Rhodium and iridium complexes with thiolate and tertiary phosphine ligands. the synthesis

Article abstract of DOI:10.1039/b005588n

Reaction of [MF(CO)(PPh₃)₂] (M = Rh or Ir) with bulky aromatic thiols ArSH gave the binuclear complexes [M₂(u-SAr)₂(CO)₂(PPh₃)₂] (M = Rh, SAr = SC₆H₂Pr₃¹2,4,6 or SC6H3Me2-2,6) and mononuclear complies [M(SAr)(CO)(PPh3)J (M = Rh or Ir, SAr = SC₆H₃Cl₂-2,6 or SC6H4SiPh3-2; M = Ir, SAr = SC6H2Pr^l3-2,4,6 or SC₆H}Me₂-2,6. The crystal structure of [Rh₂(u-SC₆H₃Pr'3-2,4,6)2(CO) ₂(PPh₃)₂] showed a binuclear thiolate bridged core while that of [Ir(SC₆H₃Cl₂-2,6)(CO)(PPh_{3 2}J revealed a conventional square planar geometry with Irans PPh₃ ligands. Three rhodium complexes were shown to be efficient catalysts for the hydroformylation of hept-1-ene under mild conditions with good selectivity for linear aldehyde for SAr = SC6H4SiPh3-2. Reaction of [MF(CO)(PPh₃)₂] with phosphinothiolate proligands PSH gave the monomeric complexes [M(PS)(CO)(PPh₃)₂] (M = Rh or Ir; PS = SC6H₄PPh₂-2 or S(CH2)₃PPh₂; M = Rh, PS = SCH2CH₂PPh₂ or SCH(CH3)CH2PPh2). The complex [Rh(SC6H4PPh22)(CO)(PPh3)] reacted reversibly with protons (HBF4) to give the dimeric dication [Rh₂(u-SC₆H₄PPh₂-2) ₂(CO)₂-(PPh₃)₂]²⁺, shown by a crystal structure be a thiolate bridged dimer with an Rh-Rh bond and pseudo-octahedral geometry about each Rh^III. Electrophilic attack by [Me3O][BF4] on [Rh(SC₆H₄PPh2-2)(CO)(PPh3)] occurred at sulfur to give [Rh(MeSC₆H₄PPh₂-2)(CO)(PPh³)] ⁺ and excess of Mel gave [Rh2I6(MeSC6H4PPh2-2)2], with octahedral Rh"1 linked by a double iodide bridge. Attack at sulfur also occurred in [Rh(SC6H4PPh2-2)(CO)(PPh3)] with I(CH2)3I and ICH2CO2H to give [Rh(2-Ph2PC6H4SCH2CH2CH2)(CO)(PPh3)] and [RhI2(2-Ph2PC6H4SCH2CO2)(PPh3)] respectively. The complex [RhI3(CO)(PPh3)2] was a by-product and shown by a crystal structure to have a pseudooctahedral structure with trans-PPhj ligands. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b005588n

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Rhodium and iridium complexes with thiolate and tertiary
phosphine ligands. The synthesis and structures of trans-
[Ir(SC6H3Cl2-2,6)(CO)(PPh3)2], [Rh2(ꢀ-SC6H3Pri3-2,4,6)2(CO)2-
(PPh3)2], [Rh2H2(ꢀ-SC6H4PPh2-2)2(CO)2(PPh3)2][BF4]2, and
[Rh2I6(MeSC6H4PPh2-2)2]
Jonathan R. Dilworth,* David Morales and Yifan Zheng
Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford,
UK OX1 3QR
Received 18th February 2000, Accepted 19th July 2000
Published on the Web 14th August 2000
Reaction of [MF(CO)(PPh3)2] (M = Rh or Ir) with bulky aromatic thiols ArSH gave the binuclear complexes
[M2(µ-SAr)2(CO)2(PPh3)2] (M = Rh, SAr = SC6H2Pri3-2,4,6 or SC6H3Me2-2,6) and mononuclear complexes
[M(SAr)(CO)(PPh3)2] (M = Rh or Ir, SAr = SC6H3Cl2-2,6 or SC6H4SiPh3-2; M = Ir, SAr = SC6H2Pri3-2,4,6 or
SC6H3Me2-2,6. The crystal structure of [Rh2(µ-SC6H3Pri3-2,4,6)2(CO)2(PPh3)2] showed a binuclear thiolate bridged
core while that of [Ir(SC6H3Cl2-2,6)(CO)(PPh3)2] revealed a conventional square planar geometry with trans PPh3
ligands. Three rhodium complexes were shown to be efficient catalysts for the hydroformylation of hept-1-ene under
mild conditions with good selectivity for linear aldehyde for SAr = SC6H4SiPh3-2. Reaction of [MF(CO)(PPh3)2]
with phosphinothiolate proligands PSH gave the monomeric complexes [M(PS)(CO)(PPh3)2] (M = Rh or Ir; PS = SC6-
H4PPh2-2 or S(CH2)3PPh2; M = Rh, PS = SCH2CH2PPh2 or SCH(CH3)CH2PPh2). The complex [Rh(SC6H4PPh2-
2)(CO)(PPh3)] reacted reversibly with protons (HBF4) to give the dimeric dication [Rh2(µ-SC6H4PPh2-2)2(CO)2-
(PPh3)2]2ϩ, shown by a crystal structure be a thiolate bridged dimer with an Rh–Rh bond and pseudo-octahedral
geometry about each RhIII. Electrophilic attack by [Me3O][BF4] on [Rh(SC6H4PPh2-2)(CO)(PPh3)] occurred at sulfur
to give [Rh(MeSC6H4PPh2-2)(CO)(PPh3)]ϩ and excess of MeI gave [Rh2I6(MeSC6H4PPh2-2)2], with octahedral RhIII
linked by a double iodide bridge. Attack at sulfur also occurred in [Rh(SC6H4PPh2-2)(CO)(PPh3)] with I(CH2)3I
and ICH2CO2H to give [Rh(2-Ph2PC6H4SCH2CH2CH2)(CO)(PPh3)] and [RhI2(2-Ph2PC6H4SCH2CO2)(PPh3)]
respectively. The complex [RhI3(CO)(PPh3)2] was a by-product and shown by a crystal structure to have a pseudo-
octahedral structure with trans-PPh3 ligands.
ium() complex [IrH(Ph2PC6H4S)2(CO)].8 The binucleating
phosphinothiol proligand HSC6H3(CH2PPh2)2-2,6 (PSHP)
Introduction
Although thiolate complexes of RhI and IrI with tertiary phos-
phine co-ligands are well documented, the majority are poly-
nuclear with bridging thiolates1 and examples of mononuclear
complexes are rare. A wide range of binuclear complexes
containing simple di-µ-thiolate bridges are known, and [Ir2-
(µ-SCMe3)2(CO)2(P(OMe)3)2] is typical. The tridentate trithiol
CH3C(CH2SH)3 forms trinuclear thiolate bridged complexes
of the type [CH3C{CH2SRh(CO)(P(OMe)3)}3].2 In addition
many complexes with mixed bridging ligand systems are
also known and exemplified by [Ir2(µ-pz)(µ-SCMe3)(CO)2-
(P(OMe3)2)2].3
The chemistry of rhodium and iridium complexes with
hybrid phosphorus–sulfur donor chelating ligands is by com-
parison less well explored.4 However such ligands appear to
bind very effectively to platinum group metals, and complexes
with RhI have been shown to be robust and efficient catalysts
for the carbonylation of methanol.5,6 The thiolate-bridged
dimeric complexes [Rh2(PS)2(CO)2] (PS = Ph2PCH2CH2S, Ph2-
PC6H10S or Ph2PC6H4S-2) and [M2(Ph2PC6H4S-2)(COD)2]
(M = Rh or Ir; COD = cyclooctadiene) have been known
for some time.5 Recently the synthesis of the monomeric
complexes [M(Ph2PC6H4S-2)(CO)(PPh3)] (M = Rh or Ir)
was also reported,7 together with the chemistry of the alkoxide
analogues. The PS ligands with aliphatic backbones behave dif-
ferently, and reaction of [IrCl(CO)(PPh3)2] with 2 equivalents
of Ph2PCH2CH2SH in the presence of base generated the irid-
reacts with [MCl(CO)(PPh3)2] (M = Rh or Ir) to give [Rh2Cl-
(PSP)(CO)2] (with half an equivalent of PSHP) and [Ir2Cl2-
(PSP)2(µ-CO)]9 (with one equivalent).
