Reversible ligand pairing and sorting processes leading to Heteroligated Palladium(II) complexes with hemilabile ligands

Article abstract of DOI:10.1021/om801060m

Halide-induced ligand pairing and sorting processes have been observed in the context of Pd(II) complexes with hemilabile P,S and P,0 ligands. Mixing of the ligands Ph₂PCH₂CH₂SMe (7) and Ph2PCH2CH2SPh (8) with a Pd(H) precursor in CH₂C1₂ results in a mixture of [(7)₂CIPd]CL [(8)₂Cl₂Pd], and [(7)(8)ClPd]Cl complexes at 20 °C. This equilibrium can be driven toward the heteroligated structure [(7)(8)ClPd]Cl by (1) cooling the mixture or (2) precipitation with hexanes, leading to the exclusive formation of semiopen heteroligated complex cis-[K²-(7)-K ¹-(8)ClPd]Cl (9a), as confirmed by a single-crystal X-ray diffraction study and solid state CPMAS ₃₁P₁H} NMR spectroscopy. Dissolution of 9a in CH2C12 leads to the original mixture of complexes, which illustrates the reversible nature of this ligand pairing and sorting process. Similar processes occur when a combination of P,S and P,0 ligands is used. The semiopen heteroligated complexes can be chemically manipulated in a reversible fashion to form closed complexes, allowing for control of the relative position and flexibility between neighboring substituents in these "tweezer"-like structures. Control experiments suggest these ligand sorting and pairing processes occur via a halide-induced ligand rearrangement (HILR) reaction.

Full text of DOI:10.1021/om801060m

1068
Organometallics 2009, 28, 1068–1074
Reversible Ligand Pairing and Sorting Processes Leading to
Heteroligated Palladium(II) Complexes with Hemilabile Ligands
Pirmin A. Ulmann,† Chad A. Mirkin,*,† Antonio G. DiPasquale,‡
Louise M. Liable-Sands,‡,§ and Arnold L. Rheingold‡
Department of Chemistry and the International Institute for Nanotechnology, Northwestern UniVersity,
2145 Sheridan Road, EVanston, Illinois 60208, Department of Chemistry and Biochemistry, UniVersity of
California, San Diego, 9500 Gilman DriVe, La Jolla, California 92093, and Chemistry Department,
Widener UniVersity, One UniVersity Place, Chester, PennsylVania 19013
ReceiVed NoVember 4, 2008
Halide-induced ligand pairing and sorting processes have been observed in the context of Pd(II) complexes
with hemilabile P,S and P,O ligands. Mixing of the ligands Ph2PCH2CH2SMe (7) and Ph2PCH2CH2SPh (8)
with a Pd(II) precursor in CH2Cl2 results in a mixture of [(7)2ClPd]Cl, [(8)2Cl2Pd], and [(7)(8)ClPd]Cl complexes
at 20 °C. This equilibrium can be driven toward the heteroligated structure [(7)(8)ClPd]Cl by (1) cooling the
mixture or (2) precipitation with hexanes, leading to the exclusive formation of semiopen heteroligated complex
cis-[κ2-(7)-κ1-(8)ClPd]Cl (9a), as confirmed by a single-crystal X-ray diffraction study and solid state CPMAS
31P{1H} NMR spectroscopy. Dissolution of 9a in CH2Cl2 leads to the original mixture of complexes, which
illustrates the reversible nature of this ligand pairing and sorting process. Similar processes occur when a
combination of P,S and P,O ligands is used. The semiopen heteroligated complexes can be chemically
manipulated in a reversible fashion to form closed complexes, allowing for control of the relative position and
flexibility between neighboring substituents in these “tweezer”-like structures. Control experiments suggest
these ligand sorting and pairing processes occur via a halide-induced ligand rearrangement (HILR) reaction.
in supramolecular coordination chemistry and in many cases
requires a template guest molecule.3c-e The ability to form AMB
structures offers a convenient way to control the relative position
of two different functional groups, appended to ligands A and
B, in one coordination complex, especially if aligned cofacially
in a “tweezer”-like fashion (Scheme 2). Such heteroligated
structures can be synthesized on the basis of the weak-link
approach (WLA)1c,h,4 and the halide-induced ligand rearrange-
ment (HILR) reaction1i,5 (Scheme 2). Since hemilabile P,X (X
) S, O) ligands are used, the relative distance and flexibility
between the functional sites can be regulated in situ using small
Introduction
The synthesis of supramolecular structures based on coordi-
nation chemistry has led to a variety of new materials and
compounds with novel shapes and reactivities.1 These structures
are frequently based on rigid ligands, resulting in highly
symmetric coordination assemblies. When multiple ligands are
mixed together that can form supramolecular structures by
coordination to transition metal ions, ligand self-pairing
behavior2a-i or the formation of mixtures of both self-paired
(homoligated) and complementary paired (heteroligated) struc-
tures2j,k is frequently observed (Scheme 1). The exclusive
formation of heteroligated AMB structures2h,i,3 via thermody-
namically controlled reactions has been less frequently reported
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* To whom correspondence should be addressed. Fax: (1) 847-467-5123.
E-mail: chadnano@northwestern.edu.
† Northwestern University.
‡ University of California, San Diego.
§ Widener University.
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10.1021/om801060m CCC: $40.75
2009 American Chemical Society
Publication on Web 01/27/2009

Heteroligated Pd(II) Complexes with Hemilabile Ligands
Organometallics, Vol. 28, No. 4, 2009 1069
Scheme 1. Homoligated and Heteroligated Complexes Based
on Ligands A and B and Metal Ion Ma
Thus far, heteroligated rearrangement processes are known
for Rh(I)-P,SAryl-P,OAryl5,6 and Pt(II)-P,SAlkyl-P,SAryl8 complexes
(3-6, Scheme 2). These assembly processes occur spontane-
ously and are independent of the order of addition of the
respective ligands. It has been shown that various functional
groups, including metalated porphyrins,6 are compatible with
the HILR reaction. Herein we describe an unusual ligand pairing
and sorting process that results in the formation of heteroligated
Pd(II) complexes. These complexes exist in the solid state and
in solution at low temperature, but spontaneously establish an
equilibrium between homoligated and heteroligated species in
solution at room temperature.
a
Ligands A and B belong to the same ligand class (e.g. pyridine,
phosphine, etc.). Additional ancillary ligands may be bound to M.
