Synthesis of Cationic Iridium(I) Complexes of Water-Soluble Phosphine Ligands, [Ir(CO)(TPPMS)3]CF3SO3, [Ir(CO)(H2O)(TPPTS)2]CF3SO3.

Article abstract of DOI:10.1021/om9806139

Several new water-soluble iridium(I) complexes were synthesized and their reactivities with small molecules (H₂ or CO) in polar solvents (DMSO or H₂O) examined. Reaction of H₂ with [Ir(CO)(TPPMS)₃]CF₃

Full text of DOI:10.1021/om9806139

Organometallics 1999, 18, 123-127
123
Syn th esis of Ca tion ic Ir id iu m (I) Com p lexes of
Wa ter -Solu ble P h osp h in e Liga n d s,
[Ir (CO)(TP P MS)3]CF 3SO3, [Ir (CO)(H2O)(TP P TS)2]CF 3SO3,
a n d [Ir (CO)2(TP P MS)3]ClO4 (TP P MS )
P P h 2(m -C6H4SO3K), TP P TS ) P (m -C6H4SO3Na )3)
David P. Paterniti, Laura W. Francisco, and J im D. Atwood*
Department of Chemistry, University at Buffalo, State University of New York,
Buffalo, New York 14260-3000
Received J uly 20, 1998
Several new water-soluble iridium(I) complexes were synthesized and their reactivities
with small molecules (H2 or CO) in polar solvents (DMSO or H2O) examined. Reaction of H2
with [Ir(CO)(TPPMS)3]CF3SO3 (TPPMS ) P(C6H5)2(m-C6H4SO3K)) in DMSO or H2O produces
[cis,mer-Ir(CO)(H)2(TPPMS)3]CF3SO3, while the reaction of CO with [Ir(CO)(TPPMS)3]-
CF3SO3 in water yields [Ir(CO)2(TPPMS)3]CF3SO3. Carbonylation of [Ir(CO)2(TPPMS)3]ClO4
in DMSO produces [Ir(CO)3(TPPMS)2]ClO4 and TPPMS; no reaction is observed in H2O.
Hydrogenation of [Ir(CO)2(TPPMS)3]ClO4 in DMSO or H2O yields [cis,mer-Ir(CO)(H)2-
(TPPMS)3]ClO4, while reaction of H2 with an aqueous solution of [Ir(CO)(H2O)(TPPTS)2]-
CF3SO3 produces [Ir(CO)(H2O)(H)2(TPPTS)2]CF3SO3. Reaction of trans-Ir(CO)ClL2 (L )
TPPMS or TPPTS) with excess L in H2O produces [Ir(CO)L3]Cl, while no reaction occurs in
DMSO. [Ir(CO)3(TPPMS)2]Cl reacts irreversibly with TPPMS in H2O to produce [Ir(CO)2-
(TPPMS)3]Cl.
In tr od u ction
ity of a metal complex in water, allowing direct com-
parison of reactions in polar and nonpolar media.
The use of water-soluble organometallic complexes as
catalysts for hydroformylation5,6,11 and hydrogenation12
of alkenes continues to increase. This, in part, has been
attributed to the success of the Ruhrchemie/Rhoˆne-
Poulenc process,13 where propylene is converted to
butanal via hydroformylation using Rh(CO)2(H)(TPPTS)2.
While mechanistic knowledge has been accumulated
over the years from hydroformylations utilizing Rh-
(CO)2(H)(PPh3)2, in organic solvents,14 systematic in-
vestigations into the effects of water on key reaction
steps (oxidative addition of H2, carbonylation, and
reductive elimination) are lacking.
Organic media have been used for homogeneous
catalysis because of their solvating abilities toward
organometallic compounds. Concerns over hazardous
waste generated during catalytic reactions and separa-
tion of product and catalyst led to the development of
systems that employ water as solvent. In these catalytic
systems, organometallic complexes are made water-
soluble through the use of hydrophilic ligands.1-3 The
benefits gained from using water-based catalytic sys-
tems include easier product separations, decreased
price, increased safety, and more efficient catalyst
recycling.4-6
Hydrophilic ligands such as TPPMS and TPPTS are
electronically similar to PPh3, as indicated by their 31P
NMR resonances.7-9 These similarities in electronic
properties allow for easy routes to prepare water-soluble
complexes by exchange of TPPMS or TPPTS for PPh3.10
The presence of the sulfonate group changes the solubil-
In contrast to most organic solvents, water is not
innocuous. Protonation, hydrogen exchange, and nu-
cleophilic attack may be expected in aqueous solution.15
Recent studies have shown water to be an active
participant in several reactions (oxidative addition of
H2 to trans-Ir(CO)X(L)2 (X ) Cl,16,17 OH,18 or CH3;19
L
) TPPMS16,18 or TPPTS17); carbonylation of trans-Ir-
(1) Kuntz, E. G. CHEMTECH 1987, 17, 570.
