Syntheses, structures and ligand conformations of Cu(II), Co(II) and Ag(I) complexes containing the phosphinic amide ligands

Article abstract of DOI:10.1016/j.poly.2011.10.022

The syntheses, structures and ligand conformations of the complexes trans-Cu(L1)₂(ClO₄)₂, (L1 = N-(2-pyrimidinyl)-P,P-diphenyl-phosphinic amide), 1, [trans-Co(L1) ₂(CH₃OH)₂](ClO₄)₂· O(C₂H₅)₂, 2, [trans-Co(L2)₂(H ₂O)₂](ClO₄)₂·2CH ₃OH, (L2 = N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide), 3, [cis-Co(L2)₂(NO₃)](NO₃), 4, and [Ag(L3)(NO ₃)(CH₃CN)]_∞, (L3 = N-(6-methyl-2- pyridinyl)-P,P-diphenyl-phosphinic amide), 5, are reported. The L1 and L2 ligands in the monomeric complexes 1-4 chelate the metal centers through the pyrimidyl/pyridyl nitrogen atoms and the phosphinic amide oxygen atoms, whereas the L3 ligands in complex 5 bridge the metal centers, forming a 1-D zigzag chain. The chelating L2 ligands in complexes 3 and 4 adopt cis conformations and the bridging L3 ligand in complex 5 adopts a trans conformation, respectively.

Full text of DOI:10.1016/j.poly.2011.10.022

Polyhedron 31 (2012) 657–664
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Polyhedron
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Syntheses, structures and ligand conformations of Cu(II), Co(II) and Ag(I)
complexes containing the phosphinic amide ligands
⇑
Chun-Wei Yeh, Keng-Han Chang, Chan-Yu Hu, Wayne Hsu, Jhy-Der Chen
Department of Chemistry, Chung-Yuan Christian University, Chung-Li, Taiwan, ROC
a r t i c l e i n f o
a b s t r a c t
Article history:
The syntheses, structures and ligand conformations of the complexes trans-Cu(L1)2(ClO4)2, (L1 = N-(2-
pyrimidinyl)-P,P-diphenyl-phosphinic amide), 1, [trans-Co(L1)2(CH3OH)2](ClO4)2ꢀO(C2H5)2, 2, [trans-
Co(L2)2(H2O)2](ClO4)2ꢀ2CH3OH, (L2 = N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide), 3, [cis-Co(L2)2
Received 10 September 2011
Accepted 19 October 2011
Available online 28 October 2011
(NO3)](NO3), 4, and [Ag(L3)(NO3)(CH3CN)]
, (L3 = N-(6-methyl-2-pyridinyl)-P,P-diphenyl-phosphinic
1
amide), 5, are reported. The L1 and L2 ligands in the monomeric complexes 1–4 chelate the metal centers
through the pyrimidyl/pyridyl nitrogen atoms and the phosphinic amide oxygen atoms, whereas the L3
ligands in complex 5 bridge the metal centers, forming a 1-D zigzag chain. The chelating L2 ligands in
complexes 3 and 4 adopt cis conformations and the bridging L3 ligand in complex 5 adopts a trans con-
formation, respectively.
Keywords:
Phosphinic amide
Conformation
Mononuclear complex
1-D zigzag chain
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
mous number of interesting supramolecular structures have been
reported, the control of structural dimensionality is still a chal-
The self-assembly of organic and inorganic molecules in the so-
lid state continues to be an active area of investigation because it
expands the range of new complexes with desired physical and
chemical properties [1–3]. Judicial choice of metal–ion templates
and organic ligands with diverse functionalities may lead to well-
defined supramolecular architectures including 1-D, 2-D or 3-D
networks [4–6]. Additionally, the structural types are also affected
by factors such as the metal-to-ligand ratio [7], counterion [8], sol-
vent [9] and the properties of the spacing ligand involving rigidity,
flexibility, length, size and geometry [9–11]. Although an enor-
lenge [12–15].
A series of complexes with the symmetric di(pyridyl/pyrim-
idyl)amide ligands [16–21] and the asymmetric methyl-4-(5-halo-
pyrimidin-2-ylcarbamoyl)benzoate ligands that exhibit interesting
structural types [22] have been synthesized and structurally charac-
terized by our group. These pyridyl/pyrimidyl amide ligands coordi-
nate to the metal centers through their pyridyl/pyrimidyl nitrogen
atoms and/or amide oxygen atoms and interact with each other
through hydrogen bonds involving the amide groups. These interac-
tions are important for molecular recognition and constructing
N
P
P
P
N
N
O
N
N
O
H3C
N
N
O
H
H
H
L1
L2
L3
⇑
Corresponding author. Tel.: +886 3 2653351; fax: +886 3 2653399.
E-mail address: jdchen@cycu.edu.tw (J.-D. Chen).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.10.022

658
C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
Table 1
Crystal data for complexes 1–5.
