Synthesis, spectral and structural studies of silver and gold(I) complexes containing some symmetrical diphosphine ligands

Article abstract of DOI:10.1016/j.jorganchem.2014.01.037

New silver(I) and gold(I) complexes [Ag₃(μ₂-CN) ₃(κ²-P,P-dppf)₂]_n· C₆H₁₂ (1), [Ag₄(μ₂-CN) ₄(κ¹-P,P-dtbpf)]_n (2), [Au ₂(μ₁-CN)₂(κ¹-P,P-dppf)] (3), [Au₂(μ₁-CN)₂(κ¹-P,P- dtbpf)] (4), [Ag₄(μ₃-CN)₂(μ₁- CN)₂(κ¹-P,P-dcpf)₂] (5), and [Au ₂(μ₁-CN)₂(κ¹-P,P-dcpf)] (6) were prepared starting with MCN (M = Ag, Au) and dppf/dtbpf/dcpf (dppf = 1,1′-bis(diphenylphosphino) ferrocene; dtbpf = 1,1′-bis(di-tert- butylphosphino) ferrocene; dcpf = 1,1′-bis(dicyclohexylphosphino) ferrocene) in 1:1 M ratio in DCM:MeOH (50:50 V/V) at room temperature. The resulting complexes have been characterized by elemental analysis, IR, ¹H & ³¹P NMR, ESI-MS and electronic absorption spectroscopy. Molecular structures for the complexes 1, 2, 5, and 6 were determined crystallographically. Complex 1 and 2 exist as an infinite one-dimensional (1D) polymeric chain constructed by [(μ₂-CN) Ag(μ₂-CN)Ag] fragments bridged via dppf/dtbpf ligands. The molecular structure of 5 reveals a centrosymmetric dimeric complex in which the two silver atoms are bonded to two dcpf ligands in κ¹ manner and two cyanide groups in a μ₃ bonding mode to generate nearly planar Ag₂(μ₃-CN)₂ framework, while complex 6 exists in open bridging mode containing Au atoms in ideal linear coordination defined by P,CN-donor sets.

Full text of DOI:10.1016/j.jorganchem.2014.01.037

Journal of Organometallic Chemistry 758 (2014) 9e18
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, spectral and structural studies of silver and gold(I)
complexes containing some symmetrical diphosphine ligands
,
a
a
b
c,
**
Manoj Trivedi a , Bhaskaran , Gurmeet Singh , Abhinav Kumar , Nigam P. Rath
*
a Department of Chemistry, University of Delhi, Delhi 110007, India
b Department of Chemistry, University of Lucknow, Lucknow 226007, India
c Department of Chemistry & Biochemistry and Centre for Nanoscience, University of Missouri-St. Louis, One University Boulevard, St. Louis,
MO 63121-4499, USA
a r t i c l e i n f o
a b s t r a c t
New silver(I) and gold(I) complexes [Ag3(m2-CN)3(k k
2-P,P-dppf)2]n$C6H12 (1), [Ag4(m2-CN)4(
1-P,P-dtbpf)]n
Article history:
Received 28 January 2014
Accepted 31 January 2014
(2), [Au2(m1-CN)2(
(5), and [Au2(m1-CN)2(
k k k
1-P,P-dppf)] (3), [Au2(m1-CN)2( 1-P,P-dtbpf)] (4), [Ag4(m3-CN)2(m1-CN)2( 1-P,P-dcpf)2]
k
1-P,P-dcpf)] (6) were prepared starting with MCN (M ¼ Ag, Au) and dppf/dtbpf/
dcpf (dppf ¼ 1,10-bis(diphenylphosphino) ferrocene; dtbpf ¼ 1,10-bis(di-tert-butylphosphino) ferrocene;
dcpf ¼ 1,10-bis(dicyclohexylphosphino) ferrocene) in 1:1 M ratio in DCM:MeOH (50:50 V/V) at room
temperature. The resulting complexes have been characterized by elemental analysis, IR, 1H & 31P NMR,
ESI-MS and electronic absorption spectroscopy. Molecular structures for the complexes 1, 2, 5, and 6
were determined crystallographically. Complex 1 and 2 exist as an infinite one-dimensional (1D) poly-
meric chain constructed by [(m2-CN)Ag(m2-CN)Ag] fragments bridged via dppf/dtbpf ligands. The mo-
lecular structure of 5 reveals a centrosymmetric dimeric complex in which the two silver atoms are
bonded to two dcpf ligands in k1 manner and two cyanide groups in a m3 bonding mode to generate
nearly planar Ag2(m3-CN)2 framework, while complex 6 exists in open bridging mode containing Au
atoms in ideal linear coordination defined by P,CN-donor sets.
Keywords:
Diphosphine
Silver complex
Gold complex
X-ray
Weak interaction
Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction
Agþ, revealed a large variety of mono-, di- and polynuclear struc-
tures that can be assembled from dppf [3,28,29,50]. The structural
Ferrocene-based phosphines have emerged as one of the most
powerful classes of ligands in chiral and achiral catalysis [1e10].
