1D and 2D supramolecular structures of silver carborane dicyclohexylphosphine complexes constructed by C-H?H-B dihydrogen bonding interactions

Article abstract of DOI:10.1016/j.poly.2011.02.052

Five new carborane dicyclohexylphosphine complexes, [Ag₂(μ-I) ₂{1,2-(P Cy₂)₂-1,2-C₂B ₁₀H₁₀}₂] (1), [Ag₂(SCN) ₂{1,2-(PCy₂)₂-1,2-C₂B ₁₀H₁₀}₂]_n·CH ₂Cl₂ (2), [Ag(ClO₄){1,2-(PCy₂) ₂-1,2-C₂B₁₀H₁₀}]·CH ₂Cl₂ (3), [Ag₂(μ-NO₃) ₂{1,2-(PCy₂)₂-1,2-C₂B ₁₀H₁₀}₂]·CH₂Cl₂ (4) and [Ag(SC₆H₄COOH){1,2-(PCy₂) ₂-1,2-C₂B₁₀H₁₀}₂] ·CH₂Cl₂ (5), have been synthesized by the reactions of 1,2-bis(dicyclohexylphosphino)-1,2-dicarba-closo-dodecaborane with AgX (X = I, SCN, ClO_4, NO₃ and SC₆H₄COOH) in CH₂Cl₂. The structures of the five complexes were characterized by elemental analysis, FT-IR, ¹H, ¹³C, ¹¹B and ³¹P NMR spectroscopy. X-ray structure analysis revealed that the structures of the complexes can be classified into three types. Complexes 1 and 4 are di-μ-X-bridged structures and complexes 3 and 5 are mononuclear structures, while complex 2 is a chain-like polymer. Complexes 1 and 2 form 2D supramolecular networks and complexes 3, 4 and 5 form 1D chains via C-H?H-B dihydrogen bonding interactions.

Full text of DOI:10.1016/j.poly.2011.02.052

Polyhedron 30 (2011) 1469–1477
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
1D and 2D supramolecular structures of silver carborane dicyclohexylphosphine
complexes constructed by C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions
a
a
a,
Li-Guo Yang a, Cheng-Chen Zhu a, Dao-Peng Zhang b, , Da-Cheng Li , Da-Qi Wang , Jian-Min Dou
⇑
⇑
a School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, PR China
b College of Chemical Engineering, Shandong University of Technology, Zibo 255049, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Five new carborane dicyclohexylphosphine complexes, [Ag2(l-I)2{1,2-(P Cy2)2-1,2-C2B10H10}2] (1),
Received 22 November 2010
Accepted 18 February 2011
Available online 15 March 2011
[Ag2(SCN)2{1,2-(PCy2)2-1,2-C2B10H10}2]nꢀCH2Cl2 (2), [Ag(ClO4){1,2-(PCy2)2-1,2-C2B10H10}]ꢀCH2Cl2 (3),
[Ag2(
l
-NO3)2{1,2-(PCy2)2-1,2-C2B10H10}2]ꢀCH2Cl2 (4) and [Ag(SC6H4COOH){1,2-(PCy2)2-1,2-C2B10H10}2]ꢀ
CH2Cl2 (5), have been synthesized by the reactions of 1,2-bis(dicyclohexylphosphino)-1,2-dicarba-closo-
dodecaborane with AgX (X = I, SCN, ClO4, NO3 and SC6H4COOH) in CH2Cl2. The structures of the five com-
plexes were characterized by elemental analysis, FT-IR, 1H, 13C, 11B and 31P NMR spectroscopy. X-ray
structure analysis revealed that the structures of the complexes can be classified into three types.
Keywords:
Synthesis and characterization
Crystal structure
Ag(I) carborane complexes
1,2-bis(Dicyclohexylphosphino)-1,2-
dicarba-closo-dodecaborane (10)
Dihydrogen bonds
Complexes 1 and 4 are di-l-X-bridged structures and complexes 3 and 5 are mononuclear structures,
while complex 2 is a chain-like polymer. Complexes 1 and 2 form 2D supramolecular networks and
complexes 3, 4 and 5 form 1D chains via C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
palladium [18,19,24], copper [25], ruthenium [26], gold [27], silver
[28], chromium, molybdenum and tungsten [29]. Our group was
The C-substituted derivatives of dicarba-closo-dodecaborane
(1,2-C2B10H10), which was first reported in the early 1960s [1],
have been intensely studied over the past several decades because
of their interesting potential applications in many fields, such as
boron neutron capture therapy (BNCT) [2–5], host–guest chemistry
[6,7], materials science [8–10], catalysts [11] and coordination
chemistry [12–15]. Recently, some diphosphine ligands of the type
closo-1,2-(PR2)2-1,2-C2B10H10 (R = phenyl, ethyl, isopropyl and eth-
oxy) have been synthesized [16]. Due to their excellent abilities to
form stable five-member chelating rings between the ligand and
metal atoms, these diphosphine ligands play an important role in
the development of coordination chemistry [17–19].
