615
vw, 527 vw, 431 w, 387 vs, 395 vw, 323 vw, 305 vw, 297 vw, 244 w, 175 vw, 146
Pentacarbonyl(1,2-chloro-2-fluoroethenyl isocyanide)chromium (4c): The
compound 2c was prepared similarly to 4a using 3c (1.03 g, 2.6 mmol).
Yield: 0.65 g (2.9 mmol, 75%) as yellow crystals containing both isomers;
m.p. 558C; elemental analysis for C8Cl2CrFNO5 (%) calcd: C 28.94, N 4.22;
found: C 29.62, N 4.27; MS (EI, 80 eV): m/z: 331, 303, 275, 245, 219, 191, 52;
1
IR (pentane): nÄ ˆ 2023 m, 1972 s, 1940 w,sh cm
;
13C NMR: d ˆ 101.25 (d,
2JC,F ˆ 49 Hz; CCl), 102.83 (d, JC,F ˆ 38 Hz; CCl), 146.08 (1JC,F ˆ 309 Hz;
CClF), 147.98 (1JC,F ˆ 312 Hz; CClF), 190.3, 191.12 (s; NC), 213.11, 213.12
(s;COcis), 214.46, 214.64 (s; COtrans); 19F NMR: d ˆ 77.8 (s), 84.3 (s).
2
vw, 115 vs cm 1. (E)-7b: 13C NMR: d ˆ 108.1 (dd, JC,F ˆ 37 Hz, JC,F
ˆ
2
3
(E/Z)-Pentacarbonyl(1,2-difluoro-2-l5-fluorotrimethylphospharanylethen-
yl isocyanide)chromium (5): Compound 4b (60 mg, 0.2 mmol) was
dissolved in [D8]toluene (1 mL) in a 5 mm NMR tube and cooled to
788C. Trimethylphosphane (0.2 mmol) was condensed onto the solution.
After mixing at 788C the tube was brought into the NMR spectrometer
and allowed to warm to 508C. 19F and 31P NMR spectra were recorded at
508C and exhibited signals of trimethylphosphane, 3b, 5, 6, and
1
2
10 Hz; CN), 123.7 (dd, JC,F ˆ 240 Hz, JC,F ˆ 62 Hz; CF CN), 137.5 (dd,
1JC,F ˆ 264 Hz, JC,F ˆ 45 Hz; CN-CF), 209.2 (s; NC), 211.5 (s; COcis), 211.6
2
(s; COtrans); 19F NMR : d ˆ 165.8 (d, JF,F ˆ 128 Hz; CF CN), 114.8 (d,
3
3JF,F ˆ 128 Hz; CN CF); (Z)-5b: 13C NMR: d ˆ 109.0 (dd, JC,F ˆ 36 Hz,
2
3JC,F ˆ 3 Hz; CN), 121.3 (dd, JC,F ˆ 251 Hz, JC,F ˆ 38 Hz; CF CN), 135.8
1
2
1
2
(dd, JC,F ˆ 282 Hz, JC,F ˆ 37 Hz; CN CF), 212.9 (s; NC), 211.6 (s; COcis),
211.6 (s; COtrans); 19F NMR : d ˆ 156.7 (d, 3JF,F ˆ 3 Hz; CF-CN), 90.0 (d,
3JF,F ˆ 3 Hz; CN CF).
1
difluorotrimethylphosphorane. 31P NMR: d ˆ 77.1 (d, JP, F ˆ 552 Hz) 5;
1
61.4 (s), PMe3; 14.7 (t, JP, F ˆ 536 Hz) PF2Me3; 19F NMR: d ˆ 97.7
[(CO)5Cr(CNCClCF13CN)] (7c) and [(CO)5Cr(CNCClCFC15N)] (7d): The
compounds 7c and 7d were prepared similarly to 7a by using 13C-KCN and
15N-KCN. Additional spectroscopic data, only those vibrationational
spectroscopic data are listed which show significant changes: 7c: IR
(KBr): nÄ ˆ 2175 w cm 1; Raman (solid): nÄ ˆ 2175 w, 926 vw, 531 w cm 1, (E)-
(dd), 109.8 (dd), 150.7 (dd) 4b; 166.6 (dd), 142.7 (d) (E)-6; 137.77
2
1
1
1
(dd, JP, F ˆ 12 Hz, JF,F 128 Hz), 134.26 (d, JP, F 128 Hz), 23.26 (d, JP, F
ˆ
1
552 Hz) 5; 4.0 (d, JP, F ˆ 536 Hz) PF2Me3.
Pentacarbonyl(1,2-difluoroethenyl isocyanide)chromium (6): Trimethyl-
phosphane (4 mmol) was added by vaccum transfer to a solution of 4b
(450 mg, 1.5 mmol) in pentane (5 mL) at 788C. After stirring for three
hours the yellow suspension was allowed to warm to 408C and water
(0.36 mL, 20 mmol) was added. After stirring for an additional two hours
the solvent was removed in vacuum at 108C and the residue was
extracted with pentane. The pentane extract was purified by PTLC (silica,
pentane, first fraction, RF ˆ 0.42). Sublimation in vacuum (258C, 0.1 Pa)
yielded 6 as a colorless crystalline solid of both isomers. Yield: 172 mg
(0.6 mmol, 40%) m.p. 358C; elemental analysis for C8HCrF2NO5 (%):
calcd: C 34.18, H 0.36, N 4.98; found: C 34.35, H 0.80, N 4.76; MS (EI,
80 eV): m/z: 281, 253, 225, 197, 169, 141, 52; IR (pentane): nÄ ˆ 2116 m, 2020
s, 1975 vs, 1944 scm 1; IR (KBr): nÄ ˆ 3128 w, 2122 m, 2036 s, 1951 vs, 1864 m,
1701 w, 1325 m, 1221 m, 1159 m, 880 m, 796 w, 653 s, 441 m cm 1; (E)-6:
1
2
1
2
7c: JC,C ˆ 113 Hz, JC,C ˆ 11 Hz; (Z)-7c: JC,C ˆ 116 Hz, JC,C ˆ 13 Hz. 7d:
IR (KBr): nÄ ˆ 2214 vw, 2200 vw cm 1; Raman (solid): nÄ ˆ 2214 vw, 2198
1
w cm
;
15N-NMR: d {second isomer} ˆ 90.54{ 91.86} (s; C15N).
[(CO)5Cr(C15NCClCFCN)] (7e): The compound 7e was prepared from
NEt4[Cr(CO)5(C15N)]. Additional spectroscopic data: (E)-5e: 15N NMR :
d ˆ 204.4 (d, JF,N ˆ 3 Hz); 13C NMR: JC,N(N-C) ˆ 30 Hz, JC,N(CN) ˆ
3
1
1
22 Hz, JC,N ˆ 7 Hz; 19F NMR : d ˆ 131.79 (d, JF,N ˆ 3 Hz; CF); (Z)-7e:
2
3
15N NMR: d ˆ 202.1 (d, JF,N ˆ 3 Hz); 13C NMR: JC,N(N-C) ˆ 30 Hz,
3
1
1JC,N(CN) ˆ 22 Hz, JC,N ˆ 2 Hz; 19F NMR: d ˆ 123.89 (d, JF,N ˆ 3 Hz;
2
3
CF).
(E/Z)-Pentacarbonyl(1-chloro-2-fluoro-4-trimethylsilyl-but-1-en-3-ynyl
isocyanide)chromium [(CO)5Cr{CNCClCFC2Si(CH3)3}] (8a): Ethynyl(tri-
methyl)silane (2.1 mL, 15 mmol) was slowly added to a solution of
methylmagnesium bromide (10 mmol, 4.2 mL of a 2.4m solution in diethyl
ether) in THF (20 mL) at 08C forming a colorless precipitate. The
suspension was allowed to warm to ambient temperature and stirred for
2 h. Complex 4a (1.028 g, 3.3 mmol) was added and the solution turned
dark brown. After 20 min pentane (50 mL) was added and the reaction
mixture was filtered through a silica pad (l ˆ 3 cm, d ˆ 1 cm) and eluted
with pentane. The solvent was removed in vacuum at 208C. The residue
was sublimed in vacuum (358C, 0.1 Pa). Yield: 862 mg (2.2 mmol, 64%) of
both isomers. Elemental analysis for C13H9ClCrFNO5Si (%): calcd: C
39.66, H 2.30, N 3.56; found: C 39.78, H 2.93, N 3.74; MS (EI, 80 eV): m/z:
393, 337, 309, 281, 253, 73, 52; IR (pentane): nÄ ˆ 2117 m, 2026 s, 1976 vs, 1945
m cm 1; IR (KBr): nÄ ˆ 2963 w, 2923 w, 2852 vw, 2159 vw, 2116 m, 2042 s,
1961 vs, 1940 vs, 1616 w, 1251 m, 1154 w, 990 m, 850 s, 763 w, 727 m, 705 vw,
659 s, 648 s, 567 vw, 533 vw, 486 m cm 1; Raman (solid): nÄ ˆ 2967 w, 2904 w,
2299 vw, 2242 vw, 2159 m, 2113 m, 2015 vs, 1997 s, 1972 w, 1938 vw, 1622 s,
1617 s, 1259 m, 1153 m, 854 vw, 765 vw, 725w, 705 vw, 665 w, 644 vw, 628 w,
2
3
1H NMR: d ˆ 7.30 (dd, JH,F ˆ 72 Hz, JH,F ˆ 4 Hz, 1H; CHF); 13C{1H}
1
2
1
NMR: d ˆ 133.9 (dd, JC,F ˆ 244 Hz, JC,F ˆ 39 Hz; CF), 138.3 (dd, JC,F
ˆ
2
259 Hz, JC,F ˆ 69 Hz; CHF), 197.7 (s; NC), 213.0 (s; COcis), 214.3 (s;
COtrans); 19F NMR: d ˆ 170.6 (dd, JF,H ˆ 72 Hz, JF,F ˆ 130 Hz; CHF),
143.4 (d, 3JF,F ˆ 130 Hz; CF); (Z)-6: 1H NMR: d ˆ 6.80 (dd, 2JH,F ˆ 70 Hz,
2
3
3JH,F ˆ 12 Hz, 1H, CHF); 19F NMR: d ˆ 160.2 (d, JF,H ˆ 70 Hz; CHF),
2
2
116.6 (d, JF,H ˆ 13 Hz; CF). [D]-6: D2O was used in the hydrolysis step.