Results and Discussion
Synthesis of Heteroligated Pd(II)-P,SAlkyl-P,SAryl Complexes
9a,b and 12. When P,SAlkyl ligand 7, P,SAryl ligand 8, and
[Pd(COD)Cl2] (COD: 1,5-cyclooctadiene) are combined in
CH2Cl2, heteroligated semiopen complex 9a forms as the major
product (Scheme 3, Figure 1). It can be isolated and separated
from the COD byproduct via precipitation with hexanes.
Homoligated complexes 10 and 11, which have been character-
ized previously,9-11 also form as determined by 31P{1H} NMR
spectroscopy in CD2Cl2. Upon cooling to -20 °C, the 31P{1H}
NMR resonance associated with 10 almost disappears and the
(4) Farrell, J. R.; Mirkin, C. A.; Guzei, I. A.; Liable-Sands, L. M.;
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nikov, M. V.; Mirkin, C. A. Angew. Chem., Int. Ed. 2005, 44, 4207–4209.
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Mirkin, C. A. Chem. Commun. 2006, 4386–4388.
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Z. Inorg. Chem. 2007, 46, 7716–7718. (b) Oliveri, C. G.; Nguyen, S. T.;
Mirkin, C. A. Inorg. Chem. 2008, 47, 2755–2763.
Figure 1. Variable-temperature 31P{1H} NMR spectra (121.5 MHz)
of 9a dissolved in CD2Cl2.
(7) (a) Gianneschi, N. C.; Bertin, P. A.; Nguyen, S. T.; Mirkin, C. A.;
Zakharov, L. N.; Rheingold, A. L. J. Am. Chem. Soc. 2003, 125, 10508–
10509. (b) Gianneschi, N. C.; Cho, S. H.; Nguyen, S. T.; Mirkin, C. A.
Angew. Chem., Int. Ed. 2004, 43, 5503–5507. (c) Gianneschi, N. C.; Nguyen,
S. T.; Mirkin, C. A. J. Am. Chem. Soc. 2005, 127, 1644–1645. (d) Oliveri,
C. G.; Gianneschi, N. C.; Nguyen, S. T.; Mirkin, C. A.; Stern, C. L.;
Wawrzak, Z.; Pink, M. J. Am. Chem. Soc. 2006, 128, 16286–16296. (e)
Heo, J.; Mirkin, C. A. Angew. Chem., Int. Ed. 2006, 45, 941–944. (f) Masar,
M. S., III; Gianneschi, N. C.; Oliveri, C. G.; Stern, C. L.; Nguyen, S. T.;
Mirkin, C. A. J. Am. Chem. Soc. 2007, 129, 10149–10158. (g) Kuwabara,
J.; Stern, C. L.; Mirkin, C. A. J. Am. Chem. Soc. 2007, 129, 10074–10075.
(h) Yoon, H. J.; Heo, J.; Mirkin, C. A. J. Am. Chem. Soc. 2007, 129, 14182–
14183. (i) Yoon, H. J.; Mirkin, C. A. J. Am. Chem. Soc. 2008, 130, 11590–
11591.
Figure 2. ORTEP diagram of complex 9a. Thermal ellipsoids are
drawn at 30% probability. Hydrogen atoms and anions are omitted
for clarity. Selected bond lengths [Å] and angles [deg]: Pd1-P1
2.2540(12), Pd1-P2 2.3110(13), Pd1-S1 2.3674(13), Pd1-Cl1
2.3468(12),P1-Pd1-P297.87(4),S1-Pd1-Cl185.55(4),P2-Pd1-Cl1
90.67(4),P1-Pd1-S186.13(4),P1-Pd1-Cl1171.35(3),P2-Pd1-S1
172.30(3).
(8) Ulmann, P. A.; Brown, A. M.; Ovchinnikov, M. V.; Mirkin, C. A.;
DiPasquale, A. G.; Rheingold, A. L. Chem.-Eur. J. 2007, 13, 4529–4534.
(9) Del Zotto, A.; Mezzetti, A.; Rigo, P.; Bressan, M.; Morandini, F.;
Morvillo, A. Inorg. Chim. Acta 1989, 158, 151–158.
(10) Compound 10 exhibits only one 31P{1H} NMR resonance due to
an exchange process between the two phosphines that is fast on the NMR
timescale.9
(11) Examples of related Pd(II)-P, X (X ) S, N, O) complexes: (a)
Munk, V. P.; Sadler, P. J. Chem. Commun. 2004, 1788–1789. (b)
Habtemariam, A.; Watchman, B.; Potter, B. S.; Palmer, R.; Parsons, S.;
Parkin, A.; Sadler, P. J. J. Chem. Soc., Dalton Trans. 2001, 1306–1318.
(c) Eisenberg, A. H.; Ovchinnikov, M. V.; Mirkin, C. A. J. Am. Chem.
Soc. 2003, 125, 2836–2837. (d) Escriche, L.; Mun˜oz, J. A.; Kiveka¨s, R.;
Sillampa¨a¨, R.; Casabo´, J. Eur. J. Inorg. Chem. 2002, 2002, 3258–3263. (e)
Clot, O.; Wolf, M. O.; Patrick, B. O. J. Am. Chem. Soc. 2001, 123, 9963–
9973. (f) Eisenberg, A. H.; Dixon, F. M.; Mirkin, C. A.; Stern, C. L.;
Incarvito, C. D.; Rheingold, A. L. Organometallics 2001, 20, 2052–2058.
(g) Dervisi, A.; Jenkins, R. L.; Malik, K. M. A.; Hursthouse, M. B.; Coles,
S. Dalton Trans. 2003, 1133–1142. (h) Hou, D.-R.; Lin, T.-C.; Hsieh, T.-
Y.; Cheng, M.-C.; Peng, S.-M.; Liu, S.-T. Phosphorus Sulfur Silicon Relat.
Elem. 1996, 108, 61–73. (i) Sanger, A. R. Can. J. Chem. 1983, 61, 2214–
2219. (k) Zotti, G.; Pilloni, G.; Rigo, P.; Martelli, M. J. Electroanal. Chem.
1981, 124, 277–284. (l) Dyer, G.; Workman, M. O.; Meek, D. W. Inorg.
Chem. 1967, 6, 1404–1407. (m) Fritz, H. P.; Gordon, I. R.; Schwarzhans,
K. E.; Venanzi, L. M. J. Chem. Soc. 1965, 5210–5216.
Figure 3. Solid state 31P{1H} CPMAS NMR spectrum (161.8 MHz)
of 9a (spinning sidebands are not shown).
ancillary ligands via selective cleavage of the M-X bonds. On
the basis of this regulation capability, which is inherent to
complexes prepared via the WLA, biomimetic allosteric coor-
dination complexes and catalytic signal amplification systems
have been developed in homoligated (AMA) systems.1h,7

1070 Organometallics, Vol. 28, No. 4, 2009
Scheme 2. Formation of Heteroligated Rh(I) and Pt(II) Complexesa
Ulmann et al.
