Bi-, tetra-, and hexanuclear AuI and binuclear AgI complexes and AgI coordination polymers containing phenylaminobis(phosphonite), PhN{P(OC6H4OMe-o) 2}2, and pyridyl ligands

Article abstract of DOI:10.1021/ic702133f

The reactions of phenylaminobis(phosphonite), PhN{P(OC₆H ₄OMe-o)₂}₂ (1) (PNP), with [AuCl(SMe ₂)] in appropriate ratios, afford the bi- and mononuclear complexes, [(AuCl)₂(μ-PNP)] (2) and [(AuCl)(PNP)]₂ (3) in good yield. Treatment of 2 with 2 equiv of AgX (X = OTf or ClO₄) followed by the addition of 1 or 2,2′-bipyridine affords [Au₂(μ-PNP) ₂](OTf)₂ (4) and [Au₂(C₁₀H ₈N₂)₂(μ-PNP)](ClO₄)₂ (5), respectively. Similarly, the macrocycles [AU₄(C ₄H₄N₂)₂(μ-PNP) ₂](ClO₄)₄ (6), [Au₄(C ₁₀H₈N₂)₂(μ-PNP) ₂](ClO₄)₄ (7), and [Au₆(C ₃H₃N₃)₂(μ-PNP) ₃](ClO₄)₆ (8) are obtained by treating 2 with pyrazine, 4,4′-bipyridine, or 1,3,5-triazine in the presence of AgClO ₄. The reaction of 1 with AgOTf in a 1:2 molar ratio produces [Ag₂(μ-OTf)₂(μ-PNP)] (9). The displacement of triflate ions in 9 by 1 leads to a disubstituted derivative, [Ag ₂(μ-PNP)₃](OTf)₂ (10). The equimolar reaction of 1 with AgClO₄ in THF affords [Ag₂(C ₄H₈O)₂(μ-PNP)₂](ClO ₄)₂ (11). Treatment of 1 with AgClO₄ followed by the addition of 2,2′-bipyridine affords a discrete binuclear complex, [Ag₂(C₁₀H₈N₂)₂(μ-PNP)] (ClO₄)₂ (12), whereas similar reactions with 4,4′-bipyridine or pyrazine produce one-dimensional zigzag Ag^I coordination polymers, [Ag₂(C₁₀H₈N ₂)(μ-ClO₄)(ClO₄)(μ-PNP)]_n (13) and [Ag₂(C₄H₄N₂)(μ-ClO ₄)(ClO₄)(μ-PNP)]_n (14) in good yield. The nature of metal-metal interactions in compounds 2, 4, 5, and 12 was analyzed theoretically by performing HF and CC calculations. The structures of the complexes 2, 4, 5, 7, 9, 12, and 14 are confirmed by single crystal X-ray diffraction studies.

Full text of DOI:10.1021/ic702133f

Inorg. Chem. 2008, 47, 2764-2776
Bi-, Tetra-, and Hexanuclear AuI and Binuclear AgI Complexes and AgI
Coordination Polymers Containing Phenylaminobis(phosphonite),
PhN{P(OC6H4OMe-o)2}2, and Pyridyl Ligands
Chelladurai Ganesamoorthy,† Maravanji S. Balakrishna,*,† Joel T. Mague,‡ and Heikki M. Tuononen§
Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology, Bombay, Powai,
Mumbai 400 076, India, Department of Chemistry, Tulane UniVersity, New Orleans, Lousiana
70118, and Department of Chemistry, UniVersity of JyVäskylä,
P.O. Box 35, JyVäskylä, FI-40014, Finland
Received October 30, 2007
The reactions of phenylaminobis(phosphonite), PhN{P(OC6H4OMe-o)2}2 (1) (PNP), with [AuCl(SMe2)] in appropriate
ratios, afford the bi- and mononuclear complexes, [(AuCl)2(µ-PNP)] (2) and [(AuCl)(PNP)]2 (3) in good yield. Treatment
of 2 with 2 equiv of AgX (X ) OTf or ClO4) followed by the addition of 1 or 2,2′-bipyridine affords [Au2(µ-PNP)2](OTf)2
(4) and [Au2(C10H8N2)2(µ-PNP)](ClO4)2 (5), respectively. Similarly, the macrocycles [Au4(C4H4N2)2(µ-PNP)2](ClO4)4
(6), [Au4(C10H8N2)2(µ-PNP)2](ClO4)4 (7), and [Au6(C3H3N3)2(µ-PNP)3](ClO4)6 (8) are obtained by treating 2 with pyrazine,
4,4′-bipyridine, or 1,3,5-triazine in the presence of AgClO4. The reaction of 1 with AgOTf in a 1:2 molar ratio
produces [Ag2(µ-OTf)2(µ-PNP)] (9). The displacement of triflate ions in 9 by 1 leads to a disubstituted derivative,
[Ag2(µ-PNP)3](OTf)2 (10). The equimolar reaction of 1 with AgClO4 in THF affords [Ag2(C4H8O)2(µ-PNP)2](ClO4)2
(11). Treatment of 1 with AgClO4 followed by the addition of 2,2′-bipyridine affords a discrete binuclear complex,
[Ag2(C10H8N2)2(µ-PNP)](ClO4)2 (12), whereas similar reactions with 4,4′-bipyridine or pyrazine produce one-dimensional
zigzag AgI coordination polymers, [Ag2(C10H8N2)(µ-ClO4)(ClO4)(µ-PNP)]n (13) and [Ag2(C4H4N2)(µ-ClO4)(ClO4)(µ-
PNP)]n (14) in good yield. The nature of metal-metal interactions in compounds 2, 4, 5, and 12 was analyzed
theoretically by performing HF and CC calculations. The structures of the complexes 2, 4, 5, 7, 9, 12, and 14 are
confirmed by single crystal X-ray diffraction studies.
Introduction
tectures via intra- and intermolecular aggregations.4 The term
“aurophilicity” has been introduced to describe the AuI-AuI
bonding interactions which are comparable in energy with
hydrogen bonding.5 The similar argentophilic and cuprophilic
interactions of AgI and CuI are weaker, and theoretical studies
by O’Grady and Kaltsoyannis showed that the strength of
the metallophilicity decreases in the order AuI > AgI > CuI.6
Although there is ample support for the existence of
aurophilicity, examples of metal-metal interactions unsup-
For the past few decades there has been continued interest
in the chemistry of d10 metal systems because of their rich
photochemical properties,1 catalytic applications,2 and use
in drug discovery.3 In addition to a variety of coordination
geometries, the short metal-metal contacts, described as
“metallophilicity”, have been employed in the construction
of several macrocyclic molecules and supramolecular archi-
* To whom correspondence should be addressed. Tel.: +91 22 2576
7181. Fax: +91 22 2576 7152/2572 3480. E-mail: krishna@chem.iitb.ac.in.
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†
Indian Institute of Technology.
‡
Tulane University.
University of Jyväskylä.
§
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2764 Inorganic Chemistry, Vol. 47, No. 7, 2008
10.1021/ic702133f CCC: $40.75  2008 American Chemical Society
Published on Web 02/13/2008

AuI and AgI Complexes and AgI Coordination Polymers
ported by bridging ligands in CuI and AgI systems are
exceedingly rare.7 Fackler and co-workers investigated the
importance of this metal-metal interaction in the photo-
physical properties in a range of Group 11 metal complexes
and described the emission energy due to metallophilicity
as a function of both metal-metal interactions and the nature
of the ligands.8
Scheme 1
In recent years, several strategies have been developed for
the construction of highly soluble polynuclear d10 metal
complexes using bi- or tridentate phosphorus based ligands.9
In particular, special emphasis has been focused on the use
of bis(diphenylphosphino)methane (dppm) with chalco-
genides.10 Although the transition metal chemistry of the
analogous short-bite aminobis(phosphine) ligand system,
X2PN(R)PX2, has been extensively studied,11 comparatively
little work has been reported on the use of these systems in
the synthesis of macromolecules and metallapolymers with
or without the assistance of other ligands such as pyridyl
ligands.12 Recently, we have reported novel tetranuclear
macrocycles and coordination polymers formed by the
interaction of the “short-bite” aminobis(phosphonite), PhN-
(P(OC6H4OMe-o)2)2 (PNP) (1), with CuI halides in the
presence of bipyridyl linkers.13 The coordination behavior
of 1 with copper(I) salts was similar to that of the PCP type
ligands, but the coordination geometries of the resulting
complexes were entirely different. In this context, we wanted
to investigate the coordinating behavior of 1 with AgI and
AuI metals as the short bite of the ligand can induce effective
metal-metal interactions. Further, the presence of pyridyl
ligands can alter the electronic properties as well. As a part
of our interest14 and that of others15 in the transition metal
chemistry of cyclic and acyclic diphosphazane ligands, we
describe in this paper the first examples of mixed-ligand AuI
and AgI complexes containing the “short-bite” aminobis-
(phosphonite), PhN(P(OC6H4OMe-o)2)2 (PNP) (1), and N-
hetero aromatic amines. This includes the formation of novel
tetra- and hexanuclear AuI macrocycles and AgI coordination
polymers. The crystal and molecular structures of several
bi- and tetranuclear complexes including a novel AgI
coordination polymer are also described.
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Results and Discussion
AuI Chloride Derivatives. The reaction of the aminobis-
(phosphonite), PhN(P(OC6H4OMe-o)2)2 (hereafter referred
as PNP) (1), with [AuCl(SMe2)] in a 1:2 molar ratio leads
to the formation of a binuclear complex, [(AuCl)2(µ-PNP)]
(2), with the ligand exhibiting the bridging mode of
coordination. A similar reaction in equimolar ratio furnishes
a mono-coordinated complex, [(AuCl)(PNP)] (3), along with
a small quantity of 2. Treatment of complex 2 with 1 in an
equimolar ratio also produces 3 in quantitative yield as shown
in Scheme 1. The 31P NMR spectrum of 2 consists of a single
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Inorganic Chemistry, Vol. 47, No. 7, 2008 2765

