Accepted Manuscript Title: Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived from phosphorus ylides Authors: Seyyed Javad Sabounchei, Fateme Akhlaghi Bagherjeri, Asghar dolatkhah, Janusz Lipkowski, Mehdi Khalaj PII:
S0022-328X(11)00504-3
DOI:
10.1016/j.jorganchem.2011.07.046
Reference:
JOM 17227
To appear in:
Journal of Organometallic Chemistry
Received Date: 14 March 2011 Revised Date:
26 July 2011
Accepted Date: 29 July 2011
Please cite this article as: S.J. Sabounchei, F.A. Bagherjeri, A. dolatkhah, J. Lipkowski, M. Khalaj. Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived from phosphorus ylides, Journal of Organometallic Chemistry (2011), doi: 10.1016/j.jorganchem.2011.07.046 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
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Graphical abstract: Pictogram
Synthesis and structure of mono- and di-nuclear complexes
M AN U
SC
of ortho-palladated derived from phosphorus ylides
Seyyed Javad Sabounchei, Fateme Akhlaghi Bagherjeri, Asghar dolatkhah, Janusz
TE D
Lipkowski and Mehdi Khalaj
O Ph2 P C CH R
Pd
O Ph2 P C CH
R
Pd PPh2
ClO4
O Ph2 P C CH
R
Pd Ph2P
PPh2
R=Me, Br
2
dppe
O Ph2 P C CH
PPh3
dppm
AC C
Ph2P
EP
Cl
py Ph3P O Ph2 P C CH
ClO4
R
Pd py
Cl
R
Pd Cl
ACCEPTED MANUSCRIPT
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Graphical abstract: Synopsis
Synthesis and structure of mono- and di-nuclear complexes
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SC
of ortho-palladated derived from phosphorus ylides
Seyyed Javad Sabounchei, Fateme Akhlaghi Bagherjeri, Asghar dolatkhah, Janusz Lipkowski and Mehdi Khalaj
Reaction
of
two
the
C,C-orthopalladated
TE D
[Pd{CHP(C6H4)Ph2CO-C6H4-R)}(µ-Cl)]2
(R=
4-Me,
4-Br)
complexes with
NaClO4/dppe, NaClO4/dppm, Py and PPh3 is reported. X-ray crystal structures
(3a)
of
and
EP
P,P')](ClO4)
analysis
[Pd{CH{P(C6H4)Ph2}COC6H4-CH3}(dppe-
[Pd{CH{P(C6H4)Ph2}COC6H4-CH3}(dppm-
P,P')](ClO4) (4a) shows that the C, C-metalated chelate has occurred.
AC C
Characterization of the obtained compounds was also performed by elemental analysis, IR, 1H, 31P, and 13C NMR.
ACCEPTED MANUSCRIPT Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived
1
from phosphorus ylides
2 3 4
Lipkowskib and Mehdi Khalajc
5
7
Fax: +988118257408
8
SC
Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174, Iran, Tel: +98811828280,
b
c
6
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
9
Warsaw, Poland
10
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a
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Seyyed Javad Sabounchei*a, Fateme Akhlaghi Bagherjeria, Asghar dolatkhaha, Janusz
Department of Chemistry, Islamic Azad University, Buinzahra Branch, Buinzahra, Qazvin,
11
Iran
12
Abstract:
13
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The phosphorus ylides Ph3P=CHC(O)C6H4R (R= 4-Me 1a, 4-Br 1b) react with PdCl2 in
14 15
(R= 4-Me 2a, 4-Br 2b) which react with NaClO4/dppe, NaClO4/dppm, py and PPh3 to give
16
the mononuclear derivatives [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppe-P,P')](ClO4) (R=4-Me
17
3a, 4-Br 3b), [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppm-P,P')](ClO4 ) (R=4-Me 4a, 4-Br 4b),
18
AC C
EP
equimolar ratios to give the C,C-orthopalladated [Pd{CHP(C6H4)Ph2CO-C6H4-R)}(µ-Cl)]2
[Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(L)] (L=py, R=4-Me 5a, 4-Br 5b, L= PPh3, R=4-Me 6a,
19
4-Br 6b). The C, C-metalated chelate are demonstrated by an X-ray diffraction study of 3a
20
and 4a. Characterization of the obtained compounds was also performed by elemental
21
analysis, IR, 1H, 31P, and 13C NMR.
22
* Corresponding author.
23
E-mail address:
[email protected] (S.J. Sabounchei).
24
1
ACCEPTED MANUSCRIPT Keywords: C,
C-chelating,
phosphorus
ylide,
Palladium,
C-H
bond
activation,
Orthopalladation
25 26 27
1.Introduction
28 29
of the most important research topics nowadays. This is because this process is a mandatory
30
key step in their functionalization and its relevance is emphasized in the functionalization of
31
hydrocarbons [1-11]. The orthometallation of phosphorus ylides R3P=C(R')(R") (R = alkyl,
32
aryl; R′ and R″ = H, alkyl, aryl, acyl) [12-16], is produced, in the vast majority of cases,
33
regioselectively at the Ph rings of the phosphine unit. Some recent contributions have shown,
34
however, that it is possible to obtain orthopalladated complexes derived from CH activation
35
at Ph rings belonging to the R' or R" substituents of the ylidic carbon and, more precisely,
36
belonging to benzamide moieties [17]. In order to expand the scope of this type of
37
orthometallated derivatives we studied the C–H bond activation process, induced by PdCl2, in
38
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The activation of C-H bonds in organic compounds promoted by transition metals is one
39
synthesis, spectroscopic and structural characterization of orthopalladated complexes with
40
mono- and bidentate ligands such as dppe, dppm, py, PPh3 (Scheme 1).
