Multidonor ligands. 3. Cyclopalladation of py{SCH2C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp3)-H bond activation

Article abstract of DOI:10.1021/om981043f

[PdCl₂(NCPh)₂] reacts with R-carbonylmethylenethiopyridines [py{SCH₂C(O)R}-2] to give, depending on the substituent R and the reaction conditions, [Pd{py{SCHC(O)Ph}-2}(μ-Cl)₂Pd-{py{SCH₂C(O)Ph}-2}Cl] or the coordination complexes [Pd{py{SCH₂C(O)R}-2}₂Cl₂] (R = Ph, Me, OMe). The latter can be doubly deprotonated by a base (Na₂CO₃ or NaH) to give dicyclometalated complexes cis-[Pd{py{SCHC(O)R}-2}₂]. These transmetalate one ligand to [PdCl₂(NCPh)₂] to give [Pd{py{SCHC(O)R}-2}(μ-Cl)]₂, which in turn reacts with (Me₄N)Cl or with monodentate ligands L or with MeCN in the presence of AgClO₄ to give anionic Me₄N[Pd{py{SCHC(O)Ph}-2}Cl₂], neutral [Pd{py{SCHC(O)R}-2}Cl(L) [R = Ph, L = PPh₃, py{SCH₂C(O)Ph}-2, ^tBuNC, NH₂CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R = Me, L = PPh₃, py, tht], or cationic [Pd{py{SCHC(O)R}-2}(NCMe)₂]ClO₄ (R = Ph, Me, OMe) complexes, respectively. The latter react with PPh₃ or with bidentate ligands to give complexes [Pd{py{SCHC(O)Ph}-2}(NCMe)(PPh₃)]ClO₄ or [Pd{py{SCHC(O)Ph}-2}L₂]ClO₄ [L = PPh₃, L₂ = N,N,N′,N′-tetramethylethylenediamine (tmeda) or 2,2′-bipyridine (bipy)]. The crystal structures of[Pd{py{SCHC(O)R}-2}₂] and [Pd{py{SCHC(O)R}-2}Cl{py{SCH₂C(O)R}-2}] have been determined.

Full text of DOI:10.1021/om981043f

2750
Organometallics 1999, 18, 2750-2759
Articles
Mu ltid on or Liga n d s. 3.† Cyclop a lla d a tion of
p y{SCH2C(O)R}-2 (p y-2 ) 2-p yr id yl, R ) P h , Me, OMe)
th r ou gh a C(sp 3)-H Bon d Activa tion
J ose´ Vicente,*,‡ Mar´ıa-Teresa Chicote, Concepcio´n Rubio, and
M. Carmen Ram´ırez de Arellano§
Grupo de Quı´mica Organometa´lica,| Departamento de Quı´mica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Apartado 4021, Murcia, 30071 Spain
Peter G. J ones
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Received December 28, 1998
[PdCl2(NCPh)2] reacts with R-carbonylmethylenethiopyridines [py{SCH2C(O)R}-2] to give,
depending on the substituent R and the reaction conditions, [Pd{py{SCHC(O)Ph}-2}(µ-Cl)2Pd-
{py{SCH2C(O)Ph}-2}Cl] or the coordination complexes [Pd{py{SCH2C(O)R}-2}2Cl2] (R ) Ph,
Me, OMe). The latter can be doubly deprotonated by a base (Na2CO3 or NaH) to give
dicyclometalated complexes cis-[Pd{py{SCHC(O)R}-2}2]. These transmetalate one ligand to
[PdCl2(NCPh)2] to give [Pd{py{SCHC(O)R}-2}(µ-Cl)]2, which in turn reacts with (Me4N)Cl
or with monodentate ligands L or with MeCN in the presence of AgClO4 to give anionic
Me4N[Pd{py{SCHC(O)Ph}-2}Cl2], neutral [Pd{py{SCHC(O)R}-2}Cl(L)] [R ) Ph, L ) PPh3,
t
py{SCH2C(O)Ph}-2, BuNC, NH2CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R )
Me, L ) PPh3, py, tht], or cationic [Pd{py{SCHC(O)R}-2}(NCMe)2]ClO4 (R ) Ph, Me, OMe)
complexes, respectively. The latter react with PPh3 or with bidentate ligands to give
complexes [Pd{py{SCHC(O)Ph}-2}(NCMe)(PPh3)]ClO4 or [Pd{py{SCHC(O)Ph}-2}L2]ClO4 [L
) PPh3, L2 ) N,N,N′,N′-tetramethylethylenediamine (tmeda) or 2,2′-bipyridine (bipy)]. The
crystal structures of [Pd{py{SCHC(O)R}-2}2] and [Pd{py{SCHC(O)R}-2}Cl{py{SCH2C(O)R}-
2}] have been determined.
In tr od u ction
purposes15-21and for enantioselective catalysis.22 Many
palladacycles have found use in the preparation of
metallomesogens,23-32 and some show antitumor activ-
ity.33,34
Cyclopalladated complexes are becoming increasingly
important in organic synthesis.2-14 Chiral cyclopalla-
dated derivatives are being used for optical resolution
† For part 2 see ref 1.
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‡ E-mail: jvs@fcu.um.es.
§ Corresponding author regarding the X-ray diffraction study of
complex 3a . Present address: Departamento de Qu´ımica Orga´nica,
Facultad de Qu´ımica, Universidad de Valencia, 46100 Valencia, Spain.
E-mail: mcra@fcu.um.es.
| WWW: http://www.scc.um.es/gi/gqo/.
Corresponding author regarding the X-ray diffraction study of
complex 6. E-mail: jones@xray36.anchem.nat.tu-bs.de.
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10.1021/om981043f CCC: $18.00 © 1999 American Chemical Society
Publication on Web 06/29/1999

Multidonor Ligands. 3
Organometallics, Vol. 18, No. 15, 1999 2751
Cyclopalladation reactions involving a C(sp2)-H ac-
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ladated complexes with a chiral C(sp3) atom bonded to
Pd.
Ch a r t 1
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2752 Organometallics, Vol. 18, No. 15, 1999
Vicente et al.
(s, br, 2 H, CH2), 7.28-8.20 [m, 17 H, H5 (py)], 8.55 [d, 1 H,
Much more scarce are those cyclopalladation reactions
involving two C-H bond activations per palladium
atom. Two kinds of complexes have been isolated from
these cyclopalladation reactions: 1M2C1L and 1M2C2L
(see Chart 1). As far as we are aware, the double C-H
bond activation reactions leading to 1M2C1L complexes
are limited to palladation of a coordinated 2-pyridine-
substituted phosphonium salt49 and 2,6-pyridine-, 3,3′-
bipyridine-, and 2-pyrazine-substituted ligands,42,44,45
while those giving 1M2C2L complexes are known for
2-pyridine- and 2-pyrazine-substituted ligands.43-45 In
this paper we report new 1M2C2L complexes.
3
H6 (py), J HH ) 5.5 Hz]. 13C{1H} NMR (75 MHz, CDCl3): δ
40.42 (CH2), 54.57 (CH), 119.82, 120.67, 121.23, 126.78, 127.59,
128.16, 128.19, 128.69, 128.78, 128.85, 132.17, 133.95, 138.53,
139.40, 150.73 (ternary carbon nuclei); 135.12, 138.50 (Cipso),
174.67, 172.77 (CS), 193.58, 194.53 (CO).
Syn th eses of [P d {p y{SCH2C(O)R}-2}2Cl2] [R ) P h (2a ),
Me (2b), OMe (2c)]. To a solution of py{SCH2C(O)R}-2 (ca.
2.3 mmol) in acetone (20 mL) was slowly added solid [PdCl2-
(NCPh)2] (ca. 1 mmol). A yellow (2a ,b) or orange (1c) suspen-
sion immediately formed, which was stirred for 30 (2a ) or 80
(2b,c) min and filtered. The solid was washed successively with
acetone (10 mL) and diethyl ether (15 mL) to give yellow 2a -
c.
2a : Yield, 100%. Mp: 206 °C dec. Anal. Calcd for C26H22
-
Exp er im en ta l Section
Cl2N2O2S2Pd: C, 49.11; H, 3.49; N, 4.41; S,10.08. Found: C,
48.69; H, 3.53; N, 4.54; S, 9.94. IR (cm-1): ν(CdO), 1674;
ν(PdCl), 348.
