Synthesis, spectroscopy and structure of new push-pull ferrocene complexes containing heteroaromatic rings (thiophene and furan) in the conjugation chain

Article abstract of DOI:10.1016/S0022-328X(98)01009-2

Six new ferrocene based donor acceptor complexes containing thiophene and furan in the conjugation chain have been synthesized by conventional methods and characterized by NMR, electronic absorption spectral and electrochemical methods. X-ray single cryst

Full text of DOI:10.1016/S0022-328X(98)01009-2

Journal of Organometallic Chemistry 575 (1999) 301–309
Synthesis, spectroscopy and structure of new push–pull ferrocene
complexes containing heteroaromatic rings (thiophene and furan) in
the conjugation chain
K.R. Justin Thomas, Jiann T. Lin *, Yuh S. Wen
Institute of chemistry, Academia Sinica, 115 Nankang, Taipei, 115 Taiwan, ROC
Received 14 August 1998; received in revised form 22 September 1998
Abstract
Six new ferrocene based donor acceptor complexes containing thiophene and furan in the conjugation chain have been
synthesized by conventional methods and characterized by NMR, electronic absorption spectral and electrochemical methods.
X-ray single crystal structures of three thiophene derivatives, [(C5H5)–Fe–(C5H4CHꢀCH–C4H3S)] (la), [(C5H5)–Fe–(C5H4–
CHꢀCH–C4H2S–CHO)] (2a) and [(C5H5)–Fe(C5H4–CHꢀCH–C4H2S–CHꢀC(CN)2)] (3a) have also been determined. Electronic
absorption spectral and electrochemical studies suggest that y-donor acceptor interactions are facile in thiophene derivatives when
compared to their benzene analogues. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Ferrocene; Thiophene; Furan; Nonlinear optics; Electronic absorption spectra; Cyclic voltammetry
ferrocenyl compounds for NLO properties. Our investi-
gations [10] as well as Humphreys laboratories [11,12]
1. Introduction
have resulted in a huge array of ruthenium acetylides
containing aryl or hetero aryl conjugatores. These
ruthenium acetylides exhibit substantial optical non-lin-
earities. Experimental and theoretical studies on or-
ganic chromophores indicated that the presence of
hetero-aromatics in the conjugation chain is highly
beneficial for the observation of large non-linear optical
properties [13]. To the best of our knowledge, hetero-
aromatics substituted ferrocenyl ethylene complexes are
not yet reported. So we have initiated a program deal-
ing with the synthesis of ferrocenyl ethylene complexes
that incorporates hetero-aromatics such as thiophene
and furan. Here, we present results in the synthesis,
structure and spectroscopy of the ferrocene based
donor-acceptor compounds with thiophene or furan in
the conjugation chain and dicyanovinyl acceptor group.
For comparison we have also synthesized the benzene
analogues. Detailed solvatochromic and electrochemi-
cal studies have been performed on these organometal-
There is a flurry of interest in the development of
new materials with large optical non-linearities [1–3].
This is mainly due to the variety of applications they
find in the fields such as optical information processing,
optical computing and telecommunications. Tremen-
dous efforts [4–6] devoted to the synthesis of organic
materials with large second-order optical non-linearities
revealed that molecular structures with both large dif-
ferences between ground state and excited state dipole
moments and large transition dipole moments will have
large second-order optical non-linearities. Molecules
that possess y-donor acceptor interactions suitably
fulfil these requirements. Even though, much effort was
focused on the synthesis of such organic compounds,
organometallic compounds have received less attention.
M.L.H. Green [7] and others [8,9] have examined few
* Corresponding author. Tel.: +886-2-27821889; fax: +886-2-
7831237; e-mail: jtlin@chem.sinica.edu.tw.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01009-2

302
K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
lic complexes to assess the y-donor acceptor
interactions.
lar ratio gives rise to the diferrocenyl derivative 4
[15].
