Syntheses and crystal structures of ferrocenyl derivatives of biphenyl

Article abstract of DOI:10.1023/A:1023998420937

Arylation of ferrocene with substituted biphenyldiazonium tetrafluoroborates afforded 4-bromo-, 4-nitro-, and 4-cyano-4′- ferrocenylbiphenyls. 4-Nitro- and 4-cyano-4′-ferrocenylbiphenyls were studied by X-ray diffraction analysis. In the crystals of 4-nitro-4′- ferrocenylbiphenyl, the molecules are linked via stacking π-π interactions.

Full text of DOI:10.1023/A:1023998420937

Russian Chemical Bulletin, International Edition, Vol. 52, No. 3, pp. 607—615, March, 2003
607
Syntheses and crystal structures
of ferrocenyl derivatives of biphenyl*
a
a
b
b
b
D. A. Lemenovskii,a M. V. Makarov, V. P. Dyadchenko, A. E. Bruce, M. R. M. Bruce, S. A. Larkin
ꢀ
B. B. Averkiev,c Z. A. Starikova,c and M. Yu. Antipinc
aDepartment of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (095) 939 0290. Eꢀmail: dali@org.chem.msu.su
bDepartment of Chemistry, University of Maine,
USA, ME 04469ꢀ5706, Orono, Aubert Hall.
Fax: (207) 581 1191. Eꢀmail: abruce@maine.edu
cA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991, Moscow, Russian Federation.
Fax: +7 (095) 135 5085
Arylation of ferrocene with substituted biphenyldiazonium tetrafluoroborates afforded
4ꢀbromoꢀ, 4ꢀnitroꢀ, and 4ꢀcyanoꢀ4´ꢀferrocenylbiphenyls. 4ꢀNitroꢀ and 4ꢀcyanoꢀ4´ꢀferroꢀ
cenylbiphenyls were studied by Xꢀray diffraction analysis. In the crystals of 4ꢀnitroꢀ4´ꢀ
ferrocenylbiphenyl, the molecules are linked via stacking πꢀπ interactions.
Key words: arylation, ferrocene, aryldiazonium tetrafluoroborates, biphenylferrocenes,
Xꢀray diffraction analysis.
Earlier,1 we have reported the synthesis of ferrocenyl
derivatives of biphenyl.
Having rigid rodꢀlike structures, biphenyl derivatives
can serve as precursors of liquidꢀcrystalline materials. The
introduction of an elecꢀ
crossꢀcoupling reactions involving arylboronic acids2 or
organomercury compounds3 have received the most study.
Unfortunately, the synthesis via arylboronic acids by crossꢀ
coupling reactions is a rather complicated process, beꢀ
cause, first, it involves the preparation of 4ꢀbromoꢀ
phenylferrocene and, second, arylboronic acids are synꢀ
thesized with the use of organolithium compounds. Synꢀ
theses based on organomercury compounds are carried
out with the use of toxic diferrocenylmercury. In addiꢀ
tion, this approach requires the preliminary synthesis of
the corresponding 4ꢀXꢀ4´ꢀYꢀbiphenyls.
In the case of biphenyl derivatives, the classical method
for the synthesis of arylferrocenes involving arylation of
ferrocene with diazonium salts was applied only to 4ꢀferroꢀ
cenylbiphenyl.4
In the present study, we examined the possibility of the
preparation of biphenylferrocene derivatives by arylation
of ferrocene with salts of substituted biphenyldiazonium,
found the optimum reaction conditions, and demonstrated
that this approach is highly competitive with known proꢀ
cedures for the synthesis of these compounds.
tronꢀwithdrawing group
and an easily polarizable
electronꢀdonating group
at positions 4 and 4´ of
Fc = (C5H5)Fe(C5H4); X = Br, CN
the biphenyl molecule should lead to the asymmetry of
the electron density distribution. This may facilitate agꢀ
gregation of the molecules both through intermolecular
dipoleꢀdipole interactions and the formation of intermoꢀ
lecular chargeꢀtransfer complexes. The ferrocenyl fragꢀ
ment is a promising donor group in these compounds. In
addition to the ability of ferrocenyl derivatives of bipheꢀ
nyl to undergo intermolecular aggregation, these comꢀ
pounds can also exhibit nonlinear optical properties. Beꢀ
sides, the presence of the ferrocenyl group allows the
molecule to be involved in reversible redox processes.
Recently,2 4ꢀformylꢀ4´ꢀferrocenylbiphenyl derivatives
possessing liquidꢀcrystalline properties have been syntheꢀ
sized. However, approaches to the synthesis of ferrocenyl
derivatives of biphenyl have been poorly developed. The
Results and Discussion
Substituted ferrocenylbiphenyls can be prepared by
arylation of ferrocene with aryldiazonium salts. However,
these reactions performed with the use of aqueous soluꢀ
* Dedicated to Academician I. P. Beletskaya on the occasion of
her anniversary.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 583—590, March, 2003.
1066ꢀ5285/03/5203ꢀ607 $25.00 © 2003 Plenum Publishing Corporation

608
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
Lemenovskii et al.
