Synthesis of palladium(II) and platinum(II) complexes with crown ether phosphane ligands: Stille coupling of aryl iodides in water

Article abstract of DOI:10.1002/ejic.200400906

The crown ether phosphanes PAr*Ph₂ (1) and PAr*₂R [Ar* = 3,4-(18-crown-6)-phenyl; R = Me (2); R = Ph (3)], prepared from PCl₂R and Ar*Li, have been studied. The syntheses and characterization of their oxides (4-6), and their BH₃ (7-9), PdCl₂ (10-12), and PtCl₂ (13-15) complexes are reported. The molecular structure of the borane complex PAr* ₂Ph·BH₃ (9) has been determined by X-ray structural analysis. Spectroscopic data suggest that phosphanes 1-3 have similar electronic properties and steric requirements to the corresponding phenylphosphane ligands PPh₂Me and PPh₃. Crown ether methylphosphane 2 and its complexes are remarkably water soluble, but 1 and 3 are only slightly soluble. Palladium(II) complexes 14 and 15 have been tested as catalysts in the Stille coupling of phenyltrichlorostannanes and aryl iodides in water.

Full text of DOI:10.1002/ejic.200400906

FULL PAPER
Synthesis of Palladium(II) and Platinum(II) Complexes with Crown Ether
Phosphane Ligands: Stille Coupling of Aryl Iodides in Water
Jorge Fresneda,[b] Ernesto de Jesús,*[a] Pilar Gómez-Sal,[a] and
Carmen López Mardomingo[b]
Keywords: Aqueous-phase catalysis / Crown compounds / C–C coupling / Palladium / Phosphane ligands
The crown ether phosphanes PAr*Ph2 (1) and PAr*2R [Ar* =
3,4-(18-crown-6)-phenyl; R = Me (2); R = Ph (3)], prepared
from PCl2R and Ar*Li, have been studied. The syntheses and
characterization of their oxides (4–6), and their BH3 (7–9),
PdCl2 (10–12), and PtCl2 (13–15) complexes are reported. The
molecular structure of the borane complex PAr*2Ph·BH3 (9)
has been determined by X-ray structural analysis. Spectro-
ing phenylphosphane ligands PPh2Me and PPh3. Crown
ether methylphosphane 2 and its complexes are remarkably
water soluble, but 1 and 3 are only slightly soluble. Palladi-
um(II) complexes 14 and 15 have been tested as catalysts in
the Stille coupling of phenyltrichlorostannanes and aryl io-
dides in water.
scopic data suggest that phosphanes 1–3 have similar elec- (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
tronic properties and steric requirements to the correspond-
Germany, 2005)
bis[3,4-(18-crown-6)-phenyl] analogs of methyldiphenyl-
and triphenylphosphane and the preparation of their PdCl2
and PtCl2 complexes. The palladium complexes are tested
as catalysts in Stille carbon–carbon couplings[15,16] in an
aqueous medium.[17]
Introduction
The synthesis and study of metal complexes for aqueous-
phase homogeneous catalysis is currently an active research
area in organometallic chemistry.[1] Aryl- and alkyl-substi-
tuted tertiary phosphanes are among the most common li-
gands present in transition-metal catalysts, but they are
hydrophobic and lack water solubility. Hydrophilicity can Results and Discussion
be introduced into a phosphane by making use of polar
Synthesis and Characterization of Crown Ether Phosphanes
substituents, usually anionic or cationic functions, such as
sulfonate or ammonium groups.[2,3] Water solubility has
also been achieved with nonionic phosphanes, for example
with hydroxyalkyl or polyether substituents but, in general,
nonionic phosphanes have attracted less attention than
ionic phosphanes. Since the first report by Shaw et al. in
1978,[4] several examples of hybrid crown ether phosphane
ligands have appeared in the literature.[5–11] Okano and co-
workers have reported the synthesis of mono[3,4-(crown)-
phenyl]diphenylphosphane ligands PAr*Ph2 with crown
heterocycles of different sizes.[6] The water solubility of
these phosphanes is low but the crown cavity acts as an
extractant and phase-transfer agent for biphasic cataly-
sis.[5,6,12,13] Crown ether phosphanes contain a secondary
site for coordination that can play an important role in
catalytic processes.[9.10,14] Here, we report the synthesis of
and Their Complexes
The synthesis of phosphanes PAr*nR3–n [Ar* = 3,4-(18-
crown-6)-phenyl, R = Me, n = 2 (2); R = Ph, n = 2 (3)] is
based on the lithiation of bromo-3,4-(18-crown-6)-benzene
and the subsequent reaction of the lithium crown-aryl
LiAr* with the corresponding chlorophosphane PClnR3–n
(Scheme 1), according to the procedure reported previously
for the synthesis of PAr*Ph2 (1).[6] The main drawback of
this procedure lies in the thermal instability[4] of LiAr*,
which requires keeping the temperature carefully below the
decomposition point (–90 °C) until the reaction with the
chlorophosphane is completed, and to use a low concentra-
tion of reactants to avoid the formation of a slush at this
temperature.[9] In our hands, moderate to high yields (60–
90%) were obtained only when the temperature was main-
tained below –90 °C for at least one hour before and one
hour after the addition of the chlorophosphane. The main
impurities contaminating the crude product are 1,2-(18-
crown-6)-benzene and butylphosphanes derived from unre-
acted nBuLi and chlorophosphanes. In the case of 3, these
are readily removed by crystallization from ethanol/meth-
anol (9:1). In contrast, all our efforts to purify methylphos-
[a] Departamento de Química Inorgánica, Universidad de Alcalá,
Campus Universitario, 28871 Alcalá de Henares (Madrid),
Spain
Fax: +34-91-885-4683
E-mail: ernesto.dejesus@uah.es
[b] Departamento de Química Orgánica, Universidad de Alcalá,
Campus Universitario, 28871 Alcalá de Henares (Madrid),
Spain
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DOI: 10.1002/ejic.200400906
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Palladium(ii) and Platinum(ii) Complexes with Crown Ether Phosphane Ligands
FULL PAPER
phane 2 by crystallization failed because of its high solubil-
The platinum (10–12) and palladium (13–15) complexes
ity in water and polar organic media (see below). Moreover, [MCl2(PAr*nR3–n)2]2 were prepared by the displacement of
only the oxide 5 was collected from chromatography col- the labile ligand in [MCl2(COD)] or [MCl2(PhCN)2]
umns of silica gel or alumina even if an inert atmosphere (Scheme 2). Palladium complex 13 has already been re-
and deoxygenated solvents were employed. Although triar- ported[5,6] and is described here only for comparative pur-
ylphosphanes are more stable, both 1 and 3 were trans- poses. The platinum complexes are white solids containing
formed quantitatively into their oxides 4 or 6 when stirred only the cis isomers, whereas the palladium ones are yellow
under an air atmosphere for three days at room tempera- and were obtained as cis-trans mixtures. The cis-trans ratios
ture.
obtained (cis amount: traces for 13, 60% for 14, and 30%
for 15) are independent of the starting material,
[PdCl2(COD)] or [PdCl2(PhCN)2]. The cis and trans iso-
mers of 15 were separated on the basis of their different
solubility in toluene. The assigned stereochemistry is in
agreement with the following experimental data and obser-
2
vations: (a) the order of the J(31P-31P) coupling constant,
estimated from second-order analysis of the 1H NMR
methyl resonance of PAr*2Me complexes,[20] and the ring
13C signals (see below); (b) the number of ν(M–X) IR ab-
sorptions, two (A1 + B1) for cis, but one (B1u) for trans;
(c) in square-planar [MCl2(PR3)2] complexes, it has been
observed that lower field phosphorus chemical shifts corre-
spond to cis and higher field chemical shifts to trans iso-
Scheme 1.
