Supramolecular structures in [Ag(dppf)] complexes [dppf = 1,1′-bis(diphenylphosphanyl)ferrocene] stabilized by coordinatively versatile trifluoroacetate (TFA) ligands

Article abstract of DOI:10.1002/ejic.200300684

The interaction of silver(I) trifluoroacetate and dppf in different molar equivalents has led to the isolation of dinuclear complexes [Ag ₂(μ-O₂CCF₃)₂(μ-dppf)] (1) and [Ag₂(η¹-O₂CCF₃) ₂(dppf)₂] (2). Treatment of 1 with excess dppf gave a coordination polymeric compound [Ag(η²-O₂CCF ₃)(dppf)]_n (3). Reaction of 1 with PMe₂Ph in MeOH in the presence of NH₄PF₆ led to displacement of trifluoroacetate, forming the mononuclear compound [Ag(PMe₂Ph) ₂(η²-dppf)]PF₆ (4). All compounds have been characterized by microanalytical and spectroscopic analyses [IR, MS and NMR (¹H, ¹⁹F and ³¹P{¹H})] as well as X-ray diffraction studies. Molecular structures of the solvates of 1, viz. 1A (1·0.5THF) and 1B (1·0.5CH₂Cl₂), 2 and 3 show that they contain trifluoroacetate in bridging, monodentate and bidentate bonding modes, respectively, with dppf as a bridging co-ligand. Compound 3 is an infinite linear [-dppf-Ag-dppf-Ag-dppf-Ag-]_n coordination polymer. Interestingly, 1A and 1B form two different supramolecular network structures through C-H...F and C-H...O hydrogen-bonding interactions. Such secondary bonding interactions also lead to the formation of a 3D supramolecular structure in 3. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200300684

FULL PAPER
Supramolecular Structures in [Ag(dppf)] Complexes
[dppf ؍ 1,1Ј-Bis(diphenylphosphanyl)ferrocene] Stabilized by Coordinatively
Versatile Trifluoroacetate (TFA) Ligands
Xiu Lian Lu,[a] Weng Kee Leong,[a] Lai Yoong Goh,*[a] and Andy T. S. Hor*[a]
Keywords: Silver / Trifluoroacetate / Coordination polymer / Supramolecular chemistry / Hydrogen bonding
The interaction of silver(
I
) trifluoroacetate and dppf in differ-
(1·0.5CH2Cl2), 2 and 3 show that they contain trifluoroacetate
in bridging, monodentate and bidentate bonding modes, re-
spectively, with dppf as a bridging co-ligand. Compound 3 is
an infinite linear [−dppf−Ag−dppf−Ag−dppf−Ag−]n coordina-
ent molar equivalents has led to the isolation of dinuclear
complexes [Ag2(µ-O2CCF3)2(µ-dppf)] (1) and [Ag2(η1-
O2CCF3)2(dppf)2] (2). Treatment of 1 with excess dppf gave
a coordination polymeric compound [Ag(η2-O2CCF3)(dppf)]n tion polymer. Interestingly, 1A and 1B form two different sup-
(3). Reaction of 1 with PMe2Ph in MeOH in the presence of
NH4PF6 led to displacement of trifluoroacetate, forming the
mononuclear compound [Ag(PMe2Ph)2(η2-dppf)]PF6 (4). All
ramolecular network structures through C−H···F and C−H···O
hydrogen-bonding interactions. Such secondary bonding in-
teractions also lead to the formation of a 3D supramolecular
compounds have been characterized by microanalytical and structure in 3.
spectroscopic analyses [IR, MS and NMR (1H, 19F and
31P{1H})] as well as X-ray diffraction studies. Molecular struc-
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
tures of the solvates of 1, viz. 1A (1·0.5THF) and 1B
Germany, 2004)
Introduction
when assisted by intermolecular forces such as H-bonding.
We describe here the results of such a study.
Transition-metal-mediated self-assembly is emerging as a
new and pragmatic strategy for the design of nanostruc-
tures, supramolecular two- or three-dimensional network
structures and coordination polymers.[1] Nitrogen-donor li-
gands have dominated these molecular designs.[1bϪ1d,1f,1h,2]
Among the metals, the use of silver in this line of crystal
Results and Discussion
Synthesis
Treatment of Ag(O2CCF3) with dppf (2:1 molar ratio) in
engineering has escalated in the last decade[2,3] due to its THF/MeOH for 8 h afforded an air-stable, non-light-sensi-
rich structural diversity, which may be further tuned by nu- tive yellow crystalline solid of a THF solvate of the disilver
merous factors such as metal-to-ligand stoichiometry, coun- complex [Ag2(O2CCF3)2(dppf)] (1) in 34% yield. Workup
terions, ligand conformation, intra- and intermolecular H- of the supernatant of 1 in CH2Cl2/ether gave the solvate
bonding and solvents. Surprisingly, phosphanes have rarely 1·0.5CH2Cl2 (30% yield). This solvate was obtained in 90%
been used in such assemblies until very recently, when some yield directly from a 6 h reaction in CH2Cl2. Recrystalliza-
helices, rings, cages and polymers began to emerge in sil- tion of 1 from THF/MeOH gave diffraction-quality crystals
ver() systems containing (2-furyl)phosphane[3a] and some of 1·0.5THF (1A) after 1 d at ambient temperature, while
diphosphanes.[3b,3d] In particular, the role of the metallodi- the same process in CH2Cl2/diethyl ether gave diffraction-
phosphane 1,1Ј-bis(diphenylphosphanyl)ferrocene (dppf) in quality crystals of 1·0.5CH2Cl2 (1B). Treatment of Ag-
supramolecular assemblies has not been investigated. We (O2CCF3) with 1 mol-equiv. of dppf in CH2Cl2 for 3 h at
expect that the variable conformation modes of dppf in room temperature yielded a yellow solid of the dinuclear
combination with coordinatively flexible ligands, such as complex [Ag2(O2CCF3)2(dppf)2] (2) in 87% yield. The reac-
acetate or nitrate as ancillary ligands,[4] will give a multitude tion of 1 with 1 mol-equiv. of dppf in CH2Cl2 for 3.5 h af-
of molecular and crystal structural possibilities with a metal forded orange solids of the polymeric complex [Ag-
like silver, which can adopt variable geometries, especially (O2CCF3)(dppf)]n (3) in 88% yield. These reactions are
shown in Scheme 1. When monitored in an NMR tube in
[a]
CDCl3, the latter reaction showed no evidence of 2 (see
Exp. Sect.); 2 is, though, very stable in CDCl3. Reaction of
1 with PMe2Ph in MeOH in the presence of NH4PF6 led
to displacement of the O2CCF3 ligand and isolation of the
Department of Chemistry, National University of Singapore,
Kent Ridge, Singapore 117543
Fax: (internat.) ϩ 65-6779-1691
E-mail: chmgohly@nus.edu.sg
andyhor@nus.edu.sg
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DOI: 10.1002/ejic.200300684
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Supramolecular Structures in [Ag(dppf)] Complexes
FULL PAPER
mononuclear complex [Ag(dppf)(PMe2Ph)2]PF6 (4) in 48%
yield (Scheme 2).
