Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived from phosphorus ylides

Article abstract of DOI:10.1016/j.jorganchem.2011.07.046

The phosphorus ylides Ph₃PCHC(O)C₆H₄R (R = 4-Me 1a, 4-Br 1b) react with PdCl₂ in equimolar ratios to give the C,C-orthopalladated [Pd{CHP(C₆H₄)Ph₂CO-C ₆H₄-R

Full text of DOI:10.1016/j.jorganchem.2011.07.046

Journal of Organometallic Chemistry 696 (2011) 3521e3526
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated
derived from phosphorus ylides
,
a
a
b
Seyyed Javad Sabounchei a , Fateme Akhlaghi Bagherjeri , Asghar dolatkhah , Janusz Lipkowski ,
*
Mehdi Khalaj c
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174, Iran
b Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
c Department of Chemistry, Islamic Azad University, Buinzahra Branch, Buinzahra, Qazvin, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
The phosphorus ylides Ph3P]CHC(O)C6H4R (R ¼ 4-Me 1a, 4-Br 1b) react with PdCl2 in equimolar ratios to
Received 14 March 2011
Received in revised form
26 July 2011
give the C,C-orthopalladated [Pd{CHP(C6H4)Ph2CO-C6H4eR)}(
m
-Cl)]2 (R ¼ 4-Me 2a, 4-Br 2b) which react
with NaClO4/dppe, NaClO4/dppm, py and PPh3 to give the mononuclear derivatives [Pd{CH{P(C6H4)Ph2}
COC6H4-R}(dppe-P,P0)[(ClO4) (R ¼ 4-Me 3a, 4-Br 3b), [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppm-P,P0)[(ClO4
( (R ¼ 4-Me 4a, 4-Br 4b), [Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(L)] (L ¼ py, R ¼ 4-Me 5a, 4-Br 5b, L ¼ PPh3,
R ¼ 4-Me 6a, 4-Br 6b). The C, C-metalated chelate are demonstrated by an X-ray diffraction study of 3a and
4a. Characterization of the obtained compounds was also performed by elemental analysis, IR, 1H, 31P, and
13C NMR.
Accepted 29 July 2011
Keywords:
C,C-Chelating
Phosphorus ylide
Palladium
Ó 2011 Elsevier B.V. All rights reserved.
CeH bond activation
Orthopalladation
1. Introduction
2. Experimental
The activation of CeH bonds in organic compounds promoted by
transition metals is one of the most important research topics
nowadays. This is because this process is a mandatory key step in
their functionalization and its relevance is emphasized in the
functionalization of hydrocarbons [1e11]. The orthometallation of
phosphorus ylides R3P]C(R0)(R00) (R ¼ alkyl, aryl; R0 and R00 ¼ H,
alkyl, aryl, acyl) [12e16], is produced, in the vast majority of cases,
regioselectively at the Ph rings of the phosphine unit. Some recent
contributions have shown, however, that it is possible to obtain
orthopalladated complexes derived from CH activation at Ph rings
belonging to the R0 or R00 substituents of the ylidic carbon and, more
precisely, belonging to benzamide moieties [17]. In order to expand
the scope of this type of orthometallated derivatives we studied the
CeH bond activation process, induced by PdCl2, in the ylide ligands
Ph3P]CHC(O)C6H4R (R ¼ 4-Me, 4-Br). In this work, we report the
synthesis, spectroscopic and structural characterization of ortho-
palladated complexes with mono- and bidentate ligands such as
dppe, dppm, py, PPh3 (Scheme 1).
2.1. Physical measurements and materials
All solvents were distilled before use. NMR spectra were
obtained on a 300 MHz Bruker FT-NMR spectrometer in CDCl3 as
the solvent. Chemical shifts (d) are reported relative to internal TMS
(1H and 13C) and external 85% phosphoric acid (31P). Melting points
were measured on a SMPI apparatus. Elemental analyses for C, H
and N were performed using a PE 2400 series II analyzer. IR spectra
were recorded on a Shimadzu FT IR 435-U-04 spectrophotometer
(KBr pellets).
2.2. X-ray crystallography
The X-ray measurements of single crystals of 3a and 4a were
carried out on a Bruker Kappa CCD single crystal diffractometer
equipped with a graphite monochromator and a low temperature
device (Oxford Cryosystems). lambda ¼ 0.71073 Å. Mo-K
a radiation
was used. The collected data were corrected for Lorentz and polar-
ization effects and numerical absorption correctionwas applied. The
structures were solved by direct methods (SHELXS-97 [18]) and
refined using full-matrix least-squares procedures (SHELXL-97
[19]). Non-hydrogen atoms were refined anisotropically, whereas
* Corresponding author. Tel.: þ98 811828280; fax: þ98 8118257408.
