Template Synthesis and Reactions of Tricarbonylmolybdenum Phosphadithiamacrocycle Complexes

Article abstract of DOI:10.1021/ic961143i

Treatment of [Me₄N]₂[PhP(CH₂CH₂S)₂] with [Mo(CO)₃(NCMe)₃] affords the reactive intermediate [Me₄N]₂[Mo(CO)₃{PhP(CH₂CH ₂S)₂}] (1), which undergoes oxidation to afford [Mo{PhP(CH₂CH₂S)₂}₂] (2), Reaction of 1 with a variety of dichloroalkanes produces [Mo(CO)₃{c-PhP(CH₂CH₂S)₂X)] (X = CH₂CH₂, CH₂CH₂CH₂, CH₂CHMe or CH₂CH(OH)CH₂). The structure of [Mo(CO)₃{c-PhP(CH₂CH₂S)₂CH ₂CH₂}] (3) has been established by X-ray crystallography and consists of a Mo(CO)₃ fragment facially coordinated by the tridentate c-PhP(CH₂CH₂S)₂CH₂CH₂ ligand. Reaction of 3 with bromine affords seven-coordinate [Mo(CO)₂{c-PhP(CH₂-CH₂S)₂CH ₂CH₂]Br₂] (7), the X-ray crystal structure of which reveals a carbonyl-capped octahedral geometry. Treatment of 3 with sulfur results in loss of the Mo(CO)₃ fragment and isolation of c-PhPS(CH₂CH₂S)₂CH₂CH₂ (8), the X-ray structure of which shows a nine-membered ring with the phosphorus center bearing phenyl and sulfide substituents. Reduction of 8 with sodium naphthalenide affords the parent ligand c-PhP(CH₂CH₂S)₂CH₂-CH₂. Crystal data: 2, C₂₀H₂₆MoP₂S₄, triclinic P1, a = 8.105(3) ?, b = 8.263(3) ?, c = 17.663(4) ?, a = 100.29(2)°, β = 99.78(2)°, γ = 98.81(2)°, Z = 2; 3, C₁₅H₁₇MoO₃PS₂, monoclinic P2₁/n, a = 9.600(3) ?, b = 15.594(5) ?, c = 11.335(3) ?, β = 93.01(2)°, Z = 4; 7, C₁₄H₁₇Br₂MoO₂PS₂, monoclinic P2₁/c, a = 17.039(3) ?, b = 8.686(2) ?, c = 12.466(3) ?, β = 100.52(2)°, Z = 4; 8, C₁₂H₁₇PS₃, monoclinic P2₁, a = 6.651(4) ?, b = 7.313(2) ?, c = 14.687(9) ?, β= 101.62(3)°, Z = 2.

Full text of DOI:10.1021/ic961143i

1578
Inorg. Chem. 1997, 36, 1578-1582
Template Synthesis and Reactions of Tricarbonylmolybdenum Phosphadithiamacrocycle
Complexes
Philip J. Blower,† John C. Jeffery,‡ John R. Miller,§ Spencer N. Salek,† Dirk Schmaljohann,†
Raymond J. Smith,† and Michael J. Went*,|
Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K., Department of
Inorganic Chemistry, The University of Bristol, Bristol BS8 1TS, U.K., Department of Chemistry and
Biological Chemistry, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K., and Department
of Chemistry, University of Kent, Canterbury, Kent CT2 7NH, U.K.
ReceiVed September 18, 1996X
Treatment of [Me4N]2[PhP(CH2CH2S)2] with [Mo(CO)3(NCMe)3] affords the reactive intermediate
[Me4N]2[Mo(CO)3{PhP(CH2CH2S)2}] (1), which undergoes oxidation to afford [Mo{PhP(CH2CH2S)2}2] (2).
Reaction of 1 with a variety of dichloroalkanes produces [Mo(CO)3{c-PhP(CH2CH2S)2X}] (X ) CH2CH2,
CH2CH2CH2, CH2CHMe or CH2CH(OH)CH2). The structure of [Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}] (3) has
been established by X-ray crystallography and consists of a Mo(CO)3 fragment facially coordinated by the tridentate
c-PhP(CH2CH2S)2CH2CH2 ligand. Reaction of 3 with bromine affords seven-coordinate [Mo(CO)2{c-PhP(CH2-
CH2S)2CH2CH2}Br2] (7), the X-ray crystal structure of which reveals a carbonyl-capped octahedral geometry.
