Synthesis, characterization and reactivity of the ω-haloalkyl complexes [(η5-C5R5)W(CO)3{(CH2)nX}] (R=H, n=3-7, X=Br and I; R=CH3, n=3, 4, X=Br and I)

Article abstract of DOI:10.1016/S0022-328X(98)00848-1

The new ω-bromoalkyl tungsten complexes [CpW(CO)₃{(CH₂)_nBr}] (n=5-7) and [Cp*W(CO)₃{(CH₂)_nBr}] (n=4) were prepared in good yields by the reactions of Na[CpW(CO)₃] or Na[Cp*W(CO)<

Full text of DOI:10.1016/S0022-328X(98)00848-1

Journal of Organometallic Chemistry 574 (1999) 252–266
Synthesis, characterization and reactivity of the ꢀ-haloalkyl complexes
[(p5-C5R5)W(CO)3{(CH2)nX}] (R=H, n=3–7, X=Br and I;
R=CH3, n=3, 4, X=Br and I)
Xiaolong Yin *, John R. Moss 1
Department of Chemistry, Uni6ersity of Cape Town, Rondebosch 7700, South Africa
Received 21 April 1998; received in revised form 12 June 1998
Abstract
The new ꢀ-bromoalkyl tungsten complexes [CpW(CO)3{(CH2)nBr}] (n=5–7) and [Cp*W(CO)3{(CH2)nBr}] (n=4) were
prepared in good yields by the reactions of Na[CpW(CO)3] or Na[Cp*W(CO)3] with the appropriate dibromoalkanes. The
iodoalkyl complexes [CpW(CO)3{(CH2)nI}] (n=3–7) and [Cp*W(CO)3{(CH2)nI}] (n=3 and 4) were prepared by reacting
[CpW(CO)3{(CH2)nBr}] or [Cp*W(CO)3{(CH2)nBr}] with sodium iodide, or by reacting the Na[CpW(CO)3] with the appropriate
diiodoalkanes. These new complexes have been fully characterized by elemental analyses, IR, 1H-, 13C-NMR and mass
spectroscopy. The thermal and electrochemical properties of some of the haloalkyl complexes are reported. The reaction of
[CpW(CO)3{(CH2)3Br}] with 3,5-dihydroxybenzyl alcohol gave both the mono- and the di-tungsten benzyl alcohol complexes
[{CpW(CO)3(CH2)3Oꢀ}{C6H3(OH)}ꢀCH2OH] and [{CpW(CO)3(CH2)3Oꢀ}2(C6H3)ꢀCH2OH]. The later complex reacted with
CBr4 and PPh3 to give the benzyl bromide complex [{CpW(CO)3(CH2)3Oꢀ}2(C6H3)ꢀCH2Br]. The reaction of [Cp-
W(CO)3{(CH2)3Br}] with 1,1,1-tris(4%-hydroxyphenyl)ethane gave the tri-nuclear tungsten complex [{CpW(CO)3(CH2)3Oꢀ
(C6H4)}3ꢀCCH3]. © 1999 Published by Elsevier Science S.A. All rights reserved.
Keywords: Haloalkyl; Tungsten; Cyclopentadienyl; Carbonyl; Bromide; Iodide
wide range of useful compounds including acyclic and
cyclic carbene complexes [12–14], homo- and hetero-
1. Introduction
bimetallic hydrocarbon-bridged complexes [13,15–17],
dendrimers [18,19], as well as many other classes of
Haloalkyl transition metal complexes of the type
[LyM{(CH2)nX}] (Ly=ligands, M=transition metal,
X=halogen, n]1), which were quite rare 30 years ago
[1], are now well known [2–10]. The synthesis and
chemistry of some haloalkyl complexes have recently
been extensively investigated [3–10] and comprehen-
sively reviewed by Moss and Friedrich [2,11]. The
haloalkyl complexes show interesting and novel chem-
functionalized alkyl compounds [9].
The complexes [(p5-C5R5)W(CO)3{(CH2)nX}] (where
n=1; R=H and CH3, X=Cl, Br and I) have been
reported [8,9]. Although the complexes [(p5-
C5R5)W(CO)3{(CH2)nX}] (X=Br; R=H, n=3 and 4
[1]; R=CH3, n=3 [14]) have been reported by King
and co-workers in 1967, the reactivity of these com-
plexes has been less studied [1,2,12–14]. The reaction of
istry and can be used, for example, as precursors for a
Na[CpW(CO)3] with 1,n-diiodoalkanes (n=3, 4) was
* Corresponding author. Current address: Department of Chem-
reported [13] to yield the hydrocarbon-bridged com-
istry, University of Louisville, Louisville, KY 40292, USA. Tel.: +1
plexes [Cp(CO)3W(CH2)nW(CO)3Cp] (n=3, 4), and the
502 8527840; fax: +1 502 8528149; e-mail: x0yin001@homer.
iodoalkyl complexes [CpW(CO)3{(CH2)nI}] (n=3 and
4) were suggested as intermediates in these reactions
louisville.edu
1 Fax: +27 21 6897499; e-mail: jrm@psipsy.uct.ac.za.
0022-328X/99/$ - see front matter © 1999 Published by Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00848-1

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
253
Scheme 1.
Scheme 2.
[13]. The intermediates could also be isolated under
suitable conditions as was demonstrated by Scott [20],
who successfully isolated [CpW(CO)3{(CH2)nI}] (n=4
and 5) but with only partial characterization. Here we
report the synthesis and full characterization of an
extensive series of haloalkyl complexes [(p5-
C5R5)W(CO)3{(CH2)nX}] (R=H, n=3–7, X=Br, I;
R=CH3, n=3, 4, X=Br and I). Furthermore, the
reactivity of these complexes leading to some bi- and
polynuclear complexes is also reported.
R=CH3, n=3, 11, 4, 12) have been prepared in good
yields by the reaction of Na[(p5-C5R5)W(CO)3] with an
excess 1,n-dibromoalkanes in THF as shown in Scheme
1. This method is similar to that reported by King and
co-workers [1] for the preparation of 1 and 2 in low
yields. Bailey and co-workers [14] have also applied this
method to prepare 11.
The reactions were monitored by IR spectroscopy,
and stopped after all the Na[(p5-C5R5)W(CO)3] was
consumed. It is found that the reaction of Na[Cp-
W(CO)3] with 1,n-dibromoalkanes at r.t. is chain-
length dependent. Thus, the longer the polymethylene
chain, the longer the reaction time required. Complexes
4 and 5 could only be prepared by refluxing the reac-
tion mixture overnight. The relatively slow reaction
rate of Na[CpW(CO)3] with 1,n-dibromoalkanes, com-
pared with that of Na[CpFe(CO)2], is due to the
weak nucleophilicity of the tungsten anion [21]. The
2. Results and discussions
2.1. Synthesis of [(p5-C5R5)W(CO)3{(CH2)nX}]
The bromoalkyl complexes [(p5-C5R5)W(CO)3
{(CH2)nBr}] (R=H, n=3, 1; 4, 2; 5, 3; 6, 4; 7, 5;

