Synthesis, structural characterization and electrochemistry of C,N-chelated organotin(IV) dicarboxylates with ferrocenyl substituents

Article abstract of DOI:10.1016/j.jorganchem.2011.02.005

A set of C,N-chelated organotin(IV) ferrocenecarboxylates, [L ^CN(n-Bu)Sn(O₂CFc)₂] (1), [(L^CN) ₂Sn(O₂CFc)₂] (2), [L^CN(n-Bu) Sn(O₂CCH₂Fc)₂

Full text of DOI:10.1016/j.jorganchem.2011.02.005

Journal of Organometallic Chemistry 696 (2011) 1809e1816
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, structural characterization and electrochemistry of C,N-chelated
organotin(IV) dicarboxylates with ferrocenyl substituents
a
a
b
a
,
a
ꢀ
ꢀ
ꢀ
*
ꢀ
ꢀ
ꢀ
ꢀ ꢁꢀ ꢀ
ꢀ
Petr Svec , Zdenka Padelková , Petr Stepnicka , Ales Ruzicka , Jaroslav Holecek
a Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 95, CZ-532 10, Pardubice, Czech Republic
b Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, CZ-128 40 Prague, Czech Republic
a r t i c l e i n f o
a b s t r a c t
A set of C,N-chelated organotin(IV) ferrocenecarboxylates, [LCN(n-Bu)Sn(O2CFc)2] (1), [(LCN)2Sn(O2CFc)2]
(2), [LCN(n-Bu)Sn(O2CCH2Fc)2] (3), [LCN(n-Bu)Sn(O2CCH2CH2Fc)2] (4), [LCN(n-Bu)Sn(O2CCH]CHFc)2] (5),
[LCN(n-Bu)Sn(O2CfcPPh2)2] (6), [(LCN)2Sn(O2CfcPPh2)2] (7), and [LCN(n-Bu)2Sn(O2CFc)] (8) (LCN ¼ 2-(N,N-
dimethylaminomethyl)phenyl, Fc ¼ ferrocenyl and fc ¼ ferrocene-1,10-diyl) has been synthesized by
metathesis of the respective organotin(IV) halides and carboxylate potassium salts and characterized by
multinuclear NMR and IR spectroscopy. The spectral data indicated that the tin atoms in diorganotin(IV)
dicarboxylates bearing one C,N-chelating ligand (1 and 3-6) are seven-coordinated with a distorted
pentagonal bipyramidal environment around the tin constituted by the n-butyl group, the chelating LCN
ligand and bidentate carboxylate. Compounds 2 and 7 possessing two chelating LCN ligands comprise
octahedrally coordinated tin atoms and monodentate carboxylate donors, whereas compound 8 assumes
a distorted trigonal bipyramidal geometry around tin with the carboxylate binding in unidentate fashion.
The solid state structures determined for 1,C6D6 and 2 by single-crystal X-ray diffraction analysis are in
agreement with spectroscopic data. Compounds 1, 3e5, and 8 were further studied by electrochemical
methods. Whereas the oxidations of ferrocene units in bis(carboxylate) 2 and monocarboxylate 8
proceed in single steps, compound 1 undergoes two closely spaced one-electron redox waves due to two
independently oxidized ferrocenyl groups. The spaced analogues of 2, compounds 3e5, again display
only single waves corresponding to two-electron exchanged.
Article history:
Received 17 January 2011
Received in revised form
31 January 2011
Accepted 7 February 2011
Keywords:
Organotin(IV) carboxylates
C,N-chelating ligand
Ferrocene carboxylates
Crystal structure
NMR spectroscopy
Electrochemistry
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
to their structural versatility. Depending on the nature of the
carboxylic acid used and the stoichiometry of the reactants, several
Current research in the chemistry of triorganotin(IV) carboxyl-
ates is focused mainly on structural studies as well as on catalytic
and medicinal activity of these compounds [1e5]. The tin atom in
simple triorganotin(IV) carboxylates is four- (Scheme 1A) or five-
coordinated in the solid state. Compounds with pentacoordinated
tin atoms are particularly structurally variable because their
carboxylate moieties can bind in asymmetric bidentate (Scheme 1,
B), symmetric bidentate (Scheme 1, C) and bidentate-bridging
fashions (Scheme 1D). Infinite polymeric networks, found in the
solid state structures of compounds where the bidentate-bridging
mode operates, often fragment into oligomeric or monomeric
species in coordinating solvents [6].
products such as monomers, dimers, tetramers, oligomeric ladders,
and hexameric drum-like structures were isolated [7].
With our contributions to this field we have reported the
preparation and structural characterization of triorganotin(IV)
carboxylates resulting from 2-{[N-(2-oxo-2H-naphthalene-1-yli-
den)hydrazo]}benzoic acid. All these compounds were found to be
monomeric in solution, featuring four-coordinated tin atoms [8].
Furthermore, a series of bis(triorganotin(IV)) esters of 4-ketopi-
melic acid was synthesized, structurally characterized and tested
for fungicidal activity [9]. The structures and in vitro antifungal
activity were also studied for some C,N-chelated azo dye organotin
(IV) complexes [10]. All these C,N-chelated organotin(IV) carbox-
ylates featured monodentate carboxylate units in solution and in
the solid state. In other contributions, we focused on the prepara-
tion, structural characterization and catalytic activity of tri-, di- and
monoorganotin(IV) trifluoroacetates bearing C,N-chelating ligand
(s) [11], and also on the preparation and structures of organotin(IV)
acetates [12] and ferrocenecarboxylates [13] bearing additional
The corresponding diorganotin (IV) carboxylates have also been
extensively investigated over the last several decades, mainly due
* Corresponding author. Fax: þ420 466037151.
ꢁꢀ ꢀ
E-mail address: ales.ruzicka@upce.cz (A. Ruzicka).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.02.005

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
THF
O
R3Sn
O
O
R3Sn
O
O
R3Sn
Sn'
O
O
LCNRSnX2 + 2 R'COOK
C
R
C
R
C R'
LCNRSn(OC(O)R')2
'
'
R3Sn
R
'
- 2 KX
O
C
A
B
D
X = Cl or Br
Scheme 1. Possible structural motifs for triorganotin(IV) esters of carboxylic acids.
phosphorus substituents in the carboxylate part. As an extension of
our recent work, we report here on the reactivity of C,N-chelated
tri- and diorganotin(IV) halides [14] towards potassium carboxyl-
ates in situ generated from simple and phosphine-substituted
ferrocene carboxylic acids (Scheme 2).
