Synthesis, structure and electronic spectra of new three-coordinated copper(I) complexes with tricyclohexylphosphine and diimine ligands

Article abstract of DOI:10.1016/j.ica.2009.10.010

Three new copper(I) complexes with tricyclohexylphosphine (PCy₃) and different diimine ligands, [Cu(phen)(PCy₃)]BF₄ (1) (phen = 1,10′-phennanthroline), [Cu(bpy)(PCy₃)₂]BF₄ (2) (bpy = 2,2′-b

Full text of DOI:10.1016/j.ica.2009.10.010

Inorganica Chimica Acta 363 (2010) 15–19
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis, structure and electronic spectra of new three-coordinated copper(I)
complexes with tricyclohexylphosphine and diimine ligands
b
b
b,
Zhong-Wei Wang a, Qian-Yong Cao b, , Xin Huang , Sen Lin , Xi-Cun Gao
*
*
a School of Material Science and Engineering, Shandong University of Science and Technology, Qingdao 266555, China
b Department of Chemistry, Nanchang University, Nanchang 330031, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Three new copper(I) complexes with tricyclohexylphosphine (PCy3) and different diimine ligands,
[Cu(phen)(PCy3)]BF4 (1) (phen = 1,100-phennanthroline), [Cu(bpy)(PCy3)2]BF4 (2) (bpy = 2,20-bipyridine)
and [Cu(MeO-CNN)(PCy3)]BF4 (3) (MeO-CNN = 6-(4-methoxyl)phenyl-2,20-bipyridine), have been syn-
thesized and characterized. X-ray structure reveals that complexes 1 and 3 are three-coordinated with
trigonal geometry, while complex 2 adopts distorted tetrahedron geometry. Complexes 1 and 3 exhibit
ligand redistribution reactions in chloromethane solution by addition of excess amount of PCy3, in which
three-coordinated 1 changes into four-coordinated [Cu(phen)(PCy3)2]+, and 3 leads to form [Cu(P-
Cy3)2]BF4 and CNN-OMe. All the three complexes display yellow 3MLCT emissions in solid state at room
temperature with kmax at 558, 564 and 582 nm for 1, 2 and 3, respectively, and red-shift to 605, 628 and
643 nm at 77 K in dichloromethane solution.
Received 25 June 2009
Accepted 15 October 2009
Available online 21 October 2009
Keywords:
Copper(I) complexes
Diimine
Phosphine
Photophysical properties
Crystal structures
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
[Cu(MeO-CNN)(PCy3)]BF4 (3). Their structures and spectroscopic
properties were also investigated.
Copper(I) complexes with diimine chelate ligands have at-
tracted much attention for their low-lying charge-transfer (CT) ex-
cited states, and potential applications in electrochemical devices
and in solar energy conversion schemes [1–6]. However, these
complexes often show weak and short-lived excited states for geo-
metric relaxation as well as solvent attack. Incorporating of ancil-
lary sterical phosphine ligands may solve these problems. For
this reason, a series of mixed-ligand copper(I) complexes contain-
ing diimine and phosphine ligands have been synthesized [7–14].
Some of these complexes show strong and ling-lived excited state
[10], and are used as electrophosphorescent materials in organic
light-emitting diodes (OLEDs) [11–12]. But until now most of the
ancillary ligands are limited in phenyl-substituted phosphines. Re-
lated studies on bulky cyclohexyl-substituted phosphine ligands
such as tricyclohexylphosphine (PCy3) are rare. Because of its bulky
steric effect, copper(I) complexes containing PCy3 often have lower
co-ordination numbers as compared with those of PPh3 [15–16].
Their photophysical properties are also different correspondingly.
Herein, we successfully designed and obtained three new mixed-
ligand copper(I) complexes with PCy3 and different
diimine ligands, [Cu(phen)(PCy3)]BF4 (1), [Cu(bpy)(PCy3)2]BF4 (2),
2. Experimental
2.1. Materials and reagents
All reactions were performed under a dinitrogen atmosphere.
Solvents were distilled by standard techniques and saturated with
dinitrogen before use. [Cu(CH3CN)4]BF4 and ligand MeO-CNN were
prepared by literature method [17–18].