Scheme 1
Figure 1. Two views of the molecular structure of
[Ag2(O2CCF3)2(dppf)]·0.5THF (1A); hydrogen and fluorine atoms
omitted for clarity
Scheme 2
˚
˚
1B, H···F distances of 2.50Ϫ2.54 A in 1A and 2.37Ϫ2.69 A
in 1B (Table 2). The H···O and C···O distances, and
CϪHϪO angles, fall within the reported ranges, viz.
Structural Studies
˚
˚
2.52Ϫ2.70 A, 3.32Ϫ3.60 A and 128Ϫ155°, respectively,
found in a CpFe half-sandwich and related carbonyl com-
[Ag2(µ-O2CCF3)2(µ-dppf)] (1)
The solvate molecules 1·0.5C4H8O (1A) and 1·0.5CH2Cl2 plexes of first-row transition metals, reported by Desiraju
(1B) are isostructural; two views of the molecular structure and co-workers. Likewise, the H···F distances and CϪHϪF
of 1A are illustrated in Figure 1. The structure consists of angles are found in the range reported for in C6H6ϪxFx
[5]
˚
a dinuclear Ag2 core bridged by two trifluoroacetate groups (x ϭ 1Ϫ5), viz. 2.41 Ϫ2.87 A and 120Ϫ174°, respectively.
and a dppf ligand, similar to the structure of [Ag2(- Packing diagrams of the supramolecular networks in 1A
O2CR)2(dppf)] (R ϭ H, CH3, Ph).[4] The Ag···Ag distances and 1B viewed from the z and x axis, respectively, are illus-
˚
˚
[3.156(2) A in 1A and 3.2434(4) A in 1B] agree with re- trated in Figures 2 and 3. In 1A, there is close packing of
˚
ported non-bond distances of 3.104(1)
A
in [Ag2(- four molecules through two types of hydrogen bonds:
˚
O2CCH3)2(dppf)]
and
3.346(4)
A
in
[Ag2(- CϪH(Ph)···O and CϪH(Cp)···FϪC. The Figure shows four
O2CPh)2(dppf)].[4b] With three bridging ligands and no for- Ag2 units clustering around a ‘‘central’’ region, which is
mal MϪM bond, we can view this as two macrocycles effectively surrounded by four phenyl rings, one from each
hinged at the two AgI centers. A twofold axis passes Ag2 unit; molecules of THF are discernible in the lattice. In
through the mid-point of the Ag(1)···Ag(1A) axis and the 1B, the elementary prototype shows four molecular units
Fe(2) atom of the dppf ligand in 1A. Selected bond param- connected by four types of H-bonds, viz. CϪH(Cp)···O,
eters (Table 1) show that the equivalent bond lengths of 1A CϪH(Ph)···O, CϪH(Cp)···FϪC and CϪH(Ph)···FϪC. Fig-
and 1B are very similar, but their bond angles deviate signif- ure 3 shows the relative orientation of three pairs of Ag2
icantly, viz. the OϪAgϪO, OϪAgϪAg, OϪAgϪP, units; considering the dppf ligand as the ‘‘head’’ end of the
PϪAgϪAg and OϪCϪO angles.
unit and the bridging TFA ligands as the ‘‘tail’’ end, there
The crystal packing of 1A and 1B shows weak CϪH···O is one pair pointing ‘‘head-to-head’’ towards each other
and CϪH···F hydrogen-bonding interactions, resulting in such that their Cp rings come close to the two CH2Cl2 mol-
˚
˚
H···O distances of 2.62Ϫ2.63 A in 1A and 2.48Ϫ2.63 A in ecules in the central portion of the molecule, while the other
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X. L. Lu, W. K. Leong, L. Y. Goh, A. T. S. Hor
FULL PAPER
˚
Table 1. Selected bond lengths [A] and bond angles [°] for solvates of Ag2(O2CCF3)2(dppf) (1); symmetry transformations used to generate
the ‘‘A’’ atoms: x ϩ 0, Ϫy ϩ 1.5, Ϫz ϩ 0.25
˚
Equivalent bond lengths [A] in the two molecules
1A
1B
1A
1B
Ag1ϪP3/Ag1ϪP1
Ag2ϪP2
Ag1ϪO12/Ag1ϪO3
Ag2ϪO4
C11AϪO(12)/C1ϪO2
C11ϪO11/C3ϪO4
2.358(3)
Ϫ
2.407(11)
Ϫ
1.219(15)
1.219(15)
2.3539(8)
2.3459(9)
2.222(3)
2.204(3)
1.221(6)
1.237(5)
Ag1ϪAg1A/Ag1ϪAg2
Ag1ϪO11/Ag1ϪO1
Ag2ϪO2
C11ϪO11/C1ϪO1
C11ϪO12A/C3ϪO3
3.156(2)
2.248(9)
Ϫ
1.219(16)
1.219(15)
3.2434(4)
2.315(3)
2.309(4)
1.209(5)
1.204(5)
Equivalent bond angles [°] in the two molecules
1A
1B
O11ϪAg1ϪO12
O11ϪAg1ϪP3
P3ϪAg1ϪO12
O11ϪAg1ϪAg1A
P3ϪAg1ϪAg1A
O12ϪAg1ϪAg1A
O11ϪC11ϪO12A
O11AϪC11AϪO12
87.6(4)
O4ϪAg2ϪO2
O4ϪAg2ϪP2
P2ϪAg2ϪO2
O4ϪAg2ϪAg1
P2ϪAg2ϪAg1
O2ϪAg2ϪAg1
O4ϪC3ϪO3
O1ϪC1ϪO2
98.99(18)
146.7(3)
124.4(3)
83.2(2)
116.33(8)
65.9(3)
129.9(14)
113.0(10)
138.43(12)
121.11(12)
76.29(9)
123.19(2)
72.86(9)
131.1(4)
129.6(4)
two pairs orientate tail-to-tail towards each other, such that
The different crystal packing encountered in these two
their CF3 groups radiate towards the CH2Cl2 molecules. solvates of 1 must be associated with their different bond
Adjacent molecules are linked into a 2D layer network by parameters, as well as the presence and location of the sol-
H-bonding (CϪH···F and CϪH···O), and these layers are vent molecules in the crystal lattice, factors that influence
linked into a 3D network through interlayer H-bond inter- the nature and strength of hydrogen bonds supporting the
actions.
network.
