Synthesis of neutral rhenium(V) complexes with fluorinated benzenethiols: The crystal and molecular structure of [ReO(C6H4S-2-F)3(PPh3)]

Article abstract of DOI:10.1016/S0020-1693(00)00378-9

The complexes [ReO(SR_f)₃(PPh₃)] and [ReN(SR_f)₂(PPh₃)₂] [R_f = C₆F₅ (1) and (6), C₆F₄-4-H (2) and (7), C₆H₄

Full text of DOI:10.1016/S0020-1693(00)00378-9

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 314 (2001) 37–41
Synthesis of neutral rhenium(V) complexes with fluorinated
benzenethiols: the crystal and molecular structure of
[ReO(C6H4S-2-F)3(PPh3)]
David Morales-Morales a, Yifan Zheng a, Jonathan R. Dilworth a,*1, Roc´ıo Redo´n b,
Hugo Torrens b,*2
a Inorganic Chemistry Laboratory, Uni6ersity of Oxford, South Parks Road, Oxford OX1 3QR, UK
b DEPg, Facultad de Qu´ımica, UNAM, Cd. Uni6ersitaria, 04510 Mexico City, Mexico
Received 9 August 2000; accepted 6 November 2000
Abstract
The complexes [ReO(SRf)3(PPh3)] and [ReN(SRf)2(PPh3)2] [Rf=C6F5 (1) and (6), C6F4-4-H (2) and (7), C6H4-2-F (3) and (8),
C6H4-3-F (4) and (9) and C6H4-4-F (5) and (10)] were synthesized in good yields by reacting [ReOCl3(PPh3)2] or [ReNCl2(PPh3)2]
and the lead salt of the corresponding fluorobenzenethiol [Pb(SRf)2]. In contrast, when the free thiol HSC6F5 was employed in the
presence of NEt3 as base, the ionic species [ReO(SC6F5)4][NEt3·HCl] (11) was isolated. The X-ray crystal structure of 3 was
determined. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Rhenium complexes; Fluorinated thiols; Oxo complexes; Thiolate complexes; Nitrido complexes
substitution or by increasing the number of fluorine
atoms in the aromatic ring [6]. In recent years the
synthesis and reactivity of rhenium complexes with
sterically hindered thiols have been studied, and al-
though the complexes are potentially capable of bind-
ing small molecules, this ability is a sensitive function of
the nature of the substituents of the thiolate ligand [1].
The usual product of reaction of Re(V) precursors with
thiolate anions is [ReO(SR)4]− and neutral rhenium
thiolate complexes, such as [ReO(SR)3(PR3)], are very
rare, and represented by the single reported example
[ReO(DMT)3(PR3)] (DMT=2,6-dimethylbenzenethio-
late). This complex was obtained by reacting
trimethylsilyl-2,6-dimethylbenzenethiolate (Me3SiDMT)
with [ReOCl3(PPh3)2] or [ReH7(PPh3)2] with RSSR
(SR=DMT) [7]. Rhenium nitrido complexes with aro-
matic thiolate ligands are also relatively uncommon;
however, the Re(VI) complex [ReN(TIPT)4]− was ob-
tained when the sodium salt of TIPTH (2,4,6-triiso-
propylbenzenethiol) was reacted with [ReNCl2(PPh3)2]
[8]. In an effort to effect an efficient synthesis of
complexes with the formulation [ReO(SR)3(PR3)] and
[ReN(SR)2(PR3)2] we have attempted the metathetical
1. Introduction
The chemistry of aromatic sterically hindered thiols
has been studied extensively in recent years owing to
the importance that some of its complexes may play as
models for active sites in metalloproteins [1]. This is
particularly true in the case of nitrogenase, thought to
be the key catalyst in the reduction of dinitrogen to
ammonia [2]. Among the sterically hindered thiolate
ligands, fluorinated benzenethiols have occupied an im-
portant place, owing to their ability to stabilize unusual
geometries, oxidation states and intra- or inter-molecu-
lar interactions [3]. Some complexes have also been
used as highly active catalysts in hydroformylation and
polymerization reactions [4] and identified as active
intermediates in desulfurization processes [5]. The suc-
cess of the fluorinated thiols over other sterically hin-
dered thiols lies in the facility with which steric and
electronic properties can be tuned by changing fluorine
1 *Corresponding author. Tel.: +44-1865-272 639; fax: +44-1865-
272 690; e-mail: jon.dilworth@chem.ox.ac.uk
2 *Corresponding author.
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(00)00378-9

