Orthopalladation of phosphorus ylides in endo position with bidentate ligands

Article abstract of DOI:10.1016/j.poly.2010.12.014

The ortho-metallated complexes [Pd₂{κ²(C,C)- C₆H₄(PPh₂CHC(O)C₆H ₅R}₂(μ-Cl)₂] (R = Ph (1a), NO₂ (1b), Br (1c)) were prepared by refluxing equimolar mixtures of Ph ₃PCHC(O)C₆H₅R, (R = Ph, NO₂, Br) and Pd(OAc)₂ in MeOH, followed by an excess of NaCl. The dinuclear complexes (1a-1c) react with silver trifluoromethylsulfonate and bidentate ligands [L = bipy (2,2′-bipyridine), phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), dppp (bis(diphenylphosphino)propane)] giving the mononuclear stabilized orthopalladated complexes in endo position [Pd{κ²(C,C)-C₆H₄(PPh₂CHC(O)R} L](OTf) [R = Ph, L = phen (2a), bipy (3a), dppe (4a), dppp (5a); R = NO ₂, L = phen (2b), bipy (3b), dppe (4b), dppp (5b); R = Br, L = phen (2c), bipy (3c), dppe (4c), dppp (5c); OTf = trifluoromethylsulfonate anion]. Orthometalation and ylidic C-coordination are demonstrated by an X-ray diffraction study of 2c and 3c. In the structures, the palladium atom shows a slightly distorted square-planar coordination geometry.

Full text of DOI:10.1016/j.poly.2010.12.014

Polyhedron 30 (2011) 778–784
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Orthopalladation of phosphorus ylides in endo position with bidentate ligands
b
a
Kazem Karami a, , Corrado Rizzoli , Farzaneh Borzooie
⇑
a Department of Chemistry, Isfahan University of Technology, Isfahan 84156/83111, Iran
b Department of General and Inorganic Chemistry, University of Parma, Parma, Italy
a r t i c l e i n f o
a b s t r a c t
The ortho-metallated complexes [Pd2{j l-Cl)2] (R = Ph (1a), NO2 (1b), Br
2(C,C)-C6H4(PPh2CHC(O)C6H5R}2(
Article history:
Received 21 October 2010
Accepted 10 December 2010
Available online 25 December 2010
(1c)) were prepared by refluxing equimolar mixtures of Ph3P@CHC(O)C6H5R, (R = Ph, NO2, Br) and
Pd(OAc)2 in MeOH, followed by an excess of NaCl. The dinuclear complexes (1a–1c) react with silver tri-
fluoromethylsulfonate and bidentate ligands [L = bipy (2,20-bipyridine), phen (phenanthroline), dppe
(bis(diphenylphosphino)ethane), dppp (bis(diphenylphosphino)propane)] giving the mononuclear stabi-
lized orthopalladated complexes in endo position [Pd{j
2(C,C)-C6H4(PPh2CHC(O)R}L](OTf) [R = Ph,
Keywords:
Phosphorus ylides
Orthopalladation
Bidentate ligands
L = phen (2a), bipy (3a), dppe (4a), dppp (5a); R = NO2, L = phen (2b), bipy (3b), dppe (4b), dppp (5b);
R = Br, L = phen (2c), bipy (3c), dppe (4c), dppp (5c); OTf = trifluoromethylsulfonate anion]. Orthometala-
tion and ylidic C-coordination are demonstrated by an X-ray diffraction study of 2c and 3c. In the struc-
tures, the palladium atom shows a slightly distorted square-planar coordination geometry.
Published by Elsevier Ltd.
1. Introduction
2. Experimental
Phosphorus ylides have found use in a wide variety of reactions
of interest, especially in the synthesis of naturally occurring prod-
ucts and compounds with biological and pharmacological activity
[1]. Metal mediated C–H bond activation is a conspicuous chal-
lenge in organic synthesis. The activation may occur either by
forming the M–C bond (intermolecular or intramolecular) or via
the functionalisation of the C–H group nearest to the metal center
of the complex [2–30]. The orthometalation of phosphorus ylides
[31–39] 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 R or
R0 substituents of the ylidic carbon and, more precisely, belonging
to benzamide moieties [40]. With the above in mind, and as a con-
tinuation of our current research study on phosphorus ylides
[41,42], herein we report the synthesis, spectroscopic and struc-
tural characterization of orthopalladated complexes with biden-
tate ligands such as 2,20-bipyridine (bipy), 1,10-phenanthroline
(phen), bis(diphenylphosphino)ethane (dppe) and bis(diphenyl-
phosphino)propane (dppp).
2.1. Physical measurements and materials
Melting points were measured on a Gallenhamp 9B 3707 F
apparatus. Infrared spectra (4000–400 cmꢀ1) were recorded on a
Jasco 680 FT-IR. 1H NMR and 31P–{1H} NMR spectra were recorded
on CDCl3 at room temperature on a 500 MHz Bruker spectrometer.
