Reaction studies on some functionalized alkyl transition metal compounds and the crystal structure of [Cp(CO)3W{(CH2)3NO2}]

Article abstract of DOI:10.1016/j.jorganchem.2006.07.003

The reactions of the halogenoalkyl compounds [Cp(CO)₃W{(CH₂)_nX}] (Cp = η⁵-C₅H₅; n = 3-5; X = Br, I) and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃Br}] with the nucleophiles Z = CN^- and N₃^- gave compounds of the type [Cp(CO)₃W{(CH₂)_nZ}] for the tungsten compounds, whilst cyclic carbene compounds were obtained from the reactions of the molybdenum compound. The reactions of [Cp(CO)₃W{(CH₂)_nBr}] (n = 3, 4) and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃Br}] with NO₃^- gave [Cp(CO)₃W{(CH₂)_nONO₂}] and [Cp(CO)₂(PPhMe₂)Mo{(CH₂)₃ONO₂}], respectively. The reaction of [Cp(CO)₃W{(CH₂)_nBr}] with AgNO₂ gave [Cp(CO)₃W{(CH₂)_nNO₂}]. In the solid state the complex [Cp(CO)₃W{(CH₂)₃NO₂}] crystallizes in a distorted square pyramidal geometry. In this molecule the nitropropyl chain deviates from the ideal, all-trans geometry as a result of short, non-hydrogen intermolecular N-O?O-N contacts. The reactions of the heterobimetallic compounds [Cp(CO)₃W{(CH₂)₃}ML_y] {ML_y = Mo(CO)₃Cp, Mo(CO)₃Cp^* and Mo(CO)₂(PMe₃)Cp; Cp^* = η⁵-C₅(CH₃)₅} with PPh₃ and CO were found to be totally metalloselective, with the ligand always attacking the metal site predicted by the reactions of the corresponding monometallic analogues above with nucleophiles. Thus the compounds [Cp(CO)₃W{(CH₂)₃}C(O)ML_z] {ML_z = Mo(CO)₂YCp, Mo(CO)₂YCp^* and Mo(CO)Y(PMe₃)Cp; Y = PPh₃ or CO} were obtained. Similarly, the reaction of [Cp(CO)₂Fe{(CH₂)₃}Mo(CO)₂(PMe₃)Cp] with CO gave only [Cp(CO)₂Fe{(CH₂)₃C(O)}Mo(CO)₂(PMe₃)Cp]. Hydrolysis of the bimetallic compound, [Cp(CO)₃W(CH₂)₃C(O)Mo(CO)(PPh₃)(PMe₃)Cp], gave the carboxypropyl compound [Cp(CO)₃W{(CH₂)₃COOH}]. Thermolysis of the compound [Cp(CO)₂Fe(CH₂)₃Mo(CO)₃(PMe₃)Cp] gave cyclopropane and propene, indicating that β-elimination and reductive processes had taken place.

Full text of DOI:10.1016/j.jorganchem.2006.07.003

Journal of Organometallic Chemistry 691 (2006) 4615–4625
www.elsevier.com/locate/jorganchem
Reaction studies on some functionalized alkyl transition
metal compounds and the crystal structure of [Cp(CO)3W{(CH2)3NO2}]
*
Evans O. Changamu, Holger B. Friedrich , Martin O. Onani, Melanie Rademeyer
School of Chemistry, University of KwaZulu-Natal, Howard College, King George V Avenue, Durban, KwaZulu-Natal 4041, South Africa
Received 29 May 2006; received in revised form 6 July 2006; accepted 6 July 2006
Available online 12 July 2006
Abstract
The reactions of the halogenoalkyl compounds [Cp(CO)3W{(CH2)nX}] (Cp = g5-C5H5; n = 3–5; X = Br, I) and [Cp(CO)2(PPhMe2)-
Mo{(CH2)3Br}] with the nucleophiles Z = CNꢀ and N3ꢀ gave compounds of the type [Cp(CO)3W{(CH2)nZ}] for the tungsten com-
pounds, whilst cyclic carbene compounds were obtained from the reactions of the molybdenum compound. The reactions of
[Cp(CO)3W{(CH2)nBr}] (n = 3, 4) and [Cp(CO)2(PPhMe2)Mo{(CH2)3Br}] with NOꢀ gave [Cp(CO)3W{(CH2)nONO2}] and [Cp(CO)2-
3
(PPhMe2)Mo{(CH2)3ONO2}], respectively. The reaction of [Cp(CO)3W{(CH2)nBr}] with AgNO2 gave [Cp(CO)3W{(CH2)nNO2}]. In
the solid state the complex [Cp(CO)3W{(CH2)3NO2}] crystallizes in a distorted square pyramidal geometry. In this molecule the nitro-
propyl chain deviates from the ideal, all-trans geometry as a result of short, non-hydrogen intermolecular N–Oꢁ ꢁ ꢁO–N contacts. The
reactions of the heterobimetallic compounds [Cp(CO)3W{(CH2)3}MLy] {MLy = Mo(CO)3Cp, Mo(CO)3Cp* and Mo(CO)2(PMe3)Cp;
Cp* = g5-C5(CH3)5} with PPh3 and CO were found to be totally metalloselective, with the ligand always attacking the metal site pre-
dicted by the reactions of the corresponding monometallic analogues above with nucleophiles. Thus the compounds [Cp(CO)3W-
{(CH2)3}C(O)MLz] {MLz = Mo(CO)2YCp, Mo(CO)2YCp* and Mo(CO)Y(PMe3)Cp; Y = PPh3 or CO} were obtained. Similarly, the
reaction of [Cp(CO)2Fe{(CH2)3}Mo(CO)2(PMe3)Cp] with CO gave only [Cp(CO)2Fe{(CH2)3C(O)}Mo(CO)2(PMe3)Cp]. Hydrolysis
of the bimetallic compound, [Cp(CO)3W(CH2)3C(O)Mo(CO)(PPh3)(PMe3)Cp], gave the carboxypropyl compound [Cp(CO)3W{(CH2)3-
COOH}]. Thermolysis of the compound [Cp(CO)2Fe(CH2)3Mo(CO)3(PMe3)Cp] gave cyclopropane and propene, indicating that b-elim-
ination and reductive processes had taken place.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Halogenoalkyl; Heterobimetallic; Tungsten; Molybdenum; Iron; Tertiary phosphines; Nitropropyl
1. Introduction
metal and its associated ligands, n P 1, X = halogen) are
known precursors of cyclic carbene complexes [1] as well
as homo- and heterodinuclear alkanediyl compounds
[1,7,8]. Heterobimetallic alkanediyl compounds are pro-
posed to be good precursors or models for catalytic inter-
mediates. It is believed that their study may lead to
improved understanding of processes such as the Fischer–
Tropsch, olefin polymerization, catalytic oxidation, hydro-
genation and hydroformylation reactions, as well as of CO
activation [9,10]. With the growing global supply of linear
paraffins and the limited supply of traditional industrial
feedstocks, the study of the activation of alkanes is also
gaining importance [11]. Information on the nature of the
chemical activities of heterodinuclear metal functionalized
When compared to halogenomethyl transition metal
compounds, longer-chain halogenoalkyl compounds have
been comparatively little studied [1]. Indeed, only those
of platinum [2], ruthenium [3], iron [4], tungsten [5,6] and
recently molybdenum [6] have been studied in any detail.
