Complexes of tungsten(IV,VI) derived from linked aryloxide ligands

Article abstract of DOI:10.1016/j.poly.2005.12.008

Biphenoxo complexes of tungsten(VI), [WCl₄{CHR[C₆H₂(Bu^t)₂O]₂}] R = H (1), Me (2) are reduced by Na/Hg in the presence of PMe₃ to give cis, trans-WCl₂(PMe₃)₂{CHR[C₆H₂(Bu^t)₂O]₂} R = H (3), Me (4). Reaction of [WOCl₄] with the biphenols 2,2′-CHR[C₆H₂(Bu^t)₂OH]₂ in diethyl ether gives [WOCl₂{CHR[C₆H₂(Bu^t)₂O]₂}] R = H (5), Me (6). Similar treatment of [W(NPh)Cl₄(Et₂O)] gives the complex [W(NPh)Cl₃{(1,1′-O,OH)(2,2′-CH₃CH)[4,6-(Bu^t)₂C₆H₂]₂}] (7) containing the monoanionic ligand {(1,1′-O,OH)(2,2′-CH₃CH)[4,6-(Bu^t)₂C₆H₂]₂}^-. Reaction of [WOCl₄] with the linear triphenol 2,6-bis(3,5-di-t-butyl-2-hydroxybenzyl)-4-methylphenol, HOArCH₂Ar¹(OH)CH₂ArOH (Ar = 4,6-di-t-butylphenol; Ar¹ = 4-methylphenyl), in refluxing toluene affords the centrosymmetric complex {WOCl[OArCH₂Ar¹(O)CH₂ArO]}₂ (8), in which the mer-tridentate ligands adopt the U-conformation. The related complex {WOCl[OAr²CH₂Ar³(O)CH₂Ar²O]} (9) has been isolated as a hydrolysis product from the reaction of [W(NPh)Cl₄(Et₂O)] and 2,6-(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-t-butylphenol, HOAr²CH₂Ar³(OH)CH₂Ar²OH (Ar² = 4-methyl-6-t-butylphenol; Ar³ = 4-t-butylphenyl), and is also available via [WOCl₄]. Reaction of [W(eg)₃] (eg = 1,2-ethanediolato) with 2,6-bis(3,5-methyl-2-hydroxybenzyl)-4-t-butylphenol, HOAr⁴CH₂Ar³(OH)CH₂Ar⁴OH(Ar⁴ = 4,6-di-methylphenol) affords [W(eg)₂(OAr⁴CH₂Ar³(O)CH₂Ar⁴OH)] (10), containing a chelating biphenolate ligand with a pendant phenolic group. Crystal structures of complexes 1, 3, 5, 8, 9 and 10 are reported.

Full text of DOI:10.1016/j.poly.2005.12.008

Polyhedron 25 (2006) 1946–1954
www.elsevier.com/locate/poly
Complexes of tungsten(IV,VI) derived from linked aryloxide ligands
a,
b,1
Carl Redshaw *, Simon M. Humphrey
a
Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, NR4 7TJ, UK
b
The University Chemistry Laboratory, Lensfield Road, Cambridge, CB2 1EW, UK
Received 23 November 2005; accepted 15 December 2005
Available online 27 January 2006
Abstract
Biphenoxo complexes of tungsten(VI), [WCl4{CHR[C6H2(But)2O]2}] R = H (1), Me (2) are reduced by Na/Hg in the presence of
PMe3 to give cis, trans-WCl2(PMe3)2{CHR[C6H2(But)2O]2} R = H (3), Me (4). Reaction of [WOCl4] with the biphenols 2,20-
CHR[C6H2(But)2OH]2 in diethyl ether gives [WOCl2{CHR[C6H2(But)2O]2}] R = H (5), Me (6). Similar treatment of [W(NPh)Cl4(Et2O)]
gives the complex [W(NPh)Cl3{(1,10-O,OH)(2,20-CH3CH)[4,6-(But)2C6H2]2}] (7) containing the monoanionic ligand {(1,10-O,OH)(2,20-
CH3CH)[4,6-(But)2C6H2]2}ꢀ. Reaction of [WOCl4] with the linear triphenol 2,6-bis(3,5-di-t-butyl-2-hydroxybenzyl)-4-methylphenol,
HOArCH2Ar1(OH)CH2ArOH (Ar = 4,6-di-t-butylphenol; Ar1 = 4-methylphenyl), in refluxing toluene affords the centrosymmetric
complex {WOCl[OArCH2Ar1(O)CH2ArO]}2 (8), in which the mer-tridentate ligands adopt the U-conformation. The related complex
{WOCl[OAr2CH2Ar3(O)CH2Ar2O]} (9) has been isolated as a hydrolysis product from the reaction of [W(NPh)Cl4(Et2O)] and 2,6-
(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-t-butylphenol, HOAr2CH2Ar3(OH)CH2Ar2OH (Ar2 = 4-methyl-6-t-butylphenol; Ar3 = 4-t-
butylphenyl), and is also available via [WOCl4]. Reaction of [W(eg)3] (eg = 1,2-ethanediolato) with 2,6-bis(3,5-methyl-2-hydroxyben-
zyl)-4-t-butylphenol, HOAr4CH2Ar3(OH)CH2Ar4OH(Ar4 = 4,6-di-methylphenol) affords [W(eg)2(OAr4CH2Ar3(O)CH2Ar4OH)] (10),
containing a chelating biphenolate ligand with a pendant phenolic group. Crystal structures of complexes 1, 3, 5, 8, 9 and 10 are reported.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Tungsten; Aryloxides; Chelating; Crystal structures
