Intermetallic Communication through Carbon Wires in Heterobinuclear Cationic Allenylidene Complexes of Chromium

Article abstract of DOI:10.1021/om0607301

The reaction of [(CO)₅M(THF)] (M = Cr, W) with lithiated 2-ethynylquinoline followed by alkylation of the resulting alkynylpentacarbonylmetalate with [R₃O]BF₄ (R = Me, Et) gives allenylidene complexes in which the terminal carbon atom of the allenylidene chain is part of an N-alkylated quinoline ring. The reaction of [(CO)₅M(THF)] (M = Cr, W) with lithiated 2-ethynylpyridine derivatives, Li[C≡CC₅H₄BrN], and [Et ₃O]BF₄ affords allenylidene complexes that contain a terminal six-membered N-heterocycle brominated at the 5- or 6-position. Various alkynyl groups can be introduced into the 5-position of the ring through [PdCl₂(PPh₃)₂] -catalyzed coupling of the 5-bromo-substituted allenylidene complexes with the terminal alkynes HC≡CR′ (R′ = TMS, Ph, C₁₀H₂₁, 4-C ₆H4-C≡CPh, 4-C₆H₄-C≡CH, Fc (Fc = (C₅H₄,)FeCp), 4-C₆H₄-C=CFc, 4-C ₆H₄-C≡CC₆H₄C≡CFc). The analogous replacement reaction of the 6-bromo-substituted chromium complex with HC≡CFc yields the corresponding 6-ferrocenylalkynyl-substituted complex. Desilylation of [(CO)₅Cr=C=C=C(CH)₂C(C≡CSiMe ₃)CHNEt] (6a) gives [(CO)₅Cr=C=C= C(CH) ₂C(C=CH)CHNEt] (15a). CuI-catalyzed coupling of 15a with {M}-Br ({M} = Ru(CO)2Cp, Fe-(CO)₂Cp*) affords the binuclear complexes [(CO)₅Cr=C=C=C(CH)₂C(C=C-{M})CHNEt]. The symmetrical binuclear complex is formed by oxidative coupling of 15a with [Cu(OAc) ₂]. The attachment of a ferrocenyl group to the chromium center via PPh₂ to give cis-[(CO)₄(Ph₂PFc)Cr=C=C=C(CH) ₄NEt] is achieved via displacement of a cis-CO ligand in [(CO) ₅Cr=C=C=C(CH)₄NEt] by PPh₂Fc. On addition of Co₂(CO)₈ to [(CO)₅Cr=C=C=C(CH) ₂C(C=CPh)CHNEt] a Co₂(CO)₆ unit adds to the C≡C bond to form a trinuclear complex. The ferrocenyl unit in [(CO) ₅Cr=C=C=C(CH)₂C(C≡CR)CHNEt] (R = Fc, C ₆H₄C≡CFc, C₆H₄C≡CC ₆H₄C≡CFc) is readily oxidized. Spectroelectrochemical studies (IR, UV/vis) confirm that in the oxidized form there is strong electronic communication of the ferrocenyl group with the (CO)₅Cr unit.

Full text of DOI:10.1021/om0607301

5
774
Organometallics 2006, 25, 5774-5787
Intermetallic Communication through Carbon Wires in
Heterobinuclear Cationic Allenylidene Complexes of Chromium
†
†
‡
‡
Normen Szesni, Matthias Drexler, J o¨ rg Maurer, Rainer F. Winter,
§
§
|
|
Fr e´ d e´ ric de Montigny, Claude Lapinte, Stefan Steffens, J u¨ rgen Heck,
†
,†
Bernhard Weibert, and Helmut Fischer*
Fakult a¨ t f u¨ r Chemie, UniVersit a¨ t Konstanz, Postfach 5560 M727, D-78434 Konstanz, Germany, Institut f u¨ r
Anorganische Chemie, UniVersit a¨ t Regensburg, UniVersit a¨ tsstrasse 31, D-93040 Regensburg, Germany,
UMR CNRS 6226 Sciences Chimiques de Rennes, UniVersit e´ de Rennes I, Campus Beaulieu, 35042 Rennes
Cedex, France, and Institut f u¨ r Anorganische und Angewandte Chemie, UniVersit a¨ t Hamburg,
Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
ReceiVed August 11, 2006
The reaction of [(CO)
of the resulting alkynylpentacarbonylmetalate with [R
in which the terminal carbon atom of the allenylidene chain is part of an N-alkylated quinoline ring. The
reaction of [(CO) M(THF)] (M ) Cr, W) with lithiated 2-ethynylpyridine derivatives, Li[CtCC
BrN], and [Et O]BF affords allenylidene complexes that contain a terminal six-membered N-heterocycle
brominated at the 5- or 6-position. Various alkynyl groups can be introduced into the 5-position of the
ring through [PdCl (PPh ]-catalyzed coupling of the 5-bromo-substituted allenylidene complexes with
the terminal alkynes HCtCR′ (R′ ) TMS, Ph, C10 -CtCPh, 4-C -CtCH, Fc (Fc ) (C )-
FeCp), 4-C -CtCFc, 4-C -CtCC CtCFc). The analogous replacement reaction of the 6-bromo-
substituted chromium complex with HCtCFc yields the corresponding 6-ferrocenylalkynyl-substituted
5
M(THF)] (M ) Cr, W) with lithiated 2-ethynylquinoline followed by alkylation
3
O]BF (R ) Me, Et) gives allenylidene complexes
4
5
5 4
H -
3
4
2
3 2
)
H21, 4-C H
6 4
H
6 4
5 4
H
H
6 4
H
6 4
6 4
H
complex. Desilylation of [(CO) CrdCdCdC(CH) C(CtCSiMe )CHNEt] (6a) gives [(CO) CrdCdCd
C(CH) C(CtCH)CHNEt] (15a). CuI-catalyzed coupling of 15a with {M}-Br ({M} ) Ru(CO) Cp, Fe-
CO) Cp*) affords the binuclear complexes [(CO) CrdCdCdC(CH) C(CtC-{M})CHNEt]. The
5
2
3
5
2
2
(
2
5
2
symmetrical binuclear complex is formed by oxidative coupling of 15a with [Cu(OAc) ]. The attachment
2
of a ferrocenyl group to the chromium center via PPh to give cis-[(CO) (Ph PFc)CrdCdCdC(CH) NEt]
is achieved via displacement of a cis-CO ligand in [(CO) CrdCdCdC(CH) NEt] by PPh Fc. On addition
of Co (CO) to [(CO) CrdCdCdC(CH) C(CtCPh)CHNEt] a Co (CO) unit adds to the CtC bond to
form a trinuclear complex. The ferrocenyl unit in [(CO) CrdCdCdC(CH) C(CtCR)CHNEt] (R ) Fc,
2
4
2
4
5
4
2
2
8
5
2
2
6
5
2
C
6
H
4
CtCFc, C CtCC CtCFc) is readily oxidized. Spectroelectrochemical studies (IR, UV/vis)
confirm that in the oxidized form there is strong electronic communication of the ferrocenyl group with
the (CO) Cr unit.
6
H
4
6 4
H
5
Introduction
Di- or oligonuclear transition-metal complexes with π-con-
particular interest, as it can be regarded as a model for a variety
5
of comparable processes in biological systems as well as in
6
7
photonic and electronic devices. The properties of such
complexes are determined by the usually redox-active terminal
end groups and the type and length of the spacers. Most of the
relevant work in this field relates to the investigation of mono-
and polynuclear metal acetylides containing terminating orga-
jugated bridges are gaining considerable attention due to their
versatile structural, chemical, and physicochemical properties.
Organometallic push-pull systems with linear conjugated
π-spacers have been proposed as a new class of one-dimensional
1
2
3
wires and exhibit both liquid crystalline and NLO properties.
4
The electronic communication in polynuclear systems is of
(
2) (a) Hudson, S. A.; Maitlis, P. M. Chem. ReV. 1993, 93, 861. (b)
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†
Universit a¨ t Konstanz.
Universit a¨ t Regensburg.
Universit e´ de Rennes I.
Universit a¨ t Hamburg.
‡
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Properties of Polymers; Mater. Res. Soc. Symp. Proc. 109; Elsevier: New
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ElectroactiVe Polymers; Plenum: New York, 1988. (c) Wisian-Neilson, P.,
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O’Hare, D. Chem. ReV. 1997, 97, 637. (f) Marder, S. R. In Inorganic
Materials, Wiley: Chichester, U.K., 1996.
§
|
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1
06, 1445; Angew. Chem., Int. Ed. Engl. 1994, 33, 1360. (b) Beck, W.;
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1
1
0.1021/om0607301 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 10/24/2006

Allenylidene Complexes of Chromium
nometallic groups, such as MnI(dmpe)2, Re(NO)(PPh3)Cp*,
Organometallics, Vol. 25, No. 24, 2006 5775
8
9
Scheme 1
Fe(CO)2Cp*,1 Fe(dppe)Cp*, Fe(dippe)Cp*, Ru(dppe)Cp*,
0
11
11
12
12
12
13
Ru(dppm)Cp*, Ru(PR3)2Cp*, and similar systems that offer
the opportunity for single- or multi-electron-transfer processes.
Additionally, bis(vinylidene)-, mixed vinylidene-alkynyl, and
related highly conjugated complexes have been synthesized and
investigated.
In contrast, there have only been a few reports on electro-
chemical studies involving allenylidene complexes.14 These
investigations reveal that the site of oxidation is the metal center,
thus increasing its acceptor properties. This leads to an enhanced
alkynyl character of the cumulenylidene ligand (B′ and B′′,
Scheme 1). Conversely, reduction mainly involves the alle-
nylidene ligand, giving rise to an increased contribution of the
cumulene-like resonance form to the overall bond description
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A, Scheme 1).
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15
investigations. These studies indicate that the HOMO is mainly
localized at the metal center and the LUMO is delocalized within
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1
0057.
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(
2
University Science Books: Mill Valley, CA, 1994. (b) Schuster, G. B. Acc.
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1
4g,h
cumulene moiety.
(
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various other complexes such as heterocyclic carbene com-
7
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1
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425.

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776 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
Scheme 2
Scheme 4
Scheme 3
in nearly quantitative yield. Other alkynyl substituents such as
dodecynyl, phenylethynyl, and 4-alkynyl-substituted phenyl-
ethynyl groups could be introduced into the 5-position of the
heterocycle as well. The corresponding mononuclear complexes
7
a-10a and 6b were obtained in good to excellent yields
(Scheme 4) by following the same procedure. The yields and
the reaction times required for a complete conversion strongly
depended on the excess of the terminal alkyne. The reaction
rates significantly increased with increasing excess of the alkyne.
Conversely, increasing the temperature led to lower yields, due
to decomposition of the product complexes. When (trimethyl-
silyl)ethyne was used, the amount of the catalyst could be
reduced to 0.01 equiv without loss of activity. Thus, an extension
of the unsaturated chain can easily be accomplished and various
terminating groups can be introduced into allenylidene com-
plexes.
Ferrocene could likewise be attached to the terminating
N-heterocycle of the allenylidene ligand through different
unsaturated spacers by Pd/Cu-catalyzed coupling of 3a with
appropriate alkynyl-functionalized ferrocenes (Scheme 4). The
complexes 11a-13a were obtained in yields ranging from 45%
(13a) to 73% (11a). In a pure form and under an inert
atmosphere the complexes were stable at room temperature.
However, under the conditions used in the synthesis of 6a-
13a, complex 13a slowly decomposed. Therefore, the reactions
were stopped after 60 min to avoid excessive decomposition of
the product, thus explaining the rather low yield.
complexes containing different metal entities and various
π-spacers, (c) the synthesis of a linear homobinuclear bis-
(allenylidene) complex by oxidative coupling of an ethynyl-
substituted allenylidene complex, and (d) the spectroelectro-
chemical properties of some of these complexes.
Results and Discussion
Synthesis of N-Heterocyclic Allenylidene Complexes 1-4.
The new allenylidene complexes 1-4 were prepared by
following the synthetic protocol reported recently.1 Reaction
of the THF complexes [(CO)5M(THF)] (M ) Cr, W) with
deprotonated 2-ethynylpyridines (2-ethinylquinoline) gave alky-
nylmetalates by displacement of the coordinated THF molecule.
These alkynyl complexes were not isolated but were im-
mediately alkylated with oxonium salts, R3O[BF4] (R ) Me,
Et). After chromatography, the complexes 1a,b and 2a,b
6
(
Scheme 2) were obtained as deep violet solids in 68-80%
yield. The corresponding bromo-functionalized complexes 3a,b
and 4a,b (Scheme 3) were obtained as red solids in only
moderate yields of 16-36%. In addition, the allenylidene
complexes 5a,b16 were isolated in low yields (<20%) as
byproducts in the synthesis of 3a,b and 4a,b. The formation of
The 3-ethynylferrocene-substituted complex 14a, analogous
to 11a, was prepared similarly by Pd/Cu-catalyzed coupling of
ethynylferrocene with complex 4a (Scheme 5).
5
a,b is readily explained by further lithiation of the lithium
Desilylation of complex 6a to give the ethynyl-terminated
derivative 15a was achieved by treating solutions of 6a in
methanol at 0 °C with KF, KOH, or K CO (Scheme 6).
alkynyl precursor and subsequent protonation on silica. By
deprotonation of 5-bromo-2-ethynylpyridine and 6-bromo-2-
ethynylpyridine at -100 °C instead of at -78 °C, the halide/
metal exchange could be minimized and the bromo-function-
alized allenylidene complexes 3a,b and 4a,b were obtained in
2
3
Complex 15a was obtained, after chromatography, as a red solid
in nearly quantitative yield. When complex 15a was treated with
a slight excess of copper(II) acetate (1.2 equiv) in the presence
of pyridine, the homobinuclear bis(allenylidene) complex 18a
(Scheme 6) was formed. Compound 18a was isolated after
chromatography as violet oil in good yield. Heterobinuclear
complexes were accessible by copper(I)-catalyzed coupling of
15a with [Cp(CO)2Ru-Br] and [Cp*(CO)2Fe-Br]. The hetero-
binuclear allenylidene-alkynyl complexes 16a and 17a (Scheme
6) were obtained in 58% and 38% yields, respectively.
2
0-47% yield (isolated yield of 5a,b <5%).
Coupling of 3 and 4 with Terminal Alkynes. When 3a was
treated with an excess of (trimethylsilyl)ethyne (10 equiv) in
the presence of catalytic amounts of (PPh3)2PdCl2 (0.05 equiv),
CuI (0.1 equiv), and triethylamine, complex 3a was smoothly
transformed into allenylidene complex 6a within about 30 min.
Complex 6a was obtained, after chromatography, as a red solid

