Coordination polymers and supramolecular structures in Ag(I)triflate-dppf systems (dppf=1,1′-bis(diphenylphosphino) ferrocene)

Article abstract of DOI:10.1016/j.jorganchem.2004.02.022

The interaction of silver triflate (OTf^-=SO₃ (CF₃)^-) and dppf [(C₅H₄ PPh₂)₂Fe)] gave different complexes, depending on the stoichiometric proportions and reaction conditions. Under limiting dppf conditions, three different forms (1-3) of [Ag₂(OTf)₂(dppf)]_x were isolated. Single crystal X-ray diffraction analyses showed that the structure of 1 (x=2n) consists of a 2-D polymer comprising a tetra-silver basic unit, while that of 2 (x=2) possesses a discrete tetra-silver framework and that of 3 (x=n) is a linear polymer based on a di-silver repeating unit. The structures are supported by bridging dppf ligands and triflate groups. The crystal lattices of the compounds are stabilized by extensive intermolecular C-H?X hydrogen bonding (H=ring proton of Cp or Ph of dpppf; X=O or F of OTf). [Ag(dppf)(OTf)] (4) and the structurally characterized mononuclear [Ag(dppf)₂](OTf) (5) were the sole products obtained from treatment of AgOTf with dppf in molar ratios of 1:1 and 1:2, respectively.

Full text of DOI:10.1016/j.jorganchem.2004.02.022

Journal of Organometallic Chemistry 689 (2004) 1746–1756
www.elsevier.com/locate/jorganchem
Coordination polymers and supramolecular
structures in Ag(I)triflate–dppf
systems (dppf ¼ 1,10-bis(diphenylphosphino)ferrocene) q
*
*
Xiu Lian Lu, Weng Kee Leong, T.S. Andy Hor , Lai Yoong Goh
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
Received 16 December 2003; accepted 23 February 2004
Abstract
The interaction of silver triflate (OTfꢀ ¼ SO3(CF3)ꢀ) and dppf [(C5H4PPh2)2Fe)] gave different complexes, depending on the
stoichiometric proportions and reaction conditions. Under limiting dppf conditions, three different forms (1–3) of
[Ag2(OTf)2(dppf)]x were isolated. Single crystal X-ray diffraction analyses showed that the structure of 1 (x ¼ 2n) consists of a 2-D
polymer comprising a tetra-silver basic unit, while that of 2 (x ¼ 2) possesses a discrete tetra-silver framework and that of 3 (x ¼ n) is
a linear polymer based on a di-silver repeating unit. The structures are supported by bridging dppf ligands and triflate groups. The
crystal lattices of the compounds are stabilized by extensive intermolecular C–Hꢁ ꢁ ꢁX hydrogen bonding (H ¼ ring proton of Cp or
Ph of dppf; X ¼ O or F of OTf). [Ag(dppf)(OTf)] (4) and the structurally characterized mononuclear [Ag(dppf)2](OTf) (5) were the
sole products obtained from treatment of AgOTf with dppf in molar ratios of 1:1 and 1:2, respectively.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Coordination polymers; Supramolecular structures; Hydrogen-bonding; dppf ꢂ 1,10-bis(diphenylphosphino)ferrocene; Silver triflate
1. Introduction
chemistry [5–7], have rarely featured in supramolecular
assemblies, until very recently when a few polymeric and
network assemblies were reported of complexes con-
taining diphosphines with N-donor coligands [8a,8b,8c]
and the bulky tris(2-furyl)phosphine [8d]. Notably
unexplored is the role of metallodiphosphines, e.g. 1,
10-bis(diphenylphosphino)ferrocene (dppf) [6] in supra-
molecular chemistry. It would be of interest to investi-
gate the chemistry of silver complexes containing dppf
with a potentially multidentate coligand like the triflate
anion (OTfꢀ ¼ SO3CF3ꢀ). Recent work by Moore and
coworkers had shown that in association with diphe-
nylacetylenes, OTf has exhibited diverse coordination
modes at silver, varying from monodentate via one ox-
ygen atom forming cyclic dimeric structures or infinite
structures of ‘‘half-bow-tie’’ chains, through bidentate
bridging via two oxygen atoms forming infinite sheet
structures [2i,2j] to l4-bridging via three oxygen atoms
to four Ag atoms forming an infinite undulating sheet
structure [2j]. This paper reports results from the reac-
tion of Ag(OTf) with dppf.
The chemistry of supramolecular network structures,
nanostructures and coordination polymers has attracted
intense interest in recent years. The architecture of these
structures is strongly influenced by the nature of the
mediating metal and ligand, reaction stoichiometry, and
counterions, and subtly by lattice solvate, intermolecu-
lar forces such as H-bonding and p–p stacking interac-
tions [1,2]. Among the metals, silver and gold are of
particular interest on account of the potential of their
compounds as biologically active agents [3], catalysts [4]
and luminescent materials [5]. The bulk of work on the
supramolecular chemistry of silver utilized N, O or S
donor bridging ligands [1c–1h,2]. Phosphine complexes
of silver though extensively studied in coordination
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.jorganchem.2004.02.022.