41
EP
the ylide ligands Ph3P=CHC(O)C6H4R (R= 4-Me, 4-Br). In this work, we report the
AC C
42
2. Experimental
43
2.1. Physical measurements and materials
44
All solvents were distilled before use. NMR spectra were obtained on a 300 MHz Bruker
45
FT-NMR spectrometer in CDCl3 as the solvent. Chemical shifts (δ) are reported relative to
46
internal TMS (1H and
C) and external 85% phosphoric acid (31P). Melting points were
47
measured on a SMPI apparatus. Elemental analyses for C, H and N were performed using a
48
13
2
ACCEPTED MANUSCRIPT PE 2400 series II analyzer. IR spectra were recorded on a Shimadzu FT IR 435-U-04
49
spectrophotometer (KBr pellets).
50 51
2.2. X-ray crystallography
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52
53
Kappa CCD single crystal diffractometer equipped with a graphite monochromator and a low
54
temperature device (Oxford Cryosystems). lambda = 0.71073Å. Mo-K radiation was
55
used. The collected data were corrected for Lorentz and polarization effects and numerical
56
absorption correction was applied. The structures were solved by direct methods (SHELXS-
57
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The X-ray measurements of single crystals of 3a and 4a were carried out on a Bruker
97 [18]) and refined using full-matrix least squares procedures (SHELXL-97 [19]). Non-
58
hydrogen atoms were refined anisotropically, whereas hydrogens were placed in calculated
59
positions, and their thermal parameters were refined isotropically.
60
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2.3. Sample preparation
61
2.3.1. Synthesis of Ph3P=CHC(O)C6H4R and Ph3P=CHC(O)C6H4R (R=4-Me 1a, 4-Br 1b)
63
EP
Ylide 1a: Triphenylphosphine (0.262 g, 1 mmol) and 2-bromo-4'-methylacetophenone
64 65
Further treatment with aqueous NaOH solution led to elimination of HBr, giving the free
66
ligand 1a. IR (KBr disk): ν (cm-1) 1599 (C=O). 1H NMR (CDCl3): δ (ppm) 2.38 (3H, s, Me);
67
4.36 (1H, d, 2JPH = 23.3 Hz, CH); 7.20–8.81 (19H, m, Ph). 31P NMR (CDCl3): δ (ppm) 12.98.
68
13
69
AC C
(0.212 g, 1 mmol) react in acetone as solvent to produce the related phosphonium salt.
C NMR (CDCl3): δ (ppm) 21.52 (s, Me); 42.19 (d, 1JPC = 142.24 Hz, CH); 112.48– 144.60
(m, Ph); 186.04 (s, CO) [20].
70
Ylide 1b: Compound 1b was prepared following the same synthetic method as that
71
reported for 1a. Thus, triphenylphosphine (0.262 g, 1 mmol) was reacted with 2,4'-
72
dibromoacetophenone (0.277 g, 1 mmol) giving the free ligand 1b. IR (KBr disk): ν (cm-1)
73
3
ACCEPTED MANUSCRIPT 1578 (C=O). 1H NMR (CDCl3): δ (ppm) 4.39 (1H, d, 2JPH = 23.47 Hz, CH); 7.25–8.0 (19H, m, Ph).
31
P NMR (CDCl3): δ (ppm) 14.16.
13
C NMR (CDCl3): δ (ppm) 50.79 (d, 1JPC =
125.03 Hz, CH) 123.65– 133.30 (m, Ph); 183.51 (s, CO) [21].
74 75 76 77
2.3.2. Synthesis of [Pd{CHP(C6H4)Ph2CO-C6H4-R)}(µ-Cl)] 2 (R=4-Me 2a, 4-Br 2b)
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78 79
0.5 mmol) was added and the resulting mixture was refluxed for 3h and then allowed to cool
80
to room temperature. The suspension was filtered and the solid was washed with diethyl ether
81
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Complex 2a. To a solution of PdCl2 (0.04 g, 0.25 mmol) in acetonitrile (10 ml), 1a (0.2 g,
82
60.58; H, 4.14%. Found: C, 60.73; H, 4.22%. M.p. 273–275 °C . IR (KBr disk): ν (cm-1) 1622
83
(C=O).
84
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to give 2a as a yellow solid. Yield: 0.19 g, 71.2%. Anal. Calc. for C54H44Cl2O2P2Pd2: C,
85
reported for 2a. Thus, PdCl2 (0.09 g, 0.51 mmol) was reacted with 1b (0.918 g, 1.02 mmol)
86
in acetonitrile (10 ml) to give 2b as a yellow solid. Yield: 0.42 g, 70.0%. Anal. Calc. for
87
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Complex 2b. Compound 2b was prepared following the same synthetic method as that
C52H38Br2Cl2O2P2Pd2: C, 52.03; H, 3.19%. Found: C, 51.82; H, 3.27%. M.p. 252–254 °C . IR
88
(KBr disk): ν (cm-1) 1623 (C=O).
