Tris-mercaptophenylphosphine complexes of rhenium: Synthesis, reactivity and structural characterization

Article abstract of DOI:10.1016/j.ica.2004.09.065

The reactions of various rhenium(III) precursers with the tetradentate umbrella ligand tris-(ortho-mercaptophenyl)phosphine (PS₃ for the tri-anionic form) followed by various neutral donor ligands is the focus of this work. The addition of a solution of P(SLi)₃ in THF to [ReBr ₃(THT)₃] in THF followed by the addition of excess isonitrile gives the octahedral complex [PS₃Re(CNiPr)₂]. This reaction also allows isolation of [PS₃Re(CNiPr)] which is separated from the bis-isonitrile complex via column chromatography. Both of these complexes were structurally characterized with the five-coordinate species displaying trigonal bipyramidal geometry and the six-coordinate species displaying a distorted octahedral geometry. The decomposition product [(S ₂PS-SPS₂)Re] is also isolated from the chromatographic separation of the two isonitrile complexes. This neutral octahedral complex displays coordination through two phosphine and four thiolate moieties, with a non-coordinated disulfide bridge that links the remaining sulfurs. The addition of a solution of H₃PS₃ and iPr₂NEt in THF to [ReBr₃(THT)₃] followed by the addition of dimethylphenylphosphine yields [PS₃Re(PMe₂Ph) ₂]. This complex, similar to the bis-isonitrile species, displays a distorted octahedral geometry. These complexes and others in the series have been fully characterized with NMR spectroscopy, infrared and mass spectrometry and elemental analyses.

Full text of DOI:10.1016/j.ica.2004.09.065

Inorganica Chimica Acta 358 (2005) 3559–3571
www.elsevier.com/locate/ica
Tris-mercaptophenylphosphine complexes of rhenium:
Synthesis, reactivity and structural characterization
a
a,b,
a
a
b
A. Shellenbarger-Jones , T. Nicholson
*, W.M. Davis , A. Davison , A.G. Jones
a
Department of Chemistry, Massachusetts Institute of Technology, 21 Dwight Street (#1), Boston, MA 02118, United States
b
Department of Radiology, Harvard Medical School, United States
Received 20 August 2004; accepted 17 September 2004
Available online 15 August 2005
Abstract
The reactions of various rhenium(III) precursers with the tetradentate umbrella ligand tris-(ortho-mercaptophenyl)phosphine
(PS3 for the tri-anionic form) followed by various neutral donor ligands is the focus of this work.
The addition of a solution of P(SLi)3 in THF to [ReBr3(THT)3] in THF followed by the addition of excess isonitrile gives the
octahedral complex [PS3Re(CNiPr)2]. This reaction also allows isolation of [PS3Re(CNiPr)] which is separated from the bis-isoni-
trile complex via column chromatography. Both of these complexes were structurally characterized with the five-coordinate species
displaying trigonal bipyramidal geometry and the six-coordinate species displaying a distorted octahedral geometry. The decompo-
sition product [(S2PS-SPS2)Re] is also isolated from the chromatographic separation of the two isonitrile complexes. This neutral
octahedral complex displays coordination through two phosphine and four thiolate moieties, with a non-coordinated disulfide
bridge that links the remaining sulfurs.
The addition of a solution of H3PS3 and iPr2NEt in THF to [ReBr3(THT)3] followed by the addition of dimethylphenylphos-
phine yields [PS3Re(PMe2Ph)2]. This complex, similar to the bis-isonitrile species, displays a distorted octahedral geometry.
These complexes and others in the series have been fully characterized with NMR spectroscopy, infrared and mass spectrometry
and elemental analyses.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Rhenium; Thiolate; Phosphine; Disulfide
1. Introduction
dimethylphenylthiolate forms [Re(SC6H3Me2-2,6)3-
(PPh3)], which can be considered to be a 12-electron,
four-coordinate species, but X-ray crystallographic
analysis reveals an agostic interaction with one of the
methyl groups on the thiolate to further stabilize the
Phosphines and thiolates are excellent stabilizing li-
gands for rhenium and technetium. In radiopharmaceu-
tical research, many P- or S-based ligand donor sets
have been developed. A recent review discusses the cur-
rent state of ligands which combine the two functional-
ities [1–3]. Bulky thiolates in particular stabilize electron
deficient rhenium and technetium, allowing for four-
and five-coordinate M(III) species that are formally
12- or 14-electron systems. The somewhat bulky 2,6-
˚
compound (Reꢀ ꢀ ꢀH = 2.07 A) [4]. In particular, the thi-
olates tend to form either trigonal bipyramidal com-
plexes of M(III) with the three sulfurs in the
equatorial plane and neutral donors in the axial posi-
tions or square pyramidal complexes with four sulfurs
in the pyramid base [4–7]. Common neutral donor li-
gands are phosphines, CO, nitrosyls, and dinitrogen.
Research on bidentate ligands has led to octahedral
complexes. Deutsch et al. synthesized a series of
*
Corresponding author. Fax: +1 617 258 6989.
E-mail address: tnichlsn@excite.com (T. Nicholson).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.09.065

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A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
[M(SR)2(DIP)2]+ compounds, where M is technetium or
rhenium, SR is a monodentate thiolate, and DIP is a
bidentate diphosphine [8,9]. These complexes are dis-
torted octahedra due to the small bite angle of the
diphosphines and are paramagnetic d4 compounds.
Tetradentate ligands have been investigated with
Group 7 metals, particularly N2S2 or NS3 linear ligands.
The resultant complexes are generally square pyramidal
M(V)oxo complexes. ‘‘Umbrella’’-style tetradentate li-
gands provide a different geometry and complexes with
these ligands tend to have a wider array of oxidation
states. The rhenium(III) trigonal bipyramidal motif is
seen with several tetradentate tri-anionic systems, con-
sisting of these ‘‘umbrella’’-style ligands [10]. These rhe-
nium(III) compounds bind various small ligands such as
N2 and ethylene in the open axial position.
Tetradentate nitrogen–sulfur systems also have been
studied. Spies and Hahn utilized the tripodal NS3 ligand
2,20,200-nitrilotris(ethanethiol) on rhenium and techne-
tium [11]. The formation of trigonal bipyramidal
M(III) complexes was observed with the tripodal NS3 li-
gand. With an axial phosphine ligand, the complex was
air-sensitive, but with other axial ligands, the compounds
were not. These compounds exhibited considerable back-
bonding to the p-acceptor ligands, resulting in lower ob-
served stretching frequencies for the C–N bonds in the
isonitriles (1850–1975 cmꢁ1) and for the C–O bond in
the carbonyl (1876 cmꢁ1). For each five-coordinate com-
plex, no further substitution of phosphines or isonitriles
to form the six-coordinate octahedral complexes was
observed.
exhibits an eight-coordinate structure unusual for rhe-
nium, with no further reduction of the rhenium center
[13].
2. Discussion
The basic reaction synthon we used for the PS3 chem-
istry was the in situ PS3Re(THT)x (THT = tetrahydro-
thiophene) generated from lithiated PS3 and
ReBr3(THT)3 in hot THF. The THT moieties on this
Re(III) species are readily substituted with stronger do-
nor ligands. The addition of Li3PS3 to an orange–yellow
solution of ReBr3(THT)3 in THF results in a gray–green
color. This gray–green complex is uncharacterized, and
on heating turns a deep red-burgundy color. The
mono-THT complex PS3Re(THT) [1] was isolated from
this mixture, and by TLC comparison was the major
component of the mixture. This complex undergoes sub-
stitution reactions with r and p donating ligands to
form trigonal bipyramidal and octahedral complexes.
Addition of an excess of coordinating ligands, such as
phosphines or isonitriles, results in an immediate color
change to a brilliant purple. The primary component,
which was purple, was identified as the bis-substituted
octahedral PS3ReL2 complex, where L is a neutral coor-
dinating ligand.
The addition of isopropylisonitrile to [1] leads to
the formation of a deep purple product and a brown
product (see Scheme 1.3). The predominant product
is the purple bis-isonitrile octahedral complex
PS3Re(CNiPr)2 [2]. Even with the addition of just
one equivalent of isonitrile, the bis-isonitrile complex
is seen by TLC. The octahedral PS3 rhenium com-
plexes have a distinctive bright purple color, in con-
trast to the trigonal bipyramidal PS3 compounds
which are brown. The mono-substituted product
PS3Re(CNiPr) [1.3] can be separated from [2] by col-
umn chromatography. Even when a considerable ex-
cess of isonitrile is used, [3] can still be isolated by
chromatography; presumably, the loss of isonitrile is
occurring to a small degree when the bis-substituted
complex is on the column.
Multidentate phosphorus and sulfur umbrella systems
have been less well studied. The ligand tris-(ortho-
mercaptophenyl)phosphine (PS3 for the tri-anionic
thiolato-form) is the focus of this work. PS3Tc(CNR)x
[R = Me, iPr; x = 1,2], can be prepared directly from
ammonium pertechnetate and the neutral trithiol
H3PS3 in the presence of the isonitrile and sodium dithi-
onite as reducing agent [12]. The corresponding reaction
of H3PS3 with ammonium pertechnetate in the presence
of HCl results in seven-coordinate Re(PS3)(HPS3). Fur-
ther treatment with a reducing agent (triethylamine) re-
sults in the formation of (HNEt3)[Re(PS3)2], which
THT
P
P
Re
C
Br
Br
THT
THT
Re
Br
S
S
S
S
Re
C
S
+
S
CNiPr
C
N
+
N
N
Li3PS3
Scheme 1.3. Synthesis of [1.2] and [1.3], isonitrile complexes (phenyl rings omitted for clarity).

