Structural diversity of copper(I) complexes formed by pyrrole- and dipyrrolylmethane-based diphosphine ligands with Cu-X·HN hydrogen bonds

Article abstract of DOI:10.1021/ic402253y

Metal complexes containing hydrogen bond donor/acceptor groups are interesting because of their applications in several areas. In the course of our investigation on the synthesis of metal complexes using newly developed pyrrole-based diphosphine ligands, a few structurally interesting copper(I) complexes containing the pyrrolic NH hydrogen bond donors were synthesized. The reaction of 2,5-bis(diphenylphosphinomethyl)pyrrole (PNP) with an equimolar quantity of CuX (X = Cl, Br, and I) afforded the binuclear copper(I) complexes [Cu(μ-X)(μ-PNP-P,P)]₂ (1-3) in very good yields (87-90%). Conversely, the analogous reaction between 1,9-bis(diphenylphosphinomethyl) diphenyldipyrrolylmethane (PNNP) and CuX (X = Cl, Br, and I) yielded the mononuclear Cu(I) complexes [CuX(PNNP-P,P)] (4-6) in very good yields (～88%), in which the diphosphine ligand is chelated to the copper metal atom. Interestingly, when this reaction was carried out with a 1:2 mol ratio of ligand/metal, the cubane-like tetranuclear Cu(I) complex, [Cu₄I ₄{μ-Ph₂C(C₄H₃N) ₂-1,9-(CH₂PPh₂)₂-P,P}₂] 7, was isolated in 68% yield. In addition, the reaction between the dipyrrolyldiphosphine ligand (PNNP) and CuCl in the presence of 1 equiv of 1,10-phenanthroline monohydrate and NaBF₄ afforded a novel ionic binuclear mixed-ligand Cu(I) complex, [Cu₂(μ-X)(μ-PNNP-P,P)(NN) ₂]BF₄ 8, where NN = 1,10-phenanthroline in 57% yield. The structures of all these complexes were confirmed by the single-crystal X-ray diffraction method and are supported by spectroscopic data. In contrast to the PNP pincer ligand, the dipyrrolyl-diphosphine ligand (PNNP) adopts chelation as well as bridging coordination modes with Cu(I) atoms, indicating its flexibility of bonding. In all the structures, the Cu-X·HN type of hydrogen bonds involving the metal halide ion as acceptor and the pyrrolic NH as donor are present with the Cu-X·H angles, which deviate from the favored 90, as observed in their solid state structures. Further, the presence of this type of hydrogen bond was confirmed by NBO, AIM, and Hirshfeld analyses.

Full text of DOI:10.1021/ic402253y

Article
pubs.acs.org/IC
Structural Diversity of Copper(I) Complexes Formed by Pyrrole- and
Dipyrrolylmethane-Based Diphosphine Ligands with Cu−X···HN
Hydrogen Bonds
Shanish Kumar, Ganesan Mani,* Debodyuti Dutta, and Sabyashachi Mishra
Department of Chemistry, Indian Institute of Technology − Kharagpur, Kharagpur, West Bengal, India 721 302
S
* Supporting Information
ABSTRACT: Metal complexes containing hydrogen bond
donor/acceptor groups are interesting because of their
applications in several areas. In the course of our investigation
on the synthesis of metal complexes using newly developed
pyrrole-based diphosphine ligands, a few structurally interest-
ing copper(I) complexes containing the pyrrolic NH hydrogen
bond donors were synthesized. The reaction of 2,5-bis-
(diphenylphosphinomethyl)pyrrole (PNP) with an equimolar
quantity of CuX (X = Cl, Br, and I) afforded the binuclear
copper(I) complexes [Cu(μ-X)(μ-PNP-P,P)]2 (1−3) in very
good yields (87−90%). Conversely, the analogous reaction
between 1,9-bis(diphenylphosphinomethyl)diphenyl-
dipyrrolylmethane (PNNP) and CuX (X = Cl, Br, and I) yielded the mononuclear Cu(I) complexes [CuX(PNNP-P,P)] (4−
6) in very good yields (∼88%), in which the diphosphine ligand is chelated to the copper metal atom. Interestingly, when this
reaction was carried out with a 1:2 mol ratio of ligand/metal, the cubane-like tetranuclear Cu(I) complex, [Cu4I4{μ-
Ph2C(C4H3N)2-1,9-(CH2PPh2)2-P,P}2] 7, was isolated in 68% yield. In addition, the reaction between the dipyrrolyldiphosphine
ligand (PNNP) and CuCl in the presence of 1 equiv of 1,10-phenanthroline monohydrate and NaBF4 afforded a novel ionic
binuclear mixed-ligand Cu(I) complex, [Cu2(μ-X)(μ-PNNP-P,P)(NN)2]BF4 8, where NN = 1,10-phenanthroline in 57% yield.
The structures of all these complexes were confirmed by the single-crystal X-ray diffraction method and are supported by
spectroscopic data. In contrast to the PNP pincer ligand, the dipyrrolyl−diphosphine ligand (PNNP) adopts chelation as well as
bridging coordination modes with Cu(I) atoms, indicating its flexibility of bonding. In all the structures, the Cu−X···HN type of
hydrogen bonds involving the metal halide ion as acceptor and the pyrrolic NH as donor are present with the Cu−X···H angles,
which deviate from the favored 90°, as observed in their solid state structures. Further, the presence of this type of hydrogen
bond was confirmed by NBO, AIM, and Hirshfeld analyses.
Chart 1. Pyrrole(A)- and Dipyrrolylmethane(B)-Based
Diphosphine Ligands
INTRODUCTION
■
Copper(I) complexes have attracted attention in the past and
continue to be an active area of research because of their
diverse structural and photophysical properties;1 they have
potential applications in areas such as optoelectronics2 and
catalysis,3 among others. Pincer ligands have been used to
modify and control the property of metal complexes. As a
result, pincer metal complexes have found several applications
in areas such as catalysis, sensors, and switches.4 However,
among several types of pincer ligands, PNP-pincer ligands,
which have both soft and hard donors, have scarcely been used
for synthesizing multinuclear Cu(I) complexes.5 Peter and co-
workers have reported highly emissive Cu(I) complexes bearing
an anionic PNP pincer ligand.6 Van der Vlugt and co-workers
studied thiolate bridged binuclear Cu(I) complexes containing
a pyridine-based PNP pincer ligand.5e,7 In this potential area of
research, we recently introduced a new type of pyrrole-based
NNN,8 PNP-pincer,9 and dipyrrolylmethane-based PNNP-type
ligands.9a The diphosphine ligands PNP and PNNP (Chart 1)
are potential tridentate and polydentate ligands, respectively,
when deprotonated. On the other hand, as a neutral ligand they
can chelate to a metal atom to give a metal complex containing
the pyrrolic NH groups. The presence of NH groups in the
structure of metal complexes are potential hydrogen bond
donors and can stabilize structures via a hydrogen bond to a
metal-bound hydrogen acceptor.
Metal complexes containing hydrogen bond donor/acceptor
groups are interesting because of their applications in areas such
Received: May 5, 2013
Published: January 3, 2014
© 2014 American Chemical Society
700
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
as molecular receptor,10 switches,11 supramolecular catalysis,12
self-assembly,13 and other reactions.14 It can be noted from
these studies that these hydrogen-bonding groups are useful for
orienting substrates to have an optimal interaction with a metal
atom that leads to substrate activation and conversion.15 For
example, in nature, carboxypeptidase A performs hydrolysis of
peptide bonds with assistance from its hydrogn-bonding
groups. Recently, metal complexes containing hydrogen bond
groups have been reported as a catalyst for hydrogenation of
CO2,16 dioxygen activation,17 and transfer hydrogenation of
ketones18 in which the M−X···H hydrogen bond plays a very
important role.
Herein, we report the syntheses and structural character-
izations of a series of three-coordinate mononuclear, homo-
leptic, and heteroleptic binuclear and tetranuclear Cu(I)
complexes bearing neutral PNP(A) and PNNP(B) ligand
systems. In addition, the presence of the Cu−X···HN type of
hydrogen bond in their structures are confirmed by NBO, AIM,
and Hirshfeld analyses.
Figure 1. ORTEP diagram of 1 with 30% probability ellipsoids; most
H atoms are omitted for clarity. Selected bond lengths (Å) and angles
(°): P1−Cu1 2.314(2), P2−Cu1 2.293(2), P3−Cu2 2.275(2), P4−
Cu2 2.258(2), Cl1−Cu2 2.463(2), Cl1−Cu1 2.500(2), Cl2−Cu2
2.452(2), Cl2−Cu1 2.497(2), Cu2−Cl1−Cu1 93.50(7), Cu2−Cl2−
Cu1 93.82(7), P2−Cu1−P1 124.48(8), P2−Cu1−Cl2 122.48(8), P1−
Cu1−Cl2 97.61(8), P2−Cu1−Cl1 97.85(8), P1−Cu1−Cl1 124.20(8),
Cl2−Cu1−Cl1 85.45(7), P4−Cu2−P3 119.75(8), P4−Cu2−Cl2
122.14(8), P3−Cu2−Cl2 101.52(8), P4−Cu2−Cl1 100.78(8), P3−
Cu2−Cl1 122.32(8), Cl2−Cu2−Cl1 87.23(7), N1···Cl2 3.383(7),
H1n···Cl2 2.74(8), N1−H1n···Cl2 145(8), N1···Cl1 3.509(7), H1n···
Cl1 2.89(8), N1−H1n···Cl1 141(8), N2···Cl2 3.341(7), H2n···Cl2
2.65(8), N2−H2n···Cl2 162(9), Cu1−Cl2···H1n 66(2), Cu2−Cl2···
H1n 68(2), Cu1−Cl1···H1n 64(2), Cu2−Cl1···H1n 65(2), Cu1−
Cl2···H2n 68(2), Cu2−Cl2···H2n 70(2), Cu1−Cl1···H2n 62(2),
Cu2−Cl1···H2n 64(2).
