Syntheses and structures of molybdenum and tungsten pentabenzylcyclopentadienyl complexes: New chlorination reactions

Article abstract of DOI:10.1016/j.jorganchem.2004.04.027

[M(CpBz)(CO)₃CH₃] (M=Mo, 2a, W, 2b; CpBz=C₅(CH₂Ph)₅) have been prepared and reacted with PCl₅ and PhI · Cl₂. Depending on the metal and on the chlorinating reagent used [Mo(CpBz)

Full text of DOI:10.1016/j.jorganchem.2004.04.027

Journal of Organometallic Chemistry 689 (2004) 2368–2376
www.elsevier.com/locate/jorganchem
Syntheses and structures of molybdenum and tungsten
pentabenzylcyclopentadienyl complexes: new chlorination reactions
*
Ana M. Martins , Rita Branquinho, Jinlan Cui, Alberto R. Dias, M. Teresa Duarte,
ꢀ
Jose Fernandes, Sandra S. Rodrigues
Centro de Quꢀımica Estrutural, Instituto Superior Tꢀecnico, Av. Rovisco Pais no. 1, 1049-001 Lisboa, Portugal
Received 30 January 2004; accepted 21 April 2004
Abstract
[M(CpBz)(CO)3CH3] (M ¼ Mo, 2a, W, 2b; CpBz ¼ C5(CH2Ph)5) have been prepared and reacted with PCl5 and PhI ꢀ Cl2. De-
pending on the metal and on the chlorinating reagent used [Mo(CpBz)(g2-COCH3)Cl3], 3, [W(CpBz)Cl4], 4, [Mo(CpBz)(CO)3Cl], 5
and [Mo(CpBz)Cl4], 6 have been obtained. The molecular structures of all compounds are reported and two conformations have
been characterised for the benzyl substituents. In complexes 2a, 2b and 5 one phenyl ring bends towards the metals while in 3 and 4
the five phenyls point opposite to the metals.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Molybdenum; Tungsten; Pentabenzylcyclopentadienyl; Oxidation; Chlorination; Carbonyl insertion
1. Introduction
2. Results and discussion
Bulky and polyfunctional cyclopentadienyl ligands
have been widely used as support of transition metal
complexes since they provide extra thermodynamic sta-
bility and kinetic control. Due to stereochemical pecu-
liarities, bulky ligands shield the metal centres and make
possible the stabilisation of unusual metal oxidation
states and coordination geometries [1]. On the other
hand, polyfunctional ligands are able to support specific
reactivity patterns and structures that extended the ap-
plications of transition metal complexes [2]. Pentaben-
zylcyclopentadienyl is simultaneously bulky and
polyfunctional since it may coordinate as a cyclopenta-
dienyl ligand but also as an arene [3]. These features led
us to the syntheses of pentabenzylcyclopentadienyl mo-
lybdenum and tungsten complexes aiming to evaluate the
specific properties that the ligand confers to the chem-
istry of half-sandwich molybdenum and tungsten deriv-
atives. Our first results on this subject focused on the
synthesis of monocyclopentadienyl chloride compounds
by oxidative decarbonylation reactions here presented.
All new compounds presented in this contribution are
summarised in Scheme 1. Following a synthetic pro-
cedure well established for the syntheses of [MCp0(CO)3-
CH3] (M ¼ Mo, W; Cp0 ¼ C5H5, Ind and derivatives),
treatment of [M(CO)6] (M ¼ Mo, W) with LiC5
(CH2Ph)5 (abbreviated LiCpBz), prepared in situ from
reaction of HCpBz [4] with LiBu, led to Li(S)n-
[M(CpBz)(CO)3] (M ¼ Mo, 1a, W, 1b; S ¼ THF, dyg-
lime) that upon reactions with MeI in THF gave
[M(CpBz)(CO)3CH3] (M ¼ Mo, 2a, W, 2b). Reactions
of 1a with a bulkier alkyl group as (CH3)3CH2Br did not
lead to the alkyl derivative. Probably due to stereo-
chemical constrain, no reaction was observed. When 1b
was prepared in dyglime and then extracted in THF,
its reaction with MeI in THF did not proceed as
expected and [Li(CH3OCH2CH2OCH2CH2OCH3]][W
(CpBz)-(CO)3] has been recovered. The yield of 2b ob-
tained in these conditions was only 6%, whereas when 1b
was prepared in THF, in analogous experimental con-
ditions, 2b was prepared in 38% yield.
The reactions of 2a and 2b with PCl5 led to high yield
syntheses of a g2-acyl molybdenum complex [Mo-
(CpBz)(g2-COCH3)Cl3], 3, and to the expected product
* Corresponding author. Tel.: +351218419172; fax: +351218464457.
