Seven-coordinate complexes of molybdenum(II) and tungsten(II) containing phosphite donor ligands: X-ray crystal structures of [WI2(CO)3{P(OiPr)3}2] and [WI2(CO)2{P(OMe)3}3]

Article abstract of DOI:10.1016/S0022-328X(98)00723-2

Treatment of [MI₂(CO)₃(NCMe)₂] with two equivalents of P(OR)₃ (for M=W only, R=Me, ⁱPr; for M=Mo and W, R=Ph) in Et₂O gave the bis(phosphite) complexes [MI₂(CO)₃{P(OR)₃}₂] (1-4) in high yield. The complex for M=W, R=ⁱPr was crystallographically characterised, and has a distorted capped octahedral geometry with a phosphite group capping a tricarbonyl face. Reaction of [WI₂(CO)₃(NCMe)₂] with three equivalents of P(OR)₃ (R=Me, Et) in Et₂O afforded the tris(phosphite) complexes [WI₂(CO)₂{P(OR)₃}₃], which was crystallographically characterised for R=Me. The structure of [WI₂(CO)₂{P(OMe)₃}₃] has an almost idealised capped trigonal prismatic geometry with a phosphite ligand capping a rectangular face containing C(1), C(2), I(2) and P(3).

Full text of DOI:10.1016/S0022-328X(98)00723-2

Journal of Organometallic Chemistry 566 (1998) 245–250
Seven-coordinate complexes of molybdenum(II) and tungsten(II)
containing phosphite donor ligands: X-ray crystal structures of
[WI2(CO)3{P(OiPr)3}2] and [WI2(CO)2{P(OMe)3}3]
Paul K. Baker a,*, Simon J. Coles b, Nigel S. Harrison a, Latifah Abdol Latif a,c
Margaret M. Meehan a, Michael B. Hursthouse b
,
a Department of Chemistry, Uni6ersity of Wales, Bangor, Gwynedd, LL57 2UW, UK
b Department of Chemistry, Uni6ersity of Wales, Cardiff, PO Box 912, Park Place, Cardiff, CF1 3TB, UK
c Centre for Foundation Studies in Science, Uni6ersity of Malaya, 50603, Kuala Lumpur, Malaysia
Received 16 April 1998
Abstract
i
Treatment of [MI2(CO)3(NCMe)2] with two equivalents of P(OR)3 (for M=W only, R=Me, Pr; for M=Mo and W, R=Ph)
in Et2O gave the bis(phosphite) complexes [MI2(CO)3{P(OR)3}2] (1–4) in high yield. The complex for M=W, R=iPr was
crystallographically characterised, and has a distorted capped octahedral geometry with a phosphite group capping a tricarbonyl
face. Reaction of [WI2(CO)3(NCMe)2] with three equivalents of P(OR)3 (R=Me, Et) in Et2O afforded the tris(phosphite)
complexes [WI2(CO)2{P(OR)3}3], which was crystallographically characterised for R=Me. The structure of
[WI2(CO)2{P(OMe)3}3] has an almost idealised capped trigonal prismatic geometry with a phosphite ligand capping a rectangular
face containing C(1), C(2), I(2) and P(3). © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Seven-coordinates; Molybdenum(II); Tungsten(II); Phosphites
coordinate neutral halocarbonyl product such as
[MoCl2(CO)3{P(OMe)3}2].
1. Introduction
Over the past 12 years we have been exploring the
chemistry of the highly versatile seven-coordinate com-
plexes [MXY(CO)3(NCMe)2] (M=Mo, W; X, Y=
halide or pseudo-halide) with a variety of neutral and
anionic donor ligands [23,24]. In this paper we describe
the reactions of [MI2(CO)3(NCMe)2] (M=Mo, W) with
Although a large number of halocarbonyl seven-coor-
dinate complexes of molybdenum(II) and tungsten(II)
containing phosphine ligands have been reported [1–19],
very few examples containing phosphites have appeared.
Two crystallographically characterised examples are:
[WBr2(CO){P(OMe)3}2
{(Me)2AsC(CF3)ꢀC(CF3)As-
i
P(OR)3 (R=Me, Et, Pr, Ph). An early communication
on this work has been published [25].
