Synthesis of neutral iridium(III) and rhodium(III) complexes with the proligands Pr2iP(C6H4-SH-2) [priPSH] 1; PhP(C6H4-SH-2)2 [phPS2H2]2 and PhP(C2H4SH)2 [ePS2H3]3

Article abstract of DOI:10.1016/S0020-1693(02)00695-3

The reactivity of the hybrid phosphorus-sulfur proligands prⁱPSH, phPS₂H₂ and ePS₂H₂ with iridium and rhodium precursors has been explored. By reacting IrCl₃ with prⁱPSH in the presence of NEt₃ as base, the octahedral Ir(III) specie [Ir(prⁱPS)₃] was obtained and its crystal structure determined. Reactions of the potentially tridentated proligands phPS₂H₂ and ePS₂H₂ with trans-[MF(CO)(PPh₃)₂] (M=Rh and Ir) were also investigated. Complexes of general formula [M(H)(phPS₂)(CO)(PPh₃)] were obtained with phPS₂H₂. A single crystal X-ray structure determination for [Rh(H)(phPS₂)(CO)(PPh₃)] showed the complex to be octahedral. Reactions with the aliphatic proligand ePS₂H₂ afforded analogous species to those with phPS₂H₂.

Full text of DOI:10.1016/S0020-1693(02)00695-3

Inorganica Chimica Acta 332 (2002) 101–107
www.elsevier.com/locate/ica
Synthesis of neutral iridium(III) and rhodium(III) complexes with
the proligands Pr2i P(C6H4ꢀSH-2) [priPSH] 1; PhP(C6H4ꢀSH-2)2
[phPS2H2]2 and PhP(C2H4SH)2 [ePS2H2]3. The X-ray crystal
structures of [Ir(priPS)3] and [Rh(H)(phPS2)(CO)(PPh3)]
David Morales-Morales a,*, Sergio Rodr´ıguez-Morales a, Jonathan R. Dilworth b,
Antonio Sousa-Pedrares b, Yifan Zheng b
a Instituto de Qu´ımica, Uni6ersidad Nacional Auto´noma de Me´xico, Cd. Uni6ersitaria, Circuito Exterior, Coyoaca´n, 04510 Mexico, D.F.
b Inorganic Chemistry Laboratory, Uni6ersity of Oxford, South Parks Road, Oxford OX1 3QR, UK
Received 14 September 2001; accepted 30 November 2001
Abstract
The reactivity of the hybrid phosphorus–sulfur proligands priPSH, phPS2H2 and ePS2H2 with iridium and rhodium precursors
has been explored. By reacting IrCl3 with priPSH in the presence of NEt3 as base, the octahedral Ir(III) specie [Ir(priPS)3] was
obtained and its crystal structure determined. Reactions of the potentially tridentated proligands phPS2H2 and ePS2H2 with
trans-[MF(CO)(PPh3)2] (M=Rh and Ir) were also investigated. Complexes of general formula [M(H)(phPS2)(CO)(PPh3)] were
obtained with phPS2H2. A single crystal X-ray structure determination for [Rh(H)(phPS2)(CO)(PPh3)] showed the complex to be
octahedral. Reactions with the aliphatic proligand ePS2H2 afforded analogous species to those with phPS2H2. © 2002 Elsevier
Science B.V. All rights reserved.
Keywords: Phosphorus–sulfur proligands; Rhodium complexes; Iridium complexes; Hydrides; Crystal structures
ceuticals [4]. These complexes have shown an intriguing
variety of structures [5] or unusual oxidation states and
enhanced solubility [6], making these species excellent
candidates for further studies in reactivity. In the spe-
cific case of compounds with elements of the Groups
8–10 these may be suitable species for catalytic screen-
ing. Moreover, the presence of these ligands in the
coordination sphere of transition metal-complexes may
render interesting behaviours in solution as these lig-
ands can be capable of full or partial de-ligation (hemi-
lability) [7] being able to provide important extra
coordination sites for incoming substrates during a
catalytic process [8]. To date, most studies have focused
on bidentate ligands such as R2PCH2CH2SH [9] and
R2P(C6H4ꢀSH-2) [10], while the potentially tridentate
proligands RP(CH2CH2SH)2 and RP(C6H4ꢀSH-2)2
have received much less attention [11]. We report here
on the coordination chemistry of rhodium and iridium
with the mixed phosphine-thiol proligands Pri2P(C6H4ꢀ
SH-2) [priPSH]; PhP(C6H4ꢀSH-2)2 [phPS2H2] and
PhP(C2H4SH)2 [ePS2H2].