Compound
1
2
3
4
5
Formula
C
32H28Cl2CuN6O10P2
C38H46Cl2CoN6O13P2
986.58
monoclinic
C2/c
24.4050(10)
13.9337(6)
13.7701(6)
90
108.128(2)
90
4450.1(3)
4
1.473
2044
0.646
C36H42Cl2CoN4O14P2
946.51
C34H30CoN6O8P2
771.51
C20H20AgO4N4P
519.24
monoclinic
Cc
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
852.98
monoclinic
P21
9.7297(3)
18.2171(7)
10.5143(4)
90
98.127(2)
90
1844.91(11)
2
1.535
870
0.887
triclinic
triclinic
ꢀ
ꢀ
P1
P1
9.5973(2)
11.2904(2)
11.5231(2)
114.386(1)
96.378(1)
103.737(1)
1073.38(3)
1
12.0562(3)
12.2505(3)
13.3029(4)
84.041(1)
75.480(1)
76.280(2)
1845.68(9)
2
17.868(4)
13.837(2)
9.902(2)
90
118.472(15)
90
2152.1(7)
4
1.603
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g/cm3)
F (000)
1.464
489
0.667
1.388
794
0.609
1048
1.045
l
(MoKa
) (mmꢂ1
)
Range(2h) for data
collection (°)
3.96 6 2h 6 56.88
3.40 6 2h 6 58.96
4.00 6 2h 6 56.62
3.42 6 2h 6 56.58
5.08 6 2h 6 55.00
Limiting indices
ꢂ13 6 h 6 12,
ꢂ24 6 k 6 24,
ꢂ14 6 l 6 14
9187 [0.0608]
ꢂ32 6 h 6 32,
ꢂ18 6 k 6 18,
ꢂ18 6 l 6 18
5554 [0.0977]
ꢂ12 6 h 6 12,
ꢂ15 6 k 6 15,
ꢂ15 6 l 6 15
5322 [0.0245]
ꢂ15 6 h 6 16,
ꢂ16 6 k 6 15,
ꢂ17 6 l 6 15
9043 [0.0408]
ꢂ23 6 h 6 23,
ꢂ17 6 k 6 17,
ꢂ12 6 l 6 12
3259 [0.0119]
Independent
reflections (Rint
Data/restraints/
parameters
)
9187/1/478
5554/2/314
5322/0/281
9043/0/460
3259/2/278
GOF indicatorc
Final R indices
[I > 2(I)]a,b
0.929
1.006
1.013
0.961
1.038
R1 = 0.0349, wR2 = 0.0738
R1 = 0.0564, wR2 = 0.1455
R1 = 0.0366, wR2 = 0.0876
R1 = 0.0460, wR2 = 0.0924
R1 = 0.0248, wR2 = 0.0625
R indices (all data)
R1 = 0.0573, wR2 = 0.0795
R1 = 0.1217, wR2 = 0.1652
R1 = 0.0563, wR2 = 0.0982
R1 = 0.0966, wR2 = 0.1042
R1 = 0.0258, wR2 = 0.0633
a
R1
wR2 = [
=
R
||Fo| ꢂ |Fc||/
R|Fo|.
b
2
2
R
w(Fo ꢂ Fc2)2/
R r
w(Fo2)2]1/2. w = 1/[ 2(Fo2) + (ap)2 + (bp)], p = [max(Fo or 0) + 2(Fc2)]/3. a = 0.0404, b = 0 for 1, i = 0.0783, b = 0 for 2, a = 0.0462, b = 0.4159 for 3,
a = 0.0488, b = 0 for 4, a = 0.0259, b = 1.7904 for 5.
c
Quality-of-fit = [
R
w(|Fo2| ꢂ |Fc2|)2/(Nobserved ꢂ Nparameters)]1/2
.
supramolecular arrays. Recently, we have reported the coordination
chemistry of the N-(4-methyl-2-pyrimidinyl)-P,P-diphenyl-phos-
phinic amide (L0) ligand, which coordinates to the metal center
throughthe pyrimidylnitrogen atomsand phosphinic amide oxygen
atoms, and three different ligand conformations were observed for
the L0 ligands [23]. With this background information, we sought
to investigate the coordination chemistry of the phosphinic amide
ligands with the nitrogen donors located in different positions. We
prepared a series of ligands: N-(2-pyrimidinyl)-P,P-diphenyl-phos-
phinic amide (L1), N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide
(L2), and N-(6-methyl-2-pyridinyl)-P,P-diphenyl-phosphinic amide
(L3). Each of these ligands was then reacted with various metal salts.
Herein, we report the syntheses, structures and ligand conforma-
tions of five new metal complexes containing these phosphinic
amide ligands: trans-Cu(L1)2(ClO4)2, 1, [trans-Co(L1)2(CH3OH)2](-
ClO4)2ꢀO(C2H5)2, 2, [trans-Co(L2)2(H2O)2](ClO4)2ꢀ2CH3OH, 3, [cis-
Thermal gravimetric analysis (TGA) was performed with a Thermal
Analysis TGA-2050.
2.2. Materials
The reagents Cu(ClO4)2ꢀ6H2O, Co(ClO4)2ꢀ6H2O, Co(NO3)2ꢀ6H2O
and AgNO3 were purchased from Aldrich Co. and used as received.
The ligands, N-(2-pyrimidinyl)-P,P-diphenyl-phosphinic amide
(L1), N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide (L2) and N-
(6-methyl-2-pyridinyl)-P,P-diphenyl-phosphinic amide (L3) were
prepared according to known procedures [24].
