Synthesis, spectral characterization, and X-ray crystal structure of Pd(II) complexes containing the orthometallated C,C-chelating ligand C 6H 4-PPh 2C(H)C(O)CH 2Cl

Article abstract of DOI:10.1080/00958972.2013.788694

The ylide-phosphonium salt [PPh₃CH₂C(O)CH ₂Cl]⁺Cl^- (1) reacted with Pd(OAc)₂ to give the chloro-bridged dinuclear complex [Pd{C(H)PPh₃C(O)CH ₂Cl}(μ-Cl)(OAc)]₂

Full text of DOI:10.1080/00958972.2013.788694

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Synthesis, spectral characterization,
and X-ray crystal structure of
Pd(II) complexes containing the
orthometallated C,C-chelating ligand
C6H4-PPh2C(H)C(O)CH2Cl
Kazem Karami a , Sara Amouzad a , Mahboubeh Hosseini-Kharat a
& Corrado Rizzoli b
a Department of Chemistry , Isfahan University of Technology ,
Isfahan , Iran
b Department of Chemistry , University of Parma , Parma , Italy
Accepted author version posted online: 25 Mar 2013.Published
online: 02 May 2013.
To cite this article: Kazem Karami , Sara Amouzad , Mahboubeh Hosseini-Kharat & Corrado
Rizzoli (2013) Synthesis, spectral characterization, and X-ray crystal structure of Pd(II) complexes
containing the orthometallated C,C-chelating ligand C6H4-PPh2C(H)C(O)CH2Cl, Journal of
Coordination Chemistry, 66:10, 1774-1783, DOI: 10.1080/00958972.2013.788694
To link to this article: http://dx.doi.org/10.1080/00958972.2013.788694
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Journal of Coordination Chemistry, 2013
Vol. 66, No. 10, 1774–1783, http://dx.doi.org/10.1080/00958972.2013.788694
Synthesis, spectral characterization, and X-ray crystal
structure of Pd(II) complexes containing the orthometallated
C,C-chelating ligand C6H4-PPh2C(H)C(O)CH2Cl
KAZEM KARAMI*y, SARA AMOUZADy, MAHBOUBEH HOSSEINI-KHARATy and
CORRADO RIZZOLIz
yDepartment of Chemistry, Isfahan University of Technology, Isfahan, Iran
zDepartment of Chemistry, University of Parma, Parma, Italy
(Received 9 December 2012; in final form 30 January 2013)
The ylide-phosphonium salt [PPh3CH2C(O)CH2Cl]+Clꢀ (1) reacted with Pd(OAc)2 to give the
chloro-bridged dinuclear complex [Pd{C(H)PPh3C(O)CH2Cl}(μ-Cl)(OAc)]2 (2), which underwent
bridge cleavage reactions with a neutral bidentate N-donor to afford the cationic orthometallated
complexes [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(NꢀN)]CF3SO3 [NꢀN=bipy (2,2’-bipyridine)
(3), phen (1,10-phenanthroline) (4), 4-Me-phen (4-methyl-1,10-phenanthroline) (5), and 5-NO2
phen (5-nitro-1,10-phenanthroline) (6)]. The complexes were identified and characterized by
spectroscopic studies (IR and NMR). X-ray single-crystal analysis of 4 and 5 revealed the presence
of an orthometallated C6H4-PPh2 unit and a C-linked ylide PdꢀC(H). Thermal behavior of 3–6 is
investigated by thermogravimetry.
Keywords: CH-bond activation; Cyclopalladated complex; Phosphorus ylide; Crystal structure
1. Introduction
The reactivity and coordination chemistry of phosphorous ylides R3P=C(R′)(R″) (R=alkyl,
aryl; R′ and R″=H, alkyl, aryl, acyl, etc.) toward transition metals are important in organo-
metallic chemistry [1–19]. They are versatile ligands due to their ambidentate character, in
addition to their applicability in organic synthesis [20–22]. Carbonyl-stabilized phosphorus
ylides are interesting ligands because they can behave as C or O donors owing to
delocalization of the ylidic electron pair [23–29]. Orthometallation of phosphorous ylides
[6–812, 1729–32] occurs in the vast majority of cases, regioselectively at Ph rings of the
phosphine. Some recent contributions have shown that it is possible to obtain orthopalla-
dated complexes derived from CH activation at Ph rings belonging to the R′ or R″
substituents of the ylidic carbon and, more precisely, belonging to benzamide moieties
[33].
To expand the scope of C,C-orthometallated complexes [29, 34–36], CꢀH bond
activation processes induced on 2 by addition of bidentate N-donors under mild conditions
*Corresponding author. Email: karami@cc.iut.ac.ir
Ó 2013 Taylor & Francis