254
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Table 1
Data for [CpW(CO)3{(CH2)nX}]
Compound number
X
n
Yield (%)
M.p. (°C)
IR w(CO)a (cm−1
)
Elemental analysis (%)
C: found (calc.)
H: found (calc.)
1b
2c
3
4
5
Br
Br
Br
Br
Br
I
I
I
I
I
3
4
5
6
7
3
4
5
6
7
66
45
50
49
37
70
56
63
62
57
108–110
58–66
122–125
61–63
44–48
81–84
67–69
127–130
57–58
2020s, 1929vs
2017s, 1927vs
2017s, 1927vs
2017s, 1927vs
2017s, 1927vs
2020s, 1929vs
2018s, 1927vs
2017s, 1927vs
2017s, 1927vs
2016s, 1927vs
29.30(29.00)
31.12(30.70)
32.35(32.33)
34.08(33.83)
35.73(35.25)
26.92(26.32)
28.11(27.91)
29.97(29.46)
31.46(30.91)
32.57(32.28)
2.42(2.40)
2.75(2.77)
3.06(3.13)
3.47(3.45)
3.79(3.75)
2.21(2.21)
2.45(2.51)
2.65(2.85)
3.14(3.15)
3.44(3.43)
6
7d
8e
9
10
49–51
a IR in hexane.
b Ref. [1], m.p. 109–112°C.
c Ref. [1], m.p. 66–68°C, DSC studies showed that this complex might exist in different crystal forms (see Section 2).
d Ref. [20], m.p. 69–71°C.
e Ref. [20], m.p. 129–131°C.
trans-2-oxacyclopentylidene tungsten complexes as
shown below:
[(p5-C5R5)(CO)2IW(¸C¹O¹C¹H¹2CºH2)] (R=H, CH3)
Na[Cp*W(CO)3] is found to be more reactive than the
Cp analogs due to the increased nucleophilicity caused
by the Cp* ligand. It is also found, as expected, that the
reaction of Na[CpW(CO)3] with 1,4-diiodobutane, to
give the complex 7, is faster than its reaction with
1,4-dibromobutane.
The different products obtained from the reactions of 1
and 11 with NaI under the above reaction conditions
may thus be due to the reaction temperature.
The method, shown in Scheme 2, has been previously
used to convert bromoalkyl complexes of iron and
ruthenium to the corresponding iodoalkyl complexes
[5,6].
The iodoalkyl complexes, like the bromoalkyl com-
plexes, are yellow crystalline solids. They have similar
melting points to the corresponding bromoalkyl com-
plexes, except 6, which has a much lower melting point
than 1. The iodoalkyl complexes are more sensitive to
light and air than their bromoalkyl analogs.
Complexes 1–5, 7, 11 and 12 were obtained in good
yields as yellow crystalline solids after purification by
chromatography and recrystallization. They are moder-
ately air stable, both in solution and in the solid state
for short periods of time.
The
iodoalkyl
complexes
[(p5-C5R5)W(CO)3-
{(CH2)nI}] (R=H, n=3, 6; 5, 8; 6, 9; 7, 10; R=CH3,
n=3, 13, 4, 14) have been successfully prepared in high
yields by the reaction of the corresponding bromoalkyl
complexes with NaI in acetone at r.t. for 1–2 days, as
shown in Scheme 2. Complexes 7 and 8 were previously
prepared in this laboratory via a similar route, but were
not fully characterized [20].
2.2. Characterization of [(p5-C5R5)W(CO)3{(CH2)nX}]
The preparation of 6 and 13, from the reaction of 1
and 11 with NaI, respectively, is in contrast to reports
[12,14] that reaction of 1 and 11 with LiI in refluxing
1,2-dimethoxyethane or THF, respectively, gave the
The haloalkyl complexes (1–14) have been fully char-
acterized. The yields, melting points and IR spectra, as
well as elemental analysis data for the haloalkyl com-
Table 2
Data for [Cp*W(CO)3{(CH2)nX}]
Compound number
X
n
Yield (%)
M.p. (°C)
IR w(CO)a (cm−1
)
Elemental analysis (%)
C: found (calc.)
H: found (calc.)
11b
12
13
Br
Br
I
3
4
3
4
68
62
78
71
83–85
53–55
83–85
63–65
2007s, 1914vs
2005s, 1913vs
2006s, 1914vs
2005s, 1913vs
36.93(36.60)
38.09(37.87)
34.26(33.59)
35.30(34.84)
4.05(4.03)
4.33(4.30)
3.76(3.70)
4.00(3.96)
14
I
a IR in hexane.
b Ref. [14], m.p. 80–82°C.

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
255

256
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Table 4
1H-NMR data for [Cp*W(CO)3{(CH2)nX}] (400 MHz, CDCl3)a
Compound number
X
n
C5(CH3)5
CH2X 3J(HH)
CH2CH2X 3J(HH)
h-CH2
i-CH2
11b
12
13
Br
Br
I
3
4
3
4
1.97, 15H, s
1.97, 15H, s
1.98, 15H, s
1.96, 15H, s
3.35, 2H, t, 7.2
3.42, 2H, t, 7.2
3.16, 2H, t, 7.2
3.19, 2H, t, 7.2
2.07, 2H, m
1.91, 2H, qn, 7.2
2.04, 2H, m
0.75, 2H, m
0.79, 2H, m
0.76, 2H, m
0.78, 2H, m
1.70, 2H, m
1.66, 2H, m
14
I
1.89, 2H, qn, 7.2
a Coupling constants are given in Hz, h-CH2 refers to the protons on the CH2 h to tungsten, etc.
b These data are in good agreement with literature values [14].
plexes (1–14) are summarized in Tables 1 and 2. All the
complexes have been characterized by satisfactory C
and H analyses. The 1H- and 13C-NMR, as well as mass
spectral data are summarized in Tables 3–8.
it can be seen that the h-CH2 (h to tungsten) resonances
appear at ca. 1.5 ppm for the Cp complexes and at ca.
0.8 ppm for the Cp* complexes. No coupling between
tungsten and the h-CH2 protons is observed. The ob-
servation that the h-CH2 protons of the Cp* complexes
are more shielded than those of the Cp analogs may be
due to the increased electron density at the tungsten
center in these Cp* complexes. The CH2X (X=Br, I)
protons for complexes with n=3 are also found slightly
more shielded than the CH2X protons for complexes
with n\4. However, the CH2X and CH2CH2X protons
show no further shift on increasing the chain length
beyond n=5, suggesting that the effect of the tungsten
group on the chain end is now no longer detectable in
these complexes. Similar trends were also observed in
the haloalkyl iron complexes [5]. The up-field shift of
0.2–0.3 ppm of the CH2X resonances, as X changes
from Br to I, is as expected because of the difference in
their electronegativities, however, the effect of the halo-
gen diminishes quickly along the carbon chain.
2.2.1. IR spectroscopy
As seen in Tables 1 and 2, the IR spectra of com-
plexes 1–14 are in good agreement with the data re-
ported for some known compounds [1,14,20]. There is
no significant change in the positions of the carbonyl
bands in the IR spectra between the bromoalkyl and
corresponding iodoalkyl complexes, and there is only a
very slight trend towards lower wavenumbers as the
carbon chain lengthens from n=3 to n=5. The IR
spectra of the Cp complexes are also very similar to
those of the long chain alkyl complexes [Cp-
W(CO)3(CH2)nCH3] (n=5–9) [22]. The w(CO) for the
Cp* complexes is lower than that for the analogous Cp
complexes by ca. 13 cm−1. This is consistent with the
increase in electron density on the metal (caused by the
Cp* group), which results in increased back-bonding to
the carbonyl groups, and hence, a lower w(CO) [5].
2.2.3. 13C-NMR spectroscopy
1
2.2.2. H-NMR spectroscopy
No 13C-NMR data have previously been reported for
complexes 1–14 [1,13,20]. The data for complexes 1–14
are given in Tables 5 and 6. Assignments were made by
comparison with the 13C-NMR data reported for the
haloalkyl complexes [CpFe(CO)2{(CH2)nX}] (n=3–7,
X=Br, I) [5] and [CpW(CO)3R] (R=various alkyl
groups) [22], as well as by HETCOR experiments.
1
The H-NMR data for complexes 1–14 are summa-
1
rized in Tables 3 and 4. The H-NMR data for 11 have
been reported by Bailey et al. [14] and our results for
the same compound agree well with the reported data.
The complexes 1, 2, 7 and 8 have also been previously
1
characterized by H-NMR [1,20]. From Tables 3 and 4,
Table 5
13C-NMR chemical shift data (l ppm) for [CpW(CO)3{(CH2)nX}] (100 MHz, CDCl3)
a
Compound number
X
n
CO
Cp
CH2X
CH2CH2X h-CH2
i-CH2
k-CH2
l-CH2
m-CH2
1
2
3
4
5
6
7
8
9
Br
Br
Br
Br
Br
I
I
I
I
I
3
4
5
6
7
3
4
5
6
7
228.17, 217.36
228.53, 217.47
228.62, 217.60
228.83, 217.57
228.90, 217.55
228.15, 217.38
228.52, 217.47
228.68, 217.59
228.86, 217.57
228.91, 217.55
91.53
91.47
91.47
91.47
91.46
91.49
91.47
91.47
91.46
91.47
37.77
33.49
32.28
32.88
32.84
11.70
6.99
7.40
7.36
7.37
40.09
35.05
34.11
34.09
34.06
41.00
37.49
33.02
33.60
33.58
−14.66
−12.44
−10.91
−10.46
−10.21
−11.92
−12.61
−10.91
−10.45
−10.21
38.35
35.88
36.62
36.72
34.29
34.98
35.65
27.66
28.20
28.18
27.99
39.03
36.64
36.61
36.73
35.66
34.76
35.62
29.99
30.50
10
a h-CH2 refers to the CH2 carbon h to tungsten, etc.