Chemical shifts (d) are reported relative to internal TMS and
external 85% phosphoric acid. Elemental analyses were carried
out on a PE 2400 series II analyzer. Pd(OAc)2, 1-([1,10-biphenyl]-
4-yl)-2-bromoethanone, 2-bromo-1-(40-bromo-[1,10-biphenyl]-4-
yl)ethanone, 2-bromo-1-(40-nitro-[1,10-biphenyl]-4-yl)ethanone,
2,20-bipyridine, 1,10-phenanthroline, bis(diphenylphosphino)eth-
ane, bis(diphenylphosphino)propane, PPh3 and AgOTf were pur-
chased from Merck. THF was dried using magnesium sulfate
powder just before use. All other solvents were used without fur-
ther purification.
2.2. Synthesis
2.2.1. Preparation of PhBPPY (a)
To
a
solution of 1-([1,10-biphenyl]-4-yl)-2-bromoethanone
(825 mg, 3 mmol) in CHCl3 (20 ml), a solution of PPh3 (786 mg,
3 mmol) in CHCl3 (5 ml) was added dropwise. After stirring at
room temperature for 4 h, the solution was evaporated to dryness.
The residue was reacted with NaOH (2 g, 0.5 mmol) in EtOH/H2O
⇑
Corresponding author. Tel.: +98 3113912351; fax: +98 3113912350.
E-mail address: karami@cc.iut.ac.ir (K. Karami).
0277-5387/$ - see front matter Published by Elsevier Ltd.
doi:10.1016/j.poly.2010.12.014

K. Karami et al. / Polyhedron 30 (2011) 778–784
779
(1:1 v/v, 20 ml), giving a as a yellow solid. Yield: 887 mg (65%).
C6H4), 7.05–7.31 (m, 14H, Hm, C6H5), 7.30–7.42 (m, 7H, Hp, C6H5),
7.43–7.52 (m, 10H, Ho, PPh2, dppp + Ho, PPh2 + Ho, C6H5), 7.60–
M.p. 230–231 °C. IR (KBr disk, cmꢀ1):
m
1507, 1H NMR (500 MHz,
2
3
CDCl3, ppm): d = 4.52 (d, 1H, CHP, JHH = 24 Hz), 7.38 (t, 1H, Hp,
8.13 (m, 4H, C6H4CO), 7.69 (dd, 2H, Ho, PPh2, dppp, JHH = 8 Hz),
3
3
3
C6H5, JHH = 7 Hz), 7.48 (t, 2H, Hm, C6H5, JHH = 11 Hz), 7.47 (t, 2H,
7.81 (t, 2H, Ho, PPh2, dppp, JHH = 7 Hz). 31P–{1H} NMR (CDCl3,
Hm, C6H4), 7.53 (m, 6H, Hm, PPh3), 7.60 (m, 2H, Ho, C6H5,
ppm): d = ꢀ2.14 (s, 1P, PPh2 trans CH), 14.47 (s, 1P, PPh2cis CH),
3
3JHH = 6 Hz), 7.65 (t, 3H, Hp, PPh3, JHH = 6 Hz), 7.84 (m, 6H, Ho,
25.68 (s, 1P, CHP).
PPh3), 8.08 (d, 2H, Ho, C6H4). 31P–{1H} NMR (CDCl3, ppm):
d = 17.2 (s, 1P, CHP).
2.2.4. Preparation of NO2BPPY (b)
To a solution of 2-bromo-1-(40-nitro-[1,10-biphenyl]-4-yl)etha-
none (732 mg, 3 mmol) in CHCl3 (20 ml), a solution of PPh3
(786 mg, 3 mmol) in CHCl3 (5 ml) was added dropwise. The mix-
ture was stirred at room temperature for 4 h, then it was evapo-
rated to dryness. The residue was reacted with NaOH (2 g,
0.5 mmol) in MeOH/H2O (1:1 v/v, 20 ml), giving b as a yellow solid.
2.2.2. Preparation of [Pd(l-Cl)(PhBPPY)]2 (1a)
A mixture of Pd(OAc)2 (116 mg, 0.52 mmol) in CH2Cl2 (15 ml)
and phosphorus ylide a (237 mg, 0.52 mmol) was refluxed for
24 h at 60 °C. Some decomposition (presence of black Pd) was evi-
dent. The mixture then was evaporated to dryness and the solid
dissolved in MeOH and treated with an excess of NaCl (111 mg,
1.90 mmol). A yellow solid immediately precipitated. The stirring
was maintained for 12 h at room temperature, then the solution
was filtered, and the precipitate washed with Et2O (5 ml) and
water (10 ml) and dried in vacuum. Yield: 324 mg (52%). M.p.
298 °C. Anal. Calc. for C64H48O2Cl2P2Pd2. C, 64.34; H, 4.05; Found.
Yield: 921 mg (72%). M.p. 153 °C. IR (KBr disk, cmꢀ1):
m
1521, 1H
2
NMR (500 MHz, ppm, CDCl3): d = 4.53 (d, 1H, CHP, JPH = 23 Hz),
7.02 (m, 2H, C6H4CO), 7.52–7.59 (m, 6H, Hm, 3C6H5), 7.61–7.69
(m, 3H, Hp, 3C6H5), 7.72–7.76 (m, 6H, Ho, 3C6H5), 8.10–8.23 (dd,
3
2H, C6H4CO, JPH = 9 Hz), 31P–{1H} NMR (CDCl3, ppm): d = 17.20
(s, 1P, CHP).