RESULTS AND DISCUSSION
Homoleptic Binuclear Cu(I) Complexes 1, 2, and 3. As
shown in Scheme 1, the reaction between an equimolar
■
Scheme 1. Synthesis of Homoleptic Binuclear Cu(I)
Complexes 1−3 Bearing the PNP-Pincer Ligand A
asymmetric unit. The X-ray structure revealed that each
diphosphine ligand is twisted and bridges the planar rhombic
“Cu(μ-X)2Cu” core in a trans fashion such that the plane
formed by Cu2X2 core and the plane formed by the pyrrole ring
together with the methylene carbons of each diphosphine
ligand are orthogonal to each other. The two Cu(I) atoms are
not equally bridged by the halide ions, for instance, Cu1−Cl1 =
2.500(2) Å and Cu2−Cl1 = 2.463(2) Å, having a difference of
0.037 Å. The Cu···Cu distances are 3.615(2) Å (1) and
3.610(1) Å (3), which are substantially longer than that found
in the Cu metal (2.56 Å) and hence indicate no bonding
interaction between the copper atoms. These nonbonding
distances fall in the range reported for similar rhombic “Cu(μ-
X)2Cu” core structures containing two bridging diphosphine
ligands.20 Their average X−Cu−X angles (86.34(7)° (Cl) and
97.56(3)° (I)) are smaller than those found in the respective
Cu(I) dimer complexes of the type [L2Cu(μ-X)2CuL2]
containing monodentate and chelating diphosphine li-
gands,16b,21 but the average I−Cu−I angle (97.56(3)°) is
higher than that found [94.06(6)°] in [Cu2(μ-I)2{μ-Ph2P-
(CH2)2CONH(CH2)2NHCO(CH2)2PPh2}2].20a
Each Cu(I) atom exhibits a pseudotetrahedral geometry. In
the chloride complex 1, both arms of each ligand are almost
equally twisted as indicated by the dihedral angles, P4−C18−
C17−N1 = −56.3(9)° and P1−C13−C14−N1 = −48.0(9)°,
which assisted the pyrrolic NH groups to form two bifurcated
hydrogen bonds. In the case of the iodide complex 3, the twist
angles differ drastically, for instance, P1−C13−C14−N1 =
−69.4(7)° and P4−C18−C17−N1 = −24.2(9)°, and hence the
pyrrolic NH groups are not able to form bifurcated hydrogen
bonds, in contrast to the chloride structure. However, the Cu···
Cu distance (3.610(1) Å) found in 3 does not differ much from
that (3.615(2) Å) of 1. Complex 3 exhibits the I1···I2 distance
of 4.1217(6) Å, which is longer than that reported for the
binuclear Cu(I) complex containing bridging diphosphine
quantity of the PNP-pincer ligand, A, and CuX (X = Cl, Br, and
I) afforded the binuclear copper(I) complexes 1, 2, and 3,
bearing two bridging diphosphine ligands, respectively. These
complexes were isolated in very good yields (87−90%) and are
characterized by spectroscopic, elemental analysis, and single-
crystal X-ray diffraction methods.19 The H NMR spectra of
1
complexes 1−3 in toluene-d8 feature broad singlets for their
NH, CH2, and the pyrrolic β-CH protons, indicating a
symmetrical structure for them. The 31P{H} NMR spectra of
1−3 recorded in the same solvent show singlets at δ = −13.0,
−15.9, and −21.9 ppm, respectively, indicating that all four
phosphorus centers of each complex are in equivalent
environments. Further, the 31P chemical shifts of complex 1
and 2 are downfield shifted by 3.3 and 0.4 ppm, respectively,
while that of 3 is upfield shifted by 5.6 ppm, as compared to the
free ligand (31P: δ = −16.3 ppm). This trend of the chemical
shift moving to the shielded region as the electronegativity of
the halide ion decreases is opposite to the trend shown by the
Ni(II) pincer metal complexes containing the same ligand
[NiX{C4H2N-2,5-(CH2PPh2)2-κ3PNP}] (X = Cl, Br, and I)
reported earlier.9a
The structures of 1 and 3 were determined by X-ray
diffraction.19 The ORTEP diagram of 1 is given in Figure 1
along with selected bond lengths and angles, and their
refinement data are summarized in Table 2. These complexes
crystallize in the monoclinic system with one molecule in their
701
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
Scheme 2. Synthesis of Cu(I) Complexes of the Dipyrrolylmethane-Based Diphosphine Ligands B: Three Coordinate, 4−6, and
the Cubane-Like Tetranuclear, 7, complexes
Table 1. Selected Bond Lengths (Å) and Angles (°) for the Three-Coordinate Cu(I) Complexes, 4−6
complex
P1−Cu
P2−Cu
Cu−X
P1−Cu−P2
P1−Cu−X
P2−Cu−X
4
5
6
2.2391(7)
2.238(2)
2.2511(7)
2.251(2)
2.2927(7)
2.4208(15)
2.5404(7)
142.13(3)
141.88(7)
131.28(5)
109.34(3)
109.54(7)
115.00(4)
108.36(3)
108.43(7)
113.15(4)
2.2456(14)
2.2500(14)
ligand [Cu2(μ-I)2(Ph2P(CH2)2CONH(CH2)2NHCO-
(CH2)2PPh2)2] (I···I = 3.96 Å).20a
Three-Coordinate 4−6 and the Cubane-Like Tetranu-
clear 7 Cu(I) Complexes. As shown in Scheme 2, the reaction
between the dipyrrolylmethane-based diphosphine ligand B
and CuX (X = Cl, Br, and I) in a 1:1 mol ratio afforded the
mononuclear Cu(I) complexes 4, 5, and 6 in very good yields
(∼88%), respectively. Interestingly, when the mole ratio of B
and CuI is changed to 1:2, the cubane-like tetranuclear Cu(I)
complex 7 was isolated in 68% yield. These mononuclear
complexes 4, 5, and 6 in toluene-d8 possess almost the same 31P
chemical shift values, which appear as singlets at δ = −5.7, −5.8,
and −6.6 ppm, respectively. Similarly, the 31P{H} NMR
spectrum of 7 in dichloromethane gives a singlet at δ = −6.2
ppm. All these 31P chemical shifts are downfield shifted as
compared to that of the free ligand (31P: δ = −15.5 ppm), and
they indicate that the two phosphorus centers in each complex
are in equivalent environments. Further, none of these
complexes exhibit emission in toluene or dichloromethane
solution, but their structures are interesting with Cu−X···HN
hydrogen bonds among other features described below (Table
1.
The X-ray structure of 4 and its selected bond lengths and
angles are given in Figure 2. The structures of 5 and 6 are given
in SI (Figure S33 and Figure S34, respectively). Complexes 4−
6 crystallize in the triclinic P1 space group with one molecule in
their asymmetric unit. The structure of each complex
[CuX(PNNP)], where X = Cl, Br, and I, consists of one
chelated diphosphine ligand B and one halide atom, resulting in
a three-coordinate Cu(I) complex. The geometry around the
copper atom in each complex is a planar distorted equilateral
triangular with the P1−Cu−P2 angles (X = Cl, 142.13(3)°, Br,
141.88(7)°, and I, 131.28(5)°) higher than the corresponding
other two angles, P1−Cu−X and P2−Cu−X, and the sum of
the angles around copper ranges from 359.4 to 359.8°. The two
phosphorus atoms and Cu−X unit form a plane, and the
dipyrrolylmethane moiety is located above this plane with both
the pyrrolic NH groups oriented toward the halide ion and
hydrogen bonded to the halide ion, as shown in Figure 2.
Figure 2. (a) ORTEP diagram of 4 with 30% probability ellipsoids;
most H atoms are omitted for clarity; (b) side view. Hydrogen
bonding distances (Å) and angles (°): N1···Cl 3.374(2), H1n···Cl
2.57(3), N1−H1n···Cl 170(3), N2···Cl 3.283(2), H2n···Cl 2.50(3),
N2−H2n···Cl 160(2), Cu−Cl···H1n 73.1(6), Cu−Cl···H2n 78.3(6).
All the Cu−P bond distances are shorter than those reported
for an analogous tricoordinate Cu(I) pincer complex,
[PNPCuBr]5c (2.3104(5) Å and 2.3150(5) Å), and those for
the complexes of the formula [CuXL2] containing mono-
dentate phosphine ligands (L = PPh3,22 or PCy323) or a
chelating diphosphine ligand.24 However, certain Cu−P bond
distances are slightly higher than that found in the [CuXL2]
complex when L = P(CH2Ph)3.25 This can be because of steric
factors associated with the dipyrrolydiphosphine ligand B.