* Corresponding authors. Tel.: +65-68742677; fax: +65-67791691.
E-mail addresses: andyhor@nus.edu.sg (T.S. Andy Hor), chmgoh-
ly@nus.edu.sg (L.Y. Goh).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.02.022

X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
1747
2. Results and discussion
not observed in the mass spectra. In the ES–MS of 3, mass
fragments (the highest being [Ag6(OTf)5(dppf)3]þ) indic-
ative of the presence of polymeric species were observed.
In the proton NMR spectra, the a and b protons of
the Cp rings of dppf appear as two singlets in the region
d 4.19–4.72 in d6-acetone, with slight shifts occurring
when the temperature is lowered. At ambient tempera-
ture, the 31P{1H} spectrum of complexes 1–3 each shows
a broad signal (m1=2 200–300 Hz) at ca. d 5–7, which
transforms into a sharp pair of doublets at 243 K and
below, arising from coupling to 107=109Ag, with J values
(710–820 Hz) indicative of coordination of one P atom
per Ag center [9]; this is in agreement with X-ray
structural analyses.
2.1. Reactions of Ag(OTf) with dppf
The reaction of Ag(OTf) and dppf in 3:1 molar
equivalents in CHCl3 for 1.5 h gave a yellow suspension;
separation of the soluble and insoluble components
followed by crystallisation gave the coordination poly-
mers 1 (64%) and 3 (34%), respectively, both possessing
the same stoichiometric [Ag4(OTf)4(dppf)2]. The same
reaction for 20 h again led to the isolation of 3 in
identical yield (34%), together with a tetrameric complex
[Ag4(OTf)4(dppf)2] (2) (62%) from the filtrate. 2 was also
obtained (in 72% yield) from a 15 h reaction using 2
Ag(OTf):1 dppf in MeOH–THF.
Crystallisation of 1 and 3 in CH2Cl2–hexane mixtures
gave diffraction-quality crystals of the solvates,
1 ꢁ 0.5CH2Cl2 and 3 ꢁ 0.5CH2Cl2, respectively. Diffrac-
tion-quality crystals of 2 were obtained as 2 ꢁ CH2Cl2
(2A) and 2 ꢁ 0.25CH2Cl2(2B) by slow evaporation of a
CH2Cl2 solution and from a CH2Cl2–hexane mixture,
respectively.
Using 1 Ag(OTf):1 dppf, the reaction in CH2Cl2–
toluene for 8 h gave in 90% yield a yellow solid (4),
possessing an empirical formula [Ag(dppf)(OTf)], the
structure of which is hitherto unknown.
Using 1 Ag(OTf):2 dppf the reaction in MeOH–THF
for 8 h led to the isolation of [Ag(dppf)2](OTf) (5) as a
yellow solid in 90% yield. Diffraction-quality crystals
were obtained from CH2Cl2.
It is observed that the VT-31P NMR spectral fea-
tures vary significantly with solvent, as shown in Ta-
ble 1 and illustrated in Fig. 1 for the compound 2 in
d6-acetone and in CDCl3. It is significant that the low
temperature doublets are much sharper in CDCl3 and
the broad virtual triplet in CDCl3 at 300 K (d 3.6, 6.4,
9.4, unres., each with m1=2 ca. 300 Hz) is seen in d6-
acetone only as a broad peak d 6.0 (m1=2 200 Hz). The
1
chemical shifts of the H(Cp) and 19F resonances of 2
are also different in the two solvents. The VT features
in the 31P spectra can be rationalized based on inter-
and intra-molecular exchange of 31P with 107Ag and
109Ag, first observed by Dean and coworkers in di-
nuclear Ag complexes containing bridging diphos-
phines [10].
Complexes 4 and 5 exhibit slightly different VT features
in their 31P spectra. At 300 K, both exhibit a broad dou-
blet, which at low temperature (223 K) shows coupling to
107Ag/109Ag. The magnitude of these couplings (4 401/465
Hz, and 5 232/271 Hz) is in agreement with the coordi-
nation of two and four P atoms, respectively, per Ag
center [9], as evident in their chemical formulae and also
confirmed by structural analysis in the case of 5.