3a, 4a: M ) Rh(I), X ) O, R ) aryl; 3b, 4b: M ) Pt(II), X ) S, R ) alkyl; 5, 6: M ) Rh(I), R ) aryl; Ar: aryl, counterion: BF4-, NBD:
a
2,5-norbornadiene, COD: 1,5-cyclooctadiene.
Scheme 3. Formation of Heteroligated Pd(II)-P,SAlkyl-P,SAryl Complexes
resonance associated with 11 disappears completely, but both
resonances reappear upon warming to 20 °C. For 9a, the two
using Me4NCl (1 equiv) in MeOH/CH2Cl2. The presence of
BF4- as the counterion in 9b instead of chloride (9a) results in
the stabilization of the heteroligated semiopen compound in
solution. Addition of acetonitrile, which is known to coordinate
to Pd(II) with moderate strength,11f does not open complex 12,
a reflection of the more tightly bound thioether ligands.
Formation of Heteroligated Pd(II)-P,SAlkyl-P,OAryl Complexes
14a,b, 16, and 17. Mixing of P,S ligand 7 and P,O ligand 13
with [Pd(COD)Cl2] in CH2Cl2, followed by the removal of COD
via precipitation with hexanes, predominantly leads to hetero-
ligated complex 14a (Scheme 4). Indeed, 31P{1H} NMR
spectroscopy of the solution exhibits resonances at δ 61.2 (s)
and 22.3 (s), assigned to 14a, and two minor resonances at δ
44.8 (s) and 12.9 (s) assigned to complexes 10 and 15. Complex
10 is known9,10 and complex 15 has been synthesized via a
separate route and fully characterized in solution and by single-
crystal X-ray diffraction in the solid state (Figure 5). At -20
°C, resonances assigned to 10 and 15 are less intense, but
observable (see Experimental Section). Slow recrystallization
results in a pale yellow solid (80% yield) with an elemental
composition that is consistent with semiopen complex 14a.
31P{1H} CPMAS NMR spectroscopy in the solid state measured
on material obtained via precipitation of a CH2Cl2 solution of
the mixture (14a, 10, 15) with hexanes, followed by concentra-
tion in Vacuo, exhibits resonances at δ 63.9 (s) and 33.4 (s),
diagnostic of 14a.
2
resonances assigned to the two P ligands at δ 62.0 (d, JP-P
)
3 Hz) and 20.8 (d, 2JP-P ) 4 Hz) exhibit coupling to each other
at -20 °C. Slow recrystallization by layering of the reaction
mixture with hexanes results in colorless needles (78% yield)
that consist of 9a, according to a single-crystal X-ray diffraction
study (Figure 2) and elemental analysis.
In order to gain more information on the crystallization
process of compound 9a, a mixture of 9a, 10, and 11 (Figure
1), formed upon dissolution of analytically pure compound 9a
in CD2Cl2, was subjected to precipitation with hexanes and
isolation of the pale yellow powder by vacuum removal of
solvent, resulting in pure 9a, as evidenced by solid state 31P{1H}
CPMAS NMR spectroscopy (Figure 3). Indeed, only two
resonances at δ 65.7 (s) and 29.5 (s), consistent with 9a being
the only product in the solid state, are observed. Therefore, the
precipitation procedure does not simply lead to a selective
crystallization of 9a from the mixture of components, but rather
involves a shift in the equilibrium from 9a, 10, and 11 to
exclusively 9a upon precipitation/crystallization.
These results indicate that the relative distribution between
complexes 9a, 10, and 11 is thermodynamically controlled and
mediated by a dynamic equilibration process in solution.
Closed heteroligated complex 12 (Scheme 3) can be formed
in one-pot fashion by reacting ligands 7 and 8 with [Pd-
(COD)Cl2] with subsequent Cl- abstraction. Recrystallization
of the product from hexanes gave 12 (77% yield) and crystals
suitable for single-crystal X-ray diffraction (Figure 4). Complex
12 can be reopened to selectively give semiopen complex 9b
Closed complex 16 can be formed in 86% yield in a one-pot
procedure by mixing ligands 7 and 13 with [Pd(COD)Cl2]
followed by the addition of the Cl--abstracting agent, AgBF4
(Scheme 4). Single crystals of 16, suitable for X-ray analysis,

Heteroligated Pd(II) Complexes with Hemilabile Ligands
Organometallics, Vol. 28, No. 4, 2009 1071
Scheme 4. Formation of Heteroligated Pd(II)-P,SAlkyl-P,OAryl Complexes
were formed by the slow evaporation method (see Experimental
Section and Figure 6). Complex 16 can be reopened selectively
with Me4NCl (1 equiv) in MeOH/CH2Cl2, giving semiopen
complex 14b, or with excess acetonitrile,11f resulting in complex
17, according to 1H and 31P{1H} NMR and FT-IR spectroscopies.
These results show that the HILR reaction, in the context
of the ligands studied, occurs independent of the heteroatom in
the more weakly binding hemilabile ligand, which suggests that
the binding strength of this ligand can be systematically varied
to discriminate between small ancillary ligands of different
kinds, as shown for acetonitrile.
with a bond length of 2.35 Å, the other chloride ion is present
as an outer-sphere counterion with a Pd-Cl distance of 4.71
Å. Fully chelated κ2-P,SAlkyl/κ2-P,XAryl structures 12 · CH2Cl2 (X
) S, Figure 4) and 16 (X ) O, Figure 6) are similar to each
other, with the notable exception that the cis-oriented S-methyl
and S-phenyl groups in 12 · CH2Cl2 exhibit an anti relationship,
while the cis-oriented S-methyl and O-phenyl groups in structure
16 assume a syn relationship. Structure 15 (Figure 5) exhibits
a trans relationship between the two unchelated κ1-P,OAryl groups
with an anti relationship between the bulky PPh2 groups. Further
crystallographic data are presented in Table 1.
Crystal Structures 9a, 12 · CH2Cl2, 15, and 16. All crystal
structures exhibit distorted tetracoordinate square-planar geom-
etries with respect to the metal ion. In structure 9a (Figure 2),
the two P,S ligands coexist as five-membered κ2-P,SAlkyl chelated
and unchelated forms. While one chloride ion binds to Pd(II)
Figure 5. ORTEP diagram of complex 15. Thermal ellipsoids are
drawn at 30% probability. Hydrogen atoms and anions are omitted
for clarity. Selected bond lengths [Å] and angles [deg]: Pd1-P1
2.3172(7), Pd1-P2 2.3291(7), Pd1-Cl1 2.2998(6), Pd1-Cl2
2.2996(6),P1-Pd1-Cl194.10(2),P1-Pd1-Cl284.96(2),P2-Pd1-Cl1
85.48(2),P2-Pd1-Cl295.46(2),P1-Pd1-P2179.03(3),Cl1-Pd1-Cl2
178.73(3).
