Addition of N-aryl imines to alkyne(pentacarbonyl)chromium and tungsten - A novel route to alkenyl(amino)carbene complexes

Article abstract of DOI:10.1016/S0022-328X(00)00010-3

Photolysis of [M(CO)₆] in CH₂Cl₂ gives [(CO)₅M(CH₂Cl₂)] (M = Cr, W). Replacement of CH₂Cl₂ by arylacetylene, HC≡CC₆H ₄R-p (R = Me, H, Br), produces the thermolabile arylacetylene complexes [(CO)₅M(HC≡CC₆H₄R-p)]. Addition of N-phenyl benzylideneimines, PhN = C(C₆H₄ R′-p)H (R′ = Me, H, Cl), to solutions of these alkyne complexes affords alkenyl(amino)carbene complexes, [(CO)₅M=C(NPhH)C (C₆H₄R-p))=C(C₆H₄R′-p))H], and 2-azetidin-1-ylidene complexes, [(CO)₅M=C-NPh-C(C ₆H₄R′-p)H-C(C₆H₄R-p)H]. The formation of the alkenyl(amino)carbene complexes is favored. The ratio alkenyl(amino)carbene/2-azetidin-l-ylidene complex is 2.5-3 for M = W and 6.5-8 for M = Cr. Both types of complexes are obtained as mixtures of isomers. The 2-azetidin-1-ylidene complexes are very likely formed by cycloaddition of the imines to the C=C bond of vinylidene complexes resulting from tautomerization of the alkyne complexes. The cycloaddition is highly stereoselective. Predominantly, the syn isomer is obtained (syn/anti ≥ 9). In contrast, the alkenyl(amino)carbene complexes are presumably derived from the alkyne complexes via cycloaddition of the imines to the coordinated alkyne and subsequent 1,2-hydrogen shift and ring opening. Preferentially, the E isomers (where both aryl substituents are cis with respect to the C=C bond) are produced. The structure of the major isomer of the alkenyl(amino)carbene complex [(CO)₅W=C(NPhH)C(C₆ H₄Me-p)=C(Ph)H] has been established by X-ray structural analysis.

Full text of DOI:10.1016/S0022-328X(00)00010-3

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 599 (2000) 288–297
Addition of N-aryl imines to alkyne(pentacarbonyl)chromium and
tungsten — a novel route to alkenyl(amino)carbene complexes
Mokhles M. Abd-Elzaher 1, Thomas Froneck, Gerhard Roth, Valentin Gvozdev,
Helmut Fischer *
Fachbereich fu¨r Chemie, Uni6ersita¨t Konstanz, Uni6ersita¨tsstraße 10, Fach M727, D-78457 Konstanz, Germany
Received 25 October 1999; accepted 20 December 1999
Dedicated to Professor Dirk Walther on the occasion of his 60th birthday.
Abstract
Photolysis of [M(CO)6] in CH2Cl2 gives [(CO)5M(CH2Cl2)] (M=Cr, W). Replacement of CH2Cl2 by arylacetylene,
HCꢀCC6H4R-p (R=Me, H, Br), produces the thermolabile arylacetylene complexes [(CO)5M(HCꢀCC6H4R-p)]. Addition of
N-phenyl benzylideneimines, PhN=C(C6H4R%-p)H (R%=Me, H, Cl), to solutions of these alkyne complexes affords alkeny-
l(amino)carbene
complexes,
[(CO)5MꢁC(NPhH)C(C6H4R-p)ꢁC(C6H4R%-p)H],
and
2-azetidin-1-ylidene
complexes,
¸¹¹¹¹¹¹¹¹¹¹¹¹¹º
[(CO)5MꢁCꢂNPhꢂC(C6H4R%-p)HꢂC(C6H4R-p)H]. The formation of the alkenyl(amino)carbene complexes is favored. The ratio
alkenyl(amino)carbene/2-azetidin-1-ylidene complex is 2.5–3 for M=W and 6.5–8 for M=Cr. Both types of complexes are
obtained as mixtures of isomers. The 2-azetidin-1-ylidene complexes are very likely formed by cycloaddition of the imines to the
CꢁC bond of vinylidene complexes resulting from tautomerization of the alkyne complexes. The cycloaddition is highly
stereoselective. Predominantly, the syn isomer is obtained (syn/anti]9). In contrast, the alkenyl(amino)carbene complexes are
presumably derived from the alkyne complexes via cycloaddition of the imines to the coordinated alkyne and subsequent
1,2-hydrogen shift and ring opening. Preferentially, the E isomers (where both aryl substituents are cis with respect to the CꢁC
bond) are produced. The structure of the major isomer of the alkenyl(amino)carbene complex [(CO)5WꢁC(NPhH)C(C6H4Me-
p)ꢁC(Ph)H] has been established by X-ray structural analysis. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: N-aryl imines; Alkyne(pentacarbonyl)chromium; Alkyne(pentacarbonyl)tungsten
1. Introduction
complexes of manganese and rhenium and imines [4],
and from [(CO)5WꢁCꢁCPh2] and imines [5]. In general,
oxidative decomplexation of the four-membered ring
yields b-lactams in moderate to good yields. A vinyli-
dene complex, [(CO)5CrꢁCꢁCH2], was also proposed as
an intermediate in the reactions of pentacarbonyl[hy-
droxy(methyl)carbene]chromium with dicyclohexyl car-
bodiimide [6] and of tetramethylammonium acetyl-
(pentacarbonyl)chromate toluene-4-sulfonyl chloride/
imines [2,7], to give 2-azetidin-1-ylidene complexes
(Scheme 1).
Usually, the vinylidene complexes are generated ei-
ther from carbyne complexes, from acyl complexes or
from carbene complexes.
Recently, we observed that reactions of photochemi-
cally generated [(CO)5M(CH2Cl2)] with phenylacetylene
and N-alkyl imines [8] also afforded 2-azetidin-1-yli-
Vinylidene complexes may be regarded as
organometallic analogues of ketenes. Ketenes react with
imines by cycloaddition to afford b-lactams [1].
Analogously, several vinylidene complexes have been
shown to readily add imines to the CꢁC bond to form
four-membered transition-metal-substituted N-hetero-
cycles (Scheme 1). Examples include the formation of
2-azetidin-1-ylidene complexes from [Cp(CO)(L)Feꢁ
CꢁCR2]+ [L=P(OMe)3, PPh3; R=H, Me] and
MeNꢁC(H)aryl or thiazolines [2,3], from vinylidene
* Corresponding author. Tel.: +49-7531-882783; fax: +49-7531-
883136.
E-mail address: hfischer@dg6.chemie.uni-konstanz.de (H. Fischer)
1 Present address: Inorganic Chemistry Department, National Re-
search Centre, PO 12622 Dokki, Cairo, Egypt.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00010-3

M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
289
dene complexes and we proposed the following se-
quence: (a) substitution of phenylacetylene for coordi-
nated CH2Cl2; (b) tautomerization of the resulting
alkyne complexes [(CO)5M(HCꢀCPh)] to give the corre-
zylideneimine and N-phenyl p-methylbenzylideneimine,
respectively, yielded isomeric mixtures of the (expected)
2-azetidin-1-ylidene complexes 4a–6a and the (rather
unexpected) alkenyl(amino)carbene complexes 4b–6b
(Scheme 2). Independent of the substituent and the
metal, predominantly the alkenyl(amino)carbene com-
plexes were formed. Within error limits, the yield ratios
4b/4a and 5b/5a were the same (about 2.5). However,
substitution of chromium for tungsten more strongly
favored the formation of the alkenyl(amino)carbene
complex (6b/6a=6.5).
sponding
vinylidene
complexes
[(CO)5MꢁCꢁ
C(Ph)H]; which (c) are then trapped by the imine as
2-azetidin-1-ylidene complexes.
We now report that the corresponding reactions of
[(CO)5M(CH2Cl2)] with arylacetylene and N-aryl imines
essentially take a different course giving rise to the
formation of alkenyl(amino)carbene complexes.
