Synthesis and characterisation of cationic bis(cyclopentadienyl)-tungsten(IV) complexes

Article abstract of DOI:10.1039/a909732e

Cationic hydride complexes of bis(cyclopentadienyl)tungsten(iv) have been prepared and studied. The complex [W(η-C₅H₅)₂H(thf)][SO₃CF ₃] reacts with CS₂ in d₆-acetone to form the chelated O-alkyl dithiocarbonate tungsten hydride insertion product [W(η-C₅H₅)₂(η₂-S ₂COCH(CD₃)r5,S′)][SO₃CF₃] as demonstrated by single crystal X-ray diffraction and NMR spectroscopy. The styrene complex [W(Ti-C₃H₅)₂H(Ti₂-CH ₂CHC₆H₅)][PF₆] has been prepared as a mixture of exo and endo isomers. This isomeric mixture reacts thermally with NCMe to give [W(η-C₅H₅)₂(CH₂CH ₅C₅H₅)(NCMe)][PF₆] and photochemically with NCMe to give [W(η-C₅H₅)₂H(NCMe)][PF₆]. The molecular structures of the cxo isomer and of the benzonitrile complex [W(η-C₅H₅)₂H(NCPh)][SO₃CF ₃] are reported. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/a909732e

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Synthesis and characterisation of cationic bis(cyclopentadienyl)-
tungsten(IV) complexes†
Adrian J. Carmichael,* David J. Duncalf, Malcolm G. H. Wallbridge and Andrew McCamley
Department of Chemistry, University of Warwick, Coventry, UK CV4 7AL.
E-mail: A.J.Carmichael@warwick.ac.uk
Received 10th December 1999, Accepted 14th February 2000
Published on the Web 7th March 2000
Cationic hydride complexes of bis(cyclopentadienyl)tungsten() have been prepared and studied. The complex
[W(η-C5H5)2H(thf)][SO3CF3] reacts with CS2 in d6-acetone to form the chelated O-alkyl dithiocarbonate tungsten
hydride insertion product [W(η-C5H5)2(η2-S2COCH(CD3)2-S,SЈ)][SO3CF3] as demonstrated by single crystal X-ray
diffraction and NMR spectroscopy. The styrene complex [W(η-C5H5)2H(η2-CH2CHC6H5)][PF6] has been prepared
as a mixture of exo and endo isomers. This isomeric mixture reacts thermally with NCMe to give [W(η-C5H5)2-
(CH2CH2C6H5)(NCMe)][PF6] and photochemically with NCMe to give [W(η-C5H5)2H(NCMe)][PF6]. The molecular
structures of the exo isomer and of the benzonitrile complex [W(η-C5H5)2H(NCPh)][SO3CF3] are reported.
crystallography.20 We now describe reactions of 1 together with
Introduction
the crystal structure of one of the products, the complex result-
In several catalytic cycles the insertion of an unsaturated mol-
ing from the insertion of CS2 into d6-acetone, [W(η-C5H5)2(η2-
ecule into a transition metal–hydride bond is a fundamental
S2COCH(CD3)2-S,SЈ)][SO3CF3] 2. The crystal structure of the
complex where L = NCPh, [W(η-C5H5)2H(NCPh)][SO3CF3] 3,
step.1,2 Catalytically active transition metal–hydride complexes
can be prepared and isolated, but in many reactions they are
is presented, and also detailed are the synthesis, reactions and
generated in situ and are highly transient in nature. The high
molecular structure of the complex [W(η-C5H5)2H(η2-CH2-
degree of reactivity and selectivity afforded by these complexes,
CHC6H5)][PF6] 4.