R
R'
Fc
n-Bu
LCN
1
2
3
4
5
6
7
8
Fc
n-Bu
CH2Fc
2. Results and discussion
n-Bu
CH2CH2Fc
n-Bu (E)-CH=CHFc
2.1. C,N-Chelated organotin(IV) dicarboxylates with simple
ferrocenecarboxylic groups
n-Bu
LCN
dpf
dpf
Fc
The synthesis of C,N-chelated organotin(IV) carboxylates bearing
ferrocenyl substituents (Scheme 2) proceeded in two steps. The first
step involved the preparation of the corresponding potassium
carboxylate using equimolar amounts of potassium t-butoxide and
the respective carboxylic acid in anhydrous THF. Subsequent reac-
tion of these salts with selected C,N-chelated organotin(IV) halides
gave the desired products in satisfactory yields (isolated yields
58e81%, see Experimental). This reaction sequence appears to be
the only proper synthetic strategy, since similar reactions between
in situ generated lithium carboxylates failed to provide the desired
products while the n-butyl containing monoorganotin(IV) drum-
like hexamer [7d], resulting by a phenyl group migration process
[14b,15], has been obtained from the reaction of LCN(n-Bu)SnCl2
(LCN ¼ 2-(N,N-dimethylaminomethyl)phenyl) with two equivalents
of FcCOOLi. Likewise, the reactions of triorganotin(IV) hydrides
(prepared by the reaction of the respective triorganotin(IV) chloride
and K(BEt3)H [16]) with FcCOOH did not reach completion, afford-
ing mixtures of the starting triorganotin(IV) hydride and the desired
product in a molar ratio of ca. 1:2.
2n-Bu
Scheme 2. Preparation and numbering of compounds 1e8 (LCN ¼ 2-(N,N-dimethyl-
aminomethyl)phenyl, Fc
ferrocenecarboxylate).
¼
ferrocenyl, dpf
¼
10-(diphenylphosphino)-1-
for the doublet due to aromatic H(60) (
Scheme 3) is 98.5 Hz, which is within the range reported previously
for other C,N-chelated diorganotin(IV) compounds [14b,17]. Unfor-
tunately, the only 1H NMR resonance observable for the CH2NMe2
d
(1H) ¼ 8.48 ppm; see
pendant arm is the signal of the methyl groups at
d
(1H) ¼ 2.33 ppm,
the signal of the methylene group being obscured by the relatively
broad resonance assigned to protons of the Cp’ rings.
In the 13C{1H} NMR spectrum, a relatively broad, diagnostic signal
of the carboxyl group is seen at 183.1 ppm. This signal is accompanied
by the resonances due to ferrocene CH and Cipso. Whereas the reso-
nance of Cipso(Cp) is clearly seen at 73.5 ppm, the CH resonances are
Compounds 1e7 are all air-stable and do not appreciably react
with moisture. Their structures were established from multinuclear
NMR (in solution) and IR spectra, and confirmed by elemental
analysis. In addition, the solid-state structures of 1,C6D6 and 2 were
determined by single-crystal X-ray diffraction analysis.
Reddish brown single crystals of solvate 1,C6D6 were obtained
from a concentrated solution in C6D6. The crystal structure of this
compound (Fig. 1) reveals seven-coordinated tin atom with a dis-
torted pentagonal bipyramidal geometry. Two asymmetric biden-
tate carboxylate substituents (Sn1-O1 2.196(4) Å and Sn1-O2 2.495
(3) Å; Sn1-O3 2.189(3) Å and Sn1-O4 2.398(3) Å) are situated in the
equatorial plane of the pentagonal bipyramid together with the
nitrogen atom from the C,N-chelating ligand. Structural parameters
indicate a relatively strong intramolecular N/Sn interaction
(N1-Sn1 2.497(4) Å). Both tin-bound carbon atoms C1 (from the
C,N-chelating ligand) and C10 occupy axial positions with the angle
C1-Sn1-C10 being 165.3(2)ꢀ. The sum of the equatorial interatomic
angles is 360.15ꢀ, which indicates with coplanar arrangement of the
equatorial donor atoms. Both ferrocenyl moieties point in the same
direction with respect to the equatorial plane. Their cyclo-
pentadienyl rings are rotated from an eclipsed conformation by ca.
4ꢀ (Fe1) and 36ꢀ (Fe2), respectively, and show similar Fe-ring
centroid distances (range 1.63e1.66 Å) and negligible tilting (4.0
(5)ꢀ for Fe1 and 2.9(3)ꢀ for Fe2).
Fig. 1. Molecular structure of 1$C6D6. ORTEP view (50% probability level); benzene
molecule and hydrogen atoms are omitted for clarity. Selected interatomic distances
[Å] and angles [ꢀ]: Sn1-N1 2.497(4), Sn1-O1 2.196(4), Sn1-O2 2.495(3), Sn1-O3 2.189
(3), Sn1-O4 2.398(3), Sn1-C1 2.113(5), Sn1-C10 2.123(6), O1-C14 1.283(5), O2-C14 1.252
(6), O3-C25 1.278(6), O4-C25 1.261(6), N1-Sn1-O1 144.80(12), N1-Sn1-O2 90.37(12),
N1-Sn1-O3 133.65(13), N1-Sn1-O4 77.53(13), N1-Sn1-C10 90.71(18), C1-Sn1-C10 165.3
(2), O1-Sn1-O2 55.51(11), O1-C14-O2 120.5(4), O1-Sn1-O3 79.88(12), O2-Sn1-O4
167.75(11), O3-Sn1-O4 56.86(13), O3-C25-O4 119.4(4).
The structure of 1 in solution was studied by multinuclear NMR
spectroscopy (in C6D6). Both multiplicity and integral intensity of
signals in the 1H NMR spectrum are in agreement with the formu-
lation. The coupling constant 3J(119Sn, 1H) of the satellites observed

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
1811
Ph2P
are cis to one carboxylate groups and trans to another. The inter-
atomic distances Sn1-N1 (2.544(4) Å) and Sn1-N2 (2.613(5) Å)
slightly differ from each other but still are within the range expected
for intramolecular N/Sn interactions [8e10,12e14] In comparison
with 1, where both carboxylic moieties coordinated in anisobi-
dentate manner, the carboxylate moieties in 2 are bonded in mon-
odentate fashion (Sn1-O1 2.072(3) Å and Sn1-O2 3.252(3) Å;
Sn1-O3 2.059(4) Å and Sn1-O4 3.290(4) Å, respectively; see
Scheme 1). A possible bidentate coordination is prevented by the
two bidentate C,N-chelating ligands at the tin atom (Sn1-N1 2.544
(4) Å, Sn1-N2 2.613(5) Å, Sn1-C1 2.123(4) Å a Sn1-C10 2.126(5)Å).
The tin atom in 2 thus reveals a geometry similar to that found
previously for [(LCN)2Sn(OC(O)CF3)2] [11] and [(LCN)2SnX2] (X ¼ F, Cl,
Br, I) [14b,20]. Ferrocene cyclopentadienyls in 2 assume interme-
diate conformations, departing by ca. 2 (Fe2) and 12ꢀ (Fe1) from an
ideal eclipsed conformation. The ferrocene units exert negligible
tilts (max. 2.3(3)ꢀ) and similar Fe-ring centroid distances (1.643(3)
and 1.652(3) Å for Fe1, 1.631(2) and 1.630(2) Å for Fe2).
N(CH3)2
Sn
Cp'
Cp
Cp'
Cp
3'
5'
2'
1'
1
3
Fe
Fe
Fc
4'
4
2
Sn
6'
LCN
n-Bu
dpf
Scheme 3. General NMR numbering of organic substituents.
presumably overlapped, resulting in one broad signal at 71.7 ppm. In
the 119Sn{1H} spectrum, there is a single resonance at ꢁ386.0 ppm,
confirming the presence of only one tin-containing species in
benzene solution. The chemical shift value is typical for seven-coor-
dinated tin atoms bearing one C,N-chelating ligand and one n-Bu
substituent. Compared to the starting [LCN(n-Bu)SnCl2](
d
(
119Sn) w ꢁ107 ppm), the 119Sn resonance of 1 appears shifted to
lower frequencies, which again implicates an increase of the
coordination number of the tin atom from five to seven [18]. From the
data collected, it follows that both carboxylate ligands are bonded in
bidentate fashionbothinthesolidstateandinsolution. IRspectra[19]
are in agreement with this observation, showing the carboxylate
bands for neat 1 at 1544 and 1360 cmꢁ1, which again indicates
bidentate coordination of the carboxylate moieties [8,9].
