Synthesis and electrochemical and spectroscopic properties of molybdenum complexes bearing 5-alkoxythiophene or -bithiophene groups

Article abstract of DOI:10.1002/ejic.200401012

trans-[MoF{NN=CH(5′-R-thienyl)}(dppe)₂][BF₄] (R = OMe and OEt) and trans-[MoF{NN=CH(5′-R-2,2′-bithienyl)}-(dppe) ₂][BF₄] (R = OMe, OEt and OiPr) were synthesised in good yields by treating 5-alkoxy-2-formylthiop

Full text of DOI:10.1002/ejic.200401012

FULL PAPER
Synthesis and Electrochemical and Spectroscopic Properties of Molybdenum
Complexes Bearing 5-Alkoxythiophene or -bithiophene Groups
António M. Fonseca,*[a] Maria Manuela M. Raposo,[a] Ana M. R. C. Sousa,[a]
Gilbert Kirsch,[b] and Marc Beley[c]
Keywords: Sulfur heterocycles / Molybdenum / N ligands / Conjugated systems
trans-[MoF{NN=CH(5Ј-R-thienyl)}(dppe)2][BF4] (R
=
OMe
of these compounds were studied. These results suggest that
efficient π-conjugated systems are obtained due to the low-
energy charge-transfer between the metal atom and the het-
erocyclic moieties.
and OEt) and trans-[MoF{NN=CH(5Ј-R-2,2Ј-bithienyl)}-
(dppe)2][BF4] (R = OMe, OEt and OiPr) were synthesised in
good yields by treating 5-alkoxy-2-formylthiophenes and 5Ј-
alkoxy-5-formyl-2,2Ј-bithiophenes, respectively, with the hy-
drazido(2–) complex trans-[MoF(NNH2)(dppe)2][BF4]. The
electrochemical, spectroscopic and solvatochromic properties
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
complexes of the general type trans-[MX(NNR)(dppe)2]+
[M = Mo or W; X = halide; dppe = 1,2-bis(diphenylphos-
phanyl)ethane; R = heterocyclic group] are particularly at-
tractive because the conjugated structure, including the cen-
tral metal atom and the square-planar {M(dppe)2} as-
sembly, is robust.[11,12]
In this paper we wish to report the synthesis and the
electrochemical, spectroscopic and solvatochromic proper-
ties of the new electron-donor–π-acceptor systems trans-
[MoF{NN=CH(thienyl-5Ј-alkoxy)}(dppe)2][BF4] 6 and 8
Introduction
There is considerable interest in the synthesis of new or-
ganic and organometallic materials with large second-order
optical nonlinearities because of their potential applications
in telecommunications, optical computing, optical storage
and optical information processing.[1–3]
Structural, redox and photophysical properties can easily
be tuned in organometallic compounds. Consequently, they
have been explored in the design of materials for nonlinear
optical (NLO) applications.[4,5] In this case, for a molecule
to be of interest it must present an excited state of similar
energy to the ground state, as well as a dipolar moment that
is quite different in the ground and excited states.[6,7] These
requirements are satisfied in asymmetric conjugated com-
plexes containing electron-acceptor and electron-donor
groups connected by a conjugated π system.[8,9] For exam-
ple, metal complexes based on nitrosylmolybdenum and
-tungsten moieties stabilised by tris(3,5-dimethylpyrazolyl)-
borate and attached to phenolato or anilido groups are
strongly polarised and may therefore be able to act as elec-
tron termini of dipolar complexes having second-order
NLO properties.[7] Thiophene and bithiophene chromo-
phores exhibit greater β second-order polarisabilities com-
pared to those of biphenyls or stilbenes.[10] Transition metal
(alkoxy
= OMe and OEt, respectively) and trans-
[MoF{NN=CH(bithienyl-5Ј-alkoxy)}(dppe)2][BF4] 7, 9 and
10 (alkoxy = OMe, OEt and OiPr, respectively). As far as
we know, the synthesis and the characterisation of molyb-
denum complexes bearing 2-alkoxythienyl groups and 2-al-
koxybithienyl groups has not been reported previously.