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3561
Table 1
In the proton NMR spectrum of [2], a 2:1 relative
Crystal data and structure refinement for PS3Re(CNiPr)2 [1.2]
intensity is noted for the aryl rings of the PS3 ligand,
and the alkyl resonances for the isonitrile ligands are
also observed with different chemical shifts. This indi-
cates the asymmetry of the molecule and suggests the
octahedral structure with the isonitrile ligands in a cis
arrangement. In the 31P NMR spectrum, a singlet at
110 ppm is observed, significantly downfield from free
H3PS3, which exhibits a shift of ꢁ26.4 ppm [14]. The
presence of an unbroadened NMR spectrum was unex-
pected for a presumably six-coordinate d4 rhenium com-
plex. This will be discussed in greater detail (vide infra).
The stretching frequencies of the coordinated isonitriles
in [2] are at 2154 and 2097 cmꢁ1, both shifted to lower
wavenumbers than free ligand due to p-back-bonding
with the rhenium center.
Empirical formula
Formula weight
Temperature (K)
C26H26N2PReS3
679.84
183(2)
˚
Wavelength (A)
0.71073
Crystal system
Space group
Unit cell dimensions
Orthorhombic
Pna21
˚
a (A)
18.7467(12)
13.2509(9)
˚
b (A)
˚
c (A)
10.3297(7)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90
2566.0(3)
3
˚
Volume (A )
Z
4
Density (calculated) (g cmꢁ3
)
1.760
5.060
1336
Absorption coefficient (mmꢁ1
F(000)
)
A single crystal X-ray diffraction study was under-
taken; this shows a distorted octahedral geometry for
the rhenium center. An ORTEP diagram is shown in
Fig. 1. Crystallographic information and selected bond
lengths and angles are available in Tables 1 and 2. Com-
plete data can be found in Appendix A. The locations of
the two mutually trans sulfur atoms S(1) and S(3) are
distorted from an idealized octahedron towards the
equatorial isonitrile ligand. The C(19)–Re(1)–S(1) and
C(19)–Re(1)–S(3) angles are both less than 90ꢁ, with
the S(1)–Re(1)–S(3) angle only 147ꢁ. The remaining an-
gles are closer to those of a standard octahedron; the li-
gand–metal–ligand angles orthogonal to the equatorial
plane are all close to 90ꢁ. The distortion is significant en-
ough to change the orbital energies to allow for a dia-
magnetic d4 complex, as observed by 1H NMR
spectroscopy.
Crystal size (mm)
h Range for data collection
Limiting indices
0.20 · 0.21 · 0.23
3.81ꢁ to 23.25ꢁ
ꢁ9 < h < 20, ꢁ14 < k < 12,
ꢁ11 < l < 3
Reflections collected
Independent reflections
Rint
5552
2003
0.0467
None
Absorption correction
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Full-matrix least-squares on F2
2003/1/299
1.143
R1 = 0.0324, wR2 = 0.0848
R1 = 0.0330, wR2 = 0.0853
0.010(14)
0.0004(3)
1.864 and ꢁ1.378
Absolute structure parameter
Extinction coefficient
Largest different peak and
ꢁ3
˚
hole (e A
)
The X-ray structural analysis is in agreement with the
other solution and solid-state data. The Re–S(2) bond
trans to an isonitrile is the shortest of the Re–S bonds,
˚
˚
˚
at 2.307(3) A, versus 2.325(3) A and 2.384(3) A for
Re–S(1) and Re–S(3), respectively. The two isonitriles
themselves have an identical bond length for the C„N
˚
of 1.17(2) A, reasonable for a terminal isonitrile [15].
In the isomorphous PS3Tc(CNiPr)2, the isonitriles dis-
play similar C„N bond lengths of 1.152(8) and
˚
1.150(9) A [12]. The two isonitrile ligands are slightly
bent: for the ligand trans to the P, Re–C–N is
179.0(9)ꢁ and C–N–C is 168.0(11)ꢁ; for the ligand trans
to an S, Re–C–N is 176.5(10)ꢁ and C–N–C is 169.6(12)ꢁ.
The mono-isonitrile complex, PS3Re(CNiPr) [3], was
also isolated. The nuclear magnetic resonance spectrum
for this brown compound is typical for a trigonal bipy-
ramidal molecule. The approximate C3v symmetry al-
lows for identical solution behavior of the aryl rings.
The symmetric aryl rings on the PS3 are visible as four
multiplets of equal intensity between 7.2 and 8.5 ppm
1
in the H NMR spectrum. The septet at 5.03 ppm and
doublet at 1.67 ppm are produced by the coordinated
isonitrile. The 31P resonance at 137.7 ppm is in the range
Fig. 1. ORTEP diagram of PS3Re(CNiPr)2 [1.2] (phenyl rings omitted
for clarity).