Orthometallated Pd(II) complexes
1775
Scheme 1. (i) PPh3, dichloromethane, 60 °C; (ii) Pd(OAc)2, dichloromethane, room temperature, 24 h;
(iii) (Ag-CF3SO3), acetonitrile, bidentate ligand, room temperature.
have been investigated, resulting in synthesis of new mononuclear orthometallated 3–6
(scheme 1).
2. Experimental
2.1. General
Starting materials and solvents were purchased from Merck and used without purification.
Infrared spectra were recorded on a FT-IR JASCO 680 spectrophotometer from 4000–
400 cmꢀ1 using KBr pellets. NMR spectra were recorded in DMSO-d6 at room tempera-
ture on a Bruker spectrometer at 400.13 MHz (1H), 100.61 MHz (13C), and 161.97 MHz
(31P). Chemical shifts (ppm) are reported according to internal TMS (1H, 13C) and external
85% phosphoric acid (31P). Thermal analysis curves (TG) were obtained from a Labsys
TG-DSC 1600 thermal analyzer in flowing air with a heating rate of 10 °C min–1.
Elemental analysis was performed on a Leco, CHNS-932 apparatus.
2.2. Synthesis of mono-phosphonium salt [PPh3CH2C(O)CH2Cl]+Clꢀ (1)
To a solution of 1,3-dichloro-2-propanone (0.504 g, 4 mM) in dichloromethane (15 mL)
was added PPh3 (1.048 g, 4 mM). The resulting solution was heated under reflux for 24 h
and then filtered through a plug of MgSO4. The filtrate was concentrated to ca. 2 mL, and
n-hexane (15 mL) was added to precipitate 1 as a white solid, which was collected and
1
air-dried. Yield 72%; IR (KBr, cmꢀ1): ν(CO) = 1734. H NMR (DMSO-d6, ppm): δ = 4.93
2
(s, 2H, CH2Cl), 5.9 (d, 2H, CH2P JPH = 12 Hz), 7.53ꢀ7.90 (m, 15H, PPh3). 31P {1H}
NMR (DMSO-d6, ppm): δ = 19.84 (s, 1P, CH2P).

