An imidazole-based P-N bridging ligand and its binuclear copper(I), silver(I) and palladium(I) complexes: Synthesis, characterizations and x-ray structures

Article abstract of DOI:10.1016/S0277-5387(00)00658-6

Reaction of 1-methylimidazole with n-BuLi in tetrahydrofuran at - 78°C followed by addition of chlorodiphenylphosphine afforded a P-N bridging ligand, 2-(diphenylphosphino)-1-methylimidazole (dpim) in good yield. The structure of the ligand was determined by single crystal X-ray analysis. Reaction of a stoichiometric amount of the ligand with [Cu(MeCN)₄]ClO₄ in acetonitrile led to the binuclear complex [Cu₂(μ-dpim)₃(MeCN)] (ClO₄)₂·2CH₃CN (1·2CH₃CN), whose structure was determined by single crystal X-ray analysis. The solid state structure shows that the two copper ions are held by three dpim ligands and the coordination geometry around each metal atom is different, one being three- and the other being four-coordinated. One of the copper ions forms a distorted tetrahedral array with two P and one N atoms from the dpim ligand and an additional N atom from an acetonitrile ligand, whereas the other copper ion is three coordinated with two N and one P atoms from the dpim ligand. The nitrate-bridged polymeric silver(I) complex, {[Ag₂(μ-dpim)₂(NO₃)] (NO₃)}_n (2) was prepared by the reaction of equimolar amounts of the ligand and silver nitrate in methanol and was characterized by IR, NMR and X-ray analysis. The dimeric unit, [Ag₂(μ-dpim)₂], possesses an eight-membered annular core structure with two ligands bridging the two metal ions in a head-to-tail configuration. Two types of nitrate ions are present in 2: One makes an infinite one-dimensional chain by joining the dimeric units through its two oxygen atoms in an anti-anti bridging mode whereas the other is disordered with a half occupancy and is located at the left and right sides of the chain. The dynamic behavior of 2 in acetone was also studied by variable temperature 31P NMR. The binuclear palladium(I) complex [Pd₂Cl₂(dpim)₂] (4) was prepared by a conproportionation reaction between complex [PdCl₂(dpim)₂] (3) and [Pd(dba)²] (dba = dibenzylideneaceton). Only one geometric isomer, probably head-to-tail (HT), was formed in this reaction. Complex 3 was prepared by treating [PdCl₂(PhCN)₂] with two moles of ligand in dichloromethane solution. In this complex the ligand acts as a P-monodentate. In solution it exists as a mixture of cis and trans isomers.

Full text of DOI:10.1016/S0277-5387(00)00658-6

Polyhedron 20 (2001) 627–633
www.elsevier.nl/locate/poly
An imidazole-based P–N bridging ligand and its binuclear
copper(I), silver(I) and palladium(I) complexes:
synthesis, characterizations and X-ray structures
M. Abdul Jalil, Tomokazu Yamada, Shuhei Fujinami, Takaharu Honjo,
Hiroaki Nishikawa *
Department of Chemistry, Faculty of Science, Kanazawa Uni6ersity, Kakuma-machi, Kanazawa 920-1192, Japan
Received 2 October 2000; accepted 7 December 2000
Abstract
Reaction of 1-methylimidazole with n-BuLi in tetrahydrofuran at −78°C followed by addition of chlorodiphenylphosphine
afforded a P–N bridging ligand, 2-(diphenylphosphino)-1-methylimidazole (dpim) in good yield. The structure of the ligand was
determined by single crystal X-ray analysis. Reaction of a stoichiometric amount of the ligand with [Cu(MeCN)4]ClO4 in
acetonitrile led to the binuclear complex [Cu2(m-dpim)3(MeCN)](ClO4)2·2CH3CN (1·2CH3CN), whose structure was determined by
single crystal X-ray analysis. The solid state structure shows that the two copper ions are held by three dpim ligands and the
coordination geometry around each metal atom is different, one being three- and the other being four-coordinated. One of the
copper ions forms a distorted tetrahedral array with two P and one N atoms from the dpim ligand and an additional N atom from
an acetonitrile ligand, whereas the other copper ion is three coordinated with two N and one P atoms from the dpim ligand. The
nitrate-bridged polymeric silver(I) complex, {[Ag2(m-dpim)2(NO3)](NO3)}n (2) was prepared by the reaction of equimolar amounts
of the ligand and silver nitrate in methanol and was characterized by IR, NMR and X-ray analysis. The dimeric unit,
[Ag2(m-dpim)2], possesses an eight-membered annular core structure with two ligands bridging the two metal ions in a head-to-tail
configuration. Two types of nitrate ions are present in 2: one makes an infinite one-dimensional chain by joining the dimeric units
through its two oxygen atoms in an anti–anti bridging mode whereas the other is disordered with a half occupancy and is located
at the left and right sides of the chain. The dynamic behavior of 2 in acetone was also studied by variable temperature 31P NMR.