E-mail address: ana.martins@ist.utl.pt (A.M. Martins).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.04.027

A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
2369
-
CH2Ph
CH2Ph
CH2Ph
PhH2C
PhH2C
PhH2C
CH2Ph
CH2Ph
CH2Ph
PhH2C
Mo(CO)6
Li
M
OC
CO
CO
MeI
M = Mo, 1a, W, 1b
CH2Ph
PhH2C
PhH2C
CH2Ph
CH2Ph
CO
M
OC
H3C
PCl5
CO
PCl5
CH2Ph
CH2Ph
M = Mo, 2a, W, 2b
PhI Cl2
CH2Ph
CH2Ph
Cl
CH2Ph
CH2Ph
Cl
PhH2C
PhH2C
PhH2C
PhH2C
W
Mo
Cl
Cl
Cl
O
Cl
Cl
CH3
M = Mo, 3
C
CH2Ph
M = W, 4
CH2Ph
PhH2C
PhH2C
CH2Ph
CO
Mo
OC
Cl
CO
5
PhI Cl2
CH2Ph
CH2Ph
PhH2C
PhH2C
CH2Ph
Mo
Cl
Cl
Cl
Cl
6
Scheme 1.
[W(CpBz)Cl4], 4, in the case of tungsten. By analogy
with [MCp0(CO)3CH3] (M ¼ Mo, W; Cp0 ¼ C5H5 and
derivatives) [5–7] that reacts with PCl5 to give
[MCp0Cl4], we did not expect to obtain complex 3 as the
oxidation product of 2a with PCl5. Actually, acyl inter-
mediates have never been claimed to form for Mo or W
half-sandwich compounds under similar experimental
conditions and, furthermore, similar reactivity patterns
have always been displayed by Mo and W complexes in
chlorination reactions. Although acyl derivatives of
general formula [MoCp(CO)3(r-COR)] have been de-
scribed [8,9], alkyl migrations to CO have not been ob-
served in [MoCp0(CO)3CH3] (Cp0 ¼ C5H5, Cp*, Ind),
under pressure of carbon monoxide [10]. In the presence

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A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
Table 1
Relevant bond distances and angles as well as torsion angles for
compounds 2a, 2b and 5
of AlBr3, however, [MoCp(CO)3Me] readily undergoes
methyl migration to give
[MoCp(CO)2{C(OAlBrBr2)Me}]
that reacts with CO to give [MoCp(CO)3{C(OAl-
Br3)Me}] and hydrolyses to [MoCp(CO)2(COMe)] [11].
Analogous [MoCp(CO)2(PPh2R)(r-COMe)] (R ¼ H,
Ph), are formed by reactions of [MoCp(CO)3Me] with
the appropriate phosphines [12] and related g2-acyl
complexes, [MTp(CO)2{g2-C(O)R}] (M ¼ Mo, W) have
been reported to form by reaction of [MTp(CO)3]ꢁ with
alkylating reagents [13,14]. The different behaviours
shown by CpMo and TpMo based complexes have been
reasoned on both stereochemical and electronic argu-
ments [13]. Complex 3 is reminiscent of that reported by
Kreissl and co-workers on the protonation of [WCp-
(CO)2(BCTol)] with HCl that leads to [WCp(CO){g2-
C(O)CH2Tol}Cl2] by insertion of CO in a W–C bond
[15] and also of [WCp(CO)(NCMe)2(g2-COEt)](BF4)2
reported by Tilset and co-worker [16] as the oxidation
product of [WCp(CO)3Et] in acetonitrile.
[M(CpBz)(CO)3Me]
[Mo(CpBz)-
(CO)3Cl], 5
2a
(M ¼ Mo)
2b
(M ¼ W)
M–C(6)/Cl(1)
M–C(7)
M–C(8)
2.290(6)
1.981(4)
2.048(5)
1.971(4)
1.139(5)
1.034(6)
1.121(5)
2.023(8)
2.306(3)
1.999(3)
1.985(3)
1.970(3)
1.150(3)
1.151(3)
1.153(4)
2.022(5)
2.8041(18)
1.997(6)
2.047(8)
1.983(6)
1.145(7)
0.995(8)
1.125(7)
2.018(8)
M–C(9)
C(7)–O(1)
C(8)–O(2)
C(9)–O(3)
M–CT
Cl(1)/C(6)–M–C(7)
Cl(1)/C(6)–M–C(8)
Cl(1)/C(6)–M–C(9)
C(7)–M–C(8)
75.9(2)
74.67(12)
130.00(11)
71.57(12)
76.13(11)
104.35(11)
77.61(12)
112.5(8)
78.5(2)
127.7(2)
72.4(2)
74.1(2)
129.02(19)
71.18(19)
74.4(3)
C(7)–M–C(9)
C(8)–M–C(9)
105.4(2)
75.7(2)
107.0(2)
76.6(3)
CT–M–Cl(1)/C(6)
CT–M–C(7)
CT–M–C(8)
116.5(9)
130.6(8)
115.9(8)
123.8(8)
115.4(9)
129.9(9)
115.1(9)
123.2(9)
The unexpected result obtained with PCl5 led us to
perform reactions of [Mo(CpBz)(CO)3CH3] with
PhI ꢀ Cl2 as a chlorinating reagent. The reaction of
equimolar amounts of 2a and PhI ꢀ Cl2 led to the syn-
thesis of [Mo(CpBz)(CO)3Cl], 5, whereas the use of an
excess of PhI ꢀ Cl2 gave [Mo(CpBz)Cl4], 6. These results
show that the reactivity of [Mo(CpBz)CO)3CH3] with
PhI ꢀ Cl2 pursue via (i) the replacement of a Me by a Cl
ligand and (ii) decarbonylation of the metal centre in
consequence of its oxidation, a pattern that has been
commonly observed for similar complexes [7,17].