(E)-[D]-6: 2D NMR: d ˆ 7.13 (d, JD,F ˆ 11 Hz), 19F NMR: d ˆ 143.6 (d,
2
CF, 3JF,F ˆ 130 Hz), 171.1 (dt, CDF, 3JF,F ˆ 130 Hz, 2JD,F ˆ 11 Hz); (Z)-[D]-
6: 2D NMR: d ˆ 6.58 (dd, JD,F ˆ 11 Hz, JD,F ˆ 1.9 Hz), 19F NMR: d ˆ
2
3
116.9 (s; CF), 160.6 (t, CDF, 2JD,F ˆ 11 Hz).
(E/Z)-Pentacarbonyl(1-chloro-2-cyano-2-fluoroethenyl isocyanide)chro-
mium (7a): Complex 4a (966 mg, 3.1 mmol) was dissolved in acetonitrile
(20 mL) and heated to 458C. Potassium cyanide (586 mg, 9.0 mmol) was
added. The progress of the reaction was monitored by 19F NMR
spectroscopy. After about 45 min the mixture was placed on a silica
column and eluted with pentane. This resulted in two fractions, the first of
which contained 4a the second the product (RF ˆ 0.10) 7a. Sublimation in
vacuum (358C, 0.1 Pa) yielded 7a as an orange solid composed of both
isomers. Yield: 706 mg (2.2 mmol, 71%); m.p. 648C; elemental analysis for
C9ClCrFN2O5 (%): calcd: C 33.51, N 8.68; found: C 33.80, N 8.51; MS (EI,
80 eV): m/z: 322, 294, 266, 238, 210, 182 (100%), 78, 52; IR (KBr): nÄ ˆ 2235
vw, 2222 vw, 2117 s, 2025 s sh, 1950 vs br, 1626 vs, 1272 s, 1190 s, 1163 m, 1076
vw, 1015 vw, 980 m, 931 w, 865 vw, 682 s, 649 vs, 577 w, 539 w 437 m, 386 w,
338 vw cm 1; IR (pentane): nÄ ˆ 1987 vs, 1977 m sh, 1955 sh cm 1; Raman
(solid): nÄ ˆ 2254 vw, 2235 w, 2222 w, 2115 w, 2002 vs, 1984 m 1959 w, 1949 w,
1628 s, 1600 vw, 1271 m, 1191 m, 1160 w, 980 vw, 931 vw, 730 vw, 678 w, 664
w, 625 w, 539 w, 510 w, 432 m, 387 vs, 338 vw, 209 vw, 195 vw, 171 vw 110
616 w, 567 vw, 512 vw, 490 vw, 437 m, 387 vs, 275 w, 212 vw, 167 w cm 1. (E)-
8a: 1H NMR: d ˆ 0.27 (s, 9H; CH3); 13C NMR: d ˆ
0.5 (qh, JC,H
ˆ
ˆ
ˆ
1
3
2
2
122 Hz, JC,H ˆ 2 Hz; CH3), 90.2 (d, JC,F ˆ 35 Hz; CF C), 109.5 (d, JC,F
3
3
1
56 Hz; CCl), 113.8 (m, JC,F ˆ 1 Hz, JC,H ˆ 3 Hz; C Si), 142.2 (d, JC,F
250 Hz; CF), 186.9 (s; CN), 213.3 (s; COcis), 214.8 (s; COtrans); 19F NMR:
d ˆ 109.63 (s); (Z)-8a: 1H NMR: d ˆ 0.27 (s, 9H; CH3); 13C{1H} NMR:
2
2
d ˆ 0.9 (s; CH3), 90.7 (d, JC,F ˆ 34 Hz; CF C), 108.8 (d, JC,F ˆ 43 Hz;
CCl), 115.3 (dd, 3JC,F ˆ 4 Hz; C Si), 140.7 (d, JC,F ˆ 254 Hz; CF), 192.4 (s;
1
CN), 213.1 (s; COcis), 214.9 (s; COtrans); 19F NMR: d ˆ 104.99 (s).
(E/Z)-Pentacarbonyl(1,2-difluoro-4-trimethylsilyl-but-1-en-3-ynyl isocya-
nide)chromium [(CO)5Cr{CNCFCFC2Si(CH3)3}] (8b): The compound 8b
was prepared similarly to 8a by using the Grignard reagent of ethynyl-
(trimethyl)silane (10.0 mmol) and 4b (1495 mg, 5.0 mmol). The product was
purified by sublimation in vacuum (358C/ 0.1 Pa). Yield: 1610 mg
(4.3 mmol, 85%) of both isomers as a yellow solid. Elemental analysis
vs cm 1; (E)-7a: 13C NMR: d ˆ 108.9 (d, 2JC,F ˆ 40 Hz; CN), 117.5 (d, 2JC,F
ˆ
46 Hz; CCl), 131.9 (d, 1JC,F ˆ 256 Hz; CF), 202.4 (d, 4JC,F ˆ 5 Hz NC), 212.0
(s; COcis), 212.6 (s; COtrans); 19F NMR: d ˆ 131.73 (s; CF); (Z)-7a:
2
2
13C NMR: d ˆ 109.4 (d, JC,F ˆ 40 Hz; CN), 115.2 (d, JC,F ˆ 33 Hz; CCl),
Chem. Eur. J. 2001, 7, No. 4
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0704-0889 $ 17.50+.50/0
889

D. Lentz et al.
FULL PAPER
for C13H9CrF2NO5Si (%): calcd: C 41.38, H 2.40, N 3.71; found: C 41.60, H
2.63, N 3.71; MS (EI, 80 eV): m/z: 377, 321, 293, 265, 237, 203 (100%), 73,
52; IR (KBr): nÄ ˆ 2969 w, 2159 w, 2115 s, 2037 vs, 1982 vs, 1960 vs, 1939 vs,
1414 w, 1289 w, 1250 m, 1234 s, 1094 m, 1071 w, 1019 vw, 860 s, 847 s, 774 m,
762 w, 668 s, 657 vs, 647 vs, 584 w, 497 vw, 437 m cm 1; IR (pentane): nÄ ˆ
2113 vw, 2014 w, 1981 vs, 1950 m cm 1; Raman (solid): nÄ ˆ 2971 vw, 2908 w,
2328 vw, 2158 m, 2113 s, 2017 vs, 2002 s, 1984 w, 1958 vw, 1945 w, 1968 m,
1416 vw, 1288 s, 1259 vw, 1093, vw, 850 vw, 774 vw, 639 w, 610 w, 598 vw, 584
vw, 433 w, 385 m, 271 vw, 223 vw, 178 vw 108 m cm 1. (E)-8b: 1H NMR: d ˆ
CC Si), 132.3 (s; CF C), 136.3 (s; N CF), 203.9 (s; CN), 212.5 (s; COcis),
3
213.8 (s; COtrans); 19F NMR: d ˆ 146.94 (d, JF,F ˆ 127 Hz; CF CC),
3
125.30 (d, JF,F ˆ 127 Hz, N CF); (Z)-8d: 1H NMR: d ˆ 0.22 (s, 9H;
1
2
CH3); 13C NMR: d ˆ 0.9 (q, JC,H ˆ 121 Hz; CH3), 61.2 (d, JC,F ˆ 34 Hz;
CF CC), 85.4 (s; CC Si), 89.2 (s; CF CC), 100.5 (s; CC Si), 130.7 (dd,
1JC,F ˆ 247 Hz, 2JC,F ˆ 35 Hz CF C), 134.3 (dd, 1JC,F ˆ 270 Hz, 1JC,F ˆ 45 Hz,
N CF), 198.7 (s; CN), 212.6 (s; COcis), 213.7 (s; COtrans); 19F NMR: d ˆ
137.22 (s; CF CC), 104.18 (s; N CF).
(E/Z)-Pentacarbonyl(1-chloro-2-fluoro-pent-1-en-3-ynyl isocyanide)chro-
mium [(CO)5Cr(CNCClCFC2CH3)] (8e): The complex 8e was prepared
similarly to 8a using the Grignard reagent of propyne (4.5 mmol) and 4a
(500 mg, 1.6 mmol). After filtration through a pad of silica (2 cm) and
elution with pentane the solvent was removed in vacuum and the residue
was distilled under vacuum (0.1 Pa) at 30 to 408C using a microdistillation
apparatus with a small cup at the bottom of the condensation finger.
