Packing and compositional disorder with MoO2Cl2(OPMePh2)2, MoOCl3(OPMePh2)2 and MoCl4(OPMePh2)2 as assessed by single crystal X-ray diffraction

Article abstract of DOI:10.1016/S0020-1693(02)01157-X

The structures as determined by single crystal X-ray determinations of MoO₂Cl₂(OPMePh₂)₂ and various mixtures of MoO₂Cl₂(OPMePh₂)₂ (A), MoOCl₃(OPMePh₂)₂ (B) and MoCl₄(OPMePh₂)₂ (C) specifically in ratios 40.2/59.8; 30.8/69.2; 14/86; 4/96 in A/B, 100% B and 82/18 in B/C are reported. The structural data illustrate that both compositional and packing disorder afford mechanisms by which apparent long and different Mo-O bond distances can be obtained.

Full text of DOI:10.1016/S0020-1693(02)01157-X

Inorganica Chimica Acta 342 (2003) 247ꢁ254
/
www.elsevier.com/locate/ica
Packing and compositional disorder with MoO2Cl2(OPMePh2)2,
MoOCl3(OPMePh2)2 and MoCl4(OPMePh2)2 as assessed by
single crystal X-ray diffraction
Frank R. Fronczek a, Rudy L. Luck b,ꢀ, Ge Wang b
a Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803-1804, USA
b Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA
Received 8 April 2002; accepted 23 May 2002
Abstract
The structures as determined by single crystal X-ray determinations of MoO2Cl2(OPMePh2)2 and various mixtures of
MoO2Cl2(OPMePh2)2 (A), MoOCl3(OPMePh2)2 (B) and MoCl4(OPMePh2)2 (C) specifically in ratios 40.2/59.8; 30.8/69.2; 14/86;
4/96 in A/B, 100% B and 82/18 in B/C are reported. The structural data illustrate that both compositional and packing disorder
afford mechanisms by which apparent long and different MoÃ
/O bond distances can be obtained.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Packing and compositional disorder; MoO2Cl2 (OPMePh2)2; MoOCl3(OPMePh2)2
1. Introduction
sion which was that the BSI in these complexes was a
consequence of mixtures of cis,mer-MoOCl2(PR3)3 and
the isostructural mer-MoCl3(PR3)3 [11ꢁ13]. This phe-
In 1971, the term ‘distortional isomerism’ was first
proposed by Chatt, Manojlovic-Muir and Muir to
explain the relationship between the green and blue
/
nomenon was appropriately described as compositional
disorder and indeed verifiable cases of BSI are rare [14].
In the course of an investigation into the substitution
of the chloride ligands on the heteronuclear quadruply
bonded complex MoWCl4(PMePh2)4 [15] with the
complexes of cis,mer-MoOCl2(PMe2Ph)3 [1ꢁ
structure analyses of these two compounds revealed that
the green species has a significantly longer MoÄO bond
/
3]. X-ray
/
ꢃ
˚
˚
(1.8 A) compared with the typical value of (1.6 A) [4,5]
found in the blue species. Several other distortional
isomers were reported after this first claim of ‘possibility
of a new type of isomerism’ [6,7] but there was evidence
amide NPh2 group, we obtained crystals of apparent
stoichiometry MoO2Cl2(OPMePh2)2, which appeared to
contain very long MoÃ
/
O bond distances (dMoÃO
ꢂ2.0
/
˚
A). With the now well-established fact of compositional
disorder in mind [16] we considered that the co-crystal-
lization of MoO2Cl2(OPMePh2)2 with some isostruc-
tural complex was the reason for the bond length
variation. Here we report that the structure of pure
of green complexes which contained short MoÄ
/O bond
lengths, specifically MoOCl2(PMePh2)2 with d(MoÃO)
ꢂ
/
˚
1.669 A [8]. These isomers are compositionally and
geometrically identical molecules but differ only by one
or more bond lengths. In 1988, Hoffman et al. termed
the isomers as ‘bond-stretch isomers (BSI)’ [9,10] and
this described the phenomenon more accurately. Par-
kins’ and Enemark’s groups reinvestigated the cis,mer-
MoOCl2(PR3)3 in 1991, and reached the same conclu-
MoO2Cl2(OPMePh2)2 contains MoÃ
/
O (oxo ligand)
˚
bond distances of 1.671(2) A. Contamination of this
material with MoOCl3(OPMePh2)2 leads to an apparent
lengthening of this bond due to the ‘incorporation’ of
chloride into the oxo site both as a consequence of co-
crystallization and packing disorder with MoOCl3(OP-
MePh2)2. In order to demonstrate the co-crystallization
among the above three compounds, we deliberately grew
crystals from the solution of mixtures of the above
ꢀ Corresponding author. Tel.: ꢄ
2061
E-mail address: rluck@mtu.edu (R.L. Luck).