The binuclear palladium(I) complex [Pd2Cl2(dpim)2] (4) was prepared by a conproportionation reaction between complex
[PdCl2(dpim)2] (3) and [Pd(dba)2] (dba=dibenzylideneaceton). Only one geometric isomer, probably head-to-tail (HT), was
formed in this reaction. Complex 3 was prepared by treating [PdCl2(PhCN)2] with two moles of ligand in dichloromethane
solution. In this complex the ligand acts as a P-monodentate. In solution it exists as a mixture of cis and trans isomers. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: Hybrid ligands; Binuclear complexes; Copper; Silver; Palladium
1. Introduction
which both metals participate simultaneously to give a
new substrate reactivity [2,3]. For these reasons, such
bimetallic systems are interesting for their potential
applications in catalysis [4]. The ligands bis-
In recent years there has been great interest in binu-
clear complexes where two metal ions are held in close
proximity [1]. These bimetallic complexes in some cases
exhibit unusual and unexpected structures and react
with unsaturated and small molecules by a process in
(diphenylphosphino)methane
(dppm)
and
2-
(diphenylphosphino)pyridine (dppy) are frequently used
to prepare binuclear complexes. The binuclear transi-
tion metal complexes of the latter unsymmetric and
rigid dppy ligand have been the focus of much investi-
gation in the last few years because of the novel struc-
tural and reactive features of these complexes. In
addition to a large number of binuclear complexes [5],
* Corresponding author. Tel.: +81-762-645703; Fax: +81-762-
645742.
E-mail address: nisikawa@cacheibm.s.kanazawa-u.ac.jp (H.
Nishikawa).
0277-5387/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0277-5387(00)00658-6

628
M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
several mononuclear species [6] as well as clusters [7]
and oligomers [8] have also been reported. The ligand
can act also as a P-monodentate [9] and PN-chelate
[6a,c]. Some catalytic reactions of these complexes in-
cluding hydrogenation [3], hydroformylation [5,10] and
carbonylation [11] have also been investigated.
2. Results and discussion
2.1. Synthesis of the ligand
The ligand was prepared conveniently using the one-
pot reaction outlined in Scheme 1. Lithiation of 1-
methylimidazole at its 2-position by n-BuLi followed by
addition of an equimolar amount of chlorodiphenyl-
phosphine afforded the ligand in fairly good yield
(:75%). Recrystallization from diethylether–hexane
afforded analytically pure colorless crystals.
Although, the compound is known, the preparative
method is different and needs a long reaction time [14].
Furthermore, the coordination chemistry of the com-
pound is totally unexplored. The present synthetic
method is very simple and convenient. In the previous
paper complete analytical data were not given and the
reported melting point (80–82°C) is significantly differ-
ent from the present value (58–60°C). We have charac-
terized the compound fully by elemental analysis, NMR
spectroscopies and single crystal X-ray analysis. The
ORTEP view of the molecular structure of dpim is
depicted in Fig. 1 and selected bond distances and
angles are listed in Table 1.