The oxidative addition chemistry of dinuclear thiolate
bridged complexes of rhodium and iridium has been studied in
some detail. Depending on the binuclear complex used as the
starting point, bifunctional agents such as diiodomethane
react to give complexes with triple bridges comprising a
methylene group and two thiolate sulfurs or a methylene with
one bridging thiolate sulfur and another bridging ligand such as
pyrazole.10,11 Dimethyl acetylene dicarboxylate oxidatively adds
to give species such as [Ir (µ-pz)(µ-SBut)(µ-MeO CC᎐CCO -
᎐
2
2
2
Me)(CO)2(P(OMe)3)2] with a triple bridge including the
acetylene molecule, bonded as a dimetallated olefin.2 In con-
trast, tetracyanoethylene adds in asymmetric fashion to [Ir2-
(µ-SBut)2(CO)2(PR3)2] (R=Me, Ph or OMe) to give the com-
plexes [(RP3)2(OC)Ir(µ-SBut)2Ir(CO)(C2(CN)4)].12 Significant
rearrangement also occurs on addition of hexafluoro-2-butyne
to [Ir2(µ-SBut)2(CO)4] to give trinuclear ‘crown-like’ complexes
of the type [Ir3(µ-SBut)3(µ-C4F6)(CO)6].13
In view of the comparative paucity of data on mononuclear
complexes we have investigated the synthesis and reactivities of
complexes of the type [Ir(SAr)(CO)(PPh3)2] (M = Rh or Ir;
Ar = 2,6-disubstituted arene) and [Rh(Ph2PC6H4S-2)(CO)-
(PPh3)]. The presence of thiolate ligands in such complexes
introduces the possibility of chemistry occurring at sulfur and
DOI: 10.1039/b005588n
J. Chem. Soc., Dalton Trans., 2000, 3007–3015
This journal is © The Royal Society of Chemistry 2000
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Table 1 Complexes of rhodium() and iridium() with bulky aromatic thiolates
Elemental
analysis (%)a
NMR (δ, J/Hz)c
Complex
Colour
Yellow
C
H
ν(CO)b
31P
1H
MSd (m/z)
1 trans-[Rh(DCBT)(CO)(PPh3)2]
60.0 (60.0) 3.9 (4.0) 1965
70.8 (71.6) 4.8 (4.8) 1978
60.2 (60.9) 3.9 (4.0) 1966
32.2 (d),
JP-Rh = 133.4
30.50 (d),
JP-Rh = 133.6
34.2 (d),
JP-Rh = 156.7
7.1–7.8 (m) (33 H, aromatic)
6.8–7.8 (m) (49 H, aromatic)
804
(M Ϫ CO)ϩ
1022 (Mϩ)
2 trans-[Rh(TPSBT)(CO)(PPh3)2] Yellow
3 [Rh2(µ-DMBT)2(CO)2(PPh3)2]
Yellow
6.5–7.5 (m) (36 H, aromatic),
2.74(s) (6 H, CH3), 1.54(s)
(6 H, CH3)
1060 Mϩ
4 [Rh2(µ-TIPBT)2(CO)2(PPh3)2]
Yellow
64.5 (65.0) 6.0 (6.1) 1976
35.0 (d),
6.6–7.7 (m) (34 H, aromatic),
5.6 (m), 4.8 (m), 4.3 (m),
2.7 (m) (4 H, CH), 0.6–1.6 (m)
(36 H, CH3)
1229
1JP-Rh = 153.6
(M ϩ 1 Ϫ
CO)ϩ
5 trans-[Ir(DCBT)(CO)(PPh3)2]
Yellow
55.7 (56.9) 3.6 (3.6) 1946
20.8(s)
6.7–7.8 (m) (33 H, aromatic)
945
(M ϩ Na)ϩ
1111 (Mϩ)
853
6 trans-[Ir(TPSBT)(CO)(PPh3)2]
7 trans-[Ir(DMBT)(CO)(PPh3)2]
Yellow
Yellow
66.0 (65.9) 4.4 (4.4) 2004
63.7 (63.7) 4.4 (4.5) 2035
Ϫ3.4(s)
9.31(s)
6.4–7.7 (m) (49 H, aromatic)
6.8–7.9 (m) (33 H, aromatic),
2.3(s) (6 H, CH3)
6.8–7.9 (m) (32 H, aromatic),
2.6–3.7 (m) (3 H, CH), 0.6–14
(m) (18 H, CH3)
(M Ϫ CO)ϩ
951
8 trans-[Ir(TIPBT)(CO)(PPh3)2]
Yellow
61.2 (61.3) 4.4 (4.5) 2035
9.21(s)
(M Ϫ CO)ϩ
a Calculated values in parentheses. b As Nujol mulls, in cmϪ1 c In CDCl3 solution. d FAB mass spectra in 3-nitrobenzyl alcohol matrix.
.
Scheme 1 Synthesis of thiolate complexes of IrI and RhI.
disposition of the aromatic thiolate groups. In the dimeric
rhodium complex 3 the two thiolates are presumably equivalent
in the anti configuration (see structure of 4 below), but the Me
groups are inequivalent, and appear as two singlets. For the
rhodium complexes 1 and 2 the Rh–P coupling constants of ca.
134 Hz are consistent with a trans arrangement of the tertiary
phosphine ligands.
Fig. 1 Structures and abbreviations of aromatic thiol proligands.
we have explored the balance between electrophilic attack at the
metal and sulfur.
The crystal and molecular structure of [Rh2(ꢀ-TIPBT)2(CO)2-
(PPh3)2] 4
Results and discussion
Synthesis of complexes of sterically hindered thiolates
A ZORTEP14 representation of the structure appears in Fig. 2
and selected bond lengths and angles are shown in Table 2. The
two square planar rhodium() units are bridged by two
arenethiolate sulfurs with the arene groups adopting an anti
arrangement with respect to the Rh2S2 core. The observation of
only two singlets in the 1H NMR of the DMTB analogue sug-
gests free rotation about the C–S bond in solution. The Rh–S
distances are very similar to those observed for anti-[Rh2-
(µ-SBut)2(CO)2(PPh3)2]15 (2.357(1) and 2.391(6) Å) and [Rh2-
(µ-SPh)2(CO)2(PPh3)2]16 (2.375(7) and 2.400(7) Å). The slightly
longer Rh–S distances observed in 4 are ascribable to the steric
effects exerted by the 2,6-substituents in the arenethiolate
group. The Rh2S2 has a characteristic ‘butterfly’ configuration
and the Rh ؒ ؒ ؒ Rh distance of 3.522(1) Å indicates the absence
of a Rh–Rh bond.
Reaction of [RhCl(CO)(PPh3)2] with free thiols RSH gives
oxidation addition products and with sodium or lithium salts
complex mixtures can be formed. However [RhF(CO)(PPh3)2]
with bulky aromatic thiols in toluene gives the complexes
[M(SAr)(CO)(PPh3)2] (M = Rh, SAr = DCBT (1) or TPSBT
(2); M = Ir, SAr = DCBT (5), TPSBT (6), DMBT (7) or TIPBT
(8)) and [Rh2(µ-SAr)2(CO)2(PPh3)2] (SAr = TIPTB (4) or
DMBT (3)). The structures and abbreviations for the thiols are
summarised in Fig. 1, and the syntheses are summarised in
Scheme 1. The complexes were isolated as moderately air-stable
bright yellow solids, and analytical and spectroscopic data are
summarised in Table 1.