3. Spectral characteristics
NMR spectral characteristics of all the complexes are
given in Table 1. IR and MS spectral data are given in
Table S1 in Supplementary Information. Parent ions are
Table 1
NMR spectral dataa
Complex
1H d (Cp) of dppfb
31P{1H}
19F d
300 K
223 K
d (m1=2, Hz),
300 K
d (J107=109 Ag–P, Hz)c,
223 K
300 K
223 K
1
4.41, 4.61
4.43, 4.55
3.87, 4.55
4.22, 4.69
4.25, 4.67
–
5.5 (ca. 300)
6.0 (ca. 200)
5.2 (714, 820)
5.3 (710, 820)
–
)1.9
)1.9
)1.6
)2.3
)2.3
–
2
2d
3.6, 6.4, 9.4 (unres., ca. 260,
300, 260)
5.3 (ca. 200)
3
4
5
4.41, 4.60
4.38, 4.57
4.23, 4.69
5.2 (714, 820)
)2.0 (401, 465)
)3.5 (232, 271)
)2.0
)2.7
)2.5
)2.4
–
–
–
)0.9 (d, br, JAg–P 424 Hz)
)3.5 (d, br, JAg–P 244 Hz)
4.19, 4.33
(each m1=2 30 Hz)
–
a In (CD3)2CO, unless other stated.
b Phenyl protons of all the complexes are observed as a multiplet at d 7.45–7.60.
c Two pairs of doublets arising from coupling to 107Ag and 109Ag.
d In CDCl3.

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X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
Fig. 1. VT-31P{1H} NMR of 2 in (a) (CD3)2CO, (b) CDCl3. (The scale of chemical shifts in (b) is compressed to illustrate more clearly the features of
the multiplet broad peak at 300 K.)
4. Molecular structures and crystal packing
the other two are monodentate, each g1-bound via O to
a silver atom (Ag1A and Ag1B, respectively). These
[Ag4(OTf)4] cluster moieties are bridged by dppf ligands
at all its Ag atoms, forming a two-dimensional coordi-
nation polymeric network, reinforced by C–H(Ph)ꢁ ꢁ ꢁF
and C–H(Cp)ꢁ ꢁ ꢁO hydrogen-bonding, which also plays
a role in the formation of a three-dimensional supra-
molecular structure (Fig. 2(b)). Bond parameters are
given in Table 2. The lack of electron donors under these
dppf-limiting conditions forces the Ag atoms to take up
the 16-e trigonal-planar local geometry.
Complexes 1–3 with the same empirical formula,
possess different structures in terms of coordination and
nuclearity. X-ray diffraction analyses of the CH2Cl2
solvates of these complexes show that 1 and 3 are
polymeric in nature. The structure of 1 comprises a two-
dimensional coordination polymer, a section of which is
illustrated in Fig. 2(a).
Four Ag(OTf) units are aggregated via a planar
Ag2O2 ring ([Ag2AO22AAg2BO22B]), the centroid of
which is an inversion center of symmetry. The two OTf
moieties which support the Ag2O2 ring, each bridges
(g1-O, l2-O) three silver atoms, i.e. (Ag2A, Ag2B,
Ag1A) and (Ag2A, Ag2B, Ag1B), respectively; whereas
Complex 2 crystallizes in two different CH2Cl2 sol-
vates, 2 ꢁ CH2Cl2 (2A) and 2 ꢁ 0.25CH2Cl2 (2B), which are
isostructural with some variations in bond parameters, as
given in Table 3. Similar to [Ag4(OTf)4(PMePh2)4] [7a], 2

X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
1749
Fig. 2. (a) View of a section of the coordination polymer 1. (b) 3-D supramolecular structure of 1. Some H-bonding interactions are shown in dashed
lines.
Table 2
ꢀ
Selected bond lengths (A) and angles (°) for 1
ꢀ
Bond lengths (A)
Ag(1)–O(1)
Ag(1)–P(1)
Ag(2)–P(2)
S(1)–O(11)
S(1)–O(13)
S(2)–O(21)
S(2)–O(23)
2.298(5)
2.3638(4)
2.3359(15)
1.439(6)
1.440(6)
1.441(5)
1.420(5)
Ag(1)–O(2)
Ag(2)–O(22)#1
Ag(2)–O(22)
S(1)–O(12)
S(1)–C(1)
2.333
2.286(4)
2.430(5)
1.412(7)
1.809(8)
1.447(4)
1.814(7)
S(2)–O(22)
S(2)–C(2)
Angles (°)
O(11)–Ag(1)–O(12)
O(21)–Ag(1)–P(1)
O(22)#1–Ag(2)–O(22)
Ag(2)#1–O(22)–Ag(2)
S(2)–O(21)–Ag(1)
97.1(2)
O(11)–Ag(1)–P(1)
134.88(16)
147.83(13)
125.01(11)
124.6(3)
121.51(15)
82.88(16)
97.12(16)
130.6(3)
O(22)#1–Ag(2)–P(2)
P(2)–Ag(2)–O(22)
S(1)–O(11)–Ag(1)
S(2)–O(22)–Ag(2)#1
C(15)#2–Fe(1)–C(15)
C(13)#2–Fe(1)–C(13)
C(21)#2–Fe(2)–C(21)
C(25)#2–Fe(2)–C(25)
121.7(3)
180.000(1)
180.0(4)
C(11)#2–Fe(2)–C(11)
C(12)#2–Fe(1)–C(12)
C(14)#2–Fe(1)–C(14)
C(22)#2–Fe(2)–C(22)
180.0(4)
180.000(1)
180.00(19)
180.0(2)
180.000(2)
180.0(3)
Symmetry transformations used to generate equivalent atoms: #1 ꢀx þ 1; ꢀy þ 1; ꢀz þ 1; #2 ꢀx; ꢀy þ 2; ꢀz; #3 ꢀx þ 2; ꢀy þ 1; ꢀz þ 1.