The application of some of these compounds in organic
synthesis has been described [1], but few reaction studies
on these compounds have been reported. Importantly,
compounds of the type [LyM{(CH2)nX}] (LyM = transition
*
Corresponding author. Tel.: +27 31 260 3197; fax: +27 31 260 3091.
E-mail address: friedric@ukzn.ac.za (H.B. Friedrich).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.07.003

4616
E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
paraffins is therefore of interest. Few of these complexes
are known and therefore few reaction studies have been
carried out on them.
functionalized propyl transition metal compounds, when
compared to longer alkyl chain compounds, has been pos-
tulated to be due to an interaction between the metal and
the functional group at the end of the propyl chain [4,6]
We have previously reported the synthesis of the halo-
genoalkyl compounds [Cp(CO)3W{(CH2)nX}] (Cp =
g5-C5H5; n = 3–6; X = Br, I) and [Cp(CO)2(PPhMe2)-
Mo{(CH2)nX}] (n = 3,4) [6], and the heterobimetallic
alkanediyl compounds [Cp(CO)3W{(CH2)3}MLy] {MLy =
Mo(CO)3Cp, Mo(CO)3Cp* (Cp* = g5-C5(CH3)5), Mo-
(CO)2(PMe3)Cp} [8] and [Cp(CO)2Fe(CH2)3Ru(CO)2Cp]
[12], and now report on reaction studies carried out on
some of these compounds.
½CpðCOÞ3WfðCH2ÞnBrgꢂ þAgNO3
1 ðn¼3Þ; 2 ðn¼4Þ
! ½CpðCOÞ3WfðCH2ÞnONO2gꢂ þAgBr
ð1aÞ
ð1bÞ
1a ðn¼3Þ; 2a ðn¼4Þ
½CpðCOÞ3WfðCH2ÞnBrgꢂ þ AgNO2
! ½CpðCOÞ3WfðCH2ÞnNO2gꢂ þAgBr
1b ðn¼3Þ; 2b ðn¼4Þ
1
The H NMR spectra of 2a and 2b showed a significant
downfield shift of ca. 1 ppm due to the CH2NO2 and
CH2ONO2 protons versus the CH2Br protons of the start-
ing material [8]. In the 13C NMR spectra the carbon at-
tached to these protons was very deshielded, and found
at 72.9 and 75.0 ppm, respectively, compared to 8.16 ppm
for the starting material [8], reflecting the strong electro-
negativity of the nitro and nitrato groups.
Neither 1, [Cp(CO)3W{(CH2)3I}] (3), nor [Cp(CO)3W-
{(CH2)4I}] (4) reacted with sodium cyanide or potassium
cyanide in acetonitrile. However, the reaction of silver cya-
nide with compound 3 in acetonitrile gave the compound
[Cp(CO)3W{(CH2)3CN}] (3a) (Eq. (2))
2. Results and discussion
2.1. Reactions of [Cp(CO)3W{(CH2)nX}] (n = 3–5;
X = Br,I)
The compound [Cp(CO)3W{(CH2)3Br}] (1) was reacted
with silver nitrate in acetonitrile at room temperature to
give an orange product. Significant effervescence was noted
on the addition of the AgNO3 and the analytical data
obtained for the product implied a mixture of [Cp(CO)3W-
{(CH2)3ONO2}] (1a) and [Cp(CO)3W{(CH2)3NO2}] (1b).
Repeating the reaction at 0 ꢁC in the dark with [Cp-
(CO)3W{(CH2)4Br}] (2) gave [Cp(CO)3W{(CH2)4ONO2}]
(2a) only (Eq. (1a)). Apart from the elemental analysis data,
the key diagnostic feature was intense IR peaks at 1622 and
1280 cmꢀ1, assignable to the symmetric and asymmetric
N@O stretching of a covalent nitrate, respectively [13].
The reaction of [Cp(CO)3W{(CH2)4Br}] with AgNO2 at
0 ꢁC in the dark gave the yellow nitrobutyl compound
[Cp(CO)3W{(CH2)4NO2}] (2b) (Eq. (1b)), according to
the elemental analysis data and the absence of a peak in
its IR spectrum in the region indicative of an organo-nitrate
compound [14]. Both 2a and 2b are relatively stable and
were fully characterized. In contrast, the reaction of 1 at
0 ꢁC in the dark with AgNO3 and AgNO2, respectively,
gave products which were significantly less stable. Thus
compound 1a is pyrophoric in the solid state with even
traces of oxygen, whilst 1b is unstable in solution at room
temperature. The difference in the physical properties of
½CpðCOÞ3WfðCH2Þ3Igꢂ þAgCN
3
! ½CpðCOÞ3WfðCH2Þ3CNgꢂ þAgI
ð2Þ
3a
A sharp peak at 2244 cmꢀ1, characteristic of m(CN) was ob-
1
served in the infrared spectrum [13]. The H NMR spec-
trum showed peaks around 3.10 ppm (CH2CN) and
1.7 pm (CH2CH2CN) in the upfield region (Table 1). The
1
reaction proceeded slowly, as found by monitoring by H
NMR spectroscopy over several days (for the disappear-
ance of the CH2I peak) and did not reach completion.
The 13C NMR spectrum showed a peak at 119 ppm, which
is attributable to the cyano group [13].
A change of reaction medium had a significant effect on
the reaction. Hence, the reaction of AgCN with 3 in an
equi-volume mixture of nitrogen saturated water and tetra-
Table 1
IR, yields and 1H NMR data from the reaction studies of some of the tungsten halogenoalkyl compounds
Compound
IR m(CO)a (cmꢀ1
)
Yield (%)
Cpb
a-CH2
CH2L
CH2CH2L
b-CH2
c-CH2
[Cp(CO)3W{(CH2)3CN}]
[Cp(CO)3W{(CH2)4CN}]
[Cp(CO)3W{(CH2)3NO2}]
[Cp(CO)3W{(CH2)4NO2}]
[Cp(CO)3W{(CH2)4ONO2}]
[Cp(CO)3W{(CH2)4N3}]
[Cp(CO)3W{(CH2)5N3}]
a
2012sb, 1914sb
2011sb, 1912sb
2011sb, 1912sb
2011ss, 1912sb
2011ss, 1912sb
2011ss, 1912sb
2010ss, 1910sb
95
92
97
97
63
98
95
5.38s
5.38s
5.36s
5.38s
5.38s
5.38s
5.35s
1.44m
1.46m
1.49m
1.46m
1.46m
1.45m
1.51m
3.10t, 7.2c
3.42t, 7.2
4.43t, 6.6
4.38t, 7.1
4.44t, 6.6
3.42t, 6.7
3.16t, 6.7
1.70m
1.84m
1.71m
1.99m
1.71m
1.85m
1.82m
1.64m
1.62m
1.62m
1.67m
1.37m
1.47m
Measured in CH2Cl2 sb = strong broad, ss = strong sharp.
1H NMR spectra measured in CDCl3 relative to TMS (d = 0.00 ppm), s = singlet, m = multiplet, t = triplet; a-CH2 refers to the CH2-group a to
b
tungsten, etc.
c
J values are given in Hz.

E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
4617
hydrofuran over 4 days gave 3a in very high yield. Similarly,
[Cp(CO)2(PPhMe2)Mo{(CH2)3Br}] + AgCN
the reaction of NaCN with 4 in this solvent mixture over 4
days gave the yellow compound [Cp(CO)3W{(CH2)4CN}].