C, 63.13; H, 3.81. IR (KBr, cmꢀ1):
m
1623, 1H NMR (500 MHz,
ppm, CDCl3): d = 4.90 (s, CHP, minor), 4.97 (s, CHP, major), 7.12–
8.12 (m, 4C6H5 + C6H4CO, both isomers). 31P–{1H} NMR (CDCl3,
ppm): d = 18.41 (sbr both isomers).
2.2.5. Preparation of [Pd(l-Cl)(NO2BPPY)]2 (1b)
A mixture of Pd(OAc)2 (104 mg, 0.46 mmol) in CH2Cl2 (15 ml)
and phosphorus ylide b (195.5 mg, 0.46 mmol) was refluxed for
24 h at 60 °C. Some decomposition was evident. The mixture was
then evaporated to dryness and the brown solid obtained was dis-
solved in MeOH (15 ml), treated with an excess of NaCl (108 mg,
1.84 mmol) and the solution further stirred for 12 h. A green solid
precipitated which was filtered, washed with water (10 ml) and
Et2O (5 ml) and dried in vacuum. Yield: 400 mg (77%). M.p 199–
2.2.3. Preparation of [Pd(L)(PhBPPy)](OTf) with L = phen (2a), bipy
(3a), dppe (4a) or (dppp) (5a)
Compound 1a (75 mg, 0.063 mmol for 2a, 4a and 5a; 49 mg,
0.0407 mmol for 3a) was dissolved in THF (20 mL) and treated
with AgOTf (32 mg, 0.126 mol for 2a, 4a and 5a; 21 mg,
0.082 mmol for 3a). The resulting mixture was stirred for 30 min
at room temperature and then filtered over MgSO4. Afterwards
an equimolar amount of the corresponding ligand L was added
and the solution was stirred for four additional hours, and then
the solvent was evaporated to dryness and the residue treated with
Et2O (5 ml) to give 2a as a pale yellow solid or 3a, 4a and 5a as
white solids. Yields: 75 mg (73%) for 2a, 39 mg (68%) for 3a,
79 mg (66%) for 4a or 71 mg (58%) for 5a.
205 °C (dec). IR (KBr, cmꢀ1):
m
1635, 1H NMR (500 MHz, ppm,
CDCl3): d = 4.83 (s, CHP, minor), 4.95 (s, CHP, major), 7.24–8.15
(m, C6H5 + C6H4CO + C6H4, both isomers). 31P–{1H} NMR (CDCl3,
ppm): d = 19.86 (sbr both isomers).
2.2.6. Preparation of [Pd(L)(NO2BPPY)](OTf) with L = phen (2b), bipy
(3b), dppe (4b) or (dppp) (5b)
A solution of compound 1b (100 mg, 0.088 mmol for 2b; 20 mg,
0.017 mmol for 3b; 60 mg, 0.053 mmol for 4b; 80 mg, 0.071 mmol
for 5b) in THF (20 ml) was treated with AgOTf (45 mg, 0.176 mmol
for 2b; 9 mg, 0.035 mmol for 3b; 27 mg, 0.105 mmol for 4b; 36 mg,
0.140 mmol for 5b). The resulting mixture was stirred for 30 min at
room temperature and then filtered over MgSO4. An equimolar
amount of the corresponding ligand L was then added, the solution
was stirred for four additional hours, the solvent was evaporated to
dryness and the residue treated with Et2O (5 ml for 2b, 4b and 5b)
or CH2Cl2/n-hexane mixture (1:5 v/v, 15 ml for 3b) to give a pale
yellow, pale orange, white or brown solid for 2b, 3b, 4b or 5b
respectively. Yields: 107 mg (78%) for 2b, 16 mg (68%) for 3b,
340 mg (80%) for 4b or 280 mg (84%) for 5b.
Complex 2a. M.p. 190–194 °C (dec). IR (KBr, cmꢀ1):
m
1632, 1H
NMR (500 MHz, ppm, CDCl3): d = 5.56 (s, 1H, CHP), 7.29–7.43 (m,
4H, C6H4), 7.41–7.89 (m, 15H, PPh2 + C6H5), 7.77–7.79 (m, 2H,
phen), 8.10–8.17 (m, 2H, C6H4CO), 8.17–8.18 (d, 2H, C6H4CO,
3
3JHH = 8 Hz), 8.23–8.24 (d, 1H, phen, JHH = 8 Hz), 8.53–8.54 (d,
3
1H, phen, JHH = 8 Hz), 8.89–8.90 (m, 2H, phen), 8.99–9.00 (d, 1H,
3
phen, JHH = 5 Hz), 9.20 (sbr, 1H, phen).31P–{1H} NMR (CDCl3,
ppm): d = 22.28 (s, 1P, CHP).