Consequently, the Cu−X bond distances (Cl, 2.2927(7) Å or
Br, 2.4208(15) Å) are longer than the corresponding value
reported for the [CuXL2] complexes containing monodentate
phosphine ligands (L = PPh3, PCy3, PPh2(o-tol),26 or
PCy2Ph27) or a bidentate phosphine ligand.20 Conversely, the
Cu−I bond distance (2.5404(7) Å) in 6 is lower than that
reported for the [CuXL2] complexes containing the phosphine
ligand such as PCy3 or P(CH2Ph)3, but it is longer when this
copper complex contains PPh3 or PPh2(o-tol). Further, since
the two phosphorus atoms of the diphosphine ligand B are
connected via nine atoms, the P−Cu−P angles in 4−6 are
higher than those reported for the [PNPCuBr] complex
containing (2,6-bis[(diphenylphosphino)methyl]pyridine) and
702
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
Figure 3. (a) ORTEP diagram of 7 with 30% probability ellipsoids; most H atoms are omitted for clarity; (b) shows only the “Cu4I4P4” skeleton of
the distorted cubane structure. Selected bond lengths (Å) and angles (°): P1−Cu1 2.2552(16), P2−Cu2 2.2434(16), Cu1−I1 2.6393(9), Cu1−I2
2.6807(8), Cu1−I2i 2.7954(9), Cu1···Cu2i 2.972(1), Cu1···Cu2 3.252(1), Cu1···Cu1i 3.248(1), Cu2···Cu2i 3.195(1), Cu2−I1 2.6745(8), Cu2−I1i
2.6831(8), Cu2−I2i 2.7347(9), I1···I2 4.458, I1···I2i 4.195, I1···I1i 4.205, I2···I2i 4.273, I2···I1i 4.195, P1−Cu1−I1 115.15(5), P1−Cu1−I2
114.54(5), I1−Cu1−I2 113.86(3), P1−Cu1−I2i 107.68(5), I1−Cu1−I2i 101.02(3), I2−Cu1−I2i 102.54(3), P2−Cu2−I1 121.14(5), P2−Cu2−I1i
111.97(4), I1−Cu2−I1i 103.42(3), P2−Cu2−I2i 107.29(5), I1−Cu2−I2i 101.71(3), I1i−Cu2−I2i 110.74(3), Cu1−I1−Cu2 75.45(3), Cu1−I1−
Cu2i 67.87(2), Cu2−I1−Cu2i 73.21(3), Cu1−I2−Cu2i 66.55(2), Cu1−I2−Cu1i 72.72(3), Cu2i−I2−Cu1i 72.02(2), N1···I1 3.947(4), H1n···I1
3.17(5), N1−H1n···I1 174(5), N2···N1 3.011(6), H2n···N1 2.43(5), N2−H2n···N1 124(4), Cu1−I1···H1n 70.0(9), Cu2−I1···H1n 94.2(9).
those found in [CuXL2] complexes (L = PPh3, PCy3,
P(CH2P)3, PPh2(o-tol), or PCy2Ph).
(Scheme 3). The 31P NMR spectrum of 8 in CH2Cl2 gives a
singlet at δ −6.4 ppm, which is downfield shifted as compared
The tetranuclear Cu(I) complex 7 crystallizes in the
monoclinic P2/n space group with one-half of the molecule
in the asymmetric unit. The whole molecule was generated by
C2 symmetry operation and is given in Figure 3. The X-ray
structure revealed that four Cu(I) and four I− atoms are
arranged alternatively in the corners of a distorted cubane
structure. Each face of this distorted cube consists of a “Cu2I2”
unit, and their copper atoms are bridged by two diphosphine
ligands in a trans fashion. Each Cu atom is coordinated to three
iodine atoms and one phosphorus donor, exhibiting a distorted
tetrahedral geometry. Cu−P, Cu−I, Cu···Cu, and I···I distances
and their angles are in the range reported for other distorted
Cu(I) cubane structures containing monodentate28 or
bidentate phosphine20a ligands. The Cu···Cu distances vary
from 2.972(1) to 3.252(1) Å, averaging to 3.167(1) Å. The
Cu−I bond lengths vary from 2.6393(9) Å to 2.7954(9) Å
about Cu1 and from 2.6745(8) Å to 2.7347(9) Å about Cu2.
The Cu−I−Cu angles range from 66.55(2)° to 75.45(3)°,
showing the distortion of cubane structure, which is probably
caused by repulsion between the iodine atoms. Both the
pyrrolic NH groups are projected toward the “Cu4I4” core, and
one of the NH groups of each ligand is hydrogen bonded to the
iodine atom.
Further, in contrast to several Cu(I) cubane clusters with
reported different Cu···Cu distances that affect their
luminescence properties, complex 7 is not emissive probably
because of its relatively longer nonbonding Cu···Cu distances.29
To the best of our knowledge, this structure represents only the
third copper−iodide cubane containing a bidentate phosphine
ligand.
Heteroleptic Binuclear Cu(I) Complex 8. Because we
observed the Cu−X···H hydrogen bonding in the solid-state
structures of homoleptic Cu(I) complexes, we set the synthesis
of heteroleptic Cu(I) complex to observe this type of hydrogen
bonding. A novel binuclear ionic Cu(I) complex 8 was obtained
in 57% yield from the one-pot reaction between the
dipyrrolyldiphosphine ligand B and CuCl in the presence of
1 equiv of 1,10-phenanthroline monohydrate and NaBF4
Scheme 3. Synthesis of a Mixed-Ligand Cu(I) Complex 8
Containing the Bridging Dipyrrolyldiphosphine Ligand B
with that of the free ligand and indicating that the phosphorus
centers are in equivalent environments. This complex in
CH2Cl2 exhibits an absorption band (λmax) at 439 nm, falling in
the region characteristic for a metal-to-ligand charge-transfer
transition (see Supporting Information, Figure S31). This
wavelength is longer than the λmax values reported for the
mononuclear mixed-ligand Cu(I) complexes containing a
simple phenanthroline ligand, [Cu(NN)(P−P)]BF4 (P−P =
bis[2-(diphenylphosphino)phenyl]ether) (λmax = 391 nm)30
and [Cu(NN)(PPh3)2]BF4 (λmax = 365 nm).31
Complex 8 is not emissive in toluene or dichloromethane
solution, like the previous copper complexes. This observation
is consistent with the report of McMillin1a,32 and others33 that
homoleptic or heteroleptic Cu(I) complexes containing one
2,9-disubstituted phenanthroline molecule are emissive, while
Cu(I) complexes containing simplex 1,10-phenanthroline are
not emissive, because the substituents at the 2,9-positions of the
phenanthroline molecule sterically inhibit the structural
distortion of Cu(I) complex from the tetrahedral to the
flattened structure in the excited state. Further, the structure of
8 as determined by X-ray diffraction given in Figure 4 is
703
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
interesting with the bent chloride ion bridging and Cu−X···H
hydrogen bonds.
dipyrrolymethane moiety of the ligand is bent toward the
chlorine atom. The two phenanthroline molecules exhibiting
π−π interactions are parallel to each other when viewing along
the Cu···Cu vector and are perpendicular to an approximate
plane formed by the two Cu, P, methylene carbon atoms
together with the chloride ion in the center. The geometry
around each copper atom is a distorted tetrahedral with almost
equal P1−Cu1−Cl1 and P2−Cu2−Cl1 angles of 110.37(9)°
and 110.75(9)°, respectively. The Cu1−P1 and Cu2−P2 bond
distances are almost equal and smaller than those found for the
mononuclear 4 and the tetranuclear 7 Cu(I) complexes.
Similarly, the Cu−Cl bond distances [2.403(2) Å and 2.404(3)
Å] are slightly shorter than the average Cu−Cl distance
(2.478(2) Å) found in complex 1 but are longer than those
(2.2927(7) Å) found in the mononuclear complex 4. The
Cu1···Cu2 distance of 4.332(2) Å indicates no bonding
interaction between the two copper atoms and is longer than
that (3.310 Å) reported for the similar dinuclear Cu(I) complex
containing 2,2′-bipyridine.34 Each copper atom in the structure
of 8 possesses 18 valence electrons, and the complex is air
stable.
