Silyl derivatives of ferrocene with pending indenyl or fluorenyl substituets at silicon

Article abstract of DOI:10.1016/S0022-328X(02)01560-7

The reactions of chlorosilyl-substituted ferrocenes with indenyl lithium and fluorenyl lithium have been used to synthesise new ferrocene derivatives in which 1-indenyl (ind) or 9-fluorenyl (flu) substituents are connected with the ferrocene sandwich through a silicon bridge. In addition to the monosubstituted indenyl-silyl- and fluorenyl-silyl-ferrocenes Fc-SiMe₂(ind) (1a), Fc-SiMe₂(flu) (1b), Fc-SiMe(Ph)(flu) (2b), Fc-SiMe(flu)₂ (3b) and Fc-SiCl(flu)₂ (4b), the 1,1′-disubstituted ferrocenes fc[SiMe₂(ind)]₂ (5a) and fc[SiMe₂(flu)]₂ (5b) as well as the 1-sila-[1]ferrocenophanes fc[SiMe(ind)] (6a) and fc[SiMe(flu)] (6b) were included in this study. The products were characterised in solution by ¹H-, ¹³C- and ²⁹Si-NMR spectroscopy and by mass spectrometry. The molecular structures of the di(fluorenyl)silyl ferrocenes 3b and 4b and of the 1-sila-[1]ferrocenophanes 6a and 6b were determined by single crystal X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(02)01560-7

Journal of Organometallic Chemistry 656 (2002) 71Á80
/
www.elsevier.com/locate/jorganchem
Silyl derivatives of ferrocene with pending indenyl or fluorenyl
substituents at silicon
Max Herberhold *, Anahid Ayazi, Wolfgang Milius, Bernd Wrackmeyer *
Laboratorium fur Anorganische Chemie der Universitat Bayreuth, Postfach 101251, D-95440 Bayreuth, Germany
¨ ¨
Received 22 January 2002; received in revised form 2 April 2002; accepted 25 April 2002
Dedicated to Professor Gottfried Huttner on the occasion of his 65th birthday
Abstract
The reactions of chlorosilyl-substituted ferrocenes with indenyl lithium and fluorenyl lithium have been used to synthesise new
ferrocene derivatives in which 1-indenyl (ind) or 9-fluorenyl (flu) substituents are connected with the ferrocene sandwich through a
silicon bridge. In addition to the monosubstituted indenyl-silyl- and fluorenyl-silyl-ferrocenes FcÃ
/
SiMe2(ind) (1a), FcÃ
/
SiMe2(flu)
(1b), FcÃSiMe(Ph)(flu) (2b), FcÃSiMe(flu)2 (3b) and FcÃSiCl(flu)2 (4b), the 1,1?-disubstituted ferrocenes fc[SiMe2(ind)]2 (5a) and
/
/
/
fc[SiMe2(flu)]2 (5b) as well as the 1-sila-[1]ferrocenophanes fc[SiMe(ind)] (6a) and fc[SiMe(flu)] (6b) were included in this study. The
products were characterised in solution by 1H-, 13C- and 29Si-NMR spectroscopy and by mass spectrometry. The molecular
structures of the di(fluorenyl)silyl ferrocenes 3b and 4b and of the 1-sila-[1]ferrocenophanes 6a and 6b were determined by single
crystal X-ray crystallography. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Ferrocenes; Silanes; Indenyl; Fluorenyl; X-ray
1. Introduction
been described. According to the X-ray structure
determination of the fluorenyl compound A [3], the
conformational arrangement of the two h5-cyclopenta-
The synthesis of ferrocenes bearing planar substitu-
ents such as cyclopentadienyl (Cp), indenyl (ind) or
fluorenyl (flu) in the side-chain has attracted some
interest because these groups are able to act as ligand
functionalities for the construction of di- and trinuclear
complexes (which may incorporate different metals). In
the present study the indenyl and fluorenyl derivatives
are preferentially investigated, because the large indenyl
and fluorenyl substituents were found to reduce the
number of isomers which are formed, and because they
are more flexible compared to cyclopentadienyl with
respect to ring slippage in additional complexations.
Both 1,1?-bis(dimethylindenylmethyl)ferrocene, Fe[C5-
dienyl rings [4] in the crystal is tꢀ
/
171.38, i.e. the
molecule approaches the staggered conformation (tꢀ
/
1808) although it is not centrosymmetric [3].