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A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
Table 2
˚
Selected bond lengths [A] and angles [ꢁ] for PS3Re(CNiPr)2 [1.2]
˚
Bond lengths (A)
Re(1)–C(23)
Re(1)–C(19)
Re(1)–P(1)
Re(1)–S(2)
Re(1)–S(1)
Re(1)–S(3)
N(1)–C(19)
N(2)–C(23)
2.038(12)
2.093(11)
2.303(2)
2.307(3)
2.325(3)
2.384(3)
1.17(2)
1.17(2)
Bond angles (ꢁ)
C(23)–Re(1)–C(19)
C(23)–Re(1)–P(1)
C(19)–Re(1)–P(1)
C(23)–Re(1)–S(2)
C(19)–Re(1)–S(2)
P(1)–Re(1)–S(2)
C(23)–Re(1)–S(1)
C(19)–Re(1)–S(1)
P(1)–Re(1)–S(1)
S(2)–Re(1)–S(1)
C(23)–Re(1)–S(3)
C(19)–Re(1)–S(3)
P(1)–Re(1)–S(3)
S(2)–Re(1)–S(3)
S(1)–Re(1)–S(3)
C(19)–N(1)–C(20)
C(23)–N(2)–C(24)
N(1)–C(19)–Re(1)
N(2)–C(23)–Re(1)
86.4(4)
173.0(3)
100.0(3)
89.3(3)
175.0(3)
84.45(9)
94.2(3)
76.4(3)
84.64(9)
106.39(10)
101.1(3)
76.4(3)
83.33(9)
102.10(11)
147.73(11)
168.0(11)
169.6(12)
179.0(9)
176.5(10)
Fig. 2. ORTEP of PS3Re(CNiPr) [1.2].
Table 3
Crystal data and structure refinement for PS3Re(CNiPr) [1.3]
Empirical formula
Formula weight
Temperature (K)
C22H19NPReS
610.73
183(2)
˚
Wavelength (A)
0.71073
monoclinic
P2(1)/c
for that observed for other five-coordinate PS3Re com-
pounds [4,16], but is considerably downfield of the free
phosphine.
Crystal system
Space group
Unit cell dimensions
˚
The X-ray structure of [3] is isomorphous with the
technetium analogue, crystallizing in the P21/c space
group [6]. An ORTEP diagram is shown in Fig. 2. Crys-
tallographic information and selected bond lengths and
angles are available in Tables 3 and 4. Complete data
can be found in Appendix A. The isonitrile is again
a (A)
10.3354(6)
13.1611(8)
16.3387(10)
90
91.2730(10)
90
2221.9(2)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
Volume (A )
Z
4
slightly bent, having
174.6(4)ꢁ and a C–N–C angle of 173.5(5)ꢁ; the C„N
bond length of 1.15(1) A is consistent with the corre-
a Re–C–N bond angle of
Density (calculated) (g cmꢁ3
)
1.826
5.831
1184
Absorption coefficient (mmꢁ1
F(000)
Crystal size (mm3)
h Range for data collection
Limiting indices
)
˚
sponding bond in the technetium analogue. The absorp-
tion frequencies for the isonitriles in the IR spectra of
0.22 · 0.22 · 0.25
2.49ꢁ to 23.28ꢁ
ꢁ11 6 h 6 8, ꢁ14 6 k 6 14,
ꢁ16 6 l 6 18
8615
the two compounds differ by 30 cmꢁ1
, however,
[2115 cmꢁ1 for Re versus 2144 cmꢁ1 for Tc, see Table
5]. The isonitriles in the NS3ReCNR complexes synthe-
sized by Spies and Hahn are considerably more bent,
having C–N–C angles in the range of 150–155ꢁ [11].
The strong backbonding to the isonitriles in those com-
pounds is further evidenced by the low wavenumber of
the C„N stretching frequencies, seen between 1840
Reflections collected
Independent reflections (Rint = 0.0381) 3197
Completeness to h = 23.28
Absorption correction
Maximum and minimum transmission 0.0640 and 0.0303
Refinement method
99.6%
empirical
full-matrix least-squares
on F2
3197/0/256
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Extinction coefficient
Largest different peak and hole (e A
and 1975 cmꢁ1
.
1.176
The synthesis of the mono- and bis-isonitrile com-
plexes on a scale over 100 mg allows for the discernment
of an additional product, [4]. This is again purple in
solution, but a much less vibrant color than that of
R1 = 0.0245, wR2 = 0.0636
R1 = 0.0257, wR2 = 0.0641
0.00180(12)
0.763 and ꢁ0.668
ꢁ3
˚
)

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3563
Table 4
crystals were obtained from dichloromethane layered
with pentane. An X-ray structural analysis showed the
formation of a disulfide bond to join two PS3 ligands
and a distorted, octahedral, d3 rhenium center (see
Scheme 1.4). An ORTEP diagram is shown in Fig. 3.
Crystallographic information and selected bond lengths
and angles are available in Tables 6 and 7. Complete
data can be found in Appendix A.
˚
Selected bond lengths [A] and angles [ꢁ] for PS3Re(CNiPr) [1.3]
˚
Bond lengths (A)
Re–C(1)
Re–S(2)
Re–S(1)
Re–S(3)
Re–P
2.054(5)
2.2457(12)
2.2455(12)
2.2516(13)
2.2896(11)
1.151(6)
N–C(1)
A related ligand rearrangement has been observed on
osmium with the PS3 ligand [19]. In that case, two disul-
fide bonds were formed to create a 14-atom macrocycle,
with one S of each disulfide bridge coordinating to the
metal center (see Scheme 1.5). In [4], the disulfide bond
Bond angles (ꢁ)
C(1)–Re–S(2)
C(1)–Re–S(1)
S(2)–Re–S(1)
C(1)–Re–S(3)
S(2)–Re–S(3)
S(1)–Re–S(3)
C(1)–Re–P
94.60(14)
91.54(14)
118.77(4)
96.62(13)
119.01(5)
120.58(5)
176.95(13)
85.77(4)
˚
is not within the coordination sphere (Re–S(3) = 4.3 A,
˚
˚
Re–S(6) = 5.1 A, versus. Re–S of 2.3–2.4 A for the non-
bridged sulfurs). The P(1)–Re–P(2) angle is quite wide at
S(2)–Re–P
S(1)–Re–P
S(3)–Re–P
85.64(4)
85.83(4)
˚
108.66(5) A, to accommodate the disulfide bridge. This
C(1)–N–C(2)
N–C(1)–Re
173.5(5)
174.6(4)
Table 5
Comparison of IR stretching frequencies (KBr, in cmꢁ1) for the C„N
bonds in spectra of PS3M isonitriles
Coordinating
ligand (L)
PS3ReL
PS3ReL2
PS3TcL
PS3TcL2
CNMe
CNiPr
n.a.
2115
n.a.
2154, 2097
2163 [12]
2144 [12]
2173 [12]
2155,2127,
2115 [12]
n.a.
CN(2,6-Me2Ph)
2058 [16]
2123, 2056
n.a.
the bis-isonitrile. The IR spectrum of the gray–purple
solid revealed the absence of any isonitrile stretching fre-
quencies. The proton NMR spectrum was markedly
broadened, showing several broad peaks. The width of
the peaks (greater than 100 Hz) suggested a non-rhe-
nium(III) compound, which characteristically have only
slightly broadened, contact-shifted peaks when they ex-
hibit paramagnetism [17,18]. The mass spectrum indi-
cated an M+ of 897 m/z, corresponding to (PS3)2Re
with an appropriate isotopic abundance pattern. Single
Fig. 3. ORTEP diagram of Re(S2PS-SPS2) [1.4].
SH
P
S
S
SH
S
S
S
P
P
S
Re
P
S
S
SH
SH
Scheme 1.4. Formation of [Re(S2PS-SPS2)] (phenyl rings omitted for clarity).