(Me)2}] [20] and [MoCl(SnCl2Bun)(CO)2{P(OMe)3}3]
[21]. It is interesting to note that reaction of the chloro-
bridged dimer, [{Mo(v-Cl)Cl(CO)4}2] with P(OMe)3
yielded the unusual crystallographically characterised
product [Mo2Cl3(CO)4{P(OMe)3}4]n+[MoCl4(O){OP-
(OMe)2}]n− [22], rather than an expected seven-
2. Results and discussion
The starting materials used in this research, namely
[MI2(CO)3(NCMe)2] (M=Mo, W) were prepared by
reacting
the
zero-valent
complexes
fac-
* Corresponding author. Fax: +44 1248 370528.
[M(CO)3(NCMe)3] in situ with equimolar quantities of
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00723-2

246
P.K. Baker et al. / Journal of Organometallic Chemistry 566 (1998) 245–250
Table 1
Physical and analytical data for the complexes 1–6
Complex
Colour
Yield (%)
Found C
Calculated H (%)
(1) [WI2(CO)3{P(OMe)3}2]
(2) [WI2(CO)3{P(OiPr)3}2]
(3) [MoI2(CO)3{P(OPh)3}2].Et2O
(4) [WI2(CO)3{P(OPh)3}2].Et2O
(5) [WI2(CO)2{P(OMe)3}3]
(6) [WI2(CO)2{P(OEt)3}3]
Yellow
Yellowish orange
Yellow
Yellow
Yellow
68
79
76
71
60
74
14.2 (14.0)
26.9 (26.9)
45.5 (45.8)
42.3 (42.4)
15.1 (15.3)
24.3 (24.2)
2.5 (2.4)
4.5 (4.5)
3.3 (3.6)
3.0 (3.3)
3.2 (3.1)
4.7 (4.6)
Yellow
I2 (at 0°C) [26]. Reaction of [MI2(CO)3(NCMe)2] with
two equivalents of P(OR)3 in Et2O at room temperature
afforded excellent yields of the acetonitrile displaced
however they can be stored under an inert atmosphere
in the solid state for several days without significant
decomposition. The IR spectra for complexes 1–4
(Table 2) all have three carbonyl bands in the expected
region for [MX2(CO)3L2] type complexes, except for the
molybdenum complex [MoI2(CO)3{P(OPh)3}2].Et2O (3),
which has four bands at 2002(sh), 1967, 1934 and 1901
cm−1, which may indicate the presence of isomers. A
nujol mull was also recorded of complex 3 and also
i
products [MI2(CO)3{P(OR)3}2] (M=W, R=Me, Pr;
M=Mo, W, R=Ph) (1–4). Complexes 1–4 have been
fully characterised by elemental analysis (C and H)
(Table 1), IR, 1H, 31P and in selected cases by 13C-NMR
spectroscopy (Table 2). The triphenylphosphite com-
plexes [MI2(CO)3{P(OPh)3}2].Et2O (M=Mo, W) (3 and
4) were confirmed as diethyl ether solvates by repeated
elemental analyses and 1H-NMR spectroscopy. 1H-
NMR data for 1 and the IR data for 4 are not included
as they have been previously presented [25]. The IR data
for complex 1 is incorrect in the original communication,
and the carbonyl bands in Table 2 (2043, 1980 and 1942
cm−1) are the correct values for this complex. The
complexes are all very soluble in organic solvents such
as CH2Cl2, CHCl3, Et2O and toluene, but only moder-
ately soluble in hexane and pentane. They are air-sensi-
tive in the solid state and very air-sensitive in solution,
shows four bands at 1990, 1954, 1925 and 1894 cm−1
,
which again suggests the presence of isomers. It should
be noted that a number of attempts to prepare other
molybdenum
complexes
of
the
types
[MoI2(CO)3{P(OR)3}2] and [MoI2(CO)2{P(OR)3}3] were
unsuccessful, mainly due to the instability of these
complexes, and the likely formation of mixtures. In
order to study the solid state structure, suitable single
crystals for X-ray analysis of [WI2(CO)3{P(OiPr)3}2] (2)
were grown by cooling a concentrated Et2O solution of
2 at −5°C for 72 h.