Although there are many different types of ferrocenyl diphos-
phines, the most common are 1,10-bis(diphenylphosphino) ferro-
cene (dppf) [11e25] and 1,10-bis(di-tert-butylphosphino) ferrocene
(dtbpf) [19,26]. These ligands have significant advantages over
other diphosphines which contain alkyl, rather than metallocene,
backbones [27]. There are several reports available on dppf [28e36]
and a few on dtbpf [19,26,37e42] and dcpf [27,43]. Compared to the
significant amount of work on dppf itself, dtbpf and dcpf have
received surprisingly little attention. Recently another incentive to
study silver and gold complexes of bis(phosphino)ferrocenes, are of
particular interest on account of the potential of their compounds
as biologically active agents [44], catalysts [45] and luminescent
materials [46e49]. Previous work on the coinage metals, especially
outcome is generally hard to predict due to the numerous per-
mutations arising from the flexible metal geometry
(linear
(unidentate 4 bridging 4 chelating) and coordination state of the
supporting anion (halide, pseudohalide etc.)
4 trigonal planar 4 tetrahedral), dppf bonding
(uncoordinated 4 terminal 4 bridging 4 chelating 4 capping).
Our current understanding on [AgX(dppf)]n [29e31] and
[AuX(dppf)]n [51e55] complexes is that they generally prefer
dimeric and polymeric structures. Several variations are known
depending on the interaction of the dppf and Xꢀ but few reports are
published till date related to dtbpf/dcpf and Xꢀ. The dppf based
complexes are commonly prepared from direct addition of MX to
dppf using stoichiometric conditions of 1:1. During the course of
our current study concerning interaction of MCN (M ¼ Ag, Au) with
dppf/dtbpf/dcpf, and to assist our understanding of the Ag(I) and
Au(I) species present in solid and solution state, herein we report
the synthesis, spectroscopic characterization, and structural studies
* Corresponding author. Tel.: þ91 (0) 9811730475.
of representative silver(I) and gold(I) complexes [Ag3(m2-CN)3(k2
P,P-dppf)2]n$C6H12 (1), [Ag4(m2-CN)4(
1-P,P-dtbpf)]n (2)], [Ag4(m3
-
-
** Corresponding author. Tel.: þ1 314 516 5333.
E-mail addresses: manojtri@gmail.com (M. Trivedi), rathn@umsl.edu (N.P. Rath).
k
http://dx.doi.org/10.1016/j.jorganchem.2014.01.037
0022-328X/Ó 2014 Elsevier B.V. All rights reserved.

10
M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
CN)2(m1-CN)2(
respectively.
k
1-P,P-dcpf)2] (5) and [Au2(m1-CN)2(
k
1-P,P-dcpf)] (6),
of the complexes was also obtained from ESI-MS. The positions of
different peaks and overall fragmentation patterns in the ESI-MS of
the respective complexes are consistent with their formulations.
Infrared spectra of all the complexes exhibited characteristic band
2. Results and discussion
corresponding to nChN at 2136 cmꢀ1, 2114 cmꢀ1, 2138 cmꢀ1
,
2151 cmꢀ1, 2129 cmꢀ1 and 2147 cmꢀ1, respectively. However, only
one nChN band agrees well with the presence of only one type of
cyanide bridge between silver and gold (I) atom [58e62] which is in
accordance with those reported in literature for bridging pseudo-
halide groups [30,56e60]. The 1H NMR spectra of all the complexes
2.1. Synthesis
The reactions of silver(I) cyanide with 1,10-bis(diphenylphos-
phino)ferrocene (dppf)/1,10-bis(di-tert-butylphosphino) ferrocene
(dtbpf)/1,10-bis(dicyclohexylphosphino) ferrocene (dcpf) ligand in a
dichloromethane:methanol mixture (50:50 V/V) in equimolar ratio
under refluxing with stirring in dark afforded the infinite one
dimensional polymeric chains [Ag3(m2-CN)3(
(1), [Ag4(m2-CN)4(
1-P,P-dtbpf)]n (2) and centrosymmetric dimeric
complex [Ag4(m3-CN)2(m1-CN)2(
1-P,P-dcpf)2] (5), respectively
show two singlets in the range of
to
5-C5H4 protons of the dppf, dtbpf and dcpf ligand. The phenyl
ring protons of dppf ligand in complex 1 and 3 resonated as a
multiplets at
¼ 8.10e7.30 ppm. The tert-butyl protons in complex
2 and 4 were observed as two overlapping doublets at
d
¼ 4.43e4.10 ppm corresponding
h
k
2-P,P-dppf)2]n$C6H12
d
k
d
¼ 1.21 ppm.
k
The cyclohexyl proton in complex 5 and 6 were observed as
(Schemes 1e3), while the reactions of gold(I) cyanide with dppf/
dtbpf/dcpf under the similar condition mention above in presence
multiplet at 2.71e1.22 ppm. The 31P{1H} NMR spectra for the
complex 1, 2, and 5 resonated at
as a broad singlets, while the other complexes 3, 4, and 6 showed a
single sharp resonance at 31.4 (3), 64.9 (4), and 41.6 ppm (6),
d
ꢀ2.559 (1), 41.54 (2), and 56.6 (5)
of light led to the isolation of binuclear gold(I) complexes [Au2(m1
-
-
CN)2(
k
1-P,P-dppf)] (3), [Au2(m1-CN)2(
k
1-P,P-dtbpf)] (4) and [Au2(m1
1-P,P-dcpf)] (6) (Schemes 1e3).