/
1-906-487-2309; fax: ꢄ1-906-487-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 1 5 7 - X

248
F.R. Fronczek et al. / Inorganica Chimica Acta 342 (2003) 247ꢁ254
/
compounds and the crystals obtained revealed varied
MoÃO bond lengths.
ing mode in related compounds [19]. This peak was
observed in other compounds of the type Mo(V)OCl3L
and not for those consisting of Mo(VI)O2Cl2LL? [20].
1H NMR (CHCl3): d 1.6 (br, 3H, Me), 7.27 (br, 2H, m-
Ph), 7.42 (br, 1H, p-Ph), 7.76 (br, 2H, o-Ph). IR (Nujol
/
2. Experimental
mull) 970 (vs Mo(V)Ã
cmꢃ1 31P NMR (CHCl3): d 43.12 (br) relative to
H3PO4.
/
O), 1146 (s, PÃ
/
O), 1130 (s, PÃ
/
O)
2.1. Materials
.
Molybdenum pentachloride, methyldiphenylpho-
sphine oxide, and lead molybdate were obtained from
Aldrich Chemicals and used as received. Dichloro-
methane was dried over calcium hydride and distilled
under nitrogen. Benzene and hexane were dried over
sodium benzophenone ketyl and distilled under nitro-
gen. Methanol was dried over magnesium methoxide.
All preparations were carried out using standard schlenk
techniques under an inert atmosphere. Infrared spectra
were obtained on a Mattson GL-3020 FT IR spectro-
meter. 1H and 31P NMR data were recorded on a Varian
XL-400 spectrometer.
2.4. Preparation of MoCl4(OPMePh2)2 (C)
A suspension of MoCl4(THF)2 (1.3 g, 3.4 mmol),
which was prepared as previously reported [21], in
benzene was treated with OPMePh2 (1.6 g, 7.8 mmol).
The mixture was stirred at r.t. for 5 h over which period
the orange solution became yellow. The mixture was
filtered, washed with benzene and dried under vacuum.
The yield was 65%. IR (Nujol mull) 1081 (s, PÃ
/
O), 1067
O) cmꢃ1. We were unable to obtain crystals of this
compound due to the instability of the compound in
solution.
(s, PÃ
/
2.2. Preparation of MoO2Cl2(OPMePh2)2 (A)
2.5. Preparation of co-crystals
MoO2Cl2(OPMePh2)2 (A) was synthesized according
to the published procedure [17], except that OPMePh2
was used instead of OPPh3. The yield was 58%. The
compound in the form of a white precipitate was filtered
and dried under vacuum. The IR spectrum in the form
of a Nujol mull contained two strong bands at 942 and
903 cmꢃ1 which indicated the symmetric and asym-
Crystals of material labeled as 3 and 7 were obtained
by layering the products obtained in the reaction of
MoWCl4(PMePh2)4 [15] and 4 equiv. of LiNPh2 in
benzene with hexanes. Crystal 1 was obtained from pure
A; 2 was 33% each of A, B and C; 4 was 80% A, 20% B; 5
was 50% B 50% C; and 6 was from ‘pure’ C. These
mixtures were dissolved in either dried dichloromethane
or THF and then layered with hexanes or benzene.
Suitable crystals for 2, 4, 5, and 6 grew in about 1 week
(the most suitable were obtained from mixtures layered
with benzene) and, except for 4, the compositions
obtained were not the same as the initial mixtures.
metric vibrations for the MoÄ
that previous reported for the OPPh3 analog [17,18]. 1H
NMR (CDCl3): d2.23 (d, 3H, Jꢂ13.2 Hz, Me), 7.39(m,
2H, Jꢂ18.4 Hz, m-Ph), 7.49 (m, 1H, Jꢂ8.8 Hz, p-Ph),
7.77 (m, 2H, Jꢂ21.2 Hz, o-Ph). IR (Nujol mull) 942
(vs, MoÄO), 903 (s, MoÄO), 1155 (s, PÃO), 1136 (s, PÃ
O) cmꢃ1 31P NMR (CDCl3): d 42.96 (br) relative to
/O bond, and agreed with
/
/
/
/
/
/
/
/
.