2.2. Synthesis
2.2.1. Synthesis of [Cu(phen)(PCy3)]BF4 (1)
A mixture of [Cu(CH3CN)4]BF4 (100 mg, 0.32 mmol) and phen
(58 mg, 0.32 mmol) in dichloromethane (20 mL) was stirred under
nitrogen atmosphere at room temperature for 2 h. Then PCy3
(179 mg, 0.64 mmol) was added kept stirring for 2 h. The solvents
were removed and the solid residue was afforded. Yellow single
crystals suitable for X-ray diffraction were obtained from the solu-
tion of dichloromethane by vapor diffusion with diethyl ether.
Yield: 183 mg (82%). Anal. Calc. for C31H43BCl2CuF4N2P (1ꢀCH2Cl2,
695.90): C, 53.50; H, 6.23; N, 4.03. Found: C, 52.12; H, 56.69; N,
4.28%. 1H NMR (400 MHz, CDCl3): 8.70 (m, 2H), 8.55 (m, 2H),
8.02 (s, 2H), 7.75 (m, 2H), 5.27 (s, 2H), 1.46–1.70 (m, 17H), 1.18
(s, 16H).
* Corresponding authors. Tel.: +86 791 3969252; fax: +86 791 3969386 (Q.-Y.
Cao).
E-mail addresses: cqyong@ncu.edu.cn (Q.-Y. Cao), xcgao@ncu.edu.cn (X.-C. Gao).
0020-1693/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.10.010

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Z.-W. Wang et al. / Inorganica Chimica Acta 363 (2010) 15–19
2.2.2. Synthesis of [Cu(bpy)(PCy3)2]BF4 (2)
by full-matrix least squares on F2 using the SHELXL 97 [21] program
Complex 2 was prepared in a similar way to complex 1 except
that bpy was used in place of phen. The yellow crystals were ob-
tained suitable for X-ray diffraction. Yield: 78%. Anal. Calc. for
C46H74BCuF4N2P2 (867.36): C, 63.70; H, 8.60; N, 3.23. Found: C,
63.98; H, 8.21; N, 3.61%. 1H NMR (400 MHz, CDCl3): d 8.50 (d,
J = 9.0 Hz, 2H), 8.26 (d, J = 5.4 Hz, 2H), 8.11 (m, 2H), 7.30 (m, 2H),
1.50ꢁ1.72 (m, 34H), 1.20 (s, 32H).
package. The non-hydrogen atoms were refined anisotropically.
3. Result and discussion
3.1. Synthesis and crystal structures
Copper complexes were prepared by reaction different diimine
ligands with [Cu(CH3CN)4]BF4 and PCy3 in dry dichloromethane
under N2 atmosphere in a 1:1:2 stoichiometry. The reaction re-
sulted in the formation of [Cu(phen)(PCy3)]BF4, [Cu(bpy)(PCy3)2]-
BF4, and [Cu(MeO-CNN)(PCy3)]BF4 for complexes 1–3, where the
ligand stoichiometry were confirmed by 1H NMR, elemental analy-
sis and X-ray diffraction. All three complexes are yellow solid and
soluble in most organic solvents such as dichloromethane, chloro-
form and acetonitrile. They are stable in air and moisture.
The molecular structures of complexes of 1–3 have been charac-
terized by X-ray analysis. The copper(I) center adopts different
coordinated geometry according to the diimine ligands. For com-
plex 1 (see Fig. 1 and Table 2), the Cu(I) center adopts trigonal
geometry with the N1–Cu1–N2, N1–Cu1–P1 and N2–Cu1–P1 an-
gles 82.21(19), 142.39(14) and 132.52(14)°, respectively. Its Cu–N
(2.029(5) and 2.070(5) Å) and Cu1–P1 (2.1714(15) Å) distances
are shorter than those of tetrahedron copper(I) complexes
[Cu(phen)(PPh3)2]+ [8,22]. However, the Cu(I) center in complex
2 (see Fig. 2 and Table 2) adopts distorted tetrahedron geometry
with N1–Cu1–N2 and P1–Cu1–P2 angles 77.17(2) and 130.30(5)°,
respectively. The average Cu–N and Cu–P distances are 2.166 and
2.295 Å, respectively, which are comparable to those observed in
[Cu(phen)(PPh3)2]+ and [Cu(bpy)(PPh3)2]+ [9,23]. In addition, the
bpy ligand in 2 is not coplanar, with a dihedral angle 27.5(3)° be-
tween the two pyridyl moieties. This value is larger than that
(17.0(2)°) in [Cu(bpy)(PPh3)2]+, which is reasonable since larger
steric effect in PCy3 than that in PPh3.