Complex 3a. M.p. 152–160 °C (dec). IR (KBr, cmꢀ1):
m
1633, 1H
NMR (500 MHz, ppm, CDCl3): d = 5.20 (s, 1H, CHP), 7.25–7.40 (m,
4H, C6H4), 7.45 (t, 2H, Ho, bipy), 7.51–7.56 (m, 6H, Hm, PPh2 + Hm,
C6H5), 7.58–7.65 (m, 7H, Hp, bipy + Hp, PPh2 + Hp, Ho, C6H5), 7.91–
3
8.02 (m, 5H, Ho, PPh2 + C6H4CO), 8.09 (d, 2H, C6H4CO, JHH = 8 Hz),
Complex 2b. M.p. 154–162 °C (dec). IR (KBr, cmꢀ1): 1632, 1H
m
3
8.18 (d, 1H, Ho, PPh2, JHH = 8 Hz), 8.31–8.32 (d, 1H, Ho, bipy,
NMR (500 MHz, ppm, CDCl3): d = 5.79 (s, 1H, CHP), 7.42–7.56 (m,
4H, C6H4), 7.59–7.88 (m, 10H, PPh2), 7.84–7.97 (m, 2H, phen),
8.12 (d, 2H, C6H4CO, 3JHH = 9 Hz), 8.23 (d, 2H, C6H4CO, 3JHH = 9 Hz),
3
3JHH = 8 Hz), 8.41–8.43 (d, 1H, Ho, bipy, JHH = 8 Hz), 8.57 (m, 1H,
3
Hm, bipy). 8.60–8.61 (d, 1H, Hm, bipy, JHH = 6 Hz).31P–{1H} NMR
3
3
(CDCl3, ppm): d = 21.70 (s, 1P, CHP).
8.29 (d, 2H, phen, JHH = 8 Hz), 8.57 (d, 2H, phen, JHH = 8 Hz), 9.01
Complex 4a. M.p. 218–222 °C (dec). IR (KBr, cmꢀ1):
m
1630, 1H
(d, 1H, phen, JHH = 5 Hz), 9.45 (sbr, 1H, phen). 31P–{1H} NMR
3
NMR (500 MHz, ppm, CDCl3): d = 2.70 (m, 4H, CH2, dppe), 4.99 (s,
1H, CHP), 7.01 (m, 4H, C6H4), 7.16 (m, 4H, Hm, PPh2), 7.28 (m,
10H, Hm, dppe + Hp, PPh2), 7.38 (m, 16H, Ho, PPh2 + Ho, Hp, dppe),
7.55 (m, 5H, C6H5), 7.68 (m, 4H, C6H4CO). 31P–{1H} NMR (CDCl3,
ppm): d = 24.93 (s, 1P, CHP), 43.74 (s, 1P, PPh2 trans CH), 53.32
(s, 1P, PPh2 cis CH).
(CDCl3, ppm): d = 22.47 (s, 1P, CHP).
Complex 3b. M.p. 196–202 °C (dec). IR (KBr, cmꢀ1):
m
1628, 1H
NMR (500 MHz, ppm, CDCl3): d = 5.51 (s, 1H, CHP), 7.42–7.47 (m,
3H, Hm, bipy + C6H4), 7.52–8.17 (m, 10H, PPh2), 7.58–7.65 (m, 5H,
Hp, bipy + C6H4), 8.10 (m, 2H, Hm, bipy), 8.29–8.31 (d, 2H, Hm,
3
3
C6H4CO, JHH = 8 Hz), 8.61–8.62 (d, 1H, Ho, bipy, JHH = 5 Hz),
3
Complex 5a. M.p. 214–217 °C (dec). IR (KBr, cmꢀ1):
m
1613, 1H
8.69–8.70 (d, 2H, Ho, C6H4CO, JHH = 4 Hz), 9.01 (sbr, 1H, Ho, bipy).
NMR (500 MHz, ppm, CDCl3): d = 2.25 (m, 2H, CH2, dppp), 2.45
Complex 4b. Mp. 152–158 °C (dec). IR (KBr, cmꢀ1): 1633, 1H
m
2
(m, 4H, CH2, dppp), 4.54 (t, 1H, CHP, JPH = 7 Hz), 6.67 (t, 2H,
NMR (500 MHz, ppm, CDCl3): d = 1.88 (m, 2H, CH2, dppe), 2.31
(m, 2H, CH2, dppe), 4.97 (s, 1H, CHP), 6.93 (m, 2H, C6H4), 6.98
3
3
C6H4, JHH = 9 Hz), 6.79 (t, 1H, C6H4, JHH = 7 Hz), 6.96 (m, 1H,

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K. Karami et al. / Polyhedron 30 (2011) 778–784
3
(m, 2H, C6H4), 7.05–7.26 (m, 2H, Hm, dppe), 7.12–7.43 (m, 22H,
PPh2 + Hm, Hp, Ho, dppe), 7.52 (m, 4H, Ho, dppe), 7.76–7.84 (dd,
2H, C6H4CO, JHH = 2 Hz). 31P–{1H} NMR (CDCl3, ppm): d = 21.19
(s, 1P, CHP).
4H, C6H4CO, JHH = 9 Hz), 7.64 (m, 2H, Hp, dppe). 31P–{1H} NMR
Complex 3c. M.p. 138–140 °C, IR (KBr, cmꢀ1): 1637, 1H NMR
m
3
(CDCl3, ppm): d = 24.67 (s, 1P, CHP), 43.21 (s, 1P, PPh2 trans CH),
(500 MHz, ppm, CDCl3): d = 4.95 (s, 1H, CHP), 7.18–7.78 (m, 14H,
54.87 (s, 1P, PPh2 cis CH).