and the short existence of many, has generated a lot of interest
in the synthesis and characterisation of stable transition metal–
hydride complexes. For example, a series of ruthenium cations
Results and discussion
such as [Ru(η6-C6H6)H(Ph2PCH2CH2OCH3)]ϩ have been char-
The hydride complexes [W(η-C5H5)2H(L)]ϩ undergo ligand
acterised and shown to be active catalysts for ring opening
dissociation forming the 16-electron transient [W(η-C5H5)2-
metathesis polymerisation of norbornene.3 The complex [Ru-
H]ϩ.19,20 In the case of 1 where donor ligand L = thf, the
(η-C5Me5)H3(PCy3)] has been prepared and used as a catalyst
transient can be generated under moderate conditions at a rate
precursor for the selective “head-to-tail” dimerisation of
suitable for synthetic purposes. Generation of this intermediate
acrylic compounds,4 and the Group 6 transition metal com-
by heating d6-acetone solutions of 1 in the presence of
plexes [MH(CO)5]Ϫ have been employed in the study of carbon
additional ligands (CO2, CS2, styrene and methyl acrylate) was
dioxide activation.5,6
carried out. Monitoring by 1H NMR spectroscopy showed
that unco-ordinated thf was produced, however no isolable
The first bis(cyclopentadienyl) complex of tungsten, [W(η-
C5H5)2H2], was prepared by Green et al. in 1961.7 Since this
organometallic products were obtained except for the reaction
report, a large number of bent metallocene derivatives have
with carbon disulfide. This reaction, unlike the others, gives a
been prepared and studied.8,9 Most of this research has relied
1
clean H NMR spectrum with resonances at δ 5.81 and 3.76
on Green’s original method,7 or on his improved scaled up ver-
(Table 1). With the aid of a single crystal X-ray diffraction
structure of the product, Fig. 1, the resonances were respec-
sion,10 as the entry route. Alternative entry routes have been
reported and include a metal-vapour synthesis11 and a synthesis
tively assigned to the cyclopentadienyl ligands and the methine
from [WCl4(dme)].12 Routes to bent metallocene complexes of
hydrogen in [W(η-C5H5)2(η2-S2COCH(CD3)2-S,SЈ)][SO3CF3] 2.
tungsten containing substituted cyclopentadienyl ligands and
Only one resonance is observed for the cyclopentadienyl ligands
indicating that an equilibrium process, fast on the NMR time-
scale, is occurring: this is most likely rotation about the C(11)–
O(1) bond. The resonances for the deuteriated methyl groups
η5-cyclic analogues have been described;13–15 the preparation of
ansa-metallocenes has also been reported.16–18
As part of a programme investigating small molecule activ-
ation, new methods for the preparation of cationic [W(η-
were indistinguishable from the resonance for the solvent,
C5H5)2]-based compounds have been sought.19,20 We recently
d6-acetone.
reported a synthetic route to the cationic hydride complexes
The single crystal structure of complex 2 is shown in Fig. 1;
selected bond lengths and angles are given in Table 2. The struc-
[W(η-C5H5)2H(L)]ϩ (L = NCR, CNtBu or thf), eqn. (1).20 These
ture shows a distorted tetrahedral geometry about the tungsten
[W(η-C5H5)2H2] ϩ CF3SO3Me ϩ L →
centre with two η5-cyclopentadienyl ligands co-ordinated and
[W(η-C5H5)2H(L)]ϩ ϩ CH4 (1)
the remaining sites occupied by two sulfur atoms of a
chelated O-alkyl dithiocarbonate ligand. The four-membered
metalloheterocyclic ring defined by W1, S1, S2 and C11 is
essentially planar with the maximum deviation of any atom
complexes have been characterised by spectroscopic techniques,
and in the case of L = thf, [W(η-C5H5)2H(thf)][SO3CF3] 1, by
from the plane being 0.001 Å (O1 is only 0.019 Å above this
plane). The tungsten–sulfur bond length of 2.470(4) Å is
† This paper is dedicated to the late Dr Andrew McCamley.
