Silver(I) tertiary phosphine complexes: Influence of the anion on the structural and spectroscopic properties

Article abstract of DOI:10.1016/j.poly.2009.10.008

Two-, three- and four-coordinate silver(I) complexes, AgX (X = CN^-, PF₆^-, and SbF₆^-), with triphenyl phosphine, tricyclohexyl phosphine, diphenylcyclohexyl phosphine, and dicyclohexylphenyl phosphine have been synthesised and characterised by single crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and ¹³C and ³¹P NMR spectroscopy. From the reaction of a metal salt to phosphine ligand ratio of 1:1 the various compounds crystallize as 1:2, 1:3, and 1:4 compounds [Ag(PPh₂Cy)₃(CN)]·5H₂O (1), [Ag(PCy₃)₂]·PF₆ (2), [Ag(PPh₃)₄)]·SbF₆·CHCl₃ (3), [Ag(PCy₃)₂]·SbF₆ (4), [Ag(PPh₂Cy)₂(C₃H₆O)]·SbF₆ (5), and [Ag(PPhCy₂)₂]·SbF₆.CHCl₃ (6) monomers, with a wide variety of geometries around the central silver(I) atom. Compounds 1 and 3 have slightly distorted tetrahedral geometry around the silver(I) atom. The compounds 2, 4, and 6 show linear geometry around the metal centre, while compound 5 has a distorted trigonal planar geometry. The elemental analysis and NMR spectroscopic results are consistent with the single crystal structural analyses.

Full text of DOI:10.1016/j.poly.2009.10.008

Polyhedron 29 (2010) 701–708
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Silver(I) tertiary phosphine complexes: Influence of the anion on the structural
and spectroscopic properties
*
Muhammad Altaf , Helen Stoeckli-Evans
Institute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland
a r t i c l e i n f o
a b s t r a c t
Two-, three- and four-coordinate silver(I) complexes, AgX (X = CNÀ, PF6À, and SbF6À), with triphenyl phos-
phine, tricyclohexyl phosphine, diphenylcyclohexyl phosphine, and dicyclohexylphenyl phosphine have
been synthesised and characterised by single crystal X-ray diffraction, elemental analysis, infrared spec-
troscopy, and 13C and 31P NMR spectroscopy. From the reaction of a metal salt to phosphine ligand ratio of
1:1 the various compounds crystallize as 1:2, 1:3, and 1:4 compounds [Ag(PPh2Cy)3(CN)]Á5H2O (1), [Ag(P-
Cy3)2]ÁPF6 (2), [Ag(PPh3)4)]ÁSbF6ÁCHCl3 (3), [Ag(PCy3)2]ÁSbF6 (4), [Ag(PPh2Cy)2(C3H6O)]ÁSbF6 (5), and
[Ag(PPhCy2)2]ÁSbF6.CHCl3 (6) monomers, with a wide variety of geometries around the central silver(I)
atom. Compounds 1 and 3 have slightly distorted tetrahedral geometry around the silver(I) atom. The
compounds 2, 4, and 6 show linear geometry around the metal centre, while compound 5 has a distorted
trigonal planar geometry. The elemental analysis and NMR spectroscopic results are consistent with the
single crystal structural analyses.
Article history:
Received 29 July 2009
Accepted 5 October 2009
Available online 14 October 2009
Keywords:
Tertiary phosphines
Silver(I) complexes
Crystal structure
Spectroscopic studies
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
show a diversity of structural types and several reviews on this to-
pic has been published [28–31]. The metal centre in the majority of
Silver(I) exhibits a remarkable diversity in its structural chem-
istry and this is illustrated by the wide variety of structural types
that are encountered in complexes of silver(I) salts. In silver(I)
mononuclear and multinuclear complexes with neutral phosphine
and amine ligands the silver(I) atom exhibits variable coordination
numbers [1–5]. Reactions of AgX (X = NOÀ3 , ClO4À, C2H3O2À, CNÀ,
SCNÀ, PF6À, SbF6À, ClÀ, BrÀ, and IÀ etc.,) with monodentate tertiary
phosphine and multidentate nitrogen donor bases yielded a di-
verse array of two-, three- and four-coordinate complexes with
structural and spectroscopic properties that are determined by,
specific choices of the phosphine and the other ligands, the stoichi-
ometry and to a lesser extent by the choice of the anion [6–10].
Tertiary phosphine complexes of silver(I) of the type [AgXLn],
where L = tertiary phosphine; n = 1–4; X = coordinating or non-
coordinating anion, were first prepared in 1937 [11]. The general
method of preparation involves the reaction of stoichiometric
amounts of the phosphine ligand with the appropriate silver(I) salt.