possesses a discrete tetra-silver entity, but their structures
are significantly different. That of 2 contains a Ag4 rect-
angular make-up, the centroid of which constitutes an
inversion center (Fig. 3(a)). The four Ag atoms are sym-
metrically bridged by two dppf ligands and two single-
anchor (O) triflates on the periphery, and cross-connected
by the remaining two l4-triflates. This bonding mode of
OTf was found in [Ag2(DCPA)(OTf)2] (DCPA ¼ 3,30-
dicyanodiphenylacetylene) [2j]. As seen more clearly in
the line-drawing of 2 in Fig. 3(a), the asymmetric unit
contains five fused metallacycles, consisting of two ‘rings’
of Ag2(dppf)O2S and one each of AgOSOAgOSO,
Ag2O3S and Ag2O2. The high level of denticity of the two
l4-triflates results in 18-e tetrahedral Ag(I) centers. As
expected, there is negligible direct Agꢁ ꢁ ꢁAg interactions in
this tetrahedral d10 system. The connectivity resulting
from two l4-triflates produces a compact structure that is
markedly different from that of [Ag4(OTf)4(PMePh2)4]
[7a], in which pairs of Ag centers are connected by a l-
O,O0-triflate to give a ‘step’ configuration (Fig. 4(a)), re-
lated to the usual ‘chair’ geometry of many tetra-silver
Ag4X4L4 complexes (Fig. 4(b)). These differences are not
related to the phosphines, as evident from similar Ag–P
distances.

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X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
Table 3
ꢀ
Selected bond lengths (A) and angles (°) for 2A and 2B
2A
2B
2A
2B
ꢀ
Bond lengths (A)
Ag(1)–P(1)
Ag(2)–P(2)
Ag(2)–O(2)
Ag(2)–O(4)
S(1)–O(2)
S(2)–O(4)
S(2)–O(6)
2.3593(8)
2.3464(8)
2.539(2)
2.376(2)
1.432(2)
1.458(2)
1.432(3)
2.3524(19)
2.338(2)
2.355(5)
2.416(6)
1.435(6)
1.456(6)
1.399(12)
Ag(1)–O(1)
2.454(2)
2.583(3)
2.383(2)
1.437(2)
1.451(2)
1.431(3)
3.779(1)
4.683(1)
2.456(5)
2.427(5)
2.462(6)
1.437(5)
1.448(6)
1.403(12)
3.846(2)
4.306(2)
Ag(1)–O(3)or O(3)#1
Ag(2)–O(3) or O(3)#1
S(1)–O(1)
S(1)–O(3)#1 or O(3)
S(2)–O(5)
Ag(1)ꢁ ꢁ ꢁAg(2)
Ag(1)ꢁ ꢁ ꢁAg(2A)
Angles (°)
P(1)–Ag(1)–O(1)
P(1)–Ag(1)–O(3) or
P(1)–Ag(1)–O(3)#1
P(2)–Ag(2)–O(4)
135.76(6)
120.65(6)
135.85(13)
126.64(14)
P(1)–Ag(1)–O(4)
P(2)–Ag(2)–O(2)
138.04(6)
119.25(6)
133.43(15)
138.57(14)
134.89(6)
77.61(8)
129.13(15)
82.1(2)
P(2)–Ag(2)–O(3) or
P(2)–Ag(2)–O(3)#1
O(4)–Ag(1)–O(3) or
O(4)–Ag(1)–O(3)#1
O(4)–Ag(2)–O(2)
141.29(7)
75.38(8)
75.73(9)
99.05(8)
131.19(15)
123.15(13)
73.59(19)
86.0(2)
O(4)–Ag(1)–O(1)
O(4)–Ag(2)–O(3) or
O(4)–Ag(2)–O(3)#1
Ag(2)–O(4)–Ag(1)
78.99(8)
72.71(18)
105.9(2)
125.7(3)
105.93(9)
138.29(15)
Ag(2)–O(3)–Ag(1) or
Ag(1)#1–O(3)–Ag(2)#1
Ag(1)–O(1)–S(1)
103.8(2)
125.3(3)
Ag(2)–O(2)–S(1)
O(3)#1, Ag(1)#1, Ag(2)#1 atoms are in 2B.