The spectroscopic properties of the monomeric complexes
were generally entirely consistent with a planar structure. Two
thiols DCBTH and TIPBTH gave dimeric complexes with Rh,
reflecting the greater steric constraints exerted by the 2,6-
isopropyl or 2,6-chloro substituents, which cause loss of a
triphenylphosphine ligand. The greater kinetic stability of
iridium leads to monomeric iridium() complexes as triphenyl-
phosphine is not lost. The 1H NMR of complex 7 indicates that
both Me groups are equivalent, indicating a symmetrical
The crystal and molecular structure of [Ir(DCBT)(CO)(PPh3)2]
5
A ZORTEP representation of the molecular structure of com-
plex 5 is shown in Fig. 3, and selected bond lengths and angles
are shown in Table 3. The geometry about iridium is slightly
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Table 2 Selected bond lengths (Å) and angles (Њ) for compound 4
Rh(1)–C
1.764(8)
2.266(2)
2.369(2)
2.415(2)
1.814(8)
2.267(2)
2.368(2)
2.448(2)
1.798(7)
S(2)–C(21)
P(1)–C(41)
P(1)–C(61)
P(1)–C(52)
P(2)–C(31)
P(2)–C(81)
P(2)–C(71)
C–O
1.803(7)
1.813(7)
1.813(8)
1.876(7)
1.812(7)
1.842(7)
1.851(8)
1.217(8)
1.150(9)
Rh(1)–P(1)
Rh(1)–S(1)
Rh(1)–S(2)
Rh(2)–C(0)
Rh(2)–P(2)
Rh(2)–S(1)
Rh(2)–S(2)
S(1)–C(11)
C(0)–O(0)
C–Rh(1)–P(1)
C–Rh(1)–S(1)
P(1)–Rh(1)–S(1)
C–Rh(1)–S(2)
P(1)–Rh(1)–S(2)
S(1)–Rh(1)–S(2)
C(0)–Rh(2)–P(2)
C(0)–Rh(2)–S(1)
P(2)–Rh(2)–S(1)
C(0)–Rh(2)–S(2)
92.1(2)
93.5(2)
169.90(7)
171.1(2)
94.03(7)
81.45(6)
89.9(2)
92.7(2)
170.69(7)
173.4(2)
P(2)–Rh(2)–S(2)
S(1)–Rh(2)–S(2)
C(11)–S(1)–Rh(1)
C(11)–S(1)–Rh(2)
Rh(1)–S(1)–Rh(2)
C(21)–S(2)–Rh(1)
C(21)–S(2)–Rh(2)
Rh(1)–S(2)–Rh(2)
O–C–Rh(1)
96.65(7)
80.76(6)
116.2(2)
114.1(2)
96.05(7)
119.1(2)
117.7(3)
92.81(6)
177.1(6)
177.3(8)
O(0)–C(0)–Rh(2)
Fig. 3 A ZORTEP representation of the structure of [Ir(DCBT)-
(CO)(PPh3)2] 5 showing the atom labelling scheme.
Table 3 Selected bond lengths (Å) and angles (Њ) for compound 5
Ir–C
Ir–P(2)
Ir–P(1)
Ir–S(3)
P(1)–C(21)
P(1)–C(11)
P(2)–C(51)
1.824(4)
2.3238(9)
2.3335(8)
2.3933(9)
1.828(3)
1.827(3)
1.824(3)
P(2)–C(41)
P(2)–C(61)
S(3)–C(71)
Cl(1)–C(72)
Cl(2)–C(76)
O–C
1.833(3)
1.835(3)
1.756(4)
1.737(5)
1.733(6)
1.153(5)
C–Ir–P(2)
C–Ir–P(1)
P(2)–Ir–P(1)
C–Ir–S(3)
92.25(11)
86.42(11)
174.31(3)
169.67(12)
P(2)–Ir–S(3)
P(1)–Ir–S(3)
O–C–Ir
85.66(3)
94.68(3)
177.0(3)
Fig. 4 Percentage conversion of olefin into linear aldehyde for the
hydroformylation of 1-heptene (70 ЊC, 5 bar forming gas) for a range of
rhodium() aromatic thiolate complexes.
Catalytic activity of rhodium thiolate complexes
The catalytic activity of binuclear complexes such as [Rh2-
(µ-SR)2(CO)2P2] (R = But or Me2NCH2CH2, P = tertiary phos-
phine), particularly for hydroformylation or aminomethylation,
has been explored in some detail.18–20 In situ IR experiments
showed the formation of mononuclear hydrides such as
[RhHP3] under hydroformylation conditions (80 ЊC, 5–30 bar).
Deuterioformylation experiments provided no evidence for
the involvement of binuclear species.21 Similar results were
obtained in water using sulfonated triphenylphosphine to con-
fer solubility.22 Generally conversion rates are reasonably high
and use of chiral diphosphines provides high regioselectivity
and medium to high enantiomeric excesses.23 Asymmetric
hydroformylation of styrene has also been achieved using
1,1Ј-binaphthalene-2,2Ј-dithiol complexes of RhI.24
Here both monomeric and dimeric rhodium complexes 1, 2
and 4 were tested for hydroformylation catalysis activity for
1-heptene, and the results are presented in Fig. 4. High
conversion rates are obtained under the mild conditions (70 ЊC,
5 bar forming gas) with reasonable to good regioselectivities for
formation of linear as opposed to branched aldehydes. Maxi-
mum selectivity for linear aldehyde was observed for complex 2
of the asymmetrically substituted thiol TPSBTH where the
single large Ph3Si group is clearly able to exert steric influence
on the reaction stereochemistry at the olefin insertion step.
There is no discernible difference in rate or selectivity between
the dimeric and monomeric complexes and in view of the
results obtained above it seems likely that both give rise to
monomeric intermediates. The overall conversion rates are
comparable with those for [RhCl(PPh3)3] and the selectivity to
linear aldehyde formation is approximately twice that for
Wilkinson’s complex. The strong dependence of conversion
yield and stereochemistry on the thiolate suggests that thiolate
Fig. 2 A ZORTEP representation of the structure of [Rh2(µ-TIPBT)2-
(CO)2(PPh3)2] 4 showing the atom labelling scheme. The tertiary phos-
phine phenyl groups are omitted for clarity.
distorted square planar with C–Ir–P(2) 92.25(11), C–Ir–P(1)
86.42(11)Њ, P(2)–Ir–S(3) 85.67(5)Њ and P(1)–Ir–S(3) 94.68(3).
The orientation of the DCBT ligand is such as to bring one Cl
substituent close to the metal with an Ir ؒ ؒ ؒ Cl(1) distance of
3.197(1) Å. This suggests weak donation of electron density of
the Cl lone pairs to the iridium, which may explain the lower
value for ν(CO) for this complex compared to those of the other
monomeric iridium() complexes. The Ir–S bond length of
2.393(2) Å is somewhat longer than that observed for other
monomeric thiolate complexes such as [Ir(η5-C5Me5)(SC6-
F4H)2].16 However the variations in ligands and oxidation states
make a precise comparison difficult.
J. Chem. Soc., Dalton Trans., 2000, 3007–3015
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Fig. 5 Structures and abbreviations for phosphinothiol proligands.
co-ordination may be retained in the active catalyst under the
conditions used, although involvement as a non-co-ordinated
anion cannot be excluded.
Synthesis of phosphinothiolate complexes
We describe here the convenient high yield (ca. 90%) syntheses
of complexes of the type [M(PS)(CO)(PPh3)2] 9–14 (M = Rh or
Ir; PS = PhPPS, ePPS, PrPPS; abbreviations and structures
summarised in Fig. 5) by direct reaction of [RhF(CO)(PPh3)2]
with PSH in toluene, Et3N being added for M = Ir. We also
describe oxidative addition reactions with a range of electro-
philes with the objective of establishing if electrophilic attack
occurred at sulfur or the metal and if replacement of chloride
by thiolate in [RhCl(CO)P2] (P = tertiary phosphine) type
complexes modified the chemistry.