Ganesamoorthy et al.
Scheme 2
peak at 114.3 ppm whereas 3 shows two doublets centered
at 112.2 and 133.8 ppm, with a large JPP coupling of 341
(6) and [Au4(C10H8N2)2(µ-PNP)2](ClO4)4 (7) in good yield.
In both complexes, the binuclear (µ-PNP)Au2 moieties are
bridged by bipyridyl ligands. Extensive investigations by
Puddephatt and co-workers on similar systems have shown
that a crossover from macrocyclic ring to sinusoidal polymer
was observed when the length of the spacer between the two
phosphorus atoms increases.17 However, this is not true in
all cases, and the recent report by the same group has shown
that ligands of the type Ph2P(CH2)nPPh2 (n ) 1, 3, or 5)
prefer to form tetranuclear macrocycles instead of polymeric
chains.18 This leads to the conclusion that the steric/electronic
effects may not play any role in the formation of a particular
complex. Instead, both the macrocyclic and the polymeric
complexes could exist in a rapid equilibrium in solution with
the least soluble complex preferentially crystallizing or
precipitating from the solution. Because there is no report
on the formation of a AuI polymer with R2PQPR2 (Q )
-NR′ or -CH2) ligands, we believe that the “rigid short-
bite” R2PN(R′)PR2 (where R, R′ ) alkyl or aryl) ligands
with bulky substituents around the phosphorus centers will
prefer to form thermodynamically favored ring structures
instead of forming the polymers.19 The analogous hexa-
nuclear species [Au6(C3H3N3)2(µ-PNP)3](ClO4)6 (8) was
2
Hz.16 The 1H NMR spectra of 2 and 3 show single
resonances corresponding to the ortho-methoxy groups at
3.82 and 3.71 ppm, respectively. The structure of complex
2 was confirmed by an X-ray structure determination.
Bi-, Tetra-, and Hexanuclear AuI Macrocycles. Com-
plex 2 is a potential precursor for the preparation of various
bi-, tetra-, and hexanuclear gold(I) macrocycles due to the
presence of two highly polar Au-Cl bonds. Treatment of
complex 2 with silver salts of poorly coordinating anions
followed by the addition of bi- or tridentate ligands resulted
in the formation of interesting mixed ligand complexes as
shown in Scheme 2. The reaction of 2 with 2 equiv of AgOTf
followed by the addition of ligand 1 gives the binuclear
complex [Au2(µ-PNP)2](OTf)2 (4) whereas the similar reac-
tion with AgClO4 and then 2,2′-bipyridine produces the
complex [Au2(C10H8N2)2(µ-PNP)2](ClO4)2 (5) in good yield.
The 31P NMR spectra of complexes 4 and 5 show single
resonances at 121.9 and 112.0 ppm, respectively. The spectral
and analytical data support the proposed formulations of
complexes 4 and 5, and their structures were confirmed
through single crystal X-ray diffraction studies.
The reactions of 2 with 2 equiv of AgClO4 followed by
addition of 1 equiv of pyrazine or 4,4′-bipyridine produce
the tetranuclear macrocycles [Au4(C4H4N2)2(µ-PNP)2](ClO4)4
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2766 Inorganic Chemistry, Vol. 47, No. 7, 2008

AuI and AgI Complexes and AgI Coordination Polymers
Scheme 3
prepared by reacting 2 with AgClO4 and 1,3,5-triazine in a
3:6:2 molar ratio. The 31P NMR spectra of complexes 6-8
exhibit single resonances at 117.0, 110.5, and 111.4 ppm,
respectively, indicating effective equivalence of all phos-
phorus atoms. The crystal structure of 7 has been established
through a single crystal X-ray diffraction study. Complexes
2-8 are colorless, air stable, crystalline solids, highly soluble
in CH2Cl2, CHCl3, and THF. Although these complexes are
moderately stable to air, they turn purple after keeping for a
long time even under inert atmosphere.
due to the ortho-methoxy and aromatic protons appear in
the appropriate regions with the expected relative intensities.
1
Although the JAgP values for complexes 9-11 are signifi-
cantly larger than that observed in analogous phosphine
systems, the expected decrease in 1JAgP values as the number
of phosphorus atoms around AgI increases from 1 to 3 is
consistent with the previous observations in analogous
systems.20 However, low temperature NMR could not be
performed because of the poor solubility of the complexes
in solvents other than DMSO. The structure of complex 9
was established through a single crystal X-ray diffraction
study.
Treatment of 1 with AgClO4 in the presence of 2 equiv
of 2,2′-bipyridine produces a binuclear complex, [Ag2(C10H8-
N2)2(µ-PNP)](ClO4)2 (12), whereas the similar reactions with
4,4′-bipyridine or pyrazine afford one-dimensional zigzag
AgI coordination polymers, [Ag2(C10H8N2)(µ-ClO4)(ClO4)(µ-
PNP)]n (13) and [Ag2(C4H4N2)(µ-ClO4)(ClO4)(µ-PNP)]n (14),
in quantitative yield. The structure of complex 12 is
analogous to the AuI derivative 5 in which the metal centers
have trigonal planar geometry being surrounded by a
phosphorus atom and a chelating 2,2′-bipyridine ligand. The
31P NMR spectrum of complex 12, analogous to the spectra
observed for the complexes, [Ag2(CH3CN)2(ClO4)(µ-
dppm)2]21 and [AgNO2(µ-dppm)]2,22a consists of a well-
resolved A portion of an AA′XX′ multiplet centered at 119.8
ppm with a [1JAgP] value of 930 Hz. Because of the poor
solubility of complex 13 in most suitable solvents, NMR
spectroscopic studies could not be carried out, but the
molecular composition was confirmed from elemental analy-
sis data. The 31P NMR spectrum of complex 14 shows a
broad singlet at 123.5 ppm. The analytical data supports the
proposed structures for complexes 12-14, and the structures
Silver(I) Derivatives. The reaction of 1 with AgOTf in a
1:2 mole ratio leads to the formation of a binuclear complex,
[Ag2(µ-OTf)2(µ-PNP)] (9), in quantitative yield. In complex
9, the AgI atoms are bridged by a pair of trifluoromethane-
sulfonate ions and a PNP ligand so as to provide trigonal
planar geometry around the AgI centers. The displacement
of trifluoromethanesulfonate ligands in 9 by 2 equiv of 1
afforded a “manxane”-like triply bridged binuclear complex,
[Ag2(µ-PNP)3](OTf)2 (10), as shown in Scheme 3. The 31P
NMR spectrum of complex 9 consists of the A portion of a
AA′XX′ multiplet centered at 116.7 ppm, whereas the
resonance due to 10 appears at 120.8 ppm as a broad
singlet.20 The complex, [Ag2(C4H8O)2(µ-PNP)2](ClO4)2 (11),
has been prepared by reacting an equimolar amount of 1
with AgClO4 in THF. In the 31P NMR spectrum of complex
11, the resonance appears at 109.2 ppm as a broad doublet
1
due to the complex spin system. In the H NMR spectrum,
the resonances corresponding to the coordinated THF
molecules appear as two triplets centered at 1.84 and 3.73
ppm with an apparent JHH coupling of 3.6 Hz. The resonance
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Inorganic Chemistry, Vol. 47, No. 7, 2008 2767