2.3. Preparation
2.3.1. trans-Cu(L1)2(ClO4)2, (1)
Co(L2)2(NO3)](NO3), 4 and [Ag(L3)(NO3)(CH3CN)] , 5, which were
1
L1 (0.59 g, 2.0 mmol) was placed in a flask containing 20 mL
CH3OH and Cu(ClO4)2ꢀ6H2O (0.37 g, 1.0 mmol) was added. The
mixture was then stirred at room temperature for 24 h to afford
a blue solution with some pale yellow solid. The solid was filtered
and then diethyl ether added to introduce precipitation. The pre-
cipitate was filtered and washed with diethyl ether (2 ꢁ 10 mL)
and then dried under vacuum to give the blue powder. Yield:
0.21 g (25% based on Cu). Anal. Calc. for C32H28CuCl2N6O10P2
(MW = 851.00), C, 45.12; H, 3.32; N, 9.87. Found: C, 45.07; H,
3.31; N, 9.85%. IR data (cmꢂ1): 3095(w), 3039(w), 2940(w),
2860(w), 2803(w), 2738 (w), 2360(w), 1602(s), 1571(m), 1487(s),
1338(w), 1260(w), 1186(w), 1150(s), 1109(s), 1058(s), 996(w),
980(w), 958(m), 842(w), 808(w), 794(w), 751(w), 734(m),
694(m), 645(w), 623(m), 568(m), 543(m), 515(w). The blue crys-
tals were obtained by slow diffusion of diethyl ether into a meth-
anol solution of the compound for several weeks.
characterized by single crystal X-ray crystallography.
2. Experimental
2.1. General procedures
All manipulations were carried out under dry, oxygen-free
nitrogen using Schlenk techniques unless otherwise noted. Sol-
vents were dried and deoxygenated by refluxing over the appropri-
ate reagents before use. Diethyl ether was purified by distillation
from sodium/benzophenone, CH3OH from Mg/I2 and CH3CN from
CaH2. IR spectra (KBr disk) were obtained from a Jasco FT/IR-460
plus spectrometer. Elemental analyses were obtained from a PE
2400 series II CHNS/O analyzer or a HERAEUS VaruoEL analyzer.

C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
659
Table 2
Selected bond distances (Å) and angles (°) for complexes 1–5.
Complex 1
Distances
Cu–O(1)
Cu–N(4)
Cu–O(6)
P(1)–O(1)
1.929(2)
2.048(2)
2.482(2)
1.505(2)
Cu–O(2)
Cu–N(1)
Cu–O(10)
P(2)–O(2)
1.932(2)
2.055(2)
2.592(3)
1.502(2)
Angles
O(1)–Cu–O(2)
O(2)–Cu–N(4)
O(2)–Cu–N(1)
O(6)–Cu–N(1)
O(6)–Cu–O(1)
O(6)–Cu–O(10)
N(4)–Cu–O(10)
O(2)–Cu–O(10)
178.9(1)
91.8(1)
88.3(1)
95.8(1)
87.9(1)
179.1(1)
94.9(1)
86.5(1)
O(1)–Cu–N(4)
O(1)–Cu–N(1)
N(4)–Cu–N(1)
O(6)–Cu–N(4)
O(6)–Cu–O(2)
N(1)–Cu–O(10)
O(1)–Cu–O(10)
87.4(1)
92.6(1)
178.5(1)
85.7(1)
92.8(1)
83.6(1)
92.8(1)
Complex 2a
Distances
Co–O(1)
Fig. 1. Coordination environment about the Cu(II) center of 1. The hydrogen atoms
are omitted for clarity.
2.049(2)
2.241(2)
Co–O(2)
P–O(1)
2.062(2)
1.495(2)
Co–N(1)
Angles
O(1A)–Co–O(1)
O(1)–Co–O(2)
O(1)–Co–O(2A)
N(1A)–Co–N(1)
O(2)–Co–N(1A)
O(1A)–Co–N(1)
180.0(1)
91.4(1)
88.6(1)
180.0
86.7(1)
88.3(1)
O(1A)–Co–O(2)
O(2)–Co–O(2A)
O(1)–Co–N(1A)
O(1)–Co–N(1)
O(2A)–Co–N(1)
O(2)–Co–N(1)
88.6(1)
180.0
88.3(1)
91.7(1)
86.7(1)
93.3(1)
(45% based on Co). Anal.
Calc. for
C34H36CoCl2N6O12P2
(MW = 911.06), C, 44.78; H, 3.98; N, 9.22. Found: C, 44.75; H,
3.94; N, 9.42%. IR data (cmꢂ1): 3411(br), 2939(w), 2866(w),
1677(w), 1593(m), 1579(m), 1475(m), 1437(s), 1261(w), 1159(s),
1097(s), 997(w), 950(m), 830(w), 799(w), 754(m), 733(m),
694(m), 623(m), 557(m), 539(m), 515(w).
Complex 3b
Distances
Co–O(1)
2.048(1)
2.083(2)
Co–N(1)
P–O(1)
2.243(2)
1.494(1)
2.3.3. [trans-Co(L2)2(H2O)2](ClO4)2ꢀ2CH3OH, (3)
Co–O(2)
The complex was prepared using the procedure described for 1
except L2 (0.59 g, 2.0 mmol) and Co(ClO4)2ꢀ6H2O (0.36 g,
1.0 mmol) were used. Yield: 0.51 g (54% based on Co). Anal. Calc.
for C36H42Cl2CoN4O14P2 (MW = 946.53), C, 45.68; H, 4.47; N, 5.92.
