Cyclopalladated azido complexes containing C,N-donor (HC～N = 2-(2′-thienyl)pyridine, azobenzene, 3,3′-dimethyl azobenzene, N,N′-dimethylbenzylamine, 2-phenylpyridine) ligands: Reactivity towards organic unsaturated compounds and catalytic properties

Article abstract of DOI:10.1039/b907324h

Cyclopalladated azido dimers having various C,N-donor ligands, [Pd(μ-N₃)(C,N-Lⁿ)]₂ (L¹H = 2-(2′-thienyl)pyridine; L²H = azobenzene; L³H = 3,3′-dimethylazobenzene; L⁴H = N,N′-dimethylbenzylamine; L⁵H = 2-phenylpyridine), underwent cleavage with tertiary (or chelating) phosphines to form the cyclopalladated [Pd(N₃)(PR ₃)(C,N-L)], the σ-bonded [Pd(N₃)(PR ₃)₂(C-L)], or the dinuclear-cyclopalladated [PdN ₃(PR₃)(C,N-L)]₂(μ-P～P) complexes. In particular, treating [Pd(μ-N₃)(C,N-L)]₂ with the basic chelating phosphine (depe or dmpe) produced the homoleptic bis(chelating) complex [Pd(C,N-Lⁿ)₂] (n = 1-3). Complex [Pd(N ₃)(PR₃)(C,N-L⁴)] or [Pd(N₃)(PR ₃)₂(C-L⁴)] reacted with aryl isocyanides to selectively give the imidoyl [Pd(N₃)(-CN-Ar)(PR₃)(N-L ⁴)] or the imidoyl carbodiimido complex [Pd(NCN-Ar)(-CN-Ar)(PR ₃)(N-L⁴)], which was formed by the CN-Ar insertion into the orthometallated Pd-C bond on the phenyl moiety or the interaction into the Pd-N₃ bond of the supporting ligand. In addition, reactions of [Pd(N₃)(PR₃)₂(C-Lⁿ)] (n = 1, 2, 4) with R-NCS {R = i-Pr, C₆H₄-NCS, (CH₃) ₃Si} gave the S-coordinated tetrazole-thiolato Pd(ii) complexes. Finally, the catalytic activity of the cyclopalladated azido complexes was evaluated. The Royal Society of Chemistry 2009.

Full text of DOI:10.1039/b907324h

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PAPER
www.rsc.org/dalton | Dalton Transactions
Cyclopalladated azido complexes containing C,N-donor (HC~N =
2-(2¢-thienyl)pyridine, azobenzene, 3,3¢-dimethyl azobenzene,
N,N¢-dimethylbenzylamine, 2-phenylpyridine) ligands: reactivity towards
organic unsaturated compounds and catalytic properties†
Kyung-Eun Lee,a,b Hyeong-Tak Jeon,a Sam-Yong Han,a Jungyeob Ham,c Yong-Joo Kim*a and Soon W. Leeb
Received 14th April 2009, Accepted 4th June 2009
First published as an Advance Article on the web 8th July 2009
DOI: 10.1039/b907324h
Cyclopalladated azido dimers having various C,N-donor ligands, [Pd(m-N3)(C,N-Ln)]2 (L1H =
2-(2¢-thienyl)pyridine; L2H = azobenzene; L3H = 3,3¢-dimethylazobenzene; L4H = N,N¢-dimethyl-
benzylamine; L5H = 2-phenylpyridine), underwent cleavage with tertiary (or chelating) phosphines to
form the cyclopalladated [Pd(N3)(PR3)(C,N-L)], the s-bonded [Pd(N3)(PR3)2(C-L)], or the dinuclear-
cyclopalladated [PdN3(PR3)(C,N-L)]2(m-P~P) complexes. In particular, treating [Pd(m-N3)(C,N-L)]2
with the basic chelating phosphine (depe or dmpe) produced the homoleptic bis(chelating) complex
[Pd(C,N-Ln)2] (n = 1–3). Complex [Pd(N3)(PR3)(C,N-L4)] or [Pd(N3)(PR3)2(C-L4)] reacted with aryl
4
=
isocyanides to selectively give the imidoyl [Pd(N3)(–C N–Ar)(PR3)(N-L )] or the imidoyl carbodiimido
4
= =
=
complex [Pd(N C N–Ar)(–C N–Ar)(PR3)(N-L )], which was formed by the CN–Ar insertion into
the orthometallated Pd–C bond on the phenyl moiety or the interaction into the Pd–N3 bond of the
supporting ligand. In addition, reactions of [Pd(N3)(PR3)2(C-Ln)] (n = 1, 2, 4) with R–NCS {R = i-Pr,
C6H4–NCS, (CH3)3Si} gave the S-coordinated tetrazole–thiolato Pd(II) complexes. Finally, the catalytic
activity of the cyclopalladated azido complexes was evaluated.
or isothiocyanates gave novel organometallic compounds.16 As an
Introduction
extension of this work, we prepared and investigated the mono-
and dinuclear cyclopalladated azido complexes containing a series
of C,N-donor ligands [Pd(N3)(PR3)(C,N-Ln)], [Pd(N3)(PR3)2(C-
Ln)], and [Pd(N3)(C,N-Ln)]2(m-P~P) (n = 1–5 in Chart 1). Here, we
describe the preparation of the novel cyclopalladated Pd–azido
complexes and their reactivity towards phosphines (Scheme 1).
We also report the selective insertion of small molecules such as
organic isocyanides into the Pd–C bond in these complexes, along
with their catalytic activity for C–C coupling reactions.
Cyclometallated Pd(II) complexes possessing the C~N chelating
ligands have gained much attention because they catalyze various
organic reactions and act as key intermediates in organic and
organometallic syntheses.1–7 However, only a few cases of these
type of Pd(II) complexes containing pseudo-halogen ligands
such as an azido group have been studied for their biological
activity or thermal behavior.8,9 The azido ligand in transition-
metal complexes is known to react with organic unsaturated
compounds to give heterocycles by dipolar cycloaddition or
nitrene compounds by thermal or photoirradation.10 In particular,
the C,N-ligand in cyclopalladated complexes is shown to be
labile towards tertiary (or chelating) phosphines.11–15 In this
context, the azido group introduction into the cyclometallated
system, that is, the combination of both ligands (the azido ligand
and C,N-ligand), may induce a novel reactivity. Moreover, the
catalytic properties of these azido complexes have not yet been
explored.
Recently, we observed that reactions of the cyclometallated
Pd(II)–azido complexes containing phenyl (or thienyl) pyridyl
derivatives as the C,N-donor ligands with organic isocyanides
Chart 1
Results and discussion
aDepartment of Chemistry, Kangnung National University, Gangneung
210-702, Korea. E-mail: yjkim@kangnung.ac.kr; Fax: +82-33-647-1183;
Tel: +82-33-640-2308
Preparation of the cyclometallated Pd(II)–azido complexes
possessing C,N-donors
bDepartment of Chemistry, Sungkyunkwan University, Natural Science
Campus, Suwon 440-746, Korea
The cyclopalladated azido dimer [Pd(m-N3)(C,N-Ln)]2 in Scheme 2
could be prepared from [Pd(m-Cl)(C,N-Ln)]2 and NaN3 in
DMSO/excess H2O. The subsequent addition of the corre-
sponding phosphine readily converted these complexes into
cKorea Institute of Science and Technology, 290 Daejeon-dong, Gangneung
210-340, Korea
† CCDC reference numbers 713100 and 727728. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/b907324h
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Scheme 1
the desired azido or novel complexes (Schemes 3–7). Con-
sistent with the expectation based on stoichiometry, the cy-
clopalladated [Pd(N3)(PR3)(C,N-L)] (Path A), the C-coordinated
[Pd(N3)(PR3)2(C-L)] (Path B), and the dinuclear [Pd(N3)(C,N-
L)]2(m-P~P) (Path C) azides were formed when the dimer was
treated with the stoichiometric amount of monodentate or
chelating phosphines (Scheme 3). Formation of the products was
monitored by examining the characteristic N3 stretching band at
2028–2060 cm-1.
Scheme 4
Scheme 2
Scheme 5
Scheme 3
Although several cleavage reactions of the Cl-bridged cy-
clopalladated complexes by phosphines to give neutral or ionic
complexes are known,11–15 only one example associated with the
N3-bridged cyclopalladated complexes is known to date.8
The products were characterized by spectroscopic and analytical
data, and their colors, yields, and analytical data are listed in
Table 1. Complexes 1, 3, 7, 12, 21, and 24 were structurally
Scheme 6
characterized by X-ray diffraction (for compounds 1, 3, 7, and
12 see Fig. 1–4). Schemes 4–7 illustrate specific examples of
the cleavage of the cyclopalladated azido dimers by chelating
phosphines (Path C in Scheme 3).