DOI: 10.1039/a909732e
J. Chem. Soc., Dalton Trans., 2000, 1219–1223 1219
This journal is © The Royal Society of Chemistry 2000

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Table 1 Analytical and spectroscopic data
Complex
Analysisa (%)
IRb (cmϪ1
)
1H NMRc
13C NMR
2d
4e
5.81 [10H, s, η-C5H5]
3.76 [1H, s, OCH(CD3)2]
endo
7.21 [5H, m, C6H5]
5.79 [5H, s, η-C5H5]
C 38.00 (38.30)
H 3.3 (3.40)
1436 [ν(C᎐C)]
145.76, 144.36 [Cq, C6H5]
129.22, 129.05, 128.91, 127.47,
126.91 [CH, C6H5]
᎐
5.31 [5H, s, η-C5H5]
92.15, 91.87, 91.74, 90.88 [η-C5H5]
40.05, 35.29 [CH2CH2CHC6H5]
15.29, 7.37 [CH2CHC6H5]
4.27 [1H, dd, J(HH) = 14.1, 10.4, CH2CHC6H5]
2.49 [1H, dd, J(HH) = 14.1, 5.5, CH2CHC6H5-cis]
2.28 [1H, dd, J(HH) = 10.4, 5.5, CH2CHC6H5-trans]
Ϫ6.01 [1H, s, hydride, J(183WH) = 50.1]
exo
7.21 [5H, m, C6H5]
5.81 [5H, s, η-C5H5]
5.15 [5H, s, η-C5H5]
3.99 [1H, dd, J(HH) = 14.0, 10.4, CH2CHC6H5]
2.42 [1H, ddd, J(HH) = 14.0, 6.7, 1.2, CH2CHC6H5-cis]
2.19 [1H, ddd, J(HH) = 10.4, 6.7, 1.2, CH2CHC6H5-trans]
Ϫ6.53 [1H, s, hydride, J(183WH) = 48.2]
7.18 [5H, m, C6H5]
5.49 [10H, s, η-C5H5]
2.77 [3H, s, CH3CN]
5
C 39.35 (39.70)
H 3.65 (3.65)
N 2.40 (2.30)
2343 [ν(CC) ϩ
δ(CH3)]
2268 [ν(CN)]
148.75 [Cq, C6H5]
136.42 [CN]
128.91 [CH, C6H5]
128.43 [CH, C6H5]
125.75 [CH, C6H5]
92.19 [η-C5H5]
2.72 [2H, m, CH2CH2C6H5]
1.11 [2H, m, CH2CH2C6H5]
45.12 [CH2CH2C6H5]
4.80 [CH3CN]
Ϫ3.73 [CH2CH2C6H5]
Ϫ
a Analytical data given as found (required). b Nujol mull. Complexes 4 and 5 also show strong bands at 828 and 557 cmϪ1, assigned as ν(P–F) of PF6
counter ion. c In (CD3)2CO solution (295 K), data given as chemical shift (δ) (relative intensity, multiplicity, J/Hz, assignment). d Characterisation by
1H NMR and X-ray diffraction data only. e Combined 13C NMR data for endo and exo isomers.
Table 2 Selected bond lengths (Å) and angles (Њ) for the complexes 2, 3
and exo-4
[W(η-C5H5)2(η2-S2COCH(CD3)2-S,SЈ)][SO3CF3] 2
W–Cp
1.98
Cp–W(1)–Cp
135.7
70.12(15)
88.2(6)
W(1)–S(1)
W(1)–S(2)
S(1)–C(11)
S(2)–C(11)
C(11)–O(1)
O(1)–C(12)
2.470(4)
2.470(4)
1.699(17)
1.696(17)
1.312(19)
1.477(19)
S(1)–W(1)–S(2)
W(1)–S(1)–C(11)
W(1)–S(2)–C(11)
S(1)–C(11)–S(2)
S(1)–C(11)–O(1)
S(2)–C(11)–O(1)
C(11)–O(1)–C(12)
88.3(6)
113.4(9)
119.3(12)
127.3(13)
121.1(13)
[W(η-C5H5)2H(NCPh)][SO3CF3] 3
W–Cp
W–N
N–C(11)
1.96
2.096(9)
1.159(14)
Cp–W–Cp
W–N–C(11)
N–C(11)–C(12)
143.7
176.9(9)
174.4(13)
Fig. 1 Molecular structure of the cation of complex 2.