Found: C, 45.98; H, 4.77; N, 5.62%. IR data (cmꢂ1): 3667(w),
3562(w), 3502(m), 3269(m), 2001(m), 1607(m), 1458(s),
1395(m), 1237(m), 1158(s), 1106(s), 938(m0, 824(m), 779(m),
739(m), 695(m), 628(m), 542(w).
Angles
O(1)–Co–O(1A)
O(1)–Co–O(2)
O(1)–Co–O(2A)
O(1)–Co–N(1)
O(1A)–Co–N(1)
O(2A)–Co–N(1)
180.0(1)
90.7(1)
89.3(1)
91.0(1)
89.0(1)
88.0(1)
O(2)–Co–O(2A)
N(1)–Co–N(1A)
O(1A)–Co–O(2)
O(2)–Co–N(1)
O(1)–Co–N(1A)
O(2)–Co–N(1A)
180.0(1)
180.0(1)
89.3(1)
92.0(1)
89.0(1)
88.0(1)
Complex 4
Distances
Co–O(1)
Co–O(3)
Co–N(3)
P(1)–O(1)
2.013(2)
2.168(2)
2.189(2)
1.500(2)
Co–O(2)
Co–N(1)
Co–O(4)
P(2)–O(2)
2.016(1)
2.170(2)
2.192(2)
1.499(2)
2.3.4. [cis-Co(L2)2(NO3)](NO3), (4)
The complex was prepared using the procedure described for 3
except Co(NO3)2ꢀ6H2O (0.29 g, 1.00 mmol) was used. Yield: 0.56 g
(73% based on Co). Anal. Calc. for C34H30CoN6O8P2 (MW = 771.51),
C, 52.93; H, 3.92; N, 10.89. Found: C, 52.98; H, 3.57; N, 10.61%. IR
data (cmꢂ1): 3420(m), 3083(s), 2922(m), 2839(m), 2360(m),
1999(m), 1905(m), 1826(m), 1775(m), 1608(s), 1467(s), 1390(m),
1309(s), 1235(m), 1141(m), 1099(m), 1024(m), 952(s), 820(m),
782(m), 739(s), 694(m), 633(s), 542(m), 424(m).
Angles
N(3)–Co–O(4)
O(1)–Co–O(3)
O(1)–Co–N(1)
O(3)–Co–N(1)
O(2)–Co–N(3)
N(1)–Co–N(3)
O(2)–Co–O(4)
N(1)–Co–O(4)
88.1(1)
88.8(1)
92.3(1)
91.5(1)
91.9(1)
177.5(1)
96.7(1)
90.4(1)
O(1)–Co–O(2)
O(2)–Co–O(3)
O(2)–Co–N(1)
O(1)–Co–N(3)
O(3)–Co–N(3)
O(1)–Co–O(4)
O(3)–Co–O(4)
115.9(1)
155.2(1)
86.2(1)
90.0(1)
89.5(1)
147.4(1)
58.6(1)
Complex 5c
Distances
Ag–N(3)
Ag–O(1A)
Ag–O(2)
2.3.5. [Ag(L3)(NO3)(CH3CN)] , (5)
1
L3 (0.31 g, 1.00 mmol) was placed in a flask containing 25 mL
CH3CN and AgNO3 (0.17 g, 1.00 mmol) was added. The mixture
was then stirred at room temperature for 24 h and afforded a yel-
low solution with some yellow solid. The solution was filtered and
then diethyl ether was added to introduce precipitation. The pre-
cipitate was filtered and washed with diethyl ether (2 ꢁ 10 mL)
and then dried under vacuum to give the yellow product. Yield:
2.265(4)
2.440(2)
2.544(5)
Ag–N(1)
Ag–O(3)
P–O(1)
2.353(3)
2.525(4)
1.494(2)
Angles
N(3)–Ag–O(1A)
N(3)–Ag–O(3)
O(1A)–Ag–O(3)
N(1)–Ag–O(2)
O(3)–Ag–O(2)
121.9(11)
118.3(2)
87.5(1)
90.1(2)
48.8(1)
N(3)–Ag–N(1)
N(1)–Ag–O(1A)
N(1)–Ag–O(3)
N(3)–Ag–O(2)
O(1A)–Ag–O(2)
127.3 (1)
94.3(1)
98.4(1)
87.9(2)
136.2(1)
0.34 g (65% based on Ag). Anal. Calc. for
C20H20AgN4O4P
(MW = 519.24): C, 46.26; H, 3.88; N, 10.79. Found: C, 46.10; H,
3.51; N, 10.62%. IR (cmꢂ1): 3352(w), 3039(b), 2743(m), 2390(m),
1972(w), 1904(m), 1833(m), 1666(s), 1528(w), 1384(m), 1257(s),
1122(m), 1008(m), 900(m), 765(s), 697(s), 622(m), 546(w),
510(w), 459(w). Colorless crystals were obtained by slow diffusion
of diethyl ether into a CH3CN solution of complex 5 for several
weeks.
a
b
c
Symmetry code (A): ꢂx + 1/2, ꢂy + 1/2, ꢂz.
