Synthesis, characterization, and X-ray crystallography of a series of ditungsten complexes with bis(diphenylphosphino)amine

Article abstract of DOI:10.1016/S0022-328X(99)00610-5

The W₂(II, II) and W₂(III, III) compounds, W₂(μ-O₂CC₆H₅)₂Cl ₂(μ-dppa)₂ (1), W₂(μ-O₂CC₆H₅)₂Br ₂

Full text of DOI:10.1016/S0022-328X(99)00610-5

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 596 (2000) 136–143
Synthesis, characterization, and X-ray crystallography of a series
of ditungsten complexes with bis(diphenylphosphino)amine
Judith L. Eglin a,*, Laura T. Smith a , Richard J. Staples b , Edward J. Valente c,
Jeffrey D. Zubkowski d
a Department of Chemistry at Mississippi State Uni6ersity, Mississippi State, MS 39762, USA
b Department of Chemistry, Har6ard Uni6ersity, Cambridge, MA 02138, USA
c Department of Chemistry at Mississippi College, Clinton, MS 39058, USA
d Department of Chemistry at Jackson State Uni6ersity, Jackson, MS 39217, USA
Received 2 August 1999
Dedicated to Professor F.A. Cotton on the occasion of his 70th birthday.
Abstract
The W2(II, II) and W2(III, III) compounds, W2(m-O2CC6H5)2Cl2(m-dppa)2 (1), W2(m-O2CC6H5)2Br2(m-dppa)2 (2), W2(m-
O2CC6H5)2I2(m-dppa)2 (3), W2Cl4(m-dppa)2 (4), W2(m-Cl)2Cl4(m-dppa)2 (5), and W2(m-H)2Cl4(m-dppa)2 (6), have been synthesized
using the chelating phosphine ligand dppa (bis(diphenylphosphino)amine). The series of metal–metal multiply bonded complexes
has been characterized by NMR and UV–vis spectroscopy, and the structures of 2·(THF)2, 5·(THF)4, and 6·(THF)2 determined
by X-ray crystallography. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Ditungsten; Metal–metal multiple bond; Phosphine
the related W2(II, II) compound W2Cl4(dppa)2 and two
edge-sharing bioctahedral (ESBO) W2(III, III) com-
plexes, W2(m-Cl)2Cl4(m-dppa)2 and W2(m-H)2Cl4(m-
dppa)2 [6,8–11]
1. Introduction
The compounds W2(m-O2CC6H5)2Cl2(m-dppa)2 (1),
W2(m-O2CC6H5)2Br2(m-dppa)2 (2), W2(m-O2CC6H5)2-
I2(m-dppa)2 (3), W2Cl4(m-dppa)2 (4), W2(m-Cl)2Cl4(m-
dppa)2 (5), and W2(m-H)2Cl4(m-dppa)2 (6) have been
synthesized using a simpler synthetic route to multiply
bonded ditungsten complexes with the ability to easily
vary the coordinated ligands of W2(II, II) and related
compounds [1–6]. Previously, the potential of W2(m-
O2CC6H5)4 [7] as a starting material concentrated on
the use of the phosphine ligand dppm (bis-
(diphenylphosphino)methane) with ZnX2 as the halide
source to synthesize quadruply bonded complexes of
the general type W2(m-O2CC6H5)2X2(m-dppm)2 where X
is Cl, Br and I; the axially coordinated halide [4]. The
extension of this project to the chelating phosphine
dppa (bis(diphenylphosphino)amine) resulted in the
synthesis and spectroscopic characterization of a series
of W2(m-O2CC6H5)2X2(m-dppa)2 complexes as well as
2. Results and discussion
2.1. Preparation and general properties
Investigations in our laboratory have shown that the
quadruply bonded material W2(m-O2CC6H5)4 [7] pro-
vides a relatively stable, easily synthesized dinuclear
starting material for compounds of the general type
W2(m-O2CC6H5)2X2(dppm)2 where X is Cl, Br, and I
[4]. The original study of the reactivity of W2(m-
O2CC6H5)4 [7] with ZnX2 and dppm [4] has been ex-
tended to the chelating phosphine dppa with the
synthesis of the W2(m-O2CC6H5)2X2(m-dppa)2 series of
complexes with X=Cl, Br, and I.