In 1995, the first study of a new kind of interaction, the dihydro-
gen bond (DHB), was performed [20]. Since then, several types of
DHBs have been reported, including O–Hꢀ ꢀ ꢀH–B, N–Hꢀ ꢀ ꢀH–B, S–
Hꢀ ꢀ ꢀH–B, C–Hꢀ ꢀ ꢀH–B [21,22]. With respect to [C–Hꢀ ꢀ ꢀH–B] dihydro-
gen bonds, the ability of C–H bonds to form the dihydrogen bonds
has been fairly well recognized. Our group also studied C–Hꢀ ꢀ ꢀH–B
dihydrogen bond systems involving isopropyl groups in previous
work [23].
also interested in these types of ligands, and synthesized some
complexes of 1,2-(PR2)2-1,2-C2B10H10 (R = Ph, iPr) with transition
metals such as nickel [30], palladium [31], silver [32], zinc [33]
and copper [34]. In addition, the structure of the compound 1,2-
(PCy2)2-1,2-C2B10H10 has been reported [35]. To further study the
effect of different substitute groups on the structure of the com-
plexes formed, in this paper, we investigated the reactions of the
ligand 1,2-(PCy2)2-1,2-C2B10H10 with AgX (X = I, SCN, ClO4, NO3
and SC6H4COOH), and obtained five silver complexes with the
molecular formula [Ag2(
(1), [Ag2(SCN)2 {1,2-(PCy2)2-1,2-C2B10H10}2]nꢀCH2Cl2 (2), [Ag(ClO4)
-NO3)2{1,2-(PCy2)2-
l-I)2{1,2-(PCy2)2-1,2-C2B10H10}2]
{1,2-(PCy2)2-1,2-C2B10H10}]ꢀCH2Cl2 (3), [Ag2(
l
1,2-C2B10H10}2]ꢀCH2Cl2 (4) and [Ag(SC6H4COOH){1,2-(PCy2)2-1,2-
C2B10H10}2]ꢀCH2Cl2 (5). To the best of our knowledge, there has
been no report on complexes of 1,2-(PCy2)2-1,2-C2B10H10, which
are linked into 1D and 2D supramolecular structures through
C–Hꢀ ꢀ ꢀH–B dihydrogen bonds interactions between the cyclohexyl
groups and the carborane cages.
2. Experimental
Related to the previous work, several groups have reported
complexes of bis(diphenylphosphino)-o-carborane, including
2.1. Materials
All the reactions were carried out under an atmosphere of dry
dinitrogen. Dichloromethane, ethanol and n-hexane were dried
with appropriate drying agents and distilled under dinitrogen prior
⇑
Corresponding authors. Tel.: +86 0635 8239298, fax: +86 635 8239001.
E-mail addresses: dpzhang73@126.com (D.-P. Zhang), dougroup@163.com
(J.-M. Dou).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.02.052

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L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
to use. 1,2-(PCy2)2-1,2-C2B10H10 was synthesized according to the
literature [35]. All the other reagent chemicals were purchased
and used as received.
filtration, the solvent was volatilized in air and yellow crystals sep-
arated out about 1 week later (39.3 mg, 51%). M.p. 198–199 °C. FT-
IR (cmꢁ1): 2921 (s), 2848 (m), 2570 (m), 1630 (w), 1445 (m), 1384
(m), 1072 (m), 719 (m). 1H NMR (400.15 MHz, CDCl3) d (ppm):
1.35–2.23 (44H, Cy-H); 13C NMR (100.63 MHz, CDCl3) d (ppm):
26.0–39.0 (s, C, Cy-C); 77.312–76.680 (d, 1J(C, P) = 252.8, 2C, carbo-
rane-C). 11B NMR (CDCl3) d (ppm): ꢁ22.5 (6B), ꢁ27.9 (6B), ꢁ31.7
(8B). 31P{1H} NMR (CDCl3) d (ppm): 45.66 (s, 4(PCy2)). Anal. Calc.
for C52H108Ag2B20I2P4: C, 40.44; H, 6.99. Found: C, 40.64; H, 7.10%.