Results and Discussion
Synthesis
As part of our ongoing effort to develop chromophores
for nonlinear optical applications,[13–16] we synthesised se-
veral donor–acceptor 5,5Ј-disubstituted 2,2Ј-bithio-
phenes[13] by functionalisation of the corresponding 5-alk-
oxybithiophenes.[17] We have recently reported the synthesis
of the 5Ј-alkoxy-5-formyl-2,2Ј-bithiophene derivatives 2, 4
and 5 (alkoxy = OMe, OEt and OiPr, respectively), which
made these compounds available in reasonable amounts.[13]
Indeed, we were able to use these compounds successfully
as substrates for the synthesis of the molybdenum com-
plexes. The versatile method to form carbon–nitrogen
bonds involves the initial conversion of trans-[Mo(N2)2-
[a] Centro de Química, Universidade do Minho,
Campus de Gualtar, 4710-057 Braga, Portugal
Fax: +351-253-678-983
E-mail: amcf@quimica.uminho.pt
[b] Laboratoire d’Ingénierie Moléculaire et Biochimie Pharmacolo-
gique, UFR SciFA/Université de Metz,
1, Boulevard Arago, Metz Technopôle, CP 87811, 57078 Metz
Cedex 3, France
[c] Laboratoire de Chimie et Applications, UFR SciFA/Université
de Metz, Metz Technopôle, IPEM,
1, Boulevard Arago, 57078 Metz Cedex 3, France
Eur. J. Inorg. Chem. 2005, 4361–4365
DOI: 10.1002/ejic.200401012
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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A. M. Fonseca, M. M. M. Raposo, A. M. R. C. Sousa, G. Kirsch, M. Beley
FULL PAPER
(dppe)2] into the hydrazido(2–) complex trans- Electrochemistry
[MoF(NNH2)(dppe)2][BF4], which then undergoes an elec-
Electrochemical data for compounds 1–5 are summarised
trophilic attack at the terminal nitrogen atom. It can there-
fore be used as a key intermediate in the preparation of
organonitrogen complexes by subsequent reactions with or-
ganic carbonyl compounds.[18] Condensation with 5-alkoxy-
2-formylthiophene [alkoxy = OMe (1) or OEt (3)] or 5Ј-
alkoxy-5-formyl-2,2Ј-bithiophene [alkoxy = OMe (2), OEt
(4) or OiPr (5)] gave the molybdenum complexes 6–10 bear-
ing the alkoxythiophenic or alkoxybithiophenic group,
respectively, in good yields (65–78%; Scheme 1).
in Table 1. Cyclic voltammetry shows an irreversible single-
electron oxidation process (Epa) which can be attributed to
the formation of the radical cation of the heterocyclic part.
As the HOMO levels in the heterocyclic part increase with
the donor effect of the alkoxy groups along the series OMe
Ͻ OEt Ͻ OiPr, the ease of oxidation increases gradually.
The oxidation processes of the bithienyl groups are system-
atically shifted to less positive potentials than those of the
thienyl groups. This fact can be explained by the stabilisa-
tion of the cation radical due to its higher delocalisation on
the bithienyl moiety. At low potentials (Ͻ –2 V vs. fc/fc+)
these compounds exhibit one irreversible single-electron
process (–Epr), which generates a radical anion. The elec-
tron goes into a π*-antibonding orbital of the heterocycle.
This electron injection occurs at more negative potentials
as the alkoxy group is an electron donor and its delocalis-
ation on the heterocyclic part is difficult.
Electrochemical data for complexes 6–10 are collected in
Table 2.