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
257
Table 6
13C-NMR chemical shift data (l ppm) for [Cp*W(CO)3{(CH2)nX}] (100 MHz, CDCl3)
a
Compound number
X
n
CO
C5(CH3)5
CH2X
CH2CH2X
h-CH2
i-CH2
C5(CH3)5
11
12
13
14
Br
Br
I
3
4
3
4
232.01, 223.01
232.29, 223.10
231.97, 223.03
232.30, 223.07
102.89
102.77
102.91
102.77
38.92
33.49
13.47
6.63
39.88
35.10
40.74
37.48
−3.41
−1.02
−0.46
−1.25
10.36
10.36
10.37
10.36
39.82
40.64
I
a h-CH2 refers to the CH2 carbon h to tungsten, etc.
The chain length or the nature of the halogen have
no significant effect on the positions of the CO peaks.
Similarly, the chain length and the halogen do not
appear to affect the position of Cp or Cp* peaks very
much, although for complexes with n=3, the CO peaks
are found at a slightly higher field and the Cp or Cp*
peaks at a slightly lower field, compared with those for
complexes with n\3. The methylene h-CH2 carbons in
the Cp* complexes are significantly (ca. 10 ppm) more
deshielded than those in the corresponding Cp com-
plexes. So too are the carbonyl carbon peaks, though to
a lesser degree (ca. 4 ppm). The deshielding effect is no
longer apparent for the i-carbons of the methylene
chain.
The effect of the halogen on the l value of the h-CH2
carbon, for the complexes where n=3 and n=4, is
very apparent, and diminishes gradually with increasing
n from 5 to 7. The peak due to the h-carbon is shifted
up-field for those complexes with smaller values of n.
This is in contrast to what one would expect consider-
ing the inductive effect of the halogens. For both the
Cp and the Cp* complexes, the complexes with n=3
are of particular interest, as the peak for the h-carbon
is at a much higher field for X=Br than for X=I.
These observations could possibly be explained in terms
of a weak interaction between the halogen and tung-
sten, as has been suggested for the iron complexes
[CpFe(CO)2{(CH2)nX}] [5]. The interaction between
tungsten and halogen is also shown by the ca. 4 ppm
down-field shift of the peaks of the CH2X carbon for
n=3, relative to the corresponding peaks for com-
pounds with n=4–7. Thus as n increases, the distance
between X and tungsten increases, and the effect of
their interaction would decrease. Also apparent from
the 13C-NMR data is the large chemical shift difference
(ca. 25 ppm) between the CH2X carbons (X=Br and
I), reflecting the different electron withdrawing abilities
of the halogens.
8, with probable assignments. The assignment of peaks
in the mass spectra of these haloalkyl complexes is
complicated by the extensive isotope patterns of tung-
sten- and bromine-containing ions, which makes the
assignment potentially ambiguous.
Molecular ion peaks are observed in the spectra of all
the Cp complexes 1–10, but are of low intensity.
Molecular ions are also observed in the spectra of all
the Cp* complexes 11–14 and are of the strongest
intensities except in the spectrum of 13. This difference
is largely due to the enhanced stability for these Cp*
complexes. For the Cp complexes, all spectra show
weak peaks corresponding to loss of CO from the
parent ions, except 2, 7 and 9. All spectra also exhibit
peaks that are characteristic of the compounds contain-
ing the [CpW(CO)3] group, which gives rise to the ions
[CpW(CO)3]+ (m/z 333, represented by 184W), [Cp-
W(CO)2]+ (m/z 305), [CpW(CO)]+ (m/z 277), and
[CpW]+ (m/z 249). Similarly, [Cp*W(CO)n]+ (n=0–
3) contained peaks with low intensities are observed in
the spectra of the Cp* complexes.
The most abundant peak observed in the Cp com-
plexes 3–6 and 9 corresponds to [CpW(CO)2X]+,
whereas for complexes 1, 2, 7 and 8, the most abundant
peak corresponds to [CpWX]+. Due to the tungsten
isotopes, the most abundant peak for complex 10 could
not be assigned unambiguously, but is most likely to be
[CpW(CO)X]+. All of the most abundant peaks ob-
served include W–X fragments, which is a good indica-
tion that the interaction between the halogen and
tungsten can exist in these haloalkyl complexes, partic-
ularly after CO is lost from the molecular ion. Such
interaction could be postulated as shown in Scheme 3.
All the complexes fragment according to three main
pathways as illustrated in Scheme 4 for complex 6.
2.2.5. Thermal properties of [CpW(CO)3{(CH2)nBr}]
The thermal properties of complexes [Cp-
W(CO)3{(CH2)nBr}] (n=3, 1; and 4, 2) were studied by
DSC and TGA. The DSC traces of 1 and 2 recorded
over the range 40–300°C under nitrogen and are shown
in Fig. 1. The upper trace for 1 shows an endothermic
peak at 109°C, which corresponds to the melting of the
sample, by comparison with the hot-stage microscopy
results. The exothermic peak at 194°C corresponds to
2.2.4. Mass spectra
Low resolution electron impact mass spectra were
obtained for all the compounds under discussion. The
intensities of the major peaks of [CpW(CO)3{(CH2)nX}]
(1–10) are reported in Table 7, while those of
[Cp*W(CO)3{(CH2)nX}] (11–14) are reported in Table