The formation of borane adducts is a classical method mers in PdII complexes, whereas the reverse is true for PtII;
for the protection of phosphanes against oxidation during (d) the estimated phosphorus chemical shift value em-
purification or synthetic steps (the borane group also plays ploying the reported[21] empirical correlation between the
an activation role in the latter).[18] For the synthesis of the chemical shifts of free and coordinated phosphanes; esti-
borane complexes 7–9, an equimolar solution of BH3·THF mated/experimental values are δ = 34.7/33.0 (cis-13), 23.3/
was treated with the purified phosphanes (only for 1 and 3) 24.1 (trans-13), 18.4/19.7 (cis-14), 9.0/7.7 (trans-14), 35.1/
or, alternatively, added directly to the crude product ob- 33.4 (cis-15), and 23.7/23.8 ppm (trans-15); (e) for Pt com-
tained during their preparation. In both cases pure samples plexes, yellow colors are typical of trans isomers whereas
1
of 7–9 were obtained in high yields as white, air-stable sol- cis isomers are usually white;[22] the J(31P-195Pt) value is
ids after crystallization from ethanol/methanol. The depro- typically in the range of 2200–2500 Hz for trans and 3500–
tected phosphanes 1–3 were recovered from their borane 3700 Hz for cis-[PtCl2(PR3)2] complexes (3641–3673 Hz for
adducts 7–9 by decomplexation with an excess of the di- cis 10–12).[23]
amine ligand 1,4-diazabicyclo[2.2.2]octane (DABCO). A
mixture of phosphane, DABCO, and DABCO·BH3 com-
posed the crude product, from which the phosphanes 1 and
3 were easily separated by crystallization. Again, the prop-
erties of 2 complicated the purification of this phosphane,
although almost pure samples could be obtained by re-
peated washings with hexane and long high-vacuum treat-
ments. In practice, we limited the purification step to a
short high-vacuum treatment until complete sublimation of
Scheme 2.
the DABCO. Samples thus obtained consisted of a 1.6:1
Spectroscopic and analytical data for compounds 2–15
mixture of phosphane 2 and DABCO·BH3 and were appro- are given in the Experimental Section. For the assignment
priate for the synthesis of the complexes described here. A of 1H and 13C NMR signals and the determination of coup-
clear difference was observed in the complexation/decom- ling constants, we applied a combination of selective and
plexation process between triarylphosphanes 1 and 3 and broadband ({1H} and {31P}) decoupling techniques to-
methylphosphane 2. Complexation of the former with gether with the simulation of second-order spectra. The 31
P
BH3·THF is slower (at room temperature, 24 h for 1 and 3, nuclei of the crown ether aryl derivatives 2–15 resonate al-
and 4 h for 2) but decomplexation seems to be easier (4 h most at the same position as their parent phenyl analogs
at 40 °C and 1.2 equiv. of DABCO for 1 and 3, 5 h at THF (PPh2Me and PPh3). For example, the 31P NMR chemical
reflux and 3.5 equiv. of DABCO for 2). The enhanced shifts for the pair PAr*2Me (2)/PPh2Me are as follows (in
strength of the P–B bond in the more electron-rich phos- CDCl3): δ = –25.6/–28 ppm for the free phosphane,[24] δ =
phane 2 is presumably responsible for these observations. It 0.9/–1.2 ppm for the cis platinum complex,[25] and δ = 7.7/
has been pointed out that BH3 decomplexation by amine 7.8 ppm for the trans palladium complex.[26] Therefore, the
exchange can be an inefficient process for electron-rich, ste- steric requirements and electronic properties imposed by
rically hindered phosphanes.[19]
the Ar* group to the phosphane ligand are possibly very
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J. Fresneda, E. de Jesús, P. Gómez-Sal, C. López Mardomingo
FULL PAPER
similar to those of a Ph group. In fact, Storhoff et al.[11] 14 Hz]. Finally, pseudo triplets for ipso Ph, ipso Ar*, or Me
have evaluated the donor/acceptor characteristics of several carbons are observed in the trans complexes, according to
crown ether containing phosphanes, including 1, from the the larger P–P coupling constants. The simulated spectra of
A1 ν(CO) bands for [Ni(CO)3L] complexes.[27] They re- the Ar* protons match the experimental ones satisfactorily
ported that the PPh2Ar* complex absorbs 0.6 cm–1 lower when P–P couplings of 0 (for cis-Pd), approx. 12 Hz (for
than the PPh3 analog, thus indicating that the donor ability cis-Pt), and Ͼ100 Hz (for trans-Pd) are considered in the
of crown ether phosphane 1 is apparently only slightly second-order interpretation.
greater than that of triphenylphosphane. The steric bulk of
The solubility of catalysts in water is a relevant parame-
phosphanes is typically expressed in terms of cone angles, ter when considering processes in this media. Triarylphos-
usually the Tolman cone angle, θTol, originally derived from phanes 1 and 3 are only slightly soluble in water. Within
space-filling models,[28] or the Musco cone angle, θMus, de- this reduced solubility, the affinity for water increases with
rived from phosphane X-ray diffraction data.[29] The esti- the number of crown-ether aryl groups as shown by the
mation of these angles from the 31P NMR spectroscopic measured water/toluene distribution constants (7.4×10–3
data of trans-[PdCl2(PR3)2] complexes is possible because for 1, 1.46×10–3 for 3). In contrast, the methylphosphane
an empirical linear relationship has been demonstrated be- 2 is exceptionally water soluble. These differences are re-
tween the 31P chemical shift and θ.[30] As remarked above, flected in their metal complexes; for example, the palladium
chemical shifts of crown ether complexes trans- triarylphosphane complex 10 is poorly soluble in water
[PdCl2(PAr*3–nRn)2] [δ = 24.1 (13), 7.7 (14), and 23.8 ppm (0.002 g/100 mL), whereas the palladium methyldiarylphos-
(15)] match almost exactly those of the related non-crown phane complex 11 has a remarkable solubility (Ͼ10 g/
ether trans-[PdCl2L2] [δ = 24.4 (L = PPh3),[31] 7.8 ppm (L = 100 mL).
PPh2Me)[26]]. Thus, it is predicted that Ar* phosphanes
should have identical cone angles to Ph phosphanes. The
estimated[32] values are θTol = 131° and 147°, and θMus
126° and 134° for methyldiaryl and triarylphosphanes,
=
Crystal Structure of Borane–Phosphane 9
respectively (actual values for PPh2Me and PPh3 are θTol
=
The molecular structure of borane complex
PAr*2Ph·BH3 (9) based on X-ray structural analysis is given
136° and 145°,[28] respectively).
The magnitude of the 13C–31P coupling constants is in Figure 1. In spite of the presence of two 18-crown-6 ether
highly dependent on structural parameters, such as the co- rings, the bond distances and angles around the phosphorus
ordination state of the P atom.[33] One-bond coupling con- atom, which are listed in Table 1, are almost equal to those
stants between ipso Ph or Ar* carbon-13 and phosphorus- of Ph3P·BH3.[35] For example, the mean P–Cipso and P–B
31 appear in a well-defined range for each type of com- distances and Cipso–P–Cipso and B–P–Cipso bond angles are,
1
pound: J(13C-31P) = 9–11 (2 and 3), 105–108 (4–6), 58–63 respectively, 1.811(4) and 1.917(5) Å, and 106.0(2)° and
(7–9), 68–71 (cis, 10–12), 55–65 (cis, 13–15), and 45– 112.6(2)° in 9, compared with 1.818 and 1.917 Å, and
55 Hz (trans, 13–15). The pattern of the 13C NMR signals 106.3° and 112.6° in Ph3P·BH3. Complex 9 adopts a three-
2
is a source of information about the magnitude of J(31P- fold rotor conformation, according to the Dance and
31P) coupling constants and serves to elucidate the cis-trans Scudder nomenclature,[36] with B–P–Cipso–Cortho torsion
stereochemistry of square-planar [MCl2(PR3)2] complexes. angles within the range 30.4–41.5° (mean: 36.8°). In con-
The Me, Ar*, or Ph 13C nuclei in 10–15 constitute the X trast, the conformation of Ph3P·BH3 is irregular, with two
part of an AAЈX spin system,[34] where A and AЈ are, rotor rings and the other parallel to the P–B bond. The
respectively, the nearest and the most distant 31P nuclei, for crown ether ring O(1)–O(6) is folded toward a face of the
which five symmetrically disposed spectral lines are ex- phenyl ring with an angle between crown and phenyl mean
pected. If we assume J(13C-31PAЈ) to be essentially zero, the planes of 129.3(1)°, whereas the disposition of the crown
actual appearance of the 13C resonance lies between two ether O(7)–O(12) is almost coplanar [angle between mean
limiting cases depending on the relative values of J(13C- planes = 172.4(1)°]. With respect to the plane defined by
2
31PA) and J(31PA-31PAЈ):[23] (a) a triplet produced by the the ipso carbon atoms [C(1), C(17), and C(33)], the crown
weakening of the two outer lines (resonances marked as O(1)–O(6) is placed completely within the semispace oppo-
pseudo triplets in the Experimental Section), favored by site the P–B bond (endo orientation), whereas O(7)–O(12)
2
2
larger J(31PA-31PAЈ) values; (b) lower J(31PA-31PAЈ) values has an exo orientation, with half of the crown atoms situ-
favor an apparent doublet of doublets (or a doublet in the ated in each semispace. The crystallographic cone angle cal-
limiting case) due to the vanishing of the central line culated[37] for the phosphane PAr*2Ph (3) in the solid-state
(pseudo dd or d in the experimental section). For cis-Pd structure of complex 9 is very large (175°). However, single
complex 15, all the carbons are split into doublets when crystallographic cone angles of ligands with significant con-
2
coupled with 31P, as expected for J(31PA-31PAЈ) Ϸ 0. For formational freedom are not relevant in describing steric
cis-Pt complexes, the carbons coupled to 31P appear as effects in solution and are only representative of the confor-
pseudo triplets, except those with the largest J(13C-31PA) mation adopted in the particular structure. In this sense,
(ipso Ph, ipso Ar*, and Me carbons), which are observed as the conformation adopted by the crown ether groups in the
pseudo dd or d [a quantitative analysis of ipso Ph and ipso solid structure of 9 (exo-endo) is better ascribed to crystal-
Ar* resonances gives an estimation for 2J(31PA-31PAЈ) of 10– packing forces than to intermolecular interactions; chang-
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Palladium(ii) and Platinum(ii) Complexes with Crown Ether Phosphane Ligands
FULL PAPER
ing the conformation to an endo-endo disposition reduces stability of methyldiarylphosphane towards oxidation). Sur-
the cone angle to 160°. This value is only slightly larger prisingly, Beletskaya and co-workers[40] reported yields of
than that of PPh3 in Ph3P·BH3 (155°).[38]
about 85% when employing 1:2 mixtures of PdCl2 and the
monosulfonated phosphane P(m-C6H4SO3Na)Ph2. Reac-
tions with [PdCl2(COD)] and [PdCl2(PPh3)2] proceed in 62
to 75% yields, normally with decomposition of the catalysts
and formation of Pd0.[43]
Scheme 3.
