Tetracopper(I) phosphonitocavitand: Synthesis, halide anion inclusion and optical nonlinearity

Article abstract of DOI:10.1016/j.molstruc.2005.02.002

Treatment of tetraphosphonitoresorcinarene [(CH₃) ₂CHCH₂CHC₆H₂O₂PPh] ₄ (1) with an excess [CuCl] powder in the presence of pyridine (py) yielded a tetracopper(I) phosphonitocavitand [pyH][1·Cu ₄(μ-Cl)₄(μ₄-Cl)] (2). The Included μ₄-Cl in 2 was easily substituted by heavy halide anion to give [pyH][1·Cu₄(μ-Cl)₄(μ₄-X)] (X=Br, 3; I, 4). The complexes 2, 3, and 4 have been characterized by X-ray structure determinations. The similar structure contains four coplanar cupper atoms bridged by four μ-Cl and one central trapped μ₄-X atoms in the inside of the closing bowl-shaped cavitand. The third-order nonlinear optical properties of 2 as a typical metal-cavitand complex were investigated in this paper.

Full text of DOI:10.1016/j.molstruc.2005.02.002

Journal of Molecular Structure 741 (2005) 129–134
www.elsevier.com/locate/molstruc
Tetracopper(I) phosphonitocavitand: synthesis, halide
anion inclusion and optical nonlinearity
b
c
Qian-Feng Zhanga,b, , Richard D. Adams , Dieter Fenske
*
aDepartment of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan, Anhui 243002, China
bDepartment of Chemistry and Biochemistry and the USC Nanocenter, University of South Carolina, Columbia, SC 29208, USA
c
¨ ¨
Institut fur Anorganische Chemie, Universitat Karlsruhe, 76128 Karlsruhe, Germany
Received 19 January 2005; revised 1 February 2005; accepted 3 February 2005
Available online 9 March 2005
Abstract
Treatment of tetraphosphonitoresorcinarene [(CH3)2CHCH2CHC6H2O2PPh]4 (1) with an excess [CuCl] powder in the presence of
pyridine (py) yielded a tetracopper(I) phosphonitocavitand [pyH][1$Cu4(m-Cl)4(m4-Cl)] (2). The Included m4-Cl in 2 was easily substituted
by heavy halide anion to give [pyH][1$Cu4(m-Cl)4(m4-X)] (XZBr, 3; I, 4). The complexes 2, 3, and 4 have been characterized by X-ray
structure determinations. The similar structure contains four coplanar cupper atoms bridged by four m-Cl and one central trapped m4-X atoms
in the inside of the closing bowl-shaped cavitand. The third-order nonlinear optical properties of 2 as a typical metal-cavitand complex were
investigated in this paper.
q 2005 Elsevier B.V. All rights reserved.
Keywords: Copper(I); Phosphonitocavitand; Crystal structure; Optical nonlinearity; Supramolecular chemistry
1. Introduction
block molecules. Among the several building blocks
employed [8], resorcinarenes and resorcinarene-based
cavitands have proven to be particularly interesting as
multidentate ligands, due to the presence of rigidly
preorganized cavities of molecular dimensions and the
possibility of introducing many different ligand moieties
[9]. Thus, the use of these compounds, properly functiona-
lized at the upper rim, has resulted in the formation
coordination cages and metal complexes with peculiar anion
complexation properties [10].