˚
Table 2. Hydrogen bond lengths [A] and bond angles [°] for 1A and 1B
˚
˚
˚
DϪH
DϪH [A]
A
H···A [A]
DϪA [A]
ЄDHA
Symmetry
1A:
C326ϪH326
C315ϪH315
C2ϪH2
0.94
0.94
0.93
0.93
O11
O12
F11
F13
2.63
2.62
2.54
2.50
3.441(19)
3.399(19)
3.094(24)
3.251(6)
146
141
119
138
1 Ϫ y, x, Ϫz
1 Ϫ y, x, Ϫz
1 Ϫ y, x, Ϫz
1 Ϫ y, x, Ϫz
C2ϪH2
1B:
C4AϪH4A
C3CϪH3C
C13ϪH13
C11ϪH11
C11ϪH11
C12ϪH12
C6CϪH6C
C3DϪH3D
C3BϪH3B
C7ϪH7
0.94
0.94
0.99
0.99
0.99
0.99
0.94
0.94
0.94
0.99
F1
F1
F3
F4
F4A
F5A
F6A
O1
O2
O4
2.61
2.69
2.68
2.48
2.67
2.37
2.64
2.54
2.63
2.48
3.344(6)
3.420(8)
3.250(5)
3.079(7)
3.182(10)
3.071(11)
3.225(15)
3.205(6)
3.403(6)
3.468(6)
136
135
117
119
113
127
121
128
139
178
2 Ϫ x, 1 Ϫ y, 2 Ϫ z
x Ϫ 1, y, z
2 Ϫ x, y Ϫ 0.5, 1.5 Ϫ z
x, 1.5 Ϫ y, Ϫ0.5 ϩ z
x, 1.5 Ϫ y, Ϫ0.5 ϩ z
1 Ϫ x, y Ϫ 0.5, 1.5 Ϫ z
x, 1.5 Ϫ y, Ϫ0.5 ϩ z
x, 1.5 Ϫ y, Ϫ0.5 ϩ z
2 Ϫ x, y Ϫ 0.5, 1.5 Ϫ z
1 Ϫ x, y Ϫ 0.5, 1.5 Ϫ z
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Supramolecular Structures in [Ag(dppf)] Complexes
FULL PAPER
Figure 3. Packing diagram of the supramolecular network in
[Ag2(O2CCF3)2(dppf)]·0.5CH2Cl2 (1B) viewed from the x axis; four
types of H-bonds are illustrated: CϪH(Cp)···O, CϪH(Ph)···O,
CϪH(Cp)···FϪC and CϪH(Ph)···FϪC
Figure 2. Packing diagram of the supramolecular network in 1A
viewed from the z axis, showing CϪH(Ph)···O and CϪH(Cp)
···FϪC hydrogen bonds; the four THF molecules in each layer
are visible
[Ag2(O2CCF3)2(dppf)2] (2)
[Ag2(O2CCF3)2(dppf)2] (2) (Figure 4) contains two three-
coordinate silver atoms doubly bridged by two dppf li-
gands; being η1-coordinated to an oxygen atom of trifluo-
roacetate anions, each Ag atom achieves a 16e configura-
tion. Selected bond parameters of 2 are given in Table 3.
Similar structures have been reported for [Ag2(-
NO3)2(dpm)2] and [Ag2(dpm)2(O2CCH2Ph)2] (dpm
ϭ
Ph2PCH2PPh2) with monodentate nitrate and carboxylate
ligands, respectively,[6a,6b] which possess Ag···Ag distances
Figure 4. Molecular structure of 2; hydrogen atoms omitted for
˚
of 3.085(1) and 3.080(1) A, respectively; however, there is clarity; thermal ellipsoids drawn to 50% probability
˚
no metalϪmetal interaction in 2 (Ag···Ag ϭ 3.781 A), as
[4b]
˚
with Ag2(NO3)2(dppf)2 [Ag···Ag ϭ 3.936(2) A].
The
boxylate group adapts as a bridging or monodentate ligand,
forming an [Ag2(dppf)2] ring structure in the latter situ-
ation, as was found in Ag2(NO3)2(dpm)2 and [Ag2(dpm)2-
(O2CCH2Ph)2].[6a,6b]
AgϪP distances are also very close to those reported for
Ag2(NO3)2(dppf)2.[4b] Except for a H-bond between the
CHCl3 solvent molecule and an oxygen atom of TFA, viz.
˚
C1ϪH1S(CHCl3)···O2 (2.12 A), there are no secondary
bonding interactions of the types observed in 1A, 1B and 3.