typical of that found in tungstenocene sulfur complexes as
shown in Table 3. Both C–S bonds are essentially equal in
length and shorter than the typical C–S single bond,21,22 which,
along with the observed planarity, is consistent with delocalis-
ation in the chelated O-alkyl dithiocarbonate ligand. The S1–
W–S2 angle of 70.12(15)Њ is smaller than the related angle in
many other reported d2 tungstenocene complexes as a result
of compression enforced by the ring size.23–25 This angle is
similar in size to that found in the related four-membered
ring complexes [(η-C5H5)2W(µ-SC6H5)2M(CO)4] (M = Cr, Mo
or W).26
C(11)–C(12) 1.44(2)
exo-[W(η-C5H5)2H(η2-CH2CHC6H5)][PF6] exo-4
W–Cp
W–C(11)
W–C(12)
1.98
2.264(16)
2.323(15)
Cp–W–Cp
139.7
C(11)–W–C(12)
W–C(11)–C(12)
W–C(12)–C(11)
W–C(12)–C(13)
36.2(6)
74.1(9)
69.6(9)
120.9(11)
C(11)–C(12) 1.43(3)
C(12)–C(13) 1.47(2)
C(11)–C(12)–C(13) 123.3(15)
Cp = C5H5 ring centroid.
In [W(η-C5H5)2H(L)][SO3CF3] where L = PhCN 3 the ‘L’ lig-
tetrahedral geometry around the tungsten centre, as observed in
all complexes of this type. The W–N bond length (2.096(9) Å) is
similar to that reported by us for related cationic tungsten–
acetonitrile complexes.19,20
₁
and is much more tightly bound than where L = thf 1; at 44 ЊC t
₂

for L substitution is 315 and 6.7 hours respectively,20 making 3
much less useful as a synthetic source of the 16-electron transi-
ent [W(η-C5H5)2H]ϩ. Crystals of 3 suitable for X-ray diffraction
were grown from benzonitrile–Et2O and a molecular structure
obtained as illustrated in Fig. 2. Selected bond lengths and
angles are given in Table 2. A pseudo-tetrahedral tungsten
centre with a ring centroid–tungsten–ring centroid angle of
143.7Њ is observed. The hydride ligand was not located in the
difference map, however, positioning of the hydride ligand
at the site observed in Fig. 2 would complete the pseudo-
The olefin complex [W(η-C5H5)2H(η2-CH2CHC6H5)][PF6] 4
was prepared as described for related complexes27,28 by treating
the neutral dichloride [W(η-C5H5)2Cl2] with an excess of the
Grignard reagent29 [MgBr(CHCH3C6H5)]. Compound 4 was
isolated as a mixture of endo and exo isomers in the ratio 4:3, a
typical ratio found for olefin hydride complexes of tungsteno-
cene,28 Scheme 1. We presume that the observed isomer ratio is
an equilibrium position attained by a base catalysed proton-
1220
J. Chem. Soc., Dalton Trans., 2000, 1219–1223

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Table 3 Tungsten–sulfur bond lengths in tungstenocene complexes
Complex
W–S/Å
Ref.
[(η-C5H5)2W(µ-SC6H5)2Cr(CO)4]
[(η-C5H5)2W(µ-SC6H5)2Mo(CO)4]
[(η-C5H5)2W(µ-SC6H5)2W(CO)4]
[W(η-C5H5)2(S2C6H4)]
2.504(6)
2.487(7)
2.49(1)
2.421(2)
2.42
26
26
26
43
[W(η-C5H5)2(η2-S4)]
44
[W(η-C5H5)2(2-SN2OC4H3)][PF6]
2
2.495(7)
2.470(4)
45
This work
Fig. 3 Molecular structure of the cation of complex exo-4.
solution of 4 at 0 ЊC, and a molecular structure obtained as
illustrated in Fig. 3. Selected bond lengths and angles are pre-
sented in Table 2. The structure shows a tungsten centre with
the two cyclopentadienyl ligands co-ordinated in the con-
ventional η5 fashion. The hydride ligand was located in the
difference map, at the site shown in Fig. 3, thus assigning the
stereochemistry about the tungsten centre as exo. The olefinic
carbon–carbon bond length (C11–C12) of 1.43(3) Å is longer
than that of a free olefin (e.g. ethene, 1.337(2) Å)30 and is simi-
lar to that found in olefin complexes of electron rich, low valent
metal centres.31–33 The observed long olefinic bond length in
exo-4, along with the W–olefin carbon bond lengths (2.264(16)
and 2.323(15) Å) which are similar to those reported in related
complexes,34,35 for a tungsten–carbon σ bond, mean that 4 has
considerable metallocyclopropane character. This is consistent
with the observed spectroscopic data for 4. A search of the
Cambridge Crystallographic Database revealed that no mono-
nuclear tungsten–styrene compounds have previously been
characterised by crystallography. In fact, only two η2-olefin
complexes of the bis(cyclopentadienyl)tungsten unit have been
structurally characterised: [W(η-C5H5)2CH3(η2-CH2CH2)][PF6]
and the ansa complex [W{(η-C5H4)CMe2(η-C5H4)}H(η2-
CH2CH2)][B(C6F5)4].36,37 The olefin ligand in these complexes is
bound in a manner similar to that found in 4.