d
CN)2(
k
respectively for dppf, dtbpf and dcpf ligands indicating that all the
phosphorus atoms were chemically equivalent (See F-1eF-3,
Supporting material). These chemical shifts are within the accepted
range and are comparable to that of the silver(I) and gold(I) com-
2.2. Characterization
All the complexes are air-stable, non-hygroscopic solids and
soluble in dimethylformamide, dimethylsulfoxide and halogenated
solvents but insoluble in petroleum ether and diethyl ether. The
complexes were fully characterized by IR, UVeVis, 1H & 31P NMR
and ESI-MS. Analytical data of the complexes confirmed well to
their respective formulations. More information about composition
plexes
containing
dppf,
dtbpf
and
dcpf
ligands
[27,28,30,32,33,35,37e43,61]. All the complexes exhibited two
bands at 460e478 nm and 265e266 nm in dichloromethane so-
lution (See F-4, Supporting material). The lower-energy band in the
range of 460e478 nm can be assigned to the ded transition
Scheme 1. Synthetic Routes for 1 and 3.

M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
11
Scheme 2. Synthetic Routes for 2 and 4.
assigned to the 1E1g ) 1A1g of ferrocenyl moiety. The higher-energy
band at 265e275 nm has been assigned to intraligand charge
transfer.
C(36)#1 ¼ 2.045(4) A, N(1)eC(36) ¼ 1.114(5) A]. The bond angles at
Ag1 [N(1)eAg(1)eP(1), C(35)eAg(1)eN(1), C(35)eAg(1)eP(2),
N(1)eAg(1)eP(2), C(35)eAg(1)eP(1), and P(2)eAg(1)eP(1)] lie in
the range of 98.01(9)ꢁe117.00(8)ꢁ. The AgeP bonds are coplanar
with the plane defined by the [AgeCNeAgeCNe]n zigzag back-
bone. The mean AgeP, AgeC(CN) and Ag1eN(CN) bond lengths
ꢀ
ꢀ
2.3. Molecular structure determination
ꢀ
ꢀ
ꢀ
Details about the data collection, solution and refinement are
presented in Table 1. The molecular structures for the complex 1, 2,
5 and 6 with atomic numbering scheme are presented in Figs. 1e4
and important geometrical and hydrogen bond parameters are
presented in Tables 2 and 3, respectively. Complexes 1, 2, 5 and 6
crystallized in triclinic and monoclinic system with P-1, C2/c, C2/c
and P21/c space groups, respectively. The asymmetric unit of the
(2.4727(8) A vs. 2.0966(7) A vs. 2.2365(7) A) are longer than those of
the [{Ag2(CN)2(dppmapy)}$0.5CHCl3]n (where dppmapy: N-diphe-
nylphosphanylmethyl-4-aminopyridine)
2.062(9) A vs. 2.217(5) A) [57] but nearly similar as compared to
[P(o-tol)3Ag2(CN)2(py)]n (2.451(2) A vs. 2.3105 A vs. 2.375(3) A; o-
tol ¼ o-toluene) [62]. Complex 1 consists of [(m2-CN)Ag(m2-CN)Ag]
fragments bridged by the dppf ligands, forming an infinite 1D
polymeric chain extending along the b axis (See F-5, Supporting
material). The two substituted Cp rings in the dppf ligand in com-
ꢀ
(2.3880(19)
A
vs.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
complex 1 and 2 have one [Ag2(m2-CN)2Ag1(
k
2-P,P-dppf)]$0.5C6H12
and [Ag(m1-CN)Ag(m2-CN)(
k
1-P-0.5dtbpf)] molecules which propa-
gated linearly to give an infinite one-dimensional zigzag and helical
polymeric chains, while the molecular structure of 5 revealed a
centrosymmetrical dimeric unit in which, the two dcpf ligands in k1
manner and two cyanide groups in m3 modes bridging the two
silver atoms. The asymmetric unit of 6 comprises of binuclear
(C34H52FeP2)(AuCN)2 molecule which is located at the inversion
centre. As shown in Fig. 1, the two Ag atoms in complex 1 show
different coordination geometries. The distorted tetrahedral coor-
dination of Ag1 is achieved by two P atoms of the chelating dppf
plex
1
adopt the antiperiplanar staggered conformation
[Cp(centroid)/Fe/Cp(centroid) ¼ 178.06ꢁ], which determines the
conformational chirality of the Cp2Fe fragment.