(2) Wolfgang, A. H.; Christian, W. K. Angew. Chem., Int. Ed. Engl.
1993, 32, 1524.
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(4) Wolfgang, A. H.; Christian, W. K. J . Mol. Catal. 1992, 73, 191.
(5) J oo´, F.; To´th, Z. J . Mol. Catal. 1980, 8, 369.
(6) (a) Kalck, P.; Monteil, F. Adv. Organomet. Chem. 1992, 34, 219.
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(7) Lawson, H. J .; Atwood, J . D. J . Am. Chem. Soc. 1989, 111,
6223.
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Ser. C 1990, 310, 493.
(11) (a) Beller, M.; Cormile, B.; Frohning, C. D.; Kohlpaintner, C.
W. J . Mol. Catal. A 1995, 104, 17. (b) Herrmann, W.; Kohlpaintner,
C. W. Angew. Chem., Int. Ed. Engl. 1993, 32, 1524. (c) Barton, M.;
Atwood, J . D. J . Coord. Chem. 1991, 24, 43.
(12) Roundhill, D. M., Adv. Organomet. Chem. 1995, 38, 155.
(13) (a) Morel, D.; J enck, J . Fr. Patent 2,550,202 to Rhoˆne-Polenc
Recherches, 1983. (b) Cornils, B.; Kuntz, E. G. J . Organomet. Chem.
1995, 502, 177.
(14) (a) Brown, C. K.; Wilkinson, G., J . Chem. Soc. (A) 1970,
2757. (b) Theodosiou, I.; Baron, R.; Chanon, M. J . Mol. Catal. 1985,
32, 27.
(9) Herrmann, W. A.; Kulpe, J . A.; Kellner, J .; Riepl, H.; Bahrmann,
H.; Konkol, W., Angew. Chem., Int. Ed. Engl. 1990, 29, 391.
(10) Borowski, A. F.; Cole-Hamilton, D. J .; Wilkinson, G. New J .
Chem. 1978, 2, 127.
(15) (a) J oo´, F.; Csiba, P.; Benyei, A. J . Chem. Soc., Chem. Commun.
1993, 1602. (b) J oo´, F.; Nadasdi, L.; Benyei, A. Cs.; Darensbourg, D.
J . J . Organomet. Chem. 1996, 512, 45. (c) Laghmari, M.; Sinou, D. J .
Mol. Catal. 1991, 66, L15.
10.1021/om9806139 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/15/1998

124 Organometallics, Vol. 18, No. 2, 1999
Paterniti et al.
(CO)X(L)2 (X ) Cl,18,20,21 OH;18 L ) TPPMS,18,20 TPPMS-
Na,19 or TPPTS21)). In this article, we report the
synthesis and characterization of several new cationic
iridium(I) complexes ([Ir(CO)(TPPMS)3]CF3SO3, [trans-
Ir(CO)(H2O)(TPPTS)2]CF3SO3 and [Ir(CO)2(TPPMS)3]-
ClO4) and their reactions with H2 or CO in DMSO and
H2O. Reactions of trans-Ir(CO)Cl(L)2 (L ) TPPMS or
TPPTS) with excess L in DMSO or H2O and reactions
of CO with [Ir(CO)2(TPPMS)3]ClO4 in DMSO and H2O
are also described.
by procedures similar to the literature procedures. In prepar-
ing trans-Ir(CO)(CF3SO3)(PPh3)2, silver salt metathesis, in the
absence of light, was performed on 199.3 mg (0.2554 mmol) of
trans-Ir(CO)Cl(PPh3)2 with 65.3 mg (0.254 mmol) of AgCF3-
SO3 in 15 mL of toluene. After stirring the solution for 45 min,
the AgCl precipitate was removed on a medium sintered-glass
filter and the volume was reduced to ∼5 mL; trans-Ir(CO)-
(CF3SO3)(PPh3)2 was precipitated by addition of hexanes (yield
210.6 mg, 92%). [Ir(CO)(PPh3)3]CF3SO3 was prepared by
reacting a 1:1 molar ratio of trans-Ir(CO)(OCF3SO2)(PPh3)2
(196.5 mg (0.220 mmol)) with PPh3 (57.2 mg (0.220 mmol)) in
15 mL of toluene. The deep orange [Ir(CO)(PPh3)3]CF3SO3
precipitate was collected after 2 h on a medium sintered-glass
filter and washed with toluene and hexanes (yield 254.0 mg,
99%). The exchange of PPh3 with TPPMS was performed using
244.4 mg (0.211 mmol) of [Ir(CO)(PPh3)3]CF3SO3 and 252.4 mg
(0.662 mmol, 3.1 equiv) of TPPMS in 25 mL of THF. After
stirring the solution overnight, the orange [Ir(CO)(TPPMS)3]-
CF3SO3 precipitate was collected and washed with THF,
diethyl ether, and hexanes (yield 255.4 mg, 80%). The char-
acteristic data for trans-Ir(CO)(OCF3SO2)(PPh3)2 and [Ir(CO)-
(PPh3)3]CF3SO3 (Table 1) were in agreement with previously
reported values.23,25,26 The 31P NMR resonances of [Ir(CO)-
(TPPMS)3]CF3SO3 integrated in a 1:2 ratio for cis phosphine
to trans phosphines (Figure 1), and the infrared and 31P
NMR data were similar to [Ir(CO)(PPh3)3]CF3SO3 (Table
1). [Ir(CO)(TPPMS)3]CF3SO3 can be recrystallized in 1:1 etha-
nol/cyclohexane (yield 48%). Elemental anal. Found: C(43.7),
H(4.1), and P(5.6). Requires: C(43.7), H(3.9), and P(5.5)
for a formula of [Ir(CO)(P(C6H5)2(C6H4SO3K‚H2O))3]CF3SO3‚
3CH3CH2OH.