Fig. 3. (a) Molecular structure and line-drawing of 2A/2B. Thermal ellipsoids are drawn to 50% probability level. (b) Packing diagram of 2A, showing
H-bonding (in dashed lines) between one central Ag4 unit and six surrounding units.

X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
1751
Fig. 4. (a) Line drawing of [Ag(SO3CF3)(PMePh2)]4. (b) Chair configuration of Ag4X4L4 type compounds.
The geometrical flexibility of Ag(I), in an already
highly complex adjustable state with mobile ligands such
as triflate and dppf, makes this an ideal system for su-
pramolecular examination. We find extensive intermo-
lecular C–Hꢁ ꢁ ꢁO and C–Hꢁ ꢁ ꢁF–C hydrogen-bonding in
the crystal lattices of 2A and 2B. The slight difference of a
fractional molecule of CH2Cl2 in their crystal lattices is
accentuated into significantly different crystal packing
patterns, giving two very different supramolecular net-
work structures. In the crystal lattice of 2A, one central
tetrameric unit is linked to six surrounding units via three
types of hydrogen-bonds, involving both Cp and Ph hy-
drogen atoms and both ends (F and O) of a triflate, re-
sulting in a two-dimensional network (Fig. 3(b)). The
structure of 2B consists of a 3-dimensional supramolec-
ular network (Fig. 5(a)) formed by the linking of adjacent
‘crossed’ layers; the prototypes of each layer, consisting of
hydrogen-bonded tetrameric units, are illustrated in Figs.
S5a1 and S5a2, given in SI. Additional hydrogen-bonding
interactions between two ‘crossed’ layers are illustrated in
Fig. S5b. The contrasting features between the assemblies
of 2A and 2B resemble those of the different network
structures of [Ag2(DCPA)(OTf)2] (DCPA ¼ 3,30-dicyan-
odiphenylacetylene) resulted from the use of different re-
crystallizing solvents (benzene and toluene) [2j].
Fig. 5. (a) Packing diagram of 2B, viewed from the b-axis, showing
superimposition of two adjacent layers, individual illustrations of
which are given in Fig.5a1 and Fig.5a2 in SI.
Complex 3 presents a form of polymeric assembly,
fundamentally different from that of 1. Unlike 1 which has
both terminal and bridging triflates, 3 has no terminal
ligands. Keeping the 16-e trigonal-planar basic geometry,
each Ag(I) is inter-connected by two l2-bridging triflates
and bridging dppf. The lack of face-bridging l3-triflates
forces the assembly totake up a more open uni-directional
propagation. The basic unit of this polymeric chain is
easily visualized as an eight-membered [Ag2S2O4] mac-
rocyclic ring, exo-connected by bridging dppf, viz. [–(l-
dppf)Ag(l-OTf)2Ag–] (Fig. 6(a)). This coordination
polymer is further strengthened by an unusually short
(and presumably significant) non-bonding Agꢁ ꢁ ꢁC inter-
ꢀ
action (Ag(1)ꢁ ꢁ ꢁC(213) 2.489(6) A) between the phenyl
ring and metal. This interaction appears to give extra

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X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
Fig. 6. (a) A view and line-drawing of the polymeric chain structure of 3. Thermal ellipsoids are drawn to 50% probability level. (b) 3-D supra-
molecular structure of 3, showing C–H(Ph)ꢁ ꢁ ꢁF(OTf) H-bonds and interactions of F(OTf)with CH2Cl2 shown as disordered molecules in the central
portion of the diagram.
support to the ‘‘unsaturated’’ 16-e trigonal planar Ag(I).
Other selected bond parameters are given in Table 4.
Unlike in 2A/2B, the CH2Cl2 solvate molecule partici-
pates in weak inter-chain and inter-layer interactions with
the Ph rings of dppf ligand (the weak hydrogen bonds
Compound 5 is mononuclear, in which the silver
atom exhibits a distorted tetrahedral coordination
geometry with two chelating dppf ligands. Selected
bond lengths and bond angles are given in Table 5.
The structure of the molecular unit shown in
Fig. 7(a), resembles that of the cation [Ag(dppf)2]
ClO4, for which no secondary interactions were
reported [6c]. However, in complex 5 five types of
hydrogen-bonding interactions, viz. C–H(Ph)ꢁ ꢁ ꢁO,
C–H(CH2Cl2)ꢁ ꢁ ꢁO, C–H(Ph)ꢁ ꢁ ꢁCl, C–H(Ph)ꢁ ꢁ ꢁF and
C–H(CH2Cl2)ꢁ ꢁ ꢁF, connect CH2Cl2, the Ph rings of
dppf and CF3SO3, to form a 2-D supramolecular
network, shown in Fig. 7(b).