By employing the same procedure described above, complexes
2–5 were prepared.
2.2. Physical measurements
Infrared spectra were obtained from KBr pellets on a Nicolet-
460 FT-IR spectrophotometer. Elemental analysis (C, H) was per-
formed with a Perkin-Elemer 2400 II elemental analyzer. The 1H,
13C, 11B and 31P NMR spectra were recorded on a Varian Mercury
400 spectrometer in CDCl3 solution with tetramethylsilane (TMS)
as an internal standard at 400.15 and 100.63 MHz, respectively.
The 13C spectra are broadband proton decoupled. The chemical
shifts are reported in parts per million with respect to the refer-
ences and are stated relative to external TMS for the 1H and 13C
NMR spectra. Chemical shift values for the 11B NMR spectra were
referenced to external BF3ꢀOEt2 and 31P{1H} NMR spectra were ref-
erenced to external 85% H3PO4.
2.4.2. Complex 2
(40.1 mg, 52%). M.p. 212–215 °C. FT-IR (cmꢁ1): 2929 (s), 2851
(m), 2567 (m), 2088 (m), 1629 (m), 1446 (s), 1384 (m), 1073 (m),
739 (m). 1H NMR (400.15 MHz, CDCl3) d (ppm): 1.34–2.22 (44H,
Cy-H); 13C NMR (100.63 MHz, CDCl3) d (ppm): 26.1–39.1 (s, 24C,
Cy-C); 77.335–76.703 (d, 1J(C, P) = 252.8, 2C, carborane-C). 11B
NMR (CDCl3) d (ppm): ꢁ22.6 (2B), ꢁ29.4 (2B), ꢁ32.5 (2B), ꢁ35.0
(4B). 31P{1H} NMR (CDCl3) d (ppm): 45.60 (s, 2(PCy2)). Anal. Calc.
for C56H112Ag2B20Cl4N2P4S2: C, 42.66; H, 7.11; N, 1.78. Found: C,
42.44; H, 7.16; N, 1.70%.
2.3. X-ray crystallography
Yellow crystals of complexes 1–5 were selected for diffraction
analysis. The collections of intensity data were carried out on a
Bruker Smart-1000 CCD diffractometer using graphite-monochro-
2.4.3. Complex 3
matized Mo K
a
radiation (k = 0.71073 Å) at 298(2) K. The struc-
(40.6 mg, 49%). M.p. > 300 °C. FT-IR (cmꢁ1): 2932 (s), 2852 (m),
2576 (m), 1630 (w), 1446 (m), 1384 (w), 1073(m), 735 (m). 1H
NMR (400.15 MHz, CDCl3) d (ppm): 1.32–2.20 (44H, Cy-H); 13C
NMR (100.63 MHz, CDCl3) d (ppm): 26.5–39.4 (s, 24C, Cy-C);
77.529–76.627 (d, 1J(C, P) = 360.8, 2C, carborane-C). 11B NMR
(CDCl3) d (ppm): ꢁ23.5 (2B), ꢁ30.3 (2B), ꢁ35.3 (2B), ꢁ44.5 (4B).
31P{1H} NMR (CDCl3) d (ppm): 27.07, 24.85 (s, 2(PCy2)). Anal. Calc.
for C27H56AgB10Cl3O4P2: C, 39.08; H, 6.76. Found: C, 39.20; H,
6.66%.
tures were solved by direct methods and expanded using Fourier
difference techniques with the SHELXTL-97 program package [36].
The non- hydrogen atoms were refined anisotropically by full-
matrix least-squares calculations on F2. The R-factor of complex 3
was high, which might result from the weakly diffracting nature
of the crystal. All H atoms were located from Fourier maps and
were refined isotropically. The crystallographic data for the five
complexes are summarized in Table 1.
2.4. Synthesis
2.4.4. Complex 4
(37.3 mg, 47%). M.p. 192–193 °C. FT-IR (cmꢁ1): 2928 (s), 2851
(m), 2574 (m), 1630 (w), 1449 (s), 1384 (m), 1073 (m), 732 (m).