Supramolecular host–guest complexes constructed from
cone-shaped polyaromatic macrocycles such as calixarenes
and resorcinarenes including the related cavitands have
attracted intensive interests because of their applications in
field as diverse ion sensors, storage, transports, and optical
electronics [1,2]. The host–guest chemistry for shape- and
size-selectivity has also potential application in catalysis
reactions [3]. A recent aspect of this interesting chemistry is
the confinement of molecules within supramolecular
capsules, which are from the assembly of six resorcin[4]-
arenes and pyrogallol[4]arenes, with the cavities of the host
molecules directed inwards [4–6]. The interior of molecular
capsules can be regarded as a ‘new phase of matter’ [7]. A
detailed understanding of the interplay and orientation of
the host and guest molecules is restricted to the building
The functionalized resorcinarene-based molecules as the
multidentate bowl-shaped ligands have been recently used
to coordinate the surface of metal clusters so as to stabilize
the metal cluster and to control the sizes of the resultant
nanometer particles [11]. In particular, the affinity of
thioated and phosphorylated cavitand ligands towards soft
metal ions was demonstrated with the coinage-metal
copper(I), silver(I) and gold(I) [10,12,13]. Puddephatt and
coworkers have studied interactions of tetraphosphinito-
resorcinarene with the coinage-metal CuC, AgC, and AuC
and reported successively a number of tetrametalopho-
sphonitocavitand complexes, in which the metals occupy in
the inside of the closing bowl-shaped cavitand [13–16]. As a
part of our research on the third-order nonlinear
optical properties (NLO) of coinage-metallic complexes
*
Corresponding author. Address: Department of Chemistry and
Chemical Engineering, Anhui University of Technology, Maanshan,
Anhui 243002, China. Tel.: C86 555 2400 551; fax: C86 555 2400 552.
E-mail address: zhangqf@ahut.edu.cn (Q.-F. Zhang).
0022-2860/$ - see front matter q 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2005.02.002

130
Q.-F. Zhang et al. / Journal of Molecular Structure 741 (2005) 129–134
and clusters [17], we are interested to the metal complexes
by the coordination of functional resorcinarene ligands with
coinage-metal atoms. It is expected to find new NLO
materials with super-cage and nano-meteric metal com-
plexes stabilized by functionalized molecular capsules. In
this paper, we report the syntheses, molecular structures
and nonlinear optical properties of tetracopper(I)
phosphonitocavitands.
50.6; H, 4.36; N, 0.83%. Calcd for C73H74NO8P4Cl4-
ICu4$CH3OH: C, 50.1; H, 4.40; N, 0.79%. UV–Vis
(CH2Cl2, nm): 305(s), 318(sh), 451(br). 31P NMR (CDCl3,
ppm): d 118.9 (s, br). MS (FAB): m/z 1661 (4-pyH).
2.2. Crystal structure determination
Single crystals of complexes 2$CH3CN$CH3OH,
3$CH3OH and 4$CH3OH were obtained from the methanol
diffuse into their CH2Cl2 solutions. Each of single crystal
was quickly sealed inside a capillary with mother liquor to
prevent loss solvents in the crystal lattice. X-ray intensity
data were collected on a Bruker SMART APEX 1000 CCD
area-detecting diffractometer equipped with graphite mono-
2. Experimental
2.1. General
All manipulations were conducted using Schlenk tech-
niques under an atmosphere of nitrogen. Phosphonitocavi-
tand [rccc-2,8,14,20-Tetrakis-(iso-butyl)-phosphonito
cavitand (C44H48O8P4Ph4)] (1) was prepared by a modifi-
cation of the literature method [13]. IR spectrum was
measured on a Digilab FTS-40 spectrophotometer. Elec-
tronic spectrum was preformed on an Hitachi U-3410
spectrophotometer. 31P NMR spectrum was recorded on a
Varian Unity-300 spectrometer relative to 85% H3PO4 acid.
Mass spectra were obtained on a Finnigan TSQ-700
spectrometer.
˚
chromated Mo Ka radiation (lZ0.71073 A) by using an u
scan technique at room temperature. The collected frames
were processed with the software SAINT [18]. The data was
corrected for absorption using the program SADABS [19]. The
structure was solved by direct methods using the SHELXTL
software package [20]. All heavy atoms positions (Cu, I, Br,
Cl and P) were revealed on the first refinement. Other
nonhydrogen atoms were located from subsequent differ-
ence Fourier syntheses. The structure was refined by full-
matrix least-squares method on F2. All nonhydrogen atoms
were refined anisotropically. Hydrogen atoms were included
but not refined. The pyridine rings in 3$CH3OH and
4$CH3OH were refined with the bond distance restraint
due to disorders. Further details of the structure analyses are
listed in Table 1. Selected bond lengths and angles of
compounds 2$CH3CN$CH3OH, 3$CH3OH and 4$CH3OH
are given in Table 2.