The 1H NMR spectrum of 2 in a CDCl3 solution displays only one
set of signals due to the CH2N (
d
(1H) ¼ 3.59 ppm) and N(CH3)2
(d
(1H) ¼ 2.09 ppm) moieties, which indicates their equivalency in the
solution. This observation is in contrast with the previously dis-
cussed 1H NMR spectra of doubly C,N-chelated organotin(IV)
halides and related compounds, where an AX pattern is typically
seen for the CH2N protons and a broad signal found for the N(CH3)2
groups [14b]. On the other hand, we have found that [(LCN)2Sn(OC
(O)CF3)2] has a different 1H NMR response since only one signal is
As mentioned above compound 1 is air-stable and does not react
with water. This was proven simply by adding few drops of D2O to
the NMR tube containing benzene-d6 solution of 1. The spectra
recorded after mixing for 5 min were identical with those of 1.
The reaction of [(LCN)2SnBr2] with two equivalents of FcCOOK as
described above produced [(LCN)2Sn(OC(O)Fc)2] (2), which was
isolated as an orange crystalline solid in a 71% isolated yield. Single
crystals suitable for the X-ray diffraction analysis were grown from
a THF solution at ꢁ30 ꢀC. The crystal structure (Fig. 2) reveals the
central tin atom in 2 to be six-coordinated with highly distorted
octahedral environment around tin and two carbon atoms of the LCN
ligands located trans to each other. The N atoms of each LCN ligand
detected for the CH2N fragment (
d
(1H) ¼ 3.73 ppm in THF-d8) and
two broad resonances are observed for non-equivalent N(CH3)2
groups [11]. The expected doublet of H(60) (
d
(1H) ¼ 8.42 ppm) in the
spectrum of 2 is somewhat broadened but still exhibits tin satellites
with coupling constant 3J(119Sn, 1H) of ca. 87 Hz, which is a typical
value for diorganotin(IV) compounds bearing C,N-chelating ligand
(s). There are also three expected resonances due to protons in the
equivalent ferrocenyl moieties. The resonance at 4.19 ppm was
assigned to protons of unsubstituted Cp’ rings while the other two
signals at 4.24 and 4.77 ppm were attributed to protons at the
substituted ring. A relatively broad signal of the OC(O) fragment at
174.2 ppm in the 13C{1H} NMR spectrum suggests the presence of
two equivalent monodentate carboxylates (bidentate carboxylic
substituents exhibit this signal shifted to about 180 ppm) [8,9,11].
Neither the resonance of the C10 carbon [21] nor the signal attrib-
utable to Cipso(Cp) could be indentified owing to their low intensity
or overlaps.
A single resonance observed in the 119Sn{1H} NMR spectrum of
2 at ꢁ375.2 ppm ultimately confirms the existence of one tin-
containing species in the solution. This chemical shift is typical for
the six-coordinated tin bearing two C,N-chelating ligands [11,14b],
which in turn indicates that the monodentate coordination of the
FcCO2 units as observed in the solid state is maintained even in the
solution. The IR spectrum (Nujol mull) of 2 exhibits two strong
carboxylate bands at 1655 cmꢁ1
(
nas(COO)) and 1316 cmꢁ1
(
ns(COO)). The difference between the nas(COO) and ns(COO)
vibrations (>300 cmꢁ1) is in agreement with monodentate coor-
dination of the carboxylate moieties and thus corresponds with
the X-ray structure and NMR data.
In analogy to compound 2, another three C,N-chelated di-
organotin(IV) carboxylates were prepared from ferrocenecarbox-
ylic acids having a hydrocarbon spacer inserted between the
ferrocenyl and carboxyl groups (compounds 3e5 in Scheme 2), and
isolated in good yields as very viscous oils or microcrystalline
solids.
NMR data of 3-5 as obtained in benzene-d6 solutions corre-
sponded with the formulated structures. The 1H NMR spectrum of
3 showed broad unresolved signals in both the aromatic and
Fig. 2. Molecular structure of 2. ORTEP plot at 50% probability level; hydrogen atoms
are omitted for clarity. Selected interatomic distances [Å] and angles [ꢀ]: Sn1-N1 2.544
(4), Sn1-N2 2.613(5), Sn1-O1 2.072(3), Sn1-O2 3.252(3), Sn1-O3 2.059(4), Sn1-O4
3.290(4), Sn1-C1 2.123(4), Sn1-C10 2.126(5), O1-C19 1.298(6), O2-C19 1.216(6), O3-C30
1.290(6), O4-C30 1.218(6), N1-Sn1-O3 164.79(12), N2-Sn1-O1 165.64(13), C1-Sn1-C10
155.77(19), N1-Sn1-N2 102.70(12), O1-Sn1-O3 99.82(13), O1-Sn1-N1 80.08(12), O3-
Sn1-N2 81.22(14).

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
aliphatic regions. Nevertheless, all signals of the C,N-chelating
a pattern similar to those of 2. The doublet of the H(60) (
d
ligand (
d
(1H) ¼ 8.21, 7.17 and 6.85 ppm for the phenyl ring;
d
(1H) ¼ 8.66 ppm) is broadened but still exhibits clearly discernible
tin satellites with 3J(119Sn, 1H) z 90 Hz. Signals of the remaining
C6H4 protons are overlapped by the resonance of the PPh2 moieties.
Signals of the CH2NMe2 pendant arm (NCH2: 3.12 ppm, NMe2:
1.74 ppm) and the cyclopentadienyl protons are found within the
expected range. More importantly, the position of the carboxylate
(1H) ¼ 3.28 and 2.18 ppm, for CH2N and N(CH3)2 moieties,
respectively), the butyl group and the carboxylate ligands were
identified. The single resonance at 183.1 ppm in the 13C NMR
spectrum suggests bidentate coordination and equivalency of the
carboxylate moieties. Together with the only 119Sn NMR signal at
ꢁ388.3 ppm, this indicates that the tin atom in 3 has the same
coordination geometry as in 1 (i.e., a distorted pentagonal bipyr-
amid). The IR spectrum of neat 3 also corroborates the presence of
bidentate carboxylate donors.
signal (
d
(
13C) ¼ 173.2 ppm) indicates monodentate coordination
and equivalency of the carboxylic substituents, whilst the single 31P
NMR resonance observed at
d
(
31P) ¼ ꢁ17.9 ppm clearly suggests the
phosphorus groups to remain uncoordinated. The presence of only
The NMR response of reddish brown oily [LCN(n-Bu)Sn(OC(O)
CH2CH2Fc)2] (4) is similar to that of 1 and 3, the important dis-
tinguishing features being the presence of resonances due to the
one tin-containing species in solution is proven by the 119Sn NMR
spectrum, showing one resonance at
d
(
119Sn) ¼ ꢁ370.0 ppm, which
is close to that of compound 2. Based on the NMR data, one can
suggest a pseudo-octahedral coordination environment around the
tin atom for 7, similar to that described for compound 2. The
presence of monodentate carboxylates is confirmed by IR spec-
troscopy, showing nas(COO) and ns(COO) bands separated by more
CH2CH2 linkers (
d
(1H) ¼ 2.74 and
d
(
13C) ¼ 30.1 ppm for FcCH2 and
d
(1H) ¼ 2.61 and
d
(
13C) ¼ 36.4 ppm for CH2CO2). Similarly to 1 and 3,
the position of the carboxylate signal (
d(
13C) ¼ 184.8 ppm) and the
119Sn NMR signal (
d(
119Sn) ¼ ꢁ390.0 ppm) suggest bidentate
coordination of the carboxylate donors, which is in line with the IR
spectrum.
than 300 cmꢁ1
.