Scheme 2
tions of aryldiazonium chlorides gave unsatisfactory reꢀ
sults. The arylation products were produced in very low
yields and their isolation presented problems due to a
high degree of resinification. We found that substituted
ferrocenylbiphenyls were readily generated by arylation
of ferrocene with aryldiazonium tetrafluoroborates 1a—c
isolated in the individual form (Scheme 1). In these reacꢀ
tions, the choice of the solvent is of great importance.
The best results were achieved by performing the reacꢀ
tions in an acetic acid—trifluoroacetic acid—dichloroꢀ
ethane mixture.
Scheme 1
Fc = (C5H5)Fe(C5H4); X = Br (a), NO2 (b), CN (c)
X = Br (a), NO2 (b), CN (c)
The structures of compounds 2a—c were established
by IR and 1H NMR spectroscopy. Compounds 2b,c were
also studied by Xꢀray diffraction analysis.
Reagents and conditions: i. 1) CuCN, DMF, 153 °C; 2) FeCl3,
HCl; ii. SnCl2, HCl, and EtOH or NaSH and MeOH.
The synthesis of arylamines, which are necessary for
the preparation of tetrafluoroborates 1a—c, is presented
in Scheme 2.
Scheme 3
Both arylamines 3a—c and intermediates in their synꢀ
thesis have been described earlier.5—9 However, proceꢀ
dures published in the literature often give unsatisfactory
results. We developed wellꢀreproducible procedures for
the synthesis of these compounds.
Diazotization of amines 3a—c was carried out accordꢀ
ing to a standard procedure (Scheme 3).
We attempted to replace the bromine atom in comꢀ
pound 2a by the SH group according to a procedure deꢀ
scribed earlier.10 However, this attempt led only to the
formation of sulfide 4 (Scheme 4).
Under the aboveꢀdescribed conditions, the reaction
ended in the formation of sulfide even in the presence of a
substantial excess of sodium ethylthiolate.
X = Br (a), NO2 (b), CN (c)
Scheme 4
The molecular and crystal structures of ferrocenylꢀ
biphenyls 2b and 2c were established by Xꢀray diffraction
analysis.
The molecular structures of compounds 2b and 2c are
shown in Figs. 1 and 2, respectively. The principal bond
lengths and bond angles are listed in Tables 1 and 2,
respectively.

Synthesis and structure of biphenylferrocenes
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
609
O(2)
C(19)
C(18)
C(17)
C(20)
C(21)
C(15)
C(16)
C(6)
C(7)
C(8)
C(14)
C(13)
N(1)
C(10) C(11)
O(1)
C(9)
C(22)
C(12)
Fe(1)
C(2)
C(1)
C(3)
C(5)
C(4)
Fig. 1. Structure of one of the crystallographically independent molecules (A) in the crystal of compound 2b.
C(9)
C(8)
C(19)
C(13)
C(15)
C(12)
C(16)
C(18)
C(10)
C(6)
C(14)
C(11)
C(20)
C(17)
C(7)
Fe(1)
C(3)
C(23)
C(21)
N(1)
C(22)
C(4)
C(5)
C(2)
C(1)
Fig. 2. Molecular structure of compound 2c.
The crystal structure of 2b contains two cystalloꢀ
graphically independent 4ꢀnitroꢀ4´ꢀferrocenylbiphenyl
molecules (A and B, see Fig. 1), which differ by the conꢀ
formation of the Cp—Fe—Cp´ ferrocenyl fragment (Cp
and Cp´ are unsubstituted and substituted cyclopentaꢀ
dienyl rings, respectively). In the molecule A, the cycloꢀ
pentadienyl rings are in an eclipsed conformation
(C(10)—Cnt1—Cnt2—C(5) pseudotorsion angle is 0.7°,
where Cnt1 and Cnt2 are the centroids of the Cp´ and Cp
rings, respectively). In the molecule B, the corresponding
C(10´)—Cnt1—Cnt2—C(5´) angle is 30.1°, which indiꢀ
cates that the cyclopentadienyl rings are in a skewed conꢀ
formation (ideal angle characterizing this conformation
is 36°). The Cp and Cp´ rings are coplanar (angles beꢀ
tween the planes of the rings are 0.2° and 2.6° in the
molecules A and B, respectively). In both molecules, the
Cp´—Ar1—Ar2—NO2 fragments (Ar = C6H4) have idenꢀ
tical structures, all rings of the fragment being nonꢀ
coplanar. The dihedral angles between the planes of Cp´
and Ar1, Ar1 and Ar2, and Ar2 and NO2 are 7.2(3)°,
23.7(2)°, and 5.1(5)° in the molecule A and 10.7(3)°,
21.7(2)°, and 7.4(5)° in the molecule B, respectively.
The Ar1—Ar2—NO2 fragment is slightly bent from the
Cp´ ring toward the unsubstituted Cp ring. The
C(11)...C(14)...C(17)...C(20)...N(1) line forms angles of
2.7° (in the molecule A) and 4.1° (in the molecule B) with
the plane of the Cp´ ring. The molecules A and B (except
for the unsubstituted cyclopentadienyl rings) are related
by a center of a pseudosymmetry.