The structures of 1 and 2 illustrate a preference of the 16e
AgI center in these dinuclear species for a trigonal-planar
[Ag(O2CCF3)(dppf)]n (3)
The structure of 3 consists of a polymeric chain made up
configuration, with the diphosphane adopting a bridging of repeating units of [ϪPAg(η2-O2CCF3)PϪ]n where
coordination mode, while the weakly coordinating car- PϪP ϭ dppf (Figure 5). Each silver atom is four-coordi-
Eur. J. Inorg. Chem. 2004, 2504Ϫ2513
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X. L. Lu, W. K. Leong, L. Y. Goh, A. T. S. Hor
FULL PAPER
˚
In the above complexes the participation of weak hydro-
gen bonding between CϪH(Cp/Ph) bonds to O and/or
FϪC of coordinated ligands stabilizes supramolecular
structures, the nature of which is further influenced by the
presence of solvent molecules in the crystal lattice, as in 1A
and 1B. The role of such weak hydrogen-bonding interac-
tions in such phenomena has been reported frequently in
recent years in organic systems[5,9] and coordination
compounds[2g,10Ϫ12] though less frequently in organometal-
lic complexes,[12Ϫ15] e.g. in the bonding of CϪH(arene) to
O(carbonyl) in a chromium complex,[12] of CϪH(arene) to
Table 3. Selected bond lengths [A] and bond angles [°] for 2
Ag1ϪO1
Ag1ϪP1
C1ϪO2
2.471(4)
Ag1ϪP2
2.4775(15)
1.239(7)
2.4776(15) C1ϪO1
1.226(7)
O1ϪAg1ϪP2
P2ϪAg1ϪP1
C111ϪP1ϪAg1 114.31(18)
103.23(9)
136.45(5)
O1ϪAg1ϪP1
C11ϪP1ϪAg1
C121ϪP1ϪAg1 110.66(19)
117.42(9)
121.82(18)
C1ϪO1ϪAg1
O2ϪC1ϪC2
119.3(4)
116.3(5)
O2ϪC1ϪO1
O1ϪC1ϪC2
127.0(6)
116.7(5)
Ϫ [13]
Ϫ [16]
F of the anions, BF4
or PF6
and of CϪF of C6F5
nate, being bonded to a chelating trifluoroacetate ligand
and two phosphorus atoms of two different dppf ligands,
thus forming a one-dimensional infinite chain, which is
further reinforced by intra-chain hydrogen-bond interac-
to O(carbonyl) in complexes of Fe, Co, Mn and Re.[15]
[Ag(PMe2Ph)2(dppf)]PF6 (4)
This molecule possesses a mononuclear structure in
which the silver atom assumes a distorted tetrahedral ge-
ometry with coordination to a chelating dppf and two mon-
odentate dimethyl(phenyl)phosphane ligands (Figure 7).
Selected bond parameters are given in Table 6. The bite an-
gle of the dppf ligand, P(1)ϪAg(1)ϪP(2) 105.96(4)°, is simi-
lar to that in [Ag(dppf)2]ClO4 [105.71(4)°]; the other angles
at Ag [P(3)ϪAg(1)ϪP(4) 105.87(5)°, P(3)ϪAg(1)ϪP(1)
113.80(4)°, P(4)ϪAg(1)ϪP(2) 107.58(4)°] show small devi-
ations from those in [Ag(dppf)2]ClO4 [98.39(4)°,
113.15(4)°, 114.54(4)°].[17]
˚
tions [CϪH(Cp)···O 2.47 A, 155°]. A plane of symmetry
passes through the Ag atom and bisects the AgOCO ring.
Notably, the chelating mode of the carboxylate ligand in
AgI complexes is rarely encountered,[7] in contrast to the
commonly reported monodentate and µ-bridging modes.[8]
Selected bond parameters and hydrogen bond parameters
are given in Table 4. The AgϪP distance [Ag(1)ϪP(1)
˚
2.4270(16) A] is intermediate between those encountered in
the other Ag(dppf) complexes in this study (2.34Ϫ2.57 A).
The Ag(1)ϪO(1) bond is longer [2.527(7) A] than those in
1A and 1B (2.21, 2.31 A), in which TFA bridges two Ag
˚
˚
˚
˚
atoms, and in 2 (2.47 A), in which TFA is monodentate.
Spectral Characteristics
While no inter-chain hydrogen-bonding interactions are
found between adjacent polymeric chains viewed from the
x axis, they do exist between adjacent chains viewed from
the y axis (Table 5 and packing diagram in Figure 6).
VT-1H NMR Spectral Features
1
At 328 K the H NMR spectrum of 1 in CDCl3 shows
two singlets at δ ϭ 3.96 and 4.45 ppm for the α- and β-
protons of the Cp rings of dppf and a multiplet at δ ϭ
7.39Ϫ7.54 ppm (unresolved δ ϭ 7.39, 7.41, 7.44, 7.47, 7.50,
7.52 and 7.54 ppm) for the Ph protons of dppf. These fea-
tures vary little upon lowering the temperature to 243 K Ϫ
there is mainly a loss of resolution in the Ph multiplet and
slight broadening of the β-CpH signal (δ ϭ 4.39 ppm) with
concurrent greater broadening of the α-CpH signal (δ ϭ
3.85 ppm); below 243 K both α and β signals undergo
extensive broadening.
1
The H NMR spectrum of 2 in (CD3)2CO at 300 K and
above shows only one peak, at δ ϭ 4.44 ppm, for the Cp
protons of dppf and two multiples, δ ϭ 7.45Ϫ7.50 and
7.68Ϫ7.70 ppm, for the Ph protons of dppf. Below 273 K,
the Cp singlet transforms into a broad unresolved multiplet,
Figure 5. Section of the polymeric chain of 3; hydrogen atoms omit-
ted for clarity; thermal ellipsoids drawn to 50% probability
˚
Table 4. Selected bond lengths [A] and bond angles [°] for complex 3; symmetry transformations used to generate the ‘‘A’’ atoms: Ϫx, y,
Ϫz ϩ 0.5
Ag1ϪP1
Ag1ϪO1A
C1ϪO1A
2.4267(17)
2.518(8)
1.190(9)
Ag1ϪO1
C1ϪO1
2.518(8)
1.190(9)
Ag1ϪP1A
C1ϪC2
2.4267(17)
1.67(3)
P1ϪAg1ϪP1A
P1ϪAg1ϪO1
C1ϪO1ϪAg1
129.58(9)
110.07(18)
92.6(8)
P1ϪAg1ϪO1A
P1AϪAg1ϪO1
O1ϪC1ϪC2
115.47(18)
115.47(18)
117.4(7)
P1AϪAg1ϪO1A
O1AϪAg1ϪO1
O1ϪC1ϪO1A
110.07(18)
49.6(3)
125.2(14)
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Supramolecular Structures in [Ag(dppf)] Complexes
FULL PAPER
˚
Table 5. Hydrogen-bond lengths [A] and bond angles [°] for 3
˚
˚
˚
DϪH
DϪH [A]
A
H···A [A]
DϪA [A]
ЄDHA [°]
Symmetry
C4AϪH4A
C5ϪH5
0.94
0.94
F2
O1
2.63
2.47
3.479(19)
3.351(10)
149
155
0.5 Ϫ x, 0.5 Ϫ y, 1 Ϫ z
Ϫx, 1 Ϫ y, 1 Ϫ z
˚
Table 6. Selected bond lengths [A] and bond angles [°] for com-
plex 4
Ag(1)ϪP(1)
Ag(1)ϪP(3)
P(1)ϪC(101)
P(3)ϪC(301)
P(3)ϪC(31)
P(4)ϪC(41)
2.5474(12) Ag(1)ϪP(2)
2.5371(13) Ag(1)ϪP(4)
2.5700(12)
2.5212(13)
1.808(5)
1.816(5)
1.829(5)
1.817(6)
1.08(5)
P(2)ϪC(201)
P(4)ϪC(401)
P(3)ϪC(32)
P(4)ϪC(42)
1.820(5)
1.821(5)
1.812(5)
P(1)ϪAg(1)ϪP(2) 105.96(4)
P(4)ϪAg(1)ϪP(1) 112.47(4)
P(4)ϪAg(1)ϪP(2) 107.5(4)
P(3)ϪAg(1)ϪP(4) 105.87(5)
P(3)ϪAg(1)ϪP(1) 113.80(4)
P(3)ϪAg(1)ϪP(2) 111.07(4)
δ ϭ 7.37 ppm, and the Cp signals as two broad singlets at
δ ϭ 4.34 and 4.25 ppm; at lower temperatures these were
transformed into several unassignable broad peaks at δ ϭ
2.5Ϫ6.3 ppm.