Hydrogen Bonding Discussion. In all the structures 1, 3,
and 4−8, the pyrrolic NH groups form hydrogen bonds with
the metal halide ion whose metric parameters are given in their
figure captions. In addition, the structures of 7 and 8 showed
one of the pyrrolic NH groups hydrogen bonded to the
adjacent pyrrolide nitrogen atom, that is, the N−H···N type of
hydrogen bond. All the H···X (X = Cl, Br, and I) distances are
well below the sum of the van der Waals radii of the
corresponding atoms with their N−H···X angles greater than
140°. This type of M−X···HN hydrogen bonding has been
analyzed particularly by Crabtree,35 Brammer,36 Bernstein37
and co-workers and has been reported for several structures.38
The interesting aspect of this type of hydrogen bond is the
directional preference of M−X···HN interaction, and its angle
falls in the range of 90−130°, as observed in many structures.34
However, analysis of the Cu−X···H angles in the structures of
−
Figure 4. (a) ORTEP diagram of 8 with BF4 with 30% probability
ellipsoids; most H atoms are omitted for clarity; (b) a view along the
Cu···Cu vector. Selected bond lengths (Å) and angles (°): N3−Cu2
2.060(7), N4−Cu2 2.062(7), N5−Cu1 2.143(8), N6−Cu1 2.043(7),
P1−Cu1 2.198(2), P2−Cu2 2.177(2), Cl1−Cu1 2.403(2), Cl1−Cu2
2.404(3), N6−Cu1−N5 79.3(3), N6−Cu1−P1 131.1(2), N5−Cu1−
P1 126.3(2), N6−Cu1−Cl1 95.6(2), N5−Cu1−Cl1 108.0(2), P1−
Cu1−Cl1 110.37(9), N3−Cu2−N4 81.4(3), N3−Cu2−P2 119.9(2),
N4−Cu2−P2 128.4(2), N3−Cu2−Cl1 97.5(2), N4−Cu2−Cl1
111.9(2), P2−Cu2−Cl1 110.75(9), N1···Cll 3.228(7), H1n1···Cl1
2.56(8), N1−H1n1···Cl1 155(9), N2···Cll 3.259(7), H2n2···Cl1
2.34(7), N2−H2n2···Cl1 164(6), N1···N2 3.005(10), H1n1···N2
2.53(8), N1−H1n1···N2 125(9), Cu1−Cl1···H1n1 91(2), Cu1−Cl1···
H2n2 136(2), Cu2−Cl1···H1n1 128(2), Cu2−Cl1···H2n2 85(2).
The cationic part of this complex consists of two Cu(I)
atoms bridged by one diphosphine and one chlorine ligand. In
addition, each copper atom is chelated by one phenanthroline
molecule, resulting in a monocationic binuclear Cu(I) complex
−
whose charge is neutralized by the disordered BF4 ion. The
chlorine atom bridges the two copper atoms by being on the
bridging side of the dipyrrolydiphosphine ligand so that the
pyrrolic NH groups are able to form hydrogen bonds. The
Figure 5. (a) Optimized structure of 8. The bond critical points between the pyrrolic hydrogen atom and the Cu−Cl unit, signifying hydrogen
bonds, are highlighted with black circles. (b) Hirshfeld43 surface analysis of the observed Cu−X···HN interactions in complex 8.
704
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
1, 3, and 4−8 showed some anomalies. The tetranuclear 7 and
the mixed ligand complex 8 showed most of the Cu−X···H
angles above 90° (ranging from 70.0(9) to 136(2)°),
complying with the directionally preferred angular value. In
contrast to this, the Cu−X···H angles displayed by the dinuclear
(1 and 3) and the mononuclear (4−6) complexes range from
56.51(2)° to 78.3(6)°, which are drastically lower than 90° that
is expected for the more basic p-lone pair orbital of metal
bound halide ion involved.33 Steric constraints of the ligand
systems that form mono-, di-, and tetranuclear complexes
containing bridging and terminal halide ions, electron rich
Cu(I)-d10, and packing forces could contribute to these
observed angles in the solid state. In addition, these angles
are similar to the values found for a Cu(I) dimer complex of the
type containing bridging chloride ions, [LCu(μ-Cl)2CuL]39
(Cu1−Cl1···H8 = 81.85(2)°, Cu1i−Cl1···H8 = 155.61(3)°),
for a Cu(I) dimer complex containing terminally bonded
chloride ions (Cu1−Cl2···H2Ni = 87.8(7)°),40 and for a
mononuclear Cu(I) complex containing a terminally bonded
chloride ion (Cu1−Cl1···H1 = 83(1)°);41 these angles are
obtained by viewing their cif files by Mercury 3.1 software.
As a representative example for each type of stucture, the
chloro derivative complexes 1, 4, 8 and the cubane structure 7
were analysized by NBO and AIM calculation methods to
ascertain the presence of H-bonds in the above-mentioned
complexes. The NBO analysis of the bond between the
pyrrolide nitrogen and its hydrogen atom showed an increased
s-orbital character for the pyrrolide nitrogen atom as compared
to the same in the free ligands A and B (see Supporting
Information, Table S8). This increase in s-orbital character
(suggesting an increase in electgronegativity of the N atom) is a
characteristic feature of the presence of the H-bond in these
structures. Further, upon comparison of the ν(NH) stretching
frequency of the free ligands A and B (Chart 1) with that of the
corresponding optimized geometry of complex, the ν(NH)
stretching frequency for each structure is red shifted, suggesting
the weakening of the N−H bonds in these complexes (see
Supporting Information, Table S8). This could be because of
the presence of H-bonds between the pyrrolic NH and chlorine
atom. This is further supported by the AIM analysis for the
presence of an electron density path linking the pyrrolic NH
proton with acceptor (Cl−Cu) and a bond critical point for
each H-bond. For example, the optimized structure of complex
8 with all bond critical points is given in Figure 5. The bond
critical points between the pyrrolic hydrogen atom and Cu−Cl
unit, signifying hydrogen bonds, are highlighted by black circles
in Figure 5. At each of these critical points, the electron density
is more than 0.002 au, and the Laplacian of electron density is
higher than 0.004 au (see Supporting Information, Table S9),
thus fulfilling the criteria for H-bond.42
hydrogen bonds in 1, 4, 7, and 8, N···X distances are shorter
and fall within the sum of the van der Waals radii of the
nitrogen and chlorine atoms. In addition, Hirshfeld analysis
clearly confirms the presence of Cu−X···HN interactions in
these complexes (see Figure 5b for 8 and Supporting
Information, Figure S38 for other structures).
CONCLUSION
■
The monopyrrolyldiphosphine PNP-pincer ligand A gave the
dimeric Cu(I) complexes in which the ligand adopts a bridging
mode of coordination, while the dipyrrolyldiphosphine PNNP
ligand B afforded the mono-, di- and tetranuclear Cu(I)
complexes, in which it exhibits the chelating and bridging
coordination modes. This shows that ligand B is more flexible
than A probably because of the chain length difference between
them. It is interesting to note that the formation of the
mononuclear Cu(I) complex 6 against the tetranuclear complex
7 was controlled by changing the mole ratio of the PNNP
ligand B. In addition, although none of the Cu(I) complexes
formed by these diphosphine ligands are emissive, they
represent rarely reported and structurally interesting complexes
with multiple Cu−X···HN type of hydrogen bonds with the
majority of Cu−X···H angles below 90° in contrast to the
preferred 90−130° value. The presence of H-bonds involving
metal halide ion as acceptor and the pyrrolic NH as donor was
confirmed by the NBO and AIM analyses, which are supported
by Hirshfeld analysis. All these are further contributing to the
existing structural diversity of Cu(I) complexes. In particular,
the binuclear heteroleptic complex 8 represents a novel
structure of its type. Synthesis of other mixed−ligand Cu(I)
and Ag(I) complexes for their photophysical properties and
other metal complexes are underway.
EXPERIMENTAL SECTION
■
All reactions and manipulations were carried out under a
nitrogen atmosphere using standard Schlenk-line techniques.
Petroleum ether (bp 40−60 °C) and other solvents were
distilled according to the standard procedures. The PNP (A)
and PNNP (B) ligands were prepared as per the procedure
reported in the literature.14 CuX (X = Cl, Br, and I), toluene-d8,
CDCl3, and NaBF4 were purchased from Aldrich. The
compound 1,10-phenanthroline, solvents and other chemicals
1
were purchased from local commercial sources. H NMR (200
and 400 MHz), 13C NMR (50.3 and 100.6 MHz), and 31P
(161.9 MHz) spectra were recorded on Bruker ACF200 and
AV400 spectrometers at room temperature. 1H NMR chemical
shifts are referenced with respect to the chemical shift of the
residual protons present in the deuterated solvents. For 31P
NMR measurements, 85% H3PO4 was used as an external
standard. FTIR spectra were recorded using Perkin−Elmer
Spectrum Rx. High-resolution mass spectra (ESI) were
recorded using the Xevo G2 Tof mass spectrometer (Waters).
Elemental analyses were carried out using a Perkin−Elmer 2400
CHN analyzer. UV−vis spectra were recorded using a quartz
cuvette on a Shimadzu spectrophotometer.
Computational Method. The crystal structure of com-
plexes 1, 4, 7, and 8 were used as the starting point of geometry
optimization employing the M06-2X functional44 and 6-
31G(d,p) basis set. Frequency calculation was carried out for
these complexes by employing the BLYP45 functional and 6-
31G(d,p) basis set. Natural bond orbital (NBO) analysis46 and
atoms in molecules (AIM) analysis47 were carried out to check
In addition, to check the propensity of the pyrrole ring NH
toward hydrogen bonding, the corresponding structures
containing furan rings instead of pyrrole rings were optimized
(see Supporting Information, Figure S37). These furan ring
optimized structures were found to be adopting the same
conformation as do the pyrrole ring structures 1, 4, 7, and 8.
However, the existence of H-bonds in these structures is
supported by the O···X distances in the optimized furan
derivative structures. The O···X distances are much longer than
the sum of the van der Waals radii of the oxygen and chlorine
atoms and are longer than the N···X distances of the
corresponding pyrrole ring structures. Therefore, it is
comprehensible that because of the formation of NH···X
705
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
the existence of hydrogen bonds in these complexes. For NBO
analysis, the B3LYP48 functional and 6-31+G(d,p) basis set was
used. For complex 7, a smaller basis set (3-21G) was used.