H3PO4. Suitable crystals (labeled as 1) were obtained in
1 week by layering a THF solution of A with an equal
volume of dried methanol.
2.6. X-ray diffraction studies
For 1ꢁ4 suitable crystals were chosen and removed
/
from the mother liquor to a microscope slide where they
were stabilized by immersion in a mixture of mother
liquor and mineral oil. The crystals were then trimmed
using a sharp scalpel, rolled in epoxy resin, and fixed on
top of a thin glass fiber, which was anchored in a
goniometer-mounting pin. Compounds 5 and 6 were
mounted in 0.3 mm glass capillaries, which was filled
with the solutions that the crystals grew from, and then
capped with epoxy resin. All measurements were per-
formed at r.t., except for 6 and 7, which were measured
at 120 and 223 K, respectively. Except for compound 6,
2.3. Preparation of MoOCl3(OPMePh2)2 (B)
Dichloromethane(2.5 ml) and freshly opened acetyl
chloride (3.5 g, 0.042 mol) were added to lead molybdate
(2.5 g, 6.8 mmol). The mixture was stirred for 30 min
and then filtered. The addition of OPMePh2 (3 g, 13.6
mmol), dissolved in a minimum quantity of dichloro-
methane, to the dark brown filtrate gave a green
solution and white precipitate in high yields (i.e. ꢀ
/
70%). The mixture was stirred at room temperature
(r.t.) for 3 h, and at the end contained a green
precipitate. The product was collected by filtration,
washed with benzene and dried under vacuum. The IR
spectrum contained an absorption at 970 cmꢃ1 which
the diffractometer used was an EnrafꢁNonius Diffractis
/
586 Turbo CAD4 X-ray diffractometer. The data collec-
tion and reduction were accomplished using procedures
detailed previously [22]. The windows program WINGX
was used as the interface for the solution and refinement
has been previously assigned for the Mo(V)Ã
/
O stretch-

F.R. Fronczek et al. / Inorganica Chimica Acta 342 (2003) 247ꢁ
/
254
249
of the models [23]. The data were first reduced and
corrected for absorption using psi-scans [24] and then
solved using the program SIR97 [25]. The model was
refined with SHELXL97 [26] first with isotropic and then
anisotropic thermal parameters to convergence. In those
crystals where co-crystallization and/or disorder oc-
curred, the percentage occupancies were determined by
refinement of the site occupancies with the sum con-
strained to unity. Some sites could be modeled with
anisotropic thermal parameters; others had to be
defined with isotropic parameters. Compound 6 was
collected on a kCCD (with Oxford Cryostream) at 120
K using v-scans with k offsets. The data was reduced
and processed using the program COLLECT [27] and the
solution and refinement was as detailed above for the
compositional disorder [12] and thus we set about
deliberately preparing mixtures consisting of different
quantities of ‘pure’ materials. For obvious reasons, it
was important to establish the structural details of pure
MoO2Cl2(OPMePh2)2 and thus crystals from A were
grown and the data from this is listed as structure 1. An
ORTEP-3 [30] representation of 1 is given in Fig. 1.
Crystals of this compound did not contain any inter-
stitial solvent molecules and MoÃ
/
O atom distances for
˚
the oxo ligand of 1.676(3) and 1.677(3) A were obtained.
Compound 1, which was the only molecule out of the
seven studied herein to crystallize without lattice sol-
vent, contained disorder in the arrangement of one of
the phenyl rings as shown in Fig. 1 and was the only
structure to contain this particular type of ligand
disorder. Interestingly, this disorder is also present in
the crystal structure of the tungsten analogue to A [31].
A drawing of 2 is displayed in Fig. 2. The distorted
octahedral geometry displayed by 2 is typical of what
other structures. Crystallographic data for 1ꢁ7 are given
/
in Table 1. Selected bond distances and angles are listed
in Table 2.
remaining complexes 3ꢁ
cis-phosphine oxide ligand arrangement. Compounds
2ꢁ7 all co-crystallized with a 1/2 mol of benzene,
/
7 display, i.e. a trans-chloride,
3. Results and discussion
/
3.1. Synthesis of A, B and C
situated around an inversion point. This molecule of
solvation was arranged in a disordered manner in 3
where it appeared to have crystallized in two orienta-
tions, which differed by a 308 rotation about the
inversion point of the benzene molecule.