1776
K. Karami et al.
2.3. Synthesis of [Pd{C(H)PPh3C(O)CH2Cl}(μ-Cl)(OAc)]2 (2)
Phosphonium salt (1) (0.116 g, 0.3 mM) was added to a dichloromethane (15 mL) solution
of palladium(II) acetate (0.067 g, 0.3 mM) and the mixture was stirred for 24 h at room
temperature. The resulting solution was concentrated to ca. 2 mL, and n-hexane (15 mL)
was added to precipitate 2 as an orange solid, which was collected and air-dried. Yield:
76%. IR (KBr, cmꢀ1): ν(CO) = 1671; νas(COO) = 1584; νs(COO) = 1334; ν(Pd-OAc) = 471.
Anal. calcd for C46H42O6P2Cl4Pd2: C, 49.89; H, 3.82. Found: C, 49.22; H, 3.67%.
2.4. Synthesis of [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(bipy)]CF3SO3 (3)
Silver triflate (Ag-CF3SO3) (0.03 g, 0.12 mM) was added to a solution of 2 (0.063 g,
0.06 mM) in acetonitrile (15 mL). The resulting mixture was stirred for 30 min in the
absence of light and then filtered through a plug of MgSO4 to remove AgCl. Bipyridine
(0.018 g, 0.12 mM) was added to the filtrate, and the mixture was stirred for 2 h and then
filtered again through MgSO4. The solvent was removed to ca. 2 mL, and n-hexane
(15 mL) was added to precipitate 3 as a light green solid, which was collected and
1
air-dried. Yield: 84%. IR (KBr, cmꢀ1): ν(CO) = 1677. H NMR (DMSO-d6, ppm): δ = 4.58
(s, 2H, CH2Cl), 5.04 (s, 1H, CHP) 7.49ꢀ7.84 (m, 14H, (C6H4)PPh2), 7.95ꢀ8.74 (m, 8H,
bipy). 31P {1H} NMR (DMSO-d6, ppm): δ = 19.65 (s, 1P, CHP).
2.5. Synthesis of [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(phen)]CF3SO3 (4)
Silver triflate (Ag-CF3SO3) (0.025 g, 0.1 mM) was added to a solution of 2 (0.05 g,
0.005 mM) in acetonitrile (15 mL). The resulting mixture was stirred for 30 min in the
absence of light and then filtered through a plug of MgSO4 to remove AgCl. 1,10-phenan-
throline (0.018 g, 0.1 mM) was added to the filtrate, and the mixture was stirred for 2 h
and then filtered again through MgSO4. The solvent was removed to ca. 2 mL, and
n-hexane (15 mL) was added to precipitate 4 as a cream solid, which was collected and
1
air-dried. Yield: 64%. IR (KBr, cmꢀ1): ν(CO) = 1678. H NMR (DMSO-d6, ppm): δ = 4.73
(s, 2H, CH2Cl), 5.24 (s, 1H, CHP) 7.45ꢀ7.96 (m, 14H, (C6H4)PPh2), 8.32ꢀ9.73 (m, 7H,
1
phen), 9.74 (br s, Ha, phen). 13C{1H} NMR (DMSO-d6, ppm): δ = 37.1 (d, Jpc = 56 Hz),
49.34 (Caliphatic), 119.05, 122.26, 123.44, 124.42, 125.07, 125.54, 126.05, 126.64, 127.32,
128.43, 129.34, 129.56, 129.71, 129.83, 131.37, 131.50, 132.07, 132.12, 133.29, 133.35,
135.44, 135.68, 135.82, 137.10, 138.38, 138.90, 142.72, 148.60, 150.61, 152.32 (Caromatic),
195.08 (s, CO), 31P {1H} NMR (DMSO-d6, ppm): δ = 19.82 (s, 1P, CHP).
2.6. Synthesis of [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(4-Me-phen)]CF3SO3 (5)
Silver triflate (Ag-CF3SO3) (0.025 g, 0.1 mM) was added to a solution of 2 (0.05 g,
0.005 mM) in acetonitrile (15 mL). The resulting mixture was stirred for 30 min in the dark
and then filtered through a plug of MgSO4 to remove AgCl. 4-Me-Phenanthroline
(0.019 g, 0.1 mM) was added to the filtrate, and the mixture was stirred for 2 h and then
filtered again through MgSO4. The solvent was removed to ca. 2 mL, and n-hexane
(15 mL) was added to precipitate 5 as a light purple solid, which was collected and air-
1
dried. Yield: 72%. IR (KBr, cmꢀ1): ν(CO) = 1677. H NMR (DMSO-d6, ppm): δ = 2.88