Scheme 2 Summary of the synthesis and reactions of [Rh(Ph2PC6H4-
S-2)(CO)(PPh3)2] 9. (i) ArSH in toluene. (ii) I(CH2)3I in CH2Cl2. (iii)
Excess of ICH2CO2H in benzene. (iv) HBF4ؒEt2O in CH2Cl2. (v)
[MeO][BF4] in CH2Cl2. (vi) Excess of MeI in benzene. All reactions at
room temperature.
The comparative lability of the fluoride ligand in the com-
plexes [MF(CO)(PPh3)2] permits high yield syntheses of the
complexes [M(PS)(CO)(PPh3)2] by direct reaction with one
equivalent of the thiol. In our hands reaction of the chloro-
complexes with lithium or sodium salts of the phosphinothiol
gave mixtures and significantly lower yields of the required
product. The complexes 9 to 14 were isolated as moderately air-
stable yellow solids and analytical and spectroscopic data are
summarised in Table 4.
solution. The IR spectrum shows a single intense band at 2050
cm
Ϫ1 assigned to ν(CO) and a broad bond at around 1090 cmϪ1
due to the [BF4]Ϫ counter ion. The FAB mass spectrum
displays a peak at m/z = 687 due to [M]2ϩ and also peaks at
m/z = 1082 ([M Ϫ H Ϫ CO Ϫ PPh3]ϩ) and 658 ([M Ϫ 2CO]2ϩ).
Reaction of 17 with Et3N in methanol results in the quanti-
tative regeneration of complex 9, confirming an unusual
example of reversible, pH-dependent formation of a thiolate-
bridged metal–metal bond. However despite the clear evidence
for the presence of protons from the reaction with base, we were
unable to detect any 1
The IR spectra show strong absorptions in the range 1947–
1976 cmϪ1 assigned to ν(CO). It is at first sight somewhat sur-
prising that the CO stretching frequency is higher for the
complexes with PS ligands with ethylene or trimethylene back-
bones than for those with a phenyl group linking P and S
(PhPPS). This may be due to the saturated hydrogen backbones
conferring more flexibility on the ligand. A similar effect is
observed for [Ir(PrPPS)(CO)(PPh3)] 14 and [Ir(PhPPS)(CO)-
(PPh3)] 13, where ν(CO) is 50 cmϪ1 higher for the complex with
H NMR resonances attributable to metal
hydride in the range δ ϩ10 to Ϫ30. This may be due to a rapid
hydrogen exchange process between the metal and sulfur
sites, but the hydride resonances still could not be detected at
lower temperatures. It is also possible that they are obscured by
other intense peaks in the spectrum. The 31P NMR revealed
a complex second order spectrum which was consistent with the
solid state structure discussed below.
1
the trimethylene bridge. The H and 31P NMR spectra were in
accord with a square planar geometry of the complexes with
The formation of the dimeric cation 17 presumably occurs
via initial protonation at the metal to give [RhH(FBF3)-
(PhPPS)(CO)(PPh3)] followed by displacement of the weakly
bond [BF4]Ϫ anion by the thiolate sulfur of an adjacent mol-
ecule. A precedent is found in the complex [IrH(FBF3)-
Cl(CO)(PPh3)2] where a crystal structure confirmed the pres-
ence of an F-bound [BF4]Ϫ anion.25 Further support for the
possibility of bridging hydrides in 17 comes from protonation
of the complex [Ir2H2(SBut)2(CO)2(PPh3)2] that gave [Ir2H2-
(µ-H)(SBut)2(CO)2(PPh3)2]ϩ in which there is a single hydride
bridging between the two iridiums.26
trans phosphorus donors, as shown by X-ray crystallography.6
Syntheses of complexes of the type [IrH(PS)2(CO)]
(PS ؍ PhPPS 15 or PrPPS) 16
Reaction of [IrF(CO)(PPh3)2] with 2 equivalents of PhPPSH or
ePPSH in the presence of diethylamine as base gave the com-
plexes [IrH(PhPPS)2(CO)] 15 or [IrH(PrPPS)2(CO)] 16 in good
yield as pale yellow powders. Complex 15 was identical to that
prepared earlier from [IrCl(CO)(PPh3)2], and 16 is directly
analogous. Analytical and spectroscopic data for (Table 4) 16
are consistent with its formulation as an octahedral iridium()
complex.
The crystal stucture of [Rh2H2(phPPS)2(CO)2(PPh3)2]2؉ 17. A
ZORTEP representation of the molecular structure of complex
17 is shown in Fig. 6 and selected bond lengths and angles are
displayed in Table 5. The geometry about each Rh is distorted
octahedral (including the Rh–Rh bond) with each Rh atom
lying above the P,P,S,S plane. There are vacant sites approxi-
mately trans to P(2) and P(4) which could accommodate the
hydride ligands. The molecule is folded about the S–S vector to
give a butterfly type structure, and the Rh–Rh distance is
typical for a metal–metal single bond. The Rh–S distances for
the bridging thiolates are significantly different [Rh(1)–S(1)
2.309(2), Rh(2)–S(1) 2.376(2), Rh(1)–S(2) 2.412(2), Rh(2)–S(2)
Reactions of [Rh(PhPPS)(CO)(PPh3)] 9
Reactions of complex 9 with a range of electrophiles have been
investigated, and these are summarised in Scheme 2. The
reaction with HCl gave a complex, intractable mixture of
products that could not be separated. However with excess of
HBF4ؒOEt2 in dry CH2Cl2 at room temperature a near quanti-
tative yield was obtained of the deep purple dimeric cation
[Rh2H2(PhPPS)2(CO)2(PPh3)2]2ϩ 17 isolated as the [BF4]Ϫ salt.