The reactions of the compounds [Cp(CO)3W{(CH2)4Br}]
and [Cp(CO)3W{(CH2)5I}] with sodium azide gave
[Cp(CO)3W{(CH2)4N3}] and [Cp(CO)3W{(CH2)5N3}],
respectively (Eq. (3))
[Cp(CO)(CN)(PPhMe2)Mo{CO(CH2)2CH2}] + AgBr
ð5Þ
The product was observed to decompose immediately in air.
The characterization data obtained for the product suggests
that the nucleophile, CNꢀ, induced cyclization to give a cyc-
lic carbene compound. In particular, a characteristic peak
at d = 366 ppm was observed in the 13C NMR spectrum,
which can be assigned to the carbene carbon. Reported alk-
oxy carbene compounds have carbene carbon peaks in this
region [15–17]. Similar results to the above were obtained
when the reaction above was repeated in ‘super dry’ etha-
nol. Whilst cyclic carbene formation is known to occur on
the reaction of [C5R5(CO)3Mo{(CH2)3Br}] (R = H, CH3)
with CNꢀ [16], the analogous compound with a bulky
PPh3 ligand, [Cp(CO)2(PPh3)Mo{(CH2)3Br}], was reported
to not react with nucleophiles to give carbene compounds.
The reaction of compound 5 with sodium azide in aceto-
nitrile at room temperature also gave a very unstable cyclic
carbene compound, as interpreted from the spectroscopic
data obtained. Repeating this reaction at low temperatures
(ꢀ8 and ꢀ40 ꢁC) gave the same product.
½CpðCOÞ3WfðCH2ÞnXgꢂ þNaN3
n¼4 ðX¼BrÞ; n¼5 ðX¼IÞ
! ½CpðCOÞ3WfðCH2ÞnN3gꢂ þ NaI
ð3Þ
In both of these reactions, there was a change in the m(CO)
region in the infrared spectrum after only 5 min from the
start of the reaction. A medium, broad band was observed
at 1639 cmꢀ1, suggesting that an alkyl migration reaction
may have occurred. However, no acyl group was seen in
the final product. As expected, a weak peak was observed
at 2155 cmꢀ1 that could be attributed to the stretching
vibrations of –N@N+@Nꢀ. Characterization data of the
products obtained from the above reactions are listed in
Tables 1 and 2.
2.2. Reactions of [Cp(CO)2(PPhMe2)Mo{(CH2)nBr}]
(n = 3,4)
2.3. Reactions of [Cp(CO)3W{(CH2)n}MLy] {n = 3,
MLy = Mo(CO)3Cp, Mo(CO)3Cp* and
Mo(CO)2(PMe3)Cp and n = 4, MLy = Mo(CO)3Cp}
and [Cp(CO)2Fe(CH2)3Mo(CO)2(PMe3)Cp]
The compound [Cp(CO)2(PPhMe2)Mo(CH2)3Br] (5)
was reacted with silver nitrate in acetonitrile to form
[Cp(CO)2(PPhMe2)Mo{(CH2)3ONO2}] (5a) as shown in
the following equation:
2.3.1. Reactions with neutral nucleophiles
½CpðCOÞ2ðPPhMe2ÞMofðCH2Þ3Brgꢂ þAgNO3
5
The compound [Cp(CO)3W(CH2)3Mo(CO)3Cp] (6)
reacted with PPh3 in acetonitrile to give the orange com-
pound, [Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp] (6a),
as shown in the the following equation:
! ½CpðCOÞ2ðPPhMe2ÞMofðCH2Þ3ONO2gꢂ þAgBr ð4Þ
5a
1
In the H NMR spectrum, the Cp peak shifted downfield
from 4.70 pm (starting material 5) to 5.31 ppm (product
5a), and the triplet at 3.34 ppm (5) shifted downfield to
4.33 ppm (5a). In the 13C NMR spectrum the Cp signal
of the product was observed downfield at 94.93 versus
91.83 ppm (5), and the –CH2Br peak moved from 37.69
(5a) to 68.14 ppm (5).
½CpðCOÞ3WðCH2Þ3MoðCOÞ3Cpꢂ þPPh3
6
! ½CpðCOÞ3WðCH2Þ3CðOÞMoðCOÞ2ðPPh3ÞCpꢂ
ð6Þ
6a
Monitoring this reaction by infrared spectroscopy showed
the growth of an acyl peak at 1712 cmꢀ1 and the concur-
rent disappearance of the band at 1963 cmꢀ1, assigned to
a terminal Mo–CO group of the starting material. A sharp
Compound 5 and silver cyanide were reacted in acetoni-
trile (Eq. (5)).
Table 2
13C NMR data from the reaction studies of some of the tungsten halogenoalkyl compoundsa
Compound
CO
CN
Cp
a-CH2
CH2L
CH2CH2L
b-CH2
c-CH2
[Cp(CO)3W{(CH2)3CN}]
[Cp(CO)3W{(CH2)4CN}]
[Cp(CO)3W{(CH2)3NO2}]
[Cp(CO)3W{(CH2)4NO2}]
[Cp(CO)3W{(CH2)4ONO2}]
[Cp(CO)3W{(CH2)4N3}]
[Cp(CO)3W{(CH2)5N3}]
a
228, 217
228, 217
b, 217
228, 217
228, 217
228, 217
228, 217
119.3
119.1
91.5
91.0
91.5
91.5
91.5
91.0
91.5
ꢀ11.9
ꢀ12.4
ꢀ12.3
ꢀ13.1
ꢀ12.3
ꢀ12.4
ꢀ12.4
11.7
33.5
72.9
75.0
72.9
33.6
33.6
40.9
35.0
32.6
33.2
32.5
35.1
35.1
38.3
33.1
32.6
38.4
38.5c
38.5c
Measured in CDCl3 relative to TMS (d = 0.00 ppm); a-CH2 refers to the CH2-group and a refers to tungsten, etc.
b
c
Not observed.
Peaks overlap.

4618
E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
triplet observed at 3.05 ppm in the 1H NMR spectrum
could be assigned to CH2 next to an acyl group. Also,
the CpMo peak moved upfield from 5.27 (6) to 4.97 ppm
(6a), whilst the position of the Cp peak assigned to tung-
sten was unchanged, relative to the starting material. In
the 13C NMR spectrum, the CpMo peak moved downfield
from 92.6 ppm in the starting material to 96.5 ppm. The
chemical shift of the WCH2 peak changed from ꢀ5.1 (6)
to ꢀ9.9 ppm (6a), the peak in the starting material assigned
to MoCH2 at 7.6 ppm had disappeared and was replaced
by a peak due to MoC(O)CH2 at 71.1 ppm, while the
MoCH2CH2 peak moved from 44.3 (6) to 33.2 ppm (6a).
The 13C NMR chemical shift for the acyl carbon was ob-
served downfield at 267 ppm. Similar compounds had acyl
carbon peaks around 261 ppm [7]. The data thus clearly
show that a migratory insertion reaction [18] had taken
place exclusively at the molybdenum end of the molecule.
Compound 6, when reacted with two equivalents of PPh3
in the same solvent, also gave 6a only i.e. no reaction at
the tungsten end of the molecule occurred.