1. Introduction
The chemistry of metal complexes of both simple and
bulky thiolate ligands has been well documented [1].
Recently, attention has increasingly been paid to the
coordination chemistry of polydentate ligands incorpo-
rating both thiolate and tertiary phosphine donor lig-
ands, as their combination is likely to confer unusual
structures and reactivities on their metal complexes [2].
Some of these complexes have been used as models of
biologically active centres in metalloproteins such as
ferredoxins, nitrogenase, blue copper proteins and
metallothioneins [3] or as models for the design of
complexes with potential application as radiopharma-
* Corresponding author. Tel.: +55-56224514; fax: +55-5616
2217.
E-mail address: damor@servidor.unam.mx (D. Morales-Morales).
1 (phenyl-2-thiol)diisopropylphosphine.
2 bis(phenyl-2-thiol)phenylphosphine.
3 bis(ethyl-2-thiol)phenylphosphine.
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(02)00695-3

102
D. Morales-Morales et al. / Inorganica Chimica Acta 332 (2002) 101–107
2. Experimental
vacuum and the reddish–brown residue recrystallised
from a double layer solvent system of CH2Cl2/MeOH.
Yield 90 mg (85%). IR (nujol): w=2049 cm−1
2.1. Materials and methods
1
[w(RhꢀH)], 1979 cm−1 [w(CꢁO)]. H NMR (CDCl3, 200
MHz): l=8.6–6.6 (m, 28H, arom.). 31P NMR (CDCl3,
81.0 MHz): Not observed. Elem. Anal. C37H29OP2S2Rh
(718.61): calcd. C 61.8, H 4.1. Found C 61.8, H 4.0%.
Mol. mass 689 (M+ꢀHꢀCO).
Unless stated otherwise, all reactions were carried out
under an atmosphere of dinitrogen using conventional
Schlenk glassware, solvents were dried using established
procedures and distilled under dinitrogen immediately
prior to use. The IR spectra were recorded on a
Perkin–Elmer Paragon FT IR spectrometer as nujol
2.4. [Rh(H)(ePS2)(CO)(PPh3)] (3)
1
mulls. The H NMR spectra were recorded on a JEOL
To a solution of trans-[RhF(CO)(PPh3)2] (100 mg,
0.15 mmol) in methanol (25 cm3) precooled to −78 °C
(dry-ice/acetone bath) was added 1 equiv. of the phos-
phino-dithiol ePS2H2. The solution was stirred for 10
min at this temperature and then the heating bath was
removed to allow the solution to reach room tempera-
ture (r.t.). The volume was then reduced in vacuum and
the residue redisolved in the minimum volume of
CH2Cl2 and precipitated with n-pentane. Yield 74 mg
(80%). IR (nujol): w=2057 cm−1 [w(RhꢀH)], 1965
EX270 spectrometer. Chemical shifts are reported in
ppm down field of TMS using the solvent (CDCl3,
l=7.27) as internal standard. 31P NMR spectra were
recorded with complete proton decoupling and are
reported in ppm using 85% H3PO4 as external standard.
Elemental analyses were determined on a Perkin–Elmer
240 at the University of Essex, UK. Positive-ion FAB
mass spectra were recorded on a JEOL SX102 mass
spectrometer operated at an accelerating voltage of 10
kV. Samples were desorbed from a nitrobenzyl alcohol
(NOBA) matrix using 3 keV xenon atoms. Mass mea-
surements in FAB are performed at a resolution of
3000 using magnetic field scans and the matrix ions as
the reference material or, alternatively, by electric field
scans with the sample peak bracketed by two
(polyethylene glycol or cesium iodide) reference ions.