The IR spectra, elemental analyses, conductance measure-
ments in acetone, and melting point determinations were
carried out as described earlier.80 The neutral complexes 3-10
are nonconducting in acetone. Unless otherwise stated the
reactions were carried out at room temperature without special
precautions against moisture, the 1H, 13C{1H}, and 31P{1H}
NMR spectra were recorded with a Varian Unity-300 spec-
trometer in CDCl3 solution, and chemical shifts are referred
to TMS [1H, 13C{1H}] or H3PO4 [31P{1H}]. 2-Mercaptopyridine
(HSpy) and chloroacetone were purchased from Fluka, 2-bro-
moacetophenone [BrCH2C(O)Ph] was from Aldrich, and meth-
ylchloroacetate was from Merck. The ligands py{SCH2C-
(O)R}-2 (R ) Ph, Me, OMe) were prepared as previously
described.1,53
2b: Yield, 95%. Mp: 168 °C. Anal. Calcd for C16H18
-
Cl2N2O2S2Pd: C, 37.55; H, 3.55; N, 5.47; S, 12.53. Found: C,
37.50; H, 3.61; N, 5.30; S, 12.46. IR (cm-1): ν(CdO), 1644;
ν(PdCl), 352.
2c: Yield, 95%. Mp: 226 °C dec. Anal. Calcd for C16H18
-
Cl2N2O4S2Pd: C, 35.34; H, 3.34; N, 5.15; S,11.77. Found: C,
35.65; H, 3.36; N, 4.97; S, 11.24. IR (cm-1): ν(CdO), 1746;
ν(PdCl), 350.
Syn th eses of [P d {p y{SCHC(O)R}-2}2] [R ) P h (3a ), Me
(3b), OMe (3c)]. To a suspension of 2 (a , 705 mg, 1.11 mmol;
b, 2.635 g, 5.15 mmol; c, 744 mg, 1.37 mmol) in acetone (2a ,b,
20 mL) or chloroform (2c, 20 mL) was added solid Na2CO3 (2a ,
282 mg, 2.66 mmol; 2b, 819 mg, 7.72 mmol) or NaH (2c, 66
mg, 2.74 mmol), and the resulting mixture was refluxed for 7,
5, or 1.5 h, respectively. In the cases of 3a and 3b the solvent
was removed under vacuum, the residue was extracted with
CH2Cl2 (3 × 5 mL), and the combined extracts were filtered
through Celite. In the case of 3c, the reaction mixture was
directly filtered through anhydrous MgSO4. The resulting
solution was concentrated (to ca. 2 mL), and diethyl ether
(3a ,b, 20 mL) or n-hexane (3c, 20 mL) was added to precipitate
yellow 3a ,b or orange 3c.
Syn th esis of [P d {p y{SCHC(O)P h }-2}(µ-Cl)2P d {p y-
{SCH2C(O)P h }-2}Cl] (1). A solution of py{SCH2C(O)Ph}-2
(700 mg, 3.05 mmol) in acetone (5 mL) was added dropwise to
a well-stirred solution of [PdCl2(NCPh)2] (1.17 g, 3.05 mmol)
in acetone (5 mL). A red suspension immediately formed,
which was stirred for 1 h and filtered. The solid was washed
with acetone (3 × 5 mL) to give 1 as a red solid, which was
dried in an oven at 80 °C overnight. Yield: 817 mg, 1.05 mmol,
69%. Mp: 193 °C. Anal. Calcd for C26H21Cl3N2O2S2Pd2: C,
40.21; H, 2.73; N, 3.61; S, 8.26. Found: C, 40.15; H, 2.74; N,
3.48; S, 8.21. IR (cm-1): ν(CdO), 1674, 1644; ν(PdCl), 356, 304,
3a : Yield, 580 mg, 1.03 mmol, 93%. Mp: 213 °C. Anal. Calcd
for C26H20N2O2S2Pd: C, 55.47; H, 3.58; N, 4.97; S, 11.39.
Found: C, 54.98; H, 3.58; N, 5.03; S, 11.20. IR (cm-1): ν(CdO),
1
272. H NMR (300 MHz, dmso-d6): δ 5.19 (s, 1 H, CH), 6.13
1
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1644, 1626. H NMR (300 MHz, CDCl3): δ 3.95 (s, 1 H, CH),
6.98 [m, 1 H, H5 (py)], 7.53 [m, 4 H, H3 (py) + H3 (Ph) + H4
(Ph)], 7.58 [m, 1 H, H4 (py)], 7.69 [m, 2 H, H2 (Ph)], 7.80 [d,
3
1 H, H6 (py), J HH ) 5.1 Hz]. 13C{1H} NMR (75 MHz, CDCl3):
δ 42.60 (s, CH), 119.96, 121.69, 127.17, 128.11, 131.02, 137.34,
148.72 (ternary carbon nuclei); 140.91 (Cipso), 170.85 (CS),
197.38 (CO).
Cr ysta l Str u ctu r e. A yellow prism of 3a of 0.44 × 0.22 ×
i
0.12 mm, obtained by liquid diffusion of Pr2O into a CHCl3
solution of 3a , was mounted in inert oil on a glass fiber and
transferred to the diffractometer (Siemens P4 with LT2 low-
temperature attachment). The crystal data are summarized
in Table 1. Unit cell parameters were determined from a least-
squares fit of 63 accurately centered reflections (9.98° < 2θ <
24.9°). An absorption correction based on ψ scans was em-
ployed with transmission factor 0.756-0.601. The structure
was solved by direct methods and refined anisotropically on
F2 (program SHELXL 93).81 Hydrogen atoms were included
using a riding model. The programs use the neutral atom
scattering factors from International Tables for Crystal-
lography.82 A system of 266 restraints (to local ring symmetry
and U components of neighboring light atoms) was employed.
Maximum ∆/σ ) 0.001. Figure 1 shows the thermal ellipsoid
plot of 3a ; Tables 1 and 2 give crystallographic data and
selected bond lengths and angles, respectively.
(80) Vicente, J .; Chicote, M. T.; Gonza´lez-Herrero, P.; J ones, P. G.
Inorg. Chem. 1997, 36, 5735.
(81) Sheldrick, G. M. SHELXL 93; University of Go¨ttingen: Go¨t-
tingen, Germany, 1993.
(82) International Tables for Crystallography; Kluwer Academic
Publishers: Dordrecht, The Netherlands, 1992; Vol. C, Tables 6.1.1.4
(pp 500-502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp 193-199).
3b: Yield, 1.956 g, 4.45 mmol, 87%. Mp: 228 °C. Anal. Calcd
for C16H16N2O2S2Pd: C, 43.78; H, 3.68; N, 6.38; S, 14.61

Multidonor Ligands. 3
Organometallics, Vol. 18, No. 15, 1999 2753
Ta ble 2. Selected Bon d Len gth s [Å] a n d An gles
[d eg] for Com p lexes 3a a n d 6‚CDCl3
3a
6‚CDCl3
Pd-N(1)
2.093(3)
2.112(3)
2.071(3)
2.056(4)
1.745(4)
1.745(4)
1.813(3)
1.803(4)
1.360(5)
1.345(4)
Pd-N(1)
Pd-N(2)
Pd-C(6)
Pd-Cl(1)
S(1)-C(11)
S(1)-C(5)
S(2)-C(21)
S(2)-C(6)
N(1)-C(11)
N(2)-C(21)
2.040(2)
2.045(2)
2.048(3)
2.3738(8)
1.753(3)
1.793(3)
1.729(3)
1.799(3)
1.344(4)
1.358(4)
Pd-N(2)
Pd-C(6)
Pd-C(26)
S(1)-C(1)
S(2)-C(21)
S(1)-C(6)
S(2)-C(26)
N(1)-C(1)
N(2)-C(21)
C(26)-Pd-C(6)
C(6)-Pd-N(1)
N(1)-Pd-N(2)
C(26)-Pd-N(2)
Pd-C(6)-S(1)
Pd-C(26)-S(2)
C(1)-S(1)-C(6)
97.08(14) N(1)-Pd-C(6)
82.25(13) N(2)-Pd-C(6)
96.74(11) N(2)-Pd-Cl(1)
84.08(13) N(1)-Pd-Cl(1)
90.76(11)
85.72(11)
93.80(7)
89.71(7)
109.5(2)
99.23(14)
F igu r e 1. Thermal ellipsoid plot of 3a (50% probability
levels) with the labeling scheme.