E-mail address: jsabounchei@yahoo.co.uk (S. J. Sabounchei).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.07.046

3522
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 696 (2011) 3521e3526
O
Ph3P
C
C
H
R
R= Me (1a), Br (1b)
(i)
O
C
Ph2
P
1/2
CH
R
Pd
Cl
2
O
C
R= Me (2a), Br (2b)
Ph2
P
CH
O
C
ClO4
Ph2
P
CH
Pd
(ii)
R
Pd
(v)
PPh2
Ph2P
(iii)
(iv)
R
R= Me (3a), Br (3b)
Cl
Ph3P
R= Me (6a), Br (6b)
O
Ph2
P
CH
O
C
Ph2
P
CH
Pd
C
ClO4
R
Pd
R
PPh2
R= Me (4a), Br (4b)
Ph2P
Cl
py
R= Me (5a), Br (5b)
Scheme 1. Synthesis and reactivity of orthopalladate phenacyl phosphorus ylides. (i) PdCl2/CH3CN/D; (ii) dppe/CH2Cl2/NaClO4?H2O; (iii) dppm/CH2Cl2/NaClO4?H2O; (iv) py/
CH3COCH3; (v) pph3/CH2Cl2.
hydrogens were placed in calculated positions, and their thermal
with diethyl ether to give 2a as a yellow solid. Yield: 0.19 g, 71.2%.
parameters were refined isotropically.
Anal. Calc. for C54H44Cl2O2P2Pd2: C, 60.58; H, 4.14%. Found: C, 60.73;
H, 4.22%. M.p. 273e275 ꢁC. IR (KBr disk): (cmꢀ1) 1622 (C]O).
n
2.3. Sample preparation
2.3.2.2. Complex 2b. Compound 2b was prepared following the
same synthetic method as that reported for 2a. Thus, PdCl2 (0.09 g,
0.51 mmol) was reacted with 1b (0.918 g, 1.02 mmol) in acetonitrile
(10 ml) to give 2b as a yellow solid. Yield: 0.42 g, 70.0%. Anal. Calc.
for C52H38Br2Cl2O2P2Pd2: C, 52.03; H, 3.19%. Found: C, 51.82; H,
2.3.1. Synthesis of Ph3P]CHC(O)C6H4R and Ph3P]CHC(O)C6H4R
(R ¼ 4-Me 1a, 4-Br 1b)
2.3.1.1. Ylide 1a. Triphenylphosphine (0.262 g, 1 mmol) and
2-bromo-40-methylacetophenone (0.212 g,1 mmol) react in acetone
as solvent to produce the related phosphonium salt. Further treat-
ment with aqueous NaOH solution led to elimination of HBr, giving
3.27%. M.p. 252e254 ꢁC. IR (KBr disk):
n
(cmꢀ1) 1623 (C]O).
the free ligand 1a. IR (KBr disk):
n
(cmꢀ1) 1599 (C]O). 1H NMR
2.3.3. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppe-P,P0)[(ClO4)
(R ¼ 4-Me 3a, 4-Br 3b)
(CDCl3):
d
(ppm) 2.38 (3H, s, Me); 4.36 (1H, d, 2JPH ¼ 23.3 Hz, CH);
7.20e8.81 (19H, m, Ph). 31P NMR (CDCl3):
d
(ppm) 12.98. 13C NMR
2.3.3.1. Complex 3a. To a suspension of 2a (0.042 g, 0.04 mmol) in
CH2Cl2 (15 ml) solid dppe (0.056 g, 0.14 mmol) and NaClO4?1H2O,
0.21 mmol was added, resulting in the immediate precipitation of
NaCl. This suspension was stirred for 35 min at room temperature
and then filtered over Celite. The clear solution was concentrated
(2 ml) and diethyl ether (25 ml) was added to precipitate the white
solid 3a. Yield: 0.062 g. 63.3%. Anal. Calc. for C53H46PdClO5P3: C,
63.80; H, 4.65%. Found: C, 63.96; H, 4.80%. M.p. 161e163 ꢁC. IR (KBr
1
(CDCl3):
d
(ppm) 21.52 (s, Me); 42.19 (d, JPC ¼ 142.24 Hz, CH);
112.48e144.60 (m, Ph); 186.04 (s, CO) [20].
2.3.1.2. Ylide 1b. Compound 1b was prepared following the same
synthetic method as that reported for 1a. Thus, triphenylphosphine
(0.262 g, 1 mmol) was reacted with 2,40-dibromoacetophenone
(0.277 g, 1 mmol) giving the free ligand 1b. IR (KBr disk):
n )
(cmꢀ1
1578 (C]O). 1H NMR (CDCl3):
d
(ppm) 4.39 (1H, d, 2JPH ¼ 23.47 Hz,
disk):
(4H, br, dppe); 4.88 (1H, br, CH); 6.28e7.40 (38H, m, Ph). 31P{1H}
NMR: (ppm) 21.46 (1P, m, CHP); 40.90 (1P, m, PPh2 trans CH);
50.36 (1P, m, PPh2 cis CH). 13C NMR:
(ppm) (CH, was not seen);
n d (ppm) 2.21 (3H, s, Me); 2.63
(cmꢀ1) 1622 (C]O). 1H NMR:
CH); 7.25e8.0 (19H, m, Ph). 31P NMR (CDCl3): (ppm) 14.16.13C NMR
d
(CDCl3):
Ph); 183.51 (s, CO) [21].
d
(ppm) 50.79 (d, 1JPC ¼ 125.03 Hz, CH) 123.65e133.30 (m,
d
d
21.44 (s, Me); 30.33 (br, 2CH2 dppe); 126.17e143.47 (m, Ph); 195.54
2.3.2. Synthesis of [Pd{CHP(C6H4)Ph2COeC6H4eR)}(
2a, 4-Br 2b)
m-Cl)]2 (R ¼ 4-Me
(s, CO).