1. Introduction
for Mo and W [4]. Group 4 and 5 metal derivatives of
2,20-methylene-bis(6-phenylphenoxide) have also been
reported [4b]. In general, the resulting 8-membered chelate
rings derived from the doubly deprotonated biphenol
adopt a flattened boat conformation. Tungsten complexes
containing bis(aryloxo) ligands with bridges formed by
either CHR (R = H or Me), S, Te or CH2 have also been
reported and their use in the ring-opening polymerisation
of norbornene investigated [5]. More recently, a number
of aluminium complexes have appeared in the literature
including four-coordinate cationic species, as well as
dimeric alkoxyaluminium species [6]. The related linear tri-
phenolate ligands are also attracting increasing attention
[7], and their limited reported coordination chemistry has
been reviewed by Kawaguchi and Matsuo [8].
The successful use of chelating aryloxide ancillary
ligands to provide control of molecular weight and poly-
mer microstructure during a-olefin polymerization has
stimulated synthetic efforts in this area of transition metal
coordination chemistry [1]. In particular, complexes incor-
porating chelating diaryloxide ligands of the form [CHR-
{4-R0,6-R00C6H2O}2]
(R = H,
Me;
R0 = R00 = But;
R0 = Me, R00 = But) have been structurally characterised
for a number of early transition metals, including V, Ti,
Zr and Ta [2,3] together with dinuclear (d3–d3) species
*
Corresponding author.
E-mail address: carl.redshaw@uea.ac.uk (C. Redshaw).
Present address: Department of Chemistry, University of California,
As part of our on-going investigations into constrained
geometry ligand–metal environments [9], we recently
reported vanadyl complexes bearing bi- or triphenolate
1
Berkeley, CA 94720, USA and the Chemical Sciences Division, Lawrence
Berkeley National Laboratory.
0277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.12.008

C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
1947
OH
OH
OH
OH
R
OH
R
R
R1
R1
R1
R2
R1
R = R1 = tBu, R2 = Me (C)
R = R2 = tBu, R1 = Me (D)
R = R1 = Me, R2 = tBu (E)
R = H, R1 =Me (A)
R = Me, R1 = tBu (B)
Scheme 1.
Cl
O
Cl
PMe3
Cl
Cl
Cl
Cl
O
Cl
W
Cl
W
W
O
O
O
O
O
But
But
But
But
But
But
PMe3
R
R
R
1 (R = H)
2 (R = Me)
3 (R = H)
4 (R = Me)
5 (R = H)
6 (R = Me)
R1
R2
R1
R
O
W
O
R
Cl
O
O
O
O
OH
O
O
Cl
PhN
W
O
Cl
O
W
OH
Cl
O
But
O
O
But
O
W
O
R
Cl
R
But
10
R2
R1
R1
7
R=R1=But, R2 = Me (8)
R=R2=But, R1 = Me (9)
Scheme 2.
ancillary chelate ligands. Such vanadyl species were found
to be extremely active for the polymerisation of ethylene,
when combined with dimethylaluminium chloride
(DMAC) [9b]. Related niobium pro-catalysts were much
less active under similar conditions [9c]. In an attempt to
more fully understand the coordinating characteristics of
these chelating aryloxides, we have extended our investiga-
tions to high valent tungsten, which is known to exhibit
rich aryloxide chemistry [10]. Here, new tungsten(IV and
VI) complexes incorporating linked aryloxide ligands
derived from the triphenols A and B, and the trisphenols
C, D and E are reported – see Schemes 1 and 2.
CHR[4,6-(But)2C6H2OH]2 (R = H (A), Me (B)) in either
refluxing CCl4 or toluene readily gives multi-gram quanti-
ties of [WCl4{2,20-CHR[4,6-(But)2C6H2O]2}] R = H (1),
Me (2) as dark purple/black solids. Both 1 and 2 can be
recrystallized from CH2Cl2 as dark purple needles and
the structure of 1 was determined by a single crystal X-
ray analysis. The tungsten centre (Fig. 1) is pseudo octahe-
dral and resembles those found in the cis-aryloxide com-
plexes [WCl4(OC6H3-2,6-R2)2] (R = Ph, iPr) [10a,10e].