In addition to the synthesis of the series of W2(m-
O2CC6H5)2X2(dppa)2 compounds, the related com-
* Corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00610-5

J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
137
pounds W2Cl4(m-dppa)2, W2(m-Cl)2Cl4(m-dppa)2, and
W2(m-H)2Cl4(m-dppa)2 have been prepared from WCl4
and dppa using NaBEt3H as the reducing agent
[4,12,13]. W2(m-H)2Cl4(m-dppa)2 is the third W2(III, III)
dihydride species synthesized in our laboratory. Other
compounds in the series are W2(m-H)2(m-O2CC6H5)2-
Cl2(P(C6H5)3)2 [6] and W2(m-H)2Cl4(m-dppm)2 [11]. Un-
like the synthesis of W2(m-H)2Cl4(m-dppm)2 that re-
quires heating of W2Cl4(m-dppm)2 in the presence of H2
[11], the formation of W2(m-H)2Cl4(m-dppa)2 occurs at
room temperature from the oxidative addition of H2 to
W2Cl4(m-dppa)2. The related ESBO compound W2(m-
Cl)2Cl4(m-dppa)2 results from a one-electron reduction
of WCl4 in the presence of dppa [3,14–17].
[7]. A similar trend is observed for the dimolybdenum
series of Mo2X4(m-dppa)2 and Mo2(m-O2CCH3)2X2(m-
dppa)2 complexes where X is Cl and Br [19]. However,
,
the W–W bond distance of 2·(THF)2 (2.2986(11) A)
and the related compound W2(m-O2CC6H5)2I2(m-dppm)2
,
(2.2925(6) A) [4] are essentially the same, with no
significant variation due to a change in the chelating
phosphine ligand. Of note in the structure of 2·(THF)2
is the presence of hydrogen bonding between interstitial
solvent and the amine protons of the dppa ligands (Fig.
1). The oxygen atoms of the THF solvent molecules are
,
1.957 A from the protons of the bridging N–H atoms
in the dppa ligands.
As expected [4], the W–Br bond distance of the
axially coordinated bromide in 2·(THF)2 is longer
,
(2.857(2) A) than observed for the equatorial W–Br
2.2. Structures
bond distances in W2Br4(m-dppm)2 of 2.507(3) and
,
2.520(3) A [12]. The difference in the distances of the
W–I bond distance of W2(m-O2CC6H5)2I2(m-dppm)2
(3.1033(7) A) and the W–Br bond distance of 2·(THF)2
The coordination geometry about the quadruply
bonded ditungsten core (s2p4d2) in both the dppm and
dppa series of W2(m-O2CC6H5)2X2(m-P-P)2 complexes
remains eclipsed without weakening of the d bond due
to incomplete overlap [18]. However, MO calculations
performed on the model compound W2(m-O2CH)2I2-
(PH3)4 demonstrate that the axial ligands effectively
reduce the strength of the W–W s bond [4]. Compared
to the W–W bond distance of W2Br4(m-dppm)2
,
reflects the change in ionic radius, I versus Br. The
W–W–Br bond angle of 2·(THF)2 is 171.97(4)° and
further studies of the W2(m-O2CC6H5)2X2(m-P-P)2 series
of complexes will focus on the substitution of the axial
halides.
The bond distances and angles of W2(m-Cl)2Cl4(m-
dppa)2·(THF)4 vary minimally from the bond distances
and angles observed in W2(m-Cl)2Cl4(m-dppm)2 with a
,
(2.2632(9) A), a slight increase in the metal–metal bond
distance is observed for W2(m-O2CC6H5)2Br2(m-dppa)2
Fig. 1. ORTEP drawing of W2(m-O2CC6H5)2Br2(m-dppa)2·(THF)2 (2·(THF)2). The thermal ellipsoids are drawn at 50% probability. With the
exception of the N–H atoms, hydrogen atoms have been omitted for clarity.