Symmetry code (A): ꢂx, ꢂy, ꢂz.
Symmetry code (A) x, ꢂy + 2, z + 1/2.
2.3.2. [trans-Co(L1)2(CH3OH)2](ClO4)2ꢀO(C2H5)2, (2)
The complex was prepared using the procedure described for 1,
except Co(ClO4)2ꢀ6H2O (0.36 g, 1.0 mmol) was used. Yield: 0.43 g

660
C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
Fig. 2. Coordination environment about the Co(II) center of 2. The hydrogen atoms are omitted for clarity. Symmetry transformations used to generate equivalent atoms: (A)
ꢂx + 1/2, ꢂy + 1/2, ꢂz.
Fig. 3. Coordination environment about the Co(II) center of 3. The hydrogen atoms are omitted for clarity. Symmetry transformations used to generate equivalent atoms are
(A) ꢂx, ꢂy, ꢂz.
2.4. X-ray crystallography
pertaining to crystal parameters and structure refinement is sum-
marized in Table 1. Selected bond distances and angles are listed in
Table 2.
The diffraction data for 1 and 2 were collected on a Bruker Kap-
pa APEX II diffractometer and those for 3 and 4 on a Bruker APEX II
CCD diffractometer at 22 °C, while that of 5 was collected on a Bru-
ker AXS P4 diffractometer at 22 °C. Each was equipped with a
3. Results and discussion
graphite-monochromated MoK
a
(k = 0.71073 Å) radiation source.
a
3.1. Syntheses and spectroscopic studies
Data reduction was carried by standard methods with the use of
well-established computational procedures [25,26]. The structure
factors were obtained after Lorentz and polarization correction.
An empirical absorption correction based on a series of ‘‘multi-
scan’’ was applied to the data for complexes 1–4, whereas the
The reactions of N-(2-pyrimidinyl)-P,P-diphenyl-phosphinic
amide (L1) and N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide
(L2) with Cu(ClO4)2ꢀ6H2O, Co(ClO4)2ꢀ6H2O and Co(NO3)2ꢀ6H2O in
CH3OH afforded the mononuclear complexes trans-Cu(L1)2(ClO4)2,
1, [trans-Co(L1)2(CH3OH)2](ClO4)2ꢀO(C2H5)2, 2, [trans-Co(L2)2
(H2O)2](ClO4)2ꢀ2CH3OH, 3 and [cis-Co(L2)2(NO3)](NO3), 4, while the
reaction of N-(6-methyl-2-pyridinyl)-P,P-diphenyl-phosphinic am
ide (L3) with AgNO3 in CH3CN gave the 1-D zigzag chain
empirical absorption correction based on
w-scans was applied to
the data for complex 5. The positions of some of the heavier atoms
were located by direct methods and the remaining atoms were lo-
cated from difference Fourier maps calculated after least-square
refinements [27]. For complex 3, the H atoms of the water and
methanol molecules, H2WA, H2WB and H7O, were located in the
difference electron density map and refined isotropically, while
the other hydrogen atoms in 1–5 were added by using the HADD
[Ag(L1)(NO3)(CH3CN)] , 5. These complexes were characterized by
1
elemental analysis and IR spectra, and their structures were deter-
mined by X-ray crystallography. The IR spectra of the free ligands,
L1, L2 and L3, show the absorptions for the P@O stretches at 1234,
1230 and 1233 cmꢂ1, respectively, which have higher energies than
those at 1150, 1159, 1158, 1141 and 1122 cmꢂ1, respectively for
complexes 1–5 indicating the phosphinic amide oxygen atoms are
coordinated to the metal ions.
ꢂ
program. The oxygen atoms (O3, O4, O5 and O6) from the ClO4
anion (occupancy of 0.5 and 0.5) in complex 2 and the O2 atom
ꢂ
from the NO3 anion (occupancy of 0.15 and 0.85) in complex 5
were found to be disordered over two positions. Basic information

C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
661
Fig. 4. (a) Coordination environment about the Co(II) center of 4, showing the
D
configuration. The hydrogen atoms are omitted for clarity. (b) The molecules form dimers
through intermolecular C–Hꢀ ꢀ ꢀ
p interactions (green dash). (Color online)
3.2. Structure of 1
oxygen atom [Cu–O = 2.04ꢂ8 (2) and 2.055 (2) Å]; it is also coordi-
nated by two trans ClO4 anions [Cu–O = 2.482 (2) and 2.592
(3) Å], Fig. 1. The calculated T value for the Cu(II) center in 1 is
0.79, indicating a distorted tetragonal bipyramidal geometry as
shown by Hathaway and Hodgson [28]. The long Cu–O distances
in the axial positions are presumably due to the weak coordination
The structure of trans-Cu(L1)2(ClO4)2, 1, was solved in the space
group P21 with two molecules in the unit cell. The Cu(II) center is
chelated by two trans L1 ligands through the pyrimidyl nitrogen
atom [Cu–N = 2.048 (2) and 2.055 (2) Å] and the phosphinic amide

662
C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
ꢂ
Fig. S2. Anion–
the pyrimidyl groups of the L1 ligands are also observed. The
distance of 3.217 (1) Å is shorter than the sum of the Paul-
p interactions [31] between the ClO4 anions and
Oꢀ ꢀ ꢀp
ing’s value for the half thickness of a phenyl ring (1.85 Å) [29]
and the van der Waals radius of O (1.52 Å) [30], which is 3.37 Å.
