Coordination properties of the 1,1′-bis[((6-methyl)-2-pyridyl)amido] ferrocene ligand towards group 11 complexes

Article abstract of DOI:10.1039/b927208a

The coordination properties of the 1,1′-bis[((6-methyl)-2-pyridyl) amido]ferrocene ligand (L) towards group 11 and palladium complexes have been studied. L coordinates as the bridging ligand, through the pyridinic nitrogen atoms, when reacting with the gold(i) compounds [Au(OTf)(PPh₃)] and [Au(C₆F₅)(tht)] or with the gold(iii) species [Au(C ₆F₅)₃(tht)] leading to linear or square planar derivatives, respectively. The reaction of L with [O(AuPPh₃) ₃]ClO₄ affords the tetranuclear compound [Au ₄(L-H)₂(PPh₃)₄](ClO ₄)₂ in which the amide groups have been deprotonated and the ligand acts as dianionic, N,N,N,N-tetradentate. The treatment of the ligand L with silver salts leads to mononuclear complexes with the ligand acting as N,N,O or N,N chelating in [AgL]OTf, or [AgL₂]OTf, or to dinuclear species with an N,N bridging ligand in [Ag₂(PPh₃) ₂(μ-L)](OTf)₂. Tetracoordination around the copper atom is proposed for the copper complexes [CuL(PPh₃)₂]PF ₆, [CuL]PF₆, or [CuL₂]PF₆ with the ligand coordinated in an NH,NH,N,N or an N,N chelating fashion. Finally the palladium compound [PtCl₂L] has been synthesized with a trans-chelating ligand. In the structures of some of these derivatives the presence of secondary interactions such as weak hydrogen bonds of the type C-H...O, C-H...N or C-H...X (X = F, Cl) or even M...O interactions leads to supramolecular networks.

Full text of DOI:10.1039/b927208a

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www.rsc.org/dalton | Dalton Transactions
Coordination properties of the 1,1¢-bis[((6-methyl)-2-pyridyl)amido]ferrocene
ligand towards group 11 complexes†
Javier E. Aguado,a Olga Crespo,a M. Concepcio´n Gimeno,*a Peter G. Jones,b Antonio Lagunaa and
M. Dolores Villacampaa
Received 4th January 2010, Accepted 10th March 2010
First published as an Advance Article on the web 25th March 2010
DOI: 10.1039/b927208a
The coordination properties of the 1,1¢-bis[((6-methyl)-2-pyridyl)amido]ferrocene ligand (L) towards
group 11 and palladium complexes have been studied. L coordinates as the bridging ligand, through
the pyridinic nitrogen atoms, when reacting with the gold(I) compounds [Au(OTf)(PPh3)] and
[Au(C6F5)(tht)] or with the gold(III) species [Au(C6F5)3(tht)] leading to linear or square planar
derivatives, respectively. The reaction of L with [O(AuPPh3)3]ClO4 affords the tetranuclear compound
[Au4(L-H)2(PPh3)4](ClO4)2 in which the amide groups have been deprotonated and the ligand acts as
dianionic, N,N,N,N-tetradentate. The treatment of the ligand L with silver salts leads to mononuclear
complexes with the ligand acting as N,N,O or N,N chelating in [AgL]OTf, or [AgL2]OTf, or to dinuclear
species with an N,N bridging ligand in [Ag2(PPh3)2(m-L)](OTf)2. Tetracoordination around the copper
atom is proposed for the copper complexes [CuL(PPh3)2]PF6, [CuL]PF6, or [CuL2]PF6 with the ligand
coordinated in an NH,NH,N,N or an N,N chelating fashion. Finally the palladium compound [PtCl2L]
has been synthesized with a trans-chelating ligand. In the structures of some of these derivatives the
presence of secondary interactions such as weak hydrogen bonds of the type C–H ◊ ◊ ◊ O, C–H ◊ ◊ ◊ N or
C–H ◊ ◊ ◊ X (X = F, Cl) or even M ◊ ◊ ◊ O interactions leads to supramolecular networks.
molecular recognition as they are able to modify selectively
their electrochemical properties upon coordination of the target
Introduction
species.2e,4 More recently, ferrocene receptors for neutral molecules
have been developed and been shown to bind biologically relevant
molecules though complementary hydrogen-binding interactions.5
Our contributions to this field include several ferrocene ligands
that show interesting coordination properties and in some cases
give rise to supramolecular motifs through weak hydrogen bonds.6
We report here on the coordination properties of the 1,1¢-
bis[((6-methyl)-2-pyridyl)amido]ferrocene ligand towards group
11 metals and palladium compounds. Several metallic complexes
of Pd,7 M2+ (M = Cu, Ni, Co)8 have been reported with similar
ligands. Here we describe the coordination behaviour of this
ligand, which is thereby shown to act as a bidentate bridging,
chelating or trans-chelating ligand and also as a tridentate or
tetradentate neutral or dianionic chelating ligand.
Ferrocene is a very versatile molecule with important properties
such as high electron density, aromaticity and redox reversibility.
These characteristics, together with the well established routes
to mono and 1,1¢-disubstituted ferrocene derivatives with a great
variety of organic fragments containing donor atoms such as O,
N, S, P, make ferrocene a very suitable building block in many
fields of research.1 Current areas of interest in ferrocene chemistry
include the use in catalysis, materials and bioinorganic chemistry.