[Ir (CO)2(TP P MS)3]ClO4. Using a previously published
method,22 with slight modification, [Ir(CO)2(PPh3)3]ClO4 was
synthesized by reacting 51.7 mg (0.0444 mmol) of [Ir(CO)3-
(PPh3)2]ClO4 with 25.85 mg (0.0985 mmol, 2.2 equiv) of PPh3
in a 50:50 THF/methanol solution. After the reaction was
complete (overnight), the solvent was pumped off, leaving a
lemon yellow product. The crude product was then suspended
in 10 mL of THF and precipitated with hexane, where it was
collected on a fine sintered-glass filter and washed with THF,
diethyl ether, and hexanes (yield 32.1 mg, 52%). The exchange
of PPh3 with TPPMS was performed using 32.1 mg (0.0230
mmol) of [Ir(CO)2(PPh3)3]ClO4 with 33.5 mg (0.0879 mmol, 3.8
equiv) of TPPMS in 25 mL of THF (the solution was stirred
overnight before collecting the product on a fine sintered-glass
filter, where it was washed with THF, diethyl ether, and
hexane (yield 40.6 mg, 99%). Elemental anal. Found: C(45.2),
H(3.0), P(6.2), and S(6.2). Requires: C(45.2), H(2.8), P(6.2), and
S(6.5) for a formula of [Ir(CO)2(P(C6H5)2(C6H4SO3K))3]ClO4.
The spectral characteristics of [Ir(CO)2(TPPMS)3]ClO4 (Table
1) were similar to [Ir(CO)2(PPh3)3]ClO4 (Table 1).
Exp er im en ta l Section
Ma ter ia ls. IrCl3‚3H2O was purchased or borrowed from
J ohnson Matthey. Triphenylphosphine, n-octylamine, fuming
sulfuric acid (20% and 30% SO3 w/w), and CH3Li were
purchased from Aldrich Chemical. Deuterated solvents were
purchased from Cambridge Isotope Labs, Aldrich Chemical
Co., or MSD Labs and were used as received unless otherwise
noted. H2 and CO were obtained from Matheson. Solvents used
outside the glovebox were used as received without further
drying or purification unless otherwise noted. Water was triply
distilled and deionized, while D2O and DMSO-d6 were de-
gassed on a high-vacuum line (three freeze-pump-thaw
cycles) in a pressure tube fitted with a Teflon stopcock.
Solvents used within the glovebox were prepared as follows:
THF and diethyl ether were refluxed in a N2 atmosphere over
Na/benzophenone until the solution turned blue or purple.
Hexane was refluxed overnight in a N2 atmosphere over finely
divided CaH2. DMSO was refluxed over finely divided CaH2
until dry and then distilled at reduced pressure while main-
taining a temperature of less than 90 °C. The compounds
trans-Ir(CO)Cl(TPPMS)2,18 [Ir(CO)3(PPh3)2]ClO4,22 and TPPMS18
were prepared as previously described.
In str u m en ta l Mea su r em en ts. Infrared spectra were ob-
tained using a Mattson Polaris Fourier transform spectrometer
or a Perkin-Elmer Paragon 1000 FT-IR spectrometer. Solution
spectra were recorded using 0.5 mm NaCl or 0.1 mm CaF2
(DMSO or H2O) cells while solid-state spectra were recorded
as KBr disks. All spectra are reported in wavenumbers (cm-1).