1H NMR (400.15 MHz, CDCl3) d (ppm): 1.33–2.21 (44H, Cy-H);
13C NMR (100.63 MHz, CDCl3) d (ppm): 26.6–39.5 (s, 24C, Cy-C);
77.312–76.680 (d, 1J(C, P) = 252.8, 2C, carborane-C). 11B NMR
2.4.1. Complex 1
AgI (23.5 mg, 0.10 mmol) and 1,2-(PCy2)2-1,2-C2B10H10
(53.5 mg, 0.10 mmol) were mixed in 10 ml CH2Cl2. The mixture
was stirred for 6 h under a dry nitrogen atmosphere. After
Table 1
Details of the crystal parameters, data collection and refinement for complexes 1–5.
1
2
3
4
5
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
a (Å)
C
52H108Ag2B20I2P4
C56H112Ag2B20Cl4N2P4S2 C27H56AgB10Cl3O4P2
C54H116Ag2B20Cl4N2O6P4
1587.11
C34H61AgB10Cl2O2P2S
882.70
monoclinic
C2/c
1543.00
monoclinic
P2(1)/n
1575.22
monoclinic
P2(1)/n
828.98
triclinic
triclinic
ꢀ
ꢀ
P1
P1
15.4620(18)
10.2101(12)
23.532(3)
90
102.983(2)
90
3620.0(7)
2
1.416
15.6140(15)
11.4001(12)
22.900(2)
90
100.358(2)
90
9.234(9)
10.048(10)
23.09(2)
85.667(16)
89.487(15)
63.690(14)
1915(3)
12.0834(11)
13.7671(14)
14.6367(16)
114.055(2)
101.2800(10)
107.4010(10)
1975.8(3)
1
38.012(3)
11.3940(10)
25.075(2)
90
115.471(2)
90
9804.7(15)
8
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
4009.8(7)
2
2
D (Mg mꢁ3
F(0 0 0)
)
1.305
1.438
1.334
824
1.196
3664
1560
1632
856
Data/restraints/parameters
6365/0/361
1.009
7052/7/406
1.003
6469/1369/452
1.009
6864/0/415
1.002
86161/1/469
1.001
Goodness-of-fit on F2
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0749,
wR2 = 0.1654
R1 = 0.1317,
wR2 = 0.1982
1.609 and ꢁ1.154
R1 = 0.0478,
wR2 = 0.0981
R1 = 0.0493,
wR2 = 0.1053
0.873 and ꢁ0.650
R1 = 0.1041,
wR2 = 0.2598
R1 = 0.1519,
wR2 = 0.2956
1.330 and ꢁ1.159
R1 = 0.0544,
wR2 = 0.1501
R1 = 0.0627,wR2 = 0.1361
R1 = 0.0916,wR2 = 0.1970 R1 = 0.1605,wR2 = 0.1570
0.792 and -0.732 0.773 and -0.388
Largest difference in peak and hole
(e Åꢁ3
)

L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
1471
Cy2
Cy2
P
PCy2
P
X
X
CH2Cl2
stirring
C
C
C
AgX
+
Ag
Ag
C
C
C
PCy2
P
P
Cy2
Cy2
(X = I, O-NO2)
Scheme 1. Preparation of complexes 1 and 4.
N
C
Cy2
S
P
C
Ag
C
P
Cy2
N
C
Cy2
P
PCy2
CH2Cl2
stirring
C
S
AgSCN
+
C
C
Ag
PCy2
C
P
N
Cy2
C
Cy2
P
S
C
Ag
C
P
Cy2
Scheme 2. Preparation of complex 2.
for C54H116Ag2B20Cl4N2O6P4: C, 40.83; H, 7.31; N, 1.76. Found: C,
41.05; H, 7.39; N, 1.65%.
Cy2
P
PCy2
C
CH2Cl2
stirring
C
C
AgX
+
C
Ag
X
PCy2
P
Cy2
2.4.5. Complex 5
(39.7 mg, 45%). M.p. > 300 °C. FT-IR (cmꢁ1): 2921 (s), 2848 (m),
2570 (m), 1632 (m), 1445 (m), 1384 (m), 1072 (m), 739 (m). 1H
NMR (400.15 MHz, CDCl3) d (ppm): 1.29–2.17 (44H, Cy-H); 13C
NMR (100.63 MHz, CDCl3) d (ppm): 26.8–39.8 (s, 24C, Cy-C);
77.320–76.680 (d, 1J(C, P) = 256.0, 2C, carborane-C). 11B NMR
(CDCl3) d (ppm): ꢁ20.6 (2B), ꢁ25.6 (2B), ꢁ28.3 (2B), ꢁ32.3 (4B).