38
D. Morales-Morales et al. / Inorganica Chimica Acta 314 (2001) 37–41
reactions of fluorobenzenethiolate lead salts with
[ReOCl3(PPh3)2] or [ReNCl2(PPh3)2].
standard reflections were measured every 200 reflections
to check the crystal orientation. The data were cor-
rected for Lorentz and polarization factors and an
absorption correction was applied using „-scans of nine
reflections. The structure was solved via direct methods
[13] and refined by Fo2 by full-matrix least squares [14].
All non-hydrogen atoms were anisotropic. The hydro-
gen atoms were included in idealized positions with Uiso
free to refine. The weighting scheme gave satisfactory
agreement analyses. Final R indices [5272I\2|(I)]
2. Experimental
2.1. Materials and methods
Unless stated otherwise, all reactions were carried out
under an atmosphere of dinitrogen using conventional
Schlenk glassware, and solvents were dried using estab-
lished procedures and distilled under dinitrogen imme-
diately prior to use. IR spectra were recorded on a
Perkin–Elmer Paragon FT-IR spectrometer as Nujol
R1=0.0271 (on F), wR2=0.0707. The largest differ-
−3
ence peak and hole were 1.485 e−
and −0.397 e−
,
A
−3
,
A
respectively; the highest peak in the final
difference Fourier map was in the vicinity of the metal
atoms; the final map had no significant features. The
maximum shift/e.s.d. value was 0.002. Sources of scat-
tering factors were as in Ref. [14]. The details of the
structure determination are given in Table 1; selected
bond lengths and angles are in Table 2. The numbering
of the atoms is shown in Fig. 1 (ZORTEP) [15].
1
mulls and H (400.03 MHz), 19F (376.41 MHz) and 31P
NMR (161.94 MHz) spectra on a JEOL EX270 spec-
trometer in CDCl3 solutions. Elemental analyses were
determined on a Perkin–Elmer 240 at the University of
Essex. The fluorinated benzenethiols were obtained
from Aldrich Chemical Co. and used without further
purification. The starting materials [Pb(SRf)2] [Rf=
C6F5, C6F4-4-H, C6H4-2-F, C6H4-3-F and C6H4-4-F]
[9], [ReOCl3(PPh3)2] [10] and [ReNCl2(PPh3)2] [11] were
prepared according to published procedures.
3. Results and discussion
3.1. Synthesis of the complexes [ReO(SRf)3(PPh3)] and
[ReN(SRf)2(PPh3)2]
2.2. Synthesis of
[ReO(SRf)3(PPh3)]/[ReN(SRf)2(PPh3)2]
The
reaction
of
the
starting
materials
[ReOCl3(PPh3)2] or [ReNCl2(PPh3)2] with the lead salts
of the fluorobenzenethiols in CH2Cl2 affords the thio-
late complexes [ReO(SRf)3(PPh3)2] and [ReN(SRf)2-
(PPh3)2] in good yields (Schemes 1 and 2). The reac-
tions proceed cleanly to yield only the desired species,
except in the cases of Rf=C6H4-2-F (3) and (8), C6H4-
3-F (4) and (9), C6H4-4-F (5) and (10) where further
purification was necessary. All complexes are stable in
the solid state, but tend to decompose in solution under
aerobic conditions; the products of decomposition were
not identified. The results obtained contrast with those
of other reactions carried out using free thiophenol or
other sterically hindered thiols in the presence of base
which give exclusively ionic species with the formula-
tion [ReX(SR)4]−, X=O, N [16,17]. The use of the
essentially covalent lead salts avoids the use of thiolate
anion and permits the stoichiometric, non-reductive
introduction of thiolate ligands. The differences in
products formed is probably a kinetic effect originating
from the necessity to form a four-center transition state
prior to elimination of lead chloride. This is almost
certainly slower than simple nucleophilic attack of thio-
late anion. The proposed formulations were confirmed
by elemental analyses, IR spectroscopy, mass spec-
trometry and multinuclear NMR data (Table 1). The
infrared spectroscopic data obtained show intense
bands for all the oxo complexes in the range 918 to
To a dichloromethane solution of [ReOCl3(PPh3)2]
(50 mg, 0.060 mmol) or [ReNCl2(PPh3)2] (50 mg,
0.063 mmol) equivalent amounts of the lead salts were
added. The resulting suspensions were stirred for 24 h
at room temperature. After this time the resulting solu-
tions were filtered through a short plug of Celite and
the solvent removed under vacuum. For the reactions
with Pb(SRf)2 Rf=C6H4-2-F, C6H4-3-F, C6H4-4-F, fur-
ther purification was required and column chromatog-
raphy was performed using silica-gel as stationary
phase and CH2Cl2 as eluent first and then pentane.
Dark-green fractions were collected and the solvent
evaporated under vacuum. A second fraction (brown–
reddish) was separated; however, the amounts obtained
were too small to carry out any further analysis.
2.3. Single crystal X-ray structure determination of
[ReO(C6H4S-2-F)3(PPh3)] (3)
Intensity data were collected on an Enraf–Nonius
CAD4 diffractometer [12] with monochromated Mo
,
Ka radiation (u= 0.710 73 A). Cell constants were
obtained from least-squares refinement of the setting
angles of 25 centered reflections in the range 1.52BqB
25°. The data were collected in the ꢀ–2q scan mode
and three standard reflections were measured every 2 h
of exposure. No loss of intensity was observed. Three