VT-19F NMR Spectral Features
The sharp 19F signal of 1 in CDCl3 varies slightly, from
δ ϭ 1.6 ppm at 300 K to δ ϭ 1.7 ppm at 223 K, while that
of complex 2 in (CD3)2CO undergoes a greater downfield
shift, from δ ϭ 2.4 ppm at 323 K to δ ϭ 2.7 ppm at 223 K,
with increasing line-width broadening. Below this, the peak
transformed into two broad overlapping peaks, which at
183 K are seen at δ ϭ 3.1 and 2.8 ppm (relative intensity
ca. 1:2); these overlapping peaks indicate the presence of
trifluoroacetate ligands in different coordination environ-
ments, most probably caused by different denticities of the
ligands. This is accompanied by complex variations in the
1H and 31P{1H} NMR spectra.
Figure 6. Packing diagram of 3 viewed from the y axis, showing
two layers in the central chain, and inter-chain [CϪH(Ph)···FϪC]
hydrogen-bonding interactions
The VT-19F NMR spectrum of 3 in CDCl3 shows only
one sharp peak (δ ϭ 1.2 ppm) in the range 300Ϫ223 K,
while at 213 K a minor peak (ca. 10%) emerges at δ ϭ
1.7 ppm, indicating two types of coordinated trifluoroacet-
ate ligands, as in 2 above.
VT-31P{1H} NMR Spectral Features
The variations of 1 in CDCl3 are shown in Figure 8. A
broad peak at δ ϭ 6.6 ppm (ν1/2 ϭ 405 Hz) at 328 K broad-
ens further at 313 K (δ ϭ 6.5 ppm, ν1/2 ϭ 607 Hz). At
296 K, three overlapping broad peaks appear at δ ϭ 10.1,
7.4 and 4.2 ppm (ν1/2 ϭ 146, 255 and 146 Hz, with relative
intensity ca. 1:2:1); these gradually transform into two pairs
of sharp doublets at 223 K, being centered at δ ϭ 7.6 ppm
(J107/109AgϪP ϭ 695 and 805 Hz), indicative of coordi-
Figure 7. Molecular structure of cationic 4; hydrogen atoms omit-
ted for clarity; thermal ellipsoids drawn to 50% probability
which at 223 K, is centered at δ ϭ 4.50 ppm, while the mul- nation of one P atom to an Ag atom,[18] which is in agree-
tiplicity of the phenyl protons is also drastically changed.
ment with its solid-state structure. These VT features can
In CDCl3 at 300 K, the Ph protons of 3 are seen as a be rationalized in terms of 31PϪ107Ag/109Ag inter- and in-
broad peak at δ ϭ 7.52 ppm and a multiplet centered at tramolecular exchange processes first observed by Dean
Eur. J. Inorg. Chem. 2004, 2504Ϫ2513
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2509

X. L. Lu, W. K. Leong, L. Y. Goh, A. T. S. Hor
FULL PAPER
and co-workers in dinuclear Ag complexes containing range (88Ϫ200 cmϪ1) reported for bridging trifluoroacetate
bridging diphosphanes.[19]
complexes.[20] The ∆ν˜(asymm. Ϫ symm.) ϭ 231 cmϪ1 of 2
for monodentate trifluoroacetates is similar to 232 cmϪ1 in
PhHg(O2CMe) containing monodentate carboxylate
groups.[20] The IR stretching frequencies of 3 are close to
those of 2, with a ∆ν˜(asymm. Ϫ symm.) of 227 cmϪ1, very
close to that in 2, even though, unlike 2, its acetate ligand
is in a chelating mode. Notably, ∆ν˜(asymm. Ϫ symm.) for
the trifluoroacetate ligand in 3 far exceeds those of most
chelating acetate ligands (65Ϫ175 cmϪ1), except for those
of Sn(O2CMe)4 (320, 440 cmϪ1).[20] CϪH stretches of the
Cp and Ph rings of dppf in 2 are observed as two weak
unresolved peaks at ν ϭ 3077 and 3058 cmϪ1, while 1A/1B
˜
and 3 also show two CϪH stretches in the same frequency
range, but in addition exhibit three other very weak peaks
between ν ϭ 2960 and 2853 cmϪ1. Presumably, these lower-
˜
frequency stretches pertain to CϪH hydrogen-bonded to O
or F of TFA, as shown in their crystal structures.
Conclusion
Facile interactions between silver trifluoroacetate and
dppf afford a coordination polymer or dinuclear species
possessing TFA in different bonding modes, depending on
the stoichiometry of the reactants. Weak hydrogen-bonding
interactions (CϪH···F and CϪH···O) in the dinuclear com-
pounds yield 2D supramolecular structures, the nature of
which varies with solvent molecules in the crystal lattice.
Figure 8. VT 31P{1H} NMR spectra of 1 in CDCl3
31P NMR spectra in (CD3)2CO of 2 show a very broad
peak at δ ϭ Ϫ1.2 ppm (ν1/2 ഠ 300 Hz) at 300 K. As the
temperature is lowered to 183 K, a combination of broad
bands and 107/109Ag-coupled doublets appear. With 3, a de-
crease of temperature causes the broad ambient-tempera-
ture signal [δ ϭ Ϫ1.5 ppm (ν1/2 ϭ 600 Hz)] to transform
into a very complex pattern, consisting of several broad
‘‘humps’’, which can not be rationalized. The only distinc-
tive feature is a doublet at δ ϭ Ϫ3.45 ppm , which is observ-
able at 223 K and below with J107/109AgϪP couplings of
418 and 482 Hz, indicative of coordination of two P atoms
per Ag atom, which is consistent with its solid-state linear
polymeric structure.