The synthesis of A was based on well-established
procedures [17] to prepare molybdenum (VI) com-
pounds of the form MoO2X2L2 (Xꢂ
/
halide, Lꢂmono-
/
1
dentate ligand). This complex was identified by H and
31P NMR, IR and (as crystals labeled as 1) by single X-
ray diffraction. The structure of the triphenylphosphine
oxide analog, i.e. MoO2Cl2(OPPh3)2, was previously
reported [29]. Compound B was prepared by adding the
phosphine oxide ligand to the obtained filtrate from the
reaction of lead molybdate and acetyl chloride in the
quantities reported in the Section 2. We find that the
nature of the product from this reaction is very sensitive
to the quantities of acetyl chloride used and also works
best if the container is freshly opened. This complex was
identified on the basis of its IR, 1H and 31P NMR
spectra. A value of 967 cmꢃ1 has been assigned for the
An examination of the occupancies for the O atom as
listed in Table 1 reveals that varying occupancies were
observed with the serendipitous results as afforded in
the structures of 3 and 7 and in the different prepara-
tions consisting of mixing different quantities of A, B
and C. The particular mixture of A, B and C that these
occupancies represent is given by the compositional
listing also in Table 1. Unfortunately, the tetrachloride
compound C proved to be very unstable in solution
affording the complex MoOCl3(OPMePh2)2, (6), when
we attempted to grow crystals of C directly. The
structure of this compound was previously reported
also as a benzene solvate but in this case 1 mol of
benzene crystallized with 1 mol of MoOCl3(OPMePh2)2
[32] instead of the 1/2 mol reported with 6, a situation
which resulted in different unit cell parameters. A
drawing of 6 is shown in Fig. 3. As 6 is believed to be
n(Mo(V)Ã
/
O) stretching frequency [19,20]. With B, this
stretch occurs at 970 cmꢃ1. Compound C, MoCl4(OP-
MePh2)2, was prepared by substitution of the THF
ligands in MoCl4(THF)2 [21] with OPMePh2. Unfortu-
nately, we were not capable of producing crystals of this
material.
composed entirely of MoOCl3(OPMePh2)2×
/1/2C6H6,
(and not a 50:50 mixture of A and C, based on IR
evidence of the crystals where only B and no A was
found) the disorder in the equatorial chloride and oxo
ligands is caused by packing disorder. Interestingly, even
this disorder can be accounted for by simply modeling
each disordered atom site as an oxygen atom. However,
3.2. Crystallographic results
Our interest in compositional disorder arose as a
result of the structural determination of the material
labeled as 3 and 7. It was not immediately apparent as to
this affords long MoÃ
/
O atom bond distances on the
˚
why different Mo to O atom distances (dMoÃO
:
/
1.8 and
order of 2 A and there is always substantial residual
electron density near the O atoms on the opposite side of
˚
2 A) were being resolved in these structures, i.e. if the
disorder is accounted for solely as an O atom. It
occurred to us that this may be another case of
the MoÃ
/
O interaction. In all cases, the nature of the
disorder was resolved by constraining the MoÃ
/O

Table 1
Crystal data and structure refinement details for 1ꢁ
/
7
1
2
3
4
5
6
7
Composition
MoO2Cl2(OPMePh2)2 40.2% MoO2Cl2(OP-
30.8% MoO2Cl2(OP-