The IrCl3 was obtained from Aldrich Chemical Co. and
used without further purification. The proligand
priPSH was synthesised in analogous manner to that of
the known phosphino-thiol phPSH [12]. The proligands
phPS2H2 [12] and ePS2H2 [11b] and the starting materi-
als trans-[MF(CO)(PPh3)2] (M=Rh and Ir) [13] were
prepared according to published procedures.
1
cm−1 [w(CꢁO)]. H NMR (CDCl3, 200 MHz): l=8.0–
7.0 (m, 20H, arom.), 3.0–0.9 (m, 8H, CH2). 31P NMR
(CDCl3, 81.0 MHz): Not observed. Elem. Anal.
C29H29OP2S2Rh (622.52): calcd. C 56.0, H 4.7. Found
C 56.3, H 4.6%. Mol. mass 593 (M+ꢀHꢀCO).
2.5. [Ir(H)(phPS2)(CO)(PPh3)] (4)
The title complex was synthesised in a similar man-
ner to that of complex (2). By reacting trans-[Ir-
F(CO)(PPh3)2] (100 mg, 0.13 mmol) with the
phosphino-dithiol phPS2H2 in equivalent amounts. The
product was recrystallised from a double layer solvent
system of CH2Cl2/MeOH. Yield 95 mg (90%). IR (nu-
jol): w=2100 cm−1 [w(RhꢀH)], 2026 cm−1 [w(CꢁO)].
1H NMR (CDCl3, 200 MHz): l=7.7–6.7 (m, 28H,
2.2. [Ir(priPS)3] (1)
2
arom.), −11.36 (t, 1H, IrꢀH, JHꢀP=11.74 Hz). 31P
A methanol solution consisting of IrCl3 (100 mg, 12
mmol) and the phosphino-thiol priPSH (3 equiv.), in
the presence of NEt3 as base, were heated under reflux
for 2 h, after this time the yellow precipitate formed
was filtered and washed with cold ether. Yield 218 mg
2
NMR (CDCl3, 81.0 MHz): l=58.09 (d, JPꢀP=297.1
Hz), 4.36 (d, 2JPꢀP=297.1 Hz). Elem. Anal.
C37H29OP2S2Ir (807.92): calcd. C 55.0, H 3.6. Found C
55.0, H 3.7%. Mol. mass 779 (M+ꢀHꢀCO).
1
(75%). H NMR (CDCl3, 200 MHz): l=7.6–6.7 (m,
2.6. [Ir(H)(ePS2)(CO)(PPh3)] (5)
12H, arom.), 3.35–3.15 (m, br, 2H, CH), 3.1–2.85 (m,
br, 2H, CH), 2.7–2.3 (m, br, 2H, CH). 31P NMR
(CDCl3, 81.0 MHz): l=15.88 (s, br), 9.80 (s, br), 7.94
(s, br). Elem. Anal. C36H54P3S3Ir (868.15): calcd. C
49.8, H 6.2. Found C 49.8, H 6.3%. Mol. mass 868
(M+).
Complex (5) was synthesised in an analogous manner
to that of complex (2). By reacting trans-[Ir-
F(CO)(PPh3)2] (100 mg, 0.13 mmol) and the phosphino-
dithiol ePS2H2 in equivalent amounts. The product was
redisolved in the minimum volume of CH2Cl2 and
precipitated with n-pentane. Yield 70 mg (75%). 1H
NMR (CDCl3, 200 MHz): l=8.0–6.9 (m, 20H,
arom.), 3.0–0.8 (m, 8H, CH2). 31P NMR (CDCl3, 81.0
MHz): l=48.50 (d, 2JPꢀP=169.8 Hz), 43.15 (d,
2JPꢀP=169.8 Hz). Elem. Anal. C29H29OP2S2Ir (711.84):
calcd. C 48.9, H 4.1. Found C 48.7, H 4.3%. Mol. mass
711 (M+ꢀH).