Figure 4. ORTEP diagram of complex 12 · CH2Cl2. Thermal
ellipsoids are drawn at 30% probability. Hydrogen atoms, solvent
molecules, and anions are omitted for clarity. Selected bond lengths
[Å] and angles [deg]: Pd1-P1 2.2778(11), Pd1-P2 2.2720(12),
Pd1-S1 2.3588(12), Pd1-S2 2.3814(12), P1-Pd1-P2 98.36(4),
S1-Pd1-S2 91.12(4), P1-Pd1-S2 85.51(4), P2-Pd1-S1 85.37(4),
P1-Pd1-S1 175.47(4), P2-Pd1-S2 171.82(4).
Scheme 5. Formation of Heteroligated Complex 9c upon
Iodide Addition to Homoligated Complexes 18 and 19
Figure 6. ORTEP diagram of complex 16. Thermal ellipsoids are
drawn at 30% probability. Hydrogen atoms and anions are omitted
for clarity. Selected bond lengths [Å] and angles [deg]: Pd1-P1
2.2291(6), Pd1-P2 2.2790(7), Pd1-S1 2.3881(8), Pd1-O1
2.1601(16),P1-Pd1-P297.47(2),S1-Pd1-O195.48(5),P1-Pd1-O1
176.35(5),P2-Pd1-S1175.09(2),P1-Pd1-S186.66(2),P2-Pd1-O1
80.26(5).

1072 Organometallics, Vol. 28, No. 4, 2009
Ulmann et al.
Table 1. Crystallographic Data for 9a, 12 · CH2Cl2, 15, and 16
9a
12 · CH2Cl2
15
16
formula
fw
color, habit
cryst dimens [mm]
space group
cryst syst
a [Å]
b [Å]
c [Å]
R [deg]
ꢀ [deg]
γ [deg]
V [Å3]
C35H36Cl2P2PdS2
760.00
C36H38B2Cl2F8P2PdS2
947.64
colorless blade
0.22 × 0.10 × 0.08
C2/c
monoclinic
37.697(4)
13.4866(12)
17.6277(17)
90
115.2870(10)
90
C40H38Cl2O2P2Pd
789.94
yellow block
0.28 × 0.16 × 0.10
P2(1)
monoclinic
9.9937(6)
18.6424(11)
10.6535(6)
90
116.0850(10)
90
C35H36B2F8OP2PdS
846.66
colorless plate
0.12 × 0.10 × 0.05
colorless plate
0.34 × 0.30 × 0.18
j
j
P1
P1
triclinic
triclinic
9.835(5)
12.815(7)
14.592(8)
102.884(7)
107.206(7)
94.910(7)
1689.7(16)
2
11.0292(6)
13.0562(7)
13.6416(7)
84.9740(10)
66.6040(10)
88.5070(10)
1795.86(17)
2
8103.3(13)
8
1.554
1782.65(18)
2
1.472
Z
Dcalcd [g cm-3
]
1.494
1.566
radiation (λ, D [Å])
F(000)
Mo KR (0.71073)
776
Mo KR (0.71073)
3824
Mo KR (0.71073)
808
Mo KR (0.71073)
856
2θ range [deg]
3.02 to 56.00
0.950
2.38 to 41.68
0.836
4.26 to 56.18
0.795
3.14 to 56.68
0.734
abs coeff [mm-1
]
T [K]
no. of measd reflns
no. of indep reflns
100(2)
19 458
7347
100(2)
16 887
4239
100(2)
15 992
100(2)
23 757
8101
6983
refinement method
full-matrix least-squares on F2
GOF on F2
1.048
1.066
1.010
1.017
final R indices [I > 2σ(I)]
R1 ) 0.0425, wR2 ) 0.1015 R1 ) 0.0351, wR2 ) 0.0856 R1 ) 0.0245, wR2 ) 0.0559 R1 ) 0.0342, wR2 ) 0.0760
R indices (all data)
R1 ) 0.0570, wR2 ) 0.1096 R1 ) 0.0413, wR2 ) 0.0891 R1 ) 0.0281, wR2 ) 0.0583 R1 ) 0.0488, wR2 ) 0.0821
largest diff. peak and hole [e · Å-3
]
1.270 and -1.211
0.477 and -0.991
0.497 and -0.336
1.145 and -0.759
Confirmation of the Halide-Induced Ligand Rearrange-
ment (HILR) Reaction in Pd(II) Complexes. To confirm that
the formation of heteroligated complexes occurs spontaneously
in the presence of halide ions via a ligand rearrangement process,
ligands 7 and 8 (1 equiv each) were separately mixed with
[Pd(COD)Cl2] (0.5 equiv each) in CD2Cl2, and the formation
of complexes 109 and 119 was confirmed via 31P{1H} NMR
spectroscopy. These two solutions were mixed rapidly, and an
additional 31P{1H} NMR spectrum was acquired after 15 min,
which exhibited major resonances corresponding to heteroligated
structure 9a as well as minor resonances for 10 and 11. This
experiment illustrates that the HILR reaction occurs via a ligand
dissociation/reassociation process, which leads to a mixture that
consists predominantly of heteroligated species. In an additional
experiment, complexes 18 (1 equiv) and 19 (1 equiv) (Scheme
5) were mixed in CH2Cl2 in the absence of any halide ions,
and no reaction was observed after 18 days, according to
31P{1H} NMR spectroscopy. Compounds 18 and 19 also showed
no reactivity in CH3OH/CD3OD (10:1 v/v) after 2.5 h, whereas
the formation of heteroligated complex 9c was observed upon
addition of Me4NI (2 equiv) after 30 min, according to 31P{1H}
NMR spectroscopy and high-resolution ESI-MS. These experi-
ments show the crucial role of halide ions for the formation of
heteroligated species via ligand rearrangement processes.