The 1H-NMR data indicated that after chromato-
graphic work-up the 2-azetidin-1-ylidene complexes
4a–6a were obtained as mixtures of two stereoisomers
(syn and anti ), which could not be separated by column
chromatography. The resonances of the protons
bonded to the ring C(aryl) atoms of the major isomer
appeared as doublets at l=6.51–6.64 and 4.53–4.67
ppm (3JH,H=4.6–4.7 Hz, each), suggesting a syn ar-
rangement of these protons. The coupling constant for
the corresponding signals of the minor isomer at l=
2. Results and discussion
Addition of arylacetylenes at −80°C to solutions of
[(CO)5M(CH2Cl2)] freshly prepared by irradiation of
the metal hexacarbonyls [M(CO)6] in dichloromethane
at −85°C afforded the arylacetylene(pentacarbonyl)
complexes 1–3 via replacement of the coordinated
dichloromethane by alkynes (Scheme 2). Subsequent
reaction of 1–3 with two equivalents of N-phenyl ben-
3
5.74–5.83 and 3.94–4.10 ppm was JH,H=1.7 Hz, es-
tablishing that these protons were anti to each other.
Therefore, the thermodynamically less stable syn iso-
mers dominated in each case.
The syn/anti ratio increased only slightly both with
the substituent R (M=W: syn/anti=84:16 [R=Ph],
90:10 [p-Tol] and the metal (R=Ph: syn/anti=84:16
[W], 80:20 [Cr]).
The alkenyl(amino)carbene complexes were similarly
obtained as mixtures of two isomers. Presumably, the
isomers differed by the arrangement of the substituents
at the CꢁC bond. The ratio of isomers was about 9:1.
Predominantly, the E isomers (both aryl substituents
are mutually cis) were formed as deduced from the
1H-NMR chemical shifts for ꢁCH based on the an-
isotropy of the vicinal aryl substituent and the X-ray
structural analysis of 11b.
Scheme 1.
When alkynes and benzylideneimines with different
para substituents at the aryl groups were employed, the
formation of only one regioisomer of the 2-azetidin-1-
ylidene complexes and the alkenyl(amino)carbene com-
plexes was observed. In all cases, the aryl substituent of
the alkyne ended up at the C4 position of the 2-aze-
tidin-1-ylidene complex and at the Ca position (adjacent
to the carbene carbon) of the CꢁC bond in the alkeny-
l(amino)carbene complexes (Scheme 3).
The yields of 9a–14a and 9b–14b were similar to
those of the tungsten complexes 4a–5a and 4b–5b. The
same applied to the chromium complexes 15a–17a and
15b–17b. The ratios of alkenyl(amino)carbene com-
plex/2-azetidin-1-ylidene complex were about 3 (M=
W) and
8
(M=Cr). Usually, two isomeric
alkenyl(amino)carbene complexes were formed. The
isomeric ratio varied between 7:3 and 9:1.
Scheme 2.

290
M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
2. the attachment of the p-tolyl group to the Ca atom;
3. the strong deviation of the carbene and the olefinic
plane from coplanarity (torsion angle W(1)ꢂC(6)ꢂ
C(7)ꢂC(8) 120.6(4)°; for a projection of the molecule
along the C(6)ꢂC(7) axis see Fig. 2) and;
4. the Z orientation of the phenyl group at the partial
,
C(6)ꢂN(1) double bond (1.324(6) A).
The carbene carbon is planar coordinated (sum of
angles: 359.5°). However, the formation of an extended
W(1)ꢂC(6)ꢂC(7)ꢂC(8) p system is prevented by the tilt
of the olefin against the carbene plane, which is proba-
bly due to reduction in steric congestion. As a conse-
,
quence, the C(6)ꢂC(7) bond is rather long (1.503(7) A).
The distance compares well with that in carbene com-
plexes with an orthogonal or almost orthogonal ar-
rangement of the carbene and the alkene plane (e.g.
,
1.511(12)
A
in [(CO)5WꢁC(NEt2)ꢂC(CHꢁCH2)ꢁ
C(H)C6H4Me-p] (torsion angle −84.5(11)°) [9] and
,
1.488(8) A in [(CO)5CrꢁC(OMe)ꢂC(Me)ꢁC(H)Me] [10]).
In contrast, the bond length of the central CꢂC single
bond in complexes with a coplanar or an almost copla-
nar arrangement of the carbene and the alkene plane is
Scheme 3.
,
,
usually in the range 1.40–1.47 A (e.g. 1.427(4) A in
[(CO)5CrꢁC(NH2)ꢂCHꢁC(NMe2)Ph] {torsion angle
Table 1
,
Selected bond lengths (A) and bond angles (°) for 11b
Bond lengths
W(1)ꢂC(1)
W(1)ꢂC(3)
W(1)ꢂC(5)
C(6)ꢂC(7)
C(7)ꢂC(8)
C(8)ꢂC(31)
C(11)ꢂC(12)
2.044(6)
2.041(6)
2.024(7)
1.503(7)
1.362(8)
1.476(8)
1.379(9)
W(1)ꢂC(2)
W(1)ꢂC(4)
W(1)ꢂC(6)
C(6)ꢂN(1)
C(7)ꢂC(21)
N(1)ꢂC(11)
2.040(6)
2.027(6)
2.239(6)
1.324(6)
1.479(7)
1.439(6)
Bond angles
C(1)ꢂW(1)ꢂC(5)
C(3)ꢂW(1)ꢂC(5)
C(1)ꢂW(1)ꢂC(6)
C(3)ꢂW(1)ꢂC(6)
C(5)ꢂW(1)ꢂC(6)
W(1)ꢂC(6)ꢂN(1)
C(6)ꢂC(7)ꢂC(8)
C(8)ꢂC(7)ꢂC(21)
C(6)ꢂN(1)ꢂC(11)
N(1)ꢂC(11)ꢂC(16)
C(7)ꢂC(21)ꢂC(26)
C(8)ꢂC(31)ꢂC(36)
87.7(3)
84.5(3)
91.4(2)
C(2)ꢂW(1)ꢂC(5)
C(4)ꢂW(1)ꢂC(5)
C(2)ꢂW(1)ꢂC(6)
C(4)ꢂW(1)ꢂC(6)
W(1)ꢂC(6)ꢂC(7)
C(7)ꢂC(6)ꢂN(1)
C(6)ꢂC(7)ꢂC(21)
C(7)ꢂC(8)ꢂC(31)
N(1)ꢂC(11)ꢂC(12)
C(7)ꢂC(21)ꢂC(22)
C(8)ꢂC(31)ꢂC(32)
89.4(3)
89.2(2)
86.4(2)
96.6(2)
95.1(2)
175.7(2)
128.7(4)
118.6(5)
124.6(5)
128.9(5)
120.5(5)
120.2(4)
124.9(5)
121.6(3)
109.2(5)
116.7(5)
129.9(5)
117.9(5)
121.9(5)
117.4(5)
Fig. 1. Structure of the major isomer of complex 11b (hydrogen
atoms omitted for clarity).
The structure of the major isomer of the alkenyl-
(amino)carbene complex 11b obtained from
[(CO)5W(HCꢀCTol-p)] and PhNꢁC(H)Ph was estab-
lished by an X-ray structural analysis (Table 1 and Fig.
1).
The most important features of the structure of 11b
are
1. the mutual cis orientation of both aryl groups at the
Ca=Cb bond;
Fig. 2. Projection of complex 11b along the C(6)ꢂC(7) axis.

M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
291
It is reasonable to assume that the alkenyl-
(amino)carbene complexes are derived from the 2-aze-
tidin-1-ylidene complexes either by: (a) deprotonation
at C4, followed by subsequent ring opening and repro-
tonation at nitrogen; or (b) by 1,3-migration of the
proton at C4 and ring opening. However, both mecha-
nisms disagree with the experimental facts. The trans-
formation of 2-azetidin-1-ylidene complexes into
alkenyl(amino)carbene complexes can be induced nei-
ther thermally nor by the presence in excess of imines,
aniline or NaOMe. When trifluoroacetic acid was
added to solutions of 5a, only decomposition of 5a
was observed. The formation of the alkenyl-
(amino)carbene complex 5b could not be detected.