2.1.1. Synthesis of [pyH][1$Cu4(m-Cl)4(m4-Cl)] (2)
A mixture of excess CuCl powder (100 mg, 1.0 mmol), 1
(170 mg, 0.15 mmol) and py (1.0 ml) in CH2Cl2 (25 ml)
was stirred at room temperature overnight. The resulting
light yellow solution was filtered to remove the unreacted
CuCl. The solvent was pumped off and the residue was
recrystallized from CH2Cl2/MeOH. Needle colorless crys-
tals suitable for X-ray diffraction were obtained for several
days. Yield: 186 mg, 91%. Anal. Found: C, 51.6; H, 4.41; N,
1.49%. Calcd for C73H74NO8P4Cl5Cu4$CH3CN$CH2Cl2: C,
52.4; H, 4.45; N, 1.58%. UV–Vis (CH2Cl2, nm): 292(s),
308(sh), 447(br). 31P NMR (CDCl3, ppm): d 132.7 (s, br).
MS (FAB): m/z 1599 (2-pyH).
2.3. Optical measurements
A CH3CN solution of 7.5!10K3 mol dmK3 of complex
2 was placed in a 1-mm quartz cell for optical measure-
ments. The optical limiting characteristics along with
nonlinear absorption and refraction was investigated with
a linearly polarized laser light (lZ532 nm, pulse widthZ
7 ns) generated from a Q-switched and frequency-doubled
Nd:YAG laser. The spatial profiles of the optical pulses
were nearly Gaussian. The laser beam was focused with a
25-cm focal-length focusing mirror. The radius of the laser
beam waist was measured to be 30G5 mm (half-width at
1/e2 maximum in irradiance). The incident and transmitted
pulse energy were measured simultaneously by two Laser
Precision detectors (RjP-735 energy probes) communicat-
ing to a computer via an IEEE interface [21], while the
incident pulse energy was varied by a Newport Com.
Attenuator. The interval between the laser pulses was
chosen to be 1 s to avoid the influence of thermal and long-
term effects. The details of the set-up can be found
elsewhere [22].
2.1.2. Synthesis of [pyH][1$Cu4(m-Cl)4(m4-Br)] (3)
To a solution of 2 (117 mg, 0.07 mmol) in THF (10 ml)
was added a solution of NaBr (50 mg, 0.49 mmol) in water
(1 ml), and then the mixture was stirred 2 h. The solvent was
pumped off and the residue was washed with MeOH and
Et2O. Recrystallization from CH2Cl2/MeOH gave colorless
crystals in a yield of 76% (89 mg). Anal. Found: C, 51.2; H,
4.47; N, 0.93%. Calcd for C73H74NO8P4Cl4BrCu4$CH3OH:
C, 51.5; H, 4.52; N, 0.81%. UV–Vis (CH2Cl2, nm): 302(s),
316(sh), 445(br). 31P NMR (CDCl3, ppm): d 129.5 (s, br).
MS (FAB): m/z 1614 (3-pyH).