Compound 8e was isolated as yellow orange oil containing a mixture of the
E and Z isomer. Yield: 350 mg (66%). MS (EI, 70 eV) : m/z: 335, 279, 251,
223, 195 (100%), 160, 89, 71, 52; IR (KBr): nÄ ˆ 2954 vw, 2913 vw, 2118 m,
2102 s, 2070 s, 2026 s, 2011s, 1950 vs, 1633 m, 1575 w, 1439 vw, 1426 w, 1366
vw, 1263 vw, 1188 vw, 1159 m, 1056 m, 1040 m,10113 m, 885 w, 713 w, 651 s,
626 m, 515 s, 494 m, 468 m 442 m cm 1; IR (pentane): nÄ ˆ 2234 vw, 2216 w,
2029 m, 1976 vs, 1944 w cm 1; Raman (solid): nÄ ˆ 2924 w, 2847 vw, 2331 vw,
2230 m, 2116 s, 2028 s, 2005 s, 2946 w sh, 1620 s, 1427 vw, 1375 w, 1297 w,
1169 s, 1062 vw, 1039 vw, 1022 vw, 880 w, 826 vw, 732 vw, 664 w, 632 vw, 611
w, 572 vw, 546 w, 521 w, 438 w, 386 vs, 343 vw, 326 vw, 302 vw, 254 vw, 183
1
0.24 (s, 9H; CH3); 13C NMR: d ˆ 1.0 (q, JC,H ˆ 120 Hz; CH3), 88.5 (dd,
3
1
2JC,F ˆ 32 Hz, JC,F ˆ 10 Hz; CF CC), 117.0 (s; CC Si), 132.3 (dd, JC,F
ˆ
2
1
2
237 Hz, JC,F ˆ 58 Hz; CF C), 134.8 (dd, JC,F ˆ 252 Hz, JC,F ˆ 54 Hz, N
CF), 201.6 (d, JC,F ˆ 9 Hz, NC), 212.8 (s; COcis), 214.2 (s; COtrans); 19F
3
3
3
NMR: d ˆ 144.27 (d, JF,F ˆ 127 Hz; CF CC), 128.23 (d, JF,F ˆ 127 Hz,
N CF); (Z)-8b: H NMR: d ˆ 0.24 (s, 9H; CH3); 13C NMR: d ˆ 1.0 (q,
1
1JC,H ˆ 120 Hz; CH3), 89.2 (d, JC,F ˆ 31 Hz; CF CC), 113.3 (s; CC Si),
2
1
2
1
130.6 (dd, JC,F ˆ 246 Hz, JC,F ˆ 33 Hz; CF C), 133.1 (dd, JC,F ˆ 266 Hz,
2JC,F ˆ 45 Hz, N CF), 195.0 (s; NC), 213.0 (s; COcis), 214.1 (s; COtrans); 19F
3
3
NMR: d ˆ 134.80 (d, JF,F ˆ 3 Hz; CF-CC),
110.12 (d, JF,F ˆ 3 Hz,
N-CF).
(E/Z)-Pentacarbonyl(1-chloro-2-fluoro-6-trimethylsilyl-hex-1-en-3,5-diyn-
yl isocyanide)chromium [(CO)5Cr{CNCClCFC4Si(CH3)3}] (8c): Methyl-
lithium (1.5 mL of a 1.6m solution in diethyl ether) was added to a solution
of 1,4-bis(trimethylsilyl)butadiyne (585 mg, 3 mmol ) in diethyl ether
(10 mL) and stirred for 1 h at ambient temperature. Complex 4a (505 mg,
1.6 mmol) was added. After 5 min the reaction mixture was cooled with
liquid nitrogen. The reaction mixture was allowed to warm to ambient
temperature and the solvent was removed under vacuum. The dark brown
residue was extracted with pentane to give a dark orange-brown solution.
The solvent and volatile by-products were pumped off under vacuum at
308C. The residue was dissolved in pentane and filtered through a pad of
silica yielding a orange solution. After the solvent had been removed under
vacuum, 8c (335 mg, 50%) was isolated as a dark yellow solid (m.p. 508C)
containing a mixture of both isomers. MS (EI, 80 eV): m/z: 417, 374, 361,
333, 305, 277 (100%), 179, 156, 73, 52; IR (KBr): nÄ ˆ 2962 m, 2900 vw, 2116
vw, 2099 vw, 2067 m 2023 w, 1967 s, 1735 w 1636 w 1413 w, 1335 vw, 1249 s,
1
5
5
vw cm
;
1H NMR: d ˆ 2.157 (d, JH,F ˆ 4.6 Hz), 2.164 (d, JH,F ˆ 4.8 Hz);
the assignment of the 13C resonance is based on 19F,13C correlation spectra
(HMQC and HMBC); (E)-8e: 13C NMR: d ˆ 4.98 (q, 1JC,H ˆ 133 Hz), 68.06
(dq, 3JC,H ˆ 5 Hz, 2JC,F ˆ 37 Hz; CF CC), 105.24 (q, 2JC,H ˆ 11 Hz; CF CC),
2
1
108.22 (d, JC,F ˆ 57 Hz; CCl), 143.42 (d, JC,F ˆ 251 Hz; CF), 185 (s; CN),
213.58 (s; COcis), 215.12 (s; COtrans); 19F NMR: d ˆ 106.39 (qua, JH,F
ˆ
ˆ
5
4.6 Hz); (Z)-8e: 13C NMR: d ˆ 5.26 (q, JC,H ˆ 133 Hz), 68.41 (dq, JC,H
1
3
2
2
5 Hz, JC,F ˆ 35 Hz; CF CC), 104.17 (q, JC,H ˆ 11 Hz; CF CC), 107.72 (d,
2JC,F ˆ 46 Hz; CCl), 141.41 (d, 1JC,F ˆ 253 Hz; CF), 190.8 (s; CN), 213.39 (s;
COcis), 215.25 (s; COtrans); 19F NMR : d ˆ 101.94 (q, JH,F ˆ 4.8 Hz).
5
(E/Z)-Pentacarbonyl(1,2-difluoro-4-phenyl-but-1-en-3-ynyl isocyanide)-
chromium [(CO)5Cr(CNCFCFC2C6H5)] (8 f): Methylmagnesium bromide
(2 mmol, 3m solution in diethyl ether) was slowly added to a solution of
ethynylbenzene in THF (10 mL) at 08C leading to a colorless suspension
which was allowed to warm to ambient temperature and stirred for 90 min.
Addition of complex 2b (300 mg, 1.0 mmol) resulted in a brown reaction
mixture. After the mixture had been stirred for 30 min, pentane (100 mL)
was added to the dark brown suspension. After filtration through a pad of
silica the product was purified by crystallization from pentane at 308C.
The less soluble E isomer crystallized first as orange crystals (m.p. 1058C).
Almost pure Z isomer was obtained as yellow crystals (m.p. 628C) by
sublimation of the compound that remained in solution in vacuum (358C,
0.1 Pa). Elemental analysis for C16H5CrF2NO5 (%): calcd: C 50.41, H 1.32,
N 3.67; found: C 50.27, H 1.67, N 3.79; MS (EI, 80 eV): m/z: 381, 353, 325,
297, 269, 241 (100%), 189, 151, 52; IR (KBr): nÄ ˆ 2211 w, 2113 w, 2000 sh,
1941 vs br, 1489 w, 1444 vw, 1341 vw, 1267 m, 1184 m, 1168 m, 1074 m, 1024
vw, 820 w, 756 m, 685 s, 647 vs, 586 w, 522 w, 496 vw, 435 m cm 1; Raman
(solid): nÄ ˆ 3067 vw, 2208 s, 2157 vw, 2111 m, 2041 s, 1993 vs, 1946 w, 1670 vs,
1596 m, 1489 w, 1341 w, 1270s, 1167 m, 1074 w, 1025 vw, 998 w, 821 vw, 755
1176 w, 1101 vw, 1036 vw, 846 s, 765 m, 704 w, 648 s, 554 m, 446 w, 380
1
m cm 1; IR (n-hexane): nÄ ˆ 2114 vw, 2102 vw, 2018 w, 1977 s, 1946 vw cm
;
(E)-8c: 1H NMR: d ˆ 0.22 (s, 9H; CH3); 13C{19F} NMR: d ˆ 0.91 (q,
2
4
1JC,H ˆ 121 Hz; CH3), 61.99 (d, JC,F ˆ 38 Hz; CF CC), 85.20 (d, JC,F
ˆ
3
3
3 Hz; CC Si), 89.58 (d, JC,F ˆ 6 Hz; CF CC), 101.74 (m, JC,H ˆ 2.5 Hz,
2
1
5JC,F ˆ 0.8 Hz; CC Si), 111.61 (d, JC,F ˆ 55 Hz, N CCl), 142.19 (d, JC,F
ˆ
4
250 Hz; CF), 189.44 (d, JC,F ˆ 4 Hz; CN), 213.00 (s; COcis), 214.61 (s;
COtrans); 19F NMR: d ˆ 112.27; (Z)-8c: H NMR: d ˆ 0.24 (s, 9H; CH3);
1
2
13C NMR: d ˆ 0.84 (q, 1JC,H ˆ 121 Hz; CH3), 62.46 (d, JC,F ˆ 35 Hz; CF
4
3
CC), 85.48 (d, JC,F ˆ 4 Hz; CC Si), 90.40 (d, JC,F ˆ 5 Hz; CF CC), 101.47
(m, JC,H ˆ 2.8 Hz, JC,F ˆ 1.3 Hz; CC Si), 110.64 (d, 2JC,F ˆ 42 Hz, N CCl),
3
5
1
4
140.60 (d, JC,F ˆ 252 Hz; CF), 194.23.7 (d, JC,F ˆ 7 Hz; CN), 212.94 (s;
COcis), 214.63 (s; COtrans); 19F NMR: d ˆ 107.32 (s).