138
J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
,
H)2Cl4(m-dppm)2 [11] and 2.3500(12) A for W2(m-
H)2Cl2(PPh3)2(m-O2CC6H5)2 [6], W2(m-H)2Cl4(m-dppa)2·
(THF)2 contains the longest W–W bond distance ob-
served to date for a W2(III, III) ESBO dihydride com-
pound. As a result of the increase in the metal–metal
bond distance of 6·(THF)2, the W–H bond distances
,
are longer (2.025(20) and 2.134(20) A) than the W–H
bond distances observed previously in either W2(m-
,
H)2Cl4(m-dppm)2 (1.83(8) and 1.74(8) A) [11] or W2(m-
,
H)2Cl2(PPh3)2(m-O2CC6H5)2 (1.67(8) and 1.90(8) A) [6]
(Figs. 2 and 3). Analogous to the structure of 2·(THF)2,
the protons of the N–H in the dppa ligands are hydro-
,
gen bonded (1.986 and 2.208 A) to THF solvent
molecules.
2.3. NMR spectroscopy
The 31P-NMR spectrum for W2(m-O2CC6H5)2Br2(m-
dppa)2 (2) contains a singlet at 92.88 ppm with JW–P
coupling of 108 and 290 Hz. The 31P-NMR spectra of
1 and 3 are similar to that of 2 with singlets at 92.88
ppm (JW–P coupling of 116 and 288 Hz) and 92.91 ppm
(JW–P coupling of 113 and 297 Hz) respectively and
confirm the general structures of 1 and 3. Slight in-
creases in the chemical shift on progression through the
series from Cl to I are observed for both the dppa
ligand series 1–3 and the W2(m-O2CC6H5)2X2(m-dppm)2
series [4]. A large 31P chemical shift difference of ap-
proximately 47 ppm is observed between 1–3 and the
free phosphine ligand. A smaller 31P chemical shift
difference (D 23 ppm) is observed in comparison of 1–3
to W2Cl4(m-dppa)2, as observed for the analogous series
with dppm [4].
Fig. 2. ORTEP drawing of W2(m-Cl)2Cl4(m-dppa)2·(THF)4 (5·(THF)4).
The thermal ellipsoids are drawn at 50% probability. Hydrogen
atoms have been omitted for clarity.
The related dimolybdenum compounds, Mo2(m-
O2CCH3)2X2(m-dppa)2, have chemical shifts of 78.7
(Cl), 77.8 (Br), 75.2 (I), and 80.4 ppm (acetonitrile) with
the larger shift of the acetonitrile compound attributed
to the ionic character of the molecule [21,22]. A change
in the phosphine ligand in the dimolybdenum studies
from the dppa to the dppma (bis(diphenylphos-
phino)methylamine) ligand results in chemical shift dif-
ferences of 27 ppm from the free phosphine ligand for
Mo2(m-O2CCH3)2X2(m-dppma)2 in contrast to 36 ppm
observed for Mo2X2(m-O2CCH3)2(m-dppa)2 [23]. The ex-
treme sensitivity of the phosphorus chemical shift to the
nature of the bridging phosphine and carboxylate lig-
ands is demonstrated by the changes in chemical shift
upon a change in the bridging ligand for both the
ditungsten and dimolybdenum compounds [4,19,21–
23].
Fig. 3. ORTEP drawing of the W2(m-H)2Cl4P4 core of W2(m-H)2Cl4(m-
dppa)2·(THF)2 (6·(THF)2). The thermal ellipsoids are drawn at 50%
probability.
,
W–W bond distance of 2.691(1) A, W–Clb bond dis-
,
tances of 2.405(3) and 2.393(3) A, a W–Clb–W bond
angle of 68.23(9)°, and a W–W–Clt bond angle of
137.65° [20]. Unlike the structure of 2·(THF)2, the
closest oxygen atom of the THF solvent molecule is
,
3.105 A from the proton of the bridging amine of the
dppa ligand.
The 31P-NMR spectrum of W2Cl4(m-dppa)2 contains
a singlet at 69.9 ppm with JW–P coupling of 138 Hz.