The reaction of silver(I) salts with monodentate tertiary phos-
phines in a 1:2 stoichiometric ratio generally results in the forma-
tion of either monomeric [AgX(PR3)2]/[Ag(PR3)2]ÁX or dimeric
complexes [{AgX(PR3)2}2], depending on the donor properties of
the phosphine ligand, the bulkiness of the ligand, the substituents
and the donor properties of the anion [12–27]. These complexes
the neutral [AgX(PR3)2] and [{AgX(PR3)2}2] complexes are predom-
inantly four-coordinate with the anion acting as either as a biden-
tate chelating ligand or as a bridging ligand, with two or three
coordination found only in circumstances where the anion is a
weak donor or the substituents on the phosphine ligand are bulky
[16,19–24].
There is great interest to understand about how the molecular
properties of the ligands affect the evolving structures of the com-
plexes and their physical, chemical and biological properties
[32,33]. Much effort has been devoted to the design and syntheses
of pre-organised ligands that are able to control the structure and
properties of complexes [34–37]. Silver(I) complexes with various
N, S, O, P, and C donor ligands are of growing interest owing to their
wide variation in structural format and rich physical, photo-phys-
ical, biological and chemical properties [38–43].
In our current investigations into the dependence of the struc-
tural and spectroscopic properties of these compounds on the
choice of monodentate tertiary phosphine and coordinating and
non-coordination anions, we have sought to extend the array of
available data for two-, three-, and four-coordinate complexes of
silver(I) with triphenyl phosphine, tricyclohexyl phosphine, cyclo-
hexyldiphenyl phosphine, and dicyclohexyl(phenyl) phosphine
(Scheme 1).
Spectroscopic data has been obtained from infrared spectros-
copy and 1H, 13C and 31P NMR spectroscopy. Along with X-ray dif-
fraction techniques, there are several potentially useful
* Corresponding author. Tel.: +41 32 718 24 00; fax: +41 32 718 25 11.
E-mail address: muhammad.altaf@unine.ch (M. Altaf).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.10.008

702
M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
2.3. Preparation of [Ag(PCy3)2]ÁPF6 (2)
To the solution of AgPF6 (0.025 g, 0.1 mmol) in acetonitrile
(5 mL) was added tricyclohexyl phosphine (0.057 g, 0.2 mmol) in
CH2Cl2 (10 mL). The reaction mixture was stirred for 30 min at
room temperature. The colourless solution obtained was filtered
to avoid any impurity and left undisturbed for crystallization. After
a couple of days colourless crystals were obtained (Yield 83%) Anal.
Calc. for C36H66AgF6P3: C, 53.09; H, 8.11. Found: C, 54.10; H, 8.46%.
P
P
IR (t
, cmÀ1): 3549m, 3409m, 2922s, 2825s, 1633m, 1618s, 1451vs,
1293m, 1171s, 1015s, 834vs, 622m, 557s. 1H NMR (CD2Cl2–d2;
ppm): 1.6–2.1, 2.4 (m, 33H, cyclohexyl protons). 13C NMR
(CD2Cl2–d2; ppm): 25.22–31.96 (cyclohexyl carbons). 31P NMR
(CD2Cl2–d2; ppm): 37.71, 40.68 (d, two broad peaks for phospho-
rous atom of tricyclohexyl phosphine and PFÀ6 counter ion).
tricyclohexyl phosphine
triphenyl phosphine
P
2.4. Preparation of [Ag(PPh3)4)].SbF6ÁCHCl3 (3)
P
To the solution of AgSbF6 (0.035 g, 0.1 mmol) in acetonitrile
(5 mL) was added 2-mercapto thiazoline (0.018 g, 0.2 mmol) in
MeOH (5 mL) and triphenyl phosphine (0.027 g, 0.1 mmol) in
CHCl3 (10 mL). The reaction mixture was stirred overnight at
50 °C. The resultant solution was evaporated slowly at room tem-
perature. After three days colourless block crystals of unexpected
product was obtained. A suitable crystal was chosen for X-ray dif-
fraction studies. The crystalline product was collected by filtration
(Yield 17% with respect to silver salt). Anal. Calc. for
C73H61AgCl3F6P4Sb: C, 57.93; H, 4.03. Found: C, 57.13; H, 4.56%.
cyclohexyldiphenyl phosphine
dicyclohexyl(phenyl) phosphine
Scheme 1. Chemdraw structures of tertiary phosphine ligands.
spectroscopic techniques for characterising compounds in the solid
state and solution. Thus IR, and NMR spectroscopy have proved to
be useful techniques for the determination of the structures of sil-
ver(I) complexes [44,5,45,46]. Silver(I)-phosphine complexes and
their single crystal X-ray structures, IR absorption spectra and
NMR spectroscopic properties are discussed here.
IR (t
, cmÀ1): 3551m, 3478s, 3412s, 3075m, 3052m, 1633m,
1615s, 1437vs, 1257m, 1155s, 1013s, 750m, 843m, 646vs, 503m.
No NMR measurement was carried out due to the very little
amount of the final product.