Figure 1. View of the molecular structure of 9 with the atom-num-
bering scheme.
Table 2. Yields in reactions of ArI with PhSnCl3 in the presence of
palladium complexes 14 and 15 in aqueous alkaline medium.
Aryl iodide
Product
Catalyst[a]
Yield[b]
Table 1. Selected bond distances [Å] and angles [°] for 9.
p-NH2C6H4I p-NH2C6H4-C6H5 [PdCl2(COD)]
p-NH2C6H4I p-NH2C6H4-C6H5 [PdCl2(PPh3)2]
p-NH2C6H4I p-NH2C6H4-C6H5 [PdCl2(PAr*2Me)2] (14) 95%
p-NH2C6H4I p-NH2C6H4-C6H5 [PdCl2(PAr*2Ph)2] (15) 98%
62%
75%
P–B
1.917(5)
1.805(4)
1.812(4)
1.817(4)
113.0(2)
112.7(2)
112.3(2)
105.6(2)
106.5(2)
106.2(2)
[c]
[c]
P–C(1)
P–C(17)
p-CH3C6H4I p-CH3C6H4-C6H5
p-CH3C6H4I p-CH3C6H4-C6H5
p-CH3C6H4I p-CH3C6H4-C6H5
[PdCl2(PPh3)2]
[PdCl2(PAr*2Me)2] (14) 86%
[PdCl2(PAr*2Ph)2] (15) 98%
69%
P–C(33)
C(1)–P–B
C(17)-P–B
C(33)-P–B
C(1)–P–C(17)
C(17)–P–C(33)
C(33)–P–C(1)
[a] 1.0 mol-% with respect to the aryl iodide. See Experimental Sec-
tion for details. [b] Yield of isolated product based on starting ArI.
Differences up to 100% were mainly due to unchanged ArI. [c] The
reaction proceeded quantitatively and neither starting aryl iodide
1
nor by-products were detected by H NMR spectroscopy or TLC.
Conclusions
Palladium-Catalyzed Stille Couplings of
Phenyltrichlorostannanes and Aryl Halides in Aqueous
Solution
We have synthesized the new hybrid phosphane crown
ether molecules PAr*2Me (2) and PAr*2Ph (3), where Ar*
= 3,4-(18-crown-6)-phenyl, and their BH3, PtCl2, and PdCl2
complexes. Because of the conformational flexibility of the
crown ether substituents, the available data suggest that
compounds 1–3 are isosteric to the corresponding phenyl-
phosphane ligands (PPh2Me or PPh3). If we consider, in
addition, the electronic similarity between crown and non-
crown ligands, we can conclude that 1–3 are good alterna-
tives to PPh2Me and PPh3 when working in aqueous me-
dium. Moreover, the methylphosphane PAr*2Me (2) fur-
nishes to their complexes a water solubility comparable to
those of sulfonated phosphanes. However, solubility is not
the only parameter to be considered, as shown by the fact
that the only slightly water-soluble phenylphosphane
PAr*2Ph (3) gives the best yields in the Stille coupling reac-
tions in water here studied. Taking into account these pre-
liminary but promising results in catalysis, the work here
undertaken is being pursued with the synthesis of new
crown ether phosphanes and a more detailed study of Stille
and other C–C coupling reactions in water.
In 1993, Zhang and Daves[39] reported the achievement
of Stille coupling reactions in aqueous media that they had
been unable to accomplish in nonaqueous solvents. How-
ever, reactions carried out in water alone gave very low
yields owing to the limited solubility of the reactants. Belet-
skaya[40] and Collum[41] independently reported successful
couplings in water alone, thanks to the application of alkyl-
trichlorostannanes instead of tetraorganotin compounds;
the former are less toxic and expensive, and produce water-
soluble anionic alkylhydroxostannates in situ in aqueous al-
kaline solution. The catalyst employed was PdCl2 with or
without the addition of sulfonated water-soluble phosphane
[40]
ligands such as P(m-C6H4SO3Na)Ph2
or P(m-
C6H4SO3Na)2Ph,[41] or, in
a recent paper by Wolf,
P(OH)(tBu)2.[42]
We chose the coupling of PhSnCl3 and p-iodotoluene or
p-iodoaniline, under the Belestkaya–Collum conditions
(Scheme 3), to test the efficiency of the palladium com-
plexes 14 and 15 as aqueous-phase catalysts. [PdCl2(COD)]
and [PdCl2(PPh3)2] were also tested as a reference. Table 2
summarizes our results. Yields were especially high (Ͼ86%)
for both crown catalysts 14 or 15, but the less-soluble cata-
lyst 15 gave quantitative yields whereas those of the highly
Experimental Section
Reagents and General Techniques: All operations were performed
soluble 14 were a bit lower (may be because of the lower under an argon atmosphere by using Schlenk or dry-box tech-
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J. Fresneda, E. de Jesús, P. Gómez-Sal, C. López Mardomingo
FULL PAPER
niques. Solvents were dried and distilled under argon and degassed
prior to use, as described elsewhere.[44] Unless otherwise stated, rea-
gents were obtained from commercial sources and used as received.
PAr*Ph2 (1),[6,9] [PtCl2(COD)], and [PdCl2(COD)][45] were prepared
according to reported procedures. 1H, 13C, 31P, and 11B NMR spec-
tra were recorded on Varian Unity 300 or 500 Plus spectrometers.
below –90 °C over a period of 60 min and then the reaction mixture
was allowed to warm up to room temperature in the course of 3 h.
Stirring was continued overnight. The solvent was removed in
vacuo and the resulting residue was extracted with dichlorometh-
ane (3×30 mL). The dichloromethane was removed under reduced
pressure to provide a colorless oil. Pure 3 (0.390 g, 83%) was ob-
Chemical shifts (δ, ppm) are relative to SiMe4 (1H, 13C), 85% tained by crystallization of the crude from a mixture of absolute
H3PO4 (31P), or F3B·OEt2 (11B), and were measured by internal
referencing to the deuterated solvent (13C and residual 1H reso-
nances), or by the substitution method (31P and 11B references).
Coupling constants (J) are given in hertz. The ring-numbering sys-
tem employed in the description of NMR spectroscopic data is
given in Figure 2. In 13C NMR, JP virtual of pseudo triplets (see Re-
sults and Discussion) corresponds to J(13C–31PA) + J(13C–31PAЈ).