(E/Z)-Pentacarbonyl(1,2-difluoro-6-trimethylsilyl-hex-1-en-3,5-diynyl iso-
cyanide)chromium [(CO)5Cr{CNCFCFC4Si(CH3)3}] (8d): Methyllithium
(6.0 mmol, 1.5m in diethyl ether) was added to a solution of bis(trimethyl
silyl)butadiyne (1552 mg, 8.0 mmol) in diethyl ether (30 mL). After the
solution had been stirred for 3 h at ambient temperature, 4b (1495 mg,
5.0 mmol) was added. After 15 min water (0.2 mL) was added to stop the
reaction. The remaining suspension was diluted with pentane (30 mL) and
filtered through a pad (5 cm) of silica. The solvent was removed in vacuum
at 208C and the residue purified by column chromatography (silica/
pentane) and sublimation in vacuum (458C, 0.1 Pa). Yield: 2113 mg
(5.8 mmol, 72%) of both isomers as a yellow solid. M.p. 438C; elemental
analysis for C15H9CrF2NO5Si (%): calcd: C 44.89, H 2.26, N 3.49; found: C
45.01, H 2.59, N 4.02; MS (EI, 80 eV): m/z: 401, 345, 289, 261(100%), 73, 52;
IR (KBr): nÄ ˆ 2963 vw, 2195 w, 2114 m, 2105 m, 2023 vs, 2004 vs, 1948 vs,
1704 vw, 1653 m, 1345 w, 1274 s, 1252 m, 1132 m, 1004 w, 985 w, 958 m, 848 s,
762 w, 706 m, 648 s, 540 w, 436 m cm 1; IR (pentane): nÄ ˆ 2199 vw, 2113 sh,
2106 vw, 2012 w, 1982 vs, 1951 sh m cm 1; Raman (solid): nÄ ˆ 2965 vw, 2903
vw, 2194 vs, 2112 w, 2016 m, 1997 s, 1945 w, 1653 s, 1342 w, 1332 w, 1267 m,
1132 w, 985 vw, 957 vw, 849 vw, 762 vw, 703 w, 631 m, 604 m, 574 vw, 540, vw,
vw, 688vw, 647 w, 598 m, 522 w, 432 m, 388 vs, 365 w, 334 vw, 250 vw, 177 w,
1
116 vs cm
;
1H NMR: d ˆ 7.52 ± 7.32 (m, 5H; Ph); (E)-8 f: IR (pentane):
1
nÄ ˆ 2212 w, 2114 vw, 2014 m, 1981 vs, 1950 m cm
;
13C{1H} NMR: d ˆ 74.5
2
3
3
4
(dd, JC,F ˆ 33 Hz, JC,F ˆ 11 Hz; CF CC), 108.1 (dd, JC,F ˆ 12 Hz, JC,F
ˆ
6 Hz; CF CC), 120.3 (s; Ph C1), 128.6 (s; Ph C2), 130.4 (s; Ph C4), 131.7
1
2
(s; Ph C3), 132.8 (dd, JC,F ˆ 236 Hz, JC,F ˆ 58 Hz; CF CC), 134.0 (dd,
1JC,F ˆ 251 Hz, 2JC,F ˆ 55 Hz, N CF), 201.3 (s; NC), 212.8 (s; COcis), 214.2 (s;
COtrans); 13C {19F} NMR: (3JC,H ˆ 5 Hz; CF CC), (2JC,H ˆ 8 Hz, Ph C1),
(1JC,H ˆ 163 Hz, 2JC,H ˆ 7 Hz, Ph C2), (1JC,H ˆ 163 Hz, 2JC,H ˆ 7 Hz, Ph C4),
(1JC,H ˆ 164 Hz, JC,H ˆ 7 Hz, Ph C3); 19F NMR: d ˆ 143.42 (d, JF,F
ˆ
2
3
3
126 Hz; CF-CC), -128.35 (d, JF,F ˆ 126 Hz, N CF); (Z)-8 f: IR (pentane):
1
nÄ ˆ 2212 w, 2115 w, 2018 m, 1981 vs, 1950 w cm
;
13C{1H} NMR: d ˆ 75.0 (d,
2JC,F ˆ 33 Hz; CF CC), 104.5 (dd, 3JC,F ˆ 7 Hz, 4JC,F ˆ 6 Hz; CF CC), 119.9
1
(s; Ph C1), 128.7 (s; Ph C2), 130.5 (s; Ph C4), 131.0 (dd, JC,F ˆ 245 Hz,
507 vw, 485 w, 432 m, 385 s, 331 vw, 272 vw, 237 vw, 219 vw, 178 vw cm 1. (E)-
2JC,F ˆ 58 Hz; CF CC), 131.9 (s; Ph C3), 132.5 (dd, JCF ˆ 266 Hz, JC,F
ˆ
1
2
8d: 1H NMR: d ˆ 0.24 (s, 9H; CH3); 13C{19F} NMR: d ˆ 0.9 (q, JC,H
ˆ
46 Hz, N CF), 195.7 (s; NC), 212.9 (s; COcis), 214.1 (s; COtrans); 13C{19F}
1
121 Hz; CH3), 60.2 (s; CF CC), 85.5 (s; CC Si), 92.8 (s; CF CC), 101.7 (s;
NMR: (3JC,H ˆ 5 Hz; CF CC), (2JC,H ˆ 8 Hz, Ph C1), (1JC,H ˆ 161 Hz,
890
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0704-0890 $ 17.50+.50/0
Chem. Eur. J. 2001, 7, No. 4

Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
2JC,H ˆ 7 Hz, Ph C2), (1JC,H ˆ 162 Hz, 2JC,H ˆ 8 Hz, Ph C4); 19F NMR : d ˆ
O), 193.2 (NC), 213.4 (s; COcis), 215.3 (s; COtrans); 19F NMR: d ˆ 155.82
(d, 3JF,F ˆ 114 Hz), 114.44 (d, 3JF,F ˆ 114 Hz); (Z)-8i: 1H NMR: d ˆ 3.92 (s,
133.62 (s; CF CC), 110.73 (s; N CF).
1
3H; OCH3); 13C NMR: d ˆ 59.7 (q, JC,H ˆ 149 Hz; OCH3), 118.5 (dd,
(E/Z)-Pentacarbonyl(1-chloro-2-fluoro-prop-1-enyl isocyanide)chromium
[(CO)5Cr(CNCClCFCH3)] (8g): Methylmagnesium bromide (1.5 mL,
3.0 mmol, 2m in THF) was added to a solution of 4a (630 mg, 2.0 mmol)
in diethyl ether (30 mL) and heated to reflux. After 15 min pentane
(100 mL) was added and the solution was filtered through a pad of silica.
The solvent was removed in vacuum at 208C and the residue was purified
by PTLC. The first fraction contained 4a, the second the product 8g, which
was eluted with dichloromethane and sublimed in vacuum (258C, 0.1 Pa)
yielding both isomers as a light yellow solid (443 mg, 1.4 mmol; 71%). M.p.
438C; elemental analysis for C9H3CrClFNO5 (%): calcd: C 34.69, H 0.97, N
4.50; found: C 34.92, H 1.80, N 4.94; MS (EI, 80 eV): m/z: 311, 255, 227, 199,
171 (100%), 78, 71, 52; IR (KBr): nÄ ˆ 2129 s, 2058 vs, 1945 vs, 1666 m, 1428
w, 1384 m, 1267 m, 1260 m, 1166 s, 1143 m, 1036 s, 952 m, 943 m, 918 m, 678 s,
653 vs, 633 m, 535 vw, 517 vw, 489 vw, 446 s cm 1; IR (pentane): nÄ ˆ 2118 m,
2037 s, 2007 m, 1975 vs, 1942 m cm 1; Raman (solid): nÄ ˆ 2974 vw, 2934 w,
2325 vw, 2123 m, 2035 s, 1993 m, 1988 m, 1972 m, 1927 w, 1667 w, 1434 vw,
1JCF ˆ 241 Hz, 2JCF ˆ 58 Hz; N CF), 150.8 (dd, 1JC,F ˆ 286 Hz, 2JC,F ˆ 42 Hz;
CF O), 193.0 (NC), 213.4 (s; COcis), 215.1 (s; COtrans); 19F NMR: d ˆ
3
3
150.20 (d, JF,F ˆ 18 Hz), 103.93 (d, JF,F ˆ 18 Hz).
Pentacarbonyl(1,2,2-trifluoro-2-methoxyethen-1-yl isocyanide)chromium
[(CO)5Cr(CNCHFCF2OCH3)] (9): Potassium carbonate (28 mg, 0.2 mmol)
was added to a suspension of 4b (415 mg, 1.5 mmol) in methanol (4 mL).
Within a few minutes the yellow suspension turned into dark brown. After
15 min the mixture was placed on a pad of silica and the product fraction
was eluted with dichloromethane. The solvent was removed in vacuum at
208C leaving 9 as a yellow oil. Yield: 387 mg (1.2mmol, 84%); m.p. 148C;
C9H4CrF2NO6 (%): calcd C 32.65, H 1.22, N 4.23; found: C 32.64, H 1.52, N
4.73; MS (EI, 80 eV): m/z ˆ 331, 303, 275, 247, 219, 191 (100%), 78, 52; IR
(KBr): nÄ ˆ 2970 w, 2871 vw, 2145 s, 2045 vs, 1946 b, 1457 m, 1375 w, 1335 s,
1303 m, 1259 s, 1235 s, 1161 s, 1124 m, 1091 vs, 1051 s, 1021 m, 974 m, 826 m,
737 m, 723 m, 653 vs, 590 m, 567 w, 531 w, 496 w, 443s cm 1; Raman (solid):
nÄ ˆ 2971 vw, 2872 vw, 2145 w sh, 2127 w, 2040 m, 2005 s, 1943 w sh, 1458 vw,
1384 w, 1259 w, 1166 m. 1141 w, 1036 vw, 916 vw, 671 m, 651 vw, 633 m, 562
1
vw, 547 w, 535 vw, 517 vw, 501 vw, 444 m, 390 vs, 326 vw, 262 w, 179 w cm
.