These functionalized ferrocene derivatives and the study of their
coordination to metal centres represent an important topic of
research in many areas that seek special properties of such species,
e.g. non-linear optical properties, charge transport, liquid crystals,
electrochemical recognition, catalysis, nanoparticles, immunoas-
say reagents or biological applications.1,2
The introduction of a ferrocene group into supramolecular
coordination systems not only incorporates a redox-active group
but also leads to interesting assembled structures because of
the conformational flexibility of the ferrocene moieties and the
varying coordination numbers of metal ions. Several reports have
dealt with the synthesis of ferrocene-based bidentate ligands that
contain pyridine moieties, their interesting coordination properties
and novel supramolecular structures.3 These ferrocene-containing
amidopyridyl compounds have been used in electrochemical
Results and discussion
The ligand 1,1¢-bis[((6-methyl)-2-pyridyl)amido]ferrocene (L) has
been prepared by reaction of di-chlorocarbonylferrocene with
2-amine-6-methylpyridine, molar ratio 1 : 2, in dichloromethane
and in the presence of NEt3 as has been previously reported.9 The
structure of the ligand has been reported at room temperature and
150 K in the Cambridge Database.10
aDepartamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales
de Arago´n, Universidad de Zaragoza-C.S.I.C., E-50009, Zaragoza, Spain
The reactivity of L towards several gold compounds has been
studied and thus the reaction of L with two equivalents of
[Au(OTf)(PPh3)] affords the complex [Au2(m-L)(PPh3)2](OTf)2 (1)
in which the gold atoms have coordinated to the ligand through the
nitrogen atoms of the pyridine rings (see Scheme 1). The IR and
NMR data agrees with the formulation proposed. The 1H NMR
bInstitut fu¨r Anorganische und Analytische Chemie der Technischen Univer-
sita¨t, Postfach 3329, D-38023, Braunschweig, Germany
† Electronic supplementary information (ESI) available: Experimental
details. CCDC reference numbers 760667–760669. For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/b927208a
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Scheme 1 i) 2 [Au(OTf)(PPh3)], ii) 2 [O(AuPPh3)3]ClO4, iii) 2 [Au(C6F5)(tht)], iv) 2 [Au(C6F5)3(OEt2)].
Fig. 1 Perspective view of the X-ray structure of complex 1 showing the atom labelling scheme. Hydrogen atoms have been omitted for clarity. Ellipsoids
represent 50% probability levels.
spectrum shows the following resonances: two multiplets for the
a and b protons of the ferrocenyl unit, in the aromatic region of
the resonances for the phenyl and pyridine protons (overlapped),
inversion symmetry, can be seen in Fig. 1. A selection of bond
lengths and angles are collected in Table 1. In the molecule
the cyclopentadienyl units have an antiperiplanar disposition
probably in order to minimize the steric hindrance of the bulky
triphenylphosphine groups. The ferrocene ligand acts in a bridging
mode. Each gold centre displays linear geometry [N11–Au–P =
1
the amido protons and the methyl groups. The 31P{ H} NMR
spectrum shows the equivalence of both phosphorus atoms as
only one singlet appears.
The crystal structure of complex 1 has been established by X-ray
diffraction and the molecule, which displays crystallographic
◦
˚
179.31(14) ]. The Au–N and Au–P bond distances are 2.110(5) A
˚
and 2.2353(17) A, respectively (Table 1). The former are among the
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◦
˚
shows two resonances at 30.2 and 27.8 ppm, arising at the two
different types of phosphorus atoms, and with a chemical shift
characteristic of P–Au–py and P–Au–amide environments. In the
IR spectra the absorption due to the NH is no longer observed. The
1H NMR spectrum presents the resonances for the ferrocenyl unit
as three multiplets in a ratio of 4 : 2 : 2, a singlet for the methyl
protons and the resonances of the pyridine ring and phenyl rings;
the signal corresponding to the NH proton has disappeared.
The reaction of L with two equivalents of [Au(C6F5)(tht)] (tht =
tetrahydrothiophene) gives the complex [Au2(C6F5)2(m-L)] (3) in
which the ligand bridges both gold fragments. The 1H NMR
spectrum contains two multiplets for the a and b protons of
the cyclopentadienyl units, a singlet for the methyl group, two
doublets and a triplet for the pyridine moiety and a singlet for the
amide protons. The 19F NMR spectrum however shows inequiv-
alent pentafluorophenyl rings, probably because of the restricted
rotational freedom of the pentafluorophenyl group around the
Au–Cipso bond, and thus six resonances in a ratio 2 : 2 : 1 : 1 : 2 : 2
for the meta, para and ortho fluorine, respectively, can be observed.
This restricted rotation of pentafluorophenyl rings has been
previously observed by us and others in many gold, palladium
and platinum complexes with pentafluorophenyl rings.13 A rapid
exchange between the pyridine and NH coordination sites is ruled
out because of the low tendency of gold(I) centers to bond the
nitrogen atom of an amide CO-NH- group. The LSIMS mass
spectrum presents the molecular peak at m/z = 1182 (15%).
The gold(III) derivative [Au2(C6F5)6(m-L)] (4) has also been
synthesized by reaction of the ligand with [Au(C6F5)3(OEt2)]
in a molar ratio 1 : 2. The spectroscopic data corroborates the
coordination of the tris(pentafluorophenyl) fragments to both
pyridine nitrogen atoms giving a dinuclear derivative with the
ligand bridging both gold centres. The 1H NMR spectrum presents
multiplets for the a and b protons of the cyclopentadienyl groups,
singlets for the methyl and NH protons, and the pyridine protons
appear as a doublet (5,5¢), a triplet (4,4¢) and a doublet (3,3¢). The
19F NMR spectrum shows two types of pentafluorophenyl units in
a ratio 2 : 1, the mutually trans fluorines are equivalent, and each
one presents three different resonances for the ortho, meta and
para fluorine. The mass spectrum presents the molecular peak at
m/z = 1850 (7%) and the fragment at m/z = 1152 (7%) originating
from the loss of one “Au(C6F5)3” unit.