A
typical cyclic voltammogram of trans-
[MoF{NN=CH(5Ј-OEt-2,2Ј-bithienyl)}(dppe)2][BF4] (9) in
DMF/0.1  [Bu4N][BF4] at a vitreous carbon electrode is
shown in Figure 1. The molybdenum complexes show three
single-electron oxidation processes. The first (Ea1/2) and sec-
ond processes (Epa1) are reversible and irreversible, respec-
tively, and correspond to the MoIV/MoV and MoV/MoVI
waves. Controlled potential coulometry of the first oxi-
dation step confirms a single-electron process. The resulting
solution displays a cyclic voltammetric profile that re-
sembles the original one. The parent complex trans-
[MoF(NNH2)(dppe)2][BF4] has only one irreversible wave
at 0.34 V vs. fc+/fc. A comparison of the values obtained
for 6–10 with that of the parent complex shows that the
donor effect of the alkoxy substituent stabilises MoV com-
pletely and MoVI partially. However, the oxidation poten-
Scheme 1.
The structures of these complexes were confirmed by the tials of compounds 7 and 9, which have a bithiophenic link,
usual spectroscopic methods. Each diazenido [hydrazido- are slightly higher (40 mV) than those of 6 and 8, which
(–2)] complex shows a characteristic band in the 1515– bear a thiophenic link. This fact can be explained by metal-
1550 cm–1 region of its FTIR spectrum that can be assigned to-heterocycle π*-orbital back-donation via the hydrazido
to ν(C=N).[19] Their trans stereochemistry was confirmed ligand. This back-donation increases in the case of a bithio-
by the 31P{1H}NMR spectra, which show a single reso- phenic link, which contributes to the stabilisation of the
nance.
metal-centred HOMO orbital. In both cases this suggests a
Table 1. Electrochemical and electronic spectroscopic data for the thiophenic and bithiophenic groups 1–5.
Electrochemical data[a] Electronic spectroscopic data[b]
Compound
R
n
Reductions
–Epr [V]
Oxidations
Epa [V]
λmax [nm]
10–3 ε [–1 cm–1]
1
2
3
4
5
OMe
OMe
OEt
OEt
OiPr
1
2
1
2
2
2.30
2.00
2.34
2.08
2.14
0.86
0.76
0.82
0.74
0.73
310
362
316
391
393
24.7
16.3
21.2
24.5
23.8
[a] All measurements were recorded at 298 K in degassed acetonitrile solutions with [Bu4N][BF4] (0.2 ) as supporting electrolyte at a
carbon working electrode with a scan rate of 0.1 Vs–1. Ferrocene was added as an internal standard at the end of each measurement,
potentials were converted into V vs. the ferrocene/ferrocenium couple [E1/2(fc+/fc) = 0.38 V/SCE]. [b] Measured in acetonitrile.
4362
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Molybdenum Complexes Bearing 5-Alkoxythiophene or -bithiophene Groups
FULL PAPER
Table 2. Electrochemical and electronic spectroscopic data for complexes 6–10.
Electrochemical data[a]
Electronic spectroscopic data[b]
Complex
R
n
Reduction
Oxidations
Epa1 [V]
–Ec1/2 [V]
Ea1/2 [V]
Epa2 [V]
λmax [nm]
10–3 ε [–1 cm–1]
6
7
OMe
OMe
OEt
OEt
OiPr
1
2
1
2
2
1.45
1.36
1.50
1.40
1.43
0.24
0.28
0.20
0.24
0.20
0.47
0.53
0.42
0.50
0.47
0.87
0.76
0.83
0.74
0.74
469
482
474
497
496
17.2
17.4
18.1
16.7
19.3
8
9
10
[a] All measurements were recorded at 298 K in degassed acetonitrile solutions with [Bu4N][BF4] (0.2 ) as supporting electrolyte at a
carbon working electrode with a scan rate of 0.1 Vs–1. Ferrocene was added as an internal standard at the end of each measurement,
potentials were converted into V vs. the ferrocenium/ferrocene couple [E1/2(fc+/fc) = 0.38 V/SCE]. [b] Measured in acetonitrile.
