Synthesis, crystal structures and photophysical properties of novel copper(I) complexes with 4-diphenylphosphino-1,5-naphthyridine ligands

Article abstract of DOI:10.1016/j.inoche.2011.12.028

Two new copper(I) complexes [Cu(L¹)₂]PF₆ (L¹ = 4-diphenylphosphino-1,5-naphthyridine, 1) and [Cu(L ²)₂]PF₆ (L² = 4-diphenylphosphino-8- methyl-1,5-naphthyridine, 2), have been prepared and characterized. In each of them, the coordinate geometry of Cu atom is a distorted square planar configuration with bond distances and angles in the normal range. Moreover, compound 2 features one-dimensional zigzag chains which are cross-linked by the metal complex cations and PF₆^- anions through hydrogen bonding interactions. The HOMO-LUMO energy gaps of 1-2 estimated by the cyclic voltammetry (CV) show values in the order of 1 > 2. Both 1 and 2 show low-energy bands ranging from 360 to 430 nm and available florescence in the solid state at room temperature with λ_max = 532-541 nm. The UV-vis absorption spectra of 1-2 show obvious red-shifts compared with those of the corresponding quinoline containing Cu(I) complexes [Cu(QN) ₂]PF₆ (QN = 8-diphenylphosphino quinoline), exhibiting the HOMO-LUMO energy gaps of 1-2 should be narrower than that of [Cu(QN) ₂]PF₆.

Full text of DOI:10.1016/j.inoche.2011.12.028

Inorganic Chemistry Communications 17 (2012) 116–119
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Synthesis, crystal structures and photophysical properties of novel copper(I)
complexes with 4-diphenylphosphino-1,5-naphthyridine ligands
⁎
Chen Chen, Kunyan Wang, Peng Jiang, Guangliang Song, Hongjun Zhu
Department of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, PR China
a r t i c l e i n f o
a b s t r a c t
Two new copper(I) complexes [Cu(L1)2]PF6 (L1 =4-diphenylphosphino-1,5-naphthyridine, 1) and [Cu(L2)2]
PF6 (L2 =4-diphenylphosphino-8-methyl-1,5-naphthyridine, 2), have been prepared and characterized. In
each of them, the coordinate geometry of Cu atom is a distorted square planar configuration with bond dis-
tances and angles in the normal range. Moreover, compound 2 features one-dimensional zigzag chains which
are cross-linked by the metal complex cations and PF6− anions through hydrogen bonding interactions. The
HOMO–LUMO energy gaps of 1–2 estimated by the cyclic voltammetry (CV) show values in the order of
1>2. Both 1 and 2 show low-energy bands ranging from 360 to 430 nm and available florescence in the
solid state at room temperature with λmax =532–541 nm. The UV–vis absorption spectra of 1–2 show obvi-
ous red-shifts compared with those of the corresponding quinoline containing Cu(I) complexes [Cu(QN)2]PF6
(QN=8-diphenylphosphino quinoline), exhibiting the HOMO–LUMO energy gaps of 1–2 should be narrower
than that of [Cu(QN)2]PF6.
Article history:
Received 18 October 2011
Accepted 16 December 2011
Available online 27 December 2011
Keywords:
Copper(I) complexes
1,5-Naphthyridine
HOMO–LUMO energy gaps
Red-shifts
Florescence
© 2011 Elsevier B.V. All rights reserved.
Copper(I) complexes have garnered much attention because of their
economical and environmental utilization in organic light emitting
diodes (OLEDs) [1]. Tremendous efforts have been devoted to tune
its fluorescence color to the red or blue region [2]. Among them,
the Cu(I) complex based on the asymmetrical P^N ligand processes
a considerably higher reduced state and exited state stability than
the analogous complexes based on symmetrical diimine or dipho-
sphine ligand [3]. In recent years, 8-(diphenylphosphino)-quinoline
(QN) ligands were extensively used for crystallization of Cu(I), Ni(I),
Ru(II) and Pd(II) compounds [3,4], whereas naphthalenephosphine based
coordination compounds were seldom reported. 4-Diphenylphosphino-
1,5-naphthyridine, which can be regarded as a combination of the
bidentate 1,5-naphthyridine and 4-(diphenylphosphino) pyridine,
exhibit various coordination modes, high symmetry and large con-
jugated π-system that may lead to special physical properties and
potential applications. Additionally, the difference of redox properties
between naphthyridine and quinoline provides a significant impetus
for our continued exploratory synthesis [5]. Here, we report the synthe-
sis, crystal structures and photophysical properties of two novel Cu(I)
complexes [Cu(L1)2]PF6 (L1=4-diphenylphosphino-1,5-naphthyri-
dine, 1) and [Cu(L2)2]PF6 (L2=4-diphenylphosphino-8-methyl-1,5-
naphthyridine, 2). To the best of our knowledge, there are no reports
of such work based on 1,5-naphthalenephosphine ligands.