Table 1 Selected bond lengths (A) and angles ( ) for 1
Au–N(11)
2.110(5)
179.31(14)
114.1(2)
113.4(2)
Au–P
2.2353(17)
110.4(2)
117.6(4)
121.7(4)
N(11)–Au–P
C(21)–P–Au
C(41)–P–Au
C(31)–P–Au
C(12)–N(11)–Au
C(16)–N(11)–Au
longest Au–N bonds in gold(I) complexes in which the gold centre
displays linear coordination, cf. [Au(Fcpy)(PPh3)]OTf (FcPy =
3-ferrocenylpyridine), two independent molecules, Au–P 2.233(3),
2.228(3) A, Au–N 2.065(10), 2.070(9) A;11 [Au(dmpy)(PPh3)]ClO4
˚
˚
˚
(dmpy = 2,6-dimethylpyridine), Au–P 2.233(4) A, Au–N 2.091(3)
12
˚
A; [Au(pbzim)(PPh3)]ClO4 (pbzim = 2,6-di-tert-butylpyridine),
12
˚
˚
Au–P 2.233(4) A, Au–N 2.091(3) A]; [Au(C6F5)(FcPy)] (Au–N
11
˚
2.114(15) A) or [{Au(PPh3)}2{Fc(SPy)2}](OTf)2 [Fc(Spy)2
=
˚
1,1¢-bispyridylthioferrocene)], Au–P 2.2420(17) A, Au–N
6g
˚
2.083(6) A.
Several hydrogen bonds of the type C–H ◊ ◊ ◊ O, N–H ◊ ◊ ◊ O and
C–H ◊ ◊ ◊ F contribute to the final packing (see ESI Table S1†).
Hydrogen bonds that involve the triflate oxygen atoms must be
interpreted with care, as the anion is disordered over two positions
with occupation factors 0.54, 0.46. The cations are connected to
form chains parallel to the x axis by the weak hydrogen bond C42–
˚
˚
H42 ◊ ◊ ◊ O1 [d(C–H ◊ ◊ ◊ O) 3.414(8) A, d(H ◊ ◊ ◊ O) 2.62 A] combined
˚
with the contact Au ◊ ◊ ◊ O1 3.09 A (Fig. 2).
The ligand L possesses, apart from the nitrogen atoms of the
pyridine groups, two amido NH groups that can also coordinate
to metallic centres. The gold compound [O(AuPPh3)3]ClO4 is an
excellent aurating agent that can deprotonate twice, forming H2O,
and thus incorporate up to three gold atoms into another com-
pound. In the case of L the amido protons can be deprotonated
and then there are four coordination sites that are the two pyridine
nitrogens and the amide groups. The reaction of L with two
equivalents of the oxonium complex at room temperature gives
a mixture of complex 1 and another complex that according to its
NMR spectrum is the tetragold species [Au4(L-2H)(PPh3)4](ClO4)2
(2). If we carry out the same reaction under reflux conditions for
24 h the expected complex [Au4(L-2H)(PPh3)4](ClO4)2 (2), in which
the ligand is acting as tetradentate by coordination to gold through
the deprotonated NH groups and the pyridine atoms, is isolated.
The rest of the gold atoms coming from the oxonium compound
are lost possibly in the form of [Au(PPh3)2]OTf, [Au(OTf)(PPh3)]
The reactivity of the ligand L towards silver(I) complexes has
been tested; thus the treatment with one equivalent of Ag(OTf)
or other unidentified by-products. The 31P{ H} NMR spectrum
1
Fig. 2 Formation of chains through hydrogen bonds and Au ◊ ◊ ◊ O interactions in compound 1.
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1
2
Scheme 2 i) Ag(OTf) ii) Ag(OTf), iii) 2 [Ag(OTf)(PPh3)]
◦
˚
Table 2 Selected bond lengths (A) and angles ( ) for 5
Ag–N(21)
Ag–N(31)
N(21)–Ag–N(31)
N(21)–Ag–O(2)
N(31)–Ag–O(2)
2.1768(19)
2.1998(19)
179.23(7)
103.79(6)
75.56(6)
Ag–O(2)
Ag–O(2)#1
N(21)–Ag–O(2)#1
N(31)–Ag–O(2)#1
O(2)–Ag–O(2)#1
2.5605(16)
2.7178(17)
91.01(6)
88.92(6)
115.00(4)
affords the complex [Ag(L)]OTf (5) in high yield (see Scheme 2).
The 1H NMR spectrum of the compound shows the typical
resonances for the ligand protons but with a different chemical
shift in agreement with the coordination to a metallic center.
The mass spectrum presents the molecular peak [Ag(OTf)(L)]+
at m/z = 712 (5%), although the most intense peak corresponds
to the cation molecular peak, [AgL]+, at m/z = 561.
The crystal structure of complex 5 has been established by
X-ray diffraction. In compound 5 the ferrocene ligand is tridentate
(Fig. 3). The cyclopentadienyl rings are staggered by 4.4◦ around
the Cp ◊ ◊ ◊ Cp axis (Cp = centre of the cyclopentadienyl ring) as
defined by the torsion angle C1–Cp–Cp–C10. The silver atom
diplays a T-shaped geometry [N21–Ag–N31 179.23(7)◦, N21–Ag–
O2 103.79(6), N31–Ag–O2 75.56(6), see Table 2] with the silver
Fig. 3 Perspective view of the X-ray structure of the cation of complex
5 showing the atom labelling scheme. Hydrogen atoms have been omitted
for clarity. Ellipsoids represent 50% probability levels.
˚
atom 0.008 A out of the plane formed by O2, N31 and N21.
In addition, the silver atom displays a short contact with one of
˚
the oxygen atoms of another molecule [Ag–O2#1 2.7178(17) A]
leading to the formation of a chain (Fig. 4).
sulfoisophthalic acid) for which “Ag(bpy)” units form chains,
as do the “Ag(HSIP)(bpy)” units. Both types of chains
An analogous arrangement, with similar Ag–N and Ag–O
bond distances, is found in the compound {[Ag(bpy)]-
14
˚
are linked through Ag ◊ ◊ ◊ O contacts (2.7598(7) A). In
[Ag(HSIP)(bpy)](H2O)2}n (bpy
=
bipyridine, H3SIP
=
5-
{[Ag(bpy)][Ag(HSIP)(bpy)](H2O)2}n the silver centres of the
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Fig. 4 Formation of chains in 5 through Ag ◊ ◊ ◊ O contacts (width broad dashed lines) and hydrogen bonds (thin dotted lines).