Contrary to 3 and 4, the 1H NMR spectrum of [LCN(n-Bu)Sn
(O2CCH]CHFc)2] (5) displays narrow, nicely resolved signals,
allowing for a complete interpretation. The value of 3J(119Sn,
1H) ¼ 98.8 Hz for tin-satellites flanking the doublet of the aromatic
2.3. The related C,N-chelated organotin(IV) monocarboxylate 8
Triorganotin(IV) carboxylate [LCN(n-Bu)2Sn(O2CFc)] (8) was
synthesized similarly to compounds mentioned above by reacting
[LCN(n-Bu)2SnCl] with one equivalent of FcCOOK and was isolated
as a reddish brown oily product in a 73% yield.
According to NMR spectra one can assume that the central tin
atom in 8 is five-coordinated (in benzene-d6) and has a distorted
trigonal bipyramidal geometry as found previously for C,N-chelated
triorganotin(IV) compounds [LCNR2SnX], where R ¼ n-Bu or Ph, and
X ¼ F, Cl, Br, OCOCF3 [11,23]. The 1H NMR spectrum of 8 displays the
expected signals of the LCN and butyl groups. However, the 1H
H(60) (
d
(1H) ¼ 8.41 ppm) is within the range reported previously for
C,N-chelated diorganotin(IV) compounds [14b,17]. A typical pattern
is found also for the CH]CH group, namely a pair of doublets (
d
(1H) ¼ 7.87 ppm for CH ¼ CHFc,
d
(1H) ¼ 6.32 ppm for O2CCH ¼ CH)
with 3J(1H, 1H) coupling constant of 15.7 Hz, which corroborates
(E)-geometry at the double bond. The resonance of the CH2N
fragment was not identified, probably due to overlaps with the
relatively broad resonance due to Cp’ protons. On the other hand,
the signal of the N(CH3)2 moiety was clearly seen at 2.37 ppm
together with a typical pattern of the n-Bu substituent in the
aliphatic region of the 1H NMR spectrum.
chemical shifts of CH2N protons (
from that of 1 (
for the signal of NMe2 group (
d
(1H) ¼ 3.12 ppm) differs greatly
d
(CH2N) ¼ 4.24 ppm) and a similar trend is seen also
d
(1H) ¼ 1.80 ppm; for 1:
d
The 13C NMR spectrum of 5 displays the C]O signal at
178.1 ppm, shifted to lower frequencies when compared to the
corresponding resonances in 3 or 4 due to conjugation. Signals of
the double bond carbons are seen at 145.8 ppm (CH]CHFc) and
117.1 ppm (O2CCH]CH). The 119Sn NMR signal at ꢁ391.0 ppm
suggests a seven-coordinated tin species to be present in solution.
(1H) ¼ 2.31 ppm). The coupling constant 3J(119Sn, 1H) ¼ 53.5 Hz
observed for the satellites around the H(60) signal is characteristic
for C,N-chelated triorganotin(IV) compounds [17a,23a].
The position of the signal of the carboxyl fragment
(d
(
13C) ¼ 175.2 ppm in C6D6) implies monodentate coordination of the
carboxylato ligand, which is in accordance with the position of the
carboxylate bands in the IR spectrum (nas(COO) ¼ 1636 cmꢁ1 and
ns(COO) ¼ 1321 cmꢁ1; difference > 300 cmꢁ1). Finally, the 119Sn
NMR spectrum suggests the presence of five-coordinated tin centre,
2.2. C,N-Chelated organotin(IV) dicarboxylates bearing
10-(diphenylphosphino)ferrocen-1-yl moieties
showing a single resonance at
d
(
119Sn) ¼ ꢁ92.2 ppm. The 119Sn NMR
In addition to simple carboxylates, two C,N-chelated diorganotin
(IV) carboxylatates 6 and 7 (Scheme 2) were prepared from 10-
(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) [22].
Compound [LCN(n-Bu)Sn(O2CfcPPh2)2] (6; fc ¼ ferrocene-1,10-diyl)
was isolated as an orange crystalline solid. Its 1H NMR spectrum is
similar to that of 1. However, the presence of the PPh2 moieties
leads to a differentiation of all cyclopentadienyl protons and
appearance of a broad multiplet near 7.40 ppm, which overlaps
with the signals of the C,N-chelating ligand. The presence of the
phosphorus substituent is clearly manifested in the 31P NMR
signals of 8 appears shifted by ca. 45 ppm to lower frequencies
compared to the starting [LCN(n-Bu)2SnCl] (
d(
119Sn) ¼ ꢁ48.5 ppm in
C6D6), which is a trend already noted for other, chemically related
C,N-chelated organotin(IV) carboxylates [12].
Table 1
Summary of electrochemical data for 1, 3e5, and 8.a
Compound
E [V]b
D
Ep [mV]c
1
2
3
4
5
8
Epa ¼ 0.250, Epc ¼ 0.110
Eꢀ0 ¼ 0.075
ed
spectrum, showing a singlet at
d
(
31P) ¼ ꢁ16.8 ppm, which is close
85
ca. 125
85
90
75
Eꢀ0 ¼ 0.035
to Hdpf itself [22a]. Likewise 1, the position of the resonance due to
the carboxyl group in 6 (182.7 ppm) indicates its bidentate coor-
dination while the 119Sn NMR spectrum suggest the presence of
Eꢀ0 ¼ 0.050
Eꢀ0 ¼ 0.110
Eꢀ0 ¼ 0.080
seven-coordinated tin species in solution (
d(
119Sn) ¼ ꢁ388.2 ppm).
a
In 1,2-dichloroethane in the presence of 0.1 M Bu4N[PF6] supporting electrolyte.
The IR spectrum supports the formulation, showing two carbox-
ylate bands with nas(COO) e ns(COO) < 200 cmꢁ1
.
Values versus ferrocene/ferrocenium reference (see Experimental).
b
Epa/Epc are anodic/cathodic peak potentials. Eꢀ0
¼
½(Epa
þ
Epc); scan
Compound [(LCN)2Sn(O2CfcPPh2)2] (7) was isolated as reddish
brown microcrystalline solid in 79% yield. The NMR resonances
attributed to protons at the C,N-chelating ligands constitute
rate ¼ 200 mV sꢁ1
.
.
c
D
Ep ¼ Ep ꢁ Epc
d
Two convoluted waves.