While the AIM analysis was performed using AIM2000
program,49 the geometry optimization, frequency calculations,
and NBO analysis were carried out using Gaussian09
program.50
87% yield). 1H NMR (toluene-d8, 400 MHz, ppm): δ = 3.49 (s,
4H, CH2), 5.57 (s, 2H, pyrrole β-CH), 5.89 (t, J (HH) = 2.8
Hz, 2H, pyrrole β-CH), 6.88−7.42 (m, 30H, phenyl CH), 10.81
(br s, 2H, NH). 31P{1H}NMR (161.9 MHz, toluene-d8, ppm):
δ = −5.7(s). FT-IR (KBr, cm−1): ν =3298 (s), 3054 (m), 1587
(m), 1482 (m), 1434 (s), 1393 (m), 1261 (w), 1214 (w), 1185
(w), 1121 (w), 1098 (m), 1043 (w), 873 (w), 793 (s), 773 (s),
756 (s), 697 (vs), 647 (w), 578 (w), 508 (m), 476 (w), 448
(w). HRMS (+ESI) m/z: [M − Cl−]+ calcd for
C47H40ClCuN2P2, 757.2063; found, 757.1982. Anal. Calcd for
C47H40ClCuN2P2: C, 71.12; H, 5.08; N, 3.53. Found: C, 71.46;
H, 5.20; N, 3.31.
Synthesis of [Cu(μ-Cl){μ-C4H2NH-2,5-(CH2PPh2)2-P,P}]2,
1. To a THF (∼50 mL) solution of monopyrrolic diphosphine
ligand A (0.234 g, 0.505 mmol) was added solid CuCl (0.050 g,
0.505 mmol), and the solution was stirred for 16 h at room
temperature, giving a clear solution. The solution was layered
with petroleum ether and allowed to stand for about 2 weeks to
give colorless crystals of complex 1. The crystals were separated
by decanting the mother liquor and dried under vacuum (0.250
The bromide (5) and the iodide (6) analogues of complex 4
were synthesized by following the synthetic procedure of 4. For
the synthesis of 5, CuBr (0.050 g, 0.350 mmol) and
dipyrrolydiphosphine ligand B (0.242 g, 0.350 mmol) were
used. The yield is 88% (0.215 g, 0.260 mmol). For the synthesis
of 6, CuI (0.100 g, 0.525 mmol) and ligand B (0.365 g, 0.525
mmol) were used. The reaction mixture was concentrated to
∼20 mL, and then ∼20 mL of petroleum ether was added. After
the solution was cooled to −15 °C for 1 week, colorless crystals
of 6 were formed. The yield is 87% (0.405 g, 0.460 mmol).
1
g, 0.222 mmol, 88% yield). H NMR (toluene-d8, 400 MHz,
ppm): δ = 3.55 (s, 8H, CH2), 5.42 (s, 4H, pyrrole β-CH),
6.83−7.25 (m, 40H, phenyl CH), 12.00 (br s, 2H, NH).
31P{1H}NMR (161.9 MHz, toluene-d8, ppm): δ = −13.0(s).
FT-IR (KBr, cm−1): ν = 3319 (s), 3051 (m), 1584 (m), 1483
(m), 1434 (s), 1398 (w), 1271 (w), 1182 (w), 1100 (m), 1029
(m), 998 (w), 827 (m), 741 (vs), 693 (vs), 639 (w), 508 (m),
477 (m), 444 (w), 403 (w). HRMS (+ESI) m/z: [M − Cl−]+
calcd for C60H54Cl2Cu2N2P4, 1087.1718; found, 1087.1440.
Anal. Calcd for C60H54Cl2Cu2N2P4: C, 64.06; H, 4.84; N, 2.49.
Found: C, 64.26; H, 4.96; N, 2.37.
1
[CuBr{Ph2C(C4H2NH)2-1,9-(CH2PPh2)2-P,P}], 5. H NMR
(toluene-d8, 400 MHz, ppm): δ = 3.54 (s, 4H, CH2), 5.57 (s,
2H, pyrrole β-CH), 5.90 (t, J (HH) = 2.8 Hz, 2H, pyrrole β-
CH), 6.89−7.43 (m, 30H, phenyl CH), 10.50 (br s, 2H, NH).
31P{1H}NMR (161.9 MHz, toluene-d8, ppm): δ = −5.8(s). FT-
IR (KBr, cm−1): ν = 3306 (s), 3054 (w), 1586 (m), 1482 (m),
1434 (s), 1393 (m), 1260 (w), 1184 (m), 1097 (s), 1043 (m),
791 (s), 771 (s), 755 (s), 697 (vs), 508 (s). HRMS (+ESI) m/
z: [M − Br−]+ calcd for C47H40BrCuN2P2, 757.2063; found,
757.1982.
The bromide (2) and the iodide (3) analogues of complex 1
were synthesized by following the synthetic procedure of 1. For
the synthesis of 2, CuBr (0.050 g, 0.350 mmol) and ligand A
(0.162 g, 0.350 mmol) were used. The yield is 90% (0.190 g,
0.160 mmol). For the synthesis of 3, CuI (0.100 g, 0.525
mmol) and ligand A (0.244 g, 0.525 mmol) were used. The
yield is 87% (0.3 g, 0.230 mmol).
[CuI{Ph2C(C4H2NH)2-1,9-(CH2PPh2)2-P,P}], 6. 1H NMR
(toluene-d8, 400 MHz, ppm): δ = 3.60 (s, 4H, CH2), 5.55 (s,
2H, pyrrole β-CH), 5.90 (s, 2H, pyrrole β-CH), 6.87−7.44 (m,
30H, phenyl CH), 10.12 (br s, 2H, NH). 31P{1H}NMR (161.9
MHz, toluene-d8, ppm): δ = −6.6(s). FT-IR (KBr, cm−1): ν =
3400 (m), 3294 (s), 3052 (m), 1580 (m), 1484 (s), 1444 (m),
1434 (s), 1394 (m), 1309 (w), 1262 (w), 1217 (w), 1180 (w),
1156 (w), 1101 (s), 1082 (m), 1037 (m), 998 (w), 899(w), 874
(w), 835 (w), 812 (w), 783 (m), 762 (s), 741 (s), 692 (vs), 634
(w), 593 (w), 539 (w), 507 (s), 495 (m), 484 (m), 460 (w),
444 (w). HRMS (+ESI) m/z: [M − I−]+ calcd for
C47H40CuIN2P2, 757.2063; found, 757.1926.
1
[Cu(μ-Br){μ-C4H2NH-2,5-(CH2PPh2)2-P,P}]2, 2. H NMR
(toluene-d8, 400 MHz, ppm): δ = 3.66 (s, 8H, CH2), 5.51 (s,
4H, pyrrole β-CH), 6.87−7.22 (m, 40H, phenyl CH), 11.60 (br
s, 2H, NH). 31P{1H}NMR (161.9 MHz, toluene-d8, ppm): δ =
−16.0 (s). FT-IR (KBr, cm−1): ν = 3323 (s), 3050 (m), 1584
(m), 1483 (m), 1434 (s), 1397 (m), 1166 (m), 1100(s), 1030
(m), 808 (m), 742 (s), 693 (vs), 635 (w), 507 (s), 478 (m).
HRMS (+ESI) m/z: [M − Br−]+ calcd for C60H54Br2Cu2N2P4,
1131.1213; found, 1131.0908. Anal. Calcd for
C60H54Br2Cu2N2P4: C, 59.37; H, 4.48; N, 2.31. Found: C,
58.62; H, 4.69; N, 2.15.
[Cu(μ-I){μ-C4H2NH-2,5-(CH2PPh2)2-P,P}]2, 3. 1H NMR
(toluene-d8, 400 MHz, ppm): δ = 3.75 (s, 8H, CH2), 5.55 (s,
4H, pyrrole β-CH), 6.88−7.21 (m, 40H, phenyl CH), 11.45 (br
s, 2H, NH). 31P{1H}NMR (161.9 MHz, toluene-d8, ppm): δ =
−21.9(s). FT-IR (KBr, cm−1): ν = 3330 (vs), 3050 (w), 1583
(w), 1482 (m), 1434 (s), 1395 (m), 1098 (m), 1030 (m), 832
(w), 742 (vs), 693 (vs), 633 (w), 506 (s), 478 (m). HRMS
(+ESI) m/z: [M − I−]+ calcd for C60H54I2Cu2N2P4, 1179.1074;
found, 1179.0767. Anal. Calcd for C60H54Cu2I2N2P4: C, 55.10;
H, 4.16; N, 2.14. Found: C, 55.69; H, 4.43; N, 1.92.
Synthesis of [Cu4I4{μ-Ph2C(C4H3N)2-1,9-(CH2PPh2)2-
P,P}2] 7. To a THF (100 mL) solution of dipyrrolydiphosphine
ligand B (0.365 g, 0.525 mmol) was added solid CuI (0.200 g,
1.050 mmol). The solution was stirred for 48 h at room
temperature and then filtered to remove some insoluble
residue. The clear solution was layered with petroleum ether,
which then was allowed to stand for 2 weeks to give colorless
crystals of complex 7. Crystals were separated by decanting the
mother liquor and dried under vacuum (0.412 g, 0.180 mmol,
1
68% yield). H NMR (toluene-d8, 400 MHz, ppm): δ = 3.58
Synthesis of Complex [CuCl{Ph2C(C4H2NH)2-1,9-
(CH2PPh2)2-P,P}], 4. To a THF (50 mL) solution of
dipyrrolyldiphosphine ligand B (0.352 g, 0.510 mmol) was
added solid CuCl (0.050 g, 0.505 mmol), and the solution was
stirred for 20 h at room temperature, giving a clear solution.