˚
The W–O bond lengths [1.848(3)–1.8621(4) A] are typical
[10], and the chelate bite angle is 92.52(15)ꢁ, with the 8-
membered metallocyclic ring adopting the boat conforma-
tion. Selected bond lengths and angles are given in Table 1
and crystallographic data is presented in Table 3.
2. Results and discussion
The reduction of 1 or 2 with sodium amalgam in toluene
in the presence of PMe3 gives red/brown prisms of the cis,
trans-tungsten(IV) complexes [WCl2(PMe3)2{2,20-CHR-
[4,6-(But)2C6H2O]2}] R = H (3), Me (4), respectively. For
4, the 31P NMR spectrum consists of a singlet at d
ꢀ8.8 ppm; 183W satellites are present [J(P–W) = 222 Hz].
2.1. Diphenolates
The starting material [WCl6] has been used previously
for the synthesis of aryloxides of tungsten(VI) [10a,10b].
The reaction of [WCl6] and the biphenol ligands 2,20-

1948
C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
Fig. 1. ORTEP diagram of [WCl4{2,20-CH2[4,6-(But)2C6H2O]2}] (1).
Ellipsoids are shown at 50% probability levels.
Fig. 2. ORTEP diagram of [WCl2(PMe3)2{2,20-CH2[4,6-(But)2C6H2O]2}]
(3). Ellipsoids are shown at 50% probability levels.
Table 1
˚
Bond lengths (A) and angles (ꢁ) for diphenolate complexes
1
3
5
tion were grown from a saturated hexane solution at 0 ꢁC.
The molecular structure is shown in Fig. 3; the geometrical
parameters – see Table 1 (and spectroscopic data), are very
similar to those reported by Takashima et al. for the same
product obtained in refluxing THF and crystallised form
hexane/toluene [5].
A similar reaction of [W(NPh)Cl4(Et2O)] with the biphe-
nol 2,20-CH3CH[4,6-(But)2C6H2OH]2 in diethyl ether at
ꢀ78 ꢁC leads to [W(NPh)Cl3{(1,10-O,OH)(2,20-CH3CH)-
[4,6-(But)2C6H2]2}] (7) in which the diphenol coordinates
in a bidentate monoanionic form. Conformation of the
monoanionic bonding is provided by IR spectra, where a
band at 3492 cmꢀ1 can be assigned as the stretch of the
OH group. It is noteworthy that reaction of catechol with
Bond lengths
W(1)–O(1)
W(1)–O(2)
W(1)–O(3)
W(1)–Cl(1)
W(1)–Cl(2)
W(1)–Cl(3)
W(1)–Cl(4)
W(1)–P(1)
W(1)–P(2)
1.848(3)
1.862(4)
1.933(2)
1.850(4)
1.854(4)
1.678(4)
2.319(2)
2.322(2)
2.341(2)
2.324(1)
2.344(1)
2.327(1)
2.4081(9)
2.535(1)
2.566(1)
Bond angles
O(1)–W(1)–O(2)
O(1)–W(1)–O(1A)
Cl(1)–W(1)–Cl(2)
Cl(1)–W(1)–Cl(1A)
P(1)–W(1)–P(2)
92.5(2)
89.6(2)
99.85(12)
82.61(5)
176.9(1)
85.35(6)
176.36(5)
[WOCl4] has also been found to give
a complex
[W(O)Cl(O2C6H4)(O,OHC6H4) Æ OEt2] (see F below) con-
taining a chelating monoanionic ligand [11].
The molecular structure of 3 is shown in Fig. 2; selected
bond lengths and angles are given in Table 1. The molecule
has approximate octahedral geometry with trans-
phosphines, but cis-chlorines that are coplanar with the
dioxometallacycle. This arrangement contrasts with the
trans, trans, trans-WCl2O2P2 core observed for the related
aryloxide complex [WCl2(OC6H3-2,6-Ph2)2(PMe2Ph)2]
[10c], and reflects the geometrical constraints imposed by
the chelating ligand. In 3, there is evidence of a trans-
phosphine influence: the mutually trans, formally chemi-
cally equivalent phosphines quite unexpectedly differ in
˚
bond lengths [2.535(1) and 2.556(1) A], a phenomenon
ascribed to competitive p-back bonding. The diphenolate
binds symmetrically with equal W–O–C angles [133.7(2)ꢁ],
a bite angle of 99.8(1)ꢁ and adopts the flattened boat con-
formation seen previously.
The reaction of an ethereal solution of [WOCl4] with the
biphenols A and B forms [WOCl2{2,20-CHR[4,6-(But)2-
C6H2O]2}] R = H (5), Me (6) in good yields (55–60%).
Crystals of 5 suitable for a single crystal X-ray determina-
Fig. 3. ORTEP diagram of [WOCl2{2,20-CH2[4,6-(But)2C6H2O]2}] (5).
Ellipsoids are shown at 50% probability levels.