Treatment of 3 with sulfur results in loss of the Mo(CO)3 fragment and isolation of c-PhPS(CH2CH2S)2CH2CH2
(8), the X-ray structure of which shows a nine-membered ring with the phosphorus center bearing phenyl and
sulfide substituents. Reduction of 8 with sodium naphthalenide affords the parent ligand c-PhP(CH2CH2S)2CH2-
CH2. Crystal data: 2, C20H26MoP2S4, triclinic P1h, a ) 8.105(3) Å, b ) 8.263(3) Å, c ) 17.663(4) Å, R )
100.29(2)°, â ) 99.78(2)°, γ ) 98.81(2)°, Z ) 2; 3, C15H17MoO3PS2, monoclinic P21/n, a ) 9.600(3) Å, b )
15.594(5) Å, c ) 11.335(3) Å, â ) 93.01(2)°, Z ) 4; 7, C14H17Br2MoO2PS2, monoclinic P21/c, a ) 17.039(3)
Å, b ) 8.686(2) Å, c ) 12.466(3) Å, â ) 100.52(2)°, Z ) 4; 8, C12H17PS3, monoclinic P21, a ) 6.651(4) Å, b
) 7.313(2) Å, c ) 14.687(9) Å, â ) 101.62(3)°, Z ) 2.
Introduction
Previous reports have addressed the preparation of mixed
phosphathiamacrocycles, although they all concern ring sizes
of 11 or greater.6-8 Eleven-membered phosphathiatrihetero-
macrocycles of the type 2,6,10-triheterobenzo[11]crown-3 have
been prepared by the high-dilution reactions of a bis(nucleophile)
with a bis(electrophile), and coordination to M(CO)3 (M ) Cr,
Mo, W) fragments has been demonstrated.7,8
Our studies have concentrated on the synthesis of mixed
phosphathiacyclononanes, and we have previously reported the
synthesis of c-PhP(CH2CH2S)2CH2CH2 (L) by a high-dilution
method.1 This paper reports the template synthesis and reactiv-
ity of phosphadithiacyclononanes and related cyclodecanes.
Our study of mixed phosphathiamacrocycles attempts to
combine the areas of phosphine coordination chemistry and the
more recent developments in thiamacrocycle coordination
chemistry.1 The chemistry of complexes containing phosphine
ligands has been studied intensively, and a vast number of mono-
and didentate phosphine complexes are known, some of which
have important catalytic properties. In comparison, thioethers
are relatively weakly bound ligands.2 However, thioether
macrocycles and in particular 1,4,7-trithiacyclononane (9S3) are
capable of producing metal complexes of high thermodynamic
and kinetic stability.3,4 The unique properties of 9S3 are a result
of the combination of the macrocyclic effect with a conformation
which is ideal for facial tridentate coordination, and many 9S3
complexes exhibit interesting electronic and electrochemical
properties. These observations lead to the speculation as to
whether the combination of the nine-membered-ring confor-
mational properties with phosphine donor centers might offer
complexes with even greater stability and novelty. Recent
reports suggest that syntheses of triphosphacyclononane com-
plexes using a group 6 metal tricarbonyl template are difficult.5
Experimental Section
All reactions were carried out under an atmosphere of nitrogen using
standard Schlenk tube and vacuum line techniques, and all solvents
were freshly distilled under a nitrogen atmosphere and over appropriate
drying agents. Petroleum ether (bp 40-60 °C) and dichloromethane
were distilled over calcium hydride, and tetrahydrofuran was distilled
over potassium. The compound PhP(CH2CH2SH)2 was prepared by a
literature method.9 Fast atom bombardment and chemical ionization
spectra were recorded by the EPSRC Mass Spectrometry Service at
the University of Swansea with a VG ZAB-E instrument. FAB spectra
were recorded from a matrix sample with NOBA. Infrared spectra
† Department of Biosciences, University of Kent.
‡ The University of Bristol.
§ University of Essex.
(6) Champness, N. R.; Frampton, C. S.; Reid, G.; Tocher, D. A. J. Chem.
Soc., Dalton Trans. 1994, 3031.
(7) Kyba, E. P.; John, A. M.; Brown, S. B.; Hudson, C. W.; McPhaul,
M. J.; Harding, A.; Larsen, K.; Niedzwiecki, S.; Davies, R. E. J. Am.
Chem. Soc. 1980, 102, 139.
| Department of Chemistry, University of Kent.
X Abstract published in AdVance ACS Abstracts, March 1, 1997.
(1) Smith, R. J.; Powell, A. K.; Barnard, N.; Dilworth, J. R.; Blower, P.
J. J. Chem. Soc., Chem. Commun. 1993, 54.
(2) Murray, S. G.; Hartley, F. R. Chem. ReV. 1981, 81, 365.
(3) Blake, A. J.; Schro¨der, M. AdV. Inorg. Chem. 1990, 35, 1.
(4) Cooper, S. R.; Rawle, S. C. Struct, Bonding (Berlin) 1990, 72, 1.
(5) Edwards, P. G.; Fleming, J. S.; Liyanage, S. S.; Coles, S. J.;
Hursthouse, M. B. J. Chem. Soc., Dalton Trans. 1996, 1801.