IR spectra were recorded on a Perkin–Elmer Spectrum 2000 FT-IR
spectrometer and data are given in cm–1. The Analytical Services of
the Universidad de Alcalá performed the C, H, and N analyses in
a Heraeus CHN-O-Rapid microanalyzer, and the MS-ESI+ mass
spectra in an Automass Multi, ThermoQuest. MALDI-TOF mass
spectra were recorded by the Analytical Services of the Universidad
Autónoma de Madrid.
ethanol and methanol (9:1). C38H51O12P (730.79): calcd. C 62.46,
H 7.03; found C 62.21, H 6.89. H NMR (CDCl3, 500 MHz): δ =
1
7.28 (m, 3 H, Ph), 7.22 (m, 2 H, Ph), 6.81 (m, 6 H, Ar*), 4.13 (m,
4 H, CH2 crown), 4.01 (m, 4 H, crown), 3.91 (m, 4 H, crown), 3.83
(m, 4 H, crown), 3.75 (m, 4 H, crown), 3.74–3.68 (m, 12 H, crown),
3.67 (s, 8 H, crown) ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ =
149.68 [s, Ar*(C4)], 148.84 [d, JP = 9.0, Ar*(C3)], 138.13 [d, JP
10.6, Ar*(Cipso)], 133.18 [d, JP = 18.9, Ph(Cortho)], 128.98 [d, JP
=
=
8.7, Ph(C1)], 128.38 [s, Ph(Cpara)], 128.33 [d, JP = 6.7, Ph(Cmeta)],
127.31 [d, JP = 20.0, Ar*(C6)], 119.10 [d, JP = 22.5, Ar*(C2)],
113.73 [d, JP = 8.3, Ar*(C5)], 70.90, 70.79, 70.75, 69.68, 69.57,
69.05, 68.91 (s, CH2 crown) ppm. 31P{1H} NMR (CDCl3,
202 MHz): δ = –4.4 ppm.
P(O)Ar*Ph2 (4): Phosphane PAr*Ph2 (1) (0.15 g, 0.30 mmol) was
dissolved in CHCl3 (10 mL). The solution was stirred at room tem-
perature for 3 d under an air atmosphere. Subsequently, the solvent
was evaporated to dryness and the residue crystallized from ethanol
at –25 °C to give pure oxide 4 as a white solid (0.13 g, 84%).
C28H33O7P (512.54): calcd. C 65.62, H 6.49; found C 65.71, H 6.42.
1H NMR (CDCl3, 300 MHz): δ = 7.62 [m, JP = 11.9, 4 H, Ph-
(Hortho)], 7.50 [m, 2 H, Ph(Hpara)], 7.42 [m, 4 H, Ph(Hmeta)], 7.22
[dd, JP = 12.1, JH6 = 1.8, 1 H, Ar*(H2)], 7.03 [ddd, JP = 12.1, JH5
= 8.1, 1 H, Ar*(H6)], 6.86 [dd, JP = 3.1, 1 H, Ar*(H5)], 4.16 (m, 2
H, CH2 crown), 4.08 (m, 2 H, crown), 3.91 (m, 2 H, crown), 3.84
(m, 2 H, crown), 3.77–3.66 (m, 12 H, crown) ppm. 13C{1H} NMR
(CDCl3, 75 MHz): δ = 152.09 [s, Ar*(C4)], 148.90 [d, JP = 14.7,
Ar*(C3)], 132.89 [d, JP = 104.7, Ph(Cipso)], 131.89 [d, JP = 14.0,
Ph(Cortho)], 128.41 [d, JP = 11.8, Ph(Cmeta)], 131.79 [d, JP = 2.9,
Ph(Cpara)], 126.27 [d, JP = 11.6, Ar*(C6)], 124.12 [d, JP = 108.4,
Ar*(C1)], 116.87 [d, JP = 11.1, Ar*(C2)], 112.81 [d, JP = 14.7,
Ar*(C5)], 70.98, 70.94, 70.83, 70.75, 70.68, 69.49, 69.41, 69.23,
68.94 (s, CH2 crown) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ =
30.5 ppm.
Figure 2. Selected 13C{1H} chemical shifts (in ppm) and coupling
constants (in Hz) for compounds 2–15, with the ring-labeling
scheme employed in the Experimental Section.
PAr*2Me (2): The procedure described below for 3 was used for
the synthesis of phosphane 2 (0.28 g, 65%) as a colorless oil start-
ing from 4-bromobenzo-3,4-(18-crown-6) (0.500 g, 1.28 mmol), a
1.6 m hexane solution of n-butyllithium (0.88 mL, 1.41 mmol), and
a 1.0 m solution of dichloromethylphosphane in hexane (0.70 mL,
0.70 mmol). However, this phosphane could not be purified by
crystallization as described for 3, because of its high solubility in
water and polar organic media such as methanol or THF. 1H NMR
(CDCl3, 500 MHz): δ = 6.93 [td, JP = 7.0, JH5 = 7.8, JH2 = 1.7, 2
H, Ar*(H6)], 6.87 [dd, JP = 7.5, 2 H, Ar*(H2)], 6.82 [dd, JP = 1.3,
2 H, Ar*(H5)], 4.12 (m, 4 H, CH2 crown), 4.07 (m, 4 H, crown),
3.90 (m, 4 H, crown), 3.87 (m, 4 H, crown), 3.74 (m, 8 H, crown),
3.70 (m, 8 H, crown), 3.66 (s, 8 H, crown), 1.51 (d, JP = 3.3, 3 H,
Me) ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ = 149.53 [s,
Ar*(C4)], 148.38 [d, JP = 8.1, Ar*(C3)], 132.23 [d, JP = 10.3,
Ar*(C1)], 125.46 [d, JP = 19.9, Ar*(C2)], 118.02 [d, JP = 21.4,
Ar*(C6)], 114.00 [d, JP = 8.1, Ar*(C5)], 70.85, 70.78, 70.75, 69.65,
69.61, 69.30, 69.03 (s, CH2 crown), 13.24 (d, JC,P = 8.1, Me) ppm.
31P{1H} NMR (CDCl3, 202 MHz): δ = –25.6 ppm.
P(O)Ar*2Me (5) and P(O)Ar*2Ph (6): The procedure described
above for 4 was used for the synthesis of phosphane oxides 5
(0.084 g, 55%) from 2 (0.150 g, 0.224 mmol), and 6 (0.138 g, 90%)
from 3 (0.150 g, 0.205 mmol). The latter was obtained as an oil
which was purified by chromatography on a silica gel column using
a 1:1 mixture of toluene and ethanol as the mobile phase.
5: C33H49O13P (684.72): calcd. C 57.89, H 7.21; found C 57.95, H
1
7.08. MS (ESI+): m/z = 707.3 (calcd. for MNa+: 707.0). H NMR
(CDCl3, 500 MHz): δ = 7.19 [dd, JP = 12.3, JH6 = 1.9, 2 H,
Ar*(H2)], 7.13 [ddd, JP = 12.0, JH5 = 8.0, 2 H, Ar*(H6)], 6.87 [dd,
JP = 2.9, 2 H, Ar*(H5)], 4.15 (m, 4 H, CH2 crown), 4.13 (m, 4 H,
crown), 3.91 (m, 4 H, crown), 3.89 (m, 4 H, crown), 3.78 (m, 8 H,
PAr*2Ph (3): In a 100-mL round-bottomed flask equipped with a
low-temperature thermometer, a magnetic stirrer, and a dropping
funnel, 4-bromobenzo-3,4-(18-crown-6) (0.500 g, 1.28 mmol) was
dissolved in freshly distilled THF (60 mL) and cooled in a meth-
anol/liquid nitrogen slush. The temperature was lowered to –95 °C
and then a 1.6 m hexane solution of n-butyllithium (0.88 mL,
1.41 mmol) was added dropwise to the cooled and stirred solution,
keeping the temperature below –92 °C. The stirring was continued
for 90 min while the temperature was carefully maintained in the
stated range. Then, dichlorophenylphosphane (0.10 mL,
0.73 mmol) dissolved in THF (1 mL) was added gradually to the
stirred mixture over a period of 10 min. The temperature was kept
crown), 3.73 (m, 8 H, crown), 3.65 (s, 8 H, crown), 1.91 (d, JP
=
13.2, 3 H, Me) ppm. 13C{1H} NMR (CDCl3, 126 MHz): δ = 151.81
[s, Ar*(C4)], 148.85 [d, JP = 14.5, Ar*(C3)], 125.95 [d, JP = 106.2,
Ar*(C1)], 124.30 [d, JP = 10.6, Ar*(C2)], 115.49 [d, JP = 11.7,
Ar*(C6)], 112.87 [d, JP = 15.0, Ar*(C5)], 70.87, 70.81, 70.75, 70.67,
70.66, 70.60, 69.42, 69.32, 69.15, 68.82 (s, CH2 crown), 16.99 (d, JP
= 75.5, Me) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ =
31.5 ppm.