“Ag(HSIP)(bpy)” fragment displays T-shaped geometry with
The reaction of L with Ag(OTf) in a 2 : 1 molar ratio gives
the species [Ag(L)2]OTf 6, in which the silver atom is probably
coordinated to two bidentate chelating ligands through the
pyridine nitrogen atoms. The IR and NMR data agrees with the
proposed formulation.
˚
Ag–N distances of 2.178(7) and 2.209(7) A (cf. 2.1768(19),
˚
2.1998(19) A found in 5). These distances are slightly longer
than those of the two coordinated linear silver centres
˚
in the “Ag(bpy)” units (2.154(7), 2.162(7) A). The Ag–O
˚
bonding distance in 5 (2.5605(16) A) is longer than that
The treatment of L with two equivalents of [Ag(OTf)(PPh3)]
leads to the dinuclear species [Ag2(m-L)(PPh3)2](OTf)2 7 with
the ligand bridging both silver centres. The H NMR spectrum
˚
in {[Ag(bpy)][Ag(HSIP)(bpy)](H2O)2} (2.453(7) A). The bond
1
lengths increase as the number of weak contacts (Ag ◊ ◊ ◊ N,
Ag ◊ ◊ ◊ O…) increases. Thus longer distances than those in 5 are
shown in [Ag2{1,2-bis(8-quinolyloxymethyl)benzene}3]15 in which
presents the resonances for the ligand coordinated to silver and
1
for the triphenylphosphine. The 31P{ H} NMR spectrum at room
˚
each silver centre displays two short Ag ◊ ◊ ◊ O (2.656(2)–2.725(2) A)
temperature shows a broad resonance that splits into two doublets
at -55 ◦C because of the coupling of the phosphorus atom with the
two silver nuclei, 109Ag and 107Ag. The mass spectrum (LSIMS+)
presents the fragments at m/z = 1343 (2%) corresponding to the
loss of a triflate anion from the molecular peak.
˚
and one Ag–N (2.714(2)–2.722(2) A) contacts in addition to two
Ag–N and one Ag–O bonds [Ag–N 2.213(2), 2.229(2) A; Ag–O
˚
˚
2.595(2) A].
Hydrogen bonds of the type C–H ◊ ◊ ◊ O and N–H ◊ ◊ ◊ O are
present (see ESI, Table S2†). The oxygen atoms bonded to the
silver centre in the chain Ag–O ◊ ◊ ◊ Ag–O ◊ ◊ ◊ are also involved
in two hydrogen bonds, one with one of the hydrogen atoms of
one of the cyclopentadienyl rings of the adjacent molecule [C2–
H2 ◊ ◊ ◊ O2#] [d(C–H ◊ ◊ ◊ O) 3.323(3) A; d(H ◊ ◊ ◊ O) 2.45 A], the other
with the hydrogen atom of the amide group [N11–H11 ◊ ◊ ◊ O2#]
[d(N–H ◊ ◊ ◊ O) 3.150(3) A; d(H ◊ ◊ ◊ O) 2.40(3) A], reinforcing the
chain (Fig. 4). In each chain the oxygen atoms not bonded to
silver (O1) participate in hydrogen bonds with hydrogen atoms of a
cyclopentadienyl ring of another molecule [C8–H8 ◊ ◊ ◊ O1#] [d(C–
H ◊ ◊ ◊ O 3.292(3) A; d((H ◊ ◊ ◊ O) 2.57 A] leading to a 3D structure.
The pattern is complicated further by hydrogen bonds involving
the oxygen atoms of the triflate groups (e.g. from N12–H12 of the
The reactivity of the ferrocene ligand with copper(I) complexes
has also been studied and the treatment of [Cu(NO3)(PPh3)2]
with L gives [Cu(L)(PPh3)2]NO3 8, in which presumably the
copper centre has a tetrahedral geometry with a coordinated
1
˚
˚
chelating ligand (see Scheme 3). The H NMR spectrum shows
the resonances for the a and b cyclopentadienyl protons as
two multiplets, the protons for the pyridine moieties appear as
multiplets and the methyl and amine NH protons as singlets.
˚
˚
1
The 31P{ H} NMR spectrum shows a unique resonance for the
phosphine ligands.
˚
˚
The reaction of L with [Cu(NCMe)4]PF6 in a 1 : 1 and a 2 : 1
4
molar ratio has been carried out affording the complexes [Cu(h -
L)]PF6 9 and [Cu(L)2]PF6 10. In complex 9 we propose that the
copper centre is coordinated to the four nitrogen atoms of the
ligand, two from the NH groups and two from the pyridine units.
˚
chain to O3 of the triflate, d(N–H ◊ ◊ ◊ O) 2.956(3) A; d(H ◊ ◊ ◊ O)
˚
2.17(3) A).