31P{1H} NMR (CDCl3) d (ppm): 27.72, 24.50 (s, 2(PCy2)). Anal. Calc.
for C34H61AgB10Cl2O2P2S: C, 46.22; H, 6.91. Found: C, 46.02; H,
6.82%.
(X = O-ClO3, SC6H4COOH)
Scheme 3. Preparation of complexes 3 and 5.
(CDCl3) d (ppm): ꢁ19.1 (2B), ꢁ24.4 (8B), ꢁ28.1 (10B). 31P{1H} NMR
(CDCl3) d (ppm): 27.73, 27.57, 25.45, 25.30 (s, 4(PCy2)). Anal. Calc.
Fig. 1. The crystal structure of complex 1. The H atoms have been omitted for clarity.

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L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
Fig. 2. The crystal structure of complex 4. The H atoms and solvent molecules have been omitted for clarity.
3. Results and discussion
Table 2
Selected bond lengths (Å) and angles (°) for complexes 1–5.
3.1. Synthesis of complexes
Complex 1
P(1)–C(25)
P(2)–C(26)
C(25)–C(26)
P(1)–Ag(1)–P(2)
I(1)–Ag(1)–I(1)#1
1.88(1)
1.88(1)
1.88(2)
92.2(1)
101.5(4)
Ag(1)–p(2)
I(1)–Ag(1)
Ag(1)–P(1)
I(1)–Ag(1)#1
2.51(3)
2.80(1)
2.49(3)
2.87(1)
All the complexes are obtained by the reactions of 1,2-(PCy2)2-
1,2-C2B10H10 with AgX (X = I, SCN, ClO4, NO3 and SC6H4COOH) in
CH2Cl2 solution under the protection of dry N2 at room tempera-
ture. The as-obtained five complexes can be classified into three
types according to their structural characteristics. Complexes 1
Complex 2
Ag(1)–N(1)
Ag(1)–P(2)
Ag(1)–P(1)
Ag(1)–S(1)
2.33(5)
2.50(1)
2.51(1)
2.53(2)
P(1)–C(1)
P(2)–C(2)
C(1)–C(2)
P(2)–Ag(1)–P(1)
1.88(5)
1.88(5)
1.88(7)
90.1(5)
and
4 possess di-l-X-bridged dimer structures (X = I, NO3)
(Scheme 1). Complex 2 is a chain-like polymer composed of repeat-
ing structural units [Ag2(SCN)2{1,2-(PCy2)2-1,2-C2B10H10}2]
(Scheme 2). Complexes 3 and 5 are mononuclear structures
(Scheme 3). These phenomena can be attributed to the difference
of the coordination anions, which has also been reported by
Francesco Caruso [28].
Complex 3
Ag(1)–O(1)
Ag(1)–P(1)
Ag(1)–P(2)
O(1)–Ag(1)–P(2)
2.27(7)
2.44(3)
2.45(3)
135.7(2)
P(2)–C(2)
P(1)–C(1)
C(1)–C(2)
P(1)–Ag(1)–P(2)
1.86(1)
1.86(1)
1.85(1)
94.3(1)
Complex 4
3.2. IR spectra
Ag(1)–O(3)
Ag(1)–P(1)
Ag(1)–P(2)
O(3)–Ag(1)#1
O(3)–Ag(1)–O(3)#1
2.28(4)
2.41(2)
2.46(2)
2.47(4)
72.5(1)
P(2)–C(2)
C(2)–C(1)
P(1)–C(1)
P(1)–Ag(1)–P(2)
1.84(6)
1.91(8)
1.86(5)
96.1(5)
The IR spectra of these five complexes are very similar. Absorp-
tions characteristic of terminal B–H vibrations are exhibited at
2567, 2576, 2574 and 2570 cmꢁ1 for complexes 1–5, respectively,
which lie in the normal range for B–H vibrations of 2645–
2450 cmꢁ1 [37]. Also, all the B–H vibration absorptions for com-
plexes 1–5 are almost equal to that of the free ligand
(2586 cmꢁ1), indicating that the coordination of the metal to the
free ligand has no influence on the B–H group. The peak at
Complex 5
Ag(1)–S(1)
Ag(1)–P(1)
Ag(1)–P(2)
P(1)–C(2)
2.39(3)
2.46(3)
2.47(2)
1.83(9)
136.1(9)
P(2)–C(1)
C(1)–C(2)
S(1)–C(27)
S(1)–Ag(1)–P(1)
P(1)–Ag(1)–P(2)
1.85(9)
1.87(1)
1.77(1)
131.8(9)
92.0(8)
S(1)–Ag(1)–P(2)
1072 cmꢁ1 can be attributed to the absorption of
vC(Cycl)–P. The
The symmetry transformations used to generate equivalent atoms for complex 1: #
1 ꢁx + 1, ꢁy + 2, ꢁz; complex 2, # 1 ꢁx + 1, ꢁy + 1, ꢁz; complex 4, # 1 ꢁx + 1/2,
y + 1/2, ꢁz + 1/2.