89
EP
90
3b)
AC C
2.3.3. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppe-P,P')](ClO4) (R=4-Me 3a, 4-Br
91 92
Complex 3a. To a suspension of 2a (0.042 g, 0.04 mmol) in CH2Cl2 (15 ml) solid dppe
93
(0.056 g, 0.14 mmol) and NaClO4?1H2O, 0.21 mmol was added, resulting in the immediate
94
precipitation of NaCl. This suspension was stirred for 35 minutes at room temperature and
95
then filtered over Celite. The clear solution was concentrated (2 ml) and diethyl ether (25 ml)
96
was added to precipitate the white solid 3a. Yield: 0.062 g. 63.3%. Anal. Calc. for
97
C53H46PdClO5P3: C, 63.80; H, 4.65%. Found: C, 63.96; H, 4.80%. M.p. 161–163 °C . IR (KBr
98
4
ACCEPTED MANUSCRIPT disk): ν (cm-1) 1622 (C=O). 1H NMR: δ (ppm) 2.21 (3H, s, Me); 2.63 (4H, br, dppe); 4.88 P{1H} NMR: δ (ppm) 21.46 (1P, m, CHP); 40.90
100
(1P, m, PPh2 trans CH); 50.36 (1P, m, PPh2 cis CH). 13C NMR: δ (ppm) (CH, was not seen);
101
21.44 (s, Me); 30.33 (br, 2CH2 dppe); 126.17–143.47 (m, Ph); 195.54 (s, CO).
102
(1H, br, CH); 6.28–7.40 (38H, m, Ph).
31
99
103
reported for 3a. Thus, 2b (0.074 g, 0.07 mmol) in CH2Cl2 (15 ml) was added solid dppe
104
(0.056 g, 0.14 mmol) and NaClO4?1H2O, 0.21 mmol to give 3b as a white solid. Yield: 0.072
105
g. 51.4%. Anal. Calc. for C52H43PdClO5P3Br: C, 58.78; H, 4.08%. Found: C, 58.43; H,
106
4.20%. M.p. 170–172 °C . IR (KBr disk): ν (cm-1) 1632 (C=O). 1H NMR: δ (ppm) 2.7 (4H, br,
107
P{1H} NMR: δ (ppm) 25.12 (1P, m,
108
CHP); 44.30 (1P, m, PPh2 trans CH); 56.67 (1P, m, PPh2 cis CH). 13C NMR: δ (ppm) 29.65
109
(br, 2CH2 dppe); 41.69 (br, CH); 126.26–136.60 (m, Ph); 195.01 (s, CO).
110
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dppe); 4.9 (1H, br, CH); 7.30–7.57 (38H, m, Ph).
31
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Complex 3b. Compound 3b was prepared following the same synthetic method as that
111
4b)
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2.3.4. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}(dppm-P,P')](ClO4) (R=4-Me 4a, 4-Br
112 113 114
(0.092g, 0.24 mmol) and NaClO4?1H2O, 0.36 mmol was added, resulting in the immediate
115
precipitation of NaCl. This suspension was stirred for 35 minutes at room temperature and
116
AC C
EP
Complex 4a. To a suspension of 2a (0.127 g, 0.12 mmol) in CH2Cl2 (15 ml) solid dppm
then filtered over Celite. The clear colorless solution was concentrated (2 ml) and diethyl
117
ether (30 ml) was added to precipitate 4a as a white solid. Yield: 0.163g. 69.2%. Anal. Calc.
118
for C52H44PdClO5P3: C, 63.49; H, 4.51%. Found: C, 63.20; H, 4.41%. M.p. 219–221 °C . IR
119
(KBr disk): ν (cm-1) 1630 (C=O). 1H NMR: δ (ppm) 2.24 (3H, s, Me); 4.02 (2H, t, 2JPH = 9.67
120
Hz, CH2 dppm,); 5.13 (1H, dd, 2JPH = 5.13, 3JPH = 2.41 Hz, CH.); 6.66–8.01 (38H, m, Ph).
121
31
122
P{1H} NMR: δ (ppm) -34.36 (1P, m, PPh2 trans CH); -20.30 (1P, m, PPh2 cis CH); 19.33
5
ACCEPTED MANUSCRIPT (br, CHP).
13
C NMR: δ (ppm) (CH, was not seen); 21.17 (s, Me); 38.65 (br, CH2 dppm);
126.32–135.30 (m, Ph); 196.09 (s, CO).
123 124 125
reported for 4a. Thus, to 2b (0.084 g, 0.08 mmol) in CH2Cl2 (15 ml) was added solid dppm
126
(0.061 g, 0.16 mmol) and NaClO4?1H2O, 0.24 mmol to give 4b as a white solid. Yield:
127
0.097g. 58.4%. Anal. Calc. for C51H41PdClO5P3Br: C, 58.42; H, 3.94%. Found: C, 58.24; H,
128
3.80%. M.p. 255–257 °C . IR (KBr disk): ν (cm-1) 1630 (C=O). 1H NMR: δ (ppm) 4.01 (2H, t,
129
2
JPH = 8.96 Hz, CH2 dppm); 5.13 (1H, d, 2JPH = 6.63 Hz, CH); 6.86- 8 (38H, m, Ph). 31P{1H}
130
NMR: δ (ppm) -29.01 (1P, m, PPh2 trans CH); -12.84 (1P, m, PPh2 cis CH); 23.02 (1P, m,
131
CHP).13C NMR: δ (ppm) 29.67 (br, CH2 dppe); 42.14 (br, CH); 125–138 (m, Ph); 195.77 (s,
132
CO).