The 31P-NMR spectrum of W2(m-H)2Cl4(m-dppa)2 con-
tains a singlet at 73.8 ppm and JW–P coupling of 145
Hz. The 31P-NMR chemical shifts of 4 and 6 are quite
similar with a difference of only 3.9 ppm, slightly larger
The W–W bond distance of the W2(III, III) ESBO
,
complex W2(m-H)2Cl4(m-dppa)2·(THF)2 (2.407(2) A) is
,
only 0.1 A longer than the quadruply bonded com-
pound W2(m-O2CC6H5)2Br2(m-dppa)2·(THF)2 and over
,
0.2 A shorter than W2(m-Cl)2Cl4(m-dppa)2·(THF)4. With
,
W–W bond distances of 2.3918(7) A for W2(m-

J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
139
than the chemical shift difference observed for
W2Cl4(m-dppm)2 and W2(m-H)2Cl4(m-dppm)2 (D 2.3
ppm) [4,11]. 31P-NMR spectra of the reaction mixture
of W2Cl4(m-dppa)2 obtained at intervals over several
hours indicate the formation of W2(m-H)2Cl4(m-dppa)2
potassium–sodium benzophenone ketyl and methylene
chloride was dried over P2O5. All solvents were freshly
distilled under an atmosphere of argon prior to use.
The starting material WCl4 was synthesized from WCl6
and W(CO)6 using the previously reported method [30].
The chelating phosphine ligand dppa was purchased
from Strem Chemicals and kept under dynamic vac-
uum overnight to remove any residual oxygen or mois-
ture. Tri-n-butyl phosphine was purchased from
Johnson Matthey, used without further purification,
and transferred under an atmosphere of argon.
NaO2CC6H5 was obtained from Matheson Coleman
and Bell, and all residual oxygen and moisture was
removed by heating the salt to 200° C for 6 h under
dynamic vacuum. NaBEt3H was purchased as a 1 M
solution in toluene from Aldrich Chemical Company
and used without further purification. ZnCl2, ZnBr2,
and ZnI2 were purchased from Aldrich Chemical Com-
pany and all transfers performed under an argon atmo-
sphere.
1
at room temperature. The H-NMR spectrum of W2(m-
H)2Cl4(m-dppa)2 confirmed the presence of the bridging
hydrides with a pentet observed at a chemical shift of
5.514 ppm with JH–P coupling of 6.4 Hz and JH–W
coupling of 109 Hz.
Based on Fenske–Hall calculations in the model
compound W2(m-H)2(m-O2CH)2(PH3)2Cl2,
a
W–W
triple bond is predicted (s2p2d2) with a large HOMO–
LUMO gap (ꢀ2.7 eV) [6]. The temperature indepen-
dence of the 31P-NMR spectra of W2(m-H)2Cl4-
(m-dppm)2 and the narrow linewidths of both the W2(m-
H)2Cl4(m-dppm)2 and W2(m-H)2Cl4(m-dppa)2 spectra
confirm the presence of a large HOMO–LUMO gap
and the diamagnetism of compounds of this type [11].
In contrast, magnetic studies of W2(m-Cl)2Cl4(m-dppm)2
reflect the partial occupancy of the d* orbital at r.t.,
and a magnetic moment of 0.70 B.M. is observed at
24°C [14,24]. The 31P-NMR spectrum of W2(m-
Cl)2Cl4(m-dppa)2 obtained at 23.5°C contained a broad
singlet, Dw1/2=329 Hz, at −23.5 ppm.
31P{1H}-NMR spectra (162 MHz) were recorded on
a General Electric instrument using an Omega NMR
spectrometer with a 10 mm broad band probe and
referenced externally to H3PO4 (0.0 ppm). 1H-NMR
spectra (400 MHz) were recorded on the same spec-
trometer with a 5 mm probe and referenced to TMS.
The UV–vis spectra were recorded on a Hewlett–
Packard 8452 model diode array spectrophotometer
from 190 to 820 nm. Magnetic susceptibility measure-
ments were performed on a Johnson Matthey Mag-
netic Susceptibility Balance and diamagnetic cor-
rections were applied [31].
2.4. UV–6is spectroscopy
Unlike the W2(m-O2CC6H5)2X2(m-dppm)2 series with
d to d* transitions at 454 nm for X=Cl, 438 nm for
X=Br, and 400 nm for X=I [4], the W2(m-
O2CC6H5)2X2(m-dppa)2 series does not vary systemati-
cally with
a change in halide. In the case of
W2(m-O2CC6H5)4, the presence of axial ligands in the
solutions for UV–vis spectroscopy resulted in absorp-
tion bands at shorter wavelengths by 30 nm as a result
of weakening of the W–W bond strength [7]. Without
additional structural information for the W2(m-
O2CC6H5)2X2(m-dppa)2 series, the basis [4,25–28] for
the changes in the UV–vis spectra across the series
[436 nm for X=Cl, 382 nm for X=Br, and 442 nm
for X=I] cannot be determined.