Table 2
IRa, 1H-b, 31P-c and 13C- NMRb data for the phosphite complexes
Complex IR w(CO) (cm−1
)
1H-NMR l (ppm)
31P-{1H}NMR l (ppm)
115.35(s); JWP not resolved
104.11(s), JWP=246.0 Hz
13C-{1H}NMR l (ppm)
1
2
2043(s); 1980(s);
1942(s)
2038(m); 1971(s);
1932(s)
209.36(t, 2CO);198.39(br, CO);
55.20(t, P(OCH3)3)
212.66(t, 2CO); 199.99 (t, CO);
72.95(t, P(OCH(CH3)2); 23.71(s,
P(OCH(CH3)2)
4.82{m, 6H,P{OCH(CH3)2}3};
1.48{d, JP–H=8.5 Hz,
36H,P{OCH(CH3)2}3}
3
4
2002(sh); 1967(s);
1934(s); 1901(s)
7.10–7.60{br,m, 30H,P(OC6H5)3}; 129.51(s); JWP not resolved
3.45{q, JP–H=6.9 Hz,
4H,(CH3CH2)2O}; 1.25{t, JP–H
6.5 Hz, 6H,(CH3CH2)2O}
=
6.80–7.60{br, m, 30H,P(OC6H5)3}; 99.32(s); JWP=347 Hz
3.50{q,JP–H=6.7 Hz,
4H,(CH3CH2)2O}; 1.25{t, JP–H
6.4 Hz, 6H,(CH3CH2)2O}
3.70{m, P(OCH3)3}
=
5
6
1961(s); 1881(s)
1957(s); 1881(s)
117.57(br); 107.37(br,s); 93.84
(br,m)
113.12(br); 103.18(br,s)/
101.60(br,s); 89.67(br,m)
ꢀ228(br, CO); ꢀ221(br, CO);
55.27(br, s, P(OCH3)3)
4.12{br,m, 18H,P(OCH2CH3)3};
1.28{t, JP–H=6.2 Hz,
27H,P(OCH2CH3)3}
a Spectra recorded as thin CHCl3 films between NaCl plates.
b Spectra recorded in CDCl3 at 25°C and referenced to SiMe4.
c Spectra recorded in CDCl3 at 25°C and referenced to 85% H3PO4.

P.K. Baker et al. / Journal of Organometallic Chemistry 566 (1998) 245–250
247
Fig. 1. X-ray crystal structure of [WI2(CO)3{P(OiPr)3}2] (2). Thermal ellipsoids shown at 30% probability.
The structure of [WI2(CO)3{P(OiPr)3}2] (2) is shown
in Fig. 1, together with the atomic numbering scheme.
The structure of 2 exhibits a distorted capped octahe-
dral geometry. The capping moiety is the phosphite
ligand P(2), which occupies the face formed by the
three carbonyl ligands (the three W–C bond lengths are
very similar, W(1)–C(1)=2.007(7), W(1)–C(2)=
also obtained (Table 2), and for example show, the
presence of carbonyl resonances at l=209.36 and
198.39 ppm for 1, which are in the normal octahedral
range. The intensity ratio of the resonances at l=
209.36 to 198.39 is ca. 2:1. It is very likely the two
equivalent carbonyl groups trans- to the two iodo
groups can be ascribed to the resonance at 209.36 ppm,
and the higher field resonance at 198.39 ppm to the
carbonyl group trans- to the octahedral phosphite lig-
and. Since the 13C-NMR spectrum of complex 2 is
similar to 1 in the carbonyl region, it is likely that their
structures will be very similar.
˚
1.982(7), W(1)–C(3)=2.068(7) A). The distortion from
ideal capped octahedral geometry is caused by the
larger steric bulk of the phosphite ligand, which forces
the C(1) carbonyl group out of plane (I(1)–W(1)–
P(2)=136.22(5) and I(1)–W(1)–C(1)=150.6(2)°). This
is unusual in that one would normally expect the ligand
with the lesser bulk to form the cap. W–P bond lengths
Treatment of [WI2(CO)3(NCMe)2] with three equiva-
lents of P(OR)3 (R=Me, Et) in Et2O at room tempera-
˚
are similar (2.525(2) and 2.420(3) A), when one would
ture
gave
the
tris(phosphite)
complexes
expect the ligand forming the cap to have a longer
interaction with the metal. This is due to the phosphite
group capping a face formed by carbonyls, which have
a small steric bulk and allow the bulky ligand to bond
at its ideal distance.