1376 vw, 1335 w, 1259 vw, 1090 vw, 973 vw, 826 vw, 804 vw, 736 vw, 722 vw,
(E)-8g: 1H NMR: d ˆ 2.24 (d, 3JH,F ˆ 16 Hz, 3H; CH3); 13C NMR: d ˆ 15.8
665, vw, 590 vw, 568 vw, 534 vw, 497 vw, 441 w, 386 vs, 321 vw, 259 vw cm
;
1
1
2
(dq, JC,F ˆ 131 Hz, JC,F ˆ 24 Hz; CH3), 102.7 (not resolved, CCl), 159.3
1H NMR: d ˆ 3.72 (s; 3H, CH3), 5.53 (d, 2JH,F ˆ 50 Hz, 1H; CHF); 13C{1H}
NMR: d ˆ 51.5 (t, 3JC,F ˆ 7 Hz; CH3), 86.8 (dt, 1JC,F ˆ 221 Hz, 2JC,F ˆ 42 Hz;
CFH), 118.2 (dt, 1JC,F ˆ 270 Hz, 2JC,F ˆ 27 Hz; CF2), 188.5 (s; CN), 213.4 (s;
1
2
(dq, JC,F ˆ 267 Hz, JC,H ˆ 8 Hz; CF), 184.9 (s; CN), 213.5 (s; COcis), 215.2
(s; COtrans);19F NMR: d ˆ 97.91 (q, 3JF,H ˆ 16 Hz; CF); (Z)-8g: 1H NMR:
d ˆ 2.17 (d, 3JH,F ˆ 16 Hz, 3H; CH3); 13C NMR: d ˆ 15.1 (dq, 1JC,F ˆ 131 Hz,
1
COcis), 214.5 (s; COtrans); 13C{19F} NMR: d ˆ 51.5 (q, JC,F ˆ 149 Hz; CH3),
2JC,F ˆ 24 Hz; CH3), 102.2 (not resolved, CCl), 158.1 (dq, JC,F ˆ 271 Hz,
86.8 (d, 1JC,H ˆ 179 Hz; CFH), 118.2 (s; CF2), 188.5 (s; CN), 213.4 (s; COcis),
1
2JC,H ˆ 8 Hz; CF), 184.8 (s; CN), 213.6 (s; COcis), 215.6 (s; COtrans); 19F
214.5 (s; COtrans); 19F NMR: d ˆ 159.70 (dt, JF,H ˆ 50 Hz, JF,F ˆ 12 Hz;
2
3
3
NMR: d ˆ 93.35 (q, JF,H ˆ 16 Hz; CF).
CHF), 92.19 (ddd, 2JF,F ˆ 138 Hz, 3JF,F ˆ 12 Hz, 3JF,H ˆ 3 Hz; CF2), 90.81
2
3
(dd, JF,F ˆ 138 Hz, JF,F ˆ 12 Hz; CF2).
(E/Z)-Pentacarbonyl(1,2-difluoro-prop-1-enyl
isocyanide)chromium
[(CO)5Cr(CNCFCFCH3)] (8h): Compound 8h was prepared similarly to
8g by using 4b (600 mg, 2.0 mmol).Yield: 524 mg (1.8 mmol, 89%) of both
[(CO)5Cr(CNCFCFC2CFCFNC)Cr(CO)5] (10): n-Butyllithium (1.5 mL,
3.0 mmol, 2m in pentane) was slowly added to tributyl(ethynyl)stannane
(945 mg, 3.0 mmol) dissolved in diethyl ether (40 mL) at 508C. After 1 h
the solution was allowed to warm to 208C and 4b (900 mg, 3.0 mmol) was
added. The solution was allowed to warm to ambient temperature over
30 min, pentane (20 mL) was added, and the reaction mixture filtered
through pad of silica. Crystallization from pentane yielded the Z,Z isomer
as an orange solid, while 4b and small amounts of the other isomers were
still dissolved. Yield: 100 mg (0.2 mmol, 11%); elemental analysis for
C18Cr2F4N2O10 (%): calcd: C 37.01, N 4.80; found: C 37.76, N 5.32; MS (EI,
80 eV) : m/z: 584, 472, 444, 416, 388, 360, 332, 304 (100%), 71, 52; (Z,Z)-10:
m.p. 1218C; IR (KBr): nÄ ˆ 2115 m, 2040 vs, 2005 vs, 1943 vs, 1666 m, 1373 w,
1275 s, 1219 s, 1108 m, 862 vw, 797 m, 695 m, 645 vs, 586 w, 565 w, 499 vw, 472
vw, 440 m, 424 m, 386 vw, 349 vw cm 1; IR (pentane): nÄ ˆ 2114 vw, 2017 w
sh, 2008 w, 1987 vs, 1970 s cm 1; Raman (solid): nÄ ˆ 2207 w, 2114 w, 2040 vw,
1998 vs, 1975 vw, 1948 m, 1668 m, 1658 m, 1290 m, 1201 m, 1109 vw, 1046 vw,
isomers as
a colorless solid. M.p. 468C; elemental analysis for
C9H3CrF2NO5 (%): calcd: C 36.63, H 1.03, N 4.75; found: C 36.82, H
1.56, N 5.12; MS (EI, 80 eV): m/z: 295, 267, 239, 211, 183, 155 (100%), 78,
71, 52; IR (KBr): nÄ ˆ 2927 vw, 2126 s, 2055 vs, 1939 vs, 1729 s, 1431 w, 1388
m, 1278 w, 1239 s, 1228 m, 1119 m, 1035 vw, 966 w, 734 m, 649 vs, 562 w, 525
vw, 489 w, 443 m, 386 vw cm 1; IR (pentane): nÄ ˆ 2116 w, 2055 w, 2031 m,
2009 w, 1976 vs, 1945 w cm 1; Raman (solid). nÄ ˆ 2931 vw, 2121 m, 2035 s,
1998 s, 1966 w, 1935 vw, 1730 w, 1443 vw, 1388 w, 1279 w, 1238 w, 1121 vw,
1032 vw, 732 w, 669 w, 647 vw, 562 w, 533 vw, 440 w, 390 vs, 346 vw, 265 vw,
1
209 w cm 1. H NMR: d {2nd isomer} ˆ 2.16 {2.12} (s; 3H, CH3); (E)-8h:
1
13C {19F} NMR: d ˆ 13.0 (q, JC,H ˆ 130 Hz; CH3), 130.0 (s; CN CF), 147.8
(q, 2JC,H ˆ 8 Hz; CF CH3), 193.3 (s; CN), 213.3 (s; COcis), 215.0 (s; COtrans);
2
3
13C {1H} NMR: d ˆ 13.0 (dd, JC,F ˆ 23 Hz, JC,F ˆ 3 Hz; CH3), 147.8 (dd,
1JC,F ˆ 255 Hz, JC,F ˆ 56 Hz; CF CH3); 19F NMR: d ˆ 143.09 (q, JF,F
ˆ
2
3
3
3
126 Hz, N CF), 134.44 (dq, JF,F ˆ 126 Hz, JF,H ˆ 16 Hz, CF-CH3); (Z)-
795 vw, 701 vw, 651 vw, 586 w, 564 vw, 527 vw, 499 vw, 470 vw, 429 w, 387 vs,
8h: 13C{19F} NMR: d ˆ 13.0 (q, JC,H ˆ 130 Hz; CH3), 128.8 (s; CN
360 vw, 288 vw, 237 w, 163 w cm
;
13C NMR: d ˆ 89.6 (d, 2JC,F ˆ 36 Hz; CF
1
1
2
1
2
1
CF),144.7 (q, JC,H ˆ 8 Hz; CF CH3),191.7 (s; CN), 213.3 (s; COcis), 214.7
CC), 129.6 (dd, JC,F ˆ 245 Hz, JC,F ˆ 35 Hz; CF CC), 134.5 (dd, JC,F
ˆ
(s; COtrans); 13C {1H} NMR: d ˆ 13.0 (d, JC,F ˆ 23 Hz; CH3), 144.7 (dd,
272 Hz, JC,F ˆ 43 Hz, N CF), 201.7 (s; CN), 213.0 (s; COcis), 213.6 (s;
COtrans); 19F NMR: d ˆ 140.95 (s; CF CC), 100.56 (s; N CF); (E,E)-10:
2
2
1JC,F ˆ 260, JC,F ˆ 21, CF CH3); 19F NMR: d ˆ 126.05 (q, JF,H ˆ 16 Hz;
2
3
3
3
CF-CH3), 124.88 (s; N CF).