π-conjugated system between the metal acceptor group and
The UV/Vis spectroscopic data for complexes 6–10 are
the alkoxythiophene and -bithiophene moieties. In com- summarised in Table 2. The parent complex trans-
plexes 6–10 the oxidation potentials (Epa2) of the heterocy- [MoF(NNH2)(dppe)2][BF4] shows a broad band at around
clic parts are not significantly modified in comparison with 275 nm corresponding to a transition in the dppe ligand.
those of the corresponding compounds 1–5. The reduction Complexes 6–10, which bear heterocyclic groups, show an
of the complexes occurs in a quasi-reversible one-electron absorption band in the visible region because the molybde-
process (–Ec1/2, ∆Ep = 200 mV). For 7, 9 and 10, with a num part lowers the energies of the transition in the hetero-
bithiophenic linker, the reduction potentials are shifted to cycle. For example, the absorption maximum of 1, which
higher values than for 6 and 8. The corresponding stabilisa- appears at 310 nm, is red-shifted to 469 nm for complex 6.
tion of the LUMO (π*) ligand orbital does not correspond The intramolecular charge-transfer process, which origi-
to an electron-donor effect of this link, but to a better de- nates in the Mo part and is propagated through the π-con-
localisation of the injected electron into the ligand on the jugated spacer ligand [hydrazido(2–)], gives rise to a con-
bithiophene moiety via the imino bridge.
siderable bathochromic shift of the alkoxythiophenic and
-bithiophenic transitions (Figure 2). For these complexes,
the alkoxy group effect and the better delocalisation in the
bithienyl groups induce modifications of their electronic
spectra similar to those described for compounds 1–5. The
influence of the incorporation of thiophene moieties in
push-pull compounds on the charge-transfer properties has
been described previously.[20]
Figure 1. Cyclic voltammogram of trans-[MoF{NN=CH(5Ј-OEt-
2,2Ј-bithienyl)}(dppe)2][BF4] (9) in DMF/0.1  [Bu4N][BF4] at a
vitreous carbon electrode (area = 0.049 cm2). Scan rate: 100 mVs–1;
concentration of complex: 2.3 m.
UV/Vis and Solvatochromic Studies
The UV/Vis spectroscopic data for heterocycles 1–5 are
presented in Table 1. The electronic absorption spectra
show an absorption band in the near-UV region due to the
π–π* transitions in the heterocyclic parts. The bithienyl
groups show red-shifted absorption maxima relative to the
thienyl groups. This is due to better delocalisation of the
excited electron in the π*-orbital, which causes its stabilisa-
tion. Moreover, the position of these bands is influenced by
the donor effect of the alkoxy group, which lowers the en-
ergy gap.
Figure 2. UV/Vis spectra of 2-formyl-5-methoxythiophene (1) and
trans-[MoF{NN=CH(5Ј-methoxythienyl)}(dppe)2][BF4] (6) in ace-
tonitrile, demonstrating the effect of the Mo part on the absorption
maxima between 300 and 700 nm.
Eur. J. Inorg. Chem. 2005, 4361–4365
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A. M. Fonseca, M. M. M. Raposo, A. M. R. C. Sousa, G. Kirsch, M. Beley
FULL PAPER
Table 3. Solvatochromic data (λmax [nm] and ν [cm–1] of the charge-transfer band) for complexes 6–10 in selected solvents in comparison
˜
0
with the π* values of Kamlet and Taft.[24]
Solvent (π*)
Acetonitrile (0.75)
λmax, ν
Complex
THF (0.58)
λmax, ν
Acetone (0.71)
λmax, ν
CH2Cl2 (0.82)
λmax, ν
DMSO (0.88)
λmax, ν
˜
˜
˜
˜
˜
0
0
0
0
0
6
7
466, 21459
479, 20877
479, 20877
493, 20284
491, 20366
468, 21413
481, 20790
482, 20747
495, 20202
494, 20243
469, 21322
482, 20747
484, 20661
497, 20121
496, 20161
471, 21231
485, 20619
487, 20534
501, 19960
499, 20040
474, 21097
488, 20492
490, 20408
505, 19802
502, 19920
8
9
10
In general, the stronger the donor and/or acceptor group, oriented parallel to the transition dipole and is, moreover,
the smaller the energy difference between the ground and constant over the whole charge-transfer band.