258
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Table 7
Mass spectral data for [CpW(CO)3{(CH2)nX}]
Iona
Relative peak intensitiesb (%)
n=
3
4
5
6
7
X=
Br
I
Br
I
Br
I
Br
I
Br
I
M
11
15
24
7
2
0
23
31
0
73
0
23
2
0
30
5
17
100
56
0
0
55
8
74
4
17
9
20
4
0
14
5
0
28
0
81
100
56
0
84
52
0
59
13
2
5
0
0
0
0
3
4
0
0
0
49
100
62
0
79
57
0
59
24
0
9
7
0
0
0
16
69
48
MꢀCO
12
12
0
0
80
0
27
12
80
53
0
93
46
0
61
0
0
0
4
0
0
100
4
Mꢀ3COc
Mꢀ(CH2)n
MꢀHX
Mꢀ(CH2)nX
MꢀCOꢀ(CH2)n
MꢀCOꢀ(CH2)nX
MꢀCOꢀHX
Mꢀ2COꢀ(CH2)n
Mꢀ2COꢀ(CH2)nX
Mꢀ2COꢀHX
Mꢀ3COꢀ(CH2)nX
Mꢀ3COꢀHX
Mꢀ(CH2)nꢀCO2
Mꢀ(CH2)nꢀXꢀCO2
Mꢀ(CH2)nXꢀCO2ꢀCO
Mꢀ(CH2)nXꢀCO2ꢀCpH
Mꢀ(CH2)nXꢀCO2ꢀCOꢀCpH
CpWX
0
0
3
58
20
60
45
0
54
46
43
65
0
11
16
0
15
8
60
52
37
12
65
0
10
40
18
13
24
15
28
10
100
12
24
61
82
71
41
73
58
61
79
0
0
0
3
27
0
60
100
41
22
46
37
44
66
20
11
37
29
33
14
91
0
100
83
66
99
82
89
94
0
0
0
0
0
100d
100d
42
88e
46
5
0
0
0
0
2
8
0
0
81
5
0
0
0
0
56
0
13
24
6
0
9
0
93
0
0
100
0
100
0
88e
0
WX
a
M=[CpW(CO)3{(CH2)nX}]; all ions have a single positive charge; ion refers to probable assignment.
b Peak intensities are relative to the base peak at m/z 328/330 due to [CpWBr]+ (calculations based on the most abundant peaks for all ions) for
complexes X=Br, n=3 and 4, m/z 376 [CpWI]+for X=I, n=4 and 5; m/z 384/386 due to [CpW(CO)2Br]+ for complexes X=Br, n=5–7, m/z
432 due to [CpW(CO)2I]+ for complexes X=I, n=3 and 6; m/z 403 for X=I, n=7.
c No ions corresponding to Mꢀ2CO, Mꢀ2CO ꢀCp, MꢀCOꢀCp or Mꢀ3COꢀCp observed.
d These ions cannot be distinguished.
e These ions cannot be distinguished.
the decomposition of the complex. This can be seen from
the TGA results (Fig. 2), which show a significant mass
loss at this temperature.
2.2.6. Electrochemical beha6ior of some haloalkyl
complexes
The electrochemical properties of the haloalkyl com-
plexes 1, 8, and 14 were studied under argon in acetoni-
trile solution at r.t. The oxidation potentials of these
complexes are summarized in Table 9.
The DSC trace for complex 2 shows three endothermic
peaks at 62, 68 and 72°C, which by comparison with the
hot-stage microscopy results, are assigned to the melting
points of the sample. The presence of more than one peak
in the melting range of 2 suggests that this complex may
exist in several crystalline forms or phases. Further
support for this is obtained by checking the IR and
1H-NMR spectra of the sample after heating the sample
The CV measurements show that these haloalkyl and
hydroxyalkyl complexes undergo chemically irreversible
oxidation in the range 0.44–0.66 V versus the ferrocene/
ferrocenium (Fc/Fc+) couple. These results are very
similar to those obtained for [CpW(CO)3(CH2)6CH3]
[22]. This indicates that the oxidation of these haloalkyl
complexes takes place at the tungsten center and is
independent of the halo group. The complex with the
Cp* ligand, 14, was oxidized at a much less positive
potential than similar complexes containing the Cp
ligand, which is a direct indication that the tungsten
center in the Cp* complex is more electron rich than in
the Cp complexes. This is due to the strong electron
donating effect of the Cp* ligand. Similar studies on the
iron complexes [CpFe(CO)2(CH2)5CH3] and [CpFe
(CO)2{(CH2)6Br}] have shown [10] that their electro-
chemical behavior and redox potentials are affected
neither by the hydrocarbon chain length nor by the
1
to melting under nitrogen. Thus, the IR and H-NMR
spectra of the melted sample are the same as the IR and
1H-NMR spectra of the pre-heated sample, although the
color of the melted sample is slightly darker. In addition,
the TGA also shows no decomposition over the range
40–190°C. The exothermic peak at 213°C on the DSC
trace of 2 is assigned to the decomposition of the
complex. This is seen from the TGA results, which show
a significant mass loss at this temperature.
The decomposition temperature for 2 is ca. 10°C
higher than that of 1. This could be due to the alkyl chain
length and the interaction between the tungsten and
halogen as discussed in previous sections.

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
259
Table 8
3,5-dihydroxybenzyl alcohol in refluxing acetone for 3
days, in the presence of K2CO3 and 18-crown-6, gave
predominately the bis-substituted product 15, (51%
yield) and a small amount of the mono-substituted
product 16, (3%). Both complexes were obtained as
yellow solids after purification by column chromatogra-
phy and recrystallization (Scheme 5).
The reaction of [CpW(CO)3(CH2)4I], 7 with 3,5-dihy-
droxybenzyl alcohol was carried out similarly in reflux-
ing acetone for 2 days, but gave only a low yield (24%)
of the bis-substituted product, 17.
Mass spectral data for [Cp*W(CO)3{(CH2)nX}]
Iona
Relative intensityb (%)
n=
X= Br
100
3
4
I
Br
I
M
MꢀCO
Mꢀ2CO
Mꢀ3CO
MꢀHX
Mꢀ(CH2)n
Mꢀ(CH2)nX
MꢀCOꢀ(CH2)n
MꢀCOꢀHX
MꢀCOꢀ(CH2)nX
Mꢀ2COꢀ(CH2)n
Mꢀ2COꢀHX
Mꢀ2COꢀ(CH2)nX
Mꢀ3COꢀHX
Mꢀ3COꢀ(CH2)nX
Cp*WX
48
34
8
10
0
11
45
0
100
0
99
1
46
17
0
10
3
2c
0
1d
100e
6
0
Two bands are observed in the IR spectra of 15–17
at similar positions to those observed for the corre-
sponding haloalkyl complexes. This suggests that the
2c
0
1d
0
0
0
0
100e
0
1
44
18
0
78
100
0
0
11
0
0
metal center is not affected by the reaction. The H-
0
84
0
8
0
NMR spectra of 15–17 show a CH2O proton triplet
peaks at ca. l 3.9 ppm, which confirms the conversion
from the haloalkyl to the anticipated products. The
complexes 15 and 16 can be easily distinguished by
observation of the aromatic proton resonances and by
integration, and also by observation of the phenolic
0
0
67
27
38
0
73
79
19
20
11
0
13
0
10
7
1
OH proton peak at 4.7 ppm in the H-NMR spectrum
a M=[Cp*W(CO)3{(CH2)nX}]; all ions have a single positive charge;
ion refers to probable assignment.
of 16. Three separate proton resonances with equal
b Peak intensities are relative to the parent peak for complexes with
n=3, 4 and X=Br, relative to [Cp*W(CO)2] for n=3, X=I, and
relative to [Cp*W(CH2)4I] for n=4, X=I.
integration are observed, in the region 6.2–6.4 ppm, in
1
the H-NMR spectrum of 16, due to the inequivalence
of these aromatic protons in the mononuclear complex.
c These ions cannot be distinguished.
Two separate proton peaks with integration of 2:1 due
d These ions cannot be distinguished.
1
to the aromatic protons are observed in the H-NMR
e These ions cannot be distinguished.
spectrum of 15. Elemental analysis results confirm the
formulae of the proposed complexes 15 and 16.
groups. Given the fact that these tungsten complexes
show similar chemistry in a range of reactions to that of
the iron complexes [10], it is expected that the electro-
chemical behavior of these tungsten complexes [Cp-
W(CO)3{(CH2)nX}] is not likely to be affected by the
alkyl chain length or the nature of the functional
groups.
The thermal properties of 15 and 16 have also been
studied. It is found that the mononuclear complex 16 is
less thermally stable than the binuclear complex 15.
The melting points [DSC Tmax(endo)] for 15 and 16 are
171 and 152°C, respectively, in agreement with the
melting points observed on the hot-stage microscope.
The decomposition points [DSC Tmax(exo)] measured
for 15 and 16 are 203 and 190°C, respectively.
2.3. Reacti6ity of [CpW(CO)3{(CH2)nX}]
2.3.2. Reaction of [CpW(CO)3{(CH2)3Br}], 1 with
1,1,1-tris(4%-hydroxyphenyl)ethane
2.3.1. Reaction of [CpW(CO)3{(CH2)3Br}], 1 and
[CpW(CO)3{(CH2)4I}], 7 with 3,5-dihydroxybenzyl
alcohol
The reaction of [CpRu(CO)2{(CH2)3Br}] with 3,5-di-
hydroxybenzyl alcohol has been reported as the first
step for the preparation of large ruthenium dendrimers
[18,19]. We have carried out similar reactions with
tungsten haloalkyl complexes. The reaction of 1 with
The reaction of
1
with 1,1,1-tris(4%-hydrox-
yphenyl)ethane was also carried out in refluxing ace-
tone for 3 days, in the presence of K2CO3 and
18-crown-6, which gave the product 18 as shown below
in good yield (61%).
Scheme 3.