These observations indicate that 5b is not derived
from 5a but rather that in the reaction of
[(CO)5M(alkyne)] complexes with N-aryl imines, 2-aze-
tidin-1-ylidene and alkenyl(amino)carbene complexes
are formed simultaneously.
A mechanism consistent with all observations is
shown in Scheme 4, path (a). Cycloaddition of the
imine (very likely in a stepwise fashion) to the car-
bon–carbon bond of the coordinated alkyne pre-
sumably gives the dehydroazetidine p-complex A. A
subsequent 1,2-hydrogen shift and ring opening by an
electrocyclic process could finally produce the alkenyl-
(amino)carbene complexes. The formation of the Z
isomer (with respect to the partial C(carbene)ꢂN
bond) is very likely determined in the 1,2-hydrogen
shift step, that of the cis isomer (with respect to the
CꢁC bond) presumably in the cycloaddition step to
form the four-membered ring in A.
In summary, the reactions of imines with terminal
alkynes coordinated to (CO)5M-fragments strongly de-
pend on the substituent at nitrogen of the imine. N-
Alkyl imines exclusively give 2-azetidin-1-ylidene
complexes. Other coupling products have so far not
been observed. In contrast, in the reactions with the
less nucleophilic N-aryl imines predominantly alkenyl-
(amino)carbene complexes are formed and the corre-
sponding 2-azetidin-1-ylidene complexes are obtained
in rather small amounts. It is very likely that the type
of product is already determined in the initial reaction
step and depends on whether the imine adds to the
alkyne or the vinylidene tautomer.
Alkenylcarbene complexes are usually prepared ei-
ther by the classical Fischer route via addition of
alkenyl lithium to a metal carbonyl and subsequent
alkylation of the resulting metallate [16], by addition of
protic nucleophiles to the CꢀC bond of alkynylcarbene
complexes [17,18], by insertion of p-donor substituted
alkynes into the MꢁC bond of carbene complexes
[16,19] or by cycloaddition of olefins to alkynylcarbene
complexes [18]. The synthesis of alkenylcarbene com-
plexes from alkyne complexes and imines constitutes a
new approach to this type of carbene complexes.
Scheme 4.
,
169.4°} [11], 1.418(5)
A
in [(CO)5CrꢁC{Nꢁ
C(OMe)Ph}-CHꢁC(H)NMe2] (torsion angle 175.7°)
,
[12] and 1.407(5)
A
in [(CO)5CrꢁC(OEt)ꢂCHꢁ
C(Ph){N(CH2)4}] (torsion angle 173.0°) [13]). To re-
duce unfavorable steric interaction the planes at N(1)
and Ca are strongly tilted against the carbene plane
(torsion angles: C(6)ꢂC(7)ꢂC(21)ꢂC(22) 123.6(6)°,
C(6)ꢂN(1)ꢂC(11)ꢂC(12) −110.7(7)°). As is usually ob-
served with (CO)5M–carbene complexes, the carbene
plane bisects the adjacent OCꢂWꢂCO angle (torsion
angle C(3)ꢂW(1)ꢂC(6)ꢂC(7) 40.6(4)°).
The 2-azetidin-1-ylidene complexes are presumably
formed by tautomerization of the alkyne complexes to
vinylidene complexes, addition of the N-aryl benzyli-
deneimine to the metal-bound vinylidene carbon atom
and subsequent ring-closure (Scheme 4, route (b)). A
similar mechanism has already been proposed for the
formation of 2-azetidin-1-ylidene complexes from
[(CO)5W(alkyne)] complexes and N-alkyl imines [8].
Although it was not possible to detect the vinylidene
complexes by IR or NMR spectroscopy, the presence
of the vinylidene complex tautomers in solution is
plausible on the basis of trapping experiments with
alcohols, ynamines and alkoxyalkynes to give alkoxy-
carbene [14] and cyclobutenylidene complexes [15], re-
spectively. The cycloaddition is regiospecific. The
formation of the regioisomeric 3-azetidin-1-ylidene
complexes has not been observed.

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M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
3. Experimental
3.1. General
K): l 203.6 (trans-CO), 196.0 (cis-CO), 132.0, 131.3,
127.7, 125.5 (aryl), 67.6 (ꢀCꢂC6H4), 58.4 (ꢀCꢂH).
3.2.3. Pentacarbonyl(p2-p-tolylacetylene)chromium (8)
IR (CH2Cl2, 243 K) w(CO) (cm−1): 2074 m, 1953 vs,
All operations were performed under an inert atmo-
sphere (nitrogen or argon) by using standard Schlenk
techniques. Solvents were dried by refluxing over CaH2
(CH2Cl2, pentane) or sodium–benzophenone ketyl
(Et2O) and were freshly distilled prior to use. The silica
gel used for chromatography (Baker, silica gel for flash
chromatography) was nitrogen saturated. The yields
refer to analytically pure compounds and were not
1
1887 sh. H-NMR (CDCl3, 238 K): l 7.45–7.08 (m,
4H, aryl), 4.81 (s, 1H, ꢀCH), 2.32 (s, 3H, CH3). 13C-
NMR (CDCl3, 238 K): l 224.0 (trans-CO), 214.8 (cis-
CO), 140.2, 130.9, 129.6, 119.7 (C6H4), 67.8 (CꢂTol),
57.3 (CꢂH), 21.5 (Me).
3.3. Reaction of (p2-alkyne)pentacarbonylmetal
complexes with N-phenyl imines
optimized. Instrumentation: H- and 13C-NMR spectra
1
were recorded with a Bruker AC 250 or a Bruker WM
1
250 spectrometer. H-NMR resonances of solutions in
At −30°C, a solution of N-phenyl p-methylbenzyli-
deneimine, N-phenyl benzylideneimine, and N-phenyl
p-chlorbenzylideneimine {(Ph)NꢁC(H)R, R=p-Tol,
Ph, p-chlorphenyl; two equivalents each relative to
[M(CO)6]}, respectively, in 3–4 ml of CH2Cl2 was
added to a freshly prepared and highly concentrated
solution of the acetylene complexes 1–3, 7 and 8,
respectively. The solution was stirred for 90 min and
gradually warmed to r.t. The solvent was removed in
vacuo to give a brown oil. The oil was chro-
matographed at −30°C on neutral Al2O3. First, with
5:1 pentane–dichloromethane a yellow band was eluted
that contained the 2-azetidin-1-ylidene complexes (4a–
6a, 9a–17a) as a mixture of the syn and anti isomers.
Then, with 10:13.5 pentane–dichloromethane a second
yellow fraction was eluted, which afforded the
amino(ethenyl)carbene complexes (4b–6b, 9b–17b) af-
ter removal of the solvent in vacuo.
CDCl3 are reported relative to TMS, those of solutions
in acetone-d6 and the 13C-NMR-resonances relative to
the residual solvent peaks of acetone-d6 and CDCl3. If
not specifically mentioned, IR and NMR spectra are
taken at room temperature (r.t.). IR: Biorad FTS 60
spectrophotometer; MS: Finnigan MAT 312 (EI, 70 eV
or FAB, NBOH [3-nitrobenzyl alcohol]). The peaks of
the tungsten complexes are listed with respect to 184W.
Elemental analyses: Heraeus CHN-O-RAPID. Photoly-
sis reactions were carried out in a duran glass apparatus
by using a mercury high pressure lamp (TQ 150, Fa.
Heraeus). The imines [20] and p-bromophenylacetylene
[21] were prepared according to literature procedures.