Ganesamoorthy et al.
Table 1. NMR Data for Compounds 1–14
1H NMR (in ppm)
31P{1H}
compound
NMR (in ppm)
OCH3
aryl protons
1
2
3
132.2 (s)
114.3 (s)
133.8 (d)
3.62 (s)
3.82 (s)
6.76–7.60 (m)
6.82–7.78 (m)
112.2 (d)
3.71 (br s)
6.80–7.65 (m)
2JPP ) 341 Hz
121.9 (s)
4
5
6
7
8
9
10
11
12
3.60 (s)
3.88 (s)
3.92 (s)
3.85 (s)
3.76 (s)
3.88 (s)
3.56 (s)
3.43 (s)
6.44–7.59 (m)
6.86–8.37 (m)
6.66–8.70 (m)
6.79–8.52 (m)
6.42–8.80 (m)
6.42–7.70 (m)
6.78–7.52 (m)
6.76–7.55 (m)
112.0 (s)
117.0 (br s)
110.5 (s)
111.4 (s)
116.7 (m)
120.8 (br s)
109.2 (m)
119.8 (m)
2JPP ) 67 Hz
123.5 (br s)
3.73 (s)
3.74 (s)
6.64–8.00 (m)
6.72–8.47 (m)
14
of complexes 12 and 14 are confirmed by single crystal X-ray
diffraction studies. Although the complexes 9-14 are
moderately stable to air, they undergo dissociation in solution
1
to give insoluble metallic residues. Full H and 31P NMR
spectral data for complexes 1-12 and 14 are given in
Table 1.
Figure 2. Molecular structure of 4. All hydrogen atoms and lattice solvents
have been omitted for clarity. Displacement ellipsoids are drawn at the 50%
probability level.
Crystal and Molecular Structures of 2, 4, 5, 7, 9, 12,
and 14. Perspective views of the molecular structures of
compounds 2, 4, 5, 7, 9, 12, and 14 with atom numbering
schemes are shown in Figures 1-7, respectively. A full
tabulation of intramolecular Au · · · Au distances and Au-P
bond lengths in complexes having the R2PQPR2 (Q ) -NR′
or -CH2) framework for comparison with the results
presented here is given in Table 2, crystal data and the details
of the structure determinations in Table 3, and selected bond
lengths and bond angles in Tables 4-6. The molecular
structure of 2 consists of a discrete [(µ-PNP)(AuCl)2] species
having crystallographically imposed twofold rotation sym-
metry. The AuI center adopts an approximately linear
geometry with a P-Au-Cl angle of 173.21(2)°. The
P-Au-Cl units are cis-oriented, there are no close non-
bonded contacts to the chlorine atoms, and the intramolecular
Au · · · Au distance is 3.124 Å. This is well within the
Au· · ·Au distances considered to represent aurophilic inter-
Figure 3. Molecular structure of 5. All hydrogen atoms, a perchlorate ion,
and lattice solvents have been omitted for clarity. Displacement ellipsoids
are drawn at the 50% probability level.
actions. That it indicates an attractive interaction and not
just an approach enforced by ligand constraints (the intrali-
gand P · · ·P separation is 2.861(2) Å) is indicated by the fact
that the gold atoms are displaced toward each other from
the positions they would have occupied were the P-Au-Cl
moieties strictly linear. The Au-P and Au-Cl bond dis-
tances are 2.206(1) Å and 2.285(1) Å, respectively, while
the P-N-Pi bond angle is 117.11(17)°.
The complex 4 consists of a planar eight-membered
diauracycle, [-P1-N-P2-Au]2, having crystallographically
imposed centrosymmetry. The aminobis(phosphonite) ligands
bridge the two metal centers from opposite sides so as to
Figure 1. Molecular structure of 2. All hydrogen atoms have been omitted
for clarity. Displacement ellipsoids are drawn at the 50% probability level.
2768 Inorganic Chemistry, Vol. 47, No. 7, 2008

AuI and AgI Complexes and AgI Coordination Polymers
Figure 4. Molecular structure of 7. All hydrogen atoms and perchlorate ions have been omitted for clarity. Displacement ellipsoids are drawn at the 50%
probability level.
Figure 5. Molecular structure of 9. All hydrogen atoms have been omitted
for clarity. Displacement ellipsoids are drawn at the 50% probability level.
provide an approximate linear geometry around each AuI
(P1-Au-P2 ) 173.50(3)°). This brings the two AuI centers
Figure 6. Molecular structure of 12. All hydrogen atoms and lattice solvents
in close proximity with an intramolecular Au · · ·Au distance
have been omitted for clarity. Displacement ellipsoids are drawn at the 50%
probability level.
of 2.907(1) Å and, as this is shorter than the intraligand P · · ·P
separation (2.982(3) Å), an attractive interaction exists. As
expected, the P1-Au and P2-Au bond distances (2.292(1)
Å and 2.314(1) Å) are longer than those of the corresponding
chloro derivative 2 because of the greater trans influence of
the phosphonite moiety. The complex has two slightly
different P-N bonds with bond distances of 1.662(3) Å and
1.677(3) Å while the P1-N-P2 angle is 126.59(17)° which
is larger than that observed in free ligand (116.07(12)°). The
trifluoromethanesulfonate ion participates in a number of
significant C-H · · · O and C-H · · · F hydrogen bonding
interactions with neighboring phenyl groups which leads to
efficient packing of cations and anions. Specifically, O11
makes contacts of 2.44 Å with H19 (C19-H19 · · ·O11 angle
) 169°), 2.46 Å with H5 (at -x, 2 - y, 1 - z; C5-H5 · · ·O11
angle ) 163°), and 2.67 Å with H12 (C12-H12· · ·O11 angle
) 155°). These are comparable to or less than the average
C-H · · · O of 2.62 Å given by Steiner.22b In addition, H32
makes a contact of 2.49 Å with F1 (at x, 2.5 - y, 0.5 + z;
C32-H32 · · · F1 angle ) 178°) and H33 contacts F1 (at -x,
0.5 + y, 0.5 - z; C33-H33 · · · F1 angle ) 151°) at 2.58 Å.
These can be compared with an average C-H · · · F distance
of 2.60 Å given by Brammer et al.22c
In complex 5, the AuI atoms have trigonal planar geometry
being surrounded by two nitrogen atoms and a phosphorus
atom. The sum of the angles around the Au1 and Au2 centers
Inorganic Chemistry, Vol. 47, No. 7, 2008 2769

Ganesamoorthy et al.
Figure 7. Molecular structure of 14. All hydrogen atoms have been omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level.
View axes: -86.99X, -22.32Y, - 3.48Z. Symmetry operation i ) - 0.5 + x, y, 0.5 - z, ii ) 0.5 + x, y, 0.5 - z.
Table 2. Au· · ·Au and Au-P Distancesa
bond distance (Å)
complex
Au · · ·Au
3.351(2)
P-Au
2.238(1)
reference
[Au2Cl2(µ-dppm)]
26a
[Au3Cl2(µ-dppm)2][Au(C6F5)3Cl]
[Au3Cl2(µ-dppm)2]Cl
3.067(5), 3.164(5)
3.076(1)
3.163(1)
3.133(1)
3.106(1), 3.084(1)
3.148(1)
3.221(2), 3.131(2)
3.133(3)
3.332(1)
3.035(1)
3.135(1)
2.880(1)
2.867(1)
3.575(1)
3.048(1)
3.159(1)
3.028(2)
3.023(1)
3.045(1)
2.925(3)
2.988(1)
2.992(1)
2.939(1)
3.076(1)
3.418(1)
3.166(1)
2.993(1)
3.093(1)
2.984(1)
3.438(1)
2.838(2)
3.037(1)
2.840(1)
3.071(1)
3.124(1)
2.907(1)
3.058(1)
3.108(1)
2.322(1)-2.243(1)
2.319(3), 2.240(3)
2.288(3), 2.279(3)
2.234(5), 2.231(5)
2.230(3)-2.241(3)
2.239(2), 2.235(2)
2.271(1)-2.287(1)
2.309(9), 2.313(9)
2.261(1), 2.259(1)
2.259(1), 2.266(2)
2.252(2), 2.250(2)
2.235(2), 2.279(2)
2.241(3), 2.279(3)
2.253(1)
26b
26c
26d
26e
18
19b
19a
17c
27a
27b
27c
27d
27d
27e
28a
28b
28c
28c
28d
28e
29a
29a
29a
29a
29b
29b
29b
29b
29b
29c
29d
29d
[{Au(C5F5)}2(µ-dppm)]
[m-(µ-dppm)Au2(pzH)2](ClO4)2
[Au2(µ-dppm)(4,4′-bpy)]2[CF3CO2]4
[(µ-dppm)Au2L]2(ClO4)4
[{Au4(µ-dppm)2(CtCC6H4N)4]
[{Au4(µ-dcpm)2(CtNC6H4NtC)2]
[(µ-dppm){Au(2-SPym-4-NH2)}2]
[Au2(µ-dppm){S2P(p-C6H4)(OC5H9)}2]
[{Au(2-SC6H4NH2)}2(µ-dppm)]
[Au2(µ-dppm)(TU)]
[Au2(µ-dppm)(Me-TU)]
[(µ-dppm)(AuI)2]
[(µ-dppm)Au2(C5H4NS)2]
2.261(1), 2.270(1)
2.265(1)
2.313(5)
2.304(2)
2.289(3)
[(µ-dppm){AuSC(OMe)dNC6H4NO2-4}2]
[Au2(µ-dmpm)2](ClO4)2
[Au2(µ-dmpm)2]Br2
[Au2(µ-dmpm)2](PF6)2
[Au2(µ-dmpm)(µ-S2C2(CN)2)]
[Au2(µ-dcpm)2][Au(CN)2]2
[Au2(µ-dcpm)2]Cl2
2.268(1), 2.253(1)
2.307(2), 2.316(2)
2.309(1)-2.328(1)
2.317(3), 2.320(3)
2.342(3), 2.321(2)
2.236(1), 2.236(1)
2.244(1), 2.240(1)
2.309(2), 2.330(2)
2.268(2), 2.279(2)
2.299(1), 2.302(1)
2.257(2), 2.267(2)
2.298(5), 2.313(6)
2.313(2), 2.228(2)
2.350(3), 2.396(3)
2.264(2), 2.271(2)
2.206(1)
[Au2(µ-dcpm)2](CO4)2
[Au2(µ-dcpm)2]I2
[Au2Cl2(µ-iPr2PCH2PPh2)]
[Au2Br2(µ-iPr2PCH2PPh2)]
[Au2I2(µ-iPr2PCH2PPh2)2]
[{Au(C5F5)}2(µ-iPr2PCH2PPh2)]
[Au2(µ-iPr2PCH2PPh2)2](CF3SO3)2
[{µ-Ph2PN(C6H11)PPh2}Au2(SC6H4F-p)2]
[Au2{µ-Ph2PN(Et)PPh2}2][SbF6]2
[Au3Cl2{µ-Ph2PN(Et)PPh2}2]PF6
[{µ-Ph2PN(nPr)PPh2}Au2(CtCPh)2]
[{µ-Ph2PN(nPr)PPh2}Au2(CtCC6H4OMe-p)2]
[(AuCl)2(µ-PNP)]
29e
29e
this work
this work
this work
this work
[Au2(µ-PNP)2](OTf)2
2.292(1), 2.314(1)
2.176(2), 2.168(2)
2.216(1), 2.203(1)
[Au2(2,2′-bpy)2(µ-PNP)2](ClO4)2
[Au4(4,4′-bpy)2(µ-PNP)2](ClO4)4
a dppm ) bis(diphenylphosphino)methane; pzH ) 3,5-dimethylpyrazole; L ) N,N′-bis-4-methylpyridyl oxalamide; dcpm ) bis(dicyclohexylphosphi-
no)methane; 2-SPym-4-NH2 ) 4-amino-2-pyrimidine-thiol; TU ) 2-thiouracil; Me-TU ) 6-methyl-2-thiouracil; dmpm ) bis(dimethylphosphino)methane.
2770 Inorganic Chemistry, Vol. 47, No. 7, 2008