19F NMR: d ˆ 140.04 (d, JF,F ˆ 124 Hz; CF CC), 120.50 (d, JF,F
ˆ
124 Hz, N CF); (E,Z)-10: 19F NMR: d ˆ 151.31 (d, JC,F ˆ 126 Hz,(E)-
3
[(CO)5Cr(CNCFCFOCH3)] (8i): Complex 8i was the only isolated product
in experiments to deprotonate propiolic acid methyl ester with LDA and
reaction with 4b. Propiolic acid methyl ester (0.9 mL, 10.0 mmol) was
dissolved in diethyl ether (30 mL) at 08C and lithium diisopropylamide
(4 mL, 8.0 mmol, 2m in THF) was added. After five minutes 4b (1495 mg,
5.0 mmol) was added. The reaction mixture was filtered through a pad of
silica after 10 min. The solvent was removed in vacuum at 208C and the
residue purified by column chromatography (silica, pentane) and crystal-
lized from pentane at 308C. Yield: 701 mg (2.3 mmol, 45%) of both
isomers as a white solid. M.p. 578C; elemental analysis for C9H3CrF2NO6
(%): calcd: C 34.75, H 0.97, N 4.50; found: C 34.81, H 1.57, N 5.04; MS (EI,
80 eV) : m/z: 311, 283, 255, 227, 199, 171 (100%), 78, 52; IR (KBr): nÄ ˆ 2960
w, 2864 vw, 2123 s, 2046 vs, 1944 vs, 1745 m, 1453 m, 1384 vw, 1290 m, 1266 s,
3
ˆ
ˆ
CF CF C), 141.97 (s; (Z)-CF CF C), 140.04 (d, JC,F ˆ 126 Hz, (E)-
ˆ
ˆ
CF CF C), 101.95 (s; (Z)-CF CF C).
(E/Z)-Pentacarbonyl(1-chloro-2-fluoro-but-1-en-3-ynyl isocyanide)chro-
mium [(CO)5Cr(CNCClCFC2H)] (11a): Potassium carbonate (40 mg,
0.3 mmol) was added to a suspension of 8a (709 mg, 1.8 mmol) in methanol
(4 mL) at ambient temperature. The desilylation was completed within a
few minutes and the black solution was purified by PTLC (silica 1mm,
pentane). The first fraction was eluted with dichloromethane. The solvent
was evaporated in vacuum at 208C and the residue sublimed in vacuum
to yield 426 mg (1.3 mmol, 74%) of both isomers as a yellow, air- and light-
sensitive solid. Elemental analysis for C10HCrClFNO5 (%): calcd: C 37.35,
H 0.31, N 4.36; found: C 37.20, H 1.58, N 4.60; MS (EI, 80 eV): m/z: 321, 293,
265, 237, 209, 181 (100%), 78, 52; IR (KBr): nÄ ˆ 3295 m, 2119 m, 2035 vs,
1945 br, 1609 w, 1264 w, 1176 m, 1034 vw, 977 w, 936 w, 678 s, 651 vs, 557 vw,
526 m, 497 vw, 442 m cm 1; IR (pentane): nÄ ˆ 2117 w, 2021 m, 1978 vs, 1947
w cm 1; Raman (solid): nÄ ˆ 2335 vw, 2105 m, 2029 m 2015 s, 2004 s, 1941 w,
1671 vw, 1624 m, 1271 w, 1170 m, 976 vw, 933 vw, 684 sh, 673 w, 606 vw, 558
m, 528 vw, 437 w, 388 m, 335 vs, 288 vw, 272 vw, 208 vw, 140 m cm 1; (E)-
1178 w, 1124 s, 950 m, 757 m, 653 vs, 576 w, 544 w, 494 vw, 441 m cm 1; IR
1
(pentane): nÄ ˆ 2116 w, 2036 m, 1999 vw, 1975 vs, 1944 w, 1746 w cm
;
Raman (solid): nÄ ˆ 2960 vw, 2119 s, 2035 s, 1999 m, 1970 w, 1938 vw, 1744 w,
1260 m. 1126 vw, 949 vw, 755 w, 668 w, 650 vw, 634 vw, 574 vw, 544 vw, 495
vw, 440 w, 391 vs, 265 vw, 210 vw cm 1. (E)-8i: H NMR: d ˆ 3.93 (s, 3H;
1
1
1
OCH3); 13C NMR: d ˆ 59.8 (q, JC,H ˆ 149 Hz, OCH3), 119.0 (dd, JC,F
ˆ
2
1
2
4
236 Hz, JC,F ˆ 67 Hz, N CF), 151.5 (dd, JC,F ˆ 277 Hz, JC,F ˆ 48 Hz; CF
11a: 1H NMR: d ˆ 4.00 (d, JH,F ˆ 3 Hz, 1H; CC H); 13C NMR: d ˆ 70.9
Chem. Eur. J. 2001, 7, No. 4
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0704-0891 $ 17.50+.50/0
891

D. Lentz et al.
FULL PAPER
2
2
1
3
2
2
(dd, JC,H ˆ 51 Hz, JC,F ˆ 27 Hz; CCH), 93.2 (dd, JC,H ˆ 261 Hz, JC,F
ˆ
ˆ
102.05 (d, JC,F ˆ 48 Hz; CCl)/101.38 (d, JC,F ˆ 61 Hz; CCl), 156.61 (d,
2
1
3
1
5 Hz; CH), 110.8 (d, JC,F ˆ 52 Hz; CCl), 142.2 (dd, JC,F ˆ 251 Hz, JC,H
1JC,F ˆ 254 Hz; CF)/155.76 (d, JC,F ˆ 249 Hz; CF), 187.44/194.53 (s; CN),
5 Hz; CF), 189.0 (s; CN), 213.2 (s; COcis), 214.5 (s; COtrans); 19F NMR: d ˆ
110.54 (d, 4JF,H ˆ 3 Hz; CF); (Z)-11a: 1H NMR: d ˆ 3.97 (d, 4JH,F ˆ 4 Hz,
197.89 (br, Co(CO)), 213.41/213.06 (s; COcis), 215.27/214.66 (s; COtrans); 19
NMR: d (major/minor isomer) ˆ 90.42/ 96.82 (s).
F
1H, CC H); 13C NMR: d ˆ 71.3 (dd, JC,H ˆ 51 Hz, JC,F ˆ 25 Hz , CCH),
2
2
Trifluoroethenyl isocyanide (13b): The pyrolysis tube (l ˆ 500 mm, od ˆ
16 mm) of an apparatus as shown in Figure 5 was heated to 3508C without
cooling the traps and evacuated for 2 h. Then the oven temperature was
lowered to about 200 to 2408C, the first trap was cooled to 788C, and a
1
3
2
94.2 (dd, JC,H ˆ 261 Hz, JC,F ˆ 5 Hz; CH), 109.9 (d, JC,F ˆ 40 Hz; CCl),
140.4 (dd, 1JC,F ˆ 254 Hz, 3JC,H ˆ 6 Hz , CF), 193.7 (s; CN), 213.0 (s; COcis),
214.6 (s; COtrans); 19F NMR: d ˆ 105.50 (d, JF,H ˆ 4 Hz; CF).
4
(E/Z)-Pentacarbonyl(1,2-difluoro-
but-1-en-3-ynyl isocyanide)chromium
[(CO)5Cr(CNCFCFC2H)]
(11b):
Compound 11b was prepared similar-
ly to 11a by using 8b (755 mg,
2.0 mmol). Yield: 531 mg (1.7 mmol,
87%) of both isomers as a air- and
light-sensitive brown solid. Elemental
analysis for C10HCrF2NO5 (%): calcd:
C 39.35, H 0.33, N 4.59; found: C
39.62, H 0.78, N 4.59; MS (EI, 80 eV) :
m/z: 305, 277, 249, 221, 193, 165
(100%), 90, 71, 52; IR (pentane): nÄ ˆ
3309 m, 2119 w, 2110 w, 2014 m, 1981
vs, 1951 s cm 1; Raman (solid): nÄ ˆ
2105 s, 2038 m, 2028 m, 1998 s, 1989
s, 1948 w, 1667 m, 1292 m, 1249 vw,
1227 w, 1083 vw, 730 vw, 650 vw, 604 w,
527 vw, 433 w, 388 s, 285 vw, 232 vw,
Figure 5. Schematic representation of the pyrolysis apparatus.
4
190 w, 154 w, 116 vs cm 1; (E)-11b: 1H NMR: d ˆ 4.11 (dd, JH,F ˆ 3 Hz,
test tube containing a small magnetic stirring bar (which allowed the
adjustment of the sample tube within the pyrolysis tube) was charged with
pentacarbonyl(trifluoroethenyl isocyanide)chromium (4b; 1.9 g, 6.4 mmol)
and placed into the pyrolysis tube by opening the Teflon fitting at the rear
end. The apparatus was then evacuated immediately. Unreacted 4b was
5JH,F ˆ 3 Hz, 1H, CC-H); 13C NMR: d ˆ 69.2 (ddd, JC,H ˆ 51 Hz, JC,F
ˆ
ˆ
2
2
3
1
2
3
35 Hz, JC,F ˆ 10 Hz; CCH), 96.2 (ddd, JC,H ˆ 260 Hz, JC,F ˆ 12 Hz, JC,F
1
2
3
6 Hz; CH), 132.2 (ddd, JC,F ˆ 237 Hz, JC,F ˆ 58 Hz, JC,H ˆ 5 Hz; CF C),
1
2
3
135.9 (dd, JC,F ˆ 254 Hz, JC,F ˆ 53 Hz, N CF), 202.7 (d, JC,F ˆ 9 Hz, NC),
212.7 (s; COcis), 213,9 (s; COtrans); 19F NMR: d ˆ 147.53 (dd, 3JF,F ˆ 127 Hz,
trapped at
788C. An optimum pyrolysis temperature (2508C) and
4JF,H ˆ 3 Hz; CF CC),
127.41 (d, JF,F ˆ 127 Hz, N CF); (Z)-11b:
3
pressure (0.1 to 1 Pa) was obtained by adjusting the position of the sample
using a magnet. After a few hours all of 4b had sublimed. The product 13b
was collected in a trap cooled to 1968C. The amount of 13b (2 to 4 mmol)
obtained in the 1968C trap was sufficient for vapor pressure determi-
nation measurements, which gave an extrapolated boiling point of 18(6)8C.