The complex is moderately stable in air both as a solid and in
3010
J. Chem. Soc., Dalton Trans., 2000, 3007–3015

Table 4 Phosphinothiolate complexes of rhodium() and iridium()
Elemental
analysis (%)a
NMR (δ, J/Hz)c
ν(CO)b 31P
Complex
Colour
C
H
1H
MSd(m/z)
9 [Rh(PhPPS)(CO)(PPh3)]
10 [Rh(PrPPS)(CO)(PPh3)]
Pale yellow
Yellow orange
64.9 (64.7) 4.1 (4.3) 1962
60.1 (60.2) 5.4 (5.4) 1952
63.5 (dd), 33.4 (dd), JRh-P = 130.4, JP-P = 301.1
87.5 (dd), 32.8 (dd), JRh-P = 127.3, JP-P = 287.6
6.8–7.8 (m) (29 H, phenyl group)
687 (Mϩ)
6.8–7.8 (m) (19 H, aromatic), 2.5–2.7 (br) (2 H, CH), 653 (Mϩ)
1.37 (d), 1.31 (d), 1.20 (d), 1.14 (d) (12 H, CH3)
11 [Rh(ePPS)(CO)(PPh3)]
12 [Rh(e*PPS)(CO)(PPh3)]
Yellow
Yellow
62.1 (62.1) 4.5 (4.6) 1976
62.5 (62.5) 5.0 (4.9) 1951
6.8–8.4 (m) (25 H, aromatic), 2.2–3.7 (br) (4 H, CH2) 639 (Mϩ)
7.0–8.0 (m) (25 H, aromatic), 2.9–3.2 (m) (2 H, CH2), 653 (Mϩ)
2.4–2.7 (m) (1 H, CH), 1.3–1.5 (d) (3 H, CH3)
68.2 (dd), 59.9 (dd), JRh-P = 133.4, JP-P = 304.2
13 [Ir(PhPPS)(CO)(PPh3)]
14 [Ir(PrPPS)(CO)(PPh3)]
Yellow
Yellow
57.2 (57.3) 3.8 (3.8) 1947
52.5 (52.6) 4.6 (4.7) 1997
55.0 (d), 25.9 (d), JP-P = 303.1
53.1 (d), 6.84 (d), JP-P = 380.0
6.7–6.9 (m) (29 H, aromatic)
776 (Mϩ)
6.7–7.9 (m) (19 H, aromatic), 2.3–3.0 (br) (2 H, CH), 708 (Mϩ)
0.8–1.5 (m) (12 H, CH3)
15 [IR(H)(PhPPS)2(CO)]
Yellow
55.1 (55.0) 3.6 (3.6) 2026,
37.08 (d), 23.84 (d), 2JP-P = 307.2
6.7–8.0 (m) (28 H, aromatic), Ϫ11.29 (dd) (1 H, 778
ν(Ir–H)
hydride), 2JH-P = 8.85
(M Ϫ CO Ϫ H)ϩ
2098w
50.3 (50.3) 4.5 (4.5) 2018,
ν(Ir–H)
16 [Ir(H)(PrPPS)2(CO)]
Yellow
Ϫ28.3(s)
7.2–8.2 (m) (20 H, aromatic), 2.0–3.9 (m) (12 H, 740 (Mϩ)
CH2), Ϫ11.6 (d) (1 H, hydride, JP-H = 11.2)
2112w
17 [Rh2(PhPPS)2(CO)2(PPh3)2][BF4]2 Purple
56.2 (56.8) 3.9 (3.9) 2050
62.0 (d), 15.5 (d)
6.4–8.0 (m) (aromatic)
1082
(M Ϫ CO Ϫ
PPh3 Ϫ H)ϩ
701 (Mϩ)
18 [Rh(PhPPSMe)(CO)(PPh3)][BF4]
Purple
57.9 (57.9) 4.1 (4.1) 2014
61.8 (dd), 1JP-Rh = 115.2, 27.5 (dd), 1JP-Rh = 123.3, 6.5–8.0 (m) (29 H, aromatic), 1.8 (s) (3 H, SCH3)
2JP-P = 272.9
19 [Rh2(µ-I)2(I)4(PhPPSMe)2]
20 [RhI2(PhPPS(CH2)3)(CO)(PPh3)]
Deep red
Bright red
29.0 (28.8) 2.2 (2.2)
54.1 (54.3) 3.7 (3.6) 2062
70.5 (dd), 1JP-Rh = 115.2
6.7–8.2 (m) (20 H, aromatic), 1.8 (s) (3 H, CH3)
701 (Mϩ)
61.2 (dd), 1JP-Rh = 136.4, 25.8 (dd), 1JP-Rh = 121.2, 6.7–8.1 (m) (29 H, aromatic), 0.7–2.4 (m, br) (6 H, 730
2JP-P = 16.2
CH2)
(M Ϫ 2I)ϩ
21 [RhI2(PhPPSCH2CO2)(PPh3)]
22 trans-[RhI3(CO)(PPh3)2]
Deep red
46.9 (47.0) 3.3 (3.3) 1652
43.0 (42.9) 2.9 (2.9) 2082
48.2 (dd), 4.9 (dd), 2JP-P = 545.7
6.8–7.5 (m) (29 H, aromatic), 2.75 (d) (1 H, CH2), 971 (Mϩ)
2.20 (d) (1 H, CH2), 2JH-H = 17.3
Deep orange
48.2 (d), 1JP-Rh = 76.8
6.8–8.5 (m) (aromatic)
881
(M Ϫ CO Ϫ I)ϩ
a Calculated values in parentheses. b As Nujol mulls, in cmϪ1 c In CDCl3 solution. d FAB mass spectra in 3-nitrobenzyl alcohol matrix.
.

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Table 5 Selected bond lengths (Å) and angles (Њ) for compound 17
Table 6 Selected bond lengths (Å) and angles (Њ) for compound 19
Rh(1)–C(1)
Rh(1)–S(1)
Rh(1)–P(1)
Rh(1)–P(2)
Rh(1)–S(2)
Rh(1)–Rh(2)
Rh(2)–C(2)
Rh(2)–P(3)
Rh(2)–S(2)
Rh(2)–S(1)
Rh(2)–P(4)
S(1)–C(12)
P(1)–C(11)
1.933(9)
2.309(2)
2.320(2)
2.395(2)
2.412(2)
2.746(2)
1.886(9)
2.320(2)
2.321(2)
2.376(2)
2.440(2)
1.777(8)
1.816(8)
P(1)–C(21)
P(1)–C(31)
P(2)–C(81)
P(2)–C(61)
P(2)–C(71)
S(2)–C(42)
P(3)–C(41)
P(3)–C(51)
P(3)–C(91)
P(4)–C(111)
P(4)–C(101)
C(1)–O(1)
C(2)–O(2)
1.828(8)
1.840(8)
1.833(9)
1.833(8)
1.836(8)
1.784(8)
1.815(8)
1.816(8)
1.829(8)
1.814(8)
1.830(8)
1.090(10)
1.136(11)
Rh–P
Rh–S
Rh–I(2)
Rh–I(3)
Rh–I(1)
Rh–I(1)#1
2.272(3)
2.355(4)
2.659(2)
2.6603(14)
2.683(2)
2.7602(14)
I(1)–Rh#1
S–C(12)
S–C
P–C(11)
P–C(31)
P–C(21)
2.7602(14)
1.801(12)
1.831(14)
1.808(13)
1.807(13)
1.828(14)
P–Rh–S
86.10(12)
91.93(10)
84.12(10)
89.75(10)
174.11(10)
91.85(5)
P–Rh–I(1)#1
S–Rh–I(1)#1
I(2)–Rh–I(1)#1
I(3)–Rh–I(1)#1
I(1)–Rh–I(1)#1
Rh–I(1)–Rh#1
C(12)–S–C
176.02(10)
90.09(9)
86.53(4)
93.97(4)
81.62(4)
98.38(4)
96.5(6)
P–Rh–I(2)
S–Rh–I(2)
P–Rh–I(3)
S–Rh–I(3)
I(2)–Rh–I(3)
P–Rh–I(1)
S–Rh–I(1)
I(2)–Rh–I(1)
I(3)–Rh–I(1)
99.88(9)
C(1)–Rh(1)–S(1)
C(1)–Rh(1)–P(1)
S(1)–Rh(1)–P(1)
C(1)–Rh(1)–P(2)
S(1)–Rh(1)–P(2)
P(1)–Rh(1)–P(2)
C(1)–Rh(1)–S(2)
S(1)–Rh(1)–S(2)
P(1)–Rh(1)–S(2)
P(2)–Rh(2)–S(2)
161.7(2)
96.5(2)
86.75(7)
99.2(2)
98.08(7)
98.70(8)
92.9(2)
78.68(7)
159.14(7)
98.07(8)
C(2)–Rh(2)–P(3)
C(2)–Rh(2)–S(2)
P(3)–Rh(2)–S(2)
C(2)–Rh(2)–S(1)
P(3)–Rh(2)–S(1)
S(2)–Rh(2)–S(1)
C(2)–Rh(2)–P(4)
P(3)–Rh(2)–P(4)
S(2)–Rh(2)–P(4)
S(1)–Rh(2)–P(4)
91.0(3)
161.9(3)
87.02(8)
97.2(3)
158.88(7)
79.16(8)
98.3(3)
105.13(8)
99.54(7)
92.96(8)
95.65(10)
168.16(5)
89.17(4)
C(12)–S–Rh
C–S–Rh
103.4(5)
114.0(5)
Symmetry relation: #1 Ϫx, Ϫy, Ϫz.
C(1)–Rh(1)–Rh(2) 106.7(2)
S(1)–Rh(1)–Rh(2)
P(1)–Rh(1)–Rh(2)
P(2)–Rh(1)–Rh(2)
S(2)–Rh(1)–Rh(2)
55.27(5)
106.32(6)
141.18(6)
52.99(5)
Fig. 7 A ZORTEP representation of the structure of [Rh2I6(Ph2-
PC6H4SMe-2)2] 19, showing the atom labelling scheme.
unexpected for these systems, and is observed as a by-product in
the carbonylation of methanol.27 The availability of sulfur as an
additional site for alkylation has a significant effect on the
course of the reaction, and little or no acetone is formed
when [RhCl(CO)(PPh3)2] is treated with an excess of MeI under
similar conditions.