PPh2 + C6H4), 7.29–7.31 (m, 2H, Hm, bipy), 7.47–7.49 (d, 2H, Hm,
3
3
Complex 5b. M.p. 112–119 °C (dec). IR (KBr, cmꢀ1):
m
1627, 1H
C6H4CO, JHH = 7 Hz), 7.69–7.71 (d, 2H, Ho, C6H4CO, JHH = 8 Hz)
7.83–8.04 (m, 2H, Hp, bipy), 8.01–8.20 (m, 2H, Hm, bipy), 8.38–
8.44 (m, 2H, Ho, bipy). 31P–{1H} NMR (CDCl3, ppm): d = 21.19 (s,
1P, CHP).
NMR (500 MHz, ppm, CDCl3): d = 1.88 (sbr, 1H, CH2, dppp), 2.27
(t, 1H, CH2, dppp, 3JPH = 13 Hz), 2.38 (dt, 1H, CH2, dppp, 3JPH = 5 Hz),
3
2.56 (sbr, 2H, CH2, dppp), 3.77 (t, 1H, CH2, dppp, JPH = 6 Hz), 4.52
3
3
(t, 1H, CHP, JPH = 6 Hz), 6.67 (t, 2H, C6H4, JHH = 9 Hz), 6.81 (t, 1H,
Complex 4c. M.p. 234–236 °C (dec), Anal. Calc. for
3
C6H4, JHH = 7 Hz), 6.97 (m, 1H, C6H4), 7.05 (m, 1H, Hp, dppp),
C m
59H48F3O4P3PdS, C, 63.87; H, 4.36; Found, IR (KBr, cmꢀ1):
7.12 (m, 2H, Hm, dppp), 7.15 (m, 4H, Hm, PPh2), 7.26 (m, 2H, Hp,
PPh2), 7.31 (m, 2H, Hm, dppp), 7.39 (m, 4H, Hm, dppp), 7.44 (m,
3H, Hp, dppp), 7.55-7.78 (m, 8H, Ho, dppp), 7.60–7.69 (m, 1H,
C6H4CO), 7.78–8.05 (m, 4H, Ho, PPh2), 7.89 (d, 2H, C6H4CO,
3JHH = 9 Hz), 8.12 (t, 1H, C6H4CO, 3JHH = 7 Hz).31P–{1H} NMR (CDCl3,
ppm): d = ꢀ2.61 (s, 1P, PPh2 trans CH), 14.81 (s, 1P, PPh2 cis CH),
25.38 (s, 1P, CHP).
1625, 1H NMR (500 MHz, ppm, CDCl3): d = 1.88 (m, 2H, CH2, dppe),
3.76 (m, 2H, CH2, dppe), 4.95 (s, 1P, CHP), 6.98–7.09 (m, 4H, C6H4),
7.04–7.09 (m, 2H, Hm, PPh2), 7.15–7.17 (m, 2H, Hm, PPh2), 7.17–
7.25 (m, 5H, Hm, PPh2, dppe), 7.35–7.37 (m, 3H, Hm, PPh2, dppe),
7.37–7.51 (m, 6H, Hp, C6H5), 7.51–7.61 (m, 12H, Ho, C6H5), 7.65–
7.74 (m, 4H, C6H4CO). 31P–{1H} NMR (CDCl3, ppm): d = 24.55 (s,
1P, CHP), 43.94 (s, 1P, PPh2 trans CH), 53.92 (s, 1P, PPh2 cis CH).
Complex 5c. M.p. 222–224 °C (dec), Anal. Calc. for
C
60H50F3O4P3PdS, C, 64.15; H, 4.49; Found, C, 64.01; H, 4.32, IR
2.2.7. Preparation of BrBPPY (c)
(KBr, cmꢀ1):
m
1623, 1H NMR (500 MHz, ppm, CDCl3): d = 2.20–
To a solution of 2-bromo-1-(40-bromo-[1,10-biphenyl]-4-yl)eth-
anone (834 mg, 3 mmol) in CHCl3 (20 ml), a solution of PPh3
(786 mg, 3 mmol) in CHCl3 (5 ml) was added dropwise. The mix-
ture was stirred at room temperature for 4 h, then it was evapo-
rated to dryness. The residue was reacted with NaOH (2 g,
0.5 mmol) in MeOH/H2O (1:1 v/v, 20 ml), giving c as a white solid.
2
2.70 (m, 6H, CH2, dppp), 4.43 (t, 1H, CHP, JPH = 7 Hz), 6.64–6.98
(m, 4H, C6H4), 7.02–7.22 (m, 4H, Hp, dppp), 7.07–7.20 (m, 8H,
Hm, dppp), 7.37–7.67 (m, 10H, PPh2), 7.37–8.01 (m, 9H, Ho,
dppp + C6H4CO), 7.67 (m, 2H, C6H4CO), 8.09 (m, 1H, C6H4CO).
31P–{1H} NMR (CDCl3): d = ꢀ2.48 (s, 1P, PPh2 trans CH), 14.47 (s,
1P, PPh2 cis CH), 25.57 (s, 1P, CHP).
Yield: 556 mg (67%). M.p. 183 °C, IR (KBr, cmꢀ1):
m
1519, 1H NMR
2
(500 MHz, ppm, CDCl3): d = 4.37 (d, CHP, JPH = 24 Hz), 7.02 (m,
2H, C6H4CO), 7.50 (m, 6H, Hm, 3C6H5), 7.59 (m, 3H, Hp, 3C6H5),
7.73 (m, 6H, Ho, 3C6H5), 7.96 (m, 2H, C6H4CO). 31P–{1H} NMR
(CDCl3, ppm): d = 16.02.