3.4. Structure of 3
The structure of [trans-Co(L2)2(H2O)2](ClO4)2ꢀ2CH3OH, 3, was
ꢀ
solved in the space group P1. Fig. 3 depicts the environment about
the Co(II) center. The Co(II) metal center adopts a slightly distorted
octahedral coordination geometry with the bond angles deviating
slightly from 90° or 180°. The Co(II) atom is chelated by two trans
L2 ligands through the pyridyl nitrogen atoms [Co–N = 2.243 (2) Å]
and the phosphinic amide oxygen atoms [Co–O = 2.048 (1) Å]. It is
further coordinated by two trans water molecules through their
oxygꢂen atoms [Co–O = 2.083 (2) Å]. The [Co(L2)2(H2O)2]2+ cations,
ClO4 anions and methanol molecules are interlinked through a
series of O–Hꢀ ꢀ ꢀO [Oꢀ ꢀ ꢀO = 2.65 (1)–2.89 (1) Å] and N–Hꢀ ꢀ ꢀO
[Nꢀ ꢀ ꢀO = 2.965 (1) Å] hydrogen bonds and form 1-D supramolecu-
lar chains, Fig. S3.
3.5. Structure of 4
The structure of [cis-Co(L2)2(NO3)](NO3), 4, was solved in the
ꢀ
space group P1 with two molecules in the unit cell. Fig. 4a depicts
the environment about the Co(II) center. The Co(II) metal center is
chelated by two cis L2 ligands through the pyridyl nitrogen atoms
[Co–N = 2.170 (2) and 2.189 (2) Å] and the phosphinic amide oxy-
gen atoms [Co–O = 2.013 (2) and 2.016 (1) Å] and is also chelated
ꢂ
by the NO3 anion [Co–O = 2.168 (2) and 2.170(2) Å, \O–Co–
Fig. 5. (a) Coordination environment about the Ag(I) center of 5. The hydrogen
atoms are omitted for clarity. Symmetry transformations used to generate
equivalent atoms are (A) x, ꢂy + 2, z + 1/2. (b) A view of the 1-D zigzag chain
running along the c-axis.
O = 58.63 (6)°], resulting in a distorted octahedral geometry.
Noticeably, the two pyridyl atoms are trans to each other, while
the two phosphinic oxygen atoms are cis to each other. This result
is in contrast to complexes 1–3 in which the two pyrimidyl/pyridyl
nitrogen atoms and the two phosphinic oxygen atoms are all trans
to each other. Because the Co(II) metal center is chelated by two L2
ligands and one nitrate anion, the [Co(L2)2(NO3)]+ cation is chiral.
ability of the ClO4ꢂ anion and the d9 electronic configuration of the
Cu(II) ion that results in strong Jahn-Teller distortion. The mole-
cules of 1 are interlinked through a series of self-complementary
donor–acceptor (DA) double N–Hꢀ ꢀ ꢀN hydrogen bonds
[Nꢀ ꢀ ꢀN = 2.12 (1) and 2.15 (1) Å] to form 1-D supramolecular tapes
The structure shown in Fig. 4(a) adopts a
the crystal conforms to the centrosymmetric space group P1, the
molecule with
configuration is coexistent. The [Co(L2)2(NO3)]+
= 2.774 (1) Å] interac-
D configuration. Because
ꢀ
K
cations form dimers through C–Hꢀ ꢀ ꢀ
p
[Hꢀ ꢀ ꢀ
p
(see Fig. S1 in the Supplementary data). Intermolecular C–Hꢀ ꢀ ꢀ
p
tions between the phenyl hydrogen atoms and the phenyl rings, Fig
4b, which are also interlinked by the nitrate anions through N–
Hꢀ ꢀ ꢀO [Nꢀ ꢀ ꢀO = 2.87 (1)–3.23 (1) Å] hydrogen bonds, Fig. S4.
short contacts between pyrimidyl/phenyl hydrogen atoms and
the phenyl rings [Hꢀ ꢀ ꢀ = 2.54 (1)–2.89 (1) Å] are also observed.
distances are shorter than the sum of the Pauling’s va-
p
These Hꢀ ꢀ ꢀ
p
lue for the half thickness of a phenyl ring (1.85 Å) [29] and the van
3.6. Structure of 5
der Waals radius of H (1.20 Å) [30], which is 3.05 Å.