2.3.2.1. Complex 2a. To a solution of PdCl2 (0.04 g, 0.25 mmol) in
acetonitrile (10 ml),1a (0.2 g, 0.5 mmol) was added and the resulting
mixture was refluxed for 3 h and then allowed to cool to room
temperature. The suspension was filtered and the solid was washed
2.3.3.2. Complex 3b. Compound 3b was prepared following the
same synthetic method as that reported for 3a. Thus, 2b (0.074 g,
0.07 mmol) in CH2Cl2 (15 ml) was added solid dppe (0.056 g,
0.14 mmol) and NaClO4?1H2O, 0.21 mmol to give 3b as a white

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 696 (2011) 3521e3526
3523
solid. Yield: 0.072 g. 51.4%. Anal. Calc. for C52H43PdClO5P3Br: C,
58.78; H, 4.08%. Found: C, 58.43; H, 4.20%. M.p. 170e172 ꢁC. IR (KBr
disk): (ppm) 2.7 (4H, br, dppe); 4.9
(cmꢀ1) 1632 (C]O). 1H NMR:
(1H, br, CH); 7.30e7.57 (38H, m, Ph). 31P{1H} NMR:
(ppm) 25.12
(1P, m, CHP); 44.30 (1P, m, PPh2 trans CH); 56.67 (1P, m, PPh2 cis
CH). 13C NMR:
(ppm) 29.65 (br, 2CH2 dppe); 41.69 (br, CH);
2.3.6. Synthesisof[Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(PPh3)](R¼ 4-Me
6a, 4-Br 6b)
n
d
2.3.6.1. Complex 6a. To a suspension of complex 2a (0.063 g,
0.06 mmol) in CH2Cl2 (10 ml) was added solid PPh3 (0.03 g,
0.12 mmol). The mixture was stirred for 30 min. The resulting
colorless solution was concentrated (2 ml) and diethyl ether (30 ml)
was added to precipitate white solid. Yield: 0.08 g. 84%. Anal. Calc.
for C45H37ClOP2Pd: C, 67.76; H, 4.67%. Found: C, 67.91; H, 4.82%. M.p.
d
d
126.26e136.60 (m, Ph); 195.01 (s, CO).
2.3.4. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppm-P,P0)
[(ClO4) (R ¼ 4-Me 4a, 4-Br 4b)
217e220 ꢁC. IR (KBr disk):
2.32 (3H, s, Me); 5.45 (1H, dd, JPH ¼ 8.78, JPH ¼ 8.39 Hz, CH);
n d (ppm)
(cmꢀ1) 1623 (C]O). 1H NMR:
2
3
2.3.4.1. Complex 4a. To a suspension of 2a (0.127 g, 0.12 mmol) in
CH2Cl2 (15 ml) solid dppm (0.092 g, 0.24 mmol) and NaClO4?1H2O,
0.36 mmol was added, resulting in the immediate precipitation of
NaCl. This suspension was stirred for 35 min at room temperature
and then filtered over Celite. The clear colorless solution was
concentrated (2 ml) and diethyl ether (30 ml) was added to
precipitate 4a as a white solid. Yield: 0.163 g. 69.2%. Anal. Calc. for
C52H44PdClO5P3: C, 63.49; H, 4.51%. Found: C, 63.20; H, 4.41%. M.p.
6.88e8.34 (33H, m, Ph). 31P{1H}:
d (ppm) 12.25 (PPh3) and 28.67
(CHP) (2d, 3JPP ¼ 19.70 Hz).13C NMR:
d (ppm) 21.92 (s, Me); 36.04 (d,
1JPC ¼ 62.88 Hz, CH); 119.71e146.65 (m, Ph); 192.70 (s, CO).
2.3.6.2. Complex 6b. Compound 6b was prepared following the
same synthetic method as that reported for 6a. Thus, to 2b (0.063 g,
0.06 mmol) in CH2Cl2 (10 ml) was added solid PPh3 (0.03 g,
0.12 mmol) to give 6b as a white solid. Yield: 0.060 g. 60%. Anal.
Calc. for C44H34PdClBrOP2: C, 61.27; H, 3.97 Found: C, 61.44; H, 4.10.