2.3. [Rh(H)(phPS2)(CO)(PPh3)] (2)
To a solution of trans-[RhF(CO)(PPh3)2] (100 mg,
0.15 mmol) in toluene (25 cm3) 1 equiv. of the phos-
phino-dithiol phPS2H2 was added. The solution was
stirred for 45 min. The volume was then reduced in

D. Morales-Morales et al. / Inorganica Chimica Acta 332 (2002) 101–107
103
2.7. Data Collection and refinement for [Ir(priPS)3] (1)
and [Rh(H)(phPS2)(CO)(PPh3)] (2).
Table 2
i
,
Selected bond lengths (A) and angles (°) for [Ir(pr PS)3] (1)
,
Bond lengths (A)
Intensity data were collected (graphite-monochro-
IrꢀP(1)
IrꢀS(1)
IrꢀP(2)
IrꢀS(2)
IrꢀP(3)
IrꢀS(3)
2.3484(8)
2.3523(7)
2.3619(7)
2.3805(7)
2.3908(7)
2.4157(7)
,
mated Mo Ka radiation, u=0.71069 A) on an Enraf–
Nonius CAD4 diffractometer [14] for complex (1) and at
EPSRC service, Cardiff, UK on a Delft-Instruments
FAST-TV Area detector diffractometer for (2). In both
cases the data were corrected for Lorentz and polarisa-
tion factors and absorption correction was applied us-
ing c-scans of nine reflections. The structures were
solved via direct methods [15] and refined by Fo2 by
full-matrix least squares [16]. All non-hydrogen atoms
were anisotropic and the hydride atom was not consid-
ered in the refinement (complex 2). The hydrogen
atoms (except hydride atom in complex 2) were in-
cluded in idealised positions with Uiso free to refine.
Sources of scattering factors were as in reference [16].
The details of the structure determination are given in
Bond angles (°)
P(1)ꢀIrꢀS(1)
P(1)ꢀIrꢀP(2)
S(1)ꢀIrꢀP(2)
P(1)ꢀIrꢀS(2)
S(1)ꢀIrꢀS(2)
P(2)ꢀIrꢀS(2)
P(1)ꢀIrꢀP(3)
S(1)ꢀIrꢀP(3)
P(2)ꢀIrꢀP(3)
S(2)ꢀIrꢀP(3)
P(1)ꢀIrꢀS(3)
S(1)ꢀIrꢀS(3)
P(2)ꢀIrꢀS(3)
S(2)ꢀIrꢀS(3)
P(3)ꢀIrꢀS(3)
87.63(3)
96.22(3)
93.85(3)
93.59(3)
176.80(2)
83.07(3)
94.98(3)
86.32(3)
168.80(3)
96.52(3)
170.38(3)
83.02(3)
86.64(3)
95.88(3)
82.26(2)
,
Table 1 and selected bond lengths (A) and angles (°) in
Table 2 (complex 1). The numbering of the atoms are
Table 1
Summary of crystal structure data for complexes 1 and 2
1
2
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C
868.08
293(2)
monoclinic
P21/c
36H54IrP3S3
C37H28OP2RhS2
717.56
293(2)
monoclinic
P21/c
,
a (A)
17.775(1)
11.886(1)
19.060(2)
90
115.84(1)
90
13.258(7)
13.614(4)
18.383(4)
90
101.430(2)
90
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
3624.2(5)
4
3252(2)
4
Z
q Range (lattice) (°)
8.29BqB12.8
1.591
4.014
1.87BqB25.07
1.460
0.781
Dcalc (g cm−3
)
Fig. 1. An ORTEP representation of the structure of [Ir(priPS)3] (1) at
50% of probability showing the atom labelling scheme.
v (mm−1
F(000)
)
1760
1460
Crystal colour
Yellow
Prism
Red
Prism
shown in Fig. 1 (complex 1) and Fig. 2 (complex 2)
(ORTEP) [17].