D. Morales-Morales et al. / Inorganica Chimica Acta 314 (2001) 37–41
39
940 cm−1, which are typical for the ReꢀO stretching
Table 2
,
Selected bond lengths (A) and angles (°) for [ReO(SC6H4-2-F)3(PPh3)]
(3)
1
vibration. The H NMR spectrum of the complexes is
not very revealing, and only the signals corresponding
to the aromatic protons in the PPh3 and the thiolate
ligands are observed. The 31P NMR exhibits a singlet in
all cases to confirm the proposed structures, with a
single phosphine ligand for the oxo complexes or, in the
case of the nitrido species, two equivalent phosphorus
,
Bond lengths (A)
Bond angles (°)
ReꢁO
1.6893(3)
OꢁReꢁS(3)
OꢁReꢁS(2)
S(3)ꢁReꢁS(2)
S(1)ꢁReꢁP
OꢁReꢁS(1)
S(3)ꢁReꢁS(1)
S(2)ꢁReꢁS(1)
OꢁReꢁP
114.92(13)
118.54(12)
123.88(5)
162.68(4)
104.91(12)
86.94(4)
94.85(4)
92.02(12)
86.53(4)
ReꢁS(3)
ReꢁS(2)
ReꢁS(1)
ReꢁP
2.2866(12)
2.3071(11)
2.3157(11)
2.5093(11)
Table 1
S(3)ꢁReꢁP
S(2)ꢁReꢁP
Crystal data and structure refinement [ReO(SC6H4-2-F)3(PPh3)] (3)
79.87(4)
Empirical formula
Formula weight
Temperature (K)
Diffractometer
C36H27F3OPReS3
845.93
293(2)
Enraf–Nonius CAD4
0.710 73
ꢀ–2q
1–7 (in ꢀ)
triclinic
,
Wavelength (A)
Collection method
Scan rate (min−1
Crystal system
Space group
)
(
P1
Unit cell dimensions
,
a (A)
10.7545(10)
12.174(2)
14.766(2)
71.405(10)
71.142(10)
81.992(10)
1732.6(4)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
No. of reflections (lattice)
25
q range (lattice)
15–16
1.621
Dcalc (g cm−3
)
Absorption coefficient
(mm−1
F(000)
)
832
Crystal size (mm3)
q range for data collection
(°)
0.55×0.3×0.25
Fig. 1. A ZORTEP representation of the structure [ReO(SC6H4-2-
F)3(PPh3)] (3) at 50% probability, showing the atom-labeling scheme.
1.52 to 25.02
−125h50, −145k514,
−175l516
Index ranges
Reflections collected
Independent reflections
Absorption correction
Max. and min.
6122
6104 (Rint=0.0104)
„-scan
transmission
1, 89.9
Standard decay correction
Program used
0
SHELXL-93 [14]
Solution method (direct)
Weighting scheme
SHELXS-86 (Sheldrick, 1991)
calc w=1/[|2(Fo2)+(0.046 69P)
2+0.6071P] where P=(Fo2+2Fc2)/3
Full-matrix least-squares on F2
6104/0/406
Refinement method
Scheme 1. Preparation of oxo-complexes of rhenium(V) with
fluorobenzenethiolates.
Data/restraints/parameters
Goodness-of-fit on F2
R indices [5272I\2|(I)]
R indices (all data)
1.103a
R1=0.0271, wR2=0.0707b
R1=0.0379, wR2=0.0743b
Largest diff. peak and hole
groups probably in a trans arrangement. The 19F NMR
shows the signals expected for the fluorine atoms
present in the corresponding fluorobenzene thiolates
[18]. Elemental analysis and mass spectrometry experi-
ments also confirm the proposed formulations for the
complexes as monomeric species.
−3
(e−
A
)
1.485 and −0.397
0.002
,
Max. shift/e.s.d.
a S=[w(Fo)2−(Fc)2)2/(n−p)]1/2 where n is the number of reflec-
tions and p is the total number of parameters.
b R1=ꢀFo−Fcꢀ/ꢀFoꢀ, wR2=[w((Fo)2−(Fc)2)2/w(Fo)2]1/2
.