In the crystal of 4ꢀcyanoꢀ4´ꢀferrocenylbiphenyl (2c),
the rings of the Cp´—Ar1—Ar2 fragment are also nonꢀ
coplanar. The dihedral angles between the Cp´ and
Ar1 planes and the Ar1 and Ar2 planes are 9.9(1)° and
42.39(7)°, respectively. The Cp rings are in a nearly
eclipsed conformation with the C(10)—Cnt1—Cnt2—C(5)
pseudotorsion angle of 7.9°.
In molecules 2b and 2c, all aromatic rings are planar
(average deviations are in the ranges of 0.001—0.003 and
0.002—0.007 Å for the Cp and phenyl rings, respectively).
The bond lengths in 2b and 2c are close to standard
values. The average C—C bond lengths in the phenyl and
Cp rings are 1.39 and 1.42 Å, respectively. The Fe—C

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Lemenovskii et al.
Table 1. Selected bond lengths in compounds 2b,c
Analysis of the crystal packing of the 4ꢀnitroꢀ4´ꢀ
ferrocenylbiphenyl molecules (Fig. 3) showed that the
molecules A and B are linked in the centrosymmetrical
A...A and B...B dimers in a headꢀtoꢀtail fashion. The
intermolecular distances between the parallel overlapping
phenyl rings (3.323(5) and 3.256(5) Å in the A...A and
B...B dimers, respectively) are shorter than the valꢀ
ues expected for the van der Waals contacts. In the
dimers, the shortest C(17)...C(21A) (C(21)...C(17A)) and
C(17´)...C(21B) (C(21´)...C(17B)) intermolecular conꢀ
Bond
d/Å
2b
2c
Molecule A
Molecule B
C(1)—C(2)
C(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(5)—C(1)
C(6)—C(7)
C(7)—C(8)
C(8)—C(9)
1.419(7)
1.394(7)
1.409(7)
1.406(7)
1.395(7)
1.418(6)
1.408(6)
1.436(6)
1.427(5)
1.423(5)
1.473(5)
1.396(5)
1.376(6)
1.394(5)
1.399(5)
1.382(6)
1.387(5)
1.479(5)
1.405(5)
1.378(6)
1.379(6)
1.384(6)
1.367(6)
1.402(5)
1.470(5)
1.223(5)
1.225(5)
—
1.417(6)
1.419(7)
1.406(7)
1.409(7)
1.383(7)
1.413(6)
1.413(6)
1.412(6)
1.432(5)
1.433(5)
1.465(5)
1.400(5)
1.385(6)
1.383(5)
1.408(5)
1.368(5)
1.395(5)
1.487(5)
1.400(5)
1.370(6)
1.378(5)
1.377(6)
1.379(6)
1.398(5)
1.464(5)
1.221(5)
1.232(5)
—
1.418(3)
1.419(2)
1.415(3)
1.419(3)
1.428(3)
1.427(3)
1.422(2)
1.421(3)
1.438(2)
1.439(2)
1.468(2)
1.401(2)
1.385(2)
1.404(2)
1.402(2)
1.389(2)
1.399(2)
1.475(2)
1.403(2)
1.382(3)
1.398(3)
1.396(3)
1.383(3)
1.398(2)
—
C(9)—C(10)
C(10)—C(6)
C(10)—C(11)
C(11)—C(12)
C(12)—C(13)
C(13)—C(14)
C(14)—C(15)
C(15)—C(16)
C(16)—C(11)
C(14)—C(17)
C(17)—C(18)
C(18)—C(19)
C(19)—C(20)
C(20)—C(21)
C(21)—C(22)
C(22)—C(17)
C(20)—N(1)
N(1)—O(1)
N(1)—O(2)
C(20)—C(23)
C(23)—N(1)
Fe(1A)
C(17A)
C(21)
—
—
1.438(3)
1.143(2)
—
—
C(21A)
C(17)
distance in the ferrocenyl fragment is 2.04 Å. The average
N—O and C—N (Ar2—NO2) bond lengths are 1.225 and
1.467 Å, respectively.
Table 2. Selected bond angles in compounds 2b,c
Angle
ω/deg
2b
2c
Molecule B
Molecule B
O(2)—N(1)—O(1)
O(1)—N(1)—C(20)
C(21)—C(20)—N(1)
C(9)—C(10)—C(11)
C(15)—C(14)—C(17) 120.6(3)
C(15)—C(16)—C(11) 121.4(4)
C(19)—C(18)—C(17) 121.8(4)
C(16)—C(11)—C(10) 120.3(3)
C(18)—C(17)—C(14) 120.6(3)
123.9(4)
118.4(4)
119.5(4)
126.7(4)
123.8(4)
118.2(4)
119.6(3)
126.0(3)
120.3(3)
122.3(3)
121.8(4)
121.2(3)
120.8(3)
—
—
—
—
Fe(1)
126.74(15)
121.58(16)
121.33(16)
120.97(17)
121.21(15)
121.52(16)
120.28(16)
179.5(2)
C(19)—C(20)—C(23)
C(20)—C(23)—N(1)
—
—
Fig. 3. Centrosymmetrical A...A dimer. (The molecules B are
linked in the B...B dimers with a similar structure.)