6: C38H51O13P (746.79): calcd. C 61.12, H 6.88; found C 60.97, H
6.82. 1H NMR (CDCl3, 300 MHz): δ = 7.60 [m, JP = 12.1, 2 H,
1472
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 1468–1476

Palladium(ii) and Platinum(ii) Complexes with Crown Ether Phosphane Ligands
FULL PAPER
Ph(Hortho)], 7.50 [m, 1 H, Ph(Hpara)], 7.43 [m, 2 H, Ph(Hmeta)], 7.21
[dd, JP = 12.5, JH6 = 1.7, 2 H, Ar*(H2)], 7.00 [ddd, JP = 12.1, JH5
(0.250 g, 0.342 mmol). The presence of 1 equiv. of MeOH in the
crystalline white solid is suggested by the elemental analyses and
= 8.2, 2 H, Ar*(H6)], 6.86 [dd, JP = 2.9, 2 H, Ar*(H5)], 4.13 (m, 4 confirmed by NMR spectra (resonances of the methanol are omit-
H, CH2 crown), 4.01 (m, 4 H, crown), 3.91 (m, 4 H, crown), 3.83
ted in the spectroscopic data below). C38.5H56BO12.5P (760.65, in-
(m, 4 H, crown), 3.75 (m, 4 H, crown), 3.74–3.67 (m, 12 H, crown), cludes 1/2 a molecule of methanol): calcd. C 60.79, H 7.42; found
1
3.66 (s, 8 H, crown) ppm. 13C{1H} NMR (CDCl3, 126 MHz): δ =
C 60.74, H 7.36. H NMR (CDCl3, 500 MHz): δ = 7.49 [m, JP =
151.82 [s, Ar*(C4)], 148.87 [d, JP = 14.5, Ar*(C3)], 132.92 [d, JP
12.4, Ph(Cortho)], 131.52 [d, JP = 2.6, Ph(Cpara)], 130.01 [d, JP
105.6, Ph(Cipso)], 128.55 [d, JP = 11.5, Ph(Cmeta)], 126.68 [d, JP
=
=
=
10.8, 2 H, Ph(Hortho)], 7.47 [m, 1 H, Ph(Hpara)], 7.38 [m, 2 H,
Ph(Hmeta)], 7.08 [dd, JP = 11.4, JH6 = 1.8, 2 H, Ar*(H2)], 7.00 [ddd,
JP = 8.6, JH5 = 8.4, 2 H, Ar*(H6)], 6.85 [dd, JP = 2.6, 2 H, Ar*(H5)],
4.15 (m, 4 H, CH2 crown), 4.05 (m, 4 H, crown), 3.91 (m, 4 H,
12.0, Ar*(C6)], 124.02 [d, JP = 106.9, Ar*(C1)], 117.52 [d, JP = 12.1,
Ar*(C2)], 113.03 [d, JP = 14.3, Ar*(C5)], 70.93, 70.83, 70.80, 70.67, crown), 3.84 (m, 4 H, crown), 3.75 (m, 4 H, crown), 3.74–3.67 (m,
70.65, 70.42, 69.45, 69.18, 68.89 (s, CH2 crown) ppm. 31P{1H}
NMR (CDCl3, 202 MHz): δ = 31.3 ppm.
12 H, crown), 3.66 (s, 8 H, crown), 1.5–0.6 (very broad, BH3) ppm.
13C{1H} NMR (CDCl3, 75 MHz): δ = 151.50 [s, Ar*(C4)], 148.98
[d, JP = 13.3, Ar*(C3)], 132.89 [d, JP = 9.6, Ph(Cortho)], 130.95 [d,
JP = 3.0, Ph(Cpara)], 130.11 [d, JP = 58.2, Ph(Cipso)], 128.60 [d, JP
Ar*Ph2P·BH3 (7): PAr*Ph2 (1; 0.11 g, 0.22 mmol) was dissolved in
THF (20 mL) and a 1.0 m solution of BH3·THF in THF (0.22 mL,
0.22 mmol) was added with a syringe. The mixture was stirred at
room temperature for 24 h. The solvent was subsequently removed
under vacuum to give a white solid. Pure borane complex 7
(0.097 g, 85%) was obtained after crystallization of the crude pro-
duct from a mixture of absolute ethanol and methanol (18:1) at
–25 °C. C28H36BO6P (510.38): calcd. C 65.89, H 7.11; found C
66.01, H 7.08. MS (ESI+): m/z = 534.0 (calcd. for MNa+: 533.2),
520.0 (calcd. for MNa+ – BH3: 519.2). 1H NMR (CDCl3,
300 MHz): δ = 7.52 [m, JP = 10.8, 4 H, Ph(Hortho)], 7.47 [m, 2 H,
Ph(Hpara)], 7.43 [m, 4 H, Ph(Hmeta)], 7.10 [dd, JP = 11.4, JH6 = 1.8,
1 H, Ar*(H2)], 7.05 [ddd, JP = 10.4, JH5 = 8.2, 1 H, Ar*(H6)], 6.87
[dd, JP = 2.4, 1 H, Ar*(H5)], 4.15 (m, 2 H, CH2 crown), 4.05 (m,
2 H, crown), 3.91 (m, 2 H, crown), 3.84 (m, 2 H, crown), 3.74 (m,
2 H, crown), 3.71 (m, 2 H, crown), 3.70 (m, 2 H, crown), 3.68 (m,
2 H, crown), 3.65 (s, 4 H, crown), 1.5–0.6 (very broad, BH3) ppm.
13C{1H} NMR (CDCl3, 126 MHz): δ = 151.64 [d, JP = 2.2,
Ar*(C4)], 148.98 [d, JP = 12.8, Ar*(C3)], 133.03 [d, JP = 9.5, Ph-
(Cortho)], 132.04 [d, JP = 2.2, Ph(Cpara)], 129.65 [d, JP = 57.8,
Ph(Cipso)], 128.67 [d, JP = 10.0, Ph(Cmeta)], 127.38 [d, JP = 9.5,
Ar*(C6)], 120.07 [d, JP = 62.3, Ar*(C1)], 118.21 [d, JP = 12.8,
Ar*(C2)], 113.28 [d, JP = 12.23, Ar*(C5)], 70.94, 70.89, 70.80, 70.71,
70.67, 69.45, 69.37, 69.17, 68.88 (s, CH2 crown) ppm. 31P{1H}
NMR (CDCl3, 202 MHz): δ = 21.5 ppm.
= 10.3, Ph(Cmeta)], 127.17 [d, JP = 8.9, Ar*(C6)], 120.57 [d, JP
=
62.7, Ar*(C1)], 117.97 [d, JP = 12.5, Ar*(C2)], 113.17 [d, JP = 12.5,
Ar*(C5)], 70.90, 70.82, 70.78, 70.69, 70.63, 70.41, 69.36, 69.12,
68.84 (s, CH2 crown) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ =
21.0 ppm.
Decomplexation of Phosphane–Borane Complex 7: This was carried
out as described below for complex 9.
Decomplexation of Phosphane–Borane Complex 8: Complex 8
(0.044 g, 0.065 mmol) and 1,4-diazabicyclo[2.2.2]octane (DABCO)
(0.0174, 0.16 mmol) were dissolved in THF (5 mL). The mixture
was refluxed at 85 °C for 5 h and then allowed to cool to room
temperature. The solvent was removed under reduced pressure and
complete decomplexation was evidenced by 1H NMR spectroscopy.
The excess of DABCO was completely eliminated under high vac-
uum at room temperature and the DABCO·BH3 formed in the re-
action was partially removed in this treatment. The final product
was found to be a mixture of phosphane 2 and DABCO·BH3 (1.6:1,
1H NMR).
Decomplexation of Phosphane–Borane Complex 9: Complex 9
(0.22 g, 0.30 mmol) and the DABCO ligand (0.040, 0.36 mmol)
were dissolved in toluene (20 mL). The mixture was stirred at 40 °C
for 4 h. The solvent was removed under reduced pressure and the
crude product was identified as a 1:1 mixture of phosphane 3 and
complex BH3·DABCO (1H NMR), showing that decomplexation
was complete. Phosphane 3 (0.20 g, 90%) could be purified by
crystallization of the crude mixture with ethanol at –25 °C.