cooperative interactions between different functionalities in
tweezer complexes that derive from this novel ligand pairing
and sorting process.1i
Experimental Section
General Methods/Instrument Details. All reactions were
carried out under an inert atmosphere of nitrogen using standard
Schlenk techniques or an inert atmosphere glovebox. CH2Cl2,
acetonitrile, and hexanes were dried and purified through activated
alumina columns as described by Grubbs et al. prior to use.12 All
solvents were degassed with nitrogen prior to use. Deuterated
solvents were purchased from Cambridge Isotope Laboratories and
used as received. All other chemicals were used as received from
Aldrich Chemical Co. or prepared according to literature procedures
(7,8 8,13 1314). 1H NMR spectra were recorded on a Varian Mercury
300 MHz FT-NMR spectrometer at 300 MHz and referenced to
residual proton resonances in deuterated solvents. 19F{1H} NMR
spectra were recorded on a Varian Mercury 300 MHz FT-NMR
spectrometer at 282.5 MHz and referenced relative to an external
CFCl3 (in CDCl3) standard. Solution 31P{1H} NMR spectra were
recorded on a Varian Mercury 300 MHz FT-NMR spectrometer at
121.5 MHz and referenced relative to an external 85% H3PO4
standard. The NMR probe temperature was calibrated using
methanol (-20 to 20 °C) before variable-temperature measure-
ments.15 Solid state 31P{1H} CPMAS (cross-polarization magic-
angle spinning) NMR spectra were recorded on a 400 MHz Varian
FT-NMR system with a wide bore magnet and a T3 MAS probe
(HPC mode) at 161.8 MHz, with 3.3 µs proton pulse width, a
contact time of 5 ms, a recycle delay of 30 s, and a spin rate of
10 000 s-1. Chemical shifts were referenced with respect to an
external 85% H3PO4 standard by referencing the resonance for
external solid NH4H2PO4 to 0.8 ppm. All chemical shifts are
reported in ppm. FT-IR spectra were recorded in solution using a
Thermo Nicolet Nexus 670 FT-IR spectrometer with a NaCl cell
Conclusions
Thermodynamically controlled pairing and sorting processes
that favor complementary combinations are well known in
biological or organic supramolecular assemblies (e.g., pairing
of nucleobases), but are still relatively rare in supramolecular
coordination chemistry. The results obtained thus far show that
the HILR reaction consistently results in the spontaneous
formation of heteroligated species with various d8 transition
metal ions [Rh(I),5,6 Pt(II),8 Pd(II)]. In the case of the Pd(II)
complexes, these ligand pairing and sorting processes are
reversible, as evidenced by the dynamic equilibrium established
with the homoligated complexes in solution at elevated tem-
peratures. One can control this process through the choice of
counterion and stabilize the heteroligated structures with non-
(12) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518–1520.
(13) Dubois, D. L.; Myers, W. H.; Meek, D. W. J. Chem. Soc., Dalton
Trans. 1975, 1011–1015.
(14) Singewald, E. T.; Shi, X.; Mirkin, C. A.; Schofer, S. J.; Stern, C. L.
Organometallics 1996, 15, 3062–3069.
-
or weakly coordinating counterions such as BF4 . This “toolbox”
(15) Raiford, D. S.; Fisk, C. L.; Becker, E. D. Anal. Chem. 1979, 51,
2050–2051.
of reactions will be useful in studying and regulating the

Heteroligated Pd(II) Complexes with Hemilabile Ligands
Organometallics, Vol. 28, No. 4, 2009 1073
(cell length ) 0.1 mm). Electrospray ionization (ESI) mass spectra
were recorded on a Micromass Quatro II triple quadrupole mass
spectrometer or an Agilent LC/MS MSD1100 mass spectrometer.
MALDI-TOF mass spectra were recorded on an Applied Biosys-
tems Voyager-DE STR at the Mass Spectrometry Laboratory of
the University of Illinois, Urbana-Champaign, IL. High-resolution
elecrospray ionization mass spectra (ESI-HRMS) were recorded
on an Agilent 6210 TOF LC/MS spectrometer. Elemental analyses
were performed by Quantitative Technologies, Whitehouse, NJ, or
the Microanalytical Laboratory of the University of Illinois,
Urbana-Champaign, IL.
through Celite. Recrystallization from CH2Cl2/hexanes (slow dif-
fusion) resulted in 12 · 1/2CH2Cl2 as a pale yellow powder (216.7
mg, 77%). 1H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.80-7.77 (m,
2H, arom.), 7.58-7.44 (m, 23H, arom.), 3.4-2.9 (m, 8H, CH2),
2.57 (s, 3H, CH3). 31P{1H} NMR (121.5 MHz, CD2Cl2, 22 °C): δ
62.4 (s). MS (ESI, CH2Cl2): m/z 775.3 [M - BF4]+, 344.2 [M -
2 BF4]2+. Anal. Calcd for C35H36B2F8P2PdS2 · 1/2CH2Cl2: C, 47.10;
H, 4.12. Found: C, 47.42; H, 3.93. A residual amount of CH2Cl2
was observed via 1H NMR spectroscopy in CDCl3 upon drying in
Vacuo. Crystals of 12 · CH2Cl2 suitable for single-crystal X-ray
diffraction were obtained by slow diffusion of hexanes into a
solution of 12 in CH2Cl2 (colorless blades). Addition of acetonitrile
(5 µL, 0.1 mmol, 20 equiv) to 12 (5.0 mg, 0.0058 mmol, 1 equiv)
in CD2Cl2 (0.75 mL) at 24 °C resulted in no opening of complex
12 after 2 h, according to 31P{1H} NMR spectroscopy.
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2SPh)ClPd]Cl, 9a. A
solution of [Pd(COD)Cl2] (44.3 mg, 0.155 mmol, 1 equiv) in
CH2Cl2 (4 mL) was added dropwise to a stirring solution of
Ph2PCH2CH2SPh (8) (50.0 mg, 0.155 mmol, 1 equiv) in CH2Cl2
(2 mL) at 24 °C. The solution was yellow. After 5 min, a solution
of Ph2PCH2CH2SMe (7) (40.4 mg, 0.155 mmol, 1 equiv) in CH2Cl2
(2 mL) was added dropwise, and the yellow reaction mixture was
stirred for 1 h. Recrystallization from CH2Cl2/hexanes resulted in
9a as a colorless solid (92.0 mg, 78%). CPMAS 31P{1H} NMR
(161.8 MHz, 22 °C): δ 65.7 (s), 29.5 (s). Anal. Calcd for
C35H36Cl2P2PdS2: C, 55.31; H, 4.77. Found: C, 55.43; H, 4.73.
Crystals of 9a suitable for single-crystal X-ray diffraction were
obtained by slow diffusion of hexanes into the reaction mixture
(colorless plates). The following characterization data are for a
mixture of 9a, 10, and 11 in solution, which forms upon dissolution
of 9a in CD2Cl2, as described in the prior sections, Scheme 3 and
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2OPh)ClPd]Cl, 14a.