In complex 2, the two Ag atoms are also in different coordina-
tion geometries (Fig. 2). Ag1 is disordered (disorder fraction is
<10%) and almost in distorted trigonal planar environment, with
the two cyanide ligands [Ag(1)eN(1)
ꢀ
¼
2.295(9) A, Ag(1)e
ꢀ
N(2) ¼ 2.328(10) A] in m2 mode and one phosphorous atom of dtbpf
ligand in k1-manner [Ag(1)eP(1) ¼ 2.4025(19) A]. The other Ag2 is
ꢀ
ꢀ
ꢀ
ligand [Ag(1)eP(1) ¼ 2.4865(8) A, Ag(1)eP(2) ¼ 2.4588(8) A] and
linearly coordinated by two C atoms from two cyanides [Ag(2)e
two cyanide ligands [Ag(1)eN(1)
¼
2.313(3) A, Ag(1)e
C(14)
¼
2.043(12) A, Ag(2)eC(15)#2
¼
2.093(10) A, N(2)e
ꢀ
ꢀ
ꢀ
#1
ꢀ
ꢀ
ꢀ
ꢀ
C(35) ¼ 2.200(14) A, Ag(1)eN(35) ¼ 2.160(10) A]. The bridging
C(15) ¼ 1.071(13) A, N(1)eC(14) ¼ 1.112(14) A]. The bond angles at
Ag1 [N(1)eAg(1)eN(2), N(2)eAg(1)eP(1), N(1)eAg(1)eP(1)] lie in
the range of 106.6(4)ꢁ-123.4(3)ꢁ, respectively. The AgeP bonds are
nearly perpendicular with the plane defined by the [AgeCNeAge
cyanide group around Ag1 in 1 is disordered across an inversion
centre. The other Ag2 is linearly coordinated by two C atoms from
ꢀ
two
cyanides
[Ag(2)eC(36)
¼
2.045(4)
A,
Ag(2)e

12
M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
Scheme 3. Synthetic Routes for 5 and 6.
CNe]n helical backbone. The mean AgeP, AgeC(CN) and Ag1e
fragments bridged by the dtbpf ligands in complex 2, resulting in
the formation of an infinite 1D polymeric helical chain extending
along the b axis (See F-6, Supporting material). The two substituted
Cp rings in the dtbpf ligand in 2 adopt the antiperiplanar staggered
conformation [Cp(centroid)/Fe/Cp(centroid) ¼ 174.38ꢁ].
ꢀ
ꢀ
N(CN) bond lengths are (2.4025(19)
2.312(10) A). These distances are also longer than those of the
A vs. 2.068(11) A vs.
ꢀ
[{Ag2(CN)2(dppmapy)}$0.5CHCl3]n but nearly similar to [P(o-tol)3
-
Ag2(CN)2(py)]n as observed above. The [(m2-CN)Ag(m2-CN)Ag]
Table 1
Crystallographic data for 1, 2, 5 and 6.
1
2
5
6
Empirical Formula
FW
C77H68N3P4Ag3Fe2
1594.53
Triclinic
P-1
10.0301(4)
13.5120(5)
14.0645(5)
117.245(4)
97.598(3)
96.137(3)
1649.17(13)
1
C30H44N4P2Ag4Fe
1009.96
Monoclinic
C2/c
20.2238(10)
10.4092(4)
16.8208(8)
90.00
102.682(5)
90.00
3454.6(3)
4
C72H104N4P4Ag4Fe2
1692.65
Monoclinic
C2/c
21.2347(6)
14.2274(5)
28.0768(10)
90.00
106.418(3)
90.00
8136.5(5)
4
C36H52N2P2Au2Fe
1024.52
Monoclinic
P21/c
14.4052(3)
9.5273(2)
26.8320(5)
90.00
103.225(2)
90.00
3584.83(13)
4
Crystal system
Space group
ꢀ
a, A
ꢀ
b, A
ꢀ
c, A
a
, deg
, deg
b
g
, deg
3
ꢀ
V, A
Z
dcalc, g cmꢀ3
1.605
1.448
1.942
2.756
1.382
1.408
1.898
8.681
m
, mmꢀ1
T, K
293 (2)
0.0362
0.0294
0.0827
293 (2)
0.0615
0.0552
150(2)
0.0806
0.0720
0.2322
150(2)
0.0429
0.0379
0.0927
R1 all
R1 [I > 2
wR2
s(I)]
0.1405
wR2 [I > 2
s
(I)]
0.0813
0.1358
0.2256
0.0898
GoF
1.090
1.078
1.112
1.137

M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
13
Fig. 1. Molecular structure for 1.
Fig. 2. Molecular structure for 2.

14
M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
antiperiplanar
Fe/Cp(centroid)
conformational chirality of the Cp2Fe fragment.
staggered
¼
conformation
[Cp(centroid)/
171.09ꢁe177.16ꢁ], which determines the
In complex 6, the iron atom lies on a symmetry centre. The dcpf
ligand coordinates the gold centres in an open bridging mode
(Fig. 4). The P1eAu1eC35 and P2eAu2eC36 bond angles are
178.9(3)ꢁand 176.2(2)ꢁ, which is very close to the linear value. The
ꢀ
AueP and AueC bond distances are 2.2634(18)e2.2674(17) A and
ꢀ
1.989(8)e1.997(8) A, respectively, which are comparable with other
gold derivatives with ferrocenyl diphosphines [51e55]. The cyclo-
ꢀ
pentadienyl ring is planar and located 1661e1.663 A from the iron
atom; by symmetry, both Cp rings are antiperiplanar staggered
confirmation [Cp(centroid)/Fe/Cp(centroid)
¼
177.08ꢁ]. The
ꢀ
shortest FeeAu interactions [4.148e4.224 A] are present in com-
plex 6 (See F-7, Supporting material), and there is no short Au/Au
ꢀ
contact (none <8.387 A). Crystal packing in complex 1 and 6 are
stabilised by inter- and intra-molecular CeH/X (X ¼ N), CeH/
and interactions, while in complex 2, only inter- and intra-
molecular CeH/ and intra interactions are present. An
interesting feature of the crystal packing in complex 1 is single
helical motif resulting from inter and intra interactions (See
F-8, supporting material). The contact distances for in-
p
p
/p
p
p/p
p/p
p
/p
ꢀ
teractions are in the range of 3.211e3.378 A. These distances are
within the range reported previously [63]. Inter and intra-
molecular CeH/N and CeH/
plex 1 and 6, while in complex 2, only CeH/
present. The contact distances for CeH/N and CeH/
teractions are in the range of 2.538e2.608 A and 2.650e2.855 A,
respectively. These distances are within the range reported by other
workers [64,65]. The self-assembling of 1, 5 and 6 contains solvent
accessible voids in the crystal 3D lattice, while no solvent accessible
voids are present in the crystal 3D lattice of complex 2 (See F-9e11,
Supporting material).