Experimental Section
General: Ag(O2CCF3), PMe2Ph and NH4PF6 were purchased from
Aldrich, and dppf from STREM, and used as supplied. All reac-
tions were performed under dry nitrogen using Schlenk techniques.
Solvents were freshly distilled from standard drying agents. NMR
spectra were recorded with a Bruker ACF300 FT NMR spec-
trometer (1H at 300.13 MHz; 31P{1H} at 121.50 MHz and 19F at
282.38 MHz), with chemical shifts referenced to residual non-deut-
erated solvent, external H3PO4 and external CF3COOH, respec-
tively. Infrared spectra were measured in KBr pellets in the range
of 400Ϫ4000 cmϪ1 with a Perkin-Elmer 1600 FT-IR spectrometer.
FAB and ESI mass spectra were obtained with Finnigan
MAT95XL-T and MATLCQ spectrometers, respectively. All el-
emental analyses were carried out in-house.
Mass Spectra
FABϩ-MS spectra of 1A/1B and 2 do not show the par-
ent ion fragment [Mϩ], but fragments arising from the con-
secutive loss of an O2CCF3 ligand and an Ag(O2CCF3)
moiety, leading to m/z ϭ 661 [Ag ϩ dppf] as the most in-
tense fragment. The FABϩ-MS spectrum of 3 is identical to
that of 2. The highest mass fragment in the ESIϩ-MS spec-
trum of 4 arises from the addition of 1 equiv. of PMe2Ph
to the parent ion at m/z ϭ 1216 [Mϩ ϩ PMe2Ph], followed
Syntheses
Reactions of Ag(O2CCF3) with dppf. Using Ag؉/dppf (2:1) in THF/
MeOH. Synthesis of [Ag2(O2CCF3)2(dppf)] (1): Ligand dppf
(0.111 g, 0.20 mmol) in THF (10 mL) was added to a solution of
by fragments showing consecutive losses of PMe2Ph to Ag(O2CCF3) (0.094 g, 0.43 mmol) in MeOH (10 mL) and the re-
yield m/z ϭ 661 as the strongest peak. The FABϩ-MS spec-
trum of 5 only shows the most intense peak at m/z ϭ 662.
sultant solution stirred for 8 h. The so-obtained orange suspension
was filtered through Celite, and the orange filtrate was concen-
trated to ca. 2 mL. Addition of diethyl ether (5 mL) and cooling at
0Ϫ5 °C for 3 h gave yellow air-stable, non-light-sensitive crystals of
a THF solvate of [Ag2(O2CCF3)2(dppf)] (1) (0.073 g, 0.07 mmol,
Infrared Spectra
IR spectra of 1A/1B show the bridging O2CCF3 vibration
frequencies at ν˜ ϭ 1684 (asymm.), 1437 (symm.), 1207 and
34%). C38H28Ag2F6FeO4P2·0.6C4H8O (1039.4): calcd. C 46.6, H
1
3.2, P 6.0; found C 45.9, H 2.7, P 6.0. H NMR (CDCl3, 300 K):
1133, with ∆ν(asymm. Ϫ symm.) ϭ 247 cmϪ1 Ϫ outside the δ ϭ 7.39Ϫ7.55 (m, 20 H, Ph), 4.44 and 3.92 (each s, 4 H, C5H4)
˜
2510
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 2504Ϫ2513

Supramolecular Structures in [Ag(dppf)] Complexes
ppm. 31P{1H} NMR: δ ϭ 10.1, 7.4 and 4.2 ppm (ν1/2 ϭ 146, 255 to 5 h. The 31P signals varied from δ ϭ Ϫ1.4 to Ϫ1.0 ppm (ca.
FULL PAPER
and 146 Hz, with relative intensity ca. 1:2:1). 19F NMR: δ ϭ
400 Hz), while the F signals were seen as overlapping singlets of
1.6 ppm. FABϩ-MS: m/z ϭ 883 [M Ϫ O2CCF3]ϩ, 661 [M Ϫ Ag Ϫ equal intensity at δ ϭ 1.3 and 0.9 ppm. These resonances did not
2 (O2CCF3)]ϩ, 1437 [M ϩ dppf]ϩ. IR (KBr cmϪ1): νCO : 1684, appear in the region of those in the spectrum of 2.
2
1437, 1207, 1133; νothers: 3071 w, 3050 w, 2960 vwbr, 2923 vw, 2852
Reaction with PMe2Ph: Ligand PMe2Ph (0.04 mL, 0.26 mmol) was
added to a solution of 1 (0.05 g, 0.05 mmol) in MeOH (15 mL).
After stirring for 1 h, NH4PF6 (0.035 g, 0.21 mmol) was added. A
bright yellow precipitate then began to separate, and the mixture
was stirred for a further 30 min. The precipitate was filtered off
and recrystallized from CH2Cl2/diethyl ether to give air-stable, non-
light-sensitive yellow crystals of [Ag(dppf)(PMe2Ph)2]PF6 (4)
(25.8 mg, 48%). C50H50AgF6FeP5·H2O (1101.6): calcd. C 54.5, H
vwbr, 1508 w, 1021 m, 838 m, 803 s, 724 vs, 696 s, 518 w, 456
w. Concentration of the mother liquor to dryness, redissolution in
CH2Cl2, followed by addition of diethyl ether (3 mL) then gave an
orange
solid
of
1·0.5CH2Cl2
(0.065 g,
30%
yield).
C38H28Ag2F6FeO4P2·0.5CH2Cl2 (1038.6): calcd. C 44.5, H 2.8;
1
found C 44.8, H 2.9. H NMR (CDCl3): As above with additional
δ ϭ 5.30 ppm (CH2Cl2). 19F NMR: As above. 31P{1H} NMR: With
slight variations: δ ϭ 10.4, 7.4, 4.3 ppm (ν1/2 ϭ 54, 121 and 54 Hz,
relative intensity 1:2:1). A similar reaction of Ag(O2CCF3) (0.404 g,
1.83 mmol) and dppf (0.507 g, 0.92 mmol) in CH2Cl2 (20 mL) for
6 h furnished a yellow solid of 1·CH2Cl2 (0.811 g, 90%). Crystalli-
zation of 1 in THF/MeOH and CH2Cl2/diethyl ether gave orange
diffraction-quality crystals of 1·0.5THF ϵ 1A and 1·0.5CH2Cl2 ϵ
1B, respectively, after 1 d at ambient temperature.