2.1.3. Synthesis of [pyH][1$Cu4(m-Cl)4(m4-I)] (4)
This complex was prepared similarly as for 3 using NaI
(70 mg, 0.47 mmol) in place of NaBr, and recrystallized
from CH2Cl2/MeOH. Yield: 82 mg, 72%. Anal. Found: C,

Q.-F. Zhang et al. / Journal of Molecular Structure 741 (2005) 129–134
131
Table 1
Table 2
˚
Crystal data and structure refinements for 1$CH3CN$CH2Cl2, 2$CH3OH,
and 3$CH3OH
Selected bond lengths (A) and angles (deg) for 1$CH3CN$CH2Cl2,
2$CH3OH, and 3$CH3OH
Compound
1$CH3CN$
CH2Cl2
2$CH3OH
3$CH3OH
XZCl (1)
XZBr (2)
XZI (3)
2.175(4)
Cu(1)–P(1)
Cu(2)–P(2)
Cu(3)–P(3)
Cu(4)–P(4)
Cu(1)–Cl(1)
Cu(1)–Cl(4)
Cu(2)–Cl(1)
Cu(2)–Cl(2)
Cu(3)–Cl(2)
Cu(3)–Cl(3)
Cu(4)–Cl(3)
Cu(4)–Cl(4)
Cu(1)–X
2.169(2)
2.168(2)
2.169(2)
2.170(2)
2.358(2)
2.353(2)
2.347(2)
2.345(2)
2.347(2)
2.349(2)
2.353(2)
2.351(2)
2.551(2)
2.579(2)
2.580(2)
2.557(2)
2.181(4)
2.173(4)
2.177(4)
2.173(4)
2.399(3)
2.399(3)
2.405(3)
2.396(3)
2.383(3)
2.443(3)
2.438(3)
2.390(3)
2.667(2)
2.669(2)
2.645(2)
2.646(2)
Empirical formula
C76H79N2O8-
C74H78NO9P4- C74H78NO9P4-
2.178(4)
2.195(4)
2.192(4)
2.380(5)
2.352(4)
2.355(4)
2.385(5)
2.366(4)
2.534(4)
2.533(4)
2.359(5)
2.773(2)
2.771(2)
2.757(2)
2.755(2)
P4Cl7Cu4
1774.60
Monoclinic
P21/n
Cl4BrCu4
1725.12
Monoclinic
P21/n
Cl4ICu4
1772.11
Monoclinic
P21/n
Formula weight
Crystal system
Space group
˚
a (A)
˚
b (A)
20.711(2)
19.4586(19)
20.766(2)
105.683(2)
8057.3(14)
4
20.8253(18)
19.5146(16)
20.8325(19)
105.695(2)
8150.6(12)
4
20.8459(14)
19.5462(13)
20.8371(12)
105.541(2)
8179.8(9)
4
˚
c (A)
b (deg)
3
˚
Volume (A )
Z
T (K)
173
294
294
Density (calcd)
(g/cm3)
1.463
1.406
1.299
Cu(2)–X
Cu(3)–X
Absorption coeffi-
cient (mmK1
1.406
1.781
1.663
Cu(4)–X
)
P(1)–Cu(1)–Cl(1)
P(1)–Cu(1)–Cl(4)
Cl(4)–Cu(1)–Cl(1)
P(1)–Cu(1)–X
113.55(8)
117.12(8)
104.02(8)
127.79(7)
94.36(7)
95.66(7)
115.41(9)
113.01(8)
107.58(8)
126.32(7)
96.22(7)
95.18(7)
115.28(8)
113.07(8)
107.70(8)
126.33(7)
96.14(7)
95.24(7)
117.19(8)
113.67(8)
104.28(7)
127.42(7)
94.27(7)
95.75(7)
87.78(7)
87.05(7)
87.83(7)
87.56(7)
79.14(6)
78.96(6)
127.19(7)
127.29(7)
78.82(6)
77.54(6)
117.02(13)
113.87(14)
104.49(12)
123.26(12)
97.84(10)
96.99(9)
118.37(17)
114.21(17)
103.99(16)
120.06(12)
98.97(12)
98.07(12)
113.96(17)
118.56(17)
104.12(16)
119.97(12)
99.06(12)
98.04(12)
112.88(17)
112.79(15)
106.81(14)
119.12(12)
99.95(13)
103.85(10)
112.85(17)
112.49(15)
106.92(14)
119.26(13)
99.99(13)
103.94(10)
88.71(14)
87.46(14)
79.43(12)
87.60(14)
72.79(6)
F(000)
3632
3520
3592
q range for data
collection (deg)
Reflections
collected
1.46–25.03
1.46–25.03
1.45–25.03
47485
14221
48633
14371
48708
14428
Cl(4)–Cu(1)–X
Cl(1)–Cu(1)–X
P(2)–Cu(2)–Cl(2)
P(2)–Cu(2)–Cl(1)
Cl(2)–Cu(2)–Cl(1)
P(2)–Cu(2)–X
Independent
reflections
113.91(13)
116.94(14)
104.65(12)
123.45(12)
97.72(10)
96.79(9)
R(int)
0.0735
0.0956
0.1147
Data/restraints/
parameters
Goodness of fit
on F2
14221/6/879
14371/0/834
14428/0/850
Cl(2)–Cu(2)–X
Cl(1)–Cu(2)–X
P(3)–Cu(3)–Cl(2)
P(3)–Cu(3)–Cl(3)
Cl(2)–Cu(3)–Cl(3)
P(3)–Cu(3)–X
0.935
0.979
1.072
111.86(14)
113.89(13)
107.17(12)
123.00(12)
98.69(9)
Final R1a, wR2b
0.0692, 0.