It is well established that the properties and catalytic
activities of complexes of phosphine ligands often vary
considerably depending upon the nature of the ligands.
Since dppy has proven to be a useful bridging ligand, it
is important to develop new such P–N bridging ligands
containing other N-heterocycles. In this context 1-
methylimidazole would be an excellent candidate which
has been found to be a better p-donor and poorer
p-acceptor ligand compared to pyridine [12]. E and C
values for 1-methylimidazole suggest that it is a
stronger base than pyridine with ‘softer’ properties [13].
Furthermore, imidazole has great biological impor-
tance. Herein we report a P–N bridging ligand contain-
ing an imidazole donor, 2-(diphenylphosphino)-1-
methylimidazole (dpim) and some binuclear complexes.
Because of its similarity to the dppy ligand, it should be
capable of substitution for dppy in any of the numerous
complexes of this popular ligand.
,
The P–C(Ph) distances (1.829(3) and 1.831(3) A for
C5 and C11 respectively) are very similar to those for
dppy [1.824(2) and 1.824(2)] [15]. However, the P–
,
C(im) bond distance [1.822(2) A] is slightly shorter than
,
the P–C(py) distance [1.837(3) A] of dppy. The ob-
,
served bite distance for dpim is about 2.841 A whereas
it is about 2.648 A for dppy. Although the bite distance
,
Scheme 1.
of the present ligand is slightly longer than that of
dppy, we found the ligand is more effective, in some
cases, at holding two metal ions in close proximity
compared to dppy (vide infra).
2.2. Synthesis and characterization of complexes
The syntheses of the complexes are shown in Eqs.
(1)–(4).
Fig. 1. An ORTEP view of the molecular structure of the ligand dpim.
Table 1
(1)
,
Selected bond distances (A) and angles (°) for the ligand dpim
Bond distances
P1–C3
P1–C5
P1–C11
1.822(2)
1.829(3)
1.831(3)
N1–C3
N1–C4
N2–C3
1.365(3)
1.461(3)
1.324(3)
Bond angles
C3–P1–C5
C3–P1–C11
104.1(1)
100.3(1)
C5–P1–C11
P1–C3–N2
101.8(1)
128.5(2)
(2)

M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
629
(4)
The copper(I) complex [Cu2(m-dpim)3(MeCN)][ClO4]2
(1) was prepared by treating an acetonitrile solution of
[Cu(MeCN)4]ClO4 with dpim (2:3 molar ratio) at 40–
45°C for 3 h. Addition of diethylether to the reaction
mixture gives the complex as a white powder. In the
complex both nitrogen and phosphorus atoms of the
ligand are coordinated, as shown by significant
downfield shifts of the H4 proton and 31P resonances
compared to those in the free ligand. The relatively
large chemical shift observed for the H4 proton in
complexes compared to the free ligand probably results
from its proximity to the nitrogen donor atom; this
proton would be expected to experience the strongest
s-effect. The structure of 1·2CH3CN was determined
by single crystal X-ray analysis. An ORTEP view of the
complex cation is depicted in Fig. 2; selected bond
distances and angles are listed in Table 2.
The X-ray structure of 1·2CH3CN comprises two
copper ions bridged by three dpim ligands, where the
coordination geometry around each metal atom is dif-
ferent, one being three- and the other four-coordinated.
This structural type with higher number of bridging
ligands is a rare example, probably due to the extensive
crowding around the metal centers. The dppy ligand
Fig. 2. An ORTEP view of the cation of 1·2MeCN. All phenyl rings
and hydrogen atoms are omitted for clarity.