2.3. X-ray crystallography
Single crystals of 2c and 3c suitable for X-ray crystallography
were obtained by diffusion of n-hexane into a CH2Cl2 solution of
each complex. Intensity data were collected at ambient tempera-
2.2.8. Preparation of [Pd(l-Cl)(BrBPPY)]2 (1c)
ture (294(2) K) using graphite monochromated Mo K
a radiation
To a solution of Pd(OAc)2 (85 mg, 0.38 mmol) in CH2Cl2 (15 ml)
phosphorus ylide c (176 mg, 0.38 mmol) was added, and the mix-
ture refluxed for 24 h at 60 °C. Some decomposition (presence of
black Pd) was evident. After evaporating the mixture to dryness,
the solid residue was dissolved in MeOH, treated with an excess
of NaCl (44 mg, 0.76 mmol) and further stirred for 12 h. A pale
green solid immediately precipitated which was filtered, washed
with Et2O (5 ml) and water (10 ml) and dried in vacuum. Yield:
300 mg (66%). M.p. 258–260 °C (dec), Anal. Calc. for
(k = 0.71073 Å) on a Bruker APEX-II CCD diffractometer for 2c
and on a Bruker SMART 1000 CCD diffractometer for 3c. Data were
corrected for absorption using the SABABS program [43].
In both complexes the triflate anion was found to be disordered
over two positions (called A and B), with site occupancy factors of
0.6/0.4 in 2c and 0.75/0.25 in 3c. During the refinement, the S–O,
Oꢁ ꢁ ꢁO, C–F and Fꢁ ꢁ ꢁF distances were constrained to 1.44(1),
2.42(2), 1.32(1) and 2.15(2) Å, respectively. The O, F and C atoms
of the minor component of the disorder were refined isotropically.
Moreover, in 3c the S1A and F1A atoms were refined by restraining
the anisotropic displacement parameters to be approximately iso-
tropic. The dichloromethane solvent molecule in 3c showed rather
C
64H48O2Cl2P2Pd2, C, 64.34; H, 4.05; Found: C, 63.13; H, 3.81; IR
(KBr, cmꢀ1): 1623, 1H NMR (500 MHz, ppm, CDCl3): d = 4.90 (s,
m
CHP, minor): 4.97 (s, CHP, major), 7.12–8.12 (m, 4C6H5 + C6H4CO,
both isomers). 31P–{1H} NMR (CDCl3, ppm): d = 18.41 (sbr both
isomers).
Table 1
Relevant NMR data (d, ppm) for phosphorus ylides a–c and complexes 2a–5c.
2.2.9. Preparation of [Pd(L)(BrBPPY)](OTf) with L = phen (2c), bipy
(3c), dppe (4c) or (dppp) (5c)
Compound
d(CH)
d(P)
Da
A solution of compound 1c (54 mg, 0.045 mmol for 2c and 3c;
25 mg, 0.021 mmol for 4c; 37 mg, 0.031 mmol for 5c) in THF
(20 ml) was treated with AgOTf (23 mg, 0.090 mmol for 2c and
3c; 11 mg, 0.042 mmol for 4c; 16 mg, 0.062 mmol for 5c). The
resulting mixture was stirred for 30 min at room temperature
and then filtered over MgSO4. An equimolar amount of the corre-
sponding ligand L was then added, the solution was stirred for four
additional hours, the solvent was evaporated to dryness and the
residue treated with Et2O (20 ml) to give a white solid for 2c, 4c
and 5c or a yellow solid for 3c. Yields: 58 mg (79%) for 2c, 52 mg
(81%) for 3c, 18 mg (45%) for 4c or 44 mg (79%) for 5c.
a
4.52
5.56
5.20
4.99
4.54
4.50
5.79
5.51
4.97
4.52
4.37
5.62
4.96
4.95
4.43
17.20
22.28
21.70
24.93/43.74/53.32
ꢀ2.14/14.47/25.68
17.27
22.47
22.11
24.67/43.21/54.87
ꢀ2.61/14.81/25.38
16.02
22.43
21.19
24.55/43.94/53.92
ꢀ2.48/14.48/25.57
2a
3a
4a
5a
b
2b
3b
4b
5b
c
56.16/65.74
15.03/31.64
55.6/67.3
14.6/32
2c
3c
4c
5c
Complex 2c. M.p. 172–176 °C (dec). IR (KBr, cmꢀ1):
m
1636, 1H
56.4/66.3
14.7/31.6
NMR (500 MHz, ppm, CDCl3): d = 5.62 (s, 1H, CHP), 7.44–7.52 (m,
D
= d(coordinate) ꢀ d(free). Values for 31P chemical shifts of the free ligands
a
6H, Hm, PPh2 + C6H4), 7.53–7.61 (m, 8H, Hp, Ho, PPh2), 7.58–8.31
3
dppe and dppp are d = ꢀ12.42 and ꢀ17.17 ppm, respectively.