Fig. 2 Molecular structure of the cation of complex 3.
The reaction of the isomeric mixture of complex 4 with
MeCN under thermal conditions is similar to that reported for
[W(η-C5H5)2H(η2-CH2CH2)][PF6].19 The styrene in 4 inserts
into the tungsten–hydride bond, followed by co-ordination of
an NCMe molecule at the vacant site to yield only one product,
[W(η-C5H5)2(CH2CH2C6H5)(NCMe)][PF6] 5, and not a mixture
of isomers (Scheme 1). The NMR spectra show the presence of
two methylene groups, and the IR spectrum is similar to that for
the acetonitile complexes reported previously,19,20 thus confirm-
ing the structure of 5 as that resulting from primary insertion
with a terminal nitrile co-ordinated.
Scheme 1 Synthesis and reactions of complex 4. (i) 20 ЊC, toluene,
[MgBr(CHCH3C6H5)]; (ii) 20 ЊC, water, NH4PF6; (iii) 20 ЊC, MeCN;
(iv) hν, 20 ЊC, MeCN.
The analogous reaction with d3-MeCN was carried out, thus
1
ation/deprotonation process of the hydride ligand during
work-up.28
allowing it to be followed by H NMR. This showed that the
reaction was slower than that with [W(η-C5H5)2H(η2-CH2-
CH2)][PF6].19,38 This may be reasonably ascribed to the electron
withdrawing substituent on the olefin double bond of 4 which
encourages back donation and makes the olefin bond more
strongly to the tungsten in 4. The insertion rates for the exo and
endo isomers are different, the endo undergoing insertion ca.
3.5 times as fast. This fits with the trend observed in the [W(η-
C5H5)2H(η2-CH2CHCH3)][PF6] system, in which insertion of
the propene ligand into the tungsten–hydride bond has been
studied using Spin Population Transfer experiments.28 The
insertion product 5 contains an alkyl with an electron with-
drawing group which has the effect of stabilising the alkyl
towards β-hydride elimination. Qualitative analysis of a series
The analytical and spectroscopic data for 4 are given in
1
Table 1. The resonances for the endo and exo forms in the H
NMR spectrum of the isomeric mixture were assigned using
integrals, and an observed coupling between the methylene pro-
tons of the lesser isomer (J(HH) = 1.2 Hz) by a through-space
interaction. The methine resonance of the major isomer was
somewhat broader, compared with that of the minor isomer,
indicating an analogous, but unresolved, through-space inter-
action. The IR spectrum of 4 shows a reduction of 194 cmϪ1
for the ν(C᎐C) band compared to that of free styrene.