absorption at approximate 736 cmꢁ1 shows the existence of the
deformation of the cage [24]. The absorptions centered at
Fig. 3. The zigzag chain in complex 1. The H atoms have been omitted for clarity.

L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
1473
1384 cmꢁ1 may be attributed to the vC–H scissoring vibration of the
3.4. Description of the crystal structures
CH2 group. A middle absorption at about 2088 cmꢁ1 for complex 2
should be attributed to the C„N bond of SCNꢁ.
3.4.1. The crystal structures of complexes 1 and 4
The crystal structures of complexes 1 and 4 are shown in Figs. 1
and 2, respectively, and selected bond lengths and angles are listed
in Table 2. Complexes 1 and 4 possess binuclear structures with a
rhomboid core consisting of two Ag atoms and two bidentate li-
gands. Each Ag atom has the same environment because com-
plexes 1 and 4 are centrosymmetric. The Ag atom is tetrahedrally
surrounded by two P atoms of the ligand and the other two donors
3.3. NMR spectra
All the complexes were characterized by 1H and 13C NMR spec-
troscopy. The 1H NMR (400.15 MHz) showed a resonance at ca.
1.25–2.69 ppm, which could be assigned to the H atoms of the
P(Cy2)2 group. In the 13C NMR spectra (100.63 MHz), the resonance
at ca. d = 26.0–40.0 ppm can be assigned to the carbon atom of the
cyclohexyl, and d = 78.0–76.0 ppm are the carborane cage C atoms
[38]. The 11B NMR spectra display a 3:3:4 splitting pattern for com-
plex 1, 1:1:1:2 for complexes 2, 3 and 5, and 1:4:5 for complex 4.
The 31P NMR spectra of complexes 1 and 2 showed a resonance at
45.66 and 45.60 ppm, respectively. The 31P NMR spectra display a
1:1 splitting pattern for complexes 3 and 5, and 1:1:1:1 for com-
plex 4.
are di-
l
-X bridged atoms (X = I or NO3). The conformation of the
-Cl)2{1,2-
two complexes are similar with the complex [Ag2(
l
(PPh2)2-1,2-C2B10H10}2] [39]. In complex 1, the Ag(1)–I(1) and
Ag(1)–P(1) bond lengths are 2.87(1) and 2.49 (3) Å, which agree
well with the corresponding bond lengths of 2.89(1) and
2.49(2) Å in the complex [Ag2I2(o-PP)] (o-PP = 1,2-Bis[(diphenyl
phosphino)methyl]benzene) [28]. The P–Ag–P angle is 92.2(1)° in
complex 1, which is slightly larger than the corresponding angle
(89.8(5)°) in the complex [Ag2(l-Cl)2{1,2-(PPh2)2-1,2-C2B10H10}2].
Fig. 4. Two-dimensional hexagonal grid of complex 1 formed by intermolecular C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions.
Fig. 5. The zigzag chain in complex 4 formed by intermolecular C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions.

1474
L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
In complex 4, the P–Ag–P angle is 96.1(5)°, which is larger than the
corresponding value of complex 1. This may result from the differ-
ence of the size of the atoms (I ꢂ O). A similar change of P–Ag–P
angles has also been observed in the previous literature [28]. The
distance of the Ag(1)–O(3) bond is 2.28(4) Å, which is shorter than
the corresponding bond reported for the complex [Ag2(NO3)2
(m-PP)] (2.47(2) Å, m-PP = 1,3-bis[(diphenylphosphino)methyl]
benzene) [30]. The orientation of the nitrates relative to the
Ag2O2 core is the same in complex 4, which is different from that
in the complex [Ag2(NO3)2(m-PP)].