103.9(2)
109.2(2)
97.0(2)
Pd-C(6)-S(2)
C(21)-S(2)-C(6)
Ta ble 1. Cr ysta l Da ta for Com p lexes 3a a n d
S(2)-C(21)-N(2) 118.0(2)
6‚CDCl3
C(21)-S(2)-C(26) 100.2(2)
C(11)-S(1)-C(5)
103.8(2)
3a
6‚CDCl3
(Me), 51.70 (s, CH), 119.90, 121.87, 137.32, 148.92 (ternary
carbon nuclei), 171.75 (CS), 176.71 (CO).
formula
Mr
C26H20N2O2PdS2
562.96
C27H21Cl4DN2O2PdS2
719.80
space group
cell constants
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
P21/n
Pbca
Syn th eses of [P d {p y{SCHC(O)R}-2}(µ-Cl)]2 [R ) P h
(4a ), Me (4b), OMe (4c)]. To a suspension of 3 (a , 1162 mg,
2.06 mmol; b, 1 g, 2.28 mmol; c, 160 mg, 0.34 mmol) in acetone
(a , 15 mL; b, 40 mL; c, 25 mL) was added [PdCl2(NCPh)2] (a ,
792 mg, 2.06 mmol; b, 874 mg, 2.28 mmol; c, 130 mg, 0.34
mmol). A clear solution formed, from which an orange solid
precipitated within a few minutes. After 2 (4a ) or 1.5 (4b) or
24 (4c) h of stirring, the suspension was filtered (4a ,b) or
centrifuged (4c) and the orange solid washed with diethyl ether
(4a , 15 mL) or acetone (4b, 3 × 10 mL; 4c, 15 mL) and air-
dried. The solid was recrystallized from dichloromethane/
diethyl ether (4a ) or suspended in chloroform (15 mL), the
suspension refluxed for 15 h, the resulting solution concen-
trated (2 mL), and diethyl ether (15 mL) added to precipitate
4b,c.
13.114(2)
9.8241(12)
18.454(3)
90
107.975(10)
90
2261.5(5)
4
1.653
1.033
173(2)
50
0.71073
1136
3984
11.8989(12)
18.244(2)
26.688(2)
90
90
90
5793.5(10)
8
1.650
1.183
173(2)
50
0.71073
2880
5080
Z
Dx (Mg/m3)
µ (mm-1
T (K)
)
2θmax
λ (Å)
F(000)
no. of ind reflns
no. of params
no. of restraints
R1a
298
266
0.0331
0.0700
0.919
343
0
0.0327
0.0644
0.956
0.707
4a : Yield, 1.433 g, 1.90 mmol, 94%. Mp: 225 °C. Anal. Calcd
for C26H20Cl2N2O2S2Pd2: C, 42.18; H, 2.72; N, 3.78; S, 8.66.
Found: C, 41.85; H, 2.71; N, 3.82; S, 8.54. IR (cm-1): ν(CdO),
wR2b
1
1644; ν(PdCl), 328, 294, 258. H NMR (300 MHz, dmso-d6): δ
S(F2)
5.21 (s, 1 H, CH), 7.24-7.97 [complex multiplets, 8 H, py +
Ph], 8.59 [m, 1 H, H6 (py)]. 13C{1H} NMR (75 MHz, dmso-d6):
δ 54.62 (CH), 120.66, 121.22, 128.17, 128.74, 132.17, 139.37,
150.73 (ternary carbon nuclei), 138.48 (Cipso), 172.25 (CS),
194.65 (CO).
max. ∆F (e Å-3
)
0.601
a
b
R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σI. wR2 )
[∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2
+ bP, where P ) (2Fc + Fo2)/3 and a and b are constants set by
2
the program.
4b: Yield, 1347 mg, 2.19 mmol, 96%. Mp: 235 °C. Anal.
Calcd for C16H16Cl2N2O2S2Pd2: C, 31.19; H, 2.62; N, 4.55; S,
10.40. Found: C, 30.74; H, 2.71; N, 4.29; S, 9.61. IR (cm-1):
ν(CdO), 1660; ν(PdCl), 314, 278, 254. 1H NMR (200 MHz,
CDCl3): δ 2.32 (s, 3 H, Me), 4.74 [s, 1 H, CH), 7.00 [m 1 H, H4
(py)], 7.57 [m, 2 H, H 3 + H5 (py)], 8.11 [m, 1 H, H6 (py)].
4c: Yield, 178 mg, 0.27 mmol, 81%. Mp: 324 °C. Anal. Calcd
for C16H16Cl2N2O4S2Pd2: C, 29.65; H, 2.49; N, 4.32; S, 9.89.
Found: C, 29.28; H, 2.44; N, 4.14; S, 9.21. IR (cm-1): ν(CdO),
1697; ν(PdCl), 362, 334, 293, 265. 1H NMR (200 MHz, CDCl3):
δ 3.71 (s, 1 H, CH), 3.73 (s, 3 H, Me), 6,99 [m, 1 H, H4 (py)]
Found: C, 43.64; H, 3.60; N, 6.17; S, 14.35. IR (cm-1): ν(Cd
O), 1650. 1H NMR (200 MHz, CDCl3): δ 2.31 (s, 3 H, Me), 4.10
(s, 1 H, CH), 7.01 [m, 1 H, H4 (py)], 7.60 [m, 2 H, H3 + H5
3
(py)], 7.86 [d, 1 H, H6 (py), J HH ) 5.6 Hz]. 13C{1H} NMR (50
MHz, CDCl3): δ 28.26 (Me), 46.38 (CH), 119.96, 121.94, 137.47,
148.76 (ternary carbon nuclei), 171.09 (CS), 203.81 (CO).
3c (1:1 mixture of diastereoisomers RR + SS and RS): Yield,
471 mg, 1.00 mmol, 73%. Mp: 220 °C. Anal. Calcd for
C
16H16N2O4S2Pd: C, 40.82; H, 3.43; N, 5.95; S, 13.62. Found:
C, 40.72; H, 3.58; N, 5.62; S, 13.25. IR (cm-1): ν(CdO), 1682.
1H NMR (200 MHz, CDCl3): δ 3.65 (s, 3 H, Me), 3.69 (s, 3 H,
Me), 4.04 (s, 1 H, CH), 4.32 (s, 1 H, CH), 6.98-7.03 (m, 2 H,
py), 7.47-7.60 (m, 4 H, py), 7.90-7.95 (m, 2 H, py). When this
mixture of stereoisomers is refluxed in chloroform for 19 h, a
small amount of palladium is deposited. When the suspension
is filtered through Celite, the solution concentrated (2 mL),
and diethyl ether added, 3c precipitates as the pair of
enantiomers RR + SS or the RS isomer for which 1H NMR
(200 MHz, CDCl3): δ 3.65 (s, 3 H, Me), 4.04 (s, 1 H, CH), 6.98
[m, 1 H, H4 (py)], 7.45 [m, 2 H, H3 + H5 (py)], 7.94 [d, 1 H,
3
7.48 [d, 1 H, H3 (py), HHH ) 7.6 Hz], 7.60 [m, 1 H, H5 (py)],
8.24 [m, 1 H, H6 (py)].
Syn th eses of [P d {p y{SCHC(O)R}-2}Cl(L)] [R ) P h , L
) P P h 3 (5a ), p y{SCH2C(O)P h }-2 (6), tBu NC (7), S-NH2CH-
(Me)P h (8), p y (9a ), tetr a h yd r oth iop h en e (th t) (10a ); R
) Me, L ) P P h 3 (5b), p y (9b), th t (10b)]. To a suspension of
4a (or 4b) (ca. 0.5 mmol) in dichloromethane (20 mL) was
added 2 equiv (4 in the case of 7) of the corresponding ligand.
The resulting solution was stirred for 0.5 (5a , 6), 1.5 (5b, 9b),
3.5 (7), or 4.5 (8) h or overnight (9a , 10a ,b) and concentrated
(to ca. 1 mL), and diethyl ether (20 mL) or n-pentane (10b, 15
3
H6 (py, J HH ) 5.6 Hz). 13C{1H} (50 MHz, CDCl3): δ 32.90

2754 Organometallics, Vol. 18, No. 15, 1999
Vicente et al.
t
1H NMR (300 MHz, CDCl3): δ 1.24 (s, 9 H, Bu), 5.60 (s, 1 H,
CH), 7.08 [m, 1 H, H4 (py)], 7.51 [m, 6 H, H5 (py) + Ph], 7.97
[m, 1 H, H3 (py)], 8.98 (m, 1 H, H6 (py)]. 13C{1H} NMR (75
MHz, CDCl3): δ 29.60 (Me), 45.26 (CH), 119.84, 120.26, 128.09,
128.35, 132.13, 138.24, 151.08 (ternary carbon nuclei), 137.64
(Cipso), 172.54 (CS), 196.78 (CO).