The different mechanisms displayed by the chlorina-
tion reactions described and that compound 3 is not a
precursor of 6 are also corroborated by the lack of re-
activity between [Mo(CpBz)(g2-COCH3)Cl3] and an
excess of PCl5 or PhI ꢀ Cl2.
131.2(7)
117.3(7)
129.1(7)
CT–M–C(9)
M–C(1)–C(10)–C(11)
M–C(2)–C(20)–C(21)
M–C(3)–C(30)–C(31)
M–C(4)–C(40)–C(41)
M–C(5)–C(50)–C(51)
)11.1(5)
)173.5(3)
171.8(3)
170.5(3)
157.9(3)
10.0(3)
)11.6(7)
)172.3(4)
172.0(4)
171.3(4)
158.5(4)
)157.1(2)
)169.3(2)
)171.8(3)
173.4(3)
CT – CpBz centroid.
depict ORTEP representations of the complexes pre-
senting the corresponding atomic labelling scheme.
The metal co-ordination geometry in complexes
[M(CpBz)(CO)3X] (M ¼ Mo, X ¼ CH3, 2a, Cl, 5;
M ¼ W, X ¼ CH3, 2b) is very similar and can be best
described as four-legged piano-stool, usually observed
for M(Cp0)L4 complexes. As expected and registered in
Table 1, the CpBz(Centroid)–M–X angles are larger
than the corresponding basal angles. In these complexes
the metal to basal mean square plane distances are
The characterisation of all complexes by IR shows a
common pattern due to the pentabenzylcyclopentadie-
nyl fragment and characteristic peaks attributable to
terminal CO and acyl ligands. The IR acyl frequency in
3 is shifted to higher wavenumbers compared to values
for Mo(II) g2-acyl compounds [13].
ꢁ
1.086(2), 1.057(2) and 1.099(3) A for 2a, 2b and 5, re-
spectively, while the distances to the CpBz mean square
1
The H NMR spectra of the diamagnetic complexes
ꢁ
plane are 2.022(2), 2.021(2) and 2.017(2) A, respectively.
(1a, 1b, 2a, 2b and 5) show one singlet for the metilenic
protons and the usual 2:2:1 patterns for the benzyl ar-
omatic protons of the pentabenzylcyclopentadienyl li-
gand, indicating that there are no constrains to the free
rotation of the benzyl groups. Complexes 2a, 2b and 5
present two carbon resonances for the carbonyl carbons
that integrate 2:1, according to their relative positions to
the methyl or chloride ligands.
The molecular structures of [M(CpBz)(CO)3CH3]
(M ¼ Mo, 2a; W, 2b), [Mo(CpBz)(g2-COCH3)Cl3], 3,
[W(CpBz)Cl4], 4 and [Mo(CpBz)(CO)3Cl], 5 have been
determined by X-ray diffraction. Relevant bond lengths
and angles are presented in Table 1 (for complexes 2a,
2b, and 5), and Table 2 (for complexes 3 and 4). Figs. 1–5
The CpBz mean square and the basal planes define di-
hedral angles of 5.4(2)°, 5.1(2)° and 7.6(3)° respectively
in 2a, 2b and 5. The phenyl rings of four benzyl frag-
ments are directed opposite to the metal and one is
bended down towards the metals but sufficiently far
apart to prevent any bonding interaction. This ar-
rangement is also observed in the solid state structure of
[Mo(CpBz)(CO)3I] [4]. To better characterize the rela-
tive conformation of the phenyl rings we present in
Table 1 the torsion angles of the pending benzyl arms
defined as M–C(CpBz ring)–C(CH2 bridge)–Cipso. In all
compounds the phenyl rings bending towards the metals
define torsion angles of 10–11°, while the others present

A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
2371
Table 2
Relevant bond distances, angles as well as torsion angles for com-
pound 3 and 4
Mo(CpBz5)(g2-
COMe)Cl3, 3
(M ¼ Mo)
W(CpBz5)Cl4,
4 (M ¼ W)
M–C(6)
M–O(1)
M–Cl(1)
M–Cl(2)
M–Cl(3)
M–Cl(4)
C(6)–O(1)
C(6)–C(7)
M–CT1
M–CT2
2.041(13)
2.156(9)
2.399(3)
2.364(3)
2.425(3)
–
–
–
2.279(7)
2.308(7)
2.263(6)
2.247(8)
–
1.201(14)
1.435(18)
2.078(9)
2.01(1)
–
2.028(7)
–
Cl(1)–M–C(6)
Cl(1)–M–O(1)
C(6)–M–O(1)
Cl(1)–M–CT2
Cl(2)–M–C(6)
Cl(2)–M–O(1)
Cl(2)–M–CT2
Cl(3)–M–C(6)
Cl(3)–M–O(1)
Cl(3)–M–CT2
Cl(1)–M–Cl(2)
Cl(1)–M–Cl(3)
Cl(1)–M–Cl(4)
Cl(2)–M–Cl(3)
Cl(2)–M–Cl(4)
Cl(3)–M–Cl(4)
CT1–M–Cl(1)
CT1–M–Cl(2)
CT1–M–Cl(3)
CT1–M–Cl(4)/CT2
73.6(4)
79.8(3)
33.1(4)
76.2(4)
98.5(4)
131.7(2)
115.6(6)
71.6(4)
79.8(3)
75.2(5)
85.82(13)
141.79(12)
–
–
–
–
Fig. 1. Molecular structure of complex 2a. H atoms were excluded for
clarity, thermal ellipsoids at 30% probability level.