[WI2(CO)2{P(OR)3}3] (5 and 6) in high yield. Com-
plexes 5 and 6 were characterised as previously (Tables
1 and 2). They are both extremely soluble in most
organic solvents (more so than the bis(phosphite) com-
plexes 1–4), and are also very air-sensitive in solution.
The IR spectra for 5 and 6 both have two carbonyl
bands at 1961 and 1881cm−1 (5) and 1957 and
1881cm−1 (6), respectively. This agrees with the solid
state structure of 5 shown in Fig. 2.
1
The room temperature H-NMR spectra of 2–4 con-
form with the solid state structure of 2 shown in Fig. 1.
The room temperature 31P-NMR spectrum for 2
showed a singlet at 104.13 ppm, flanked by the W
satellites, giving a JWP of 246 Hz. The room tempera-
ture 13C-{1H}NMR spectra for complexes 1 and 2 were
Suitable single crystals for X-ray analysis of
[WI2(CO)2{P(OMe)3}3] (5) were grown by cooling a

248
P.K. Baker et al. / Journal of Organometallic Chemistry 566 (1998) 245–250
Fig. 2. X-ray crystal structure of [WI2(CO)2{P(OMe)3}3] (5). Thermal ellipsoids shown at 30% probability.
and a broad singlet (possibly a triplet) at l=107.37
ppm. The room temperature 13C-{1H}NMR spectrum
(Table 2) of 5 has carbonyl resonances at l=228 and
221 ppm, which appear as broad resonances, and hence
it is difficult to assign with the carbonyl groups in
complex 5.
concentrated Et2O solution of 5 to −5°C for 72 h. The
molecular structure of 5 is shown in Fig. 2, together
with the atom numbering scheme. The tungsten atom
lies in a seven-coordinate environment, the geometry of
which is best described as being a slight distortion from
a capped trigonal prism due to differing spatial require-
ments of the ligands. P(1) forms the cap upon the face
defined by C(1), C(2), I(2) and P(3), giving coordination
angles of approximately 80° [C(1)–W(1)–P(1)=
In
summary,
although
the
reactions
of
[MI2(CO)3(NCMe)2] (M=Mo and W) with both two
i
and three equivalents of P(OR)3 (R=Me, Et, Pr and
Ph) gave six fully characterised complexes, a number of
attempts were made to isolate and characterise the
other analogues in the series without success. Many of
the complexes were oils and difficult to purify. It is
interesting to note that the two representative crystal
76.1(2)°,
C(2)–W(1)–P(1)=76.6(2)°,
P(1)–W(1)–
I(2)=79.55(5)°], apart from P(3) which forms an angle
P(1)–W(1)–P(3)=94.32(6)° due to steric repulsion be-
tween the two bulky phosphite groups. This geometry is
in agreement with the related complex [Mo-
Cl(SnCl2Bun)(CO)2{P(OMe)3}3] [21].
structures
of
[WI2(CO)3{P(OiPr)3}2]
(2)
and
The room temperature 1H-NMR spectrum of 5
agrees with its solid-state structure shown in Fig. 2. The
[WI2(CO)2{P(OMe)3}3] (5) both have different basic
seven-coordinate structures which is most likely to be
due to the very different steric requirements of two and
three phosphite ligands attached to the tungsten centres
in 2 and 5, respectively.