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
1813
stepwise manner indicates their electronic communication (prob-
ably through-space). An introduction of a spacer unit between the
ferrocenyl moiety and the carboxylate group in type-1 compounds
(i.e., in carboxylates 3-5) changes this redox response so that it
limits to the case of identical non-communicating redox centres
(such in 2) and, hence, a standard redox wave with an intensity
corresponding to an overall two-electron exchange is observed.
Besides, the spacer unit causes the ferrocene/ferrocenium redox
wave to shift along the potential axis depending on its electronic
influence (Eꢀ0: 5 >> 3 > 4).
3. Conclusion
Potassium carboxylates prepared in situ from ferrocenecarbox-
ylic acid and its analogues bearing a spacer between the carboxyl
group and the ferrocene unit react smoothly with [LCN(n-Bu)SnX2]
or [(LCN)2SnX2] (X ¼ Cl or Br) to afford the respective bis-carbox-
ylates 1e5. Structures of these compounds (particularly the coor-
dination environment around tin) changes with the number of the
C,N-chelating organic groups (LCN): Compounds bearing only one
LCN moiety feature seven-coordinated tin centres and bidentate
carboxylate ligands while that with two LCN groups (compound 2)
Fig. 3. Cyclic voltammograms of compounds 1, 4, 5, and 8 as recorded in 1,2-dichlo-
roethane on a platinum disc electrode at scan rate 0.20 V sꢁ1. The potentials are given
relative to ferrocene/ferrocenium. For details, see Experimental.
comprises
a six-coordinated tin atom. Similar situation was
2.4. Electrochemistry
observed for compounds prepared from Hdpf (compounds 6 and 7)
as the phosphorus groups do not coordinate the tin centres in
either intra- or intermolecular fashion. The related triorganotin(IV)
monocarboxylate 8 assumes trigonal bipyramidal geometry with
monodentate carboxylate ligand. The redox properties of the
compounds depend on the overall structure and the nature of the
spacer group which separates the redox active ferrocenyl units
from the tin bonded carboxylate. The spacer not only influences the
value of the redox potential of the ferrocene/ferrocenium couple
but also a possible communication in compounds possessing two
equivalent redox-active pendants.
Compounds [LCN(n-Bu)Sn(O2C-Y-Fc)2] (1, Y ¼ none; 3, Y ¼ CH2;
4, Y ¼ CH2CH2; and 5, Y ¼ (E)eCH]CH), [(LCN)2Sn(O2CFc)2] (2) and
the monocarboxylate [LCN(n-Bu)2Sn(O2CFc)] (8) have been studied
by cyclic and differential pulse voltammetry on platinum disc
electrode in 1,2-dichloroethane. Because of the presence of the
redox active ferrocenyl groups, attention was paid mainly to anodic
region, where the oxidation of the ferrocene units takes place. The
pertinent data are summarized in Table 1; selected voltammograms
are presented in Figs. 3 and 4.
Monocarboxylate 8 expectedly undergoes a single reversible,
one-electron oxidation attributable to the ferrocene/ferrocenium
couple. A similar behavior is observed for compound 2, which
displays one reversible redox wave attributable to simultaneous
oxidation of both ferrocenyl units at a potential very similar to that
of 8 (Table 1). In contrast, the oxidation of compound 1 proceeds in
two closely spaced one-electron steps (see Figs. 3 and 4). The fact
that the chemically equivalent ferrocene units of 1 are oxidized in
4. Experimental
4.1. Materials and methods
All reactions were carried out under argon using standard
Schlenk techniques if not described otherwise. [LCN(n-Bu)2SnCl]
[24], [LCN(n-Bu)SnCl2] [24], [(LCN)2SnBr2] [14b], Hdpf [22a],
FcCH2COOH [25], FcCH2CH2COOH [26] and (E)-FcCH ¼ CHCOOH
[27] were prepared according to published procedures. t-BuOK
(97%), FcCOOH (97%) and all solvents were obtained from
commercial sources (SigmaeAldrich). THF was dried by distillation
from sodium-potassium alloy, degassed and stored over a potas-
sium mirror.
Solution NMR spectra (see Scheme 3) were recorded with
a Bruker Avance 500 spectrometer at 500.13 MHz (1H), 125.76 MHz
(
13C{1H}), 202.45 MHz (31P{1H}), and 186.50 MHz (119Sn{1H}) at
ambient temperature. The solutions were obtained by dissolving of
approximately 40 mg of the analyzed compound in 0.6 ml of
deuterated solvent. Chemical shifts in the 1H and 13C NMR spectra
are given relative to residual signals of the solvent (CDCl3: 7.27 ppm
for 1H and 77.2 ppm for 13C; benzene-d6: 7.16 ppm for 1H and
128.4 ppm for 13C). 31P and 119Sn NMR data are referenced to
external H3PO4
stannane (
(
d
(
31P) ¼ 0.0 ppm) and external neat tetramethyl-
d
(
119Sn) ¼ 0.0 ppm), respectively. The 119Sn NMR spectra
were measured in the inverse gated-decoupling mode. IR spectra
were recorded with a Nicolet 7600 FT IR spectrometer. Melting
points were determined on a Kofler block and are uncorrected.
Electrochemical measurements were performed with
Fig. 4. Differential pulse voltammograms of 1, 4, 5, and 8 as recorded in 1,2-dichlo-
roethane on a platinum disc electrode with a 5 mV step and modulation amplitude of
50 mV. The potentials are given relative to ferrocene/ferrocenium. For details, see
Experimental.
a computer-controlled potentiostat
Netherlands) at room temperature using a standard Metrohm
mAUTOLAB III (Eco Chemie,

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
three-electrode cell equipped with a platinum disc electrode
(AUTOLAB RDE, 3 mm diameter) as the working electrode, plat-
inum sheet auxiliary electrode, and saturated calomel reference
electrode (SCE), which was separated from the analyzed solution by
a salt-bridge (0.1 M Bu4N[PF6] in 1,2-dichloroethane). The analyzed
compounds were dissolved in 1,2-dichloroethane (anhydrous,
SigmaeAldrich) to give a solution containing ca. 7.5 ꢂ 10ꢁ4 M of the
analyzed compound and 0.1 M Bu4N[PF6] (Fluka, purissimum for
electrochemistry) as the supporting electrolyte. The solutions were
degassed with argon before the measurement and then kept under
an argon blanket. The redox potentials were internally referenced
to decamethylferrocene/decamethylferrocenium [28] and the
values then converted to the conventional ferrocene/ferrocenium
scale by subtracting 0.548 V, which as the redox potential of dec-
amethylferrocene/decamethylferrocenium vs. ferrocene/ferroce-
nium [29].
SnCl2] (122 mg, 0.32 mmol). Reddish oily product was obtained.