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Table 1 Color, yields, and analytical data for the isolated complexes
Analysesb
C (%)
Complexa
Color
Yield (%)
49
H (%)
N (%)
1 [Pd(N3)(PMe3)(C,N-L1)]
2 [Pd(N3)(PMe3)(C,N-L4)]
3 [Pd(N3)(PEt3)(C,N-L4)]
4 [Pd(N3)(PMe2Ph)(C,N-L4)]
5 [Pd(N3)(PCy3)(C,N-L4)]
6 [Pd(N3)(PMe3)2(C-L1)]
7 [Pd(N3)(PMe3)2(C-L2)]
8 [Pd(N3)(PEt3)2(C-L2)]
9 [Pd(N3)(P(n-Pr)3)2(C-L2)]
10 [Pd(N3)(PMe3)2(C-L4)]
11 [Pd(N3)(C,N-L1)]2(m-dppf)
12 [Pd(N3)(C,N-L1)]2(m-dppp)
13 [Pd(N3)(C,N-L1)]2(m-dppb)
14 [Pd(N3)(C,N-L1)]2(m-depe)
15 [Pd(Cl)L1]2(m-dmpe)
Yellow
White
White
White
Yellow
White
Purple
Purple
Orange
White
Brown
Yellow
Yellow
Yellow
Yellow
Purple
Orange
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
White
Orange
White
37.28
(37.46)
39.89
(40.18)
50.21
(50.61)
48.43
(48.52)
57.52
(57.59)
38.91
(39.10)
44.96
(44.87)
51.16
(50.93)
55.96
(55.42)
41.26
(41.44)
52.86
(53.30)
51.87
(52.49)
52.72
(52.93)
40.86
(40.83)
38.64
(38.21)
63.79
(64.06)
57.17
(57.52)
43.87
(43.59)
55.12
(55.28)
47.35
(47.36)
55.30
(54.99)
64.74
(64.71)
61.04
(60.76)
40.58
(40.61)
56.17
3.85
(3.93)
6.01
(5.90)
2.85
(2.92)
5.84
(5.51)
8.44
(8.06)
5.57
(5.25)
6.02
(5.85)
7.48
(6.95)
8.27
(7.91)
7.24
(6.95)
3.78
(3.44)
3.69
(3.72)
3.87
(3.86)
4.43
(4.41)
3.78
(3.74)
4.88
(4.99)
4.43
(4.27)
6.28
(6.27)
5.03
(5.15)
4.92
(4.97)
7.63
(7.02)
8.33
(7.86)
7.05
(6.63)
5.82
(5.56)
8.08
14.43
(14.56)
15.63
(15.62)
18.31
(18.44)
13.21
(13.31)
9.71
(9.95)
11.80
(12.16)
14.17
(14.54)
12.67
(12.37)
11.07
(10.77)
13.52
(12.89)
9.11
(9.56)
10.60
(10.88)
10.34
(10.74)
13.26
(13.61)
3.63
(3.71)
10.52
(10.67)
12.72
(12.90)
14.35
(14.52)
11.17
(11.46)
13.67
(13.81)
12.79
(12.83)
8.05
80
45
74
96
63
82
89
86
94
94
74
96
60
37
20 [Pd(C,N-L3)2]
75
21 [Pd(N3)(C,N-L2)]2(m-dppb)
22 [Pd(N3)(C,N-L4)]2(m-depe)
23 [Pd(N3)(C,N-L4)]2(m-dppp)
93
86
51
24 [Pd(N3)(C,N-L5)]2(m-depe)
56
4
=
25 [Pd(N3)(–C( N–R))(N-L )(PMe3)]
68
(R = C6H3-2,6-i-Pr2)
4
=
=
=
26 [Pd(N
C
N–R)(–C( N–R))(N-L )(PMe3)]
46
(R = C6H3-2,6-i-Pr2)
(7.94)
9.60
(9.45)
12.33
(12.46)
6.16
(6.31)
12.86
(13.19)
4
=
=
=
27 [Pd(N
C
N–R)(–C( N–R))(N-L )(PMe3)]
73
(R = C6H3-2,6-Me2)
28 {Pd(S[CN4(R)])(C-L1)(PMe3)2}
53
(R = i-Pr)
29 [Pd(NCS)(P(n-Pr)3)2(C-L2)]
87
(55.89)
43.43
(42.98)
(7.72)
6.45
(6.08)
30 {Pd(PMe3)2(S[CN4]–)(C-L4)}2(m-C6H4)
47
a HL1 = 2-(2¢-thienyl)pyridine; HL2 = azobenzene; HL3 = 3,3¢-dimethylazobenzene; HL4 = N,N¢-dimethylbenzylamine; HL5 = 2-phenylpyridine.
b Calculated values are given in parentheses. Abbreviations: dppf = 1,2-bis(diphenyl)ferrocene; dppp = 1,3-bis(diphenylphosphino)propane; dppb =
1,4-bis(diphenylphosphino)butane; depe = 1,2-bis(diethylphosphino)ethane; dmpe = 1,2-bis(dimethylphosphino)methane.
As shown in Scheme 4, bulky bis(phosphine) reagents [dppf =
1,1¢-bis(diphenylphosphino)ferrocene; dppp = 1,3-bis(diphenyl-
phosphino)propane; dppb = 1,4-bis(diphenylphosphino)butane]
stoichiometrically cleave the N3-bridged cyclopalladated dimer
having the 2-thienylpyridine group to give the (chelating
phosphine)-bridged dinulear Pd azides [Pd(N3)(C,N-L1)]2(m-P~P)
(11–13) in high yields.
Interestingly, reactions of [Pd(m-X)(C,N-L1)]2 (X = N3 or
Cl) with an equimolar amount of depe or dmpe, more basic
bis(phosphine) reagents, produce a mixture of the dinuclear
compound [Pd(X)(C,N-L1)]2(m-P~P) (X = N3, depe (14); Cl,
dmpe (15); Cl, depe, (16)) as a major product, the homoleptic
bis(chelated) compound [Pd(C,N-L1)2] (17) as a minor prod-
uct, and the bis(phosphine) dihalide compound [(P~P)PdX2]
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Scheme 7
◦
˚
Fig. 2 ORTEP drawing of 3. Selected bond lengths (A) and angles ( ):
Pd1–C1 2.028(3), Pd1–N2 2.124(3), Pd1–N1 2.153(3), Pd1–P1 2.258(1),
N2–N3 1.189(5), N3–N4 1.148(5); C1–Pd1–N2 170.5(1), C1–Pd1–N1
81.9(1), N2–Pd1–N1 91.7(1), C1–Pd1–P1 95.0(1), N2–Pd1–P1 91.4(1),
N3–N2–Pd1 130.4(3), N4–N3–N2 176.4(5).
◦
Fig. 1 ORTEP drawing42 of 1. Selected bond lengths (A) and angles ( ):
Pd1–C7 2.002(2), Pd1–N2 2.094(2), Pd1–N1 2.116(1), Pd1–P1 2.2350(4),
N2–N3 1.175(2), N3–N4 1.143(2); C7–Pd1–N2 170.55(7), C7–Pd1–N1
81.22(6), N2–Pd1–N1 89.45(6), N1–Pd1–P1 172.92(4), N3–N2–Pd1
127.6(1), N4–N3–N2 175.8(2).
˚
(Scheme 5). The molecular structure of compound 17 was
determined by X-ray diffraction (Fig. 5). In contrast, similar
treatments with two equivalents of phosphine give the ionic
complex [Pd(C,N-L1)(P~P)](N3) (18), in which the azido group
acts as a counterion. In these reactions, compared with the Cl-
bridged cyclopalladated complexes, the N3-bridged analogs are
cleaved to the bis(chelated) compounds in lower yields. It is
worth noting that the bulkier chelating phosphines (that is, dppf,
dppp, and dppb) cleave the dimer [Pd(m-X)(C,N-L)]2 to give the
(chelating phosphine)-bridged dinulear Pd compounds (Schemes 4
and 6), rather than the bis(chelated) mononuclear compounds.
Reactions of the N3- or Cl-bridged dinuclear compounds con-
taining azobenzene derivatives with one equivalent depe smoothly
◦
˚
Fig. 3 ORTEP drawing of 7. Selected bond lengths (A) and angles ( ):
Pd1–C1 2.009(3), Pd1–N3 2.142(3), Pd1–P1 2.321(1), Pd1–P2 2.329(1),
N1–N2 1.220(4), N3–N4 1.158(5), N4–N5 1.175(5); C1–Pd1–N3 177.3(1),
C1–Pd1–P1 88.00(9), N3–Pd1–P1 91.32(9), P1–Pd1–P2 176.35(3),
N4–N3–Pd1 121.4(3), N3–N4–N5 176.5(4).
phosphine dppb produces the expected dinuclear Pd(II) azide
[Pd(N3)(C,N-L2)]2(m-dppb) (21), whose structure was determined
by X-ray diffraction (Fig. 6). In addition, reactions of the N3-
bridged dimer having L4H or L5H with those chelating phos-
phines produce only the phosphine-bridged dinuclear compound,
[Pd(N3)(C,N-L4)]2(m-P~P) (m-P~P = depe (22), dppp (23)) or
[Pd(N3)(C,N-L5)]2(m-depe) (24) (Scheme 7, Fig. 7). No other
bis(chelated) compounds, such as [Pd(C,N-L4)2] or [Pd(C,N-
L5)2], were observed. These results suggest that the ability of the
C,N-ligands to form a homoleptic bis(chelated) compound is in
proceeds to quantitatively give
a bis(chelated) compound
{[Pd(C,N-L2)2] (19) or [Pd(C,N-L3)2] (20)} and [Pd(depe)X2]
(Scheme 6). In contrast, similar reactions with the less basic
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˚
Fig. 4 ORTEP drawing of 12. Selected bond lengths (A) and an-
gles (◦): Pd1–C1 2.009(3), Pd1–N1 2.113(2), Pd1–N2 2.082(4), Pd1–P1
2.2375(7), Pd2–C37 2.010(3), Pd2–N5 2.115(2), Pd2–N6 2.109(3), Pd2–P2
2.2442(7); C1–Pd1–N2 169.5(2), C1–Pd1–N1 80.9(1), N1–Pd1–N2
89.0(1), C1–Pd1–P1 93.50(8), C37–Pd2–N6 169.3(1), C37–Pd2–N5
81.2(1), N5–Pd2–N6 88.1(1), C37–Pd2–P2 91.82(8), N2–N3–N4 155.5(7),
N8–N7–N6 176.5(3).
decreasing order of azobenzene derivatives (L2 or L3) >
thienylpyridine (L1) > 2-phenylpyridine (L5) ª N,N¢-dimethyl-
benzylamine (L4) and that the C-donor atom is bound to the Pd
metal more strongly than the N-donor atom.