The ferrocenyl derivatives were characterized by IR
and 1H-NMR spectroscopy, EI MS and elemental
analyses. The results are in accordance with the pro-
posed molecular formulations. The molecular struc-
tures of the thiophene derivatives were further
confirmed by the single crystal X-ray diffraction mea-
surements (vice supra). All of the compounds studied
2. Results and discussions
2.1. Synthesis and spectra
The thiophene and furan derivatives (la and 2a)
were prepared by the Wittig reactions of the thienyl
or furanyl methyl triphenyl phosphonium bromide
with ferrocene carboxaldehyde. Formylation at the
5th position of the hetero-aromatic ring was achieved
by using Vilsmeier reagent. Finally, Knoevenagel con-
densation of the aldehydes with malononitrile in the
presence of piperidine yielded the dicyanovinyl deriva-
tives (Scheme 1). The phenylene derivative 2c 1-ferro-
cenyl-2-(4-benzenecarboxaldehyde)ethylene is a known
compound [14], but for this study, it was prepared in
good yield by the Wittig reaction of ferrocenyl methyl
phosphonium bromide with excess terephthaldehyde
(four equivalents) (Scheme 2). It is interesting to note
that the reaction of the above reagents in an equimo-
1
exhibit H- and 13C-NMR signals associated with the
ferrocenyl and aromatic fragments (Tables 1 and 2).
The ethylene bridge signals for la and 2a indicated
the presence of cis and trans isomers.
No attempt was made to separate the isomers.
However, the isomeric mixtures were successfully con-
verted into the trans isomer by heating in toluene for
4–6 h. Subsequently, the vinyl protons appear as
doublets with coupling constant of ca. 16 Hz in ac-
cord with the expected trans stereochemistry. The fer-
rocenyl groups give rise to three separate signals as
expected with the unsubstituted C5H5 (Cp) ring giving
a sharp singlet around 4.10 ppm. The mono substi-
tuted C5H4 (Cp) ring exhibits an unsymmetrical pair
Scheme 1.

K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
303
Scheme 2.
of triplets corresponding to the spectrum of an A2B2
2.2. Structure of the complexes 1a, 2a and 3a
pattern. These signals appear at low field of the un-
substituted C5H5 singlet, showing that the aryl/het-
eroaryl rings considerably shield all the four ring
protons. This shielding is more pronounced in the
thiophene and furan derivatives in comparison to the
benzene analogues. The effect of the electron with-
drawing acceptor group is also witnessed in the 1H
chemical shifts of the substituted C5H4 ring. Thus, the
signals corresponding to them appear in compara-
tively low field for 3a and 3b.
The structure of the ferrocenyl complexes 1a, 2a
and 3a were determined by using single crystal X-ray
diffraction method. The molecular structures of the
complexes were displayed in Figs. 1–3. Table 3 pro-
vides the crystal parameters and other experimental
details. The selected bond lengths and angles were
presented in Table 4. The complexes possess ca.
eclipsed ferrocenyl geometry. The variation in the
Fe–C bond distances are small, 1.993(6)–2.050(4) and

304
K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
Table 1
1H Spectral dataa
No.
1a
1b
2a
2b
3a
3b
3c
Cp
Cp%
Vinyl
H-3
H-4
Others
4.12
4.12
4.17
4.16
4.19
4.17
4.14
4.25(m)
4.40(m)
4.28(m)
4.50(m)
4.38(m)
4.60(m)
4.39(m)
4.60(m)
4.45(m)
4.68(m)
4.46(m)
4.60(m)
4.40(m)
4.63(m)
6.66 (15.9)
6.81 (15.8)
6.61 (16.2)
6.79 (16.1)
7.00 (15.9)
7.10 (15.9)
6.71 (16.1)
7.18 (16.1)
7.09 (15.9)
7.25 (15.9)
6.78 (16.0)
7.34 (16.0)
6.90 (16.2)
7.36 (16.2)
6.94 (m)
6.30 (3.3)
7.20 (3.8)
659 (3.6)
7.29 (4.2)
6.74 (3.8)
7.73(8.4, H-2)
6.94 (m)
6.43 (m)
7.81 (4.2)
7.40 (3.7)
7.81 (4.2)
7.43 (3.8)
8.00(8.5, H-3)
7.11(5-H)
7.49(5-H)
9.87(CHO)
9.56(CHO)
8.30(CHꢀ)
7.86(CHꢀ)
8.21(CHꢀ)
a Chemical shifts in ppm, within parenthesis are multiplicitys, assignment or coupling constant values in case of doublets.
Table 2
13C Spectral dataa
No.