1H and 31P NMR spectra were recorded on Varian VXR-400
1
or 500 MHz spectrometers. H NMR spectra were referenced
to residual solvent resonances in the deuterated solvent, and
all NMR spectra contained resonances corresponding to aro-
matic protons, but these resonances were not assigned unless
otherwise noted. 31P NMR spectra were referenced to an
external sample of 85% H3PO4 in D2O (reference was set to
0.0 ppm) and were proton decoupled. For 1H and 31P NMR
spectra that were recorded in H2O, a sealed D2O reference was
placed into the sample for signal locking. Solvent suppression
techniques were utilized during the acquisition of 1H NMR
spectra in water. All chemical shifts (δ) are reported in ppm,
and all coupling constants (J ) are reported in Hz.
Elemental analyses were provided by E + R Microanalytical
Laboratory, Inc.
Syn th eses. All syntheses, preparations, and reactions,
unless otherwise noted, were performed in an argon-filled
glovebox or via Schlenk techniques.
[tr a n s-Ir (CO)(H2O)(TP P TS)2]CF 3SO3. In the absence of
light, silver salt metathesis was performed on trans-Ir(CO)-
Cl(TPPTS)2. In this reaction, 12 mg (0.0467 mmol) of
AgCF3SO3 and 70 mg (0.0500 mmol) of trans-Ir(CO)Cl-
(TPPTS)2 were dissolved in 2 mL of deionized water. The re-
sulting silver chloride precipitate was collected after 1 h on a
fine sintered-glass filter, and [trans-Ir(CO)(H2O)(TPPTS)2]-
CF3SO3 was recovered after the water was removed via
vacuum (yield 86%27). The 31P NMR and infrared data (Table
1) were similar to [trans-Ir(CO)(H2O)(PPh3)2]CF3SO3.28
Rea ction s. The reactions with H2, CO, and L (L ) TPPTS
or TPPMS), unless otherwise noted, were accomplished by
[Ir (CO)(TP P MS)3]CF 3SO3. The complexes trans-Ir(CO)-
(CF3SO3)(PPh3)223 and [Ir(CO)(PPh3)3]CF3SO324 were prepared
(16) Paterniti, D. P.; Roman, P. J ., J r.; Atwood, J . D. J . Chem. Soc.,
Chem. Commun. 1996, 2659.
(17) Paterniti, D. P.; Roman, P. J ., J r.; Atwood, J . D. Organometallics
1997, 16, 3371.
(18) Roman, P. J ., J r.; Paterniti, D. P.; See, R. F.; Churchill, M. R.;
Atwood, J . D., Organometallics 1997, 16, 1484.
(19) Paterniti, D. P.; Atwood, J . D. J . Chem. Soc., Chem. Commun.
1997, 1665.
(22) Malatesta, L.; Caglio, G.; Angoletta, M. J . Chem. Soc. 1965,
6974.
(23) Liston, D. J .; Young, J . L.; Scheidt, W. R.; Reed, C. A. J . Am.
Chem. Soc. 1989, 111, 6643.
(24) Peone, J ., J r.; Vaska, L. Angew. Chem., Int. Ed. Engl. 1971,
10, 511.
(20) Paterniti, D. P.; Atwood, J . D. Polyhedron 1998, 17, 1177.
(21) Roman, P. J ., J r.; Atwood, J . D. Organometallics 1997, 16,
5536.
(25) Reed, C. A.; Roper, L. J . Chem. Soc., Dalton Trans. 1973, 1365.
(26) Williams, A. F.; Bhaduri, S.; Maddock, A. G. J . Chem. Soc.,
Dalton Trans. 1975, 1958.