The new ligands, L1 and L2 were synthesized by the reactions of
Ph2PLi [6] with the chloro-substituted starting compounds (Clnd
and Clmnd) [7], which were different from the reported method
[8]. The homoleptic complexes [Cu(L1)2]PF6 and [Cu(L2)2]PF6 were
obtained by the reaction of L1 and L2 with [Cu(CH3CN)4]PF6 in
CH3OH/CHCl3 [9] (Scheme 1), respectively.
The 1H NMR spectrum of 1 and 2 shows a symmetric signal set,
and only one single assigned to the proton of the methyl group in
the 4-position on a naphthyridine ring at δ 2.9 appeared. The 31P
NMR spectrums of 1 and 2 show a relatively broad signal at δ
−18.0 and δ −17.2 result from quadrapolar relaxation arising from
the copper nucleus [10], whereas the signal of free ligands is sharp
at δ −15.4 and δ −15.1, respectively. The elemental analysis (C, H,
and N) and mass spectrometric data are in excellent agreement with
the compositions of the ligands [9].
The X-ray diffraction measurements of single crystal of 1 were
carried out at room temperature (RT) [11] and low temperature
(LT) [12], respectively. Complex 1(RT) crystallizes in the monoclinic
system P21/c space group with two molecules per asymmetric unit
(Fig. 1a) and the presence of two hexafluorophosphate anions (PF6−
)
providing charge balance. The copper(I) exhibits highly distorted tetra-
hedral geometry arising from the intraligand chelate angles N1–Cu1–P1
in I and N7–Cu2–P4 in II being 88.47 (18) (deg) and 87.92 (17) (deg),
respectively. However, the P1–Cu1–P2 angle 118.61 (8) (deg) in I and
the P4–Cu2–P3 angle 122.04 (8) (deg) in II, have opened up due to
the steric effects from the bulky ND ligands. The average Cu–N
(2.055 Å) and Cu–P (2.225 Å) bond distances are comparable to those
reported for [Cu(QN)2]PF6 (QN=8-diphenylphosphino quinoline)
⁎
Corresponding author. Tel.: +86 25 8317 2358; fax: +86 25 8358 7443.
E-mail address: zhuhjnjut@hotmail.com (H. Zhu).
1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2011.12.028

C. Chen et al. / Inorganic Chemistry Communications 17 (2012) 116–119
117
Scheme 1. Synthesis of ligands and corresponding Cu(I) complexes.
Fig. 1. Views of 1(RT), hydrogen atoms and PF6− anions are omitted for clarity. (a) Coordination environment of Cu atom; (b) crystal packing structure with polyhedron along the a-
axis, green dash lines indicated hydrogen bonds.
(2.072 and 2.225 Å) [4f]. The selected bond lengths and bond angles are
given in Table 1. One of the two PF6− anions is position-disordered even
though in the low temperature (Fig. S1).
between the phenyl groups of the two Ph2P segments on each of the
two molecules in one asymmetric unit. Their reduced centroid–centroid
contacts of 3.78–3.95 Å symbolized the formation of a non-negligible
intra-molecular π–π stacking interaction (brown dash line), which are
analogous to those reported in the Ru(II) and Cu(I) complexes con-
taining phosphine ligands [3d, 3e]. It is noted that PF6− anions form
a zigzag chain along the a-axis as the Cu atoms (Fig. S2).