8: Yield, 88%. Mp: 156 °C. Anal. Calcd for C21H21ClN2OPdS:
C, 51.34; H, 4.30; N, 5.70; S, 6.53. Found: C, 51.22; H, 4.40;
N, 5.75; S, 6.26. IR (cm-1): ν(NH), 3242, 3198; ν(CdO), 1630;
1
ν(PdCl), 340 or 296. H NMR (300 MHz, CDCl3): δ 1.62 (d, 3
3
3
H, Me, J HH, 4.4 Hz), 1.88 (d, 3 H, Me, J HH, 4.4 Hz), 2.7 (m, 2
H, NH2), 3.36 (m, 2 H, NH2), 4.38 (s, 1 H, CH), 4.99 (s, 1 H,
CH), 4.45 (m, 2 H, NCH), 7.10 (m, 2 H), 7.21-7.58 (m, 20 H),
7.87 (m, 4 H) 9.20 (m, 2 H).
9a : Yield, 89%. Mp: 178 °C. Anal. Calcd for C18H15ClN2-
OPdS: C, 48.12; H, 3.37; N, 6.23; S, 7.14. Found: C, 47.80; H,
3.40; N, 6.02; S, 6.96. IR (cm-1): ν(CdO), 1632; ν(PdCl), 316.
1H NMR (200 MHz, CDCl3): δ 5.23 (s, 1 H, CH), 6.98-7.60
(m, 11 H), 8.37 (m, 2 H), 9.00 (m, 1 H).
F igu r e 2. Thermal ellipsoid plot of 6‚CDCl3 (50% prob-
ability levels) with the labeling scheme.
9b: Yield, 68%. Mp: 296 °C. Anal. Calcd for C13H13ClN2-
OPdS: C, 40.33; H, 3.38; N, 7.24; S, 8.28. Found: C, 40.66; H,
3.35; N, 7.28; S, 8.34. IR (cm-1): ν(CdO), 1640; ν(PdCl), 348.
1H NMR (300 MHz, CDCl3): δ 2.19 (S, 3 H, Me), 4.16 (s, 1 H,
CH), 7.00 (m, 1 H) 7.33-7.38 (m, 2 H), 7.60 (m, 1 H), 7.80 (m,
1 H), 8.70 (m, 2 H), 8.84 (m, 1 H), 9.13 (m, 1 H).
mL) was added to precipitate a yellow solid, which was filtered
off and air-dried. In the case of 9b refluxing in chloroform (15
mL) for 4.5 h, concentration of the solution (1 mL), and
addition of diethyl ether (20 mL) were required to provide an
analytically pure sample. Complexes 6, 10a , and 10b were
recrystallized from dichloromethane/diethyl ether. Addition-
ally, complexes 6, 8, 9a , 10a , 9b, and 10b were dried in an
oven at 80 °C (9b, 60 °C) overnight.
10a : Yield, 80%. Mp: 163 °C. Anal. Calcd for C17H18
-
ClNOPdS2: C, 44.55; H, 3.96; N, 3.06; S, 13.99. Found: C,
44.65; H, 4.03; N, 3.79; S, 13.77. IR (cm-1): ν(CdO), 1630;
1
ν(PdCl), 304 or 262. H NMR (200 MHz, CDCl3): δ 1.97 (s, 4
5a : Yield, 93%. Mp: 243 °C. Anal. Calcd for C31H25
-
H, tht), 2.70 (s, 4 H, tht), 5.24 (s, 1 H, CH), 7.03 [m, 1 H], 7.44
(m, 5 H), 7.85 (m, 2 H), 8.90 (m, H6, 1 H).
ClNOPPdS: C, 58.87; H, 3.98; N, 2.21; S, 5.06. Found: C, 58.77;
H, 3.98; N, 2.24; S, 4.94. IR (cm-1): ν(CdO), 1642; ν(PdCl),
1
3
10b: Yield, 80%. Mp: 191 °C. Anal. Calcd for C12H16
-
304. H NMR (300 MHz, CDCl3): δ 4.41 (d, 1 H, CH, J PH
)
ClNOPdS2: C, 36.38; H, 4.07; N, 3.53; S, 16.18. Found: C,
2.7 Hz), 7.15 (m, 5 H, Ph) 7.45 [m, 18 H, PPh3 + H3 + H4 +
H5 (py)], 9.05 [m, 1 H, H6 (py)]. 13C{1H} NMR (75 MHz,
CDCl3): δ 49.92 (s, CH), 120.23, 127.45, 128.12, 128.23, 128.45,
130.63, 131.34, 134.47, 134.69, 137.84, 150.59, 150.62 (ternary
carbon nuclei), 129.84, 130.69, 130.89, 139.09 (quaternary
carbon nuclei), 197.03 (CO). 31P{1H} NMR (121 MHz, CDCl3):
δ 27.83 (s).
35.83; H, 3.85; N, 3.80; S, 14.56. IR (cm-1): ν(CdO), 1659;
1
ν(PdCl), 311. H NMR (200 MHz, CDCl3): δ 2.10 (s, 4 H, tht),
3.24 (s, 4 H, tht), 2.22 (s, 3 H, Me), 4.10 (s, 1 H, CH), 6.97 [m,
3
1 H, H4 (py)], 7.40 [d, 1 H, H3 (py), J HH ) 7.72 Hz], 7.53 [m,
3
1 H, H5 (py)], 9.00 [d, 1 H, H6 (py), J HH ) 5.62 Hz].
Syn th esis of Me4N[P d {p y{SCHC(O)P h }-2}Cl2] (11). To
a suspension of 4a (150 mg, 0.20 mmol) in acetone (30 mL)
was added (Me4N)Cl (43.28 mg, 0.40 mmol). The suspension
was stirred for 24 h and concentrated to dryness. The residue
was extracted with dichloromethane (3 × 5 mL), and the
combined extracts were filtered through Celite. The solution
was concentrated (to ca. 2 mL) and diethyl ether (20 mL) added
to give 11 as a yellow-orange solid, which was recrystallized
from dichloromethane and diethyl ether and dried in an oven
at 80 °C overnight. Yield: 157 mg, 0.33 mmol, 82%. Mp: 221
°C. Anal. Calcd for C17H22Cl2N2OPdS: C, 42.56; H, 4.62; N,
5.84; S, 6.68. Found: C, 42.74; H, 4.84; N, 5.93; S, 6.66. IR.
5b: Yield, 91%. Mp: 188 °C. Anal. Calcd for
C26H23-
ClNOPPdS: C, 54.75; H, 4.06; N, 2.46; S, 5.62. Found: C, 54.67;
H, 4.12; N, 2.32; S, 5.66. IR (cm-1): ν(CdO), 1660; ν(PdCl),
1
294. H NMR (300 MHz, CDCl3): δ 1.86 (S, 3 H, Me), 3.54 (d,
1 H, CH, 3J PH ) 3.3 Hz), 7.09 [m, 1 H, H4 (py)], 7.63 (m, 17 H,
H3 + H5 (py) + PPh3], 9.12 (m, 1 H, H6). 31P{1H} NMR (121
MHz, CDCl3): δ 29.82 (s).
6: Yield, 85%. Mp: 203 °C. Anal. Calcd for C26H21ClN2O2-
PdS2: C, 52.10; H, 3.53; N, 4.67; S, 10.70. Found: C, 52.06; H,
3.56; N, 4.71; S, 10.98. IR (cm-1): ν(CdO), 1690, 1630; ν(PdCl),
316. 1H NMR (200 MHz, CDCl3): δ 4.70 (AB system, 2 H, CH2,
2HHH ) 16 Hz), 5.28 (s, 1 H, CH), 6.47 (m, 1 H), 7.01(m, 4 H),
1
(cm-1): ν(CdO), 1630 ν(PdCl), 328, 296. H NMR (300 MHz,
3
7.49 (m, 10 H) 8.10 (m, 2 H), 8.94 (d, 1 H, J HH ) 5.9 Hz).
dmso-d6): δ 3.14 (s, 12 H, NMe4), 5.38 (s, 1 H, CH), 7.10 [t, 1
13C{1H} NMR (50 MHz, CDCl3): δ 39.73 (s, CH2), 45.21 (CH),
119.52, 120.30, 121.04, 122.77, 127.20, 128.24, 128.54, 128.83,
129.08, 131.51, 134.31, 137.22, 152.68, 153.00 (ternary carbon
nuclei), 99.19, 122.77, 132.06, 142.85, 143.13 (quaternary
carbon nuclei), 192.44 (CO).