The systems discussed above demonstrate the stabil-
ization of supramolecular assemblies via the extensive
occurrence of weak secondary hydrogen-bonding inter-
actions. Though frequently observed in organic and co-
ordination compounds [11], these interactions in
organometallic complexes have only recently been no-
ticed [11f,12]. Here we observe bonding interactions be-
tween the C–H’s of arene or Cp rings to oxygen or fluorine
atoms of the CF3SO3 moiety. Literature examples show
ꢀ
between Cl and H(Ph) being Cl3Sꢁ ꢁ ꢁH(223), 2.61 A, 124°
ꢀ
and Cl3Sꢁ ꢁ ꢁH(224), 2.73 A, 119° (see Table S4). A 3-D
view of the polymer chain, showing H-bonding interac-
tions is given in Fig. S6c in SI). Together with additional
inter-chain H-bonding between the hydrogen atoms of Cp
and Ph rings with coordinated triflate oxygen and fluorine
atoms, we witness a three-dimensional supramolecular
structure (Fig. 6(b)). The role of dppf in this assembly, as
well as in those of 2A/2B, seems to be critical. This is best
illustrated when a bidentate dppf is replaced by two
monodentate phosphines. For example, [Ag4(OTf)4
(PMePh2)4] [7a] adopts a completely different tetrameric,
but discrete, entity in the crystalline state, as discussed
above. Incidentally, the Agꢁ ꢁ ꢁPh interaction (Ag–
ꢀ
C44 ¼ 2.721(3) A) is also apparent in this structure al-
though it is significantly longer, and presumably weaker,
ꢀ
than that (2.489(6) A) in 3.

X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
1753
Table 4
ꢀ
Selected bond lengths (A) and angles (°) in 3
ꢀ
Bond lengths (A)
Ag(1)–P(1)
Ag(1)–O(12)#1
Ag(2)–O(11)
Ag(1)–C(213)
S(1)–O(13)
S(1)–O(11)
S(2)–O(22)
S(2)–O(1)#2
C(1)–F(11)
C(1)–F(13)
C(2)–F(22)
2.3827(14)
2.414(5)
2.303(5)
2.489(6)
1.396(6)
1.436(5)
1.422(5)
1.427(4)
1.292(10)
1.289(9)
1.301(15)
Ag(2)–P(2)
Ag(1)–O(1)
Ag(2)–O(21)
Ag(1)#2–O(12)
S(1)–O(12)
S(1)–C(1)
2.3781(14)
2.528(4)
2.403(4)
2.414(5)
1.421(5)
1.806(8)
1.426(4)
1.796(9)
1.282(10)
1.319(12)
1.278(13)
S(2)–O(21)
S(2)–C(2)
C(1)–F(12)
C(2)–F(21)
C(2)–F(23)
Angles (°)
P(1)–Ag(1)–O(12)#1
O(12)#1–Ag(1)–C(213)
O(12)–Ag(1)–O(1)
O(11)–Ag(2)–P(2)
P(2)–Ag(2)–O(21)
C(211)–P(2)–Ag(2)
104.68(12)
103.37(19)
84.72(18)
139.04(17)
113.61(12)
112.53(1)
P(1)–Ag(1)–C(213)
P(1)–Ag(1)–O(1)
144.06(17)
120.25(13)
84.2(2)
C(213)–Ag(1)–O(1)
O(11)–Ag(2)–O(21)
C(221)–P(2)–Ag(2)
91.90(19)
117.60(17)
Symmetry transformations used to generate equivalent atoms: #1 ꢀx þ 3=2; y þ 1=2; ꢀz þ 1=2; #2 ꢀx þ 3=2; y ꢀ 1=2; ꢀz þ 1=2.
Table 5
Selected bond lengths (A) and bond angles (°) for 5
ꢀ
Ag(1)–P(1)
Ag(1)–P(4)
P(3)–C(16)
2.5604(9)
2.5641(9)
1.800(3)
Ag(1)–P(2)
P(1)–C(1)
P(4)–C(11)
2.6415(9)
1.806(3)
1.819(3)
Ag(1)–P(3)
P(2)–C(6)
P(3)–C(31)
2.6121(10)
1.811(4)
1.821(5)
P(3)–C(32)
P(2)–C(1C)
1.829(5)
1.825(3)
P(1)–C(1A)
P(2)–C(1D)
1.824(3)
1.837(3)
P(1)–C(1B)
P(3)–C(1E)
1.828(3)
1.830(4)
P(3)–C(1F)
S(1)–O(1)
1.836(4)
1.384(4)
P(4)–C(1H)
S(1)–O(3)
1.833(3)
1.371(4)
P(4)–C(1G)
S(1)–O(2)
1.834(4)
1.404(4)
P(1)–Ag(1)–P(2)
P(1)–Ag(1)–P(4)
P(4)–Ag(1)–P(2)
104.91(4)
114.03(3)
106.50(3)
P(1)–Ag(1)–P(3)
P(4)–Ag(1)–P(3)
P(3)–Ag(1)–P(2)
117.99(3)
98.02(3)
115.06(3)
Fig. 7. (a) Molecular structure of 5. Thermal ellipsoids are drawn to 50% probability level. (b) Packing diagram of 5, showing C–Hꢁ ꢁ ꢁO and C–Hꢁ ꢁ ꢁF
H-bonds (in dashed lines) between SO3CF3 and CH2Cl2 and the ring H’s of Cp and Ph of dppf.