p
interactions are present in com-
interactions are
in-
p
p
ꢀ
ꢀ
2.4. Electrochemistry
The electrochemical properties of our new complexes were
investigated by cyclic voltammetry in CH2Cl2 at room temperature
(r.t.) and the redox data are gathered in Table 4. Cyclic voltammo-
grams (Fig. 5) of the complexes 1, 2 and 5 exhibits two reversible
oxidation peak at 0.19 Ve0.77 V corresponding to Fcþ/0, and
0.76 Ve1.26 V, which are due to AgIeAg0 redox change of the silver-
based units. We have also investigated the redox behaviour of the
gold complexes 3, 4, and 6. All show two reversible oxidation peaks
at 0.21 Ve0.25 V and 0.81 Ve1.20 V, which could be tentatively
assigned as arising from Fcþ/0, and AuIeAu0 oxidation.
Fig. 3. Molecular structure for 5.
In complex 5, the two Ag atoms have different coordination
geometries (Fig. 3). The distorted tetrahedral coordination of Ag1
is achieved by two P atoms of the chelating dcpf ligand [Ag(1)e
ꢀ
ꢀ
P(1) ¼ 2.443(2) A, Ag(1)eP(2) ¼ 2.442(2) A] and two cyanide
#1
ꢀ
ꢀ
ligands [Ag(1)eN(1) ¼ 2.510(7) A, Ag(1)eN(1) ¼ 2.497(7) A].
The other Ag2 is linearly coordinated by one C and one N atoms
ꢀ
from two cyanides [Ag(2)eC(35)
¼
2.053(8) A, Ag(2)e
1.100(15) A, N(1)e
ꢀ
ꢀ
N(2)
¼
2.080(12) A, C(36)eN(2)
¼
ꢁ
ꢀ
C(35) ¼ 1.136(11) A]. The P1eAgeP2 bite angle for 5 is 130.00(7) ,
of the chelating dcpf is very close to the expected value for this
coordination. The other coordination bond angles in 5 are rather
distorted [P(1)eAg(1)eN(1)
¼
103.79(16), P(2)eAg(1)e
N(1) ¼ 109.24(16), P(1)eAg(1)eN(1)#1 ¼ 110.72(16), P(2)eAg(1)e
N(1)#1 ¼ 103.02(16), N(1)#1eAg(1)eN(1) ¼ 94.5(2)], because of
the four-membered Ag2N2 ring and of the steric hindrance of the
dcpf ligand. The two AgeN bond lengths are asymmetrical,
ꢀ
[2.497(7) and 2.510(7) A]. The plane of the bridge defined in 5 by
the two silver centres and the two nitrogen atoms is almost
perpendicular to the plane defined by the four phosphorus
ꢀ
atoms. The Ag/Ag distance in 5 is of 3.398(2) A. The bond dis-
tances and angles in 5 agree with those reported bis(dicyclo-
hexylphosphino) ferrocene complexes [27,43]. The two
substituted Cp rings in the dcpf ligand in
5
adopt the
Fig. 4. Molecular structure for 6.

M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
15
Table 2
Selected bond lengths (A), and bond angles ( ) for 1, 2, 5 and 6.