Ar*2MeP·BH3 (8): The procedure described above for 7 was used
for the synthesis of borane complex 8 starting from the crude pro-
duct 2 (0.35 g, 0.52 mmol) and a 1.0 m solution of BH3·THF in
THF (0.52 mL, 0.52 mmol). In this case, the reaction time was re-
duced to 4 h, and the crude product was recrystallized three times
from a mixture of absolute ethanol and methanol (18:1) at –25 °C
to provide 0.21 g (60%) of an analytically pure solid which was
identified as 8. C33H52BO12P (682.55): calcd. C 58.07, H 7.68;
found C 58.30, H 7.63. MS (ESI+): m/z = 706.0 (calcd. for MNa+:
705.3). IR (KBr pellets): ν(BH) = 2371 s. 1H NMR (CDCl3,
500 MHz): δ = 7.19 [dd, JP = 12.3, JH6 = 1.9, 2 H, Ar*(H2)], 7.13
[ddd, JP = 12.0, JH5 = 8.0, 2 H, Ar*(H6)], 6.87 [dd, JP = 2.9, 2 H,
Ar*(H5)], 4.15 (m, 4 H, CH2 crown), 4.13 (m, 4 H, crown), 3.91
(m, 4 H, crown), 3.89 (m, 4 H, crown), 3.78 (m, 8 H, crown), 3.73
(m, 8 H, crown), 3.65 (s, 8 H, crown), 1.74 (d, JP = 10.3, 3 H, Me),
1.3–0.5 (very broad, BH3) ppm. 11B{1H} NMR (CDCl3, 160 MHz):
δ = –39 ppm. 13C{1H} NMR (CDCl3, 126 MHz): δ = 151.52 [s,
Ar*(C4)], 148.97 [d, JP = 13.3, Ar*(C3)], 125.52 [d, JP = 8.9,
Ar*(C6)], 122.20 [d, JP = 60.5, Ar*(C1)], 117.25 [d, JP = 11.8,
Ar*(C2)], 113.55 [d, JP = 13.3, Ar*(C5)], 70.91, 70.85, 70.77, 70.68,
69.50, 69.39, 68.94 (s, CH2 crown), 12.5 (d, JP = 41.3, Me) ppm.
31P{1H} NMR (CDCl3, 202 MHz): δ = 10.2 ppm.
[PtCl2(PAr*Ph2)2] (10): The procedure described below for 12 was
used for the synthesis of platinum complex 10 starting from phos-
phane
1 (0.067 g, 0.13 mmol) and [PtCl2(PhCN)2] (0.028 g,
0.059 mmol). Complex 10 was obtained as a pure white solid con-
taining only the cis isomer (0.062 g, 83%). C56H66Cl2O12P2Pt
(1259.07): calcd. C 53.42, H 5.28; found C 53.11, H 5.31. MS
(ESI+): m/z = 1281.0 (calcd. for MNa+: 1280.3). IR (Nujol): ν(Pt–
Cl) = 318, 292. 1H NMR (CDCl3, 500 MHz): δ = 7.44 [m, 8 H,
Ph(Hortho)], 7.28 [m, 4 H, Ph(Hpara)], 7.14 [m, 8 H, Ph(Hmeta)], 7.09
[m, JP = 10.5, JH6 = 2.0, 2 H, Ar*(H2)], 6.93 [m, JP Ϸ 8, 2 H,
Ar*(H6)], 6.59 [dd, JP = 2.2, JH5 = 8.3, 2 H, Ar*(H5)], 4.10 (m, 4
H, CH2 crown), 3.90 (m, 4 H, crown), 3.76 (m, 8 H, crown), 3.74
(m, 8 H, crown), 3.69 (m, 8 H, crown), 3.66 (s, 8 H, crown) ppm.
13C{1H} NMR (CDCl3, 75 MHz): δ = 151.07 [d, JP = 2.2, Ar*(C4)],
147.67 [pseudo t, JP virtual = 14.4, Ar*(C3)], 134.44 [pseudo t,
JP virtual = 9.6, Ph(Cortho)], 130.47 [s, Ph(Cpara)], 130.01 [pseudo dd,
Japparent = 68.0 and 2.4, Ph(Cipso)], 129.01 [pseudo t, JP virtual = 9.6,
Ar*(C6)], 127.66 [pseudo t, JP virtual = 11.6, Ph(Cmeta)], 120.09
[pseudo dd, Japparent = 68.0 and 1.6, Ar*(C1)], 120.39 [pseudo t, JP
= 12.6, Ar*(C2)], 112.03 [pseudo t, JP = 12.8, Ar*(C5)], 70.93,
70.90, 70.79, 70.69, 70.58, 69.32, 68.92, 68.79 (s, CH2 crown) ppm.
Ar*2PhP·BH3 (9): The procedure described above for 7 was used
for the synthesis of borane complex 9 (0.308 g, 90%) from 3
Eur. J. Inorg. Chem. 2005, 1468–1476
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1473

J. Fresneda, E. de Jesús, P. Gómez-Sal, C. López Mardomingo
31P{1H} NMR (CDCl3, 202 MHz): δ = 15.1 (s with 195Pt satellites, Ar*(H2)], 7.40–7.30 [m, 12 H, Ph(Hmeta) and Ph(Hpara) overlap-
FULL PAPER
JPt = 3669 Hz).
ping], 7.14 [m, JP virtual = 10.4, JH5 = 8.4, 2 H, Ar*(H6)], 6.82 [br.
d, JP virtual Ϸ 2.0, 2 H, Ar*(H5)], 4.14 (m, 4 H, CH2 crown), 4.00
(m, 4 H, crown), 3.91 (m, 4 H, crown), 3.79 (m, 4 H, crown), 3.74
(m, 4 H, crown), 3.70–3.68 (m, 12 H, crown), 3.65 (s, 8 H, crown)
ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ = 151.03 [s, Ar*(C4)],
148.16 [pseudo t, JP virtual = 14.8, Ar*(C3)], 134.79 [pseudo t,
JP virtual = 11.8, Ph(Cortho)], 130.33 [s, Ph(Cpara)], 130.21 [pseudo t,
JP = 50.1, Ph(Cipso)], 128.94 [pseudo t, JP virtual = 11.8, Ar*(C6)],
127.90 [pseudo t, JP virtual = 8.8, Ph(Cmeta)], 121.08 [pseudo t,
JP virtual = 14.8, Ar*(C2)], 120.80 [pseudo t, JP virtual = 53.2,
Ar*(C1)], 112.76 [pseudo t, JP virtual = 5.6, Ar*(C5)], 70.97, 70.83,
70.79, 70.75, 70.66, 69.46, 69.05, 68.84 (s, CH2 crown) ppm.
31P{1H} NMR (CDCl3, 202 MHz): δ = 24.1 ppm.
[PtCl2(PAr*2Me)2] (11): Phosphane–borane complex 8 (0.044 g,
0.065 mmol) and DABCO (0.0174 g, 0.15 mmol) were refluxed in
THF for 5 h. The solvent was removed and the residue was treated
with 1 equiv. of [PtCl2(PhCN)2] (0.015 g, 0.032 mmol) in toluene
(5 mL). The mixture was stirred at room temperature for 15 h. Sub-
sequently, the solvent was removed in vacuo and the residue washed
with hexane. The crude product thus obtained, a mixture of cis-
11 and BH3·DABCO, was chromatographed on a neutral alumina
column using a 9:1 mixture of toluene and ethanol as mobile phase.