1
4.8; found C 54.2, H 4.8. H NMR (CDCl3): δ ϭ 7.60Ϫ7.81 (Ph),
4.68, 4.56, 4.03 (C5H4), 1.82 (d, J ϭ 13 Hz, PMe2Ph) ppm. 31P{1H}
NMR: δ ϭ 39.8 and 3.9 (dppf), Ϫ5.5 (PMe2Ph), Ϫ144 (sept) ppm.
ESIϩ-MS: m/z ϭ 1216 [M ϩ PMe2Ph]ϩ, 798 [M Ϫ PMe2Ph]ϩ, 661
[M Ϫ 2 PMe2Ph]ϩ. IR (Nujol, cmϪ1): νPF : 840 and 556. Single
6
diffraction-quality crystals were obtained by recrystallization in
MeOH/diethyl ether (1:4) after 1 d at Ϫ30 °C.
Using Ag؉/dppf (1:1) in CH2Cl2. Synthesis of [Ag2(-
O2CCF3)2(dppf)2] (2): Ligand dppf (1.014 g, 1.83 mmol) was added
to a suspension of Ag(O2CCF3) (0.404 g, 1.83 mmol) in CH2Cl2
(15 mL) and the mixture stirred at room temperature for 3 h. The
resultant orange homogeneous solution was concentrated to ca.
2 ml; the subsequent addition of hexane (2 mL) gave yellow solids
of [Ag2(O2CCF3)2(dppf)2] (2)·0.25CH2Cl2 (1.23 g, 86%).
C72H56Ag2F6Fe2O4P4·0.25CH2Cl2 (1571.8): calcd. C 55.2, H 3.6;
found C 55.2, H 3.95. 1H NMR [(CD3)2CO, 300 K]: δ ϭ 7.69, 7.48
(each centered m, 8-H and 12-H, respectively, Ph), 4.44 (s, 8 H,
C5H4) ppm. 31P{1H} NMR: δ ϭ Ϫ1.2 ppm (ν1/2 ഠ 300 Hz). 19F
NMR: δ ϭ 2.4 ppm. 1H NMR (CDCl3, 300 K): δ ϭ 7.41, 7.33
(each centered m, 12-H and 8-H, respectively, Ph), 4.51 and 4.05
Variable-Temperature (VT) NMR Spectra: 1H, 31P{1H} and 19F VT
NMR spectra obtained for complexes 1Ϫ3 are described in the
Results and Discussion section.
Crystal Structure Determinations: Crystals were mounted on quartz
fibers. X-ray data were collected with a Bruker AXS SMART CCD
diffractometer, using Mo-Kα radiation (λ ϭ 0.71073 A) at 223 K
˚
(for 1Ϫ3) or 293 K (for 4) (Table 7).The program SMART[21] was
used to collect the intensity data, indexing and determination of
lattice parameters, SAINT[22] was used to integrate the intensity of
reflections and scaling, SADABS[21] was used for absorption cor-
rection and SHELXTL[23] for space group and structure determi-
nation and least-squares refinements against F2. The structure was
solved by direct methods to locate the heavy atoms, followed by
difference maps for the light, non-hydrogen atoms. Cp and Ph hy-
drogen atoms were placed in calculated positions. For 1A, the crys-
tal was modeled as a racemic twin. The CF3 groups were treated
as disordered over two alternative sites with equal occupancies; the
two sites were symmetry-related. CϪF and F···F distances were
restrained to be equal, and the F atoms were given individual iso-
tropic thermal parameters. There was a half molecule of THF dis-
(each s, 4 H, C5H4) ppm. 31P{1H} NMR: δ ϭ Ϫ1.0 ppm (ν1/2
ഠ
300 Hz). 19F NMR: δ ϭ Ϫ0.1 ppm. FABϩ-MS: m/z ϭ 1437 [M Ϫ
O2CCF3] ϩ, 1216 [M Ϫ Ag Ϫ 2 (O2CCF3)]ϩ, 661 [M Ϫ Ag Ϫ 2
(O2CCF3) Ϫ dppf]ϩ. IR (KBr, cmϪ1): νCO : 1664 s, 1433 m, 1199
2
s, 1131 s; νothers: 3077 wsh, 3058 wbr, 1480 w, 1313 vw, 1175 ssh,
1031 w, 837 m, 764 m, 697 s, 484 mbr. Diffraction-quality single
crystals of 2 were obtained from a solution in CHCl3 layered with
hexane after 1 d at room temperature.
Reactions of [Ag2(O2CCF3)2(dppf)] (1). Reaction with dppf. Syn- ordered about a twofold axis. This was modeled over two alterna-
thesis of [Ag(O2CCF3)(dppf)]n (3): Ligand dppf (0.03 mL,
0.05 mmol) was added to a solution of 1 (0.050 g, 0.05 mmol) in
tive sites of equal occupancies with the oxygen and two carbon
atoms common; all the carbon atoms were given a common iso-
CH2Cl2 (15 mL) and the mixture stirred for 3.5 h. The homo- tropic thermal parameter, with that for the oxygen at 1.1 times that
geneous product solution was then concentrated to ca. 1 mL, fol- of the carbon atoms. Appropriate restraints were placed to keep
lowed by addition of hexane (1.5 mL), whereupon an orange solid the geometry reasonable. For 2, the CHCl3 solvent molecule was
of [Ag(O2CCF3)(dppf)]n (3) (0.034 g, 88%) separated. modeled as disordered over two sites; occupancies were refined and
C72H56Ag2F6Fe2O4P4 (1550.6): calcd. C 55.8, H 3.6; found C 55.2,
summed to unity. CϪCl and Cl···Cl distances were restrained to be
equal. Anisotropic thermal parameters for each Cl atom were
paired with that of the alternative site. For 3, the CF3 groups were
H 3.95. 1H NMR (CDCl3, 300 K): δ ϭ 7.52 (ν1/2 ഠ 20 Hz, 8 H,
Ph), 7.37 (centered m, 12 H, Ph), 4.34 and 4.25 (each s, ν1/2
ഠ
15 Hz, 4 H, C5H4) ppm. 31P{1H} NMR: δ ϭ Ϫ1.5 ppm with sh at treated as disordered over two alternative sites with equal occu-
Ϫ3.0 (combined ν1/2 ഠ 600 Hz). 19F NMR: δ ϭ 1.2 ppm. FABϩ-
pancies; the two sites were symmetry-related. CϪF and F···F dis-
tances were restrained to be equal, and atoms were given isotropic
MS: As in 2. IR (KBr, cmϪ1): νCO : 1662 s, 1435 m, 1200 vs, 1133
2
s; νothers: 3081 wsh, 3051 w, 2960 w, 2923 w, 2863 vw, 1480 w, 1098 thermal parameters. Crystal data and refinement parameters are
m, 1031 w, 836 w, 798 vw, 745 m, 722 vw, 696 s, 513 ssh, 487 sbr.