H4Ã
/
CMe2(ind)]2 [1], and 1,1?-bis(dimethylfluorenyl-
methyl)ferrocene, Fe[C5H4Ã
/CMe2(flu)]2 (A) [2,3], have
A series of ferrocenyl-indenyl compounds without or
* Corresponding authors. Tel.: ꢁ
552157
E-mail
Herberhold), b.wrack@uni-bayreuth.de (B. Wrackmeyer).
/
49-921-552540; fax: ꢁ
/
49-921-
with spacer (Ã
/
CH2Ã
/
, Ã
/
CÅ
/
CÃ
/
, Ã
/
C6H4Ã
/
) between the
two groups and their CpFe adducts have also been
addresses:
max.herberhold@uni-bayreuth.de
(M.
described [31].
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 5 6 0 - 7

72
M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á80
/
We now report on some silyl-substituted ferrocene
derivatives in which the 1-indenyl or 9-fluorenyl sub-
stituents are attached to silicon.
2. Results and discussion
2.1. Synthesis
Scheme 2.
The lithiation of ferrocene (FeCp2, FcH) can be
conducted selectively to give either monolithio-ferro-
cene, FcLi [5] (using t-BuLi in THF solution), or 1,1?-
dilithio-ferrocene, fcLi2(tmeda)n (nꢀ1 or 2) [6] (using
/
n-BuLi in hexane in the presence of tetramethylethyle-
nediamine). Subsequent reactions of the lithiated ferro-
cenes with methylchlorosilanes lead to the chlorosilyl-
substituted ferrocene derivatives 1Á
which had been characterised previously [7Á
Starting from monolithio-ferrocene, the monosubsti-
tuted ferrocenes 1Á4 were prepared. Starting from 1,1?-
/
6 (Schemes 1 and 2)
/
12].
/
dilithio-ferrocene, either 1,1?-disilyl-substituted ferro-
cenes (such as 5) or 1-sila-[1]ferrocenophanes (such as
6) became accessible.
Scheme 3.
The reactions of the chlorosilyl-substituted ferrocenes
1Á
and fluorenyl lithium afforded the desired 1-indenyl (a)
and 9-fluorenyl (b) derivatives 1a,b, 2bÁ4b, 5a,b and
6a,b (Scheme 3) under concomitant formation of LiCl.
Attempts to prepare the 1-indenyl analogues of 2bÁ4b
were not successful so far. Although two 9-fluorenyl
substituents at silicon are tolerated (3b and 4b), the last
chloro substituent in 4b could not be displaced for a
third fluorenyl group.
/
5 and the 1-sila-[1]ferrocenophane 6 with indenyl-
Table 1 contains a comparison of the bond lengths
and angles of the three fluorenyl complexes 3b, 4b and
/
6b. The two di(9-fluorenyl)-substituted silanes, FcÃ
/
SiMe(flu)2 (3b) and FcÃSiCl(flu)2 (4b), both form
/
/
¯
triclinic crystals with space group P1; they are crowded
molecules like di(9-fluorenyl)dimethylsilane, SiMe2(flu)2
[14]. The two cyclopentadienyl rings of the ferrocene
unit are nearly parallel (tilt angle aꢀ2.6 and 0.78 in 3b
/
and 4b, respectively, cf. Table 3) and adopt an almost
ecliptic conformation (with twist angles of 2.5 and 1.48,
respectively, cf. Table 3). As expected, the dihedral
angles between the plane of the substituted cyclopenta-
dienyl ring and the respective fluorenyl system differ
considerably: in the case of 3b, the angles are 85.0 and
48.38, while in the case of 4b the angles are 86.5 and
112.88, i.e. in both complexes one of the two fluorenyl
substituents is arranged in an almost orthogonal posi-
tion relative to the ferrocene cyclopentadienyl rings. The
dihedral angles between the two fluorenyl planes are
117.68 in 3b and 122.38 in 4b; the corresponding angles
are 80.1 and 96.88 in the two non-identical molecules of
SiMe2(flu)2 [14] which are present in the orthorhombic
crystal.