The homoleptic bis(chelated) compounds [Pd(C,N-L1)2] (17)17
and [Pd(C,N-L2)2] (19)18,19 were previously prepared by treating the
dichloro- or Cl-bridged Pd compounds with the transmetallating
reagent (mercurated or lithiated) possessing those C,N-donor
ligands.17–27 In particular, these type of compounds possessing
azobenezene or phenylpyridine derivatives have gained consid-
erable attention due to their applications in photoactive or
liquid–crystalline materials.20 Therefore, their facile preparation
is currently an important research topic. As shown in Schemes 5
and 6, our synthetic route to the bis(chelated) compounds by the
use of basic chelating phosphines appears to be unique in that
those bis(chelated) products can be readily isolated from the other
products containing phosphine ligands.
◦
˚
Fig. 5 (a) ORTEP drawing of 17. Selected bond lengths (A) and angles ( ):
Pd1–C7 1.990(2), Pd1–C16 1.996(2), Pd1–N2 2.179(2), Pd1–N1 2.181(2);
C7–Pd1–C16 95.67(8), C7–Pd1–N2 176.18(7), C16–Pd1–N2 80.51(7),
C7–Pd1–N1 80.62(7), C16–Pd1–N1 175.27(6), N2–Pd1–N1 103.19(6).
(b) Packing diagram of complex 17. (c) A space-filling model for a
dimeric unit for complex 17: red, Pd; yellow, S; purple: N; grey: C; white,
H.
Reactivity toward organic isocyanides and isothiocyanates
Insertion of unsaturated organic molecules such as organic
isocyanides (CN–R) into the M–C bond in the orthometal-
lated compounds containing an aryl moiety of the C,N-donor
ligand is an important step in preparing a variety of organic
heterocycles.28–30 We previously reported the reactions of organic
isocyanides with group 10 metal azides having the C,N-donor
ligands, pyridyl or pyridyl–thiophene derivatives (Chart 2). These
reactions produced complexes containing an imidoyl group or
a C-coordinated tetrazolato ring, depending on the nature of
the incoming isocyanides or the C,N-donor ligands.16 With
these results in mind, we initiated insertion studies of organic
isocyanides towards the cyclopalladated azides.
The cyclopalladated azide complex [Pd(N3)(PMe3)(C,N-L4)] (2)
readily inserts one equivalent of isocyanide into the Pd–C (phenyl)
bond to give the corresponding imidoyl compound [Pd(N3)
4
=
(–C( N–Ar)(N-L )(PMe3)] (Ar = C6H3-2,6-i-Pr2; 25) (Scheme 8).
The molecular structure of 25 in Fig. 8 clearly demonstrates the
formation of the proposed imidoyl Pd(II) azide. The following
addition of another equivalent of isocyanide to complex 25
= =
produces the novel carbodiimido Pd(II) complex [Pd(N C N–
4
=
Ar)(–C( N–Ar)(N-L )(PMe3)] (26). These type of complexes
can also be prepared in a single step; that is, complexes 26
and 27 can be prepared by treating [Pd(N3)(PMe3)(C,N-L4)]
(2) and [Pd(N3)(PMe3)2(C-L4)] (10) with two equivalents of the
Chart 2
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◦
˚
Fig. 6 ORTEP drawing of 21. Selected bond lengths (A) and angles ( ):
Pd1–C1 2.006(3), Pd1–N4 2.102(2), Pd1–N1 2.109(3), Pd1–P1 2.2571(7),
N1–N2 1.180(4), N2–N3 1.159(4); N4–N5 1.266(4); C1–Pd1–N4
79.0(1), C1–Pd1–N1 166.9(1), N4–Pd1–N1 94.3(1), C1–Pd1–P1 95.01(9),
N4–Pd1–P1 173.79(8), N1–Pd1–P1 91.32(9), N3–N2–N1 175.9(4). Two
halves of this compound are related by the crystallographic center of
symmetry.
◦
˚
Fig. 8 ORTEP drawing of 25. Selected bond lengths (A) and angles ( ):
Pd1–C10 2.005(4), Pd1–N3 2.147(4), Pd1–N1 2.215(3), Pd1–P1 2.257(1),
N1–C3 1.502(5), N2–C10 1.274(4), N2–C11 1.417(4); C10–Pd1–N3
174.2(2), C10–Pd1–N1 89.6(1), N3–Pd1–N1 84.9(2), C10–Pd1–P1 94.3(1),
N3–Pd1–P1 91.4(1), N1–Pd1–P1 172.4(1).
◦
˚
Fig. 7 ORTEP drawing of 24. Selected bond lengths (A) and angles ( ):
Pd1–N1 2.000(3), Pd1–C1 2.091(3), Pd1–N2 2.119(3), Pd1–P1 2.2473(9),
P1–C12 1.826(4); N1–Pd1–C1 80.7(1), N1–Pd1–N2 170.1(1), C1–Pd1–N2
91.3(1), C12–P1–Pd1 112.7(1), N4–N3–N2 176.5(4).
Scheme 8
Pd(II) isothiocyanate complex trans-[Pd(NCS)(P(n-Pr3)2(C-L2)]
(29) by the replacement of N3 with NCS, or the dinuclear Pd
tetrazole–thiolato complex {Pd(PMe3)2(S[CN4])(C-L4)}2(m-C6H4)
(30) by the dipolar cycloaddition of R–NCS to the Pd–azido
bond (Scheme 9). Molecular structures of 28 (Fig. 9) and 29
(Fig. 10) were confirmed by X-ray diffraction. However, we
could not observe cyclometallation products formed by phosphine
dissociation. One of the reasons may be the relatively weak nucle-
ophilicity of the isothiocyanates, compared to the corresponding
isocyanides, toward a metal center.
corresponding CN–Ar (Ar = C6H3-2,6-i-Pr2, C6H3-2,6-Me2),
respectively. The formation of products (25–27) can be readily
followed by monitoring the characteristic IR bands of the imidoyl
=
group (C N), carbodiimido group, and azido groups. The IR
bands of the carbodiimido group (for 26 and 27) agree well with
those found in our previous work.16 In particular, complexes 26
and 27 were further characterized by HMQC (or HMBC) tech-
niques to accurately assign aromatic substituents in the imidoyl
=
= =
(–C N–Ar) and carbodiimidoyl (N C N–Ar) fragments.
On the other hand, reactions of the bis(phosphine) Pd(II) azides
(6, 9, 10), which have a s-bonded C-L1, C-L2, or C-L4 ligand,
with several organic isothiocyanates (R = 2,6-Me2C6H3, C6H4–
NCS, (CH3)3Si) produced the S-coordinated tetrazole–thiolato
Pd complex trans-[Pd(SCN4–2,6-Me2C6H3)(PMe3)2(C-L1)] (28) by
the dipolar cycloaddition of R–NCS to the Pd–azido bond, the
Structures of compounds
Details on crystal data, intensity collection, and refinement details
of 1, 3, 7, 12, 17, 21, 24, 25, 28 and 29 are given in Table 2. In all
structures, the coordination of the Pd metal is essentially square-
planar.
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Scheme 9
In complex 12, two [Pd(C,N-L1)(N3)(PPh2)]2 moieties are linked
by a propylene fragment, and each Pd is planar four-coordinate
(Fig. 4). Interestingly, one azido group (N6–N7–N8) is essentially
linear with the bond angle of 176.5(3)◦, whereas the other
(N2–N3–N4) is severely bent with the bond angle of 155.5(7)◦.
Unfortunately, we cannot provide a reasonable explanation for
this phenomenon.
In complex 17, the molecule has a pseudo-C2 axis passing
through the Pd metal (Fig. 5(a)). The carbon donors are trans
to the nitrogen donors, which leads to the cisoid orientation of
two sulfur atoms. The Pd–C bond distances are shorter than
the Pd–N bond distances, indicating that the carbon atoms have
stronger trans-influence power than the nitrogen atoms. A packing
diagram of complex 17 is presented in Fig. 5(b), which shows
an intriguing structural feature, a pseudo-dimeric unit. This unit
is formed by the p–p stacking between the thiophene ring in
one molecule and the pyridine ring in another. There are two
distinct separations between centroids of the two rings (3.75 and
The coupling reactions catalyzed by cyclopalladated complexes
containing C~N donor ligands have been studied.1,32–38 However,
the coupling reactions using cyclometallated complexes contain-
ing pseudo-halide ligands are relatively rare. In this context,
we evaluated the catalytic activity of our cyclopalladated azido
complexes for the Suzuki–Miyaura coupling (Scheme 10). In a
typical catalytic reaction, a catalyst (1 mol%) in toluene was added
to a mixture of aryl bromide, phenylboronic acid, and K2CO3 in
the molar ratio of 1 : 1.3 : 2. Reaction conditions and product yields
are listed in Table 3.
Scheme 10
˚
˚
3.92 A), and the Pd ◊ ◊ ◊ Pd separation is 3.75 A. This type of
p–p interaction is known to be important for the formation of
coordination polymers. In particular, for face-to-face interactions,
the centroid–centroid separations are typically found to be in the
Chart 3 presents the Pd catalysts used in the experiments.