ꢁ
ꢀ
1
2
5
6
Ag(1)eC(35)
2.200(14)
2.160(10)
2.313(3)
2.4588(8)
2.4865(8)
2.045(4)
1.114(5)
1.833(3)
1.821(4)
1.820(3)
1.831(3)
117.0(19)
111.00(3)
109.83(9)
112.00(3)
98.01(9)
108.84(3)
180.00(3)
Ag(2)eC(14)
2.043(12)
2.093(10)
2.295(9)
2.328(10)
2.4025(19)
1.112(14)
1.071(13)
1.893(7)
1.882(7)
106.6(4)
123.4(3)
121.1(2)
178.1(5)
171.9(11)
C(36)eN(2)
Ag(1)eP(1)
Ag(1)eP(2)
1.100(15)
2.443(2)
2.442(2)
2.510(7)
2.497(7)
2.053(8)
2.080(12)
1.850(8)
1.854(19)
1.852(8)
1.862(8)
1.136(11)
130.00(7)
103.79(16)
109.24(16)
103.02(16)
178.50(4)
85.5(2)
Au(2)eP(2)
Au(1)eP(1)
Au(2)eC(36)
Au(1)eC(35)
P(1)eC(17)
P(1)eC(11)
P(2)eC(29)
P(2)eC(23)
N(2)eC(36)
2.2634(18)
Ag(1)eN(35)#1
Ag(1)eN(1)
Ag(2)eC(15)#2
Ag(1)eN(1)
2.2674(17)
1.997(8)
1.989(8)
1.835(6)
1.849(6)
1.849(6)
1.834(7)
1.135(10)
1.150(10)
176.5(8)
177.3(8)
176.2(2)
178.9(3)
Ag(1)eP(2)
Ag(1)eP(1)
Ag(2)eC(36)
N(1)eC(36)
P(1)eC(17)
P(1)eC(11)
P(2)eC(23)
P(2)eC(29)
C(35)eAg(1)eN(1)
C(35)eAg(1)eP(2)
N(1)eAg(1)eP(2)
C(35)eAg(1)eP(1)
N(1)eAg(1)eP(1)
P(2)eAg(1)eP(1)
C(36)#1eAg(2)eC(36)
Ag(1)eN(2)
Ag(1)eP(1)
N(1)eC(14)
N(2)eC(15)
P(1)eC(6)
P(1)eC(10)
N(1)eAg(1)eN(2)
N(1)eAg(1)eP(1)
N(2)eAg(1)eP(1)
C(14)eAg(2)eC(15)#2
N(1)eC(14)eAg(2)
Ag(1)eN(1)
Ag(1)eN(1)#1
Ag(2)eC(35)
Ag(2)eN(2)
P(2)eC(23)
P(2)eC(29)
P(1)eC(11)
P(1)eC(17)
N(1)eC(35)
P(1)eAg(1)eP(2)
P(1)eAg(1)eN(1)
P(2)eAg(1)eN(1)
P(2)eAg(1)eN(1)#1
C(35)eAg(2)eN(2)
Ag(1)#1eN(1)eAg(1)
N(1)eC(35)eAg(2)
C(36)eN(2)eAg(2)
C(35)eN(1)
N(1)eC(35)eAu(1)
N(2)eC(36)eAu(2)
C(36)eAu(2)eP(2)
C(35)eAu(1)eP(1)
178.7(8)
175.5(14)
3. Conclusion
complexes were obtained on a Perkin Elmer Lambda-35 spec-
trometer. 1H, and 31P{1H} NMR spectra were recorded on a JEOL AL-
400 FTNMR instrument using tetramethylsilane and phosphoric
acid as an internal standard, respectively. Mass spectral data were
recorded using a Waters micromass LCT Mass Spectrometer/Data
system. Electrochemical properties of the complexes were
measured by cyclic voltammetry using platinum as working elec-
trode and the supporting electrolyte was [NBu4]ClO4 (0.1 M) in
dichloromethane solution of 0.001 M of complex versus Ag/AgCl at
The work presented here concerns the reaction chemistry of
silver(I) and gold(I) cyanide with dppf/dtbpf/dcpf ligands, that re-
sults in the formation of two infinite one dimensional silver(I)
polymeric chains [Ag3(m2-CN)3(
CN)4(
1-P,P-dtbpf)]n (2), one centrosymmetric dimeric complex
[Ag4(m3-CN)2(m1-CN)2(
1-P,P-dcpf)2] (5) and three binuclear gold(I)
complexes [Au2(m1-CN)2(
1-P,P-dppf)] (3), [Au2(m1-CN)2( 1-P,P-
dtbpf)] (4) and [Au2(m1-CN)2(
1-P,P-dcpf)] (6), respectively. This
k -
2-P,P-dppf)2]n$C6H12 (1); [Ag4(m2
k
k
k
k
k
a scan rate of 100 mV sꢀ1
.
result revealed that dppf/dtbpf/dcpf could be excellent ligands, and
its chemistry related to metal cyanide is anticipated to be as rich as
those of the other diphosphines. Further studies in this respect are
underway in our laboratory.
4.2. Synthesis
4.2.1. [Ag3(m2-CN)3(k
2-P,P-dppf)2]n$C6H12 (1)
1,10-Bis(diphenylphosphino)ferrocene (dppf) (0.554 g,1.0 mmol)
was added to a solution of silver(I) cyanide (0.134 g, 1.0 mmol) in
30 mL CH3OH:CH2Cl2 (50:50 V/V) mixture in dark at room tem-
perature. The resultant suspension was refluxed with stirring under
nitrogen atmosphere for 24 h. Slowly, the colour of the solution
changed from light orange to dark yellowish orange. The resulting
solution was evaporated to dryness to give a yellowish orange solid
which was then extracted with dichloromethane (20 mL). The
addition of cyclohexane (250 mL) to this solution led to yellowish
orange needle shaped diffraction quality crystals. These were
separated and washed with hexane and dried. Yield: (1.116 g, 70%).
Anal. Calc. for C77H68N3P4Ag3Fe2: C, 57.97; H, 4.27; N, 2.63. Found:
4. Experimental
4.1. Materials and physical measurements
All the synthetic manipulations were performed under nitrogen
atmosphere. The solvents were purified and dried before use by
adopting the standard procedures [66]. Silver(I) cyanide, 1,10-bis(-
diphenylphosphino) ferrocene (Aldrich), gold(I) cyanide (Aldrich),
1,10-bis(dicyclohexylphosphino)ferrocene (Aldrich) and 1,10-bis(di-
tert-butylphosphino) ferrocene (Aldrich) were used as received.