Cp
Cp%
Vinyl
C-2
C-3
C-4
C-S
Others
–
1a
69.22
66.73
69.04
82.92
67.62
69.86
83.90
68.35
70.76
82.53
68.39
70.82
82.33
68.75
70.33
83.20
119.30
126.87
143.58
123.07
124.26
127.52
1b
2a
2b
3a
69.97
70.14
70.18
71.36
112.42
126.64
154.74
141.61
152.42
133.65
107.41
133.58
109.75
136.30
115.2
142.4
–
119.00
126.22
138.98
133.76
142.90
153.70
159.92
142.90
183.32
177.10
113.54
125.36
118.48
126.59
152.16
156.66
115.60
114.92
148.13
162.10
115.19
115.95
164.22
115.30
130.71
114.40
3b
3c
70.42
70.20
68.85
71.55
81.93
112.66
128.99
141.92
127.26
112.42
130.42
137.21
132.39
162.10
145.85
68.46
70.79
80.42
125.00
134.06
a Chemical shifts in ppm.
is more effective in 3a. In 3a, the Fe–C distance
associated with the unsubstituted cyclopentadienyl ring
is 2.006, while that with the substituted cyclopentadi-
enyl ring is 2.036. Effects of the substituents on the
geometry of the cyclopentadienyl rings are also appar-
ent in the ring C–C distances and C–C–C angles.
Thus, the distances involving C(1) are some what
longer than the remaining C–C distances. Both the
cyclopentadienyl rings are planar within experimental
error and they are also parallel to each other. The
thiophene rings are coplanar with the parent cyclopen-
tadienyl rings as indicated by the dihedral angles (8.9,
16.1 and 9.9°, respectively for 1a, 2a and 3a) between
the respective thiophene and cyclopentadienyl rings. A
slight tilting observed for 2a may arise from crystal
packing effects.

K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
305
Fig. 1. Molecular structure of 1a with atom numbering scheme.
2.3. Electronic absorption spectra
plexes the MLCT band is shifted to higher wavelength
and located at around 700 nm, while the benzene
analogue experiences normal effect. In dimethyl sulfox-
ide, 3a and 3c show shifts for MLCT and d-d bands,
thus pointing to the possibility of some chemical mod-
ification. In contrast to the belief that the less aromatic
furan derivative exhibits little solvatochromism. On
going from hexane to dichloromethane a maximum
shift of 24 nm is observed for the thiophene derivative,
3a and the furan derivative 3b possess fewer shifts.
The solution electronic absorption spectral studies of
compounds designed to possess NLO properties are
important for two specific reasons. Firstly, it is neces-
sary to know the transparency region. Secondly, the
solvatochromic behaviour of the sample is generally
considered as indicative of high molecular hyperpolaris-
ability, i, and hence of potential bulk NLO properties.
The
compound
Z-[1-ferrocenyl-2-(4-nitrophenyl)-
ethylene] provides an example of an organometallic
species which displays marked solvatochromism and
also a high powder SHG [7]. The electronic absorption
spectra of the present complexes were recorded in
dichloromethane and data are presented in Table 5. In
general, ferrocenyl compounds show two prominent
bands. The band in the UV region is described to
possess d-d character while the visible band is believed
to be due to an MLCT excitation. All the compounds
studied exhibit the above two bands. The higher wave-
length band exhibits appreciable bathochromic shift as
more electron withdrawing acceptor groups are intro-
duced. Thus, the absorption maxima of the di-
cyanovinyl derivatives top among the complexes.
Within the series the thiophene derivative possess
MLCT absorption in low energy (Fig. 4). This further
corroborates the idea that replacing phenyl groups in
the conjugation chain by less aromatic heterocyclic
rings such as thiophene will facilitate the y-donor ac-
ceptor interactions.
2.4. Electrochemistry
The electrochemical properties of the ferrocenyl com-
pounds were examined in dichloromethane solution by
cyclic voltammetry, and the pertinent data are pre-
sented in Table 7. The compounds 1a and 1b with no
acceptor groups showed oxidation potentials almost
same as parent ferrocene (FcH). Electron withdrawing
substituents on the aryl/heteroaryl rings significantly
affect the oxidation potentials. Thus, for instance 2b
and 3b exhibit 71 and 99 mV anodic shifts, respectively
The solvatochromism of the dicyanovinyl complexes
were investigated in detail in ten solvents of differing
dielectric properties and the data are presented in Table
6. Higher bathochromic shift is observed in
dichloromethane. A drastic change in the spectral pat-
tern is noticed when the spectrum is recorded both in
dimethyl formamide and dimethyl sulfoxide. In
dimethyl formamide, for thiophene and furan com-
Fig. 2. Perspective view of 2a with atom numbering scheme.