Allenylidene Complexes of Chromium
Organometallics, Vol. 25, No. 24, 2006 5777
Scheme 5
Scheme 8
Scheme 6
Câ bond of the allenylidene ligand is conceivable, due to a
considerable contribution of the zwitterionic alkynyl complex
resonance forms B′ and B′′ (see Scheme 1) to the overall
bonding description. However, the reaction is highly regiose-
lective. Only the product of coordination to the terminal C-C
bond has been observed. There is no indication for complexation
of the CR-Câ bond. When the unsubstituted complex 5a instead
of 9a was treated with Co2(CO)8 employing the same reaction
conditions, complex 5a rapidly decomposed. In contrast, in the
absence of Co2(CO)8 complex 5a is stable. These observations
indicate that Co2(CO)8 (or a fragment derived from Co2(CO)8
by loss of CO) indeed interacts with the CR-Câ bond. However,
the product of such an interaction is unstable and rapidly
decomposes. The rapid decomposition on complexation of the
CR-Câ bond is presumably due to loss of the stabilizing
electronic interaction of the nitrogen π-donor with the (CO)5Cr
acceptor unit. Note that allenylidene pentacarbonyl complexes
lacking a stabilizing interaction of the CR2 group with the
[
[
[
(CO)5M] fragment are rather unstable. As an example,
(CO)5CrdCdCdCMe2] has not been isolated until now and
(CO)5CrdCdCdCPh2] has been isolated but quickly decom-
Scheme 7
1
3h
poses in solution at room temperature.
Spectroscopic Results. The ν(CO) vibrations and the ν(CCC)
absorption in allenylidene carbonyl complexes are sensitive
probes for the electronic interaction of the terminal substituents
1
6,17h,k,18,19
with the carbonyl metal fragment.
All allenylidene
complexes exhibit spectroscopic features characteristic for
π-donor-substituted allenylidene complexes. The absorptions are
found at rather low energy and are comparable to those of
16
amino(alkoxy)allenylidene complexes, indicating pronounced
donor character of the ligand (see resonance forms B′ and B′′
in Scheme 1). However, the comparison of the vibrations of
3
1
a, 4a, 6a-17a, and 20a with those of unsubstituted 5a16 (Table
) suggests that neither substitution of the pyridyl ring of the
allenylidene ligand nor elongation of the conjugated chain (11a
f 12a f 13a) strongly influences the electron distribution
within the “(CO)5MdCdCdC” fragment. In contrast, replacing
one CO ligand by a phosphine considerably reduces the
importance of the zwitterionic iminium-alkynyl resonance
The redox-active phosphine FcPh2P could be introduced into
the metal-ligand moiety via photolytically induced substitution.
When 5a was irradiated in the presence of a slight excess of
ferrocenyldiphenylphosphine, the deep violet allenylidene com-
plex 19a was formed within about 2 h. Chromatography on silica
afforded 19a as a violet solid in 62% yield (Scheme 7).
Finally, the reaction of the phenylethynyl-terminated complex
forms B′ and B′′ relative to that of the cumulene form A
20
(Scheme 1), as has already been observed.
The chemical shifts of the allenylidene carbon atoms of the
new complexes (Table 1) agree well with those of the known
(18) Szesni, N.; Weibert, B.; Fischer, H. Inorg. Chim. Acta 2006, 359,
9a with a slight excess of octacarbonyldicobalt(0) at ambient
617.
(19) Szesni, N.; Weibert, B.; Fischer, H. Inorg. Chim. Acta 2005, 358,
temperature yielded (ca. 58%) the heterotrinuclear complex 20a
as a brown-violet oil (Scheme 8). The addition of the Co2(CO)6
fragment to the terminal C-C triple bond as well as to the CR-
1
645.
(20) Szesni, N.; Weibert, B.; Fischer, H. Inorg. Chim. Acta 2004, 357,
1789.

5778 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
Table 1. Selected Spectroscopic Data for the Allenylidene
Complexes 1a,b-6a,b and 7a-20aa
compd
ν(CO)
ν(CCC)b δ(CR) δ(Câ) δ(Cγ) λmax
1
1
2
2
3
3
4
4
5
5
6
6
7
8
9
1
1
1
1
1
1
1
a
b
a
b
a
b
a
b
2076, 1933, 1907
2080, 1927,1900
2076, 1933, 1907
2080, 1927, 1900
2077, 1930, 1905
2080, 1925, 1899
2078, 1930, 1904
2081, 1924, 1898
2076, 1929, 1901
2079, 1922, 1894
2078, 1930, 1905
2081, 1925, 1898
2077, 1930, 1903
2078, 1931, 1904
2077, 1931, 1904
2078, 1931, 1904
2077, 1930, 1903
2077, 1931, 1904
2078, 1931, 1904
2077, 1930, 1902
2077, 1930, 1904
Cr-CO: 2078, 1928,
2000
2003
2000
2003
2005
2008
2005
2006
2012
2016
2002
2004
2003
2003
2001
2001
2002
2002
2001
2009
2003
2009
200.9 117.9 139.9 544
178.7 115.6 141.5 523
201.5 117.8 138.9 543
179.3 115.5 138.9 523
190.5 113.2 139.7 512
170.8 111.5 140.6 495
191.1 111.5 136.0 511
170.0 109.5 137.1 494
186.1 111.6 139.0 479
166.0 109.7 139.2 464
193.7 113.4 136.4 513
172.5 111.1 137.3 496
190.3 112.1 135.7 502
192.6 112.9 135.8 516
192.9 113.1 135.9 522
193.2 116.5 135.8 522
190.1 112.4 137.7 519
192.9 113.0 135.7 520
185.0 113.1 135.9 522
185.7 111.9 138.3 524
193.2 115.8 136.3 514
182.7 110.6 134.3 487
Figure 1. Plot of complex 2a (ellipsoids drawn at the 50%
probability level, hydrogen atoms omitted). Selected bond lengths
1
6
a
b
a
b
a
a
a
1
6
(
1
Å) and angles (deg): Cr(1)-C(1) ) 1.905(4), Cr(1)-C(2) )
.909(4), Cr(1)-C(3) ) 1.901(4), Cr(1)-C(4) ) 1.901(4), Cr(1)-
C(5) ) 1.886(4), Cr(1)-C(6) ) 2.015(4), C(6)-C(7) ) 1.239(5),
C(7)-C(8) ) 1.394(5), C(8)-N(1) ) 1.370(4), C(8)-C(9) )
1.415(5); Cr(1)-C(6)-C(7) ) 173.0(3), C(6)-C(7)-C(8) ) 175.4-
(3).
0a
1a
2a
3a
4a
5a
6a
1899
Ru-CO: 2045, 1996
17a
Cr-CO: 2077, 1928,
2009
181.6 110.6 133.7 492
1899
Fe-CO: 2017, 1972
2077, 1933, 1906
2037, 1896, 1887,
1
1
8a
9a
1993
1968
198.2 114.7 136.1 575
206.4 118.4 137.8 539
1
857
Cr-CO: 2076, 1930,
904
Co-CO: 2095, 2060,
033
2
0a
2001
189.3 120.0 138.1 522
1
Figure 2. Plot of complex 19a (ellipsoids drawn at the 50%
probability level, hydrogen atoms omitted). Selected bond lengths
2
(
Å) and angles (deg): Cr(1)-P(1) ) 2.395(1), Cr(1)-C(1) ) 1.877-
a
IR absorptions in cm in THF, 13C NMR data in ppm in d6-acetone,
-1
(
)
4), Cr(1)-C(2) ) 1.861(4), Cr(1)-C(3) ) 1.887(4), Cr(1)-C(4)
b
λmax in nm in CH2Cl2. Dominant character ν(CCC): however, there is
1.856(3), Cr(1)-C(5) ) 2.009(4), C(5)-C(6) ) 1.234(5), C(6)-
considerable mixing of the ν(CCC) with ν(CO) A1 vibrations.
C(7) ) 1.397(5), C(7)-N(1) ) 1.373(4), C(7)-C(8) ) 1.400(5);
Cr(1)-C(5)-C(6) ) 176.4(3), C(5)-C(6)-C(7) ) 173.0(4).
pyridyl allenylidene complexes 5a,b.16 In comparison to the
resonance of the CR atom of nondonor-substituted allenylidene
(1.394(5) Å in 2a, 1.397(5) Å in 19a) is long, in accord with a
21
complexes, that of 3a-20a is found at significantly lower field.
significant contribution of the resonance form B′ (Scheme 1).
The M-C3 fragment deviates slightly from linearity in both
complexes. The plane of the allenylidene ligand in 2a eclipses
the cis-CO groups (torsion angle C(1)-Cr(1)-C(8)-N(1) )
The substitution pattern of the pyridyl ring only slightly
1
3
influences the C allenylidene resonances, and this matches
well with our observations from IR spectroscopy.
The UV/vis spectra of the complexes 3a, 4a, and 6a-17a
show an intense metal-to-ligand charge transfer (MLCT)
absorption in the range 487 (16a)-524 nm (14a). The λmax
values of 3a, 4a, and 6a-15a are nearly independent of the
substitution pattern and of the elongation of the unsaturated
chain, indicating significant interactions between the allenylidene
chromophore and the substituents at the pyridyl ring. In
comparison to the unsubstituted complex 5a, all absorptions are
shifted to lower energy. As expected, the phosphine-substituted
complex 19a absorbs at even lower energy, consistent with a
rise in energy of the mostly metal-localized HOMO.
3
4.2°). A comparison of the individual bond distances in 2a
with those in 5a indicates that the annulated ring reduces the
π-donor properties of the terminal substituent. The conclusion
is also supported by the IR data.
In 19a the P-Cr axis is nearly perpendicular to the alle-
nylidene plane (torsion angle P(1)-Cr(1)-C(7)-N(1) ) -78.3°),
thus optimizing back-donation into the allenylidene ligand. As
expected, both Cr-COcis distances (Cr(1)-C(1) and Cr(1)-
C(3)) are shorter than the Cr-COtrans bonds, Cr(1)-C(4) and
Cr(1)-C(2) being very similar.
Electrochemistry and Spectroelectrochemistry of 11a-13a
and 19a. The ferrocenyl unit in 11a-13a bonded to the terminal
carbon atom of the chain is readily oxidized. The cyclic
voltammograms of 11a-13a display in CH2Cl2/[NBu4]PF6 a
fully reversible one-electron wave in the range +1.2/-1.0 V
vs the saturated calomel electrode (SCE) (Table 2). This redox
process corresponds to the well-known ferrocene-centered
oxidation and, as expected, indicates that the Fe(III) forms are
stable on the time scale of the voltammetric experiment.
The molecular structures of 2a and 19a were additionally
established by X-ray structural analyses (Figures 1 and 2). The
structures exhibit all features usually observed with aminoal-
lenylidene complexes.1
6,17k,18,19,22
The CR-Câ bond (C6-C7 in
2
a and C5-C6 in 19a) is rather short and corresponds to an
elongated C-C triple bond. Conversely, the Câ-Cγ bond
(
21) Fischer, H.; Reindl, D.; Roth, G. Z. Naturforsch. 1994, 49b, 1207.
(22) (a) Fischer, E. O.; Kalder, H. J.; Frank, A.; K o¨ hler, F. H.; Huttner,
G. Angew. Chem. 1976, 88, 683; Angew. Chem., Int. Ed. Engl. 1976, 15,
23. (b) Duetsch, M.; Stein, F.; Pohl, E.; Herbst-Irmer, R.; de Meijere, A.
Organometallics 1993, 12, 2556. (c) Aumann, R. Chem. Ber. 1994, 127,
25.
It is immediately apparent that the carbon-rich alkynylalle-
nylidene pentacarbonyl metal substituents are electron-with-
drawing and make the oxidation of 11a-13a more difficult than
6
7