The data fit the linear equation lnp ˆ 24736(442)/RT‡17.1301(2562)
giving an enthalpy of vaporization of 24.7(5) kJmol 1. An IR spectrum was
recorded in a 100 mm infrared gas cell. To record the NMR spectra the
compound was condensed into an ordinary glass NMR tube containing
deuterochloroform (0.7 mL) and sealed under vacuum. NMR spectra were
recorded at ambient temperature. 19F NMR (CDCl3): d ˆ 101.5 (dd,
4
5
1H NMR: d ˆ 3.92 (dd, JH,F ˆ 3 Hz, JH,F ˆ 1 Hz, 1H, CC-H); 13C NMR:
2
2
1
d ˆ 70.1 (dd, JC,H ˆ 51 Hz, JC,F ˆ 34 Hz; CCH), 92.8 (ddd, JC,H ˆ 261 Hz,
4
1
2
3JC,F ˆ 6 Hz, JC,F ˆ 6 Hz; CH), 130.5 (ddd, JC,F ˆ 246 Hz, JC,F ˆ 34 Hz,
3JC,H ˆ 5 Hz; CF C), 133.7 (dd, JC,F ˆ 265 Hz, JC,F ˆ 43 Hz, N CF), 197.8
1
2
(s; NC), 212.9 (s; COcis), 213.8 (s; COtrans), 19F NMR: d ˆ 137.82 (d, 4JF,H
ˆ
3 Hz; CF CC), 108.32 (s; N CF).
(E/Z)-Pentacarbonyl(1,2-difluoro-hex-1-en-3,5-diynyl isocyanide)chromi-
um [(CO)5Cr(CNCFCFC4H)] (11d): Compound 11d was prepared sim-
ilarly to 11a by using 8d (160 mg, 0.4 mmol) but was obtained in small
yields. (E)-11d: 1H NMR: d ˆ 3.01 (d, JH,F ˆ 2 Hz, 1H; C H); 1H
13C NMR(HMQC): d ˆ 80 (1JC,H ˆ 245 Hz; CC H); 19F NMR: d ˆ
3
2
3
2JF,F ˆ 53 Hz, JF,F ˆ 50 Hz),
112.5 (dd, JF,F ˆ 53 Hz, JF,F ˆ 113 Hz),
3
3
1
157.6 (dd, JF,F ˆ 50 Hz, JF,F ˆ 113 Hz, JN,F ˆ 10 Hz); IR (gaseous): nÄ ˆ
3
3
148.50 (dd, JF,F ˆ 126 Hz; CF CC), 124.43 (d, JF,F ˆ 126 Hz, N CF);
(Z)-11d: 1H NMR: d ˆ 2.91 (dd, JH,F ˆ 1 Hz, JH,F ˆ 2 Hz, 1H, C H); 1H
2111 s (CN), 1801 s (C C), 1363 s, 1279 vs, 1212 m, 1147 vs, 936 w cm 1; MS
ˆ
‡
‡
‡
(80 eV, EI): m/z: 107 [M] , 88 [C3F2N] , 76 [C2F2N] and smaller fragment
13C NMR(HMQC, HMBC): d ˆ 66 (2JC,H ˆ 44 Hz; CC H), 79 (1JC,H
ˆ
‡
ions; high-resolution MS: [M] calcd: 106.99829, found: 106.99827.
245 Hz; CC H), 89 (CCC H); 19
F
13C NMR(HMQC): d ˆ 60.5 (CF CC),
ˆ
130.3 (CF CC), 134.4 (N CF); 19F NMR: d ˆ 138.64 (s; CF CC),
(E/Z)-1,2-Dichloro-2-fluoroethenyl isocyanide [CN CCl CFCl] (13c):
Experimental conditions were as described above, using precursor 4c and
a pyrolysis temperature of 2508C. The pyrolysis products were trapped at
103.00 (s; N CF).
Octacarbonyl{m2-pentacarbonyl[(E/Z)-1-chloro-2-fluoropent-1-en-3-ynyl iso-
ˆ
1968C. IR (gaseous): nÄ ˆ 2104 vs (CN), 1654 s (C C), 1280 w, 1215 s, 1207
cyanide]chromium}dicobalt
[Co2(CO)6{m2-(CO)5Cr(CNCClCFC2CH3)}]
s, 1153 m, 1147 m, 1120 s, 1111 s, 962 w, 931 m, 876 s, 786 w, 780 w, 729
(12): Octacarbonyldicobalt (150 mg, 0.44 mmol) and 8e (150 mg,
0.45 mmol) were dissolved in n-hexane (5 mL) and stirred at ambient
temperature for 12 h. The solution was filtered through thin pad of silica
using hexane as eluent. Most of the solvent was removed under vacuum.
Crystallization at 308C yielded 12 (180 mg, 66%) as dark red crystals
(m.p. 1028C) as a mixture of the E and Z isomer. Elemental analysis for
C17H3ClCo2CrFNO11 (%): calcd: C 32.85, H 0.49, N 2.25; found: C 32.79, H
1.34, N 2.71, MS (EI, 80 eV) : m/z: 621, 593, 565, 537, 509, 481, 453, 425, 397,
369, 341, 313, 279, 220, 195, 108, 80, 52; IR (KBr): nÄ ˆ 2920 vw, 22852 vw,
2117 w, 2101 s, 2027 s, 1951 vs, 1633 w, 1575 vw, 1439 vw, 1426 vw, 1264 vw
1159 w, 1057 w, 1040 vw, 1014 vw, 851 vw, 714 vw, 653, s, 627 w, 516 m, 495 m,
w cm 1; MS (80 eV, EI): m/z: 139 [M] , 104 [C3ClFN] and smaller
‡
‡
‡
fragment ions; high-resolution MS: [M] calcd: 138.93913, found:
138.93919.
1-Chloro-2,2-difluroethenyl isocyanide (13a): Experimental conditions
were as described above, using precursor 4a and a pyrolysis temperature
of 2508C. The pyrolysis products were trapped at 1968C. IR (gaseous):
ˆ
nÄ ˆ 2111 vs (CN), 1744 vs (C C), 1354 s, 1346 s, 1173 s, 1056 vs, 1051
1
vs cm
;
19F NMR (CD2Cl2, 508C): d ˆ 79.9 (d, 2JF,F ˆ 7 Hz), 86.6 (d,
2JF,F ˆ 7 Hz); 13C NMR (CD2Cl2, 508C): d ˆ 157.1 (dd, JC,F ˆ 292 Hz,
1
1JC,F ˆ 301 Hz), 175.5 (s; CN).
468 w, 445 m cm 1; IR (hexane): nÄ ˆ 2102 w, 2066 w, 2045 m, 2035 m, 2020
(E/Z)-1,2-Difluoroethenyl isocyanide [CN CF CFH] (14): Experimental
ˆ
1
vw, 1974 s cm
;
1H-NMR: d (major/minor isomer) ˆ 2.772/2.854; the
conditions were as described above, using precursor 6 (250 mg, 0.9 mmol)
and a pyrolysis temperature of 2308C. The pyrolysis products were purified
by fractional condensation and trapped at 1968C. MS (EI, 80 eV): m/z: 89
assignment of the 13C resonance is based on 19F,13C correlation spectra
(HMQC and HMBC) and signal intensities; 13C NMR: d (major/minor
1
1
isomer) ˆ 22.35 (q, JC,H ˆ 131 Hz)/21.79 (q, JC,H ˆ 131 Hz), 69.10 (d,
(100%), 70, 51; IR (gas): nÄ ˆ 3128 w, 2106 vs, 1720 w, 1558 w, 1332 m, 1322
2JC,F ˆ 45 Hz; CF CC)/68.84 (d, JC,F ˆ 48 Hz; CF CC), 94.89 (m, JC,H
ˆ
m, 1243 vs, 1230 vs, 1186 vs, 1179 vs, 1171 vs, 903 vw, 831 w, 795 m cm
,
2
2
1
3
2
3
9 Hz, JC,F ˆ 9 Hz; CF CC)/ 93.74 (m, JC,H ˆ 9 Hz, JC,F ˆ 9 Hz; CF CC),
additional absorption due to HCCNC 15 were observed at 3339, 2219, 2037,
892
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001 0947-6539/01/0704-0892 $ 17.50+.50/0 Chem. Eur. J. 2001, 7, No. 4

Halogenated Ethenyl Isocyanide Chromium Complexes
881±893
2
3
1229, 621 cm 1; (E)-4: 1H NMR: d ˆ 7.26 (dd, JH,F ˆ 72 Hz, JH,F ˆ 3 Hz,
1H; CHF); 19F NMR : d ˆ 167.0 (dd, 2JF,H ˆ 71 Hz, 3JF,F ˆ 129 Hz; CHF),
143.4 (dd, 3JF,F ˆ 129 Hz, 3JF,H ˆ 3 Hz, 2JF,N ˆ 10 Hz; CF); (Z)-4: 1H NMR:
d ˆ 6.83 (dd, 2JH,F ˆ 69 Hz, 3JH,F ˆ 12 Hz, 1H; CHF); 19F NMR : d ˆ 155.2
[10] A. Guarnieri, R. Hinze, M. Krüger, H. Zerbe-Foese, D. Lentz, D.