306
K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
Fig. 3. Molecular structure of 3a with atom numbering scheme.
in oxidation potentials relative to unsubstituted
derivative 1b. A similar effect is observed for the
thiophene derivatives also. Tremendous shift is realised
for the dicyanovinyl derivatives in accordance with its
superior electron withdrawing ability. On comparing
the benzene and heteroaryl (thiophene and furan)
derivatives the later compounds exhibit large anodic
shifts in oxidation potentials. This probably suggests
that in the heteroaryl derivatives the y-donor acceptor
interactions are more pronounced. The DEp values of
the standard ferrocene and the compounds used in this
study fall in the same range (Table 7). Thus, the
ferrocene oxidation in all the compounds may be
termed as reversible or quasi-reversible. An additional
Table 3
Crystallographic data for 1a, 2a and 3a
Compound
1a
2a
3a
Empirical formula
Formula weight
Crystal system
Space group
C16H14SFe
294.19
Monoclinic
P21/n
C17H14OSFe
322.20
Monoclinic
P21/a
C20H14N2SFe
370.25
Monoclinic
P21/a
Unit cell dimensions
˚
a (A)
19.375(4)
5.9820(23)
22.641(3)
2617.1(12)
8
8.1167(9)
10.0537(23)
17.8006(23)
1422.0(4)
4
12.5914(16)
7.7549(9)
17.287(4)
1683.3(5)
4
˚
b (A)
˚
c (A)
−3
˚
V (A
)
Z
Dcalc. (mg m−3
)
2.987
2.563
1.505
1.191
1.461
1.015
v(Mo–Kh), (m−1
)
Min/max transmission
F(000)
0.932/1.000
2432
0.09×0.13×0.38
2.06–50.00
0.862/1.000
664
0.31×0.31×0.63
2.06–50.00
0.933/1.000
762
0.38×0.44×0.47
2.06–50.00
Crystal size (mm3)
2q range
Index ranges
−235h522, 05k57, 05l526 −95h59, 05k511, 05l521 −145h514, 05k514, 05l514
Reflections collected
Unique data/restraints/parameters
Rf, Rw
4736
2582
3121
4589/0/325
0.049, 0.052
0.640/−0.350
2499/0/181
0.031, 0.035
0.320/−0.290
2967/0/217
0.036, 0.041
0.290/−0.270
−3
˚
Largest remaining peak/hole (e A
)

K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
307
Table 4
boxaldehyde [17] were prepared by adopting reported
methods.
Selected bond distances and angles in 1a, 2a and 3a
1a
2a
3a
4.1. 2-(2-Ferrocenyl-6inyl)-thiophene (1a)
Molecule 1 Molecule 2
The compound (2-thienylmethyl)triphenyl phospho-
nium bromide (4.39 g, 10 mmol) was dissolved in dry
THF and cooled to 0°C. Potassium t-butoxide (1.35 g,
12 mmol)was added as a solid through a side arm while
stirring the solution vigorously. This generated a deep
red coloration. After stirring at 0°C for another 30 min,
the solution was brought to room temperature (r.t.) and
ferrocene carboxaldehyde (2.14 g, 10 mmol) added in a
few batches. The reaction mixture was heated to reflux
for 4 h. When the tlc revealed no further reaction it was
quenched with ice water and extracted with diethyl
ether. The ether layer was washed with brine solution
and dried over anhydrous MgSO4. Evaporation of the
ethereal solution and subjecting the residue to column
chromatography in silica using dichloromethane/hexane
(1:4) as eluant provided 1a in an 82% yield. MS (EI):
m/e 294 (100%, M+). Anal. calc. for C16H14SFe: C
65.32, H 4.80%. Found: C 65.23, H 4.88%.