219e221 ꢁC. IR (KBr disk):
n d (ppm)
(cmꢀ1) 1630 (C]O). 1H NMR:
2.24 (3H, s, Me); 4.02 (2H, t, 2JPH ¼ 9.67 Hz, CH2 dppm,); 5.13 (1H, dd,
M.p. 250e252 ꢁC. IR (KBr disk)
n
(cmꢀ1) 1629 (C]O). 1H NMR:
3
2
3
2JPH ¼ 5.13, JPH ¼ 2.41 Hz, CH.); 6.66e8.01 (38H, m, Ph). 31P{1H}
d
(ppm) 4.92 (1H, dd, JPH ¼ 7.05, JPH ¼ 6.25 Hz, CH); 7.48e7.83
3
NMR:
d
(ppm) ꢀ34.36 (1P, m, PPh2 trans CH); ꢀ20.30 (1P, m, PPh2 cis
(20H, m, Ph). 31P{1H} NMR:
d
(ppm) 12.03 (d, JPP ¼ 17.76, PPh3),
CH); 19.33 (br, CHP). 13C NMR:
d
(ppm) (CH, was not seen); 21.17 (s,
29.02 (d, JPP ¼ 19.09, CHP). 13C NMR:
d (ppm) 33.30 (d, CH,
3
Me); 38.65 (br, CH2 dppm); 126.32e135.30 (m, Ph); 196.09 (s, CO).
1JPC ¼ 61.78 Hz); 120.99e150.24 (m, Ph); 193.55 (s, CO).
2.3.4.2. Complex 4b. Compound 4b was prepared following the
same synthetic method as that reported for 4a. Thus, to 2b (0.084 g,
0.08 mmol) in CH2Cl2 (15 ml) was added solid dppm (0.061 g,
0.16 mmol) and NaClO4?1H2O, 0.24 mmol to give 4b as a white solid.
Yield: 0.097 g. 58.4%. Anal. Calc. for C51H41PdClO5P3Br: C, 58.42; H,
2.4. Results and discussion
2.4.1. Synthesis
The reflux reactions of PdCl2 with ylides 1a and 1b (prepared by
reacting triphenylphosphine with 2-bromo-40-methylacetophe-
none and 2,40-dibromoacetophenone in acetone and treatment with
aqueous NaOH solution) for 3 h (1:2 molar ratio) in CH3CN gave the
dimeric orthopalladated complexes 2a and 2b as green-yellow solid.
The reactions of 2a and 2b with bidentate diphosphine ligands dppe
and dppm (1:2 molar ratio) in presence of NaClO4?1H2O in CH2Cl2
led to the splitting of the chloride bridge and obtained the mono-
nuclear derivatives that dppe and dppm groups are bonded to the Pd
atom giving fiveand four membered P,P-chelate rings (3a, 3b, 4a and
4b). Also, the reactions 2a and 2b with monodentate ligands py
(excess of pyridine) in acetone and PPh3 (1:2 molar ratio) in CH2Cl2
gave mononuclear derivatives as cis and trans isomers for 5a and 5b
and more stable isomer of trans for 6a and 6b. These isomers have
been characterized by 1H, 31P and 13C NMR measurements.
3.94%. Found: C, 58.24; H, 3.80%. M.p. 255e257 ꢁC. IR (KBr disk):
n
(cmꢀ1) 1630 (C]O).1H NMR:
d
(ppm) 4.01 (2H, t, 2JPH ¼ 8.96 Hz, CH2
dppm); 5.13 (1H, d, 2JPH ¼ 6.63 Hz, CH); 6.86e8 (38H, m, Ph). 31P{1H}
NMR:
d
(ppm) ꢀ29.01 (1P, m, PPh2 trans CH); ꢀ12.84 (1P, m, PPh2 cis
CH); 23.02 (1P, m, CHP).13C NMR:
d (ppm) 29.67 (br, CH2 dppe);
42.14 (br, CH); 125e138 (m, Ph); 195.77 (s, CO).
2.3.5. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(py)] (R ¼ 4-Me
5a, 4-Br 5b)
2.3.5.1. Complex 5a. To a suspension of 2a (0.063 g, 0.06 mmol) in
acetone (5 ml) was added an excess of pyridine (80 mL, 1 mmol) and
the resulting yellow solution was stirred for 14 h at room temper-
ature. After the reaction time, the solvent was concentrated and the
residue treated with cold n-hexane (15 ml) to give a green solid.
Yield: 0.050 g. 65.0%. Anal. Calc. for C32H27PdClNOP: C, 62.55; H,
4.43; N, 2.28%. Found: C, 62.20; H, 4.35; N, 2.18%. M.p. 215e217 ꢁC
2.4.2. Spectroscopy
The IR, 1H- and 31P-NMR data of ligands as well as the corre-
(dec). IR (KBr disk):
Me, major); 2.31 (s, Me, minor); 5.04 (br, CH, major.); 5.15 (br, CH,
minor.); 6.51e8.39 (23H, m, Ph). 31P{1H} NMR:
(ppm) 13.01 (1P, s,
(ppm) 20.03 (s, Me,
n
(cmꢀ1) 1622, (C]O). 1H NMR:
d
(ppm) 2.27 (s,
sponding metal complexes are listed in Table 1. The n(CO) band,
which is sensitive to complexation, occurs at 1599 and 1578 cmꢀ1
d
in the parent ylides 1a and 1b, respectively [20,21]. Coordination of
ylide through the carbon atom causes an increase in the
whereas for O-coordination a lowering of the (CO) band is
expected [22]. The IR spectra of all complexes 2e6 (a and b) show
a strong absorption in the range of 1622e1632 cmꢀ1, meaning that
ylides are C-bonded to the palladium center and C-coordination has
occurred. These isomers appear in 1H and 31P{1H} NMR.