C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
1949
ligands, which adopts a U conformation. The W@O bond
length [1.689(5) A] is typical. The two halves of the mol-
NPh
W
˚
Cl
Cl
O
W
O
Cl
O
ecule in 8 (space group C2/c, Z = 4) are related by an
inversion site located at the centre of the W2O2 square.
The core of the structure is reminiscent of that observed
in a number of other tungsten(VI) oxo alkoxides –
edge-shared bioctahedral structures featuring asymmetric
alkoxide bridges, which are coplanar with terminal oxo
ligands [10c].
Similar reaction of [W(NPh)Cl4(Et2O)] with triphenol D
2,6-(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-t-butylphenol,
HOAr2CH2Ar3(OH)CH2Ar2OH (Ar2 = 4-methyl-6-t-but-
ylphenol; Ar3 = 4-t-butylphenyl) afforded, on work-up,
brown blocks of the hydrolysis product {WOCl[OAr2CH2-
Ar3(O)CH2Ar2O]} (9). Complex 9 can also be prepared
directly from the reaction of [WOCl4] and D. The molecular
But
Cl
O
OH
O
OH
But
But
Et2O
But
7
F
For
2,20-methylenebis(6-tert-butyl-4-methylphenol),
2,20-CH2[4-Me,6-(But)C6H2OH]2, it has previously been
noted that the 1H NMR resonances for the methylene
bridge protons are sensitive to the changes in the metal
coordination sphere [3a]. A similar situation is found in
this work for both diphenols 2,20-CHR[4,6-(But)2-
C6H2OH]2) (R = H, Me), where dramatic changes in shifts
are noted particularly for the CH proton of the bridge. For
example, CH resonances for 1 and 5 (all recorded in
CDCl3) occur at d 5.80, 3.99 and 4.11, 3.72, respectively.
Table 2
˚
Bond lengths (A) and angles (ꢁ) for triphenolate complexes
8
9
10
2.2. Triphenolates
Bond lengths
W(1)–O(1)
W(1)–O(2)
W(1)–O(3)
W(1)–O(4)
W(1)–O(5)
W(1)–O(6)
W(1)–O(7)
W(1)–O(2A)
W(1)–Cl(1)
1.886(5)
2.207(5)
1.892(5)
1.689(5)
1.890(3)
2.198(3)
1.883(3)
1.698(3)
1.865(2)
1.951(2)
The interaction of [WOCl4] with the linear triphenol
ligand HOArCH2Ar1(OH)CH2ArOH (Ar = 4,6-di-t-butyl-
phenol; Ar1 = 4-methylphenyl) C, in refluxing toluene
yielded, on work-up, the complex {WOCl[OArCH2Ar1
(O)CH2ArO]}2 (8), in good yield (ca. 55%). Crystals of
8, suitable for a single crystal X-ray diffraction study,
were obtained from a saturated acetonitrile solution on
prolonged standing at ambient temperature. The molecu-
lar structure is shown in Fig. 4, with selected bond lengths
and angles given in Table 2. The two pseudo octahedral
tungsten centres are linked via asymmetric aryloxide
1.910(2)
1.896(2)
1.914(2)
1.908(2)
2.053(2)
2.335(2)
2.074(3)
2.341(1)
2.319(2)
Bond angles
W(1)–O(1)–W(1A)
O(1)–W(1)–O(3)
O(1)–W(1)–O(2)
O(1)–W(1)–O(4)
O(4)–W(1)–O(5)
113.9(2)
162.6(2)
86.1(2)
96.5(2)
115.8(1)
164.7(1)
86.3(1)
96.1(1)
85.65(8)
85.84(8)
79.13(9)
˚
bridges [W–O 2.053(5) and 2.207(5) A], the bridges each
derived from one of the facially bound triphenolate
Fig. 4. (left) Structural diagram of the dimeric unit {WOCl[OArCH2Ar1(O)CH2ArO]}2 (8). Hydrogen atoms have been omitted for clarity; (right)
ORTEP view of the asymmetric unit of 8.

1950
C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
structure (Fig. 5) has the same dimeric form as isostructural
8, while geometrical parameters are also similar (see Table 2
and Fig. 6).