(8) Fox, M. A.; Campbell, K. A.; Kyba, E. P. Inorg. Chem. 1981, 20,
4163.
(9) Blower, P. J.; Dilworth, J. R.; Leigh, G. J.; Neaves, B. D.; Normanton,
F. B.; Hutchinson, J.; Zubieta, J. A. J. Chem. Soc., Dalton Trans.
1985, 2647.
S0020-1669(96)01143-3 CCC: $14.00 © 1997 American Chemical Society

Tricarbonylmolybdenum Phosphadithiamacrocycles
Inorganic Chemistry, Vol. 36, No. 8, 1997 1579
Table 1. Analyticala and Physical Data
analysis (%)
compd
appearance
yield (%)
ν
max(CO)b (cm-1
)
C
H
Mc
2
3
4
5
6
7
8
red solid
20
70
61
37
32
67
18
43.8 (43.5)
40.4 (41.3)
42.1 (42.7)
42.7 (42.7)
41.1 (41.2)
29.8 (29.6)
48.0 (50.0)
5.0 (4.7)
3.7 (3.9)
4.0 (4.3)
4.8 (4.3)
4.9 (4.1)
3.1 (3.0)
5.8 (5.9)
554
438
452
yellow solid
yellow solid
yellow solid
yellow solid
orange solid
white solid
1920 s, 1822 s, 1796 s
1922 s, 1822 s, 1790 s
1922 s, 1794 s
1924 s, 1804 s
1948 s, 1888 m
a Calculated values are given in parentheses. b Recorded as Nujol mulls. c Fast atom bombardment (FAB) mass spectroscopy.
Table 2. Details of the X-ray Structure Analyses for Compounds 2, 3, 7, and 8a
2
3
7
8
formula
fw
λ (Å)
space group
temp (K)
cell constants
a (Å)
C20H26MoP2S4
552.53
0.710 73
P1h
C15H17MoO3PS2
436.32
0.710 73
P21/n
C14H17Br2MoO2PS2
568.13
0.710 73
P21/c
C12H17PS3
288.4
0.710 73
P21
173
173
173
291
8.105(3)
8.263(3)
17.663(4)
100.29(2)
99.78(2)
98.81(2)
1126.4(6)
2
1.63
1.10
0.0516
0.0205
1.0660
0.0201
9.600(3)
15.594(5)
11.335(3)
17.039(3)
8.686(2)
12.466(3)
6.651(4)
7.313(2)
14.687(9)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
93.01(2)
100.52(2)
101.62(3)
1694.4(9)
4
1.71
1.122
0.0552
0.0202
1.3702
0.0225
1814.1(7)
4
2.08
699.7(6)
2
1.37
Dc (g cm-3
µ (mm-1)
)
5.45
0.595
wR2 (F2, all reflcns)
d
0.150
0.0917
0.0
e
R1 (F, Fo > 4σ(Fo))
R (F, Fo > 3σ(Fo))
R′ (F, Fo > 3σ(Fo))
0.0577
0.070
0.096
a wR2 ) [∑[w(Fo - Fc2)2]/∑w(Fo )2]1/2; w-1 ) σ2(Fo ) + (dP)2 + eP; P ) [max(Fo,0) + 2Fc2]/3.
2
2
2
were recorded with a Perkin-Elmer 983G spectrophotometer, and NMR
spectra were recorded with a JEOL GX 270 instrument. Elemental
analyses were performed by Mr. A. J. Fassam at the University of Kent.
Analytical and physical data for the new compounds are given in Table
1.
Preparation of [Me4N]2[Mo(CO)3{PhP(CH2CH2S)2}]. A solution
of PhP(CH2CH2SH)2 (1.00 g, 4.34 mmol) in 25% methanolic tetra-
methylammonium hydroxide (3.66 mL, 8.80 mmol) was stirred for 3
min. Removal of the solvent in Vacuo afforded a quantitative yield of
[Me4N]2[PhP(CH2CH2S)2], which was then stirred for 20 h with a
solution of [Mo(CO)3(NCMe)3], prepared by refluxing [Mo(CO)6] (1.15
g, 4.36 mmol) for 3 h in MeCN (15 mL). The resulting solution was
then cooled to -20 °C to afford bright yellow crystals of [Me4N]2-
[Mo(CO)3{PhP(CH2CH2S)2}] (1) (1.83 g, 67%) after removal of the
solvent Via a cannular tube and drying in Vacuo.
formed. The solvent was removed Via a cannular tube, and the solid
was washed with diethyl ether and then dried in Vacuo to afford
[Mo(CO)2{c-PhP(CH2CH2S)2CH2CH2}Br2] (7) (0.046 g, 67%).