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Table 6
Table 7
˚
Crystal data and structure refinement for Re(S2PS-SPS2) [1.4]
Selected bond lengths [A] and angles [ꢁ] for Re(S2PS-SPS2) [1.4]
˚
Bond lengths (A)
Empirical formula
Formula weight
Temperature (K)
C37H26Cl2P2ReS6
981.98
293(2)
0.71073
triclinic
Re(1)–S(1)
Re(1)–S(2)
Re(1)–S(5)
Re(1)–S(4)
Re(1)–P(1)
Re(1)–P(2)
S(3)–S(6)
2.3127(14)
2.3204(13)
2.3354(14)
2.3604(13)
2.4045(13)
2.4181(13)
2.066(2)
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
ꢀ
P1
˚
a (A)
10.6418(6)
11.9843(7)
˚
b (A)
Bond angles (ꢁ)
S(1)–Re(1)–S(2)
S(1)–Re(1)–S(5)
S(2)–Re(1)–S(5)
S(1)–Re(1)–S(4)
S(2)–Re(1)–S(4)
S(5)–Re(1)–S(4)
S(1)–Re(1)–P(1)
S(2)–Re(1)–P(1)
S(5)–Re(1)–P(1)
S(4)–Re(1)–P(1)
S(1)–Re(1)–P(2)
S(2)–Re(1)–P(2)
S(5)–Re(1)–P(2)
S(4)–Re(1)–P(2)
P(1)–Re(1)–P(2)
˚
c (A)
14.8036(8)
87.6280(10)
72.7280(10)
76.8040(10)
1754.5(2)
2
1.859
4.093
108.27(5)
a (ꢁ)
b (ꢁ)
c (ꢁ)
83.36(5)
100.93(5)
89.85(5)
152.78(5)
101.23(5)
83.56(5)
82.13(5)
166.87(5)
79.87(5)
162.01(5)
86.93(5)
84.33(5)
79.74(5)
108.66(5)
3
˚
Volume (A )
Z
Density (calculated) (g cmꢁ3
Absorption coefficient (mmꢁ1
F(000)
Crystal size (mm)
h Range for data collection
Limiting indices
)
)
966
0.04 · 0.18 · 0.23
2.23ꢁ to 23.27ꢁ
ꢁ10 < h < 11, ꢁ13 < k < 13,
ꢁ12 < l < 16
Reflections collected
Independent reflections
Rint
7146
4953
0.0464
Absorption correction
semi-empirical from w-scans
Maximum and minimum transmission 0.4902 and 0.2103
Refinement method
full-matrix least-squares
on F2
obtained. The product, PS3Re(PMe2Ph)2 [5], can be
purified by column chromatography in 2:1 dichloro-
methane:pentane. During the running of the column, it
was noted that the fractions on the leading edge of the
PS3Re(PMe2Ph)2 portion of the column turn a duller
reddish-purple. This indicates partial dissociation of
the sixth ligand, and is reversed upon addition of dim-
ethylphenylphosphine to the eluent. When all of the pur-
plish fractions are recombined, however, the bright
purple color returns. The Rf of dimethylphenylphos-
phine overlaps in 2:1 dichloromethane:pentane with that
of the bis-phosphine complex, allowing for retention of
the majority of the bis-phosphine complex when an ex-
cess of phosphine is present. When the pure compound
is examined by TLC without excess phosphine in solu-
tion, complete conversion to the brown five-coordinate,
mono-phosphine complex is observed within a few
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Extinction coefficient
Largest different peak and hole (eA
4953/0/434
1.037
R1 = 0.0324, wR2 = 0.0834
R1 = 0.0346, wR2 = 0.0845
0.0000(3)
1.480 and ꢁ1.028
ꢁ3
˚
)
product is also observed during the recrystallization of
pure samples of (PS3)Re(CNiPr). Oxidation in air and
loss of the volatile isonitrile presumably drives the reac-
tion in that case. The process is not reversible upon
addition of excess isonitrile to a solution of [4].
Substitution activity of phosphines with [1] was also
explored. When a solution of PS3Re(THT) [1] is treated
with an excess of dimethylphenylphosphine, a bright
purple color, similar to that of the bis-isonitrile [2], is
S
S
SH
S
S S
P
P
P
Os
P
S
S
S
S
(Phenyl rings omitted for clarity.)
S
SH
Scheme 1.5. [OsCl2(PPh3)3 + H3PS3 + NEt3 ! [Os(PS3)2] [19].

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3565
millimeters of the starting spot. This mono-phosphine
complex, PS3Re(PMe2Ph), has been previously charac-
terized [16]. In order to isolate pure [5], the purple frac-
tions from the column were concentrated to about 1 ml
under a stream of nitrogen so as not to remove the ex-
cess phosphine. The solution was then crystallized by
the slow diffusion of n-pentane into it.
When samples of [5] are dissolved in CDCl3, a red-
dish-brown solution results. The 1H NMR spectrum
obtained for this exhibits only the peaks associated
with the mono-phosphine. When a sample in CDCl3
is doped with 2 lL of dimethylphenylphosphine, only
free phosphine and several broad peaks are clearly vis-
ible in the 1H spectrum. In the 31P spectrum, only
peaks assigned to free phosphine and free phosphine
oxide are observed. At room temperature, the exchange
rate of the equatorial dimethylphenylphosphine ligand
is too rapid to observe the 1H or 31P NMR spectra
for [5].
Low temperature NMR studies were undertaken in
order to slow down the exchange rate. At temperatures
below 0 ꢁC, the exchange rate is slow enough on the
NMR time scale to permit observation of the chemical
shifts of the phosphorus nuclei. Due to the doping of
the sample with dimethylphenylphosphine (2 lL per
mL of solvent) in order to maintain the six-coordinate
complex in solution, the 31P NMR spectra prove to be
Fig. 4. ORTEP diagram of PS3Re(PMe2Ph)2 [1.5].
Table 8
Crystal data and structure refinement for PS3Re(PMe2Ph)2 [1.5]
1
more useful than the H NMR spectra. At ꢁ20 ꢁC and
Empirical formula
Formula weight
Temperature (K)
C34H34P3ReS3
817.90
183(2)
below, equatorial–axial and axial–axial coupling can
both be observed. The chemical shifts of all three phos-
phorus atoms are doublets of doublets. The largest
coupling occurs between the axial phosphorus atoms
(218 Hz) while a smaller coupling (11 and 19 Hz) is ob-
served between each axial phosphorus atom and the
equatorial phosphorus atom. Both phosphorus atoms
of the PMe2Ph ligands are observed upfield of free
dimethylphenylphosphine. As the temperature is
warmed to 20 ꢁC, the peaks broaden, and at room tem-
perature are no longer observable. The free dimethyl-
phenylphosphine phosphorus resonance is also not
visible at room temperature; these samples contained
a smaller excess of phosphine than initial room temper-
ature studies, and the peak disappears due to exchange
˚
Wavelength (A)
0.71073
monoclinic
P21/c
Crystal system
Space group
Unit cell dimensions
˚
a (A)
14.7168(14)
12.8583(13)
18.029(2)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
108.150(2)
3241.9(5)
4
1.676
4.113
3
˚
Volume (A )
Z
Density (calculated) (g cmꢁ3
Absorption coefficient (mmꢁ1
F(000)
)
)
1624
Crystal size (mm)
h Range for data collection
Limiting indices
0.02 · 0.10 · 0.37
2.15ꢁ to 23.26ꢁ
1
ꢁ14 < h < 16, ꢁ14 < k < 14,
upon warming. In the H NMR spectrum, the methyl
ꢁ20 < l < 16
12901
resonances from both coordinated phosphines and free
phosphine are observed to coalesce from three separate
resonances at ꢁ50 ꢁC to a broad singlet at 1.5 ppm at
20 ꢁC.
An X-ray crystallographic study of the crystals grown
from dichloromethane–pentane confirmed the octahe-
dral geometry about the rhenium center with two phos-
phine ligands. An ORTEP diagram is shown in Fig. 4.
Crystallographic information and selected bond lengths
and angles are available in Tables 8 and 9. Complete
data can be found in Appendix A. The three phosphorus
atoms exhibit significantly different Re–P bond lengths.
Reflections collected
Independent reflections
Rint
4644
0.0876
Absorption correction
Integration
Maximum and minimum transmission 0.9148 and 0.3676
Refinement method
Full-matrix least-squares
on F2
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Extinction coefficient
Largest different peak and hole (e A
4644/0/371
1.052
R1 = 0.0484, wR2 = 0.0971
R1 = 0.0728, wR2 = 0.1042
0.00117(14)
1.596 and ꢁ1.411
ꢁ3
˚
)