The complex [W(eg)3] has recently been used as a pre-
cursor for tungsten aryloxide synthesis [5b,12]. Interaction
of [W(eg)3] with triphenol E 2,6-bis(3,5-methyl-2-hydrox-
Table 3
Crystallographic data
Compound
1
3
5
8
9
10
Formula
C
664.12
monoclinic
P21/c
23H30Cl4O2W
C29H48Cl2P2O2W
745.36
orthorhombic
Pnma
C23H30Cl2O3W
609.22
monoclinic
C2/c
C74H98Cl2O8W2
1554.12
monoclinic
C2/c
C68H86Cl2O8W2
1469.97
monoclinic
P21/c
C32H40O7W
720.49
triclinic
Formula weight
Crystal system
Space group
ꢀ
P1
Unit cell dimensions
˚
a (A)
9.6768(2)
27.0312(4)
9.6976(2)
90
100.4067(7)
90
16.4685(3)
16.5175(3)
12.1414(3)
90
90
90
29.7734(4)
10.9410(2)
19.1098(4)
90
128.6050(10)
90
24.8831(3)
10.8875(1)
29.2577(4)
90
98.5187(4)
90
16.6019(2)
20.2365(2)
19.3438(3)
90
105.0695(4)
90
11.3314(1)
11.8523(1)
12.2420(2)
112.4766(6)
94.7475(6)
91.4843(8)
1511.07(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
2494.93(8)
4
3302.68(12)
4
4864.65
8
7838.89(16)
4
6275.34(14)
4
Z
Absorption
5.076
3.779
4.989
3.048
3.802
3.868
coefficient, l (mmꢀ1
Crystal size (mm)
hmax (ꢁ)
)
0.18 · 0.07 · 0.02
27.49
0.14 · 0.12 · 0.12
27.47
0.18 · 0.04 · 0.02
27.51
0.12 · 0.10 · 0.05
20.39
0.18 · 0.12 · 0.10
28.73
0.18 · 0.16 · 0.12
29.15
Reflections measured
Unique reflections
Reflections with
F2 > 2r(F2)
21582
5693
22883
3906
21422
5560
25940
3847
40691
16141
17614
8073
Transmission factors
Rint
0.607–0.904
0.0644
0.575–0.644
0.0609
0.4671–0.9068
0.0732
0.801–0.940
0.0715
0.5477–0.7023
0.0568
0.573–0.637
0.0350
Number of parameters
271
0.0418
0.0557
1.027
207
0.0291
0.0451
1.058
262
0.0422
0.0685
1.043
388
0.0369
0.0454
1.098
721
0.0375
0.0606
1.013
437
0.0251
0.0286
1.055
Ra [F2 > 2r(F2)]
b
Rw (all data)
Goodness-of-fitc (S)
Largest difference
peak and hole (e A
1.748 and ꢀ4.694
1.224 and ꢀ0.646
0.887 and ꢀ1.592
1.509 and ꢀ0.469
1.206 and ꢀ2.286
0.801 and ꢀ1.341
ꢀ3
˚
)
P
P
a
b
c
Conventional R = iFo| ꢀ |Fci/ |Fo| for ‘observed’ reflections having F2 > 2r(F2).
P
P
2
2 1=2
Rw ¼ ½ wðF 2o ꢀ F 2c Þ = wðF 2oÞ ꢁ for all data.
P
2
1=2
S ¼ ½ wðF 2o ꢀ F 2c Þ =ðno. of unique reflections ꢀ no. of parametersÞꢁ
.
Fig. 5. ORTEP diagram of {WOCl[OAr2CH2Ar3(O)CH2Ar2O]} (9). Ellipsoids are shown at 50% probability levels. Only half the molecule is shown for
clarity.

C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
1951
But
Me
1.883
1.892
But
But
2.341
2.335
O
O
2.198
O
2.207
O
Cl
Cl
But
But
W
W
1.689
1.698
O
O
O'
O'
2.074
2.053
O
O
But
But
But
Me
1.890
1.886
9
8
Fig. 6. Selected geometrical parameters associated with 8 and 9.
ybenzyl)-4-t-butylphenol, HOAr4CH2Ar3(OH)CH2Ar4OH
(Ar4 = 4,6-di-methylphenol) in refluxing toluene afforded
the orange complex [W(eg)2(OAr4CH2Ar3(O)CH2Ar4OH)]
(10) in good yield. Crystals suitable for an X-ray determi-
nation were grown from a saturated solution of acetonitrile
at room temperature. The molecular structure is shown in
Fig. 7. The tungsten centre is pseudo octahedral with coor-
dination sites occupied by two chelating 1,2-ethanediolato
ligands and a bidentate chelate ligand [bite angle =
85.65(8)ꢁ] derived from the triphenol E for which one of
the phenolic groups remains unbound (pendant). The 8-
membered metallocyclic ring adopting the boat conforma-
tion similar to that observed in the diphenolate complexes
1, 3 and 5, whilst the core geometry at tungsten resembles
that reported for the diphenolate complexes [W(eg)2L]
(L = 2,20-methylenebis(6-methylphenolate) and 2,20-meth-
ylenebis(6-isopropylphenolate) reported by Lehtonen and
Sillanpa¨a¨ [12b].
ligands. Further catalytic studies using these ligand systems
will be published elsewhere.
3. Experimental
3.1. General
All manipulations were carried out under an atmosphere
of nitrogen using standard Schlenk and cannula techniques
or in a conventional nitrogen-filled glove-box. Solvents
were refluxed over an appropriate drying agent, and dis-
tilled and degassed prior to use. Elemental analyses were
performed by the microanalytical services of the Depart-
ment of Chemistry at Durham and Medac Ltd. NMR spec-
tra were recorded on a Varian VXR 400 S spectrometer at
399.9 MHz (1H), and 161.9 MHz (31P); chemical shifts are
referenced to the residual protio impurity of the deuterated
solvent; IR spectra (nujol mulls, CsI windows), Perkin–
Elmer 577 and 457 grating spectrophotometers; [WOCl4],
[W(NPh)Cl4(Et2O)] and [W(eg)3] were prepared by litera-
ture methods [13–15]. Trimethylphosphine was prepared
by the method of Wolfsberger and Schmidbaur [16]. The
triphenol ligands C–E were prepared by the methods of
Scott [7a]. All other chemicals were obtained commercially
and used as received unless stated otherwise.