Crystal description
Crystal size (mm)
Reflections measured
Independent reflections
Observed reflections
[I\2|(I)]
0.35×0.30×0.14 0.14×0.14×0.14
7161
6954
5869
12 289
4805
1504
3. Results and discussion
h, k, l Ranges
−21–19, 0–14,
0–21
−15–9, −15–15,
−21–21
4805/0/388
0.0445
0.0837
0.604 and
−0.335
3.1. Synthesis and characterisation of [Ir(priPS)3] (1)
The reaction between IrCl3 and priPSH in refluxing
Data/restraints/parameters 5869/0/400
R1
wR2
0.0205
0.0340
0.478 and
−0.445
a
Largest difference peak
and hole (e A
methanol in
a 1:3 molar ratio yields complex
−3
,
)
[Ir(priPS)3] (1) as a bright yellow powder in good yield.
Complex (1) is stable both in solution and in the solid
state. The infrared and multinuclear NMR experiments
performed confirm the proposed formulation. FAB
Details in common: qmax 25°, weighting schemes w=1/[|2(Fo2)+
(0.0179P)2+0.0000P] where P=(Fo2+2Fc2)/3.
a R1=ꢀFo−Fcꢀ/ꢀFoꢀ, wR2=[w((Fo)2−(Fc)2)2/w(Fo)2]1/2
.

104
D. Morales-Morales et al. / Inorganica Chimica Acta 332 (2002) 101–107
Mass Spectrometry (FAB MS) and elemental analysis
results were also consistent with the proposed formula-
tion. Complex (1) is soluble in most of the common
solvents but insoluble in methanol, pentane and di-
ethylether. The infrared spectrum of (1) shows a group
of absorptions at 2872–3093 and 1416–1470 cm−1
assigned, respectively, to the stretching and deforma-
tion vibration modes of the isopropyl groups in the
molecule. Additional bands at 701–738 and 1548–1574
cm−1 are due to the stretching vibrations of the aro-
matic rings. The 1H NMR exhibits a group of signals in
the usual area for the aromatic protons, additional
signals at 2.3–3.2 (CH) and 0.8–1.9 ppm (CH3) are
assigned to the protons in the isopropyl groups. The
signals observed between 0.8 and 1.9 ppm can be
separated in two groups, one consisting of signals at
0.8–1.1 and 1.7–1.9 ppm and the other of multiplets at
1.2–1.4 and 1.4–1.65 ppm. The ratio between these two
groups of signals is 1:2, which is in agreement with a
mer configuration. In terms of symmetry it is evident
that there is no plane of symmetry since four different
types of methyl groups are observed. However, accord-
ing to the complexity of the signals there is some free
rotation about the PꢀC bond. The 31P NMR only
shows three groups of broad signals at 15.88, 9.80 and
7.94 ppm. Still, these signals can be assigned to three
non-equivalent phosphorus nuclei, as expected for the
structure suggested. Assignment of these broad signals
can be done analogously with that of the previously
reported compound [Ir(phPS)3] [18], where the two
signals at higher field are assigned to the trans-P atoms
and the one at lower field to the phosphorus trans to
sulfur. The FAB MS shows the molecular ion [M]+ at
868 m/z, another peak at 643 m/z, due to the loss of
one priPS− ligand and the most intense peak at 225
m/z corresponding to the molecular weight for one
molecule of ligand [priPS]+.
3.2. X-ray crystal structure of [Ir(priPS)3] (1)
Crystals of complex (1) were obtained from a double
layer solvent system of CH2Cl2/MeOH as bright yellow
prisms. The X-ray crystal structure (Fig. 1) shows the Ir
to be in a slightly distorted octahedral arrangement.