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1
2
Scheme 3 i) [Cu(NO3)(PPh3)2], ii) [Cu(NCMe)4]PF6, iii) [Cu(NCMe)4]PF6, iv) [PdCl2(NCPh)2]
The coordination mode of the ligand thus resembles that of a
The crystal structure of complex 11 has been established by
X-ray diffraction studies. Complex 11 crystallizes in the
monoclinic system with the palladium and the Fe atoms lying
on a twofold symmetry axis; consequently its asymmetric unit
contains half of the molecule (Fig. 5 shows the molecule generated
by symmetry). Selected bond lengths and angles are shown in
Table 3. The palladium centre is chelated by the pyridyl nitrogen
atoms of the ferrocene group in a trans geometry with cis angles
of 88.56(10)◦ and 91.60(10)◦; the palladium atom displays a
slightly distorted square plane coordination that tends towards
tetrahedral: the dihedral angle between the planes formed by
N2–Pd1–Cl1A and N2A–Pd–Cl1 is 6.7◦, with the chlorine
atoms oriented to the inside of the molecule. Two symmetrical
intramolecular, weak but significant, hydrogen bonds between
each chlorine and the nearest amido proton of the ferrocenyl
macrocyclic ligand. In complex 10 the geometry around the copper
1
atoms should be tetrahedral with two chelating ligands. The H
NMR spectrum of complex 9, where coordination to the NH
groups is proposed, shows the resonance for the NH protons
shifted downfield related to the ligand. The mass spectra presents
the cation molecular peak for 9 at m/z = 517 ([CuL]+, 20%) and
for 10 at m/z = 971 ([CuL2]+, 15%).
Finally, we have also explored the reactivity of ligand L with
other transition metal as palladium. Thus the reaction of L with
the palladium complex trans-[PdCl2(NCPh)2] has been carried out
and gives the complex trans-[PdCl2(L)] 11 (see Scheme 3). The 1H
NMR spectrum presents two multiplets for the a and b protons of
the cyclopendienyl groups, a singlet for the methyl protons, three
multiplets for the (5,5¢), (4,4¢) and (3,3¢) pairs of the pyridine unit
and a singlet for the NH protons. The mass spectrum shows the
molecular peak at m/z = 631 (82%).
◦
˚
ligand (H1 ◊ ◊ ◊ Cl1 distance: 2.81 A; N1–H1 ◊ ◊ ◊ Cl1 angle: 134.8 )
are present. They could be associated with the distortion of
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Fig. 5 Molecular structure of compound 11 showing the atom numbering scheme. Displacement parameter ellipsoids represent 50% probability surfaces.
◦
˚
Table 3 Selected bond lengths [A] and angles [ ] for compound 11
Conclusions
The 1,1¢-bis[((6-methyl)-2-pyridyl)amido]ferrocene ligand (L)
shows different coordination modes in its coordination to gold,
silver, copper and palladium. In most of the complexes studied
L acts as bidentate chelate or bridging ligand; it is noteworthy
that in the silver and palladium species the coordination of the
ligand is trans-chelating. Other less frequent coordination modes
are as a tridentate O,N,N-, as tetradentate neutral NH,NH,N,N-
or a tetradentate dianionic N,N,N,N-ligand. In the structures of
some of these derivatives the presence of secondary interactions
such as weak hydrogen bonds of the type C–H ◊ ◊ ◊ O, C–H ◊ ◊ ◊ N
or C–H ◊ ◊ ◊ X (X = F, Cl) or even M ◊ ◊ ◊ O interactions lead to
supramolecular networks.
Pd(1)–N(2)#1
Pd(1)–N(2)
N(2)#1–Pd(1)–N(2)
N(2)#1–Pd(1)–Cl(1)#1 91.60(10) N(2)–Pd(1)–Cl(1)
N(2)–Pd(1)–Cl(1)#1
2.046(3)
2.046(3)
Pd(1)–Cl(1)#1
Pd(1)–Cl(1)
2.2825(14)
2.2825(14)
177.09(15) N(2)#1–Pd(1)–Cl(1) 88.56(10)
91.60(10)
88.56(10) Cl(1)#1–Pd(1)–Cl(1) 173.99(6)
Symmetry transformations used to generate equivalent atoms: #1
-x,y,-z+1/2.
the square planar geometry (Fig. 5). Additionally, the molecule
presents two short intramolecular interactions between the
oxygen of the CO and one proton of the pyridine group of
each chain of the ferrocene ligand, that could be considered as
˚
hydrogen bonds (H13 ◊ ◊ ◊ O1 distance: 2.29 A; C13–H13 ◊ ◊ ◊ O1
angle: 118.4◦). The cyclopentadienyl rings adopt a staggered
orientation with a torsion angle C1–X1–X2–C5A of 20.3◦,
where X1 and X2 are the centres of the cyclopentadienyl rings.
The corresponding angle C1–X1–X2–C1A is 87.2◦. The Pd–N
Experimental
Instrumentation
˚
˚
(2.046(3) A) and Pd–Cl (2.2825(14) A) distances are of the same
order than those found in related trans square planar palladium(II)
complexes such as: [PdCl2(2-BPEFA)]16 (2-BPEFA = N,N¢-bis{2-
Infrared spectra were recorded in the range 4000–200 cm-1 on a
Perkin-Elmer 883 spectrophotometer using Nujol mulls between
polyethylene sheets. C, H, N and S analyses were carried out with
a Perkin-Elmer 2400 microanalyzer. Mass spectra were recorded
on a VG Autospec, with the liquid secondary-ion mass spectra
(LSIMS) technique, using nitrobenzyl alcohol as matrix. NMR
spectra were recorded on a Varian Unity 300 spectrometer and a
Bruker ARX 300 spectrometer in CDCl3, unless otherwise stated.
Chemical shifts are cited relative to SiMe4 (1H, external), CFCl3
(19F, external) and 85% H3PO4 (31P, external).
(2-pyridyl)ethyl}-1,1¢-ferrocenedicarboxiamide),
[PdCl2(2-
BPMFA)]16 (2-BPMFA = N,N¢-bis(2-pyridylmethyl)-1,1¢-ferro-
cenedicarboxiamide), [PdCl2(FcNP2)]17 (FcNP2 = 1,1¢-bis(1,8-
naphthyrid-2-yl)ferrocene), [PdCl2{Fc-(Ala-L-Pro-NHPy)2}]18 or
19
=
[PdCl2{Fc(N CH-6-Me-Py)2}] (Pd–N bond distances range
˚
from 2.013(5) to 2.06(1) A and Pd–Cl bond distances from
˚
2.297(3) to 2.315(1) A). There are no intermolecular H-bonds of
note in the structure of this complex 11.