Diffraction-quality crystals were obtained from CH2Cl2, layered
with hexane, after 1 d at ambient temperature. The reaction was
also monitored in an NMR tube in CDCl3 at intervals up to 5.5 h.
After 15 min, the proton spectrum showed two broad overlapping
Cp signals centered at δ ϭ 4.35 and 4.22 ppm, with a combined
halfwidth of ca. 75 Hz. These sharpened with time and after 3.5 h
were at δ ϭ 4.34 and 4.25 ppm; these then remained unchanged up
given in Table 7. Selected bond lengths and angles for 1A/1B, 2, 3
and 4 are in Tables 1, 3, 4 and 6, respectively. Hydrogen bonds and
angles of 1A/1B and 3 are in Tables 2 and 5, respectively. CCDC-
193074 to -193076 and -215390 to -215391 for complexes 1B, 3,
1A, 2 and 4, respectively contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
Eur. J. Inorg. Chem. 2004, 2504Ϫ2513
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2511

X. L. Lu, W. K. Leong, L. Y. Goh, A. T. S. Hor
Table 7. Crystal data and parameters related to the structure determination and refinement for 1Ϫ4
FULL PAPER
1A (1·0.5C4H8O)
1B (1·0.5CH2Cl2)
2·CHCl3
3
4
Empirical formula
Formula mass
Temperature [K]
Crystal system
Space group
C40H32Ag2F6FeO4.50P2 C38.5H29Ag2ClF6FeO4P2 C37H29AgCl3F3FeO2P2 C36H28AgF3FeO2P2 C50H50AgF6FeP5
1032.19
223(2)
tetragonal
I-42d
1038.60
223(2)
monoclinic
P21/c
894.61
223(2)
triclinic
775.24
223(2)
monoclinic
C2/c
1083.47
293(2)
monoclinic
P21/n
¯
P1
Crystal size [mm]
0.32 ϫ 0.22 ϫ 0.16
28.3502(5)
28.3502(5)
10.6842(2)
90
90
90
8587.3(3)
8
1.597
0.40 ϫ 0.40 ϫ 0.38
10.2862(6)
17.6488(9)
22.0971(12)
90
90.6710(10)
90
4011.2(4)
4
0.22 ϫ 0.08 ϫ 0.04
12.1521(11)
13.1192(12)
13.7594(12)
118.007(2)
103.871(2)
95.312(2)
1825.6(3)
2
1.627
0.30 ϫ 0.25 ϫ 0.15
12.790(2)
24.101(4)
16.495(3)
90
110.304(4)
90
4768.7(15)
4
0.30 ϫ 0.16 ϫ 0.09
14.2739(2)
20.9706(2)
17.0519(2)
90
106.9810(10)
90
4881.65(10)
4
˚
a [A]
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
3
˚
V [A ]
Z
Dcalcd. [Mg·mϪ3
]
1.720
1.080
1.474
Absorption coefficient
1.376
1.536
1.289
0.817
0.919
F(000)
4096
2052
896
1560
2208
Θ range for data collection [°] 2.03Ϫ24.71
1.84Ϫ25.00
Ϫ9 Յ h Յ 12
Ϫ19 Յ k Յ 20
Ϫ24 Յ l Յ 26
22913
2.07Ϫ26.37
Ϫ15 Յ h Յ 14
Ϫ16 Յ k Յ 14
0 Յ l Յ 17
24654
2.14Ϫ26.37
Ϫ15 Յ h Յ 14
0 Յ k Յ 30
0 Յ l Յ 20
19161
2.21Ϫ29.41
Ϫ19 Յ h Յ 17
0 Յ k Յ 28
0 Յ l Յ 23
31993
Index ranges
Ϫ23 Յ h Յ 23
0 Յ k Յ 33
0 Յ l Յ 12
55438
Reflection collected
Independent reflections
Transmission, max./min.
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
3619
7057
7445
4873
12074
0.8099/0.6673
3619/32/243
1.254
R1 ϭ 0.0784
wR2 ϭ 0.1827
R1 ϭ 0.0925
wR2 ϭ 0.1937
0.923/Ϫ0.441
0.5929/0.5785
7057/78/528
1.037
R1 ϭ 0.0389
wR2 ϭ 0.1117
R1 ϭ 0.0422,
wR2 ϭ 0.1144
1.198/Ϫ1.055
0.9502/0.7646
7445/30/452
1.082
R1 ϭ 0.0677
wR2 ϭ 0.1449
R1 ϭ 0.0891
wR2 ϭ 0.1559
1.865/Ϫ0.976
0.8875/0.7920
4873/6/195
1.132
R1 ϭ 0.0711
wR2 ϭ 0.2267
R1 ϭ 0.0989
wR2 ϭ 0.2384
1.277/Ϫ0.492
0.9280 & 0.7639
12074/0/568
1.027
R1ϭ 0.0612
wR2ϭ 0.1005
R1ϭ 0.1412
wR2ϭ 0.1284
0.621/Ϫ0.496
R indices (all data)
Largest diff. peak/hole
R ϭ (ΣFo Ϫ Fc)ΣFo. Rw ϭ [(ΣωFo Ϫ Fc)2/ΣωFo2 1/2. GoF ϭ [(ΣωFo Ϫ Fc)2/(Nobsd. Ϫ Nparam.)]1/2
] .
[2]
[2a]
See for instance the following and references cited therein:
bridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
L. Carlucci, G. Ciani, D. M. Proserpio, A. Sironi, J. Am. Chem.
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Received September 30, 2003
Early View Article
Published Online April 7, 2004
Eur. J. Inorg. Chem. 2004, 2504Ϫ2513
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2513