Table 2
,
Selected bond distances (A) and angles (°) for 1·2CH3CN
Bond distances
Cu1–P1
Cu1–N5
Cu2–P3
Cu2–N3
P1–C5
P2–C19
P2–C27
P3–C37
N7–C49
2.272(1)
2.041(3)
2.197(1)
1.974(3)
1.830(4)
1.801(4)
1.826(4)
1.829(4)
1.132(5)
Cu1–P2
Cu1–N7
Cu2–N1
P1–C3
P1–C11
P2–C21
P3–C35
P3–C43
C49–C50
2.278(1)
2.101(4)
2.006(3)
1.796(4)
1.836(4)
1.822(4)
1.802(4)
1.817(4)
1.453(7)
Bond angles
P1–Cu1–P2
P1–Cu1–N7
P2–Cu1–N7
P3–Cu2–N1
N1–Cu2–N3
Cu1–P1–C5
C3–P1–C5
C5–P1–C11
Cu1–P2–C21
C19–P2–C21
C21–P2–C27
Cu2–P3–C37
C35–P3–C37
Cu1–N7–C49
also forms
a similar type of complex, [Cu2(m-
124.31(4)
99.79(10)
95.40(10)
112.75(9)
115.7(1)
113.7(1)
100.4(2)
106.1(2)
112.3(1)
102.1(2)
107.8(2)
118.8(1)
100.9(2)
164.7(3)
P1–Cu1–N5
P2–Cu1–N5
N5–Cu1–N7
P3–Cu2–N3
Cu1–P1–C3
Cu1–P1–C11
C3–P1–C11
Cu1–P2–C19
Cu1–P2–C27
C19–P2–C27
Cu2–P3–C35
Cu2–P3–C43
C35–P3–C43
N7–C49–C50
117.54(9)
113.14(9)
97.1(1)
dppy)3(MeCN)][BF4]2, in which trigonal planar coordi-
nation of one copper atom and distorted tetrahedral
coordination of the other copper atom are observed
[16]. In 1·2CH3CN Cu1 forms a distorted tetrahedral
array with two P and one N atoms from the dpim
ligand and an additional N atom from an acetonitrile
ligand. The other Cu atom, Cu2, is three coordinated
with two N and one P atoms from the dpim ligand. The
Cu–P and Cu–N bond distances of four coordinated
copper are longer than those of the three coordinated
copper [Cu1–P1 2.272(1), Cu1–P2 2.278(1) and Cu2–
P3 2.197(1); Cu1–N5 2.041(3), Cu2–N1 2.006(3) and
130.22(10)
116.2(1)
114.8(1)
104.1(2)
119.3(1)
110.3(1)
104.3(2)
111.5(1)
109.8(1)
106.4(2)
178.6(5)
,
Cu2–N3 1.974(3) A]. All of these bond distances are
very similar to those of the dppy complex. The acetoni-
trile is coordinated to Cu1 in a bent fashion, as indi-
cated by the Cu1–N7–C49 angle of 164.7(3)° with a
,
Cu1–N7 distance of 2.101(4) A. The Cu···Cu separa-
,
tion (2.875(1) A) is considerably longer than that of the
,
dppy analog [2.721(3) A].
The polymeric silver(I) complex {[Ag2(m-dpim)2-
(NO3)](NO3)}n (2) was prepared by refluxing an
equimolar amount of silver nitrate and the dpim ligand
in methanol for 1 h. The complex was precipitated out
as colorless crystals when the reaction mixture was
(3)

630
M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
Fig. 3. ORTEP drawing showing the chain structure of 2. All phenyl rings and hydrogen atoms are omitted for clarity.
allowed to cool at ambient temperature. The structure
was determined by single crystal X-ray analysis. The
X-ray analysis reveals that the complex has a nitrate
bridged polymeric chain structure consisting of binu-
clear {Ag2(m-dpim)2} units having a crystallographic Ci
symmetry (Fig. 3). Selected bond distances and angles
are listed in Table 3.
In the basic binuclear unit, two silver atoms are
doubly bridged by two dpim ligands in a head-to-tail
configuration. As shown in Fig. 3, two kinds of nitrate
anions are present in 2: one makes an infinite polymeric
chain by connecting the binuclear units in an anti–anti
bridging mode through its two oxygen atoms [Ag–O=
as bridges through P and N atoms in a head-to-tail
configuration, while the third ligand is coordinated to
only one silver ion through its P donor [18].