Allenylidene Complexes of Chromium
Organometallics, Vol. 25, No. 24, 2006 5779
a
Table 2. Electrochemical Data for Complexes 11a-14a and
1
2 2
9a in CH Cl
compd
E°1 (V)
∆E (mV)
E°2 (mV)
∆E (mV)
irev/if
11a
12a
13a
14a
19a
614(5)
582(5)
593(5)
605(5)
165(5)
90
100
80
80
70
1
1
1
1
1
720(5)
750(5)
66
70
a
Conditions: E° versus a saturated calomel electrode (SCE), 0.1 M (n-
+
-
Bu)4N [PF6] at 25 °C.
that of ferrocene (0.460 V vs SCE).23 The electron-withdrawing
properties of the alkynylallenylidene pentacarbonyl metal
moieties in 11a-13a are smaller than those of the pentacarbonyl
24
carbene chromium fragment in [(CO)5CrdC(OEt)Fc] (0.77 V)
but more pronounced than those of the pentacarbonyl alkenyl-
carbene chromium fragment in [(CO)5CrdC(OEt)(CHdCH)nFc]
n ) 1, 0.595 V; n ) 2, 0,536 V; n ) 3, 0.494 V).2
5
(
A comparison of the redox potentials of compounds 11a and
1
2a shows that the introduction of an ethynylbenzene spacer
between the pyridyl-substituted allenylidene entity and the
redox-active ferrocenyl group slightly diminishes the electron-
withdrawing effect of the chromium carbonyl building block
on the iron center. However, introduction of a second ethynyl-
benzene fragment (12a f 13a) has only a negligible effect on
the redox potential of the complex. It thus seems that the
electron-withdrawing properties of the ethynylbenzene group
compensate the electronic effects of the increasing separation
of the push-pull groups.
In contrast to 11a-13a, the cyclic voltammogram of 19a
displays two reversible one-electron waves (Table 2, Figure 3)
and, in addition, an irreversible oxidation (at ca. 1.15 V) and
reduction wave (not shown in Figure 3). The irreversible
reduction is very likely due to reduction of the allenylidene unit.
DFT calculations show that the LUMO of 19a is predominantly
2
Figure 3. Cyclic voltammograms of 19a at a Pt electrode in CH -
Cl (0.1 M Bu NPF , 0.1 V s at 20 °C; E versus SCE) in the
2 4 6
range +0.95 to -0.25 V (above) and +1.5 to -1.75 V (below).
localized within the allenylidene ligand. Studies on mono- and
-
1
binuclear ruthenium allenylidene complexes1
4b-i
also indicate
that reduction is ligand-centered. The first reversible oxidation
wave (E° ) 0.165 V) is assigned to oxidation of essentially the
chromium atom. At first glance, such an assignment seems rather
unusual since (a) the first oxidation in 11a-13a is ferrocene-
centered and (b) the oxidation of pentacarbonyl carbene
chromium complexes is usually observed at much higher
ferrocene-centered oxidation. In addition, the high-field feature
3
1
is split into a 1:1 doublet by coupling with a P nucleus (A1 )
20.0 G).
The first oxidation wave of 19a is at a considerably less
positive potential than that of PFcPh2 (E° ) 0.565 V),27 of
[(CO)5MPFcPh2] (M ) Mo, E° ) 0.735 V; M ) W, E° ) 0.760
2
6
potential. However, the assignment is supported by several
observations.
2
7
V), and of [(CO)5Cr-PPh2{(C5H4)Fe(C5H4R)}] (R ) COOH,
2
8
28
(
a) From calculations on 19a it follows that the HOMO is
mostly localized on chromium.
b) The corresponding ferrocene-free complex cis-[(CO)4-
PPh3)CrdCdCdC{-N(Et)(CH)4-}] likewise exhibits a one-
E° ) 0.735 V; R ) C(dO)NMe2, E° ) 0.79 V ).
The second oxidation step observed for 19a is tentatively
assigned to oxidation of the ferrocene system. The assignment
is supported by the similarity of the oxidation potential to that
of the ferrocene-centered oxidation of 11a-13a and by the
(
(
electron oxidation wave at 0.200 V in addition to a semirevers-
ible wave at 1.07 V.
+
results of DFT calculations on 19a . These calculations indicate
+
(c) The ESR spectra of 19a[PF6] (obtained by oxidation of
that the singly occupied highest orbital in 19a is localized on
1
9a with ferrocenium hexafluorophosphate) in THF or CH2Cl2
iron. However, and in contrast to these results, from the ESR
+
+
run at 77 K display a rhombic signal with main g components
at g1 ) 1.988, g2 ) 2.037, and g3 ) 2.069. The signal is in
agreement with a chromium-centered radical rather than with a
spectra of 19a [PF6] it follows that 19a is a chromium-centered
radical (see above). Analogously to 19a, two reversible oxidation
waves were observed for the tetracarbonyl carbene phosphine
chelate complex [(CO)4Cr-PPh2{(C5H4)Fe(C5H4CNMe2)}] (E°
2
9
(
(
23) Conelly, N. G.; Geiger, W. E. Chem. ReV. 1996, 96, 877.
) 0.33 and 0.69 V).
24) (a) Fischer, E. O.; Schluge, M.; Besenhard, J. O.; Friedrich, P.;
On the basis of the chemical reversibility of the redox process
at the platinum electrode, the 17-electron Fe(III) complexes
Huttner, G.; Kreissl, F. R. Chem. Ber. 1978, 111, 3530. (b) Fischer, E. O.;
Gammel, F. J.; Besenhard, J. O.; Frank, A.; Neugebauer, D. J. Organomet.
Chem. 1980, 191, 261.
(
25) Jayaprakash, K. N.; Ray, P. C.; Matsuoka, I.; Bhadbhade, M. M.;
Puranik, V. G.; Das, P. K.; Nishihara, H.; Sarkar, A. Organometallics 1999,
8, 351.
26) Lloyd, M. K.; McCleverty, J. A.; Orchard, D. G.; Connor, J. A.;
(27) Kotz, J. C.; Nivert, C. L.; Lieber, J. M.; Reed, R. C. J. Organomet.
Chem. 1975, 91, 87.
(28) Podlaha, J.; Sˇ t eˇ pni cˇ ka, P.; Ludv ´ı k, J.; C ´ı sa ˇr ov a´ , I. Organometallics
1996, 15, 543.
1
(
Hall, M. B.; Hillier, I. H.; Jones, E. M.; McEwen, G. K. J. Chem. Soc.,
Dalton Trans. 1973, 1743.
(29) Meca, L.; Dvo rˇ a´ k, D.; Ludv ´ı k, J.; C ´ı sa ˇr ov a´ , I.; Sˇ t eˇ pni cˇ ka, P.
Organometallics 2004, 23, 2541.

5780 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
+
-
[
11a-13a] X were viewed as a possible viable synthetic
Table 3. IR Spectroscopic Data of the Neutral Complexes
1
1a, 12a, 14a, and 19a and Their Monocations in
target. However, oxidation of 11a with AgOTf at -80 °C and
+
-
1,2-Dichloroethane
precipitation of the salt [11a] OTf by addition of cold pentane
did not allow the isolation of a pure product but led to the
decomposition of the compound. Therefore, we decided to check
the stability of the monocation by ESR spectroscopy. A THF
solution of 11a was treated with 1 equiv of AgOTf at -80 °C
and stirred for 10 min at this temperature before it was
transferred into an ESR tube and frozen at liquid nitrogen
temperature. An ESR spectrum run at 77 K displays a weakly
anisotropic signal. Simulation of the experimental spectrum
allowed the extraction of the tensor components for this axial
pattern of g| ) 2.101, g⊥ ) 2.069, and giso ) 2.079. No proton
hyperfine coupling was resolved. After the first spectrum was
recorded, the ESR tube was placed in a bath at -20 °C for 30
min. Then another spectrum was run at 77 K under the same
conditions. The intensity of the signal was not perturbed by the
storage of the solution at -20 °C, indicating that the ESR-active
species is stable in solution at this temperature.
ν(CO)
ν(CCC)a
compd
ν(C N)
γ
1
1
12a
1a
1a
2077
2113
2080
2123
2080
2122
2039
2076
1928
2068
1930
2075
1928
2070
1895
2011
1903
2028
1901
2029
1900
2031
1884
1989
2004
1978
2002
1970
2010
1971
1851
1958
1515
1518
1518
1520
1549
1560
1969
2031
+
+
+
+
1
1
1
1
2a
4a
4a
9a
19a
a
There is considerable mixing of ν(CCC) with ν(CO) vibrations.
5
It is well-known that for d metallocenes the electronic ground
state is very sensitive to the combination of the metal and the
3
0
ligand orbitals. In the case of ferrocenium the degenerate
electronic configuration leads to a fast electronic relaxation; thus,
ESR spectra can only be observed at very low temperature (∼4
K) and the signal shows an axial pattern with a large anisotropy
(
g| > 4 and g⊥ < 1.5).31 The presence of the highly polarized
and extended π-system linked to one of the C5 rings of the
ferrocenium produces a dramatic change in the ESR spectrum.
The observation of a well-resolved signal at 77 K indicates that
+
the radical [11a] has a nondegenerate ground state. The weak
anisotropy of the signal and the giso value close to the free-
electron g value suggest that the carbon-rich fragment which
connects the two metal centers significantly contributes to the
delocalization of the spin density. The low chemical stability
of the radical cation is a probable consequence of its particular
electronic structure. Note that the decomposition of pentacar-
bonyl complexes of chromium, molybdenum, and tungsten is
usually initiated by M-CO dissociation.
The first oxidation process of the complexes 11a, 12a, 14a,
and 19a was additionally monitored by in situ IR and UV/vis
spectroscopy. A succession of spectra was recorded, either while
the potential was held at the appropriate value or while the
respective voltammetric wave was very slowly scanned. The
oxidation/re-reduction cycle was accompanied by some decom-
position, due to the relative instability of the radical complexes.
The spectroscopic yields of the respective starting complex after
one complete oxidation/re-reduction cycle varied between 42
and 82% (11a, 42%; 12a, 51%; 14a, 69%; 19a, 82%). With all
compounds, oxidation of the allenylidene complexes causes a
dramatic shift of the ν(CCC) and ν(CO) absorptions in the IR
spectra. IR band positions of the neutral and oxidized species
are given in Table 3. As representative examples spectra
accumulated during gradual oxidation (Figures 4a and 5a) and
re-reduction (Figures 4b and 5b) of complexes 12a and 19a
are depicted in Figures 4 and 5.
2 2
Figure 4. IR spectroelectrochemistry of complex 12a in CH Cl :
spectral changes accompanying oxidation (a) and re-reduction (b).
shift is unusually large (up to 100 cm-1) and implies consider-
able charge delocalization from iron to chromium and strong
electronic interaction of the ferrocenyl and the Cr(CO)5 moieties
Upon iron-centered oxidation (see above) the absorptions of
the pentacarbonyl chromium moiety shift toward higher energy.
This hypsochromic shift is readily explained by a decrease in
back-donation from chromium to the carbonyl ligands as a
consequence of the reduced electron density at the metal. The
+
+
+
in [11a] , [12a] , and [14a] . These shifts are of the same order
of magnitude as those observed upon oxidation of [(C6H6)Cr-
(CO)3], where the redox-active ligand is directly bonded to
3
2
chromium, and significantly exceed those observed upon
oxidation of the binuclear acetylenedithiolate-bridged complex
(
30) (a) Smart, J. C.; Robbins, J. L. J. Am. Chem. Soc. 1978, 100, 3936.
b) O’Hare, D.; Green, J. C.; Chadwick, T. P.; Miller, J. R. Organometallics
988, 7, 1335.
31) (a) Warren, K. D. Inorg. Chem. 1974, 13, 1317. (b) Gordon, K. R.;
Warren, K. D. Inorg. Chem. 1978, 17, 987.
(
1
(
(32) Camire, N.; Nafady, A.; Geiger, W. E. J. Am. Chem. Soc. 2002,
124, 7260.

Allenylidene Complexes of Chromium
Organometallics, Vol. 25, No. 24, 2006 5781
Figure 6. UV-vis spectroelectrochemistry of complex 12a in CH
Cl : spectral changes accompanying oxidation (a) and re-reduction
b).
2
-
2
(
Table 4. UV/Vis Spectroscopic Data of the Neutral
Complexes 11a, 12a, 14a, and 19a (1xa), Their Monocations
2 2
Figure 5. IR spectroelectrochemistry of complex 19a in CH Cl :
spectral changes accompanying oxidation (a) and re-reduction (b).
+
[1xa] , and Energy Difference of the Peak Maxima
1xa
[
Tp′(CO)2W(C2S2)Ru(PPh3)Cp].33 In contrast, the ν(CCC)
11a
12a
14a
19a
+
+
+
vibration in the oxidized species [11a] , [12a] , and [14a]
λmax (nm)
1xa
occurs at lower energy than in the corresponding neutral
compounds. However, the effect of oxidation on the ν(CCC)
vibration is less pronounced than that on the ν(CO) absorptions.
The influence of oxidation of the tetracarbonyl complex 19a
on the IR absorptions is comparable to that observed for 11a,
514
411
4900
515
417
4600
521
408
5300
530
400
6100
+
[1xa]
-
∆
(cm 1)
ethynyl substituent is moved from the 5-position (“para” to the
CrC2 fragment) into the 6-position (“meta” to CrC2) (11a f
4a). The large shifts observed again confirm the delocalization
1
2a, and 14a, thus confirming once more the strong interaction
1
of the ferrocenyl with the pentacarbonyl chromium moieties
of the positive charge onto Cr(CO)5, thus considerably reducing
the propensity of the chromium-ligand fragment for back-
donation. As expected, the influence of one-electron oxidation
is most pronounced with 19a. One should note again that the
first oxidation of 19a is assigned to (predominantly) the
chromium center.
NLO Properties of Complexes 11a-13a. The cumule-
nylidene complexes 11a-13a are polar push-pull systems and
are expected to exhibit nonlinear optical properties. Therefore,
the complexes were subjected to hyper-Rayleigh scattering
+
+
+
in [11a] , [12a] , and [14a] . As expected, on oxidation the
ν(CCC) vibration in 19a shifts toward higher energy, due to
reduced back-donation from chromium to the allenylidene ligand
and thus increased importance of the alkynyl resonance forms
B′ and B′′ (Scheme 1). The enhanced contribution of these
resonance forms also shows up in the shift of the ν(C-N)
-
1
vibration of 19a to higher wavenumbers (1543 cm f 1561
-
1
cm ). This effect is most pronounced for complex 19a, where
the redox-active center is predominantly the chromium atom.
On oxidation, the MLCT absorption in the UV/vis spectra
of 11a, 12a, 14a, and 19a shifts toward higher energy by 4600-
34
3
5
(
5
HRS) studies, but as they absorb substantially in the area of
32 nm (i.e., I(2ω) when the incident light has a wavelength of
I(ω) ) 1064 nm), the stimulating laser light was shifted to 1500
nm. The experiments were carried out in CH2Cl2 as described
-
1
6
100 cm (Table 4). The spectral changes accompanying the
oxidation and re-reduction of complex 12a are shown in Figure
. The extent of the shift only slightly decreases on elongation
of the chain (11a f 12a) and increases when the ferrocenyl-
6
(
34) Roth, G.; Fischer, H.; Meyer-Friedrichsen, T.; Heck, J.; Houbrechts,
S.; Persoons, A. Organometallics 1998, 17, 1511.
(35) Hendrickx, E.; Clays, K.; Persoons, A.; Dehu, C.; Br e´ das, J. L. J.
Am. Chem. Soc. 1995, 117, 3547.
(
33) Seidel, W. W.; Schaffrath, M.; Pape, T. Angew. Chem. 2005, 117,
7
976; Angew. Chem. Int. Ed. 2005, 44, 7798.