Analogous to the electronic spectra of other W2(III,
III) ESBO complexes, both the ligand-to-metal charge
transfer band (381 nm) and the prominent absorption
band between 450 and 550 nm (469 nm) are observed
in the UV–vis spectrum of W2(m-Cl)2Cl4(m-dppa)2 [29].
3.2. Preparation of W2(v-O2CC6H5)2Cl2(v-dppa)2 (1)
A gray mixture of WCl4 (0.500g, 1.54 mmol) and
NaO2CC6H5 (0.443 g, 3.07 mmol) was dissolved in 10
ml of THF and cooled to −70° C in an ethanol–dry
ice bath. After slow addition of 3.07 ml (3.07 mmol)
of NaBEt3H, the reaction was allowed to warm until
the color of the solution changed from the initial gray
to a brilliant purple. A THF (5 ml) solution of dppa
(0.592 g, 1.54 mmol) and ZnCl2 (0.320 g, 2.35 mmol)
was transferred by cannula to the purple solution,
and the ethanol–dry ice bath was removed. The solu-
tion turned a brick-red color within 30 min of warming
to room temperature (r.t.), and the complex was
precipitated with the addition of 30 ml of hexanes.
After washing the reaction mixture three times with
30 ml aliquots of hexanes, the remaining solvent was
removed under dynamic vacuum. The solid was
dissolved in THF, filtered through Celite, and dried
under dynamic vacuum to yield 1.57 g (70.4%) of a
brick-red product. Visible spectrum (THF, umax, nm):
436 sh.
3. Experimental
3.1. General procedures
Standard Schlenk, vacuum line, and drybox tech-
niques were used with an argon atmosphere. Commer-
cial grade THF, toluene, and hexanes were dried over

140
J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
3.3. Preparation of W2(v-O2CC6H5)2Br2(v-dppa)2 (2)
3.7. Preparation of W2(v-H)2Cl4(v-dppa)2 (6)
The bromide analog was obtained by the same
methodology used to synthesize W2(m-O2CC6H5)2Cl2(m-
dppa)2. ZnBr2 (0.346 g, 2.16 mmol) instead of ZnCl2
was used to yield W2(m-O2CC6H5)2Br2(m-dppa)2 (1.319
g, 55.8%). The amounts of starting material WCl4 and
the other reagents used were the same. Visible spectrum
(THF, umax, nm): 382 sh.
WCl4 (1.0 g, 3.07 mmol) was suspended in 10 ml of
THF. After the flask was cooled to −60°C in an
ethanol–dry ice bath, 6.14 ml of NaBEt3H (6.14 mmol)
was added. The reaction was allowed to warm to
−20°C and a green solution formed. Tri-n-butyl phos-
phine (1.52 ml, 6.14 mmol) was added, and the solution
allowed to warm to r.t. A THF (10 ml) solution of
dppa (1.18 g, 3.07 mmol) was transferred by cannula to
the green product W2Cl4(P(n-Bu)3)4, and the reaction
mixture heated gently for 48 h to yield a deep purple
solid product upon addition of hexanes. The precipitate
was washed several times with 30 ml aliquots of hex-
anes and solvent removed under dynamic vacuum to
yield 0.843 g (42.8%) of the purple product. Visible
3.4. Preparation of W2(v-O2CC6H5)2I2(v-dppa)2 (3)
W2(m-O2CC6H5)2I2(m-dppa)2 was obtained by the
same methodology used to synthesize the other halide
analogs 1 and 2. The same amounts of starting material
WCl4 and the other reagents were used with the halide
source ZnI2 (0.490 g, 1.54 mmol) to yield W2(m-
O2CC6H5)2I2(m-dppa)2 (1.53 g, 61.3%). Visible spectrum
(THF, lmax, nm): 442 sh.
1
spectrum (CH2Cl2, umax, nm): 378, 548, 752; H-NMR
spectrum (CDCl3, ppm): 7.99 (m), 7.138 (m) with 2:3
integrated ratio, 5.514 ppm (pentet).