–
–
–
–
–
–
–
78.9(5)
131.8(2)
82.9(6)
80.6(4)
138.6(3)
84.5(6)
113.5(7)
111.1(7)
114.6(7)
110.2(7)
84.15(13)
–
–
108.3(5)
111.1(6)
109.7(6)
133.4(7)
M–C(1)–C(10)–C(11)
M–C(2)–C(20)–C(21)
M–C(3)–C(30)–C(31)
M–C(4)–C(40)–C(41)
M–C(5)–C(50)–C(51)
)163.3(9)
)150.9(9)
)150.0(9)
)158.3(9)
)170.4(9)
)161.8(9)
)163.8(9)
)161.3(9)
)176.1(9)
)158.7(9)
CT1 – CpBz centroid; CT2 – medium point in the bond C(6)–O(1).
Fig. 2. Molecular structure of complex 2b. H atoms were excluded for
clarity, thermal ellipsoids at 50% probability level.
angles that range from 157° to 173°. The M–C bond
lengths and the bond distances and angles within the
ligands in complexes 2a, 2b and 5 are similar to those
reported for other cyclopentadienyl carbonyl com-
pounds as [Mo(CpBz)(CO)3I] [4], [M(C5H5)(CO)3Cl]
(M ¼ Mo, W) [16], [Mo(CO)3][Mo(CO)3Cl](g5; g5:g1-
C5H4CH2C5H3) [17]. However, the Mo–Cl distance
since it is not accompanied by other unusual features in
the structure, it may reflect the disorder in the basal li-
gands. The CO ligand trans to the Mo–Cl bond in 5
displays a slightly different geometry with a longer M–C
ꢁ
ꢁ
encountered in 5 is much longer (2.8041(18) A) than the
typical values for this bond in similar compounds (ca.
distance (Mo(1)–C(8), 2.047(8) A) and a shorter CBO
ꢁ
distance, 0.995(8) A (See Table 1).
ꢁ
2.5 A) [17,18] and as long as the Mo–I distance in
Table 2 presents relevant bond distances and angles
for complexes 3 and 4. The molecular structure of
[Mo(CpBz)(g2-COCH3)Cl3], 3, shows the five phenyl
rings of the pentabenzylcyclopentadienyl ligand oppo-
site to the molybdenum as can be geometrically con-
firmed by the torsion angles presented in Table 2 that
range from 150.0(9)° to 170.4(9)°. Considering the me-
dium point of the C–O bond of the g2-C(O)CH3 ligand
[Mo(CpBz)(CO)3I] [4]. Similar distances have been de-
termined for bimetallic metal–metal bonded molybde-
num complexes as Mo2(hpp)4Cl (hpp ¼ anion of
1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) [19]
where the long Mo–Cl distance has been taken as in-
dicative of a less significant bonding contribution. Yet,
the long Mo–Cl distance found in 5 is surprising and,

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A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
Fig. 3. Molecular structure of complex 5. H atoms were excluded for
clarity, thermal ellipsoids at 30% probability level.
Fig. 5. Molecular structure of complex 4. H atoms were excluded for
clarity, thermal ellipsoids at 30% probability level.
(Mo–C(2), Mo–C(3) and Mo–C(4)) reflect the trans ef-
fect of the g2-C(O)CH3 ligand, particularly striking in
ꢁ
the Mo–C(3) bond length (2.512(10) A). The Mo–C(6),
C(6)–O(1) and Mo–O(1) distances (2.041(13), 1.201(14)
ꢁ
and 2.156(9) A) are close to the values reported for
octahedral Mo(II) compounds, [MoTp(CO)nLm(g2-
C(O)R)] (n ¼ 2, m ¼ 0, R ¼ Me, Ph; n ¼ m ¼ 1,
L ¼ P(OMe)3, PEt3, R ¼ Me) [13].