0.0753, 0.
1555, 0.1610,
0.2436
0.0857, 0.
1507, 0.1575,
0.2235
[IO2s(I)] (all data) 1455, 0.1089,
0.1899
Final diff. features
1.058, K0.628 1.176, K0.790 1.558, K1.751
Cl(2)–Cu(3)–X
Cl(3)–Cu(3)–X
P(4)–Cu(4)–Cl(4)
P(4)–Cu(4)–Cl(3)
Cl(4)–Cu(4)–Cl(3)
P(4)–Cu(4)–X
3
˚
(e/A )
100.22(9)
111.94(14)
113.79(13)
107.05(12)
123.07(12)
98.63(10)
100.33(9)
86.76(11)
86.32(11)
82.62(10)
86.17(11)
76.01(6)
P
P
a
R1Z jFojKjFcj= jFoj.
wR2Z
Â
Ã
P
P
1=2
b
2
wðjFo2jKjFc2jÞ = wjFo2j
.
2
3. Results and discussion
Cl(4)–Cu(4)–X
Cl(3)–Cu(4)–X
Cu(2)–Cl(1)–Cu(1)
Cu(2)–Cl(2)–Cu(3)
Cu(3)–Cl(3)–Cu(4)
Cu(4)–Cl(4)–Cu(1)
Cu(1)–X–Cu(4)
Cu(1)–X–Cu(2)
Cu(4)–X–Cu(2)
Cu(1)–X–Cu(3)
Cu(4)–X–Cu(3)
Cu(2)–X–Cu(3)
The bowl-shaped phosphonitocavitand (1) with four PhP
units was easily obtained by treatment of resorcin[4]arene
with phosphonous dichloride PhPCl2 in the presence of
pyridine (py) as base [13]. Similar to silver analogue of
phosphonitocavitand [23], treatment of ligand 1 in CH2Cl2
solution with an excess [CuCl] powder in the presence of py
gave the sole compound tetracopper(I) phosphonitocavitand
[pyH][1$Cu4(m-Cl)4(m4-Cl)] (2) as colorless crystals. Com-
plex 2 can be dissolved in most polar solvents, such as THF,
CH2Cl2 and acetone. Reaction of 2 with NaBr or NaI in THF
solution gave new complex [pyH][1$Cu4(m-Cl)4(m4-X)]
(XZBr, 3; I, 4). The heavy halide BrK and IK substituted
the m4-ClK anion to form the face-bridging m4-Br and m4-I
bindings, respectively. Attempts to replace all the m-Cl
groups by using excess heavy halide resource and long
reaction time failed, indicative of the Cu4(m-Cl)4 having a
fixed crown structure. Thus, the cavity size of the
Cu4(m-Cl)4 crown structure may be optimized for the
76.40(6)
72.82(7)
120.72(7)
120.71(7)
75.04(6)
113.67(6)
113.79(6)
71.95(7)
75.93(6)
72.90(6)
heavy halides inclusion. The 31P NMR resonances for the
complexes 2–4 show a single broad peak downfield from
that of the free ligand 1 (165.7 ppm), and 31P resonances
shift upfield on going from ClK (132.7 ppm) to IK
(118.9 ppm), a trend that can again be ascribed to a smooth
increase in orbital overlap. The reason for this is that the
deshielding effect may result from orbital overlap due to
CuC being a d10 system.