The high insolubility of 2a and 2b in the usual organic solvents
prevented a more detailed spectroscopic characterization of them.
For this reason, these complexes were reacted with dppe, dppm,
py and PPh3 to obtain the mononuclear derivatives (Scheme 1),
which are adequately soluble in organic solvents. The 1H and 31P
{1H} NMR signals for the PCH group of all complexes are shifted
downfield compared to those of the free ylides (1a and 1b), as
a consequence of the inductive effect of the metal center. The 1H
NMR spectra of complexes 5a and 5b show duplicates signals that
must arise from the presence of both possible isomers (cis and
CHP, major.); 17.55 (s, CHP, minor.). 13C NMR:
d
n(CO) band,
minor); 21.41 (s, Me, major); 32.89 (d, 1JPC ¼ 64.06 Hz, CH, minor);
34.33 (d, 1JPC ¼ 60.19 Hz, CH, major); 123.99e152.54 (m, Ph); 196.23
(s, CO, minor); 198.55 (s, CO, major).
n
2.3.5.2. Complex 5b. Compound 5b was prepared following the
same synthetic method as that reported for 5a. Thus, to 2b (0.063 g,
0.06 mmol) in acetone (5 ml) was added an excess of pyridine
(80
Anal. Calc. for C30H22PdClBrNOP: C, 54.16; H, 3.33 Found: C, 53.93;
H, 3.20. M.p. 200-202 ꢁC. IR (KBr disk): (cmꢀ1) 1627 (C]O). 1H
NMR: (ppm) 5.00 (br, CH, major); 5.2 (br, CH, minor.); 7.22e8.75
(23H, m, Ph). 31P{1H} NMR:
mL, 1 mmol) to give 5b as a green solid. Yield: 0.050 g. 58.8%.
n
d
d
(ppm) 19.28 (s, CHP, major.); 22.01 (s,
CHP, minor).13C NMR
d
(ppm) 34.02 (d, CH, 1JPC ¼ 60.34 Hz, minor);
36.21 (d, CH, 1JPC ¼ 62.8 Hz, major); 126.05e150.44 (m, Ph); 195.65
(s, CO, minor); 197.02 (s, CO, major).

3524
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 696 (2011) 3521e3526
Table 1
2.4.3. Crystal structures analysis
IR and NMR data for phosphorus ylides 1a, 1b and related complexes.
The molecular structures of 3a and 4a were determined through
X-ray diffraction methods. A molecular drawing of complexes 3a
and 4a are shown in Figs. 1 and 2, respectively. Crystallographic
data and parameters concerning data collection and structure
solution and refinement are summarized in Table 2 and selected
bond distances and angles are presented in Table 3. Complex 3a
crystallizes on the monoclinic system, in the space group P1 21/c1.
The Pd atom is located on a square-planar environment, sur-
rounded by the methinic carbon C(0BA), the metalated carbon
C(16), and the two phosphor atoms P(21) and P(22) of the chelating
dppe ligand. Complex 4a crystallizes in the triclinic system, on the
space group P-1. The Pd atom is located on a square-planar envi-
ronment, surrounded by the methinic carbon C(15), the metalated
carbon C(16), and the two phosphor atoms P(5) and P(3) of the
chelating dppm ligand. The sum of the bond angles around the
palladium in 3a and 4a is almost 360ꢁ. Although the orthometal-
lated ligand is remarkably warped (especially 4a), the environment
around the Pd is planar. The Pd(1A)eC(0BA) [2.191(3) Å] 3a and
PdeC(15) [2.132(2) Å] 4a bond distances are statistically identical
with those found in related complexes like [Pde(C6H4e2-
pph2C(H)eCOCH2PPh3)(PPh3)(NCMe)]2þ [2.161(8) Å] [28] and
[Pd(dmba)(OH2){CH(CONMe2)(PPh3)}]þ [2.113(6) Å][29]. The
PdeC(16) [2.064(3) Å] 3a and [2.059(2) Å] 4a bond distances are
statistically identical with that found in orthopalladated complex
Compound
n
(CO)
d
(CH)
d(P)
1a
1b
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
1599
1578
1622
1623
1622
1632
1630
1630
1622
1627
1623
1629
4.36
4.39
e
12.98
14.17
e
e
e
4.88
4.9
21.46/40.90/50.36
25.12/44.30/56.67
19.33/ꢀ20.30/ꢀ34.36
23.02/ꢀ12.84/ꢀ29.01
13.01/17.55
19.28/22.01
28.67/12.25
29.03/12.03
5.13
4.01
5.04/5.15
5.00/5.20
5.45
4.92
Values for 31P chemical shifts of the free ligands dppe, dppm and PPh3
are: ꢀ15.00, ꢀ24.88, ꢀ9.96., respectively.
trans, see Scheme 2) [23].These 1H NMR spectra of 5a and 5b show
broad signals for the methinic CH groups due to the coupling with
ylidic phosphorus. The 1H NMR spectra of 4a, 6a and 6b are
consistent with doublet of doublets and that of 4b is triplet and for
3a and 3b are broad signals that must arise from the simulta-
neously coupling with two or three phosphorus centers [12,23].