Table 3 shows that all the Pd catalysts exhibit high activity
especially for para-acetyl-substituted bromobenzene and 4-cyano-
bromobenzene (entries 1–10), in some cases even with 0.1 mol%
Pd catalyst (entry 9). Also, the coupling reactions involving para-
acetyl-substituted bromobenzenes generally give higher yields
than those involving 4-bromoanisole or ortho-bromoanisole (en-
tries 11 and 12), and this reactivity was also observed for other
known Pd-catalyzed coupling reactions.32–37 In particular, the
reactions with the dinuclear cyclopalladated azides (entries 6–8) in
ethanol in place of toluene gave relatively higher yields than those
with mono or s-bonded Pd(II) azides, probably due to the higher
solubility of the dinuclear species. Unfortunately, the reactions
involving the chloro-substituted aryl compounds exhibited poor
reactivity for our compounds (entries 13–15). The results of
the catalytic experiments indicate that our cyclopalladated azido
compounds are rather efficient catalysts for the cross-coupling of
aryl bromides and phenylboronic acid. However, we believe that
further studies are necessary to tune our compounds that can
undergo the catalytic reactions under milder conditions.
range of 3.4–3.8 A.31 A space-filling model of the dimer unit clearly
˚
demonstrates its p–p interaction (Fig. 5(c)).
In complex 25, an imidoyl moiety, formed by the selective
insertion of the isocyanide (C N–Ar) into the Pd–C bond in
C,N-donor ligand, is observed (Fig. 8). In complex 28 (Fig. 9(a)),
interestingly, the square-planar Pd metal is further bound to the
S atom in the neighboring molecule by van der Waals contacts
≡
˚
(Pd ◊ ◊ ◊ S = 3.4471(8) A). These contacts connect the molecules
approximately along the b-axis to give a 1-dimensional helical
network (Fig. 9(b)). A space filling model (Fig. 9(c)) clearly
demonstrates the helical structure. For comparison, the van der
˚
Waals radii of Pd and S atoms are 1.63 and 1.80 A, respectively.
Catalytic application for cross-coupling reactions
Suzuki–Miyaura coupling of aryl halides with aryl boronic acid is
an efficient tool for the preparation of various biaryl compounds.32
6584 | Dalton Trans., 2009, 6578–6592
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◦
˚
Fig. 10 ORTEP drawing of 29. Selected bond lengths (A) and angles ( ):
Pd1–C2 2.021(6), Pd1–N1 2.078(6), Pd1–P1 2.327(2), Pd1–P2 2.338(2),
S1–C1 1.629(5), N1–C1 1.153(7), N2–N3 1.257(6); C2–Pd1–N1 177.0(3),
C2–Pd1–P1 91.2(2), N1–Pd1–P1 87.5(2), C2–Pd1–P2 88.2(2), N1–Pd1–P2
93.2(2), P1–Pd1–P2 179.23(8), C1–N1–Pd1 172.9(5), N1–C1–S1 178.4(5).
◦
˚
Fig. 9 (a) ORTEP drawing of 28. Selected bond lengths (A) and angles ( ):
Pd1–C3 2.020(2), Pd1–P2 2.3042(9), Pd1–P1 2.3151(8), Pd1–S2 2.4005(7),
S2–C16 1.715(3), N2–N3 1.350(4), N3–N4 1.285(4), N4–N5 1.341(3),
N5–C16 1.348(3); P2–Pd1–P1, 174.75(3), P2–Pd1–S2 88.79(3), P1–Pd1–S2
96.34(3), C1–S1–C4 91.1(1), C16–S2–Pd1 103.56(9), C16–N2–N3.
(b) Projection of complex 28 perpendicular to the (100) plane, showing a
1-dimensional helical network approximately along the b-axis. (c) A space
filling model of the packing of compound 28 showing its helical structure:
red, Pd; yellow, S; orange: P; purple: N; grey: C.
Chart 3
Experimental
General, materials and measurements
All manipulations of air-sensitive compounds were performed
under N2 or Ar by standard Schlenk-line techniques. Solvents
were distilled from Na–benzophenone. The analytical laboratories
at Kangnung National University carried out elemental analyses
with a CE instrument EA1110. IR spectra were recorded on a
In summary, we prepared a series of cyclopalladated azides hav-
ing C,N-donor ligands and found their lability toward chelating
phosphines to give neutral dinuclear and bis(chelated) compounds.
We observed the selective insertion of small molecules such
as organic isocyanides into the Pd–C or Pd–azido bond in
those azido complexes to give the imidoyl Pd(II) azides or the
imidoyl Pd(II) carbodiimides. Interestingly, the crystal structure of
complex 28, trans-{PdS[CN4(i-Pr)](PMe3)2(C-L1)}, was found to
have a 1-dimensional helical network formed by the intermolecular
Pd ◊ ◊ ◊ S van der Waals contacts. Finally, our cyclopalladated azides
appeared to be potential catalysts for Suzuki–Miyaura coupling
of aryl bromides and phenylboronic acid.
1
Perkin Elmer BX spectrophotometer. NMR (1H, 13C{ H}, and
1
31P{ H}) spectra were obtained on a JEOL Lamda 300 MHz
spectrometer. Chemical shifts were referenced to internal Me4Si
or to external 85% H3PO4. Mass (FAB) spectra were obtained
at the Korea Basic Science Institute (Seoul). [Pd(m-Cl)(C,N-L)]2
were prepared by the literature or modified methods.38,39 2,6-
Diisopropylphenyl isocyanide was prepared as described in the
literature.40
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Table 3 Suzuki–Miyaura cross-coupling reaction of arylhalides and phenylboronic acid catalyzed by palladacyclesa
Entry
1
Aryl bromide
Pd catalyst
Reaction time/h
1
Product
Isolated yield (%)
96
1
2
3
4
5
6
7
8
9d
2
5
1
1
1
1
1
1
1
1
96
95
10
11
12
13
23
2
93
94 (69)b
87 (99)c
88 (99)c
92 (99)c
93
10
11
12
2
2
2
1
1
1
92
56 (70)e
63
13
2
20
14 (22)f(16)g
14
15
2
2
5
5
24
NR
a All reactions were carried out with 0.2 mmol aryl halide and 0.26 mmol phenylboronic acid. b Reaction was performed at room temperature for 24 h.
c Ethanol in place of toluene was used as a solvent. d Reaction was carried out with 1.0 mmol 4¢-bromo acetophenone and 1.3 mmol phenylboronic acid
in the presence of 0.1 mol% Pd catalyst 2 and 4.0 mmol K2CO3. e Pd catalyst 5 was used. f Ethanol was used as a solvent. g Pd catalyst 23 and ethanol as
a solvent were used under the same reaction conditions.
Preparations
a glass frit and washed with H2O and n-hexane. The product was
dried under vacuum to give yellow product (0.389 g, 82%). [Pd(m-
N3)(C,N-L1)]2: (Found: C, 34.94; H, 1.83; N, 17.64. C18H12N8Pd2S2
requires: C, 35.02; H, 1.95; N, 18.15).
[Pd(m-N3)(C,N-L2)]2, [Pd(m-N3)(C,N-L3)]2, [Pd(m-N3)(C,N-
L4)]2,8 and [Pd(m-N3)(C,N-L5)]2 were similarly prepared and used
as starting materials in the subsequent reactions (Schemes 3–6)
without recrystallization due to their poor solubility in common
[Pd(m-N3)(C,N-Ln)]2 (n = 1–5). [Pd(m-N3)(C,N-L1)]2 was prepared
by a modified literature method.8 To a homogeneous solution of
[Pd(m-Cl)L1]2 (0.464 g, 0.768 mmol) in DMSO (100 cm3) was added
a solution of NaN3 (0.150 g, 2.30 mmol) in H2O (2 cm3). After
stirring for 18 h at room temperature, excess H2O was added to
the mixture to give yellow precipitate. The solids were filtered with
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organic solvents. [Pd(m-N3)(C,N-L2)]2: (Found: C, 43.37; H,
2.66; N, 20.72. C24H18N10Pd2 requires: C, 43.72; H, 2.75; N,
21.24). [Pd(m-N3)(C,N-L3)]2: (Found: C, 46.46; H, 3.98; N, 19.49.
C28H26N10Pd2 requires: C, 47.01; H, 3.66; N, 19.58). [Pd(m-
N3)(C,N-L5)]2: (Found: C, 43.38; H, 2.61; N, 18.22. C22H16N8Pd2
requires: C, 43.65; H, 2.66; N, 18.51).
12 Hz), 136.2 (d, JP–C = 11 Hz), 149.0 (d, JP–C = 2.2 Hz, C2), 149.3
(d, JP–C = 5.0 Hz, C1); dP (CDCl3) 11.8 (s).
Data for 5: nmax (KBr, cm-1) 2028 (N3); dH (CDCl3) 1.19 (m,
9H, P(C6H11)3), 1.55–1.97 (m, 24H, P(C6H11)3), 2.21–2.33 (m, 3H,
P(C6H11)3), 2.67 (d, 6H, J = 2.6 Hz, NMe2), 3.94 (d, 2H, J =
1.3 Hz, CH2), 6.86–7.00 (m, 3H, Ph), 6.86–7.00 (m, 1H, Ph); dC
(CDCl3) 26.4 (d, JP–C = 1.2 Hz, P(C6H11)3), 27.7 (d, JP–C = 11 Hz,
P(C6H11)3), 30.0 (s, NMe2), 33.6 (d, JP–C = 22 Hz, P(C6H11)3), 49.6
(d, JP–C = 2.5 Hz, CH2), 72.6 (d, JP–C = 3.1 Hz, CH2), 122.9 (s, C3),
123.8 (s, C4), 125.3 (d, JP–C = 3.7 Hz, C5), 136.6 (d, JP–C = 5.6 Hz,
C6), 148.6 (d, JP–C = 1.9 Hz, C2), 150.4 (d, JP–C = 3.7 Hz, C1); dP
(CDCl3) 43.1 (s).
Cleavage of [Pd(l-N3)(C,N-L)]2 by tertiary (2 or 4 equivalents) or
chelating phosphine (1 equivalents)
Path A. To a Schlenk flask containing [Pd(m-N3)(C,N-L1)]2
(0.340 g, 0.55 mmol) were added CH2Cl2 (15 cm3) and PMe3
(0.084 g, 1.10 mmol). An initial dark yellow suspension slowly
turned to a homogeneous brown solution. After stirring for
2 h at room temperature, the solvent was removed, and the
resulting residue was washed with n-hexane to give yellow solids.