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Dalton Trans., 2010, 39, 4321–4330 | 4327
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Starting materials
JHH = 9.0 Hz, 3,3¢-py), 8.52 (s, 2H, NH). 19F NMR, d = -121.9
(m, 4F, m-F), -122.7 (m, 1F, m-F), -122.8 (m, 1F, m-F), -155.1 (t,
2F, JFF = 20.6 Hz, p-F), -155.8 (t, 1F, JFF = 20.6 Hz, p-F), -160.1
(m, 4F, o-F), -160.7 (m, 1F, o-F), -161.0 (m, 1F, o-F). IR: C6F5,
1510 (vs), 967 (vs), 817 (m) and 795 (m) cm-1.
The starting materials Fc(COCl)2,20 [O(AuPPh3)3]ClO4,21
[Au(C6F5)(tht)],22
[Au(C6F5)3(tht)],23
[Ag(OTf)(PPh3)],24
[Cu(NO3)(PPh3)2],25 [Cu(NCMe)4]PF6,25 trans-[PdCl2(NCPh)2]26
were
prepared
according
to
published
procedures.
[Au(OTf)(PPh3)] was obtained by reaction of [AuCl(PPh3)]27 with
Ag(OTf) in dichloromethane and used in situ. All other reagents
were commercially available.
Synthesis of [Ag(g3-L)]OTf (5). To a solution of L (0.045 g,
0.1 mmol) in 20 mL of dichloromethane was added Ag(OTf)
(0.025 g, 0.1 mmol) under an argon atmosphere. The mixture
was stirred for 30 min and then evaporation of the solvent to ca.
5 mL and addition of diethyl ether gave complex 5 as an orange
solid. Yield, 0.042 g, 60%. C25H22AgF3FeN4O5S (709.96): calcd.
C 42.25, H 3.12, N 7.89, S 4.50; found C 42.21, H 3.19, N 7.70,
Synthesis of [Au2(l-L)(PPh3)2](OTf)2 (1). To a solution of L
(0.045 g, 0.1 mmol) in 20 mL of dichloromethane was added
[Au(OTf)(PPh3)] (0.121 g, 0.2 mmol) under an argon atmosphere.
The mixture was stirred for 1 h and then evaporation of the solvent
to ca. 5 mL and addition of diethyl ether gave complex 1 as
an orange solid. Yield, 0.130 g, 78%. C62H52Au2F6FeN4O8P2S2
(1670.94): calcd. C 44.56, H 3.13, N 3.35, S 3.83; found C 44.79, H
3.28, N 3.16, S 3.63. 1H NMR, d = 2.82 (s, 6H, Me), 4.54 (m, 4H,
a-C5H4), 5.08 (m, 4H, b-C5H4), 7.2-8.0 (m, 6H + 30H, py + Ph),
1
S 4.41. H NMR, d = 2.69 (s, 6H, Me), 4.47 (m, 4H, a-C5H4),
5.08 (m, 4H, b-C5H4), 7.0.2 (m, 2H, 5,5¢-py), 7.66 (m, 4H, 4,4¢-
=
py + 3,3¢-py), 9.41 (s, 2H, NH). IR: u(C O) 1610 (m) and 1659
(m) cm-1, us(SO3) 1281 (vs), us(CF3) 1224 (vs), uas(CF3) 1165 (s)
and us(SO3) 1028 (vs) cm-1.
10.17 (s, 2H, NH). 31P{ H} NMR, d = 29.8 (s, PPh3). IR: us(SO3)
1
Synthesis of [Ag(L)2]OTf (6). To a solution of L (0.090 g,
0.2 mmol) in 20 mL of dichloromethane was added Ag(OTf)
(0.025 g, 0.1 mmol) under an argon atmosphere. The mixture
was stirred for 30 min and then evaporation of the solvent to ca.
5 mL and addition of diethyl ether gave complex 5 as a yellow
solid. Yield, 0.093 g, 80%. C49H44AgF3Fe2N8O7S (1164.07): calcd.
C 50.51, H 3.81, N 9.62, S 2.74; found C 50.57, H 3.94, N 9.77,
1275, us(CF3) 1222 (vs), uas(CF3) 1156 (s) and us(SO3) 1029 (vs),
-1
=
u(C O) 1672 (s) cm .
Synthesis of [Au4(L-2H)(PPh3)4](ClO4)2 (2). To a solution of
L (0.045 g, 0.1 mmol) in 20 mL of dichloromethane was added
[O(AuPPh3)3]ClO4 (0.298 g, 0.2 mmol) under an argon atmo-
sphere. The mixture was refluxed for 24 h and then evaporation of
the solvent to ca. 5 mL and addition of diethyl ether gave complex
2 as an orange solid. Yield, 0.181 g, 73%. C96H80Au4Cl2FeN4O10P4
(2486.22): calcd. C 46.33, H 3.24, N 2.25; found: C 46.76, H 3.28,
N 2.02. 1H NMR, d = 2.02 (s, 6H, Me), 4.33 (m, 4H, a-C5H4), 5.07
(m, 2H, b-C5H4), 5.39 (m, 2H, b-C5H4), 6.90 (d, 2H, JHH = 7.3 Hz,
1
S 2.64. H NMR, d = 2.69 (s, 6H, Me), 4.50 (m, 4H, a-C5H4),
5.01 (m, 4H, b-C5H4), 7.02 (d, 2H, JHH = 7.32 Hz, 5,5¢-py), 7.69 (t,
2H, JHH = 7.58 Hz, 4,4¢-py), 7.76 (d, 2H, JHH = 7.58 Hz, 3,3¢-py),
=
9.08 (s, 2H, NH). IR u(C O) at 1611 (s) and 1687 (s), us(SO3)
1279 (vs), us(CF3) 1225 (vs), uas(CF3) 1160 (s) and us(SO3) 1024
(vs) cm-1.