excited states and the longer the wavelength of the absorp-
tion. According to Zyss,[21] the increase in the β-values
characteristic of the NLO effects is accompanied by an in-
crease of λmax in the UV/Vis spectra.
Conclusions
We have described the synthesis and characterisation of
molybdenum complexes connected via a hydrazido(2–)
bridge to alkoxythiophenic or alkoxybithiophenic groups.
Their electrochemical, spectroscopic and solvatochromic
behaviours exhibit an intramolecular charge-transfer effect.
These new complexes are promising candidates for de-
veloping novel NLO materials.
Solvatochromism is easily quantified by UV/Vis spec-
troscopy and is particularly suitable for the empirical deter-
mination of the polarity of a solvent[22,23] on a molecular-
microscopic level. To evaluate the intermolecular forces be-
tween the solvents and the solute molecules we recorded
absorption spectra of all complexes in five polar solvents of
different solvation character (Table 3). Due to the insolubil-
ity of complexes 6–10 in apolar solvents the solvatochromic
study of these compounds was only performed in polar sol-
vents such as tetrahydrofuran, acetone, acetonitrile, dichlo-
romethane and dimethyl sulfoxide. The electronic exci-
tations are governed by a positive solvatochromism with
increasing solvent polarity, indicating dipole changes within
the ground excited state.
Good correlation with the π* parameters defined by
Kamlet and Taft[24] was obtained. Table 4 summarises the
results of the linear regression analyses of absorption max-
ima for complexes 6–10. The most important values of the
linear relationship between absorption maxima and π* are
the correlation coefficient, r, and the slope, s, which de-
scribes the extent of solvatochromism from π* = 0.58 (tetra-
hydrofuran) to π* = 1.00 (DMSO). As shown in Table 4,
the greatest value for s is found for complex 9. The change
in dipole moment on electronic excitation is shown to be
Experimental Section
General: All reactions were carried out under nitrogen or argon
using standard Schlenk techniques. Solvents were freshly distilled
from appropriate drying agents under dinitrogen. The syntheses of
5Ј-alkoxy-5-formyl-2,2Ј-bithiophenes[13] and complexes trans-
[Mo(N2)(dppe)2] and trans-[MoF(NNH2)(dppe)2][17] have already
been described. The NMR spectra were obtained with a Varian
Unity Plus Spectrometer at 300 MHz using the solvent peak as
internal reference. Infrared spectra were recorded with a Perkin–
Elmer 1600 FTIR spectrophotometer. UV/Vis absorption spectra
were obtained with a Shimadzu UV/2501PC spectrophotometer.
High-resolution mass spectra (HRMS) were obtained with a GV
AutoSpec spectrometer with m-nitrobenzyl alcohol (NBA) as ma-
trix. Elemental analyses were performed with a Leco CHNS-932
analyser. Voltammetric measurements were performed with a po-
tentiostat/galvanostat (AUTOLAB /PSTAT 12 with low current
module ECD from ECO-CHEMIE) and the data processed with
the General Purpose Electrochemical System software package
(ECO-CHEMIE).