A solution of [Pd(COD)Cl2] (65.8 mg, 0.230 mmol, 1 equiv) in
CH2Cl2 (4 mL) was added dropwise to a stirring solution of
Ph2PCH2CH2SMe (7) (60.0 mg, 0.231 mmol, 1 equiv) in CH2Cl2
(2 mL) at 24 °C. The solution was yellow. After 5 min, a solution
of Ph2PCH2CH2OPh (13) (70.6 mg, 0.230 mmol, 1 equiv) in CH2Cl2
(2 mL) was added dropwise, and the orange reaction mixture was
stirred for 1 h. Recrystallization from CH2Cl2/hexanes resulted in
14a as a slightly yellow powder (137.4 mg, 80%). CPMAS 31P{1H}
NMR (161.8 MHz, 22 °C): δ 63.9 (s), 33.4 (s). Anal. Calcd for
C35H36Cl2OP2PdS: C, 56.50; H, 4.88. Found: C, 56.46; H, 4.63.
The following characterization data are for a mixture of 14a, 10,
and 15 in solution, which forms upon dissolution of 14a in CD2Cl2,
as described in the previous sections and Scheme 4. 1H NMR (300
MHz, CD2Cl2, 22 °C): δ 7.91-7.89 (m, arom.), 7.72-7.41 (m,
arom.), 7.11-7.06 (m, arom.), 6.92-6.87 (m, arom.), 4.42-4.32
(m, aliph.), 3.83 (br s, aliph.), 3.46 (br s, aliph.), 3.29 (br s, aliph.),
3.29-3.10 (m, aliph.), 2.98-2.8 (m, aliph.). 31P{1H} NMR (121.5
MHz, CD2Cl2, 20 °C): δ 61.2 (s, 14a), 44.8 (s, 10), 22.3 (s, 14a),
12.9 (s, 15); 0 °C: δ 61.9 (d, 2JP-P ) 2 Hz, 14a), 46.4 (s, 10), 26.1
1
Figure 1. H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.52-7.05 (m,
arom.), 3.66 (br s, aliph.), 3.32 (br s, aliph.), 3.09 (br s, aliph.),
2.90 (br s, aliph.), 2.78-2.42 (m, aliph.). 31P{1H} NMR (121.5
MHz, CD2Cl2, 20 °C): δ 61.0 (s, 9a), 44.9 (s, 10), 21.1 (s, 9a),
2
16.1 (s, 11); 0 °C: δ 61.5 (s, 9a), 46.4 (s, 10), 21.0 (d, JP-P ) 3
2
Hz, 9a), 16.4 (s, 11); -20 °C: δ 62.0 (d, JP-P ) 3 Hz, 9a), 48.4
(s, 10), 20.8 (d,2JP-P ) 4 Hz, 9a). The temperature equilibration
period between insertion of the NMR tube and acquisition of
variable-temperature NMR spectra was approximately 5 min.
31P{1H} NMR spectroscopic resonances for 109 and 119 were
measured separately at the respective temperatures and are con-
sistent with the corresponding assignments within 0.1 ppm. MS
(ESI, CH2Cl2): m/z ) 723.5 [M - Cl]+.
2
(s, minor unidentified species), 22.8 (d, JP-P ) 2 Hz, 14a), 12.9
2
(s, 15); -20 °C: δ 62.4 (d, JP-P ) 2 Hz, 14a), 48.3 (s, 10), 26.4
2
(s, minor unidentified species), 23.2 (d, JP-P ) 2 Hz, 14a), 12.6
(s, 15). The temperature equilibration period between insertion of
the NMR tube and acquisition of variable-temperature NMR spectra
was approximately 5 min. 31P{1H} NMR spectroscopic resonances
for 109 and 15 were measured separately at the respective
temperatures and are consistent with the corresponding assignments
within 0.2 ppm. MS (ESI, CH2Cl2): m/z 707.2 [M - Cl]+.
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2SPh)ClPd]BF4, 9b.
A solution of Me4NCl (1.9 mg, 0.018 mmol, 1 equiv) in MeOH
(anhydrous, 1 mL) was added to a solution of compound 12 (15.0
mg, 0.0174 mmol, 1 equiv) in CH2Cl2 (1 mL), resulting in a yellow
solution. 31P{1H} NMR spectroscopy after 15 min showed pre-
dominantly complex 9b. The reaction mixture was concentrated in
Vacuo, dissolved in CH2Cl2 (2 mL), followed by the addition of
hexanes until the solution became turbid (ca. 1 mL). Filtration and
concentration in Vacuo resulted in 9b (11.7 mg, 83%) as a pale
yellow powder. 1H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.95-7.21
(m, 25H, arom.), 3.22-3.02 (m, 2H, CH2), 2.93 (d, J ) 4.5 Hz,
3H, CH3), 2.77-2.68 (m, 4H, CH2), 2.59-2.55 (m, 2H, CH2).
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2OPh)ClPd]BF4,
14b. A solution of Me4NCl (1.9 mg, 0.018 mmol, 1 equiv) in MeOH
(anhydrous, 1 mL) was added to a solution of compound 16 (15.0
mg, 0.0177 mmol, 1 equiv) in CH2Cl2 (1 mL), resulting in a yellow
solution. 31P{1H} NMR spectroscopy after 15 min indicated
completion of the reaction. The reaction mixture was concentrated
in Vacuo, dissolved in CH2Cl2 (2 mL), followed by filtration and
concentration in Vacuo, resulting in 14b (12.8 mg, 91%) as a light
red powder. 1H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.9-7.24 (m,
20H, arom.), 7.06-7.00 (m, 2H, arom.), 6.85-6.82 (m, 3H, arom.),
4.43-4.33 (m, 2H, OCH2), 3.13-3.05 (m, 4H, CH2), 2.91 (d, J )
4.5 Hz, 3H, CH3), 2.68-2.52 (m, 2H, CH2). 31P{1H} NMR (121.5
2
31P{1H} NMR (121.5 MHz, CD2Cl2, 22 °C): δ 62.6 (d, JP-P ) 7
2
Hz), 22.5 (d, JP-P ) 5 Hz). 19F{1H} NMR (282.5 MHz, CD2Cl2,
22 °C): δ -152.86 (s, 10BF4), -152.91 (s, 11BF4). MS (ESI,
MeOH): m/z 723.0 [M - BF4]+, 344.0 [M - BF4 - Cl]2+. Anal.
Calcd for C35H36ClP2PdS2BF4: C, 51.81; H, 4.47. Found: C, 52.08;
H, 4.49.