Elemental analyses were performed on a Carlo Erba Model EA-1108
elemental analyzer and data of C, H and N is within ꢂ0.4% of
calculated values. Infrared spectra were recorded using Perkine
Elmer FT-IR spectrophotometer. Electronic spectra of the
C, 58.12; H, 4.45; N, 2.68. IR (cmꢀ1, KBr):
n
¼ 3440, 3052, 2926,
2136(CN), 1958, 1892, 1650, 1581, 1478, 1430, 1310, 1165, 1158, 1094,
1087, 1030, 898, 818, 742, 696, 630, 495. 1H NMR (
d ppm, 400 MHz,
Table 4
Table 3
Electrochemical data for 1e6 in dichloromethane solution/0.1 M [NBu4]ClO4 at
Hydrogen bond parameters for 1 and 6.
298 K.
ꢀ
ꢀ
DeH/AeX
d H/A A
D D/A A
q
DeH/Aꢁ
Complex
Oxidationa Epa
V vs. SCE
/
Reductionb Epc
/
V vs. SCE
1
C(9)eH(9)/N(1)a
C(24)eH(24)/N(1)
6
2.54
2.61
3.416(5)
3.499(5)
157
160
[Ag3(m2-CN)3(
[Ag4(m2-CN)4(
k
k
2-P,P-dppf)2]n.C6H12 (1)
1-P,P-dtbpf)]n (2)
0.77, 1.26
0.19, 0.76
0.22, 0.95
0.25, 1.20
0.27, 0.89
0.21, 0.81
0.91, ꢀ0.13
0.77, ꢀ0.46
ꢀ0.50, ꢀ1.13
ꢀ0.34, ꢀ1.03
0.77, ꢀ0.85
ꢀ0.18, 0.92
[Au2(m1-CN)2(
[Au2(m1-CN)2(
k
1-P,P-dppf)] (3)
1-P,P-dtbpf)] (4)
C(11)eH(11)/N(2)b
C(29)eH(29)/N(1)c
2.53
2.49
3.440(4)
3.420(5)
154
157
k
[Ag4(m3-CN)2(m1-CN)2(k
1-P,P-dcpf)2] (5)
Symmetry equivalents.
Au2(m1-CN)2(k
1-P,P-dcpf)] (6)
a
1 þ x, y, z.
a
b
Epa is the anodic peak potential of the reversible oxidation wave.
Epc is the cathodic peak potential of the reversible oxidation wave.
ꢀx, 1 ꢀ y, ꢀz.
b
c
1 ꢀ x, 1 ꢀ y, ꢀz.

16
M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
Fig. 5. Cyclic voltammograms for the complexes 1e6 in CH2Cl2/0.1 M [NBu4]ClO4 at 100 mV/sꢀ1 scan rate.
CDCl3, 298 K): 8.05e7.30 (m, 40H, Ph), 4.32(s, 8H, C5H4), 4.20 (s, 8H,
ppm, 400 MHz, CDCl3, 298 K): 8.10e7.30 (m, 40H, Ph), 4.35(s, 8H,
C5H4).
31P{1H}:
d
ꢀ2.56
(sbr).
UV/Vis:
lmax
(ε
C5H4), 4.10 (s, 8H, C5H4). 31P{1H}:
d 31.4 (s) (Sharp). UV/Vis: lmax (ε
[dm3 molꢀ1 cmꢀ1]) ¼ 266 (10,548), 460 (24,204). ESI-MS (m/z):
[dm3 molꢀ1 cmꢀ1]) ¼ 275 (18,904), 450 (30,337). ESI-MS (m/z):
1594.1(Mþ).
1000.8 (Mþ).
4.2.2. [Ag4(m2-CN)4(
k
1-P,P-dtbpf)]n (2)
4.2.4. [Au2(m1-CN)2(k
1-P,P-dtbpf)] (4)
1,10-Bis(di-tert-butylphosphino) ferrocene (dtbpf) (0.474 g,
1.0 mmol) was added to a solution of silver(I) cyanide (0.134 g,
1.0 mmol) in 30 mL CH3OH:CH2Cl2 (50:50 V/V) mixture in dark at
room temperature. The resultant suspension was refluxed with
stirring under nitrogen atmosphere for 24 h. Slowly, the colour of
the solution changed from light orange to dark yellowish red colour.
The resulting solution was evaporated to dryness to give a yellowish
red solid which was then extracted with dichloromethane (20 mL).