2.2.3. Synthesis of [Cu(MeO-CNN)(PCy3)2]BF4 (3)
Complex 3 was prepared in a similar way to complex 1 except
that MeO-CNN was used in place of phen. The yellow crystals were
obtained suitable for X-ray diffraction. Yield: 84%. Anal. Calc. for
C46H74BCuF4N2P2 (867.36): C, 63.70; H, 8.60; N, 3.23. Found: C,
63.98; H, 8.21; N, 3.61%. 1H NMR (400 MHz, CDCl3): d 8.50 (d,
J = 9.0 Hz, 2H), 8.26 (d, J = 5.4 Hz, 2H), 8.11 (m, 2H), 7.30 (m, 2H),
1.50ꢁ1.72 (m, 34H), 1.20 (s, 32H).
2.3. Photophysical measurements
UV–Vis absorption spectra were recorded using Hitachi U-3010
spectrophotometer. Emission spectra were performed with Hitachi
F-4500 fluorescence spectrometer. 1H NMR spectra were obtained
on a Bruker Avance DPX-400 MHz.
2.4. X-ray crystallography
Crystals of complexes 1–3 were obtained by vapor diffusion of
diethyl ether into CH2Cl2 solution. Crystal data and details of data
collection as well as refinement are summarized in Table 1. Diffrac-
tion data were collected at room temperature with graphitemono-
chromatized Mo Ka radiation (k = 0.71073 Å) on a Bruker SMART
CCD area detector. Diffracted data were corrected for absorption
correction using SADABS [19] program. The structures were solved
by direct methods using the program SHELXS 97 [20] and refined
The coordinate geometry of 3 (see Fig. 3 and Table 2) is similar
to that of 1, and the copper center adopts trigonal configuration
with N1–Cu1–N2, N1–Cu1–P1 and N2–Cu1–P1 angles 80.79(17),
127.65(13) and 148.80(12)°, respectively. The Cu–N (2.054(4) and
2.036(4) Å) and Cu–P (2.1732(13) distances are comparable to
Table 1
Crystallographic data for complexes 1–3.
those in 1, but shorter than those in [Cu2(l-diimine)(MeO-
CNN)2(PCy3)2](BF4)2 [17]. The two pyridyl rings of MeO-CNN ligand
Complexes
1ꢀCH2Cl2
2
3
Formula
Formula
weight
Crystal
system
Space group
Color
C31H43BCl2CuF4N2 P C46H74BCuF4N2P2
C35H47BCuF4N2OP
693.07
695.9
867.36
orthorhombic
triclinic
monoclinic
ꢀ
Pbca
Pn
P1
yellow
yellow
yellow
Crystal size
(mm)
0.49 ꢂ 0.40 ꢂ 0.38 0.50 ꢂ 0.48 ꢂ 0.36 0.33 ꢂ 0.27 ꢂ 0.25
a (Å)
b (Å)
c (Å)
9.8734(11)
19.548(2)
34.497(3)
90
90
90
6658.3(12)
8
1.688
298
11.585(1)
11.874(1)
19.190(2)
80.407(2)
78.382(1)
61.905(1)
2273.1(4)
2
11.466(2)
11.836(2)
12.548(3)
90
92.597(4)
90
1701.1(6)
2
1.353
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dc (Mg mꢃ3
T (K)
)
1.267
298(2)
7869
293(2)
4475
Number of
5812
reflections
h Range (°)
l
2.17–25.01
0.928
2.15–25.38
0.601
2.20–27.48
0.741
(mmꢃ1
)
F(0 0 0)
R1, wR2
[I > 2
3496
0.0639, 0.1432
928
0.0638, 0.1629
728
0.0437, 0.1029
r(I)]
Goodness of
fit (GOF)
on F2
1.053
1.092
0.966
Fig. 1. Molecular structure of 1ꢀCH2Cl2 at the 30% probability displacement
ellipsoids. The counter ion, dichloromethane molecules and hydrogen atoms are
omitted for clarity.

Z.-W. Wang et al. / Inorganica Chimica Acta 363 (2010) 15–19
17
Table 2
Selected bond lengths (Å) and angles (°) for 1–3.