3
H, H4 (py), J HH ) 6 Hz], 7.67 [m, 7 H, H3 + H5 (py) + Ph],
3
8.70 [d, 1 H, H6 (py), J HH ) 5.2 Hz].
Syn th eses of [P d {p y{SCHC(O)R}-2}(NCMe)2]ClO4 [R
) P h (12a ), Me (12b), OMe (12c)]. To a suspension of 4a -c
(ca. 0.15 mmol) in acetone (30 mL) was added 2 equiv of solid
AgClO4. Immediate precipitation of AgCl was observed. The
suspension was stirred for 3 (12a ) or 6 h (12b,c) and filtered.
The solution was concentrated (to ca. 1 mL) and diethyl ether
(20 mL) added to precipitate yellow (12a ,b) or orange (12c)
complexes. 12b,c were recrystallized from acetonitrile and
diethyl ether, and 12c was dried in an oven at 60 °C overnight.
Cr ysta l Da ta for 6‚CDCl3. A yellow parallelepiped of 6‚
CDCl3 of 0.70 × 0.60 × 0.35 mm was mounted and measured
as described for 3a . Unit cell parameters were determined from
a least-squares fit of 58 accurately centered reflections (9° <
2θ < 25°). An absorption correction based on ψ-scans was
employed, with transmisssion factors 0.725-0.812. The struc-
ture was solved and refined as described for 3a . Figure 1 shows
the thermal ellipsoid plot of 3a ; Tables 1 and 2 give crystal-
lographic data and selected bond lengths and angles, respec-
tively.
12a : Yield, 93%. Mp: 293 °C. Anal. Calcd for C17H16ClN3O5-
PdS: C, 39.55; H, 3.12; N, 8.14; S, 6.21. Found: C, 39.10; H,
3.21; N, 8.05; S, 6.65. IR (cm-1): ν(CdO), 1648; ν(ClO), 1110;
δ(OClO), 624. 1H NMR (300 MHz, CD3CN): δ 1.97 (s, 3 H,
free MeCN), 5.90 (s, 1 H, CH), 7.21 [m, 1 H, H4 (py)], 7.51-
7.57 (m, 2 H), 7.63 (m, 1 H), 7.73 (m, 1 H), 7.83 (m, 1 H), 7.92
7: Yield, 90%. Mp: 174 °C. Anal. Calcd for C18H19ClN2OPdS:
C, 47.70; H, 4.22; N, 6.18; S, 7.07. Found: C, 47.36; H, 4.26;
N, 6.15; S, 6.97. IR (cm-1): ν(CdO), 1652; ν(PdCl), 310 or 296.

Multidonor Ligands. 3
Organometallics, Vol. 18, No. 15, 1999 2755
(m, 2 H), 8.05 [m, 1 H, H6 (py)]. 13C{1H} (75 MHz, CD3CN):
δ 44.25 (CH), 121.98, 122.03, 128.77, 129.34, 133.73, 140.64,
152.36 (ternary carbon nuclei), 138.22, 173.88 (quaternary
carbon nuclei), 196.04 (CO).
Sch em e 1
12b: Yield, 84%. Mp: 279 °C dec. Anal. Calcd for C12H14
-
ClN3O5PdS: C, 31.74; H, 3.11; N, 9.25; S, 7.06. Found: C, 30.94;
H, 3.00; N, 8.62; S, 6.64. IR (cm-1): ν(CdO), 1666; ν(ClO), 1085;
δ(OClO), 624. 1H NMR (300 MHz, CD3CN): δ 1.98 (s, 3 H,
MeCN), 2.21 (s, 3 H, MeCN), 2.24 [s, 3 H, C(O)Me], 4.89 (s, 1
H, CH), 7.19 [m, 1 H, H4 (py)], 7.66 [m, 1 H, H3 (py)], 7.81
[m, 1 H, H5 (py)], 8.06 [m, 1 H, H6 (py)].
12c: Yield, 83%. Mp: 243 °C. Anal. Calcd for C12H14ClN3O6-
PdS: C, 30.65; H, 3.00; N, 8.94 S, 6.82. Found: C, 28.91; H,
2.81; N, 8.05; S, 6.36. IR (cm-1): ν(CdO), 1693; ν(ClO), 1089;
δ(OClO), 620. 1H NMR (300 MHz, CD3CN): δ 2.06 (s, 3 H,
MeCN), 2.31 (s, 3 H, MeCN), 3.77 (s, 3 H, OMe), 4.63 (s, 1 H,
CH), 7.31 [m, 1 H, H4 (py)], 7.74 [m, 1 H, H3 (py)], 7.92 [m, 1
H, H5 (py)], 8.25 [m, 1 H, H6 (py)].
Syn th esis of [P d {p y{SCHC(O)P h }-2}(NCMe)(P P h 3)]-
ClO4 (13). To a suspension of 12a (90 mg, 0.17 mmol) in MeCN
(20 mL) was added solid PPh3 (46 mg, 0.17 mmol). The color
changed immediately from yellow to orange. The suspension
was stirred for 1 h and concentrated (to ca. 2 mL), and diethyl
ether (20 mL) was added to precipitate 13 as an orange solid,
which was recrystallized from dichloromethane/diethyl ether
and dried in an oven at 80 °C overnight. Yield: 112 mg, 0.15
mmol, 88%. Mp: 159 °C. Anal. Calcd for C33H28ClN2O5PPdS:
C, 53.74; H, 3.83; N, 3.80; S, 4.35. Found: C, 53.66; H, 3.92;
N, 3.89; S, 4.17. IR (cm-1): ν(CdO), 1650; ν(ClO), 1093;
δ(OClO), 624. ΛM, 142 Ω-1 cm2 mol-1
CDCl3): δ 1.80 (s, 3 H, MeCN), 4.32 (d, 1 H, CH, J HP ) 5.7
Hz), 7.41 (m, 23 H, py + Ph + PPh3), 8.63 [m, 1 H, H6 (py)].
13C{1H} (75 MHz, CDCl3): δ 2.66 (Me), 45.22 (CH), 120.87,
.
1H NMR (300 MHz,
3
2.77 (m, 4 H, CH2), 2.90 (s, 3 H, Me), 4.47 (s, 1 H, CH), 7.00
[m, 1 H, H4 (py)], 7.58 [m, 7 H, H3 + H5 (py) +Ph], 7.95 [m,
1 H, H6 (py)]. 13C{1H} NMR: δ 45.73 (Me), 49.10 (Me), 50.98
(Me), 52.07 (Me), 60.91 (CH2), 64.03 (CH2), 52.60 (CH), 122.90,
123.09, 128.17, 129.55, 132.776, 139.86, 150.17 (ternary carbon
nuclei), 140.74 (Cipso), 172.75 (CS), 199.53 (CO).
2
127.94, 128.18, 129.13, 129.35, 131.93 (d, J PC ) 2.6 Hz),
132.46, 133.85, 134.08, 139.11 (ternary carbon nuclei), 122.50,
127.40, 136.24, 151.43 (quaternary carbon nuclei), 198.93 (CO).
31P{1H} NMR (121 MHz, CDCl3): 26.77 (s, PPh3).
16: Yield, 82%. Mp: 145 °C. Anal. Calcd for 16‚0.5CH2Cl2
C23.5H19Cl2N3O5PdS: C, 44.60; H, 3.03; N, 6.64; S, 5.07.
Found: C, 44.93; H, 2.99; N, 6.93; S, 5.33. IR (cm-1): ν(CdO),
Syn th eses of [P d {p y{SCHC(O)P h }-2}L2]ClO4 [L ) P P h 3
(14), L2
)
N,N,N′,N′-Tet r a m et h ylet h ylen ed ia m in e
1
1650; ν(ClO), 1084; δ(OClO), 624. H NMR (200 MHz, dmso-
(tm ed a ) (15), 2,2′-Bip yr id in e (bip y) (16)]. To a solution of
the appropriate ligand (PPh3, ca. 1 mmol; tmeda, bipy, ca. 0.5
mmol) in dichloromethane (20 mL) was added solid 12a (ca.