A peak due to an acyl group in the infrared spectrum at
1603 cmꢀ1 and a triplet observed at ca. 2.9 ppm in the
1H NMR spectrum due to CH2C(O) confirmed that a
migratory insertion reaction had taken place. Peaks due
to both of the phosphine substituents were present in the
NMR spectra. The chemical shift of the carbon a to
molybdenum was shifted downfield, from 10.47 (8) to
31.85 ppm (8a,now adjacent to the acyl group) in the 13C
NMR spectrum, confirming the site of attack. The molyb-
denum side of the molecule was thus still more reactive
than the tungsten side and a metalloselective reaction with
PPh3 had occurred, despite the presence of the basic trim-
ethylphosphine substituent on the Mo, which should lower
the reactivity towards nucleophiles. Trimethylphosphine
also has a larger Tolman cone angle (118ꢁ) than the CO li-
gand (95ꢁ) [19], but clearly provided little steric hindrance
to further substitutions taking place on the molybdenum
site. The reaction of compound 8 with the more basic
PMe3 gave the less stable compound, [Cp(CO)3W(CH2)3-
C(O)Mo(CO)(PMe3)2Cp] (8b), which decomposed on melt-
ing at room temperature.
Compound 6 and PPh3 were refluxed in tetrahydrofuran
(THF) for 5 days. An acyl band was observed in the IR
The hydrolysis of compound 8a at 5 ꢁC in a hexane/
dichloromethane solution gave yellow crystals of [Cp(CO)3-
W{(CH2)2COOH}] (9), which were characterized by X-ray
crystallography [20]. Compound 8a may form the carbox-
ylic acid derivative by attack of a hydroxyl group, from
water, on the acyl group and displacing the Mo(CO)-
(PMe3)(PPh3)Cp moiety as shown in Scheme 1.
1
spectrum after two days at 1710 cmꢀ1. The IR and the H
and 13C NMR spectra of the final product showed the pres-
ence of PPh3 but not of the acyl group, implying that a
decarbonylation reaction had followed the alkyl migration
reaction, giving the compound [Cp(CO)3W(CH2)3Mo-
(CO)2(PPh3)Cp] (6b).
The complex, [Cp(CO)3W(CH2)3Mo(CO)3Cp*] (7),
when reacted with PPh3 in CH3CN also underwent a migra-
tory insertion reaction to yield an unstable complex, [Cp-
(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp*] (7a), as shown in
the following equation:
Bubbling carbon monoxide gas through a solution of
[Cp(CO)3W(CH2)3Mo(CO)3Cp] (10) in acetonitrile yielded
the unstable acyl complex, [Cp(CO)3W(CH2)3C(O)Mo-
(CO)3Cp] (10a), as shown in the following equation:
½CpðCOÞ3WðCH2Þ3MoðCOÞ3Cpꢂ þCO
½CpðCOÞ WðCH2Þ MoðCOÞ Cpꢃꢂ þPPh3
10
3
3
3
7
! ½CpðCOÞ3WðCH2Þ3CðOÞMoðCOÞ3Cpꢂ
ð9Þ
! ½CpðCOÞ WðCH2Þ CðOÞMoðCOÞ ðPPh3ÞCpꢃꢂ
ð7Þ
10a
3
3
2
7a
An acyl peak was observed in the infrared spectrum of 10a
A strong band due to an acyl carbonyl group was observed
at 1704 cmꢀ1 in the IR spectrum. The product showed a
at 1604 cmꢀ1, as was a triplet due to the protons next to the
1
acyl group at around 3.72 ppm in the H NMR spectrum.
1
triplet downfield at 2.33 ppm due to CH2C(O) in the H
Again the reaction took place selectively at the molybde-
num center, since the chemical shift of the CpMo was ob-
served at 5.36 ppm in the 1H NMR spectrum of 10a
compared to the CpMo shift at 4.88 ppm in 10 [8]. The
CpW peak shifted only slightly from 4.71 (10) [8] to
4.97 ppm (10a). This compound was too unstable for a
13C NMR spectrum to be recorded.
The complex [Cp(CO)2Fe(CH2)3Mo(CO)2(PMe3)Cp]
(11) also reacted with carbon monoxide gas in acetonitrile
to yield [Cp(CO)2Fe(CH2)3C(O)Mo(CO)2(PMe3)Cp] (11a)
(Eq. (10)).
NMR spectrum. This downfield shift relative to compound
6a was expected because Cp* is a better electron donor than
Cp, increasing the electron density on the molybdenum
centre, which in turn causes a downfield shift of the signal
due to protons adjacent to the acyl group. The reactions of
compound 7 with excess PPh3 in CH3CN or with PPh3 in
refluxing THF also gave only compound 7a.
The compound [Cp(CO)3W(CH2)3MO(CO)2(PMe3)Cp]
(8) also reacted with equimolar or excess quantities of
PPh3, resulting in the formation of the acyl compound 8a
shown in the following equation:
½CpðCOÞ2FeðCH2Þ3MoðCOÞ2ðPMe3ÞCpꢂ þCO
11
½CpðCOÞ3WðCH2Þ3MoðCOÞ2ðPMe3ÞCpꢂ þPPh3
8
! ½CpðCOÞ2FeðCH2Þ3CðOÞMoðCOÞ2ðPMe3ÞCpꢂ
ð10Þ
11a
! ½CpðCOÞ3WðCH2Þ3CðOÞMoðCOÞðPPh3ÞðPMe3ÞCpꢂ
A strong peak at 1603 cmꢀ1 due to the acyl group was
observed in the carbonyl region of the infrared spectrum.
8a
ð8Þ

E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
4619
OH
H
2O
OH
C
O
Mo PMe3
W
W
δ
δ
Mo PMe3
C
O
OC
OC
OC
OC
CO
CO
PPh3
CO
CO
PPh3
HO
Mo PMe3
C
O
W
OC
OC
CO
PPh3
CO
OH
+
C
W
OC
OC
Mo PMe3
CO
H
O
CO
PPh3
Scheme 1. Possible pathway to the compound [Cp(CO)3W{(CH2)3COOH}].
The high basicity of the substituent PMe3 seems to stabilize
the CO-inserted product by increasing the electron density
on the metal. Consequently, a 13C NMR spectrum could
0.16 ppm) relative to the starting material, and this further
supports the conclusion that Mo was the site of attack. This
chemistry thus parallels the reaction of [Cp(CO)2Fe(CH2)3-
Mo(CO)3Cp] with CO, where only the Mo centre is at-
tacked [7]. Thus the greater basicity and bulk of the PMe3
versus CO coordinated to the molybdenum again does
not hinder attack, as was also observed for the reaction of
8 with PPh3 as described above.
1
be obtained. The H NMR spectrum showed a triplet at
2.90 ppm corresponding to the CH2 protons adjacent to
the carbonyl group. The 13C NMR spectrum showed a shift
of ca. 5 ppm observed for the CpMo (from 90.85 ppm in 11
[8] to 95.06 ppm), MoC(O)CH2 70.86 ppm, FeCH2
3.87 ppm (versus 9.60 in 11) and the central carbon of the
alkyl chain at 33.88 ppm compared to 46.10 ppm [8]. The
CpFe peak of the product shifted only slightly (by
Characterization data for the above compounds are
given in Tables 3–5 and a summary of the reactions is
shown in Scheme 2.