Variable temperature 31P NMR of 2 in acetone indi-
cates a ligand exchange process involving dissociation
of Ag–P bonds [19]. Selected 31P NMR spectra are
presented in Fig. 4. At 296 K no 31P resonance of 2 was
observed. At 273 K two broad signals were observed at
about 2.3 and 6.3 ppm. However, a resolved spectrum
centered at 5.28 ppm was obtained at 213 K.
The spectrum arises from the superposition of three
different spin systems attributable to the isotopomers
[
107Ag2(m-dpim)2]2+, [109Ag2(m-dpim)2]2+ and [107Ag-
109Ag(m-dpim)2]2+. The observed coupling constants
for 107Ag–P and 109Ag–P are 623 and 696 Hz, respec-
tively; these values are considerably higher than those
usually observed in silver–phosphine complexes. How-
ever, the ratio of the 31P–Ag coupling constants (1.146)
is very close to the ratio of the nuclear magnetic
moments of the two metal isotopes.
,
2.64(2) A], while the other is disordered with a half
occupancy and located at the left and right sides of the
chain. Each silver atom is tricoordinated in a distorted
trigonal fashion. The structural features of 2 are quite
different from those of the dppy silver complex
[Ag2(NO3)2(m-dppy)2] [17]. The dppy afforded a dinu-
clear complex in which each silver ion is tetracoordi-
nated in a distorted tetrahedral fashion and both of the
nitrate ions are coordinated to a silver ion in a chelat-
The binuclear palladium complex Pd2Cl2(dpim-P)2
(4) was prepared by the conproportionation reaction
,
ing fashion (Ag–O 2.57 and 2.58 A). In spite of the
longer bite distance of dpim compared to dppy, the
Table 3
,
Ag···Ag separation of 2 [2.918(3) A] is significantly
,
Selected bond distances (A) and angles (°) for 2
,
shorter than that of the dppy complex (3.146 A). How-
Bond distances
ever, the Ag–P and Ag–N bond distances of 2
Ag1–P1
Ag1–O2
O1–N3
2.391(3)
2.64(1)
1.23(2)
Ag1–N1
P1–C3
O2–N3
2.214(9)
1.82(1)
1.25(1)
,
[2.391(3) and 2.214(9) A, respectively] are not signifi-
cantly different from those of the dppy complex
,
[2.378(2) and 2.234(6) A, respectively]. The Ag···Ag
Bond angles
P1–Ag1–N1%
O2–Ag1–N1%
separation of 2 is also significantly shorter than that of
156.1(3)
92.5(4)
P1–Ag1–O2
Ag1–P1–C3
111.2(3)
109.6(4)
1
,
[Ag2(h -dppy)(m-dppy)2][ClO4]2 [3.072(1) A] where the
silver ions are held together by two dppy ligands acting

M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
631
copper(I) complex and a nitrate-bridged polymeric sil-
ver(I) complex have been synthesized and characterized
by single crystal X-ray analyses. A binuclear palladi-
um(I) complex has also been prepared. It is found that
in some cases the ligand afforded different types of
complexes from the dppy ligand under the same reac-
tion conditions. The present ligand may able to provide
a very good opportunity to compare its chemistry with
that of the widely used dppy ligand. Syntheses of other
homo- and heterobinuclear complexes of dpim are in
progress.
4. Experimental
4.1. Methods
Fig. 4. Selected 31P NMR spectra of 2 in acetone-d6 at various
temperatures.