0.5 mmol). The resulting orange solution (14, 15) or the orange
suspension (16) was stirred for 2 or 24 h, respectively. The
solution was filtered through anhydrous MgSO4 and concen-
trated to ca. 1 mL, and diethyl ether (20 mL) was added to
precipitate pale orange 14 or yellow 15, which were recrystal-
lized from dichloromethane and diethyl ether and dried in an
oven at 80 °C overnight. The suspension obtained in the
reaction with bipy was filtered off, and the solid was washed
with dichloromethane (15 mL) and dried in an oven at 80 °C
overnight to give 16 as a yellow solid.
d6): δ 5.68 (s, 1 H, CH), 5.76 (s, 1 H, CH2Cl2), 7.32-7.50 (m,
5 H), 7.78 (m, 2 H), 7.85-8.00 (m, 3 H), 8.31 (m, 2 H), 8.50-
8.60 (m, 5 H).
Resu lts
Slow addition of an acetone solution of py{SCH2C-
(O)Ph}-2 into a well-stirred solution of [PdCl2(NCPh)2]
in the same solvent causes spontaneous evolution of HCl
and immediate precipitation of the dinuclear complex
[Pd{py{SCHC(O)Ph}-2}(µ-Cl)2Pd{py{SCH2C(O)Ph}-2}-
Cl] (1) in ca. 70% yield (see Scheme 1). The mother
14: Yield, 75%. Mp: 142 °C. Anal. Calcd for C49H40ClNO5P2-
PdS: C, 61.38; H, 4.20; N, 1.46 S, 3.34. Found: C, 61.36; H,
4.59; N, 1.56; S, 3.50. IR (cm-1): ν(CdO), 1625; ν(ClO), 1090;
1
liquor is shown to contain (by H NMR) a mixture of
complexes that we could not separate. When py{SCH2C-
(O)R}-2 (R ) Me, OMe) are used instead, the same
reaction workups also led to inseparable mixtures.
Coordination complexes [Pd{py{SCH2C(O)R}-2}2Cl2]
[R ) Ph (2a ), Me (2b), OMe (2c)] precipitate almost
quantitatively by slow addition of [PdCl2(NCPh)2] to an
acetone solution containing ca. 2.3 equiv of the ap-
propriate py{SCH2C(O)R}-2 ligand (see Scheme 1). The
order of addition of the reagents and their molar ratio
must be observed because otherwise mixtures are
obtained containing 2 and other insoluble species that
we could not separate.
δ(OClO), 624. ΛM, 149 Ω-1 cm2 mol-1 1H NMR (300 MHz,
.
CDCl3): δ 5.97 (d, 1 H, CH, 3J PH ) 10.2 Hz), 6.88-7.42 (m, 38
H, py + Ph + PPh3), 8.66 (m, 1 H, H6(py)]. 13C{1H} NMR: δ
65.72 (CH), 124.73, 125.17, 128.00, 128.29, 128.87, 129.09,
2
2
129.44, 131.41 (d, J CP ) 2.3 Hz), 131.62 (d, J CP ) 2.2 Hz),
132.99, 133.36 (d, 2J CP )2 Hz), 133.61(d, 2J CP ) 1.2 Hz), 135.70
(ternary carbon nuclei), 129.91, 130.27, 130.78, 138.93, 151.45
(quaternary carbon nuclei), 193.00 (CO). 31P{1H} NMR (121
2
MHz, CDCl3): δ 23.44 (d, PPh3, J PP ) 45.7 Hz), 28.51 (d,
PPh3).
15: Yield, 76%. Mp: 184 °C. Anal. Calcd for C19H26ClN3O5-
PdS: C, 41.46; H, 4.76; N, 7.63; S, 5.82. Found: C, 41.48; H,
4.77; N, 7.46; S, 5.86. IR (cm-1): ν(CdO), 1650; ν(ClO), 1090;
δ(OClO), 620. ΛM, 150 Ω-1 cm2 mol-1. 1H NMR (300 MHz, CD2-
Cl2): δ 2.09 (s, 3 H, Me), 2.56 (s, 3 H, Me), 2.76 (s, 3 H, Me),
Dicyclometalated complexes cis-[Pd{py{SCHC(O)R}-
2}2] [R ) Ph (3a ), Me (3b), OMe (3c)] were obtained in

2756 Organometallics, Vol. 18, No. 15, 1999
Vicente et al.
Sch em e 2
Ch a r t 2
Similarly, the reaction of 4a with Me4NCl gives the
anionic complex Me4N[Pd{py{SCHC(O)Ph}-2}Cl2] (11),
whereas cationic complexes [Pd{py{SCHC(O)R}-2}-
(NCMe)2]ClO4 [R ) Ph (12a ), Me (12b), OMe (12c)] can
be obtained by reacting the corresponding complex 4
with 2 equiv of AgClO4 in acetonitrile. After removing
AgCl by filtration, the complexes precipitate upon
addition of diethyl ether to the concentrated solution.
Complex 12a decomposes in dichloromethane or acetone
to give a brick red insoluble product. In the case of
dichloromethane, this product analyzes as “Pd{py-
{SCHC(O)Ph}}(ClO4)‚0.5Cl2CH2” (29% yield), and from
the mother liquor complexes containing H2O (by IR)
could be isolated. Complexes 12b and 12c are rather
more unstable, requiring recrystallization from aceto-
nitrile. Despite this, they always give elemental analy-
ses with low C, H, N, and S values that we attribute to
contamination with palladium or palladium-rich de-
composition products. This is why we decided to explore
only the reactivity of the stable complex 12a .
good yields by deprotonation of both methylene groups
present in complexes 2 (see Scheme 1). Thus, refluxing
2a or 2b with an excess of Na2CO3 allowed the synthesis
of complex 3a or 3b, which were separated from the
unreacted Na2CO3 and the byproduct NaCl by extrac-
tion with dichloromethane. Complex 2c does not react
with Na2CO3, but it does do so with NaH to give 3c.
The spirocomplexes 3a -c are efficient transmetalat-
ing agents toward [PdCl2(NCPh)2], and the room-tem-
perature reaction of equimolar amounts of both reagents
in acetone gives high yields of the insoluble dinuclear
Complex 12a reacts with neutral monodentate or
chelating ligands to give various cationic derivatives (see
Scheme 2) depending on the molar ratio of the reagents.
Thus, complex [Pd{py{SCHC(O)Ph}-2}(NCMe)(PPh3)]-
ClO4 (13) was obtained by addition of 1 equiv of PPh3
to a suspension of 12a in acetonitrile, whereas com-
complexes [Pd{py{SCHC(O)R}-2}(µ-Cl)]2 [R ) Ph (4a ),
Me (4b), OMe (4c)]. Complexes 4a -c can also be
obtained in good yield by reacting [PdCl2(NCPh)2] with
the appropriate py{SCH2C(O)R}-2 (R ) Ph, Me, OMe)
ligand and Na2CO3 in 2:2:1 molar ratio.
Complexes 4a ,b have been used as starting materials
for the synthesis of various cyclometalated neutral,
anionic, and cationic species (see Scheme 2). Thus,
addition of neutral ligands to suspensions of 4a ,b gives
plexes [Pd{py{SCHC(O)Ph}-2}L2]ClO4 [L ) PPh3 (14),
L2 ) tmeda, (15), bpy (16)] were prepared by adding
solid 12a to a dichloromethane solution containing 2
equiv of PPh3 or 1 equiv of tmeda or bpy, respectively.
If the order of addition of the reagents is reversed,
mixtures are obtained containing complexes 14-16 and
the above-mentioned products that result when 12a is
dissolved in dichloromethane.
So far, starting from some of the above complexes,
we have unsuccessfully attempted (i) to oxidize them
to sulfoxides or sulfones, (ii) to deprotonate the CH
group to give complexes a-c (Chart 2), (iii) to use them
as sulfur or sulfur and oxygen donor ligands to prepare
complexes of type d (See Chart 2), and (iv) to prepare
solutions from which neutral complexes [Pd{py{SCHC-
(O)R}-2}Cl(L)] [R ) Ph, L ) PPh3 (5a ), py{SCH2C(O)-
t
Ph}-2 (6), BuNC (7), S-NH2CH(Me)Ph (8), py (9a ),
tetrahydrothiophene (tht) (10a ); R ) Me, L ) PPh3 (5b),
py (9b), tht (10b)], which result from bridge cleavage
and coordination of the neutral ligand L, can be isolated.