3566
A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
Table 9
readily upon chromatography, dissolution, or applica-
tion of vacuum, while the corresponding isonitriles do
not. Crystals of the bis-iPrNC rhenium complex are
fairly stable even under vacuum. Applying vacuum to
a crystalline sample of [2] for 3 h resulted in less than
5% formation of the mono-isonitrile. Compound [2] is
also more stable to loss of the sixth ligand than its tech-
netium congener [12]. PS3Tc(CNiPr)2 readily loses its
second isonitrile when dissolved in the absence of a large
excess (100-fold) of the ligand.
No indication has been seen of substitution of a third
phosphine or isonitrile onto the rhenium center to form
the corresponding 18-electron, seven-coordinate com-
plexes. The rhenium center does not appear overly
crowded in three-dimensional renderings of the octahe-
dral complexes. However, the PS3 may be too bulky to
allow the coordination expansion that is seen with other
Re complexes with carbonyl and isonitrile ligands [e.g.
ReBr3(CN-p-tolyl)4] [21].
˚
Selected bond lengths [A] and angles [ꢁ] for PS3Re(PMe2Ph)2 [1.5]
˚
Bond lengths (A)
Re(1)–P(1)
Re(1)–S(2)
Re(1)–S(1)
Re(1)–S(3)
Re(1)–P(3)
Re(1)–P(2)
2.297(2)
2.306(2)
2.338(2)
2.345(2)
2.406(2)
2.532(3)
Bond angles (ꢁ)
P(1)–Re(1)–S(2)
P(1)–Re(1)–S(1)
S(2)–Re(1)–S(1)
P(1)–Re(1)–S(3)
S(2)–Re(1)–S(3)
S(1)–Re(1)–S(3)
P(1)–Re(1)–P(3)
S(2)–Re(1)–P(3)
S(1)–Re(1)–P(3)
S(3)–Re(1)–P(3)
P(1)–Re(1)–P(2)
S(2)–Re(1)–P(2)
S(1)–Re(1)–P(2)
S(3)–Re(1)–P(2)
P(3)–Re(1)–P(2)
84.68(8)
84.12(8)
102.36(9)
83.63(8)
100.40(9)
152.95(9)
171.92(9)
87.34(8)
96.41(8)
99.07(8)
97.45(8)
177.84(8)
78.26(9)
79.54(8)
90.54(8)
2.1. Consideration of electronic structure
The geometries of the bis-PMe2Ph and bis-CNiPr
complexes [5] and [2] are similar. The S(1)–Re–C(19)
and S(3)–Re–C(19) angles of the isonitrile complex
are slightly smaller (76ꢁ versus 79ꢁ) than the corre-
sponding S–Re–P angles in the phosphine complex.
Overall, the two structures both exhibit a distorted
octahedral configuration. This distortion is great en-
ough that the isonitrile complex [2] exhibits a non-
paramagnetically broadened 1H NMR spectrum. In
contrast, the technetium congener of [2] is reported
The PS3 phosphorus–rhenium length is the shortest at
˚
2.297(2) A, while P(3) trans to the P of the PS3 exhibits
˚
a Re–P bond length of 2.406(2) A. The longest bond is
˚
Re–P(2), trans to S(2) of the PS3, at 2.532(3) A. The
lengthening indicates a likely S-induced structural trans
effect from the p-acid thiolate opposite that phosphine
˚
[9]. Most Re(III)–P bonds are between 2.35 and 2.45 A
[13]; the very long Re–P(2) bond is in agreement with
the lability of the sixth ligand displayed in solution. A
rhenium complex of the bidentate ligand (ortho-mercap-
tophenyl)diphenylphosphine (S–P), Re(S–P)3, contains
two trans phosphorus atoms and a phosphorus atom-
trans to a sulfur atom [20]. The Re–P bonds vary from
1
to exhibit a contact-shifted H NMR spectrum [6]. A
similar Tc/Re paramagnetic/diamagnetic shift is seen
in complexes of the ligand (ortho-mercaptophe-
nyl)diphenylphosphine (S–P), mentioned above. The
rhenium complex Re(S–P)3 is EPR silent and possesses
a diamagnetic 1H NMR spectrum while the isomor-
phous technetium congener has a measured magnetic
susceptibility (Evans method) of 3.0lB [20,22]. In gen-
eral, rhenium(III) octahedral complexes exhibit para-
magnetically shifted 1H NMR spectra. For those
complexes, the orbitals composing the t2g set on an
octahedral metal center are close enough in energy to
each other that a two unpaired electron ground state
exists. Despite perturbations from the ideal structure,
the paramagnetism is generally seen, characteristically
displayed for rhenium d4 complexes by a Knight-
˚
2.391(5) to 2.473(5) A, with the phosphorus trans to a
sulfur exhibiting the longest Re–P bond length, analo-
gously to [1.5].
In the bis-isonitrile complex [2], the Re–C bonds
are much more similar to each other [2.038(12) versus
˚
2.093(11) A] than the Re–P(2) and Re–P(3) bonds are
in [5]. Correspondingly, a much lower lability of the
sixth ligand is noted for [2]. The bis-phosphine com-
plex [5] also displays the distortion from octahedral
geometry about the central rhenium present in [2].
The S(1)–Re–S(3) angle is slightly less contracted than
in [2], at 152.95(9)ꢁ, to allow for the bulkier phosphine
ligand. The phenyl ring of the equatorial phosphine
[P(2)] is pointed up in alignment with the aryl rings
of the PS3.
The six-coordinate isonitrile complexes are more sta-
ble to loss of the sixth ligand than the corresponding
phosphine complexes, particularly considering ligand
volatility. The PMe2Ph compound loses its sixth ligand
1
shifted H NMR spectrum [17,18,23]. We suggest that
the nature of the distortion, displayed in Scheme 1.6,
results in a significant increase in energy in the dxy
orbital, producing a diamagnetic ground state. Presum-
ably, there is also an increase in the dyz, but this would
be to a lesser degree. The display of diamagnetism in
nominally octahedral complexes of d4 metal ions is
unusual.

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3567
Table 10
z
P
Re
L
Comparison of 31P NMR data for trigonal bipyramidal and octahedral
S
S
S
L
a
PS3Re compounds, referenced to 85% H3PO4
Coordinating
Ligand (L)
PS3ReL (in ppm)
PS3ReL2 (in ppm)
y
x
eg
PMe2Ph
140.4 [17.3 for L] [16]
113.6 [ꢁ57.6 ax,
ꢁ73.5 eq]b
110.0
dxy
CNiPr
CN(2,6-Me2Ph)
137.7
137.9 [16]
121.8
t2g
111.2
dxz , dyz
THT
CO
a
135.7 [16]
113.2
Scheme 1.6. Distortion from ideal octahedral geometry lead to
diamagnetic ground state.
L = PMe2Ph, CNiPr, THT: Solvent = CDCl3; L = DMP-NC,CO:
Solvent = CD2Cl2.
b
Temperature = ꢁ50 ꢁC.
2.2. Further substitution and reactivity studies
tive intensity of the integral region is approximately
85:15.
The PS3 system has also been explored with a more
volatile ligand. Carbon monoxide can be used as the
coordinating ligand to form PS3Re(CO) [6]. The
mono-CO complex was first synthesized by Daughtry
by bubbling of CO through the initial reaction solution
of PS3Re(THT), resulting in the formation of a brown
solution [16]. After several weeks, PS3Re(CO) was iso-
lated from this solution. The complex was also isolated
by leaving a solution of PS3Re(PR3) under a stream of
CO for several weeks. An intermediate, PS3Re(CO)
(PR3), with the two phosphorus atoms trans to each
other, was tentatively identified [16]. No evidence of
the substitution of additional CO molecules was
presented.
Two new procedures have been developed for the
synthesis of the mono-CO [6] via a CO-saturated reac-
tion solution at positive pressure of CO. These meth-
ods produce the compound in several hours instead
of several weeks. The compound has been synthesized
in two ways: first by addition of lithiated PS3 to a
CO-saturated THF solution of ReBr3(THT)3 or by
the addition of a THF solution of H3PS3 and iPr2EtN
to a CO-saturated THF solution of ReBr3(THT)3. The
first reaction was left under a positive pressure of CO
and formation of a red–brown product was noted.
This was concentrated after several hours and purified
by column chromatography. The second method pro-
ceeded by bubbling CO into the open reaction flask
while heating the solution. In approximately one half
hour, the maximum product formation was noted.
Product [6] was isolated by column chromatography
on silica in 1:2 dichloromethane:pentane. Once puri-
fied, solutions of pure PS3Re(CO) can be treated with
additional CO. This produces a blue solution, a color
change that is readily reversible upon removal of
the CO stream. In a Young valve NMR tube under
a CO atmosphere, the presence of the octahedral bis-
CO complex [6] can be detected via the characteristic
resonance of the PS3 (see Table 10). A peak appears
in the 31P NMR spectrum at 113.2 ppm, indicative
of an octahedral complex. The ratio of [6]:[7] by rela-
2.3. Reactivity of PS3Re(CO)
The reactivity of [6] with regards to addition and sub-
stitution reactions was investigated. With THT or pyri-
dine, no reaction occurs when [6] is dissolved in neat
reactant, heated to 90 ꢁC, and flushed with nitrogen.
The 31P NMR signal remains constant at 135 ppm,
and the solution remains a reddish-brown for over a
week. With phosphines and phosphinites, addition of
greater than one equivalent leads to the formation of a
purple complex. With triphenylphosphine, a purple solid
has been isolated that has 31P NMR resonances at 124
and ꢁ6 ppm, indicating a six-coordinate complex. The
IR spectrum exhibits
a stretching frequency at
1908 cmꢁ1, with a shoulder at 1929 cmꢁ1, indicating
the presence of bound CO on the molecule. The 31P
NMR signals are also singlets, indicating a lack of cou-
pling between the phosphorus atoms, which suggests
that the two phosphorus atoms are not trans to each
other. Dissolution induces loss of the phosphine; at-
tempted purification by column chromatography re-
sulted in the reformation of starting material [6]. The
physical characteristics of the compound indicate it to
be PS3Re(trans-CO)PPh3 [8] (see Table 11). This can
be contrasted with the intermediate in formation of [7]
identified by Daughtry as PS3Re(CO)(trans-PPh3) [9]
(see Scheme 1.7). The incoming ligand attacks along
Table 11
Comparison of IR stretching frequencies (KBr, cmꢁ1) for C@O bonds
of PS3Re(CO)Lx and NS3Re(CO) compounds [x = 0,1]
x = 0
x = 1, trans
x = 1, cis
NS3 [11]
1876
1951
1951
1951
PS3, L = PPh3
PS3, L = PEt3
PS3, L = P(n-Bu)3
1997
1981
1986
1910
Note: trans and cis refer to the position of the two phosphorus atoms
relative to one another.