3.2. Generation of (p2-alkyne)metal complexes 1–3, 7,
8
The (h2-alkyne)metal complexes 1 and 3 were gener-
ated as described in Ref. [8]; the complexes 2, 7, and 8
were analogously generated. These (h2-acetylene)-
pentacarbonyl complexes were unstable and quickly
decomposed at temperatures above −20 (M=Cr) or
0°C (M=W). Therefore, the highly concentrated solu-
tions containing the (h2-alkyne)pentacarbonyl com-
plexes obtained by these procedures were used
immediately for the reactions with imines.
3.3.1. Pentacarbonyl{(2,3,4-triphenyl)-2-azetidin-1-
ylidene}tungsten (4a) and pentacarbonyl[1,2-
diphenylethenyl(phenylamino)carbene]tungsten (4b)
Compound 4a. Yield: 0.30 g (18% relative to
[W(CO)6]). Two isomers: 84% syn, 16% anti. M.p.
113°C. IR (CH2Cl2) w(CO) (cm−1): 2063 m, 1929 vs.
1H-NMR (CDCl3) syn isomer: l 7.73–6.85 (m, 15H, 3
aryl), 6.56 (d, J=4.7 Hz, 1H, 3-CH), 4.60 (d, J=4.7
1
Hz, 1H, 4-CH). H-NMR (CDCl3) anti isomer: l 5.83
3.2.1. Pentacarbonyl(p2-p-tolylacetylene)tungsten (2)
IR (CH2Cl2, 243 K) w(CO) (cm−1): 2085 m, 1956 vs,
(d, J=1.7 Hz, 1H, 3-CH), 4.01 (d, J=1.7 Hz 1H,
4-CH). 13C-NMR (CDCl3): l 271.2 (C1), 202.8 (trans-
CO), 197.4 (cis-CO), 140.2, 130.1, 129.7, 129.6, 129.3,
129.2, 129.1, 128.7, 127.9, 127.5, 126.6, 122.6 (3 aryl),
78.0 (C3), 66.5 (C4). MS m/z (%): 607 (15) [M+], 523
(27) [M+−3CO], 467 (19) [M+−5CO], 364 (100) [M+
−5CO−C−CPh(H)], 180 (23) [M+−W(CO)5−
CꢂCPh(H)]. Anal. Found: C, 50.91; H, 3.15; N, 2.72.
C26H17NO5W (607.3). Calc.: C, 51.38; H, 2.80; N,
2.31%.
1
1933 sh. H-NMR (CDCl3, 238 K): l 7.36 (d, J=8.7
Hz, 2H, aryl), 7.26 (d, J=8.7 Hz, 2H, aryl), 6.03 (s,
1H, ꢀCH), 2.42 (s, 3H, CH3). 13C-NMR (CDCl3, 238
K): l 203.7 (trans-CO), 196.1 (cis-CO), 139.7, 130.2,
129.6, 122.3 (aryl), 80.4 (ꢀCꢂTol), 63.8 (ꢀCH), 21.6
(Me).
3.2.2. (p2-p-Bromophenylacetylene)-
pentacarbonyltungsten (7)
Compound 4b. Yield: 0.78 g (45% relative to
IR (CH2Cl2, 243 K) w(CO) (cm−1): 2085 m, 1958 vs,
[W(CO)6]). M.p. 142°C. IR (CH2Cl2) w(CO) (cm−1):
1
1
1937 sh. H-NMR (CDCl3, 238 K): l 7.62–7.29 (m,
2063 m, 1929 vs. H-NMR (CDCl3): l 10.25 (s, br, 1H,
4H, aryl), 6.39 (s, 1H, ꢀCH). 13C-NMR (CDCl3, 238
NH), 7.68–6.90 (m, 15H, 3 aryl), 6.72, 6.34 (2 s,

M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
293
together 1H, CH). 13C-NMR (CDCl3): l 262.5 (C1),
203.5 (trans-CO), 197.8 (cis-CO), 155.6 (C2), 142.2,
136.0, 135.0, 130.0, 129.8, 129.6, 129.3, 128.9, 128.6,
128.3, 128.0, 127.4, 126.9, 125.3 (3 aryl+C3). MS m/z
(%): 607 (2) [M+], 523 (10) [M+−3CO], 467 (19)
[M+−5CO], 282 (15) [M+−W(CO)5], 182 (100) [M+
−W(CO)5−CꢂCPh(H)]. Anal. Found: C, 51.03; H,
2.90; N, 2.34. C26H17NO5W (607.3). Calc.: C, 51.38; H,
2.80; N, 2.31%.
(CDCl3): l 139.5, 134.1, 132.5, 129.7, 129.6, 129.2,
128.1, 127.9, 127.7, 127.4, 126.3, 123. (3 aryl), 77.9
(C3), 65.4 (C4); anti isomer: l 294.7 (C1), 222.8 (trans-
CO), 216.7 (cis-CO), 139.3, 135.2, 129.5, 129.2, 128.9,
128.6, 126.7, 124.6 (3 aryl), 84.2 (C3), 68.1 (C4). MS
m/z (%): 475 (7) [M+], 419 (4) [M+−2CO], 391 (6)
[M+−3CO], 363 (36) [M+−4CO], 335 (100) [M+−
5CO]. Anal. Found: C, 65.83; H, 3.88; N, 3.10.
C26H17CrNO5 (475.5). Calc.: C, 65.69; H, 3.60; N,
2.95%.
3.3.2. Pentacarbonyl[(2-phenyl-3,4-di-p-tolyl)-2-
Compound 6b: Yield 0.50
g (39% relative to
azetidin-1-ylidene]tungsten (5a) and pentacarbonyl-
[1,2-p-ditolylethenyl(phenylamino)carbene]tungsten (5b)
Compound 5a. Yield: 0.32 g (18% relative to
[W(CO)6]). Two isomers: ca. 90% syn, 10% anti. M.p.:
102°C. IR (CH2Cl2) w(CO) (cm−1): 2061 m, 1929 vs.
1H-NMR (CDCl3) syn isomer: l 7.70–6.77 (m, 13H, 3
aryl), 6.51 (d, J=4.6 Hz, 1H, 3-CH), 4.53 (d, J=4.6
[Cr(CO)6]). Two isomers: ratio ca. 8:2. M.p. 93°C. IR
(CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs. 1H-NMR
(CDCl3): l 10.47, 10.32 (2 s, together 1H, NH), 7.59–
7.09 (m, 17H, 3 aryl), 6.51, 6.32 (2 s, together 1H, CH).
13C-NMR (CDCl3): l 284.7 (C1), 223.7 (trans-CO),
216.6 (cis-CO), 155.6 (C2), 141.5, 135.4, 135.1, 129.9,
129.8, 129.7, 129.1, 128.8, 128.2, 127.8, 127.1, 123.4 (3
aryl+C3). MS m/z (%): 475 (2) [M+], 447 (0.5) [M+−
CO], 419 (1) [M+−2CO], 391 (2) [M+−3CO], 363
(12) [M+−4CO], 335 (43) [M+−5CO]. Correct ele-
mental analysis could not be obtained due to insepara-
ble impurities.
1
Hz, 1H, 4-CH), 2.21, 2.15 (2 s, 6H, 2 Me). H-NMR
(CDCl3) anti isomer: l 7.70–6.77 (m, 13H, 3 aryl), 5.74
(d, J=1.7 Hz, 1H, 3-CH), 3.94 (d, J=1.7 Hz, 1H,
4-CH), 2.38, 2.34 (2 s, 6H, 2 Me). 13C-NMR (CDCl3):
l 268.9 (C1), 202.9 (trans-CO), 197.5 (cis-CO), 143.4,
140.1, 137.1, 131.1, 129.9, 129.8, 129.6, 129.1, 129.0,
128.8, 126.7, 122.8, (3 aryl), 78.3 (C3), 66.4 (C4), 21.2,
21.1 (2 Me). MS m/z (%): 635 (8) [M+], 551 (21)
[M+−3CO], 495 (18) [M+−5CO], 392 (100) [M+−
5CO−C−tolyl]. Anal. Found: C, 52.81; H, 3.59; N,
2.36. C28H21NO5W (635.3). Calc.: C, 52.93; H, 3.33; N,
2.20%.