Orthometallated Pd(II) complexes
1777
(m, 3H, CH3), 4.71 (s, 2H, CH2Cl), 5.23 (s, 1H, CHP) 7.44ꢀ8.03 (m, 14H, (C6H4)PPh2),
8.15ꢀ9.56 (m, 6H, phen), 9.70 (br s, Ha, phen). 13C{1H} NMR (DMSO-d6, ppm):
1
δ = 18.76, 36.5 (d, Jpc = 57 Hz), 49.28 (Caliphatic), 119.06, 122.26, 123.44, 124.40, 124.78,
125.05, 125.59, 126.08, 126.22, 126.72, 127.15, 128.24, 129.42, 129.51, 129.70, 129.80,
131.34, 131.50, 132.01, 133.27, 133.37, 135.64, 135.85, 136.97, 138.33, 138.77, 141.75,
149.90, 150.59, 151.23 (Caromatic), 194.91 (s, CO), 31P {1H} NMR (DMSO-d6, ppm):
δ = 19.68 (s, 1P, CHP).
2.7. Synthesis of [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(5-NO2-phen)]CF3SO3 (6)
Silver triflate (Ag-CF3SO3) (0.038 g, 0.12 mM) was added to a solution of 2 (0.068 g,
0.06 mM) in acetonitrile (15 mL). The resulting mixture was stirred for 30 min in the dark
and then filtered through a plug of MgSO4 to remove AgCl. 5-Nitro-phenanthroline
(0.023 g, 0.12 mM) was added to the filtrate, and the mixture was stirred for 2 h and then
filtered again through MgSO4. The solvent was removed to ca. 2 mL, and n-hexane
(15 mL) was added to precipitate 6 as a yellow solid, which was collected and air-dried.
1
Yield: 63%. IR (KBr, cmꢀ1): ν(CO) = 1679. H NMR (DMSO-d6, ppm): δ = 4.71 (s, 2H,
CH2Cl), 5.26 (s, 1H, CHP) 7.48ꢀ7.79 (m, 14H, (C6H4)PPh2), 9.01ꢀ9.35 (m, 6H, phen),
1
9.86 (br s, Ha, phen). 13C{1H} NMR (DMSO-d6, ppm): δ = 37.5 (d, Jpc = 57 Hz), 49.43
(Caliphatic), 119.05, 121.13, 122.40, 124.22, 125.94, 126.07, 126.27, 126.35, 126.92,
127.25, 129.33, 129.45, 129.75, 129.87, 132.05, 132.15, 133.17, 133.29, 133.40, 133.65,
134.46, 135.59, 135.84, 136.31, 140.61, 141.89, 143.89, 144.08, 152.21, 154.28 (Caromatic),
195.6 (s, CO), 31P {1H} NMR (DMSO-d6, ppm): δ = 20.32 (s, 1P, CHP).
2.8. X-ray structure determinations
X-ray diffraction data for 4 and 5 were collected at 295 K using a Bruker APEX-II CCD
diffractometer and corrected for absorption using SADABS [37]. The structures were
solved by direct methods using SIR97 [38] and refined with SHELXL97 [39]. Hydrogens
were positioned geometrically and refined using a riding model approximation, with
C–H=0.93–0.98 Å and with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(C) for methyl H. In 4, chloride
is disordered over two orientations with refined site occupancies of 0.824(2) and 0.176(2)
for the major and minor components, respectively.
3. Results and discussion
3.1. Spectral characterization
The IR spectrum of 1 shows a strong absorption at 1734 cmꢀ1, due to the C=O stretch.
The simultaneous presence of an ylide and a phosphonium is clearly inferred from the
1
NMR spectra of 1. The H NMR spectrum of 1 shows, in addition to the aromatic reso-
2
nances, two signals centered at 4.93 (s) and 5.9 (d, JPH = 12 Hz) attributed, respectively,
to the CH2Cl and CH2ꢀP+ protons. The 31P {1H} NMR spectrum of 1 shows one broad
resonance, centered at 19.84 ppm, and attributed to PCH2.
The treatment of Pd(OAc)2 with 1 (1 : 1 M ratio) gives an insoluble solid, whose stoichi-
ometry corresponds to the chloro-bridged dinuclear complex [Pd{C(H)PPh3C(O)CH2Cl}