Recrystallization from CH2Cl2–n-hexane gave yellow crystals of
[Pd(N3)(PMe3)(C,N-L1)] (1, 0.210 g, 49%). nmax (KBr, cm-1) 2040
(N3); dH (CDCl3) 1.76 (d, 9H, J = 11 Hz, P(CH3)3), 6.94 (dd, 1H,
J = 1.5, 4.9 Hz, H4¢), 7.12 (ddt, 1H, J = 1.3, 5.5, 7.5 Hz, H5),
7.37 (dd, 1H, J = 1.1, 4.7 Hz, H5¢), 7.39 (m, 1H, H3), 7.75 (dt,
1H, J = 1.7, 7.7 Hz, H4), 8.74 (m, 1H, H6); dC (CDCl3) 15.7 (d,
JP–C = 33 Hz, P(CH3)3), 117.4 (d, JP–C = 1.9 Hz, C3), 120.4 (d,
Path B. CH2Cl2 (30 cm3) and PMe3 (0.308 g, 4.04 mmol) were
added to [Pd(m-N3)(C,N-L1)]2 (0.624 g, 1.01 mmol) in a Schlenk
flask. After stirring for 18 h, the solvent was removed and washed
with n-hexane to give white solids. Recrystallization from CH2Cl2–
diethyl ether (v/v = 2 : 1) gave white crystals of [Pd(N3)(PMe3)2(C-
L1)] (6, 0.591 g, 63%). nmax (KBr, cm-1) 2035 (N3); dH (CDCl3) 1.16
(s, 18H, P(CH3)3), 6.97 (d, 1H, J = 4.9 Hz, H4¢), 7.10 (ddt, 1H,
J = 1.1, 4.8, 9.8 Hz, H5), 7.37 (d, 1H, J = 4.9 Hz, H5¢), 7.70 (dt,
1H, J = 8.0 Hz, H3), 8.56 (dt, 1H, J = 1.0, 4.3 Hz, H4), 9.00 (d,
1H, J = 8.0 Hz, H6); dC (CDCl3) 13.5 (s, P(CH3)3), 118.3 (s, C3),
120.8 (s, C5), 126.8 (s, C5¢), 133.9 (s, C4¢), 136.2 (s, C4), 139.1 (s, C2¢),
143.0 (s, C3¢), 149.5 (s, C6), 154.9 (s, C2); dP (CDCl3) -14.2 (s).
Complexes 7–10 [Pd(N3)(PR3)2(C-L2)] (PR3 = PMe3, PEt3, P(n-
Pr)3) and [Pd(N3)(PMe3)2(C-L4)] were similarly prepared.
Data for 7: nmax (KBr, cm-1) 2032 (N3); dH (CDCl3) 1.07 (t, 18H,
J = 3.2 Hz, P(CH3)3), 7.07–7.17 (m, 2H, Ar), 7.44–7.53 (m, 4H,
Ar), 7.79 (m, 1H, 8.07 (m, 2H, Ar); dC (CDCl3) 13.5 (t, J = 14 Hz,
P(CH3)3), 122.7 (s, C8), 123.7 (s, C3), 127.1 (s, C9), 129.4, 129.6,
130.6, 137.4 (br, C6), 152.3 (s, C7), 152.3 (s, C1), 156.3 (s, C2); dP
(CDCl3)–17.3 (s).
JP–C = 3.7 Hz, C5), 126.5 (d, JP–C = 4.4 Hz, C5¢), 133.1 (d, JP–C
=
8.1 Hz, C4¢), 139.6 (s, C4), 142.5 (d, JP–C = 2.5 Hz, C2¢), 148.3 (s,
C3¢), 153.5 (d, JP–C = 8.7 Hz, C6), 159.0 (d, JP–C = 2.4 Hz, C2); dP
(CDCl3)–3.83 (s).
Complexes 2–5 [Pd(N3)(PR3)(C,N-L4)] (PR3 = PMe3, PEt3,
PMe2Ph, PCy3) were analogously prepared. Data for 2: nmax
(KBr, cm-1) 2056 (N3); dH (CDCl3) 1.63 (d, 9H, J = 11 Hz,
P(CH3)3), 2.69 (d, 6H, J = 2.7 Hz, NMe2), 3.90 (d, 2H, J =
2.6 Hz, CH2), 6.96–7.06 (m, 4H, Ph); dC (CDCl3) 14.5 (d, JP–C
32 Hz, P(CH3)3), 49.7 (d, JP–C = 2.8 Hz, NMe2), 72.0 (d, JP–C
=
=
3.5 Hz, CH2), 123.1 (s, C3), 124.5 (s, C4), 125.8 (d, JP–C = 5.0 Hz,
C5), 135.7 (d, JP–C = 10 Hz, C6), 149.2 (d, JP–C = 1.8 Hz, C2), 150.0
(br, C1); dP (CDCl3) -3.33 (s).
Data for 8; nmax (KBr, cm-1) 2031 (N3); dH (CDCl3) 1.01 (qnt,
18H, J = 8.0 Hz, P(CH2CH3)3), 1.45 (m, 12H, P(CH2CH3)3), 7.07
(dt, 2H, J = 3.5, 9.2 Hz, H5¢, H6), 7.42–7.66 (m, 5H), 8.03–8.06
Data for 3: nmax (KBr, cm-1) 2041 (N3); dH (CDCl3) 1.20 (dt,
9H, J = 7.5, 9 Hz, P(CH2CH3)3), 1.94 (dq, 6H, J = 7.7, 9.5 Hz,
P(CH2CH3)3), 2.68 (d, 6H, J = 2.6 Hz, NMe2), 3.91 (d, 1H, J =
(m, 2H, H2¢); dC (CDCl3) 7.76 (s, P(CH2CH3)3), 14.5 (t, JP–C
=
2.1 Hz, CH2), 6.92–7.04 (m, 4H, Ph); dC (CDCl3) 8.66 (d, JP–C
=
12 Hz, P(CH2CH3)3), 122.6 (s, C8), 122.9 (s, C3), 123.5 (s, C9),
129.1, 129.2, 130.5, 137.4 (t, JP–C = 4.4 Hz, C6), 152.3 (s, C7), 153.8
(s, C1), 156.8 (s, C2); dP (CDCl3) 12.0 (s).
1.2 Hz, P(CH2CH3)3), 15.6 (d, JP–C = 29 Hz, P(CH2CH3)3), 49.5
(d, JP–C = 2.8 Hz, NMe2), 72.1 (d, JP–C = 3.4 Hz, CH2), 123.9 (s,
C3), 124.3 (s, C4), 125.7 (d, JP–C = 4.3 Hz, C5), 135.4 (d, JP–C
=
Data for 9: nmax (KBr, cm-1) 2035 (N3); dH (CDCl3) 0.85 (br,
18H, P(CH2CH2CH3)3), 1.39 (m, 24H, P(CH2CH2CH3)3), 7.04–
7.07 (br, H5¢, H6), 7.44–7.62 (m, 5H), 8.03–8.06 (m, 2H, H2¢);
dC (CDCl3) 15.9 (t, JP–C = 6.8 Hz, P(CH2CH2CH3)3), 17.5 (s,
P(CH2CH2CH3)3), 24.9 (t, JP–C = 12 Hz, P(CH2CH2CH3)3), 121.0
(s, C8), 122.9 (s, C3), 123.5 (s, C9), 129.0, 129.1, 130.4, 137.5, 152.4
(s, C7), 155.1 (s, C1), 156.8 (s, C2); dP (CDCl3) 4.39 (s).
8.4 Hz, C6), 149.2 (d, JP–C = 2.2 Hz, C2), 149.5 (d, JP–C = 5.2 Hz,
C1); dP (CDCl3) 32.5 (s).
Data for 4: nmax (KBr, cm-1) 2060 (N3); dH (CDCl3) 1.83 (d, 6H,
J = 10 Hz, P(CH3)2Ph), 2.78 (d, 6H, J = 2.7 Hz, NMe2), 3.95 (d,
2H, J = 2.5 Hz, CH2), 6.52 (dt, 1H, J = 1.1, 5.9 Hz, Ar), 6.68
(dt, 1H, J = 1.3, 7.3 Hz, Ar), 6.88–7.01 (m, 2H, Ar), 7.45–7.50
(m, 3H, Ar), 7.87–7.94 (m, 2H, Ar); dC (CDCl3) 15.2 (d, JP–C
33 Hz, P(CH3)2Ph), 49.8 (d, JP–C = 2.8 Hz, NMe2), 72.1 (d, JP–C
=
=
Data for 10: nmax (KBr, cm-1) 2033 (N3); dH (CDCl3) 1.19 (s,
18H, P(CH3)3), 2.31 (s, 6H, NMe2), 3.51 (s, 2H, CH2), 6.88–6.91
(m, 2H, H4, H5), 7.06–7.09 (m, 1H, H6), 7.18–7.22 (m, 1H, H3);
dC (CDCl3) 13.6 (br, 18H, P(CH3)3), 46.4 (s, 6H, NMe2), 69.1 (s,
3.5 Hz, CH2), 122.8 (s, C3), 124.3 (s, C4), 125.7 (d, JP–C = 5.6 Hz),
128.9 (d, JP–C = 11 Hz), 131.1 (d, JP–C = 2.8 Hz), 132.2 (d, JP–C
6588 | Dalton Trans., 2009, 6578–6592
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CH2), 122.7 (s, C3), 126.0 (s, C4), 128.1 (s, C5), 135.2 (s, C6), 143.1
(m, 9H, Ar), 7.73–7.79 (m, 4H, Ar), 7.87–7.97 (m, 3H, Ar); dC
(CDCl3) 13.5 (t, J = 14 Hz, P(CH3)3), 122.7 (s, C8), 123.7 (s, C3),
127.1, 129.4, 129.6, 130.6, 137.4 (br, C6), 152.3 (s, C7), 152.3 (s,
C1), 156.3 (s, C2); dP (CDCl3) 34.1 (s).