260
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Scheme 4.
Complex 18 has been characterized by elemental
and Rh. Thus, the reaction of [CpW(CO)3{(CH2)4I}]
and [RhCl2(DH2)(DH)] in the presence of NaBH4 was
conducted in a mixed solvent system of methanol/wa-
ter/KOH/pyridine. After the reaction, none of the an-
ticipated heterobimetallic complex could be observed.
However, a yellow product was isolated in low yield
(13%) in addition to some unreacted starting tungsten
complex. This yellow product was identified as a new
tungsten complex [CpW(CO)3{(CH2)4OCH3}], 20, by
1
analysis, IR, H- and 13C-NMR. The IR spectrum of
18 shows two w(CO) bands at 2012 and 1913 cm−1
,
very similar to those observed in the IR spectra of
1
15–17. The H-NMR spectrum of 18 shows a triplet
at l 3.85 ppm that corresponds to the CH2 attached
to a phenoxy group. The integration of the protons
also indicates the formula of the product being as
anticipated.
1
elemental analysis, IR, H- and 13C-NMR as well as
2.3.3. Con6ersion of 15 to the benzyl bromide complex
19
mass spectroscopy. Parent ions (m/z 422) are ob-
served in the mass spectrum of 20.
The benzyl alcohol complex 15 was reacted with
CBr4 and PPh3 in THF at r.t. After purification by
column chromatography and recrystallization, the
benzyl bromide complex 19 was obtained in low yield
(10%). This is in contrast to the similar reactions car-
ried out for the iron and ruthenium complexes
[10,17,18], which generally give benzyl bromide com-
plexes in high yields (70–90%). This is likely to be
due to the different metal employed. The complex 19
Attempts were also made to prepare heterobinu-
clear complexes of W and Pt by the reaction of [Cp-
W(CO)3{(CH2)4I}] with [Pt(CH2ꢁCH2)(PPh3)2], but
these were unsuccessful. However, the reaction of
[(p5-C5R5)W(CO)3{(CH2)nI}] with [PtMe2(R2-bipy)]
(R=H, CH3) gave rise to a series of new heterobinu-
clear W/Pt complexes that have been reported else-
where [17].
1
has also been characterized by IR and H-NMR. The
IR spectrum of 19 shows the same bands as those for
complex 15. The 1H-NMR spectrum of 19 shows a
characteristic single peak at l 4.39 ppm, while all
other peaks are found at the same positions as those
in the H-NMR spectrum of 15, which indicates the
conversion of 15 to the anticipated product (Scheme
3. Conclusion
A
series
of
ꢀ-haloalkyl
complexes
[(p5-
1
C5R5)W(CO)3{(CH2)nX}] (R=H, n=3–7, X=Br
and I; R=CH3, n=3, 4, X=Br and I) has been
synthesized and fully characterized. The characteriza-
tion data obtained for these haloalkyl complexes sup-
port previous observations by other workers that
there is an interaction between the metal and the k-
CꢀX bond in halopropyl transition metal complexes.
The haloalkyl complexes have been used as precursors
for the synthesis of binuclear and polynuclear com-
plexes.
6).
2.3.4. Attempted preparation of a heterobimetallic
complex containing W and Rh
A procedure reported [23] for the preparation of
[RhR(DH)2(py)] from [RhCl2(DH2)(DH)] and RX, in
the presence of NaBH4, was followed in an attempt
to prepare a heterobimetallic complex containing W

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
261
Fig. 1. DSC traces for the complexes 1 and 2 (scan rate=20°C min−1).
atmosphere with a heating rate of 10 or 20°C min−1
.
4. Experimental
Microanalyses were performed by the University of
Cape Town Microanalytical Laboratory. IR spectra
were recorded either on a Perkin-Elmer 983 or a
Paragon 1000 FT-IR spectrophotometer in solution
cells with NaCl windows.
All reactions were carried out under an atmosphere
of high purity nitrogen using standard Schlenk tube
techniques. Tetrahydrofuran (THF) and hexane were
dried by distilling over sodium/benezophonone.
Dichloromethane (CH2Cl2) was distilled over anhy-
drous CaCl2. Acetone was distilled over anhydrous
CaCl2 or K2CO3. Acetonitrile was distilled over P2O5.
Pyridine was dried over sodium hydroxide pellets.
Methanol (MeOH) was distilled over molecular sieve
(3A or 4A). [CpW(CO)3]2 was obtained from Strem
Chemical, USA and was used without further purifica-
tion. The complexes [Cp*W(CO)3]2 [24], 3,5-dihydroxy-
benzyl alcohol [25], and [RhCl2(DH2)(DH)] [23] were
prepared by literature methods. Alumina (BDH, active
neutral, Brockman grade I) was deactivated before use.
The dihaloalkanes (Aldrich) were used without purifica-
tion.
1H-NMR spectra were recorded on a Varian XR 200
(at 200 MHz) spectrometer or a Varian Unity 400 (at
400 MHz) spectrometer. 13C-NMR spectra were
recorded on the Varian XR 200 (at 50 MHz) spectro-
meter or the Varian Unity 400 (at 100 MHz) spectrom-
eter. The chemical shifts are relative to TMS (0 ppm) in
1
the H- and 13C-NMR spectra, whereas the deuterated
solvent signals were used as references and the chemical
shifts adjusted accordingly. Low resolution mass spec-
tra were recorded with a VG Micromass 16F spectrom-
eter operated at 70 eV ionizing voltage and using an
accelerating voltage of 4 kV.
Cyclic voltammetry (CV) was carried out on a BAS-
100B electrochemical analyser in a one-compartment
three-electrode system, consisting of Ag/Ag+(0.01 M)
as the reference electrode, platinum wire as the auxil-
iary electrode and a platinum disk electrode as the
working electrode. The supporting electrolyte was a
Melting points were recorded on a Kofler hot-stage
microscope (Reichert Thermovar) and are uncorrected.
Differential scanning calorimetry (DSC) and thermal
gravimetric analysis (TGA) were performed on a
Perkin-Elmer PC Series 7 instrument under a nitrogen