The solution was layered with petroleum ether and then
allowed to stand for 2 weeks to give colorless crystals of
complex 4. The crystals were separated by decanting the
solution and then dried under vacuum (0.350 g, 0.440 mmol,
(br s, 8H, CH2), 5.48 (br s, 4H, pyrrole β-CH), 5.58 (br s, 4H,
pyrrole β-CH), 6.84−7.47 (m, 60H, phenyl CH), 8.76 (br s,
4H, NH). 31P{1H}NMR (161.9 MHz, CH2Cl2, D2O as external
lock, ppm): δ = −6.2(s). FT-IR (KBr, cm−1): ν = 3433 (m),
3333 (m), 3052 (m), 2953 (w), 1574 (m), 1483 (m), 1434 (s),
1401 (m), 1274 (w), 1181 (m), 1099 (m), 1044(m), 999 (w),
902 (w), 827 (m), 774 (m), 741 (s), 694 (vs), 623 (w), 506
(m), 480 (m), 448 (w). Anal. Calcd. for C102H96Cu4I4N4O2P4:
C, 53.36; H, 4.21; N, 2.44. Found: C, 53.14; H, 3.92; N, 2.49.
706
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
Table 2. Crystallographic Data for 1, 4, 7, and 8
1
4
7
8
empirical formula
fw
C60H54Cl2Cu2N2P4
C47H40ClCuN2P2
793.74
C102H96Cu4I4N4O2P4
2295.47
C71H56BClCu2F4N6P2
1304.50
1124.91
wavelength (Å)
temp (K)
cryst syst
space group
a (Å)
0.71073
0.71073
0.71073
0.71073
293(2)
293(2)
293(2)
293(2)
monoclinic
P21/n
triclinic
monoclinic
P2/n
monoclinic
Cc
P1
9.988(3)
18.830(5)
29.206(8)
90.0
11.0444(7)
13.7726(9)
14.0611(9)
112.505(2)
94.387(2)
93.330(2)
1961.3(2)
2
17.3607(15)
12.7387(11)
22.6008(18)
90.0
24.571(8)
16.581(5)
17.629(5)
90.0
b (Å)
c (Å)
α (deg)
β (deg)
95.846(8)
90.0
104.827(2)
90.0
122.542(8)
90.0
γ (deg)
vol (Å3)
5464(3)
4
4831.8(7)
2
6055(3)
Z
4
Dcalcd (mg m−3
1.367
1.344
1.578
1.431
μ (mm−1
)
1.034
0.743
2.262
0.861
F(000)
2320
824
2280
2680
θ range (deg)
1.29 to 25.00
64460/9609
0.1216
1.58 to 26.39
25391/7816
0.0375
1.60 to 25.00
56689/8513
0.0672
1.57 to 24.72
34632/10051
0.1608
total/unique no. of reflns
Rint
data/restr/params
GOF (F2)
9609/0/637
1.058
7816/0/484
1.015
8513/0/502
1.036
10051/45/800
0.992
R1, wR2
0.0748, 0.1767
0.1491, 0.2184
1.227 and −0.455
0.0403, 0.0937
0.0634, 0.1054
0.447, −0.371
0.0472, 0.0948
0.0762, 0.1048
0.635 and −0.576
0.0672, 0.0900
0.1653, 0.1149
0.320, −0.402
R indices (all data) R1, wR2
largest different peak and hole (e Å−3
)
Synthesis of [Cu2(μ-Cl)(μ-PNNP-P,P)(NN)2]BF4, 8. The
dipyrrolyldiphosphine ligand B (0.351 g, 0.505 mmol), CuCl
(0.050 g, 0.505 mmol), and NaBF4 (0.060 g, 0.510 mmol) were
taken in a Schlenk flask. Eighty milliliters of acetonitrile was
added to this flask, and the resultant solution was stirred for 30
min, resulting in the formation of colorless precipitate. To this
suspension, 1,10-phenanthroline monohydrate (0.100 g, 0.505
mmol) was added, resulting in a disappearance of the
precipitate and a clear solution. The solution was stirred for
16 h and then filtered to remove some insoluble residue. The
clear solution was layered with diethyl ether and allowed to
stand for 1 week to give yellow crystals of complex 8. The
crystals were separated by decanting the solution and were
were carried out on F2 using SHELXL-97 (WinGX version)52
to locate the remaining non-hydrogen atoms.
Typically, for all the structures, hydrogen atoms attached to
carbons were fixed in calculated positions. For most of the
structures, the NH hydrogen atoms were located from the
difference Fourier map and freely refined isotropically with
their thermal parameters set as equivalent to 1.2 times that of
their parent atoms. In the structure of 3, one of the NH
hydrogen atoms was fixed, while the other was located. In case
of the structure of 7, the unit cell contains two molecules of
THF which have been treated as a diffuse contribution to the
overall scattering without specific atom positions by
SQUEEZE/PLATON.53 The presence of THF is supported
1
1
by the H NMR spectrum recorded for the crystals of 7 in
dried under vacuum (0.190 g, 0.145 mmol, 57% yield). H
toluene-d8 showing multiplets at δ = 1.46 ppm and 3.56 ppm.
Use of SQUEEZE/PLATON necessarily contributes to the
discrepancy between calculated and reported formulas in the cif
file for the structure of 7. In the structure of 8, the BF4− anion is
disordered over two positions with occupancy factors of 76 and
24%, which are handled successfully with EADP and SADI
options. The refinement data are summarized in Table 2.
NMR (CD3CN, 400 MHz, ppm): δ = 3.65 (s, 4H, CH2), 5.46
(s, 2H, pyrrole β-CH), 5.51 (s, 2H, pyrrole β-CH), 6.87−7.30
(m, 34H, phenyl and phenanthroline CH), 7.76, 8.00, 8.18 (br
s, 12H, phenanthroline CH), 10.47 (br s, 2H, NH). 31P{1H}-
NMR (161.9 MHz, CH2Cl2, D2O as external lock, ppm): δ =
−6.4(s). FT-IR (KBr, cm−1): ν = 3336 (s), 3063 (m), 1623
(w), 1587 (m), 1511 (m), 1485 (m), 1422 (s), 1186 (w), 1059
(vs), 846 (s), 771 (s), 755 (s), 727 (s), 695 (s), 507 (m), 484
(m). UV−vis: (λmax, CH2Cl2, nm) = 439, ε = 5919 M−1cm−1.
HRMS (+ESI) m/z: [M − CuCl − BF4 − 2phen]+ calcd for
C71H56BClCu2F4N6P2, 1304.5417; found, 757.1963.
X-ray Crystallography. Suitable single crystals of 1−8
were obtained from solvents mentioned in their respective
synthetic procedures. Single-crystal X-ray diffraction data
collections for all the compounds were performed at room
temperature using Bruker-APEX-II CCD diffractometer with
graphite monochromated Mo Kα radiation (λ = 0.71073 Å).
The structures were solved by SIR-9251 or SHELXS-97
available in WinGX, which successfully located most of the
non-hydrogen atoms. Subsequently, least-squares refinements
ASSOCIATED CONTENT
* Supporting Information
■
S
NMR, IR, HRMS, UV, X-ray structures, refinement data,
crystallographic data (cif), Hirshfeld analysis, optimized
structures and their Cartesian coordinates. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: gmani@chem.iitkgp.ernet.in. Fax: +91 3222 282252.
■
Notes
The authors declare no competing financial interest.
707
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
Dalton Trans. 2012, 41, 14028−14030. (c) Venkanna, G. T.; Ramos,
T. V. M; Arman, H. D.; Tonzetich, Z. J. Inorg. Chem. 2012, 51,
12789−12795.
ACKNOWLEDGMENTS
■
We thank the CSIR and DST (New Delhi, India) for financial
support and for the X-ray, NMR, and HPC facilities.
(10) (a) Amendola, V.; Fabbrizzi, L. Chem. Commun. 2009, 513−531.
(b) Soriano, M. L.; Lenthall, J. T.; Anderson, K. M.; Smith, S. J.; Steed,
J. W. Chem.Eur. J. 2010, 16, 10818−10831. (c) Mendoza, C.; Benet-
REFERENCES
■
́
Buchholz, J.; Pericas, M. A.; Vilar, R. Dalton Trans. 2009, 2974−2985.
(1) (a) McMillin, D. R.; McNett, K. M. Chem. Rev. 1998, 98, 1201−
1220. (b) Yam, V. W.-W.; Lo, K. K.-W. Chem. Soc. Rev. 1999, 28, 323−
334. (c) Armaroli, N. Chem. Soc. Rev. 2001, 30, 113−124. (d) Armaroli,
N.; Accorsi, G.; Cardinali, F.; Listorti, A. Top. Curr. Chem. 2007, 280,
69−115. (e) Peng, R.; Li, M.; Li, D. Coord. Chem. Rev. 2010, 254, 1−
18. (f) Liu, X.; Pattacini, R.; Deglmann, P.; Braunstein, P.