We could not separate the 1:1 RS-8 + SS-8 mixture even
after recrystallizing it several times.

Multidonor Ligands. 3
Organometallics, Vol. 18, No. 15, 1999 2757
complexes resulting from insertion of alkynes, isocya-
nides, or carbon monoxide.
The crystal structure of 6‚CDCl3 shows the palladium
atom in a distorted square planar environment coordi-
nated to a chelating py{SCHC(O)Ph}-2 and a chloro
ligand and to the pyridinic nitrogen of a nonmetalated
py{SCH2C(O)Ph}-2 ligand. The palladium and the donor
atoms are in a plane (mean deviation of the five atoms
0.007 Å) with the two nitrogen atoms mutually trans.
The bond angles around the palladium atom are close
to the expected 90° with the exception of the N(2)-Pd-
C(6) angle [85.72(11)°] imposed by the chelating ligand.
The bond distances and angles in the Pd-C(6)-S(2)-
C(21)-N(2) heterocycle present in 6 are similar to their
analogues in complex 3a , except for the Pd-N bond
distances, which in 6 [Pd-N(1), 2.040(2) Å; Pd-N(2),
2.045(2) Å] are appreciably shorter than that in 3a
[2.112(3) Å], consistent with the smaller trans-influence
of nitrogen than carbon donor ligands. The bond dis-
tances in the nonmetalated ligand are similar to those
in the chelating one, but the angles are appreciably
different. In the absence of the restriction imposed by
chelation, the Pd-N(1)-C(11) [120.4(2)°] and C(5)-
S(1)-C(11) [103.8(2)°] are wider and closer to their ideal
values. The Pd-Cl bond distance [2.3738(8) Å] is shorter
than those found in some Pd(II) complexes with chloro
trans to a secondary alkyl ligand [2.413-2.47 Å].87-89
It is possible that the electron-withdrawing ability of
the benzoyl group could reinforce the p(π)Cl-d(π)Pd
bond component. Nonclassical hydrogen bonds C(12)-
H(12)‚‚‚O(2) [H‚‚‚O 2.35 Å, C-H‚‚‚O 156°] and C(99)-
H(99)‚‚‚Cl(1) [H‚‚‚Cl 2.70 Å, C-H‚‚‚Cl 149°] are ob-
served.
Discu ssion
Syn th eses of Com p lexes. It is reasonable to assume
that the slow addition of py{SCH2C(O)Ph}-2 to [PdCl2-
(NCPh)2] first gives a monoadduct (e.g., [Pd{py{SCH2C-
(O)R}-2}Cl(µ-Cl)]2). This compound must be the precur-
sor of 1 after a spontaneous cyclometalation (Scheme
1). The extreme insolubility of 1 prevents further
cyclometalation to give 4a . However, 4a is obtained by
reacting 1 with Na2CO3 (2:1) (Scheme 1). Equally
reasonable is the assumption that the diadducts 2a -c,
formed by slow addition of [PdCl2(NCPh)2] to a solution
of py{SCH2C(O)R}-2, do not cyclometalate spontane-
ously because of their insolubility. However, the forma-
tion of the dicyclometalated complexes 3a -c is possible
if a base is added. In the case of 3a (R ) Ph) and 3b (R
) Me) Na2CO3 can be used as the base, but 2c does not
react with Na2CO3, and the stronger base NaH had to
be used to achieve deprotonation. This difference may
be attributed to the strong +I effect of the methoxy
group, which decreases the acidity of the methylene
protons in complex 2c. Complexes 3a -c are examples
of the rare type of complexes obtained by cyclopallada-
tion reactions involving two C-H bond activations of
two ligands per palladium atom (1M2C2L in Chart 1).
The transmetalation of one alkyl group from 3a -c to
[PdCl2(NCPh)2] gives complexes 4a -c. We have used
the same method in the synthesis of mono-o-nitrophen-
ylpalladium complexes from bis-o-nitrophenylpalladi-
um.83
Neutral and anionic complexes have been prepared
by reacting 4a -c with neutral or anionic ligands that
cleave the chloro bridge (Scheme 2). The product of the
reaction between 4a -c and AgClO4 in acetonitrile
allows the preparation of the solvento complexes 12a -
c. Complex 12a is stable in acetonitrile, but its solution
in dichloromethane changes from yellow to orange and
slowly precipitates as a brick red insoluble product
analyzing as “Pd{py{SCHC(O)Ph}}(ClO4)‚0.5Cl2CH2”. It
is reasonable to asume that polymerization is achieved
by coordination of the sulfur and the oxygen atoms (see
Scheme 2). Complex 12a has been used to prepare other
cationic complexes 13-16.
1H and 13C NMR spectra of complex 1 could only be
measured in dmso-d6. As expected, they correspond to
an equimolecular mixture of the two complexes result-
ing from bridge cleavage by the solvent, as shown by
the singlet nature of the resonance due to the CH2
protons (5.97 ppm). Otherwise, this should appear as
an AB system as observed in complex 6 (4.70 ppm in
CDCl3). NMR spectra of complexes 2a -c could not be
1
measured because of their extreme insolubility. The H
NMR spectra of complexes 1 and 3-16 show the CH-
Pd resonance in the range 3.95-5.97 (R ) Ph), 3.54-
4.74 (R ) Me), or 3.71-4.63 ppm (R ) OMe). The
corresponding parent ligands show the CH2 resonance
at 4.71, 3.99, and 3.88 ppm, within the range of their
complexes. As expected, in the series of complexes with
R ) Ph, the value of δCH is high for the cationic complex
14 (δCH ) 5.97 ppm) and in the neutral complex 4a (δCH
) 5.21 ppm), where the electronegative Cl ligand is
trans to the CH group, while complex 3a shows the
lowest value (δCH ) 3.95 ppm). However, not all values
of δCH are as easy to interpret on electronic grounds.
Thus, that of the anionic complex 11 is 5.38 ppm,
downfield shifted with respect to that in the neutral
complex 5a despite both having a chloro ligand trans
to CH. Similarly, the CH proton is more deshielded in
3c (4.06 ppm) than in 4c (3.71 ppm), although both
Str u ctu r e of Com p lexes. The crystal structure of
3a shows a spiro complex in which the palladium atom
is coordinated to the nitrogen and methylene carbon
atoms of two mutually cis-anionic py{SCHC(O)Ph}-2
ligands in a distorted square planar environment. The
bite angles of the chelating ligands are narrower [82.25-
(13)° and 84.08(13)°] and, correspondingly, the other two
angles are wider than the ideal value of 90° [97.08(14)°,
97.74(11)°]. The bond distances and angles differ mar-
ginally from one metalacycle to the other. The Pd-N
[2.093(3) and 2.112(3) Å] and Pd-C [2.056(4) and 2.071-
(3) Å] bond distances are similar to those found for other
Pd(II) complexes with pyridine trans to a secondary
alkyl ligand.84-86
(86) Kemmit, R. D. W.; Proctor, C.; Russell, D. R. J . Chem. Soc.,
Dalton Trans. 1994, 3085.
(87) Ferguson, G.; McAlees, A. J .; McCrindle, R.; Ruhe, B. L. Acta
Crystallogr., B 1982, 38, 2253.
(88) Arnek, R.; Zetlerberg, K. Organometallics 1987, 6, 1230.
(89) Crocker, C.; Empsell, H. D. J . Chem. Soc., Dalton Trans. 1982,
1217.
(83) Vicente, J .; Chicote, M. T.; Martin, J .; Artigao, M.; Solans, X.;
Font-Altaba, M.; Aguilo´, M. J . Chem. Soc., Dalton Trans. 1988, 141.
(84) Newkome, G. R.; Gupta, V. K.; Taylor, H. C. R.; Fronczek, F.
R. Organometallics 1984, 2, 1247.
(85) Kemmit, R. D. W.; McKenna, P.; Russell, D. R.; Sherry, L. J .
S. J . Chem. Soc., Dalton Trans. 1985, 259.

2758 Organometallics, Vol. 18, No. 15, 1999
Vicente et al.
complexes are neutral and the latter has a more
electronegative chloro ligand trans to CH.