Structural analysis of 2 at RT [14] reveals that it crystallizes in C2/c
space group, which is different from complex 1(RT), as shown in
Table S2. In the structure of compound 2, half of the molecule is gen-
erated by inversion (Fig. 2a). Just as in the case of 1, the Cu+ ions are
coordinated by two bidentate L2 ligands and have a four-coordinate
structure with a highly distorted tetrahedral geometry. The Cu–N and
Cu–P bond lengths are 2.071 (3) Å and 2.2443 (11) Å, respectively,
which are similar to those of 1. The metal complex cations and PF6−
anions are connected by weak C-H-–F-P hydrogen bonds and form
In the crystal packing, the metal complex cations and PF6− anions
are connected by weak C\H—F\P hydrogen bonds, mainly distrib-
uted along the a-axis (Fig. 1b). Ten H–-F distances are shorter than
2.6 Å with the shortest one of 2.28 Å (Table S1), confirming their
significant role played in crystal cohesion [13]. Detailed analysis of
the structural data reveals the presence of three sets of π–π stacking
interactions (Fig. 1b). The first one is ascribed to the π–π stacking of
naphthyridine ligands between neighboring cations, for which the
centroid–centroid contact is calculated to be 3.75 Å (yellow dash
line). The second naphthyrine ligand is parallel to the naphthyrine
chelate of the adjacent molecule where an even stronger pairwise
π–π stacking is observed with the centroid–centroid contact being
reduced to 3.72 Å (blue dash line). The third one is the π–π stacking
Table 1
Selected bond lengths (Å) and angle (deg) for 1(RT) and 2.
1(RT)
2
Cu1–N1/Cu2–N7
Cu1–N4/Cu2–N6
Cu1–P1/Cu2–P4
Cu1–P2/Cu2–P3
2.057 (6)/2.046 (5)
2.062 (5)/2.049 (6)
2.222 (2)/2.218 (2)
2.232 (2)/2.227 (2)
107.9 (2)/107.5 (2)
88.47 (18)/87.92 (17)
124.25 (16)/128.46 (16)
133.89 (16)/126.67 (17)
87.78 (16)/87.86 (19)
118.61 (8)/122.04 (8)
−5.7 (8)/−6.0 (7)
6.3 (5)/10.9 (5)
Cu–N2
Cu–N2*
Cu–P1
Cu–P1*
2.071 (3)
2.071 (3)
2.2443 (11)
2.2443 (11)
110.08 (17)
87.35 (9)
124.91 (10)
124.91 (10)
87.35 (9)
125.36 (6)
2.5 (5)
N1–Cu1–N4/N7–Cu2–N6
N1–Cu1–P1/N7–Cu2–P4
N1–Cu1–P2/N7–Cu2–P3
N4-Cu1–P1/N6–Cu2–P4
N4–Cu1–P2/N6–Cu2–P3
P1–Cu1–P2/P4–Cu2–P3
Cu1–N1–C19–C20/Cu2–N7–C80–C79
Cu1–P1–C19–C20/Cu2–P4–C79–C80
Cu1–N4–C40-C33/Cu2–N6–C60–C53
Cu1–P2–C33–C40/Cu2–P3–C53–C60
N2–Cu–N2*
N2–Cu–P1
N2–Cu–P1*
N2*–Cu–P1
N2*–Cu–P1*
P1–Cu–P1*
Cu–N2–C8–C1
Cu–P1–C1–C8
Cu–N2*–C8–C1
Cu–P1*–C1–C8
−6.5 (3)
2.5 (5)
−6.5 (3)
−2.8 (8)/−3.6 (9)
8.7 (5)/9.7 (6)

118
C. Chen et al. / Inorganic Chemistry Communications 17 (2012) 116–119
Fig. 2. Views of 2, hydrogen atoms, solvent (C5H5O) molecules and PF6− anions are omitted for clarity. (a) Coordination environment of Cu atom; (b) crystal packing structure with
polyhedron through the bonding interactions along the a-axis, green dash lines indicated hydrogen bonds.
one-dimensional zigzag chains along the c-axis (Fig. 2b). Further-
more, the zigzag chains are packed together through face-to-face
π–π stacking between naphthyrine rings from adjacent chains along
the a-axis and the interplanar distance between the naphthyrine rings
is 3.89 Å (blue dash line).