᎐
Crystals of complex 4 suitable for X-ray diffraction study
were difficult to obtain. After repeated attempts, a misshapen
crystal was grown by slow diffusion of Et2O into an acetone
1
of d6-acetone H NMR spectra of 5 taken over a period of
J. Chem. Soc., Dalton Trans., 2000, 1219–1223
1221

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Table 4 Crystal data for complexes 2, 3 and exo-4
2
3
exo-4
Formula
M
C15H17F3O4S3W
598.32
C18H16F3NO3SW
567.23
C18H19F6PW
564.15
Crystal system
Space group
Monoclinic
P21/c
Orthorhombic
P212121
Monoclinic
P21/c
a/Å
b/Å
c/Å
7.3175(2)
20.8936(7)
14.3418(4)
92.71
2190.24(11)
4
5.600
200(2)
11216
2714
8.759(2)
13.161(3)
15.623(3)
6.5260(13)
17.464(4)
15.736(3)
94.67(3)
1787.5(6)
4
6.610
220(2)
3998
2220
β/Њ
U/Å3
1801.0(7)
4
6.579
150(2)
8181
2741
0.0493
0.1122
Z
µ(Mo-Kα)/mmϪ1
T/K
Reflections collected
Unique reflections
R
0.0735
0.2375
0.0705
0.1589
wR2 (all data)
several days shows that β-hydride elimination occurs, but at a
slower rate than found in [W(η-C5H5)2(CH2CH3)(NCMe)]-
[PF6],19,38 generating 4 and free MeCN. The endo isomer is
formed first, and with time the ratio of endo:exo isomers
approaches that found for the synthesis of 4. Photolysis of 5
in d3-MeCN generates free styrene and the CD3CN analogue
[W(η-C5H5)2H(NCCD3)][PF6], with complete conversion
achieved within one hour (Scheme 1). The formation of [W(η-
C5H5)2H(NCCD3)][PF6] is consistent with the photochemical
mechanism proposed earlier.19
In conclusion, we have described some tungstenocene–
hydride complexes, including X-ray crystallographic studies,
and presented examples of their reactivity. The unsaturated
molecules CS2 and styrene have been shown to insert into the
W–H bond to give isolable organometallic complexes.
added either a drop of CS2, styrene or methyl acrylate, or it was
placed under an atmosphere of CO2. The samples were heated
1
1
to 50 ЊC and H NMR spectra ran at intervals. When the H
NMR spectra indicated reaction was complete, all volatiles were
removed under reduced pressure, and d6-acetone 1H NMR
spectra were taken of the residues. For the reaction with CS2 the
residue was recrystallised from acetone–diethyl ether to yield
brown crystals of [W(η-C5H5)2(η2-S2COCH(CD3)2-S,SЈ)][SO3-
CF3] 2.
[MgBr(CHCH3C6H5)]. To a diethyl ether (100 cm3) suspen-
sion of magnesium turnings (5.3 g, 218 mmol) at 0 ЊC was
added dropwise 1-phenylethyl bromide (10 g, 54 mmol) in
diethyl ether (50 cm3). The mixture was stirred for 2 hours
at 0 ЊC and refluxed for 2 hours. The resultant solution was
decanted and the magnesium turnings washed with diethyl
ether (3 × 15 cm3). The washings were combined to give a
0.27 M solution of [MgBr(CHCH3C6H5)] in diethyl ether (stan-
dardised by reaction of an aliquot (5 cm3) with 1.72 M HCl
(3 cm3), and titration of excess of acid with 0.1 M NaOH).
Experimental
All manipulations of air- and moisture-sensitive materials were
carried out using standard vacuum and Schlenk techniques
under an atmosphere of argon, or in a dry-box under an
atmosphere of nitrogen. All solvents were purified and dried
by refluxing over a suitable drying agent, followed by distil-
lation under a nitrogen atmosphere. Toluene was dried over
molten sodium, diethyl ether over sodium–potassium alloy
(NaK2.2), tetrahydrofuran over molten potassium, ethanol
over magnesium turnings, acetonitrile and chloroform over
calcium hydride and acetone over anhydrous magnesium sul-
fate. Carbon disulfide, styrene, methyl acrylate and benzonitrile
were distilled and degassed by three freeze–pump–thaw cycles.
Other materials were purchased from commercial sources and
used without further purification.
[W(ꢀ-C5H5)2H(ꢀ2-CH2CHC6H5)][PF6] 4. To a stirred toluene
(30 cm3) suspension of [W(η-C5H5)2Cl2] (0.3 g, 0.78 mmol) was
slowly added [MgBr(CHCH3C6H5)] (2.5 mmol) in diethyl ether.
The mixture was stirred at room temperature for 12 hours giv-
ing an orange suspension. The solvent was removed in vacuo
and to the resultant orange solid at Ϫ80 ЊC was added ethanol
(30 cm3). The mixture was warmed to room temperature and
the solvent removed under reduced pressure. The residue was
extracted with water (3 × 50 cm3) and the extracts filtered
through Celite. Addition of NH4PF6 (0.15 g, 0.92 mmol) to
this solution gave a cream precipitate which was collected by
filtration, washed with water (3 × 10 cm3) and diethyl ether
(3 × 10 cm3) and dried under vacuum. Recrystallisation from
acetone–diethyl ether yielded ca. 0.13 g (30%) of a cream
crystalline solid of 4 as a mixture of exo and endo isomers in the
ratio 3:4.