Preparation of PhPS(SCH2CH2S)2(CH2CH2). Sulfur (0.407 g,
15.9 mmol) and 3 (0.5 g, 1.47 mmol) were refluxed in toluene (100
mL) for 12 h. The black solution was filtered and the solvent removed
in Vacuo. The green solid was chromatographed on silica gel 62, 60-
200 mesh, by eluting with CH2Cl2. Removal of the solvent from a
band with an Rf value of 0.36 afforded PhPS(SCH2CH2S)2(CH2CH2)
(8) (0.076 g, 18%). NMR (CD2Cl2): 1H δ 7.98-7.50 (m, Ph, 5 H),
3.32-2.65 (m, CH2, 12 H); 13C{1H} δ 131.9-129.0 (m, Ph), 36.2 [d,
PCH2, J(PC) 52 Hz], 35.3 (s, SCH2CH2S), 28.3 [d, PCH2CH2S, J(PC)
5 Hz]; 31P{1H} δ 47.5.
Reduction of PhPS(SCH2CH2S)2(CH2CH2). A sample of 8 (0.12
g, 0.44 mmol) was treated with a freshly prepared THF solution of
sodium naphthalenide (0.9 mmol), and the mixture was stirred for 24
h. The reaction mixture was then hydrolyzed and the solvent removed
in Vacuo. GC-MS analysis of the product mixture revealed a molecular
ion for PhP(SCH2CH2S)2(CH2CH2) at m/z 257.
Preparation of [Mo{PhP(CH2CH2S)2}2]. A solution of 1 (0.50 g,
1.23 mmol) in acetonitrile (25 mL) and methanol (10 mL) was exposed
to the air for 4 weeks. The dark red crystals that formed were washed
with methanol (20 mL) to afford [Mo{PhP(CH2CH2S)2}2] (2) (0.14 g,
20%)
Crystal Structure Determinations of 2, 3, and 7. Details of the
X-ray structure analyses are summarized in Table 2. Crystals of
[Mo{PhP(CH2CH2S)2}2] (2) were obtained from MeCN/MeOH solution.
A crystal was mounted on a glass fiber, and low-temperature data were
collected on a Siemens SMART area-detector three-circle diffractometer
(Mo KR X-radiation, graphite monochromator, λ ) 0.710 73 Å). For
three settings of φ, narrow data “frames” were collected for 0.3°
increments in ω. A total of 1271 frames of data were collected,
affording rather more than a hemisphere of data for the complex. At
the end of data collection, the first 50 frames of data were recollected
to establish that crystal decay had not taken place during the course of
data collection. The substantial redundancy in data allowed empirical
absorption corrections to be applied using multiple measurements of
equivalent reflections. Data frames were collected for 10 s per frame,
Preparation of [Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}]. To a
suspension of 1 (1.73 g, 3.1 mmol) in MeCN (20 mL) was added 1,2-
dichloroethane (0.31 g, 3.1 mmol) dropwise. After 30 min, the solvent
was removed Via a cannular tube, and the green-yellow product was
dried in Vacuo, washed with methanol (30 mL), and dried in Vacuo to
afford [Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}] (3) (1.35 g, 70%). The
complexes[Mo(CO)3{c-PhP(CH2CH2S)2CH2CH(Me)}](4),[Mo(CO)3{c-
PhP(CH2CH2S)2CH2CH2CH2)}] (5), and [Mo(CO)3{c-PhP(CH2CH2S)2-
CH2CHOHCH2)}] (6) were prepared by analogous procedures.
Preparation of [Mo(CO)2{c-PhP(CH2CH2S)2CH2CH2}Br2]. Bro-
mine (0.018 g, 0.11 mmol) was added dropwise to a solution of 3 (0.050
g, 0.11 mmol) in CH2Cl2 (15 mL) over a 10 min period. The mixture
was then stirred for 30 min, during which an orange-yellow precipitate

1580 Inorganic Chemistry, Vol. 36, No. 8, 1997
Blower et al.
giving an overall time for data collection of ca. 7 h. The data frames
were integrated using SAINT.10
The structure was solved by conventional direct methods procedures
and was refined by full-matrix least-squares calculations on all F2 data
using Siemens SHELXTL 5.03.10 All non-hydrogen atoms were refined
with anisotropic thermal parameters. Hydrogen atoms were included
in calculated positions with isotropic thermal parameters ca. 1.2 times
the equivalent isotopic thermal parameters of their parent carbon atoms
(C-H distances were allowed to refine). All calculations were carried
out on a Silicon Graphics Indy or Indigo computer.
Crystals of [Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}] (3) were ob-
tained by slow evaporation of a CH2Cl2 solution, and small, poorly
diffracting crystals of [Mo(CO)2{c-PhP(CH2CH2S)2CH2CH2}Br2] (7)
were obtained from CH2Cl2/hexane. Crystals were mounted, the data
collected, and the structures solved and refined in a manner similar to
2.