All indenyl (1a, 5a, 6a) and fluorenyl (1bÁ6b) com-
/
plexes showed the molecular ion [Mꢁ] in the electron-
impact mass spectra. The peak of highest intensity
(100%) always corresponds to the fragment ion gener-
ated from [Mꢁ] by loss of one indenyl or fluorenyl
group.
2.2. X-ray studies
The molecular structures of di(9-fluorenyl)methylsi-
lyl- and di(9-fluorenyl)chlorosilyl-ferrocene (3b and 4b,
respectively, Fig. 1) and of the two 1-sila-[1]ferroceno-
phanes 6a and 6b (Fig. 2) were determined by X-ray
crystallography; selected bond lengths and angles are
collected in Tables 1 and 2.
The bond angles around silicon are found within the
range expected for a basically tetrahedral geometry
(109.58), i.e. between 105 and 1158 in 3b and between
103 and 1168 in 4b, cf. 105Á
bond vectors from Si to the fluorenyl substituents (SiÃ
C(9)) and SiÃC(9?)) include an angle with the respective
/
1128 in SiMe2(flu)2 [14]. The
/
/
fluorenyl plane which is 137.2 (flu) and 146.68 (flu?) in 3b
as well as 145.4 and 131.38 in 4b. Therefore, the valence
Scheme 1.

M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á
/80
73
Fig. 1. Molecular structures of FcÃ
/
SiMe(flu)2 (3b) and FcÃSiCl(flu)2 (4b).
/
angle C(9)Ã
/
SiÃ
/
C(9?) is only slightly larger than the ideal
6a (272.5 pm) than in 6b (269.2 pm). Similar non-
bonding FeÁ Á ÁSi distances have been found in fc[SiMe2]
(269.0 pm [20]) and fc[SiMe(Fc)] (270.8 pm [19]), the
shortest distance was reported for the case of fc[SiPh2]
(268 pm [21]).
It is not surprising that the ferrocenophane unit in
both 6a and 6b is a highly symmetrical building block,
the cyclopentadienyl rings are arranged exactly ecliptic
tetrahedral angle of 109.58. The tetrahedral coordina-
tion sphere of silicon in ferrocenyl-substituted silanes
has been confirmed in many cases, e.g. in SiFc4 [15],
Si(Fc)2(OH)2 [16], FcÃ
Me2Fc]2 [19].
/
SiMe2SiMe2Ã/Fc [17] and fc[Si-
In 3b and 4b the bulky di(9-fluorenyl)silyl substituents
(R) are slightly bent outwards from their respective
cyclopentadienyl planes, away from iron (cf. angles b in
Table 3). The reverse situation is characteristic of 1-sila-
[1]ferrocenophanes [18,19a], including 6a and 6b. The 1-
indenyl substituent in 6a (see Table 2) apparently
(tꢀ0, cf. Table 3), and the Si atom is found in the plane
/
which is determined by the Fe atom and the midpoints
of the cyclopentadienyl rings. It is remarkable, however,
that the planes of the indenyl and fluorenyl substituents,
respectively, are nearly perpendicular to the plane
containing Fe, Si and the methyl carbon and bisecting
the ferrocenophane unit, [Fe(C5H4)2Si], the dihedral
tolerates smaller deviation angles (bꢀ
the larger 9-fluorenyl substituent in 6b (bꢀ
i.e. the non-bonding distance FeÁ Á ÁSi is slightly longer in
/
37.08 av) than
/
38.28 av);
Fig. 2. Molecular structures of fc[SiMe(ind)] (6a) and fc[SiMe(flu)] (6b).

74
M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á80
/
Table 1
Selected bond lengths (pm) and bond angles (8) in the fluorenyl
complexes 3b, 4b and 6b
Table 2
Selected bond lengths (pm) and bond angles (8) in 1-methyl-1-indenyl-
sila-[1]ferrocenophane, fc[SiMe(ind)] (6a)
˚
Bond lengths (A)
Complex
FcÃSiMe(flu)2
(3b)
FcÃSiCl(flu)2
(4b)
fc[SiMe(flu)]
(6b)
Bond angles (8)
SiÃC(1)
SiÃC(6)
SiÃC(11)
SiÃC(20)
SiÁ Á ÁFe
189.5(4)
188.3(4)
187.8(4)
184.9(5)
272.5
C(1)ÃSiÃC(6)
C(1)ÃSiÃC(11)
C(1)ÃSiÃC(20)
C(6)ÃSiÃC(11)
C(6)ÃSiÃC(20)
C(11)ÃSiÃC(20)
C(11)Ã SiÃFe
C(20)ÃSiÃFe
95.34(18)
111.34(18)
112.1(2)
˚
Bond lengths (A)
SiÃC(9)
SiÃC(9?)