The compounds [W(η-C5H5)2H(thf)][SO3CF3] 1,20 [W(η-
C5H5)2H(NCPh)][SO3CF3] 320 and [W(η-C5H5)2Cl2]39 were
prepared according to literature methods.
Photochemical reactions were carried out using a water-
cooled 150 W medium-pressure mercury lamp irradiating
stirred solutions in ampoules or NMR tubes fitted with airtight
Young’s taps (Young’s ampoule or Young’s NMR tube).
Nuclear magnetic resonance spectra were recorded using
Bruker AS-250 and WH-400 spectrometers, referenced using
the resonances of residual protons in the deuteriated solvents,
infrared spectra using a Perkin-Elmer 1720X FTIR spec-
trometer using NaCl plates. Microanalyses were obtained using
a Leeman Labs CE440 analyser.
[W(ꢀ-C5H5)2(CH2CH2C6H5)(NCMe)][PF6] 5. A pale solution
of [W(η-C5H5)2H(η2-CH2CHC6H5)][PF6] 4 (0.1 g, 0.18 mmol)
in MeCN (20 cm3) was stirred in the dark at room temperature
for two weeks to give an orange solution. Removal of solvent
under reduced pressure followed by recrystallisation from
acetonitrile–diethyl ether yielded ca. 93 mg (85%) of orange
crystals of 5.
Photochemical reaction of [W(ꢀ-C5H5)2(CH2CH2C6H5)-
(NCMe)][PF6] 5 with CD3CN. A CD3CN (2 cm3) solution of
[W(η-C5H5)2(CH2CH2C6H5)(NCMe)][PF6] 5 (ca. 50 mg) in a
Young’s NMR tube was irradiated for 1 hour, during which
time the solution became yellow. 1H NMR spectrocopy showed
Preparations
[W(ꢀ-C5H5)2(ꢀ2-S2COCH(CD3)2-S,SЈ)][SO3CF3] 2. A solu-
tion of [W(η-C5H5)2H(thf)][CF3SO3] 1 (ca. 50 mg) in d6-acetone
(2 cm3) was made up in a Young’s NMR tube. To this was
1222
J. Chem. Soc., Dalton Trans., 2000, 1219–1223

View Article Online
11 M. J. D’Aniello, Jr. and E. K. Barefield, J. Organomet. Chem., 1974,
the yellow solution to contain [W(η-C5H5)2(H)(NCCD3)][PF6]
and unco-ordinated styrene only.
76, C50.
12 C. Persson and C. Andersson, Organometallics, 1993, 12, 2370.
13 G. Parkin and J. E. Bercaw, Polyhedron, 1988, 7, 2053.
14 T. C. Forschner and N. J. Cooper, J. Am. Chem. Soc., 1989, 111,
7420.
Crystal structure determinations
Crystallographic data for complexes 2, 3 and exo-4 are summar-
ised in Table 4. Single crystals were glued to quartz fibres,
coated in Nujol and cooled in the cold gas stream of the dif-
fractometer. Data for 2 and 4 were collected on a Siemens 3
circle diffractometer equipped with a SMART CCD area
detector. Data for 3 were collected on a Siemens R3 four circle
diffractometer operating in the ω–2θ mode; three standard
reflections were monitored every 197. No decay was measured.
Both instruments used graphite-monochromated Mo-Kα radi-
ation (λ = 0.71073 Å). The structures were solved by direct
methods using SHELXTL40 version 5 software; refinements
were carried out using SHELXTL 96,41 minimising on the
weighted R factor wR2. Anisotropic thermal parameters were
used for all non-H atoms with hydrogen atoms placed at calcu-
lated positions and fixed, with isotropic thermal parameters
(U = 0.08 Å3), riding on the supporting atom. The trifluoro-
methanesulfonate anion of 2 was disordered; a similarity
restraint was applied to the C–F bond lengths in order to obtain
satisfactory refinement. The hydride in 3 was not located in the
difference map and was positioned to complete the pseudo-
tetrahedral geometry around the tungsten centre. A dummy
atom representing the hydride ligand was placed in the requisite
position, as shown in Fig. 2, for illustrative purposes, but was
not included in any refinement. The hydride ligand in 4 was
placed at a site of electron density located on the difference
map, and the W–H bond length was fixed at 1.6 Å.42
15 I. S. Gonçalves and C. C. Romão, J. Organomet. Chem., 1995, 486,
155.