40
D. Morales-Morales et al. / Inorganica Chimica Acta 314 (2001) 37–41
with fluorinated benzenethiols has been synthesized.
The structure of the oxo complexes was confirmed by
single crystal X-ray analysis of [ReO(SC6H4-2-
F)3(PPh3)] to be tbp with the oxo ligand occupying one
equatorial site.
Scheme 2. Preparation of nitrido-complexes of rhenium(V) with
fluorobenzenethiolates.
5. Supplementary material
3.2. The X-ray crystal structure of
[ReO(SC6H4-2-F)3(PPh3)] (3)
A complete listing of the crystallographic methods
and details has been deposited with the Cambridge
Crystallographic Data Centre, CCDC no. 147162.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44-1223-336 033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
The details of the structure determination of complex
3 are given in Table 1. The ZORTEP representation of
the structure is given in Fig. 1, together with the
atom-labeling scheme. Selected bond lengths and angles
are given in Table 2. The overall geometry about the Re
atom is best described as being distorted trigonal
bipyramidal (tbp), with the equatorial plane comprising
the oxo atom and two thiolate ligands and the third
thiolate and triphenylphosphine occupying the apical
sites. The equatorial ligands and PꢁC bonds of PPh3 are
staggered with torsion angles of average 157.6°
[S(3)ꢁReꢁPꢁC(11)=163.1, S(2)ꢁReꢁPꢁC(21)=154.4,
OꢁReꢁPꢁC(31)=155.3] to minimize steric interactions.
The aryl groups of the equatorial thiolates are disposed
to the side of the equatorial plane away from the bulky
triphenylphosphine ligand. The ReꢀO distance is very
Acknowledgements
D.M.M. and R.R would like to thank the DGEP–
UNAM for Ph.D. scholarships. We are also indebted to
Hermann Starck, GmbH for the generous gift of rhe-
nium metal.
similar
to
that
of
the
analogous
species
,
[ReO(DMT)3(PPh3)] [1.694(6) A] [7] and the anionic
i
,
complex [ReO(DIPT)4][Ph3PSC6H3Pr2] [1.70(2) A] [17].
References
,
The ReꢁP distance [2.5093(11) A] is similar to those
observed in [ReO(DMT)3(PPh3)] [2.521(2) A] and
[1] J.R. Dilworth, J. Hu, Adv. Inorg. Chem. 40 (1994) 411.
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[Re(DMT)3(PPh3)(PHPh2)] [2.455(4) A] [7]. The ReꢁS
,
,
distances [ReꢁS(3) 2.2866(12) A, ReꢁS(2) 2.3071(11) A,
,
ReꢁS(1) 2.3157(11) A] are very similar and also com-
parable to those observed in [ReO(DMT)3(PPh3)]
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,
,
[ReꢁS(3) 2.301(2) A, ReꢁS(2) 2.293(2) A, ReꢁS(1)
,
2.319(2) A] [7]. Based on these results, and those ob-
tained from the spectroscopic techniques, we can con-
clude that the other oxo complexes should exhibit the
same tbp structure in the solid state. In the absence of
an X-ray crystal structure for the nitrido compounds,
and according to the analytical and spectroscopic data,
it is very likely that these series of complexes have a
geometry similar to that observed for the [ReO(SR)4]−
species [16,17]. These have a square pyramidal geome-
try, and in the case of the complexes described here the
phosphines will presumably be located at the base of
the pyramid in a trans arrangement. The two thiolates
complete the basal plane, and the nitride ligand is
located in the apical position.
[12] CAD4 Operations Manual, Enraf–Nonius, Delft, 1977.
[13] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[14] G.M. Sheldrick, SHELXL-93, Program for Crystal Structure
Refinement, University of Go¨ttingen, 1993.
4. Conclusions
A series of neutral oxo and nitrido Re(V) complexes

D. Morales-Morales et al. / Inorganica Chimica Acta 314 (2001) 37–41
41
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