3.3.4. Pentacarbonyl[(2,4-diphenyl-3-p-tolyl)-2-azetidin-
1-ylidene]tungsten (9a) and pentacarbonyl[1-phenyl-
2-p-tolylethenyl(phenylamino)carbene]tungsten (9b)
Compound 9a. Yield 0.14
g (8% relative to
[W(CO)6]). Two isomers: ca. 90% syn, 10% anti. M.p.
113°C. IR (CH2Cl2, 298 K) w(CO) (cm−1): 2062 m,
Compound 5b. Yield 0.78
g (43% relative to
1
1929 vs. H-NMR (CDCl3) syn isomer: l 7.72–6.78 (m,
[W(CO)6]). Two isomers: ratio ca. 9:1. M.p. 106°C. IR
(CH2Cl2) w(CO) (cm−1): 2061 m, 1929 vs. 1H-NMR
(CDCl3): l 10.04, 10.22 (2 s, together 1H, NH), 7.52–
6.87 (m, 13H, 3 aryl), 6.75, 6.24 (2 s, together 1H,
ꢁCH), 2.39, 2.35, 2.27, 2.24 (4 s, together 6H, 2 Me).
13C-NMR (CDCl3): l 261.8 (C1), 203.6 (trans-CO),
197.9 (JW,C=127.0 Hz, cis-CO), 154.5 (C2), 142.3,
138.7, 138.1, 137.3, 133.1, 132.2, 130.0, 129.7, 129.4,
128.9, 128.8, 126.8, 124.1 (3 aryl+C3), 21.3, 21.2 (2
Me). MS m/z (%): 635 (5) [M+], 551 (44) [M+−3CO],
495 (58) [M+−5CO], 310 (100) [M+−W(CO)5], 194
(75) [M+−W(CO)5−CꢁC(tolyl)H]. Anal. Found: C,
53.17; H, 3.59; N, 2.36. C28H21NO5W (635.3). Calc.: C,
52.93; H, 3.33; N, 2.20%.
14H, 3 aryl), 6.52 (d, J=4.7 Hz, 1H, 3-CH), 4.58 (d,
J=4.7 Hz, 1H, 4-CH), 2.13 (s, 3H, Me) anti isomer: l
7.72–6.78 (m, 14H, 3 aryl), 5.80 (d, J=1.6 Hz, 1H,
3-CH), 4.00 (d, J=1.6 Hz, 1H, 4-CH), 2.34 (s, 3H,
Me). 13C-NMR (CDCl3): l 270.8 (C1), 202.8 (trans-
CO), 197.4 (cis-CO), 140.1, 137.7, 134.3, 130.1, 129.7,
129.6, 129.0, 128.9, 128.1, 127.5, 126.6, 122.7 (3 aryl),
78.1 (C3), 66.5 (C4), 21.0 (Me). MS m/z (%): 621 (11)
[M+], 537 (23) [M+−3CO], 481 (21) [M+−5CO], 378
(100) [M+−5CO-C(tolyl)2H], 194 (33) [M+−
W(CO)5-C(tolyl)2H]. Anal. Found: C, 51.90; H, 3.26;
N, 2.40. C27H19NO5W (621.30). Calc.: C, 52.20; H,
3.08; N, 2.25%.
Compound 9b: Yield 1.09
g (62% relative to
[W(CO)6]). Two isomers: ratio ca. 7:3. M.p. 123°C. IR
(CH2Cl2) w(CO) (cm−1): 2062 m, 1929 vs. 1H-NMR
(CDCl3): l 10.18, 10.11 (2 s, together 1H, NH), 7.55–
7.00 (m, 14H, 3 aryl), 6.75, 6.33 (2 s, 1 H, CH), 2.29,
2.25 (3s, together 3 H, Me). 13C-NMR (CDCl3): l 260.2
(C1), 202.7 (trans-CO), 196.6 (cis-CO), 153.4 (C2),
141.0, 137.2, 135.1, 130.7, 128.9, 128.7, 128.5, 128.2,
127.9, 127.7, 126.7, 125.9 (3 aryl+C3), 20.3 (Me). MS
m/z (%): 621 (6) [M+], 537 (53) [M+−3CO], 481 (72)
[M+−5CO], 296 (33) [M+−W(CO)5]. Anal. Found:
3.3.3. Pentacarbonyl[(2,3,4-triphenyl)-2-azetidin-1-
ylidene]chromium (6a) and pentacarbonyl[1,2-
diphenylethenyl(phenylamino)carbene]chromium (6b)
Compound 6a. Yield 0.08
g (6% relative to
[Cr(CO)6]). Two isomers: 80% syn, 20% anti. M.p.
81°C. IR (CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs.
1H-NMR (CDCl3) syn isomer: l 6.64 (d, J=4.7 Hz,
1H, 3-CH), 4.67 (d, J=4.7 Hz, 1H, 4-CH) anti isomer:
l 7.70–6.87 (m, 15H, 3 aryl), 5.78 (d, J=1.7 Hz, 1H,
3-CH), 4.10 (d, J=1.7 Hz, 1H, 4-CH). 13C-NMR

294
M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
C, 52.39; H, 3.11; N, 2.16. C27H19NO5W (621.30).
Calc.: C, 52.20; H, 3.08; N, 2.25%.
(CH2Cl2) w(CO) (cm−1): 2063 m, 1929 vs. 1H-NMR
(CDCl3): l 10.13 (s, br, 1H, NH), 7.47−6.96 (m, 14H,
3 aryl), 6.79, 6.33 (2 s, together 1H, CH), 2.37, 2.26 (2
s, together 3H, Me). 13C-NMR (CDCl3): l 262.7 (C1),
203.5 (trans-CO), 197.8 (cis-CO), 155.5 (C2), 142.3,
138.9, 135.2, 132.9, 130.0, 129.8, 129.7, 129.6, 128.2,
128.0, 126.9 (3 aryl+C3), 21.4 (Me). MS m/z (%): 621
(7) [M+], 537 (19) [M+−3CO], 481 (36) [M+−5CO],
297 (68) [M+−W(CO)5], 205 (100) [M+−W(CO)5−
NPh(H)]. Anal. Found: C, 52.16; H, 3.17; N, 2.32.
C27H19O5NW (621.3). Calc.: C, 52.20; H, 3.08; N,
2.25%.
3.3.5. Pentacarbonyl[(3-p-chlorophenyl-2,4-diphenyl)-
2-azetidin-1-ylidene]tungsten (10a) and pentacarbonyl-
[2-p-chlorophenyl-1-phenylethenyl(phenylamino)-
carbene]tungsten (10b)
Compound 10a. Yield 0.31 g (17% relative to
[W(CO)6]). Two isomers: 80% syn, 20% anti. M.p.
108°C. IR (CH2Cl2) w(CO) (cm−1): 2063 m, 1929 vs.
1H-NMR (CDCl3) syn isomer: l 7.90–6.73 (m, 14H, 3
arom.), 6.52 (d, J=4.8 Hz, 1H, 3-CH), 4.60 (d, J=4.8
1
Hz, 1H, 4-CH). H-NMR (CDCl3) anti isomer: l 5.80
(d, J=1.4 Hz, 1H, 3-CH), 3.95 (d, J=1.6 Hz, 1H,
4-CH). 13C-NMR (CDCl3): l 271.2 (C1), 202.8 (trans-
CO), 197.4 (cis-CO), 140.1, 134.2, 132.9, 130.1, 129.7,
129.6, 129.2, 129.1, 128.3, 128.1, 122.7 (3 aryl), 78.0
(C3), 66.5 (C4). MS m/z (%): 641 (11) [M+], 557 (17)
[M+−3CO], 501 (12) [M+−5CO], 398 (92) [M+−
5CO−2C−2H−Ph], 306 (100) [M+−5CO−2C−
2H−Ph−NPh]. Anal. Found: C, 48.68; H, 2.67; N,
2.60. C26H16ClNO5W (641.0). Calc.: C, 48.66; H, 2.51;
N, 2.18%.