Yield: 147 mg (58%). 1H NMR (C6D6, 295 K, ppm): 8.21 (br, 1H, H
(60)); 7.17 (br, 2H, LCN); 6.85 (br, 1H, H(30)); 4.15 (br, 2H, H(Cp)); 3.91
(br, 14H, H(Cp and Cp’)); 3.57 (br, 4H, OC(O)CH2); 3.28 (br, 2H,
CH2N); 2.18 (br, 6H, N(CH3)2); 1.83 (br, 2H, H(1)); 1.71 (br, 2H, H(2));
1.42 (br, 2H, H(3)); 0.95 (br, 3H, H(4)). 13C NMR (C6D6, 295 K, ppm):
183.1 (OC(O)); 146.7 (C20); 140.6 (C10); 134.5 (C60); 129.6 (C40);
127.0 (C30); 82.2 (Cipso(Cp)); 69.0 (br, Cp and Cp’); 67.9 (br, Cp’); 63.9
(CH2N); 46.0 (N(CH3)2); 36.0 (OC(O)CH2); 28.0 (C2); 26.8 (C3); 25.9
(C1); 14.2 (C4); the signal of C50 is overlapped by the resonance of
benzene-d6. 119Sn NMR (C6D6, 295 K, ppm): ꢁ388.3. IR (neat,
cmꢁ1): 1563 (vs, nas(COO)); 1360 (m, ns(COO)). Elemental analysis
(%): found C, 56.2; H, 5.8; N,1.5. Calcd. for C37H43Fe2NO4Sn (796.14):
C, 55.82; H, 5.44; N, 1.76.
4.5. Preparation of [LCN(n-Bu)Sn(O2CCH2CH2Fc)2] (4)
4.2. Preparation of [LCN(n-Bu)Sn(O2CFc)2] (1)
The synthesis was carried out as above with FcCH2CH2COOH
(315 mg, 1.22 mmol), t-BuOK (141 mg, 1.22 mmol) and [LCN(n-Bu)
SnCl2] (232 mg, 0.61 mmol). Reddish brown oily product was
obtained. Yield: 347 mg (69%). 1H NMR (C6D6, 295 K, ppm): 8.29 (d,
1H, H(60), 3J(1H(50),1H(60)) ¼ 5.5 Hz), 3J(119Sn,1H) z 90 Hz)); 7.22 (br,
2H, LCN); 6.95 (d, 1H, H(30), 3J(1H(40), 1H(30)) ¼ 7.1 Hz)); 4.01 (br, 10H,
H(Cp’)); 3.95 (br, 8H, H(Cp)); 3.57 (br, 2H, CH2N); 2.74 (br, 4H,
CH2CH2Fc); 2.61 (br, 4H, OC(O)CH2CH2); 2.32 (br, 6H, N(CH3)2); 1.88
(br, 2H, H(1)); 1.42 (br, 2H, H(2)); 1.24 (br, 2H, H(3)); 1.04 (br, 3H, H
(4)). 13C NMR (C6D6, 295 K, ppm): 184.8 (OC(O)); 146.5 (C20); 140.5
(C10); 134.4 (C60); 129.4 (C40); 126.9 (C30); 88.4 (Cipso(Cp)); 68.7 (Cp’);
68.3 (Cp); 67.5 (Cp); 63.7 (CH2N); 46.0 (N(CH3)2; 36.4 (OC(O)CH2);
30.1 (CH2Fc); 27.9 (C2); 26.8 (C3); 25.8 (C1); 14.1 (C4); the signal of
C50 is overlapped by the resonance of benzene-d6. 119Sn NMR (C6D6,
295 K, ppm): ꢁ390.0. IR (Nujol mull, cmꢁ1): 1557 (vs, nas(COO));
1362 (m, ns(COO)). Elemental analysis (%): found C, 57.1; H, 6.0; N,1.6.
Calcd. for C39H47Fe2NO4Sn (824.20): C, 56.84; H, 5.75; N, 1.70.
A suspension of t-BuOK (201 mg, 1.74 mmol) in THF (20 ml) was
added to a solution of FcCO2H (413 mg, 1.74 mmol) in THF (20 ml).
The reaction mixture was stirred for 1 h to complete precipitation
of FcCO2K. Then, a solution of [LCN(n-Bu)SnCl2] (331 mg, 0.87 mmol)
in THF was introduced in one portion, whereupon the color of the
reaction mixture changed rapidly from orange to reddish brown.
The following operations were performed in the air. The precipi-
tated KCl was filtered off and the filtrate was evaporated to dryness
in vacuo giving 1 as a reddish brown crystalline solid. Further
purification was not necessary. Yield: 540 mg (81%). M.p.
189e191 ꢀC. 1H NMR (C6D6, 295 K, ppm): 8.48 (d, 1H, H(60), 3J(1H
(50), 1H(60)) ¼ 7.0 Hz), 3J(119Sn, 1H) ¼ 98.5 Hz); 7.20 (m, 1H, H(50));
7.11 (t,1H, H(40)); 6.88 (d,1H, H(30), 3J(1H(40), 1H(30)) ¼ 7.4 Hz)); 5.02
(br d, 4H, H(Cp)); 4.02 (br, 6H, CH2N and H(Cp)); 3.93 (br, 10H, H
(Cp’)); 2.33 (s, 6H, N(CH3)2); 1.99 (m, 2H, H(1)); 1.86 (m, 2H, H(2));
1.37 (m, 2H, H(3)); 0.83 (t, 3H, H(4)). 13C NMR (C6D6, 295 K, ppm):
183.1 (br, OC(O)); 147.3 (C20); 141.1 (C10); 135.0 (C60); 130.0 (C40);
129.0 (C50); 127.3 (C30); 73.5 (br, Cipso(Cp)); 71.7 (br, Cp); 70.3 (Cp’);
64.1 (CH2N); 46.5 (N(CH3)2); 28.9 (C2); 28.7(C3); 27.2 (C1); 14.2
(C4). 119Sn NMR (C6D6, 295 K, ppm): ꢁ386.0. IR (Nujol mull, cmꢁ1):
1544 (vs, nas(COO)); 1360 (s, ns(COO)). Elemental analysis (%): found
C, 55.0; H, 5.4; N, 1.7. Calcd. for C35H39Fe2NO4Sn (768.09): C, 54.73;
H, 5.12; N, 1.82.
4.6. Preparation of [LCN(n-Bu)Sn(O2CCH]CHFc)2] (5)
Compound 5 was obtained similarly form (E)-FcCH]CHCOOH
(270 mg, 1.05 mmol), t-BuOK (122 mg, 1.05 mmol) and [LCN(n-Bu)
SnCl2] (201 mg, 0.53 mmol). Reddish brown crystalline product was
obtained. Yield: 250 mg (58%). M.p. 88e90 ꢀC. 1H NMR (C6D6, 295 K,
3
1
ppm): 8.41 (d, 1H, H(60), J(1H(50), H(60)) ¼ 7.3 Hz), 3J(119Sn,
1H) ¼ 98.8 Hz)); 7.87 (d, 2H, CH]CHFc, 3J(1H,1H) ¼ 15.7 Hz); 7.16 (m,
4.3. Preparation of [(LCN)2Sn(O2CFc)2] (2)
1H, H(50)); 7.07 (t, 1H, H(40)); 6.85 (d, 1H, H(30), J(1H(40), 1H
3
(30)) ¼ 7.4 Hz)); 6.32 (d, 2H, OC(O)CH]CH, 3J(1H,1H) ¼ 15.7 Hz); 4.11
(s, 4H, H(Cp)); 3.97 (s, 4H, H(Cp)); 3.80 (br, 12H, H(Cp’) and CH2N);
2.37 (s, 6H, N(CH3)2); 2.06 (m, 2H, H(1)); 1.91 (m, 2H, H(2)); 1.46 (m,
2H, H(3)); 0.93 (t, 3H, H(4)). 13C NMR (C6D6, 295 K, ppm): 178.1 (OC
(O)); 147.1 (C20); 145.8 (CH]CHFc); 140.5 (C10); 134.4 (C60); 129.2
(C40); 126.9 (C30); 117.1 (OC(O)CH]CH); 79.5 (Cipso(Cp)); 70.7 (Cp);
69.8 (Cp’); 68.7 (Cp); 64.0 (CH2N); 46.1 (N(CH3)2; 30.1 (C2); 28.3(C3);
28.1 (C1); 14.2 (C4); the signal of C50 is overlapped by the resonance
of the solvent.119Sn NMR (C6D6, 295 K, ppm): ꢁ391.0. IR (Nujol mull,
cmꢁ1): 1636 (vs, nas(COO)); the band of ns(COO) is obscured by Nujol
bands. Elemental analysis (%): found C, 57.4; H, 5.5; N, 1.6. Calcd. for
C39H43Fe2NO4Sn (820.17): C, 57.11; H, 5.28; N, 1.71.