2
Furthermore, the values of the JPH coupling constants between
the methin proton and the phosphorus atom of the ylide ligands in
these complexes are lower than those of the free ylides, suggesting
that sp2 / sp3 rehybridization of the ylide carbon occurs upon
coordination to the palladium atom [24]. The 31P{1H} NMR spectra
of 3a, 3b, 4a and 4b show three different multiple signals, corre-
sponding to the three P atoms of molecules, one due to ylide,
which shows the presence of the endo-metalated ligand and the
other two to the bidentate diphosphine ligands dppe [25] and
dppm [26]. The 31P{1H} NMR spectra of the bidentate diphosphine
have one signal, while those of Pd(II) complexes with a bidentate
diphosphine show two signals due to different trans effect of arylic
and ylidic carbons (see Table 1). It should be worth noting that in
CDCl3 solution the coupling constant between the phosphorus
atoms of the chelate bidentate phosphine ligands and ylidic
phosphorus are observed in the 13P{1H} NMR spectra of
compounds 3a, 3b, 4a and 4b, although this was not observed
before [13]. The 31P{1H} NMR spectra of 5a and 5b are two singlets
due to cis and trans isomers and those of 6a and 6b show two
doublets around 12 and 29 ppm due to PPh3 and ylidic phos-
phorus, respectively [12,23].
like [Pd{k h -
2-C,NeC6H4e1-[(3, 5-Me2eC3N2)eCH2e( 5-C5H4Fe(h5
C5H5)]}Cl(PPh3)] [2.035(5) Å] [30]. The dppe and dppm groups are
bonded to the Pd atom giving five and four membered P,P-chelate
rings. The distances Pd(1A)eP(22) [2.2914(7) Å] and Pd(1A)e
P(21) [2.3513(7) Å] 3a and PdeP(3) [2.2995(6) Å] and PdeP(5)
[2.3640(6) Å] 4a are quite different, reflecting the different trans
effect of the carbon atom and the arylic carbon [31]. The mutual
trans positions of carbon and phosphorus ligands in palladium(II)
complexes 3a and 4a lead to a weakening of both PdeCaryl and
PdeP bonds (see Table 3) that is called transphobia effect [32,33]
due to
p-acceptor ability of phosphorus atom but this is not exist
on complexes with
s
-donor N atoms in ligands such as bipyridine
(PdeCaryl [ 2.017(5) Å] and PdeN [2.132(4) Å]) and phenanthroline
(PdeCaryl [1.991(3) Å] and PdeN [2.137(3) Å]) [13]. The P(7)eC(0BA)
13C-NMR spectra of these complexes show the upfield shift of
the signals due to the ylidic carbon. Such an upfield shift has been
observed in PdCl(h3e2- XC3H4) (C6H5)3PCHCOR (X ¼ H, CH3;
R ¼ CH3, C6H5) [24] and our synthesized complexes [12,27]. The 13
C
shifts of the CO group in the complexes are around 195 ppm,
relative to 183 and 186 ppm noted for the same carbon in the
parent ylides, indicating much lower shielding of the carbon of the
CO group in these complexes [27].
O
C
O
C
Ph2
P
CH
Ph2
P
CH
R
R
Pd
Pd
Cl
N
N
Cl
R= Me (5a), Br (6a)
Fig. 1. Thermal ellipsoid plot of 3a (50% probability level) showing the numbering
Scheme 2. Possible isomers of complexes 5a and 6a.
scheme. H atoms are omitted for clarity.

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 696 (2011) 3521e3526
3525
Table 3
Selected bond lengths (Å) and bond angles (0) for 3a and4a.
Bond distances
3a
4a
Pd1A-C16
Pd1A-C0BA
Pd1A-P22
Pd1A-P21
P7-C10
P7-C0BA
P7-C8
P7-C5
2.064(3)
2.191(3)
2.2914(7)
2.3513(7)
1.780(3)
1.767(3)
1.797(3)
1.806(3)
1.466(4)
1.230(3)
Pd-C16
Pd-C15
Pd-P3
2.059(2)
2.132(2)
2.2995(6)
2.3640(6)
1.761(2)
1.782(2)
1.808
1.801(2)
1.477(3)
1.233(3)
Pd-P5
P2-C15
P2-C60
Pd-C46
P2-C0AA
C15-C5
C51-O
C0BA-C13
C13-O19
Bond angles
P21-Pd1A-C0BA
P21-Pd1A-P22
C0BA-Pd1A-C16
C16-Pd1A-P22
C16- Pd1A- P21
C0BA- Pd1A- P22
Pd1A-C16-C10
Pd1A-C0BA-P7
Pd1A-P22-C32
Pd1A-P21-C30
95.81(7)
84.73(2)
85.20(10)
93.81(8)
176.42(8)
172.44(7)
115.17(19)
97.57(12)
106.89
P3-Pd-C16
P3-Pd-P5
101.48(7)
71.17(2)
104.07(6)
83.36(9)
172.22(6)
174.90(6)
99.94(10)
117.13(16)
91.39(7)
P5-Pd-C15
C15-Pd-C16
C16-Pd-P5
C15-Pd-P3
Pd-C15-P2
Pd-C16-C60
Pd-P5-C11
Pd-P3-C11
104.64(9)
93.50(7)
Fig. 2. Thermal ellipsoid plot of 4a (50% probability level) showing the numbering
scheme. H atoms are omitted for clarity.