Compound 10b. Yield 0.97 g (53% relative to
[W(CO)6]; three isomers: 70, 20, 10%). M.p. 128°C. IR
(CH2Cl2) w(CO) (cm−1): 2063 m, 1929 vs. 1H-NMR
(CDCl3): 10.19, 10.34, 10.42 (3 s, together 1H, NH),
7.58–6.89 (m, 14 H, 3 aryl), 6.67, 6.30, 6.23 (3 s,
together 1H, ꢁCH). 13C-NMR (CDCl3): l 262.5 (C1),
203.4 (trans-CO), 197.7 (cis-CO), 156.1 (C2), 142.1,
135.6, 133.8, 133.5, 131.2, 129.8, 129.7, 129.4, 129.1,
128.5, 126.9, 125.9 (3 aryl+C3). MS m/z (%): 641 (7)
[M+], 557 (40) [M+−3CO], 501 (43) [M+−5CO], 316
(100) [M+−W(CO)5]. Anal. Found: C, 49.11; H, 2.64;
N, 2.32. C26H16ClNO5W (641.0). Calc.: C, 48.66; H,
2.51; N, 2.18%.
3.3.7. Pentacarbonyl[(3-p-chlorophenyl-2-phenyl-4-
p-tolyl)-2-azetidin-1-ylidene]tungsten (12a) and
pentacarbonyl[2-p-chlorophenyl-1-p-tolylethenyl-
(phenylamino)carbene]tungsten (12b)
Compound 12a. Yield 0.30 g (16% relative to
[W(CO)6]). Two isomers: 94% syn, 6% anti. M.p. 108°C.
1
IR (CH2Cl2) w(CO) (cm−1): 2063 m, 1929 vs. H-NMR
(CDCl3) syn isomer: l 7.68–6.81 (m, 13H, 3 aryl), 6.48
(d, J=4.6 Hz, 1H, 3-CH), 4.56 (d, J=4.7 Hz, 1H,
4-CCH), 2.21 (s, 3H, Me); anti isomer: l 5.77 (d,
J=1.6 Hz, 1H, 3-CH), 3.92 (d, J=1.6 Hz, 1H, 4-CH),
2.31 (s, 3H, Me). 13C-NMR (CDCl3): l 271.1 (C1),
201.8 (trans-CO), 196.3 (cis-CO), 138.9, 136.4, 132.8,
130.6, 129.8, 128.8, 128.7, 128.0, 127.5, 121.6 (3 aryl),
76.4 (C3), 65.2 (C4), 20.1 (Me). MS m/z (%): 655 (17)
[M+], 571 (27) [M+−3CO], 515 (15) [M+−5CO], 412
(100) [M+−5CO−N(Ph)C]. Anal. Found: C, 49.43;
H, 2.98; N 2.13. C27H18ClNO5W (655.7). Calc.: C,
49.41, H, 2.77; N, 2.14%.
Compound 12b. Yield: 1.14 g (61% relative to
[W(CO)6]). Two isomers: ratio ca. 9:1. M.p.: 127°C. IR
(CH2Cl2, 298 K) w(CO) (cm−1): 2063 m, 1929 vs.
1H-NMR (CDCl3): l 10.19 (s, br, 1H, NH), 7.65–7.02
(m, 13H, aryl), 6.69 (s, 1H, ꢁCH), 2.39, 2.36 (2s,
together 3H, Me). 13C-NMR (CDCl3): l 260.5 (C1),
202.8 (trans-CO), 196.5 (JW,C=128.3 Hz, cis-CO),
154.7 (C2), 140.9, 138.0, 132.4, 131.3, 130.1, 128.9,
128.7, 128.6, 128.3, 127.3, 125.7, 123.7 (3 aryl+C3),
20.4 (Me). MS m/z (%): 655 (11) [M+], 571 (100)
[M+−3CO], 515 (64) [M+−5CO], 412 (63) [M+−
5CO−N(Ph)C]. Anal. Found: C, 49.43; H, 2.98; N
2.13. C27H18ClNO5W (655.7). Calc.: C, 49.41; H, 2.77;
N, 2.14%.
3.3.6. Pentacarbonyl[(2,3-diphenyl-4-p-tolyl)-2-azetidin-
1-ylidene]tungsten (11a) and pentacarbonyl[2-phenyl-
1-p-tolylethenyl(phenylamino)carbene]tungsten (11b)
Compound 11a. Yield: 0.32 g (18% relative to
[W(CO)6]), syn/anti ratio \97:3. M.p. 113°C. IR
(CH2Cl2, 298 K) w(CO) (cm−1): 2063 m, 1929 vs.
1H-NMR (CDCl3): l 7.76–6.90 (m, 14H, 3 aryl), 6.61
(d, J=4.7 Hz, 1H, 3-CH), 4.58 (d, J=4.7 Hz, 1H,
4-CH), 2.13 (s, 3H, Me). 13C-NMR (CDCl3): l 270.1
(C1), 203.9 (trans-CO), 198.1 (cis-CO), 141.2, 137.5,
134.2, 132.6, 131.1, 130.5, 130.2, 129.5, 129.0, 128.6,
128.0, 124.4 (3 aryl), 80.0 (C3), 66.9 (C4), 21.1 (Me).
MS m/z (%): 621 (17) [M+], 537 (78) [M+−3CO], 481
(100) [M+−5CO], 296 (75) [M+−W(CO)5−H].
Anal. Found: C, 52.05; H, 3.19; N, 2.48. C27H19NO5W
(621.3). Calc.: C, 52.20; H, 3.08; N, 2.25%.
3.3.8. [(4-p-Bromophenyl-2,3-diphenyl)-2-azetidin-1-
ylidene]pentacarbonyltungsten (13a) and [1-p-bromo-
phenyl-2-phenylethenyl(phenylamino)carbene]-
pentacarbonyltungsten (13b)
Compound 13a. Yield: 0.38 g (20% relative to
[W(CO)6]). Two isomers: 90% syn, 10% anti. M.p.
113°C. IR (CH2Cl2) w(CO) (cm−1): 2064 m, 1931 vs.
1H-NMR (CDCl3) syn isomer: l 7.72–6.85 (m, 14 H, 3
Compound 11b. Yield: 0.84 g (48% relative to
[W(CO)6]). Two isomers ratio ca. 7:3. M.p. 123°C. IR

M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
295
(CH2Cl2, 298 K) w(CO) (cm−1): 2062 m, 1929 vs.
1H-NMR (CDCl3): l 10.16, 10.24 (2 s, together 1H,
NH), 7.58–6.97 (m, 13 H, 3 aryl), 6.67, 6.29 (2 s, 1H,
CH), 2.38, 2.25 (2 s, together 3H, Me). 13C-NMR
(CDCl3): l 262.3 (C1), 203.3 (trans-CO), 197.7 (cis-
CO), 154.0 (C2), 142.1, 138.5, 135.2, 132.4, 132.0,
131.7, 131.5, 131.1, 129.9, 129.8, 129.2, 126.9, 123.0 (3
aryl+C3), 21.3 (Me). MS m/z (%): 701 (8) [M+], 617
(73) [M+−3CO], 559 (87) [M+−5CO], 377 (100) [M+
−W(CO)5]. Anal. Found: C, 46.32; H, 2.87; N, 2.12.