5,5¢-py), 7.76 (t, 2H, JHH = 7.78 Hz, 4,4¢-py), 7.90 (d, 2H, JHH
=
8.08 Hz, 3,3¢-py), 7.0-7.6 (m, 60H, Ph). 31P{ H} NMR, d = 27.8
1
-
(s, NAuPPh3), 30.2 (s, pyAuPPh3). IR: ClO4 619 (m), 1103 (s).
Synthesis of [Ag2(l-L)(PPh3)2](OTf)2 (7). To a solution of L
(0.045 g, 0.1 mmol) in 20 mL of dichloromethane was added
[Ag(OTf)(PPh3)] (0.103 g, 0.2 mmol) under an argon atmosphere.
The mixture was stirred for 30 min and then evaporation of the
solvent to ca. 5 mL and addition of diethyl ether gave complex 6
as an orange solid. Yield, 0.108 g, 73%. C62H52Ag2F6FeN4O8P2S2
(1490.0): calcd. C 49.93, H 3.51, N 3.76, S 4.29; found C 49.70,
H 3.62, N 3.56, S 4.33. 1H NMR, d = 2.63 (s, 6H, Me), 4.55 (m,
4H, a-C5H4), 5.12 (m, 4H, b-C5H4), 6.81 (m, 2H, 5,5¢-py), 7.3-7.8
Synthesis of [Au2(C6F5)2(l-L)] (3). A solution of L (0.045 g,
0.1 mmol) in 20 mL of dichloromethane and [Au(C6F5)(tht)]
(0.090 g, 0.2 mmol) under an argon atmosphere was stirred for
30 min. The solvent was evaporated to ca. 5 mL and addition of
n-hexane gave complex 3 as a yellow solid. Yield, 0.096 g, 82%.
C36H22Au2F10FeN4O2 (1182.02): calcd. C 36.54, H 1.87, N 4.73;
found: C 36.61, H 1.77, N 4.51. 1H NMR, d = 2.82 (s, 6H, Me),
4.46 (m, 4H, a-C5H4), 4.81 (m, 4H, b-C5H4), 6.82 (d, 2H, JHH
=
1
(m, 30H + 4H, Ph + 4,4¢-py + 3,3¢-py), 9.56 (s, 2H, NH). 31P{ H}
7.58 Hz, 5,5¢-py), 7.50 (t, 2H, JHH = 7.84 Hz, 4,4¢-py), 7.90 (d, 2H,
JHH = 8.34 Hz, 3,3¢-py), 8.52 (s, 2H, NH). 19F NMR, d = -114.9
(m, 2F, m-F), -116.3 (m, 1F, m-F), -116.6 (m, 1F, m-F), -158.5 (t,
1F, JFF = 20.2 Hz, p-F), -159.3 (t, 1F, JFF = 20.2 Hz, p-F), -162.1
(m, 1F, o-F), -162.4 (m, 1F, o-F), -162.9 (m, 1F, o-F), -163.6 (m,
NMR, r.t. d = 13.5 (s, br); -55 ◦C d = 13.1 (2d, J109AgP = 756 Hz,
=
J107AgP = 656 Hz). IR: u(C O) 1652 (s), us(SO3) 1289 (vs), us(CF3)
1233 (vs), uas(CF3) 1169 (s) and us(SO3) 1024 (vs) cm-1.
Synthesis of [Cu(l-L)(PPh3)2]NO3 (8). To a solution of L
(0.045 g, 0.1 mmol) in 20 mL of dichloromethane was added
[Cu(NO3)(PPh3)2] (0.065 g, 0.1 mmol) under an argon atmosphere.
The mixture was stirred for 30 min and then evaporation of the
solvent to ca. 5 mL and addition of diethyl ether gave complex
6 as an orange solid. Yield, 0.088 g, 80%. C60H52CuFeN5O5P2
(1103.20): calcd. C 65.26, H 4.75, N 6.34; found C 65.30, H 4.90,
=
1F, o-F). IR: C6F5 1505 (vs), 961 (s), 791 (s), n(C O) 1664 (s),
u(NH) at 3294 cm-1.
Synthesis of [Au2(C6F5)6(l-L)] (4). To a solution of L (0.045 g,
0.1 mmol) in 20 mL of dichloromethane was added [Au(C6F5)(tht)]
(0.154 g, 0.2 mmol) under an argon atmosphere. The mixture was
stirred for 30 min and then evaporation of the solvent to ca. 2 mL
and addition of n-hexane gave complex 4 as a yellow solid. Yield,
0.124 g, 67%. C60H22Au2F30FeN4O2 (1849.99): calcd. C 38.92, H
1.19, N 3.02; found: C 39.12, H 1.17, N 3.0. 1H NMR, d = 2.95
(s, 6H, Me), 4.78 (m, 4H, a-C5H4), 5.08 (m, 4H, b-C5H4), 7.3 (m,
2H, 5,5¢-py), 7.92 (t, 2H, JHH = 8.1 Hz, 4,4¢-py), 8.30 (d, 2H,
1
N 6.19. H NMR, d = 2.63 (s, 6H, Me), 4.64 (m, 4H, a-C5H4),
5.12 (m, 4H, b-C5H4), 7.11 (m, 2H, 5,5¢-py), 7.3–7.4 (m, 30H + 2H,
1
Ph + 4,4¢-py), 7.96 (m., 2H, 3,3¢-py), 8.43 (s, 2H, NH). 31P{ H}
-
=
NMR, d = -1.7 (s). IR: u(C O) 1693 (s), NO3 1770 (w), 1067
(w), 1041 (m), 996 (w), 838 (m) and 693 (s) cm-1.