are longer than that found in the uncomplexed phosphorane
(1.407(8) Å) [35], meaning that this bond has been relaxed, while
the C(13)eO(19) [1.230(3) Å] 3a and C(51)eO [1.233(3) Å] 4a bond
distances are shorter than that observed in the similar ligand
[1.256(2) Å] [35]. Then, the C-bonding of the ligand fixes the density
charge at the C atom and breaks the conjugation.
[1.767(3) Å] 3a and P(2)eC(15) [1.761(2) Å] 4a bond distances are
significantly longer than that observed in the similar ylide 1.706 Å
[34]. The effect of the coordination and subsequent loss of conju-
gation is more evident on the CCO fragment. The C(0BA)eC(13)
[1.466(4) Å] 3a and the C(15)eC(51) [1.477(3) Å] 4a bond distances
3. Conclusions
Table 2
Crystal Data and Structure Refinement for Compounds 3a and 4a.
The palladation of stabilized phosphoylides Ph3P]CHC(O)
C6H4R occurs regioselectively at the phenyl rings of the PPh3 group
and gives five-membered endo metallacycles of high stability. The
reaction of the dinuclear complexes with NaClO4.1H2O and neutral
bidentate ligands dppe and dppm and monodentate ligands py and
PPh3 promotes the synthesis of new mononuclear complexes, in
which the five-membered Pd-C-P-C-C metallacycle remains stable.
Also the reaction of these complexes with py leads to complexes
with two isomers (cis and trans) whereas PPh3 lead to more stable
isomer trans.
3a
4a
empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
space group
a (Å)
C54 H47 Cl4 O5 P3Pd
1117.03
120.(1)
0.7107
monoclinic
P1 21/c 1
20.7104(6)
11.8844(3)
22.4652(7)
90.00
116.478(4)
90.00
4949.4(2)
4
1.499
C52 H44 Cl O5 P3 Pd
983.63
120(1)
0.71073
triclinic
P-1
11.7852(6)
13.2128(7)
16.5537(7)
70.866(4)
77.456(4)
65.314(5)
2203.01(19)
2
b (Å)
c (Å)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
Volume (Å3)
Acknowledgments
Z
Dcalc (Mg/m3)
1.483
0.641
1008
We are grateful to the Bu-Ali Sina University for a grant and
Mr. Zebarjadian for recording the NMR spectra.
Absorption coefficient (mm_1
F(000)
)
0.737
2280
cryst size (mm3)
0.3293 ꢂ 0.2278
0.4378 ꢂ 0.2091
Appendix A. Supplementary material
ꢂ 0.0591
ꢂ 0.0603
q
Range for data collection
2.48e26.37
ꢀ25 ꢃ h ꢃ 25
ꢀ14 ꢃ k ꢃ 14
ꢀ27 ꢃ l ꢃ 28
43051/10082
[R(int) ¼ 0.0289]
0.957 and 0.846
3.20e26.37
ꢀ11 ꢃ h ꢃ 14
ꢀ12 ꢃ k ꢃ 16
ꢀ20 ꢃ l ꢃ 20
14278/8946[R(int)
¼ 0.0223]
1.00 and 0.97405
Limiting indices
CCDC 806209 and 806210 contain the supplementary crystal-
lographic data for the complexes 3a and 4a, respectively. These data
can be obtained free of charge from the Cambridge Crystallographic
Data Center via http://www.ccdc.cam.ac.uk/data_request/cif.
Reflections collected/unique
Maximum and minorimum
transmission
Refinement method
Appendix. Supplementary information
Full-matrix
Full-matrix
least-squares on F2
analytical
least-squares on F2
multi-scan
Absorption correction
Data/restraints/parameters
goodness-of-fit on F2
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2011.07.046.
10082/15/624
1.027
8946/0/560
1.048
Final R indices [I > 2
s
(I)]
R1 ¼ 0.0347,
wR2 ¼ 0.0969
R1 ¼ 0.0426,
wR2 ¼ 0.0919
1.092 and ꢀ1.032
R1 ¼ 0.0318,
wR2 ¼ 0.0735
R1 ¼ 0.0389,
wR2 ¼ 0.0689
0.763 and ꢀ0.439
References
R indices (all data)
[1] J. Le Bras, J. Muzart, Chem. Rev. 111 (2011) 1170e1214.
[2] D.A. Colby, R.G. Bergman, J.A. Ellman, Chem. Rev. 110 (2010) 624e655.