In conclusion, the compounds described herein provide
useful insight into the coordination environment afforded
by the deprotonated forms of both bi- and tri-phenolate
3.2. Preparation of [WCl4{2,20-CH2-
[4-Me,6-But-C6H2O]2}] (1)
[WCl6] (1.00 g, 2.52 mmol) and the diphenol A (0.93 g,
2.52 mmol) were combined in a dry-box. The system was
then refluxed for 12 h in either CCl4 or toluene (ca.
50 cm3) to give a dark purple/black solid. This solid was
washed with cold pentane (50 cm3) and dried in vacuo.
Yield: 1.24 g, 74%. Found: C, 42.1; H, 4.7%.
WCl4O2C23H30 requires: C, 41.6; H, 4.6%. IR: 1599m,
1161w, 1140w, 1093bs, 1019bs, 917w, 871w, 865w, 799s.
1H NMR (CDCl3): d 7.34 (d, 2H, JHH = 2.0 Hz, arylH),
7.25 (d, 2H, JHH = 1.5 Hz, arylH), 5.80 (d, 1H,
JHH = 13.9 Hz, CH2), 3.99 (d, 1H, JHH = 13.9 Hz, CH2),
3.17 (s, 6H, CH3), 1.57 (s, 18H, (CH3)3C).
Fig. 7. Structural diagram of [W(eg)2(OAr4CH2Ar3(O)CH2Ar4OH)] (10).
Ellipsoids are shown at 50% probability levels.

1952
C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
3.3. Preparation of [WCl4{2,20-CH3CH-
solid residue was extracted with pentane. Filtration, reduc-
tion (to ca. 30 cm3) and cooling (ꢀ20 ꢁC) gave dark green
cubes. Yield: 1.13 g, 63%. Found: C, 46.1; H, 5.2%.
WCl2O3C23H30 requires: C, 45.3; H, 5.0%. IR: 1300w,
1261s, 1094bs, 1020bs, 986m, 941w, 930w, 800s, 722m.
[4,6-(But)2C6H2O]2}] (2)
[WCl6] (3.39 g, 8.5 mmol) and the diphenol B (3.76 g,
8.6 mmol) were combined in a dry-box. The system was
then refluxed for 12 h in either CCl4 or toluene (ca.
50 cm3) to give a dark purple/black solid. This solid was
washed with cold pentane (50 cm3) and dried in vacuo.
Yield: 4.1 g, 62%. The compound can be crystallized from
CH2Cl2 (ꢀ20 ꢁC). Found: C, 46.9; H, 5.5%.
WCl4O2C30H44 requires: C, 47.2; H, 5.8%. IR: 1583s,
1540w, 1363s, 1336w, 1261m, 1237m, 1200m, 1166s,
1157s, 1093s, 1022s, 927w, 908m, 885s, 875m, 800s,
769m, 759w, 749w, 723w, 684w, 657w, 628w, 565w,
4
1H NMR (CDCl3): d 6.97 (d, 2H, JHH 2.0 Hz, arylH),
4
2
6.95 (d, 2H, JHH 2.0 Hz, arylH), 4.11 (d, 1H, JHH
2
16.1 Hz, CH2), 3.72 (d, 1H, JHH 15.9 Hz, CH2), 2.37 (s,
6H, 4-Me), 1.31 (s, 18H, (CH3)3C).
3.7. Preparation of [WOCl2{2,20-CH3CH-
[4,6-(But)2C6H2O]2}] (6)
To a solution of [WOCl4] (1.00 g, 2.94 mmol) in diethyl
ether (ca. 40 cm3) at ꢀ78 ꢁC was added the diphenol B
(1.29 g, 2.94 mmol). After stirring the green solution at
25 ꢁC (12 h), the volatiles were removed in vacuo and the
solid residue was extracted with pentane. Filtration, reduc-
tion (to ca. 30 cm3) and cooling (ꢀ20 ꢁC) gave dark green
cubes. Yield: 1.14 g, 55%. Found: C, 54.1; H, 6.8%.
WCl2O3C35H56 (pentane solvate) requires: C, 53.9; H,
7.2%. IR: 1589m, 1367s, 1261s, 1224s, 1200w, 1162w,
1109s, 1022s, 998s, 927m, 904w, 873s, 800s, 772m, 722w,
1
444m, 357s, 318s, 308s. H NMR (CDCl3): d 7.56 (d, 2H,
JHH = 2.0 Hz, arylH), 7.37 (d, 2H, JHH = 2.4 Hz, arylH),
5.82 (q, 1H, JHH = 6.8 Hz, CH), 1.57 (d, 3H,
JHH = 7.2 Hz, CH3), 1.53 (s, 18H, (CH3)3C), 1.31 (s,
18H, (CH3)3C).