Crystal Structure Determination of 8. Crystals of PhPS{SCH2-
CH2S}2(CH2CH2) (8) were obtained from CH2Cl2. Intensity data were
collected on an Enraf-Nonius CAD4 diffractometer with graphite-
monochromated Mo KR X-radiation (λ ) 0.710 73 Å). Cell constants
were obtained from least-squares refinement of the setting angles of
25 centered reflections in the range 22° < θ < 25°. The data were
collected in the ω-2θ scan mode, and three standard reflections were
measured after every hour of exposure. A 1.2% loss of intensity was
observed, which was linearly corrected during processing. The data
were corrected for Lorentz and polarization factors, and an absorption
correction was applied using ψ scans of nine reflections.11 The structure
was solved by direct methods,12 locating all the non-hydrogen atoms.
Hydrogen atoms were added in calculated positions with B(eq) )
1.3B(eq) of the attached atom. A weighting scheme of the form w )
1/[σ2(Fo) + (0.02Fo)2] gave a satisfactory analysis of variance.13
Neutral-atom scattering factors were taken from ref 14.
Figure 1. Molecular structure of [Mo{PhP(CH2CH2S)2}2] (2).
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
[Mo{PhP(CH2CH2S)2}2] (2)
Mo-S(11)
2.3386(7)
2.3544(9)
2.4666(8)
1.833(2)
1.838(2)
1.840(2)
1.842(2)
1.520(3)
1.527(3)
Mo-S(21)
2.3404(10)
2.3648(8)
2.4772(10)
1.845(2)
1.849(2)
1.821(2)
1.828(2)
1.526(3)
1.524(3)
Mo-S(22)
Mo-S(12)
Mo-P(2)
Mo-P(1)
P(1)-C(113)
P(2)-C(213)
S(11)-C(111)
S(21)-C(221)
C(111)-C(112)
C(221)-C(212)
P(1)-C(112)
P(2)-C(212)
S(12)-C(114)
S(22)-C(214)
C(113)-C(114)
C(213)-C(214)
S(11)-Mo-S(21)
S(21)-Mo-S(22)
S(21)-Mo-S(12)
S(11)-Mo-P(2)
S(22)-Mo-P(2)
S(11)-Mo-P(1)
S(22)-Mo-P(1)
P(2)-Mo-P(1)
91.62(3)
117.48(3)
82.94(3)
157.23(2)
79.10(3)
82.35(3)
85.49(3)
110.73(3)
S(11)-Mo-S(22)
S(11)-Mo-S(12)
S(22)-Mo-S(12)
S(21)-Mo-P(2)
S(12)-Mo-P(2)
S(21)-Mo-P(1)
S(12)-Mo-P(1)
83.64(3)
117.93(3)
151.07(2)
83.38(3)
83.60(3)
155.58(2)
79.15(3)
Results and Discussion
We found previously that the template synthesis of 9S3 can
be adapted to prepare a range of carbon-functionalized deriva-
tives.15 The substituents were introduced Via substituted 1,2-
dibromopropanes, by cyclization with 3-thiapentane-1,5-
dithiolate in the form of its molybdenum complex
[Mo(CO)3{S(CH2CH2S)2}]2-. This approach was adapted for
the synthesis of nine- and ten-membered phosphadithiamacro-
cycles. Reaction of [Me4N]2[PhP(CH2CH2S)2] with [Mo(CO)3-
(NCMe)3] affords [Me4N]2[Mo(CO)3{PhP(CH2CH2S)2}] (1).
The o-phenylene analogue of 1, [Me4N]2[Mo(CO)3{PhP-
(C6H4S)2}], was structurally characterized by Dilworth et al.,16
but 1 was found to be too air-sensitive to characterize and was
used immediately in cyclization reactions analogously to the
9S3 synthesis.17 Exposure of a solution of 1 to air results in
formation of red crystals of the molybdenum(IV) complex
[Mo{PhP(CH2CH2S)2}2] (2). Compound 2 was characterized
by elemental analysis and FAB-MS (Table 1) and also by a
single-crystal X-ray diffraction study. The molecular structure,
which is a distorted octahedron, is shown in Figure 1, and
selected bond lengths and angles are given in Table 3. The
structure was reported previously but with a considerably higher
R value (9.8%);9 however, the structural parameters are the same
within error and will not be discussed further.
Reaction of 1 with a range of dichloroalkanes affords air-
stable molybdenum tricarbonyl complexes with cyclic phos-
phadithiamacrocycles (Scheme 1). Both nine-membered (3 and
4) and ten-membered (5 and 6) rings are formed in reasonable
yields. Compound 4 contains a pendant methyl group, while 6
has a pendant hydroxyl functionality. The hydroxyl group on
the carbon backbone in 6 is not expected to compete in
coordination to soft metal centers and could be easily trans-
formed into amines or other substituents with potential for
linking to proteins for nuclear medical purposes.18 The new
compounds were characterized by infrared spectroscopy, ele-
mental analyses, and, in the case of 3 and 4, FAB-MS, in which
molecular ions were observed (Table 1). The low solubility of
3-6 prevented the acquisition of high-quality NMR spectra.