The three P and S atoms occupy meridional sites. The
central IrꢀP(1) bond is shorter and the central IrꢀS(3)
bond [trans to IrꢀP(1)] is longer than others of the same
type, suggesting an enhanced trans influence of the
central IrꢀP(1) bonds on the central IrꢀS(3) bonds. The
same is not true for the d4 complexes of [Tc(phPS)3]
and [Re(phPS)3] [19]. In other respects the bond dis-
tances are normal and the angles in the coordination
octahedron are all close to 90 or 180°. The chelation of
the PS ring systems varies slightly and this can be
attributed to the fact that the Ir atom lies out of the
least-square planes of the PꢀCꢀCꢀS units by different
amounts. This is similar, but not as marked as, the
differences found in the structures of [Tc(phPS)3] and
[Re(phPS)3] analogues. The chelated rings are distin-
guishable, and may be classified as (c, e), (e, c) and (e,
e) according to whether the P and the S atoms are
central (c) or end-positioned (e) in the mer configura-
tion. The (e, c) chelate ring shows both the smallest bite
angle at Ir and the longest IrꢀP(3) and IrꢀS(3) distances
within one chelate ring, and the greatest displacement
of the chelate ring of Ir. As is the case in [Ir(phPS)3] it
has to be assumed that the ligands (c, e) and (e, e) are
affected either by steric or by very sensitive electronic
factors. In the [Tc(phPS)3] and [Re(phPS)3] complexes
the (c, e) ligands show the longest MꢀP and MꢀS
distances and the smallest bite angles. This suggests
strongly that the electron configuration of the metal (d4
for Tc and Re, d6 for Ir) plays a significant role in the
details of the geometry. In the case of (1), as there was
no variation of the geometry after changing phenyls by
isopropyl on the phosphorus it has to be concluded that
electronic rather than steric effects govern the details of
the geometry.
3.3. Synthesis and characterisation of
[Rh(H)(phPS2)(CO)(PPh3)] (2) and
[Rh(H)(ePS2)(CO)(PPh3)] (3)
Reaction of equivalent amounts of trans-
[RhF(CO)(PPh3)2] and the proligand (phPS2H2) in tolu-
ene, yield complex 2 as a brown–reddish powder, in
good yield. Similar reaction with the proligand ePS2H2
at low temperature (−78 °C) affords complex 3 as a
yellow powder. For both complexes elemental analysis,
Fig. 2. An ORTEP representation of the structure of [Rh(H)(phPS2)-
(CO)(PPh3)] (2) at 50% of probability showing the atom labelling
scheme.

D. Morales-Morales et al. / Inorganica Chimica Acta 332 (2002) 101–107
105
observation of peaks at 30.7 and −4.0 ppm (OPPh3
and PPh3) in the 31P NMR the simplest explanation is
that there is substantial decomposition to Rh(III) or
paramagnetic Rh(II) species. Same behaviour is ob-
served for complex 3 with broad signals at 37.0–50.0
ppm in the 31P NMR spectrum. An additional signal at
−4.1 ppm corresponding to free PPh3 complement the
theory of a decomposition process in solution. The
FAB MS shows a strong peak at 689 m/z which
corresponds to the fragment [M−(H+CO)]+. An-
other peak due to the loss of a PPh3 molecule is
observed at 427 m/z, in agreement with the proposed
formulations. The proposed mechanism of formation
and proposed structure for complex 2 is shown in
Scheme 2.
Scheme 1. Proposed interconversion mechanism in solution for the
complex [Rh(H)(phPS2)(CO)(PPh3)] (2).
3.4. X-ray crystal structure of
[Rh(H)(phPS2)(CO)(PPh3)] (2)
Crystals for X-ray crystal structure experiments were
obtained from a double layer solvent system of CH2Cl2/
MeOH as red prisms. The crystals were of relatively
poor quality, and although, the coordination about the
metal was established unequivocally, it is not appropri-
ate to discuss bond lengths or angles. The structure of
2 (Fig. 2) can be described as a distorted square pyra-
mid where the vacant site is presumed occupied by the
hydride ligand. The coordination sphere is completed
by CO, PPh3, and the tridentate ligand phPS2.
Scheme 2. Proposed mechanism for the formation of complex
[Rh(H)(phPS2)(CO)(PPh3)] (2).
3.5. Synthesis and characterisation of
[Ir(H)(phPS2)(CO)(PPh3)] (4) and
[Ir(H)(ePS2)(CO)(PPh3)] (5)
IR and NMR spectroscopic and FAB MS experiments
were performed to confirm the proposed formulations.
Complexes 2 and 3 are stable in the solid state in air,
but decompose in solution under aerobic conditions.