262
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Fig. 2. TGA traces for the complexes 1 and 2 (scan rate=20°C min−1).
solution of 0.1 M [NBun4][ClO4] in dry acetonitrile. The
potentials E were recorded without IR compensation.
All potentials reported are relative to the half-wave
potential E1/2 of the ferrocene/ferrocenium couple run
under the same conditions. The experiments were per-
formed on 1.0 mM solutions under an argon atmo-
sphere at r.t. The platinum disk electrode was polished
after every three runs.
mmol) in THF (2 ml) with stirring at r.t. The reaction
mixture was stirred for 44 h at r.t. to effect completion.
The reaction was monitored by IR spectroscopy, based
on the decrease of the w(CO) bands of the anion
[CpW(CO)3]− at 1894, 1790 and 1744 cm−1. The sol-
vent was removed under reduced pressure and the
residue was extracted with CH2Cl2 (3×30 ml), filtered
and the solvent removed. The residue was dissolved in
a minimum amount of 10% CH2Cl2/hexane, then sepa-
rated on an alumina column. Elution with hexane gave
a yellow band which was concentrated, and cooled to
−78°C to yield yellow crystals of the pure product 1
(0.90 g, 66%). The melting point, elemental analysis and
physical characterization data of 1 (and others 2–14)
are given in the Section 2.
4.1. Synthesis of haloalkyl complexes
[(p5-C5R5)W(CO)3{(CH2)nX}]
The preparation of complexes [CpW(CO)3-
{(CH2)3Br}] [1], [CpW(CO)3{(CH2)4Br}] [1], [Cp*W-
(CO)3{(CH2)3Br}] [14], [CpW(CO)3{(CH2)4I}] [20] and
[CpW(CO)3{(CH2)5I}] [20] has been reported in the
literature, however, the procedures given here lead to
better yields for these complexes. All other complexes
synthesized in this work are new complexes.
4.1.2. Preparation of [CpW(CO)3{(CH2)4Br}], 2 [1]
This was prepared by the method described above for
1 with the following quantities of reagents: [Cp-
W(CO)3]2, (0.57 g, 0.85 mmol), 1,4-dibromobutane
(1.10 g, 4.9 mmol), and a reaction time of 114 h at r.t.
Work-up as described above for 1, gave 2 as yellow
crystals (0.36 g, 45%).
4.1.1. Synthesis of [CpW(CO)3{(CH2)3Br}], 1 [1]
A solution of Na[CpW(CO)3] (3.0 mmol), generated
from [CpW(CO)3]2 (1.00 g, 1.5 mmol) over Na/Hg (0.40
g Na, 4 ml Hg) in THF (20 ml) at r.t., was added
dropwise over 5 min to 1,3-dibromopropane (1.20 g, 6.0

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
263
Table 9
Oxidation potentials for haloalkyl and hydroxyalkyl complexes measured under argon in 1.0 mM acetonitrile solution containing 0.1 M
[NBun4]ClO4 at r.t.
Compound
Ea (V vs. Fc/Fc+
)
Scan rate (mV s−1
)
Nunber of measurements
1
8
14
0.66
0.63
0.44
0.56
0.61
500
100
100
200
100
2
3
3
3
3
[Wp(CH2)6CH3]a
[Wp(CH2)6CH3]a
a Results from [22].
4.1.3. Preparation of [CpW(CO)3{(CH2)5Br}], 3
This was prepared by the method described above for
1 with the following quantities of reagents: [Cp-
W(CO)3]2, (0.80 g, 1.2 mmol), 1,5-dibromopentane
(1.04 g, 4.5 mmol), and a reaction time of 10 days at r.t.
Work-up as described above for 1, gave 3 as yellow
crystals (0.60 g, 50%).
3.5 mmol), and a reaction time of 6 h at r.t. Work-up
as described above for 1, and recrystallization from
hexane at −20°C gave 7 as yellow crystals (0.87 g,
56%).
4.1.8. Preparation of [CpW(CO)3{(CH2)5I}], 8 [20]
This was prepared by the method described above for
6 with the following quantities of reagents: 3 (0.30 g,
0.62 mmol), NaI (0.30 g, 1.8 mmol), and a reaction
time of 30 h. Work-up as described above for 6, and
recrystallization from acetone/hexane at −20°C for 4
days gave 8 as yellow crystals (0.21 g, 63%).
4.1.4. Preparation of [CpW(CO)3{(CH2)6Br}], 4
This was prepared by the method described above for
1 with the following quantities of reagents: [Cp-
W(CO)3]2, (0.45 g, 0.68 mmol), 1,6-dibromohexane
(0.38 g, 1.56 mmol), and a reaction time of 16 h under
refluxing condition. Work-up as described above for 1,
elution with hexane and gradually increasing the polar-
ity by addition of diether ether, and recrystallization
from hexane at −20°C, gave 4 as yellow crystals (0.33
g, 49%).
4.1.9. Preparation of [CpW(CO)3{(CH2)6I}], 9
This was prepared by the method described above for
6, with the following quantities of reagents: 4 (0.17 g,
0.35 mmol), NaI (0.12 g, 0.8 mmol), and a reaction
time of 36 h. Work-up as described above for 6, and
recrystallization from hexane at −20°C gave 9 as
yellow crystals (0.12 g, 62%).
4.1.5. Preparation of [CpW(CO)3{(CH2)7Br}], 5
This was prepared by the method described above for
4 with the following quantities of reagents: [Cp-
W(CO)3]2, (0.50 g, 0.75 mmol), 1,7-dibromoheptane
(0.46 g, 1.78 mmol), and a reaction time of 16 h under
refluxing condition. Work-up as described above for 4
and recrystallization from hexane at −78°C, gave 5 as
yellow crystals (0.28 g, 37%).
4.1.10. Preparation of [CpW(CO)3{(CH2)7I}], 10
This was prepared by the method described above for
6 with the following quantities of reagents: 5 (0.15 g,
0.30 mmol), NaI (0.11 g, 0.7 mmol), and a reaction
time of 36 h. Work-up as described above for 6, and
recrystallization from hexane at −78°C gave 10 as
yellow crystals (0.09 g, 57%).
4.1.6. Preparation of [CpW(CO)3{(CH2)3I}], 6
4.1.11. Preparation of [Cp*W(CO)3{(CH2)3Br}], 11
[14]
Sodium iodide (0.10 g, 0.68 mmol) was added to a
solution of 1 (0.16 g, 0.34 mmol) in acetone (10 ml).
The mixture was stirred at r.t. for 27 h. The solvent was
removed under reduced pressure and the residue ex-
tracted with hexane. The combined extracts were
filtered, concentrated and transferred to an alumina
column. Elution with hexane gave a yellow band, which
was concentrated, filtered and recrystallized from hex-
ane at −20°C. The product 6 (0.12 g, 70%) was
obtained as yellow crystals.
A solution of Na[Cp*W(CO)3] {0.64 mmol, gener-
ated from [Cp*W(CO)3]2 (0.26 g, 0.32 mmol) over
Na/Hg (0.16 g Na, 2 ml Hg) in THF (15 ml) at r.t. for
1 h}, was added dropwise to a solution of 1,3-dibromo-
propane (0.26 g, 1.28 mmol) in THF (2 ml) at 0°C with
rapid stirring. The reaction mixture was stirred for 18 h
at r.t.. After this, the solvent was removed under re-
duced pressure, leaving a yellow residue. This was
extracted with diether ether, concentrated and chro-
matographed on an alumina column. Elution with hex-
ane gave a fast-moving yellow band, which was
collected. The solvent was removed to give a yellow oily
product. Recrystallization from pentane at −78°C
gave 11 as a yellow crystalline solid (0.23 g, 68%).
4.1.7. Preparation of [CpW(CO)3{(CH2)4I}], 7 [20]
This was prepared by the method described above for
1 with the following quantities of reagents: [Cp-
W(CO)3]2, (1.00 g, 1.5 mmol), 1,4-diiodobutane (1.10 g,