(dd, 2H, C6H4CO, JHH = 2 Hz), 7.87–8.01 (m, 8H, phen), 9.23 (dd,

K. Karami et al. / Polyhedron 30 (2011) 778–784
781
Scheme 1. R = Ph (a), NO2 (b), Br (c); (i) Pd(OAc)2/CH2Cl2/D; (ii) NaCl/MeOH/reflux 24 h; (iii) AgOTf/THF/phen; (iv) AgOTf/THF/bipy; (v) AgOTf/THF/dppe and AgOTf/THF/
dppp.
high thermal parameters, and its site occupancy factor was al-
lowed to vary freely, converging to 0.705(5) [fixed at 0.70 in the
last refinement cycles]. The C–Cl bond lengths were constrained
to be 1.75(1) Å.
All H atoms were placed in calculated positions and treated as
riding on their parent atoms, with C–H = 0.93–0.98 Å, and with Uiso
(H) = 1.2Ueq(C).
spectra as broad signals with unequal populations for the PdCH
groups.
The 31P–{1H} NMR spectra of 2a–2c and 3a–3c show one singlet
at about 22 ppm (Table 1) which is attributed to the CHP of ylide.
The 31P–{1H} NMR spectra of 4a–4c and 5a–5c also show three dif-
ferent signals, corresponding to the three P atoms of the molecules,
one due to the ylide, which shows the presence of the endo-meta-
lated ligand and the other two to the bidentate diphosphine li-
gands dppe and dppp. The 31P NMR spectra of the bidentate
diphosphine have one signal, while the 31P NMR spectra of Pd(II)
complexes with a bidentate diphosphine show two signal due to
different trans effect of arylic and ylidic carbons. It should be worth
noting that in CDCl3 solution the coupling constant between the
phosphorus atoms of the chelate bidentate phosphine ligands is
not observed in the 31P NMR spectra of compounds 4a–4c and
3. Results and discussion
3.1. Spectroscopy
The
1505 to 1515 cmꢀ1 in the parent ylides a–c. Coordination of ylide
through the carbon atom causes an increase in the (CO) band,
whereas for O-coordination a lowering of the (CO) band is ex-
m(CO) band which is sensitive to complexation occurs from
m
5a–5c, possibly due to a fast equilibrium of the type [Pd(
j
2-C,C-yli-
m
de)(OTf)(
j
1-P,P)] M [Pd( 2-C,C-ylide)( 2-P,P]+OTfꢀ. When the sat-
j
j
pected [40]. The IR spectra of all complexes show a strong absorp-
tion in the range of 1620–1630 cmꢀ1, which has been shifted to
higher frequency with respect to the parent ylides, meaning that
the ylides are C-bonded to the palladium center and C-coordina-
urated 5-membered chelate ligand dppe coordinates to Pd(II) ion
in orthopalladated complexes 4a, 4b and 4c, the coordination
tion has occurred. The
m(P–C) band frequencies which are also
diagnostic of the coordination, occur at 881, 860 and 883 cmꢀ1 in
the parent ylides a, b and c respectively, and are shifted to lower
frequencies for the complexes, suggesting some removal of the
electron density of the P–C bands. The IR spectra of all complexes
show significant absorptions at 1268 (vs), 1148 (s), 1032 (s), and
638 (s) cmꢀ1 according to the presence of uncoordinated CF3SO3
.
ꢀ
The 1H NMR signals for the PCH group of complexes 2a–5c are
shifted downfield compared to that of the free ylide (Table 1), as a
consequence of the inductive effect of the metal center. In the 1H
NMR spectra of 1a, 1b and 1c signals due to the methinic proton
are broad (minor) or broad doublet (major). The presence of two
chiral carbon centers (forming diastereoisomers) in each of cis or
trans complex 1–3 (Scheme 2) was confirmed using the 1H NMR
Scheme 2. R = Ph (1a), NO2 (1b), Br (1c).

782
K. Karami et al. / Polyhedron 30 (2011) 778–784
Table 2
Crystal data and structure refinement details for complexes 2c and 3c.
2c
3c
Empirical formula
Formula weight
Temperature (K)
Radiation (k, Å)
Crystal system
Space group
a(Å)
C
38H27BrN2OPPd+.CF3O3Sꢀ.CH2Cl2
C36H27BrN2OPPd+.CF3O3Sꢀ.0.7CH2Cl2
929.39
294(2)
Mo Ka (0.71073)
monoclinic
978.89
294(2)
Mo K
triclinic
P-1
11.4606(4)
12.3861(4)
15.6115(5)
91.6834(5)
99.0562(6)
111.8959(6)
2021.19(12)
2
a
(0.71073)
P21/n
10.6026(17)
21.889(4)
17.254(3)
90.00
100.487(3)
90.00
3937.4(12)
4
1.568
b(Å)
c(Å)
a
(°)
b(°)
c
(°)
V(Å3)
Z
Dcal (Mg/m3)
1.608
1.728
l
(mmꢀ1
)
1.730
Crystal size (mm3)
0.22ꢂ0.14ꢂ0.12
0.12ꢂ0.08ꢂ0.07
No. of reflections collected
No. of independent reflections
No. of data/restraints/parameters
Goodness of fit on F2
22649
38967
7313
7313/39/533
1.031
7135
7135/43/501
0.999
Final R indices (I > 2
r(I))
R1 = 0.0432
wR2 = 0.1209
R1 = 0.0506
wR2 = 0.1250
R1 = 0.0477
wR2 = 0.1097
R1 = 0.0983
wR2 = 0.1182
R indices (all data)
chemical shifts,
D
= d(coordinate) ꢀ d(free), are about 56 and
dium complexes 2a–5c for the CHP group illustrates clear shifts
to downfield as compared to those in the parent ylides a, b and c.