The structure of 3 was established by a single-crystal X-ray
diffraction study. The molecular structure is shown in Figure
2, and selected bond lengths and angles are given in Table 4.
The structure is similar to that of Mo(9S3)(CO)3 with L facially
coordinated to the tricarbonylmolybdenum fragment.19 The
angles between the carbonyls are close to 90°, indicating a
pseudooctahedral geometry; however, the chelate bite angles
of L are all less than 90° (average 81.4°) but only slightly less
than the situation in [Mo(9S3)(CO)3] (average 82.8°). The
(10) Siemens Analytical Instruments, Madison, WI.
(11) CAD4 Operations Manual; Enraf-Nonius: Delft, The Netherlands,
1977.
(12) Sheldrick, G. M. SHELXS86: Program for the solution of crystal
structures. University of Go¨ttingen, Germany, 1985.
(13) MOLEN: An InteractiVe Structure Solution Procedure; Enraf-
Nonius: Delft, The Netherlands, 1990.
(14) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Tables 2.2B and 2.3.1.
(15) Smith, R. J.; Salek, S. N.; Went, M. J.; Blower, P. J.; Barnard, N. J.
J. Chem. Soc., Dalton Trans. 1994, 3165.
(16) Dilworth, J. R.; Hutson, A. J.; Lewis, J. S.; Miller, J. R.; Zheng, Y.;
Chen, Q.; Zubieta, J. J. Chem. Soc., Dalton Trans. 1996, 1093.
(17) Sellmann, D.; Zapf, L. J. Organomet. Chem. 1985, 289, 57.
(18) Alberto, R.; Nef, W.; Smith, A.; Kaden, T. A.; Neuberger, M.; Zehnder,
M.; Frey, A.; Abram, U.; Schubiger, P. A. Inorg. Chem. 1996, 35,
3420.
(19) Ashby, M. T.; Lichtenberger, D. L. Inorg. Chem. 1985, 24, 636.

Tricarbonylmolybdenum Phosphadithiamacrocycles
Inorganic Chemistry, Vol. 36, No. 8, 1997 1581
Scheme 1
Figure 2. Molecular structure of [Mo(CO)3{c-PhP(CH2CH2S)2CH2-
CH2}] (3).
Figure 3. Molecular structure of [Mo(CO)2{c-PhP(CH2CH2S)2CH2-
CH2}Br2] (7).
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
[Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}] (3)
[Cu(η3-L)(η1-L)][PF6] is similar to that in 3, but in 3 the phenyl
ring lies perpendicular to the plane of the nine-member ring
while in [Cu(η3-L)(η1-L)][PF6] it lies in the same plane to
minimize steric interactions with η1-L.1
Mo-C(11)
Mo-C(10)
Mo-S(4)
P(1)-C(2)
C(2)-C(3)
S(4)-C(5)
C(6)-S(7)
C(8)-C(9)
C(11)-O(11)
1.951(2)
1.983(2)
2.5186(8)
1.843(2)
1.521(3)
1.823(2)
1.836(2)
1.524(3)
1.169(3)
Mo-C(12)
Mo-P(1)
1.973(2)
2.4704(10)
2.5281(9)
1.859(2)
1.845(2)
1.525(3)
1.832(2)
1.157(3)
1.159(3)
Mo-S(7)
P(1)-C(9)
C(3)-S(4)
C(5)-C(6)
S(7)-C(8)
C(10)-O(10)
C(12)-O(12)
With approximate Cs symmetry, three carbonyl bands would
be expected in the infrared spectra of 3-6 corresponding to
vibrations of (A′)2 and A′′ symmetries. This is observed for 3
and 4, but for 5 and 6 only two bands are resolved and the
spectrum has the appearance of a facial tricarbonyl complex
possessing C3V symmetry.21 A simple comparison of the relative
degree of metal electron density can be made using a calculated
weighted average of the carbonyl stretching frequencies. The
calculated values for compounds 3-6 range from 1846 to 1837
cm-1, and comparison with the values for [Mo(9S3)(CO)3]
C(11)-Mo-C(12)
C(12)-Mo-C(10)
C(12)-Mo-P(1)
C(11)-Mo-S(4)
C(10)-Mo-S(4)
C(11)-Mo-S(7)
C(10)-Mo-S(7)
S(4)-Mo-S(7)
86.58(10) C(11)-Mo-C(10)
92.44(9)
98.33(7)
167.48(7)
96.02(6)
79.81(2)
177.12(6)
81.28(2)
91.08(9)
95.90(6)
176.93(7)
89.15(7)
94.35(7)
91.60(7)
82.98(2)
C(11)-Mo-P(1)
C(10)-Mo-P(1)
C(12)-Mo-S(4)
P(1)-Mo-S(4)
C(12)-Mo-S(7)
P(1)-Mo-S(7)
(1827 cm-1 21 and [Mo{c-(HPC3H6)3}(CO)3] (1881 cm-1 20,22
) )
confirms the greater π-acidity of the phosphine functionality.