Synthesis of Cationic Iridium(I) Complexes
Organometallics, Vol. 18, No. 2, 1999 125
Ta ble 1. In fr a r ed a n d NMR Da ta for Com p ou n d s Discu ssed (All In fr a r ed Da ta Ar e for Ca r bon yl Str etch in g
F r equ en cies Un less Oth er w ise In d ica ted ). L ) TP P MS; L′ ) TP P TS
complex
[Ir(CO)L3]CF3SO3
IR (cm-1
)
31P δ (ppm)
15.2(br), 18.2(br)b,c
1H δ (IrH) (ppm); coupling constants (Hz)
2011(br)a
2011d
[Ir(CO)L3]ClO4
[Ir(CO)L3]Cl
[Ir(CO)L′3]Cl
trans-Ir(CO)(OCF3SO2)(PPh3)2
[Ir(CO)(PPh3)3]CF3SO3
2013(br)a
2013(br)a
2023(br)a
1985b
15.4(br), 18.3(br)a,c
15.8(br), 18.6(br)a,c
16.5(br), 19.8(br)a,c
27.4(br)e
2002b
15(d), 17.5(t)c,e;
J PP ) 29 Hz
29.7(s)a
[trans-Ir(CO)(H2O)L′2]CF3SO3
1993(br)a
[trans-Ir(CO)(DMSO-d6)L2]CF3SO3 1979f
28.7(br)g
[Ir(CO)2L3]CF3SO3
[Ir(CO)2L3]ClO4
1966(w), 2005a
1966(w), 2003(s)a
1967(w), 2002(s)b
1964(w), 2002(s)f
2003, 2015(sh)a
n/a
-2.1(s)a
-2.1(s)a
[Ir(CO)2(PPh3)3]ClO4
[Ir(CO)3L2]ClO4
Ir(CO)2H(L)2
-2.2(s)g
-2.4(s)a
6.9(br)g
7.2(br)a
-11.2(t) (J PH ) 10.4)g
-11.2(m)a,h
[Ir(CO)(H2O)(H)2L′2]CF3SO3
[cis,trans-Ir(CO)2(H)2L2]ClO4
2024(br), 2115(br)a,i 18.9(s)a
-6.8(td) (J PH ) 17.7; J HH ) 5.0); -23(td) (J PH ) 14.2; J HH ) 5.0)a,j
-9.96(t) (J PH ) 14.6)a
n/a
4.6(s)a
4.4(br)a
14.8(s)a
11.3(s)g
8.6(s)a
-10.2(t) (J PH ) 11.6)a
cis,trans-Ir(CO)Cl(H)2L2
cis,trans-Ir(CO)(OClO3)(H)2L2
fac-Ir(CO)(H)3L′2
n/a
n/a
n/a
-7.7(td) (J PH ) 17.5; J HH ) 5.0); -19.3(td) (J PH ) 13.5; J HH ) 5.0)a,j
-7.4(td) (J PH ) 17.4; J HH ) 4.3); -18.4(td) (J PH ) 13.9; J HH ) 4.3)g,j
-10.7(t) (J PH ) 22); -11.8(2nd order dd) (J PH ) 21)a
[cis,mer-Ir(CO)(H)2L3]CF3SO3
2011(br), 2109(br)f,i 3.4(br), -0.5(br)c,g -9.6(qd) (J PH ) 14.5, J HH ) 4.5); -11.5(dtd) (J PH(cis) ) 18.1,
2018(br), 2115(br)a,i 3.7(br), 0.5(br)a,c
J PH(trans) ) 116, J HH ) 4.5)g,j
-9.6(q) (J PH ) 15); -11.6(dt) (J PH(cis) ) 20, J PH(trans) ) 120)a,j
[cis,mer-Ir(CO)(H)2L3]ClO4
2018(br), 2110(br)f,i 3.7(br), -0.1(br)c,g -9.6(qd) (J PH ) 19, J HH ) 4); -11.5(dtd) (J PH(cis) ) 18.5,
2019(br), 2113(br)a,i 3.7(br), 0.5(br)a,c
J PH(trans) ) 119, J HH ) 3.4)g,j
-9.8(qd) (J PH ) 17.4); -11.7(dt) (J PH(cis) ) 18, J PH(trans) ) 112)a,j
TPPMS
OTPPMS
-5.2a
26.9g
a
b
d
g
h
H2O. D2O. c The NMR resonances integrated in a 2:1 ratio for trans and cis phosphines. KBr. e CD2Cl2. f DMSO. DMSO-d6. No
i
j
coupling constants were calculated because of the poorly resolved spectrum. (Ir-H). The hydrides integrated in a 1:1 ratio.
-
F igu r e 1. (A) 31P NMR spectrum of [Ir(CO)(TPPMS)3]+-CF3SO3 recorded in water (δ(trans TPPMS) ) 15.8(br) ppm;
-
δ(cis TPPMS) ) 18.6(br) ppm). (B) 31P NMR spectrum of [trans-Ir(CO)(DMSO-d6)L2]+CF3SO3 (δ ) 28.7(br) ppm) and L
(δ ) -5.2(br) ppm) from the reaction of [Ir(CO)(TPPMS)3]CF3SO3 with DMSO-d6.
NMR-scale procedures (in a 10 mL beaker, ∼30 mg of the
(TPPMS)3]ClO4) can be prepared by exchange of PPh3
with TPPMS using stoichiometric amounts of iridium-
iridium complex was suspended in ∼1 mL of DMSO-d6, D2O,
or H2O; the solution was transferred to an NMR tube, sealed,
(I) complex and TPPMS in THF; the iridium(I) TPPMS-
and removed from the glovebox. Gases were added from a high-
containing complex precipitates from THF. The char-
acterization data shown in Table 1 confirm the product
vacuum line).
formulations.