in the absorption spectrum of the free ligand, which indicates that
the corresponding states exhibit metal-to-ligand charge transfer
(MLCT) character. The absorption spectra of 1 and 2 overall red-
shift apparently compared with that of [Cu(QN)2]PF6, indicating
the narrower HOMO–LUMO electronic energy gaps in 1 and 2,
which are consistent with the results estimated from the CV mea-
surements. Furthermore, the HOMO–LUMO electronic energy gaps
of 1, 2 and [Cu(QN)2]PF6 calculated by the absorption onsets
obtained from the UV–vis absorption spectra are 2.52, 2.39 and
2.65 eV, respectively, which are comparable with those estimated
from the CV measurements. Complexes 1 and 2 are not emissive in
solution, but their solid state fluorescent emissions are available.
The emission peaks of 1 (λmax =541 nm) and 2 (λmax =532 nm) blue-
shift apparently compared with that of [Cu(QN)2]PF6 (λmax =640 nm)
[4f]. This may be because the emission of copper(I) complexes with
asymmetrical P^N ligand is mainly dependent on the nature of
the P^N ligand. Meanwhile, the emission peak of 2 shows 9 nm
blue-shift compared to that of 1. The reason for this can be explained
as that the sterically active substituent prevents the excited state
conformation change from a tetrahedral to a more flattened struc-
ture, which has a lower MLCT energy [2b].
In summary, two new cuprous complexes containing phosphino-
naphthyrine ligands were successfully prepared and characterized.
The X-ray determinations reveal that the coordinate geometry of
the Cu atoms are distorted square planar configuration. These Cu(I)
complexes show different crystal packing configuration arising from
the steric effect of the methyl substituent on naphthyridine moiety.
Not only electrochemistry properties, but also photophysical proper-
ties show that the HOMO–LUMO energy gaps of 1–2 are narrower
than that of [Cu(QN)2]PF6. The peak emission of complex 1–2 are
shifting to the blue region compared to that of [Cu(QN)2]PF6. These
results will expand the design artifices of florescent complexes which
can emit lights covering a full range of visible colors.
Electrochemical behaviors of the two complexes had been stud-
ied in acetonitrile solutions, along with the comparative complexes
[Cu(QN)2]PF6 [4f]. Similar to quinoline-based Cu(I) complex, both 1
and 2 display irreversible and multiple oxidation peaks that might
be attributed to multiple electron-transfer originating from the
Cu(I) center and the P-coordinating groups (Fig. S3a). As Table 2
shows, the first oxidation potentials for the CuII/I redox couple became
more positive in the order of [Cu(QN)2]PF6 (+0.43 V)b2(+0.54 V)b
1(+0.59 V). These indicate that the naphthyridyl backbone stabilize
the Cu(I) oxidation state more than quinolyl backbone, owing to a better
π-acceptability of the naphthyridines. During the cathodic scan, all
of the three complexes show irreversible ligand-based reduction
processes with peak potentials at −2.28, −2.00, −1.94 V and the
onset potentials for reduction are −2.18, −1.87, −1.88 V, respec-
tively. HOMO and LUMO levels were estimated from the onset
potentials by comparison to ferrocene (4.8 eV versus vacuum) [15].
Electron affinities (LUMO) were estimated from the onset of the
reduction wave (ELUMO =−(4.8+Eref +Eonset(red))) and ionization
potential (HOMO) was estimated from the onset of the oxidation
wave (EHOMO =−(4.8+Eref +Eonset(ox))). The data of EHOMO, ELUMO
,
and gaps between the LUMO and HOMO energy levels are presented
in Table 2. Both the energy gaps of 1 and 2 are narrower than
that of [Cu(QN)2]PF6, this may ascribe to the introduction of electro-
nwithdrawing nitrogen atoms to the phenyl rings of the naphthyridyl
ligands.