All reactions were carried out in oven-dried glass-
ware under an atmosphere of N2 gas. Anhydrous sol-
vents used in reactions were either purchased in
anhydrous form or distilled prior to use (THF from
sodium benzophenone). [Cu(MeCN)4]ClO4 [21],
PdCl2(PhCN)2 [22], and Pd(dba)2 [23] were prepared
according to published procedures. All chemicals were
reagent grade and were used as received. The organic
phase from all liquid–liquid extraction was dried over
anhydrous Na2SO4. Caution! Perchlorate salts of metal
complexes with organic ligands are potentially explosive
and should be handled only in small quantities with
appropriate precautions.
between Pd(II) and Pd(0) complexes. This method has
proven to be useful for the preparation of dimeric
Pd(I), Pt(I), and Rh(I) complexes of the dppy ligand.
Thus treatment of PdCl2(dpim)2 (3) with Pd(dba)2 in
dichloromethane solution produced 4 in 62% yield. The
31P NMR spectrum of this complex consists of a single
peak at l=7.60 indicating the presence of one isomer
either head-to-tail or head-to-head. The spectroscopic
data do not distinguish between head-to-tail and head-
to-head orientations of the dpim ligand. However, the
head-to-tail structure is more likely since the Ag(I)
complex 2 has been shown to have this orientation.
Complex 4 does not give any ring opening product or
A-frame complex with small organic molecules such as
CO. However, the dppy-bridged palladium complex
gives ring opening products with CO [20]. This observa-
tion suggests that imidazolyl nitrogen is more strongly
bound with the metal ion than pyridine nitrogen.
The P-bonded mononuclear palladium complex
PdCl2(dpim)2 (3) was prepared by the reaction of
PdCl2(PhCN)2 with two moles of dpim in dichloro-
methane followed by precipitation with diethyl ether. In
solution this compound is a non-electrolyte. Its 31P
NMR spectrum in CDCl3 consists of two resonances at
77.52 and 79.50 with relative intensities 1:7 respectively.
Thus in solution it exists as a mixture of cis and trans
isomers.
4.2. Instruments
All NMR spectra were recorded with a JEOL JMTC
1
400 MHz spectrometer and are reported in l units. H
spectra were referenced to TMS and 31P spectra were
referenced to 85% H3PO4 as an external standard.
Elemental analyses were performed by the Faculty of
Pharmaceutical Science, Kanazawa University. X-ray
measurements were made on a Rigaku AFC7R diffrac-
tometer or Rigaku Raxis IV imaging plate area
detector.
4.3. Preparations
4.3.1. 2-(diphenylphosphino)-1-methylimidazole (dpim)
To a stirred solution of 1-methyl imidazole (50
mmol, 4 ml) in THF (100 ml), n-butyllithium (1.5 M,
50 mmol, 33.5 ml) was added at −78°C. After 1 h
chlorodiphenylphosphine (50 mmol, 9 ml) was added
slowly via a syringe and the reaction mixture was
stirred for 6 h at ambient temperature. After removing
THF, diethylether and water were added and the or-
ganic layer was collected. The solvent was removed by
evaporation and then hexane was added to afford an
oily solid precipitation. Recrystallization of the oily
3. Conclusion
A convenient synthesis of an imidazole based P–N
bridging ligand has been carried out. The ligand is
found to be very effective at bridging two metal ions in
close proximity and is able to give stable bimetallic
complexes. A rare type of triply bridged binuclear

632
M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
solid from diethylether–hexane gave the analytically
pure ligand as colorless crystals (10.30 g, 75%), m.p.
58–60°C (literature m.p. 80–82°C). Anal. Calc. for
C16H15N2P: C, 72.17; H, 5.68; N, 10.52. Found: C,
out. Recrystallization of this precipitation from hot
methanol yielded pure colorless crystals (0.35 g, 80%).
Anal. Calc. for Ag2C32H30N6P2O6: C, 44.06; H, 3.46; N,
1
9.63. Found: C, 43.62; H, 3.77; N, 9.34%. H NMR
1
71.90; H, 5.78; N, 10.29%. H NMR (CDCl3) l=3.73
(acetone-d6) l=3.18 (s, 6H, N–CH3), 7.15 (d, 2H, H5),
7.59 (d, 2H, H4) 7.45–7.52 (m, 20H, Ph). 31P NMR
(acetone-d6, 213 K) l=5.28 (m).