2. Experimental
2.5. Preparation of [Ag(PCy3)2]ÁSbF6 (4)
2.1. Material and physical measurements
To the solution of AgSbF6 (0.035 g, 0.1 mmol) in acetonitrile
(5 mL) was added tricyclohexyl phosphine (0.057 g, 0.2 mmol) in
CH2Cl2 (10 mL). The reaction mixture was stirred for 30 min at
room temperature. Transparent solution obtained was left undis-
turbed for crystallization at room temperature by slow evapora-
tion. After three days colourless rod like crystals were obtained
(Yield 74%). Anal. Calc. for C36H66AgF6P2Sb: C, 47.76; H, 7.29.
All the reactions were carried out in air. All the reactants and
solvents were commercial products of Aldrich and ACROS and were
used with out further purification. In all cases, the crystalline prod-
ucts were obtained by the slow evaporation method. Microanaly-
ses were carried out by Mr. D. Mooser (Ecole d’ingénieurs de
Fribourg, Filière de chimie). The IR spectra were recorded as KBr
plates on a Perkin–Elmer Spectrum One FTIR instrument.1H, 13C,
and 31P NMR spectra were recorded on Bruker AMX 400 MHz using
CD2Cl2–d2 as solvent. The TMS was used as the internal standard.
Found: C, 47.95; H, 7.25%. IR (t
, cmÀ1): 3553m, 3412m, 2929s,
2823s, 1634m, 1617s, 1447vs, 1291m, 1168s, 1003s, 837vs,
628m, 555s. 1H NMR (CD2Cl2–d2; ppm): 1.5–2.2, 2.5 (m, 33H,
cyclohexyl protons). 13C NMR (CD2Cl2–d2; ppm): 25.82–31.77
(cyclohexyl carbons). 31P NMR (CD2Cl2–d2; ppm): 39.38, 42.31(d.
two peaks for phosphorous atom of tricyclohexyl phosphine).
2.2. Preparation of [Ag(PPh2Cy)3(CN)]Á5H2O (1)
To the solution of AgCN (0.014 g, 0.1 mmol) in MeOH/distilled
water (3:2) (10 mL) was added diphenylcyclohexyl phosphine
(0.086 g, 0.3 mmol) in acetonitrile (15 mL). The reaction mixture
was stirred for overnight at 50 °C. The colourless solution obtained
was filtered to avoid any impurity and cool down to room temper-
ature and evaporated slowly. After 5 days colourless plate like
crystals were obtained. A suitable crystal was chosen for X-ray dif-
fraction analysis. The rest of the product was collected by decanta-
tion of solvent and yield was found 62%. Anal. Calc. for
C55H67AgNO2P3: C, 67.70; H, 6.87; N, 1.43. Found: C, 67.66; H,
2.6. Preparation of [Ag(PPh2Cy)2(C3H6O)]ÁSbF6 (5)
The synthesis was followed by same procedure as described for
compound 4. Here diphenylcyclohexyl phosphine (0.057 g,
0.2 mmol) in CH2Cl2 was used instead of tricyclohexyl phosphine.
The clear solution obtained was left undisturbed for crystallization.
After the evaporation of solvent a transparent solid product was
obtained on the walls of evaporation dish. The resultant product
was re-dissolved in CH2Cl2/acetone (1:2) (15 mL) and kept for slow
evaporation; after 3 days colourless block crystals were obtained.
The crystalline product was carefully collected and weighed (Yield
56%). Anal. Calc. for C39H48AgF6OP2Sb: C, 49.87; H, 5.11. Found: C,
6.60; N, 1.76%. IR (t
, cmÀ1): 3412s, 3070m, 3050m, 2926vs,
2849s, 2344w, 2151w, 2107m, 1638m, 1617s, 1434vs, 1265m,
1183s, 998s, 847m, 743m, 617m, 510m. 1H NMR (CD2Cl2–d2;
ppm): 1.5–2.0, 2.5 (m, 11H, cyclohexyl protons), and 7.2–7.8 (m,
10H, phenyl protons). 13C NMR (CD2Cl2–d2; ppm): 24.77–35.58
(cyclohexyl carbons), 118 (CNÀ carbon atom) and 128.49–133.69
(phenyl carbons). 31P NMR (CD2Cl2–d2; ppm): 11.93 (s, sharp).
50.29; H, 5.24%. IR (t
, cmÀ1): 3550m, 3413s, 3007m, 3069m,
2931s, 2889m, 2859m, 2837m, 1695s,1637m, 1617s, 1436vs,
1229m, 1176m, 1097s, 885m, 749s, 668m, 505s. 1H NMR
(CD2Cl2–d2; ppm): 1.3–2.0, 2.6 (m, 11H, cyclohexyl protons), and
7.3–7.7 (m, 10H, phenyl protons). 13C NMR (CD2Cl2–d2; ppm):

M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
703
25.82–35.10 (cyclohexyl carbons), and 127.64–133.75 (phenyl car-
bons). 31P NMR (CD2Cl2–d2; ppm): 37.66(d. broad peak for phos-
phorous atom of tertiary phosphine).