Oxidative addition of bromine to 3 results in carbonyl
substitution and formation of neutral seven-coordinate [Mo(CO)2-
{c-PhP(CH2CH2S)2CH2CH2}Br2] (7). Similar results have been
observed with tridentate triphosphine macrocycles of molyb-
denum and tungsten.23 No evidence was obtained for the
presumed intermediate [Mo(CO)3{c-PhP(CH2CH2S)2CH2CH2}-
Br]Br. The structure of 7 was established by a single-crystal
X-ray diffraction study. The molecular structure is shown in
Figure 3, and selected bond lengths and angles are given in
Table 5. The coordination geometry around molybdenum
average Mo-C bond distance (1.969 Å) is longer than that
observed in [Mo(9S3)(CO)3] (1.947 Å), and the longest Mo-C
bond is trans to the phosphorus center, reflecting the greater
π-acceptor ability of phosphines compared with thioether
ligands. The Mo-S bonds are similar in 3 (2.523 Å) and
[Mo(9S3)(CO)3] (2.520 Å) but longer than the Mo-thiolate
bonds in 2 (average 2.350 Å). The Mo-P bond in 3 [2.4704(10)
Å] is similar to those in 2 [average 2.4719(10) Å] and [Mo{c-
(HPC3H6)3}(CO)3] [average 2.476(1) Å].20 In general, the
substitution of a phenylphosphine fragment for a thioether results
in minimal geometric change. The conformation of η3-L in
(21) Grant, G. J.; Carpenter, J. P.; Setzer, W. N.; VanDerveer, D. G. Inorg.
Chem. 1989, 28, 4128.
(20) (a) Diel, B. N.; Brandt, P. F.; Haltiwanger, R. C.; Norman, A. D. J.
Am. Chem. Soc. 1982, 104, 4700. (b) Diel, B. N.; Brandt, P. F.;
Haltiwanger, R. C.; Hackney, M. L. J.; Norman, A. D. Inorg. Chem.
1989, 28, 2811.
(22) Coles, S. J.; Edwards, P. G.; Fleming, J. S.; Hursthouse, M. B. J.
Chem. Soc., Dalton Trans. 1995, 1139.
(23) Coles, S. J.; Edwards, P. G.; Fleming, J. S.; Hursthouse, M. B. J.
Chem. Soc., Dalton Trans. 1995, 4091.

1582 Inorganic Chemistry, Vol. 36, No. 8, 1997
Blower et al.
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
[Mo(CO)2{c-PhP(CH2CH2S)2CH2CH2}Br2] (7)
Mo-C(11)
Mo-P(1)
1.949(9)
2.439(2)
2.616(2)
2.6585(13)
1.836(8)
1.540(12)
1.826(8)
1.831(8)
1.494(11)
1.183(11)
Mo-C(12)
Mo-S(4)
1.941(10)
2.516(2)
2.6411(13)
1.813(9)
1.830(8)
1.817(9)
1.516(11)
1.835(8)
1.142(10)
Mo-S(7)
Mo-Br(2)
P(1)-C(21)
P(1)-C(9)
C(3)-S(4)
C(5)-C(6)
S(7)-C(8)
C(11)-O(11)
Mo-Br(1)
P(1)-C(2)
C(2)-C(3)
S(4)-C(5)
C(6)-S(7)
C(8)-C(9)
C(12)-O(12)
C(11)-Mo-C(12)
C(12)-Mo-P(1)
C(12)-Mo-S(4)
C(11)-Mo-S(7)
P(1)-Mo-S(7)
C(12)-Mo-Br(2)
P(1)-Mo-Br(2)
S(7)-Mo-Br(2)
C(11)-Mo-Br(1)
S(4)-Mo-Br(1)
Br(2)-Mo-Br(1)
67.3(5)
77.4(3)
118.2(3)
145.7(4)
80.57(7)
76.7(3)
94.03(6)
80.72(6)
79.9(3)
95.32(6)
84.51(4)
C(11)-Mo-P(1)
C(11)-Mo-S(4)
P(1)-Mo-S(4)
C(12)-Mo-S(7)
S(4)-Mo-S(7)
C(11)-Mo-Br(2)
S(4)-Mo-Br(2)
C(12)-Mo-Br(1)
P(1)-Mo-Br(1)
S(7)-Mo-Br(1)
118.3(3)
75.7(3)
79.14(8)
147.0(3)
80.82(7)
112.6(3)
116.14(6)
123.0(3)
158.20(6)
77.73(6)
Figure 4. Molecular structure of c-PhPS(SCH2CH2S)2(CH2)2 (8).