3568
A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
P
Re
C
P
P
P
S
S
S
Re
C
S
S
S
C
S
S
vs.
S
Re
S
PPh3
Re
S
S
+ CO
+ PPh3
O
PPh3
PPh3
O
O
υ(CO) = 1908 cm-1
υ(CO) = 1997 cm-1
υ(CO) = 1951 cm-1
Scheme 1.7. Synthesis of PS3Re(CO)(PR3) complexes (phenyl rings omitted for clarity).
the equatorial plane and substitution into the axial posi-
tion trans to the PS3 occurs only slowly. The synthesis of
[8] has been monitored by UV–vis spectroscopy, and
isosbestic points are maintained. Substitution with iso-
nitriles occurs much more readily. Addition of an excess
of iPrNC to a solution of [6] results in immediate forma-
tion of the bis-isonitrile [2].
ing a tenacious carbonyl ligand, is a prime candidate
for this. In particular, the chemistry of bridging ligands
could present an interesting avenue of further research.
Collaboration with the research group of Professor
C.C. Cummins to study small molecule activation with
these compounds is ongoing. Bulkier versions of the
PS3 ligand [14] could also be explored to isolate the tri-
gonal bipyramidal species and focus on reactivity at the
apical ligand without competing substitution reactions.
2.4. Ligand exchange
The PS3 phosphine complexes are also subject to li-
gand exchange with stronger donor ligands. Addition
of excess isonitrile leads to formation of the octahedral
bis-isonitrile complexes. Both PS3Re(PPh3) [16] and
PS3Re(PMe2Ph) can be substituted in this manner, using
either 2,6-dimethylphenyl isonitrile (2,6-DMP-NC) or
iPrNC, to form the respective bis-isonitrile complexes
PS3Re(2,6-DMP-NC)2 [10] or PS3Re(iPrNC)2 [2]. De-
spite the bulky nature of 2,6-DMP-NC, it forms an octa-
hedral complex as well, as indicated by the characteristic
4. Experimental
Tris(o-mercaptophenyl)phosphine and ReBr3(THT)3
were synthesized according to literature procedures
[14,25]. Phosphines and isonitriles were purchased from
Strem. All solvents were purchased anhydrous and air-
free from Aldrich. Tetrahydrothiophene was distilled
from CaH2 and stored under argon over 4 A molecular
sieves.
All X-ray data were collected using a Siemens plat-
form goniometer with a CCD detector using molybde-
num Ka radiation (k = 0.71073 A). Phosphorus NMR
˚
1
31P and H NMR spectra. The 31P NMR resonance at
111 ppm is a clear indicator of the octahedral structure
(see Table 10).
˚
spectra were collected on a Varian Mercury 300 at
121.49 MHz in CDCl3 and are proton-decoupled unless
otherwise noted. An external standard of 85% H3PO4
was used for reference. Proton NMR spectra were col-
lected on a Varian Mercury 300 at 300.10 MHz in
CDCl3 unless otherwise noted, with the residual CHCl3
in the solvent used as a reference.
3. Conclusion
The tetradentate umbrella ligand PS3 presents a rich
chemistry on rhenium. In particular, it provides an inter-
esting tableau for a study of the effects of ligand choice
on electronic behavior.
This chemistry reaffirms the observed differences in
coordination number between second and third row
transition metals, namely that for similar compounds
and despite nearly identical atomic radii, the third-row
metals have a tendency towards increasing their coordi-
nation number. This is seen by the stable octahedral PS3
compounds on rhenium, as compared to the instability
of related compounds on technetium, with a marked
preference for the trigonal bipyramidal geometry. The
TcOX4ꢁ versus. TcOX52ꢁ relationship is similar, demon-
strated by the facile exchange of the fifth halide [24].
The substitution chemistry in the trigonal bipyrami-
dal complexes can be explored in even greater depth in
the future. The mono-carbonyl complex, while display-
4.1. PS3Re(THT) [1]
A THF solution of three equivalents of P(SLi)3 was
added via cannula to a THT solution of ReBr3(THT)3.
The initially brown–gray solution was heated under ar-
gon. At reflux, the solution had turned a deep burgundy
color. Concentration of the solution in vacuo followed
by column chromatography resulted in the isolation of
PS3Re(THT), a deep red solid. The compound is unsta-
ble in aerobic solution and decomposes in under 24 h to
unknown products. Attempts to recrystallize under an
inert atmosphere were unsuccessful. 31P NMR d: 121.8
1
(s). H NMR d: 8.51 (t, 3H); 7.59 (dd, 3H); 7.30 (tt,
3H); 7.19 (tt, 3H); 3.68 (m, 4H); 2.39 (m, 4H).