8.24; 12c, δH6 ) 8.25 ppm) or more (3c, δH6 ) 7.94 ppm)
shielded than the free ligand (at 8.25 ppm).
The 13C{1H} NMR spectra of some of the reported
complexes have also been measured and show the
expected resonances due to the methyl [28.26 (3b), 32.90
(3c), 29.60 (7), 2.66 (13), 45.73, 49.10, 50.98, 52.07 (15)
ppm], methylene [40.42 (1), 39.73 (6) 60.91, 64.03 (15)
ppm], methyne [54.57 (1), 42.60 (3a ), 46.38 (3b), 51.70
(3c), 54.62 (4a ), 49.92 (5a ), 45.21 (6), 45.26 (7), 44.25
(12a ), 45.22 (13) 65.72 (14), 52.60 (15) ppm], aryl,
pyridyl (range 119-175 ppm), and carbonyl [193.58,
194.53 (1), 197.38 (3a ), 203.81 (3b), 176.71 (3c), 194.65
(4a ), 197.03 (5a ), 192.44 (6), 196.78 (7), 196.04 (12a ),
198.93 (13), 193.00 (14), 199.53 (15) ppm] groups. The
spectrum of 6 shows only one CO resonance (at 192.44
ppm), although two different carbonyl groups are present
in the molecule. The spectrum of 7 does not show the
Complexes 1-10 and 13 could be of cis or trans
geometry, but, according to the NMR data obtained from
those complexes sufficiently soluble in noncoordinating
solvents (3-10 and 13), only one of the possible geo-
metric isomers is obtained in all reactions. We propose
a trans position of the pyridinic N atoms in complexes
2 and 9 because this is the geometry of complex 6.
Additionally, the IR spectrum of complex 9 suggests that
the chloro ligand is trans to the carbon atom (see below).
The NMR spectrum of complex 3c (obtained after 1.5 h
refluxing in chloroform of a mixture of 2c and HNa)
shows a double set of resonances, indicating a 1:1
mixture of the diastereoisomer RS and of the enanti-
omer pair RR + SS. However, the NMR spectrum of the
analogous 3a or 3b (obtained after refluxing in acetone
for 7 or 5 h a mixture Na2CO3 and 2a or 2b, respec-
tively) shows that only the RS or the pair of enantiomers
RR + SS is present in solution. We believe that in all
three cases a mixture of the three stereoisomers initially
forms and that on prolonged heating RS-3 f RR-3 +
SS-3, or the reverse reaction, occurs. In fact, after
refluxing 3c in chloroform for 19 h and filtering off a
small amount of precipitated palladium, the 1:1 mixture
of stereoisomers transforms into RS-3c or RR-3c + SS-
3c. According to the crystal structure of 3a (q.v.), which
shows it to be the RR isomer, this thermal reaction
transforms RS-3a into RR-3a + SS-3a . A series of NOE
experiments on complex 3a prove that both chelating
ligands also adopt a mutually cis disposition in solution.
In fact, irradiation of the methynic CH proton enhances
the resonance at 7.7 ppm, assigned to the ortho-proton
of the phenyl group, but does not modify the intensity
of the pyridinic H6 as would be expected for the trans
isomer. Similarly, irradiation of H6 enhances the H4
resonance but not the CH resonance. The cis geometry
of complexes 3 or the Cl trans to C disposition in
complexes 5 or 7 accords with the inherent instability
of Pd(II) complexes containing two carbon or one C and
one P donor ligands in mutually trans positions
(transphobia).90,91
t
quaternary BuNC carbon nuclei even if it is measured
overnight.
The 31P{1H} NMR spectra show singlet resonances
for complexes 5a (27.83 ppm), 5b (29.82 ppm), and 13
(26.77 ppm) and two doublets for complex 14 (23.44,
2
28.51 ppm; J PP 45.7 Hz)
All complexes show one or in some cases two (1, 3a ,
6) IR bands assignable to ν(CdO) mode in the ranges
1626-1690 (R ) Ph), 1640-1690 (R ) Me), and 1693-
1746 cm-1 (R ) OMe). The presence of two ν(CdO)
bands in complexes 1 and 6 must be attributed to the
presence of two different thiopyridine ligands, one N-
and the other C,N-coordinated. Although two ν(CdO)
bands should also be observed in the IR spectra of
complexes 3a -c and 4a -c, with C2v or lower symmetry,
these are only observed in the spectrum of 3a . Com-
plexes 2a , 6 (R ) Ph), and 2c (R ) OMe), containing
N-coordinated thiopyridine ligands, show the ν(CdO)
band (1674, 1690, and 1746 cm-1, respectively) close to
that in the free ligand [1678 (R ) Ph) and 1737 (R )
OMe) cm-1, respectively], while C,N-coordination causes
the energy of this band to decrease by between 26 (7)
and 55 (3c) cm-1. Surprisingly, when R ) Me (complexes
2b-10b and 12b), the ν(CdO) band (in the narrow
range of 1640-1660 cm-1) is of lower energy than that
in the free ligand, irrespective of the coordination mode
of the ligand or the charge of the complex.
The 1H NMR spectrum of complex 4a in dmso-d6
shows one resonance for each type of proton, whereas
in the case of complexes 4b and 4c, a double set of
signals is observed. If, as expected, mononuclear species
result from splitting of the chloro bridge and coordina-
tion of dmso, every set of resonances would correspond
The IR spectra of complexes 1 and 4a -c, containing
two bridging chloro ligands, show three or four medium
bands in the 400-200 cm-1 region that could tentatively
be assigned to ν(PdCl) modes [356, 304, 272 (1), 328,
294, 258 (4a ), 314, 278, 254 (4b), 362, 334, 293, 265 (4c)
cm-1] according to the low symmetry of these complexes.
In complexes 2, the presence of only one band assignable
to a ν(PdCl) mode is indicative of a trans geometry
because two bands are expected for the cis C2v isomers.
In the IR spectrum of complex 11 the bands at 328 and
296 cm-1 must be assigned to the ν(PdCl) trans to
nitrogen and carbon, respectively, according to the
higher trans influence of carbon- than nitrogen-donor
ligands. Most of the neutral complexes 5-10 show one
ν(PdCl) band around 300 cm-1, indicative of the chloro
ligand being trans to carbon. However, unequivocal
assingment of the ν(PdCl) bands in complexes 7 and 8
is not possible because they show two bands in the
region 340-262 cm-1, although according to NMR data
their solutions contain only one geometrical isomer (see
1
to one of the two possible geometrical isomers. The H
NMR spectrum of complex 8 shows duplicate reso-
nances, indicating the formation of the isomers RS and
SS in 1:1 molar ratio.
The resonance assignable to the H6 of the pyridine
in the py{SCHC(O)R}-2 ligands can be unambiguously
assigned in most complexes. In the R ) Ph series, most
complexes show this resonance downfield shifted [8.25-
9.20 ppm] with respect to that in the free ligand (8.06
ppm), while in the spectra of 3a , 12a , and 15 it appears
at 7.80, 8.05, and 7.95 ppm, respectively. All complexes
with R ) OMe show such resonance equally (3c, δH6
)
(90) Vicente, J .; Arcas, A.; Bautista, D.; J ones, P. G. Organometallics
1997, 16, 2127.
(91) Pearson, R. G. Inorg. Chem. 1973, 12, 712.

Multidonor Ligands. 3
Organometallics, Vol. 18, No. 15, 1999 2759
Experimental Section). In the case of 10b, the unique
band is observed in the middle of the range (311 cm-1).
Additionally, complex 7 shows a ν(CN) at 2232 cm-1, 8
shows two ν(NH) bands at 3242, 3198 cm-1, 11 shows
at 952 cm-1 a band due to the NMe4, and complexes
12-16 show two bands characteristic of the perchlorate
anion in the ranges 1100-1090 [ν(ClO)] and 624-620
cacio´n y Ciencia (Spain) for a grant and a contract,
respectively.
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and structure refinement details, atomic coordinates
and equivalent isotropic displacement parameters, bond dis-
tances and angles, anisotropic displacement parameters, and
hydrogen coordinates and isotropic displacement parameters
for 3c and 6‚CDCl3. This material is available free of charge
via the Internet at http://pubs.acs.org.
[δ(OClO)] cm-1
.
Ack n ow led gm en t . We thank DGES (PB97-1047)
and the Fonds der Chemischen Industrie for financial
support. C.R. and M.C.R.A. thank Ministerio de Edu-
OM981043F