Bond distance
Fe–C(1)
Fe–C(2)
Fe–C(3)
Fe–C(4)
Fe–C(5)
Fe–C(6)
Fe–C(7)
Fe–C(8)
2.046(7)
2.033(7)
2.037(7)
2.038(8)
2.028(8)
1.997(8)
1.994(9)
2.009(10)
2.025(9)
2.021(9)
1.483(12)
1.250(13)
1.478(12)
–
2.035(7)
2.045(7)
2.032(7)
2.036(8)
2.026(8)
2.029(7)
2.041(7)
2.045(7)
2.036(8)
2.036(7)
1.514(13)
1.212(14)
1.481(13)
–
2.040(3)
2.032(3)
2.041(3)
2.039(3)
2.032(3)
2.030(3)
2.032(3)
2.031(3)
2.038(3)
2.041(3)
1.448(4)
1.329(4)
1.446(4)
1.440(5)
2.035(3)
2.032(3)
2.050(4)
2.034(4)
2.028(4)
1.993(6)
1.994(6)
2.019(4)
2.016(4)
2.009(5)
1.449(4)
1.330(5)
1.439(4)
1.413(4)
1.349(5)
Fe–C(9)
Fe–C(10)
C(1)–C(11)
C(11)–C(12)
C(12)–C(13)
C(16)–C(14)
C(17)–C(18)
Bond angle
C(1)–C(11)–C(12) 124.6(8)
C(22)–C(12)–C(13) 125.5(8)
125.2(10)
127.9(10)
124.9(3)
126.2(3)
126.5(3)
125.3(3)
irreversible wave at a highly cathodic potential is ob-
served in compounds with dicyanovinyl groups. This
may be attributed to the reduction processes of the
dicyanovinyl group.
4.2. 2-(2-Ferrocenyl-6inyl)-furan (1b)
Following the above method (2-furylmethyl)
triphenyl phosphonium bromide and ferrocene carbox-
aldehyde afforded 1b as a brick red powder in an 80%
yield. MS (EI): m/e 278 (100%, M+). Anal. calc. for
C16H14OFe: C 69.10, H 5.07%. Found: C 69.08, H
4.90%.
3. Conclusions
A new series of push–pull ferrocene complexes incor-
porating hetero aromatics such as thiophene and furan
in the conjugation chain have been successfully synthe-
sized and characterized thoroughly by spectral, struc-
tural and electrochemical studies. Electronic spectral
and electrochemical studies point out that y-donor
acceptor interactions are more pronounced in the thio-
phene derivatives when compared to the corresponding
furan and benzene analogues. It is realised that the
introduction of more strong electron withdrawing
groups will enhance the y-donor acceptor interactions
and hence the optical non-linearities. Work in this
direction is in progress in our laboratory
4.3. (E)-5-(2-Ferrocenyl-6inyl)-thiophene-2-
carbaldehyde (2a) and (E)-5-(2-ferrocenyl-6inyl)-
furan-2-carbaldehyde (2b)
Essentially the same procedure was applied to pre-
pare 2a and 2b; consequently only the synthesis of 2a is
described in detail. Vilsmeier reagent was prepared by
mixing dimethyl formamide (20 ml) and phosphorus
oxychloride (1.4 ml, 15 mmol) at 0°C. This was added
dropwise over 0.5 h to an ice-cooled dimethyl for-
mamide solution (20 ml) of 1a (2.94 g, 10 mmol) with
vigorous stirring. After the addition was over, the mix-
ture was allowed to warm to r.t. and then heated at
60°C for 6 h. The reaction was quenched with the
addition of water and subsequently treated with 50 ml
of 10% aqueous sodium hydroxide solution. The dark
brown suspension was extracted with dichloromethane
and thoroughly washed with brine solution. The
dichloromethane extracts were combined, dried over
anhydrous magnesium sulfate and evaporated to dry-
ness to obtain the crude aldehyde. This was purified by
column chromatography using dichloromethane/hexane
4. Experimental
The general procedures pertaining to the synthesis of
the compounds reported in this paper and their physi-
cal measurements are identical to those previously pub-
lished [10]. Compounds (2-thienylmethyl) triphenyl
phosphonium bromide [16], (2-furylmethyl) triphenyl
phosphonium bromide [16], (5-bromo-2-thienylmethyl)
triphenyl phosphonium bromide [16] and ferrocene car-

308
K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
Table 5
Table 6
Electronic absorption data for the ferrocenyl compoundsa
Solvatochromic data for the dicyanovinyl derivatives 3a–ca
Compound
umax (nm)
‡
max
(M−1 cm−1×10−3
)
Solvent
3a
3b
3c
1a
1b
2a
2b
2c
3a
3b
3c
325
460
314
454
370
505
360
486
342
480
442
574
443
566
383
535
22.56
1.44
22.47
1.00
17.52
3.55
19.99
3.27
26.10
3.60
20.64
7.50
17.10
6.62
19.60
4.76
n-Hexane
Ethyl acetate
1,4-Dioxane
Acetonitrile
Acetone
Tetrahydrofuran
Methanol
Dichloromethane
Dimethyl formamide
Dimethyl sulfoxide
550
555
555
559
560
562
564
574
716
723
430
434
434
436
437
437
437
442
437
678
548
549
550
550
551
552
556
565
700
721
432
434
434
437
437
438
438
443
430
674
514
517
515
518
518
519
520
535
520
690
370
374
373
375
374
375
374
383
376
367
a Data measured for dichloromethane solutions of concentration
5×10−5 M.