AuI and AgI Complexes and AgI Coordination Polymers
are 358.8° and 359.8°, respectively. The Au1-P1 and the
Au2-P2 bond distances (2.1757(15) Å and 2.1677(15) Å)
are shorter than those observed in 2 and 3 while the Au-N
bond distances vary from 2.235(6) Å to 2.254(6) Å and the
bite angles created by the 2,2′-bipyridines at the Au1 and
Au2 centers are 72.42(17)° and 73.0(2)°, respectively. Even
though the two bipyridyl rings are parallel to each other,
there are no significant π-π interactions as a twist of the
PAuNN planes about the Au1 · · ·Au2 axis by 19.9(1)° makes
the two bipyridyl rings to slip away from each other. The
perchlorate ion forms a C-H · · · O hydrogen bond with H33
(H33· · ·O14 ) 2.46 Å; C33-H33· · ·O14 angle ) 151°) and
weaker contacts with other C-H units surrounding it.
The molecular structure of 7 consists of a 26-membered
macrocyclic ring containing four gold(I) centers which are
bridged by two aminobis(phosphonite) and two 4,4′-bipyri-
dine ligands. The molecule has crystallographically imposed
centrosymmetry with the inversion center at the middle of
the macrocyclic ring. The geometry about each gold(I) center
is approximately linear with P1-Au1-N2 and P2-Au2-N3
bond angles of 173.18(11) and 170.58(10), respectively, and
an Au · · · Au distance of 3.108 Å. As with 2, there appears
to be an attractive Au · · · Au interaction since the observed
Au · · · Au separation is shorter than the value of approxi-
mately 3.29 Å which would be expected for two noninter-
acting gold atoms placed on the lines directly connecting
P1 with N2 and P2 with N3. As the Cl and N-donor ligands
have approximately the same trans influence, the P1-Au1
and P2-Au2 bond distances (2.216(1) Å and 2.203(1) Å)
are quite similar to those observed in 3 while the P1-N1
and P2-N1 bond distances are 1.671(4) Å and 1.664(4) Å,
respectively. The bipyridyl moieties are roughly parallel to
one another, and the torsion angle between the two pyridyl
rings is 26.8(6)° (C38-C37-C42_a-C41_a). There is a
particularly strong C-H · · · O hydrogen bond between H39
and O13 of one perchlorate ion (H39 · · · O13 ) 2.28 Å;
C39-H39 · · · O13 angle ) 158°) and a weaker one of 2.40
Å between H41 and O9 (at x, y, -1 + z; C41-H41 · · ·O9
angle ) 164°). There are additional contacts of approximately
2.6 Å which primarily involve phenyl hydrogen atoms
surrounding the remainder of the perchlorate ions.
The crystals of 9 suitable for X-ray diffraction analysis
were grown by keeping the saturated THF solution of 9 at
room temperature for several days (in the dark). The
molecular structure consists of two nonequivalent silver ions
[trigonal planar (Ag1) and tetrahedral (Ag2) due to THF
coordination] bridged by a pair of cis-trifluoromethane-
sulfonate ions and a PNP ligand with an Ag1 · · ·Ag2 distance
of 3.016(1) Å. This value is longer than those found in the
analogous complex [Ag2(µ-dcpm)(µ-O2CCF3)2] (2.889(1)
Å)7c but shorter than those found in [Ag2(dppm)2(NO3)2]
(3.085 Å) and [Ag3(dppm)3Br2]Br (3.362(3)-3.192(3) Å)9f
indicating the possibility of a weak metal-metal interaction.
However, with three bridging ligands whose distances
between donor atoms are all less than the Ag · · · Ag separa-
tion, the latter value may simply be the result of compression
of the two metals by the short bites of the bridging ligands.
The complex has two slightly different Ag-P bonds
Inorganic Chemistry, Vol. 47, No. 7, 2008 2771