5
782 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
Table 5. Quadratic Hyperpolarizabilities for Complexes
scattering methods are in the region of cumulenylidene com-
plexes with comparable chain lengths. The effect of the
electrochemical manipulation on the NLO properties is currently
under investigation.
1
1a-13a, [(CO)
5 2 2
CrdCdCdC(NMe ) ], and
[
(CO) CrdCdCdCdCdC(NMe ) ]
5
2 2
â (10-
30
â0 (10a
-30
a
complex
esu)
esu)
b
b
1
1
[
1
1a
2a
0
20
21
73
100
0
9
9.5
33
31
Experimental Section
c
(CO)5CrdCdCdC(NMe2)2]
b
All operations were performed under an inert gas atmosphere
(nitrogen or argon) using standard Schlenk techniques. Solvents
3a
c
[
(CO)5CrdCdCdCdCdC(NMe2)2]
were dried by distillation from CaH
and sodium (THF, Et O). The silica gel used for chromatography
Baker, silica for flash chromatography) was argon-saturated and
used without modifications. The reported yields refer to analytically
2 2 2 4
(CH Cl ), LiAlH (pentane),
a
All values (10%. b Conditions: in CH2Cl2, incident light 1500 nm.
c
2
Conditions: in DMF, incident light 1064 nm.
(
earlier.36 As a reference Disperse Red 1 (DR 1; â(CH2Cl2) )
-
30
1
13
31
7
0 × 10
esu) was used.
pure compounds and are not optimized. H, C, and P NMR
spectra were recorded with Jeol JNX 400, Varian Inova 400, and
Bruker AC 250 spectrometers at ambient temperature. Chemical
shifts are relative to the residual solvent or tetramethylsilane peaks
The first hyperpolarizability â could only be obtained for the
complexes 12a and 13a (Table 5). Surprisingly, complex 11a
did not show any intensity in the HRS experiment. In contrast,
related donor-substituted allenylidene complexes exhibit moder-
ate first hyperpolarizabilities. The â values of complex 12a (â
20 × 10
those of [(CO)5CrdCdCdC(NMe2)2] (â ) 21 × 10
â0 ) 9.5 × 10 esu, in DMF). Introduction of a second
ethynylbenzene spacer between ferrocene and the heterocycle
1
13
31
(
3 4
H, C) or 100% H PO ( P). IR spectra were recorded on a
Biorad FTS 60 or a Perkin-Elmer Paragon 1000Pc. UV/vis spectra
were recorded on either a Hewlett-Packard 8453 diode array
spectrophotometer or a Bruins Instruments Omega 10 spectropho-
tometer. MS measurements were carried out on a Finnigan MAT
-
30
-30
)
esu; â0 ) 9 × 10
esu) are comparable to
-
30
esu;
-
30
34
312 instrument. Elemental analyses were carried out on a Heraeus
CHN-O-Rapid instrument. X-band ESR spectra were recorded on
a Bruker EMX-8/2.7 spectrometer, and simulated spectra were
obtained with the Bruker SIMFONIA program. The following
compounds were synthesized according to literature procedures:
-30
(
12a f 13a) almost quadruples â and â0 (13a: â ) 73 × 10
-30
esu; â0 ) 33 × 10
esu). These values are close to those of
the pentatetraenylidene complex [(CO)5CrdCdCdCdCd
-
30
-30
C(NMe2)2] (â ) 100 × 10
esu; â0 ) 31 × 10
esu, in
37
38
2
-ethynylquinoline, 5-bromo-2-ethynylpyridine, 6-bromo-2-ethy-
34
DMF). These results indicate that the extension of the π-system
that is conjugated to the allenylidene chain seems to be less
efficient than extension of the cumulenylidene carbon chain.
The effect of extension of the π-system by a “CtCC6H4-“
unit (length ca. 6.9 Å) is on the same order of magnitude as
that exerted by insertion of a “CdCd“ unit (length ca. 2.6 Å)
into the cumulenylidene chain.
39
40
41
nylpyridine, diphenylferrocenylphosphane, 4-ethynyltolane,
ethynylferrocene, 1-ethynyl-4-(ferrocenylethynyl)benzene, 1-(fer-
rocenylethynyl)-4-(phenylethynyl)benzene, 1,4-bis(ethynyl)ben-
zene, bromodicarbonyl(η -cyclopentadienyl)ruthenium, and bro-
42
43
43
44
5
45
5
45
modicarbonyl(η -pentamethylcyclopentadienyl)iron. All other
chemicals were used as received from commercial suppliers.
Preparation of the Complexes 1-4. A solution of 3.1 mL of
nBuLi (5 mmol, 1.6 M in hexane) was added dropwise at -80 °C
(1, 2) or at -100 °C (3, 4) to a solution of 5 mmol of the appropriate
alkyne (2-ethynylquinoline for 1 and 2; 5-bromo-2-ethynylpyridine
for 4; 6-bromo-2-ethynylpyridine for 3) in 50 mL of dry THF. The
solution was stirred for 20 min at this temperature. Then 50 mL of
Concluding Remarks
Pyridyl- and quinolinylallenylidene complexes are readily
synthesized from pentacarbonyl tetrahydrofuran complexes by
reaction with appropriate lithium alkynyl compounds followed
by alkylation of the resulting alkynylmetalate. Palladium/copper-
catalyzed coupling of bromo-functionalized pyridylallenylidene
complexes offers access to a broad range of complexes with
alkynyl functionalities in conjugation with the allenylidene
carbon chain. Among others, organometallic end groups can
easily be introduced, affording homo- as well as heterobinuclear
complexes. All spectroscopic data of the new complexes agree
well with those of comparable amino-substituted allenylidene
complexes. These complexes are dipolar and are stable at room
temperature, delocalization of the lone pair at nitrogen toward
the pentacarbonylmetal fragment being a major stabilizing factor.
IR and UV/vis spectroscopic data reveal that in cationic
binuclear complexes, obtained upon iron-centered one-electron
oxidation of the ferrocenyl-terminated complexes, the positive
charge is strongly delocalized, increasing the acceptor properties
of the chromium pentacarbonyl moiety. The effect of the charge
transfer on Cr-CO back-bonding is unusually large, demon-
strating that such bridging alkynyl-allenylidene ligands ef-
ficiently mediate electronic communication between the terminal
metal centers.
a solution of [(CO) M(THF)] (M ) Cr, W; 0.1 M in THF) was
5
added. The cooling bath was removed, and the brown solution was
warmed to ambient temperature. After stirring for 30 min, the
solvent was removed in vacuo. The remaining oily residue was
dissolved in 50 mL of dry CH Cl and treated with 5 mmol of
2
2
R
3
O[BF
further 60 min at 0 °C. The resulting solution was filtered at -20
°C through a 5 cm layer of silica using CH Cl as the eluent. The
solvent was evaporated and the residue chromatographed at -20
C on silica using mixtures of pentane and CH Cl as the eluent.
First, with pentane/CH Cl (2/1) a pale yellow band containing
] (M ) Cr, W) was obtained. Then, with pentane/CH Cl
polarity increasing from 1/1 to 1/3) a strongly colored band
4
] (R ) Me, Et) at 0 °C and this mixture was stirred for a
2
2
°
2
2
2
2
[M(CO)
6
2
2
(
(
37) Fakhfakh, M. A.; Fournet, A.; Prina, E.; Mouscadet, J.-F.; Franck,
X.; Hocquemiller, R.; Figadere, B. Bioorg. Med. Chem. 2003, 11,
013.
(38) Tilley, J. W.; Zawoiski, S. J. Org. Chem. 1988, 53, 386.
39) Orita, A.; Nakano, T.; An, D. L.; Tanikawa, K.; Wakamatsu, K.;
Otera, J. J. Am. Chem. Soc. 2004, 126, 10389.
5
(
(
(
40) Guillaneux, D.; Kagan, H. B. J. Org. Chem. 1995, 60, 2502.
41) Dirk, S. M.; Tour, J. M. Tetrahedron 2003, 59, 287.
(42) Rosenblum, M.; Brawn, N.; Papenmeier, J.; Applebaum, M. J.
Organomet. Chem. 1966, 6, 173.
The first hypolarizability â of the allenylidene complexes with
the most extended π-systems as measured by hyper-Rayleigh
(
43) Antonelli, E.; Rosi, P.; Lo Sterzo, C.; Viola, E. J. Organomet. Chem.
999, 578, 210.
44) Price, D. W.; Dirk, S. M.; Maya, F.; Tour, J. M. Tetrahedron 2003,
59, 2497.
(45) Brauer, G., Ed. Handbuch der Pr a¨ paratiVen Anorganischen Chemie;
Ferdinand Enke Verlag: Stuttgart, Germany, 1981; Vol. 3, Chapter 3.
1
(
(36) Farrel, T.; Manning, A. R.; Mitchell, G.; Heck, J.; Meyer-
Friedrichsen, T.; Malessa, M.; Wittenburg, C.; Prosenc, M. H.; Cunningham,
D.; McArdle, P. Eur. J. Inorg. Chem. 2002, 1677.