132
Q.-F. Zhang et al. / Journal of Molecular Structure 741 (2005) 129–134
In order to prove the Cu4(m-Cl)4 crown structure with the
halide anion inclusion, the structures of complexes 2, 3, and
4 were clearly confirmed by single crystal X-ray diffraction.
All crystal structures consist of discrete [pyH]C cations and
tetracopper(I) phosphonitocavitands along with the lattice
solvents. The selected structural parameters for these three
complexes are compiled in Table 2 for comparison. The
structure of the anion [1$Cu4(m-Cl)4(m4-Cl)]K in 2 is
shown in Fig. 1 as both top and side views. The structures
of the anions [1$Cu4(m-Cl)4(m4-Br)]K in 3 and [1$Cu4(m-
Cl)4(m4-I)]K in 4 are illustrated in Figs. 2 and 3,
respectively, from side views. The similar structures of
phosphonitocavitand with different cavitand ligands have
been previously reported by Puddephatt [14,15]. As
expected, the tetraphos-phonitocalixarene unit is present
in the bowl-shaped conformation with each phosphorous
bonded to a copper(I) atom. The Cu4(m-Cl)4(m4-X) unit lies
in the inside of the closing bowl-shaped cavitand, of which
the Cu4(m-Cl)4 moiety is arranged in a crown shape around
the bowl rim, the m4-X is trapped inside the bowl center.
Fig. 2. A perspective view of the anion [1$Cu4(m-Cl)4(m4-Br)] in 3 from the
side view. The thermal ellipsoids were drawn at 30% probability level.
The Cu4(m-Cl)4(m4-X) aggregate approximates to C4v
symmetry. Each copper atom is tetrahedrally coordinated,
and the four copper atoms are nearly coplanar with an
˚
average deviation of 0.01 A from the least squares plane.
Distances from the Cu atoms to m-Cl atoms range from
˚
2.351(2) to 2.534(4) A, while the m-Cl–Cu–m-Cl angles
range from 103.99(16) to 107.70(8)8. The average value of
˚
the Cu-m4-Cl interatomic distances is 2.567(2) A; those of
˚
Cu-m4-Br and Cu-m4-I are 2.657(2) and 2.764(2) A,
respectively, which are obviously shorter than those in the
corresponding silver complexes [14,15,23]. The average
bond length of Cu-m4-X increases from ClK to IK, owing to
the increased ionic radii of the halide. A slight difference of
the Cu–P bond distances is also noted in the three
complexes, the average Cu–P bond distances are 2.169(2),
˚
2.176(4) and 2.185(4) A for complexes 2, 3 and 4,
respectively, suggesting that the Cu–P bond interactions
are more or less influenced by the inclusion halide anions.
Fig. 3. A perspective view of the anion [1$Cu4(m-Cl)4(m4-I)] in 4 from the
side view. The thermal ellipsoids were drawn at 30% probability level.
Fig. 1. Perspective view of the anion [1$Cu4(m-Cl)4(m4-Cl)] in 2 with the
ellipsoids drawn at 30% probability level: (a) top view, (b) side view.

Q.-F. Zhang et al. / Journal of Molecular Structure 741 (2005) 129–134
133
The electronic spectra of complexes 2–4 are character-
1.1
1.0
0.9
0.8
0.7
(a)
ized by three absorptions in the 284–496 nm range. The
high energy absorption may be due to the congregation
macrocyclic p-system from phosphonitocavitand ligands.