(s, 3H, N–CH3), 7.04 (d, 1H, H5), 7.24 (d, 1H, H4),
7.32–7.44 (m, 10H, Ph). 31P NMR (CDCl3, 296 K)
l= −31.21 (s).
4.3.4. PdCl2(dpim)2·CH2Cl2 (3·CH2Cl2)
A dichloromethane solution (10 ml) of PdCl2(PhCN)2
(0.38 g, 1 mmol) was added dropwise to a solution of
dpim (0.53 g, 2 mmol) in dichloromethane (20 ml) and
stirred for 2 h. Very faint yellow crystals were precipi-
tated by the dropwise addition of diethylether. The
crystals were collected, washed with diethylether and
vacuum dried (0.62 g, 78%). Anal. Calc. for
PdC32H30N4P2Cl2·CH2Cl2: C, 49.87; H, 4.06; N, 7.05.
4.3.2. [Cu2(dpim)3(MeCN)][ClO4]2·H2O·0.5MeCN
(1·H2O·0.5MeCN)
A mixture of [Cu(NCMe)4]ClO4 (0.33 g, 1 mmol) and
dpim ligand (0.40 g, 1.5 mmol,) was stirred in acetoni-
trile (50 ml) under mild heating (40–45°C) for 3 h. The
resultant solution was concentrated under vacuum and
diethylether was added to give a solid which was col-
lected and washed with methanol and dried under
vacuum (0.5 g, 83%). Anal. Calc. for Cu2C50H48N7-
P3Cl2O8·H2O·0.5MeCN: C, 50.85; H, 4.30; N, 8.72.
1
Found: C, 50.07; H, 4.45; N, 7.30%. H NMR (CDCl3)
l=3.70 (s, 6H, N–CH3), 6.73–7.96 (m, 24H, Ph, H4
and H5). 31P NMR (CDCl3) l=77.52 and 79.50 (s).
1
Found: C, 50.54; H, 4.30; N, 9.08%. H NMR (CDCl3,
273 K) l=2.92 (s, 3H, MeCN), 3.14 (s, 9H, N–CH3),
6.65–7.69 (m, 36H, Ph and Im). 31P NMR (CDCl3, 273
K) l= −18.65 (s, 1P), −13.71 (s, 2P).
4.3.5. Pd2Cl2(dpim)2·2H2O (4·2H2O)
A blood red solution of Pd(dba)2 (0.28 g, 0.5 mmol)
in dichloromethane (20 ml) was added to a solution of
PdCl2(dpim)2 (0.35 g, 0.5 mmol) in dichloromethane (20
ml) and the mixture was refluxed for 2 h. The resultant
solution was then filtered while hot and the filtrate was
evaporated to approximately 5 ml under reduced pres-
sure. The resultant precipitate was collected by filtra-
tion, washed with ethanol and dried in vacuo (0.26 g,
62%). Anal. Calc. for Pd2C32H30N4P2Cl2·2H2O: C,
45.09; H, 4.02; N, 6.57. Found: C, 45.55; H, 3.59; N,
6.53%. 1H NMR (CDCl3) l=3.01 (s, 6H, N–CH3),
6.90 (d, 2H, H5), 7.35–7.72 (m, 20H, Ph), 8.04 (d, 2H,
H4). 31P NMR (CDCl3) l=7.60 (s).