room temperature 31P-{1H}NMR spectrum of
5
showed a rather broad spectrum, consisting of two
doublet of doublets centred at 117.57 and 93.84 ppm,

P.K. Baker et al. / Journal of Organometallic Chemistry 566 (1998) 245–250
249
Table 3
Crystal data and structure refinement for Compounds 2 and 5
Compound 2
C21H42I2O9P2W
938.14
Compound 5
C11H27I2O11P3W
865.89
Empirical formula
Formula weight
Crystal system
Triclinic
P-1
Monoclinic
P21/c
Space group
Unit cell dimensions
˚
a (A)
10.187(3)
11.154(9)
16.195(3)
16.5268(6)
10.051(3)
14.9667(6)
˚
b (A)
˚
c (A)
h (°)
i (°)
78.12(2)
73.93(2)
90.0
100.73(2)
k (°)
V (A )
69.12(2)
1640.2(14)
90.0
2442.6(3)
3
˚
Z
2
4
Density (calculated) (Mg m−3
)
1.900
5.541
900
2.355
7.499
1624
Absorption coefficient (mm−1
F(000)
)
Crystal size (mm)
0.28×0.18×0.11
0.28×0.24×0.1
Theta range for data collection (°)
Index ranges
1.97–28.58
−135h512; −145k59; −205l517
2.38–24.92
−165h517; −115k11; −165l517
Reflections collected
8044
8088
Independent reflections
Absorption correction factors
No. of parameters
6275 [Rint=0.0541]
0.864/1.240
328
3393 [Rint=0.0579]
0.854/1.381
262
Goodness-of-fit on F2
Final R indices, [I\2|(I)]
R indices (all data)
1.001
0.986
R1=0.0398; wR2=0.0985; (5367 reflections) R1=0.0314; wR2=0.0683; (2891 reflections)
R1=0.0461; wR2=0.1088
2.683 and −2.667
R1=0.0392; wR2=0.0769
1.695 and −0.979
−3
˚
Largest difference peak and hole (e A
)
3. Experimental details
Similar reactions of [WI2(CO)3(NCMe)2] with two
equivalents of P(OR)3 (for M=W only, R=Me; for
M=Mo, W; R=Ph) afforded [MI2(CO)3{P(OR)3}2]
(1, 3 and 4). See Table 1 for physical and analytical
data.
All preparations described in this paper were carried
out using standard vacuum/Schlenk line techniques.
The starting materials, [MI2(CO)3(NCMe)2] (M=Mo,
W) were prepared by the literature method [26]. Diethyl
ether was dried over sodium wire before use. All chem-
icals used were purchased from commercial sources.
Elemental analyses (C, H and N) were determined
using a Carlo Erba Elemental Analyser MOD 1108
(using helium as a carrier gas). IR spectra were
recorded as thin CH2Cl2 films between NaCl plates.
1H-, 13C- and 31P-NMR spectra were recorded on a
Bruker AC 250 MHz NMR spectrometer. 1H- and
13C-NMR spectra were referenced to SiMe4, and 31P-
NMR spectra were referenced to 85% H3PO4.
3.2. [WI2(CO)2{P(OMe)3}3] (5)
In a typical reaction; to [WI2(CO)3(NCMe)2] (0.80 g,
1.33 mmol) dissolved in diethyl ether (50 cm3) with
continuous stirring under a stream of N2 was added
P(OMe)3 (0.495 g, 3.99 mmol). After stirring for 1 min,
the solution went bright yellow. The mixture was
stirred for a further 3 h. Removal of the solvent to half
volume in vacuo and cooling to −5°C for 72 h gave
small regular yellow crystals which were suitable for
X-ray crystallography of [WI2(CO)2{P(OMe)3}3] (5).
Yield of pure product=0.688 g, 60%.
3.1. [WI2(CO)3{P(OiPr)3}2] (2)
A similar reaction of [WI2(CO)3(NCMe)2] with three
equivalents
of
P(OEt)3
in
Et2O
afforded
In a typical reaction; to [WI2(CO)3(NCMe)2] (0.80 g,
1.33 mmol) dissolved in diethyl ether (50 cm3) with
continuous stirring under a stream of dry N2 was added
P(OiPr)3 (0.554 g, 2.66 mmol). After stirring for 2 min,
the solution went light brown. The mixture was then
stirred for a further 3 h. Removal of the solvent to half
volume in vacuo and cooling to −5°C for 72 h gave
small regular orange crystals suitable for X-ray crystal-
lography of [WI2(CO)3{P(OiPr)3}2] (2). Yield of pure
product=0.981 g, 79%.
[WI2(CO)2{P(OEt)3}3] (6) as a yellow crystalline solid.
See Table 1 for physical and analytical data.
3.3. X-ray crystallography—crystal structure
determinations
Crystals of 2 and 5 suitable for structure determina-
tions were grown from concentrated cooled (−5°C)
Et2O solutions of 2 and 5 for 72 h. Crystal data and
experimental conditions are summarised in Table 3.