—

Synthesis and structure of biphenylferrocenes
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
611
O(1)
N(1)
O(2)
H(5AA)
Fe(1A)
Fe(1A)
H(5A)
O(2A)
O(1A)
H(9´A)
N(1A)
Fig. 4. Fragment of the molecular packing in the crystal of compound 2b.
C(19f)
C(3)
Fe(1)
C(11)
C(22)
C(21)
C(19)
N(1)
C(3a)
C(10)
C(22d)
C(21d)
Fig. 5. Fragment of the molecular packing in the crystal of compound 2c. Weak C...C and C...N contacts are indicated by
dashed lines.

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Lemenovskii et al.
4ꢀBromoꢀ4´ꢀnitrobiphenyl. A. Fuming nitric acid was preꢀ
pared by distillation of concentrated HNO3 with concentrated
H2SO4. The fraction with b.p. 82—85 °C was collected.
tacts are 3.337(5) and 3.268(5) Å, respectively.The shortꢀ
ened C...C contacts in the crystal structure of 2b are inꢀ
dicative of the presence of specific stacking πꢀπ interacꢀ
tions between the molecules with the resulting formation
of dimers.
Fuming nitric acid (23 mL, 35 g, 0.56 mol) was added to a
solution of 4ꢀbromobiphenyl (43.10 g, 0.185 mol) in glacial
acetic acid (70 mL). The reaction mixture was refluxed for 3 h
and cooled to 45 °C in air and then to 20 °C (but not lower) with
stirring using cold water. The crystalline precipitate that formed
was filtered off and washed with glacial acetic acid (2×20 mL)
and water until it became neutral. After drying in air, 4ꢀbromoꢀ
4´ꢀnitrobiphenyl was obtained in a yield of 25.66 g (50%), m.p.
170—172 °C (cf. lit. data6: m.p. 175—176 °C).
B. Chloroform (60 mL), bromine (6.5 mL, 20.15 g, 0.13 mol),
and powdered iron (0.73 g, (0.013 mol) were added to
4ꢀnitrobiphenyl (19.90 g, 0.10 mol). The reaction mixture was
carefully heated until the vigorous reaction started, refluxed for
3 h, and then cooled to ~20 °C. Then an aqueous solution of
sodium sulfite was added and the resulting mixture was stirred to
remove an excess of bromine. The precipitate of the product,
which is grayꢀbrown in color due to the presence of impurities,
was filtered off, washed with water, and dried in air. Crude
4ꢀbromoꢀ4´ꢀnitrobiphenyl was obtained in a yield of 16.90 g. An
additional portion of the product (2.45 g) was obtained after
evaporation of the chloroform solution (from the filtrate) and
recrystallization of the residue from acetic acid with activated
carbon. Both portions of 4ꢀbromoꢀ4´ꢀnitrobiphenyl were exꢀ
tracted in a Soxlet apparatus with light petroleum to obtain
4ꢀbromoꢀ4´ꢀnitrobiphenyl in a yield of 17.50 g (63%) as yellowꢀ
ish crystals, m.p. 174—176 °C.
4ꢀCyanoꢀ4´ꢀnitrobiphenyl. A mixture of 4ꢀbromoꢀ4´ꢀnitroꢀ
biphenyl (7.55 g, 0.027 mol), copper(I) cyanide (3.95 g,
0.044 mol), and DMF (35 mL) was refluxed with stirring under
an argon atmosphere for 8 h. After refluxing for ~2 h, a brown
solution containing a small amount of a precipitate was obꢀ
tained. The warm reaction mixture (~50 °C) was poured into a
solution of iron(III) chloride hexahydrate (23 g) in water (300 mL)
and then 36% hydrochloric acid (10 mL) and chloroform
(220 mL) were added. The resulting mixture was stirred at
40—50 °C for 30 min. The organic layer was separated, washed
with water, dried with sodium sulfate, and filtered through a
6ꢀcm layer of aluminum oxide. The solvent was distilled off on a
rotary evaporator and 4ꢀcyanoꢀ4´ꢀnitrobiphenyl was obtained
in a yield of 3.9 g (63%), m.p. 196—200 °C (cf. lit. data7: m.p.
199.5—200 °C).
4ꢀAminoꢀ4´ꢀbromobiphenyl (3a). A solution of tin(II) chloꢀ
ride dihydrate (54.0 g, 0.240 mol) in concentrated hydrochloric
acid (60 mL) was added to a solution of 4ꢀbromoꢀ4´ꢀnitroꢀ
biphenyl (15.0 g, 0.054 mol) in ethanol (120 mL). The reaction
mixture was refluxed with stirring on a water bath for 2 h. Then
the reaction solution was cooled and diluted with a threefold
volume of water. The precipitate of the salt of amine that formed
was filtered off and a solution of potassium hydroxide (50 g) in
water (80 mL) was added. The reaction mixture was stirred for
5 h, water (100 mL) was added, and a precipitate of the amine
was filtered off. The precipitate was washed with water until it
became neutral and dried in air. 4ꢀAminoꢀ4´ꢀbromobiphenyl
was obtained in a yield of 11.74 g (88%) as a white powder, m.p.
142—144 °C (cf. lit. data8: m.p. 143—144 °C).