264
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
Scheme 5.
4.1.12. Preparation of [Cp*W(CO)3{(CH2)4Br}], 12
This was prepared similarly as above from
[Cp*W(CO)3]2 (0.48 g, 0.60 mmol) and 1,4-dibromobu-
tane (0.39 g, 1.8 mmol), and a reaction time of 18 h.
Recrystallization from hexane at −78°C gave 12 as a
yellow crystalline solid (0.40 g, 62%).
minium foil and monitored by TLC (alumina, 30%
CH2Cl2/hexane). The reaction mixture was then al-
lowed to cool and the solvent removed under reduced
pressure, leaving a yellow-orange residue. The residue
was extracted with CH2Cl2 three times. The combined
extracts were filtered, concentrated and then transferred
to an alumina column. The first yellow band was eluted
with 70% CH2Cl2/hexane, which gave presumably unre-
acted starting material in very small amount. Eluting
with CH2Cl2 and gradually increasing the polarity to
10% MeOH/CH2Cl2 gave additional two yellow bands.
The major band was collected, and the solvent was
removed, giving a yellow solid product. The yellow
product was then recrystallized from CH2Cl2/hexane to
give the yellow crystalline product 15, (1.02 g, 51%
based on 3,5-dihydroxybenzyl alcohol); m.p. 155–
157°C (Found: C, 38.97; H, 3.14%; C29H28O9W2 re-
quires: C, 39.21; H, 3.18%), IR w(CO) (CH2Cl2): 2013s,
4.1.13. Preparation of [Cp*W(CO)3{(CH2)3I}], 13
This was prepared by the method described previ-
ously for the preparation of 6 with the following quan-
tities of reagents: 11 (0.17 g, 0.32 mmol), NaI (0.14 g,
0.93 mmol) and a reaction time of 45 h. Recrystalliza-
tion from hexane at −78°C gave 13 as yellow crystals
(0.15 g, 78%).
4.1.14. Preparation of [Cp*W(CO)3{(CH2)4I}], 14
This was prepared by the method described for the
preparation of 13 with the following quantities of
reagents: 12 (0.25 g, 0.46 mmol), NaI (0.26 g, 1.7 mmol)
and a reaction time of 42 h. Recrystallization from
hexane at −78°C gave 14 as yellow crystals (0.19 g,
71%).
1
1913s cm−1; H-NMR (CDCl3) l (ppm): 6.49 (2 H, d,
4
4J(HH) 2.4 Hz, aromatic), 6.37 (1 H, t, J(HH) 2.4 Hz,
aromatic), 5.41 (10 H, s, Cp), 4.61 (2 H, s, CH2OH),
3
3.86 (4 H, t, J(HH) 6.4 Hz, CH2OAr), 2.01 (4 H, m,
CH2CH2CH2), 1.56 (4 H, m, WCH2); 13C-NMR
(CDCl3) l (ppm): 228.57, 217.37 (CO), 160.52, 143.19,
105.10, 100.52 (Ar), 91.57 (Cp), 71.96 (CH2OAr), 65.48
(CH2OH), 36.22 (CH2CH2CH2), −16.43 (WCH2). The
minor yellow band was also collected, which after
removing solvent and recrystallization from CH2Cl2/
hexane, gave another yellow product 16 (0.071 g, 3%);
m.p. 141–144°C (Found: C, 41.75; H, 3.51%;
C18H18O6W requires: C, 42.05; H, 3.53%), IR w(CO)
4.2. Reacti6ity of haloalkyl complexes
4.2.1. Reaction of [CpW(CO)3{(CH2)3Br}], 1 with
3,5-dihydroxybenzyl alcohol to gi6e the benzyl alcohol
complexes [{CpW(CO)3(CH2)3Oꢀ}2(C6H3)ꢀCH2OH],
15 and [{CpW(CO)3(CH2)3Oꢀ}{C6H3(OH)}ꢀCH2OH],
16
A mixture of 1 (2.05 g, 4.52 mmol), 3,5-dihydroxy-
benzyl alcohol (0.31 g, 2.2 mmol), 18-crown-6 (0.116 g,
0.45 mmol) and K2CO3 (0.91 g, 6.6 mmol) in acetone
(70 ml) was heated to reflux and stirred vigorously for
67 h. The reaction was protected from light by alu-
(CH2Cl2): 2013s, 1911s cm−1
;
1H-NMR (CDCl3) l
4
(ppm): 6.49 (1 H, d, J(HH) 2.4 Hz, aromatic), 6.42 (1
H, m, aromatic) 6.31 (1 H, t, 4J(HH) 2.4 Hz, aromatic),
5.41 (5 H, s, Cp), 4.92 (1 H, s, ArOH), 4.60 (2 H, s,