Table 7
Cyclic voltammetric dataa
a Data measured for dichloromethane solutions of concentration
Compound
Ef (V)
Dep
Others
5×10−5 M.
1a
1b
2a
2b
2c
3a
3b
3c
0.270
0.257
0.323
0.328
0.306
0.350
0.356
0.334
0.264
98
91
88
90
90
92
95
97
82
–
–
–
–
–
(4:1) as eluant. Yield: 87%. MS (EI): m/e 322 (45%,
M+). Anal. calc. for C17H14OSFe: C 63.37, H 4.38%.
Found: C 63.08, H 4.38%.
−1.252
−1.330
−1.334
–
Ferrocene
a Conditions: sample concentration, 10−3 M; electrolyte,
NBu4ClO4 (0.1 M); solvent, dichloromethane; scan rate, 60 mV).
4.4. 4-(2-Ferrocenyl-6inyl)-benzaldehyde (2c) [14]
It was prepared in a 75% yield from ferrocenyl
methyl phosphonium bromide and four equivalents of
terephthaldehyde as described for 1a.
4.5. 2-[5-(2-Ferrocenyl-6inyl)-thiophen-2-ylmethylene]-
malononitrile (3a)
The aldehyde 2a (0.483 g, 1.5 mmol) and malononi-
trile (0.112 g, 1.7 mmol) were dissolved in
dichloromethane (20 ml) and stirred at r.t. for 2 h.
Piperidine (two drops) was added and the stirring con-
tinued for a further 12 h. Volatile materials were driven
off under reduced pressure and the resulted green
residue was chromatographed on silica using
dichloromethane/hexane (3:2) mixture as eluant. Gray
green crystalline 3a was thus obtained in an 81% yield.
MS (EI): m/e 370 (100%, M+). Anal. calc. for
C20H14N2SFe: C 64.88, H 3.81, N 757%. Found: C
64.65, H 4.02, N 6.77%.
Fig. 4. Electronic absorption spectra of (a) 3a, (b) 3b and (c) 3c.

K.R.J. Thomas et al. / Journal of Organometallic Chemistry 575 (1999) 301–309
309
Rikken, C.W. Spangler, J. Phys. Chem. 95 (1991) 10643. (b) C.
Lambert, E. Schmalzlin, K. Meerholz, C. Brauchle, Chem. Eur.
J. 4 (1998) 512.
4.6.
2-[5-(2-Ferrocenyl-6inyl)-fiaran-2-ylmethylene)-
malononitrile (3b)
[6] (a) P. Rao, K.Y. Wong, A.K.-Y. Jen, K.J. Drost, Chem. Mater.
6 (1994) 2210. (b) P. Boldt, G. Bourhill, C. Brauchle, Y. Jim. R.
Kammler, C. Muller, J. Rase, J. Wichern, J. Chem. Soc. Chem.
Commun. (1996) 793.
[7] M.L.H. Green, S.R. Marder, M.E. Thompson, J.A. Bandy, D.
Bloor, P.V. Kolinsky, R.J. Jones, Nature 330 (1987) 360.
[8] (a) J. Coe, C.J. Jones, J.A. McCleverty, D. Bloor, G. Cross, J.
Organomet. Chem. 464 (1994) 225. (b) Y.-W. Cao, X.-D. Chai,
W.-S. Yang, R. Lum, Y.-S. Jiang, T.-J. Li, M.B.-Desce, J.-M.
Lehn, Thin Solid Films 284–285 (1996) 859.
It was obtained in a 55% yield from 2b by following
a procedure similar to that of 3a. MS (EI): m/e 354
(100%, M+). Anal. calc. for C20H14ON2Fe: C 67.32, H
3.98, N 7.91%. Found: C 67.32, H 3.80, N 7.69%.