In the A...A dimer, the molecules related by a center
of symmetry are linked via the CAr—H...O contacts (shown
by dashed lines in Fig. 4; H(5A)...O(2A) is 2.55 Å, the
C(5)H(5A)O(2A) angle is 164°), which can be assigned to
weak hydrogen bonds. In the B...B dimer, the correspondꢀ
ing H(5´A)...O(2´B) distance is larger (2.73 Å) due to
rotation of the Cp ring. This rotation leads also to a shortꢀ
ening of the H(4´A)...O(1´B) distance (2.70 Å) compared
to the H(1A)...O(1A) distance (3.74 Å) in the A...A
dimer. The second oxygen atom of each molecule in the
A...A dimer forms the O(1A)...H(9´A) contact (2.48 Å;
C(9´)H(9´A)O(1A), 169°) with one of the molecules of
the B...B dimer. As a result, the A...A and B...B dimers
are linked in ribbons via weak H...O bonds (see Fig. 4).
In the crystal of 4ꢀcyanoꢀ4´ꢀferrocenylbiphenyl (2c),
the molecules are packed in a radically different fashion.
These molecules form parallel layers within which they
are arranged in a ladderꢀlike mode (Fig. 5). In each
layer, the molecules are linked by shortened C...C and
C...N contacts, viz., C(19f)—C(3), C(21d)—C(11),
C(22d)—C(10), C(3a)—N(1), and C(2a)—N(1)
(3.474(3), 3.406(3), 3.404(3), 3.382(3), and 3.386(3) Å,
respectively).
Experimental
The reactions were carried out with the use of biphenyl and
4,4´ꢀdinitrobiphenyl of highꢀpurity grade, 4ꢀbromobiphenyl
(98% purity) purchased from Lancaster, sodium hydrosulfide
monohydrate (90% purity), and copper(I) cyanide purchased
from Riedel—deHaën.
Dimethylformamide of highꢀpurity grade was kept over calꢀ
cium hydride and distilled in vacuo. Hexamethylphosphoramide
(highꢀpurity grade) was kept over zeolite calcinated in vacuo and
distilled over sodium under reduced pressure. Sodium ethylꢀ
thiolate was prepared according to a known procedure.10
The resulting compounds were purified by column chromaꢀ
tography on aluminum oxide (Brockmann activity II). Thinꢀ
layer chromatography was carried out on Silufol UVꢀ254 plates.
1
The H NMR spectra were measured on a Varian VXRꢀ400
spectrometer (400 MHz) using CDCl3 as the solvent. The IR
spectra were recorded on a URꢀ20 spectrometer in Nujol mulls.
4ꢀNitrobiphenyl. Glacial acetic acid (60 mL) and 75% HNO3
(35 mL, density 1.44 g cm–3; 0.6 mol) were added to biphenyl
(44 g, 0.286 mol). The reaction mixture was refluxed for 2.5 h and
then cooled to ~20 °C. The precipitate that formed was filtered
off, washed with warm water, and dried in air. The product was
recrystallized from glacial acetic acid (50 mL). 4ꢀNitrobiphenyl
was obtained in a yield of 29.1 g, m.p. 105—112 °C. After reꢀ
peated recrystallization from glacial acetic acid (50 mL),
4ꢀnitrobiphenyl was obtained in a yield of 25.6 g (45%), m.p.
109—113 °C (cf. lit. data5: m.p. 112—113 °C).
4ꢀAminoꢀ4´ꢀnitrobiphenyl (3b). The synthesis was carried out
according to a modified procedure described earlier.9 A solution
of 90% sodium hydrosulfide monohydrate (4.1 g, 0.050 mol) in

Synthesis and structure of biphenylferrocenes
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
613
methanol (100 mL) was added dropwise with stirring to a boiling
mixture of 4,4´ꢀdinitrobiphenyl (9.00 g, 0.037 mol), toluene
(50 mL), and methanol (200 mL) during 30 min. The reaction
mixture was refluxed with stirring for 3.5 h, a yellow precipitate
was separated, and the remaining redꢀorange solution was conꢀ
centrated on a rotary evaporator. The product was obtained as
an orange powder in a yield of 5.69 g. After recrystallization
from ethanol (300 mL), 4ꢀaminoꢀ4´ꢀnitrobiphenyl was obtained
in a yield of 4.90 g (63%) as orange crystals, m.p. 191—201 °C
(cf. lit. data9: m.p. 201—203 °C).
diethyl ether from a solution in acetonitrile. Found (%): C, 53.34;
H, 2.57; N, 14.09. C13H8BF4N3. Calculated (%): C, 53.29;
H, 2.75; N, 14.34.
4ꢀBromoꢀ4´ꢀferrocenylbiphenyl (2a). 4´ꢀBromoꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate (9.09 g, 0.026 mol) was added
portionwise with stirring to a solution of ferrocene (8.37 g,
0.045 mol) in a mixture of 1,2ꢀdichloroethane (50 mL), glacial
acetic acid (200 mL), and trifluoroacetic acid (15 mL). The
diazonium salt was added at ~20 °C during 1 h, after which the
reaction mixture was stirred for 4 h and kept at ~20 °C for 12 h.
Then water (350 mL) and chloroform (150 mL) were added.