3.4. Preparation of [WCl2(PMe3)2{2,20-CH2-
[4-Me,6-But-C6H2O]2}] (3)
1
To a solution of 1 (1.00 g, 1.31 mmol) in toluene
(40 cm3) was added PMe3 (0.31 cm3, 3.0 mmol) and 0.2%
sodium amalgam (0.09 g, 4.0 mmol). After stirring for
12 h, the suspension was filtered and the volatiles were
removed in vacuo. The residue was dissolved in hexane
(40 cm3) and stored at 0 ꢁC for 2 days to afford 3 as large
red prisms. Yield: 0.47 g, 42%. Found: C, 46.3; H, 6.5%.
WCl2P2O2C29H48 requires: C, 46.7; H, 6.5%. IR: 1405m,
1286m, 1260s, 1229s, 1166m, 1120s, 1095bs, 1018bs,
953m, 918w, 900w, 861w, 848w, 831s, 796s, 737w, 722w,
567w.
635w, 570w, 475w, 368m. H NMR (CDCl3): d 7.16 (d,
2H, JHH = 2.4 Hz, arylH), 7.12 (d, 2H, JHH = 2.0 Hz,
arylH), 3.76 (q, 1H, JHH = 6.0 Hz, CH), 1.84 (d, 3H,
JHH = 6.4 Hz, CH3), 1.31 (s, 18H, (CH3)3C), 1.21 (s,
18H, (CH3)3C).
3.8. Preparation of [W(NPh)Cl3{(1,10-O,OH)-
(2,20-CH3CH)[4,6-(But)2C6H2]2}] (7)
To a solution of [W(NPh)Cl4(Et2O)] (1.00 g, 2.0 mmol)
in diethyl ether (ca. 40 cm3) at ꢀ78 ꢁC was added the
diphenol B (0.9 g, 2.1 mmol). After stirring at 25 ꢁC for
12 h, the volatiles were removed in vacuo and the residue
was extracted with heptane. Concentration (to ca.
25 cm3) and cooling (ꢀ20 ꢁC) gave brown prisms. Yield:
0.69 g, 40%. Found: C, 49.9; H, 5.1; N, 1.7%; Calc. for
C36H50O4NCl3W: C, 50.8; H, 5.9; N, 1.7%. IR: 3492m,
1595m, 1300m, 1260s, 1214s, 1170m, 1104s, 1027m,
924w, 882m, 864m, 804m, 761s, 726s, 681w. 1H NMR
(CDCl3): d 7.126 (m, 2H, arylH), 7.47 (m, 2H, arylH),
3.69 (q, 1H, JHH 6.0 Hz, CH), 1.97 (d, 3H, JHH 6.1 Hz,
CH3), 1.30 (s, 18H, (CH3)3C), 1.22 (s, 18H, (CH3)3C).
OH obscurred.
3.5. Preparation of [WCl2(PMe3)2{2, 20-CH3CH-
[4,6-(But)2C6H2O]2}] (4)
To a solution of 2 (2.00 g, 2.62 mmol) in toluene (ca.
50 cm3) was added PMe3 (0.6 cm3, 5.3 mmol) and a 0.2%
sodium amalgam (0.14 g Na, ca. 6 mmol). The mixture
was stirred rapidly for 24 h, filtered and pumped dry in
vacuo. Recrystallization from pentane at ꢀ20 ꢁC gave a
red crystalline solid. Yield: 1.45 g, 66%. Found: C, 50.8;
H, 7.4%. WCl2P2O2C36H62 requires: C, 51.2; H, 7.4%.
IR: 1311s, 1284s, 1260s, 1236s, 1206s, 1186s, 1142s,
1122s, 1086s, 1023s, 952s, 913m, 872m, 853m, 828s, 812s,
773m, 741s, 728s, 670m, 647m, 633s, 600m, 550s. 31P
NMR (CDCl3): d ꢀ8.8 [s, with satellites J(P–W) 222 Hz].