Table 3
Yields, melting point and IR data from the reaction studies on some of the heterobimetallic compounds
Compound
Yield (%)
MP (ꢁC)
IR m(CO) (cmꢀ1 a
)
[Cp(CO)3W(CH2)3C(O)Mo(CO)(PMe3)(PPh3)Cp]
[Cp(CO)3W(CH2)4C(O)Mo(CO)(PMe3)2Cp]
[Cp(CO)2Fe(CH2)3C(O)Mo(CO)2(PMe3)Cp]
[Cp(CO)3W(CH2)3C(O)Mo(CO)3Cp]
[Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp*]
[Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp]
[Cp(CO)2Fe(CH2)3C(O)Mo(CO)2(PMe3)Cp]
a
88
92
90
98
93
89
98
78–84
dec.
118–124
dec.
82–86
146–148
dec
2010s
2010s
2002s
2010s
2011ss
2009ss
1998s
1912sb
1911sb
1940sb
1979vsb
1912sb
1911sb
1938vs
1843sh
1838sh
1843vsb
1911vsb
1844sm
1850ss
1921s
1603w
1604w
1793wb
1604wb
1704s
1613wb
1713ss
Measured in CH2Cl2, s = strong, sb = strong broad, ss = strong sharp, vs = very strong, vsb = very strong broad, w = weak, wb = weak broad.
Table 4
1H NMR data from the reaction studies on some of the heterobimetallic compoundsa
Compound
CpMo Cp*Mo CpW/Fe b-Mo
a-W/Fe c-Mo
d-Mo
P–Ph
P–CH3
[Cp(CO)3W(CH2)3C(O)Mo(CO)(PMe3)(PPh3)Cp] 5.27s
5.39s
5.35s
5.39s
4.97s
4.70s
2.93t, 7.5b 0.86s
2.35s
2.33s
2.13s
1.65m
1.61s
7.36m 1.52d, 9H, 9.3
1.54d, 18H, 12.8
7.53m
[Cp(CO)3W(CH2)4C(O)Mo(CO)(PMe3)2Cp]
[Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp*]
[Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp]
[Cp(CO)2Fe(CH2)3C(O)Mo(CO)2(PMe3)Cp]
a
5.10s
2.93t, 7.3
2.33t, 7.2
3.05t, 6.9
2.95t, 7.4
0.85s
1.64s
1.43s
1.34s
1.60m
2.00
5.36s
5.10s
7.44m
1.57d, 9H, 9.6
Measured in CDCl3 relative to TMS (0.00 ppm), a-CH2 refers to the CH2-group a to molybdenum, etc.
J values in Hz.
b

4620
E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
2.3.2. Thermal decomposition
The thermal decomposition of [Cp(CO)2Fe(CH2)3Mo-
(CO)2(PMe3)Cp] (11) was investigated. The condensed gas-
eous products were identified by 1H NMR spectroscopy. A
singlet due to cyclopropane was observed at 0.2 ppm along
with peaks at 5.6 ppm (–CH@CH2), 3.7 ppm (–CH@CH2),
1.8 ppm (–CH3) which were assigned to propene, an
expected product from this type of reaction. The dimers
[Cp(CO)2Fe]2 and [Cp(CO)2(PMe3)Mo]2 were shown to
be the main components of the dark red solid residue
1
(IR, H NMR [6]).
The mechanism for this type of reaction has been reported
to follow a b-elimination and reductive process as shown for
the proposed thermolysis of 11 in Scheme 3. We obtained
propene and cyclopropane in the ratio of approximately
4:1 for the thermolysis of 11 versus a ratio of approximately
1:1.3 reported for [Cp(CO)2Fe(CH2)3Ru(CO)2Cp] [21],
reflecting the influence of the different metals.
2.4. Crystal structure of [Cp(CO)3W(CH2CH2CH2NO2)]
The structure of [Cp(CO)3W(CH2CH2CH2NO2)] (1b) is,
to our knowledge, the first report of a crystal structure of a
nitropropyl transition metal complex. Three related func-
tionalized propyl structures of the general formula
Cp(CO)3W(CH2CH2CH2Z) have been reported, with
Z = Br (1) [6], Z = I (3) [22] and Z = COOH (9) [20].
The asymmetric unit is comprised of one molecule, with
four molecules in the unit cell. Fig. 1 illustrates the molec-
ular geometry and atomic numbering scheme employed. In
the molecule, the W atom is coordinated in a piano stool
fashion by a pentahapto-cyclopentadienyl ligand, three
carbonyl ligands and a nitropropyl chain bonded through
a carbon atom. This geometry can also be viewed as dis-
torted square pyramidal, where a single bond to the cen-
troid of the cyclopentadienyl ligand at the apex of the
square pyramid is assumed. Related compounds 1, 3 and
9 also adopt this coordination geometry in the solid state.
The C atoms constituting the cyclopentadienyl ring are
˚
co-planar, with an r.m.s. deviation of 0.002 A, and the
˚
C
Cp–CCp bond lengths range from 1.411(6) to 1.420(5) A.
The five W–C bond lengths vary from 2.304(4) to
˚
2.379(4) A, and fall within the normal range. A W–C9
˚
bond length of 2.330(4) A is observed, a value that com-
pares well with W–Calkyl bond lengths reported for related
˚
˚
structures (2.347(15) and 2.336(14) A for 1, 2.329(5) A for
3 and 2.319(4) A for 9).
˚
The nitropropyl chain is distorted from the ideal, ener-
getically favoured, all-trans conformation (indicated by a
torsion angle of 180ꢁ), with a C9–C10–C11–N torsion
angle of 77.4(4)ꢁ. This distortion occurs to allow N–
Oꢁ ꢁ ꢁO–N close contact interactions between the oxygen
atoms on pairs of neighbouring nitro groups. These short,
non-hydrogen intermolecular contacts involve atoms O4
and O5 (symmetry operator: 1 ꢀ x, ꢀ y, ꢀ z) and O5 and
O4 (symmetry operator: 1 ꢀ x, ꢀ y, ꢀ z), which approach
˚
each other at an Oꢁ ꢁ ꢁO distance of 2.624 A, and results

E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
4621
R
R
R
R
R
R
OC
CO
CO
R
R
L
Mo (CH2)n
W
OC
CO
CO
THF / Reflux
or
CH3CN / RT
R
R
OC
Mo
C
O
(CH2)n
W
Y
CO
OC
L
Y
THF
R
2L
6a Y = CO, n = 3, L = PPh3, R = H
R
7a Y = CO, n = 3, L = PPh3, R = CH3
8a Y = PMe3, n = 3, L = P Ph3, R = H
8b Y = PMe3, n = 4, L = PMe3, R = H
10a Y = CO, n = 3, L = CO, R = H
R
OC
CO
CO
R
R
Mo (CH2)n
W
OC
L
Y
6b Y = CO, n = 3, L = PPh3, R = H
Scheme 2. Summary of the reactions of heterobimetallic complexes.
CH2
OC
Fe
OC
CO
CH2
3
3
CO
CO
Mo
PMe3
Fe
Mo
PMe3
CO
OC
Fe
Mo
PMe3
OC
OC
C
O
C
O
CH2
Fe
H
Mo
PMe3
OC
C
O
Scheme 3. Proposed thermolysis pathway for compound 11.
Fig. 2. Packing diagram of 1b, viewed down the b-axis. The short contacts
between atoms O4 and O5i, and O4i and O5 (symmetry code for i:
1 ꢀ x, ꢀ y, ꢀ z) are illustrated by the dashed lines.