Complex 2
Cu1–N1
2.029(5)
Cu1–N2
2.070(5)
Cu1–P1
N1–Cu1–N2
N2–Cu1–P1
2.1714(15)
82.21(19)
132.52(14)
N1–Cu1–P1
142.39(14)
Complex 2
Cu1–N2
Cu1–N1
N2–Cu1–N1
N2– Cu1– P1
N1– Cu1– P1
Complex 3
Cu1–N1
2.147(4)
2.195(4)
77.17(2)
104.62(1)
117.31(1)
Cu1–P1
Cu1–P2
N2–Cu1–P2
N1–Cu1–P2
P1–Cu1–P2
2.289(7)
2.301(0)
113.88(1)
101.37(1)‘
130.30(5)
2.054(4)
2.036(4)
80.79(17)
148.80(12)
Cu1–P1
2.1732(13)
127.65(13)
Cu1–N2
N2–Cu1–N1
N2–Cu1–P1
N1–Cu1–P1
Fig. 3. Molecular structure of 3 at the 30% probability displacement ellipsoids. All
hydrogen atoms and dichloromethane molecules are omitted for clarity.
1.6
1.2
1.4
1.0
0.8
1.2
b
0.6
1.0
a
0.4
0.8
0.2
0.6
0.0
3
300
400
500
0.4
0.2
0.0
Wavelength / nm
2
1
250 300 350 400 450 500 550 600
Wavelength/nm
Fig. 2. Molecular structure of 2 at the 30% probability displacement ellipsoids.
Hydrogen atoms and the counter ion are omitted for clarity.
Fig. 4. Room temperature absorption spectra of 1–3 measured in dichloromethane.
The insert shows the absorption spectra of 3 in different solvents (a: CH2Cl2, b:
CH3OH), recorded using the same concentration.
are almost coplanar with a dihedral angle of 6.0(3)°, and the pen-
dant aromatic rings are twist with the adjacent pyridine fragments
with torsion angle of 43.2(3)°.
It was reported that copper (I) complexes containing diimine
and diphosphine ligands often undergo solvent-dependent, ligand
redistribution reactions [8–10], and their coordinated geometry
in solution may be also different from that in solid. Therefore, we
investigated how addition of excess PCy3 alters the UV–Vis spectra
of all complexes in dichloromethane solution. The absorption spec-
tra of 2 are almost not affected when excess PCy3 is added to the
solution, which indicates that no ligand redistribution reactions
happen in solution. However, the absorption spectra of 1 and 3
vary greatly when excess PCy3 is added to the solution (Fig. 5).
When excess PCy3 is added to the solution of 1, new broad band
in the 350–450 nm region is observed. It increases while the
absorption at 271 nm decreases, and shows an isosbestic point at
320 nm. The spectra no longer change when 5 to 10-fold excess
of PCy3 was added. Since the broad band in the 350–450 nm region
is very similar to MLCT transition of 2, we envision that new four-
coordinated species [Cu(phen)(PCy3)2]+ forms as shown in Eq. (1).
Attempts to obtain pure [Cu(phen)(PCy3)2]+ in solid by addition ex-
cess amount of PCy3 to 1 is failure, and only 1 and colorless unre-
acted PCy3 are obtained by slow diffusion diethyl ether into the
dichloromethane solution.
3.2. Electronic spectra properties
The UV–Vis spectra of complexes 1 and 3 (see Fig. 4) are dom-
inated by intense intraligand transitions with kmax in 271 nm for 1
and 274 and 332 nm for 3, given the low-energy p–p* absorption
of the free diimine ligands phen (263 nm in dichloromethane)
and MeO-CNN (273 nm and 312 nm (sh) in dichloromethane).
The weak low-energy transitions at k > 350 nm (tails about
450 nm) can be assigned to MLCT (metal-to-ligand charge-trans-
fer) transitions involving the diimine ligand and the Cu(I) ion. In
contrast, complex 2 shows intense high-energy intraligand transi-
tions at kmax = 293 nm, and moderate low-energy MLCT transitions
in the 350–450 nm region, which resembles that observed in
[Cu(Phen)(PPh3)2]+ and [Cu(bpy)(PPh3)2]+ [8–9]. The MLCT of 2
shifts toward shorter wavelength in the polar solvent, which is
consistent with the behavior of [Cu(Phen)(PPh3)2]+. However, the
MLCT of complexes 1 and 3 show positive solvatochromism effect
(Fig. 4), which implies that both complexes have a larger dipole
moment in the excited state than the ground state.