The IR spectra show absorptions at 2049 cm−1 for 2
and 2057 cm−1 for 3, which are assigned to the hydride
vibrations RhꢀH. Absorptions corresponding the CꢁO
stretching vibrations are observed at 1979 and 1965
cm−1 for complexes 2 and 3, respectively. Other ab-
sorptions at 690–740 and 1570 cm−1 are due to the
In analogous procedure to that used to prepare com-
plex 2, compounds 4 and 5 were obtained. The IR and
1H, 31P NMR spectroscopic studies as well as elemental
analysis and FAB MS were performed to confirm the
proposed formulations. Both complexes are stable in
the solid state and in solution. The IR spectra of
complexes 4 and 5 show weak absorptions due to the
presence of hydride ligands at 2100 and 2119 cm−1
,
1
aromatic rings. For both complexes H NMR exhibits
respectively. Other strong absorptions observed at 2026
or at 2016 cm−1 correspond to the CꢁO stretching
vibrations. Additional signals due to the aromatic rings
are observed at 668–813 and 1572 cm−1. The 1H NMR
of 4 shows signals for the aromatic rings between 6.7
and 7.7 ppm and a triplet at high field due to the
hydride, with a PꢀH coupling constant value consistent
with a cis arrangement of the hydride relative to the P
donors (2JHꢀP=11.74 Hz). For complex 5, the 1H
NMR spectrum exhibits a multiplet at 6.9–8.0 ppm for
the aromatic protons, additional series of broad signals
at 0.8–3.0 ppm assigned to the CH2 groups. In this case
no signal for a hydride was observed. The 31P NMR of
complex 4 shows two doublets at 58.09 and 4.36 ppm,
multiplets at 6.6–8.6 ppm due to the aromatic protons,
and for complex 3 an additional group of broad signals
at 0.9 and 3.0 ppm assigned to the methylene groups is
observed. In both cases, no signals due to hydride were
detected. This may be due to a fast decomposition
process or to a fluxional behaviour where one of the S
groups originally bonded to the metal centre is con-
verted to free (or bond) SH by a hydride shift, with or
without loss of phosphine 11b (Scheme 1). NMR exper-
iments carried out at temperatures as low as −60 °C,
still show broad signals in both the 1H and the 31P
spectra, suggesting that if there is any fluxional be-
haviour it should be very fast. However, in view of the

106
D. Morales-Morales et al. / Inorganica Chimica Acta 332 (2002) 101–107
both with a coupling constant 2JPꢀP=297.1 Hz. The 31
NMR spectrum of 5 shows the same pattern as that of
P
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4, with two doublets being located at 48.50 and 43.15
2
ppm having equivalent coupling constants of JPꢀP
=
169.8 Hz. In both cases this pattern is in accordance
with a complex with two non-equivalent mutually trans
phosphorus nuclei. The FAB MS of complex 4 shows
the molecular ion at 778.8 m/z [M+ꢀ(CO+H)]. An-
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at 516.8 m/z. For complex 5 the FAB MS shows peaks
at 711 and 420 m/z assigned respectively to [MꢀH]+
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(b) N. Froelich, P.B. Hitchcock, J. Hu, M.F. Lappert, J.R.
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Chem. Eur. J. 6 (2000) 636;
Supplementary data for complexes 1 and 2 have been
deposited at the Cambridge Crystallographic Data Cen-
tre. Copies of this information are available free of
charge on request from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (Fax: +44-1223-
336033; e-mail deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk) quoting the deposition numbers
CCDC 150 082 and 150 083, respectively.
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(b) P. Braunstein, F. Naud, Angew. Chem., Int. Ed. Engl. 40
(2001) 680.
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Met. Chem. 17 (1992) 364;
Acknowledgements
D.M.-M. would like to thank Dr Francisca
Momblona at the University of Murcia, Spain for help
in running the VT NMR experiments and the DGAPA-
UNAM (IN116001) for financial support.
(b) J.R. Dilworth, A.J. Hutson, J. Zubieta, Q. Chen, Trans. Met.
Chem. 19 (1994) 61;
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(g) K. Ortner, L. Hilditch, J.R. Dilworth, U. Abram, Inorg.
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