The UV/vis absorption spectra of complexes 1 and 2 in CH2Cl2 and
the emission (λexc =370 nm) in solid crystal at 298 K are shown in
Fig. 3. To further elucidate the origin of these peaks, absorption and
fluorescent spectrums of the free ligand are also measured, as shown
in Table S3. Complexes 1 and 2 show very similar absorption spectra
with the short wavelength region below 320 nm, being due to ligand-
centered (LC) transitions of the iminephosphine ligands. In contrast,
the low-energy bands ranging from 360 to 430 nm cannot be found
Acknowledgments
This work is financially supported by the postgraduate innovation
fund of Jiangsu province (2011, CXZZ11_0366), P.R. China.
Table 2
Electrochemical dataa for 1, 2 and Cu(QN)2+
.
Compd.
E
ref(V)
Oxidation(V)
Eonset(ox)
(V)
EHOMO
(eV)
Reduction(V)
E1
Eonset(red)
(V)
ELUMO
(eV)
Egel (eV)b
Egopt(eV)c
E2
E1
E2
1
2
0.076
0.078
0.082
0.89
0.85
0.77
0.59
0.54
0.43
0.44
0.40
0.31
−5.32
−5.29
−5.19
−1.94
−2.00
−2.28
−2.12
−2.20
−2.47
−1.88
−1.87
−2.18
−3.00
−3.00
−2.70
2.32
2.27
2.49
2.52
2.39
2.65
Cu(QN)2+
a
Redox potential recorded in acetonitrile solution with 0.1 M TBAP as supporting electrolyte; scan rate=100 mV/s.
Band gaps obtained from electrochemical data.
Band gaps obtained from UV/Vis absorption spectrum.
b
c

C. Chen et al. / Inorganic Chemistry Communications 17 (2012) 116–119
[5] (a) V.D. Parker, J. Am. Chem. Soc. 98 (1976) 98–103;
119
(b) N. Saito, T. Kanbara, T. Kushida, K. Kubota, T. Yamamoto, Chem. Lett. 10
(1993) 1775–1778;
(c) C.J. Tonzola, M.M. Alam, W. Kaminsky, S.A. Jenekhe, J. Am. Chem. Soc. 125
(2003) 13548–13558.
[6] A. Leone-Bay, J. Org. Chem. 51 (1986) 2378–2379.
[7] Synthesis of L1: A solution of PPh2Li (960 g, 5 mmol) in THF (5 mL) was added
dropwise to a solution of Clnd (820 mg, 5 mmol) in 20 ml THF at room temper-
ature under argon atmosphere in half an hour. The mixture was stirred for 20 h
at room temperature. The solvent was then removed and 10 mL of water was
added. The resultant solution was extracted by diethyl ether (3X15 mL). The
combined organic layer was concentrated and purified by column chroma-
tography producing 500 mg (32% yield) of a yellow powered solid. Anal.
Calc. for L1 (C20H15N2P1, 314.1): C, 76.42; H, 4.81; N, 8.91. Found: C, 76.70;
H, 5.08; N, 8.89%. ESI-MS: m/z = 315 [M]+ 1H NMR (300 MHz, CDCl3) (ppm):
.
δ 8.87 (dd, J=4.1, 1.6 Hz, 1H), 8.81 (d, J=4.3 Hz, 1H), 8.40 (tt, J=8.5, 1.6 Hz, 1H),
7.60 (dd, J=8.5, 4.2 Hz, 1H), 7.39–7.26 (m, 10H), 7.00 (dd, J=4.3, 3.2 Hz, 1H).
31P-NMR (CDCl3; d, ppm): δ −15.4 (s). Synthesis of L2: This compound was syn-
thesized in the same manner as L1, except that Clmnd (979 mg, 5.5 mmol) was
used instead of Clnd. The product (L2) was obtained as a yellow powered solid.
Yield: 40% (722 mg). Anal. Calc. for L2 (C21H17N2P1, 328.1): C, 76.82; H, 5.22;
N, 8.53. Found: C, 76.93; H, 4.68; N, 8.35%. ESI-MS: m/z=329 [M]+ 1H NMR
.