1754
X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
bonding of C–X(arene) to O of CO ligand for X ¼ H [11f]
or F [12c] and to F of BFꢀ4 [12b] or PFꢀ6 [12e] for X ¼ H.
from CH2Cl2–hexane after 8 h at )15 °C yielded yellow
diffraction-quality crystals of 1 ꢁ 0.5CH2Cl2.
(ii) 20 h reaction. To a suspension of Ag(OTf) (0.398 g,
1.55 mmol) in CHCl3 (20 ml) was added dppf (0.289 g,
0.52 mmol) and the mixture was stirred for 20 h. The
resultant suspension was filtered to collect a yellow pre-
cipitate of 3 described above (0.189 g, 0.18 mmol, 34%
yield). Concentration of the filtrate to ca. 2 ml, followed
by addition of hexane (3 ml) gave air-stable yellow–
brown crystalline solids of [Ag4(OTf)4(dppf)2](2) (0.341
g, 0.16 mmol, 62% yield). Anal. Calc. for C72H56
F12O12P4S4Ag4Fe2(2)CHCl3: C, 38.8; H, 2.6; S, 5.7.
Found: C, 38.6; H, 2.8; S, 5.6%. Diffraction-quality
crystals of 2 were obtained as 2 ꢁ 0.25CH2Cl2 (2B) from
CH2Cl2–hexane after 1 day at ambient temperature.
5. Conclusion
The coordination flexibility of the ligand(s) and geo-
metric variability of the metal in a seemingly simple
Ag(I)/triflate/diphosphine system has given rise to a
variety of coordination and polymeric complexes. Intra-
molecular interactions have resulted in supramolecular
assemblies which are further influenced by solvent
effects.
6. Experimental
6.2.2. (b) Using 2 Agþ:1 dppf
6.1. General
To a solution of Ag(OTf) (0.103 g, 0.40 mmol) in
MeOH (10 ml) was added dppf (0.111 g, 0.20 mmol) in
THF (10 ml) and the mixture was stirred for 15 h at
room temperature. The resultant orange suspension was
filtered through Celite. Concentration of the orange–red
filtrate to ca. 2 ml, followed by addition of ether (5 ml)
precipitated air-stable yellow solids, which on recrys-
tallization from CH2Cl2–hexane gave [Ag4(SO3CF3)4
(dppf)2] (2) (0.073g, 72% yield). Anal. Calc. for
C72H56F12O12P4S4Ag4Fe2: C, 40.5; H, 2.6; P, 5.8; F,
10.7. Found: C, 40.7; H, 2.6; P, 6.2; F, 9.5%. Diffraction-
quality crystals of 2 ꢁ CH2Cl2 (2A) were obtained from
this sample after 3 days by slow evaporation of a solu-
tion in CH2Cl2 at room temperature.
Ag(OTf) and dppf were used as supplied from Strem
Chemicals. All reactions were performed under dry ni-
trogen using Schlenk techniques. Solvents were freshly
distilled from standard drying agents. NMR spectra were
recorded on a Bruker ACF300 FT NMR spectrometer
(1H at 300.13 MHz; 31P{1H} at 121.50 MHz and 19F at
282.38 MHz), with chemical shifts referenced to residual
non-deutero solvent, external H3PO4 and external
CF3COOH, respectively. Infrared spectra were measured
in KBr pellet in the range of 400–4000 cmꢀ1 on a Perkin
Elmer 1600 FT-IR spectrometer. FAB mass spectra were
obtained on a Finnigan MAT95XL-T spectrometers. All
elemental analyses were carried out in-house.
6.2. Synthetic reactions
6.2.3. (c) Using 1 Agþ:1 dppf in CH2Cl2
To a suspension of Ag(OTf) (0.055 g, 0.21 mmol) in
CH2Cl2 (10 ml) was added dppf (0.119 g, 0.21 mmol)
in toluene (10 ml) and the mixture stirred for 8 h. This
was filtered to give a yellow solution, which on con-
centration to 1 ml followed by addition of hexane
(2 ml), gave yellow solids of [Ag(dppf)(OTf)] (4) (0.153
g, 0.19 mmol, 90%). Anal. Calc. for C35H28F3O3P2SAg
Fe: C, 51.8; H, 3.5; S, 3.9. Found: C, 51.8; H, 3.5; S,
3.8%. The structure has not been solved because of
disorder.