The synthesis of 2 was carried out as described above starting
with FcCO2H (510 mg, 2.16 mmol), t-BuOK (249 mg, 2.16 mmol) and
[(LCN)2SnBr2] (588 mg, 1.08 mmol). Orange crystalline product was
obtained. Yield: 648 mg (71%). M.p. > 220 ꢀC (dec.). 1H NMR (CDCl3,
295 K, ppm): 8.42 (br, 2H, H(60), 3J(119Sn, 1H) z 87 Hz); 7.46 (m, 2H,
3
H(50)); 7.34 (t, 2H, H(40)); 7.13 (d, 2H, H(30), J(1H(40), 1H
(30)) ¼ 7.5 Hz), 4J(119Sn, 1H) ¼ 39.9 Hz); 4.77 (s, 4H, H(Cp)); 4.24 (s,
4H, H(Cp)); 4.19 (s, 10H, H(Cp’)); 3.59 (s, 4H, CH2N); 2.09 (s, 12H, N
13
(CH3)2). C NMR (CDCl3, 295 K, ppm): 174.2 (OC(O)); 141.4 (C20);
136.9 (C60); 129.7 (C40); 128.3 (C50); 127.6 (C30); 70.7 (Cp); 70.3
(Cp); 69.7 (Cp’); 64.9 (CH2N); 46.4 (N(CH3)2); the resonances for the
C10 and Cipso(Cp) atoms were not found. 119Sn NMR (CDCl3, 295 K,
ppm): ꢁ 375.2. IR (Nujol mull, cmꢁ1): 1655 (s, nas(COO)); 1316 (s,
ns(COO)). Elemental analysis (%): found C, 57.1; H, 5.2; N, 3.2. Calcd.
for C40H42Fe2N2O4Sn (845.18): C, 56.85; H, 5.01; N, 3.31.
4.7. Preparation of [LCN(n-Bu)Sn(O2CfcPPh2)2] (6)
Starting with Hdpf (240 mg, 0.58 mmol), t-BuOK (68 mg,
0.58 mmol) and [LCN(n-Bu)SnCl2] (110 mg, 0.29 mmol), the proce-
dure described in detail for 1 afforded compound 6 as an orange
crystalline solid. Yield: 202 mg (61%). M.p. 81e83 ꢀC. 1H NMR (C6D6,
295 K, ppm): 8.44 (d, 1H, H(60), 3J(1H(50), 1H(60)) ¼ 7.0 Hz), 3J(119Sn,
1H) ¼ 98.7 Hz); 7.40 (br d, 8H, PPh2); 7.16e7.05 (m, 8H, PPh2 and
4.4. Preparation of [LCN(n-Bu)Sn(O2CCH2Fc)2] (3)
Compound 3 was prepared analogously from FcCH2COOH
(156 mg, 0.64 mmol), t-BuOK (74 mg, 0.64 mmol) and [LCN(n-Bu)

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P. Svec et al. / Journal of Organometallic Chemistry 696 (2011) 1809e1816
1815
3
LCN); 7.02 (m, 6H, PPh2 and LCN); 6.74 (d, 1H, H(30), J(1H(40), 1H
(30)) ¼ 7.3 Hz)); 4.98 (br d, 4H, H(Cp)); 4.17 (br, 2H, H(Cp’)); 4.09 (br,
2H, H(Cp’)); 4.02 (br, 6H, H(Cp and Cp’)); 3.79 (s, 2H, H(Cp’)); 3.62 (s,
2H, CH2N); 2.32 (s, 6H, N(CH3)2); 1.94 (m, 2H, H(1)); 1.83 (m, 2H, H
(2)); 1.32 (m, 2H, H(3)); 0.78 (t, 3H, H(4)). 13C NMR (C6D6, 295 K,
ppm): 182.7 (OC(O)); 147.4 (C20); 141.1 (C10); 140.2 (d, Cipso(Ph), 1J
compound at ꢁ30 ꢀC. The diffraction data were obtained at 150 K
using Oxford Cryostream low-temperature device and a Nonius
KappaCCD diffractometer using graphite-monochromatized MoK
a
radiation (
l
¼ 0.71073 Å). Data reductions were performed with
DENZO-SMN [30] and the data were corrected for absorption by
integration methods [31]. The structures were solved by direct
methods (Sir-92) [32] and refined by full matrix least-squares
based on F2 (SHELXL97) [33]. Hydrogen atoms were mostly local-
ized on a difference Fourier maps. However to ensure uniformity in
the treatment of the crystal structures, all hydrogen atoms were
recalculated into idealized positions (riding model) and assigned
temperature factors Uiso(H) ¼ 1.5Ueq(pivotal atom) for methyl
groups and 1.2Ueq for all other with CeH ¼ 0.96, 0.97, and 0.93 Å for
methyl, methylene and aromatic hydrogen atoms, respectively, and
0.82 Å for NeH and OeH protons. The molecule of 1$C6D6 reveals
a disordered n-butyl group. The disorder was treated using
constraint and restraint options available in SHELXL-97 software.
Besides, one of the unsubstituted Cp rings in each 1 and 2 of are
disordered and were refined with planar aromatic arrangements.
Crystallographic data for 1$C6D6, C41H45Fe2NO4Sn, M ¼ 846.17,
monoclinic, P21/c, a ¼ 11.1430(12), b ¼ 12.6761(10), c ¼ 28.1690(14)
(
31P, 13Cipso) ¼ 10.0 Hz); 140.0 (d, Cipso(Ph), 1J(31P, 13Cipso) ¼ 10.0 Hz);
135.2 (C60); 134.3 (d, Cortho(Ph), 2J(31P, 13Cortho) ¼ 20.4 Hz); 134.1 (d,
Cortho(Ph), 2J(31P, 13Cortho) ¼ 20.4 Hz); 130.0 (C40); 129.1e128.7 (m,
PPh2); 127.9 (C30); 78.4 (d, Cipso(Cp’), 1J(31P, 13Cipso) ¼ 9.7 Hz); 75.1 (C
(Cp’), 2J(31P, 13C) ¼ 15.4 Hz); 74.4 (m, Cp and Cp’); 73.5e72.5 (m, Cp);
64.3 (CH2N); 46.5 (N(CH3)2); 28.8 (C2); 28.2 (C3); 27.2 (C1); 14.2
(C4); the signal of C50 is overlapped by the resonance of benzene-d6.