1778
K. Karami et al.
(μ-Cl)(OAc)]2 (2) (scheme 1). The C-bonding of the ylide-phosphonium salt can be
inferred from the IR spectrum, since a decrease in the C=O stretch is observed [40, 41].
The IR spectrum also showed strong bands at 1584 and 1334 cmꢀ1 due to asymmetric and
symmetric ν(COO) stretching bands, respectively, which were consistent with monodentate
[42] acetate. The band at 471 cmꢀ1 was assigned to ν(Pd-OAc) [42]. The high insolubility
of 2 in the usual organic solvents prevented a more detailed spectroscopic characterization
of 2. Reactivity of the dimeric complex 2 was studied toward bipy, phen, 4-methyl-1,10-
phenanthroline (4-Me-phen), and 5-nitro-1,10-phenanthroline (5-NO2 phen). The reaction
of 2 with 2 equiv of bidentate N-donor results in formation of the cationic orthometalated
derivatives [Pd{(C,C)-C6H4PPh2C(H)C(O)CH2Cl}(N-N)]CF3SO3 (3–6) (NꢀN=bidentate
N-donor) in good yields. The spectroscopic data of 3–6 are in keeping with the proposed
structure in scheme 1.
The IR spectra show ν(CO) as a strong band at 1671ꢀ1679 cmꢀ1, lower than the parent
phosphonium salt 1. This lowering is well-established in complexes containing other car-
bonyl-stabilized phosphorus ylides [40, 41] and shows that the ligand coordinates through
the carbon and not through oxygen; this has been confirmed for 4 and 5 by X-ray diffrac-
tion. The ν(PꢀC), which is also sensitive to coordination, occurs at 871 cmꢀ1 in the phos-
phonium salt 1 and shifts to lower frequencies for the complexes, suggesting removal of
electron density of the PꢀC bands [29, 43]. The IR spectra of 3–6 also show significant
absorptions at 1029ꢀ1057 cmꢀ1 according to the presence of uncoordinated CF3SOꢀ3 .
The 1H NMR spectra of 3–6 show broad signals for the PC(H) at 5.04ꢀ5.26 ppm,
shifted upfield in comparison with the parent phosphonium salt. Similar behavior has
already been observed for other C-coordinated phosphonium ylide complexes [41].
In 31P {1H} NMR spectra of 3–6, signals due to PC(H) groups are 19.58ꢀ19.68 ppm.
13C {1H} NMR spectra of 4–6 show signals due to the ylidic carbon at 37.1 (1Jpc = 56 Hz),
36.5 (1Jpc = 57 Hz), and 37.5 ppm (1Jpc = 57 Hz), respectively, with characteristic coupling
constants for a C-bonded ylide [32, 35, 41].
There are two factors that promote ortho-metallation: (i) the presence of the acetate in 2
which helps the CꢀH bond breaking by acting as an intramolecular base for deprotonation
[44] and (ii) coordination of chelating (NꢀN) ligands to 2 which leaves the phenyl groups
of the phosphine in close proximity to the ylidic fragments C(H)PPh3 and promotes
ortho-metallation to minimize steric repulsions [41].
3.2. Crystal structures
Single crystals suitable for structure determinations were obtained by slow diffusion of
diethyl ether into chloroform solutions of 4 and 5, respectively. Crystallographic data and
parameters concerning data collection and structure solution and refinement are summa-
rized in table 1. Selected bond lengths (Å) and angles (°) are listed in table 2. An ORTEP
view of the cation of 4 and 5 is shown in figures 1 and 2, respectively. The geometric
parameters describing the coordination environment of the metal and the conformation of
the five-membered metallacycles in the cations of 4 and 5 are very similar. The square pla-
nar coordination geometry of Pd is slightly tetrahedrally distorted, with palladium protrud-
ing from the plane of the N2C2 core by 0.01073(15) and 0.0239(3) Å in 4 and 5,
respectively. Distortion from the regular square planar geometry is indicated by bond
angles subtended at the Pd centers (table 2). The PdꢀCaryl bond distances (1.994(2) and
1.993(4) Å for 4 and 5, respectively) are within the range usually reported for C,C-ortho-
palladated complexes [29, 35]. The PdꢀN2 distances (2.1388(17) and 2.135(3) Å) are