3.8. Crystallographic studies
3.5. Preparation of W2Cl4(v-dppa)2 (4)
Crystals of W2(m-O2CC6H5)2Br2(m-dppa)2·(THF)2
(2·(THF)2), W2(m-Cl)2Cl4(m-dppa)2·(THF)4 (5·(THF)4)
and W2(m-H)2Cl4(m-dppa)2·(THF)2 (6·(THF)2) were
grown from THF–hexanes solvent mixtures. Data were
collected for 2·(THF)2 and 5·(THF)4 using a Siemens
SMART CCD-based diffractometer equipped with a LT-
2 low-temperature apparatus operating at 213 K. A
suitable crystal was mounted on a glass fiber using
grease. Data were measured using omega scans of 0.3°
per frame for 30 s, such that a hemisphere was col-
lected. A total of 1271 frames was collected with a final
The gray powder WCl4 (0.500 g, 1.54 mmol) was
suspended in 10 ml of THF and cooled to −60°C in an
ethanol–dry ice bath. To this suspension, 3.07 ml (3.07
mmol) of NaBEt3H was added and the mixture warmed
to −20°C. The ‘WCl2’ solution was then transferred by
cannula to a flask at r.t. containing 0.60 g (1.6 mmol)
of dppa. The reaction mixture was warmed to r.t. with
copious amounts of brown powder and a brown super-
natant appearing in the solution. After washing the
reaction mixture three times with 30 ml aliquots of
hexanes, all solvent was removed under dynamic vac-
uum to yield 0.800 g (81.4%) of the brown product. If
reaction times are increased, the formation of W2(m-
H)2Cl4(m-dppa)2 occurs within several hours after the
addition of dppa. Visible spectrum (THF, umax, nm):
454.
,
,
resolution of 0.80 A for 2·(THF)2 and 0.75 A for
5·(THF)4. The first 50 frames were recollected at the
end of each data collection to monitor for decay, but
neither of the crystals used for the diffraction study
showed decomposition during data collection. Cell
parameters were retrieved using SMART [32] software
and refined using SAINT on all observed reflections.
Data reduction was performed using the SAINT soft-
ware [33], which corrects for decay and Lorentz and
polarization effects. Absorption corrections were ap-
plied using SADABS [34] supplied by George Sheldrick.
The structure was solved by direct methods using the
SHELXL-90 [35] program and refined by least squares
method on F2, SHELXL-93 [36], incorporated in
SHELXTL 5.03 (PC-Version) [37].
3.6. Preparation of W2(v-Cl)2Cl4(v-dppa)2 (5)
WCl4 (1.00 g, 3.08 mmol) was suspended in 10 ml of
THF and cooled to −60°C in an ethanol–dry ice bath.
To this mixture, 3.07 ml (3.07 mmol) of NaBEt3H was
added and the solution warmed to −20°C. The ‘WCl2’
solution was then transferred by cannula to a flask at
r.t. containing 1.20 g (3.20 mmol) of dppa. The reaction
mixture was warmed to r.t., stirred overnight, and
washed three times with 30 ml aliquots of hexanes to
yield an orange–red powder. Upon solvent removal
under dynamic vacuum, 1.87 g (74.1%) of orange-red
The structures of 2·(THF)2 and 5·(THF)4 were solved
(
in the space groups P21/n and P1, respectively, by
analysis of systematic absences. All non-hydrogen
atoms were refined anisotropically. The hydrogen
atoms were calculated by geometrical methods and
refined as a riding model. The crystal quality yielded
powder (5) was produced. Visible spectrum (THF, umax
,
1
,
nm): 381, 469; H-NMR spectrum (CD2Cl2, ppm): 7.63
poor data beyond 0.9 A for 2·(THF)2 and this data was
(s), 7.54 (s), 7.43 (s) with 1:2:2 integrated ratio.