(s C2), 154.0 (s, C1); dP (CDCl3) -15.1 (s).
Path C. To a Schlenk flask containing [Pd(m-N3)(C,N-L1)]2
(0.250 g, 0.40 mmol) were added CH2Cl2 (85 cm3) and dppf
(0.224 g, 0.40 mmol). After stirring for 5 h, the solvent was
removed, and the resulting residue was washed with diethyl ether
to give dark yellow solids, which were recrystallized from CH2Cl2–
n-hexane gave dark yellow crystals of [Pd(N3)(C,N-L1)]2(m-dppf)
(11, 0.445 g, 94%). nmax (KBr, cm-1): 2034 (N3); dH (CDCl3) 4.44
(q, 4H, Fe(C5H4)), 5.07 (br, 4H, Fe(C5H4)), 5.76 (dd, 2H, J =
1.7, 5.0 Hz, H4¢), 6.89 (dd, 2H, J = 0.9, 5.0 Hz, H5¢), 7.15 (br,
2H, Ar), 7.31–7.49 (m, 16H, Ar), 7.57–7.64 (m, 6H, Ar), 7.77 (dt,
2H, J = 1.7, 7.9 Hz, H4), 8.69 (m, 2H, H6); dC (CDCl3) 75.7 (t,
J = 3.7 Hz, Fe(C5H4)), 75.8 (s, Fe(C5H4)), 117.5 (s, C3), 120.4 (d,
Data for 22: nmax (KBr, cm-1) 2037 (N3); dH (CDCl3) 1.10 (dt,
12H, J = 7.5, 17 Hz, P(CH2CH3)2), 1.93 (m, 8H, P(CH2CH3)2),
2.14 (d, 4H, J = 2.1 Hz, PCH2), 2.67 (s, 12H, NMe2), 3.91 (s,
4H, CH2), 6.97 (m, 8H, Ar); dC (CDCl3) 8.43 (s, P(CH2CH3)2),
15.5 (t, JP–C = 13.7 Hz, P(CH2CH3)2), 17.8 (t, JP–C = 13.7 Hz,
P(CH2CH3)2), 49.5 (s, NMe2), 72.1 (s, CH2), 123.2 (s, C3), 124.6
(s, C4), 126.1 (d, JP–C = 2.2 Hz, C5), 135.1 (d, JP–C = 4.3 Hz, C6),
149.1 (d, JP–C = 0.9 Hz, C2), 159.2 (br, C1); dP (CDCl3) 34.0 (s).
Data for 24: nmax (KBr, cm-1) 2036 (N3); dH (CDCl3) 1.15
(dt, 12H, J = 7.5, 17 Hz, P(CH2CH3)2), 1.97–2.23 (m, 8H,
P(CH2CH3)2), 2.38 (s, 4H, PCH2), 6.90 (dt, 2H, J = 0.9, 7.5 Hz,
H5). 7.01 (dt, 2H, J = 1.4, 7.3 Hz, H5¢), 7.15–7.19 (m, 2H, Ar),
7.27 (m, 2H, Ar), 7.33 (dd, 2H, J = 1.5, 7.7 Hz, H3¢), 7.64 (d, 2H,
J = 8.0 Hz, H3), 7.83 (dt, 2H, J = 1.7, 8.0 Hz, H4), 8.88 (m, 2H,
H6); dC (CDCl3) 8.41 (s, P(CH2CH3)2), 15.3 (dd, JP–C = 14 Hz,
P(CH2CH3)2), 18.2 (t, JP–C = 14 Hz, P(CH2CH3)2), 118.2 (s, C3),
122.4 (s, C5), 124.2 (s, C5¢), 124.8 (s, C4¢), 129.8 (t, JP–C = 2.5 Hz,
C6), 135.9 (t, JP–C = 4.9 Hz, C3¢), 147.4 (s, C4), 148.9 (s, C1¢), 154.0
(s, C6), 163.9 (s, C2¢), 165.3 (s, C2); dP (CDCl3) 32.9 (s).
JP–C = 3.7 Hz, C5), 124.7 (d, JP–C = 4.4 Hz, C5¢), 128.3 (d, JP–C
=
11 Hz, C4¢), 130.2, 130.9, 130.9 (d, JP–C = 3.1 Hz, Ar), 133.7 (d,
JP–C = 1.2 Hz, Ar), 135.8 (d, JP–C = 8.1 Hz, Ar), 139.6 (s, C4), 142.0
(d, JP–C = 2.5 Hz, C2¢), 148.6 (s, C3¢), 154.2 (d, JP–C = 7.4 Hz, C6),
159.6 (d, JP–C = 2.5 Hz, C2); dP (CDCl3) 28.8 (s).
Similar treatments of [Pd(m-N3)(C,N-L1)]2, [Pd(m-N3)(C,N-
L3)]2, [Pd(m-N3)(C,N-L4)]2, and [Pd(m-N3)(C,N-L5)]2 with 1 equiv-
alent dppp, dppb, and depe gave the corresponding azido com-
plexes 12–14 and 21–24. Analytical and spectroscopic data of 23
were in agreement with those reported by Caires and co-workers.8
Data for 12: nmax (KBr, cm-1) 2038 (N3); dH (CDCl3) 2.15 (br, 2H,
–CH2), 2.83 (br, 4H, P–CH2), 5.89 (dd, 2H, J = 1.7, 5.0 Hz, H4¢),
6.88 (dd, 2H, J = 0.7, 5.0 Hz, H5¢), 7.16 (br, 4H, Ar), 7.30–7.41
(m, 14H), 7.68–7.80 (m, 10H), 8.78 (br, 2H, H6); dC (CDCl3) 21.9
(s, CH2), 27.8 (d, JP–C = 13 Hz, P–CH2), 29.2 (d, JP–C = 16 Hz,
Reactions of [Pd(l-X)(C,N-L1)]2 (X = N3, Cl) with 1 or
2 equivalents chelating phosphine. CH2Cl2 (75 cm3) and depe
(0.102 g, 0.49 mmol) were added to [Pd(m-N3)(C,N-L1)]2 (0.305 g,
0.49 mmol) in a Schlenk flask. After stirring for 18 h, the slightly
insoluble materials remained. The filtrate was evaporated and then
extracted with benzene (10 cm3 ¥ 3). The collected solution was
evaporated to give yellow solids, which were recrystallized from
CH2Cl2–n-hexane to give orange solids of complex 17 (0.030 g,
14%). The residues were recrystallized form CH2Cl2–n-hexane to
give pale yellow solids of [Pd(N3)(C,N-L1)]2(m-depe) (14, 0.243 g,
60%).
P–CH2), 117.4 (s, C3), 120.3 (d, JP–C = 3.1 Hz, C5), 125.2 (d, JP–C
=
3.8 Hz, C5¢), 128.7 (d, JP–C = 11 Hz), 129.6, 130.2, 131.0, 133.5 (d,
JP–C = 12 Hz), 135.0 (d, JP–C = 8.1 Hz), 139.6 (s,), 141.9 (d, JP–C
=
2.5 Hz, C2¢), 148.5 (s, C3¢), 154.0 (d, JP–C = 5.6 Hz, C6), 159.4 (br,
C2); dP (CDCl3) 31.1 (s).
Data for 13: nmax (KBr, cm-1) 2036 (N3); dH (CDCl3) 1.86 (br,
4H, P–CH2), 2.61 (br, 4H, P–CH2), 5.94 (dd, 2H, J = 1.7, 5.0 Hz,
H4¢), 6.90 (dd, 2H, J = 1.1, 5.0 Hz, H, H5¢), 7.12 (ddt, 2H, J = 1.3,
5.0, 7.4 Hz, H5), 7.34–7.48 (m, 14H, Ar), 7.71–7.83 (m, 10H, Ar),
8.80 (m, 2H, H6); dC (CDCl3) 26.2 (d, JP–C = 17 Hz, P–CH2), 27.3
(d, JP–C = 32 Hz, P–CH2), 117.4 (d, JP–C = 1.2 Hz, C3), 120.4 (d,
Data for 17: dH (CDCl3) 7.07 (dt, 1H, J = 1.3, 7.4 Hz, H5), 7.45
(d, 2H, J = 4.8 Hz, H5), 7.47 (overlap, 2H, H3+4¢), 7.65 (d, J =
4.7 Hz, H5¢), 7.71 (m, 2H, H4), 8.48 (m, 1H, H6); dC (CDCl3) 118.2
(s, C3), 119.7 (s, C5), 126.3 (s, C5¢), 135.8 (d, C4¢), 138.6 (s, C4),
141.5 (s, C2¢), 147.9 (s, C3¢), 158.1 (s, C6), 160.5 (s, C2). Complex 17
was could also be prepared from Pd(Et2S)2Cl2 and 2 equivalents
of lithiated 2-(2¢-thienyl)pyridine.17
JP–C = 3.8 Hz, C5), 125.2 (d, JP–C = 4.3 Hz, C5¢), 128.7 (d, JP–C
=
11 Hz, Ar), 129.7, 130.4, 131.1 (d, JP–C = 3.1 Hz, Ar, 133.6 (d,
JP–C = 12 Hz, Ar), 135.1 (d, JP–C = 8.7 Hz, Ar), 139.6 (s, Ar), 141.9
(d, JP–C = 2.5 Hz, C2¢), 148.6 (s, C3¢), 154.1 (d, JP–C = 5.6 Hz, C6),
159.4 (d, JP–C = 3.1 Hz, C2); dP (CDCl3) 31.7 (s).