All NMR data are given in Table 1, whereas IR and
mass spectral data are given in Table S1 in Supple-
mentary Information.
6.2.1. (a) Using 3 Agþ:1 dppf
(i) 1.5 h reaction. To a suspension of Ag(OTf) (0.130
g, 0.51 mmol) in CHCl3 (1 ml) was added dppf (0.097 g,
0.18 mmol) and the mixture was stirred for 1.5 h at
ambient temperature. The resultant suspension was fil-
tered to collect a yellow precipitate, which on crystalli-
sation gave [Ag2(OTf)2(dppf)]n (3) (0.064 g, 0.060 mmol,
34% yield). Anal. Calc. for C72H56F12O12P4S4Ag4Fe2
(3) ꢁ CHCl3: C, 38.8; H, 2.6; S, 5.7. Found: C, 38.8; H,
2.6; S, 5.3%. Diffraction-quality crystals of 3 ꢁ 0.5CH2Cl2
were obtained from CH2Cl2–hexane after 1 day at am-
bient temperature.
Concentration of the filtrate to ca. 0.5 ml, followed by
addition of hexane (1 ml) gave air-stable yellow solids of
[Ag2(OTf)2(dppf)]n (1) (0.119 g, 0.11 mmol, 64% yield).
Anal. Calc. for C36H28F6O6P2S2Ag2Fe: C, 40.5; H, 2.6;
S, 6.0. Found: C, 39.9; H, 2.6; S, 6.2%. Recrystallisation
6.2.4. (d) Using 1 Agþ:2 dppf
To a solution of Ag(OTf) (0.055 g, 0.22 mmol) in
MeOH (10 ml) was added a THF solution (10 ml) of dppf
(0.222 g, 0.40 mmol) and the mixture stirred for 8 h. This
was filtered through celite to obtain an orange filtrate,
which was concentrated to ca. 2 ml; addition of ether (5
ml), gave yellow solids of [Ag(dppf)2](OTf) (5) (0.264 g,
90%). Anal. Calc. for C69H56F3O3P4SAgFe2: C, 60.7; H,
4.1; S, 2.4; P, 9.1; F, 4.2. Found: C, 60.6; H, 4.2; S, 2.5; P,
8.3; F, 4.2%.

X.L. Lu et al. / Journal of Organometallic Chemistry 689 (2004) 1746–1756
1755
7. X-ray diffraction analyses
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK (Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or http://www.ccdc.cam.ac.uk).
Crystals were obtained as described above and
mounted on a quartz fibre. X-ray data were collected on a
Bruker SMART APEX diffractometer, equipped with a
CCD detector, using Mo Ka radiation at ambient 223 K.
Data were corrected for Lorentz and polarisation effects
with the SMART suite of programs [13], and for absorp-
tion effects with SADABS [14]. Structural solution and
refinement were carried out with the SHELXTL suite of
programs [15].
Acknowledgements
Support from the National University of Singapore
as Academic Research Fund Grant Nos. R14300077112
and R14300135112 to L.Y.G and a research scholarship
to X.L.L is gratefully. We also thank Prof. Philip A.W.
Dean (University of Western Ontario, Canada) for
helpful discussions, Ms. G.K. Tan, Dr. Koh and Dr.
B.W. Sun for technical assistance.
The structures were solved by direct methods to locate
the heavy atoms, followed by difference maps for the light,
non-hydrogen atoms. The aromatic hydrogens were
placed in calculated positions. All non-hydrogen atoms
were generally given anisotropic displacement parameters
in the final model (but see below). For 1, the CH2Cl2
solvent molecule was modeled as disordered over three
sites, all atoms isotropic, with occupancies of 0.2, 0.2 and
0.1. For 2A, the CH2Cl2 solvent molecule was modeled as
disordered over two sites with occupancies of 0.65 and
0.35. For 2B, there was disorder of one of the triflate
groups. This was modeled as disordered over two sites,
with occupancies summing to unity. The S atoms were
allowed to refine anisotropically; the lighter atoms were
given common isotropic thermal parameters. Appropri-
ate restraints were placed on bond parameters. There was
also a half-molecule of CH2Cl2 solvent which was disor-
dered about a centre of symmetry. This was also modeled
with an isotropic model, with restraints on bond param-
eters. For 3, the half molecule of CH2Cl2 solvent was
modeled as disordered over two sites, with occupancies of
0.4 and 0.1. For 5, a CH2Cl2 solvent molecule was found;
the C–Cl bond lengths were restrained to be the same.
Details of crystal parameters, data collection and struc-
ture refinement are summarized in Table S6 in SI. Bond
parameters of complexes 1, 2A, 2B, 3 and 5, are given in
Tables 2–5 and their respective H-bonding parameters in
Tables S2–S5 in SI.
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