The organic layer was separated and the aqueous layer was exꢀ
tracted with chloroform (50 mL). The combined organic phases
were washed with a solution of ascorbic acid and water until the
reaction mixture became neutral, dried with sodium sulfate, and
filtered. The solvent was removed on a rotary evaporator. The
residue (~12 g) was chromatographed on a column (l 50 cm,
d 2.5 cm) with aluminum oxide. A mixture of ferrocene and
4ꢀbromobiphenyl was eluted with light petroleum, after which
virtually pure 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl was eluted with a
1 : 3 benzene—light petroleum mixture in a yield of 1.16 g (first
portion) and then 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl weakly conꢀ
taminated with an impurity (second portion) was eluted with
benzene in a yield of 3.40 g. Repeated chromatography of the
first portion on a column (l 15 cm, d 2.5 cm) with aluminum
oxide afforded 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl in a yield of 0.93 g
as orange pearly plateletꢀlike crystals, m.p. 202—204 °C. The
second portion of the product was chromatographed three times
on a column (l 20 cm, d 2.5 cm) to obtain 4ꢀbromoꢀ4´ꢀ
ferrocenylbiphenyl in a yield of 2.60 g, m.p. 202—204 °C. The
total yield of 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl was 3.53 g (32%).
Found (%): C, 63.37; H, 4.11; Br, 19.04. C22H17BrFe. Calcuꢀ
lated (%): C, 63.35; H, 4.11; Br, 19.16. 1H NMR, δ: 4.05 (s,
5 H, C5H5); 4.33 (m, 2 H, C(7)H, C(8)H); 4.66 (m, 2 H,
C(6)H, C(9)H); 7.45—7.54 (m, 8 H, Ar).
4ꢀNitroꢀ4´ꢀferrocenylbiphenyl (2b). 4´ꢀNitroꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate (4.4 g, 0.014 mol) was added
portionwise with stirring to a solution of ferrocene (3.9 g,
0.021 mol) in a mixture of 1,2ꢀdichloroethane (17 mL), glacial
acetic acid (110 mL), and trifluoroacetic acid (24 mL) at ~20 °C
during 30 min. The reaction mixture was stirred at ~20 °C for
6 h. The mixture gradually turned darkꢀcherry and a cherryꢀ
colored precipitate formed. Then the reaction mixture was kept
without stirring at 4 °C for 18 h, after which water (200 mL) and
chloroform (150 mL) were added. The organic layer was sepaꢀ
rated and the aqueous layer was extracted with chloroform
(150 mL). The combined organic solutions were washed with
water until the mixture became neutral, dried with sodium sulꢀ
fate, and filtered. The solvent was removed on a rotary evaporaꢀ
tor. The crude product, which was obtained as a darkꢀred powꢀ
der in a yield of 5.5 g, was divided into two equal portions. Each
portion was chromatographed on a column (l 20 cm, d 2.9 cm)
with aluminum oxide. Ferrocene was eluted with light petroꢀ
leum. Three fractions, viz., 4ꢀnitrobiphenyl, 4ꢀnitroꢀ4´ꢀferroꢀ
cenylbiphenyl with a small impurity of 4ꢀnitrobiphenyl, and
pure 4ꢀnitroꢀ4´ꢀferrocenylbiphenyl, were eluted with a 1 : 2
light petroleum—chloroform mixture. 4ꢀNitrobiphenyl was exꢀ
tracted from the second fraction with two portions of boiling
light petroleum (2×10 mL). From two portions, 4ꢀnitroꢀ4´ꢀ
ferrocenylbiphenyl was obtained in a yield of 2.2 g (41%) as
4ꢀAminoꢀ4´ꢀcyanobiphenyl (3c). A solution of 90% sodium
hydrosulfide monohydrate (1.90 g, 0.023 mol) in water (15 mL)
was added dropwise with stirring to a boiling suspension of
4ꢀnitroꢀ4´ꢀcyanobiphenyl (2.70 g, 0.012 mol) in methanol
(110 mL) during 15 min. The reaction mixture was refluxed with
stirring for 6 h, during which 4´ꢀcyanoꢀ4ꢀnitrobiphenyl was comꢀ
pletely dissolved. The methanolic solution was concentrated on
a rotary evaporator and the residue was treated with water
(150 mL). The precipitate of the amine that formed was filtered
off, washed on a filter with water (4×25 mL), and dried in air.
The product was purified by chromatography on a column
(l 20 cm, d 2.5 cm) with aluminum oxide. 4ꢀAminoꢀ4´ꢀ
cyanobiphenyl was eluted with chloroform in a yield of 1.95 g
(83%), m.p. 180—184 °C (cf. lit. data7: m.p. 182—184 °C).
4´ꢀNitroꢀ4ꢀbiphenyldiazonium tetrafluoroborate (1b). Hydroꢀ
chloric acid (36%; 15 mL) was added to a suspension of 4ꢀaminoꢀ
4´ꢀnitrobiphenyl (3.83 g, 0.018 mol) in water (120 mL). The
reaction mixture was cooled with ice to 2 °C and then a solution
of sodium nitrite (1.44 g, 0.021 mol) in water (16 mL) was added
dropwise with stirring during 15 min. The reaction mixture was
stirred at 2—4 °C for 30 min and then a solution of ammonium
tetrafluoroborate (2.20 g, 0.021 mol) in water (15 mL) was added,
after which the reaction mixture turned paleꢀpink and solidified.