[W(CpBz)Cl4], 4, also exhibits a four-legged piano
stool geometry with angles between the basal ligands in
the range 78.9(5)° to 84.5(6)° (see Table 2). The basal
plane is parallel to the mean square plane of the CpBz
ring with an angle of 1.0(2)° between them. The W atom
ꢁ
is 2.028(5) A away from the CpBz mean square plane
ꢁ
and 0.864(3) A from the basal plane. The benzyl phenyl
groups are all directed opposite to the metal with torsion
angles between 158.7(9)° and 176.1(9)°. The W–
CpBz(cent) distance 2.028(7) A and the W–Cl bond
ꢁ
lengths vary between 2.247(8) and 2.308(7) A. The data
found for the molecular structure of 4 are close to those
reported for [W(C5Et5)Cl4] [7] that also point the five
ethyl groups to the same side, opposite to the metal.
ꢁ
Fig. 4. Molecular structure of complex 3. H atoms were excluded for
clarity, thermal ellipsoids at 30% probability level.
(CT2), the metal co-ordination may be described as
four-legged piano stool, with a metal CpBz mean square
ꢁ
plane distance of 2.068(5) A and a Mo basal plane dis-
ꢁ
tance of 0.961(2) A. The two planes are practically
3. Conclusions
parallel to each other with an angle of 1.5(7)° between
them. Again the basal bonding angles present values
smaller than the ones involving the CpBz (see Table 2).
The distances between the molybdenum and the five
carbons of the Cp ring may be separated in two ranges.
Shorter bond lengths are formed between the metal and
The compounds described have been prepared by
oxidative decarbonylation of half-sandwich molybde-
num and tungsten with PCl5 and PhI ꢀ Cl2. Likewise
other WCp0 derivatives in similar conditions,
[W(CpBz)(CO)3CH3] led to [W(CpBz)Cl4]. The behav-
iour of [Mo(CpBz)(CO)3CH3] is less straightforward
since, depending on the chlorinating reagent used,
ꢁ
carbons C(1) and C(5) (2.324(10) and 2.323(11) A) that
are closer to the acyl ligand. The other Mo–C distances

A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
2373
[Mo(CpBz)(g2-COCH3)Cl3] or [Mo(CpBz)Cl4] have
been obtained. The formation of a g2-acyl ligand by
insertion of CO into the Mo–CH3 bond implies that the
oxidation of the metal by PCl5 precedes the replacement
of the methyl ligand by Cl, as observed in the reaction
of 2a with PhI ꢀ Cl2. The stage at which the methyl mi-
gration takes place and the role of the CpBz ligand in
the stabilisation of possible intermediates are unknown.
However, it is plausible to envisage that, if a cationic
intermediate plays a key role in the methyl migration, as
proposed by Tilset and co-worker [16], the stabilisation
of such compound may, in the case of 2a, be achieved
by intramolecular assistance of a phenyl ring through
g2-coordination. This kind of interaction has been rec-
ognized in [MoCp(CO)2(PPh3)]þ where one of the tri-
phenylphosphine rings bends to coordinate the metal
centre [20]. The molecular structures of all classes of
compounds reported have been determined by single
crystal X-ray diffraction. The pentabenzylcyclopenta-
dienyl ligand adopts two arrangements for the phenyl
rings. In complexes 2a, 2b and 5 four phenyls point
opposite to the metals and one bends down to the
metals, while in 3 and 4 the phenyl rings are directed up,
opposite to the metals.
4.81 mmol) in THF was added. After refluxed for 2 h,
the solvent was removed. A red fraction was extracted in
diethyl ether, which was cooled at )20 °C and yielded
0.12 g (6%) yellow crystals of [W(g5-C5Bz5)(CO)3CH3]
(2b). The fraction insoluble in ether was extracted in
toluene yielded by cooling at )20 °C a white solid
identified by NMR as [LiMeOCH2CH2OCH2CH2-
OMe][W(g5-C5Bz5)(CO)3]. 1H NMR (C6D6, 300 MHz):
d 7.07–6.95 (m, 25H, o-C6H5, m-C6H5, p-C6H5), 4.12 (s,
10H, CH2Ph), 3.42 (s, 6H, CH3O), 3.17, 3.13 (d, 8H,
CH3OCH2CH2OCH2CH2OCH3). 13C NMR (C6D6): d
231.5 (CO), 142.1 (i-C6H5), 129.4 (o-C6H5), 128.0 (m-
C6H5), 125.7 (p-C6H5), 106.1 (C5Bz5), 70.6, 69.2
(H3CO–CH2CH2OCH2CH2OCH3), 59.4(CH3O), 33.7
(CH2).