Complex 11 was obtained as a solid and the cis isomer (0.032 g,
63%). C66H98Cl2O24P2Pt (1603.42): calcd. C 49.44, H 6.16; found
C 49.20, H 6.08. MS (MALDI-TOF): m/z = 1624.4 (calcd. for
MNa+: 1624.48). IR (Nujol): ν(Pt–Cl) = 312, 285. 1H NMR [PdCl2(PAr*2Me)2] (14): The procedure described above for 11 was
(CDCl3, 500 MHz,): δ = 7.08 [m, JP = 12.1, 4 H, Ar*(H2)], 6.99
[m, JP Ϸ 8, 4 H, Ar*(H6)], 6.71 [dd, JH5 = 8.3, JP = 2.0, 4 H,
used for the synthesis of palladium complex 14 starting from 8
(0.064 g, 0.094 mmol), DABCO (0.041 g, 0.37 mmol), and
Ar*(H5)], 4.12 (m, 8 H, CH2 crown), 4.00–3.83 (m, 16 H, CH2 [PdCl2(COD)] (0.012 g, 0.042 mmol). Although complex 14 was
crown), 3.74–3.67 (m, 32 H, CH2 crown), 3.65 (s, 16 H, CH2
formed in greater than 95% yield (1H NMR evidence) as a pair of
crown), 1.79 (d, JP = 10.3, 6 H, Me) ppm. 13C{1H} NMR (CDCl3, cis/trans isomers (1:0.75), the resultant oil could not be purified by
126 MHz): δ = 151.35 [s, Ar*(C4)], 148.46 [pseudo t, JP virtual
13.4, Ar*(C3)], 126.65 [pseudo t, JP virtual = 11.2, Ar*(C6)], 122.23
=
crystallization or chromatography and was used in this form in
further catalytic studies. In the NMR spectroscopic data of the
[d, JP = 68.4, Ar*(C1)], 118.26 [pseudo t, JP virtual = 14.4, Ar*(C2)], unpurified cis/trans mixture that follows, resonances corresponding
112.81 [pseudo t, JP virtual = 14.4, Ar*(C5)], 70.91, 70.84, 70.79,
to the BH3·DABCO impurity are omitted, and the cis/trans ratio
70.74, 70.67, 70.62, 69.41, 69.38, 68.90 (s, CH2 crown), 17.71 (d, JP has been taken into account in integral values. IR (Nujol): ν(Pd–
1
= 47.8, Me) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ = 0.9 (s
with 195Pt satellites, JPt = 3641 Hz).
Cl) = 356 (trans), 287, 276 (cis). H NMR (CDCl3, 500 MHz,): δ
= 7.223 and 7.216 [overlapping m, JP Ϸ 10–14, 8 H, Ar*(H6) and
Ar*(H2) trans isomer], 7.07 [dd, JP = 12.4, JH6 = 1.9, 4 H, Ar*(H2)
cis isomer], 6.97 [ddd, JP = 11.8, JH5 = 8.3, 4 H, Ar*(H6) cis iso-
mer], 6.86 [br. d, JH6 = 8.4, JP not observed, 4 H, Ar*(H5) trans
isomer], 6.72 [dd, JP = 2.6, 4 H, Ar*(H5) cis isomer], 4.15–3.66
(overlapped m, 80 H, CH2 crown, cis and trans isomers), 1.96
(pseudo t, JP virtual = 7.1, 6 H, Me trans isomer), 1.91 (d, JP = 11.1,
3 H, Me cis isomer) ppm. 13C{1H} NMR (CDCl3, 126 MHz): δ =
151.49, 150.93 [s, Ar*(C4)], 148.65 [d, JP = 14.3, Ar*(C3) cis iso-
mer], 148.36 [pseudo t, JP virtual = 14.1, Ar*(C3) trans isomer], 126.8
[PtCl2(PAr*2Ph)2] (12): Phosphane 3 (0.185 g, 0.25 mmol) and
[PtCl2(PhCN)2] (0.060 g, 0.125 mmol) were dissolved in toluene
(5 mL). The mixture was stirred at room temperature for 15 h.
Then, the solvent was removed in vacuo, the residue washed several
times with hexane, and crystallized by addition of absolute meth-
anol to afford 12 as a white solid (0.198 g, 90%). Alternatively, the
reaction time was reduced to 1 h when [PtCl2(COD)] (COD = 1,5-
cyclooctadiene) was used instead of [PtCl2(PhCN)2]. In both cases,
only the cis isomer was detected. C76H102Cl2O24P2Pt (1727.56):
calcd. C 52.84, H 5.95; found C 52.78, H 5.98. IR (Nujol): ν(Pt–
[m, Ar*(C6) cis and trans overlapping], 123.61 [pseudo t, JP virtual
=
52.0, Ar*(C1) trans isomer], 122.78 [d, JP = 57.5, Ar*(C1) cis iso-
mer], 118.78 [pseudo t, JP virtual = 14.4, Ar*(C2) trans isomer],
118.22 [d, JP = 13.8, Ar*(C2) cis isomer], 113.00 [m, Ar*(C5) cis
and trans overlapping], 70.97, 70.95, 70.85, 70.82, 70.76, 70.69,
70.64, 69.48, 69.41, 69.24, 68.91, 68.85 (s, CH2 crown), 18.6 (over-
lapping d and m, Me) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ
= 19.7 (cis), 7.7 (trans).
Cl) = 317, 290. 1H NMR (CDCl3, 300 MHz): δ = 7.42 [m, JP
=
9.0, 4 H, Ph(Hortho)], 7.27 [m, 2 H, Ph(Hpara)], 7.15 [m, 4 H,
Ph(Hmeta)], 7.09 [m, JP = 12.0, JH6 = 1.8, 4 H, Ar*(H2)], 6.86 [m,
JP = 10.2, 4 H, Ar*(H6)], 6.57 [dd, JH5 = 8.5, JP = 2.3, 4 H,
Ar*(H5)], 4.11 (m, 8 H, CH2 crown), 3.90 (m, 8 H, crown), 3.75
(m, 16 H, crown), 3.70 (m, 16 H, crown), 3.67 (m, 16 H, crown),
3.65 (s, 16 H, crown) ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ =
151.02 [s, Ar*(C4)], 147.75 [pseudo t, JP virtual = 15.2, Ar*(C3)], [PdCl2(PAr*2Ph)2] (15): The procedure described above for 12 was
134.25 [pseudo t, JP virtual = 9.4, Ph(Cortho)], 131.00 [pseudo dd, used for the synthesis of palladium complex 15 starting from phos-
Japparent = 62.4 and 2.3, Ph(Cipso)], 130.38 [s, Ph(Cpara)], 128.88 phane (0.168 g, 0.25 mmol) and [PdCl2(PhCN)2] (0.048 g,
[pseudo t, JP virtual = 10.6, Ar*(C6)], 127.62 [pseudo t, JP = 11.4, 0.125 mmol). A yellow solid was obtained (0.20 g, 98%) that was
Ph(Cmeta)], 120.85 [pseudo dd, Japparent = 70.6 and 1.5, Ar*(C1)],
identified by NMR spectroscopy as a 3:7 mixture of cis/trans iso-
120.40 [pseudo t, JP = 13.2, Ar*(C2)], 112.04 [d, JP = 13.2, mers of complex 15. Both isomers were easily separated because
Ar*(C5)], 70.91, 70.85, 70.79, 70.72, 70.69, 70.56, 69.38, 69.31,
of their different solubility in toluene. The soluble cis isomer was
3
68.97, 68.79 (s, CH2 crown) ppm. 31P{1H} NMR (CDCl3, extracted in this solvent and subsequently crystallized from meth-
202 MHz): δ = 14.8 (s with 195Pt satellites, JPt = 3673 Hz).
anol whereas the insoluble residue containing the trans isomer was
crystallized from CH2Cl2/toluene. Both were obtained as deep-yel-
low solids.
[PdCl2(PAr*Ph2)2] (13): This complex has been previously reported
by Okano et al.[6] We employed the same procedure as described
above for 12. The crude product contains traces of the cis isomer
(δP = 33.0 ppm), but after crystallization complex 13 was obtained
as a pure yellow solid containing only the trans isomer (90%).
C56H66Cl2O12P2Pd (1170.41): calcd. C 57.47, H 5.68; found C
57.80, H 5.63. MS (ESI+): m/z = 1193.6 (calcd. for MNa+: 1192.2).
IR (Nujol): ν(Pd–Cl) = 359. 1H NMR (CDCl3, 300 MHz): δ = 7.62
[m, 8 H, Ph(Hortho)], 7.45 [td, JP virtual = 12.0, JH6 = 1.9, 2 H,
trans-15: C76H102Cl2O24P2Pd (1638.90): calcd. C 55.70, H 6.27;
found C 55.54, H 6.20. IR (Nujol): ν(Pd–Cl) = 356. 1H NMR
(CDCl3, 500 MHz): δ = 7.57 [m, JP = 12.4, 4 H, Ph(Hortho)], 7.40–
7.30 [m, 10 H, Ph(Hpara), Ph(Hmeta), and Ar*(H2) overlapping], 7.08
[m, JP = 10.3, JH5 = 8.5, JH2 = 2.0, 4 H, Ar*(H6)], 6.80 [br. d, 4
H, Ar*(H5)], 4.13 (m, 8 H, CH2 crown), 3.96 (m, 8 H, crown), 3.90
(m, 8 H, crown), 3.79 (m, 8 H, crown), 3.49 (m, 8 H, crown), 3.71–
1474
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 1468–1476

Palladium(ii) and Platinum(ii) Complexes with Crown Ether Phosphane Ligands
FULL PAPER
3.68 (m, 24 H, crown), 3.67 (s, 16 H, crown) ppm. 13C{1H} NMR
(CDCl3, 75 MHz): δ = 150.93 [s, Ar*(C4)], 148.98 [pseudo t, 5% p-iodoaniline) and purified by flash chromatography on silica
JP virtual = 14.8, Ar*(C3)], 134.59 [pseudo t, JP virtual = 11.8, Ph-
gel with toluene/ethanol (9:1) to give pure 4-aminobiphenyl
by HPLC-MS and H NMR spectroscopy (95% 4-aminobiphenyl,
1
(Cortho)], 130.81 [pseudo t, JP virtual = 45.4, Ph(Cipso)], 130.19 [s, (0.244 g, 95%).