14% MoO2Cl2(OP-
MePh2)2, 59.8% MoO1- MePh2)2, 69.2% MoO1- MePh2)2 86% MoO-
4% MoO2Cl2(OP-
MePh2)2 96% MoO-
Cl3(OPMePh2)2
52.3(8)
100% MoOCl3(OP- 82% MoOCl3(OP-
MePh2)2
MePh2)2 18% Mo-
Cl4(OPMePh2)2
40.8(9)
Cl3(OPMePh2)2
70.1(7)
Cl3(OPMePh2)2
65.4(6)
Cl3(OPMePh2)2
56.7(6)
Disorder
(O atom%)
Formula
Mr
100
49.1(5)
C26H26Cl2Mo1O4P2
631.3
yellow prism
C29H29Cl2.60Mo1O3.40P2 C29H29Cl2.69Mo1O3.31P2 C29H29Cl2.86Mo1O3.14P2 C29H29Cl2.96Mo1O3.04P2 C29H29Cl3Mo1O3P2 C29H29Cl3.18Mo1O2.82P2
689.8
682.0
green prism
683.8
green prism
687.1
green prism
689.0
green prism
693.30
pale green prism
Habit
light yellow-green
needle
Crystal system
Space group
monoclinic
P21/c
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/n
˚
a (A)
9.2615(16)
17.5140(40)
17.8060(40)
90
9.2624(19)
15.622(2)
21.200(4)
90
9.280(4)
15.624(4)
21.181(4)
90
9.2810(13)
15.5960(3)
21.1770(33)
90
9.3293(18)
15.632(3)
21.218(4)
90
9.2441(2)
15.4437(3)
21.0214(4)
90
9.2343(20)
15.5413(27)
21.1078(28)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
104.959(17)
90
97.591(17)
90
97.65(2)
90
97.695(13)
90
97.727(15)
90
97.9807(8)
90
97.686(15)
90
3
˚
V (A )
l (Mo Ka
radiation)
2790.4(10)
0.71073
3040.8(10)
0.71073
3043.5(16)
0.71073
3037.7(9)
0.71073
3066.2(10)
0.71073
2972.01
0.71073
3002.02(6)
0.71073
Temperature (K) 293
Z
293
4
293
4
293
4
293
4
120
4
223
4
4
Dx (g cmꢃ3
F(000)
)
1.50
1280
1.490
1364
1.493
1364
1.503
1400
1.498
1400
1.542
1400
graphite
kCCD
1.526
1400
Monochromator graphite
Diffractometer
graphite
EN CAD4
graphite
EN CAD4
graphite
EN CAD4
graphite
EN CAD4
graphite
EN CAD4
EnrafꢁNonius
/
(EN) CAD4
Diffraction
geometry
k-geometry
diffractometer
k
k
k
k
k
a
Type of scan
m (Mo Ka)
(mm-1)
v ꢁ/2u scans
v ꢁ
0.74
/2u scans
v ꢁ
0.744
/
2u scans
v ꢁ
0.83
/
2u scans
v ꢁ
0.822
/
2u scans
multi-scan
0.848
v ꢁ2u scans
0.84
/
0.81
Crystal size
(mm)
0.30ꢅ0.25ꢅ0.20
0.20ꢅ0.15ꢅ0.10
0.20ꢅ0.18ꢅ0.12
0.20ꢅ0.15ꢅ0.15
0.40ꢅ0.2ꢅ0.15
0.40ꢅ0.08ꢅ0.07
0.50ꢅ0.30ꢅ0.30
Number of
reflections
2uRange (8)
25
25
25
25
25
25
25
16.2ꢁ
/24
20ꢁ
/30
20ꢁ
/30
19.56ꢁ
/
27.78
19.38ꢁ
/
27.7
5.1ꢁ
/
64.08
20ꢁ30
/
b
Semiempirical absorption coefficient
Number of c-
scans
222
185
5
249
7
259
7
185
5
185
5
Number of
reflections
6

Table 1 (Continued)
1
2
3
4
5
6
7
Transmission coefficients
Min
Max
0.730
0.851
24.97
0.8695
0.9262
24.97
0.742
0.862
24.97
0.8681
0.893
22.47
0.6036
0.8635
24.97
0.784
0.936
32.04
0.6788
0.7867
22.48
u max (8)
H
0ꢁ
/
11
0ꢁ
/
11
0ꢁ
/
11
0ꢁ
/
9
0ꢁ
/
11
0ꢁ
/
13
0ꢁ
/
9
K
0ꢁ
/
20
0ꢁ
/
18
0ꢁ
/
18
0ꢁ
/
16
0ꢁ
/
18
ꢃ23 to 23
ꢃ31 to 31
10 136
0ꢁ
/
16
L
ꢃ21 to 20
4892
ꢃ25 to 24
5338
ꢃ25 to 24
5335
ꢃ22 to 22
3945
ꢃ25 to 24
5382
ꢃ22 to 22
3907
c
Number of
reflections
measured
Number of
observed data
[jIjꢀ2s(I)]
Number of
parameters
Rint
2882
311
3075
353
3777
349
2822
352
3038
352
6347
329
2676
353
0.024
0.041
0.105
0.030
0.071
0.179
0.020
0.054
0.142
0.022
0.041
0.096
0.049
0.070
0.166
0.031
0.066
0.019
0.027
0.057
0.151
d
R(F)
wR(F2)
e
f
g
h
i
j
k
l
Goodness-of-fit 0.997
Max. (D/s)
1.037
0.001
1.039
0.001
1.021
0.017
1.02
0.005
1.169
0.005
1.045
0.067
0.005
ꢃ3
˚
Residual DQ (e A
)
0.297
Max
Min
1.287
ꢃ1.033
1.299
ꢃ1.178
0.513
ꢃ0.645
0.941
ꢃ1.42
0.935
ꢃ1.383
1.252
ꢃ1.4
ꢃ0.338
Scattering factors from International Tables for Crystallography (Vol. C).