Fig. 1. Molecular diagram of 1b, illustrating the atomic numbering
scheme and displacement ellipsoids at the 50% probability level.

4622
E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
in the formation of a centrosymmetrical dimer, illustrated
in Fig. 2. It is interesting to note that this deviation from
ideal geometry is also observed for 9, where an O–H. . .O
carboxylic acid dimer hydrogen bonding interaction is
present. However, in structures 1 and 3 the halogenopropyl
chains adopt an extended, all-trans conformation.
The molecular packing, as viewed down the b-axis, is illus-
trated in Fig. 2. A layered structure is formed in which a two-
dimensional sheet containing the interdigitated nitropropyl
moieties alternates with a bilayer sheet of CpW(CO)3 groups.
These layers extend parallel to the bc-plane of the unit cell.
The plane through the C atoms of the cyclopentadienyl
carbon is tilted by 61.88(13)ꢁ relative to the layer plane.
data were collected on an Oxford Excalibur2 CCD area
detector diffractometer, employing x–2h scans, with Mo
˚
Ka radiation (k = 0.71073 A) at 150 K. Data collection
and cell refinement were performed with the program CRY-
SALIS CCD 170 [24], and data reduction was carried out
using the program CRYSALIS RED 170 [24]. In total, 9233
reflections were measured, of which 3200 were independent
and 2789 > 2r(I), Rint = 0.0402 and hmax = 29.40ꢁ. Absorp-
tion corrections were performed employing the Multiscan
[25] programme. The crystal structure was solved by
SHELXS-97 [26] and refined by least squares methods (refine-
ment on F2) using SHELXL-97 [26] as part of the WinGX [27]
suite of programs. All hydrogen atoms were placed in calcu-
lated positions and refined using a riding model. A geomet-
ric analysis of the molecule was performed with the program
PLATON [28] in the WinGX [27] suite. Molecular diagrams
were generated with the computer programme ORTEP3
[29]. Compound 1b crystallizes in the monoclinic space-
3. Conclusions
The reaction studies carried out on the halogenoalkyl
compounds have shown that the terminal carbon is always
attacked in the tungsten complexes to give direct substitu-
tion products. The reactions of the molybdenum com-
pounds are more complex, with a nitroalkyl compound
forming on reaction with AgNO3, but other nucleopliles
ðCNꢀ; Nꢀ3 Þ attack the molybdenum to induce the forma-
tion of cyclic carbene compounds. The molybdenum centre
is thus significantly more reactive towards nucleophiles
than is the tungsten centre.
˚
group P21/c, with unit cell parameters a = 14.228(8) A,
˚
˚
˚
b = 8.054(6) A, c = 11.120(7) A and b = 103.23(5) A. The
final refinement gave values of R[F2 > 2r(F2)] = 0.0243
and wR(F2) = 0.0647 for 163 parameters. Table 6 lists
selected bond lengths, bond angles and torsion angles.
4.2. [Cp(CO)3W{(CH2)4NO2}]
Investigations into the chemistry of the alkanediyl com-
pounds, where the iron or tungsten and molybdenum cen-
tres were incorporated within the same molecule, showed
metalloselective reactions. The reaction sites, and hence
sites of possible alkyl functionalization, were predictable
from the chemistry of the monometallic analogues with
nucleophiles and the molybdenum centre was thus found
to be very reactive, even in those cases where a tertiary
phosphine ligand was already present.
A solution of [Cp(CO)3W{(CH2)4Br}] (2) (0.43 g,
0.84 mmol) in acetonitrile (10 ml) was prepared and cooled
to 0 ꢁC and silver nitrite (0.17 g, 0.1.08 mmol) added in the
Table 6
˚
Selected bond lengths (A), angles (ꢁ) and torsion angles (ꢁ)
ꢀ
Bond lengths (A)
C9–C10
C10–C11
C11–N
N–O5
1.526(5)
1.531(5)
1.520(5)
1.218(5)
1.321(4)
1.992(4)
1.993(4)
1.967(4)
2.330(4)
1.141(4)
1.147(5)
1.150(5)
4. Experimental
N–O4
W–C6
W–C7
W–C8
W–C9
C6–O1
C7–O2
C8–O3
All reactions were carried out under inert atmosphere
using standard Schlenk tube techniques. Acetonitrile
(Merck 99%) was distilled over phosphorus pentoxide
(Associated Chemical Enterprises 99%) and stored over
˚
molecular sieves 4 A under nitrogen. Methanol (Crest
Technical grade) and ethanol (NCP 99.9%) were distilled
over CaCl2 or Mg/I2 to obtain a ‘super dry’ solvent accord-
ing to the reported method [23]. Dichloromethane (Shalom
technical grade) and chloroform (Spectrochem 99.5%) were
double distilled and kept under molecular sieves 3 A under
nitrogen. All other details are as previously reported [8].
Bond angles (ꢁ)
O5–N–C11
O5–N–O4
O4–N–C11
C10–C9–W
N–C11–C10
C9–C10–C11
O3–C8–W
123.3(4)
123.5(4)
113.2(3)
117.4(3)
113.7(3)
112.0(3)
177.1(3)
177.4(4)
177.4(3)
˚
4.1. Crystallography
O2–C7–W
O1–C6–W
Good quality single crystals of Cp(CO)3W(CH2CH2-
CH2NO2) (1b) were obtained by crystallization from a dilute
CH2Cl2/hexane solution in a refrigerator at 5 ꢁC. A yellow,
plate-like crystal of dimensions 0.05 · 0.20 · 0.20 mm was
selected for the crystallographic investigation. Intensity
Torsion angles (ꢁ)
C11–C10–C9–W
C9–C10–C11–N
C10–C11–N–O5
C10–C11–N–O4
ꢀ168.3(2)
77.4(4)
11.2(5)
ꢀ170.0(3)

E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
4623
dark. The mixture was stirred at 0 ꢁC overnight. The reac-
tion was monitored in the m(CO) region of the infrared
spectrum. The solvent was then removed under reduced
pressure leaving a mixture of yellow and grey solids. This
was extracted with a 4:1 mixture of hexane and dichloro-
methane and filtered through a cannula under nitrogen.
The solvent was removed at reduced pressure to give a yel-
low solid (2b) which was dried under reduced pressure. The
IR spectrum showed the expected typical m(N@O) stretches
at 1553 cmꢀ1 (asym) and 1382 cmꢀ1 (sym). Found (Calc.):
C, 33.8 (33.1); H, 3.0 (3.0); N, 2.6 (3.2)%.
removed under reduced pressure leaving a yellow solid, which
was washed with hexane and dried under reduced pressure.
4.7. [Cp(CO)3W{(CH2)5N3}]
This was prepared by a procedure similar to that
described in Section 4.6 using [Cp(CO)3W{(CH2)5I}]
(0.054 g, 0.103 mmol).
4.8. [Cp(CO)2(PPhMe2)Mo{(CH2)3ONO2}]
The compound [Cp(CO)2(PPhMe2)Mo{(CH2)3Br}] (5)
(0.130 g, 0.257 mmol) and AgNO3 (0.04 g, 0.257 mmol)
were dissolved in acetonitrile (5 ml) and stirred for 24 h.