Three-electrode
two-compartment
cells
equipped with vitreous carbon-disc working electrodes, a platinum-
wire secondary electrode and a silver-wire pseudo-reference elec-
trode were employed for cyclic voltammetric measurements. The
ferrocenium-ferrocene redox couple was used as a secondary in-
ternal reference. The concentrations of the compounds were typi-
cally 1–2 m, and 0.2  [Bu4N][BF4] was used as the supporting
electrolyte in N,N-dimethylformamide solvent. The potential was
measured with respect to ferrocinium/ferrocene as an internal stan-
dard. Controlled-potential electrolyses were carried out in an H-
type cell with a vitreous carbon working electrode as described pre-
viously.[12]
Table 4. Correlation of the UV/Vis absorption maxima of com-
plexes 6–10 and the solvent parameter π*.[a]
Complexes
Regression analysis[b]
ν [cm–1]
s
r
˜
0
6
7
22013
–917.62
–962.61
–1158.20
–1196.40
–1101.80
0.9760
0.9843
0.9814
0.9863
0.9760
21448
21590
20989
20997
8
9
10
[a] Applied solvents (π* value): THF (0.58), acetone (0.71), acetoni-
trile (0.75), dichloromethane (0.82) and dimethyl sulfoxide (1.0). [b]
Intercept, slope, and correlation r of the linear solvation energy
relationship, according to the equation νmax = ν0 + sπ*.
General Procedure for the Preparation of Complexes 6–10: The com-
plex trans-[MoF(NNH2)(dppe)2][BF4] (0.2 g, 0.19 mmol) was dis-
4364
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Molybdenum Complexes Bearing 5-Alkoxythiophene or -bithiophene Groups
FULL PAPER
solved in THF (20 mL) at room temperature. Formyl ligands 1–5
Acknowledgments
(0.40 mmol) were added in excess to the solution, which was stirred
for 28 h. The volume of the solution was then reduced to about
5 mL and the precipitates were filtered off. These solids were dis-
solved in CH2Cl2 and filtered through a pad of Celite. The solu-
tions were concentrated to dryness and the solids obtained washed
with cold THF (3×5 mL), then Et2O (2×3 mL), and dried in
vacuo to give complexes 6–10 as coloured solids. In all cases, the
solids thus obtained were crystallised from CH2Cl2/Et2O.
We thank the Foundation for Science and Technology (Portugal)
for financial support from IBQF (UM) and from FEDER, POCTI
(ref. POCTI/QUI/37816/2001).
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1
6: Pink solid. Yield: 0.16 g (73%). H NMR (300 MHz, CDCl3): δ
= 2.4–2.8 (m, 8 H, 2×PCH2CH2P), 3.4 (s, 3 H, OCH3), 4.6 (s, 1
H, N=CH), 6.8–7.4 (m, 42 H, 40 H and 2 H of thienyl) ppm.
31P{1H}NMR (121.7 MHz, CDCl3): δ = –100.3 (s, MoP) ppm. IR
(KBr):
C58H54FMoN2OP4S
ν =
1550 (N=C) cm–1. HRMS (NBA): calcd. for
˜
[M]+
1067.1945;
found
1067.1968.
C58H54BF5MoN2OP4S (1152.8): calcd. C 60.43, H 4.72, N 2.43, S
2.78; found C 60.78, H 4.83, N 2.51, S 2.83.
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7: Orange solid. Yield: 0.18 g (77%). 1H NMR (300 MHz, CDCl3):
δ = 2.4–2.7 (m, 8 H, 2×PCH2CH2P), 3.6 (s, 3 H, OCH3), 4.5 (s, 1
H, N=CH), 6.8–7.4 (m, 44 H, 40 H of phenyl and 4 H of bithienyl)
ppm. 31P{1H}NMR (121.7 MHz, CDCl3): δ = –100.1 (s, MoP)
ppm. IR (KBr): ν = 1534 cm–1 (N=C). HRMS (NBA): calcd. for
˜
C62H56FMoN2OP4S2 [M]+ 1149.1823; found 1149.1816.
C62H56BF5MoN2OP4S2 (1234.9): calcd. C 60.30, H 4.57, N 2.27, S
5.19; found C 60.47, H 4.72, N 2.41, S 5.25.
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[19] J. Chatt, W. Hussain, G. J. Leigh, F. P. Terreros, J. Chem. Soc.,
Dalton Trans. 1980, 1408.