C27H18BrNO5W (700.2). Calc.: C, 46.32; H, 2.59; N,
2.00%.
aryl), 6.56 (d, J=4.7 Hz, 1H, 3-CH), 4.56 (d, J=4.7
Hz, 1H, 4-CH). H-NMR (CDCl3) anti isomer: l 5.76
1
(d, J=1.6 Hz, 1H, 3-CH), 3.97 (d, J=1.6 Hz, 1H,
4-CH). 13C-NMR (CDCl3): l 269.1 (C1), 203.0 (trans-
CO), 196.3 (cis-CO), 138.9, 132.3, 131.6, 131.2, 130.6,
130.3, 128.7, 128.6, 128.3, 127.5, 125.4, 121.6 ( 3 aryl),
82.5 (C3, syn), 76.8 (C3, anti ), 67.6 (C4, anti ), 64.7
(C4, syn). MS m/z (%): 685 (10) [M+], 603 (14) [M+−
3CO], 545 (10) [M+−5CO]. Anal. Found: C, 45.57; H,
2.84; N, 1.94. C26H16BrNO5W (686.2). Calc.: C, 45.51;
H, 2.35; N, 2.04.
Compound 13b. Yield: 0.87 g (45% relative to
[W(CO)6]). Two isomers: ratio ca. 8:2. M.p. 131°C. IR
(CH2Cl2) w(CO) (cm−1): 2063 m, 1930 vs. 1H-NMR
(CDCl3): l 10.35, 10.23 (s, br, 1H, NH), 7.59–7.07 (m,
14H, 3 aryl), 6.34, 6.70 (2s, together 1H, CH). 13C-
NMR (CDCl3): l 262.5 (C1), 203.3 (trans-CO), 197.6
(JW,C=106 Hz, cis-CO), 154.8 (C2), 142.0, 134.9,
134.6, 132.4, 132.0, 131.4, 130.0, 129.9, 129.7, 128.7,
126.8 (3 aryl+C3). MS m/z (%): 687 (0.6) [M+], 601
(4) [M+−3CO], 545 (4) [M+−5CO], 360 (100) [M+
−W(CO)5]. Anal. Found: C, 45.78; H, 2.58; N, 2.33.
C26H16BrNO5W (686.2). Calc.: C, 45.51; H, 2.35; N,
2.04%.
3.3.10. Pentacarbonyl[(2,4-diphenyl-3-p-tolyl)-2-
azetidin-1-ylidene]chromium (15a) and
pentacarbonyl[1-phenyl-2-tolylethenyl(phenylamino)-
carbene]chromium (15b)
Compound 15a. Yield 0.07
g (5% relative to
[Cr(CO)6]). Two isomers: 90% syn, 10% anti. M.p.
80°C. IR (CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs.
1H-NMR (CDCl3) syn isomer: l 7.67–6.76 (m, 14H, 3
aryl), 6.59 (d, J=4.3 Hz, 1H, 3-CH), 4.65 (d, J=4.5
Hz, 1H, 4-CH), 2.13 (s, 3H, Me). anti isomer: l 5.81 (d,
J=1.6 Hz, 1H, 3-CH), 3.96 (d, J=1.6 Hz, 1H, 4-CH).
13C-NMR (CDCl3): l 294.8 (C1), 223.0 (trans-CO),
217.2 (cis-CO), 140.0, 138.0, 134.7, 130.3, 130.1, 129.8,
129.7, 129.3, 128.5, 127.9, 126.9, 123.6 (3 aryl), 78.5
(C3), 66.0 (C4), 21.6 (Me). MS m/z (%): 489 (5) [M+],
433 (3) [M+−2CO], 405 (4) [M+−3CO], 377 (4)
[M+−4CO], 349 (77) [M+−5CO]. Anal. Found: C,
66.29; H, 4.45; N, 2.89. C27H19CrNO5·0.14 pentane
(489.5+10.1). Calc.: C, 66.54; H, 4.14; N, 2.80%.
Compound 15b. Yield 0.57 g (43% relative to
[Cr(CO)6]). Two isomers: ratio ca. 8:2. M.p. 104°C. IR
(CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs. 1H-NMR
(CDCl3): l 10.38, 10.51 (2 s, together 1H, NH), 7.68–
6.92 (m, 14H, 3 aryl), 6.50, 6.25 (2 s, together 1H, CH),
2.31, 2.27 (2 s, together 3H, Me). 13C-NMR (CDCl3): l
284.3 (C1), 223.7 (trans-CO), 216.7 (cis-CO), 154.9,
160.4 (2 C2), 141.6, 137.9, 137.4, 135.7, 132.4, 132.2,
129.9, 129.8, 129.7, 129.6, 129.5, 129.2, 129.1, 129.0,
128.9, 128.8, 128.7, 128.3, 128.2, 127.9, 127.1, 124.8,
124.8, 124.3, 124.1, 120.9 (6 aryl+C3), 21.2, 21.6 (2
Me). MS m/z (%): 489 (2) [M+], 461 (3) [M+−CO],
433 (3) [M+−2CO], 405 (12) [M+−3CO], 349 (100)
[M+−5CO]. Anal. Found: C, 65.61; H, 4.01; N, 2.96.
C27H19CrNO5 (489.5). Calc.: C, 66.26; H, 3.91; N,
2.86%.
3.3.9. [(4-p-Bromophenyl-2-phenyl-3-p-tolyl)-2-
azetidin-1-ylidene]pentacarbonyltungsten (14a) and
[1-p-bromophenyl-2-tolylethenyl(phenylamino)carbene]-
pentacarbonyltungsten (14b)
Compound 14a. Yield 0.16
g (8% relative to
[W(CO)6]). Two isomers: 75% syn, 25% anti. M.p.
113°C. IR (CH2Cl2) w(CO) (cm−1): 2062 m, 1929 vs.
1H-NMR (CDCl3) syn isomer: l 7.69–6.75 (m, 13H, 3
aryl), 6.51 (d, J=4.6 Hz, 1H, 3-CH), 4.53 (d, J=4.7
1
Hz, 1H, 4-CH), 2.17 (s, 3H, Me). H-NMR (CDCl3)
anti isomer: l 5.71 (d, J=1.6 Hz, 1H, 3-CH), 3.95 (d,
J=1.6 Hz, 1H, 4-CH), 2.34 (s, 3H, Me). 13C-NMR
(CDCl3) syn isomer: l 268.5 (C1), 202.9 (trans-CO),
197.2 (cis-CO), 139.6, 139.2, 134.6, 132.0, 130.7, 130.3,
130.0, 129.5, 129.4, 126.5, 123.3, 122.1 (3 aryl), 82.7
(C3), 68.4 (C4), 21.3 (Me); anti isomer: l 5.71 (d,
J=1.6 Hz, 1H, 3-CH), 3.95 (d, J=1.6 Hz, 1H, 4-CH),
2.34 (s, 3H, Me). 13C-NMR (CDCl3) syn isomer: l
269.5 (C1), 203.2 (trans-CO), 197.7 (cis-CO), 139.9,
138.4, 133.7, 132.0, 131.7, 130.1, 129.7, 129.6, 129.5,
126.8, 122.8, 122.1 (3 aryl), 77.7 (C3), 65.8 (C4), 21.2
(Me). MS m/z (%): 701 (13) [M+], 617 (28) [M+−
3CO], 559 (22) [M+−5CO], 456 (83) [M+−5CO−
C−N(Ph)], 272 (28) [M+−W(CO)5−C−N(Ph)].
Anal. Found: C, 45.95; H, 2.91; N, 2.28.
C27H18BrNO5W (700.2). Calc.: C, 46.32; H, 2.59; N,
2.00%.
3.3.11. Pentacarbonyl[(2,3-diphenyl-4-p-tolyl)-2-
azetidin-1-ylidene]chromium (16a) and
pentacarbonyl[(2-phenyl-1-tolylethenyl(phenylamino)-
carbene]chromium (16b)
Compound 14b. Yield 0.89 g (45% relative to
[W(CO)6]). Two isomers: ratio ca. 9:1. M.p. 132°C. IR
Compound 16a. Yield 0.07
[Cr(CO)6]). Two isomers: 80% syn, 20% anti. M.p.
g (5% relative to

296
M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
79°C. IR (CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs.