The structure of [Ag(L3)(NO3)(CH3CN)] , 5, was solved in the
1
3.3. Structure of 2
space group Cc with four molecules in the unit cell. As illustrated
in Fig. 5a, the Ag(I) ion is coordinated by one pyridyl nitrogen atom
[Ag–N = 2.353 (3) Å], one phosphinic amide oxygen atom [Ag–
O = 2.440 (2) Å], two oxygen atoms from the chelating nitrate an-
ion [Ag–O = 2.525 (4) and 2.544 (5) Å, \O–Ag–O = 48.78 (13)°]
and one nitrogen atom from a bonded CH3CN molecule [Ag–
N = 2.265 (4) Å], resulting in a distorted square pyramidal geome-
The structure of [trans-Co(L1)2(CH3OH)2](ClO4)2ꢀO(C2H5)2, 2,
was solved in the space group C2/c with four molecules in the unit
cell. Fig. 2 depicts the environment about the Co(II) center. The co-
balt metal center adopts a slightly distorted octahedral coordina-
tion geometry with the bond angles deviating slightly from 90°
or 180°. The Co(II) atom is chelated by two trans L1 ligands through
the pyrimidyl nitrogen atoms [Co–N = 2.241(2) Å] and the phos-
phinic amide oxygen atoms [Co–O = 2.049(2) Å]. Also, two trans
oxygen atoms [Co–O = 2.062(2) Å] from two methanol molecules
coordinate the cobalt center resulting in a distꢂorted octahedral
geometry. The [Co(L1)2(CH3OH)2]2+ cations, ClO4 anions and the
diethyl ether molecules are interlinked through a series of O–
try with a
s value [32] of 0.15. Fig. 5b shows the 1-D zigzag chain
running along the c axis, in which the Agꢀ ꢀ ꢀAg distance separated
by the bridging L3 ligands is 6.371 (1) Å. The polymeric chains
are supported by the N–Hꢀ ꢀ ꢀO hydrogen bonds between the amine
hydrogen atoms and the phosphinic amide oxygen atoms
[Hꢀ ꢀ ꢀO = 2.13 (1) Å, \N–Hꢀ ꢀ ꢀO = 161.9 (2)°], which are also inter-
linked through weak C–Hꢀ ꢀ ꢀO [Cꢀ ꢀ ꢀO = 3.205 (9)–3.441 (8) Å]
hydrogen bonds between phenyl/pyridyl hydrogen atoms and the
oxygen atoms of the nitrate anions, Fig. S5.
Hꢀ ꢀ ꢀO [Oꢀ ꢀ ꢀO = 2.75 (1) Å] hydrogen bonds and C–Hꢀ ꢀ ꢀ
p interac-
tions [Hꢀ ꢀ ꢀ = 2.85 (1) Å] to form 1-D supramolecular tapes,
p

C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
663
N
N
N
N
N
H
N
N
H
N
H
N
CH3
N
O
P
N
N
H3C
N
R
N
H
P
P
P
H3C
N
R
N
H
O
N
N
H
O
O
N
O
P
N
N
H
P
N
H
O
R
N
N
H
cis
trans
aligned
Fig. 6. The three possible conformations for 2,20-dipyridylamine (top), L0 (middle), L2 (R = H) and L3 (R = CH3) (bottom).
3.8. Structural comparisons
Table 3
Dihedral angles (°), torsion angles (°) and ligand conformations for the L1, L2, L3 and
An interesting comparison can be made between complexes 1–
5 and [Zn(L0)Cl2]1 and Co3(L0)4Br6 [23]. The L1 and L2 ligands in 1–
4 chelate the metal centers to form monomeric complexes and the
L3 ligand in 5 and the L0 ligand in [Zn(L0)Cl2]1 bridge the metal
centers to form 1-D polymeric chains, while the L0 ligands in
Co3(L0)4Br6 chelate and bridge the metal centers, resulting in a tri-
meric complex. Noticeably, the pyrimidyl group of the L0 ligands in
Co3(L0)4Br6 and [Zn(L0)Cl2]1 coordinate to the metal centers
through the less crowded pyrimidyl nitrogen atoms, whereas the
pyridyl nitrogen atom of L3 that is adjacent to the methyl group
is forced to coordinate to the metal ion. In addition to the different
bonding modes and ligand conformations observed, the neutral
phosphinic amide ligands, L1, L2, L3 and L0 in each complex are
not flat but twisted around the C–P and C–N bonds. Table 3 lists
the torsional angles of the phosphinic amide groups, the dihedral
angles between the phenyl rings and the pyridyl/pyrimidyl rings
of these ligands and their conformations.
L0 ligands of the metal complexes.
Complex
1
Dihedral anglea Torsion angleb Conformation Reference
66.9, 83.2,
74.6, 79.8
66.4, 71.8
83.1, 83.2
69.9, 71.4,
59.4, 88.9
44.6, 88.9
61.6, 88.5
41.4, 70.8
30.0, 81.3
122.6(3),
125.0(2)
118.6(3)
123.3(1)
116.5(1),
128.9(1)
119.3(3)
126.1(5)
101.0(2),
120.5(3)
this work
2
3
4
this work
this work
this work
cis
cis,
cis
trans
trans
cis,
5
this work
23
23
c
[Zn(L0)Cl2]1
c
Co3(L0)4Br6
trans
a
b
c
Dihedral angle between the phenyl and pyridine/pyrimidine rings.
Torsion angle in the O@P–N–H phosphinic amide group.
L0 = N-(4-methyl-2-pyrimidinyl)-P,P-diphenyl-phosphinic amide.