Based on the dihydrogen bonds C(20)–H(20A)ꢀ ꢀ ꢀH(6)–B(6), the
structure of complex 1 can be better described as a two-dimen-
sional hexagonal grid wherein the bridged molecules [Ag2
(l-I)2{1,2-(PCy2)2-1,2-C2B10H10}2] are linked into a 1D chain
(Fig. 3). Adjacent chains are further cross-linked by the same
contacts giving rise to a 2D hexagonal grid-like sheet with intragrid
Fig. 6. The crystal structure of complex 2. The H atoms and solvent molecules have been omitted for clarity.
Fig. 7. Two-dimensional hexagonal grid of the complex 2 formed by intermolecular C-HꢀꢀꢀH-B dihydrogen bonding interactions.

L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
1475
Mꢀ ꢀ ꢀM separations of 10.21 and 16.28 Å (Fig. 4). In complex 4,
adjacent molecules are linked into 1D chain via C(18)–
H(18B)ꢀ ꢀ ꢀH(6)–B(6), as is shown in Fig. 5. The distance between
adjacent molecules is 14.73 Å. There are two dihydrogen bonds be-
tween adjacent molecules, which are parallel to each other.
one S atom, one N atom of SCN and the donor phosphorus atoms of
one ligand. The Ag atoms in the chain are alternately arranged
along zigzag chains, as shown in Fig. 6. Adjacent polymer chains
are assembled into a 2D hexagonal grid via C(16)–H(16B)ꢀ ꢀ ꢀH(6)–
B(6) interactions, as shown in Fig. 7. Every hexagonal grid includes
six Ag ions and each vertex contains one crystallographic Ag ion,
with Agꢀ ꢀ ꢀAg distances of 6.55, 11.40 and 12.56 Å. Being similar
to the above complexes, the dihydrogen bonds between adjacent
chains are parallel to each other.
a
3.4.2. The crystal structure of complex 2
The crystal structure of complex 2 is illustrated in Fig. 6, and se-
lected bond lengths and angles are listed in Table 2. The unit
[Ag{1,2-(PCy2)2-1,2-C2B10H10}] is linked to a 1D coordination poly-
mer chain by the SCN- ligands. The Ag atom is tetracoordinated by
3.4.3. The crystal structures of complexes 3 and 5
The crystal structures of complexes 3 and 5 are illustrated in
Figs. 8 and 9. Selected bond lengths and angles are listed in Table
2. A perspective view of the structural units of complexes 3 and
5 is displayed in Figs. 8 and 9, respectively. The Ag atom is three
coordinated, in which two positions are occupied by the chelating
closo diphosphine ligand 1,2-(PCy2)2-1,2-C2B10H10, and the other
ꢁ
ꢁ
one comes from the O atom of ClO4 or the S atom of SC6H4COOH .
In complexes 3 and 5, adjacent molecules are linked together into
one-dimensional zigzag chains via dihydrogen bonds, as shown in
Figs. 10 and 11.
On the whole, the Cc–Cc bond lengths (the carbon of the carbo-
rane skeleton) in the five complexes are 1.88(2), 1.88(7), 1.85(1),
1.91(8) and 1.87(3) Å, respectively, which are slightly larger than
the corresponding distance of 1.6911(10) Å in 1,2-(PCy cl2)2-1,2-
C2B10H10, suggesting that the coordination with the metal atom
has obvious influences on this distance. The P(1)–C(1)–C(2)–P(2)
torsion angles are only ꢁ1.5(12)°, 0.9(5)°, 0.5(10)°, 2.4(5)° and
0.4(9)° in the complexes 1–5, respectively, while the angle in the
free ligand is 10.9(4)°, indicating that the symmetry of the ligands
in the five complexes has obviously changed and approached C2v
symmetry [40]. Besides, the P(1)–C(1)–C(2)–P(2) torsion angles
in the complexes 1 and 4 are ꢁ1.5(12)° and 2.4(5)°, which are lar-
ger than the corresponding values in complexes 2 (0.9(5)°), 3
(0.5(10)°) and 5 (0.4(9)°). The bridged structures of complexes 1
and 4 also have a great influence on the torsion angles.