4.3. [Mo(CpBz)(CO)3CH3], 2a
A solution of HCpBz (1.54 g, 2.98 mmol) in 15 ml of
THF was treated, at 0 °C, with a 1.6 M solution of BuLi
in hexanes (1.92 ml, 3.07 mmol). The mixture was stirred
for 1 h and added to a suspension of [Mo(CO)6] (0.79 g,
2.98 mmol) in THF. The mixture was then refluxed for
24 h and MeI (0.81 ml, 13.00 mmol) diluted in ca. 5 ml
of THF was added. The reflux was kept for more 3 h
and the volatiles were then evaporated off. The residue
was extracted in diethyl ether leading to a brown solu-
tion that was filtered off, concentrated and cooled to
)20 °C to yield yellow crystals of [Mo(CpBz)(CO)3CH3]
(1.80 g, 85%). 1H NMR (C6D6): d 6.87 (m, 15H, m-
C6H5, p-C6H5), 6.60 (m, 10H, o-C6H5), 3.55 (s, 10H
CH2Ph), 0.59 (s, 3H, CH3). 13C{1H}NMR (C6D6): d
242.3, 227.4 (CO) 139.4 (i-C6H5), 129.0 (o-C6H5), 128.3
(m-C6H5), 126.4 (p-C6H5), 110.1 (C5(CH2Ph)5), 32.3
(CH2Ph), –9.7 (CH3). IR (KBr): m(CBO), cmꢁ1: 2011(s),
1934(s), 1919(s), 1904(s). MS (FABþ): 712 (M þ 1)þ,
654 (M–2CO)þ, 626 (M–3CO)þ, 611 (M–3CO–CH3)þ,
515 (C5Bz5)þ. Anal. Calc. for C44H38O3Mo: C, 74.36;
H, 5.39. Found: C, 74.46; H, 5.79.
4. Experimental
4.1. General procedures
All manipulations were carried out under a dry ni-
trogen atmosphere with standard Schlenk techniques
except those where O2 from air was used as an oxidant.
Solvents were predried and distilled from the following
drying agents: hexane and dichloromethane (CaH2), d6-
benzene, toluene, THF, diglime and diethyl ether (Na).
Literature methods were used to prepare HCpBz [4].
NMR spectra were recorded on a Varian Unity 300
instrument at room temperature and were referred to
1
the residual H and 13C NMR resonances of the sol-
vents. Mass spectra were recorded on a Finnegan MAT
System 8200 spectrometer. Elemental analyses were
performed on a Fisons Instruments 1108 device.
4.4. [W(CpBz)(CO)3CH3], 2b
A 1.6 M solution of BuLi in hexanes (2.30 ml, 3.69
mmol) was added dropwise, at 0 °C, to a solution of
HCpBz (1.91 g, 3.69 mmol) in 15 ml of THF. The re-
action proceeded for 1 h and the solvent was then
evaporated to dryness. The product obtained was dis-
solved in DMF and added to a suspension of [W(CO)6]
(1.31 g, 3.73 mmol) in the same solvent. The mixture was
refluxed for 3.5 h. Removal of the solvent led to a black
oil that was dissolved in THF. MeI (1.00 ml, 16.00
mmol) dissolved in THF (8–10 ml) was then added to
and the solution was refluxed for 3 h. The volatiles were
removed and the residue extracted in diethyl ether and
filtered. Yellow crystals of 2b formed from diethyl ether
solution at )20 °C (yield 1.11 g, 38%). 1H NMR (C6D6):
4.2. [Li(CH3OCH2CH2OCH2CH2OCH3)][W(g5-C5Bz5)-
(CO)3] (1b)
To a solution of HCpBz (1.24 g, 2.40 mmol) in about
10 ml of diglyme, a 1.6 M solution of BuLi in hexanes
(1.50 ml, 2.40 mmol) was added dropwise. After 20 min
of reaction, the resulted purple solution was added to
W(CO)6 (0.87 g, 2.40 mmol) in about 10 ml of diglyme,
resulting a yellow mixture after 5 min of reaction. After
refluxed for 24 h, the reaction mixture was evaporated to
dryness, and the resulted black oil was dissolved in
about 10 ml of THF. Then a solution of MeI (0.30 ml,

2374
A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
d 6.86 (m, 15H, m-C6H5, p-C6H5), 6.63 (m, 10H, o-
C6H5), 3.58 (s, 10H CH2Ph), 0.69 (s, 3H, CH3).
13C{1H}NMR (C6D6): d 232.5, 218.0 (CO), 139.2 (i-
C6H5), 129.0 (o-C6H5), 128.3 (m-C6H5), 126.5 (p-C6H5),
108.8 (C5(CH2Ph)5), 32.4 (CH2Ph), )22.1 (CH3). IR
(KBr): m(CBO), cmꢁ1: 2009(s), 1926(s), 1893(s). Anal.