133
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Complex 4b. Compound 4b was prepared following the same synthetic method as that
2.3.5. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(py)] (R=4-Me 5a, 4-Br 5b)
134 135
excess of pyridine (80 µL, 1 mmol) and the resulting yellow solution was stirred for 14h at
136
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Complex 5a. To a suspension of 2a (0.063 g, 0.06 mmol) in acetone (5ml) was added an
137
treated with cold n-hexane (15 ml) to give a green solid. Yield: 0.050 g. 65.0%. Anal. Calc.
138
for C32H27PdClNOP: C, 62.55; H, 4.43; N, 2.28%. Found: C, 62.20; H, 4.35; N, 2.18%. M.p.
139
215–217 °C (dec). IR (KBr disk): ν (cm-1) 1622, (C=O). 1H NMR: δ (ppm) 2.27 (s, Me,
140
AC C
EP
room temperature. After the reaction time, the solvent was concentrated and the residue
major); 2.31 (s, Me, minor); 5.04 (br, CH, major.); 5.15 (br, CH, minor.); 6.51–8.39 (23H, m,
141
Ph). 31P{1H} NMR: δ (ppm) 13.01 (1P, s, CHP, major.); 17.55 (s, CHP, minor.). 13C NMR: δ
142
(ppm) 20.03 (s, Me, minor); 21.41 (s, Me, major); 32.89 (d, 1JPC = 64.06 Hz, CH, minor);
143
34.33 (d, 1JPC = 60.19 Hz, CH, major); 123.99–152.54 (m, Ph); 196.23 (s, CO, minor);
144
198.55 (s, CO, major).
145
Complex 5b. Compound 5b was prepared following the same synthetic method as that
146
reported for 5a. Thus, to 2b (0.063 g, 0.06 mmol) in acetone (5ml) was added an excess of
147
6
ACCEPTED MANUSCRIPT pyridine (80 µL, 1 mmol) to give 5b as a green solid. Yield: 0.050 g. 58.8%. Anal. Calc. for
148
C30H22PdClBrNOP: C, 54.16; H, 3.33 Found: C, 53.93; H, 3.20. M.p. 200-202 °C . IR (KBr
149
disk): ν (cm-1) 1627 (C=O). 1H NMR: δ (ppm) 5.00 (br, CH, major); 5.2 (br, CH, minor.);
150
P{1H} NMR: δ (ppm) 19.28 (s, CHP, major.); 22.01 (s, CHP,
151
minor).13C NMR δ (ppm) 34.02 (d, CH, 1JPC = 60.34 Hz, minor); 36.21 (d, CH, 1JPC = 62.8
152
Hz, major); 126.05–150.44 (m, Ph); 195.65 (s, CO, minor); 197.02 (s, CO, major).
153
31
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7.22-8.75 (23H, m, Ph).
154
2.3.5. Synthesis of [Pd{CH{P(C6H4)Ph2}COC6H4-R}Cl(PPh3)] (R=4-Me 6a, 4-Br 6b)
SC
155 156
added solid PPh3 (0.03 g, 0.12 mmol). The mixture was stirred for 30 minutes. The resulting
157
colorless solution was concentrated (2 ml) and diethyl ether (30 ml) was added to precipitate
158
white solid. Yield: 0.08 g. 84%. Anal. Calc. for C45H37ClOP2Pd: C, 67.76; H, 4.67%. Found:
159
C, 67.91; H, 4.82%. M.p. 217–220 °C . IR (KBr disk): ν (cm-1) 1623 (C=O). 1H NMR: δ
160
(ppm) 2.32 (3H, s, Me); 5.45 (1H, dd, 2JPH = 8.78, 3JPH = 8.39 Hz, CH); 6.88- 8.34 (33H, m,
161
P{1H}: δ (ppm) 12.25 (PPh3) and 28.67 (CHP) (2d, 3JPP = 19.70 Hz).13C NMR: δ
162
(ppm) 21.92 (s, Me); 36.04 (d, 1JPC = 62.88 Hz, CH); 119.71–146.65 (m, Ph); 192.70 (s, CO).
163
Complex 6b. Compound 6b was prepared following the same synthetic method as that
164
reported for 6a. Thus, to 2b (0.063 g, 0.06 mmol) in CH2Cl2 (10 ml) was added solid PPh3
165
AC C
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Ph).
31
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Complex 6a. To a suspension of complex 2a (0.063 g, 0.06 mmol) in CH2Cl2 (10 ml) was
166
31
P{1H} NMR: δ (ppm) 12.03 (d, 3JPP = 17.76, PPh3), 29.02 (d, 3JPP =
169
C NMR: δ (ppm) 33.30 (d, CH, 1JPC = 61.78 Hz); 120.99–150.24 (m, Ph);
170
(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. M.p. 250-252 °C . IR (KBr
167
disk) ν (cm-1) 1629 (C=O). 1H NMR: δ (ppm) 4.92 (1H, dd, 2JPH = 7.05, 3JPH = 6.25 Hz, CH);
168
7.48-7.83 (20H, m, Ph). 19.09, CHP).
13
193.55 (s, CO).