2.7. Preparation of [Ag(PPhCy2)2]ÁSbF6ÁCHCl3 (6)
The synthesis of compound 6 was done by following the same
procedure as described for compound 4 and 5. To the solution of
AgSbF6 (0.035 g, 0.1 mmol) in acetonitrile (5 mL) was added to a
solution of dicyclohexylphenyl phosphine (0.055 g, 0.2 mmol) in
CH2Cl2 (10 mL). The reaction mixture was stirred for 30 min and
colourless solution obtained was filtered to avoid any impurity
and left undisturbed for crystallization. After 5 days colourless
crystals were obtained. A suitable crystal was chosen for single
crystal X-ray diffraction studies. The crystalline product was col-
lected carefully and weighed (Yield 83%). Anal. Calc. for
C37H55AgCl3F6P2Sb: C, 43.88; H, 5.43. Found: C, 43.95; H, 5.21%.
IR (t
, cmÀ1): 3550m, 3478s, 3412s, 3071w, 3051w, 2930vs,
2851s, 1637m, 1617s, 1449vs, 1270m, 1179s, 1001s, 847m,
747m, 659vs, 531m. 1H NMR (CD2Cl2–d2; ppm): 1.4–2.0, 2.5 (m,
22H, cyclohexyl protons), and 7.3–7.8 (m, 5H, phenyl protons).
13C NMR (CD2Cl2–d2; ppm): 25.79–32.47 (cyclohexyl carbons),
and 124.75–134.83 (phenyl carbons). 31P NMR (CD2Cl2–d2; ppm):
34.40, 37.48 (d. two peaks for phosphorous atom of tertiary
phosphine).
Fig. 1b. View along the c-axis of the crystal packing of complex 1.
lent to 20 water molecules of crystallization per unit cell, or 5
water molecules per molecule of complex (space group Pna21,
Z = 4). All the phenyl rings were made into regular hexagons.
Two phenyl rings (C1–C6 and C25–C30) showed positional disor-
der. They were split and the occupancies were initially refined.
The final values were close enough to 0.5/0.5 to be fixed as such
in the final cycles of refinement. Atoms in rings C1A–C6A and
C1B–C6B were refined anisotropically, however those for rings
C25A–C30A and C25B–C30B were only refined isotropically as
the anisotropic thermal parameters indicated important thermal
disorder. For compound 2 the PF6 anion was disordered. The F-
atoms were split (A and B parts) and the occupancies refined to
0.80(5)/0.20(5). The P–F distances were also refined with distances
restraints. Crystals of compound 5 crystallized with a disordered
molecule of acetone (occupancies 0.7/0.3). They were also twins
and this was corrected for using the TWINrotMAT routine available
in PLATON [50]; the final refined BASF factor was 0.15. Figs. 1–6 were
drawn using the programs PLATON and Mercury [51]. A summary of
crystal data and refinement details for compounds 1–6 are given in
Table 1, and selected bond lengths and angles are listed in Table 2.
2.8. X-ray Crystallography
The intensity data were collected at 173 K on either, a one circle
(/ scans) [47], or a two circle (
Diffraction System, using Mo K
x
a
and / scans) [48] Stoe Image Plate
graphite monochromated radia-
tion. The structures were solved by direct methods using the pro-
gram SHELXS-97 [49]. The refinement and all further calculations
were carried out using SHELXL-97 [49]. The H-atoms were included
in calculated positions and treated as riding atoms using SHELXL de-
fault parameters. The non-H atoms were refined anisotropically,
using weighted full-matrix least-squares on F2. In most cases mul-
ti-scan absorption corrections were applied using the MULscanABS
routine in PLATON [50]. For compound 1 a region of diffuse electron
density was treated with the SQUEEZE routine in PLATON [50]: 201 elec-
trons for a volume of 756.5 Å3, which was estimated to be equiva-
3. Results and discussions
3.1. Structural descriptions
3.1.1. Crystal structure of [Ag(PPh2Cy)3(CN)]Á5H2O (1)
The crystal structure of compound 1 is depicted in Fig. 1a. The
complex is isostructural with
a
considerable family of
[Ag(PR3)3(X)] arrays [5,40]; the anion being modelled as C-bonded
in this complex. The geometry around the silver(I) atom is tetrahe-
dral. Silver(I) atom being coordinated with three phosphorous
atoms of monodentate tertiary phosphine ligand molecules and
one carbon atom of the cyanide counter ion. Compound 1 crystal-
lizes with five lattice water molecules. The Ag–C bond distance is
2.187(7) Å which is longer than that found in similar silver(I) cya-
nide phosphine complexes [5,40]. The Ag–P bond distances are
2.5176(15), 2.5240(14), and 2.5226(12) Å. The P–Ag–P bond angles
range from 107.02(4)° to 107.74(5)° and P–Ag–C bond angles vary
from 109.54(18)° to 113.06(14)°. These bond angles values around
the central metal atom are close to the ideal tetrahedral angle
109.5°. The X-ray structure shows that cyclohexyl rings of the ter-
tiary phosphine ligand are present in the chair conformation.