Crystal structure of [Rh2I6(PhPPSMe)2] 19. The X-ray crystal
structure is shown in Fig. 7 and selected bond lengths and
angles appear in Table 6. The geometry about each rhodium()
atom of the dimer is approximately octahedral with a double
iodide bridge. The bond distances and angles for the Rh2I6
unit are similar to those reported for [Rh2(MeCO)2I6(CO)2]2Ϫ.28
The phosphinothiolate ligand has been alkylated at sulfur
to give the corresponding bidentate thioether and the Rh–P
and Rh–S distances are very similar to those found in
[Rh(ePPSMe)2]BF4.29
Fig.
6
A ZORTEP representation of the structure of [Rh2H2-
(µ-Ph2PC6H4S-2)2(CO)2(PPh3)2]2ϩ 17 showing the atom labelling
scheme. The tertiary phosphine phenyl groups are omitted for clarity.
2.321(2) Å] probably as a consequence of the presence of the
chelated P,S ring system.
With 1,3-diiodopropane. Reaction of complex 9 with an
excess of I(CH2)3I in dry dichloromethane for 24 h at
room temperature gave 20 as a bright orange powder in ca. 55%
yield. The elemental analysis suggested the stochiometry
‘Rh(PhPSS)(CH2)3I2(CO)(PPh3)’ consistent with oxidative
addition of the diiodopropane unit. The IR showed a single
strong band at 2062 cmϪ1, the increase from that found in 9
being consistent with oxidative addition at the metal. The 31P
NMR showed two doublets of doublets at δ 61.2 and 25.8
consistent with two inequivalent phosphine ligands. The FAB
mass spectrum shows a strong peak at m/z = 658 correspond-
ing to [M Ϫ (CH2)3 Ϫ 2I Ϫ CO]ϩ with appropriate isotope
distribution.
With [Me3O][BF4] or MeI. Reaction of complex 9 with
[Me3O][BF4] in dry CH2Cl2 gave the purple rhodium() cation
[Rh(PhPPSMe)(CO)(PPh3)]ϩ 18 in high yield, isolated as the
[BF4]Ϫ salt. The IR spectrum showed an intense band due to
ν(CO) at 2014 cmϪ1 (see Table 4). This is 36 cmϪ1 lower than the
value for complex 17, consistent with alkylation taking place at
sulfur rather than the metal and retention of the rhodium()
oxidation state.
The oxidative addition of MeI is a crucial step in the carbon-
ylation of methanol in the Monsanto process, and we have
investigated the reaction of complex 9 with an excess of methyl
iodide. In benzene at room temperature the deep red dimeric
complex [Rh2I6(PhPPSMe)2] 19 is formed in high yield. GC
analysis of the reaction mixture indicated that acetone had been
formed in virtually quantitative yield, presumably via methyl-
ation of an acetyl intermediate. The formation of acetone is not
The first step of the reaction is presumably oxidative addition
of one end of the diiodopropane to the RhI or at S to give
[RhI(CH2CH2CH2I)(PhPPS)(CO)(PPh3)2] or [Rh(PhPPSCH2-
CH2CH2I)(CO)(PPh3)]ϩIϪ. These possibilities cannot be dis-
tinguished, but the fact that no CO insertion product is
3012
J. Chem. Soc., Dalton Trans., 2000, 3007–3015

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by NMR spectroscopy. The Rh–P distances are closely similar
to those in [Rh(CH3)I2(PPh3)2]32 and the Rh–I distances are
close to those found in [Rh(COCH3)I2(Ph2PCH2CH2PPh2)].33
Conclusion
Fig. 8 Proposed structure for [RhI2(Ph2PC6H4S(CH2)3)(CO)(PPh3] 20.
We have shown that reaction of a fluoro precursor with bulky
aromatic thiolates provides a convenient high yield route to
complexes of the types [M(SAr)(CO)(PPh3)2] (M = Ir) and
[M2(µ-SAr)2(CO)2(PPh3)2] (M = Rh). These have been shown to
be effective hydroformylation catalysts. The monomeric phos-
phinothiolate complex [Rh(PhPPS)(CO)(PPh3)] can be pre-
pared analogously and its reactions clearly show that, with the
exception of the proton, electrophilic attack takes place at the
thiolate sulfur. This causes such reactions to take a quite differ-
ent course from that for complexes where thiolate is replaced by
halide or the thiolate is bridging and much less susceptible to
electrophilic attack. By contrast, protonation with acids with
weakly co-ordinating anions occurs at the metal with an
unusual example of reversible thiolate bridge formation.
Fig. 9 Proposed structure for [RhI2(Ph2PC6H4SCH2CO2)(PPh3)] 21.
Experimental
Unless stated otherwise, all reactions were carried out under an
atmosphere of dinitrogen using conventional Schlenk glassware
and solvents were dried using established procedures and dis-
tilled under dinitrogen immediately prior to use. IR spectra
were recorded on a Perkin-Elmer Paragon FT-IR spectrometer
as Nujol mulls and 1H and 31P NMR spectra on a JEOL EX270
spectrometer in CDCl3 solution. Elemental analyses were
determined on a Perkin-Elmer 240 instrument at the University
of Essex. The complexes [MF(CO)(PPh3)2] (M = Rh or Ir) were
made by the literature method.34 The thiols, TIPBTH,35
DMBTH35 and TPSBTH36 and phosphinothiols PhPPSH,
ePPSH,37 e*PPSH37 and PrPPSH37 were also prepared by
published routes.
Fig. 10 A ZORTEP representation of the structure of [RhI3(CO)-
(PPh3)2] 22, showing the atom labelling scheme.
observed, and the nature of the product 19 of the reaction with
Ϫ
Me3OϩBF4 , suggest initial attack may be at sulfur. Oxidative
addition of the second CH2I group and co-ordination of the
iodide counter ion gives the final product 20, for which we
propose the structure shown in Fig. 8. The formation of the
chelated alkyl derivative presumably prevents insertion of CO
to give a co-ordinated acetyl group.
Preparations
trans-[Rh(DCBT)(CO)(PPh3)2] 1. trans-[RhF(CO)(PPh3)2]
(0.10 g, 0.15 mmol) and the thiol DCBTH (0.027 g, 15 mmol)
were stirred at room temperature in toluene (30 ml) for 45 min
to give an orange solution. The solvent was removed under
reduced pressure and the residue crystallised from CH2Cl2–
MeOH as a yellow-orange microcrystalline powder in 85% yield.
With iodoacetic acid. An excess of iodoacetic acid reacted
with complex 9 in benzene at room temperature to give 21 as a
deep red powder in about 50% isolated yield. The complex is
stable in air both in the solid state and in solution, the elemental
analysis being consistent with the stoichiometry ‘RhI2(PhPPS)-
(CH2CO2)(PPh3)’. The IR spectrum shows a strong band at
1652 cmϪ1 assigned to a carboxyl group, but no band attribut-
able to a terminally bond carbonyl ligand. 1H NMR showed the
expected multiplet for the aromatic protons and a pair of doub-
lets at δ 2.20 and 2.75 assigned to the methylene protons and
suggests metal binding by the carboxylate oxygen. The 31P
NMR comprised two doublets of doublets at δ 48.2 and 4.9
consistent with two inequivalent phosphine ligands bound to
Rh. An intense peak in the MS at m/z = 971 corresponds to
[M]ϩ and a weaker peak at m/z = 844 to [M Ϫ I]ϩ. Based on
the analytical and spectroscopic data we assign the structure
shown in Fig. 9. The loss of the CO ligand suggests a
multiple series of insertion/addition reactions, as with methyl
iodide, but we were unable to identify the eventual fate of the
CO in this case.
trans-[Rh(TPSBT)(CO)(PPh3)2] 2. This compound was pre-
pared in a similar manner to 1 from trans-[RhF(CO)(PPh3)2]
(0.1 g, 0.15 mmol) and the thiol TPSBTH (0.055 g, 0.15 mmol).