Resu lts a n d Discu ssion
Rea ction s. When [Ir(CO)(TPPMS)3]CF3SO3 is dis-
Syn t h esis. The cationic complexes of iridium(I)
solved in DMSO-d6, [trans-Ir(CO)(DMSO-d6)(TPPMS)2]-
with TPPMS ([Ir(CO)(TPPMS)3]CF3SO3 and [Ir(CO)2-
CF3SO3 and TPPMS are produced in a 1:1 ratio (eq 1).
(27) The product was contaminated with a minor amount of unre-
acted starting material (trans-Ir(CO)Cl(TPPTS)2; 31P NMR(H2O); δ )
(28) Stang, P. J .; Linsheng Song, Yo-Hsin, Huang.; Atta, M. Arif.
J . Organmet. Chem. 1991, 405, 403.
26.9(br) ppm).

126 Organometallics, Vol. 18, No. 2, 1999
Paterniti et al.
DMSO-d6
Sch em e 1
[Ir(CO)L3]CF3SO3
8
[trans-Ir(CO)(DMSO-d6)L2]CF3SO3 + L (1)
L ) TPPMS
The PPh3 analogue ([Ir(CO)(DMSO)(PPh3)2]ClO4) was
prepared by dissolving trans-Ir(CO)(OClO3)(PPh3)2 in
DMSO.25 The tris(triphenylphosphine) complex [Ir(CO)-
(PPh3)3]+, while readily characterized in nonpolar sol-
vents (31P(CDCl3): 15.5(t) and 12.9(d) ppm with J P-P
) 30 Hz and a 1:2 integration), shows only a broadened
resonance at 29 ppm in DMSO. The trisphosphine
complex [Ir(CO)(TPPMS)3]CF3SO3 is stable in H2O.
Figure 1 shows the 31P NMR spectra recorded in DMSO-
d6 and H2O with clear distinction between the com-
plexes in the two solvents. The preference for [Ir(CO)-
(TPPMS)3]+ in water versus DMSO-d6 is not entirely
understood, but may indicate hydrogen bonding be-
tween adjacent TPPMS ligands. A crystal structure of
[N(CH2C6H5)(C2H5)3+][P(C6H5)2(m-C6H4SO3)-]‚H2O con-
firmed that a system of hydrogen bonding links the
[P(C6H5)2(m-C6H4SO3)-] anions through H2O molecules
of solvation.18 The cis orientation of the TPPMS ligands
around [Ir(CO)(TPPMS)3]CF3SO3 puts them in proxim-
ity to each other, which could allow for solvation
hydrogen bonding. A similar explanation may account
for the stability of [Ir(CO)2L3]+ (L ) TPPTS or TPPMS)
versus [Ir(CO)3L2]+ in water.20,21
CF3SO3 characterized by infrared and NMR. Water
coordination to other six-coordinate water-soluble di-
hydride complexes has been observed in [Rh(H2O)(H)2-
(TPPTS)3]Cl,31 Ru(H2O)(H)2(TPPTS)3,32 and [mer-Ir-
(H2O)(H)2(PMe3)3]Cl.33
[Ir(CO)2(TPPMS)3]ClO4 reacts with H2 in H2O (or
DMSO) to produce initially [cis,cis,trans-Ir(CO)2(H)2-
(TPPMS)2]ClO4 and TPPMS via substitution of TPPMS
with H2. Reaction of TPPMS with [cis,cis,trans-Ir(CO)2-
(H)2(TPPMS)2]ClO4 slowly generates [cis,mer-Ir(CO)-
(H)2(TPPMS)3]ClO4 and CO. In addition, [cis,cis,trans-
Ir(CO)2(H)2(TPPMS)2]ClO4, which is a weak acid,
establishes an equilibrium with H3O+ and Ir(CO)2H-
(TPPMS)2. The reaction sequences are shown in Scheme
1. In a different study,20,34 carbonylation of aqueous
trans-Ir(CO)Cl(TPPMS)2 produces [Ir(CO)3(TPPMS)2]Cl
(major product) and [Ir(CO)2(H2O)(TPPMS)2]Cl and
[cis,cis,trans-Ir(CO)2(H)2(TPPMS)2]Cl as minor prod-
ucts. Similarly, protonation of Ir(CO)2H(PPh3)2 at 60 °C
in a 1% ethanolic solution of perchloric acid produces
[Ir(CO)2(H)2(PPh3)2]ClO4.22 Addition of 2 drops of 5%
KOH to an aqueous solution containing [cis,cis,trans-
Ir(CO)2(H)2(TPPMS)2]Cl results in Ir(CO)2H(TPPMS)2
as the equilibrium is shifted.34
Reaction of H2 with [Ir(CO)(TPPMS)3]CF3SO3 in H2O
or DMSO-d6 produces [cis,mer-Ir(CO)(H)2(TPPMS)3]-
CF3SO3. The reaction in water proceeds cleanly to
product (eq 2),
[Ir(CO)L3]CF3SO3 + H2 H O8
2
[cis,mer-Ir(CO)(H)2L3]CF3SO3 (2)
Carbonylation of [Ir(CO)(TPPMS)3]CF3SO3 in water
produces [Ir(CO)2(TPPMS)3]CF3SO3 (eq 5).