Ganesamoorthy et al.
Table 4. Selected Bond Distances and Bond Angles for Complexes 2, 4, and 5
complex 2 complex 4
bond distance (Å) bond angle (deg) bond distance (Å) bond angle (deg)
complex 5
bond angle (deg)
bond distance (Å)
P-N
1.676(2) P-N-P
1.600(2) N-P-Au
1.598(2) P-Au-Cl 173.21(2) P1-Au
2.206(1) Au-P-O1 115.87(7) P2-Au
2.285(1) Au-P-O3 114.65(7) Au-Au_a 2.907(1) Au-P1-N
117.11(2) P1-N
117.82(8) P2-N
1.662(3) P1-N-P2
126.59(2) P1-N1
1.683(5) P1-N1-P2
123.9(3)
P-O1
P-O3
P-Au
Au-Cl
1.677(3) P1-Au-P2 173.50(3) P2-N1
1.684(5) P1-Au1-N2 143.14(1)
2.176(2) P1-Au1-N3 143.19(1)
2.168(2) P2-Au2-N4 139.24(2)
2.247(5) P2-Au2-N5 147.52(2)
2.292(1) P1-Au-Au
2.314(1) P2-Au-Au
91.13(3) Au1-P1
90.47(2) Au2-P2
115.81(1) Au1-N2
115.38(1) Au1-N3
Au· · ·Au 3.124(1)
P1-O1
P1-O3
P2-O5
P2-O7
1.595(3) Au-P2-N
2.250(4) N2-Au1-N3
2.254(6) N4-Au2-N5
2.235(6) Au1-P1-O1 118.22(2)
1.594(4) Au1-P1-O3 114.71(2)
1.614(4) Au2-P2-O5 115.96(2)
1.602(4) Au2-P2-O7 120.31(2)
1.589(4) Au1-P1-N1 119.10(2)
72.42(2)
73.0(2)
1.588(3) Au-P1-O1 114.72(1) Au2-N4
1.582(3) Au-P1-O3 116.06(1) Au2-N5
1.589(3) Au-P2-O5 121.86(1) P1-O1
Au-P2-O7 112.64(1) P1-O3
P2-O5
P2-O7
Au1-Au2 3.058(1) Au2-P2-N1 115.46(2)
Table 5. Selected Bond Distances and Bond Angles for Complexes 7, 9, and 12
complex 7 complex 9
bond distance (Å) bond angle (deg) bond angle (deg)
complex 12
bond distance (Å)
bond distance (Å)
bond angle (deg)
121.62(1)
P1-N1
P2-N1
Au1-P1
Au2-P2
1.671(4) P1-N1-P2
123.4(2) P1-N
1.678(2) P1-N-P2
121.01(1) P1-N1 1.672(2) P1-N1-P2
1.664(4) P1-Au1-N2 173.18(1) P2-N
2.216(1) P2-Au2-N3 170.58(1) P1-Ag1
2.203(1) Au1-P1-N1 118.72(1) P2-Ag2
1.675(2) P1-Ag1-Ag2 90.04(1) P2-N1
2.348(1) P2-Ag2-Ag1 85.93(1) Ag1-P1
2.354(1) P1-Ag1-O9 123.69(5) Ag2-P2
1.671(2) P1-Ag1-N2 139.89(6)
2.321(1) P1-Ag1-N3 145.66(6)
2.315(1) P2-Ag2-N4 143.47(6)
Au1-N2 2.074(4) Au2-P2-N1 119.21(1) Ag1-Ag2 3.016(1) P1-Ag1-O12 145.26(5) Ag1-N2 2.279(2) P2-Ag2-N5 141.63(6)
Au2-N3 2.080(4) Au1-P1-O1 110.02(1) Ag1-O9 2.359(2) P2-Ag2-O10 132.85(6) Ag1-N3 2.268(2) N2-Ag1-N3
73.04(9)
73.08(9)
P1-O1
P1-O3
P2-O5
P2-O7
1.599(3) Au1-P1-O3 119.63(1) Ag1-O12 2.247(2) P2-Ag2-O13 126.67(5) Ag2-N4 2.261(2) N4-Ag2-N5
1.583(3) Au2-P2-O5 115.37(1) Ag2-O10 2.362(2) P2-Ag2-O15 121.94(5) Ag2-N5 2.279(2) Ag2-Ag1-P1 88.38(2)
1.589(3) Au2-P2-O7 113.79(1) Ag2-O13 2.457(2) Ag1-P1-N
1.593(3) Ag2-O15 2.305(2) Ag2-P2-N
117.23(7) P1-O3
121.70(7) P1-O1
P2-O5
1.602(2) Ag1-Ag2-P2 89.94(2)
1.605(2) Ag1-P1-O1 110.26(7)
1.608(2) Ag1-P1-O3 119.29(8)
1.605(2) Ag2-P2-O5 111.57(7)
Au1-Au2 3.108(1)
P1-O1
P1-O3
P2-O5
P2-O7
1.614(2)
1.604(2)
1.622(2)
1.606(2)
P2-O7
Ag1-Ag2 2.986(5) Ag2-P2-O7 120.13(8)
Ag1-P1-N1 120.65(8)
Ag2-P2-N1 119.29(8)
Table 6. Selected Bond Distances and Bond Angles for Complex 14
bond distance (Å) bond angle (deg)
P1-N1-P2
molecule. As it is, these generate intramolecular contacts
O14 · · · H14a ) 2.63 Å, O14 · · · H21b ) 2.38 Å, and
O11· · ·H28a ) 2.56 Å. Considerably shorter contacts would
be generated were the triflates in the gauche or trans
positions. Also, in the present conformation there is a nice
C-H · · · O hydrogen bond of 2.58 Å between O11 and the
C7-H7a unit in the molecule at 1/2 + x, 1/2 - y, -z with an
O · · · H-C angle of 155°.
The structure of 12 is similar to the structure of 5.
However, the Ag1-P1-N1-P2-Ag2 frame is almost
planar, and the bipyridyl rings are parallel to each other
although they are inclined at an angle of approximately 66°
to the above mentioned plane. At approximately 3.9 Å apart
there can be no significant π-π interaction. There are two
moderately strong C-H · · · O hydrogen bonds to the per-
chlorate ions: C32-H32 · · · O16 (H32 · · · O16 ) 2.39 Å;
C32-H32 · · · O16 angle ) 148°) and C26-H26 · · ·O11
(H26 · · · O11 ) 2.47 Å; C26-H26 · · · O11 ) 170°). The
patterns of bond lengths and bond angles in 12 are similar
to those observed in complex 6.
P1-N1
P2-N1
1.675(3)
1.683(3)
2.343(1)
2.368(1)
2.256(3)
2.311(3)
2.648(3)
2.553(2)
2.528(2)
2.375(2)
3.189(1)
120.14(2)
138.07(7)
116.70(7)
118.02(6)
134.04(6)
131.41(6)
125.19(6)
123.19(1)
121.84(1)
77.77(7)
P1-Ag1-N2
P2-Ag2-N3
P1-Ag1-O9
P1-Ag1-O10
P2-Ag2-O10
P2-Ag2-O13
Ag1-P1-N1
Ag2-P2-N1
Ag1-O10-Ag2
Ag1-P1
Ag2-P2
Ag1-N2
Ag2-N3
Ag1-O9
Ag1-O10
Ag2-O10
Ag2-O13
Ag1-Ag2
Table 7. Optimized Geometrical Parameters (Bond Lengths (Å) and
Bond Angles (deg)) for 2, 4, 5, and 12
compound
r(NP)
r(PM)
r(MM)
∠PNP
∠MPN
2
RHF
CC2
RHF
CC2
RHF
CC2
RHF
CC2
1.690
1.702
1.681
1.687
1.681
1.687
1.686
1.689
2.285
2.180
2.406
2.299
2.450
2.201
2.607
2.283
4.157
2.992
3.174
2.858
4.683
2.940
5.084
3.002
126.6
120.6
131.5
127.9
129.9
123.2
128.9
124.2
116.9
112.2
115.6
113.8
121.1
113.6
125.7
115.2
4
5
12
The molecular structure of 14 consist of repeating [(µ-
PNP)Ag2(µ-ClO4)(ClO4)] and pyrazine units arranged in an
alternating up–down fashion to form a 1D zigzag coordina-
tion polymer. The coordination geometry around the silver
atom is tetrahedral and consists of one nitrogen atom of the
pyrazine, one phosphorus atom of 1, and two oxygen atoms
of perchlorate ions. One of the perchlorate ions coordinates
(2.348(1) Å and 2.354(1) Å), and the P1-N-P2 bond angle
(121.01(11)°) is smaller than that observed in complex 4
(126.59(17)°). The cis arrangement of the triflates seems to
be governed by intramolecular contacts. The o-methoxyphe-
noxy groups on P2 are oriented by minimization of contacts
with the THF molecule on the same metal such that their
methoxy groups are directed toward the center of the
2772 Inorganic Chemistry, Vol. 47, No. 7, 2008

AuI and AgI Complexes and AgI Coordination Polymers
in a monodentate fashion to Ag2 while the other forms a
nearly symmetrical µ-oxo bridge between the two metals as
well as forming an unsymmetrical chelate with Ag1. The
complex has two different Ag-P bonds with bond distances
of 2.343(1) Å and 2.368(1) Å although it is not immediately
obvious what is the cause. The Ag1 · · · Ag2 distance is
3.189(1) Å, longer than that observed in complexes 9 and
12, while the Ag1-N2 and Ag2-N3 bond distances are
2.256(3) Å and 2.311(3) Å, respectively, and the P1-N1-P2
bond angle is 120.14(2).
it existsscannot be of the metallophilic type. If, on the other
hand, two vastly different interaction distances, one long (HF)
and one short (CC), are predicted, the calculations give a
good indication of the existence of metallophilic interactions.
This method also allows one to estimate the strength of a
metallophilic attraction via the difference between the
coupled cluster energies of a system at Hartree–Fock and
coupled cluster optimized geometries, respectively, divided
by the number of metal-metal interactions present.
The nature of metal-metal interactions in compounds 2,
4, 5, and 12 was analyzed theoretically by performing HF
and CC calculations. Because correlated ab initio calculations
would become extremely time-consuming using a realistic
substitution pattern, model structures in which phenyl/
methoxyphenyl groups and bipyridine ligands were replaced
with hydrogen atoms and diazabutadiene ligands, respec-
tively, were used; in the case of ionic compounds 4, 5, and
12 only the structure of the cation was modeled. The
predicted metal-metal bond distances as well as other key
geometrical parameters are given in Table 7. As expected,
the inclusion of electron correlation leads to a significant
decrease in phosphorus-metal bond length especially in
cations 5 and 12. The restricted Hartree–Fock method
predicts a fully repulsive potential in 2, 5, and 12 as
metal-metal interaction distances significantly greater than
the sum of van der Waals radii are obtained; the Au(I)-Au(I)
interaction in the structure 4 is also repulsive though the
coordination by two PNP ligands significantly restricts the
possible elongation of the metal-metal distance. Conversely,
optimization of the systems using the coupled cluster ansatz
reveals metallophilic attraction in each case and yields bond
parameters in good agreement with the experimental data.
The strength of the metallophilic attraction in systems 2,
4, 5, and 12 can be estimated by calculating the energy
difference between the Hartree–Fock and coupled cluster
optimized structures at the CC2 level of theory. It should be
noted, however, that this procedure gives only a rough
(upper) estimate of the true interaction energy. The calculated
bond energy is around 45 kJ mol-1 for systems 2 and 4 and
close to 100 kJ mol-1 for the dications in structures 5 and
12. For the former two species the energy difference is within
the typical range (i.e., the energy of a strong hydrogen bond),
but the latter two species appear at first sight to be extremely
strongly bonded by the metallophilic interaction. However,
the calculated interaction energies for 5 and 12 are skewed
by intramolecular interactions between the two planar
diazabutadiene ligands and significant changes in key geo-
metrical parameters other than the metal-metal distance (see
Table 7). Nevertheless, the computational analysis indicates
that even in these cases the short Ag(I)-Ag(I) and
Au(I)-Au(I) distances are due to metallophilic interaction
whose effects to the two structures are clearly seen when
electron correlation effects are appropriately treated in
calculations.
Theoretical Calculations
Metallophilic attractions such as the argentophilic and
aurophilic interactions originate primarily from attractive
dispersion forces which overcome the Pauli repulsion
between two closed d10 shells.5c These interactions are rather
difficult to quantify computationally as the use of correlated
ab initio methods is a prerequisite for theoretical calculations
probing metallophilicity. It is generally recognized that the
description given by the second order Møllet-Plesset
perturbation theory (MP2) somewhat exaggerates the attrac-
tive forces,5b which, thus, necessitates the use of coupled
cluster based approaches to obtain accurate energetics.
Although all density functional theory (DFT) based ap-
proaches include treatment of electron correlation effects
directly built-in to the exchange-correlation functional, they are
not suitable for modeling metallophilic interactions because of
the fact that most of the modern functionals cannot describe
long-range, nonlocal correlation effects dominated by the
fluctuating r-6 dipole term.5c,23a In systems involving heavier
elements such as gold, the attractive forces are greatly enhanced
by relativistic effects which also need to be taken into account
in any theoretical description of metallophilicity.5c,23b In practi-
cal calculations, this is usually accomplished indirectly by
employing relativistically parametrized ECP basis sets for such
atoms.
Because the Hartree–Fock (HF) method lacks treatment
of dynamic electron correlation, it is unable to account for
dispersion-type attractive terms, and the approach unavoid-
ably predicts a repulsive behavior between two metallophilic
fragments. Thus, one way to investigate the nature of short-
range metal-metal interactions observed experimentally is
to compare the results of theoretical calculations carried out
at both HF and, for example, coupled cluster (CC) level of
theory.24 Simply put, if the geometrical parameters predicted
by the two methods agree with each other as well as with
the experimental data, the observed attractive interactionsif
(21) Effendy; Di Nicola, C.; Nitiatmodjo, M.; Pettinari, C.; Skelton, B. W.;
White, A. H. Inorg. Chim. Acta 2005, 358, 735–747.
(22) (a) Effendy; Hanna, J. V.; Marchetti, F.; Martini, D.; Pettinari, C.;
Pettinari, R.; Skelton, B. W.; White, A. H. Inorg. Chim. Acta 2004,
357, 1523–1537. (b) Steiner, T. Cryst. ReV. 1996, 6, 1–57. (c)
Brammer, L.; Bruton, E. A.; Sherwood, P. Cryst. Growth Des. 2001,
1, 277–290.
(23) (a) Pyykkö, P. Angew. Chem., Int. Ed. 2002, 41, 3573–3578. (b)
Pyykkö, P.; Runeberg, N.; Mendizabal, F. Chem. Eur. J. 1997, 3,
1451–1457.
Conclusion
(24) (a) Mendizabal, F.; Pyykkö, P.; Runeberg, N. Chem. Phys. Lett. 2003,
370, 733–740. (b) Avramopoulos, A.; Papadopoulos, M. G.; Sadlej,
A. J. Chem. Phys. Lett. 2003, 370, 765–769.
We have reported the first examples of several bi-, tetra-,
and hexanuclear mixed ligand AuI and AgI complexes
Inorganic Chemistry, Vol. 47, No. 7, 2008 2773