Calc. for C44H38O3W: C, 66.17; H, 4.80. Found: C,
66.16; H, 4.90.
solution rapidly changed colour to dark purple. The
mixture was heated under reflux for 8 h and the sol-
vent was then evaporated off. The dark red oil ob-
tained was extracted in diethyl ether and the solution
was filtered and concentrated leading to dark red
crystals. Yield, 0.87 g, 90%. IR (KBr): m(C@O), cmꢁ1
:
1625(m). Anal. Calc. for C42H38Cl3OMo: C, 66.28; H,
5.03. Found: C, 66.67; H, 5.04.
4.5. [Mo(CpBz)(COCH3)Cl3], 3
4.6. [W(CpBz)Cl4], 4
A dichloromethane solution of [Mo(CpBz)(CO)3-
CH3] (0.90 g, 1.26 mmol) was added to a suspension of
PCl5 (0.66 g, 3.15 mmol) in dichloromethane. The
A solution of [W(CpBz)(CO)3CH3] (0.80 g, 0.99
mmol) in dichloromethane was added to a suspension of
PCl5 (0.52 g, 2.50 mmol) in the same solvent. A dark red
Table 3
Experimental details on X-ray data collection and structure refinement
Compound 2a
Compound 2b
Compound 3
Compound 4
Compound 5
Empirical formula
Formula weight
Temperature (K)
C44H38O3Mo1
710.68
293(2)
C44H38O3W1
798.59
120(2)
C42H38Cl3O1Mo1
761.01
293(2)
C40H35Cl4W1
841.33
293(2)
C43H35Cl1O3Mo1
731.10
293(2)
ꢁ
Wavelength (A)
0.71069
Triclinic
0.71069
Triclinic
1.54184
Triclinic
0.71069
Monoclinic
P21=n
0.71069
Triclinic
Crystal system
Space group
Unit cell dimensions
ꢂ
ꢂ
ꢂ
ꢂ
P1
P1
P1
P1
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
a ¼ 9:955ð4Þ A,
a ¼ 9:8295ð10Þ A,
a ¼ 9:867ð5Þ A,
a ¼ 10:699ð5Þ A,
a ¼ 9:958ð5Þ A,
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
b ¼ 9:992ð4Þ A,
b ¼ 9:8894ð10Þ A,
b ¼ 10:909ð5Þ A,
b ¼ 16:173ð5Þ A,
b ¼ 9:988ð5Þ A,
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
c ¼ 18:327ð6Þ A,
c ¼ 18:178ð2Þ A,
c ¼ 19:068ð5Þ A,
c ¼ 20:338ð5Þ A,
c ¼ 18:264ð7Þ A,
a ¼ 91:38ð2Þ°,
b ¼ 91:46ð2Þ°,
c ¼ 102:75ð2Þ°
1776.6(12)
2
a ¼ 89:926ð2Þ°,
b ¼ 88:271ð4Þ°,
c ¼ 77:808ð4Þ°
1726.4(3)
2
a ¼ 101:70ð2Þ°,
b ¼ 97:13ð3Þ°,
c ¼ 114:66ð3Þ°
1775.5(13)
2
b ¼ 94:03ð2Þ°
a ¼ 91:33ð2Þ°,
b ¼ 91:57ð2Þ°,
c ¼ 103:09ð2Þ°
1767.9(14)
2
3
ꢁ
Volume (A )
3510(2)
4
Z
Calculated density (Mg/m3) 1.328
1.536
3.386
1.423
5.342
1.592
3.623
1.373
0.486
Absorption coefficient
(mmꢁ1
0.408
)
F (0 0 0)
Crystal size
736
0.60 ꢂ 0.30 ꢂ 0.09
mm
800
0.49 ꢂ 0.18 ꢂ 0.15
mm
782
0.5 ꢂ 0.3 ꢂ 0.1 mm
1668
0.9 ꢂ 0.6 ꢂ 0.2 mm
752
0.9 ꢂ 0.65 ꢂ 0.15 mm
Crystal morphology
Colour
Parallelepiped
Yellow
2.09–24.97
Parallelepiped
Yellow
3.04–27.47
Parallelepiped
Dark red
4.60–66.94
Parallelepiped
Dark red
1.61–25.97
Parallelepiped
Red
2.10–24.97
Theta range for data
collection (°)
Limiting indices
ꢁ11 6 h 6 11;
ꢁ11 6 k 6 0;
ꢁ21 6 l 6 21
6577/6191
ꢁ12 6 h 6 12;
ꢁ12 6 k 6 12;
ꢁ23 6 l 6 23
29056/7795
0 6 h 6 11;
ꢁ13 6 k 6 11;
ꢁ22 6 l 6 22
6451/6064
0 6 h 6 13;
ꢁ19 6 k 6 0;
ꢁ25 6 l 6 25
7238/6861
ꢁ11 6 h 6 11;
0 6 k 6 11;
ꢁ21 6 l 6 21
Reflections collected/
unique
6705/6110
[R
¼ 0:0130]
[R
¼ 0:0504]
[R
¼ 0:0885]
[R
¼ 0:1273]
[R
ðintÞ
¼ 0:0290]
ðintÞ
ðintÞ
ðintÞ
ðintÞ
Completeness to theta
Refinement method
99.4% (h ¼ 24:97)
Full-matrix least-
squares on F 2
6191/0/568
98.7% (h ¼ 27:47)
Full-matrix least-
squares on F 2
7795/0/585
96.1% (h ¼ 66:94)
Full-matrix least-
squares on F 2
6064/0/420
100.0% (h ¼ 25:97)
Full-matrix least-
squares on F 2
6861/0/407
98.5% (h ¼ 24:97)
Full-matrix least-
squares on F 2
6110/0/434
Data/restraints/
parameters
Goodness-of-fit on F 2
Final R indices [I > 2rðIÞ]
1.024
1.042
1.024
0.936
1.048