250
P.K. Baker et al. / Journal of Organometallic Chemistry 566 (1998) 245–250
Table 4
Acknowledgements
˚
Selected bond lengths (A) and angles (°) for complexes 2 and 5
M.M. Meehan thanks the EPSRC for a studentship.
L.A. Latif thanks the British Council for providing her
with a Research Attachment Award (British Chevening
Award) and the University of Malaya for the other
financial support and leave. We also thank the EPSRC
for supporting the National X-ray Crystallography Ser-
vice at Cardiff.
2
5
˚
Bond length (A)
W(1)–C(1)
W(1)–C(2)
W(1)–C(3)
W(1)–P(1)
W(1)–P(2)
W(1)–I(1)
W(1)–I(2)
2.007(7) W(1)–C(1)
1.982(7) W(1)–C(2)
2.068(7) W(1)–P(1)
2.525(2) W(1)–P(2)
2.420(3) W(1)–P(3)
2.828(4) W(1)–I(1)
2.912(7) W(1)–I(2)
1.948(7)
2.001(8)
2.454(2)
2.416(2)
2.567(2)
2.924(7)
2.871(8)
References
Bond angles (°)
C(1)–W(1)–C(2)
C(2)–W(1)–C(3)
C(1)–W(1)–C(3)
C(1)–W(1)–P(1)
C(2)–W(1)–P(1)
C(3)–W(1)–P(1)
C(1)–W(1)–P(2)
C(2)–W(1)–P(2)
C(3)–W(1)–P(2)
P(1)–W(1)–P(2)
C(1)–W(1)–I(1)
C(2)–W(1)–I(1)
C(3)–W(1)–I(1)
C(1)–W(1)–I(2)
C(2)–W(1)–I(2)
C(3)–W(1)–I(2)
P(1)–W(1)–I(1)
P(1)–W(1)–I(2)
P(2)–W(1)–I(1)
P(2)–W(1)–I(2)
I(1)–W(1)–I(2)
114.4(3)
C(1)–W(1)–C(2)
C(1)–W(1)–P(1)
C(2)–W(1)–P(1)
C(1)–W(1)–P(2)
C(2)–W(1)–P(2)
C(1)–W(1)–P(3)
C(2)–W(1)–P(3)
P(1)–W(1)–P(2)
P(2)–W(1)–P(3)
P(1)–W(1)–P(3)
C(1)–W(1)–I(1)
C(2)–W(1)–I(1)
C(1)–W(1)–I(2)
C(2)–W(1)–I(2)
P(1)–W(1)–I(1)
P(2)–W(1)–I(1)
P(3)–W(1)–I(1)
P(1)–W(1)–I(2)
P(2)–W(1)–I(2)
P(3)–W(1)–I(2)
I(1)–W(1)–I(2)
109.3(3)
76.1(2)
76.6(2)
70.6(2)
74.2(3)
104.3(3)
119.2(3)
77.8(2)
75.2(2)
160.0(2)
73.1(2)
74.8(2)
74.2(2)
123.74(7)
150.6(2)
81.9(2)
76.5(2)
75.2(2)
168.5(2)
74.7(2)
83.70(6)
101.78(5)
136.22(5)
115.27(5)
86.74(3)
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(1986) L5.
78.5(2)
165.7(3)
124.41(6)
120.01(7)
94.32(6)
116.8(2)
108.9(2)
150.1(2)
81.2(2)
161.45(5)
73.87(5)
76.55(4)
79.55(5)
138.78(5)
86.40(5)
83.74(2)
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for FAST geometry by A. Karaulov, University of Wales,
Cardiff, 1991.
Data were collected at 150(2) K on a FAST TV Area
detector diffractometer following previously described
procedures [27]. The structures were solved via heavy
atom methods (SHELX-S) [28] and then refined by full
matrix least squares on all F2o data (SHELX-93) [29].
Non-hydrogen atoms were treated anisotropically,
whilst hydrogen atoms were placed in idealised posi-
˚
tions, (C–H=0.96 A, with Uiso tied to Ueq of the
parent atoms). An empirical absorption correction was
applied using DIFABS [30]. Values for selected bond
lengths and angles are given in Table 4. Full details of
the data collection, structure refinement, atomic coordi-
nates, bond lengths and angles, and thermal parameters
have been deposited as supplementary material.
.