L ) TPPMS
while the reaction in DMSO-d6 initially produces [trans-
Ir(CO)(DMSO-d6)(TPPMS)2]CF3SO3 and TPPMS (eq 1),
which then reacts with H2 (eq 3).
[Ir(CO)L3]CF3SO3 + CO H O8 [Ir(CO)2L3]CF3SO3 (5)
2
L ) TPPMS
[trans-Ir(CO)(DMSO-d6)L2]CF3SO3 +
Analogously, Reed et al.25 reported CO reacts with [Ir-
(CO)(PPh3)3]ClO4 to produce [Ir(CO)2(PPh3)3]ClO4 in
ethanol.
Induced decarbonylation of an aqueous solution of [Ir-
(CO)2(TPPMS)3]ClO4 by refluxing in a nitrogen atmo-
sphere produces [Ir(CO)(TPPMS)3]ClO4 (eq 6);
H2
L
8 [cis,mer-Ir(CO)(H)2L3]CF3SO3 (3)
L ) TPPMS
DMSO-d6
Reaction of [trans-Ir(CO)(H2O)(TPPTS)2]CF3SO3 with
H2 in H2O produces [cis,trans-Ir(CO)(H2O)(H)2(TPPTS)2]-
CF3SO3 (eq 4).
[Ir(CO)2L3]ClO4 N /H O8 [Ir(CO)L3]ClO4 + CO (6)
2
2
reflux
[trans-Ir(CO)(H2O)L2]CF3SO3 + H2 H O8
2
L ) TPPMS
decarbonylation of [Ir(CO)2(PPh3)3]ClO4 under similar
conditions yields [Ir(CO)(PPh3)3]ClO4.25 [cis,mer-Ir(CO)-
(H)2(TPPMS)3]ClO4 was a minor product (∼6%) of reac-
tion 6; its formation occurs through a series of reactions
that, initially, involves attack of OH- on a carbonyl
[cis,trans-Ir(CO)(H2O)(H)2L2]CF3SO3 (4)
L ) TPPTS
The aquo complex slowly undergoes further reaction
29
with H2 to fac-Ir(CO)(H)3(TPPTS)2 and a proton or
with TPPTS to form [cis,mer-Ir(CO)(H)2(TPPMS)3]-
CF3SO3 (Table 1).17 The use of triflate30 allowed genera-
tion of relatively pure [cis,trans-Ir(CO)(H2O)(H)2(TPPTS)2]-
(31) J ohnson, B. F. G.; Khattar, R.; Lewis, J .; Raithby, P. R. J .
Organomet. Chem. 1987, 335, C17.
(32) Fache, E.; Santini, C.; Senoiq, F.; Basset, J . M. J . Mol. Catal.
1992, 72, 331.
(33) Le, T. X.; Merola, J . S. Organometallics 1993, 12, 3798.
(34) Paterniti, D. P. Ph.D. Dissertation, State University of New
York at Buffalo, 1997.
(29) Harrod, J . F.; Yorke, W. J . Inorg. Chem. 1981, 20, 1156.
(30) Noyce, D. S.; Virgilio, J . A. J . Org. Chem. 1972, 37, 2643.

Synthesis of Cationic Iridium(I) Complexes
Organometallics, Vol. 18, No. 2, 1999 127
carbon of [Ir(CO)2(TPPMS)3]ClO4 to produce Ir(C(O)-
OH)(CO)(TPPMS)3 and a proton. Loss of CO2 gen-
erates Ir(CO)H(TPPMS)3,35 which is protonated to form
[cis,mer-Ir(CO)(H)2(TPPMS)3]ClO4 (eq 7).
as reported by Williams et al.26 No reaction is observed
when trans-Ir(CO)Cl(TPPTS)2 is dissolved with excess
TPPTS in DMSO-d6 (eq 13).
DMSO-d6
trans-Ir(CO)Cl(L)2 + L
8 NR
(13)
-CO2
[Ir(CO)2L3]+ H2O8 Ir(C(O)OH)(CO)L3 + H+
8
L ) TPPMS or TPPTS
+
H
Ir(CO)H(L)3 8 [Ir(CO)(H)2L3]+ (7)
Similarly, no reaction was observed for trans-Ir(CO)Cl-
(PPh3)2 with PPh3.37 The reactions of trans-Ir(CO)Cl-
(L)2 with excess L in H2O mark another route for
preparation of the tris-sulfonated phosphine iridium(I)
complexes.