Orthometallated Pd(II) complexes
Table 1. X-ray crystallographic data for 4 and 5.
1779
4
5
Empirical formula
C34H25ClN2OPPd·CF3O3S
C35H27ClN2OPPd·CF3O3S
Formula weight
787.44
801.47
T/K
295(2)
295(2)
Crystal system
Triclinic
Triclinic
Space group
Pꢀ1
Pꢀ1
a/Å
b/Å
c/Å
α/°
β/°
10.3399(5)
10.7947(5)
15.0333(7)
82.6359(7)
82.5068(7)
77.8977(7)
1617.83(13)
2
10.822(2)
10.854(2)
14.801(3)
84.721(3)
76.596(3)
83.400(4)
1676.1(6)
2
γ/°
V/Å3
Z
μ (mmꢀ1
)
0.83
1.616
0.80
1.588
Dcal/Mg mꢀ3
F(000)
792
808
h Range/°
1.4–30.0
9399
1.4–25.3
6066
6066/0/434
1.046
R1 = 0.0448, wR2 = 0.1114
R1 = 0.0514, wR2 = 0.1161
1.86, ꢀ0.87
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices
9399/0/434
1.037
R1 = 0.0323, wR2 = 0.0854
R1 = 0.0383, wR2 = 0.0900
0.75, ꢀ0.68
R indices (all data)
Largest diff. peak and hole (e Åꢀ3
)
Table 2. Selected bond lengths (Å) and angles (°) for 4 and 5.
4
5
Bond lengths (Å)
Pd1–C5
Pd1–C1
Pd1–N1
Pd1–N2
P1–C1
P1–C10
P1–C4
P1–C16
1.994(2)
1.993(4)
2.097(4)
2.109(3)
2.135(3)
1.789(4)
1.802(4)
1.778(4)
1.809(4)
2.0894(18)
2.1074(17)
2.1388(17)
1.7857(18)
1.805(2)
1.777(2)
1.809(2)
Bond angles ( °)
C5–Pd1–C1
C5–Pd1–N1
C1–Pd1–N1
C5–Pd1–N2
C1–Pd1–N2
N1–Pd1–N2
85.13(7)
98.18(8)
175.93(7)
176.86(7)
97.73(7)
79.03(7)
84.94(16)
98.93(16)
173.46(14)
175.95(15)
97.84(14)
78.57(14)
longer than the PdꢀN1 distances (2.1074(17) and 2.109(3) Å) for 4 and 5, respectively,
due to the greater trans influence of the arylic carbon with respect to the ylidic carbon.
The stabilized resonance structure for the parent ylide-phosphonium is destroyed due to
complexation, thus the C1ꢀC2 bond lengths (1.480(3) and 1.478(5) Å) in 4 and 5,
respectively, are significantly longer than the corresponding distances found in similar
uncomplexed phosphoranes (1.407(8) Å [45]), meaning that this bond has been relaxed,

1780
K. Karami et al.
Figure 1. ORTEP plot of 4 with displacement ellipsoids drawn at the 30% probability level. Only the major
component of the disordered chloride is shown.
Figure 2. ORTEP plot of 5 with displacement ellipsoids drawn at the 40% probability level.
while the C2ꢀO1 bond lengths (1.204(3) and 1.202(5) Å in 4 and 5, respectively) are
shorter than observed in similar ligand (1.256(2) Å) [45], which indicates that the C-bond-
ing of the ligand fixes the charge density at C and breaks the conjugation. In the crystal
structures of 4 and 5, the complexes are stabilized by intramolecular CꢀH…O hydrogen
bonds (figures 3 and 4, respectively).