a
H.K.L. Scalepack ([24]).
North [24].
b
c
Denzo and Scalepack ([28]).
Rꢂa(FoꢃFc)/a(Fo).
d
Rwꢂ[a[w(Fo2ꢃFc2)2]/a[w(Fo2)2]]1/2
.
e
wꢂ1/[2(F2o)ꢄ(0.0468ꢅP)2ꢄ0.4076P], where Pꢂ(max(Fo2, 0)ꢄ2ꢅF2c)/3.
f
wꢂ1/[2(F2o)ꢄ(0.0581ꢅP)2ꢄ12.4113P].
g
h
i
wꢂ1/[2(F2o)ꢄ(0.0519ꢅP)2ꢄ8.5275P].
wꢂ1/[2(F2o)ꢄ(0.0322ꢅP)2ꢄ5.3651P].
wꢂ1/[2(F2o)ꢄ(0.1126ꢅP)2ꢄ0.0000P].
j
wꢂ1/[2(F2o)ꢄ(0.0137ꢅP)2ꢄ8.2246P].
k
l
wꢂ1/[2(F2o)ꢄ(0.0562ꢅP)2ꢄ15.6020P].

252
F.R. Fronczek et al. / Inorganica Chimica Acta 342 (2003) 247ꢁ254
/
Table 2
˚
Selected bond lengths (A) and angles (8) for 1ꢁ7
/
1
2
3
4
5
6
7
Bond lengths
Mo1ÃO1
Mo1ÃO2
Mo1ÃCl1
Mo1ÃCl2
Mo1ÃO3
Mo1ÃO4
Mo1ÃCl3
Mo1ÃCl4
2.206(3)
2.160(3)
2.3962(15)
2.3816(15)
1.676(3)
1.677(3)
2.139(5)
2.115(6)
2.398(3)
2.367(3)
1.735(5)
1.736(5)
2.316(5)
2.313(5)
2.143(4)
2.121(4)
2.3959(19)
2.3703(19)
1.746(5)
1.761(5)
2.292(4)
2.268(4)
2.116(4)
2.119(3)
2.3941(18)
2.3750(18)
1.748(5)
1.733(5)
2.282(4)
2.250(4)
2.115(5)
2.122(5)
2.398(2)
2.374(2)
1.735(5)
2.116(2)
2.119(3)
2.4004(10)
2.3814(10)
1.754(5)
1.725(5)
2.266(2)
2.196(3)
2.151(5)
2.114(6)
2.369(3)
2.399(3)
1.742(5)
1.743(5)
2.319(5)
2.320(5)
1.7322(5)
2.279(4)
2.304(4)
Bond angles
CHÃMo1ÃO1
CHÃMo1ÃO2
CHÃMo1ÃO3
CHÃMo1ÃO4
CHÃMo1ÃCl2
Cl2ÃMo1ÃO1
Cl2ÃMo1ÃO2
Cl2ÃMo1ÃO3
Cl2ÃMo1ÃO4
O1ÃMo1ÃO3
O1ÃMo1ÃO4
O1ÃP1ÃC10
83.92(9)
85.49(9)
85.55(17)
86.42(18)
93.7(4)
85.61(12)
86.91(13)
93.6(4)
87.21(12)
86.34(11)
92.9(3)
87.72(16)
86.60(15)
92.0(4)
86.42(8)
87.48(8)
92.9(3)
85.84(17)
85.09(18)
93.6(4)
94.18(15)
94.70(13)
166.08(5)
85.64(9)
93.2(4)
92.5(3)
93.2(3)
92.3(5)
92.2(2)
93.7(3)
168.84(10)
85.86(17)
84.95(18)
93.6(4)
169.53(7)
86.13(12)
85.27(13)
93.5(4)
170.59(6)
85.36(12)
86.71(11)
92.9(3)
171.55(8)
85.85(16)
86.99(15)
93.8(4)
171.07(4)
86.88(8)
85.57(8)
92.6(3)
168.80(9)
85.40(17)
86.40(18)
93.9(4)
83.33(9)
94.38(15)
94.27(12)
169.35(14)
88.81(14)
113.4(2)
94.2(4)
170.6(4)
92.0(3)
94.5(3)
170.7(4)
93.7(3)
93.3(3)
90.2(3)
93.2(5)
173.1(4)
90.0(5)
94.0(2)
169.6(3)
92.3(2)
93.6(3)
170.5(4)
92.5(4)
171.5(3)
113.3(3)
113.1(3)
98.3(4)
112.9(4)
113.0(5)