The resulting yellow solution was filtered through a can-
nula, under nitrogen into a pre-weighed Schlenk tube. The
solvent was removed under reduced pressure and the prod-
uct (5a) recrystallized from a dilute dichloromethane/hex-
ane mixture. The orange precipitate was collected and
dried under reduced pressure. Yield = 95%; IR m(CO)
4.3. [Cp(CO)3W{(CH2)4ONO2}]
A
solution of [Cp(CO)3W{(CH2)4Br}] (2) (0.47 g,
0.91 mmol) in acetonitrile (6 ml) was prepared and cooled to
0 ꢁC and silver nitrate (0.169 g, 1.00 mmol) added in the dark.
The mixture was stirred at 0 ꢁC overnight. The reaction was
monitored in the m(CO) region of the infrared spectrum. The
solution was filtered via cannula under nitrogen into a pre-
weighed Schlenk tube. The solvent was then removed under
reduced pressure leaving a pale yellow solid (2a). This was
washed with hexane and dried under reduced pressure. The
IR spectrum showed the expected typical m(N@O) stretches
1
(CH2Cl2): 1922 (sb), 1910 (ss); H NMR(CDCl3) in ppm:
5.31 (singlet, Cp), 1.77 (multiplet, Mo–CH2), 1.99 (multi-
plet, Mo–CH2CH2), 4.33 (triplet, CH2ONO2), 7.42 (multi-
plet, P–Ph), 1.70 (doublet, P–CH3, JPH = 10.2 Hz); 13C
NMR (CDCl3): 94.9 (Cp), 14.0 (Mo–CH2), 38.7 (Mo–
CH2CH2), 68.1 (CH2ONO2), 128 (doublet, P–Ph,
JPC = 9.7 Hz), 18.4 (doublet, P–CH3, JPC = 32.8 Hz).
at 1622 cmꢀ1 (asym) and 1280 cmꢀ1 (sym) and 869 cmꢀ1
Found (Calc.): C, 32.4 (32.0); H, 3.1 (2.9); N, 2.8 (3.1)%.
.
4.4. [Cp(CO)3W{(CH2)3Z}] (Z = NO3 and NO2)
[Cp(CO)(N3)(PPhMe2)Mo{CO(CH2)2CH2}]
4.9.
These compounds (1a and 1b) were prepared as in Sec-
tions 4.2 and 4.3.
Compound 5 (0.08 g, 0.174 mmol) and NaN3 (0.011 g,
0.175 mmol) were weighed into a Schlenk tube, dissolved
in acetonitrile (8 ml) and stirred for 24 h. The solution
was then filtered via cannula under nitrogen and the sol-
vent removed under reduced pressure. The residue was
recrystallized from a dilute dichloromethane/hexane mix-
ture to give an orange precipitate. Yield = 90%. IR m(CO)
4.5. [Cp(CO)3W{(CH2)nCN}] (n = 3,4)
The compound [Cp(CO)3W{(CH2)3I}] (3) (0.106 g,
0.21 mmol) was weighed into a Schlenk tube. Silver cyanide
(0.03 g, 0.22 mmol) was added, followed by a mixture of
nitrogen saturated double distilled de-ionized water (2 ml)
and THF (2 ml). The mixture was stirred for 4 days. The
solvent was removed under reduced pressure and the prod-
uct recrystallized from a dichloromethane/hexane mixture
and dried under reduced pressure.
1
(CH2Cl2): 1967 (sb), 1911 (ss); H NMR(CDCl3) in ppm:
5.30 (singlet, Cp), 3.59 (multiplet, Mo@CCH2), 1.97 (mul-
tiplet, Mo@CCH2CH2), 4.71 (multiplet, OCH2), 7.44 (mul-
tiplet, P–Ph), 1.74 (doublet, P–CH3, JHH = 8.4 Hz); 13C
NMR(CDCl3): 94.5 (Cp), 62.1 (Mo@CCH2), 22.0
(Mo@CCH2CH2), 84.8 (OCH2), 128 (doublet, P–Ph,
JPC = 9.7 Hz), 19.4 (doublet, P–CH3, JPC = 34 Hz).
A similar reaction was carried out using 4 and NaCN
instead of AgCN, and [Cp(CO)3W{(CH2)4CN}] was
obtained.
4.10. [Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp]
4.6. [Cp(CO)3W{(CH2)4N3}]
(a) The complex [Cp(CO)3W(CH2)3Mo(CO)3Cp] (6)
(0.11 g, 0.178 mmol) and PPh3 (0.047 g, 0.179 mmol)
were weighed into a Schlenk tube and dissolved in
acetonitrile (4 ml). The resulting solution was stirred
at room temperature for 3 days and monitored by
IR spectroscopy in the m(CO) region. The solution
was concentrated under reduced pressure and the
product, a yellow precipitate, was filtered off. To
recrystallize, the product was dissolved in minimum
dry dichloromethane and an equal volume of hexane
The compound [Cp(CO)3W{(CH2)4Br}] (2) (0.1 g,
0.22 mmol) and sodium azide (0.015 g, 0.213 mmol) were
weighed into an empty Schlenk tube. The Schlenk tube was
evacuated and then filled with nitrogen and acetonitrile
(7 ml) was subsequently added. There was a notable change
in the m(CO) region in the IR spectrum after 5 min. At the
end of the reaction, as determined by no further changes in
the IR spectrum, the solution was filtered via cannula under
nitrogen into a pre-weighed Schlenk tube. The solvent was

4624
E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
was added. The mixture was immersed in a cold dry-
4.13. [Cp(CO)3W(CH2)3C(O)Mo(CO)(PMe3)(PPh3)Cp]
ice–acetone bath (ꢀ60 ꢁC) for a minute. The mother
liquor was decanted and the residue dried under
reduced pressure to give 6a as a yellow powder.
(a) The complex [Cp(CO)3W(CH2)3Mo(CO)2(PMe3)Cp]
(8) (0.098 g, 0.173 mmol) was dissolved in acetonitrile
(5 ml) and PPh3 (0.038 g, 0.146 mmol) was added.
The mixture was stirred at room temperature until
no more changes were observed in the m(CO) region
in the IR spectrum (18 h). An orange precipitate
had also formed. The solvent was removed under
reduced pressure. The residue was dissolved in mini-
mum dichloromethane and the product 8a precipi-
tated with hexane to give a light yellow solid.
(b) The above reaction was repeated in a 1:2 molar ratio
of 8 to PPh3 to give the same compound (8a) as in (a)
above in 72% yield.
(b) The reaction above was repeated with 1:2 molar
ratio of the compounds i.e. compound 6 (0.11 g,
0.178 mmol) and PPh3 (0.094 g, 0.358 mmol) in ace-
tonitrile (4 ml). All further details were as above.
(c) A mixture of 6 (0.105 g, 0.17 mmol) and PPh3
(0.044 g, 0.17 mmol) was weighed into a Schlenk tube
and dissolved in a minimum of THF (8 ml). The
resulting solution was refluxed, while monitoring
the changes in the carbonyl region of the infrared
spectrum twice a day. No further changes were
observed on days 8 and 9. The reaction was allowed
to cool to room temperature under nitrogen. The sol-
vent was then removed under reduced pressure. A red
residue was obtained which was dissolved in a mini-
mum of dichloromethane and the yellow product pre-
cipitated using hexane. The product (6a) was filtered
off and dried under reduced pressure.