Then the mixture was kept with periodic stirring at 3—4 °C for
40 min. The precipitate that formed was filtered off, washed on a
filter with cold water (2×35 mL) and ether (2×30 mL), and dried
in air. 4´ꢀNitroꢀ4ꢀbiphenyldiazonium tetrafluoroborate was obꢀ
tained as a paleꢀpink powder (t.decomp. >125—127 °C) in a
yield of 4.90 g (87%). The precipitation with diethyl ether from
a solution in acetonitrile afforded pure 4´ꢀnitroꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate. Found (%): C, 46.03; H, 2.42;
N, 13.54. C12H8BF4N3O2. Calculated (%): C, 46.05; H, 2.58;
N, 13.42.
4´ꢀBromoꢀ4ꢀbiphenyldiazonium tetrafluoroborate (1a). The
synthesis was carried out analogously to the synthesis of 4´ꢀnitroꢀ
4ꢀbiphenyldiazonium tetrafluoroborate. 4´ꢀBromoꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate was prepared from 4ꢀaminoꢀ4´ꢀ
bromobiphenyl (6.0 g) in a yield of 7.37 g (88%) as a yellow
powder, t.decomp. >128 °C. Pure 4´ꢀbromoꢀ4ꢀbiphenyldiꢀ
azonium tetrafluoroborate was obtained by precipitation with
diethyl ether from a solution in acetonitrile. Found (%): C, 41.29;
H, 2.09; N, 7.87. C12H8BBrF4N2. Calculated (%): C, 41.55;
H, 2.32; N, 8.07.
4´ꢀCyanoꢀ4ꢀbiphenyldiazonium tetrafluoroborate (1c). The
synthesis was carried out analogously to the synthesis of 4´ꢀnitroꢀ
4ꢀbiphenyldiazonium tetrafluoroborate. 4´ꢀCyanoꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate was prepared from 4ꢀaminoꢀ4´ꢀ
cyanobiphenyl (2.91 g) in a yield of 3.75 g (85%) as a yellow
powder, t.decomp. >129—131 °C. Pure 4´ꢀcyanoꢀ4ꢀbiphenyldiꢀ
azonium tetrafluoroborate was obtained by precipitation with

614
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
Lemenovskii et al.
cherryꢀred crystals, m.p. 230—233 °C (decomp.). Found (%):
C, 68.86; H, 4.47; N, 3.72. C22H17FeNO2. Calculated (%):
C, 68.95; H, 4.47; N, 3.65. 1H NMR, δ: 4.05 (s, 5 H, C5H5);
4.36 (m, 2 H, C(7)H, C(8)H); 4.69 (m, 2 H, C(6)H, C(9)H);
7.56 (m, 4 H, Ar); 7.74 (m, 2 H, Ar); 8.28 (m, 2 H, Ar). IR,
ν/cm–1: 1340 (NO2); 1520 (NO2).
Table 3. Crystallographic data and details of Xꢀray diffraction
study of compounds 2b and 2c
Parameters
2b
2c
Molecular formula
Molecular weight
Crystal system
Space group
T/К
C22H17FeNO2
383.22
Monoclinic
P21/c
C23H17FeN
363.23
4ꢀCyanoꢀ4´ꢀferrocenylbiphenyl (2c). 4´ꢀCyanoꢀ4ꢀbiphenylꢀ
diazonium tetrafluoroborate (2.3 g, 0.0078 mol) was added
portionwise with stirring to a solution of ferrocene (2.18 g,
0.0117 mol) in a mixture of 1,2ꢀdichloroethane (10 mL), glacial
acetic acid (62 mL), and trifluoroacetic acid (10 mL) at ~20 °C
for 15 min. The reaction mixture was stirred for 5 h and then
kept without stirring at ~20 °C for 12 h, after which water
(200 mL) and chloroform (100 mL) were added. The aqueous
layer was separated and extracted with chloroform (50 and
30 mL). The combined organic extracts were washed with water
(3×100 mL) and dried with magnesium sulfate. The chloroform
was distilled off on a rotary evaporator and the crude product
was obtained in a yield of 2.3 g. The product was chromatoꢀ
graphed on a column (l 24 cm, d 2.5 cm) with aluminum oxide.
Ferrocene was eluted with light petroleum and then 4ꢀcyanoꢀ
4´ꢀferrocenylbiphenyl was eluted with a 1 : 5 light petroꢀ
leum—benzene mixture in a yield of 1.17 g (41%), m.p.
189—196 °C. The product was treated with boiling light petroꢀ
leum (2×15 mL) and 4ꢀcyanoꢀ4´ꢀferrocenylbiphenyl was obꢀ
tained in a yield of 0.94 g (33%), m.p. 195—198 °C. Found (%):
C, 75.93; H, 4.75; N, 3.78. C23H17FeN. Calculated (%):
C, 76.05; H, 4.72; N, 3.86. 1H NMR, δ: 4.06 (s, 5 H, C5H5);
4.36 (m, 2 H, C(7)H, C(8)H); 4.69 (m, 2 H, C(6)H, C(9)H);
7.53—7.71 (m, 8 H, Ar). IR, ν/cm–1: 2238 (CN).