171
2.4. Results and discussion:
172
7
ACCEPTED MANUSCRIPT 2.4.1. Synthesis
173 174
triphenylphosphine with 2-bromo-4'-methylacetophenone and 2,4'-dibromoacetophenone in
175
acetone and treatment with aqueous NaOH solution) for 3h (1:2 molar ratio) in CH3CN gave
176
the dimeric orthopalladated complexes 2a and 2b as green-yellow solid. The reactions of 2a
177
and 2b with bidentate diphosphine ligands dppe and dppm (1:2 molar ratio) in presence of
178
NaClO4?1H2O in CH2Cl2 led to the splitting of the chloride bridge and obtained the
179
mononuclear derivatives that dppe and dppm groups are bonded to the Pd atom giving five
180
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The reflux reactions of PdCl2 with ylides 1a and 1b (prepared by reacting
181
monodentate ligands py (excess of pyridine) in acetone and PPh3 (1:2 molar ratio) in CH2Cl2
182
gave mononuclear derivatives as cis and trans isomers for 5a and 5b and more stable isomer
183
of trans for 6a and 6b. These isomers have been characterized by 1H,
184
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and four membered P,P-chelate rings (3a, 3b, 4a and 4b). Also, the reactions 2a and 2b with
measurements.
31
P and
13
C NMR
185
Scheme 1 here
The IR, 1H- and
31
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2.4.2. Spectroscopy
186 187 188 189
are listed in Table1. The ν(CO) band, which is sensitive to complexation, occurs at 1599 and
190
1578 cm-1 in the parent ylides 1a and 1b, respectively [20, 21]. Coordination of ylide through
191
the carbon atom causes an increase in the ν(CO) band, whereas for O-coordination a lowering
192
of the ν(CO) band is expected [22]. The IR spectra of all complexes 2-6 (a and b) show a
193
strong absorption in the range of 1622-1632 cm-1, meaning that ylides are C-bonded to the
194
palladium center and C-coordination has occurred. These isomers appear in 1H and 31P{1H}
195
NMR.
196
AC C
EP
P-NMR data of ligands as well as the corresponding metal complexes
197
8
ACCEPTED MANUSCRIPT Table 1 here
198
199 200
spectroscopic characterization of them. For this reason, these complexes were reacted with
201
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The high insolubility of 2a and 2b in the usual organic solvents prevented a more detailed
202
adequately soluble in organic solvents. The 1H and 31P{1H} NMR signals for the PCH group
203
of all complexes are shifted downfield compared to those of the free ylides (1a and 1b), as a
204
SC
dppe, dppm, py and PPh3 to obtain the mononuclear derivatives (Scheme 1), which are
205
5a and 5b show duplicates signals that must arise from the presence of both possible isomers
206
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consequence of the inductive effect of the metal centre. The 1H NMR spectra of complexes
207
the methinic CH groups due to the coupling with ylidic phosphorus. The 1H NMR spectra of
208
4a, 6a and 6b are consistent with doublet of doublets and that of 4b is triplet and for 3a and
209
3b are broad signals that must arise from the simultaneously coupling with two or three
210
phosphorus centers [12, 23]. Furthermore, the values of the 2JPH coupling constants between
211
the methin proton and the phosphorus atom of the ylide ligands in these complexes are lower
212
than those of the free ylides, suggesting that sp2→sp3 rehybridization of the ylide carbon
213
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(cis and trans, see scheme 2) [23].These 1H NMR spectra of 5a and 5b show broad signals for
P{1H} NMR spectra of 3a, 3b,
214
4a and 4b show three different multiple signals, corresponding to the three P atoms of
215
31
AC C
occurs upon coordination to the palladium atom [24]. The
molecules, one due to ylide, which shows the presence of the endo-metalated ligand and the
216
other two to the bidentate diphosphine ligands dppe [25] and dppm [26]. The 31P{1H} NMR
217
spectra of the bidentate diphosphine have one signal, while those of Pd(II) complexes with a
218
bidentate diphosphine show two signals due to different trans effect of arylic and ylidic
219
carbons (see Table 1). It should be worth noting that in CDCl3 solution the coupling constant
220
between the phosphorus atoms of the chelate bidentate phosphine ligands and ylidic
221
phosphorus are observed in the
13
P{1H} NMR spectra of compounds 3a, 3b, 4a and 4b, 9
222
ACCEPTED MANUSCRIPT although this was not observed before [13]. The 31P{1H} NMR spectra of 5a and 5b are two
223
singlets due to cis and trans isomers and those of 6a and 6b show two doublets around 12 and
224
29 ppm due to PPh3 and ylidic phosphorus, respectively, [12, 23].
225
Scheme 2 here
226
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227
13
228
carbon. Such an upfield shift has been observed in PdCl(η3–2- XC3H4) (C6 H5)3PCHCOR (X
229
= H, CH3; R = CH3, C6H5) [24] and our synthesized complexes [12, 27]. The 13C shifts of the
230
CO group in the complexes are around 195 ppm, relative to 183 and 186 ppm noted for the
231
same carbon in the parent ylides, indicating much lower shielding of the carbon of the CO
232
group in these complexes [27].
233
2.4.3. Crystal structures analysis
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C-NMR spectra of these complexes show the upfield shift of the signals due to the ylidic
234 235
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The molecular structures of 3a and 4a were determined through X-ray diffraction methods.
236 237
Crystallographic data and parameters concerning data collection and structure solution and
238
refinement are summarized in Table 2 and selected bond distances and angles are presented
239
in Table 3. Complex 3a crystallizes on the monoclinic system, in the space group P1 21/c1.
240
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A molecular drawing of complexes 3a and 4a are shown in Figs. 1 and 2, respectively.
The Pd atom is located on a square-planar environment, surrounded by the methinic carbon
241
C(0BA), the metallated carbon C(16), and the two phosphor atoms P(21) and P(22) of the
242
chelating dppe ligand. Complex 4a crystallizes in the triclinic system, on the space group P-1.