Ganesamoorthy et al.
OTf and ClO4), pyrazine, 1,3,5-triazine, 2,2′-bipyridine, and 4,4′-
bipyridine were purchased from Aldrich chemicals and used as such
without further purification (Caution! Perchlorate salts of metal
complexes with organic ligands are potentially explosiVe. A small
amount was used in all the reactions and handled with great
caution. All perchlorate compounds were tested and found to be
resistant to shock). Other chemicals were obtained from commercial
sources and purified prior to use.
Instrumentation. The 1H and 31P{1H} NMR (δ in ppm) spectra
were recorded using Varian VXR 300 or VXR 400 spectrometer
operating at the appropriate frequencies using TMS and 85% H3PO4
as internal and external references, respectively. The microanalyses
were performed using a Carlo Erba model 1112 elemental analyzer.
The melting points were observed in capillary tubes and are
uncorrected.
including novel coordination polymers of the aminobis(pho-
sphonite) 1 with various bi- and tridentate pyridyl ligands.
Complex 2 readily reacts with rigid bidentate N-donor
ligands like 2,2′-bipyridine, 4,4′-bipyridine, and pyrazine in
the presence of AgClO4 to give either binuclear or tetra-
nuclear macrocycles depending upon the stoichiometry of
the reactants and the reaction conditions. Similar reaction
with 1,3,5-triazine produces a hexanuclear complex 8. The
mono-, bi-, and trisubstituted AgI derivatives, 9-10, have
been prepared by the interaction of 1 with AgX (X ) ClO4
or OTf) in appropriate ratios. The aminobis(phosphonite) 1
reacts with AgClO4 in the presence of 4,4′-bipyridine or
pyrazine to give 1D zigzag coordination polymers. The
presence of metallophilic interactions in compounds 2, 4, 5,
and 12 was analyzed theoretically by performing HF and
CC calculations which was also supported by short
Ag(I)-Ag(I) and Au(I)-Au(I) distances. Coordination com-
plexes containing coplanar 4,4′-bipyridyl groups often show
conducting properties due to the extended conjugation
through metal and 4,4′-bipyridyl units. Unfortunately, in the
solid state, the structure of the AuI complex shows it to
contain noncoplanar or twisted pyridyl groups which prevent
the extension of conjugation. It would be interesting to see
whether, with appropriate solvents or anions, it is possible
to alter the orientation of the pyridyl groups so that they
can switch between coplanar and noncoplanar geometries
so as to induce reversible conducting properties. Work in
this direction is in progress.
Synthesis of [(AuCl)2{µ-PhN(P(OC6H4OMe-o)2)2}] (2). A
solution of 1 (0.059 g, 0.092 mmol) in CH2Cl2 (5 mL) was added
dropwise to a solution of AuCl(SMe2) (0.054 g, 0.184 mmol) also
in CH2Cl2 (5 mL). The reaction mixture was allowed to stir at room
temperature for 4 h. The resulting solution was concentrated to 3
mL followed by the addition of n-hexane to give a white precipitate
of 2. White crystals were obtained upon recrystallization from a
1:1 dichloromethane/n-hexane mixture. Yield: 89% (0.09 g). Mp:
200–202 °C (dec). Anal. Calcd for C34H33Au2Cl2NO8P2: C, 36.78;
1
H, 2.99; N, 1.26. Found: C, 36.79; H, 2.96; N, 1.23%. H NMR
(400 MHz, CDCl3): δ 3.82 (s, OCH3, 12H), 6.82–7.78 (m, Ph, 21H).
31P{1H} NMR (121 MHz, CDCl3): δ 114.3 (s).
Synthesis of [AuCl{PhN(P(OC6H4OMe-o)2)2}] (3). Method
1. A solution of AuCl(SMe2) (0.051 g, 0.174 mmol) in CH2Cl2 (5
mL) was added dropwise to a stirred solution of 1 (0.112 g, 0.174
mmol) also in CH2Cl2 (7 mL). The reaction mixture was allowed
to stir at room temperature for 4 h. The resulting solution was
concentrated to 3 mL followed by the addition of n-hexane to give
a white precipitate of 3. Recrystallization from a 1:1 dichlo-
romethane/n-hexane mixture gave 3 as an analytically pure white
crystalline substance. Yield: 76% (0.116 g).
Experimental Section
General Procedures. All manipulations were performed under
rigorously anaerobic conditions using Schlenk techniques. The
reactions were carried out with minimum exposure to light by
wrapping the reaction vessel with aluminum foil. All the solvents
Method 2. A solution of 1 (0.055 g, 0.085 mmol) in THF (5
mL) was added dropwise to a solution of 2 (0.094 g, 0.085 mmol)
also in THF (8 mL). The reaction mixture was refluxed for 4 h and
then cooled to room temperature. The solution was concentrated
to 3 mL, layered with 3 mL of n-hexane, and kept at -30 °C for
one day to give analytically pure white crystals of 3. Yield: 82%
(0.122 g). Mp: 220–222 °C (dec). Anal. Calcd for C34H33-
AuClNO8P2: C, 46.52; H, 3.79; N, 1.59. Found: C, 46.56; H, 3.70;
N, 1.62%. 1H NMR (400 MHz, CDCl3): δ 3.71 (br s, OCH3, 12H),
6.80–7.65 (m, Ph, 21H). 31P{1H} NMR (162 MHz, CDCl3): δ 133.8
were purified by conventional procedures and distilled prior to use.25
14e
The compounds PhN{P(OC6H4OMe-o)2}2
and AuCl(SMe2)18
were prepared according to the published procedures. AgX (X )
(25) Armarego, W. L. F.; Perrin, D. D. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann: Linacre House, Jordan
Hill, Oxford, U.K., 1996.
(26) (a) Schmidbaur, H.; Wohlleben, A.; Wagner, F.; Orama, O.; Huttner,
G. Chem. Ber. 1977, 110, 1748–1754. (b) Uson, R.; Laguna, A.;
Laguna, M.; Fernandez, E.; Villacampa, M. D.; Jones, P. G.; Sheldrick,
G. M. J. Chem. Soc., Dalton Trans. 1983, 1679–1685. (c) Lin, I. J. B.;
Hwang, J. M.; Feng, D.-F.; Cheng, M. C.; Wang, Y. Inorg. Chem.
1994, 33, 3467–3472. (d) Jones, P. G.; Thone, C. Acta Crystallogr.
1992, C48, 1312–1314. (e) Bachechi, F.; Burini, A.; Galassi, R.;
Pietroni, B. R.; Severini, M. J. Organomet. Chem. 1999, 575, 269–
277.
2
(d, JPP ) 341 Hz), 112.2 (d).
Synthesis of [Au2{µ-PhN(P(OC6H4OMe-o)2)2}2](OTf)2 (4). To
a vigorously stirred mixture of 2 (0.077 mg, 0.070 mmol) and
AgOTf (0.036 g, 0.140 mmol) in CH2Cl2 (7 mL) was added
dropwise a solution of 1 (0.045 g, 0.070 mmol) in the same solvent
(5 mL) at room temperature. The reaction mixture was stirred at
room temperature for 2 h and filtered through celite. The filtrate
was concentrated under vacuum, layered with 1 mL of n-hexane,
and kept at -30 °C to give an analytically pure product of 4 as
white crystals. Yield: 72% (0.100 g). Mp: 196–198 °C (dec). Anal.
(27) (a) Wilton-Ely, J. D. E. T.; Schier, A.; Mitzel, N. W.; Nogai, S.;
Schmidbaur, H. J. Organomet. Chem. 2002, 643(644), 313–323. (b)
Maspero, A.; Kani, I.; Mohamed, A. A.; Omary, M. A.; Staples, R. J.;
Fackler, J. P., Jr Inorg. Chem. 2003, 42, 5311–5319. (c) Bardaji, M.;
Calhorda, M. J.; Costa, P. J.; Jones, P. G.; Laguna, A.; Perez, M. R.;
Villacampa, M. D. Inorg. Chem. 2006, 45, 1059–1068. (d) Lee, Y.-
A.; Eisenberg, R. J. Am. Chem. Soc. 2003, 125, 7778–7779. (e)
Schneider, D.; Schier, A.; Schmidbaur, H. Dalton Trans. 2004, 1995–
2005.
(28) (a) Tzeng, B.-C.; Liao, J.-H.; Lee, G.-H.; Peng, S.-M. Inorg. Chim.
Acta 2004, 357, 1405–1410. (b) Ho, S. Y.; Cheng, E. C.-C.; Tiekink,
E. R. T.; Yam, V. W.-W. Inorg. Chem. 2006, 45, 8165–8174. (c) Jaw,
H.-R. C.; Savas, M. M.; Rogers, R. D.; Mason, W. R. Inorg. Chem.
1989, 28, 1028–1037. (d) Perreault, D.; Drouin, M.; Michel, A.;
Miskowski, V. M.; Schaefer, W. P.; Harvey, P. D. Inorg. Chem. 1992,
31, 695–702. (e) Tang, S. S.; Chang, C.-P.; Lin, I. J. B.; Liou, L.-S.;
Wang, J.-C. Inorg. Chem. 1997, 36, 2294–2300.
(29) (a) Fu, W.-F.; Chan, K.-C.; Cheung, K.-K.; Che, C.-M. Chem. Eur. J.
2001, 7, 4656–4664. (b) Bardaji, M.; Jones, P. G.; Laguna, A.;
Villacampa, M. D.; Villaverde, N. Dalton Trans. 2003, 4529–4536.
(c) Yam, V. W.-W.; Chan, C.-L.; Cheung, K.-K. J. Chem. Soc., Dalton
Trans. 1996, 4019–4022. (d) Field, J. S.; Grieve, J.; Haines, R. J.;
May, N.; Zulu, M. M. Polyhedron 1998, 17, 3021–3029. (e) Yip, S.-
K.; Lam, W. H.; Zhu, N.; Yam, V. W.-W. Inorg. Chim. Acta 2006,
359, 3639–3648.
2774 Inorganic Chemistry, Vol. 47, No. 7, 2008