The addition of hexane (100 mL) to this solution led to yellowish red
rod shaped diffraction quality crystals. These were separated and
washed with hexane and dried. Yield: (0.808 g, 80%). Anal. Calc. for
1,10-Bis(di-tert-butylphosphino) ferrocene (dtbpf) (0.474 g,
1.0 mmol) was added to a solution of gold(I) cyanide (0.223 g,
1.0 mmol) in 30 mL CH3OH:CH2Cl2 (50:50 V/V) mixture at room
temperature. The resultant suspension was refluxed with stirring
under nitrogen atmosphere for 24 h. Slowly, the colour of the so-
lution changed from light yellowish orange to dark yellowish red
colour. The resulting solution was evaporated to dryness to give a
yellowish red solid which were separated and washed with hexane
and dried. Yield: (0.598 g, 65%). Anal. Calc. for C28H44N2P2Au2Fe: C,
36.52; H, 4.78; N, 3.04. Found: C, 36.62; H, 4.88; N, 3.24. IR (cmꢀ1
KBr):
¼ 3404, 2930, 2940, 2878, 2861, 2151(CN), 1654, 1478, 1451,
1380, 1340, 1301, 1212, 1174, 1150, 1041, 1020, 930, 888, 810, 750,
664, 624. 1H NMR (
ppm, 400 MHz, CDCl3, 298 K): 4.40(s, 4H,
,
n
C
30H44N4P2Ag4Fe: C, 35.64; H, 4.36; N, 5.54. Found: C, 35.82; H, 4.40;
N, 5.64. IR (cmꢀ1, KBr):
¼ 3410, 3095, 2987, 2947, 2899, 2867, 2718,
2459, 2114(CN), 1645, 1477, 1458, 1392, 1368, 1302, 1216, 1175, 1154,
1040, 1021, 932, 887, 812, 751, 663, 630. 1H NMR (
ppm, 400 MHz,
n
d
C5H4), 4.12 (s, 4H, C5H4), 1.22 (d, 36H, CH3). 31P{1H}:
d 64.9 (s)
d
(Sharp). UV/Vis: lmax (ε [dm3 molꢀ1 cmꢀ1]) ¼ 275 (15,932), 453
CDCl3, 298 K), 4.35(s, 4H, C5H4), 4.15 (s, 4H, C5H4),1.21 (m, 36H, CH3).
(41,573). ESI-MS (m/z): 920.5 (Mþ).
31P{1H}:
d
41.54 (sbr). UV/Vis: lmax (ε [dm3 molꢀ1 cmꢀ1]) ¼ 265
(20,432), 474 (18,890). ESI-MS (m/z): 1009.4 (Mþ).
4.2.5. [Ag4(m3-CN)2(m1-CN)2(k
1-P,P-dcpf)2] (5)
1,10-Bis(dicyclohexylphosphino)ferrocene (dcpf) (0.578 g,
1.0 mmol) was added to a solution of silver(I) cyanide (0.134 g,
1.0 mmol) in 30 mL CH3OH:CH2Cl2 (50:50 V/V) mixture at room
temperature. The resultant suspension was refluxed with stirring
under nitrogen atmosphere for 24 h in dark. Slowly, the colour of
the solution changed from light yellowish orange to dark yellowish
orange colour. The resulting solution was evaporated to dryness to
give a yellowish orange solid which was then extracted with
dichloromethane (20 mL). The addition of diethyl ether (100 mL) to
this solution led to yellow needle shaped diffraction quality crys-
tals. These were separated and washed with hexane and dried.
Yield: (0.846 g, 50%). Anal. Calc. for C72H104N4P4Ag4Fe2: C, 51.06; H,
6.15; N, 3.31. Found: C, 51.28; H, 6.34; N, 3.43. IR (cmꢀ1, KBr):
4.2.3. [Au2(m1-CN)2(k
1-P,P-dppf)] (3)
1,10-Bis(diphenylphosphino)ferrocene (dppf) (0.554 g,1.0 mmol)
was added to a solution of gold(I) cyanide (0.223 g, 1.0 mmol) in
30 mL CH3OH:CH2Cl2 (50:50 V/V) mixture at room temperature.
The resultant suspension was refluxed with stirring under nitrogen
atmosphere for 24 h. Slowly, the colour of the solution changed
from light yellowish orange to dark yellowish orange. The resulting
solution was evaporated to dryness to give a dark yellowish orange
solid which were separated and washed with hexane and dried.
Yield: (0.500 g, 50%). Anal. Calc. for C36H28N2P2Au2Fe: C, 43.20; H,
2.80; N, 2.80. Found: C, 43.32; H, 2.85; N, 2.91. IR (cmꢀ1, KBr):
n
¼ 3430, 3022, 2929, 2147(CN), 1956, 1650, 1580, 1479, 1428, 1308,
1164, 1157, 1091, 1086, 1022, 890, 820, 740, 691, 630, 494. 1H NMR (
d
n
¼ 3401, 2926, 2852, 2368, 2345, 2129(CN), 1740, 1444, 1240, 1165,

M. Trivedi et al. / Journal of Organometallic Chemistry 758 (2014) 9e18
17
1109, 1036, 850, 625, 480. 1H NMR (
d
ppm, 400 MHz, CDCl3, 298 K):
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4.43(s, 8H, C5H4), 4.18 (s, 8H, C5H4), 2.71e1.34 (m, 88H, Cy). 31P{1H}:
56.6 (sbr). UV/Vis: lmax (ε [dm3 molꢀ1 cmꢀ1]) ¼ 272 (14,719), 478
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temperature. The resultant suspension was refluxed with stirring
under nitrogen atmosphere for 24 h. Slowly, the colour of the so-
lution changed from light yellowish orange to dark yellowish or-
ange colour. The resulting solution was evaporated to dryness to
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dichloromethane (20 mL). The addition of hexane (100 mL) to this
solution led to yellow needle shaped diffraction quality crystals.
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d
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d
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a
radiation
ꢀ
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Acknowledgements
We gratefully acknowledge financial support by the Department
of Science and Technology, New Delhi (Grant No. SR/FT/CS-104/
2011). Special thanks are due to Professor Josef Michl, Department
of Chemistry and Biochemistry, Colorado University, USA, Professor
P. Mathur and Professor Shaikh M. Mobin, Indian Institute of
Technology, Indore and National Single Crystal X-ray Diffraction
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