(300 MHz, CDCl3) (ppm): δ 8.81 (dd, J=4.3, 0.8 Hz, 1H), 8.71 (d, J=4.3 Hz, 1H),
7.43 (d, J=4.3 Hz, 1H), 7.35–7.25 (m, 10H), 6.98 (dd, J=4.3, 3.1 Hz, 1H), 2.83
(s, 3H). 31P-NMR (CDCl3; d, ppm): δ −15.1 (s).
Fig. 3. Absorption and photoluminescence spectra of 1 and 2 at room temperature.
Absorption (left): CH2Cl2, 1 cm cell. Emission (right): λexc =370 nm, solid.
[8] P.A. Aguirre, C.A. Lagos, S.A. Moya, E. Sola, G. Perisd, J.C. Bayon, Dalton Trans. 46
(2007) 5419–5426.
Appendix A. Supplementary data
[9] Synthesis of 1: L1 (408 mg, 1.3 mmol) in 10 mL chloroform was added to a solution
of [Cu(CH3CN)4]PF6 (241.8 mg, 0.65 mmol) in methanol (30 mL) under nitrogen
atmosphere. The reaction mixture was stirred for 2 h at room temperature and
then filtered. The filtrate was further reelingly evaporated to remove the solvent
and the crude product was obtained as a red powder. Red crystals of 1, which
were suitable for X-ray diffraction analysis, were obtained by recrystallization
CCDC 833120 for 1 and 833123 for 2 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.
from tetrahydrofuran/methanol/ethylether (2:1:6 v/v/v) in
(78%). Anal. Calc. for 1 (C40H30CuF6N4P3, 836.8): C, 57.39; H, 3.61; N, 6.69. Found:
C, 57.18; H, 3.77; N, 6.53%. ESI-MS: m/z=691 [Cu(L1)2]+ 1H NMR (500 MHz,
a yield of 848 mg
.
Appendix A. Supplementary data
DMSO-d6) (ppm): δ 9.26 (d, J=4.3 Hz, 1H), 8.78 (dd, J=8.6, 1.5 Hz, 1H), 8.63
(dd, J=4.5, 1.3 Hz, 1H), 8.11 (d, J=4.2 Hz, 1H), 7.87 (dd, J=8.6, 4.6 Hz, 1H),
7.53–7.38 (m, 10H). 31P-NMR (CDCl3) (ppm): δ −18.0 (br). Synthesis of 2:
This compound was synthesized in the same manner as 2, except that L2
(328 mg, 1 mmol) was used instead of L1. Orange crystals of 2 containing
one molecule of tetrahydrofuran, which were suitable for X-ray diffraction
analysis, were obtained by recrystallization from tetrahydrofuran/methano-
l/ethylether (2:1:6 v/v/v) in a yield of 586 mg (62%). Anal. Calc. for 2·C5H5O (C46H38-
CuF6N4OP3, 945.1): C, 59.20; H, 4.10; N, 6.00. Found: C, 58.42; H, 2.20; N, 5.99%.
Supplementary materials related to this article can be found online
at doi:10.1016/j.inoche.2011.12.028.
References
[1] (a) D.V. Scaltrito, D.W. Thompson, G.J. Meyer, Coord. Chem. Rev. 208 (2000) 243–266;
(b) N. Armaroli, G. Accorsi, F. Cardinali, A. Listorti, Top. Curr. Chem. 280 (2007)
69–115;
(c) A. Lavie-Cambot, M. Cantuela, Y. Leydet, G. Jonusauskasb, D.M. Bassania, N.D.
McClenaghana, Coord. Chem. Rev. 252 (2008) 2572–2584.
[2] (a) Y.G. Ma, C.M. Che, H.Y. Chao, X.M. Zhou, W.H. Chan, J.C. Shen, Adv. Mater. 11
(1999) 852–857;
ESI-MS: m/z=719 [Cu(L2)2]+ 1H NMR (300 MHz, DMSO-d6) (ppm): δ 9.25
.
(d, J =4.3 Hz, 1H), 8.44 (d, J= 4.8 Hz, 1H), 8.11 (d, J =4.3 Hz, 1H), 7.73
(dd, J =4.8, 0.8 Hz, 1H), 7.54–7.37 (m, 10H), 2.85 (s, 3H). 31P-NMR (CDCl3)
(ppm): δ −17.2 (br).