4.3.3. {[Ag2(dpim)2(NO3)](NO3)}n
The ligand dpim (0.27 g, 1 mmol) and AgNO3 (0.17
g, 1 mmol) in methanol (80 ml) were refluxed in the
dark for 1 h. Upon concentrating the resultant solution
under vacuum an off-white product was precipitated
Table 4
Crystallographic data of the ligand and complexes 1·2CH3CN and 2
dpim
1·2CH3CN
2
Formula
C16H15N2P
266.28
Cu2C54H54N9- Ag2C32H30N6-
P3Cl2O8
1248.00
P2O6
872.31
Formula
weight
4.4. X-ray crystallographic studies
Crystal
0.20×0.20
×0.50
0.60×0.15
×0.10
0.30×0.10
×0.50
All crystallographic data for the ligand and com-
plexes are listed in Table 4. Crystals of the ligand dpim
for X-ray diffraction study were grown from ether–
hexane solution during recrystallization, while crystals
of the complex 1·2CH3CN were grown by slow diffu-
sion of diethylether in acetonitrile solution of complex 1
at −5°C. Crystals of the complex 2 for X-ray diffrac-
tion study were obtained by keeping hot methanol–ace-
tone solution at room temperature (r.t.). All
measurements of the ligand dpim and 2 were performed
on a Rigaku AFC7R diffractometer using graphite-
dimension
(mm)
Crystal system monoclinic
Space group
Unit cell dimensions
monoclinic
monoclinic
P21/c (no. 14) P21/c (no. 14) P2/c (no. 13)
,
a (A)
13.283(2)
9.917(2)
10.864(3)
93.59(2)
1428.3(4)
4
14.215(2)
24.872(6)
16.093(3)
91.610(9)
5687(1)
4
13.814(4)
9.338(2)
14.974(4)
116.21(2)
1733.0(7)
2
,
b (A)
,
c (A)
i (°)
3
,
U (A )
Z
v(Mo Ka)
1.80
9.87
12.71
(cm−1
)
,
monochromated Mo Ka radiation (u=0.71070 A) at
T (°C)
Reflections
(total)
Reflections
(unique)
Rint
23.0
3651
−120.0
8467
23
4382
23°C. The data were collected using an ꢀ–2q scan
technique to a maximum 2q value of 55° at a scan
speed of 8.0° min−1 and 12.0° min−1 (in ꢀ) for the
ligand and 2 respectively. The weak reflections (IB
10.0|(I)) were rescanned (maximum of five scans) and
the counts were accumulated to ensure good counting
3476
4224
0.017
0.038; 0.059
0.053
0.079; 0.123
R; Rw
0.039; 0.054

M. Abdul Jalil et al. / Polyhedron 20 (2001) 627–633
633
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statistics. Stationary background counts were recorded
on each side of the reflection.
[4] A.R. Sanger, in: L.H. Pignolet (Ed.), Homogeneous Catalysis with
Metal Phosphine Complexes, Plenum Press, New York, 1983, p.
216
Since the crystals of 1·2CH3CN were efflorescent, an
appropriate crystal was picked up on a cold copper
plate cooled by liquid nitrogen (approximately −80°C)
and mounted on a glass rod. The measurement was
carried out by a Rigaku RAXIS-IV imaging plate area
detector using graphite monochromated Mo Ka radia-
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tion (u=0.71070 A) at −120°C. The crystal–detector
distance was 120 mm. In order to determine the cell
constants and the orientation matrix, three oscillation
photographs were taken with oscillation angle 2° and
exposure time 7 min for each frame. Intensity data were
collected by taking oscillation photographs (total oscil-
lation range 100°; 50 frames; oscillation angle 2°; expo-
sure time 10 min).
The structure of the ligand was solved by Patterson
methods whereas structures of 1·2CH3CN and 2 were
solved by SHELX 86 and SIR 92 respectively and ex-
panded using Fourier technique. All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms
were included in the structure factor calculation but not
refined. All calculations were performed using the
TEXAN crystallographic software package of Molecular
Structure Corporation.
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5. Supplementary material
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Center as supplementary publication Nos. CCDC-
149992 (ligand dpim), CCDC-149993 (1·2CH3CN) and
CCDC-149994 (2). Copies of the data can be obtained
free of charge on application to The Director, CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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Acknowledgements
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The authors thank Professor M. Suzuki for stimulat-
ing discussion. This work was supported by Sasakawa
Scientific Research Grant from The Japan Science
Society.
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