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Z.-W. Wang et al. / Inorganica Chimica Acta 363 (2010) 15–19
1.5
1.0
0.5
0.0
solution at room temperature, but display strong luminescence at
1.5
1.0
0.5
0.0
77 K in dichloromethane. The emission energies at 77 K in dichlo-
romethane appears to follow the same trend as those in solid state
with the kmax at 605, 628 and 643 nm for 1, 2 and 3, respectively.
4. Conclusions
In this work, we have synthesized and structurally character-
ized three new copper(I) complexes with tricyclohexylphosphine
and different diimine ligands. X-ray structure shows that the cop-
per(I) atom adopts three- or four-coordinated geometry according
to the diimine ligand. The three-coordinated 1 can change into
[Cu(phen)(PCy3)2]+ in chloromethane solution by addition excess
amount of PCy3, while 3 leads to [Cu(PCy3)2]BF4 and CNN-OMe.
All the three complexes display yellow 3MLCT emissions in solid
state or 77 K in solution.
300
400
500
Wavelength/nm
300
400
Wavelength/nm
500
600
Fig. 5. UV–Vis spectral of 1 (0.2 mM) in dichloromethane solution upon addition of
0, 0.2, 0.4 and 1.0 mM. The insert shows the absorption spectra of 3 (0.2 mM) in
dichloromethane solution upon addition of 0, 0.2, 0.6 and 1.0 mM.
Supplementary material
CCDC 724743, 724744 and 724745 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
1
3
2
This work was supported by the Bureau of Education of Jiangxi
Province (GJJ09074) and the program for innovative research team
of Nanchang University. We are also grateful to financial support
from Nanchang University for Youth teachers.
References
450
500
550
600
650
700
750
Wavelength/nm
[1] D.R. McMillin, K.M. McNett, Chem. Rev. 98 (1998) 1201.
[2] M.T. Miller, P.K. Gantzel, T.B. Karpishin, J. Am. Chem. Soc. 121 (1999) 4292.
[3] D.V. Scaltrito, D.W. Thompson, J.A. O’Callaghan, G.J. Meyer, Coord. Chem. Rev.
208 (2000) 243.
Fig. 6. Room temperature emission spectra of 1–3 measured in solid. (kex
=
355 nm).
[4] N. Armaroli, Chem. Soc. Rev. 30 (2001) 113.
[5] R.M. Williams, L.D. Cola, F. Hartl, J.J. Lagref, J.M. Planeix, A.D. Cian, M.W.
Hosseini, Coord. Chem. Rev. 230 (2002) 253.
[6] D. Felder, J.M. Nierengarten, F. Barigelletti, B. Ventura, N. Armaroli, J. Am.
Chem. Soc. 123 (2001) 6291.
[7] R.A. Rader, D. McMillin, M.T. Buckner, T.G. Matthews, D.J. Casadonte, R.K.
Lengel, S.B. Whittaker, L.M. Darmon, F.E. Lytle, J. Am. Chem. Soc. 103 (1981)
5906.
½CuðphenÞðPCy3Þꢄþ þ PCy3 ꢀ ½CuðphenÞðPCy3Þ ꢄþ
ð1Þ
ð2Þ
2
½CuðCNN-OMeÞðPCy3Þꢄþ þ PCy3 ꢀ ½CuðPCy3Þ ꢄþ þ CNN-OMe
2
The absorption changes of 3 upon gradual titration with PCy3
are different from those of 1. As the PCy3 concentration increase,
the band at 327 nm gradually decreases and then vanishes, while
band at 274 nm gradually increases. Since the absorption after
adding excess amount of PCy3 are very similar to that of the free
ligand CNN-OMe, we deduce that ligand redistribution reactions
as shown in Eq. (2) may happen in solution. Indeed, when we
add excess amount of PCy3 to 3, the yellow color disappears, and
colorless green luminescence crystals of [Cu(PCy3)2]BF4 [15b] and
blue luminescence crystals of CNN-OMe are formed by slow diffu-
sion diethyl ether into the dichloromethane solution. The forma-
tion of four-coordinated species for 1 while not for 3 in solution
may be due to the steric hindrance of the pendant aromatic rings
in CNN-OMe ligand, and the crystal lattice energy of 1 may lead
to the dissociation of [Cu(phen)(PCy3)2]+ in solid state.