not used in the refinement. Pertinent crystallographic

J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
141
Table 1
Crystal data for compounds 2·(THF)2, 5·(THF)4, and 6·(THF)2
W2(m-O2CC6H5)2Br2(m-dppa)2·(THF)2
(2·(THF)2)
W2(m-Cl)2Cl4(m-dppa)2·(THF)4
(5·(THF)4)
W2(m-H)2Cl4(m-dppa)2·(THF)2
(6·(THF)2)
Formula
Formula weight
Temperature (K)
C70H68Br2N2O6P4W2
1684.66
213(2)
C64H74Cl6N2P4W2
1639.53
213(2)
C56H60Cl4N2P4W2
1426.44
294(2)
,
Wavelength (A)
0.71073
0.71073
Triclinic
0.71073
Crystal system
Space group
Monoclinic
P21/n, [no. 14]
11.382(2)
20.453(7)
13.871(4)
Monoclinic
P21/c [no. 14]
22.43(2)
15.34(2)
17.794(10)
(
P1 [no. 2]
,
a (A)
10.4264(2)
12.1319(2)
13.9311(2)
67.339(1)
78.524(1)
85.979(1)
1593.58(5)
1
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
97.86(2)
109.71(5)
3
,
V (A )
3199(2)
2
1.749
5763(8)
4
1.644
4.415
Z
Dcalc (Mg m−3
Absorption coefficient 4.997
)
1.708
4.007
(mm−1
)
Data/restraints/
parameters
R1
4137/0/388
4113/60/370
7618/0/632
0.0554 a
0.1009 b
0.0414 a
0.0875 b
0.0413 a
0.0688 b
wR2
a R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ.
b wR2=[ꢀ(wFo2−Fc2)2/ꢀ(wFo4)]1/2
.
to be due to a dynamic in-plane vibration of the ring.
Attempts to model the region as a static disorder of two
contributing locations were unsuccessful. A small ex-
tinction parameter was applied and refinement was
performed against F2. Scattering factors were taken
parameters for 2·(THF)2 and 5·(THF)4 are summarized
in Table 1. Selected bond lengths and angles for
2·(THF)2 and 5·(THF)4 are listed in Tables 2 and 3.
Data for W2(m-H)2Cl4(m-dppa)2·(THF)2 (6·(THF)2)
were collected on a Siemens R3m/V automated diffrac-
tometer fitted with a molybdenum source and a
graphite monochrometer [38]. The crystal was mounted
in a 0.2 mm glass capillary and the cell determined by
careful alignment of 32 high-order diffraction intensi-
ties. Since no decomposition was observed over the
course of data collection, the data were corrected for
Lorentz and polarization effects, but not for decompo-
sition or absorption.
Table 2
,
Selected bond lengths (A) and angles (°) for 2·(THF)2
Bond lengths
W(1)–W(1A)
W(1)–P(1)
W(1)–P(2)
W(1)–O(1)
W(1)–O(2)
W(1)–Br(1)
2.2986(11)
2.541(3)
2.517(3)
2.096(7)
2.078(7)
2.857(2)
Application of the Patterson function located the two
tungsten atoms and successive difference Fourier maps
revealed the remaining non-hydrogen atoms [39,40]. In
the final model, all non-hydrogen atoms positions and
attendant anisotropic displacement factors were refined
with hydrogen atoms in calculated positions with
isotropic vibrational factors 20% greater than the at-
tached atom contributing to the calculated structure
factors. The bridging hydrides were located between the
tungsten atoms upon inspection of the final difference
Fourier map. A fixed isotropic vibrational amplitude of
0.0552 was assigned to each hydride to yield stable
refinement of the positional coordinates with other
Bond angles
O(1)–W(1)–W(1A)
O(2)–W(1)–W(1A)
O(2)–W(1)–O(1)
O(1)–W(1)–P(1)
O(2)–W(1)–P(1)
O(1)–W(1)–P(2)
O(2)–W(1)–P(2)
W(1A)–W(1)–P(1)
W(1A)–W(1)–P(2)
P(2)–W(1)–P(1)
O(1)–W(1)–Br(1)
O(2)–W(1)–Br(1)
W(1A)–W(1)–Br(1)
P(1)–W(1)–Br(1)
P(2)–W(1)–Br(1)
88.4(2)
89.9(2)
177.4(3)
95.6(2)
82.8(2)
93.5(2)
88.5(2)
102.82(8)
90.28(8)
164.21(11)
94.9(2)
87.0(2)
171.97(4)
84.13(8)
82.26(9)
difference features remaining in the range 1–2 e−3
.