Yield 70%.
[Rh2(ꢀ-DMBT)2(CO)2(PPh3)2] 3. This compound was pre-
pared in a similar manner to 1 from trans-[RhF(CO)(PPh3)2]
(0.1 g, 0.15 mmol) and the thiol DMBTH (0.020 g, 0.15 mmol).
Yield 80%.
[Rh2(ꢀ-TIPBT)2(CO)2(PPh3)2] 4. This compound was pre-
pared in a similar manner to compound 1 from trans-
[RhF(CO)(PPh3)2] (0.1 g, 0.15 mmol) and the thiol TIPBTH
(0.035 g, 0.15 mmol). Yield 83%.
trans-[Ir(DCBT)(CO)(PPh3)2] 5. To a solution of trans-
[IrF(CO)(PPh3)2] (0.1 g, 0.13 mmol) in toluene (25 cm3) was
added 1 equivalent of the thiol DCBTH (0.023 g, 0.13 mmol).
The solution was stirred at room temperature for 45 min. The
volume was reduced under vacuum and the residue recrystal-
lised from CH2Cl2–MeOH. Yield 95%.
A by-product of the reaction, isolated by recrystallisation as
a red solid in ca. 15% yield, is [RhI3(CO)(PPh3)2] 22. Crystals
suitable for structure determination were grown from
dichloromethane–methanol.30 A ZORTEP representation of
the structure appears in Fig. 10. The geometry about the Rh is
pseudo octahedral with the two phosphorus donors in trans
locations. Such trihalogenorhodium() complexes have been
observed before31 but isolated in very low yield and identified
trans-[Ir(TPSBT)(CO)(PPh3)2] 6. This compound was pre-
pared in a similar manner to 5 from trans-[IrF(CO)(PPh3)2]
(0.1 g, 0.13 mmol) and the thiol TPSBTH (0.048 g, 0.13 mmol).
Yield 90%.
J. Chem. Soc., Dalton Trans., 2000, 3007–3015
3013

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trans-[Ir(DMBT)(CO)(PPh3)2] 7. This compound was pre-
pared in a similar manner to 5 from trans-[IrF(CO)(PPh3)2]
(0.1 g, 0.13 mmol) and the thiol DMBTH (0.018 g, 0.13 mmol).
Yield 40%.
[Rh(PhPPSMe)(CO)(PPh3)][BF4] 18. To a benzene solution
(25 ml) of complex 9 (0.1 g, 0.146 mmol) was added an excess
of [Me3O][BF4] (0.05 g, 0.350 mmol). After stirring for 30 min a
precipitate started to form and a change from a bright yellow
to a dark purple was observed. The mixture was stirred for
one hour and then the deep purple precipitate filtered off,
redissolved in the minimum amount of CH2Cl2 and precip-
itated with n-pentane as a fine, deep purple powder 18, yield
65%.
trans-[Ir(TIPBT)(CO)(PPh3)2] 8. To a solution of trans-
[IrF(CO)(PPh3)2] (0.1 g, 0.13 mmol), TIPBTH (0.031 g, 0.13
mmol) was added. After stirring in toluene (25 ml) for 1 hour a
green solution was obtained. Reduction of the solvent under
vacuum yielded a green oily product. The crude material
was then redissolved in the minimum amount of CH2Cl2 and
chromatographed on a column using silica gel as the stationary
phase (Kieselgel 60, Fluka) and eluted with CH2Cl2. The green
solution was collected and impurities remained at the top of the
column. Yield 43% as a yellow solid.
[Rh2(ꢀ-I)2(I)4(PhPPSMe)2] 19. To a solution of complex 9
(0.1 g, 0.146 mmol) in benzene (10 cm3), was added MeI (0.8
cm3) and the mixture allowed to stir for 24 hours. During this
time a change from bright yellow to deep red was observed. The
solvent was removed under vacuum to give a reddish black resi-
due, which was redissolved in the minimum of CH2Cl2 and
layered with MeOH. On standing for 24 hours a deep red
microcrystalline product 19 was isolated. Yield 52%.
[Rh(PhPPS)(CO)(PPh3)] 9. To
a solution of trans-
[RhF(CO)(PPh3)2] (0.1 g, 0.15 mmol) in toluene (25 cm3) was
added 1 equivalent of the phosphinothiol PhPPSH (0.044 g,
0.15 mmol). The solution was stirred for 45 min, the volume
reduced under reduced pressure and the residue recrystallised
as a pale yellow solid from CH2Cl2–MeOH. Yield 95%.
[RhI2(PhPPS(CH2)3)(CO)(PPh3)] 20. To a CH2Cl2 solution
(25 ml) of complex 9 (0.1 g, 0.146 mmol) was added 1,3-
diiodopropane (0.8 cm3) and the mixture stirred for 24 hours.
The solvent was then removed in vacuo and the orange residue
redissolved in the minimum amount of CH2Cl2 and precip-
itated with n-pentane yielding the compound 20 as a bright
orange powder. Yield 55%.
[Rh(PrPPS)(CO)(PPh3)] 10. This compound was prepared in
a similar manner to 9 from trans-[RhF(CO)(PPh3)2] (0.1 g, 0.15
mmol) and the phosphinothiol PrPPSH (0.039 g, 0.15 mmol),
yield 90%.
[RhI2(PhPPSCH2CO2)(PPh3)] 21. This compound was syn-
thesized analogously to 20 using an excess of iodoacetic acid,
yield 52%.
[Rh(ePPS)(CO)(PPh3)] 11. This compound was prepared
in a similar manner to 9 from trans-[RhF(CO)(PPh3)2] (0.1 g,
0.15 mmol) and the phosphinothiol ePPSH (0.037 g, 0.15
mmol), yield 80%.
trans-[RhI3(CO)(PPh3)2] 22. This compound was obtained
from the previous reaction as a by-product. Purification was
achieved by recrystallisation from CH2Cl2–MeOH, final yield
15%.
[Rh(e*PPS)(CO)(PPh3)] 12. This compound was prepared in
a similar manner to 9 from trans-[RhF(CO)(PPh3)2] (0.1 g, 0.15
mmol) and the phosphinothiol e*PPSH (0.039 g, 0.15 mmol),
yield 87%.
Catalysis experiments
Hydroformylation experiments were carried out at the Instituto
de Catalisis y Petroleoquimica, Consejo Superior de Investi-
gaciones Cientifícas, (C.S.I.C.), Madrid, Spain, in a 150 cm3
stainless steel autoclave with a magnetic stirrer and a glass inlet.
The temperature was kept constant at 70 ЊC by using a double
jacket water system circulate. Syngas (H2 :CO = 1:1) was
introduced at a constant pressure of 5 bar from a gas reservoir.
The fall of pressure in the autoclave was monitored with a
transducer connected to an electric recorder. A solution of the
precursor containing the substrate was placed in the evacuated
autoclave and then heated to the required temperature. When
thermal equilibrium was reached Syngas was introduced at
5 bar, and stirring was initiated. After each run the solution
was analysed by GLC with a Hewlett-Packard 5940A chrom-
atograph equipped with a 6 m × 1/8 in column of OV-17 on
Chromosorb WHP.
[Ir(PhPPS)(CO)(PPh3)] 13. To
a solution of trans-
[IrF(CO)(PPh3)2] (0.1 g, 0.13 mmol) in toluene (25 cm3) was
added 1 equivalent of the phosphinothiol PhPPSH (0.039 g,
0.13 mmol). The solution was stirred for 45 min in the presence
of NEt3, the volume reduced under reduced pressure and the
residue recrystallised as a pale yellow solid from CH2Cl2–
MeOH. Yield 72%.