4.7. 2-[4-(2-Ferrocenyl-6inyl)-benzylidene]-malononitrile
(3c)
[9] (a) V. Alain, A. Fort, M. Barzoukas, C.-T. Chen, M.B. Desce,
S.R. Marder, J.W. Perry, Inorg. Chim. Acta 242 (1996) 43. (b)
S.R. Marder, J.W. Perry, B.G. Tiemann, W.P. Schaefer,
Organometallics 10 (1991) 1896.
[10] (a) I.-Y. Wu, J.T. Lin, J. Luo, C.-S. Li, C. Tsai, Y.S. Wen, C.-C.
Hsu, F.-F. Yeh, S. Liou, Organometallics 17 (1998) 2188. (b)
I.-Y. Wu, J.T. Lin, S.S. Sun, J. Luo, C.S. Li, Y.S. Wen, C.T.
Tsai, C.-C. Hsu, J.L. Lin, Organometallics 16 (1997) 2038.
[11] R. Whittal, A.M. McDonagh, M.G. Humphrey, M. Samoc,
Adv. Organomet. Chem. (1997) 41.
Synthesized as above from 2c in a 65% yield. MS
(EI): m/e 364 (100%, M+). Anal. calc. for C22H16N2Fe:
C 72.55, H 4.43, N 7.69. Found: C 71.47, H 4.29, N
7.35%.
References
[1] (a) H.S. Nalwa, S. Miyata, Nonlinear Optics of Organic
Molecules and Polymers, CRC Press, Boca Raton, 1997. (b) C.
Bosshard, K. Sutter, P. Pretre, J. Hulliger, M. Florsheimer, P.
Kaatz, P. Gunter (Eds.), Organic Nonlinear Optical Materials,
Advances in Nonlinear Optics, vol. 1, Gordon and Breach
Publishers, New York, 1995.
[2] (a) L.R. Dalton, A.W. Harper, R. Ghosn, W.H. Steier, H.
Fetterman, Y. Shi, R.V. Mustacich, A.K.-Y. Jen, K.J. Shea,
Chem. Mater. 7 (1995) 1060. (b) D.M. Burland, R.D. Miller,
C.A. Walsh, Chem. Rev. 94 (1994) 31.
[12] R. Whittal, M.P. Cifuentes, M.G. Humphrey, B.L. Davies, M.
Samoc, S. Houbrechts, A. Persoons, G.A. Heath, D.C.R. Hock-
less, J. Organomet. Chem. 549 (1997) 127.
[13] (a) P.R. Varanasi, A.K.-Y. Jen, J. Chandrasekhar, I.N.N. Nam-
boothiri, A. Rathna, J. Am. Chem. Soc. 118 (1996) 12443. (b)
I.D.L. Albert, T.J. Marks, M.A. Ratner, J. Am. Chem. Soc. 119
(1997) 6575. (c) V.P. Rao, Y.M. Cai, A.K.-Y. Jen, J. Chem. Soc.
Chem. Commun. (1994) 1689.
[14] H.E. Bunting, M.L.H. Green, S.R. Marder, M.E. Thompson, D.
Bloor, P.V. Kolinsky, C.J. Jones, Polyhedron 11 (1992) 1489.
[15] W.H. Morrison, S. Krogsrud, D.N. Hendrickson, Inorg. Chem.
12 (1973) 1998.
[3] T. Verbiest, S. Houbrechts, M. Kauranen, K. Clays, A. Per-
soons, J. Mater. Chem. 7 (1997) 2175.
[4] J. Moore, M.R. Bryce, A.S. Batsanov, A. Green, J.A.K.
Howard, M.A. Mckervey, P. McGuigan, I. Ledoux, E. Orti, R.
Viruela, P.M. Viruela, B. Tarbit, J. Mater. Chem. 8 (1998) 1173.
[5] (a) L.-T. Chang, W. Tam, S.R. Marder, A.E. Stiegman, G.
[16] J.-X. Zhang, P. Dubbois, R. Jerome, Synth. Commun. 26 (1996)
3091.
[17] M. Rosenblum, A.K. Banerjee, N. Danieli, R.W. Fish, V.
Schlatter, J. Am. Chem. Soc. 85 (1963) 316.
.