Organometallics 2011, 30, 3302−3310. (g) Meinholz, M. M.; Stalke,
D. Z. Naturforsch. 2011, 66b, 981−984. (h) Shan, X.-C.; Jiang, F.-L.;
Yuan, D.-Q.; Wu, M.-Y.; Zhang, S.-Q.; Hong, M.-C. Dalton Trans.
2012, 41, 9411−9416. (i) Krylova, V. A.; Djurovich, P. I.; Aronson, J.
W.; Haiges, R.; Whited, M. T.; Thompson, M. E. Organometallics
2012, 31, 7983−7993.
(2) (a) Zhang, Q.; Zhou, Q.; Cheng, Y.; Wang, L.; Ma, D.; Jing, X.;
Wang, F. Adv. Funct. Mater. 2006, 16, 1203−1208. (b) Deaton, J. C.;
Switalski, S. C.; Kondakov, D. Y.; Young, R. H.; Pawlik, T. D.; Giesen,
D. J.; Harkins, S. B.; Miller, A. J. M.; Mickenberg, S. F.; Peters, J. C. J.
Am. Chem. Soc. 2010, 132, 9499−9508. (c) Liu, Z. W.; Qayyum, M. F.;
Wu, C.; Whited, M. T.; Djurovich, P. I.; Hodgson, K. O.; Hedman, B.;
Solomon, E. I.; Thompson, M. E. J. Am. Chem. Soc. 2011, 133, 3700−
3703.
(d) Vega, I. E. D.; Gale, P. A.; Light, M. E.; Loeb, S. J. Chem. Commun.
2005, 4913−4915. (e) Vilar, R. Eur. J. Inorg. Chem. 2008, 3, 357−367.
(11) Albrecht, M.; Lutz, M.; Spek, A. L.; van Koten, G. Nature 2000,
406, 970−974.
(12) Jonsson, S.; Odille, F. G. J.; Norrby, P.-O.; Warnmark, K. Chem.
Commun. 2005, 549−551.
(13) Davies, P. J.; Veldman, N.; Grove, D. M.; van Koten, G.; Spek,
A. L.; Lutz, T. G. Angew. Chem., Int. Ed. Engl. 1996, 35, 1959−1961.
(14) Dobereiner, G. E.; Wu, J.; Manas, M. G.; Schley, N. D.; Takase,
M. K.; Crabtree, R. H.; Hazari, N.; Nova, A.; Maseras, F. Inorg. Chem.
2012, 51, 9683−9693.
(15) (a) Crabtree, R. H. New J. Chem. 2011, 35, 18−23. (b) DuBois,
M. R.; DuBois, D. L. Chem. Soc. Rev. 2009, 38, 62−72. (c) Wang, W.-
H.; Muckerman, J. T.; Fujita, E.; Himeda, Y. New J. Chem. 2013, 37,
1860−1866.
(16) (a) Schmeier, T. J.; Dobereiner, G. E.; Crabtree, R. H.; Hazari,
N. J. Am. Chem. Soc. 2011, 133, 9274−9277. (b) Badiei, Y. M.; Wang,
W.-H.; Hull, J. F.; Szalda, D. J.; Muckerman, J. T.; Himeda, Y.; Fujita,
E. Inorg. Chem. 2013, 52, 12576−12586.
(17) Shook, R. L.; Borovik, A. S. Inorg. Chem. 2010, 49, 3646−3660.
(18) Moore, C. M.; Szymczak, N. K. Chem. Commun. 2013, 49, 400−
402.
(19) The X-ray structure of 3 is given in SI (Figure S32). The X-ray
structure of the bromide derivative 2 (Figure S35) could not be solved
completely as their phenyl carbons have very large thermal parameter
values. However, its ORTEP diagram and refinement data are given in
Supporting Information.
(20) (a) Li, Y.; Yung, K.-F.; Chan, H.-S.; Wong, W.-T. Inorg. Chem.
Commun. 2003, 6, 1451−1453. (b) Effendy; Nicola, C. D.; Fianchini,
M.; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A. H. Inorg. Chim.
Acta 2005, 358, 763−795.
(21) (a) Eller, P. G.; Kubas, G. J.; Ryan, R. R. Inorg. Chem. 1977, 16,
2454−2462. (b) Batchelor, R. J.; Birchall, T.; Faggiani, R. Can. J. Chem.
1985, 63, 928−934. (c) Bowmaker, G. A.; Hanna, J. V.; Hart, R. D.;
Healy, P. C.; White, A. H. J. Chem. Soc., Dalton Trans. 1994, 2621−
2629. (d) Neo, S. P.; Zhou, Z.-Y.; Mak, T. C. W.; Hor, T. S. A. J.
Chem. Soc., Dalton Trans. 1994, 3451−3458. (e) Bowmaker, G. A.;
Hart, R. D.; Jones, B. E.; Skelton, B. W.; White, A. H. J. Chem. Soc.,
Dalton Trans. 1995, 3063−3070. (f) Bayler, A.; Schier, A.; Schmidbaur,
H. Inorg. Chem. 1998, 37, 4353−4359. (g) Aslanidis, P.; Cox, P. J.;
Divanidis, S.; Tsipis, A. C. Inorg. Chem. 2002, 41, 6875−6886.
(22) Bowmaker, G. A.; Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.;
Pakawatchai, C.; White, A. H. J. Chem. Soc., Dalton Trans. 1987, 1089−
1097.
(23) (a) Soloveichik, G. L.; Eisenstein, O.; Poulton, J. T.; Streib, W.
E.; Huffman, J. C.; Caulton, K. G. Inorg. Chem. 1992, 31, 3306−3312.
(b) Bowmaker, G. A.; Boyd, S. E.; Hanna, J. V.; Hart, R. D.; Healy, P.
C.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 2002,
2722−2730.
(24) Hashimoto, M.; Igawa, S.; Yashima, M.; Kawata, I.; Hoshino,
M.; Osawa, M. J. Am. Chem. Soc. 2011, 133, 10348−10351.
(25) Ainscough, E. W.; Brodie, A. M.; Burrell, A. K.; Freeman, G. H.;
Jameson, G. B.; Bowmaker, G. A.; Hanna, J. V.; Healy, P. C. J. Chem.
Soc., Dalton Trans. 2001, 144−151.
(3) (a) Fache, F.; Schulz, E.; Tommasino, M. L.; Lemaire, M. Chem.
Rev. 2000, 100, 2159−2231. (b) Kamigaito, M.; Ando, T.; Sawamoto,
M. Chem. Rev. 2001, 101, 3689−3745. (c) Bai, S.-Q.; Koh, L. L.; Hor,
T. S. A. Inorg. Chem. 2009, 48, 1207−1213. (d) Beletskaya, I. P.;
Cheprakov, A. V. Organometallics 2012, 31, 7753−7808.
(4) (a) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40,
3750−3781. (b) van der Boom, M. E.; Milstein, D. Chem. Rev. 2003,
103, 1759−1792. (c) Singleton, J. T. Tetrahedron 2003, 59, 1837−
1857. (d) Leis, W.; Mayer, H. A.; Kaska, W. C. Coord. Chem. Rev.
2008, 252, 1787−1797. (e) Benito-Garagorri, D.; Kirchner, K. Acc.
Chem. Res. 2008, 41, 201−213. (f) van der Vlugt, J. I.; Reek, J. N. H.
Angew. Chem., Int. Ed. 2009, 48, 8832−8846. (g) Milstein, D. Top.
Catal. 2010, 53, 915−923. (h) Gunanathan, C.; Milstein, D. Acc.
Chem. Res. 2011, 44, 588−602. (i) Choi, J.; MacArthur, A. H. R.;
Brookhart, M.; Goldman, A. S. Chem. Rev. 2011, 111, 1761−1779.
(j) Selander, N.; Szabo, K. J. Chem. Rev. 2011, 111, 2048−2076.
(k) Niu, J.-L.; Hao, X.-Q.; Gong, J.-F.; Song, M.-P. Dalton Trans. 2011,
40, 5135−5150. (l) Bhattacharya, P.; Guan, H. Comments Inorg. Chem.
2011, 32, 88−112. (m) van Koten, G. J. Organomet. Chem. 2013, 730,
156−164.
(5) (a) Hayashi, A.; Okazaki, M.; Ozawa, F.; Tanaka, R.
Organometallics 2007, 26, 5246−5249. (b) Muller, C.; Pidko, E. A.;
̈
Lutz, M.; Spek, A. L.; Vogt, D. Chem.Eur. J. 2008, 14, 8803−8807.
(c) van der Vlugt, J. I.; Pidko, E. A.; Vogt, D.; Lutz, M.; Spek, A. L.;
Meetsma, A. Inorg. Chem. 2008, 47, 4442−4444. (d) van der Vlugt, J.