Orthometallated Pd(II) complexes
1781
Figure 3. Packing diagram of 4. Dashed lines represent the hydrogen bonding interactions. Hydrogens not
involved in hydrogen bonding are omitted for clarity.
Figure 4. Packing diagram of 5. Dashed lines represent the hydrogen bonding interaction. Hydrogens not
involved in hydrogen bonding are omitted for clarity. Only the major component of the disordered chloride is
shown.
3.3. Thermogravimetric analysis
Thermogravimetric analyses [46] of 3–6 were carried out to define the influence of
N-donor on the initial decomposition temperature and on the thermal decomposition
mechanism. The steps, initial and final temperatures (°C), partial mass losses (%) for the
thermal decompositions of four complexes, are given in table 3. The thermal decomposi-
tion of 3 occurs in two consecutive steps. The first mass loss occurs between 350ꢀ450 °C

1782
K. Karami et al.
Table 3. Thermal analysis data for 3–6.
Δm (%)
Complex
3
Step
ΔT/°C
Found
Calcd
Assignment
1
2
1
2
1
2
1
2
350ꢀ450
450ꢀ560
360ꢀ450
450ꢀ550
360ꢀ455
455ꢀ560
355ꢀ500
500ꢀ620
38.16
45.23
30.82
56.45
29.94
57.12
28.79
58.61
39.89
46.07
30.41
56.06
29.88
56.83
28.77
58.44
bipy, CF3SO3
ꢀC6H4PPh2C(H)C(O)CH2Cl
ꢀC(H)C(O)CH2Cl, CF3SO3
phen, ꢀC6H4PPh2
4
5
6
ꢀC(H)C(O)CH2Cl, CF3SO3
4-Me-phen, ꢀC6H4PPh2
ꢀC(H)C(O)CH2Cl, CF3SO3
5-No2-phen, ꢀC6H4PPh2
corresponding to, by mass calculation, loss of CF3SO3 and bipy and the uptake of O2. The
second mass loss takes place between 450ꢀ560 °C and corresponds to elimination of
ꢀC6H4-PPh2C(H)C(O)CH2Cl. Complexes 4–6 present similar decomposition patterns. The
first step of decomposition corresponds to release of CF3SO3 and ꢀC(H)C(O)CH2Cl from
355ꢀ500 °C and uptake of O2. From 450ꢀ620 °C, a mass loss occurs which was attrib-
uted to elimination of the bidentate N-donor and ꢀC6H4-PPh2 group. All complexes also
exhibited a mass gain from 550ꢀ850 °C, attributed to PdO formation (ASTM card file
6-0515). This behavior was already observed for other palladium complexes [46, 47]. By
taking into account the initial temperature of the decomposition process, 3–6 show similar
thermal stabilities, indicating that the presence of different N-donor ligands has a minor
influence on the thermal behavior.
4. Conclusion
A new dinuclear complex has been obtained through reaction of the ylide-phosphonium
salt [PPh3CH2C(O)CH2Cl]+Clꢀ (1) with Pd(OAc)2 giving [Pd{C(H)PPh3C(O)CH2Cl}(μ-
Cl)(OAc)]2 (2). Orthometallation can be promoted under mild conditions by reacting 2
with bidentate N-donor chelating ligands resulting in synthesis of mononuclear orthometal-
lated complexes (3–6), in which a five-membered metallacycle is formed. The crystal
structures of 4 and 5 allowed complete characterization of the cyclometallated ligand. The
thermoanalytical data of 3–6 show that the thermal degradation consists of elimination of
the ligands and oxidation of the remaining Pd to PdO.
Supplementary data
CCDC 913735 and 913734 contain the supplementary crystallographic data for 4 and 5,
respectively. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/con-
ts/retrieving.html, or from the Cambridge Crystallographic Data Center, 12 Union Road,
Cambridge CB2 1EZ, UK; Fax: +44 1223 336 033; or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
We are grateful for the financial support from the Department of Chemistry, Isfahan
University of Technology (IUT).

Orthometallated Pd(II) complexes
1783
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