4.14. [Cp(CO)3W(CH2)4C(O)Mo(CO)(PMe3)2Cp]
A solution of [Cp(CO)3W(CH2)4Mo(CO)2(PMe3)Cp] (8)
(0.10 g, 0.172 mmol) and PMe3 (0.013 g, 0.172 mmol) was
made up in acetonitrile (5 ml). The mixture was stirred at
room temperature for 3 days while monitoring the reaction
progress using 1H NMR spectroscopy. The orange solution
was evaporated to dryness under reduced pressure to leave
a light yellow residue, which was dissolved in minimum of
dichloromethane, filtered and the product (8b) precipitated
with hexane.
4.11. [Cp(CO)3W(CH2)3Mo(CO)2(PPh3)Cp]
The above reaction was repeated with a 2:1 ratio of PPh3
(0.084 g, 0.320 mmol) and 6 (0.10 g, 0.161 mmol) in THF
(8 ml). Again the changes were monitored using IR in the
carbonyl region of the IR spectrum, and the reaction was
judged to be complete after 5 days. Work-up of the product
was repeated as above and a yellow product (6b) was
obtained which was dried and characterized. Yield = 84%.
The IR m(CO) (CH2Cl2) in cmꢀ1: 2010 ss, 1913 sm, 1870
4.15. [Cp(CO)3W(CH2)3C(O)Mo(CO)3Cp]
The complex [Cp(CO)3W(CH2)3Mo(CO)3Cp] (10)
(0.186 mmol) was dissolved in acetonitrile (5 ml) in a
Schlenk tube and sealed with a rubber suba seal. Using a
slender, flexible Teflon tube, carbon monoxide gas was
bubbled into the solution. The reaction was followed by
observing changes in the m(CO) region in the infrared spec-
trum. A strong, sharp acyl band was observed in the car-
bonyl region of the IR spectrum. The bubbling was
stopped after 30 h. The product was dried under reduced
pressure and recrystallized from a dichloromethane/hexane
mixture. The product (10a) obtained was unstable and was
only partially characterized.
1
ss, 1848 sh; m.p.: 182–185 ꢁC; H NMR (CDCl3) in ppm:
7.4 (multiplet, Ph), 5.38 (singlet, WCp), 4.74 (singlet,
MoCp), 1.97, 1.65, 0.86 (CH2CH2CH2); 13C NMR (CDCl3)
in ppm: 128.49 (doublet, Ph, JPC = 12.3 Hz), 91.53, 95.83
(Cp), ꢀ11.06 (W–CH2), 1.01(Mo–CH2), 31.57 (W–CH2CH2).
4.12. [Cp(CO)3W(CH2)3C(O)Mo(CO)2(PPh3)Cp*]
(a) The compound [Cp(CO)3W(CH2)3Mo(CO)3Cp*] (7)
(0.20 g, 0.29 mmol) and PPh3 (0.076 g, 0.29 mmol)
were weighed into a Schlenk tube and the mixture dis-
solved in acetonitrile (4 ml). The solution was stirred
at room temperature for 3 days, after which the sol-
vent was removed under reduced pressure. The yellow
product was dissolved in minimum dry dichlorometh-
ane. Dry hexane was added until the product just
started to precipitate. The mixture was then immersed
in a dry-ice–acetone bath (ꢀ60 ꢁC) for 2 min. The
mother liquor was decanted and the residue dried
under reduced pressure to give 7a as a yellow powder.
(b) The above reaction (a) was repeated in a 1:2 molar
ratio. The compound 7 (0.20 g, 0.29 mmol) was
reacted with PPh3 (0.152 g, 0.58 mmol) in acetonitrile
(4 ml) at room temperature for 4 days. Work-up was
as reported in (a) above.
4.16. [Cp(CO)2Fe(CH2)3C(O)Mo(CO)2(PMe3)Cp]
Reaction conditions were as above, except that [Cp(CO)2-
Fe(CH2)3Mo(CO)2(PMe3)Cp] (11) (0.15 g, 0.31 mmol) was
dissolved in acetonitrile (5 ml) to give 11a after reaction
and work-up.
4.17. Thermal decomposition of
[Cp(CO)2Fe(CH2)3Mo(CO)2(PMe3)Cp]
The compound [Cp(CO)2Fe(CH2)3Mo(CO)2(PMe3)Cp]
(11) (0.1 g, 0.21 mmol) was weighed into a Schlenk tube,
which was connected to a second Schlenk tube containing
CDCl3 immersed in liquid nitrogen. The system was evac-

E.O. Changamu et al. / Journal of Organometallic Chemistry 691 (2006) 4615–4625
4625
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uated. The Schlenk tube containing 11 was heated to
decomposition. The gaseous products were trapped in the
Schlenk tube immersed in the liquid nitrogen. The solid res-
idue after the heating was red in colour. The condensed
gaseous products dissolved into the CDCl3 when the solu-
tion was allowed to attain room temperature. The 1H
NMR spectrum of the solution was obtained. The data
obtained were as follows: (propene) 5.60, 3.73, 1.83 ppm
and (cyclopropane) 0.223 ppm.
[9] P.M. Maitlis, H.C. Long, R. Quyoum, M.L. Turner, Z.-Q. Wang,
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Acknowledgements
We thank the University of KwaZulu-Natal (URF) and
the National Research Foundation (NRF) for funding. We
also thank the Deutscher Akademischer Austausch Dienst
(DAAD) for a Ph.D. Scholarship (M.O.O.) and the Jomo
Kenyatta University of Agriculture and Technology
(M.O.O.). E.O.C. thanks Kenyatta University for study
leave. The assistance of Ms. Z. Mabuza in the laboratory
is also acknowledged.
[12] S.J. Archer, K.P. Finch, H.B. Friedrich, J.R. Moss, A.M. Crouch,
Inorg. Chim. Acta 182 (1991) 145.
[13] R.M. Silverstein, G.C. Bassler, T.C. Morrill, Spectrometric Identifi-
cation of Organic Compounds, Wiley, Singapore, 1991.
[14] R. Ballino, L. Barboni, G. Giarlo, J. Org. Chem. 69 (2004) 6907.
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Appendix A. Supplementary material
[17] H. Adams, N.A. Bailey, M.J. Winter, J. Chem. Soc., Dalton Trans.
(1984) 273.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC 279095. Copies of this information may be
obtained free of charge from: The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223
336 033 or e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk). Supplementary data associ-
ated with this article can be found, in the online version,
at doi:10.1016/j.jorganchem.2006.07.003.
[18] F. Calderazzo, Angew. Chem., Int. Ed. Engl. 16 (1977) 299.
[19] C.A. Tollman, Chem. Rev. 77 (1977) 313.
[20] H.B. Friedrich, R.A. Howie, M.O. Onani, Acta Crystallogr., Sect. E
60 (2004) m1641.
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(1983) 2435.
[22] H.B. Friedrich, M.O. Onani, M. Rademeyer, Acta Crystallogr., Sect.
E 61 (2005) m144.
[23] B.S. Furniss, A.J. Hannaford, P.W.G. Smith, A.R. Tatchell, Vogel’s
Textbook of Practical Organic Chemistry, fifth ed., Longman, New
York, 1978, p. 401.
[24] Oxford Diffraction Ltd, CrysAlis CCD and CrysAlis RED. Version
1.170, Oxford Diffraction Ltd, Abingdon, Oxford, England, 2003.
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