Preugschat, J. Mol. Spectrosc. 1992, 156, 39; A. Huckauf, A. Guarnieri,
D. Lentz, A. Fayt, J. Mol. Spectrosc. 1998, 188, 109.
[11] H. Bürger, S. Sommer, D. Lentz, D. Preugschat, J. Mol. Spectrosc.
1992, 156, 360.
[12] H. Bürger, D. Lentz, B. Meisner, N. Nickelt, D. Preugschat, M.
Senzlober, Chem. Eur. J. 2000, 6, 3377.
[13] A. M. Smith, G. Schallmoser, A. Thoma, V. E. Bondybey, J. Chem.
Phys. 1993, 98, 1776.
[14] C. Bartel, P. Botschwina, H. Bürger, A. Guarnieri, ¾. Heyl, A.
Huckauf, D. Lentz, T. Merzliak, El B. Mkadmi, Angew. Chem. 1998,
110, 3036; Angew. Chem. Int. Ed. 1998, 37, 2879.
[15] J. Gripp, A. Guarnieri, W. Stahl, D. Lentz, J. Mol. Struct. 2000, 526, 81.
[16] P. Thaddeus, M. C. McCarthy, M. J. Travers, C. A. Gottlieb, W. Chen,
Faraday Discuss. 1998, 109, 121.
[17] P. Botschwina, ¾. Heyl, W. Chen, M. C. McCarthy, J.-U. Grabow, M. J.
Travers, P. Thaddeus, J. Chem. Phys. 1998, 109, 3108.
[18] R. Kunz, W. P. Fehlhammer, Angew. Chem. 1994, 106, 331; Angew.
Chem. Int. Ed. Engl. 1994, 33, 330.
2
2
3
2
(ddt, JF,H ˆ 69 Hz, JF,N ˆ 5 Hz, JF,F ˆ 2 Hz; CHF), 121.7 (dt, vbr, JF,N
ˆ
10 Hz, 3JF,H ˆ 12 Hz; CF).
Isocyanopropynenitrile (16) and (E)/(Z)-3-Chloro-2-fluoro-3-isocyanopro-
penenitrile (17): Experimental conditions were as described above, using
precursor 7a and a pyrolysis temperature of 2408C. The pyrolysis products
were collected in a trap kept at 1968C and purified by fractional
condensation under vacuum (0.001 Pa) through traps cooled to 788C,
1008C, and 1968C. Compounds 16 and 17 were collected in the trap
kept at 1968C and 1008C, respectively.(E)-17: 13C{19F} NMR (CD2Cl2) :
d ˆ 108.9 (d, 2JC,F ˆ 39 Hz; CN), 134.7 (d, 1JC,F ˆ 261 Hz; CF), 181.1 (s; NC);
19F NMR: d ˆ 121.13 (s; CF); (Z)-17: 13C{19F} NMR: d ˆ 109.1 (d, 2JC,F
ˆ
39 Hz; CN), 133.2 (d, 1JC,F ˆ 271 Hz; CF); 19F NMR : d ˆ 114.47 (s; CF).
16: IR (gas): nÄ ˆ 2296 w, 2210 s and 2053 cm 1; MS: m/z: 76 [M] , 50 [C3N]
‡
‡
and smaller fragment ions.
Crystallography: Crystal data and details of the structure determinations
are presented in Table 4. The intensity data were collected using a Bruker
AXS Smart (11a, 11b, 8i) and a STOE (12) diffractometer, respectively.
Corrections for Lorentz polarization and absorption effects were applied to
the data. The structures were solved by Patterson and direct methods
(SHELXS-97),[39] respectively. Hydrogen atoms were found in subsequent
difference maps 11a, b and refined isotropically and refined in calculated
positions 8i and 12 with isotropic thermal parameters. Anisotropic thermal
parameters were applied to all non-hydrogen atoms. Refinement for all
structures on F 2 were achieved by using the SHELXL-97 system.[39]
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication numbers CCDC-145286
(11a), CCDC-115287 (11b), CCDC-145288 (8i) and CCDC-145289 (12).
Copies of the data can be obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (Fax: (‡44)1223-336-033;
e-mail:deposit@ccdc.cam.ac.uk).
[19] D. Bergemann, Diplomarbeit, Freie Universität Berlin.
[20] P. J. Stang in Modern Acetylene Chemistry (Eds. P. J. Stang, F. Die-
derich), VCH, Weinheim, 1995, p. 67.
[21] D. Lentz, F. Nowak, D. Preugschat, M. Wasgindt, Angew. Chem. 1993,
105, 1547; Angew. Chem. Int. Ed. Engl. 1993, 32, 1456.
[22] R. D. Chambers in Synthetic Fluorine Chemistry, Eds. G. A. Olah,
R. D. Chambers, G. K. S. Prakash, Wiley-Interscience, New York,
1992; R. D. Chambers, J. F. S. Vaughan, Topics in Current Chem. 1997,
192, 1.
[23] K. H. Dötz in Reactions of Coordinated Ligands (Ed. P. S. Brater-
mann), Plenum Press, New York, 1986; B. Crociani in Reactions of
Coordinated Ligands (Ed. P. S. Bratermann), Plenum Press, New
York, 1986.
[24] W. P. Fehlhammer, F. Degel, G. Beck, Chem. Ber. 1987, 120, 461.
[25] D. Lentz, Angew. Chem. 1994, 106, 1377; Angew. Chem. Int. Ed. Engl.
1994, 33, 1315.
[26] D. Lentz, R. Marschall, Chem. Ber. 1990, 123, 751.
[27] D. J. Burton, S. Shinya, R. D. Howells, J. Am. Chem. Soc. 1979, 101,
3689.
[28] H. Wessolowsky, G.-V. Röschenthaler, R. Winter, G. Gard, Z.
Naturforsch. B 1991, 46, 123.
[29] A. M. English, K. R. Plowman, I. M. Baibich, J. P. Hickey, I. S. Butler,
G. Jaouen, P. Lemoux, J. Organomet. Chem. 1981, 205, 177.
[30] G. Christian, H. Stolzenberg, W. P. Fehlhammer, J. Chem. Soc. Chem.
Commun. 1992, 184.
Acknowledgement
Support by the Deutsche Forschungsgemeinschaft (DFG) and the Fonds
der Chemischen Industrie is gratefully acknowledged. We are grateful to
the Hoechst AG (Frankfurt, Germany) and DuPont (Wilmington, DE) for
providing some starting materials.
[31] D. Lentz, Chem. Ber. 1984, 117, 415.
[32] E. Singleton, H. E. Oosthuizen, Adv. Organomet. Chem. 1983, 22, 209.
[33] R. S. Dickson, P. J. Fraser, Adv. Organomet. Chem. 1974, 12, 323; M. J.
Went, Adv. Organomet. Chem. 1997, 41, 69.
[1] D. S. Matteson, R. A. Bailey, J. Am. Chem. Soc. 1968, 90, 3761.
[2] A. Gautier, Justus Liebigs Ann. Chem. 1867, 142, 289; A. Gautier,
Justus Liebigs Ann. Chem. 1868, 146, 124.
[3] A. W. Hofmann, Justus Liebigs Ann. Chem. 1867, 144, 114; A. W.
Hofmann, Justus Liebigs Ann. Chem. 1868, 146, 107.
[4] D. Lentz, D. Preugschat, J. Chem. Soc. Chem. Commun. 1992, 1523.
[5] J. Buschmann, S. Kleinhenz, D. Lentz, P. Luger, K. V. Madappat, D.
Preugschat, J. S. Thrasher, Inorg. Chem. 2000, 39, 2807.
[6] W. P. Fehlhammer, G. Beck, J. Organomet. Chem. 1989, 379, 97.
[7] M. Krüger, H. Dreizler, D. Preugschat, D. Lentz, Angew. Chem. 1991,
103, 1674; Angew. Chem. Int. Ed. Engl. 1991, 30, 1644.
[8] K. Kawaguchi, M. Ohishi, S.-I. Ishikawa, N. Kaifu, Astrophys. J. 1992,
386, L51.
[34] J. Mason in Multinuclear NMR, (Ed. J. Mason), Plenum, New York,
London 1987, p. 335 ± 362.
[35] K. Yamada, G. Winnewisser, Z. Naturforsch. A 1981, 36, 1052; S. Haas,
G. Winnewisser, K. Yamada, Can. J. Chem. 1994, 72, 1165.
[36] A. Guarnieri, A. Huckauf, personal communication.
[37] Handbuch der präparativen Anorganischen Chemie (Ed. G. Brauer),
Bd. 3, F. Enke, Stuttgart 1981.
[38] M. Höfler, H. Löwenich, J. Organometal. Chem. 226 (1982) 229.
[39] SHELX97 [Includes SHELXS97, SHELXL97, CIFTAB] Programs for
Crystal Structure Analysis (Release 97 ± 2), G. M. Sheldrick, Uni-
versität Göttingen, Germany, 1998.
[40] ORTEP3 for Windows, L. J. Farrugia, J. Appl. Crystallogr. 1997, 30,
565.
[9] L. Zanathy, H. Bock, D. Lentz, D. Preugschat, P. Botschwina, J. Chem.
Soc. Chem. Commun. 1992, 403.
Received: June 26, 2000 [F2566]
Chem. Eur. J. 2001, 7, No. 4
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0704-0893 $ 17.50+.50/0
893