243
The Pd atom is located on a square-planar environment, surrounded by the methinic carbon
244
C(15), the metallated carbon C(16), and the two phosphor atoms P(5) and P(3) of the
245
chelating dppm ligand. The sum of the bond angles around the palladium in 3a and 4a is
246
almost 360˚. Although the orthometallated ligand is remarkably warped (especially 4a), the
247
10
ACCEPTED MANUSCRIPT 248
[2.132(2) Å] 4a bond distances are statistically identical with those found in related
249
complexes like [Pd-(C6H4-2-pph2C(H)-COCH2PPh3)(PPh3)(NCMe)]2+ [2.161(8) Å] [28] and
250
[Pd(dmba)(OH2){CH(CONMe2)(PPh3)}]+ [2.113(6) Å] [ 29]. The Pd–C(16) [2.064(3) Å] 3a
251
and [2.059(2) Å] 4a bond distances are statistically identical with that found in
252
orthopalladated complex like [Pd{κ2-C,N-C6H4-1-[(3, 5-Me2-C3N2)-CH2-(η5-C5H4Fe(η5-
253
C5H5)]}Cl(PPh3)] [2.035(5) Å] [30]. The dppe and dppm groups are bonded to the Pd atom
254
giving five and four membered P,P-chelate rings. The distances Pd(1A)–P(22) [2.2914(7) Å]
255
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environment around the Pd is planar. The Pd(1A)–C(0BA) [2.191(3) Å] 3a and Pd–C(15)
256
4a are quite different, reflecting the different trans effect of the carbon atom and the arylic
257
carbon [31]. The mutual trans positions of carbon and phosphorus ligands in palladium(II)
258
complexes 3a and 4a lead to a weakening of both Pd-Caryl and Pd-P bonds (see Table 3) that
259
is called transphobia effect [32 , 33] due to π-acceptor ability of phosphorus atom but this is
260
not exist on complexes with σ-donor N atoms in ligands such as bipyridine (Pd-Caryl [
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and Pd(1A)–P(21) [2.3513(7) Å] 3a and Pd–P(3) [2.2995(6) Å] and Pd–P(5) [2.3640(6) Å]
262
[2.137(3) Å]) [13]. The P(7)-C(0BA) [1.767(3) Å] 3a and P(2)-C(15) [1.761(2) Å] 4a bond
263
distances are significantly longer than that observed in the similar ylide 1.706 Å [34]. The
264
effect of the coordination and subsequent loss of conjugation is more evident on the CCO
265
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2.017(5) Å] and Pd-N [2.132(4) Å]) and phenanthroline (Pd-Caryl [1.991(3) Å] and Pd-N
fragment. The C(0BA)-C(13) [1.466(4) Å] 3a and the C(15)-C(51) [1.477(3) Å] 4a bond
266
distances are longer than that found in the uncomplexed phosphorane (1.407(8) Å) [35],
267
meaning that this bond has been relaxed, while the C(13)-O(19) [1.230(3) Å] 3a and C(51)-O
268
[1.233(3) Å] 4a bond distances are shorter than that observed in the similar ligand [1.256(2)
269
Å] [35]. Then, the C-bonding of the ligand fixes the density charge at the C atom and breaks
270
the conjugation.
271 272
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273
Table 3 here
274
Fig. 1 here
275
Fig. 2 here
276 277
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Conclusions
278
at the phenyl rings of the PPh3 group and gives five-membered endo metallacycles of high
279
stability. The reaction of the dinuclear complexes with NaClO4.1H2O and neutral bidentate
280
ligands dppe and dppm and monodentate ligands py and PPh3 promotes the synthesis of new
281
mononuclear complexes, in which the five-membered Pd-C-P-C-C metallacycle remains
282
stable. Also the reaction of these complexes with py leads to complexes with two isomers (cis
283
and trans) whereas PPh3 lead to more stable isomer trans.
284
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The palladation of stabilized phosphoylides Ph3P=CHC(O)C6H4R occurs regioselectively
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Acknowledgements
285
We are grateful to the Bu-Ali Sina University for a grant and Mr. Zebarjadian for recording the NMR spectra.
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289
Appendix A. Supplementary material
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CCDC 806209 and 806210 contain the supplementary crystallographic data for the
291
complexes 3a and 4a, respectively. These data can be obtained free of charge from the
292
Cambridge Crystallographic Data Center via http://www.ccdc.cam.ac.uk/data_request/cif.
293
294
295 296
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[2] D.A. Colby, R.G. Bergman, J.A. Ellman, Chem. Rev. 110 (2010), 624-655.
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[3] C. Copéret, Chem. Rev. 110 (2010) 656-680.
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[4] M.P. Doyle, R. Duffy, M. Ratnikov, L. Zhou, Chem. Rev. 110 (2010) 704-724.
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[5] C.-M. Che, V. Kar-Yan Lo, C.-Y Zhou and J.-S Huang, Chem. Soc. Rev. 40 (2011)
302
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References:
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[6] W.R. Gutekunst, P.S. Baran, Chem. Soc. Rev. 40 (2011) 1976–1991.
SC
304 305
[8] A.S. Tsai, R.G. Bergman, J.A. Ellman, J. Am. Chem. Soc. 130 (2008) 6316–6317.
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[9] R. Giri, B.-F. Shi, K.M. Engle, N. Maugel, J.-Q. Yu, Chem. Soc. Rev. 38 (2009) 3242–
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[10] T.W. Lyons and M.S. Sanford, Chem. Rev. 110 (2010) 1147–1169.