Allenylidene Complexes of Chromium
Organometallics, Vol. 25, No. 24, 2006 5783
containing the product complexes 1-4 was eluted. In the synthesis
Pentacarbonyl(5-bromo-N-ethyl-3-hydropyridine-1,2-propa-
dienylidene)chromium (3a). Yield: 0.90 g (45%), red solid. Mp:
112-114 °C. IR (THF): ν(CO, CCC) 2077 vw, 2005 m, 1930 vs,
of 3 and 4 the pyridinylallenylidene complexes 5a1 and 5b
6
16
2 2
(pentane/CH Cl 1/4) were isolated as side products in low yield
-
1
1
3
(<5%).
1905 m cm . H NMR (400 MHz, d
6
-acetone): δ 1.50 (t, JHH
), 4.31 (q, JHH ) 7.0 Hz, 2H, NCH CH
.49 (dd, JHH ) 8.2 Hz, JHH ) 1.2 Hz, 1H, Pyr H), 7.70 (dd,
)
3
7
.4 Hz, 3H, NCH
2
CH
3
2
3
),
Pentacarbonyl(N-methyl-3-hydroquinoline-1,2-propadie-
nylidene)chromium (1a). Yield: 1.33 g (74%), deep violet solid.
Mp: 125-128 °C. IR (THF): ν(CO, CCC) 2076 vw, 2000 m, 1933
3
2
7
3
2
3
J
HH ) 7.8 Hz, JHH ) 1.2 Hz, 1H, Pyr H), 7.86 (t, JHH ) 8.2 Hz,
13
-
1
1
6 2 3
1H, Pyr H). C NMR (100 MHz, d -acetone): δ 13.1 (NCH CH ),
vs, 1907 m cm . H NMR (400 MHz, d
6
-acetone): δ 3.59 (s, 3H,
3
3
2 3 â
56.0 (NCH CH ), 113.2 (C ), 127.4, 130.1, 134.3, 143.4 (4 Pyr
C), 139.7 (C ), 190.5 (C ), 219.3 (cis-CO), 223.7 (trans-CO). FAB
γ R
NCH
3
), 7.59 (d, JHH ) 9.0 Hz, 1H, Quin H), 7.76 (t, JHH ) 8.2
Hz, 1H, Quin H), 8.05 (t, JHH ) 8.2 Hz, 1H, Quin H), 8.13 (m,
H, Quin H), 8.52 (d, JHH ) 9.0 Hz, 1H, Quin H). C NMR (100
MHz, d -acetone): δ 40.2 (NCH ), 117.9 (C ), 118.6, 126.7, 127.3,
28.0, 130.6, 134.8, 140.1, 141.9 (8 Quin C), 139.9 (C ), 200.9
), 219.2 (cis-CO), 224.0 (trans-CO). EI (MS): m/z (%) 359 (41)
3
+
+
3
13
(MS): m/z (%) 401 (21) [M ], 373 (19) [(M - CO) ], 345 (27)
2
+
+
+
[
(M - 2CO) ], 317 (22) [(M - 3CO) ], 289 (100) [(M - 4CO) ],
6
3
â
+
2
61 (70) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 512 (4.289).
(402.12): C, 41.82; H, 2.01; N,
1
γ
Anal. Calcd for C14
H
8
BrCrNO
5
(
[
[
C
R
+
+
+
3.48. Found: C, 41.97; H, 2.12; N, 3.50.
M ], 275 (16) [(M - 3CO) ], 247 (50) [(M - 4CO) ], 219 (100)
+
(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 544 (4.361). Anal.
Pentacarbonyl(5-bromo-N-ethyl-3-hydropyridine-1,2-propa-
dienylidene)tungsten (3b). Yield: 0.91 g (34%), red solid. Mp:
93-95 °C. IR (THF): ν(CO, CCC) 2080 vw, 2008 m, 1925 vs,
Calcd for C17
H
9
CrNO
5
(359.56): C, 56.84; H, 2.53; N, 3.90.
Found: C, 57.07; H, 2.72; N, 3.96.
-
1
1
3
1
7
899 m cm . H NMR (400 MHz, d
6
-acetone): δ 1.61 (t, JHH
), 5.05 (q, JHH ) 7.1 Hz, 2H, NCH CH
.62 (dd, JHH ) 8.2 Hz, JHH ) 1.2 Hz, 1H, Pyr H), 7.83 (dd,
)
Pentacarbonyl(N-methyl-3-hydroquinoline-1,2-propadie-
nylidene)tungsten (1b). Yield: 1.75 g (71%), deep violet solid.
Mp: 101-104 °C. IR (THF): ν(CO, CCC) 2080 vw, 2003 m, 1927
3
.0 Hz, 3H, NCH
2
CH
3
2
3
),
3
2
7
3
2
3
-
1
1
JHH ) 7.8 Hz, J ) 1.2 Hz, 1H, Pyr H), 7.98 (t, J ) 8.1 Hz,
vs, 1900 m cm . H NMR (400 MHz, d
6
-acetone): δ 4.62 (s, 3H,
HH
HH
1H, Pyr H). 13C NMR (100 MHz, d -acetone): δ 13.2 (NCH CH ),
3
3
NCH
3
), 7.66 (d, JHH ) 8.6 Hz, 1H, Quin H), 7.78 (td, JHH ) 7.0
6
2
3
2
4
3
4
â
56.2 (NCH CH ), 111.5 (C , J ) 25.0 Hz), 127.9, 130.3, 134.7,
Hz, JHH ) 1.2 Hz, 1H, Quin H), 8.09 (td, JHH ) 7.4 Hz, JHH
)
2
3
WC
1
3
4
γ R
143.5 (4 Pyr C), 140.6 (C ), 170.8 (C , J ) 100.0 Hz), 198.4
1
.0 Hz, 1H, Quin H), 8.17 (dd, JHH ) 7.8 Hz, JHH ) 1.1 Hz, 1H,
WC
1
1
3
3
(cis-CO, J ) 125.0 Hz), 203.0 (trans-CO, J ) 131.7 Hz).
Quin H), 8.24 (d, JHH ) 7.6 Hz, 1H, Quin H), 8.61 (d, JHH ) 7.8
WC
WC
+
+
Hz, 1H, Quin H). 13C NMR (100 MHz, d
FAB (MS): m/z (%) 535 (80) [M ], 507 (100) [(M - CO) ], 479
6
-acetone): δ 40.6 (NCH ),
15.6 (C ), 118.8, 126.9, 127.5, 128.3, 130.7, 134.9, 140.1, 142.4
8 Quin C), 141.5 (C
Hz), 203.3 (trans-CO). EI (MS): m/z (%) 491 (8) [M ], 463 (10)
3
+
+
(
92) [(M - 2CO) ], 451 (21) [(M - 3CO) ], 395 (31) [(M -
1
â
+
1
5CO) ]. UV/vis: λ (log ꢀ) [CH Cl ] 495 (4.326). Anal. Calcd
(
γ
), 178.7 (C
R
), 198.4 (cis-CO, JWC ) 121.2
max
2
2
+
14 8 5
for C H BrNO W (533.98): C, 31.49; H, 1.51; N, 2.62. Found:
C, 31.58; H, 1.50; N, 2.74.
+
+
+
[
2
(M - CO) ], 435 (11) [(M - 2CO) ], 351 (44) [(M - 5CO) ],
+
68 (100) [W(CO)
Anal. Calcd for C17
Found: C, 41.68; H, 1.78; N, 2.91.
4
]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 523 (4.413).
Pentacarbonyl(6-bromo-N-ethyl-3-hydropyridine-1,2-propa-
dienylidene)chromium (4a). Yield: 0.94 g (47%), red solid. Mp:
123 °C dec. IR (THF): ν(CO, CCC) 2078 vw, 2005 m, 2010 m,
H
9
NO W (491.11): C, 41.58; H, 1.85; N, 2.85.
5
-
1 1
1
(
6
930 vs, 1904 m cm . H NMR (400 MHz, d -acetone): δ 1.53
Pentacarbonyl(N-ethyl-3-hydroquinoline-1,2-propadienylidene)-
chromium (2a). Yield 1.26 g (68%), deep violet solid. Mp: 108-
3
3
t, JHH ) 7.2 Hz, 3H, NCH
2
CH
3
), 4.64 (q, JHH ) 7.2 Hz, 2H,
3
3
NCH
2
CH
3
), 7.42 (d, JHH ) 8.9 Hz, 1H, Pyr H), 8.15 (dd, JHH )
1
10 °C. IR (THF): ν(CO, CCC) 2076 vw, 2000 m, 1933 vs, 1907
2
2
-
1
1
3
8.8 Hz, J ) 2.2 Hz, 1H, Pyr H), 8.73 (d, J ) 2.2 Hz, 1H,
m cm . H NMR (400 MHz, d
6
-acetone): δ 1.60 (t, JHH ) 7.0
), 5.13 (q, JHH ) 7.0 Hz, 3H, NCH CH ), 7.53
d, JHH ) 9.1 Hz, 1H, Quin H), 7.72 (t, JHH ) 8.0 Hz, 1H, Quin
HH
HH
Pyr H). 13C NMR (100 MHz, d -acetone): δ 14.7 (NCH CH ), 55.3
3
Hz, 3H, NCH
(
2
CH
3
2
3
6
2
3
3
3
2 3 â
(NCH CH ), 111.5 (C ), 113.9, 131.3, 144.1, 145.3 (4 Pyr C), 136.0
(C ), 191.1 (C ), 219.2 (cis-CO), 223.5 (trans-CO). FAB (MS):
γ R
3
H), 8.03 (t, JHH ) 8.0 Hz, 1H, Quin H), 8.13 (m, 2H, Quin H),
+
+
3
13
m/z (%) 402 (31) [M ], 373 (5) [(M - CO) ], 345 (26) [(M -
8
.48 (d, JHH ) 9.1 Hz, 1H, Quin H). C NMR (100 MHz, d
acetone): δ 13.4 (NCH CH ), 48.5 (NCH CH ), 117.8 (C ), 118.1,
27.0, 127.9, 128.0, 130.9, 134.9, 140.3, 142.2 (8 Quin C), 138.9
), 201.5 (C ), 219.1 (cis-CO), 224.1 (trans-CO). EI (MS): m/z
%) 373 (32) [M ], 289 (17) [(M - 3CO) ], 261 (41) [(M -
6
-
+
+
+
2
CO) ], 317 (27) [(M - 3CO) ], 289 (41) [(M - 4CO) ], 261
2
3
2
3
â
+
(
100) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 511 (4.235).
1
Anal. Calcd for C14
8
H BrCrNO
5
(402.12): C, 41.82; H, 2.01; N,
(C
γ
R
+
+
3.48. Found: C, 41.79; H, 2.07; N, 3.55.
(
+
+
4
5
2
CO) ], 233 (100) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
43 (4.385). Anal. Calcd for C18 11CrNO (373.29): C, 57.92; H,
.97; N, 3.75. Found: C, 58.00; H, 3.09; N, 3.94.
Pentacarbonyl(N-ethyl-3-hydroquinoline-1,2-propadienylidene)-
tungsten (2b). Yield: 2.02 g (80%), deep violet solid. Mp: 93-
5 °C. IR (THF): ν(CO, CCC) 2080 vw, 2003 m, 1927 vs, 1900
2
Cl
2
]
Pentacarbonyl(6-bromo-N-ethyl-3-hydropyridine-1,2-propa-
dienylidene)tungsten (4b). Yield: 0.53 g (20%), red solid. Mp:
101-103 °C. IR (THF): ν(CO, CCC) 2081 vw, 2014 m, 2006 m,
H
5
-
1 1
1
(
6
924 vs, 1898 m cm . H NMR (400 MHz, d -acetone): δ 1.53
3
3
t, JHH ) 7.2 Hz, 3H, NCH
2
CH
3
), 4.64 (q, JHH ) 7.2 Hz, 2H,
3
3
NCH
2
CH
3
), 7.47 (d, JHH ) 8.6 Hz, 1H, Pyr H), 8.22 (dd, JHH )
9
2
2
-
1
1
3
9.0 Hz, J ) 2.3 Hz, 1H, Pyr H), 8.81 (d, J ) 2.0 Hz, 1H,
m cm . H NMR (400 MHz, d
6
-acetone): δ 1.50 (t, JHH ) 7.4
), 5.02 (q, JHH ) 7.4 Hz, 2H, NCH CH ), 7.46
d, JHH ) 7.6 Hz, 1H, Quin H), 7.59 (t, JHH ) 7.2 Hz, 1H, Quin
HH
HH
Pyr H). 13C NMR (100 MHz, d -acetone): δ 14.8 (NCH CH ), 55.6
3
Hz, 3H, NCH
(
2
CH
3
2
3
6
2
3
3
3
2 3 â
(NCH CH ), 109.5 (C ), 114.6, 131.6, 144.5, 145.6 (4 Pyr C), 137.1
1
3
3
γ R
(C ), 170.0 (C ), 198.4 (cis-CO, J ) 125.0 Hz), 202.8 (trans-
H), 7.91 (t, JHH ) 7.4 Hz, 1H, Quin H), 8.00 (d, JHH ) 7.8 Hz,
WC
1
+
H, Quin H), 8.10 (t, 3JHH ) 7.6 Hz, 1H, Quin H), 8.44 (d, JHH
3
CO, J ) 130.1 Hz). FAB (MS): m/z (%) 535 (80) [M ], 507
1
7
)
WC
+
+
.2 Hz, 1H, Quin H). 13C NMR (100 MHz, d
CH ), 48.7 (NCH CH ), 115.5 (C ), 118.2, 127.2, 127.3,
28.1, 130.9, 134.9, 140.1, 142.4 (8 QuinC), 138.9 (C ), 179.3 (C ),
98.3 (cis-CO, JWC ) 125.0 Hz), 203.3 (trans-CO, JWC ) 132.8
(44) [(M - CO) ], 479 (80) [(M - 2CO) ], 451 (87) [(M -
6
-acetone): δ 13.4
+
+
3
CO) ], 395 (100) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2 2
Cl ]
(
NCH
2
3
2
3
â
4
94 (4.324). Anal. Calcd for C14 BrNO W (533.98): C, 31.49;
H
8
5
1
1
γ
1
R
1
H, 1.51; N, 2.62. Found: C, 31.70; H, 1.55; N, 2.81.
+
+
Hz). EI (MS): m/z (%) 505 (28) [M ], 477 (17) [(M - CO) ],
General Procedure for the Coupling of Complexes 3 and 4
with Terminal Alkynes. A solution of 1 mmol of the complexes
3/4, 1 mL of triethylamine, and 5 equiv of the appropriate terminal
alkyne in 5 mL of dry THF was degassed in three freeze-pump
+
+
4
4
λ
49 (51) [(M - 2CO) ], 421 (33) [(M - 3CO) ], 391 (31) [(M -
+
+
+
CO) ], 363 (63) [(M - 5CO) ], 268 (100) [W(CO)
4
]. UV/vis:
max (log ꢀ) [CH Cl ] 523 (4.431). Anal. Calcd for C18H11NO W
2
2
5
(505.14): C, 42.80; H, 2.19; N, 2.77. Found: C, 43.03; H, 2.26;
3 2 2
cycles. Then 0.35 g (5 mol %) of [(PPh ) PdCl ] and 0.02 g (10
N, 2.78.
mol %) of CuI were added. The solution was stirred until all of the