[3] C. Copéret, Chem. Rev. 110 (2010) 656e680.
largest diff. peak, hole (eâÅꢀ3
)

3526
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 696 (2011) 3521e3526
[4] M.P. Doyle, R. Duffy, M. Ratnikov, L. Zhou, Chem. Rev. 110 (2010) 704e724.
[5] C.-M. Che, V. Kar-Yan Lo, C.-Y. Zhou, J.-S. Huang, Chem. Soc. Rev. 40 (2011)
1950e1975.
[21] S.J. Sabounchei, A.R. Dadrass, Asian J. Chem. 19 (2007) 5471e5476.
[22] J.A. Albanese, D.L. Staley, A.L. Rheingold, J.L. Burmeister, Inorg. Chem. 29
(1990) 2209e2213.
[6] W.R. Gutekunst, P.S. Baran, Chem. Soc. Rev. 40 (2011) 1976e1991.
[7] H. Davies, J. Du Bois, J.-Q. Yu, Chem. Soc. Rev. 40 (2011) 1855e1856.
[8] A.S. Tsai, R.G. Bergman, J.A. Ellman, J. Am. Chem. Soc. 130 (2008) 6316e6317.
[9] R. Giri, B.-F. Shi, K.M. Engle, N. Maugel, J.-Q. Yu, Chem. Soc. Rev. 38 (2009)
3242e3272.
[10] T.W. Lyons, M.S. Sanford, Chem. Rev. 110 (2010) 1147e1169.
[11] H.-Q. Do, O. Daugulis, J. Am. Chem. Soc. 130 (2008) 1128e1129.
[12] S.J. Sabounchei, H. Nemattalab, F. Akhlaghi, H.R. Khavasi, Polyhedron 27
(2008) 3275e3279.
[23] J. Vicente, M.T. Chicote, J. Fernandez-Baeza, J. Organomet. Chem. 364 (1989)
407e414.
[24] G. Facchin, R. Bertani, M. Calligaris, G. Nardin, M. Mari, J. Chem. Soc. Dalton
Trans. (1987) 1381e1387.
[25] C. Cativiela, L.R. Falvello, J.C. Ginés, R. Navarro, E.P. Urriolabeitia, New J. Chem.
25 (2001) 344e352.
[26] P.E. Garrou, Chem. Rev. 85 (1985) 171e185.
[27] S.J. Sabounchei, H. Nemattalab, S. Salehzadeh, S. Khani, M. Bayat, H.R. Khavasi,
Polyhedron 27 (2008) 2015e2021.
[13] K. Karami, C. Rizzoli, F. Borzooie, Polyhedron 30 (2011) 778e784.
[14] E.P. Urriolabeitia, Dalton Trans. (2008) 5673e5686.
[15] E. Serrano, C. Vallés, J.J. Carbó, A. Lledós, T. Soler, R. Navarro, E.P. Urriolabeitia,
Organometallics 25 (2006) 4653e4664.
[28] L.R. Falvello, S. Fernández, R. Navarro, A. Rueda, E.P. Urriolabeitia, Organo-
metallics 17 (1998) 5887e5900.
[29] I.C. Barco, L.R. Falvello, S. Fernández, R. Navarro, E.P. Urriolabeitia, J. Chem. Soc.
Dalton Trans. (1998) 1699e1706.
[16] K. Muñiz, Transition Metal Catalyzed Electrophilic Halogenation of CeH bonds
in Alpha-Position to Carbonyl Groups (Topics in Organometallic Chemistry),
First ed. Springer, 2010.
[17] D. Aguilar, M.A. Aragüés, R. Bielsa, E. Serrano, R. Navarro, E.P. Urriolabeitia,
Organometallics 26 (2007) 3541e3551.
[18] G.M. Sheldrick, SHELXS 97, Program for the Solution of Crystal Structures.
University of Göttingen, Germany, 1997.
[19] G.M. Sheldrick, SHELXL 97, Program for the Refinement of Crystal Structures.
University of Göttingen, Germany, 1997.
[30] A. González, C. López, X. Solans, M. Font-Bardía, E. Molins, J. Organomet.
Chem. 693 (2008) 2119e2131.
[31] D. Aguilar, M. Angel Aragüés, R. Bielsa, E. Serrano, T. Soler, R. Navarro,
E.P. Urriolabeitia, J. Organomet. Chem. 693 (2008) 417e424.
[32] J. Vicente, J.A. Abad, A.D. Frankland, M.C. Ramírez de Arellano, Chem. Eur. J. 5
(1999) 3066e3075.
[33] J. Vicente, A. Arcas, D. Bautista, Organometallics 16 (1997) 2127e2138.
[34] R. Usón, J. Forniés, R. Navarro, P. Espinet, C. Mendívil, J. Organomet. Chem. 290
(1985) 125e131.
[20] N.A. Nesmeyanov, E.V. Binshtok, O.A. Reutov, Dokl. Akad. Nauk SSSR 198
(1971) 1102e1106.
[35] S.J. Sabounchei, A.R. Dadras, M. Jafarzadeh, H.R. Khavasi, Acta Cryst. E63
(2007) 3160.