The strong broad peak may be assigned as the internal P-to-
Cu charge-transfer. The middle broad at ca. 494 nm may be
attributed to metal-to-ligand charge-transfer. The NLO
properties of complex 2 as a representative compound
were investigated by using the Z-scan technique. The
nonlinear absorption component was evaluated under an
open aperture configuration. Theoretical curves of transmit-
tance against the Z-position, Eqs. (1) and (2), were fitted to
the observed Z-scan data
ð
N
2
1
TðZÞ Z
ln½1 CqðzÞꢀeKt dt
(1)
(2)
80
60
40
20
0
20
40
60
80
p1=2qðZÞ
KN
Z (mm)
ð1 KeKa L
Þ
0
1.3
1.2
1.1
1.0
0.9
0.8
0.7
(b)
qðZÞ Z a2IiðZÞ
a0
by varying the effective third-order NLO absorptivity a2
value, where the experimentally measured a0 (linear
absorptivity), L (the optical path of sample) and Ii(Z) (the
on-axis irradiance at Z-position) were adopted. The solid
line in Fig. 4(a) is the theoretical curve calculated with a2Z
1.15!10K13 m/W for the concentrations 7.5!10K3 M for
2 in an acetonitrile solution. The nonlinear refractive
component of 2 was assessed by dividing the normalized
Z-scan data obtained in the close-aperture configuration by
those obtained in the open-aperture configuration. The
nonlinear refractive component plotted with the filled
squares in Fig. 4(b) was assessed by dividing the normalized
Z-scan data obtained under the closed aperture configuration
by the normalized Z-scan data obtained under the open
aperture configuration. The valley and peak occur at about
equal distances from the focus. It can be seen that the
difference in valley–peak positions DZVKP is 9.2 mm and
the difference between normalised transmittance values at
valley and peak positions DTVKPZ0.22 for 2. These results
suggest an effectively weak third-order optical nonlinearity
[24]. The solid curve is an eye guide for comparison where
the effective nonlinear refractivity n2 value estimated
therefore is 3.24!10K14 esu for 2. Comparing the NLO
data of complex 2 with the other reported M(W)/Cu(Ag)/
S(Se) clusters [17,25], it may be seen that the NLO behavior
of complex 2 is slightly inferior to those of polynuclear
clusters. Compared with the analogous silver complex [23],
the copper complex 2 has relatively weak optical limiting
effect. This will make us further to design the synthesis of
polynuclear heavy coinage-metal clusters stabilized by
phosphonitocavitand ligands. Because the formation of
polynuclear clusters with phosphonitocavitands depends
very much on the nature of the phosphine and the resource
of bridging atoms [26], the present metal complexes with
phosphonitocavitand ligands as staring materials may be
used to react with active chalcogenide resources. From these
80
60
40
20
0
20
40
60
80
Z (mm)
Fig. 4. Z-scan data of 7.5!10K3 M of 2 in CH3CN at 532 nm with Io being
1.2!1012 W/m2: (a) collected under the open aperture configuration
showing NLO absorption; (b) obtained by dividing the normalized Z-scan
data obtained under the closed aperture configuration by the normalized Z-
scan data in (a). The solid curves are theoretical fits based on Z-scan
theoretical calculations.
reactions, a variety of structural type polynuclear clusters
may be reasonably predicted. Therefore, further studies are
in progress, which are directed toward the preparations of
polynuclear clusters with phosphonitocavitand ligands so as
to obtain desirable nonlinear optical materials.
4. Supplementary materials
Crystal data (excluding structure factors) for the structures
in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication
nos. CCDC-254328/254329/254330. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/conts/

134
Q.-F. Zhang et al. / Journal of Molecular Structure 741 (2005) 129–134
[10] O.D. Fox, M.G.B. Drew, P.D. Beer, Angew. Chem. Int. Ed. 39
retrieving.html (or from the Cambridge Crystallographic Data
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1223 336 033; or deposit@ccdc.cam.ac.uk).
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Acknowledgements
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This project was supported by the Key Scientific
Research Foundation of State Education Ministry (grant
no. 204067) and Anhui Provincial Natural Science Foun-
dation to QFZ. Dr Q.F. Zhang is grateful to the Alexander
von Humboldt Foundation for the assistance.
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