97.5(5)
113.1(3)
113.3(3)
95.6(5)
113.2(4)
113.0(4)
96.9(6)
112.73(17)
113.58(19)
98.0(3)
112.9(4)
112.6(4)
97.1(5)
O2ÃP2ÃC20
113.1(2)
O3ÃMo1ÃO4
Mo1ÃO1ÃP1
Mo1ÃO2ÃP2
Cl3ÃMo1ÃO1
Cl3ÃMo1ÃO2
Cl3ÃMo1ÃO4
Cl3ÃMo1ÃC11
Cl3ÃMo1ÃCl2
Cl3ÃMo1ÃCl4
Cl4ÃMo1ÃO1
Cl4ÃMo1ÃO2
Cl4ÃMo1ÃO3
Cl4ÃMo1ÃCl1
Cl4ÃMo1ÃCl2
O3ÃMo1ÃO1
O3ÃMo1ÃO2
O4ÃMo1ÃO1
O4ÃMo1ÃO2
101.80(16)
139.59(18)
156.5(2)
145.2(4)
153.4(4)
169.9(3)
91.0(3)
145.3(3)
152.3(3)
170.9(3)
91.2(3)
151.9(3)
145.1(2)
90.2(3)
151.3(4)
146.0(3)
170.7(2)
89.7(2)
144.40(16)
149.47(18)
170.60(9)
90.42(9)
97.0(2)
144.6(4)
152.6(4)
169.5(3)
90.5(3)
170.3(2)
97.6(4))
93.42(13)
92.45(13)
98.5(2)
98.1(4)
94.9(2)
95.5(3)
94.2(2)
93.0(2)
99.2(5)
98.0(4)
92.54(7)
94.2(2)
92.64(17)
92.82(17)
98.4(2)
93.2(2)
92.3(2)
101.1(4)
89.0(3)
93.10(7)
98.70(9)
90.68(10)
170.82(10)
99.7(3)
100.4(3)
88.72(19)
168.3(2)
100.6(4)
92.79(16)
93.46(16)
170.7(4)
91.1(4)
100.9(3)
89.6(3)
90.89(16)
90.5(2)
99.2(4)
90.8(2)
172.0(2)
96.0(4)
168.0(3)
100.4(5)
92.6(3)
168.6(3)
100.0(5)
94.0(3)
92.63(17)
93.77(17)
90.2(3)
92.95(17)
92.62(17)
173.1(4)
92.0(4)
93.12(7)
92.86(7)
169.6(3)
89.4(3)
94.4(3)
92.9(3)
170.6(4)
91.6(4)
92.0(3)
170.5(1)
91.5(4)
92.5(4)
170.3(3)
171.5(3)
91.5(3)
93.7(3)
173.3(3)
90.0(5)
171.1(5)
92.3(2)
172.5(3)
170.9(3)
171.5(4)
˚
distance to be approximately 1.7 A, and the MoÃ
/Cl
these structures display a similar geometry to that
displayed for 2 and 6 in Figs. 2 and 3, respectively.
The packing disorder in these structures is due to the
disordered arrangement of compound B.
˚
distance was set at 2.37 A. The occupancies were refined
(as pointed out in the Section 2) allowing for a
determination of the composition [26]. In all cases, the
presence of the mixtures as suggested in Table 1 was
confirmed qualitatively by obtaining the IR spectra of
the compounds verifying that both MoO2Cl2(OP-
MePh2)2 and MoOCl3(OPMePh2)2 were present.
As the experimental and crystallographic data indi-
cate, we were not successful in obtaining material
containing the tetrachloride MoCl4(OPMePh2)2 (C).