[12] S.J. Sabounchei , H. Nemattalab, F. Akhlaghi, H.R. Khavasi, Polyhedron 27 (2008)
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3275-3279.
312 313
[14] E.P. Urriolabeitia, Dalton Trans. (2008) 5673-5686.
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[13] K. Karami, C. Rizzoli, F. Borzooie, Polyhedron 30 (2011) 778-784.
[15] E. Serrano, C. Vallés, J.J. Carbó, A. Lledós, T. Soler, R. Navarro, E.P. Urriolabeitia, Organometallics 25 (2006) 4653-4664.
315 316
[16] K. Muñiz, Transition Metal Catalyzed Electrophilic Halogenation of C-H bonds in
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alpha-Position to Carbonyl Groups (Topics in Organometallic Chemistry), 1st Edition,
318
Springer, 2010.
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[17] D. Aguilar, M.A. Aragüés, R. Bielsa, E. Serrano, R. Navarro, E.P. Urriolabeitia, Organometallics 26 (2007) 3541-3551.
320 321
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ACCEPTED MANUSCRIPT [18] G.M. Sheldrick. SHELXS 97, Program for the Solution of Crystal Structures, University of Göttingen, Germany (1997).
322 323
[19] G.M. Sheldrick. SHELXL 97, Program for the Refinement of Crystal Structures, University of Göttingen, Germany (1997).
324 325 326
1102-1106.
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[20] N.A. Nesmeyanov, E.V. Binshtok, O.A. Reutov, Dokl. Akad. Nauk SSSR 198 (1971)
328
[22] J.A. Albanese, D.L. Staley, A.L. Rheingold, J.L. Burmeister, Inorg. Chem. 29 (1990)
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[21] S.J. Sabounchei, A.R. Dadrass, Asian J. Chem. 19 (2007) 5471-5476.
2209-2213.
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[23] J. Vicente, M.T. Chicote, J. Fernandez-Baeza, J. Organomet. Chem. 364 (1989) 407414.
332
[24] G. Facchin, R. Bertani, M. Calligaris, G. Nardin, M. Mari, J. Chem. Soc., Dalton Trans. (1987) 1381-1387.
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[25] C. Cativiela, L.R. Falvello, J.C. Ginés, R. Navarro, E.P. Urriolabeitia, New J. Chem. 25
335 336 337
[27] S.J. Sabounchei, H. Nemattalab, S. Salehzadeh, S. Khani, M. Bayat, H.R. Khavasi,
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Polyhedron 27 (2008) 2015-2021.
339 340
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[26] P.E. Garrou, Chem. Rev. 85 (1985) 171-185.
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(2001) 344-352.
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[28] L.R. Falvello, S. Fernández, R. Navarro, A. Rueda, E.P. Urriolabeitia, Organometallics 17 (1998) 5887-5900.
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[29] I.C. Barco, L.R. Falvello, S. Fernández, R. Navarro, E.P. Urriolabeitia, J. Chem. Soc. Dalton Trans. (1998) 1699-1706.
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[30] A. González, C. López, X. Solans, M. Font-Bardía, E. Molins, J. Organomet. Chem. 693 (2008) 2119-2131.
344 345
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ACCEPTED MANUSCRIPT [31] D. Aguilar, M. Angel Aragüés, R. Bielsa, E. Serrano, T. Soler, R. Navarro, E. P. Urriolabeitia, J. Organomet. Chem. 693 (2008) 417-424.
346 347
[32] J. Vicente, J.A. Abad, A.D. Frankland, M.C. Ramírez de Arellano, Chem. Eur. J. 5 (1999) 3066-3075.
348 349 350
[34] R. Usón, J. Forniés, R. Navarro, P. Espinet, C. Mendívil, J. Organomet. Chem. 290
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[33] J. Vicente, A. Arcas, D. Bautista, Organometallics 16 (1997) 2127-2138.
(1985) 125-131.
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[35] S.J. Sabounchei, A.R. Dadras, M. Jafarzadeh, H.R. Khavasi, Acta Cryst. E63 (2007)
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3160.
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Research highlight
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The palladation of α-keto stabilized phosphoylides occurs regioselectively at the PPh3 group.
This orthopalladation gives five-membered endo metallacycles of high stability.
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The dppe group behaves as an P,P-chelate ligand and is bonded to the Pd giving a five membered ring.
a four membered ring.
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The dppm group behaves as an P,P-chelate ligand and is bonded to the Pd giving
The reaction of the dinuclear complexes with Py lead to complexes with two
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isomers (cis and trans).
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Tables
δ(CH)
δ(P)
1a
1599
4.36
12.98
1b
1578
4.39
14.17
2a
1622
-
-
2b
1623
-
-
3a
1622
4.88
21.46/40.90/50.36
3b
1632
4.9
25.12/44.30/56.67
4a
1630
5.13
4b
1630
4.01
5a
1622
5.04/5.15
5b
1627
5.00/5.20
6a
1623
5.45
6b
1629
4.92
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ν(CO)
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Compound
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Table 1- IR and NMR data for phosphorus ylides 1a, 1b and related complexes
19.33/-20.30/-34.36 23.02/-12.84/-29.01 13.01/17.55
19.28/22.01
28.67/12.25
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29.03/12.03
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Values for 31P chemical shifts of the free ligands dppe, dppm and PPh3 are: -15.00, -24.88, -9.96., respectively.