AuI and AgI Complexes and AgI Coordination Polymers
Calcd for C70H66Au2F6N2O22P4S2: C, 42.39; H, 3.35; N, 1.41; S,
3.23. Found: C, 42.43; H, 3.37; N, 1.44; S, 3.25%. H NMR (400
Synthesis of [Ag2{µ-PhN(P(OC6H4OMe-o)2)2}3](OTf)2 (10).
This was synthesized by a procedure similar to that of 9 using 1
(0.082 g, 0.128 mmol) and AgOTf (0.022 g, 0.085 mmol). Yield:
66% (0.069 g). Mp: 188–190 °C (dec). Anal. Calcd for
1
MHz, CDCl3): δ 3.60 (s, OCH3, 24H), 6.44–7.59 (m, Ph, 42H).
31P{1H}NMR (121 MHz, CDCl3): δ 121.9 (s).
C104H99Ag2F6N3O30P6S2: C, 50.97; H, 4.07; N, 1.72; S, 2.62. Found:
Synthesis of [Au2(C10H8N2)2{µ-PhN{P(OC6H4OMe-o)2}2}]-
(ClO4)2 (5). A mixture of 2 (0.099 g, 0.089 mmol) and AgClO4
(0.040 g, 0.178 mmol) in CH2Cl2 (7 mL) was allowed to stir at
room temperature for 2 h. The suspension was filtered through celite
into a solution of 2,2′-bipyridine (0.028 g, 0.178 mmol) in the same
solvent (2 mL) at room temperature. The resulting reaction mixture
was allowed to stir for a further 2 h. The filtrate was concentrated
under vacuum, layered with 1 mL of n-hexane, and kept at -30
°C to give an analytically pure product of 5 as white crystals. Yield:
81% (0.111 g). Mp: 176–178 °C (dec). Anal. Calcd for C54H49-
Au2Cl2N5O16P2: C, 41.82; H, 3.18; N, 4.52. Found: C, 41.80; H,
C, 50.92; H, 4.04; N, 1.69; S, 2.57%. 1H NMR (400 MHz, CDCl3):
δ 3.56 (s, OCH3, 36H), 6.78–7.52 (m, Ph, 63H). 31P{1H} NMR
(162 MHz, CDCl3): δ 120.8 (br s).
Synthesis of [Ag2(C4H8O)2{µ-PhN(P(OC6H4OMe-o)2)2}2]-
(ClO4)2 (11). A solution of 1 (0.057 g, 0.089 mmol) in THF (5
mL) was added dropwise to a suspension of AgClO4 (0.040 g, 0.178
mmol) also in THF (5 mL) with constant stirring. The stirring was
continued for 2 h at room temperature, and again a solution of 1
(0.057 g, 0.089 mmol) in THF (5 mL) was added dropwise; the
mixture was stirred for a further period of 2 h. The resulting solution
was concentrated to 5 mL and stored at room temperature for 24 h
to give analytically pure white crystals of 11. Yield: 89% (0.146
g). Mp: 122–124 °C (dec). Anal. Calcd for C76H82Ag2Cl2N2O26P4:
C, 49.34; H, 4.47; N, 1.51. Found: C, 49.30; H, 4.43; N, 1.49%.
1H NMR (400 MHz, CDCl3): δ 1.84 (t, CH2, 8H), 3.74 (t, OCH2,
8H), 3.43 (s, OCH3, 24H), 6.76–7.55 (m, Ph, 42H). 31P{1H} NMR
(162 MHz, CDCl3): δ 109.2 (m, |1JAgP| ) 770 Hz).
1
3.18; N, 4.56%. H NMR (400 MHz, CDCl3): δ 3.88 (s, OCH3,
12H), 6.86–8.37 (m, Ph, 37H). 31P{1H} NMR (162 MHz, CDCl3):
δ 112.0 (s).
Synthesis of [Au4(C4H4N2)2{µ-PhN{P(OC6H4OMe-o)2}2}2]-
(ClO4)4 (6). This was synthesized by a procedure similar to that of
5 using 2 (0.185 g, 0.166 mmol), AgClO4 (0.075 g, 0.333 mmol)
and pyrazine (0.013 g, 0.166 mmol). An analytically pure white
crystalline product of 6 was obtained by keeping the saturated
CH2Cl2/THF (1:1 mixture) solution of 6 at room temperature for
several days. Yield: 64% (0.140 g). Mp: 109–110 °C (dec). Anal.
Calcd for C76H74Au4Cl4N6O32P4: C, 34.62; H, 2.83; N, 3.19. Found:
C, 34.58; H, 2.80; N, 3.15%. 1H NMR (400 MHz, CDCl3): δ 3.92
(s, OCH3, 24H), 6.66–8.70 (m, Ph, 50H). 31P{1H} NMR (162 MHz,
CDCl3): δ 117.0 (br s).
Synthesis of [Ag2(C10H8N2)2{µ-PhN(P(OC6H4OMe-o)2)2}](ClO4)2
(12). A solution of 1 (0.099 g, 0.153 mmol) in CH2Cl2 (6 mL) was
added dropwise to a suspension of AgClO4 (0.069 g, 0.306 mmol)
also in CH2Cl2 (8 mL) with constant stirring. The reaction mixture
was stirred for 2 h, and then a solution of 2,2′-bipyridine (0.048 g,
0.306 mmol) in CH
2Cl2 (3 mL) was added dropwise. The resulting
solution was concentrated to 4 mL, layered with 2 mL of n-hexane,
and stored at -30 °C for 3 days to give white crystals of 12. Yield:
82% (0.172 g). Mp: 150–152 °C (dec). Anal. Calcd for
C54H49Ag2Cl2N5O16P2: C, 47.25; H, 3.60; N, 5.10. Found: C, 47.20;
H, 3.63; N, 5.15%. 1H NMR (400 MHz, CDCl3): δ 3.73 (s, OCH3,
12H), 6.64–8.00 (m, Ph, 37H). 31P{1H} NMR (162 MHz, CDCl3):
Synthesis of [Au4(C10H8N2)2{µ-PhN{P(OC6H4OMe-o)2}2}2]-
(ClO4)4 (7). This was synthesized by a procedure similar to that of
5 using 2 (0.084 g, 0.075 mmol), AgClO4 (0.034 g, 0.151 mmol),
and 4,4′-bipyridine (0.012 g, 0.075 mmol). Analytically pure white
crystals of 7 were obtained by keeping the saturated CH2Cl2/n-
hexane (2:1 mixture) solution of 7 at room temperature for 1 day.
Yield: 70% (0.073 g). Mp: 156–158 °C (dec). Anal. Calcd for
C88H82Au4Cl4N6O32P4: C, 37.89; H, 2.96; N, 3.01. Found: C, 37.80;
H, 2.90; N, 3.06%. 1H NMR (400 MHz, CDCl3): δ 3.85 (s, OCH3,
24H), 6.79–8.52 (m, Ph, 58H). 31P{1H} NMR (162 MHz, CDCl3):
δ 110.5 (s).
2
δ 119.8 (m, |1JAgP| ) 930 Hz, JPP ) 67 Hz).
Synthesisof[Ag2(C10H8N2)(µ-ClO4)(ClO4){µ-PhN(P(OC6H4OMe-
o)2)2}]n (13). A solution of 4,4′-bipyridine (0.011 g, 0.070 mmol)
in CH2Cl2 (3 mL) was added dropwise to a mixture of 1 (0.045 g,
0.070 mmol) and AgClO4 (0.029 g, 0.140 mmol) also in CH2Cl2
(5 mL) with constant stirring. The resulting white cloudy precipitate
was collected by filtration and washed with diethyl ether twice (5
mL each). Yield: 94% (0.080 g). Mp: 186–188 °C (dec). Anal.
Calcd for C44H41Ag2Cl2N3P2O16: C, 43.44; H, 3.40; N, 3.45. Found:
C, 43.48; H, 3.43; N, 3.50%.
Synthesis of [Au6(C3H3N3)2{µ-PhN{P(OC6H4OMe-o)2}2}3]-
(ClO4)6 (8). This was synthesized by a procedure similar to that of
5 using 2 (0.076 g, 0.069 mmol), AgClO4 (0.031 g, 0.138 mmol),
and 1,3,5-triazine (0.004 g, 0.046 mmol). Yield: 48% (0.043 g).
Mp: 128–130 °C (dec). Anal. Calcd for C108H105Au6Cl6N9O48P6:
C, 33.45; H, 2.73; N, 3.25. Found: C, 33.50; H, 2.79; N, 3.30%.
1H NMR (400 MHz, CDCl3): δ 3.76 (s, OCH3, 36H), 6.42–8.80
(m, Ph, 69H). 31P{1H} NMR (162 MHz, CDCl3): δ 111.4 (s).
Synthesis of [Ag2(µ-OTf)2{µ-PhN(P(OC6H4OMe-o)2)2}] (9). A
solution of 1 (0.068 g, 0.105 mmol) in CH2Cl2 (5 mL) was added
dropwise to a suspension of AgOTf (0.054 g, 0.210 mmol) also in
CH2Cl2 (7 mL) with constant stirring. The reaction mixture was
allowed to stir at room temperature for 4 h. The resulting solution
was concentrated to 4 mL, layered with 2 mL of n-hexane and
stored at -30 °C for 1 day to afford a white crystalline product.
The crystals suitable for X-ray diffraction analysis were grown by
keeping the saturated THF solution of 9 at room temperature for
several days. Yield: 89% (0.108 g). Mp: 174–176 °C (dec). Anal.
Calcd for C36H33Ag2F6NO14P2S2: C, 37.29; H, 2.87; N, 1.21; S,
Synthesisof[Ag2(C4H4N2)(µ-ClO4)(ClO4){µ-PhN(P(OC6H4OMe-
o)2)2}]n (14). 14 was synthesized by a procedure similar to that of
12 using 1 (0.065 g, 0.101 mmol), AgClO4 (0.046 g, 0.202 mmol),
and pyrazine (0.008 g, 0.101 mmol). Yield: 79% (0.091 g). Mp:
168–170 °C (dec). Anal. Calcd for C38H37Ag2Cl2N3O16P2: C, 40.02;
1
H, 3.27; N, 3.68. Found: C, 40.07; H, 3.24; N, 3.69%. H NMR
(400 MHz, DMSO-d6): δ 3.74 (s, OCH3, 12H), 6.72–8.47 (m, Ph,
25H). 31P{1H} NMR (162 MHz, DMSO-d6): δ 123.5 (br s).
Computational Details. The molecular structures of model
systems of compounds 2, 4, 5, and 12 in which phenyl/methoxy-
phenyl groups and bipyridine ligands were replaced with hydrogen
atoms and diazabutadiene, respectively, were fully optimized at both
RHF and RI-CC2 levels of theory.30 Triple-ꢁ quality basis sets
augmented with two polarization functions (def2-TZVPP) were used
for all lighter atoms; for gold and silver nuclei, quasi-relativistic
1
5.53. Found: C, 37.23; H, 2.85; N, 1.20; S, 5.50%. H NMR (400
MHz, CDCl3): δ 3.88 (s, OCH3, 12H), 6.42–7.70 (m, Ph, 21H).
(30) For a description of the RI-CC2 method, see: Hattig, C.; Weigend, F.
31P{1H} NMR (162 MHz, CDCl3): δ 116.7 (m, |1JAgP| ) 1026 Hz).
J. Chem. Phys. 2000, 113, 5154–5161.
Inorganic Chemistry, Vol. 47, No. 7, 2008 2775