X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
265
Scheme 6.
CH2OH), 3.85 (2 H, t, 3J(HH) 6.4 Hz, CH2OAr),
4.2.4. Con6ersion of the benzyl alcohol complex 15 to
2.01 (2 H, m, CH2CH2CH2), 1.56 (2 H, m, WCH2),
1.25 (1 H, s, CH2OH).
the benzyl bromide complex [{CpW(CO)3(CH2)3Oꢀ}2
(C6H3)ꢀCH2Br], 19
To a solution of 15 (0.13 g 0.15 mmol) in THF (2 ml)
PPh3 (0.05g, 0.19 mmol) and CBr4 (0.06 g, 0.19 mmol)
were added. The reaction mixture was stirred for 15
min at r.t. Additional PPh3 (0.05g, 0.19 mmol) and
CBr4 (0.06 g, 0.19 mmol) were added to the reaction
mixture and the reaction continued for another 25 min.
Monitoring the reaction by TLC showed that complete
conversion of the starting complex had occurred. Dis-
tilled water (10 ml) was added to quench the reaction.
The resulting mixture was extracted twice with CH2Cl2
and the combined extracts were dried (Mg2SO4), con-
centrated and transferred to an alumina column. The
first yellow band, eluted with 30% CH2Cl2/hexane, was
very unstable and turned black soon after it was eluted.
The second yellow band gave an oily solid. Recrystal-
lization from CH2Cl2/hexane and drying under high
vacuum gave 19 (0.014 g, 10%) as a yellow-brown solid,
m.p. 96–105°C (Found: C, 37.48; H, 3.12%;
C29H28O8BrW2 requires: C, 36.62; H, 2.86%), IR w(CO)
4.2.2. Reaction of [CpW(CO)3{(CH2)4I}], 7 with
3,5-dihydroxybenzyl alcohol to gi6e
[{CpW(CO)3(CH2)4Oꢀ}2(C6H3)ꢀCH2OH], 17
A mixture of 7 (0.13 g, 0.26 mmol), 3,5-dihydroxy-
benzyl alcohol (0.018 g, 0.13 mmol), 18-crown-6 (0.01
g, 0.04 mmol) and K2CO3 (0.09 g, 0.66 mmol) in
acetone (20 ml) was heated to reflux and stirred vig-
orously for 48 h. Work-up as described above for 15
gave the complex 17 (0.029 g, 24%) as a yellow solid;
IR w(CO) (CH2Cl2): 2011s, 1911s cm−1
;
1H-NMR
4
(CDCl3) l (ppm): 6.51 (2 H, d, J(HH) 2.4 Hz, aro-
4
matic), 6.38 (1 H, t, J(HH) 2.4 Hz, aromatic), 5.38
(10 H, s, Cp), 4.62 (2 H, s, CH2OH), 3.96 (4 H, t,
3J(HH) 6.4 Hz, CH2OAr), 1.76 (8 H, m,
CH2CH2CH2CH2), 1.56 (4 H, m, WCH2), 1.25 (1 H,
s, CH2OH); 13C-NMR (CDCl3) l (ppm): 228.79,
217.51 (CO), 160.52, 143.17, 105.15, 100.68 (Ar),
91.49 (Cp), 67.29 (CH2OAr), 65.47 (CH2OH), 35.03,
33.08 (CH2CH2CH2CH2), −11.24 (WCH2). Satisfac-
tory elemental analysis results were not obtained for
this compound.
(CH2Cl2): 2013s, 1913s cm−1
;
1H-NMR (CDCl3) l
4
(ppm): 6.49 (2 H, d, J(HH) 2.4 Hz, aromatic), 6.35 (1
H, t, J(HH) 2.4 Hz, aromatic), 5.40 (10 H, s, Cp), 4.39
4
(2 H, s, CH2Br), 3.85 (4 H, t, 3J(HH) 6.4 Hz, CH2OAr),
2.00 (4 H, m, CH2CH2CH2), 1.55 (4 H, m, WCH2).
4.2.3. Reaction of [CpW(CO)3{(CH2)3Br}], 1 with
1,1,1-tris(4%-hydroxyphenyl)ethane to gi6e the
tri-nuclear tungsten complex
4.2.5. Attempted reaction of [RhCl2(DH2)(DH)] with
[CpW(CO)3{(CH2)4I}], 7: isolation of
[{CpW(CO)3(CH2)3Oꢀ(C6H4)}3ꢀCCH3], 18
[CpW(CO)3{(CH2)4OCH3}], 20
A mixture of 1 (0.26 g, 0.57 mmol), 1,1,1-tris(4%-hy-
droxyphenyl)ethane (0.052 g, 0.17 mmol), 18-crown-6
(0.012 g, 0.05 mmol) and K2CO3 (0.15 g, 1.1 mmol)
in acetone (20 ml) was heated to reflux and stirred
vigorously for 72 h. Work-up as described above for
15 gave 18 (0.050 g, 61%); m.p. 85–88°C (Found: C,
44.86; H, 4.03%; C53H48O12W3 requires: C, 44.56; H,
This procedure is similar to that reported for the
synthesis of [RhR(DH)2(py)] [23]. [RhCl2(DH2)(DH)]
(0.12 g, 0.30 mmol) was suspended in MeOH (18 ml).
The suspension was treated with 50% aqueous KOH
solution (3 ml) at r.t. followed by a solution of NaBH4
(0.012 g, 0.30 mmol) in MeOH (2 ml). An immediate
color change from yellow to black indicated that the
reduction of Rh(III) to Rh(I) had occurred. After 30
min, 7 (0.165 g, 0.32 mmol) was added to the Rh(I)
solution at r.t.. The color of the reaction mixture
gradually turned to yellow. After 30 min, pyridine (0.03
g, 0.38 mmol) was added to the mixture and the
solution stirred for further 40 min. The solvent was
removed under reduced pressure, leaving a yellow oil.
The oil was dissolved in CH2Cl2 and the solution
washed with water and NH4Cl solution. The organic
3.39%), IR w(CO) (CH2Cl2): 2012s, 1913s cm−1; H-
1
NMR (CDCl3) l (ppm): 6.96 (6 H, d, 3J(HH) 8.8
3
Hz), 6.75 (6H, d, J(HH) 8.8 Hz), 5.40 (15 H, s, Cp),
3
3.85 (6 H, t, J(HH) 6.4 Hz), 2.09 (3 H, s, CH3), 2.00
(6 H, m, CH2CH2CH2), 1.57 (6 H, m, WCH2); 13C-
NMR (CDCl3) l (ppm): 228.49, 217.21 (CO), 157.02,
141.66, 129.54, 113.61 (Ar), 91.48 (Cp), 71.80
(CH2O), 50.55 (CCH3), 36.27 (WCH2CH2), 30.73
(CCH3), −16.36 (WCH2).

266
X. Yin, J.R. Moss / Journal of Organometallic Chemistry 574 (1999) 252–266
[4] J.R. Moss, S. Pelling, J. Organomet. Chem. 236 (1982) 221.
[5] H.B. Friedrich, P.A. Makhesha, J.R. Moss, B.K. Williamson, J.
Organomet. Chem. 384 (1990) 325.
[6] H.B. Friedrich, K.P. Finch, M.A. Gafoor, J.R. Moss, Inorg.
Chim. Acta 206 (1993) 225.
[7] S. Pelling, C. Botha, J.R. Moss, J. Chem. Soc. Dalton Trans.
(1983) 1495.
[8] H.B. Friedrich, J.R. Moss, J. Organomet. Chem. 453 (1993) 85.
[9] J.R. Moss, M.L. Niven, P.M. Stretch, Inorg. Chim. Acta 119
(1986) 177.
[10] Y.-H. Liao, Ph.D. Thesis, University of Cape Town, South
Africa, 1994.
[11] J.R. Moss, Trends Organomet. Chem. 1 (1994) 211.
[12] N.A. Bailey, P.L. Chell, C.P. Manuel, A. Mukhopadhyay, D.
Rogers, H.E. Tabbron, M.J. Winter, J. Chem. Soc. Dalton
Trans. (1983) 2397.
[13] H. Adams, N.A. Bailey, M.J. Winter, J. Chem. Soc. Dalton
Trans. (1984) 273.
[14] N.A. Bailey, D.A. Dunn, C.N. Foxcroft, G.R. Harrison, M.J.
Winter, S. Woodward, J. Chem. Soc. Dalton Trans. (1988) 1449.
[15] H.B. Friedrich, J.R. Moss, B.K. Williamson, J. Organomet.
Chem. 394 (1990) 313.
layer was separated, the aqueous layer was washed once
with CH2Cl2. The combined CH2Cl2 solution was dried
(Mg2SO4), concentrated and dried, to give a yellow
solid. This solid was further purified by chromatogra-
phy on an alumina column, eluted with hexane then
gradually increase the polarity by slow adding ether.
The first yellow fraction was unreacted starting material
[CpW(CO)3{(CH2)4I}], based on its TLC and IR. The
second yellow band, after recrystallization from hexane,
gave 20 (0.032 g, 25%), m.p. 59–60°C (Found: C,
37.77; H, 3.91%; EI-MS, m/z 422 (M+), C13H16O4W
requires: C, 37.17; H, 3.84%; M, 420), IR w(CO) (hex-
1
ane): 2016s, 1926vs cm−1; H-NMR (CDCl3) l (ppm):
3
5.39 (5 H, s, Cp), 3.38 (2 H, t, J(HH) 6.4, CH2O), 3.34
(3 H, s, CH3O), 1.58 (6 H, m, WCH2CH2CH2). 13C-
NMR (CDCl3) l (ppm): 228.91, 217.45 (CO), 91.47
(Cp), 72.27 (CH2O), 58.49 (CH3O), 35.60, 33.30
(CH2CH2CH2CH2), −10.69 (WCH2).
[16] S.F. Mapolie, Ph.D. Thesis, University of Cape Town, South
Africa, 1988.
[17] X. Yin, J.R. Moss, J. Organomet. Chem. 557 (1998) 259.
[18] Y.-H. Liao, J.R. Moss, J. Chem. Soc. Chem. Commun. (1993)
1774.
[19] Y.-H. Liao, J.R. Moss, Organometallics 14 (1995) 2130; 15
(1996) 4307.
[20] L.G. Scott, M.Sc. Thesis, University of Cape Town, South
Africa, 1984.
[21] R.E. Dessy, R.L. Pohl, R.B. King, J. Am. Chem. Soc. 88 (1966)
5121.
Acknowledgements
We thank the University of Cape Town, SASOL and
the Foundation for Research and Development for
support and Johnson Matthey for the generous loan of
platinum metal salts. We also thank Dr A.T. Hutton
for assisting with the electrochemical measurements.
[22] X. Yin, Ph.D. Thesis, University of Cape Town, South Africa,
1997.
[23] B. Giese, J. Hartung, C. Kesselheim, H.J. Lindner, I. Svoboda,
Chem. Ber. 126 (1993) 1193.
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