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Table 2. Crystal Data and Structure Refinement for Compounds 3a and 4a
3a
4a
C54 H47 Cl4 O5 P3 Pd
C52 H44 Cl O5 P3 Pd
Formula weight
1117.03
983.63
Temperature (K)
120.(1)
120(1)
Wavelength (Å)
0.7107
0.71073
Crystal system
monoclinic
triclinic
space group
P1 21/c 1
P-1
a (Å)
20.7104(6)
11.7852(6)
b (Å)
11.8844(3)
c (Å)
22.4652(7)
α (°)
90.00
β (°)
116.478(4)
77.456(4)
90.00
65.314(5)
3
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16.5537(7)
70.866(4)
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γ (°)
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empirical formula
Volume (Å )
4949.4(2)
2203.01(19)
Z
4
2
3
Dcalc (Mg/m )
1.499 _1
Absorption coefficient (mm )
0.737
F(000)
2280 3
θ Range for data collection Limiting indices
1008
0.3293× 0.2278× 0.0591
0.4378× 0.2091× 0.0603
2.48- 26.37
3.20 - 26.37
-25 ≤ h ≤ 25
-11≤ h ≤ 14
-14 ≤ k ≤ 14
-12 ≤ k ≤ 16
-27 ≤ l ≤ 28
-20 ≤ l ≤ 20
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Reflections collected/unique
0.641
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cryst size (mm )
1.483
Maximum and minorimum transmission
43051/10082 [R(int) = 0.0289] 0.957 and 0.846
14278 /8946 [R(int) = 0.0223] 1.00 and 0.97405
Refinement method
Full-matrix least-squares on F
Full-matrix least-squares on F2
Absorption correction
analytical
multi-scan
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Data/restraints/parameters
10082/15/624
8946/0/560
goodness-of-fit on F2
1.027
1.048
Final R indices [I > 2σ(I)]
R1= 0.0347, wR2= 0.0969
R1= 0.0318 , wR2= 0.0735
R1= 0.0426, wR2= 0.0919
R1= 0.0389 , wR2= 0.0689
1.092 and -1.032
0.763 and -0.439
R indices (all data)
-3
largest diff. peak, hole (eâÅ )
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Table 3. Selected bond lengths (Å) and bond angles (0) for 3a and4a. Bond distances 3a
4a 2.064(3)
Pd-C16
Pd1A-C0BA
2.191(3)
Pd-C15
2.132(2)
Pd1A-P22
2.2914(7)
Pd-P3
2.2995(6)
Pd1A-P21
2.3513(7)
Pd-P5
2.3640(6)
P7-C10
1.780(3)
P2-C15
1.761(2)
P7-C0BA
1.767(3)
P2-C60
P7-C8
1.797(3)
Pd-C46
P7-C5
1.806(3)
C0BA-C13
1.466(4)
C13-O19
1.230(3)
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1.808
P2-C0AA
1.801(2)
C15-C5
1.477(3)
C51-O
1.233(3)
P21-Pd1A-C0BA
95.81(7)
P3-Pd- C16
101.48(7)
P21-Pd1A-P22
84.73(2)
P3-Pd-P5
71.17(2)
C0BA-Pd1A-C16
85.20(10)
P5-Pd- C15
104.07(6)
C16-Pd1A-P22
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Bond angles
2.059(2)
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Pd1A-C16
93.81(8)
C15-Pd-C16
83.36(9)
176.42(8)
C16- Pd- P5
172.22(6)
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C16- Pd1A- P21 C0BA- Pd1A- P22
172.44(7)
C15- Pd- P3
174.90(6)
Pd1A-C16-C10
115.17(19)
Pd-C15-P2
99.94(10)
Pd1A-C0BA-P7
97.57(12)
Pd-C16-C60
117.13(16)
Pd1A-P22-C32
106.89
Pd-P5-C11
91.39(7)
Pd1A-P21-C30
104.64(9)
Pd-P3-C11
93.50(7)
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Captions of Schemes and Figures Scheme 1. Synthesis and reactivity of orthopalladate phenacyl phosphorus ylides Scheme 2. Possible isomers of complexes 5a and 6a
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Fig. 1. Thermal ellipsoid plot of 3a (50% probability level) showing the numbering scheme. H atoms are omitted for clarity.
Fig. 2. Thermal ellipsoid plot of 4a (50% probability level) showing the numbering scheme.
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H atoms are omitted for clarity.
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O Ph3P
C H
C R
(i)
O Ph2 P C CH
1/2
R
Pd Cl R= Me (2a), Br (2b)
R
Pd
ClO4
PPh2
O
Ph2 P C CH
R ClO4
Pd PPh2
O Ph2 P C CH
(iv)
R
Pd Ph3P
Cl
R= Me (6a), Br (6b)
O Ph2 P C CH
R
Pd
py
Cl
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R= Me (4a), Br (4b)
(v) (iii)
R= Me (3a), Br (3b)
Ph2P
(ii)
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Ph2 P C CH
Ph2P
2
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R= Me (1a), Br (1b)
R= Me (5a), Br (5b)
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Scheme 1. (i) PdCl2/CH3CN/∆; (ii) dppe/CH2Cl2/NaClO4?H2O; (iii) dppm/CH2Cl2/NaClO4?H2O; (iv) py/CH3COCH3; (v) pph3/CH2Cl2
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O Ph2 P C CH Pd Cl N
R
R= Me (5a), Br (6a)
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Scheme 2
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Cl
O Ph2 P C CH Pd N
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Fig.1
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Fig. 2