1H-NMR (CDCl3) syn isomer: l 7.68–6.87 (m, 14H, 3
aryl), 6.60 (d, J=4.5 Hz, 1H, 3-CH), 4.62 (d, J=4.5
Hz, 1H, 4-CH), 2.17 (s, 3H, Me); anti isomer: l 7.68–
6.87 (m, 14H, 3 aryl), 5.71 (d, J=1.6 Hz, 1H, 3-CH),
4.07 (d, J=1.7 Hz, 1H, 4-CH), 2.37 (s, 3H, Me).
13C-NMR (CDCl3): l 296.0 (C1), 222.8 (trans-CO),
216.9 (cis-CO), 140.0, 137.1, 133.0, 131.1, 129.8, 129.7,
129.5, 129.2, 128.7, 128.2, 126.5, 123.4, (3 aryl), 84.7
(C3, anti ), 78.5 (C3, syn), 68.1 (C4, anti ), 65.8 (C4,
syn), 21.2 (Me, anti ), 21.1(Me, syn). MS m/z (%): 489
(6) [M+], 405 (5) [M+−3CO], 378 (22) [M+−4CO];
349 (86) [M+−5CO], 296 (7) [M+−Cr(CO)5-H].
Anal. Found: C, 66.09; H, 4.02; N, 3.03.
C27H19CrNO5 (489.45). Calc.: C, 66.26; H, 3.91; N,
2.86%.
6.77 (m, 13 H, 3 aryl), 6.30, 6.10 (2 s, together 1H,
CH), 2.36, 2.26 (2 s, together 3H, Me). 13C-NMR
(CDCl3): l 287.4, 282.5 (2 C1), 223.8, 223.1 (2 trans-
CO), 216.8, 216.4 (2 cis-CO), 155.6, 149.7 (2 C2),
141.3, 139.4, 138.8, 138.2, 133.9, 133.5, 132.9, 132.6,
131.5, 130.9. 130.3, 129.7, 129.6, 129.5, 129.2, 129.0,
128.2, 126.9, 123.9, 121.5, 119.9 (6 aryl+2 C3), 21.3,
21.2 (2 Me). MS m/z (%): 523 (0.4) [M+], 495 (2)
[M+−CO], 467 (0.5) [M+−2CO], 439 (9) [M+−
3CO], 383 (63) [M+−5CO], 330 (41) [M+−
Cr(CO)5−H]. Anal. Found: C, 61.98; H, 3.77; N,
3.07. C27H18ClCrNO5 (523.9). Calc.: C, 61.90; H, 3.46;
N, 2.67%.
3.4. X-ray structural analysis of 11b
Compound 16b. Yield 0.62 g (46% relative to
[Cr(CO)6]). Two isomers: ratio ca. 7:3. M.p. 105°C. IR
(CH2Cl2) w(CO) (cm−1): 2055 m, 1933 vs. 1H-NMR
(CDCl3): l 10.34, 10.64 (2 s, together 1H, NH), 7.55–
7.03 (m, 14H, 3 aryl), 6.47, 6.18 (2 s, together 1H,
CH), 2.36, 2.27 (2 s, together 3H, Me). 13C-NMR
(CDCl3): l 284.6 (C1), 223.8 (trans-CO), 216.7 (cis-
CO), 155.6 (C2), 141.6, 138.8, 138.0, 135.3, 132.3,
129.9, 129.7, 129.6, 129.2, 128.2, 127.1, 123.4 (3 aryl+
C3), 21.3 (Me). MS m/z (%): 489 (2) [M+], 461 (3)
[M+−CO], 433 (1) [M+−2CO], 405 (15) [M+−
3CO], 349 (100) [M+−5CO], 296 (50) [M+−
Cr(CO)5−H]. Anal. Found: C, 66.54; H, 4.05; N 2.92.
C27H19CrNO5 (489.5). Calc.: C, 66.26; H, 3.91; N,
2.86%.
C27H19NO5W, molecular mass (621.30), crystal size
0.2×0.2×0.2 mm3 (obtained by recrystallization from
3:1 pentane–dichloromethane at −30°C); crystal sys-
(
tem triclinic, space group P1, a=8.785(3), b=
,
12.254(7),
c=12.798(5)
A,
h=102.15(4),
3
,
i=105.42(3), k=95.97(4)°; V=1279.6(10) A , Z=2,
D
calc=1.723 g cm−1, u (MoꢂKa)=0.71073 A, F(000)
,
646; Wyckoff scan, 2q range 4.0–54.0°, scan rate vari-
able 2.0–29.3° min−1 in ꢀ; 5589 independent reflec-
tions, 4680 reflections with F\4|(F); 319 refined
parameters; R=0.033, Rw=0.035. Largest difference
peak and hole: +0.77 and −1.13 e A−3). The mea-
,
surements were performed at −26°C, with a crystal of
11b mounted in a glass capillary on a Siemens R3m/V
diffractometer (graphite monochromator, MoꢂKa radi-
,
3.3.12. Pentacarbonyl[(3-p-chlorophenyl-2-phenyl-4-p-
tolyl)-2-azetidin-1-ylidene]chromium (17a) and
pentacarbonyl[2-p-chlorophenyl-1-tolylethenyl(phenylami
no)carbene]chromium (17b)
ation, u=0.71073 A). A semi-empirical absorption
correction (based on ten reflections) was carried out.
The structure was solved by Patterson methods using
the SHELXTL-PLUS (VMS) program package. The posi-
tions of the hydrogen atoms were calculated by assum-
Compound 17a. Yield 0.08
g (6% relative to
,
[Cr(CO)6]). Two isomers syn/anti\9:1. M.p. 73°C. IR
(CH2Cl2) w(CO) (cm−1): 2055 m, 1934 vs. 1H-NMR
(acetone-d6): syn isomer: l 8.00–7.02 (m, 14H, 3
aryl+3-CH), 4.91 (d, J=4.5 Hz, 1H, 4-CH), 2.18 (s,
3H, Me); anti isomer: l 8.00–7.02 (m, 14H, 3 aryl+3-
CH), 5.70 (d, J=1.5 Hz, 3-CH), 0 4.05 (d, J=1.5 Hz,
1H, 4-CH), 2.22 (s, 3H, Me);. 13C-NMR (acetone-d6):
l 293.8 (C1), 223.9 (trans-CO), 217.6 (cis-CO), 133.7,
133.1, 132.4, 130.9, 130.6, 130.4, 130.0, 129.8, 129.6,
129.1, 125.0, 117.7 (3 aryl), 79.5 (C3), 66.4 (C4), 21.2
(Me). MS m/z (%): 523 (5) [M+], 495 (1) [M+−CO],
467 (2) [M+−2CO], 439 (4) [M+−3CO], 411 (33)
[M+−4CO], 383 (100) [M+−5CO]. Correct elemen-
tal analysis could not be obtained due to inseparable
impurities.
ing ideal geometry (dCꢂH=0.96 A), and their
coordinates were refined together with those of the
attached C atoms as ‘riding models’. The positions of
all other atoms were refined anisotropically by the
full-matrix least-squares method.
4. Supplementary material
Crystallographic data for the structural analysis of
[(CO)5WꢁC(NPhH)C(C6H4Me-p)ꢁC(Ph)H]·1/2CH2Cl2
(11b) have been deposited with the Cambridge Crystal-
lographic Data Centre as supplementary publication
no. CCDC 136352. Copies of this information may be
obtained free of charge from: The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (Fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Compound 17b. Yield 0.56 g (39% relative to
[Cr(CO)6]). Two isomers syn/anti ratio ca. 7:3. IR
(CH2Cl2) w(CO) (cm−1): 2055 m, 1934 vs. 1H-NMR
(CDCl3): l 10.69, 10.56 (2 s, together 1H, NH), 7.51–

M.M. Abd-Elzaher et al. / Journal of Organometallic Chemistry 599 (2000) 288–297
297
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Support of these investigations by the Deutscher
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the Volkswagen-Stiftung and the Fonds der Chemis-
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