[Ir(PrPPS)(CO)(PPh3)] 14. This compound was prepared in
a similar manner to 13 from trans-[IrF(CO)(PPh3)2] (0.1 g, 0.13
mmol) and the phosphinothiol PrPPSH (0.034 g, 0.13 mmol),
yield 90%.
[Ir(H)(PhPPS)2(CO)] 15. This compound was prepared in a
similar manner to 13 from trans-[IrF(CO)(PPh3)2] (0.1 g, 0.13
mmol) and the phosphinothiol PhPPSH (0.039 g, 0.13 mmol),
but no NEt3 was added, yield 87%.
X-Ray data collection
For complexes 5 and 17. Intensity data were collected on an
Enraf-Nonius CAD4 diffractometer38 with monochromated
Mo-Kα radiation (λ = 0.71073 Å). Cell constants were obtained
from least squares refinement of the setting angles of 25 centred
reflections in the range 1.87 < θ < 24.97Њ. The data were col-
lected in the ω–2θ scan mode and three standard reflections
were measured every 2 hours of exposure. Three standard
reflections were measured every 200 to check the crystal orien-
tation. The data were corrected for Lorentz and polarisation
factors and an absorption correction was applied using psi
scans of nine reflections.
[Ir(H)(PrPPS)2(CO)] 16. This compound was prepared in a
similar manner to 15 from trans-[IrF(CO)(PPh3)2] (0.1 g, 0.13
mmol) and the phosphinothiol PrPPSH (0.034 g, 0.13 mmol),
yield 87%.
[Rh2(PhPPS)2(CO)2(PPh3)2][BF4]2 17. To a CH2Cl2 solution
(20 cm3) of complex 9 (0.1 g, 0.146 mmol) was added an excess
of HBF4 (0.03 mg, 0.35 mmol); an immediate change from a
bright yellow to a dark purple was observed. The mixture was
stirred for 1 hour and then the solvent removed under vacuum.
The residue was redissolved in the minimum amount of CH2Cl2
and precipitated with n-pentane as a fine, dark red-purple
powder 17, yield 80%.
For complexes 4 and 19. Intensity data were collected at the
EPSRC service, Cardiff on a Delft-Instrument FAST-TV area
detector diffractometer with graphite-monochromated Mo-Kα
3014
J. Chem. Soc., Dalton Trans., 2000, 3007–3015

View Article Online
Table 7 Summary of X-ray structural data for complexs 4, 5, 17 and 19
4 [Rh2(µ-TIPBT)2-
(CO)2(PPh3)2]
5 trans-[Ir(DCBT)-
(CO)(PPh3)2]
17 [RhH2(PhPPS)2-
(CO)2(PPh3)2][BF4]2
19 [Rh2(µ-I)2(I)4-
(PhPPSMe)2]
Empirical formula
M
C68H76O2P2Rh2S2
1257.17
C43H33Cl2IrOP2S
922.79
C74H60B2F8O2P4Rh2S2
1548.66
C19H17I3PRhS
791.97
Crystal system
Space group
Monoclinic
P21/n
Triclinic
P1
Triclinic
P1
Monoclinic
P21/n
¯
¯
a/Å
b/Å
c/Å
α/Њ
13.529(4)
33.568(10)
14.134(5)
9.2039(10)
11.600(2)
19.014(3)
99.934(10)
95.243(10)
106.744(10)
1893.3(5)
2
11.931(2)
13.554(9)
22.814(4)
97.70(3)
97.870(10)
97.41(4)
3581(3)
2
12.503(2)
12.982(5)
14.481(3)
β/Њ
104.69(5)
92.51(5)
γ/Њ
V/Å3
6209(3)
4
0.693
2348.2(11)
4
4.829
Z
µ(Mo-Kα)/mmϪ1
T/K
3.840
293
0.674
293
293
293
Reflections collected
Independent reflections (Rins
Reflections observed
R1, wR2
20978
8986(0.1085)
5682
7071
6616(0.0121)
6098
13194
12610(0.0701)
9358
6872
3276(0.0757)
1980
)
0.0637, 0.1356
0.0222, 0.0575
0.0685, 0.1951
0.430, 0.0925
radiation (λ = 0.71069 Å).39 Cell constants were obtained from
least squares refinement of the setting angles of 250 reflections
having θ = 2.34–25.09Њ.
17 J. J. Garcia, H. Torrens, H. Adams, N. A. Bailey and P. Maitlis,
J. Chem. Soc., Chem. Commun., 1991, 74.
18 S. Sirol and P. Kalck, Nouv. J. Chim., 1997, 21, 1129; E. Fernandez,
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20 T. Bang, J. Molinier and P. Kalck, J. Organomet. Chem., 1993, 455,
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21 M. Dieguez, C. Claver, A. M. Masdeu-Bolto, A. Ruiz, P. W. N. M.
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26 J.-J. Bonnet, A. Thorez, A. Maissonat, J. Galy and R. Poilblanc,
J. Am. Chem. Soc., 1979, 101, 5940.
27 L. S. Hegedus, S. Lo and D. E. Bloss, J. Am. Chem. Soc, 1973, 95,
3040; N. E. Schore, C. Ilenda and R. G. Bergman, J. Am. Chem. Soc.,
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Structure analysis and refinement. The structures were all
2
solved via direct methods40 and refined on Fo by full-matrix
least squares.41 All non-hydrogen atoms were anisotropic. The
hydrogen atoms were included in idealised positions with Uiso
free to refine. The weighting scheme gave satisfactory results.
The structure diagrams were produced by ZORTEP.14 Crystal-
lographic data for all four compounds are presented in Table 7.
CCDC reference number 186/2095.
See http://www.rsc.org/suppdata/dt/b0/b005588n/ for crystal-
lographic files in .cif format.
Acknowledgements
We are grateful to CONACYT for financial support to D. M.,
and to Dr P. Terreros at the Instituto de Catalisis y Petroleo-
quimica, C. S. I. C. Campus UAM, Madrid, Spain, for the
facilities to carry out the catalytic experiments.
28 G. W. Adamson, J. J. Daly and D. Forster, J. Organomet. Chem.,
1974, 71, C17.
29 D. G. Dick and D. W. Stephan, Can. J. Chem. 1986, 64, 1870.
30 Crystal data: a = 24.092(4), b = 9.662(3), c = 16.819(4) Å, β =
115.08(4)Њ, monoclinic, space group C2/c. Owing to the poor quality
of the crystal, we were not able to collect enough data fully to refine
the structure, however by constraining all carbon atoms on the
phenyl group a reasonable structure was determined and refined
which was consistent well with analytical data.
31 M. C. Baird, J. T. Mague, J. A. Osborn and G. Wilkinson, J. Chem.
Soc. A, 1967, 1347; A. J. Deeming and B. L. Shaw, J. Chem. Soc. A,
1969, 597; C. Rosslyn, D. J. Cole-Hamilton, R. Whyman, J. C.
Barnes and M. C. Simpson, J. Chem. Soc., Dalton Trans., 1994,
1963.
32 J. A. Evans, D. R. Russell, A. Bright and B. L. Shaw, Chem.
Commun., 1971, 841.
33 K. G. Malloy and J. L. Petersen, Organometallics, 1995, 14, 2931.
34 J. R. Fitzgerald, N. Y. Sakhab, R. S. Strange and V. P. Narutis, Inorg.
Chem., 1973, 12, 1081.
35 P. J. Blower, J. R. Dilworth, J. P. Hutchinson and J. Zubieta, J. Chem.
Soc., Dalton Trans., 1985, 1533.
36 E. Bloch, V. Eswarakishnan, M. Gernon, G. Oferi-Okai, C. Saha,
K. Tong and J. Zubieta, J. Am. Chem. Soc., 1989, 111, 658.
37 P. J. Blower, J. R. Dilworth, G. J. Leigh, B. D. Neaves, F. B.
Normanton, J. P. Hutchinson and J. Zubieta, J. Chem. Soc., Dalton
Trans., 1985, 2647.
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