SiÃC(14)
SiÃC(19)
SiÃC(24)
SiÃCl
192.4(4)
191.0(5)
184.6(5)
189.1(2)
189.1(2)
183.6(2)
189.1(5)
110.28(19)
114.5(2)
112.2(2)
187.9(5)
187.8(5)
184.3(6)
187.3(5)
FeÃC(1)
FeÃC(2)
FeÃC(3)
FeÃC(4)
FeÃC(5)
FeÃC(6)
FeÃC(7)
FeÃC(8)
200.9(4)
202.9(4)
208.0(4)
209.0(4)
202.8(5)
202.1(4)
203.2(4)
208.1(4)
207.9(4)
203.6(4)
150.5(6)
150.7(5)
132.8(6)
146.5(7)
138.8(7)
139.6(6)
137.6(7)
138.7(6)
139.0(6)
140.0(6)
122.67(14)
125.10(18)
206.91(10)
FeÃC(14)
FeÃC(15)
FeÃC(16)
FeÃC(17)
FeÃC(18)
FeÃC(19)
FeÃC(20)
FeÃC(21)
FeÃC(22)
FeÃC(23)
FeÁ Á ÁSi
C(1)ÃC(2)
C(1)ÃC(10)
C(2)ÃC(3)
C(3)ÃC(4)
C(4)ÃC(11)
C(5)ÃC(6)
C(5)ÃC(12)
C(6)ÃC(7)
C(7)ÃC(8)
C(8)ÃC(13)
C(9)ÃC(10)
C(9)ÃC(13)
C(10)ÃC(11)
C(11)ÃC(12)
C(12)ÃC(13)
205.4(4)
203.4(4)
203.7(5)
206.6(5)
204.2(4)
205.5(5)
203.1(5)
204.1(5)
204.2(5)
204.0(5)
204.7(2)
204.2(2)
205.4(2)
205.3(2)
203.2(2)
204.1(3)
203.4(3)
204.0(3)
204.1(3)
204.7(3)
202.2(5)
202.0(5)
207.2(6)
206.9(6)
202.2(6)
200.7(5)
202.9(5)
206.7(5)
206.7(6)
203.0(5)
269.2
SiÃC(1)ÃC(2)
SiÃC(1)ÃC(5)
SiÃC(11)ÃC(12)
SiÃC(11)ÃC(18)
SiÃFeÃC(1)
120.8(3)
118.3(3)
112.3(3)
111.7(3)
44.05(12)
43.71(12)
FeÃC(9)
SiÃFeÃC(6)
FeÃC(10)
C(11)ÃC(12)
C(11)ÃC(18)
C(12)ÃC(13)
C(13)ÃC(19)
C(14)ÃC(15)
C(14)ÃC(19)
C(15)ÃC(16)
C(16)ÃC(17)
C(17)ÃC(18)
C(18)ÃC(19)
C(12)ÃC(11)ÃC(18)
C(11)ÃC(12)ÃC(13)
C(12)ÃC(13)ÃC(19)
C(11)ÃC(18)ÃC(19)
C(13)ÃC(19)ÃC(18)
101.5(3)
111.3(4)
110.1(4)
109.9(4)
107.0(4)
137.8(7)
138.6(7)
135.7(10)
137.3(10)
141.7(8)
136.4(12)
139.8(8)
135.4(13)
142.7(11)
138.3(8)
151.0(6)
151.4(7)
140.3(7)
142.9(8)
139.9(8)
139.6(5)
135.8(4)
137.9(6)
137.0(5)
138.6(4)
137.5(4)
139.4(4)
135.7(5)
139.4(4)
137.8(4)
151.4(3)
152.2(3)
140.1(4)
146.1(4)
138.9(3)
138.8(9)
138.9(8)
138.1(10)
136.9(9)
138.7(8)
135.3(10)
139.6(8)
138.3(11)
139.0(9)
138.0(8)
150.5(7)
151.1(7)
140.3(7)
145.1(8)
140.4(8)
indenyl plane is 146.98 in 6a, the corresponding angle
C(9) vector (189.1(5) pm) and the
between the SiÃ
/
fluorenyl plane 147.28 in 6b.