16 L. Labella, A. Chernega and M. L. H. Green, J. Chem. Soc., Dalton
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155.
18 S. L. J. Conway, T. Dijkstra, L. H. Doerrer, J. C. Green, M. L. H.
Green and A. H. H. Stephens, J. Chem. Soc., Dalton Trans., 1988,
2689.
19 A. J. Carmichael and A. McCamley, J. Chem. Soc., Dalton Trans.,
1995, 3125.
20 A. J. Carmichael and A. McCamley, J. Chem. Soc., Dalton Trans.,
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21 R. Thomas, C. B. Shoemaker and K. Eriks, Acta Crystallogr., 1966,
21, 12.
22 W. Maier, Angew. Chem., 1961, 73, 120.
23 M. J. Calhorda, A. R. Dias, M. T. Duarte, A. M. Martins, P. M.
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24 T. S. Cameron, T. M. Klapotke, A. Schulz and J. Valkonen, J. Chem.
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25 A. C. Filippou, A. R. Dias, A. M. Martins and C. C. Romão,
J. Organomet. Chem., 1993, 455, 129.
26 K. Prout and G. V. Rees, Acta Crystallogr., Sect. B, 1974, 30, 2717.
27 F. W. S. Benfield and M. L. H. Green, J. Chem. Soc., Dalton Trans.,
1974, 1324.
28 J. P. McNally and N. J. Cooper, Organometallics, 1988, 7, 1704.
29 N. Piccolrovazzi, P. Pino, G. Consiglio, A. Sironi and M. Moret,
Organometallics, 1990, 9, 3098.
30 L. S. Bartell, E. A. Roth, C. D. Hollowell, K. Kuchitsu and J. J. E.
Young, J. Chem. Phys., 1965, 11, 2683.
31 S. A. Cohen, P. R. Auburn and J. E. Bercaw, J. Am. Chem. Soc.,
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32 P. Binger, P. Muller, R. Benn, A. Rufinska, B. Gabor, C. Kruger and
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33 L. J. Guggenberger, P. Meakin and F. N. Tebbe, J. Am. Chem. Soc.,
1974, 95, 5420.
CCDC reference number 186/1859.
See http://www.rsc.org/suppdata/dt/a9/a909732e/ for crystal-
lographic files in .cif format.
Acknowledgements
We acknowledge the EPSRC for providing an Earmarked stu-
dentship (to A. J. C.).
34 R. A. Forder, I. W. Jefferson and K. Prout, Acta Crystallogr.,
Sect. B, 1975, 31, 618.
35 E. J. M. Hamilton, D. E. Smith and A. J. Welch, Acta Crystallogr.,
Sect. C, 1987, 43, 1214.
36 F. M. Miao and K. Prout, Acta Crystallogr., Sect. B, 1982, 38, 945.
37 A. Chernega, J. Cook, M. L. H. Green, L. Labella, S. J. Simpson,
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38 A. J. Carmichael, Ph.D. Thesis, University of Warwick, 1997.
39 R. L. Cooper and M. L. H. Green, J. Chem. Soc. A, 1967, 1155.
40 G. M. Sheldrick, SHELXTL 5.0, Siemens Analytical Instruments,
Madison, WI, 1994.
41 G. M. Sheldrick, SHELXTL 96, University of Göttingen, 1996.
42 R. J. Klinger, J. C. Huffman and J. K. Kochi, J. Am. Chem. Soc.,
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43 T. Debaerdemaeker and A. Kutoglu, Acta Crystallogr., Sect. B,
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44 B. R. Davis and I. Bernal, J. Cryst. Mol. Struct., 1972, 2, 135.
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