Synthesis and structure of mono- and di-nuclear

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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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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

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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:

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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

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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.

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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

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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);

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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

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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,

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60.58; H, 4.14%. Found: C, 60.73; H, 4.22%. M.p. 273–275 °C . IR (KBr disk): ν (cm-1) 1622

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(C=O).

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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

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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

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(0.056 g, 0.14 mmol) and NaClO4?1H2O, 0.21 mmol was added, resulting in the immediate

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precipitation of NaCl. This suspension was stirred for 35 minutes at room temperature and

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then filtered over Celite. The clear solution was concentrated (2 ml) and diethyl ether (25 ml)

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was added to precipitate the white solid 3a. Yield: 0.062 g. 63.3%. Anal. Calc. for

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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);

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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,

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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

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(br, 2CH2 dppe); 41.69 (br, CH); 126.26–136.60 (m, Ph); 195.01 (s, CO).

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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

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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

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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

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ether (30 ml) was added to precipitate 4a as a white solid. Yield: 0.163g. 69.2%. Anal. Calc.

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for C52H44PdClO5P3: C, 63.49; H, 4.51%. Found: C, 63.20; H, 4.41%. M.p. 219–221 °C . IR

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(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

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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

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(0.061 g, 0.16 mmol) and NaClO4?1H2O, 0.24 mmol to give 4b as a white solid. Yield:

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0.097g. 58.4%. Anal. Calc. for C51H41PdClO5P3Br: C, 58.42; H, 3.94%. Found: C, 58.24; H,

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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,

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CHP).13C NMR: δ (ppm) 29.67 (br, CH2 dppe); 42.14 (br, CH); 125–138 (m, Ph); 195.77 (s,

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CO).

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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

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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.

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for C32H27PdClNOP: C, 62.55; H, 4.43; N, 2.28%. Found: C, 62.20; H, 4.35; N, 2.18%. M.p.

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215–217 °C (dec). IR (KBr disk): ν (cm-1) 1622, (C=O). 1H NMR: δ (ppm) 2.27 (s, Me,

140

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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,

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Ph). 31P{1H} NMR: δ (ppm) 13.01 (1P, s, CHP, major.); 17.55 (s, CHP, minor.). 13C NMR: δ

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(ppm) 20.03 (s, Me, minor); 21.41 (s, Me, major); 32.89 (d, 1JPC = 64.06 Hz, CH, minor);

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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).

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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.);

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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

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7.22-8.75 (23H, m, Ph).

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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

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colorless solution was concentrated (2 ml) and diethyl ether (30 ml) was added to precipitate

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white solid. Yield: 0.08 g. 84%. Anal. Calc. for C45H37ClOP2Pd: C, 67.76; H, 4.67%. Found:

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C, 67.91; H, 4.82%. M.p. 217–220 °C . IR (KBr disk): ν (cm-1) 1623 (C=O). 1H NMR: δ

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(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

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(ppm) 21.92 (s, Me); 36.04 (d, 1JPC = 62.88 Hz, CH); 119.71–146.65 (m, Ph); 192.70 (s, CO).

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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

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Ph).

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Complex 6a. To a suspension of complex 2a (0.063 g, 0.06 mmol) in CH2Cl2 (10 ml) was

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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,

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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

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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

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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

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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 [

261

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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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ACCEPTED MANUSCRIPT Table 2 here

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

286

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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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288

289

Appendix A. Supplementary material

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290

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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[1] J. Le Bras, J. Muzart, Chem. Rev. 111 (2011) 1170–1214.

298

[2] D.A. Colby, R.G. Bergman, J.A. Ellman, Chem. Rev. 110 (2010), 624-655.

299

[3] C. Copéret, Chem. Rev. 110 (2010) 656-680.

300

[4] M.P. Doyle, R. Duffy, M. Ratnikov, L. Zhou, Chem. Rev. 110 (2010) 704-724.

301

[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:

1950–1975.

303

[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.

306

[9] R. Giri, B.-F. Shi, K.M. Engle, N. Maugel, J.-Q. Yu, Chem. Soc. Rev. 38 (2009) 3242–

307

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[7] H. Davies, J. Du Bois, J.-Q. Yu, Chem. Soc. Rev. 40 (2011) 1855–1856.

3272.

308 309

[11] H.-Q. Do, O. Daugulis, J. Am. Chem. Soc. 130 (2008) 1128-1129.

310

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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)

311

3275-3279.

312 313

[14] E.P. Urriolabeitia, Dalton Trans. (2008) 5673-5686.

314

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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

317

alpha-Position to Carbonyl Groups (Topics in Organometallic Chemistry), 1st Edition,

318

Springer, 2010.

319

[17] D. Aguilar, M.A. Aragüés, R. Bielsa, E. Serrano, R. Navarro, E.P. Urriolabeitia, Organometallics 26 (2007) 3541-3551.

320 321

13

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.

327

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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)

329

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[21] S.J. Sabounchei, A.R. Dadrass, Asian J. Chem. 19 (2007) 5471-5476.

2209-2213.

330

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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.

333 334

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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,

338

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.

331

[28] L.R. Falvello, S. Fernández, R. Navarro, A. Rueda, E.P. Urriolabeitia, Organometallics 17 (1998) 5887-5900.

341

[29] I.C. Barco, L.R. Falvello, S. Fernández, R. Navarro, E.P. Urriolabeitia, J. Chem. Soc. Dalton Trans. (1998) 1699-1706.

342 343

[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.

352

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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)

SC 1.782(2)

M AN U

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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O

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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

R

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Cl

O Ph2 P C CH Pd N

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Fig.1

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Fig. 2