I.; Pidko, E. A.; Vogt, D.; Lutz, M.; Spek, A. L. Inorg. Chem. 2009, 48,
7513−7515. (e) van der Vlugt, J. I.; Pidko, E. A.; Bauer, R. C.;
Gloaguen, Y.; Rong, M. K.; Lutz, M. Chem.Eur. J. 2011, 17, 3850−
3854. (f) Orthaber, A.; Belaj, F.; Pietshnig, R. Inorg. Chim. Acta 2011,
374, 211−215. (g) Nakajima, Y.; Shiraishi, Y.; Tsuchimoto, T.; Ozawa,
F. Chem. Commun. 2011, 47, 6332−6334.
(6) (a) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2004, 126,
2885−2893. (b) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2005,
127, 2030−2031. (c) Mankad, N. P.; Rivard, E.; Harkins, S. B.; Peters,
J. C. J. Am. Chem. Soc. 2005, 127, 16032−16033. (d) Harkins, S. B.;
Mankad, N. P.; Miller, A. J. M.; Szilagyi, R. K.; Peters, J. C. J. Am.
Chem. Soc. 2008, 130, 3478−3485.
(26) Bowmaker, G. A.; Engelhardt, L. M.; Healy, P. C.; Kildea, J. D.;
Papasergio, R. I.; White, A. H. Inorg. Chem. 1987, 26, 3533−3538.
(27) Altaf, M.; Stoeckli-Evans, H. Inorg. Chem. Acta 2010, 363,
2567−2573.
(28) (a) Churchill, M. R.; Kalra, K. L. Inorg. Chem. 1974, 13, 1899−
1904. (b) Churchill, M. R.; Rotella, F. J. Inorg. Chem. 1977, 16, 3267−
3273. (c) Dyason, J. C.; Healy, P. C.; Engelhardt, L. M.; Pakawatchai,
C.; Patrick, V. A.; Raston, C. L.; White, A. H. J. Chem. Soc., Dalton
(7) de Boer, S. Y.; Gloaguen, Y.; Lutz, M.; van der Vlugt, J. I. Inorg.
Chim. Acta 2012, 380, 336−342.
(8) Ghorai, D.; Kumar, S.; Mani, G. Dalton Trans. 2012, 41, 9503−
9512.
(9) (a) Kumar, S.; Mani, G.; Mondal, S.; Chattaraj, P. K. Inorg. Chem.
2012, 51, 12527−12539. (b) Gruger, N.; Wadepohl, H.; Gade, L. H.
̈
708
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709

Inorganic Chemistry
Article
Trans. 1985, 831−838. (d) Herberhold, M.; Akkus, N.; Milius, W. Z.
Anorg. Allg. Chem. 2003, 629, 2458−2464. (e) Lobana, T. S.; Kumar,
R.; Sharma, R.; Nishioka, T.; Castineiras, A. J. Coord. Chem. 2005, 58,
849−855. (f) Seddigi, Z. S.; Hossain, G. M. G.; Banu, A. Acta
Crystallogr., Sect. E: Struct. Rep. Online 2007, E63, m756−m758.
(29) (a) Perruchas, S.; Le Goff, X. F.; Maron, S.; Maurin, I.; Guillen,
F.; Garcia, A.; Gacoin, T.; Boilot, J.-P. J. Am. Chem. Soc. 2010, 132,
10967−10969. (b) Kitagawa, H.; Ozawa, Y.; Toriumi, K. Chem.
Commun. 2010, 46, 6302−6304. (c) Perruchas, S.; Tard, C.; Le Goff,
X. F.; Fargues, A.; Garcia, A.; Kahlal, S.; Saillard, J. Y.; Gacoin, T.;
Boilot, J. P. Inorg. Chem. 2011, 50, 10682−10692. (d) Liu, Z.;
Djurovich, P. I.; Whited, M. T.; Thompson, M. E. Inorg. Chem. 2012,
51, 230−236.
(49) Biegler-Konig, F.; Schonbohm, J.; Bayles, D. J. Comput. Chem.
2001, 22, 545−559.
̈
̈
(50) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, Jr., J. A.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.;
Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega,
N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.;
Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
(30) Kuang, S.-M.; Cuttell, D. G.; McMillin, D. R.; Fanwick, P. E.;
Walton, R. A. Inorg. Chem. 2002, 41, 3313−3322.
̈
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
(31) Palmer, C. E. A.; McMillin, D. R. Inorg. Chem. 1987, 26, 3837−
3840.
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.Gaussian 09,
revision A.1; Gaussian, Inc., Wallingford CT, 2009.
(51) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J.
(32) Cunningham, C. T.; Moore, J. J.; Cunningham, K. L. H.;
Fanwick, P. E.; McMillin, D. R. Inorg. Chem. 2000, 39, 3638−3644.
(33) (a) Miller, M. T.; Gantzel, P. K.; Karpishin, T. B. J. Am. Chem.
Soc. 1999, 121, 4292−4293. (b) Tsuboyama, A.; Kuge, K.; Furugori,
M.; Okada, S.; Hoshino, M.; Ueno, K. Inorg. Chem. 2007, 46, 1992−
2001. (c) Luo, S. P.; Mejía, E.; Friedrich, A.; Pazidis, A.; Junge, H.;
Surkus, A. E.; Jackstell, R.; Denurra, S.; Gladiali, S.; Lochbrunner, S.;
Beller, M. Angew. Chem., Int. Ed. 2013, 52, 419−423.
Appl. Crystallogr. 1993, 26, 343−350.
(52) (a) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112−122.
(b) Farrugia, L. J. Appl. Crystallogr. 1999, 32, 837−838.
(53) van der Sluis, P.; Spek, A. L. Acta Cryst. A 1990, 46, 194−201.
(34) Ganesamoorthy, C.; Balakrishna, M. S.; George, P. P.; Mague, J.
T. Inorg. Chem. 2007, 46, 848−858.
(35) Yap, G. P. A.; Rheingold, A. L.; Das, P.; Crabtree, R. H. Inorg.
Chem. 1995, 34, 3474−3476.
(36) (a) Rivas, J. C. M.; Brammer, L. Inorg. Chem. 1998, 37, 4756−
́
4757. (b) Aullon, G.; Bellamy, D.; Brammer, L.; Bruton, E. A.; Orpen,
A. G. Chem. Commun. 1998, 653−654. (c) Brammer, L.; Bruton, E. A.;
Sherwood, P. New J. Chem. 1999, 23, 965−968.
(37) Dadon, H.; Bernstein, J. Inorg. Chem. 1997, 36, 2898−2900.
(38) (a) Wehman-Ooyevaar, I. C. M.; Grove, D. M.; Kooijman, H.;
van der Suis, P.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1992,
114, 9916−9924. (b) Neve, F.; Crispini, A. Cryst. Growth Des. 2001, 1,
387−393. (c) Kumar, D. K.; Das, A.; Dastidar, P. Cryst. Growth Des.
2005, 5, 651−660. (d) Park, Y. J.; Kim, J.-S.; Youm, K.-T.; Lee, N.-K.;
Ko, J.; Park, H.-S.; Jun, M.-J. Angew. Chem., Int. Ed. 2006, 45, 4290−
4294. (e) Hoseini, S. J.; Mohamadikish, M.; Kamali, K.; Heinemann, F.
W.; Rashidi, M. Dalton Trans. 2007, 1697−1704. (f) Zuo, W.;
Braunstein, P. Organometallics 2010, 29, 5535−5543.
(39) Yang, L.; Houser, R. Inorg. Chem. 2006, 45, 9416−9422.
(40) Chiarella, G. M.; Melgarejo, D. Y.; Rozanski, A.; Hempte, P.;
Perez, L. M.; Reber, C.; Fackler, J. P., Jr. Chem. Commun. 2010, 46,
136−138.
(41) Ghassemzadeh, M.; Tabatabaee, M.; Soleimani, S.; Neumuller,
̈
B. Z. Anorg. Allg. Chem. 2005, 631, 1871−1876.
(42) (a) Majerz, I. J. Phys. Chem. A 2012, 116, 7992−8000.
(b) Popelier, P. L. A.; Bader, R. F. W. J. Phys. Chem. 1994, 98, 4473−
4481. (c) Piccoli, P. M. B.; Koetzle, T. F.; Schultz, A. J.; Zhurova, E. A.;
Stare, J.; Pinkerton, A. A.; Eckert, J.; Hadzi, D. J. Phys. Chem. A 2008,
112, 6667−6677. (d) Koch, U.; Popelier, P. L. A. J. Phys. Chem. 1995,
99, 9747−9754. (e) Popelier, P. L. A. J. Phys. Chem. 1998, 102, 1873−
1878.
(43) (a) Wolff, S. K.; Grimwood, D. J.; McKinnon, J. J.; Turner, M.
J.; Jayatilaka, D.; Spackman, M. A.; CrystalExplorer , version 3.0;
University of Western Australia, 2012. (b) Spackman, M. A.; Jayatilaka,
D. CrystEngComm 2009, 11, 19−32.
(44) Zhao, Y.; Truhlar, D. G. Theor. Chem. Acc. 2008, 120, 2008215−
2008241.
(45) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B: Condens. Matter
Mater. Phys. 1998, 37, 785−789.
(46) (a) Foster, J. P.; Weinhold, F. J. Am. Chem. Soc. 1980, 102,
7211−7218. (b) Reed, A. E.; Weinstock, R. B.; Weinhold, F. J. Chem.
Phys. 1985, 83, 735−746.
(47) Martin, F.; Zipse, H. J. Comput. Chem. 2005, 26, 97−105.
(48) Becke, A. D. J. Chem. Phys. 1993, 98, 1372−1377.
709
dx.doi.org/10.1021/ic402253y | Inorg. Chem. 2014, 53, 700−709