The similar reaction of [Pd(m-N3)(C,N-L1)]2 (0.305 g,
0.49 mmol) with 2 equivalents depe (0.204 g, 0.98 mmol) gave
white solids of [Pd(C,N-L1)(depe)](N3) (18, 0.297 g, 58%). The
solids were slightly hygroscopic and characterized by spectroscopic
(IR, 1H, 13C and 31P NMR) analyses. nmax (KBr, cm-1) 2035 (N3);
dH (CDCl3) 1.26 (two dt, 12H, J = 7.5, 16 Hz, P(CH2CH3)2), 2.09–
2.51 (m, 12 H, P–CH2), 7.06–7.09 (m, 1H, H4¢), 7.35–7.47 (m, 2H,
H5 + H3), 7.65 (dd, J = 1.0, 8.0 Hz, 1H, H5¢), 7.89 (dt, 1H, J = 1.5,
7.7 Hz, H4), 8.74 (m, 1H, H6); dC (CDCl3) 9.51 (dd, JP–C = 14 Hz,
Data for 14: nmax (KBr, cm-1) 2039, 2052 (N3); dH (CDCl3) 1.17
(dd, 12H, J = 7.5, 12 Hz, P–(CH2CH3)2), 2.11 (m, 8H, P–CH2),
2.38 (br, 4H, P–CH2), 6.92 (dd, 2H, J = 4.9 Hz, H4¢), 7.13 (m,
2H, H5), 7.20 (d, 2H, J = 7.9 Hz), 7.28 (d, 2H, J = 7.9 Hz), 7.74
(dt, 2H, J = 1.7, 7.7 Hz, H4), 8.69 (m, 2H, H6); dC (CDCl3) 8.17
(s, CH2), 15.8 (d, JP–C = 15 Hz, P–CH2), 18.9 (t, JP–C = 15 Hz,
P(CH2CH3)2), 18.2 (d, JP–C = 21 Hz, P(CH2CH3)2), 20.1 (d, JP–C
=
P–CH2), 117.3(s, C3), 120.4 (d, JP–C = 1.6 Hz, C5), 126.6 (t, JP–C
=
32 Hz, P(CH2CH3)2), 22.0 (dd, JP–C = 8.1, 29 Hz, P–CH2–), 25.9
(dd, JP–C = 17, 32 Hz, P–CH2–), 119.1 (d, JP–C = 3.7 Hz, C3), 122.5
(d, JP–C = 4.4 Hz, C5), 127.7 (dd, JP–C = 3.1, 11 Hz, C4¢), 133.3 (t,
1.6 Hz, C5¢), 132.8 (t, JP–C = 3.1 Hz, C4¢), 139.4 (s, C4), 142.4 (d,
JP–C = 1.3 Hz, C3¢), 152.7 (t, JP–C = 4.0 Hz, C6), 159.1 (t, JP–C
=
1.2 Hz, C2); dP (CDCl3) 34.0 (s).
JP–C = 7.2 Hz, C4), 140.2, 151.1 (d, JP–C = 5.0 Hz), 160.8 (t, JP–C
=
Data for 21: nmax (KBr, cm-1) 2041 (N3); dH (CDCl3) 1.71 (br,
4H, P–CH2), 2.50 (br, 4H, P–CH2), 6.47 (t, 1H, J = 6.75 Hz, Ar),
6.70 (dt, 1H, J = 1.3, 7.5 Hz, Ar), 7.09 (m, 1H, Ar), 7.36–7.52
1.2 Hz), 160.7 (dd, JP–C = 2.5, 3.7 Hz), 162.8 (d, JP–C = 6.2 Hz),
164.3 (d, JP–C = 6.3 Hz); dP (CDCl3) 56.1 (d, J = 31 Hz), 69.5 (d,
J = 18 Hz).
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CH2Cl2 (60 cm3) and depe (0.119 g, 0.58 mmol) were added to
[Pd(m-Cl)(C,N-L1)]2 (0.350 g, 0.58 mmol), and the mixture was
stirred for 18 h. The resulting solution was filtered and evaporated
to give yellow residues, which were solidified with diethyl ether to
give yellow solids. Recrystallization from CH2Cl2–n-hexane gave
orange crystals of [Pd(C,N-L1)2] (17, 0.060 g, 24%). The filtrate
was evaporated under vacuum to give pale yellow solids, which
were recrystallized from CH2Cl2–diethyl ether to give a mixture of
[PdCl(C,N-L1)]2(m-depe) (16) and (depe)PdCl2. dH (CDCl3) 1.76
(br t, 12H, J = 5.1 Hz, P(CH2CH3)2), 1.93 (m, 8H, P(CH2CH3)2),
2.48 (s, 4H, P–CH2), 6.96 (d, 2H, J = 5.0 Hz, H4¢), 7.08 (m, 2H,
H5), 7.22 (d, 2H, J = 5.0 Hz, H5¢), 7.33 (d, 2H, J = 7.5 Hz, H3),
7.71 (dt, 2H, J = 1.5, 7.7 Hz, H4), 9.20 (m, 2H, H6). The 13C NMR
data could not be obtained due to its poor solubility. dP (CDCl3)
9.70 (s).
The similar reaction of [Pd(m-Cl)(C,N-L1)]2 with 1 equivalent
dmpe gave a mixture of 17 and [PdCl(C,N-L1)]2(m-dmpe) (15).
Data for 15: dH (CDCl3) 1.76 (dd, 12H, J = 5.3 Hz, P(CH3)2),
2.48 (m, 4H, P–CH2), 6.96 (m, 2H, H4¢), 7.08 (br, 2H, H5), 7.22 (d,
2H, J = 4.9 Hz, H5¢), 7.33 (d, 2H, J = 5.0, 8.0 Hz, H3), 7.77 (dt,
2H, J = 1.7, 7.7 Hz, H4), 9.15 (m, 2H, H6); dC (CDCl3) 15.0 (dd,
JP–C = 16 Hz, P(CH3)2), 26.2 (dd, JP–C = 17 Hz, P-CH2), 117.2(s,
C3), 120.1(s, C5), 126.2 (s, C5¢), 133.2(s, C4¢), 139.4 (s, C4), 142.3 (d,
JP–C = 1.3 Hz, C2¢), 149.0 (s, C3¢), 153.2 (t, JP–C = 3.1 Hz, C6), 159.1
(t, JP–C = 1.2 Hz, C2); dP (CDCl3) 9.69 (s).
dH (CDCl3, -40 ◦C) 0.99 (d, 9H, JP–H = 11 Hz, P(CH3)3), 1.12 (d,
3H, J = 6.7 Hz, C(CH3)2), 1.19 (d, 3H, J = 6.6 Hz, C(CH3)2), 1.31
(d, 3H, J = 6.9 Hz, C(CH3)2), 1.78 (d, 3H, J = 6.8 Hz, C(CH3)2),
2.53 (s, 3H, NMe2), 2.80 (s, 3H, NMe2), 3.07 (dd, 1H, J = 5.4,
12 Hz, CH2), 3.46 (sep, 1H, J = 7.4 Hz, CH(CH3)2), 3.80 (d, 1H,
J = 12 Hz, CH2), 4.43 (sep, 1H, J = 7.0 Hz, CH(CH3)2), 7.02–7.04
(m, 1H, Ar), 7.12–7.21 (m, 2H, Ar), 7.29–7.38 (m, 2H, Ar), 7.44–
7.50 (m, 2H, Ar); dC (CDCl3, r.t.) 15.6 (d, JP–C = 31 Hz, P(CH3)3),
25.0 (s, CH(CH3)2), 29.2 (s, CH(CH3)2), 48.0 (br, NMe2), 65.0 (d,
JP–C = 1.9 Hz, CH2), 122.7 (s, C3), 123.7 (s, C4), 124.6, 127.1, 129.7,
130.0, 131.9, 145.1 (d, JP–C = 5.3 Hz, Ar), 145.2 (d, JP–C = 6.8 Hz,
=
Ar), 190.5 (d, JP–C = 3.5 Hz, C N); dP (CDCl3, r.t.) -9.08 (s).
Reactions of [Pd(N3)(PMe3)2(C-L4)] (15) with CN–R
(R = 2,6-i-Pr2C6H3) or 2,6-Me2C6H3)
CH2Cl2 (3 cm3) and 2,6-diisopropylphenyl isocyanide (0.246 g,
13.1 mmol) were added to
a Schlenk flask containing
[Pd(N3)(PMe3)2(C-L4)] (10, 0.272g, 0.63 mmol) inthat order. After
stirring for 18 h, the solvent was removed, and then the resulting
residue was solidified with n-hexane : diethyl ether (v/v = 1 : 1). The
resulting solids were filtered off and washed with hexane to give
crude solids. Recrystallization from CH2Cl2–n-hexane gave yellow
4
= =
=
crystals of [Pd(N C N–R)(–C( N–R)(PMe3)(N-L )] (R = 2,6-
-1
= =
i-Pr2C6H3) (26, 0.132 g, 30%). nmax (KBr, cm ) 2130 (N C N);
dH (CDCl3, -40 ◦C) 0.94 (d, 9H, JP–H = 11 Hz, P(CH3)3), 1.09
(d, 3H, J = 6.7 Hz, CH(CH3)2b), 1.18 (dd, 15H, J = 3.3, 6.9 Hz,
CH(CH3)2a+c), 1.30 (d, 3H, J = 6.9 Hz, C(CH3)2c), 1.73 (d, 3H,
J = 6.7 Hz, C(CH3)2b), 2.63 (s, 3H, NMe2), 2.81 (s, 3H, NMe2),
3.06 (dd, 1H, J = 5.6, 12 Hz, CH2), 3.44 (sep, 1H, J = 6.8 Hz,
CHc(CH3)2), 3.63 (sep, 2H, J = 6.8 Hz, CHa(CH3)2), 3.80 (d, 1H,
J = 12 Hz, CH2), 4.40 (sep, 1H, J = 6.8 Hz, CHb(CH3)2), 6.87–
6.92 (m, 1H, Ar), 7.02 (d, 2H, J = 7.4 Hz, Ar), 7.12–7.21 (m, 4H,
Ar), 7.29–7.34 (m, 2H, Ar), 7.45–7.49 (m, 1H, Ar); dC (CDCl3,
r.t.) 16.3 (d, JP–C = 32 Hz, P(CH3)3), 23.5 (s, CH(CH3)2), 25.0
(s, CH(CH3)2), 25.0 (s, CH(CH3)2), 29.2 (s, CH(CH3)2), 48.0 (br,
NMe2), 65.8 (br, CH2), 120.0 (s, C3), 122.4 (s, C4), 123.7, 124.1,
127.0, 129.7, 130.0, 132.1, 141.7, 142,1, 145.5 (d, JP–C = 5.3 Hz),
145.6 (d, JP–C = 6.8 Hz), 165.0 (br); dP (CDCl3, r.t.) -8.37 (s).