Despite our precautions regarding drying solvents and
exclusion of moist air, mixtures initially containing C
resulted in crystals where C transformed into MoO-
Cl3(OPMePh2)2 (B). Evidence of C was only found for
the crystals labeled as 7 produced in the reaction
between of MoWCl4(PMePh2)4 [15] and 4 equiv. of
LiNPh2, which had also produced (in a different
experimental run) material of composition labeled as
We believe that compounds labeled as 2ꢁ5 and 7
/
represent materials exhibiting compositional as well as
packing disorder. This is a particularly noteworthy
feature about these compounds. The composition data
listed in Table 1 show that the quantity of MoO2-
Cl2(OPMePh2)2 (A), to MoOCl3(OPMePh2)2 (B), de-
creases from 40.2/59.8 in 2 to 4/96 in 5. Essentially, all of

F.R. Fronczek et al. / Inorganica Chimica Acta 342 (2003) 247ꢁ
/
254
253
(as determined crystallographically) is to have composi-
tional disorder with B and C.
There are some noteworthy differences in the geome-
tries of complexes 1ꢁ
O atom bond distances for the O atom in the phosphine
/
7, see Table 2. First, the two MoÃ
/
˚
oxide ligand at 2.160(3) and 2.206(3) A are significantly
different in 1. In some cases, namely 4ꢁ6, these distances
are not significantly different but the distances in 1 are
longer than the corresponding distances in 2ꢁ7. This
difference is reflected in the MoÃOÃP angles where
those in 1 again display the largest range at 139.59(18)
and 156.5(2)8. The smaller angle in complexes 2ꢁ
/
/
/
/
/
7
ranges from 144.40(6) to 146.0(3)8 and the larger one
ranges from 149.47(18) to 153.4(4)8. The corresponding
Fig. 1. ORTEP-3 [30] representation of
1 with 20% probability
ellipsoids. Spheres of arbitrary radii represent H atoms. The major
orientation (68.2(5)%) in the disordered phenyl ring on the right of the
drawing is the one almost perpendicular to the plane of the paper.
angles in 1 are significantly different from those in 2ꢁ
There are some slight differences in the axial trans-
chloride ligands distances and angles, i.e. Cl1ÃMoÃCl2.
/7.
/
/
This angle ranges from 166.08(5)8 in 1 to 171.55(8)8 in 5
similar to bond angles in related structures [32,33]. The
two oxo ligands complete the coordination sphere in 1
and, the MoÃ
/
O(oxo) bond distances here, as expected,
are the shortest. In the other structures, this distance
˚
ranges from 1.725(5) to 1.761(5) A which is no doubt a
consequence of the packing and compositional disorder.
Cl(eq) bond
This disorder also results in shorter MoÃ
/
distances compared with the MoÃCl(ax) bond distances.
/
In summary, a variety of disorder was found in these
crystallographic studies ranging from solvent, ligand,
packing and compositional disorder. The refinement
suggests that complexes A and B can co-crystallize and
evidence was found for B and C on one occasion. As of
this moment, we do not have evidence that A and C can
co-crystallize or that ternary mixtures can be produced
[16c] with these series of compounds. Attempts to define
this were thwarted by the unfortunate decomposition
of C.
Fig. 2. ORTEP-3 [30] representation of 2 at 50% probability ellipsoids,
without the benzene molecule of solvation. H atoms are not shown.
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 182926ꢁ
/
182932 for com-
pounds 1ꢁ7, respectively. Copies of this information
/
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(fax: ꢄ44-1223-336-033; e-mail: deposit@ccdc.cam.ac.
uk or www: http://www.ccdc.cam.ac.uk).
/
Fig. 3. ORTEP-3 [30] representation of 6 at 50% probability ellipsoids,
without the benzene molecule of solvation. Spheres of arbitrary radii
represent H atoms.
3. The IR of this mixture clearly indicated the presence
of B and did not indicate A. The only way (assuming
refining occupancies is meaningful in all cases) to
account for the below 50% occupancy of the O atom
Acknowledgements
We thank Michigan Technological University and the
NSF (CHE-0079158) for generous support.

254
F.R. Fronczek et al. / Inorganica Chimica Acta 342 (2003) 247ꢁ254
/
G.F. Neilson, R.P. Sperline, J.H. Enemark,
Wieghardt, Inorg. Chem. 33 (1994) 15.
G Backes, K.
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