R1 ¼ 0:0458;
wR2 ¼ 0:1168
R1 ¼ 0:0589;
wR2 ¼ 0:1234
None
R1 ¼ 0:0241;
wR2 ¼ 0:0537
R1 ¼ 0:0265;
wR2 ¼ 0:0545
None
R1 ¼ 0:1050;
wR2 ¼ 0:2690
R1 ¼ 0:1507;
wR2 ¼ 0:2949
0.0026(5)
R1 ¼ 0:0849;
wR2 ¼ 0:1985
R1 ¼ 0:1787;
wR2 ¼ 0:2339
None
R1 ¼ 0:0636;
wR2 ¼ 0:1637
R1 ¼ 0:0844;
wR2 ¼ 0:1773
0.0010(13)
R indices (all data)
Extinction coefficient
Absorption correction
Largest differential peak
Psi scan
1.952 and )0.454
Sortav
1.047 and )1.904
None
1.381 and )1.312
Difabs
1.985 and )2.295
Difabs
2.033 and )0.834
ꢁ3
ꢁ
and hole (e A
)

A.M. Martins et al. / Journal of Organometallic Chemistry 689 (2004) 2368–2376
2375
solution formed almost immediately and gas evolution
was observed. The mixture was stirred for 24 h and fil-
tered. The solvent was evaporated to dryness leading to
an orange solid in 92% yield (0.76 g). Anal. Calc. for
C40H35Cl4W: C, 57.10; H, 4.19. Found: C, 56.98; H, 4.31.
non-hydrogen atoms were refined anisotropically. Hy-
drogen atoms were inserted in idealized positions riding
in the parent C atoms except for compound 2b where
they were located in the electron density map and re-
fined. The poor crystal quality of compound 4 (seen in
the Rint value obtained) prevented the refinement to
lower R values. In compound 5 the Cl atom shows some
disorder but no model gave a better R factor or better
atomic displacement parameter, the residual electron
density found in this complex reflects this disorder.
Different absorption corrections were used in the crystal
data and are referred in Table 3 [24,25]. Torsion angles,
mean square planes and other geometrical parameters
were calculated using PARST [26]. More experimental
details are given in the Supplementary Material. Illus-
trations of the molecular structures were made with
ORTEP 3 [27]. Data was deposited in CCDC under the
deposit numbers CCDC 229976–229980 for compounds
2a, 2b, 3, 4 and 5, respectively.
4.7. [Mo(CpBz)(CO)3Cl], 5
[Mo(CpBz)(CO)3CH3] (3a) (1.52 g, 2.14 mmol) in
dichloromethane was added dropwise, at )40 °C, to a
solution of PhI ꢀ Cl2 (0.59 g, 2.14 mmol) in the same
solvent. The colour of the reaction mixture turned dark
red almost immediately and gas evolution was ob-
served. The mixture was stirred overnight and solvent
was then evaporated to dryness. The residue was ex-
tracted with hexane and the solution was filtered and
evaporated to dryness. Crystals suitable for X-ray dif-
1
fraction were grown from diethyl ether at )20 °C. H
NMR (C6D6, 300 MHz): d 6.88 (m, 15H, m-C6H5 + p-
C6H5), 6.62 (m, 10H, o-C6H5), 3.72 (s, 10H CH2Ph).
13C NMR (C6D6): d 227.4, 205.7 (CO), 139.4 (i-C6H5),
129.0 (o-C6H5), 128.3 (m-C6H5), 126.7 (p-C6H5), 113.2
Acknowledgements
(C5Bz5), 33.3 (CH2). IR (KBr disc): m(CBO), cmꢁ1
:
2032(s), 1963(s).
~
^
We are grateful to Fundaßcao para a Ciencia e a
Tecnologia, Portugal, that funded this work (POCTI/
QUI/34400/2000 and SFRH/BPD/3590/2000).
4.8. [Mo(CpBz)Cl4], 6
[Mo(g5-C5Bz5)(CO)3CH3] (3a) (2.21 g, 3.10 mmol) in
dichloromethane was added dropwise, at )40 °C, to a
solution of PhI ꢀ Cl2 (11.25 mmol) in the same solvent.
The colour turned into red almost immediately and gas
evolution was observed. The mixture was allowed to stir
overnight. The solvent was removed under vacuum to
give a red oil that was washed with cold hexane and left
a dark-red powder (1.55 g, g ¼ 66%).
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