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3569
4.2. PS3Re(CNiPr)2 [2]
Crystals suitable for X-ray diffraction studies were ob-
tained from a slow diffusion of pentane into a CH2Cl2
solution of the compound.
Under argon, 0.0532 g H3PS3 (0.148 mmol) in 10 mL
of anhydrous THF were lithiated with 1 M LiN(TMS)2
(450 lL, 3 equiv.). The solution was evaporated in va-
cuo and redissolved in THF, then the solution was
transferred via cannula to a flask containing 0.1032 g
ReBr3(THT)3 (0.149 mmol) dissolved in 20 mL THF.
The dark green–brown solution was brought to reflux
and 70 lL of CNiPr (0.77 mmol) was added via syringe.
After 2 h at reflux, the reaction was allowed to cool to
room temperature, and the solvent was then removed
under a stream of nitrogen. Column chromatography
with 2:1 CH2Cl2:pentane resulted in the isolation of a
minor brown fraction as well as a major purple fraction.
The major fraction was identified as PS3Re(CNiPr)2
with recovery of 0.062 g (62% yield), while the brown
fraction is identified below. Crystals suitable for X-ray
diffraction studies were obtained from a slow diffusion
of ether into a CH2Cl2 solution of the compound.
1H NMR (CD2Cl2, Bruker 400) d: 8.46 (t, 2H); 7.96 (t,
1H); 7.63 (dd, 2H); 7.33-7.15 (m, 5H); 6.96 (t, 1H); 5.41
1H NMR (CD2Cl2, Bruker 400) d: 8.50 (t, 3H); 7.55
(dd, 3H); 7.36 (t, 3H); 7.24 (t, 3H); 5.03(sept, 1H);
1.67 (d, 6H). 31P NMR d: 137.7 (s). IR (KBr, cmꢁ1):
2115 m(C„N).
4.5. X-ray data collection parameters for [3]
The data for [3] were collected using a crystalline
block having dimensions 0.22 · 0.22 · 0.25 mm. The
crystal system was monoclinic (a = c = 90ꢁ) with a =
˚
˚
˚
10.3354(6) A, b = 13.1611(8) A, c = 16.3387(10) A, and
b = 91.2730(10)ꢁ; this results in
a
cell volume
3
˚
V = 2221.9(2) A with Z = 4. The space group was
P21/c. The absorption coefficient was 5.831 mmꢁ1, the
calculated density q = 1.826 g cmꢁ3, and F(000) =
1184. The data were obtained at 183(2) K in the h range
2.49 to 23.28ꢁ with limiting indices ꢁ11 6 h 6 8;
ꢁ14 6 k 6 14; ꢁ16 6 l 6 18. Of the 8615 reflections col-
lected, 3197 were independent (Rint = 0.0381). The struc-
ture was solved by direct methods in conjunction with
standard difference Fourier techniques and an empirical
absorption correction was applied [26]. Least squares
refinement based upon F2 with 3197 data, 0 restraint
and 256 parameters converged with final residuals
R1 = 0.0245; wR2 = 0.0636; and GOF = 1.176 based on
I > 2r(I). The extinction coefficient was 0.00180(12).
(sept, 1H); 3.91 (sept, 1H); 1.63 (d, 6H); 0.83 (d, 6H). 31
P
NMR (CDCl3): 110.0 (s). IR (KBr, cmꢁ1): 2154, 2097
m(C„N). Visible (CHCl3, nm): kmax 318 (sh); 397
(e = 3700 l molꢁ1 cmꢁ1); 538 (e = 5200 l molꢁ1 cmꢁ1).
Elemental analysis: Found (Theory) %C 45.71(45.93);
%H 3.52(3.85); %N 3.75(4.12).
4.3. X-ray data collection parameters for [2]
4.6. (S2PS-SPS2)Re [4]
The data for [2] were collected using a crystal having
dimensions 0.20 · 0.21 · 0.23 mm. The crystal sys-
tem was orthorhombic (a = b = c = 90ꢁ) with a =
This was isolated from a column separation of the
PS3Re(CNiPr)x materials in 2:1 dichloromethane:pen-
tane. Single crystals were obtained from pentane layered
over a dichloromethane solution. The product is also
observed during recrystallizations of samples of [3] that
were determined to be pure prior to recrystallization.
1H NMR (broad) d: 14.0 (s), 13.1 (s),12.5 (s), 9.8 (s),
7.8 (s), 5.9 (s). FAB(+)MS m/z: 897 M+.
˚
˚
˚
18.7467(12) A, b = 13.2509(9) A, and c = 10.3297(7) A;
3
˚
this results in a cell volume V = 2566.0(3) A with
Z = 4. The space group was Pna21. The absorption coef-
ficient was 5.060 mmꢁ1
,
the calculated density
q = 1.760 g cmꢁ3, and F(000) = 1336. The data were
obtained at 183(2) K in the h range 3.81 to 23.25ꢁ with
limiting
indices
ꢁ9 6 h 6 20;
ꢁ14 6 k 6 12;
ꢁ11 6 l 6 3. Of the 5552 reflections collected, 2003 were
independent (Rint = 0.0467). The rhenium atom was lo-
cated by the Patterson method before using standard
difference Fourier techniques to complete the solution
of the structure [26]. Least squares refinement based
upon F2 with 2003 data, 1 restraint and 299 parameters
4.7. X-ray data collection parameters for [4]
The data for [4] were collected using a crystalline plate
having dimensions 0.04 · 0.18 · 0.23 mm. The crystal
˚
system
was
triclinic,
with
a = 10.6418(6) A,
˚
˚
b = 11.9843(7) A, c = 14.8036(8) A, a = 87.6280(10)ꢁ,
b = 72.7280(10)ꢁ, and c = 76.8040(10)ꢁ with space group
converged
with
final
residuals
R1 = 0.0324;
3
ꢀ
˚
wR2 = 0.0848; and GOF = 1.143 based on I > 2r(I).
The extinction coefficient was 0.0004(3).
P1. The cell volume was 1754.5(2) A with Z = 2. The
absorption coefficient was 4.093 mmꢁ1, the calculated
density q = 1.859 g cmꢁ3, and F(000) = 966. The data
were obtained at 293(2) K in the h range 2.23–23.27ꢁ with
4.4. PS3Re(CNiPr) [3]
limiting
indices
ꢁ10 6 h 6 11;
ꢁ13 6 k 6 13;
The brown fraction from the above reaction was iso-
lated and identified as PS3Re(CNiPr). In all cases, less
than 5% of the mono-substituted complex was obtained.
ꢁ12 6 l 6 16. Of the 7146 reflections collected, 4953
were independent (Rint = 0.0464). The structure was
solved by direct methods in conjunction with standard