Fig. 1a. View of the molecular structure of complex 1, with atom labelling scheme
and displacement ellipsoids drawn at the 50% probability level.

704
M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
Fig. 2a. A view of the molecular structure of complex 2, with selected atom
labelling scheme and displacement ellipsoids drawn at the 50% probability level
(the anion has been omitted for clarity).
Fig. 3. A view of the molecular structure of compound 3, with selected atom
labelling scheme and displacement ellipsoids drawn at the 50% probability level
(the anion and solvated molecule have been omitted for clarity).
3.1.3. Crystal structure of [Ag(PPh3)4)]ÁSbF6ÁCHCl3 (3)
The representative view of the crystal structure of complex 3 is
shown in Fig. 3. The compound 3 is a solvo polymorph of the com-
plex [Ag(PPh3)4)]ÁSbF6 [52]. In compound 3 the geometrical envi-
ronment around Ag(I) atom is again close to ideal tetrahedral.
The silver(I) atom is coordinated with four phosphorous atoms
of monodentate tertiary phosphine ligand molecules. The com-
pound 3 is solvated by one chloroform molecule as well. In the
hexafluoro antimonate counter ion, the Sb(V) atom is hexa-coordi-
nated with an octahedral geometrical environment.
The Ag–P bond distances vary from 2.6197(6) to 2.6282(7) Å.
These Ag–P bond distances are longer than that found in com-
pounds 1 and 2 and are shorter than those found in its polymor-
phic form [Ag(PPh3)4)].SbF6 [52]. The P–Ag–P bond angles range
from 108.01(2)° to 110.62(2)°; close to ideal tetrahedral angle
Fig. 2b. Panel showing the almost totally eclipsed arrangement of the two
dicyclohexylphenyl phosphine molecules coordinated with silver(I) centre in
complex 2.
3.1.2. Crystal structure of [Ag(PCy3)2]ÁPF6 (2)
The molecular structure of compound 2 is illustrated in Fig. 2a.
Here the geometry around the central silver(I) atom is linear. Atom
Ag1 is coordinated with two phosphorous atoms of monodentate
tertiary phosphine ligand molecules. The PFÀ6 anion is well sepa-
rated from the metal centre and does not show any coordination.
The phosphorous atom of the counter ion is hexa-coordinated
and an ideal octahedron is observed around phosphorous atom.
The P–Ag–P unit is planar [179.42(6)°], and the two phosphine li-
gand molecules are eclipsed; the cyclohexyl rings are again present
in chair conformations.
The molecular structure of compound 2 is highly symmetric and
C2 symmetry is observed here. The phosphorous atom of the coun-
ter ion is found to be disordered about the C2 axis. The Ag–P bond
distances are 2.3802(16) and 2.3779(16) Å, considerably shorter
than in compound 1. The Ag–P bond length differences found in
complexes 1 and 2, and other the silver(I) complexes reported here,
are attributed to the different crystallographic environments
around the central atom, the chemical composition of the tertiary
phosphine ligands and to some extent the nature of the counter
ions as well.
Fig. 4a. Ortep view of the molecular structure of 4, with selected atom labelling
scheme and displacement ellipsoids drawn at the 50% probability level (the anion
has been omitted for clarity).

M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
705
Fig. 4b. View showing the two tertiary phosphine ligand molecules present in a
partially eclipsed form in compound 4.
Fig. 6a. Representative view of molecular structure of compound 6 with selected
atom labelling scheme and displacement ellipsoids drawn at the 50% probability
level (the anion and solvated molecule have been omitted for clarity).
Fig. 5a. A view of the silver(I)phosphine moiety in compound 5, with partial
numbering scheme and displacement ellipsoids drawn at the 50% probability level
(the anion and the disordered solvated acetone molecule have been omitted for
clarity).
Fig. 6b. A view showing the partially eclipsed tertiary phosphine molecules
coordinated to the silver(I) atom in compound 6.
3.1.4. Crystal structure of [Ag(PCy3)2]ÁSbF6 (4)
The single crystal structure of the monomer complex 4 is illus-
trated in Fig. 4a. The geometrical environment around silver(I)
atom is linear and the central metal atom is coordinated with
two phosphorous atoms of monodentate tertiary phosphine ligand.