3.9. Preparation of {WOCl[OArCH2Ar0(O)CH2ArO]}2
Ar0 = 4-methylphenyl (8)
3.6. Preparation of [WOCl2{2,20-CH2-
To a solution of [WOCl4] (1.00 g, 2.94 mmol) in diethyl
ether (ca. 40 cm3) at ꢀ78 ꢁC was added the triphenol C
(1.60 g, 2.94 mmol). The system was refluxed for 12 h, vola-
tiles were removed in vacuo, and the residue was extracted
into warm MeCN (30 cm3). Prolonged standing at ambient
temperature (2–3 days), afforded purple needles of 8. Yield:
0.98 g, 43%. Further crops can be obtained by concentration
[4-Me,6-But-C6H2O]2}] (5)
To a solution of [WOCl4] (1.00 g, 2.94 mmol) in diethyl
ether (ca. 40 cm3) at ꢀ78 ꢁC was added the diphenol A
(1.08 g, 2.94 mmol). After stirring the green solution at
25 ꢁC (12 h), the volatiles were removed in vacuo and the

C. Redshaw, S.M. Humphrey / Polyhedron 25 (2006) 1946–1954
1953
of the mother-liquor. Total isolated yield 64%. Found: C,
60.8; H, 7.1%. Calc. for C74H104O8Cl2W2: C, 61.6; H,
7.2%. IR: 1594w, 1359m, 1293w, 1261s, 1241w, 1218w,
1155m, 1095bs, 1019bs, 973s, 910w, 880w, 872w, 852m,
796s, 767m, 753w, 722w, 666w, 601w, 570m, 514w, 506w,
Absorption corrections were made based on w- and x-
scans using the SORTAV program [18]. Structures were
solved using direct methods and refined on F2 using the
program SIR-92 [19] and then refined using SHELXTL-97 soft-
ware [20]. Geometrical restraints were applied to improve
refinement of PMe3 ligands in compound 3; all P–C bond
distances have been restrained using a single common free
variable, while Cꢂ ꢂ ꢂC distances were treated similarly, in
order to obtain idealized (tetrahedral) geometries for these
moieties. All non-hydrogen atoms were refined anisotropi-
cally for all structures. Aromatic H-atoms were fixed based
on idealised positions and their values of Uiso set to 1.5
times that of the carrier atom [21]. See Table 1 for further
crystallographic information.
1
472w, 455w. H NMR (CDCl3): d 7.27 (m, 8H, arylH),
2
7.09 (s, 4H, arylH), 5.07 (d, 4H, JHH 13.3 Hz, CH2), 3.50
2
(d, 4H, JHH 13.3 Hz, CH2), 2.27 (s, 6H, CH3), 1.40 (s,
36H, C(CH3)3), 1.24 (s, 36H, C(CH3)3).
3.10. Preparation of {WOCl[OArCH2Ar0(O)CH2ArO]}2
Ar0 = 4-tert-butylphenyl (9)
[W(NPh)Cl4(Et2O)] (1.00 g, 2.0 mmol) and triphenol D
(1.01 g, 2.01 mmol) were refluxed in toluene (30 cm3) for
12 h. On cooling, volatiles were removed in vacuo and
the residue was extracted into hexane (30 cm3). Cooling
to ꢀ20 ꢁC afforded brown blocks of 9 in 38% yield:
0.56 g. Alternatively, 9 can be prepared in ca. 60% yield
using [WOCl4] in the above procedure. Found: C, 54.8;
H, 6.1%. Calc. for C68H86O8Cl2W2: C, 55.6; H, 5.9%. IR:
1600w, 1293w, 1261s, 1206m, 1168m, 1096bs, 1019bs,
Acknowledgements
The University of East Anglia and Prof. V.C. Gibson
(Imperial College) are thanked for financial support. We
thank John Davies (Cambridge University) for help with
crystal structure determinations.
1
972m, 909w, 858m, 801s, 738m, 718m. H NMR (CDCl3):
Appendix A. Supplementary data
d 7.21–7.24 (m, 4H, arylH), 7.17 (s, 4H, arylH), 7.10 (s, 4H,
arylH), 5.05 (d, 4H, 2JHH 13.4 Hz, CH2), 3.52 (d, 4H, 2JHH
13.4 Hz, CH2), 2.49 (s, 12H, CH3), 1.42 (s, 36H, C(CH3)3),
1.19 (s, 18H, C(CH3)3).
Atomic coordinates, bond lengths and angles, displace-
ment parameters and hydrogen atom positions have been
deposited with the Cambridge Crystallographic Data Cen-
tre, with deposition codes CCDC 290126 – 290131. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK, fax: +44 1223 366 033, e-mail: deposit@ccdc.
ac.uk or on the web www: http://www.ccdc.cam.ac.uk. Sup-
plementary data associated with this article can be found, in
the online version, at doi:10.1016/j.poly.2005.12.008.
3.11. Preparation of [W(eg)2(OAr4CH2Ar3(O)-
CH2Ar4OH)] (10)
[W(eg)3] (1.00 g, 2.75 mmol) and triphenol E (2.27 g,
5.49 mmol) were refluxed in toluene for 12 h. Volatiles were
removed in vacuo and the residue was extracted into hot
MeCN (40 cm3). Prolonged standing at ambient tempera-
ture afforded 10 as orange needles. Yield: 1.08 g, 55%.
Found: C, 52.9; H, 5.1%. Calc. for C32H40O7W: C, 53.3;
H, 5.6%. IR: 3367w, 1304m, 1248m, 1214s, 1146m,
1099w, 1049m, 1030s, 944w, 913s, 878m, 840m, 781w,
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