2
2
MHz, CD2Cl2, 22 °C): δ 63.7 (d, JP-P ) 6 Hz), 25.4 (d, JP-P
)
6 Hz). 19F{1H} NMR (282.5 MHz, CD2Cl2, 22 °C): δ -152.95 (s,
10BF4), -153.01 (s, 11BF4). HRMS (ESI, MeOH): m/z 707.0694
[M - BF4]+.
cis-[K2-(Ph2PCH2CH2SMe)-K2-(Ph2PCH2CH2SPh)Pd](BF4)2, 12.
A solution of [Pd(COD)Cl2] (88.5 mg, 0.310 mmol, 1 equiv) in
CH2Cl2 (4 mL) was added dropwise to a stirring solution of
Ph2PCH2CH2SPh (8) (100.0 mg, 0.310 mmol, 1 equiv) in CH2Cl2
(2 mL) at 24 °C. After 5 min, a solution of Ph2PCH2CH2SMe (7)
(80.7 mg, 0.310 mmol, 1 equiv) in CH2Cl2 (2 mL) was added
dropwise, and the reaction mixture was stirred for 1 h. After addition
of AgBF4 (120.7 mg, 0.620 mmol, 2 equiv), the reaction solution
turned cloudy yellow. After 1 h, the reaction solution was filtered
trans-[K1-(Ph2PCH2CH2OPh)2Cl2Pd], 15. [Pd(COD)Cl2] (25.0
mg, 0.0876 mmol, 1 equiv) in CH2Cl2 (3 mL) was added to a
solution of Ph2PCH2CH2OPh (13) (53.7 mg, 0.175 mmol, 2 equiv)
in CH2Cl2 (2 mL), resulting in a yellow solution. After 1 h, the
reaction solution was layered with hexanes (slow recrystallization),
1
resulting in yellow crystals of 15 (65.0 mg, 94%). H NMR (300
MHz, CD2Cl2, 22 °C): δ 7.77-7.71 (m, 8H, arom.), 7.50-7.39

1074 Organometallics, Vol. 28, No. 4, 2009
Ulmann et al.
(m, 12H, arom.), 7.23-7.18 (m, 4H, arom.), 6.98-6.88 (m, 2H,
arom.), 6.78-6.71 (m, 4H, arom.), 4.30-4.24 (m, 4H, OCH2),
3.02-2.96 (m, 4H, PCH2). 31P{1H} NMR (121.5 MHz, CD2Cl2,
20 °C): δ 25.7 (s, minor unidentified species), 13.0 (s, 15); 0 °C:
δ 26.0 (s, minor unidentified species), 12.8 (s, 15); -20 °C: δ 26.3
(s, minor unidentified species), 12.5 (s, 15). MS (ESI, CH2Cl2):
m/z 753.1 [M - Cl]+. Anal. Calcd for C40H38Cl2O2P2Pd: C, 60.81;
H, 4.85. Found: C, 60.60; H, 4.75. Crystals of 15 suitable for single-
crystal X-ray diffraction were obtained by slow diffusion of hexanes
into a solution of 15 in CH2Cl2 (yellow blocks).
was yellow. After 15 min, AgBF4 (18.1 mg, 0.0930 mmol, 2 equiv)
was added and the cloudy yellow reaction mixture was stirred for 1 h.
Precipitation with hexanes, filtration through Celite, followed by
extraction of the precipitate with CH2Cl2 (25 mL) and concentration
in Vacuo resulted in 19 · 3/4CH2Cl2 as a light yellow powder (42.8
1
mg, 93%). H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.75-7.05 (m,
30H, arom.), 3.28-3.26 (m, 4H, SCH2), 3.15-3.05 (m, 4H, PCH2).
31P{1H} NMR (121.5 MHz, CD2Cl2, 22 °C): δ 62.9 (s). MS (ESI,
MeOH):m/z375.0[M-2BF4]2+.Anal.CalcdforC40H38B2F8P2PdS2 · 3/
4CH2Cl2: C, 49.51; H, 4.03. Found: C, 49.64; H, 3.73. A residual
amount of CH2Cl2 was observed via 1H NMR spectroscopy in CDCl3
upon drying in Vacuo. 31P{1H} NMR data are consistent with the
perchlorate derivative of 19 reported in ref 9.
Control Experiments for HILR Reaction. Formation of
Heteroligated Complex 9a from Homoligated Complexes 10
and 11. Complex 10 was formed by the addition of a solution of
[Pd(COD)Cl2] (4.5 mg, 0.016 mmol, 0.5 equiv) in CD2Cl2 (0.75
mL) to 7 (8.1 mg, 0.031 mmol, 1 equiv). Complex 11 was formed
by the addition of a solution of [Pd(COD)Cl2] (4.5 mg, 0.016 mmol,
0.5 equiv) in CD2Cl2 (0.75 mL) to 8 (10.0 mg, 0.031 mmol, 1
equiv). 31P{1H} NMR spectra for 10 and 11 were consistent with
ref 9 and assignments in Figure 1. These two solutions were mixed,
and a 31P{1H} NMR spectrum was acquired after 15 min, showing
a mixture of 9a (major component), 10, and 11.
cis-[K2-(Ph2PCH2CH2SMe)-K2-(Ph2PCH2CH2OPh)Pd](BF4)2,
16. A solution of [Pd(COD)Cl2] (82.2 mg, 0.288 mmol, 1 equiv)
in CH2Cl2 (4 mL) was added dropwise to a stirring solution of
Ph2PCH2CH2SMe (7) (75.0 mg, 0.288 mmol, 1 equiv) in CH2Cl2
(2 mL) at 24 °C. After 5 min, a solution of Ph2PCH2CH2OPh (13)
(88.2 mg, 0.288 mmol, 1 equiv) in CH2Cl2 (2 mL) was added
dropwise, and the orange reaction mixture was stirred for 1 h. After
addition of AgBF4 (112.1 mg, 0.576 mmol, 2 equiv), the reaction
solution turned cloudy yellow. After 1 h, the reaction solution was
filtered through Celite, followed by recrystallization from CH2Cl2/
hexanes (slow diffusion), resulting in 16 as a slightly orange powder
(209.3 mg, 86%). 1H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.67-7.49
(m, 24H, arom.), 7.14-7.09 (m, 1H, arom.), 4.42-4.15 (m, 2H,
OCH2), 3.55-3.05 (m, 4H, CH2), 2.95-2.4 (m, 2H, CH2), 2.14 (s,
3H, CH3). 31P{1H} NMR (121.5 MHz, CD2Cl2, 22 °C): δ 63.9 (s),
51.4 (s). MS (MALDI-TOF, DHB): m/z 670.8 [M - H - 2 BF4]+.