The molecular structure of compound 4 does not has C2-symmetry
unlike compound 2. However, the Sb(V) atom has octahedral
geometry as found in compound 3, and is coordinated with six
fluorine atoms. The P–Ag–P unit is linear, within experimental er-
ror, but slightly less linear found than that found in complex 2,
[175.37(3)° compared to 179.43(6)° for 2]. The tertiary phosphine
ligand molecules are eclipsed and the cyclohexyl rings are present
in chair conformations, as in complexes 1 and 2. The Ag–P1 and
Ag–P2 bond distances are 2.3767(10) and 2.3750(10) Å, respec-
tively. These Ag–P distances are shorter than those found in com-
plexes 1 and 3 but comparable with those in 2.
Fig. 5b. A view showing the molecular structure of compound
disordered solvated acetone molecule, and the SbF6 anion.
5 with the
109.5°. The P–Ag–P bond angle values different slightly to those
found in complex [Ag(PPh3)4)]ÁSbF6, which has the same geometri-
cal environment around the silver(I) atom and possesses crystallo-
graphic C3 symmetry [52].

706
M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
Table 1
Table 1 (continued)
Summery of crystal data and structure refinement details for compounds 1–6.
5
6
1
2
Z
2
8
Formula
M
C55H63AgNP3Á5(H2O)
1028.92
0.71073
173
orthorhombic
Pna 21
C36H66AgF6P3
813.67
0.71073
173
triclinic
C 2/m
Dcalc (Mg mÀ3
)
1.552
1.30
944
0.38 Â 0.34 Â 0.23
1.95–26.40
15848
1.561
1.39
4080
0.35 Â 0.15 Â 0.08
2.10–26.00
39451
l
(Mo K
a
) (mmÀ1
)
Wavelength (Å)
Temperature (K)
Crystal symmetry
Space group
a (Å)
F(0 0 0)
Crystal size (mm)
h Limits (°)
Measured
21.5982(15)
18.7015(13)
13.2231(8)
90
90
90
5341.1(6)
4
1.280
24.145(2)
17.8524(10)
9.7455(8)
90
105.671(9)
90
4044.6(5)
4
1.336
reflections
b (Å)
c (Å)
Unique reflections 7346 (0.0)
(Rint
Observed
reflections
8329 (0.069)
4648
)
a
(°)
5004
0.90
b (°)
c
(°)
Goodness of fit
0.87
V (Å3)
(GOF) on F2
Z
R1 (F), a[I > 2
wR2 (F2),
r
(I)]
0.0413
0.1006
0.0590
0.1501
Dcalc (Mg mÀ3
)
l
(Mo K
a
) (mmÀ1
)
0.51
0.67
b[I > 2
r(I)]
F(0 0 0)
Crystal size (mm)
h Limits (°)
2168
1712
P
P
a
R1
=
||Fo| À |Fc||/ |Fo|.
0.38 Â 0.35 Â 0.20
1.44–25.48
27065
0.30 Â 0.27 Â 0.11
2.10–25.85
16060
P
P
wR2 = [ w(F2o À Fc2)2/ wFo4]1/2
.
b
Measured
reflections
3.1.5. Crystal structure of [Ag(PPh2Cy)2(C3H6O)]ÁSbF6 (5)
Unique reflections 9418 (0.068)
(Rint
Observed
reflections
4065 (0.0614)
2533
The molecular structure of compound 5 is illustrated in Fig. 5a.
A highly disordered acetone molecule of crystallization coordinates
to the silver(I) atom, as shown in Fig. 5b. On the basis of this evi-
dence, we suggest a distorted trigonal planar geometry around
the silver(I) atom in complex 5. The central silver(I) atom is further
coordinated with two phosphorous atoms of monodentate tertiary
phosphine ligand molecules. In the non-coordinating SbFÀ6 counter
ion, the Sb(V) atom has an octahedral geometry as in compounds 3
and 4, and is coordinated with six fluorine atoms. The Ag–P1 and
Ag–P2 distances are 2.4166(18) and 2.4127(19) Å, respectively.
These bond distance values are longer than those in compounds
2 and 4, and shorter than those found in compounds 1 and 3.
The Ag–O bond distance is 2.664(16) Å, showing weak coordina-
tion of the disordered oxygen atom of the solvated acetone mole-
cule. The P–Ag–P bond angle is 158.91(6)° and O–Ag–P1 and O–
Ag–P2 bond angles are 95.2(4) and 105.6(4)°, respectively.
The P–Ag–P bond angle 158.91(6)° shows a very large deviation
from an ideal linear angle of 180° or an ideal trigonal planar angle
of 120°. These bond angles values provide additional evidence of
the weak coordination of the acetone molecule to the silver(I) me-
tal centre in 5. The cyclohexyl rings of the tertiary phosphine mol-
ecules are again present in chair conformations.