3.7. Conformation of ligands L1, L2 and L3
3.9. Thermal analyses
A great effort has been made in investigating the coordination
between various metal ions and the bis(2-pyridyl)amine (Hdpa) li-
gand and its anion (dpaꢂ). Three types of conformations were
found for these ligands, Fig. 6 (top). In the bidentate mode of coor-
dination, the two pyridyl nitrogen atoms are arranged in a cis con-
formation, as shown in a previously described copper(II) complex
[33], while the trans conformation was found in the crystal struc-
ture of the free Hdpa ligand [34]. The aligned conformation, in
which the three nitrogen atoms are arranged in a near linear array
for coordination to the metal atoms, has been found for the dpaꢂ
ligands in several linear trinuclear complexes [35]. The free L0 li-
gands and those in the complexes [Zn(L0)Cl2]1 and Co3(L0)4Br6
[23] also show these three conformations, Fig. 6 (middle). Accord-
ingly, on the basis of the relative orientations of the pyridyl nitro-
gen atom, the amide nitrogen atom and the amide oxygen atom,
the L2 and L3 ligands can possibly show three conformations in
the solid state, Fig. 6 (bottom). Based on this descriptor, the L2 li-
gands in complexes 3 and 4 adopt the cis conformation, while the
L3 ligand in complex 5 adopts the trans conformation. However,
because the environments of the two pyrimidyl nitrogen atoms
of L1 are the same, the conformations of the L1 ligands in 1 and
2 can not be determined.
Thermal gravimetric analyses (TGA) were carried out to exam-
ine the thermal stabilities of 1–5, Fig. S6. The samples were heated
up in air with a heating rate of 10 °C minꢂ1. The TGA curve of 1
shows the first weight loss of 12.0% (Calc. 11.7%) from 140 to
ꢂ
170 °C, which can be ascribed to the removal of one bonded ClO4
anion. The second weight loss of 11.3% (Calc. ꢂ11.7%) from 180 to
230 °C is due to the removal of the other ClO4 anion. The weight
loss in the range 230–360 °C is consistent with the removal of the
L1 ligands. The TGA curve of 2 shows a weight loss of 13.9% (Calc.
14.0%) from 75 to 150 °C, corresponding to the removal of lattice
diethyl ether and methanol molecules. A second weight loss oc-
curred in the range 170–225 °C, consistent with the removal of
ꢂ
the ClO4 anions (calcd. 20.2%, obs. 19.8%). The weight loss from
225 to 355 °C corresponds to the removal of the L1 ligands. Com-
plex 3 shows the loss of the methanol and water molecules in
the range 80–160 °C (Calc. 10.6%, obs. 10.8%) followed by the loss
ꢂ
of the ClO4 anions in the range 160–235 °C (Calc. 21.0%, obs.
20.8%). The weight loss from 235 to 360 °C is consistent with the
removal of ꢂthe L2 ligands. The TGA curve of 4 shows the weight
loss of NO3 anions (Calc. 16.0%, obs. 16.1%) and two L2 ligands
in the ranges 130–180 and 230–357 °C, respectively. Complex 5

664
C.-W. Yeh et al. / Polyhedron 31 (2012) 657–664
shows the loss ofꢂthe bonded CH3CN molecule (Calc. 7.9%, obs.
7.7%) and the NO3 anions (Calc. 11.9%, obs. 12.0%) in the ranges
118–144 °C and 260–290 °C, respectively. The weight loss from
290 to 355 °C is consistent with the removal of the L3 ligands.
The residual product weights of 8.5%, 7.5%, 7.3%, 8.9% and 21.1%
for 1–5 were finally found above 360 °C, corresponding to the for-
mation of the metal oxides (CuO, calcd. 9.3% for 1; CoO Calc. 7.6%,
7.9% and 9.7% for 2–4 and Ag2O Calc. 22.3% for 5).
can be obtained free of charge via http://www.ccdc.cam.ac.uk/con-
ts/retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223
336 033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.poly.2011.10.022.
References
The TGA results show that the solvent molecules were removed
at higher temperatures than their corresponding boiling points,
and this result indicates that the solvent molecules are stabilized
in the structures. In complex 5, the L3 ligands were removed at
temperatures above 290 °C, which are higher than those for the
L1 and L2 ligands in complexes 1–4. This result suggests that the
structure of the 1-D polymeric chain of 5 is more thermally stable
than those of the 0-D monomeric complexes, 1–4. Additionally, the
TGA results show that complexes 1–5, which contain the phosphi-
nic amide ligands, are thermally stable and the L1, L2 and L3 li-
gands decomposed at temperatures above 225 °C.
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In this study, the coordination chemistry of five new complexes
containing the phosphinic amide ligands L1, L2 and L3 has been
successfully accomplished. These ligands coordinate to the metal
ions through the pyridyl/pyrimidyl nitrogen atom and the phosphi-
nic amide oxygen atom. The L2 ligands in complexes 3 and 4 adopt
the cis conformation resulting in six-membered chelating rings and
mononuclear structures, while the L3 ligands in 5 adopt the trans
conformation and bridge the metal ions to form a 1-D zigzag chain.
C–Hꢀ ꢀ ꢀ
p
and anion–
p
interactions as well as N–Hꢀ ꢀ ꢀN, N–Hꢀ ꢀ ꢀO, O–
Hꢀ ꢀ ꢀO and C–Hꢀ ꢀ ꢀO hydrogen bonds were found in complexes 1–5,
which extend the dimensionalities of their corresponding struc-
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We are grateful to the National Science Council of the Republic
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Appendix A. Supplementary data
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CCDC 840540, 840541, 840542, 840543, 840544 contains the
supplementary crystallographic data for 1, 2, 3, 4, 5. These data