31P NMR (C6D6, 295 K, ppm): ꢁ16.8 (s, PPh2). 119Sn NMR (C6D6,
295 K, ppm): ꢁ388.2. IR (Nujol mull, cmꢁ1): 1541 (vs, nas(COO));
1355 (s, ns(COO)). Elemental analysis (%): found C, 62.6; H, 5.4; N,1.0.
Calcd. for C59H57Fe2NO4P2Sn (1136.45): C, 62.36; H, 5.06; N, 1.23.
4.8. Preparation of [(LCN)2Sn(O2CfcPPh2)2] (7)
Using the procedure described above, Hdpf (257 mg,
0.62 mmol), t-BuOK (97%, 72 mg, 0.62 mmol) and [(LCN)2SnBr2]
(170 mg, 0.31 mmol) afforded 7 as a reddish brown crystalline solid.
Yield: 289 mg (79%). M.p. 92e94 ꢀC. 1H NMR (C6D6, 295 K, ppm):
8.66 (br, 2H, H(60), 3J(119Sn, 1H) z 90 Hz); 7.50 (br, 8H, PPh2); 7.37
(br, 2H, LCN); 7.16e7.05 (m, 10H, PPh2 and LCN); 6.56 (d, 2H, H(30), 3J
(1H(40), 1H(30)) ¼ 7.1 Hz); 4.89 (s, 4H, H(Cp)); 4.78 (br, 4H, H(Cp’));
4.31 (br, 4H, H(Cp)); 4.09 (s, 4H, Cp’); 3.12 (br, 4H, CH2N); 1.74 (very
broad, 12H, N(CH3)2). 13C NMR (C6D6, 295 K, ppm): 173.2 (OC(O));
Å,
a
¼ 90,
b
¼ 111.124(7),
g
¼ 90ꢀ, Z ¼ 4, V ¼ 3711.5(5) Å3,
Dc ¼ 1.514 g cmꢁ3
,
m
¼ 1.481 mmꢁ1, Tmin ¼ 0.633, Tmax ¼ 0.846;
51851 reflections measured (qmax ¼ 24.0ꢀ), 5815 independent
(Rint ¼ 0.0426), 5070 with I > 2 (I), 390 parameters, S ¼ 1.072, R1
s
(obs. data) ¼ 0.0426, wR2(all data) ¼ 0.0973; max, min residual
electron density ¼ 1.925, ꢁ1.140 eÅꢁ3
.
Crystallographic data for 2; C40H42Fe2N2O4Sn, M ¼ 845.15,
monoclinic, Cc, a ¼ 12.2571(12), b ¼ 18.6440(9), c ¼ 15.6719(7) Å,
142.4 (C20); 142.1 (C10); 140.4 (d, Cipso(Ph), 1J(31P, 13Cipso) ¼ 10.7 Hz);
a
¼ 90,
b
¼ 95.571(13),
g
¼ 90ꢀ, Z ¼ 4, V ¼ 3564.4(1) Å3,
13
138.0 (C60); 134.3 (d, Cortho(Ph), 2J(31P,
C
) ¼ 19.1 Hz); 129.9
Dc ¼ 1.575 g cmꢁ3
,
m
¼ 1.543 mmꢁ1, Tmin ¼ 0.668, Tmax ¼ 0.788;
ortho
(C40); 78.0 (Cipso(Cp)); 77.6 (d, Cipso(Cp’), 1J(31P,
C
) ¼ 8.0 Hz);
ipso
14272 reflections measured (qmax ¼ 27.5ꢀ), 7318 independent
13
74.8 (br, Cp’); 74.5 (Cp); 72.5 (Cp’); 72.2 (Cp); 65.0 (CH2N); 46.3 (N
(CH3)2); the signals of C50, C30, Cmeta(Ph) and Cpara(Ph) atoms are
overlapped by the resonance of benzene-d6. 31P NMR (C6D6, 295 K,
ppm): ꢁ17.9 (s, PPh2). 119Sn NMR (C6D6, 295 K, ppm): ꢁ370.0. IR
(Nujol mull, cmꢁ1): 1654 (vs, nas(COO)); 1316 (vs, ns(COO)).
Elemental analysis (%): found C, 57.1; H, 5.2; N, 3.2. Calcd. for
C40H42Fe2N2O4Sn (845.18): C, 56.85; H, 5.01; N, 3.31.
(Rint ¼ 0.0350), 6798 with I > 2 (I), 398 parameters, S ¼ 1.074, R1
s
(obs. data) ¼ 0.0350, wR2(all data) ¼ 0.0703; max, min residual
electron density ¼ 1.121, ꢁ0.67 eÅꢁ3
.
Acknowledgements
This work was financially supported by the Czech Science
Foundation (project no. P207/10/0215). It is also a part of long-term
research projects of the Faculty of Chemical Technology, University
of Pardubice and the Faculty of Science, Charles University in Pra-
gue supported by the Ministry of Education, Youth and Sports of the
Czech Republic (project nos. VZ 0021627501 & MSM0021620857).
4.9. Preparation of [LCN(n-Bu)2Sn(O2CFc)] (8)
Compound 8 was obtained in an analogous manner using
FcCO2H (309 mg, 1.30 mmol), t-BuOK (151 mg, 1.30 mmol) and
[LCN(n-Bu)2SnCl] (525 mg, 1.30 mmol). Reddish brown oily product
was obtained. Yield: 567 mg (73%). 1H NMR (C6D6, 295 K, ppm):
Appendix A. Supplementary information
8.61 (d, 1H, H(60), J(1H(50), H(60))
¼
6.7 Hz), 3J(119Sn,
3
1
1H) ¼ 53.5 Hz); 7.38 (t, 1H, H(50)); 7.25 (m, 1H, H(40)); 6.99 (d, 1H, H
CCDC 807996 and CCDC 807995 contain the supplementary
crystallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
(30), J(1H(40), 1H(30)) ¼ 7.4 Hz)); 5.21 (s, 2H, H(Cp)); 4.33 (s, 5H, H
3
(Cp’)); 4.22 (s, 2H, H(Cp)); 3.12 (s, 2H, CH2N); 1.98 (m, 4H, H(1));
1.80 (s, 6H, N(CH3)2); 1.55 (m, 4H, H(2)); 1.42 (m, 4H, H(3)); 1.02 (t,
3H, H(4)). 13C NMR (C6D6, 295 K, ppm): 175.2 (OC(O)); 143.3 (C20);
142.8 (C10); 138.5 (C60); 129.1 (C40); 127.1 (C30); 77.7 (Cipso(Cp)); 71.2
(Cp); 70.3 (Cp); 69.8 (Cp’); 65.5 (CH2N); 45.1 (N(CH3)2); 28.6 (C2);
27.5 (C3); 17.0 (C1); 14.0 (C4); the resonance of C50 is overlapped by
the solvent signal. 119Sn NMR (C6D6, 295 K, ppm): ꢁ92.2. IR (neat,
cmꢁ1): 1636 (vs, nas(COO)); 1321 (vs, ns(OC(O)). Elemental analysis
(%): found C, 56.7; H, 6.7; N, 2.2. Calcd. for C28H39FeNO2Sn (596.17):
C, 56.41; H, 6.59; N, 2.35.
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