Ph(Cpara)], 128.78 [pseudo t, JP virtual = 11.8, Ar*(C6)], 127.82
X-ray Structure Determinations: White, needle-shaped crystals of 9
[pseudo t, JP = 10.4, Ph(Cmeta)], 121.25 [pseudo t, JP virtual = 53.0,
Ar*(C1)], 120.86 [m, Ar*(C2), overlapping with Ar*(C1)], 113.17 [d,
JP = 12.5, Ar*(C5)], 70.98, 70.94, 70.85, 70.78, 70.65, 69.49, 69.13,
68.85 (s, CH2 crown) ppm. 31P{1H} NMR (CDCl3, 202 MHz): δ =
23.8 ppm.
were obtained from methanol/ethanol at –25 °C. A summary of
crystal data, data collection, and refinement parameters for the
structural analysis is given in Table 3. The crystal was glued to a
glass fiber and mounted on a Kappa-CCD Bruker–Nonius dif-
fractometer with area detector, and data were collected using
graphite monochromated Mo-Kα radiation (λ = 0.71073 Å). Data
collection was performed at 200 K, with an exposure time of 24 s
per frame (3 sets; 247 frames). Raw data were corrected for Lorenz
and polarization effects. The structure was solved by direct meth-
ods, completed by subsequent difference Fourier techniques, and
refined by full-matrix least-squares on F2 (SHELXL-97).[46] Aniso-
tropic thermal parameters were used in the last cycles of refinement
for the non-hydrogen atoms. Most of the hydrogen atoms were
found in the final Fourier map and were refined with isotropic ther-
mal displacement parameters, others were introduced in the last
cycle of refinement from geometrical calculations and refined using
a riding model. A molecule of methanol with important disorder
was located; the hydrogen atoms of the methyl group are not in-
cluded. All the calculations were made using the WINGX sys-
tem.[47]
cis-15: C76H102Cl2O24P2Pd (1638.90): calcd. C 55.70, H 6.27; found
C 55.78, H 6.19. IR (Nujol): ν(Pd–Cl) = 287, 276. 1H NMR
(CDCl3, 300 MHz): δ = 7.63 [m, JP = 12.6, 4 H, Ph(Hortho)], 7.45
[m, 2 H, Ph(Hpara)], 7.38 [m, 4 H, Ph(Hmeta)], 7.29 [dd, JP = 13.2,
JH6 = 1.8, 4 H, Ar*(H2)], 7.05 [ddd, JP = 12.1, JH5 = 8.4, 4 H,
Ar*(H6)], 6.80 [dd, JP = 2.5, 4 H, Ar*(H5)], 4.15 (m, 8 H, CH2
crown), 4.07 (m, 8 H, crown), 3.92 (m, 8 H, crown), 3.80 (m, 8 H,
crown), 3.75 (m, 8 H, crown), 3.71–3.68 (m, 24 H, crown), 3.67 (s,
16 H, crown) ppm. 13C{1H} NMR (CDCl3, 75 MHz): δ = 151.89
[d, JP Ϸ 1.0, Ar*(C4)], 148.30 [d, JP = 15.5, Ar*(C3)], 134.40 [d, JP
= 11.6, Ph(Cortho)], 131.51 [s, Ph(Cpara)], 128.76 [d, JP = 3.9,
Ar*(C6)], 128.31 [d, JP = 12.2, Ph(Cmeta)], 128.28 [d, JP = 54.7,
Ph(Cipso)], 120.09 [d, JP = 14.9, Ar*(C2)], 118.31 [d, JP = 64.7,
Ar*(C1)], 112.45 [d, JP = 15.5, Ar*(C5)], 71.01, 70.95, 70.86, 70.73,
70.71, 70.58, 69.39, 69.34, 69.26, 68.83 (s, CH2 crown) ppm.
31P{1H} NMR (CDCl3, 202 MHz): δ = 33.4 ppm.
CCDC-253624 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Water Solubility of Complexes 10 and 11: The extent of water solu-
bility was assessed by placing a small, accurately weighted quantity
of the compound in a vial, followed by slow addition of water,
with stirring, from a 50 μL syringe. Solubility measurements were
repeated several times to give an average value. Measured solubility
in water at 25 °C: 0.002 g/100 mL (10) and 10 g/100 mL (11).
Table 3. Crystallographic details for 9.
Empirical formula
Habit
C38H54BO12P·CH4O
needles
Distribution Coefficients Between Toluene and Water for Phosphanes
1 and 3: Previously, the UV spectra of phosphanes 1 and 3 were
registered in ethanol at several concentrations (from ca. 1×10–5 to
1×10–4 m). Two absorption bands were observed at λmax = 203 and
261 nm for 1, and 208 and 283 nm for 3. Fits of c versus A plots
showed a linear correlation in the entire range of concentrations
considered only in the case of the second maximum absorption (R2
Ͼ 0.999). Thus, the absorptions at 261 nm (ε = 12100) for 1, and
283 nm (ε = 13300) for 3 were used as follows in the determination
of distribution coefficients. A small, accurately weighted quantity
of phosphane (approx. 0.02 mmol) was added to a 1:1 mixture of
toluene and water (5 + 5 mL) that was stirred for 20 min at 25 °C.
An aliquot of the aqueous solution (2 mL) was removed with
Formula mass
a [Å]
b [Å]
c [Å]
β [°]
λ (Mo-Kα) [Å]
Temp. [K]
Space group
Crystal size [mm]
V [Å3]
776.67
18.7794(19)
8.5756(9)
26.566(4)
106.11(1)
0.71073
200(2)
monoclinic, P21/n
0.5×0.1×0.1
4110.3(9)
4
1.226
1.26
5.00 to 27.51
–24 Յ h Յ 24
–11 Յ k Յ 11
–34 Յ l Յ 23
25581
9222 [R(int) = 0.1577]
4238
9222/0/677
0.0984; 0.2027
1.013
Z
Dcalcd. [gcm–3]
μ [cm–1]
θ limits [°]
Limiting indices
a
pipette, evaporated to dryness, and dissolved in ethanol
(3 mL). The original water-phase concentration was determined
by measuring the concentration of phosphane in the ethanol
Reflections collected
Unique reflections
solution by UV spectroscopy, using the
c versus A plots
previously obtained. At 25 °C, distribution constants, defined as
[phosphane]aq/[phosphane]toluene, are 7.4×10–3 for 1, and 1.46×10–2
for 3.
Reflections observed with I Ͼ 2σ(I)
Data/restraints/parameters
R [I Ͼ 2σ(I)]; wR2 [a]
Goodness-of-fit indicator
Max. peak in final diff. map [eÅ–3]
Min. peak in final diff. map [eÅ–3]
Palladium-Catalyzed Stille Couplings: We used similar conditions
0.578
–0.390
to those previously described.[40,41] In
a typical experiment,
PhSnCl3 (0.31 mL, 1.824 mmol) was dissolved in 2 mL of degassed
water. The solution was treated with 5.5 mL of aqueous KOH (1
m) and stirred for several minutes. The p-iodoaniline (0.339 g,
1.52 mmol) and the Pd catalyst 14 (0.023 g, 0.0152 mmol) were
R = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]1/2
.
[a]
2
2 2
then added and the mixture was stirred for 3 h at 100 °C under Acknowledgments
argon. The product was extracted with diethyl ether and dried with
sodium sulfate. The solution was filtered off and the solvent re-
moved in vacuo to give a solid. The crude product was analyzed
We gratefully acknowledge financial support from the DGI-Minis-
terio de Ciencia y Tecnología (Project BQU2001-1160).
Eur. J. Inorg. Chem. 2005, 1468–1476
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1475

J. Fresneda, E. de Jesús, P. Gómez-Sal, C. López Mardomingo
FULL PAPER
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Received: October 26, 2005
1476
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Eur. J. Inorg. Chem. 2005, 1468–1476