Ganesamoorthy et al.
ECP basis sets of equal valence quality were employed.31 All
calculations were performed with the Turbomole 5.9.1 program
package32 using appropriate point group symmetries and MPI-
parallelism.
were solved by direct methods (for 5, 7, 9, 12, and 14), or the
positions of the heavy atoms were obtained from a sharpened
Patterson function (for 2 and 4). All structures were refined by full-
matrix least-squares procedures using the SHELXTL program
package.36 Hydrogen atoms were placed in calculated positions and
included as riding contributions with isotropic displacement pa-
rameters tied to those of the attached nonhydrogen atoms.
X-ray Crystallography. A crystal of each of the compounds 2,
4, 5, 7, 9, 12, and 14 suitable for X-ray crystal analysis was mounted
in a Cryoloop with a drop of Paratone oil and placed in the cold
nitrogen stream of the Kryoflex attachment of the Bruker APEX
CCD diffractometer. Full spheres of data were collected using 606
scans in ω (0.3° per scan) at ω ) 0, 120, and 240° (for 2 and 4)
or a combination of three sets of 400 scans in ω (0.5° per scan) at
ꢂ ) 0, 90, and 180° plus two sets of 800 scans in ꢂ (0.45° per
scan) at ω ) -30 and 210° (for 5, 7, 9 12, and 14) under the
control of the SMART software package33a (for 2, 4, 7, 9, and 12)
or the APEX2 program suite33b (for 5 and 14). The raw data were
reduced to F2 values using the SAINT+ software,34 and global
refinements of unit cell parameters using 6680–9939 reflections
chosen from the full data sets were performed. Multiple measure-
ments of equivalent reflections provided the basis for empirical
absorption corrections as well as corrections for any crystal
deterioration during the data collection (SADABS35). The structures
Acknowledgment. We are grateful to the Department of
Science and Technology (DST), New Delhi, for funding.
C.G. thanks CSIR, New Delhi, for a Senior Research
Fellowship (SRF). We also thank SAIF, Mumbai, and
Department of Chemistry Instrumentation Facilities, Bombay,
for spectral and analytical data, and J.T.M. thanks the
Louisiana Board of Regents through Grant LEQSF(2002-
03)-ENH-TR-67 for purchase of the CCD diffractometer and
the Chemistry Department of Tulane University for support
of the X-ray laboratory.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of 2, 4, 5, 7, 9, 12,
and 14. This material is available free of charge via the Internet at
http://pubs.acs.org.
(31) All basis sets were taken from the Turbomole 5.9.1 internal basis set
library. For explicit basis set listings, see: ftp://ftp.chemie.uni-
karlsruhe.de/pub/basen/ or Weigend, F.; Ahlrichs, R. Phys. Chem.
Chem. Phys. 2005, 7, 3297–3305.
(32) Ahlrichs, R.; Bär, M.; Häser, M.; Horn, H.; Kölmel, C. Chem. Phys.
Lett. 1989, 162, 165–169.
IC702133F
(34) SAINT+, versions 6.35A and 7.34A; Bruker-AXS: Madison, WI, 2002,
2006.
(36) (a) SHELXTL, version 6.10; Bruker-AXS: Madison, WI, 2000. (b)
Sheldrick, G. M. SHELXS97 and SHELXL97; University of Göttingen:
Göttingen, Germany, 1997.
(35) Sheldrick, G. M. SADABS,version 2.05 and version 2007/2; University
of Göttingen: Göttingen, Germany, 2002, 2007.
2776 Inorganic Chemistry, Vol. 47, No. 7, 2008