[10] B. Mohr, E.E. Brooks, N. Rath, E. Deutsch, Inorg. Chem. 30 (1991) 4541–4545.
[11] X-ray diffraction datas were collected at 293 K on a Nonius CAD4 area detector
using grafite-monochromated Mo Kα radiation (λ=0.71073 Å). Intensity data
sets were corrected for absorption by a psi-scan procedure and the structures
was determined by direct methods, with SHELXL-1997. Nonhydrogen atoms
were refined anisotropically, and all hydrogen atoms were placed at ideal
positions and allowed to ride.
[12] X-ray diffraction datas were collected at 223 K on a Rigaku Saturn area detector
using grafite-monochromated Mo Kα radiation (λ=0.71073 Å). Intensity data
sets were corrected for absorption by a multi-scan procedure and the structures
was determined by direct methods, with SHELXL-1997. Nonhydrogen atoms were
refined anisotropically, and all hydrogen atoms were placed at ideal positions and
allowed to ride.
(b) D.G. Cuttell, S.M. Kuang, D.R. McMillin, R.A. Walton, J. Am. Chem. Soc. 124
(2002) 6–7;
(c) V. Pawlowski, G. Knör, C. Lennartz, A. Vogler, Eur. J. Inorg. Chem. 15 (2005)
3167–3171;
(d) A. Tsuboyama, K. Kuge, M. Furugori, S. Okada, M. Hoshino, K. Ueno, Inorg.
Chem. 46 (2007) 1992–2001;
(e) G.F. Manbeck, W.W. Brennessel, C.M. Evans, R. Eisenberg, Inorg. Chem. 49
(2010) 2834–2843;
(f) G. Accorsi, N. Armaroli, C. Duhayon, B. Delavaux-Nicot, R. Welter, O. Moudam,
M. Holler, J.F. Nierengarten, Eur. J. Inorg. Chem. 1 (2010) 164–173.
[3] L. Qin, Q.-S. Zhang, W. Sun, J.-Y. Wang, C.-Z. Lu, Y.-X. Cheng, L.-X. Wang, Dalton
Trans. (2009) 9388–9391.
[4] (a) H.A. Hudali, J.V. Kingston, H.A. Tayim, Inorg. Chem. 18 (1979) 1391–1394;
(b) K. Issleib, M. Haftendorn, Z. Anorg, Allg. Chem. 389 (1972) 263–268;
(c) P. Wehman, H.M.A. van Donge, A. Hagos, P.C.J. Kamer, P.W.N.M. van Leeuwen,
J. Organomet. Chem. 535 (1997) 183–193;
[13] (a) F. Grepioni, G. Cojazzi, S.M. Draper, N. Scully, D. Braga, Organometallics 17
(1998) 296–307;
(b) J.I.I. Kim, I.S. Shin, H. Kim, J.K. Lee, J. Am. Chem. Soc. 127 (2005) 1614–1615.
[14] X-ray diffraction datas were collected at 293 K on a Nonius CAD4 area detector
using grafite-monochromated Mo Kα radiation (λ=0.71073 Å). Intensity data
sets were corrected for absorption by a psi-scan procedure and the structures
was determined by direct methods, with SHELXL-1997. Nonhydrogen atoms
were refined anisotropically, and all hydrogen atoms were placed at ideal positions
and allowed to ride.
(d) T. Suzuki, T. Kuchiyama, S. Kishi, S. Kaizaki, H.D. Takagi, M. Kato, Inorg. Chem.
42 (2003) 785–795;
(e) T. Suzuki, T. Kuchiyama, S. Kishi, S. Kaizaki, M. Kato, Bull. Chem. Soc. Jpn. 75
(2002) 2433–2439;
(f) T. Tsukuda, C. Nishigata, K. Arai, T. Tsubomura, Polyhedron 28 (2009) 7–12;
(g) K. Matsumoto, N. Matsumoto, A. Ishii, M. Hasegawab, T. Tsubomura, Dalton
Trans. 34 (2009) 6795–6801.
[15] X. Shen, F.L. Wang, F. Sun, R. Zhao, D.R. Zhu, Inorg. Chem. Commun. 14 (2011)
1511–1515.