L ) TPPMS
Reaction of CO with [Ir(CO)2(TPPMS)3]ClO4 in DMSO
produces [Ir(CO)3(TPPMS)2]ClO4 and TPPMS (eq 8), but
no reaction occurs in H2O (eq 9).
Con clu sion
DMSO-d6
The use of the hydrophilic ligand TPPMS allows
preparation of water-soluble cationic iridium(I) com-
plexes ([Ir(CO)(TPPMS)3]CF3SO3 and [Ir(CO)2(TPPMS)3]-
ClO4). The complexes prepared and the characteriza-
tions are remarkably similar for PPh3 complexes and
complexes of sulfonated phosphine ligands. However, for
reactions in H2O versus DMSO a number of differences
are observed: (1) Ir(CO)(TPPMS)3+ is stable in H2O but
[Ir(CO)2L3]ClO4 + CO
8 [Ir(CO)3L2]ClO4 + L
(8)
L ) TPPMS
[Ir(CO)2L3]ClO4 + CO H O8 NR
(9)
2
L ) TPPMS
+
loses TPPMS to form Ir(CO)(DMSO)(TPPMS)2 in
Consistent with reactions 8 and 9, TPPMS reacts
irreversibly with [Ir(CO)3(TPPMS)2]ClO4 in water to
produce [Ir(CO)2(TPPMS)3]ClO4 and CO (eq 10).
DMSO. (2) Ir(CO)(DMSO)(TPPMS)2+ is an identifiable
+
intermediate in reaction of Ir(CO)(TPPMS)3 with H2
in DMSO. No intermediate is seen for the hydrogenation
in H2O. (3) While H2 and CO react with Ir(CO)2-
(TPPMS)3+ in DMSO, only H2 reacts in H2O. (4) In H2O
[Ir(CO)3L2]ClO4 + L H O8 [Ir(CO)2L3]ClO4 + CO(g)
2
+
Ir(CO)2(TPPMS)3 loses CO (water reflux) to give Ir-
(10)
(CO)(TPPMS)3+. In DMSO, CO and TPPMS are readily
lost to give Ir(CO)(DMSO)(TPPMS)2+. (5) Reaction of
L ) TPPMS
+
Ir(CO)3(TPPMS)2 with TPPMS in H2O gives Ir(CO)2-
Reaction of [Ir(CO)3(PPh3)2]ClO4 with PPh3 in DMSO-
d6 establishes an equilibrium with [Ir(CO)2(PPh3)3]ClO4
and CO(g), which favors the products (eq 11).
(TPPMS)3+; no reaction is observed in DMSO. (6) trans-
Ir(CO)(Cl)(TPPMS)2 reacts with TPPMS in H2O to give
Ir(CO)(TPPMS)3+; in DMSO only TPPMS exchange is
observed.
[Ir(CO)3(PPh3)2]ClO4 + PPh3 {DMSO-d
}
6
The different reactions of iridium(I) complexes in H2O
in comparison to the also polar DMSO can all be
attributed to unusual stability in H2O for complexes
containing three sulfonated ligands. This stability in
water may indicate hydrogen bonding from water to cis-
sulfonated phosphine groups.
[Ir(CO)2(PPh3)3]ClO4 + CO(g) (11)
Adding excess L (L ) TPPMS or TPPTS) to an
aqueous solution of trans-Ir(CO)Cl(L)2 results in im-
mediate formation of [Ir(CO)L3]Cl (eq 12), as indicated
trans-Ir(CO)Cl(L)2 + L H O8 [Ir(CO)L3]Cl (12)
2
Ack n ow led gm en t. The authors are grateful to the
Department of Energy, ER 13775, for support of this
research, and to Dr. Paul Roman, J r., for his generous
donations of trans-Ir(CO)Cl(TPPTS)2 and TPPTS.
L ) TPPMS or TPPTS
by infrared and 31P NMR data,36 which are spectro-
scopically consistent with [Ir(CO)(TPPMS)3]+X (X )
CF3SO3- or ClO4-, see Table 1) and [Ir(CO)(PPh3)3]PF6
Su p p or tin g In for m a tion Ava ila ble: Synthesis data and
UV-vis data for compounds discussed in text (6 pages).
Ordering information is given on any current masthead page.
(35) Rokicki, A. Adv. Organomomet. Chem. 1988, 28, 139.
(36) ([Ir(CO)(TPPMS)3]+Cl- (IR: νCO ) 2013(br) cm-1; δ ) 15.8(br)
OM9806139
and 18.6(br) ppm) and [Ir(CO)(TPPTS)3]+Cl- (IR: νCO ) 2023(br) cm-1
δ ) 16.5(vbr) and 19.8(vbr) ppm).
;
(37) Chen, J . Y.; Halpern, J . J . Am. Chem. Soc. 1971, 93, 4939.