Fig. 8. The crystal structure of complex 3. The H atoms and solvent molecules have
been omitted for clarity.
3.5. Dihydrogen bond
Selected distances and angles for complexes 1–5 relating to the
intermolecular DHB are shown in Table 3. The distances of the two
Hꢀ ꢀ ꢀH interactions for complexes 1–5 range from 2.26 to 2.39 Å,
which are slightly shorter than the sum of the van der Waals radii
of
H
and
H
(2.4 Å) [17]. The distances of C(20)ꢀ ꢀ ꢀB(6) and
C(16)ꢀ ꢀ ꢀB(6) are 3.89 and 3.92 Å for complexes 1 and 2, which
are similar to the distances of Cꢀ ꢀ ꢀB (3.93, 3.94 and 3.91 Å)
for [Cu2(l
-X)2(1,2-(PiPr2)2-1,2-C2B10H10)2] (X = Cl, Br, I) [24].
The C(18)ꢀ ꢀ ꢀB(8) distance in complex 5 is 4.08 Å, which is similar
to the distances of 4.10 Å in [(C2B10H11
Cꢀ ꢀ ꢀB
)
C6H4(C2B10H10)C6H4(C2B10H11)] [41]. In complex 4, the
C(18)ꢀ ꢀ ꢀB(6) distance is 3.72 Å, which is slightly larger than the
C(6)ꢀ ꢀ ꢀB(180) distance, with the value of 3.59 Å, in the complex
8,90-[closo-{3-Co(
(163.5°) and the B–Hꢀ ꢀ ꢀH angle (134.3°) of C(18)–H(18A)ꢀ ꢀ ꢀH(8)–
g
5-C5H5)-1,2-C2B9H10}] [42]. The C–Hꢀ ꢀ ꢀH angle
Table 3
Selected distances (Å) and angles (°) of complexes 1–5 related to intermolecular
DHBs.
Complex C–Hꢀ ꢀ ꢀH–B
Hꢀ ꢀ ꢀH Cꢀ ꢀ ꢀB C–Hꢀ ꢀ ꢀH H–Hꢀ ꢀ ꢀB
1
2
3
4
5
C(20)–H(20A)ꢀ ꢀ ꢀH(6)–B(6)
2.32
2.36
2.39
3.89
3.92
3.69
3.72
4.08
4.28
147.8
139.7
110.5
130.4
163.5
163.8
114.4
133.3
116.8
132.5
134.3
174.6
C(16)–H(16B)ꢀ ꢀ ꢀH(6)–B(6)
C(8)–H(8B)ꢀ ꢀ ꢀH(10)–B(10)
C(18)–H(18 B)ꢀ ꢀ ꢀH(6)–B(6) 2.26
C(18)–H(18A)ꢀ ꢀ ꢀH(8)–B(8)
C(5)–H(5)ꢀ ꢀ ꢀH(3A)–B(3)
2.29
2.23
Fig. 9. The crystal structure of complex 5. The H atoms and solvent molecules have
been omitted for clarity.

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L.-G. Yang et al. / Polyhedron 30 (2011) 1469–1477
Fig. 10. The zigzag chain in complex 3 formed by intermolecular C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions.
Fig. 11. The zigzag chain in complex 5 formed by intermolecular C–Hꢀ ꢀ ꢀH–B dihydrogen bonding interactions.
B(8) in complex 5 are consistent with other typical DHBs described
as X–Hꢀ ꢀ ꢀH–M (X is a typical electronegative atom and M is a
transition metal or boron atom) [20].
Acknowledgements
This work was supported by the National Natural Science Foun-
dation of PR China (Project No. 20971063), the Natural Science
Foundation of Shandong Province (Y2007B01) and the Shandong
‘‘Tai-Shan Scholar Research Fund’’.
4. Conclusion
In this work, the reactions between the closo-carborane dicyclo-
hexylphosphine ligand 1,2-(PCy2)2-1,2-C2B10H10 and Ag(I) salts,
under the protection of dry N2 at room temperature, have been
investigated for the first time. Five silver carborane complexes
were obtained. The structure analyses of complexes 1–5 reveal that
the different coordination anions lead to different structures of
complexes 1–5. It was also found that C–Hꢀ ꢀ ꢀH–B contacts exist
in these five complexes. Because of the different orientations of
the DHBs, the complexes are linked into 1D and 2D supramolecular
structures via dihydrogen bonds.
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