)
6473
0.88
Goodness-of-fit
0.94
(GOF) on F2
R1 (F), a[I > 2
wR2 (F2),
r
(I)]
0.0427
0.873
0.0521
0.1335
b[I > 2
r(I)]
3
4
Formula
C
72H60AgF6P4SbÁCHCl3
C36H66AgP2ÁF6Sb
M
1512.07
0.71073
173
904.45
Wavelength (Å)
Temperature (K)
Crystal symmetry
Space group
a (Å)
b (Å)
c (Å)
(°)
b (°)
0.71073
173
monoclinic
P21/n
14.3626(5)
19.1856(10)
15.9332(6)
90
114.936(3)
90
3981.2(3)
4
1.509
1.30
1856
monoclinic
P21/c
12.0120(5)
23.0780(6)
23.4887(10)
90
90.499(3)
90
6511.1(4)
4
1.542
1.00
3048
0.46 Â 0.32 Â 0.21
1.70–29.28
88111
a
c
(°)
V (Å3)
Z
Dcalc (Mg mÀ3
)
l
(Mo K
a
) (mmÀ1
)
F(0 0 0)
Crystal size (mm)
h Limits (°)
Measured
reflections
0.50 Â 0.27 Â 0.23
1.61–29.63
54225
3.1.6. Crystal structure of [Ag(PPhCy2)2]ÁSbF6ÁCHCl3 (6)
A perspective view of the molecular structure of compound 6 is
shown in Fig. 6a. The compound crystallizes in the orthorhombic
space group Pbca. The geometrical environment around the silver(I)
atom is linear within experimental error. Silver(I) atom is coordi-
nated with two phosphorous atoms of monodentate tertiary phos-
phine ligand molecules. The complex is solvated with one
chloroform molecule, as in compound 3. The Ag–P1 and Ag–P2 bond
distances are 2.3892(17) and 2.3859(17) Å, respectively. These bond
distances are more or less comparable with those in compounds 2
and 4 but shorter than those in compounds 1, 3 and 5. The P–Ag–P
bond angle is 173.33(6)°, smaller than that found in compounds 2
and 4. The bond angles found around the silver(I) atom indicate
quite large deviations from the ideal linear angle of 180°. The differ-
ences in bond length and bond angle values found in compounds 2, 4
and 6 are attributed to different chemical composition of the ligands
and to some extent to the counter ions as well.
Unique reflections 17605 (0.056)
(Rint
Observed
reflections
10766 (0.070)
8572
)
12913
0.99
Goodness of fit
1.05
(GOF) on F2
a
R1 (F), [I > 2
r
(I)]
0.0371
0.0798
0.0521
0.1326
wR2 (F2),
b[I > 2
r(I)]
5
C
6
Formula
36H42AgF6P2SbÁC3H6OÁF6Sb C36H54AgCl3P2ÁCHCl3ÁF6Sb
M
938.33
0.71073
173
1011.72
0.71073
173
Wavelength (Å)
Temperature (K)
Crystal symmetry
Space group
a (Å)
b (Å)
c (Å)
(°)
b (°)
(°)
V (Å3)
triclinic
orthorhombic
Pbca
ꢀ
P1
12.9403(15)
13.6997(17)
14.0354(17)
114.286(13)
96.745(14)
111.183(13)
2008.4(4)
16.3557(14)
29.989(3)
17.548(2)
90
90
90
a
3.2. 1H, 13C and 31P NMR spectroscopic studies
c
In the 1H NMR spectra of compounds 1, 2 and 4–6, the signals
8607.1(15)
due to the phenyl and cyclohexyl groups of the teriary phosphines

M. Altaf, H. Stoeckli-Evans / Polyhedron 29 (2010) 701–708
707
Table 2
presence of a singlet peak may be due to rapid intermolecular ex-
change of phosphine between different silver(I) atoms and free
phosphine ligand in solution [54]. In the 31P NMR of compounds
2 and 4, the resonances for the coordinated tricyclohexyl phos-
phine appear as two sets of intense doublet peaks at 37.71, 40.68
and 39.38, 42.31 ppm, respectively, about 30, 32 and 31, 34 ppm,
respectively, downfield compared to the uncomplexed tricy-
clohexyl phosphine (ꢀ8 ppm). The presence of two sets of doublet
peaks may be due to the presence of different types of silver(I)
complexes of tricyclohexyl phosphine in the solution. In the 31P
NMR of compound 5 the resonance for the coordinated diph-
enylcyclohexyl phosphine appears as an intense doublet peak at
37.66 ppm, about 31 ppm downfield compared to the uncom-
plexed dipenylcyclohexyl phosphine. In the 31P NMR of compound
6 the resonances for the coordinated dicyclhexylphenyl phosphine
appear as intense doublet peaks at 34.40 and 37.48 ppm, about 31,
and 33, 36 ppm, respectively, downfield compared to the uncom-
plexed dicyclhexylphenyl phosphine (ꢀ1 ppm). Silver(I) complexes
with (1:2 stoichiometric ratio) show well resolved pairs of dou-
blets, the resolution of signals for 1:2 species is due to 1J(P–Ag)
coupling. The 31P NMR spectral results are in agreement with the
previously reported silver(I) phosphine complexes [22–42,44,5].