The splitting of the chloride bridges in complexes 1a, 1b and 1c
with neutral bidentate ligands produced exclusively the corre-
sponding mononuclear compounds 2a–2c, 3a–3c, 4a–4c, and 5a–
5c (Scheme 1). The 1H NMR spectra show the expected resonances
for all of the groups present in these molecules and do not show
any unusual features.
66 ppm for ligand dppe, whereas the values for the saturated 6-
membered chelate ligand dppp in complexes 5a, 5b and 5c are
about 14 and 31 ppm, much smaller than those for ligand dppe
(Table 1). Thus, chemical shift 31P–{1H} NMR study on all palla-
Table 3
Selected bond distances (Å) and angles (deg) and hydrogen bonding geometry (Å, °)
for compounds 2c and 3ca.
3.2. X-ray crystallography study
2c
3c
Pd1–N1
Pd1–N2
Pd1–C1
Pd1–C9
P1–C1
P1–C14
P1–C15
P1–C21
N1–Pd1–N2
N1–Pd1–C1
N1–Pd1–C9
N2–Pd1–C1
N2–Pd1–C9
C9–Pd1–C1
2.137(3)
2.094(3)
2.115(3)
1.991(3)
1.794(3)
1.774(3)
1.811(3)
1.809(3)
78.50(11)
99.01(11)
172.88(12)
175.86(11)
97.00(12)
85.79(12)
Pd1–N1
Pd1–N2
Pd1–C1
Pd1–C9
P1–C1
P1–C14
P1–C15
P1–C21
N1–Pd1–N2
N1–Pd1–C1
N1–Pd1–C9
N2–Pd1–C1
N2–Pd1–C9
C9–Pd1–C1
2.132(4)
2.100(4)
2.117(5)
2.017(5)
1.766(5)
1.770(5)
1.822(5)
1.809(5)
78.18(17)
99.10(18)
174.03(19)
174.19(17)
98.33(18)
84.8(2)
Crystallographic data and parameters concerning data
collection and structure solution and refinement are summarized
in Table 2. Selected bond lengths (Å) and angles (°) and hydrogen
bonding interactions for complexes 2c and 3c are listed in Table
2c
D–Hꢁ ꢁ ꢁA
D–H
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
D–Hꢁ ꢁ ꢁA
C26–H26ꢁ ꢁ ꢁO1
C36–H36ꢁ ꢁ ꢁO3A
C4–H4ꢁ ꢁ ꢁO1i
0.93
0.93
0.93
0.93
0.93
0.93
0.97
2.40
2.44
2.51
2.46
2.52
2.48
2.50
2.992(4)
3.136(10)
3.331(13)
3.186(6)
3.321(10)
3.254(9)
3.435(7)
122
131
147
135
144
141
161
C20–H20ꢁ ꢁ ꢁO2Aii
C27–H27ꢁ ꢁ ꢁO2Aii
C29–H29ꢁ ꢁ ꢁO4Aiii
C40–H40Aꢁ ꢁ ꢁO1iv
3c
D–Hꢁ ꢁ ꢁA
D–H
Hꢁ ꢁ ꢁA
Dꢁ ꢁ ꢁA
D–Hꢁ ꢁ ꢁA
C8–H8ꢁ ꢁ ꢁO4
0.93
0.93
0.97
0.93
2.52
2.51
2.44
2.52
3.447(8)
3.410(9)
3.402(13)
3.395(16)
179
163
170
157
C22–H22ꢁ ꢁ ꢁO4
C38–H38Bꢁ ꢁ ꢁO1
C35–H35ꢁ ꢁ ꢁF2Av
a
Symmetry codes: (i) ꢀx, ꢀy, 2 ꢀ z; (ii) ꢀ1 + x, y, z; (iii) ꢀx, ꢀy, 1 ꢀ z; (iv) ꢀx,
1 ꢀ y, 2 ꢀ z; (v) ꢀ1/2 + x, 1/2 ꢀ y, 1/2 + z.
Fig. 1. The structure of the cation in 2c, with displacement ellipsoids drawn at the
30% probability level. Hydrogen atoms are omitted for clarity.

K. Karami et al. / Polyhedron 30 (2011) 778–784
783
the dinuclear complexes with AgOTf and neutral bidentate ligands
phen, bipy, dppe and dppp promotes the synthesis of new mono-
nuclear complexes, in which the five-membered Pd–C–P–C–C
metallacycle remains stable.
Acknowledgements
The authors acknowledge the Department of Chemistry, Isfahan
University of Technology, and Department of General and Inor-
ganic Chemistry, University of Parma, University of Parma, for
financial support. The author thanks the Isfahan University of
Technology (IUT) Research Council and Center of Excellence in Sen-
sor and Green Chemistry (IUT) for supporting this study.
Appendix A. Supplementary data
CCDC 783344 and 783353 contain the supplementary crystallo-
graphic data for compounds 2c and 3c, respectively. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
Fig. 2. The structure of the cation in 3c, with displacement ellipsoids drawn at the
30% probability level. Hydrogen atoms are omitted for clarity.
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l
l-
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