Upon excitation at 370 nm, complexes 1–3 exhibit intense pho-
toluminescence with kmax at 558, 564 and 582 nm in the solid state
at room temperature, respectively (Fig. 6). Since the emission ener-
gies are comparable to those of some reported mixed-ligand cop-
per(I) complexes containing diimine and diphosphine ligands
[13–14], the yellow emissions are assigned to the 3MLCT state.
The three complexes do not display any detectable emission in
[8] J.R. Kirchhoff, D.R. McMillin, W.R. Robinson, D.R. Powell, A.T. McKenzie, S.
Chen, Inorg. Chem. 24 (1985) 3928.
[9] L.M. Engelhardt, C. Pakawatchai, A.H. White, J. Chem. Soc., Dalton Trans. (1985)
125.
[10] (a) D.G. Cuttell, S.M. Kuang, P.E. Fanwick, D.R. McMillin, R.A. Walton, J. Am.
Chem. Soc. 124 (2002) 6;
(b) S.M. Kuang, D.G. Cuttell, D.R. McMillin, P.E. Fanwick, R.A. Walton, Inorg.
Chem. 41 (2002) 3313.
[11] (a) Q. Zhang, Q. Zhou, Y. Cheng, L. Wang, D. Ma, X. Jing, F. Wang, Adv. Mater. 16
(2004) 432;
(b) Q. Zhang, Q. Zhou, Y. Cheng, L. Wang, D. Ma, X. Jing, F. Wang, Adv. Funct.
Mater. 16 (2006) 1203;
(c) Q. Zhang, J. Ding, Y. Cheng, L. Wang, Z. Xie, X. Jing, F. Wang, Adv. Funct.
Mater. 17 (2007) 2983.
[12] (a) W.L. Jia, T. McCormick, Y. Tao, J.P. Lu, S. Wang, Inorg. Chem. 44 (2005) 5706;
(b) T. McCormick, W.L. Jia, S. Wang, Inorg. Chem. 45 (2006) 147.
[13] L. Yang, J.K. Feng, A.M. Ren, M. Zhang, Y.G. Ma, X.D. Liu, Eur. J. Inorg. Chem.
(2005) 1867.
[14] K. Saito, T. Tsukuda, T. Tsubomura, Bull. Chem. Soc. Jpn. 79 (2006) 437.
[15] (a) C.M. Che, Z. Mao, V.M. Miskowski, M.C. Tse, C.K. Chan, K.K. Cheung, D.L.
Phikips, K.H. Leung, Angew. Chem., Int. Ed. Engl. 39 (2000) 4084;
(b) Z. Mao, H.Y. Chao, C.M. Che, W.F. Fu, K.K. Cheung, N.Y. Zhu, Chem. Eur. J. 9
(2003) 2885;
(c) W.F. Fu, X. Gan, C.M. Che, Q.Y. Cao, Z.Y. Zhou, N.Y. Zhu, Chem. Eur. J. 10
(2004) 2228.
[16] G.A. Bowmaker, S.E. Boyd, J.V. Hanna, R.D. Hart, P.C. Healy, B.W. Skelton, A.H.
White, J. Chem. Soc., Dalton Trans. (2002) 2722.
[17] G.J. Kubas, B. Monzyk, A.L. Crumbliss, Inorg. Synth. 28 (1990) 68.

Z.-W. Wang et al. / Inorganica Chimica Acta 363 (2010) 15–19
19
[18] (a) Q.Y. Cao, X. Gan, W.F. Fu, Chin. J. Chem. 22 (2004) 1283;
(b) W.F. Fu, X. Gan, J. Jiao, Y. Chen, M. Yuan, S.M. Chi, M.M. Yu, S.X. Xiong, Inorg.
Chim. Acta 360 (2007) 2758.
[21] G.M. Sheldrick, SHELXL 97, Program for the Refinement of Crystal Structure,
University of Gottingen, 1997.
[22] C.G. Bates, P. Saejueng, J.M. Murphy, D. Venkataraman, Org. Lett. 4 (2002)
[19] G.M. Sheldrick, SADABS, Bruker/Siemens Area Detector Absorption Correction
Program, Version 2.02, Bruker AXS, Madison, WI, 1998.
[20] G.M. Sheldrick, SHELXS 97, Program for the Solution of Crystal Structure,
University of Gottingen, 1997.
4727.
[23] M. Navarro, O.A. Corona, T. Gonzaleza, M.V. Capparelli, Acta Crystallogr. E64
(2008) m533.