Phenyl carbons C43 through C48 have considerably
broadened anisotropic displacement factors that appear

142
J.L. Eglin et al. / Journal of Organometallic Chemistry 596 (2000) 136–143
Table 3
4. Supplementary material
,
Selected bond lengths (A) and angles (°) for compound 5·(THF)4
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Center as supplementary publication nos. CCDC
131483 (6·(THF)2), CCDC 1131484 (2·(THF)2), and
CCDC 131485 (5·(THF)4). Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
Complete tables of crystal data, positional and
isotropic equivalent thermal parameters, anisotropic
thermal parameters, bond distances, bond angles, and a
listing of observed and calculated structure factors for
the molecules of W2(m-O2CC6H5)2Br2(m-dppa)2·(THF)2
(2·(THF)2), W2(m-Cl)2Cl4(m-dppa)2·(THF)4 (5·(THF)4),
and W2(m-H)2Cl4(m-dppa)2·(THF)2 (6·(THF)2) are avail-
able from author J.L.E. upon request.
Bond lengths
W(1)–W(1A)
W(1)–Cl(1)
W(1)–Cl(2)
W(1)–Cl(3)
W(1)–P(1)
W(1)–P(2)
2.6828(8)
2.394(2)
2.421(2)
2.422(2)
2.582(2)
2.541(3)
Bond angles
Cl(1A)–W(1)–Cl(1)
W(1A)–Cl(1)–W(1)
Cl(2)–W(1)–W(1A)
Cl(3)–W(1)–W(1A)
Cl(2)–W(1)–Cl(3)
Cl(2)–W(1)–P(1)
Cl(3)–W(1)–P(1)
Cl(2)–W(1)–P(2)
Cl(3)–W(1)–P(2)
P(1)–W(1)–W(1A)
P(2)–W(1)–W(1A)
P(2)–W(1)–P(1)
111.76(6)
68.24(6)
139.41(6)
136.66(6)
83.86(8)
87.73(8)
89.81(8)
85.23(8)
88.07(8)
93.51(6)
92.75(6)
172.82(8)
Acknowledgements
from the International Tables for X-Ray Crystallogra-
phy [41]. Crystallographic parameters for 6·(THF)2 are
summarized in Table 1 with selected bond lengths and
angles for 6·(THF)2 listed in Table 4.
L.S. and J.E. would like to acknowledge the support
of the National Science Foundation EPSCoR program
(EHR 9108767) and the ARI Program (CHE 92-14521).
E.V. and J.Z. acknowledge the support of the Office of
Naval Research.
Table 4
,
Selected bond lengths (A) and angles (°) compound 6·(THF)2
References
Bond lengths
W(1)–W(2)
W(1)–Cl(1)
W(1)–Cl(2)
W(2)–Cl(3)
W(2)–Cl(4)
W(2)–P(1)
W(1)–P(2)
W(2)–P(3)
W(1)–P(4)
W(1)–H(1)
W(1)–H(2)
W(2)–H(1)
W(2)–H(2)
2.407(2)
2.379(3)
2.347(3)
2.386(3)
2.373(3)
2.512(3)
2.536(3)
2.519(4)
2.512(3)
2.025(20)
2.134(20)
2.127(21)
1.839(20)
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H(1)–W(1)–H(2)
W(1)–H(1)–W(2)
Cl(1)–W(1)–W(2)
Cl(3)–W(2)–W(1)
Cl(2)–W(1)–Cl(1)
Cl(1)–W(1)–P(2)
Cl(2)–W(1)–P(2)
Cl(3)–W(2)–P(1)
Cl(4)–W(2)–P(1)
W(1)–W(2)–P(1)
W(1)–W(2)–P(3)
P(1)–W(2)–P(3)
103.8(30)
70.8(20)
H(1)–W(2)–H(2)
W(1)–H(2)–W(2)
Cl(2)–W(1)–W(2)
Cl(4)–W(2)–W(1)
Cl(4)–W(2)–Cl(3)
Cl(1)–W(1)–P(4)
Cl(2)–W(1)–P(4)
Cl(3)–W(2)–P(3)
Cl(4)–W(2)–P(3)
W(2)–W(1)–P(2)
W(2)–W(1)–P(4)
P(4)–W(1)–P(2)
111.1(30)
74.1(20)
132.80(9)
132.44(9)
101.99(13)
90.59(11)
90.96(11)
87.24(11)
92.67(11)
93.69(9)
124.56(8)
128.24(8)
99.14(11)
83.72(12)
85.33(11)
81.51(11)
90.37(11)
95.54(9)
92.98(9)
168.68(10)
92.03(10)
172.40(11)

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