5784 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
starting material was consumed (as indicated by TLC). The solvent
5
NO Cr (423.35): C, 62.42; H, 3.10; N, 3.31. Found: C, 62.02; H,
was evaporated and the residue chromatographed on silica at -20
3.30; N, 3.29.
°
C using mixtures of pentane and CH
2 2
Cl as the eluent.
Pentacarbonyl{N-ethyl-6-[(4-phenylethynyl)phenylethynyl]-
3-hydropyridine-1,2-propadienylidene}chromium (9a). Yield:
0.37 g (71%), red solid. Mp: 99-101 °C. IR (THF): ν(CO, CCC)
Pentacarbonyl{N-ethyl-6-[(trimethylsilyl)ethynyl]-3-hydropy-
ridine-1,2-propadienylidene}chromium (6a). Yield: 0.42 g (99%),
red solid. Mp: 89 °C. IR (THF): ν(CO, CCC) 2078 vw, 2002 m,
1
-
1 1
2077 vw, 2001 m, 1931 vs, 1904 m cm . H NMR (400 MHz,
-
1
1
3
930 vs, 1905 m cm . H NMR (400 MHz, d
6
-acetone): δ 0.24
CH ), 4.75 (q,
2 3
HH ) 7.1 Hz, 2H, NCH CH ), 7.54 (d, JHH ) 8.6 Hz, 1H, Pyr
d
J
6
-acetone): δ 1.55 (t, JHH ) 7.0 Hz, 3H, NCH
2
CH
), 7.30-7.51 (m, 10H, 4 Ar H +
JHH ) 8.6 Hz, JHH ) 2.0 Hz, 1H, Pyr H), 8.77
JHH ) 2.1 Hz, 1H, Pyr H). 13C NMR (100 MHz, d -acetone):
3
), 4.67 (q,
), 1.63 (t, 3JHH ) 7.0 Hz, 3H, NCH
3
2 3
CH
(
s, 3H, Si(CH
J
3
)
3
2
3
HH ) 7.2 Hz, 2H, NCH
Pyr H), 8.09 (dd,
(d,
δ 14.8 (NCH CH ), 55.4 (NCH CH ), 85.8 (CtC), 89.3 (CtC),
3
3
3
4
3
4
4
H), 8.07 (dd, JHH ) 8.6 Hz, JHH ) 1.6 Hz, 1H, Pyr H), 8.75 (d,
6
4
13
J
HH ) 1.6 Hz, 1H, Pyr H). C NMR (100 MHz, d
.1 (Si(CH ), 15.3 (NCH CH ), 55.8 (NCH CH ), 99.4 (CtC),
02.5 (CtC), 113.4 (C ), 116.9, 131.0, 144.7, 146.9 (4 Pyr C),
36.4 (C ), 193.7 (C ), 219.7 (cis-CO), 224.2 (trans-CO). FAB
6
-acetone): δ
2
3
2
3
9
(
(
2.6 (CtC), 95.4 (CtC), 113.1 (C
4 Pyr C), 123.3, 123.4, 125.5, 129.5, 129.7, 132.4, 132.6, 132.7
8 Ar C), 135.9 (C ), 192.9 (C ), 219.3 (cis-CO), 223.8 (trans-
â
), 116.7, 130.7, 144.0, 146.2
0
1
1
3
)
3
2
3
2
3
â
γ
R
γ
R
+
+
+
+
CO). FAB (MS): m/z (%) 523 (14) [M ], 467 (8) [(M - 2CO) ],
(MS): m/z (%) 419 (9) [M ], 363 (10) [(M - 2CO) ], 335 (11)
+
+
+
+
+
411 (100) [(M - 4CO) ], 383 (84) [(M - 5CO) ]. UV/vis: λ
[
(M - 3CO) ], 307 (67) [(M - 4CO) ], 279 (100) [(M - 5CO) ].
Cl ] 513 (4.314). Anal. Calcd for C19
SiCr (419.43): C, 54.41; H, 4.09; N, 3.34. Found: C, 53.91;
H, 4.02; N, 3.01.
max
(log ꢀ) [CH
2 2 5
Cl ] 522 (4.478). Anal. Calcd for C30H17NO Cr
UV/vis: λmax (log ꢀ) [CH
NO
2
2
17
H -
(523.47): C, 68.84; H, 3.27; N, 2.68. Found: C, 68.42; H, 3.25;
5
N, 2.72.
Pentacarbonyl[6-(4-ethynylphenyl)ethynyl-N-ethyl-3-hydro-
pyridine-1,2-propadienylidene]chromium (10a). Yield: 0.24 g
54%), red-violet solid. Mp: 91-93 °C. IR (THF): ν(CO, CCC)
Pentacarbonyl{N-ethyl-6-[(trimethylsilyl)ethynyl]-3-hydropy-
ridine-1,2-propadienylidene}tungsten (6b). Yield: 0.25 g (46%),
red solid. Mp: 81-82 °C. IR (THF): ν(CO, CCC) 2081 vw, 2004
(
-
1 1
-
1
1
2078 vw, 2001 m, 1931 vs, 1904 m cm . H NMR (400 MHz,
d
1H, CtCH), 4.66 (q, JHH ) 7.0 Hz, 2H, NCH
(m, 5H, Ar H + Pyr H), 8.08 (dd, JHH ) 8.6 Hz, JHH ) 2.0 Hz,
m, 1925 vs, 1898 m cm . H NMR (400 MHz, d
6
-acetone): δ
3
), 1.64 (t, 3JHH ) 7.0 Hz, 3H, NCH
6
-acetone): δ 1.55 (t, JHH ) 7.0 Hz, 3H, NCH
2
CH
3
), 3.76 (s,
0
4
1
8
d
CH
1
1
.24 (s, 3H, Si(CH
3
)
3
2
CH ),
3
3
3
3
2
CH ), 7.45-7.50
3
.75 (q, JHH ) 7.1 Hz, 2H, NCH CH ), 7.59 (d, JHH ) 8.4 Hz,
2 3
3
4
3
4
H, Pyr H), 8.12 (dd, JHH ) 8.6 Hz, JHH ) 2.3 Hz, 1H, Pyr H),
4
13
.81 (d, 4
13
1H, Pyr H), 8.75 (d, JHH ) 1.9 Hz, 1H, Pyr H). C NMR (100
MHz, d -acetone): δ 14.8 (NCH CH ), 55.4 (NCH CH ), 81.9 (Ct
C), 83.4 (CtC), 85.7 (CtC), 95.1 (CtC), 116.5 (C ), 113.1, 130.6,
44.0, 146.1 (4 Pyr C), 122.7, 124.3, 133.1, 133.8 (4 Ar C), 135.8
), 193.2 (C ), 219.3 (cis-CO), 223.7 (trans-CO). FAB (MS):
m/z (%) 447 (31) [M ], 391 (26) [(M - 2CO) ], 363 (29) [(M -
J
HH ) 2.2 Hz, 1H, Pyr H). C NMR (100 MHz,
), 15.0 (NCH CH ), 55.7 (NCH
), 99.1 (CtC), 102.6 (CtC), 111.1 (C ), 117.2, 131.0, 144.6,
47.0 (4 Pyr C), 137.3 (C ), 172.5 (C ), 198.6 (cis-CO, JWC
23.0 Hz), 203.2 (trans-CO, JWC ) 132.6 Hz). FAB (MS): m/z
6
2
3
2
3
6
-acetone): δ -0.28 (Si(CH
3
)
3
2
3
2
-
â
3
â
1
1
γ
R
)
(C
γ
R
1
+
+
+
+
(%) 551 (90) [M ], 523 (100) [(M - CO) ], 495 (82) [(M -
+
+
+
3
CO) ], 335 (71) [(M - 4CO) ], 307 (100) [(M - 5CO) ]. UV/
vis: λmax (log ꢀ) [CH Cl ] 522 (4.457). Anal. Calcd for C24
NO Cr (447.37): C, 64.44; H, 2.93; N, 3.13. Found: C, 62.91; H,
.14; N, 2.91. Due to the reactivity of the complex, a correct
+
+
2
4
CO) ], 411 (17) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2 2
Cl ]
2
2
13
H -
96 (4.350). Anal. Calcd for C19 SiW (551.28): C, 41.40;
H17NO
5
5
H, 3.11; N, 2.54. Found: C, 42.98; H, 3.34; N, 2.10.
3
Pentacarbonyl[N-ethyl-6-(n-dodec-1-ynyl)-3-hydropyridine-
,2-propadienylidene]chromium (7a). Yield: 0.33 g (67%), red
elemental analysis could not be obtained.
1
Pentacarbonyl[N-ethyl-6-(ferrocenylethynyl)-3-hydropyridine-
oil. IR (THF): ν(CO, CCC) 2077 vw, 2003 m, 1930 vs, 1903 m
cm . H NMR (400 MHz, d
3
1,2-propadienylidene]chromium (11a). Yield: 0.39 g (73%), red
-
1
1
3
6
-acetone): δ 0.74 (t, JHH ) 7.0 Hz,
21), 1.32 (m, 2H, C10 21), 1.46
), 2.37 (t,
solid. Mp: 77 °C dec. IR (THF): ν(CO, CCC) 2077 vw, 2002 m,
H, C10
H
21), 1.17 (m, 12H, C10
H
H
-
1 1
1
(
6
930 vs, 1903 m cm . H NMR (400 MHz, d -acetone): δ 1.66
3
(
J
m, 2H, C10
H
21), 1.50 (t, JHH ) 7.4 Hz, 3H, NCH
2
CH
3
3
3
2 3
t, JHH ) 7.4 Hz, 3H, NCH CH ), 4.27 (s, 5H, Fc H), 4.38 (t, JHH
3
3
HH ) 7.0 Hz, 3H, CH
2
CH
3
), 4.62 (q, JHH ) 7.4 Hz, 2H, NCH
2
-
3
)
1.6 Hz, 2H, Fc H), 4.57 (t, JHH ) 1.9 Hz, 2H, Fc H), 4.78 (q,
3
3
CH
3
), 7.41 (d, JHH ) 8.5 Hz, 1H, Pyr H), 7.91 (dd, JHH ) 8.6
3
3
J
2 3
HH ) 7.4 Hz, 2H, NCH CH ), 7.54 (d, JHH ) 8.4 Hz, 1H, Pyr
4
4
Hz, JHH ) 1.9 Hz, 1H, Pyr H), 8.54 (d, JHH ) 2.1 Hz, 1H, Pyr
H). 13C NMR (100 MHz, d
-acetone): δ 14.3 (C10 21), 14.9
NCH CH ), 19.7, 23.3, 29.0, 29.5, 29.8, 30.0, 30.2, 32.6 (C10 21),
5.2 (NCH CH ), 75.4 (CtC), 99.4 (CtC), 112.1 (C ), 117.9,
30.4, 144.4, 145.7 (4 Pyr C), 135.7 (C
3
4
H), 8.07 (dd, JHH ) 8.4 Hz, JHH ) 2.0 Hz, 1H, Pyr H), 8.75 (d,
6
H
4
13
J
HH ) 2.1 Hz, 1H, Pyr H). C NMR (100 MHz, d
4.9 (NCH CH ), 55.3 (NCH CH ), 63.9 (Fc C), 70.5 (Fc C), 70.9
Fc C), 72.4 (Fc C), 80.2 (CtC), 96.6 (CtC), 112.4 (C ), 117.9,
6
-acetone): δ
(
5
1
2
3
H
1
(
2
3
2
3
2
3
â
â
γ
), 190.3 (C
R
), 219.4 (cis-
1
30.5, 144.2, 145.6 (4 Pyr C), 137.7 (C
γ
), 190.1 (C
R
), 219.4 (cis-
+
CO), 223.7 (trans-CO). FAB (MS): m/z (%) 487 (23) [M ], 375
+
CO), 223.7 (trans-CO). FAB (MS): m/z (%): 531 (12) [M ], 446
+
+
(
ꢀ
95) [(M - 4CO) ], 347 (100) [(M - 5CO) ]. UV/vis: λmax (log
+
+
(
5
10) [(M - 3CO) ], 419 (41) [(M - 4CO) ], 391 (100) [(M -
) [CH Cl ] 502 (4.363). Anal. Calcd for C26 Cr (487.52):
2
2
H29NO
5
+
CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 519 (4.424). Anal. Calcd
C, 64.06; H, 6.00; N, 2.87. Found: C, 63.90; H, 5.61; N, 3.01.
for C26
H
17CrFeNO
5
(531.27): C, 58.78; H, 3.23; N, 2.64. Found:
Pentacarbonyl[N-ethyl-6-(phenylethynyl)-3-hydropyridine-
C, 58.43; H, 3.67; N, 2.64.
1
,2-propadienylidene]chromium (8a). Yield: 0.42 g (99%), red
Pentacarbonyl{N-ethyl-6-[4-(ferrocenylethynyl)phenylethy-
nyl]-3-hydropyridine-1,2-propadienylidene}chromium (12a).
Yield: 0.38 g (61%), red solid. Mp: 67 °C (dec). IR (THF): ν-
solid. Mp: 112-114 °C. IR (THF): ν(CO, CCC) 2078 vw, 2003
m, 1931 vs, 1904 m cm . H NMR (400 MHz, d -acetone): δ
6
-
1 1
3
3
-1 1
1
2
.44 (t, JHH ) 7.4 Hz, 3H, NCH
H, NCH CH ), 7.21-7.38 (m, 6H, Ar H + Pyr H), 8.07 (dd, JHH
2
CH
3
), 4.56 (q, JHH ) 7.4 Hz,
(CO, CCC) 2077 vw, 2002 m, 1931 vs, 1904 m cm . H NMR
3
3
2
3
(400 MHz, d -acetone): δ 1.54 (t, J ) 7.0 Hz, 3H, NCH CH ),
6
HH
2
3
4
4
3
3
)
8.6 Hz, JHH ) 2.0 Hz, 1H, Pyr H), 8.75 (d, JHH ) 2.1 Hz, 1H,
4.13 (s, 5H, Fc H), 4.20 (t, J ) 1.9 Hz, 2H, Fc H), 4.41 (t, J
HH
3
HH
13
Pyr H). C NMR (100 MHz, d
NCH CH ), 83.9 (CtC), 95.9 (CtC), 112.9 (C
44.0, 146.0 (4 Pyr C), 122.4, 129.6, 130.6, 132.4 (4 Ar C), 135.8
), 192.6 (C ), 219.3 (cis-CO), 223.8 (trans-CO). FAB (MS):
m/z (%) 423 (17) [M ], 367 (12) [(M - 2CO) ], 339 (19) [(M -
6
-acetone): δ 14.8 (NCH
2
CH
3
), 55.4
) 2.0 Hz, 2H, Fc H), 4.65 (q, J ) 7.2 Hz, 2H, NCH CH ),
HH
2
3
3
(
1
2
3
â
), 116.9, 130.5,
7.29 - 7.49 (m, 5H, 4 Ar H + Pyr H), 8.06 (dd, J ) 8.4 Hz,
HH
4
1
4
JHH ) 2.0 Hz, 1H, Pyr H), 8.73 (d, J ) 2.1 Hz, 1H, Pyr H).
HH
3
(C
γ
R
C NMR (100 MHz, d -acetone): δ 14.8 (NCH CH ), 55.4 (NCH -
6
2
3
2
+
+
CH ), 65.2 (Fc C), 70.0 (Fc C), 70.7 (Fc C), 72.2 (Fc C), 85.5
3
+
+
+
3CO) ], 311 (82) [(M - 4CO) ], 283 (100) [(M - 5CO) ]. UV/
(CtC), 85.7 (CtC), 92.5 (CtC), 95.6 (CtC), 113.0 (C
â
), 116.7,
vis: λmax (log ꢀ) [CH Cl ] 516 (4.452). Anal. Calcd for C22H -
2
2
13
130.6, 143.9, 146.0 (4 Pyr C), 121.4, 126.1, 132.3, 132.6 (4 Ar C),