4328 | Dalton Trans., 2010, 39, 4321–4330
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Table 4 X Ray data for complexes 1, 5 and 11
Compound
1
5
11
Formula
Mr
C62H52Au2F6FeN4O8P2S2
1670.92
C25H22AgF3FeN4O5S
711.25
C24H22Cl2FeN4O2Pd
631.63
Habit/Colour
Crystal size/mm
Crystal system
Space group
Cell constants:
Needle/Yellow
0.23 ¥ 0.06 ¥ 0.06
Triclinic
Needle/Orange
0.46 ¥ 0.07 ¥ 0.05
Tetragonal
Prism/Orange
0.24 ¥ 0.18 ¥ 0.08
Monoclinic
C2/c
¯
P1
P43
˚
a/A
9.494(3)
11.430(4)
16.213(6)
100.608(12)
102.036(12)
110.857(12)
1
1.799
5.172
816
12.0259(6)
12.0259(6)
17.3790(14)
90
90
90
4
1.880
1.509
1424
-100
56
18.883(13)
12.044(7)
12.081(8)
90
121.67(2)
90
˚
b/A
˚
c/A
a (◦)
b (◦)
g (◦)
Z
4
Dx (Mg m-3)
m/mm-1
F(000)
1.794
1.649
1264
-173
54
T/◦C
-100
56
2qmax
No. of refl.:
measured
independent
Transmissions
Rint
28783
7642
0.928, 0.477
0.0743
472
4889
6237
0.962, 0.776
0.0432
371
7208
2541
0.8794, 0.6930
0.0382
156
Parameters
Restraints
wR(F2, all Refl.)
R(I, >2s(I))
S
579
1
0
0.1267
0.0507
1.023
0.0491
0.0230
1.030
0.456
0.0728
0.0348
0.947
0.522
-3
˚
max. Dr/e A
4.071
Synthesis of [Cu(g4-L)]PF6 (9). To
a
solution of
L
calcd. C 45.71, H 3.52, N 8.89; found C 46.03, H 3.88, N 9.13. 1H
NMR, d = 3.48 (s, 6H, Me), 3.62 (m, 4H, a-C5H4), 4.72 (m, 4H,
b-C5H4), 7.06 (m, 2H, 5,5¢-py), 7.73 (m, 2H, 4,4¢-py), 8.20 (m., 2H,
3,3¢-py), 10.47 (s, 2H, NH).
(0.045 g, 0.1 mmol) in 20 mL of dichloromethane was added
[Cu(NCMe)4]PF6 (0.038 g, 0.1 mmol) under an argon atmosphere.
The mixture was stirred for 30 min and then evaporation of the
solvent to ca. 5 mL and addition of diethyl ether gave complex
9 as an orange solid. Yield, 0.047 g, 71%. C24H22CuF6FeN4O2P
(662.0): calcd. C 43.50, H 3.34, N 8.46; found C 43.54, H 3.42, N
X-ray crystallography
Data were recorded with a Bruker SMART 1000 CCD diffrac-
tometer. Data collection type: w-scans and f-scans. Absorption
corrections were based on multiple scans with the program
SADABS.28 The structures were refined on F2 using the program
SHELXL-97.29 All non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were including using a rigid (methyl groups)
or riding model. Refinement special details: The triflate anion in 1
is disordered over two positions with occupation factors 0.54, 0.46.
The residual electronic density can be attributed to the irregular
broad reflections associated with the needle shape of the crystal.
Compound 5 crystallizes by chance in a chiral space group. The
absolute structure and thus the space group P43 (rather than
P41) were determined by the Flack parameter -0.014(11). Further
crystallographic details are given in Table 4.
1
8.58. H NMR, d = 2.81 (s, 6H, Me), 4.71 (m, 4H, a-C5H4), 5.0
(m, 4H, b-C5H4), 7.20 (m, 2H, 5,5¢-py), 7.88 (m, 2H, 4,4¢-py), 7.82
-
=
(m., 2H, 3,3¢-py), 8.90 (s, 2H, NH). IR: u(C O) 1682 (s), PF6
844 (s) cm-1.
Synthesis of [Cu(L)2]PF6 (10). To a solution of L (0.090 g,
0.2 mmol) in 20 mL of dichloromethane was added
[Cu(NCMe)4]PF6 (0.038 g, 0.1 mmol) under an argon atmosphere.
The mixture was stirred for 30 min and then evaporation of the
solvent to ca. 5 mL and addition of diethyl ether gave complex
10 as an orange solid. Yield, 0.083 g, 75%. C48H44CuF6Fe2N8O4P
(1116.11): calcd. C 51.60, H 3.97, N 10.03; found C 51.83, H 4.18,
1
N 9.90. H NMR, d = 2.57 (s, 6H, Me), 4.59 (m, 4H, a-C5H4),
4.92 (m, 4H, b-C5H4), 6.99 (m, 2H, 5,5¢-py), 7.65 (m, 2H, 4,4¢-py),
-
=
7.84 (m, 2H, 3,3¢-py), 8.70 (s, 2H, NH). IR: u(C O) 1163 (s), PF6
Acknowledgements
844 (s) cm-1.
We thank the Direccio´n General de Investigacio´n Cient´ıfica y
Te´cnica (CTQ2007-67273-C02-01) for financial support.
Synthesis of [PdCl2L] (11). To a solution of L (0.045 g,
0.1 mmol) in 20 mL of dichloromethane was added trans-
[PdCl2(NCPh)2] (0.038 g, 0.1 mmol) under an argon atmosphere.
The mixture was stirred for 30 min and then evaporation of the
solvent to ca. 5 mL and addition of n-hexane gave complex 11 as an
orange solid. Yield, 0.083 g, 71%. C24H22Cl2FeN4O2Pd (629.95):
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Dalton Trans., 2010, 39, 4321–4330 | 4329
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4330 | Dalton Trans., 2010, 39, 4321–4330
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