The reaction of 25 with 1 equivalent CN–R (R = 2,6-i-
Pr2C6H3) also gave the same product (78%). The obtained product
Reactions of [Pd(l-X)(C,N-L3)]2 or [Pd(l-X)(C,N-L2)]2 (X = N3,
Cl) with 1 equivalent chelating phosphine
CH2Cl2 (90 cm3) and depe (0.075 g, 0.37 mmol) were added
to [Pd(m-N3)(C,N-L3)]2 (0.262 g, 0.37 mmol). An initial red
suspension slowly turned to an orange solution. After stirring for
4 h, the solvent was removed completely, and the resulting residue
was extracted several times with diethyl ether to give dark red
solids of [Pd(C,N-L3)2] (20, 0.159 g, 83%). The remaining white
1
solids were identified by IR and H NMR to be [Pd(N3)2(depe)].
dH (CDCl3) 2.07 (s, 6H, Me), 2.45 (s, 6H, Me), 6.93–7.02 (m, 2H,
Ar), 7.22–7.30 (m, 3H, Ar), 7.92–7.97 (m, 2H, Ar); dC (CDCl3)
20.7 (s, Me), 21.0 (s, Me), 118.2 (s, C8), 123.0 (s, C3), 128.2 (s, C9),
130.3, 131.3, 133.3, 135.5, 136.8, 138.2, 151.6 (s, C7), 153.2 (s, C1),
165.7 (s, C2).
Reactions of [Pd(m-X)(C,N-L2)]2 (X = N3, Cl) with 1 equivalent
depe were analogously carried out to give [Pd(C,N-L2)2] (19, 79%)
and [Pd(depe)Cl2]. The complex 19 could also be prepared from
Hg[C-L2]2 and [Pd(m-Cl)(C,N-L2)]2 with Pd2(dba)3 or 2-lithio-
N,N-dimethylbenzylamine. Analytical and spectroscopic data of
19 coincided with those in the literature.18
1
was identified by spectroscopic (IR and H, 13C and 31P-NMR)
analyses.
Reaction of 10 with CN–R (R = 2,6-Me2C6H3) was analogously
4
= =
=
carried out to give [Pd(N C N–R)(–C( N–R)(PMe3)(N-L )]
-1
= =
(27, 73%). nmax (KBr, cm ) 2117 (N C N); dH (CDCl3, r.t.) 1.01
(d, 9H, JP–H = 11 Hz, P(CH3)3), 2.33 (s, 6H, NMe2), 2.37 (s, 3H,
Me), 2.63 (s, 3H, Me), 2.79 (s, 3H, Me), 3.03 (s, 4H, Me + CH2),
3.86 (br, 1H, CH2), 6.65 (t, 1H, J = 7.4 Hz, Ar), 6.88–6.92 (m,
4H, Ar), 7.09–7.18 (m, 3H, Ar), 7.28 (dt, 1H, J = 1.4, 7.4 Hz, Ar),
Reactions of [Pd(N3)(PMe3)(C,N-L4)] with CN–R
(R = 2,6-i-Pr2C6H3)
To a Schlenk flask containing [Pd(N3)(PMe3)(C,N-L4)] (2, 0.295 g,
0.82 mmol) were added CH2Cl2 (5 cm3) and 2,6-diisopropylphenyl
isocyanide (0.169 g, 0.90 mmol). After stirring for 18 h, the solvent
was removed, and then the resulting residue was solidified with
diethyl ether. The solids were filtered off and washed with hexanes
to give crude solids, which were recrystallized from CH2Cl2–
7.42 (dt, 1H, J = 1.3, 7.4 Hz, Ar); dC (CDCl3, r.t.) 16.2 (d, JP–C
=
32 Hz, P(CH3)3), 19.5 (s, Me), 21.5 (s, Me), 48.4 (br, NMe2), 64.7
(d, J = 16 Hz, -CH2), 119.2 (s, C3), 123.5, 124.0, 127.2, 127.8,
=
129.8, 130.8, 132.1, 144.8, 145.4, 148.3, 188.0 (C N) dP (CDCl3,
r.t.) -7.98 (s).
Reactions of [Pd(N3)(PMe3)2(C-L1)] (6), [Pd(N3)(P(n-Pr)3)2(C-
L2)] (9), and [Pd(N3)(PMe3)2(C-L4)] (10) with R–NCS (R =
i-Pr, (CH3)3Si, C6H4–NCS). To a Schlenk flask containing
[Pd(N3)(PMe3)2(C-L1)] (6, 0.262 g, 0.57 mmol) were added CH2Cl2
=
diethyl ether to give yellow crystals of [Pd(N3)(–C N–C6H3-2,6-i-
Pr2)(PMe3)(N-L4)] (25, 0.305 g, 68%). nmax (KBr, cm-1) 2032 (N3);
6590 | Dalton Trans., 2009, 6578–6592
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©

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(4 cm3) and isopropyl isothiocyanate (0.086 g, 0.85 mmol). After
stirring for 18 h, the reaction mixture was evaporated completely
under vacuum, and then the resulting residue was solidified with
n-hexane. The solids were filtered and washed with hexane (2 ¥
5 cm3). Recrystallization from CH2Cl2–n-hexane gave the white
crystals of trans-{PdS[CN4(R)](C-L1)(PMe3)2} (28, 0.170 g, 53%).
dH (CDCl3) 1.04 (br s, 18H, P(CH3)3), 1.56 (d, 6H, J = 6.8 Hz,
CH(CH3)2), 5.02 (sep, 1H, 6.8 Hz, CH(CH3)2), 7.08 (d, 1H, J =
5.0 Hz, H4¢), 7.10 (ddt, 1H, J = 1.1, 4.8, 9.8 Hz, H5), 7.39 (d, 1H,
J = 4.9 Hz, H5¢), 7.90 (dt, 1H, J = 8.0 Hz, H3), 8.54 (dt, 1H, J =
1.0, 4.3 Hz, H4), 9.72 (br d, 1H, J = 8.0 Hz, H6); dC (CDCl3) 14.0
(t, JP–C = 16 Hz, P(CH3)3), 21.8 (s, CH(CH3)2), 49.6 (s, CH(CH3)2),
120.4 (s, C3), 121.0 (s, C5), 126.5 (s, C5¢), 134.3 (s, C4¢), 137.0 (s, C4),
139.1 (s, C2¢), 143.0 (s, C3¢), 149.1 (s, C6), 154.8 (s, C2); dP (CDCl3)
-15.3 (s).
Acknowledgements
This work was supported by the Korea Research Foundation
Grant funded by the Korean Government (MOEHARD, Basic
Research Promotion Fund) (KRF-2007-521-C00148) and partly
by the NURI-2007 of Gangwon Advanced Materials.
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Complex 29, [Pd(NCS)(P(n-Pr)3)2(C-L2)], was similarly pre-
pared from [Pd(N3)(P(n-Pr)3)2(C-L2)] (9, 0.293 g, 0.50 mmol) and
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General procedure for Suzuki–Miyaura cross-coupling reactions.
To a 13 ¥ 90 mm test tube was added the phenylboronic acid
(31.7 mg, 0.26 mmol), K2CO3 (55.3 mg, 0.4 mmol), Pd catalyst (1 ¥
10-3 mmol, 1 mol%), and aryl halide (0.2 mmol) with a stirring bar.
Toluene (1.0 cm3) was added, and the resulting mixture was heated
in an oil bath at 80 ◦C. The reaction was monitored by TLC. After
the aryl bromide was totally consumed, the reaction mixture was
cooled to room temperature and quenched with brine (1.0 cm3)
and then extracted with EtOAc (3 ¥ 1.0 cm3). The resulting organic
solution was dried over MgSO4 and concentrated on a rotary
evaporator. The crude product was purified by preparation TLC
(0.5 mm).
X-Ray structure determination
X-Ray data of complexes 1, 3, 7, 25, 28 and 29 were collected
with a Siemens P4 diffractometer equipped with a Mo X-ray tube,
except those of complexes 12, 17, 21, and 24 that were collected
with a Bruker Smart APEX2 diffractometer. All calculations were
carried out with the SHELX-97 programs.41 All structures were
solved by direct methods. All non-hydrogen atoms were refined
anisotropically, and all hydrogen atoms were generated in ideal
positions and refined in a riding model.
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The Royal Society of Chemistry 2009
Dalton Trans., 2009, 6578–6592 | 6591
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