[20] G. Mignani, F. Leising, R. Meyrueix, M. Samson, Tetrahedron
Lett. 1990, 31, 4743.
[21] D. S. Zyss, in Non-Linear Optical Properties of Organic Mole-
cules and Crystals, Academic Press, Orlando, 1987, vols. 1 and
2.
[22] C. Reichardt, in Solvents and Solvents Effects in Organic Chem-
istry, 2nd ed., VCH, Weinheim, 1988.
[23] Y. S. Sohn, D. N. Hendrickson, H. B. Grey, J. Am. Chem. Soc.
1971, 93, 3603.
1
8: Pink solid. Yield: 0.15 g (67%). H NMR (300 MHz, CDCl3): δ
= 1.6 (t, J = 6.4 Hz, 3 H, OCH2CH3), 2.4–2.7 (m, 8 H,
2×PCH2CH2P), 3.5 (q, J = 6.4 Hz, 2 H, OCH2CH3), 4.5 (s, 1 H,
N=CH), 6.9–7.5 (m, 42 H, 40 H of phenyl and 2 H of thienyl) ppm.
31P{1H}NMR (121.7 MHz, CDCl3): δ = –100.2 (s, MoP) ppm. IR
(KBr):
ν
˜
=
1546 cm–1 (N=C). HRMS (NBA): calcd. for
[M]+
1081.2102; found 1081.2118.
C59H56FMoN2OP4S
C59H56BF5MoN2OP4S (1166.81): calcd. C 60.73, H 4.84, N 2.40,
S 2.75; found C 60.48, H 4.87, N 2.59, S 5.71.
9: Orange solid. Yield: 0.18 g (78%). 1H NMR (300 MHz, CDCl3):
δ = 1.8 (t, J = 6.3 Hz, 3 H, OCH2CH3), 2.4–2.7 (m, 8 H,
2×PCH2CH2P), 3.8 (q, J = 6.3 Hz, 2 H, OCH2CH3), 4.3 (s, 1 H,
N=CH), 7.0–7.6 (m, 44 H, 40 H of phenyl and 4 H of bithienyl)
ppm. 31P{1H}NMR (121.7 MHz, CDCl3): δ = –99.7 (s, MoP) ppm.
IR (KBr): ν = 1515 cm–1 (N=C). HRMS (NBA): calcd. for
˜
C63H58FMoN2OP4S2 [M]+ 1163.1979; found 1163.1929.
C63H58BF5MoN2OP4S2 (1248.9): calcd. C 60.59, H 4.68, N 2.24, S
5,14; found C 60.82, H 4.77, N 2.44, S 5.19.
10: Orange solid. Yield: 0.16 g (65%). 1H NMR (300 MHz,
CDCl3): δ = 1.5 [d, J = 6.1 Hz, 6 H, OCH(CH3)2], 2.3–2.7 (m, 8
H, 2×PCH2CH2P), 3.4 [m, 1 H, OCH(CH3)2], 4.2 (s, 1 H, N=CH),
and 6.9–7.6 (m, 44 H, 40 H of phenyl and 4 H of bithienyl) ppm.
31P{1H}NMR (121.7 MHz, CDCl3): δ = –99.8 (s, MoP) ppm. IR
(KBr):
ν =
1519 cm–1 (N=C). HRMS (NBA): calcd. for
˜
[24] M. J. Kamlet, J.-L. M. Abboud, M. H. Abraham, R. W. Taft,
J. Org. Chem. 1983, 48, 2877.
C64H60FMoN2OP4S2 [M]+ 1177.2136; found 1177.2101.
C64H60BF5MoN2OP4S2 (1263.0): calcd. C 60.87, H 4.79, N 2.22, S
5.08; found C 61.12, H 4.88, N 2.15, S 5.17.
Received: December 9, 2004
Published Online: September 19, 2005
Eur. J. Inorg. Chem. 2005, 4361–4365
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4365