The differences observed in the 31P NMR spectra of the silver(I)
complexes are attributed to the presence of different geometries
around the silver(I) atom in the solution form of these complexes.
Selected bond lengths (Å) and bond angles (°) for compounds 1–6.
Bond lengths (Å)
Bond angles (°)
1
Ag1–P1
Ag1–P2
Ag1–P3
Ag1–C55
2.5176(15)
2.5240(14)
2.5226(12)
2.202(5)
P1–Ag1–P2
P1–Ag1–P3
P2–Ag1–P3
P1–Ag1–C55
P2–Ag1–C55
P3–Ag1–C55
107.63(5)
107.02(4)
107.74(5)
109.54(18)
113.06(14)
111.60(4)
2
Ag1–P1
Ag1–P2
2.3802(16)
2.3779(16)
P1–Ag1–P2
179.42(6)
3
Ag1–P1
Ag1–P2
Ag1–P3
Ag1–P4
2.6236(6)
2.6261(7)
2.6197(6)
2.6282(7)
P1–Ag1–P2
P1–Ag1–P3
P1–Ag1–P4
P2–Ag1–P3
P2–Ag1–P4
P3–Ag1–P4
109.16(2)
109.39(2)
110.26(2)
110.62(2)
108.01(2)
109.40(2)
4
Ag1–P1
Ag1–P2
2.3767(10)
2.3750(10)
P1–Ag1–P2
175.37(3)
5
Ag1–P1
2.4166(18)
2.4127(19)
2.664(16)
P1–Ag1–P2
P1–Ag1–O2i
P2–Ag1–O2i
158.91(6)
95.2(4)
105.6(4)
Ag1–P2
Ag1–O2i
Symmetry codes:
(i) Àx + 1, Ày + 1, Àz.
4. Conclusions
6
Ag1–P1
Ag1–P2
2.3892(17)
2.3859(17)
P1–Ag1–P2
173.33(6)
The synthesis of silver(I) tertiary phosphine compounds reveals
that the geometry around the silver(I) atom is highly dependent on
the type of tertiary phosphine and to some extent on the molar ra-
tio of the reactants used. The tertiary phosphines having bulky
groups, like cyclohexyl, impose a linear geometry around the cen-
tral metal atom with silver(I) salts containing non-coordinating
counter ions (SbFÀ6 and PF6À), and trigonal planar to tetrahedral
geometry in the case of silver(I) salts with coordinating anions.
Whereas triphenylphosphine, with less bulky groups, imposes tet-
rahedral geometry around the central metal atom, with silver(I)
salts containing coordinating or non-coordinating anions. These
silver(I) phosphine precursors have been used successfully for
the preparation of mixed ligand coordination polymers with versa-
tile architectures [43].
are observed by their chemical shifts in the regions 7–8 and 1–
2.6 ppm, in CD2Cl2–d2 solution. No chemical shifts were observed
for the protons of the solvate molecules in the spectra of com-
pounds 1, 3, 5 and 6.
In the 13C NMR spectra of complex 1, the chemical shifts for the
phenyl and cyclohexyl carbons are observed in the range of
128.49–133.69 and 24.77–35.58 ppm, respectively, and a small
peak is observed at 118 ppm for the CNÀ group (carbon atom).
The 13C NMR spectra of complexes 2 and 4 are almost similar
and a set of peaks are observed in the range of 25.22–31.96 and
25.82–31.77 ppm (cyclohexyl carbons). The pattern of cyclohexyl
resonances is similar to those reported for a gold(I) complex [53].
In 13C NMR spectrum of complex 5, the chemical shifts for the phe-
nyl and cyclohexyl carbons are observed in the range of 127.64–
133.75 and 25.82–35.10 ppm, respectively. No extra signals were
observed for the solvate acetone molecule, present in the solid
state structure. The 13C NMR spectrum of complex 6 shows two
sets of peaks in the range of 25.79–32.47 and 124.75–
134.83 ppm for cyclohexyl and phenyl carbons, respectively. Again
no peak for the chloroform carbon atom was observed which, is
similar to the situation for complex 5. These complexes appear to
lose the solvated molecule of low boiling point solvents at ambient
conditions. These results are according to expectations and indi-
cate that the difference between the solution and solid state
structures.
Supplementary data
CCDC 741314, 741315, 741316, 741317, 741318 and 741319
contain the supplementary crystallographic data for compounds
1–6. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
This work was partially supported by the Swiss National Sci-
ence Foundation.
31P NMR spectra of silver(I) complexes 1–2 and 4–6 were re-
corded at room temperature. Naturally occurring isotopes of silver
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