3570
A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
difference Fourier techniques and a semi-empirical
absorption from w-scans was applied [26]. Least squares
refinement based on F2 with 4953 data, 0 restraints, and
434 parameters converged with final residuals
R1 = 0.0324; wR2 = 0.0834; and GOF = 1.037 based on
I > 2r(I). The extinction coefficient was 0.0000(3).
Patterson method before using standard difference Fou-
rier techniques to complete the solution of the structure
[26]. An integration absorption correction was applied.
Least squares refinement based upon F2 with 4644 data,
0 restraint and 371 parameters converged with final
residuals R1 = 0.0484; wR2 = 0.0971; and GOF = 1.052
based on I > 2r(I). The extinction coefficient was
0.00117(14).
4.8. PS3Re(PMe2Ph)2 [5]
Method One. As in the synthesis of [2] and [3] above,
Li3PS3 was added to ReBr3(THT)3. The solution was
heated under argon for 1 h, during which it turned deep
purple. The solution was cooled and concentrated to
2 mL. Column chromatography (2:1 CH2Cl2:pentane
on silica) led to isolation of a purple fraction. This
was concentrated to a volume of 1 mL under a stream
of nitrogen. Crystals were grown by the slow diffusion
of n-pentane into the solution.
Method Two. In a 50 mL Schlenk flask, ReBr3(THT)3
(0.1024 g, 0.148 mmol) was dissolved in 10 mL of dry
THF under argon. A solution of H3PS3 (0.0533 g,
0.149 mmol) and iPr2NEt (26 lL, 0.149 mmol) in THF
was added via syringe. Dimethylphenylphosphine
(100 lL, 5 equiv.) was then added via syringe. The solu-
tion became reddish-orange and turned purple upon
mild heating. After 3 h, the THF was removed under
vacuum, and the residue was redissolved in minimal
dichloromethane, approximately 2 mL. Heptane
(40 mL) was added to the solution, and it was placed
in the freezer overnight. The title compound was recov-
ered as a precipitate in 47 % yield (0.057 g).
4.10. PS3Re(CO) [6]
Tetrahydrofuran was saturated with CO by bubbling
CO through a flask of THF for 30 min. ReBr3(THT)3
(0.6041 g, 0.875 mmol) was dissolved in the THF in a
50 mL Schlenk flask under a positive pressure of CO.
The H3PS3 ligand (0.3267 g, 0.911 mmol) was dissolved
in a small amount of THF and deprotonated with iPr2-
NEt (1 equiv., 0.9 mmol). The PS3 solution was then
added to the rhenium solution by syringe. Moderate
heating of the solution produced a reddish color and
gradually evaporated the solvent over a period of 2 h.
The residue was purified by column chromatography
(2:1 CH2Cl2:pentane on silica) to yield PS3Re(CO) as
an orange–brown solid, with recovery of 0.247 g (49 %
yield.) The product was spectroscopically identical as
determined by NMR and IR studies to a sample previ-
ously prepared by a different method [16] (for reference
purposes: 31P NMR (CD2Cl2): d:135.3 ppm; IR (KBr):
1951 cmꢁ1).
4.11. PS3Re(CO)2 [7]
1H NMR (Varian 501, 500.248 MHz, ꢁ50 ꢁC) d: 8.1–
5.9 (m, aryl); 1.97 (s, equatorial P(CH3)2Ph); 1.14 (dd,
axial P(CH3)2Ph). 31P NMR (Varian 501, 202.66 MHz,
ꢁ50 ꢁC) d: 113.6 (dd, JP-Ptrans = 218 Hz, JP-Pcis = 11 Hz,
Compound [6] (10 mg) was dissolved in 1 g dichloro-
methane-d2. The solution was placed in a Young valve
NMR tube and flushed with CO twice. The tube was
opened to CO for 15 min, then sealed at a positive pres-
sure of CO. The solution was studied by 31P NMR spec-
troscopy. 31P NMR (CD2Cl2) d: 135.3 [PS3Re(CO)];
113.16 [PS3Re(CO)2].
PS ); ꢁ57.6 (dd, JP-Ptrans = 218 Hz, JP-Pcis = 19 Hz, axial
3
PMe2Ph); ꢁ73.5 (dd, JP-Pcis = 11 hz, JP-Pcis = 19 Hz,
equatorial PMe2Ph).
Visible (CHCl3, nm): kmax 397 (e = 970 l molꢁ1
cmꢁ1); 536 (e = 1400 l molꢁ1 cmꢁ1).
4.12. PS3Re(CO)(PPh3) [8]
4.9. X-ray data collection parameters for [5]
Compound [6] (5.0 mg, 8.8 lmol) was dissolved in
0.5 g CD2Cl2. A solution of PPh3 (4.6 mg, 18 lmol) in
0.5 g CD2Cl2 was added. The color rapidly changed
from brown to purplish-blue. A crystalline precipitate
was obtained by layering with heptane. Quantitative
transformation to the title compound resulted. 1H
NMR (CDCl3) d: 8.0–7.8 (m), 7.6–7.0(m). 31P NMR
(CDCl3) d: 124.4 (s), ꢁ6.0 (s). IR (KBr, cmꢁ1): 1929
(sh), 1908 m(C„O).
The data for [5] were collected using a crystalline
plate having dimensions 0.03 · 0.10 · 0.37 mm. The
crystal system was monoclinic (a = c = 90ꢁ) with
˚
˚
˚
a = 14.7168(14) A, b = 12.8583(13) A, c = 18.029(2) A,
and b = 108.150(2)ꢁ; this results in a cell volume
3
˚
V = 3241.9(5) A with Z = 4. The space group was
P21/c. The absorption coefficient was 4.113 mmꢁ1, the
calculated
density
q = 1.676 g cmꢁ3
,
and
F(000) = 1624. The data were obtained at 183(2) K in
the h range 2.15 to 23.26ꢁ with limiting indices
ꢁ14 6 h 6 16; ꢁ14 6 k 6 14; ꢁ20 6 l 6 16. Of the
12901 reflections collected, 4644 were independent
(Rint = 0.0876). The rhenium atom was located by the
4.13. PS3Re(CN-2,6-Me2C6H4)2 [10]
To a solution of PS3Re(PPh3) in THF under argon
was added 1 equiv. of 2,6-dimethylphenyl isocyanide

A. Shellenbarger-Jones et al. / Inorganica Chimica Acta 358 (2005) 3559–3571
3571
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(2,6-DMP-NC) as a solution in THF. There was an
immediate color change from brown to deep purple.
By TLC, three colored components were visible, one
brown and two purple. The brown component had an
Rf consistent with starting material. Free triphenylphos-
phine was also indicated. Addition of a small amount of
additional isocyanide resulted in minimal change in the
TLC. The products were separated by column chroma-
tography (1:2 dichloromethane:pentane on silica) and
characterized. The brown fraction was starting material.
The major purple fraction isolated was identified as
PS3Re(2,6-DMP-NC)2. The bis-isocyanide was recrys-
tallized by slow evaporation of a heptane solution.
1H NMR (CD2Cl2) d 8.49(t, 2H); 8.00 (t, 1H); 7.66 (d,
2H); 7.37 (d, 1H); 7.35–6.85 (m, 12H); 2.75 (s, 6H); 1.95
(s, 6H). 31P NMR (CD2Cl2) d 111.2 (s). IR (KBr, cmꢁ1):
2123, 2056 m(C„N).
[10] B. Neuner, R.R. Schrock, Organometallics 15 (1996) 5.
[11] H. Spies, M. Glaser, H.J. Pietzsch, F.E. Hahn, T. Lugger, Inorg.
Chim. Acta 240 (1995) 465.
[12] N. De Vries, J. Cook, A.G. Jones, A. Davison, Inorg. Chem. 30
(1991) 2662.
4.14. Reaction of isonitriles with PS3RePMe2Ph
[13] P. Perez-Lourido, J. Romero, J. Garcia-Vazquez, A. Sousa,
K.P. Maresca, D.J. Rose, J.A. Zubieta, Inorg. Chem. 37 (1998)
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[14] E. Block, G. Ofori-Okai, J.A. Zubieta, J. Am. Chem. Soc. 111
(1989) 2327.
[15] L. Malatesta, F. Bonati, Isocyanide Complexes of Metals, Wiley-
Interscience, London, 1969.
[16] S. Daughtry. Rhenium Complexes with the Umbrella Ligand Tris
(o-Mercaptophenyl)Phosphine, M.Sc. thesis, Massachusetts Insti-
tute of Technology, 1997.
[17] J. Chatt, G.J. Leigh, D.M.P. Mingos, E.W. Randall, D. Shaw,
Chem. Commun. (1968) 419.
[18] E.W. Randall, D. Shaw, J. Chem. Soc. (A) (1969) 2867.
[19] J.R. Dilworth, Y. Zheng, J.R. Miller, J. Chem. Soc., Dalton
Trans. (1992) 1757.
A series of 2 mL solutions containing 10 mg of
PS3Re(PMe2Ph) in CH2Cl2 were made. A solution of
10 equivalents of isonitrile (2,6-DMP-NC or iPrNC)
was made in 1 mL dichloromethane and added to the
Re solution in 0.1 mL aliquots. Addition of one equiva-
lent of isonitrile resulted in a mixture of three fractions,
one brown and two purple, as above. Addition of great-
er than two equivalents resulted in quantitative transfor-
mation to either [1.10] or [1.2], depending on the
isonitrile used.
[20] J.R. Dilworth, A.J. Hutson, S. Morton, M. Harman, M.B.
Hursthouse, J.A. Zubieta, C.M. Archer, J.D. Kelly, Polyhedron
11 (1992) 2151.
[21] P.M. Treichel, J.P. Williams, W.A. Freeman, J.I. Gelder, J.
Organomet. Chem. 170 (1979) 247.
Appendix A. Supplementary data
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.ica.
2004.09.065.
[22] C. Bolzati, F. Refosco, F. Tisato, G. Bandoli, A. Dolmella,
Inorg. Chim. Acta 201 (1992) 7.
[23] H.P. Gunz, G.J. Leigh, J. Chem. Soc. (A) (1971) 2229.
[24] R.W. Thomas, M.J. Heeg, R.C. Elder, E. Deutsch, Inorg. Chem.
24 (1985) 1472.
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