Table 6. Selected Bond Lengths (Å) and Angles (deg) for
c-PhSP(CH2CH2S)2CH2CH2 (8)
S(1)-C(12)
S(2)-C(14)
S(3)-P
1.815(9)
1.805(9)
1.963(3)
1.831(7)
1.51(1)
S(1)-C(15)
S(2)-C(16)
P-C(1)
1.801(9)
1.792(9)
1.827(7)
1.828(9)
1.53(1)
appears as a capped octahedron. The octahedron is defined by
the sulfur, phosphorus, and bromine atoms and one carbonyl
carbon [C(12)], the cap being the other carbonyl carbon atom
[C(11)] on the triangular face defined by S(4), Br(1), and C(12).
Carbonyl ligands have been found to cap in the related structures
of [Mo(CO)3{c-(PriPC3H6)3}Br]+ 23 and [W(CO)2{MeS(CH2)2S-
(CH2)2SMe}I2].24 L still occupies facial coordination sites and
the average bite angle (80.1°) is similar to that of 3, but the
phenyl ring has rotated in a manner similar to that observed for
[Cu(η3-L)(η1-L)][PF6], revealing greater steric congestion at the
metal center.1 The Mo-P bond distance [2.439(2) Å] has
decreased relative to that in 3 [2.4704(10) Å] despite the increase
in coordination number, possibly reflecting the high formal
oxidation state of molybdenum in 7. The distance for Mo-
S(4) [2.516(2) Å] where the sulfur is trans to a bromide ligand
is similar to the Mo-S distances found in 3, but the distance
for Mo-S(7) [2.616(2) Å] where the sulfur is trans to a carbonyl
ligand is significantly longer.
It is difficult to displace L from 3, and we previously reported
that treatment of 3 with [PhP(CH2CH2S)2]2- or ethanedithiolate
results merely in recovery of unreacted 3.1 This contrasts with
[Mo(CO)3(9S3)], from which 9S3 is readily displaced with the
parent dithiolate [S(CH2CH2S)2]2-. Thus the incorporation of
the phosphine donor increases the kinetic inertness of 3 relative
to [Mo(CO)3(9S3)]. However, reaction of 3 with sulfur in
refluxing toluene results in removal of the Mo(CO)3 fragment
and isolation of compound 8. The structure of 8 was established
by a single-crystal X-ray diffraction study. The molecular
structure is shown in Figure 4, and selected bond lengths and
angles are given in Table 6. The molecule contains a nine-
membered ring with three dimethylene groups alternating among
P-C(11)
P-C(13)
C(11)-C(12)
C(15)-C(16)
C(13)-C(14)
1.53(1)
C(12)-S(1)-C(15)
S(3)-P-C(1)
104.9(4)
113.3(3)
110.4(3)
104.8(5)
122.5(7)
119.2(9)
117.2(6)
119.4(6)
119.0(7)
C(14)-S(2)-C(16)
S(3)-P-C(11)
C(1)-P-C(11)
C(11)-P-C(13)
P-C(1)-C(6)
P-C(11)-C(12)
P-C(13)-C(14)
S(1)-C(15)-C(16)
105.7(4)
111.6(3)
105.3(4)
111.1(4)
118.3(6)
115.0(5)
117.1(6)
116.8(6)
S(3)-P-C(13)
C(1)-P-C(13)
P-C(1)-C(2)
C(2)-C(1)-C(6)
S(1)-C(12)-C(11)
S(2)-C(14)-C(13)
S(2)-C(16)-C(15)
S(1), S(2), and P. The P-S(3) distance [1.963(3) Å] indicates
double-bond order, while all other bond lengths and angles are
normal for single bonds. The ring adopts a conformation with
approximate 2-fold symmetry about a line from P to the
midpoint of C(15)-C(16). The geometry is similar to that
observed for η1-L in [Cu(η3-L)(η1-L)][PF6].1
In conclusion, the structural results presented in this paper
confirm the ability of L to coordinate facially in a manner similar
to the coordination of 9S3. The reactivity studies show that
the phosphine-containing complexes are more resistant to
dissociation than their 9S3 analogs. These properties suggest
applications in the design of kinetically inert complexes
containing soft metal centers.
Acknowledgment. We thank the EPSRC and CRC for
studentships (S.N.S. and R.J.S.) and the EPSRC for access to
the mass spectrometry service.
Supporting Information Available: X-ray crystallographic files,
in CIF format, for 2, 3, 7, and 8 are available on the Internet only.
Access information is given on any current masthead page.
(24) Baker, P. K.; Harris, S. D.; Durrant, M. C.; Hughes, D. L.; Richards,
R. L. J. Chem. Soc., Dalton Trans. 1994, 1401.
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