4ꢀEthylthioꢀ4´ꢀferrocenylbiphenyl (4). Sodium ethylthiolate
(0.25 g, 2.98 mmol) and anhydrous hexamethylphosphoramide
(15 mL) were added to 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl (0.40 g,
0.96 mmol). The reaction mixture was stirred under argon at
95 °C for 2.5 h until 4ꢀbromoꢀ4´ꢀferrocenylbiphenyl was comꢀ
pletely consumed (TLC control). After cooling to ~20 °C, the
reaction mixture was poured into a mixture of 36% hydrochloric
acid (7 mL) and water (100 mL). The aqueous phase was exꢀ
tracted with diethyl ether (100 mL). The organic layer was sepaꢀ
rated, dried with magnesium sulfate, and filtered. The ether was
removed in vacuo. The residue was chromatographed on a colꢀ
umn (l 6.5 cm, d 2.5 cm) with aluminum oxide. 4ꢀEthylthioꢀ4´ꢀ
ferrocenylbiphenyl was eluted with a 1 : 4 benzene—light petroꢀ
leum mixture in a yield of 0.25 g (66%). After recrystallizaꢀ
tion from light petroleum, 4ꢀethylthioꢀ4´ꢀferrocenylbiphenyl
was obtained as orange crystals in a yield of 0.23 g (61%),
m.p. 174—176 °C. Found (%): C, 72.56; H, 5.58; Fe, 14.11.
C24H22FeS. Calculated (%): C, 72.37; H, 5.57; Fe, 14.02.
1H NMR, δ: 1.35 (t, 3 H, Me, 3J = 7.2 Hz); 2.99 (q, 2 H, CH2S,
3J = 7.2 Hz); 4.06 (s, 5 H, C5H5); 4.33 (m, 2 H, C(7)H, C(8)H);
4.67 (m, 2 H, C(6)H, C(9)H); 7.38—7.56 (m, 8 H, Ar).
Triclinic
P–1
168(2)
100(2)
Z
8
2
a/Å
b/Å
c/Å
α/deg
10.700(2)
30.986(6)
10.145(2)
90
98.64(3)
90
3325.6(11)
1.531
0.923
7.6572(11)
9.3248(3)
12.6740(18)
74.468(2)
74.446(3)
87.711(3)
839.5(2)
1.437
β/deg
γ/deg
V/Å3
dcalc/g cm–3
Absorption coefficient,
µ/mm–1
0.902
F(000)
1584
θ/2θ
2—26
376
ω
2—30
Scan mode
θ Scan range/deg
Number of measured
reflections
Number of independent
reflections
Rint
Number of refinable
parameters
GOOF
6890
7861
6513
4647
0.1504
469
0.0207
294
1.050
4270
0.961
3730
Number of reflections
with I ≥ 2σ(I )
Final R factors
(for reflections with I ≥ 2σ(I )):
R1
wR2
0.0568
0.1282
0.0368
0.0852
R factors for all reflections:
R1
wR2
0.1223
0.1509
0.0507
0.0906
Residual electron
density/e•Å–3
–1.225/0.441
–0.349/0.548
(dmin/dmax
)
The structures of 2b and 2c were solved by direct methods
and refined isotropically by the fullꢀmatrix leastꢀsquares method.
The Xꢀray data for compound 2c were processes with the use of
the SAINT program.11 The absorption correction was applied
using the SADABS program.12 The final refinement was carried
out by the fullꢀmatrix leastꢀsquares method with anisotropic
thermal parameters. The positions of the hydrogen atoms were
calculated geometrically and refined using the riding model. All
calculations were carried out with the use of the SHELXTL
program package13 on IBM PC.
Xꢀray diffraction study. Crystals of 4ꢀnitroꢀ4´ꢀferrocenylꢀ
biphenyl (2b) and 4ꢀcyanoꢀ4´ꢀferrocenylbiphenyl (2c) suitable
for Xꢀray diffraction analysis were grown by the gradual addition
of light petroleum to solutions of 2b and 2c in benzene. Xꢀray
diffraction data for compounds 2b and 2c were collected on a
fourꢀcircle automated SyntexꢀP21 diffractometer and a SMART
Bruker diffractometer (graphite monochromator, λ(MoꢀKα) =
0.71073 Å) at 168 and 100 К, respectively. The crystallographic
data are given in Table 3.
This study was financially supported by the Russian
Foundation for Basic Research (Project Nos. 00ꢀ03ꢀ32840
and 03ꢀ03ꢀ32716).

Synthesis and structure of biphenylferrocenes
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 3, March, 2003
615
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11. SMART V5.051 and SAINT V5.00, Area Detector Control and
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12. G. M. Sheldrick, SADABS, Program for Empirical Absorption
Correction of Area Detector Data, University of Göttingen,
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13. G. M. Sheldrick, SHELXTLꢀ97, V5.10, Bruker AXS Inc.,
Madison (WIꢀ53719, USA), 1997.
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Received October 9, 2002