Anal. Calcd for C35H36B2F8OP2PdS: C, 49.65; H, 4.29. Found: C,
49.72; H, 4.20. Crystals of 16 suitable for single-crystal X-ray
diffraction were obtained by slow evaporation of hexanes into a
solution of 16 in 1,2-dichloroethane (colorless plates).
Formation of Heteroligated Complex 9c from Homoligated
Complexes 18 and 19. Complexes 18 (10.4 mg, 0.0130 mmol, 1
equiv) and 19 (12.0 mg, 0.0130 mmol, 1 equiv) were dissolved in
MeOH (anhydrous, 10 mL) and stirred, resulting in a yellow
solution. After 1 h, a solution of Me4NI (5.2 mg, 0.0259 mmol, 2
equiv) in CD3OD (1 mL) was added to the reaction solution,
resulting in the formation of an orange solution. 31P{1H} NMR
spectroscopy after 30 min indicated the formation of heteroligated
complex 9c. The solvent was removed in Vacuo, CH2Cl2 (2 mL)
was added to the residue, and the solution was filtered, followed
by removal of solvent in Vacuo, resulting in 9c (24.2 mg, 77%) as
an orange solid.
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2OPh)(acetonit-
rile)Pd](BF4)2, 17. Compound 16 (7.5 mg, 0.0089 mmol, 1 equiv)
was dissolved in CD2Cl2 (1 mL), followed by the addition of
acetonitrile (3 µL, 0.06 mmol, 6 equiv). 31P{1H} NMR spectroscopy
of the light yellow solution after 15 min showed quantitative
formation of 17. 1H NMR (300 MHz, CD2Cl2, 22 °C): δ 7.63-7.18
(m, 20H, arom.), 7.05-6.93 (m, 2H, arom.), 6.65-6.62 (m, 3H,
arom.), 4.14-4.08 (m, 2H, OCH2), 3.25-3.21 (m, 2H, CH2),
3.15-2.9 (m, 2H, CH2), 2.79 (d, J ) 4.8 Hz, 3H, CH3), 2.70-2.67
(m, 2H, CH2), 1.97 (s, ca. 20H, CH3CN). 31P{1H} NMR (121.5
cis-[K2-(Ph2PCH2CH2SMe)-K1-(Ph2PCH2CH2SPh)IPd]BF4,
1
9c. H NMR (300 MHz, CD3OD, 22 °C): δ 7.82-7.23 (m, 25H,
arom.), 3.3-3.05 (m, 2H, CH2), 3.0 (s, 3H, CH3), 2.95-2.6 (m,
6H, CH2). 31P{1H} NMR (121.5 MHz, CD3OD, 22 °C): δ 61.9 (s),
17.3 (s). 19F{1H} NMR (282.5 MHz, CD3OD, 22 °C): δ -154.32
(s, 10BF4), -154.37 (s, 11BF4). HRMS (ESI, MeOH): m/z 814.9812
[M - BF4]+.
2
2
MHz, CD2Cl2, 22 °C): δ 64.3 (d, JP-P ) 5 Hz), 22.5 (d, JP-P
)
5 Hz). MS (MALDI-TOF, DHB): m/z 670.8 [M - acetonitrile -
H - 2 BF4]+. FT-IR (CD2Cl2): νCN 2303 (metal bound acetonitrile),
2197 (free acetonitrile) cm-1. Addition of 1 equiv of acetonitrile
to 16 led to only a partial opening of the complex. The compound
was not isolated in the solid state due to loss of acetonitrile upon
solvent removal.
X-ray Crystallography. Crystallographic data are collected in
Table 1. Crystals were mounted on Cryoloops with Paratone oil.
Data were collected in a nitrogen gas stream at 100(2) K using phi
and omega scans. Crystal-to-detector distance was 60 mm. The data
were integrated using the Bruker SAINT software program and
scaled using the SADABS software program. All non-hydrogen
atoms were refined anisotropically by full-matrix least-squares
(SHELXL-97). All hydrogen atoms were placed using a riding
model. Their positions were constrained relative to their parent atom
using the appropriate HFIX command in SHELXL-97.
cis-[K2-(Ph2PCH2CH2SMe)2Pd](BF4)2, 18. A solution of [Pd-
(COD)Cl2] (54.8 mg, 0.192 mmol, 1 equiv) in CH2Cl2 (3 mL) was
added dropwise to a stirring solution of Ph2PCH2CH2SMe (7) (100.0
mg, 0.384 mmol, 2 equiv) in CH2Cl2 (2 mL) at 24 °C. The solution
was orange. After 15 min, AgBF4 (74.8 mg, 0.384 mmol, 2 equiv)
was added, and the cloudy light yellow reaction mixture was stirred
for 1 h. Precipitation with hexanes, filtration through Celite, followed
by extraction of the precipitate with CH2Cl2 (25 mL) and concentration
Acknowledgment. We acknowledge the NSF, ARO,
AFOSR, and DDRE for financial support of this research
and IMSERC (Northwestern U.) for analytical services.
C.A.M. is also grateful for an NIH Director’s Pioneer Award.
P.A.U. thanks Dr. Yuyang Wu and Mr. Abdelqader Sumrein
for help with analytical measurements.
1
in Vacuo resulted in 18 as a yellow powder (153.4 mg, 99.8%). H
NMR (300 MHz, CD2Cl2, 22 °C): δ 7.9-7.40 (m, 20H, arom.),
3.6-2.95 (m, 8H, CH2), 2.78 (d, J ) 3.9 Hz, 6H, CH3). 31P{1H} NMR
(121.5 MHz, CD2Cl2, 22 °C): δ 61.5 (s). MS (ESI, MeOH): m/z 313.0,
[M - 2 BF4]2+. Anal. Calcd for C30H34B2F8P2PdS2: C, 45.00; H, 4.28.
Found: C, 44.64; H, 4.15. 31P{1H} NMR data are consistent with the
perchlorate derivative of 18 reported in ref 9.
Supporting Information Available: Crystallographic data for
9a, 12 · CH2Cl2, 15, and 16 in cif format are available free of charge
via the Internet at http://pubs.acs.org.
cis-[K2-(Ph2PCH2CH2SPh)2Pd](BF4)2, 19. A solution of [Pd-
(COD)Cl2] (13.3 mg, 0.0466 mmol, 1 equiv) in CH2Cl2 (3 mL) was
added dropwise to a stirring solution of Ph2PCH2CH2SPh (8) (30.0
mg, 0.0931 mmol, 2 equiv) in CH2Cl2 (2 mL) at 24 °C. The solution
OM801060M