Allenylidene Complexes of Chromium
35.7 (C ), 192.9 (C ), 219.3 (cis-CO), 223.7 (trans-CO). FAB
Organometallics, Vol. 25, No. 24, 2006 5785
1
γ
R
solution was stirred at this temperature for 60 min. The solvent
was evaporated, and the residue was chromatographed on silica at
-20 °C using mixtures of pentane and CH Cl (1/1 to 1/3) as the
2 2
+
+
(
(
(
MS): m/z (%) 629 (8) [M ], 517 (60) [(M - 4CO + H) ], 489
+
100) [(M - 5CO + H) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
(629.37): C, 64.89; H,
.04; N, 2.23. Found: C, 65.18; H, 3.32; N, 2.19.
Pentacarbonyl{N-ethyl-6-[4-(4-(ferrocenylethynyl)phenyl-
2
] 520
4.421). Anal. Calcd for C34
H19CrFeNO
5
eluent. Yield: 0.33 g (58%), orange solid. Mp: 65 °C dec. IR
(THF): ν(CC) 2114 w; ν(CO, CCC) 2078 vw, 2045 m (Ru-CO),
3
-
1 1
2
009 m, 1996 m (Ru-CO), 1928 vs, 1899 m cm . H NMR (400
3
MHz, d
6
-acetone): δ 1.49 (t, JHH ) 7.0 Hz, 3H, NCH
q, JHH ) 7.1 Hz, 2H, NCH CH ), 5.60 (s, 5H, Cp H), 7.31 (d,
JHH ) 8.6 Hz, 1H, Pyr H), 7.75 (d, J ) 8.6 Hz, 1H, Pyr H),
2 3
CH ), 4.58
ethynyl)phenylethynyl]-3-hydropyridine-1,2-propadienylidene}-
chromium (13a). Yield: 0.33 g (45%), red solid. Mp: 72 °C dec.
3
(
2
3
3
3
-
1
IR (THF): ν(CO, CCC) 2078 vw, 2001 m, 1931 vs, 1904 m cm
.
HH
8.30 (s, 1H, Pyr H). 13C NMR (100 MHz, d -acetone): δ 15.0
1
3
H NMR (400 MHz, d
6
-acetone): δ 1.66 (t, JHH ) 7.4 Hz, 3H,
6
3
2 3 2 3
(NCH CH ), 55.0 (NCH CH ), 89.6 (Cp C), 101.3 (CtC), 105.0
(CtC), 110.6 (C ), 122.2, 130.0, 144.7, 144.8 (4 Pyr C), 134.3
â
NCH CH ), 4.24 (s, 5H, Fc H), 4.32 (t, JHH ) 1.9 Hz, 2H, Fc H),
2
3
3
3
4
.53 (t, JHH ) 1.9 Hz, 2H, Fc H), 4.79 (q, JHH ) 7.4 Hz, 2H,
3
γ R
(C ), 182.7 (C ), 198.3 (Ru-CO), 219.6 (cis-CO), 223.7 (trans-
NCH
)
2
CH
3
), 7.33-7.63 (m, 9H, 4 Ar H + Pyr H), 8.20 (dd, JHH
+
4
4
CO). FAB (MS): m/z (%) 569 (21) [M + H ], 513 (9) [(M - CO
8.4 Hz, JHH ) 2.0 Hz, 1H, Pyr H), 8.89 (d, JHH ) 2.1 Hz, 1H,
+
+
13
+ H) ], 485 (14) [(M - 2CO + H) ], 457 (100) [(M - 4CO +
Pyr H). C NMR (100 MHz, d
NCH CH ), 65.7 (Fc C), 70.0 (Fc C), 70.7 (Fc C), 72.2 (Fc C),
8.0 (CtC), 85.1 (CtC), 90.9 (CtC), 91.9 (CtC), 95.4 (CtC),
7.2 (CtC), 113.1 (C ), 119.9, 130.7, 143.7, 146.2 (4 Pyr C), 122.8,
25.4, 129.4, 132.2, 132.5, 132.7, 133.1, 134.9 (8 Ar C), 135.9
), 185.0 (C ), 219.3 (cis-CO), 223.7 (trans-CO). FAB (MS):
6 2 3
-acetone): δ 14.7 (NCH CH ), 55.5
+
+
+
(
2
3
H) ], 429 (91) [(M - 5CO + H) ], 401 (28) [(M - 6CO + H) ],
+
7
9
1
373 (32) [(M - 7CO + H) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 487
(4.410). Anal. Calcd for C23
H
13CrNO
7
Ru (568.43): C, 48.60; H,
â
2.31; N, 2.46. Found: C, 48.84; H, 2.48; N, 2.63.
5
(C
γ
R
Pentacarbonyl{6-[dicarbonyl(η -pentamethylcyclopentadienyl)-
+
+
m/z (%) 731 (5) [M ], 619 (73) [(M - 4CO) ], 591 (100) [(M -
ferrio]ethynyl-N-ethyl-3-hydropyridine-1,2-propadienylidene}-
chromium (17a). A 0.02 g (10 mol %) amount of CuI and 0.36 g
+
5
CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 522 (4.529). Anal. Calcd
for C42
H25CrFeNO
5
(731.51): C, 68.96; H, 3.44; N, 1.91. Found:
(1.1 mmol) of [Cp*(CO) FeBr] were added at 0 °C to a solution
2
C, 68.13; H, 3.42; N, 1.76.
of 0.35 g (1 mmol) of complex 15a in 10 mL of THF/Et N (1/1),
3
Pentacarbonyl[N-ethyl-5-(ferrocenylethynyl)-3-hydropyridine-
,2-propadienylidene]tungsten (14a). Yield: 0.32 g (60%), red
solid. Mp: 111-112 °C. IR (THF): ν(CO, CCC) 2077 vw, 2009
and the solution was stirred at 0 °C for 60 min. The solvent was
evaporated, and the residue was chromatographed on silica at -20
2 2
°C using mixtures of pentane and CH Cl (1/1 to 1/3) as the eluent
to yield 0.26 g (38%) of a brown oil. IR (THF): ν(CC) 2095 w;
ν(CO, CCC) 2077 vw, 2017 m (Fe-CO), 2009 m, 1972 m (Fe-
1
-
1 1
m, 1930 vs, 1902 m cm . H NMR (400 MHz, d
6
-acetone): δ
), 4.36 (s, 5H, Cp), 4.53 (t,
HH ) 7.2 Hz, 2H, Cp), 4.78(t, JHH ) 1.6 Hz, 2H, Cp), 5.04 (q,
3
1
2 3
.67 (t, JHH ) 7.2 Hz, 3H, NCH CH
3
3
-1 1
J
CO), 1928 vs, 1899 m cm . H NMR (400 MHz, d
6
-acetone): δ
), 1.91 (s, 15H, Cp CH ),
), 7.40 (d, JHH ) 8.6 Hz,
1H, Pyr H), 7.88 (d, JHH ) 8.6 Hz, 1H, Pyr H), 8.39 (s, 1H, Pyr
H). 13C NMR (100 MHz, d
-acetone): δ 10.1 (Cp CH ), 15.2
(NCH CH ), 55.1 (NCH CH ), 99.0 (Cp C), 107.6 (CtC), 110.6
), 125.9 (CtC), 123.1, 130.0, 144.5, 144.8 (4 Pyr C), 133.7
), 181.6 (C ), 215.6 (Fe-CO), 219.9 (cis-CO), 223.9 (trans-
3
3
3
J
HH ) 1.6 Hz, 2H, NCH
2
CH
3
), 7.53 (d, JHH ) 8.4 Hz, 1H, Pyr
1.60 (t, JHH ) 7.0 Hz, 3H, NCH
4.69 (q, JHH ) 7.1 Hz, 2H, NCH
2
CH
CH
3
3
3
3
3
3
H), 7.63 (d, JHH ) 8.6 Hz, 1H, Pyr H), 8.25 (t, JHH ) 8.2 Hz,
2
3
3
1
5
(
H, Pyr H). 13C NMR (100 MHz, d
4.9 (NCH CH ), 71.2 (Cp), 71.8 (Cp), 73.3 (Cp), 78.7 (Cp), 83.5
), 125.3, 129.2, 136.7, 142.2 (4
), 219.5 (cis-CO), 223.7 (trans-CO).
6 2 3
-acetone): δ 13.7 (NCH CH ),
2
3
6
3
CtC), 105.4 (CtC), 111.9 (C
â
2
3
2
3
Pyr C), 138.3 (C ), 185.7 (C
γ
R
(C
(C
â
+
+
FAB (MS): m/z (%) 531 (21) [M ], 419 (69) [(M - 4CO) ], 391
γ
R
+
+
+
(
100) [(M - 5CO) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
2
] 524 (4.136).
CO). FAB (MS): m/z (%) 593 (20) [M ], 481 (90) [(M - 4CO) ],
453 (100) [(M - 5CO) ], 397 (63) [(M - 7CO) ]. UV/vis: λmax
(log ꢀ) [CH Cl ] 492 (4.284). C28 23CrFeNO (593.34). Due to the
+
+
Anal. Calcd for C26
H
17NO
5
Cr (531.27): C, 58.78; H, 3.23; N, 2.64.
Found: C, 58.63; H, 3.32; N, 2.54.
2
2
H
7
instability of the complex, a satisfactory elemental analysis could
not be obtained.
Pentacarbonyl(6-ethynyl-N-ethyl-3-hydropyridine-1,2-propa-
dienylidene)chromium (15a). A solution of 0.4 g (1 mmol) of 6a
in 50 mL of MeOH/THF (1/1) was treated at 0 °C with 0.1 g of
1,4-Bis{6,6′-[Pentacarbonyl(N-ethyl-3-hydropyridine-1,2-pro-
padienylidene)chromium]butadiyne (18a). To a solution of 0.35
g (1 mmol) of complex 15a in 10 mL of THF/pyridine (1/1) was
added 0.20 g (1.1 mmol) of Cu(OAc) at 0 °C. The solution was
2
stirred at this temperature for 180 min. The solvent was evaporated,
KF, KOH, or K
this temperature, 20 mL of degassed water was added. The solution
was extracted three times with CH Cl . The combined organic
extracts were dried over MgSO and filtered. The solvent was
removed, and the residue was chromatographed on silica at -20
C using mixtures of pentane and CH Cl (1/1 to 1/3) as the eluent.
Yield: 0.35 g (99%), red solid. Mp: 111 °C. IR (THF): ν(CO,
2 3
CO . After the mixture was stirred for 30 min at
2
2
4
and the residue was chromatographed on silica at -20 °C using
mixtures of pentane and CH Cl (1/1 to neat CH Cl ) as the eluent
2 2 2 2
°
2
2
to yield 0.21 g (60%) of a violet solid. Mp: 50 °C dec. IR (THF):
-
1
1
-1 1
CCC) 2077 vw, 2003 m, 1930 vs, 1904 m cm . H NMR (400
ν(CO, CCC) 2077 vw, 1993 m, 1933 vs, 1906 m cm . H NMR
3
3
MHz, d
6
-acetone): δ 1.53 (t, JHH ) 7.0 Hz, 3H, NCH
2
CH
3
), 4.06
(400 MHz, d
6
-acetone): δ 1.53 (t, JHH ) 7.0 Hz, 3H, NCH
2
CH
3
),
3
3
3
(
s, 1H, CtCH), 4.65 (q, JHH ) 7.1 Hz, 2H, NCH
2
CH
3
4
), 7.47 (d,
4.64 (q, JHH ) 7.1 Hz, 2H, NCH CH ), 7.49 (d, JHH ) 8.6 Hz,
2 3
3
3
3
4
J
HH ) 8.6 Hz, 1H, Pyr H), 8.02 (dd, JHH ) 8.6 Hz, JHH ) 1.6
1H, Pyr H), 8.10 (dd, JHH ) 8.6 Hz, JHH ) 2.0 Hz, 1H, Pyr H),
4
13
8.83 (d, 4
-acetone): δ 14.8 (NCH
78.7 (CtC), 114.7 (C ), 114.1, 130.8, 144.2, 147.9 (4 Pyr C), 136.1
(C ), 198.2 (C ), 219.1 (cis-CO), 223.8 (trans-CO). FAB (MS):
m/z (%) 692 (11) [M ], 636 (5) [(M - 2CO) ], 552 (81) [(M -
13
Hz, 1H, Pyr H), 8.69 (d, JHH ) 1.6 Hz, 1H, Pyr H). C NMR
J
HH ) 2.1 Hz, 1H, Pyr H). C NMR (100 MHz,
CH ), 55.5 (NCH CH ), 78.5 (CtC),
(
(
100 MHz, d
CtC), 85.7 (CtC), 115.8 (C
), 193.2 (C ), 219.3 (cis-CO), 223.7 (trans-CO). FAB
MS): m/z (%) 347 (21) [M ], 263 (17) [(M - 3CO) ], 235 (81)
6
-acetone): δ 14.8 (NCH
2 3
CH ), 55.4 (NCH
2
CH
3
), 78.0
d
6
2
3
2
3
â
), 112.8, 130.6, 144.6, 146.8 (4 Pyr
â
C), 136.3 (C
γ
R
γ
R
+
+
+
+
(
[
[
+
+
+
+
(M - 4CO) ], 207 (100) [(M - 5CO) ]. UV/vis: λmax (log ꢀ)
CH Cl ] 514 (4.345). Anal. Calcd for C16 NO Cr (347.28): C,
5.34; H, 2.61; N, 4.03. Found: C, 55.35; H, 2.65; N, 4.04.
5CO) ], 412 (100) [(M - 10CO) ]. UV/vis: λmax (log ꢀ) [CH
Cl ] 575 (4.685). Anal. Calcd for C32 (692.48): C,
55.50; H, 2.33; N, 4.05. Found: C, 54.67; H, 2.75; N, 3.78.
2
-
2
2
H
9
5
2
16 2 2
H N O10Cr
5
5
Pentacarbonyl{6-[dicarbonyl(η -cyclopentadienyl)ruthenio]-
Tetracarbonyl(diphenylferrocenylphosphane)(N-ethyl-3-hy-
dropyridine-1,2-propadienylidene)chromium (19a). A solution
containing 0.40 g (1 mmol) of allenylidene complex 5a and 0.44 g
ethynyl-N-ethyl-3-hydropyridine-1,2-propadienylidene}-
chromium (16a). A 0.02 g (10 mol %) amount of CuI and 0.33 g
(
0
1.1 mmol) of [Cp(CO)
.35 g (1 mmol) of complex 15a in 10 mL of THF/Et
2
RuBr] were added at 0 °C to a solution of
N (1/1). The
(1.2 mmol) of Ph
-20 °C while a slow stream of argon was passed through the
2
P(Fc) in 30 mL of dry THF was irradiated at
3

5
786 Organometallics, Vol. 25, No. 24, 2006
Szesni et al.
solution. Irradiation was stopped when the starting compound was
completely consumed (as indicated by IR spectroscopy; ca. 120
min). The solvent was removed in vacuo, and the residue was
chromatographed at -20 °C on silica using mixtures of pentane
Table 6. Crystallographic Data and Refinement Methods for
2a and 19a
2a
19a
empirical formula
Mr
C18H11CrNO5
373.28
C35H28CrFeNO4P
665.40
2 2
and CH Cl (1/1 to 1/3) as the eluent. A 0.41 g (62%) amount of
a violet solid was obtained. Mp: 111 °C dec. IR (THF): ν(CO,
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/n
11.502(4)
6.147(3)
24.670(9)
90
101.81(3)
90
1707.3(12)
4
monoclinic
P21/c
13.557(3)
17.219(3)
12.975(3)
90
97.52(3)
90
3002.9(10)
4
-
1 1
CCC) 2037 w, 1968 m, 1896 vs, 1887 vs, 1857 m cm . H NMR
3
(
4
7
400 MHz, d
6
-acetone): δ 1.38 (t, JHH ) 7.4 Hz, 3H, NCH
.04 (s, 5H, Fc H), 4.30-4.39 (m, 6H, 4Fc H + NCH CH ), 7.40-
.65 (m, 11H, 10 Ar H + Pyr H), 8.09 (d, JHH ) 8.4 Hz, 1H, Pyr
2 3
CH ),
2
3
3
R (deg)
â (deg)
γ (deg)
2
13
H), 8.77 (d, JHH ) 2.1 Hz, 1H, Pyr H). C NMR (100 MHz, d
acetone): δ 16.6 (NCH CH ), 55.5 (NCH CH ), 71.8 (Fc C), 72.8
d, JPC ) 5.8 Hz, Fc C), 76.5 (d, JPC ) 10.5 Hz, Fc C), 84.0 (d,
6
-
2
3
2
3
3
2
3
(
V (Å )
1
Z
J
â
PC ) 32.5 Hz, Fc C), 118.4 (C ), 119.8, 130.6, 142.4, 143.6 (4
3
3
4
cryst size (mm )
0.50 × 0.40 × 0.20
0.30 × 0.23 × 0.20
Pyr C), 137.8 (C
γ
), 129.3 (d, JPC ) 7.7 Hz, PAr C), 132.1 (d, JPC
-
3
Fcalcd (g cm
)
1.452
1.472
2
)
1.2 Hz, PAr C), 135.7 (d, JPC ) 18.1 Hz, PAr C), 143.0 (d,
-
1
µ (mm
F(000)
)
0.697
760
0.939
1368
1
2
J
R
PC ) 35.4 Hz, PAr C), 206.4 (d, JPC ) 20.7 Hz, C ), 225.1 (d,
2JPC ) 15.5 Hz, cis-CO), 230.8 (d, JPC ) 11.4 Hz, trans-CO), 231.0
2
radiation
λ (Å)
Mo KR
0.710 73
188(2)
Mo KR
(
d, 2JPC ) 2.9 Hz, cis-COtrans to P). 31P NMR (162.0 MHz, d
6
-
0.710 73
100(2)
+
T (K)
acetone): δ 60.0. FAB MS: m/z (%) 666 (21) [(M + H) ], 637
+
+
max 2θ (deg)
index range
54
58.4
(
[
15) [(M - CO + H) ], 610 (48) [(M - 2CO + H) ], 554 (39)
-7 e h e 14
0 e h e 18
-23 e k e 0
-17 e l e 17
8016
+
(M - 4CO + H) ]. UV/vis: λmax (log ꢀ) [CH
2
Cl
P (665.43): C, 63.18; H, 5.05;
N, 2.10. Found: C, 62.86; H, 4.43; N, 2.19.
µ-(9,10-η):(9,10-η)-[Pentacarbonyl(N-ethyl-6-phenylethynyl-
-hydropyridine-1,2-propadienylidene)chromium]bis-
tricarbonylcobalt)(Co-Co) (20a). A solution containing 0.30 g
0.71 mmol) of 8a and 0.24 g (0.85 mmol, 1.2 equiv) of [Co
CO) ] in 30 mL of dry THF was stirred at ambient temperature
2
] 539 (4.215).
-
7 e k e 7
-31 e l e 30
Anal. Calcd for C35
H28CrFeN O
2 4
no. of data
no. of unique data
parameters
4529
3727
8016
388
(
226
3
R1, wR2 (I > 2σ(I)
R1, wR2 (all data)
goodness of fit on F2
0.0548, 0.1037
0.1126, 0.1226
1.018
0.0530, 0.1119
0.0988, 0.1235
0.856
(
(
(
2
-
8
out as described in ref 47. Instead of the third harmonic (355 nm)
generated from an Nd:YAG laser with a wavelength of 1064 nm
the optical parametric oscillator (OPO)48 in use was pumped with
the second harmonic (532 nm). The signal intensity at 824 nm and
the fundamental at 532 nm were removed from the Idler using
dichroic mirrors (HR 650-850 and HR 532), a green light, and a
silicon filter (transparent >1000 nm). An additional Glan-Taylor
polarizer ensured the vertical polarization of the beam into the
until all of the starting compounds were completely consumed (as
indicated by TLC; ca. 180 min). The solvent was removed in vacuo.
The residue was chromatographed at -20 °C on silica using
mixtures of pentane and CH
.41 g (58%) of a brown-violet oil. IR (THF): ν(CO, CCC) 2095
m (Co-CO), 2076 vw, 2060 m (Co-CO), 2033 m (Co-CO), 2001
2 2
Cl (1/1 to 1/2) as the eluent to yield
0
-
1 1
6
m, 1930 vs, 1904 m cm . H NMR (400 MHz, d -acetone): δ
3
3
1
2
.51 (t, JHH ) 7.2 Hz, 3H, NCH
2 3
CH ), 4.72 (q, JHH ) 7.2 Hz,
-4
-6
measurement cell. Measurements were performed with 10 -10
H, NCH CH ), 7.32 (m, 3H, 3 Ar H), 7.56 (m, 2H, 2 Ar H + Pyr
2
3
M solutions. The validity of Beer’s law was confirmed by UV/vis
measurements of samples with corresponding concentrations.
Disperse Red 1 (DR 1) was used as an external standard with a
3
4
H), 8.11 (d, JHH ) 8.4 Hz, 1H, Pyr H), 8.77 (d, JHH ) 2.0 Hz,
1
5
H, Pyr H). 13C NMR (100 MHz, d
5.1 (NCH CH ), 120.0 (C ), 126.9, 130.9, 142.3, 142.5 (4 Pyr
), 129.4, 130.0, 130.1, 135.7 (4 Ar C), 189.3 (C ),
09.9 (COCo), 219.4 (cis-CO), 223.7 (trans-CO). FAB MS: m/z
6 2 3
-acetone): δ 15.1 (NCH CH ),
2
3
â
-
30
value of â1500(DR 1) ) 70 × 10
esu. This value was obtained
Cl and CHCl to
Using the value â(CHCl
esu,50 the hyperpolarizibility of DR 1 in CH
Cl is estimated to be
C), 138.1 (C
γ
R
by comparing the slopes of the reference in CH
2
2
3
-30
2
49
obtain the ratio of âsolute
.
3
) ) 80 × 10
+
+
(
[
(
%) 666 (21) [(M + H) ], 637 (15) [(M - CO + H) ], 610 (48)
(M - 2CO + H) ], 554 (39) [(M - 4CO + H) ]. UV/vis: λmax
log ꢀ) [CH Cl ] 522 (4.198). C28 CrNO11 (709.27). Due to
2
2
+
+
-
30
7
0 × 10 esu. The effect of the refractive indices of the solvents
2
2
H13Co
2
51
was corrected using the simple Lorentz local field.
the instability of the complex, a satisfactory elemental analysis could
not be obtained.
X-ray Structural Analysis of 2a and 19a. Single crystals
suitable for an X-ray structural analysis (Table 6) were grown by
slow diffusion of hexane into a concentrated solution of 2a or 19a
Cyclic Voltammetric and Spectroelectrochemical Measure-
ments. Cyclic voltammograms of 11a-13a were recorded using a
2 2
in CH Cl at 4 °C. The measurements were performed with a crystal
+
-
2 2 4 6
PAR 263 instrument in CH Cl (0.1 M [(n-Bu) N] PF ) at 25 °C
mounted on a glass fiber on a Siemens P4 diffractometer (graphite
monochromator, Mo KR radiation, λ ) 0.710 73 Å). For the data
collection the Wyckoff technique was used. The structure was
solved by direct methods using the SHELXTL-97 program pack-
age.52 The positions of the hydrogen atoms were calculated by
assuming ideal geometry, and their coordinates were refined
together with those of the attached carbon atoms as a “riding
model”. All other atoms were refined anisotropically.
at a platinum electrode, with an SCE reference electrode and
ferrocene as internal calibrant (0.460 V vs SCE). The electrochemi-
cal data of 14a and 19a (supporting electrolyte 0.13 M [(n-
+
-
Bu)
Model 273 potentiostat utilizing the EG&G 250 software package.
The OTTLE cell used for spectroelectrochemistry in 1,2-C Cl
obtained from Acros and freshly distilled from CaH ) follows the
4 6
N] PF ) were acquired with a computer-controlled EG&G
H
2 4
2
(
2
46
design by Hartl et al. It comprises Pt-mesh working and counter
electrodes and a thin silver wire as a pseudo-reference electrode
(47) Stadler, S.; Dietrich, G.; Bourhill, G.; Br a¨ uchle, C.; Pawlik, A.;
Grahn, W. Chem. Phys. Lett. 1995, 247, 271.
2
sandwiched between the CaF windows of a conventional liquid
IR cell. The working electrode is positioned in the center of the
spectrometer beam.
(
48) Paralite Optical Parametrical Oscillator, LAS GmbH.
(49) Kodaira, T.; Watanabe, A.; Ito, O.; Matsuda, M.; Clays, K.;
Persoons, A. J. Chem. Soc., Faraday Trans. 1997, 93, 3039.
50) Lambert, C. N o¨ ll, G.; Schm a¨ lzlin, E.; Meerholz, K. Br a¨ uchle, C.
Chem. Eur. J. 1998, 4, 2129.
51) Lambert, C.; Gaschler, W.; Schm a¨ lzlin, E.; Meerholz, K. Br a¨ uchle,
(
HRS Measurements of the First Hyperpolarizabilities of 11a-
3a. The measurements at a wavelength of 1500 nm were carried
1
(
C. J. Chem. Soc., Faraday Trans. 2 1999, 577.
(52) Sheldrick, G. M. SHELX-97, Programs for Crystal Structure
Analysis, University of G o¨ ttingen, G o¨ ttingen, Germany, 1997.
(
79.
46) Krejcik, M.; Danek, M.; Hartl, F. J. Electroanal. Chem. 1991, 317,
1

Allenylidene Complexes of Chromium
Organometallics, Vol. 25, No. 24, 2006 5787
Acknowledgment. Support of these investigations by Wacker-
Chemie GmbH (gift of chemicals) is gratefully acknowledged.
including atomic coordinates, anisotropic displacement parameters,
and geometric data. This material is available free of charge via
the Internet at http://pubs.acs.org.
Supporting Information Available: CIF files giving further
details of the structure determination of complexes 2a and 19a,
OM0607301