The angles at the pseudo-tetrahedral silicon centre are
comparable in 6a and 6b. While the intra-ferroceno-
phane angles are small (C(1)Ã
and C(14)ÃSiÃC(19)ꢀ96.8(2)8 in 6b), all other angles
CÃSiÃC are found between 110 and 1158, somewhat
/
SiÃ
/
C(6)ꢀ95.34(18)8 in 6a
/
Bond angles (8)
C(9)ÃSiÃC(14) 105.50(19)
C(9?)ÃSiÃC(14) 114.8(2)
C(9)ÃSiÃC(24) 106.4(2)
C(9?)ÃSiÃC(24) 111.6(2)
C(9)ÃSiÃC(9?) 110.2(2)
C(9)ÃSiÃC(19)
C(9)ÃSiÃFe
C(9)ÃSiÃCl
C(9?)ÃSiÃCl
C(14)ÃSiÃCl
115.32(11)
106.98(11)
109.9(2)
111.2(3)
/
/
/
/
/
larger than the ideal tetrahedral angle of 109.58.
The dihedral angles (a) between the two cyclopenta-
dienyl ring planes (Table 3) are found to be 21.28 in 6a
and 20.28 in 6b, which are typical values for 1-sila-
[1]ferrocenophanes [15,18]. Comparable inclination an-
gles a have been observed for fc[SiCl2] (19.2(4)8 [13]),
fc[SiPh2] (19.28 [21]), fc[SiMe2] (20.8(5)8 [15,20]) and
fc[SiMe(Fc)] (21.38 [19a]). The inclination of the two
cyclopentadienyl ring planes (angle a) can also be
characterised by the angle d at the iron atom between
114.69(11)
111.5(2)
122.49(17)
107.68(8)
103.04(8)
108.28(8)
C(14)ÃSiÃC(19)
C(14)ÃSiÃC(24) 107.9(2)
C(19)ÃSiÃC(24)
96.8(2)
114.3(3)
112.4(3)
SiÃC(9)ÃC(10) 117.1(3)
SiÃC(9)ÃC(13) 116.5(3)
SiÃC(14)ÃC(15) 132.0(3)
SiÃC(14)ÃC(18) 122.2(3)
SiÃC(14)ÃFe
113.32(16)
112.23(16)
129.05(17)
124.00(19)
111.5(3)
110.0(4)
119.0(4)
118.7(4)
87.2(2)
SiÃC(19)ÃFe
87.7(2)
angles being 95.0 (6a) and 87.18 (6b), respectively. The
angle between the SiÃC(11) vector (187.8(4) pm) and the
/
Scheme 4.

M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á
/80
75
Table 3
Geometry of the ferrocene unit in complexes 3b, 4b, 6a and 6b
Complex
3b
4b
0.7
6a
21.2
6b
20.2
a
a [8]
b [8]
2.6
9.8 (outwards)
b
11.8 (outwards)
36.8
37.2
164.2
0
38.4
38.0
c
d [8]
t [8]
q [8]
177.6
2.5
178.9
1.4
164.6
0
96.8(2)
d
e
95.34(18)
a
Inclination of the two cyclopentadienyl ring planes.
b
c
Deviation of the silyl substituent from its cyclopentadienyl plane.
Angle at iron between the two centers of the cyclopentadienyl rings.
Conformative deviation of the cyclopentadienyl rings from the ecliptic form (tꢀ0).
Angle at silicon within the [1]ferrocenophane unit.
d
e
Table 4
1H- and 29Si-NMR data of the starting complexes 1Á
/
6 and fluorenyl derivatives 1bÁ6b in CDCl3
/
aAssigned according to NOE and 2D 13CÁ1
/
H HETCOR experiments for 1b, 3b and 6b. bExcept of the 1H(SiMe) and 1H(Cp) signals all other
signals appear as multiplets which were not analysed.

76
M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á80
/
Table 5
13C-NMR data of the starting complexes 1Á
/6 and fluorenyl derivatives 1bÁ/6b in CDCl3
No. Complex
Ferrocene
Fluorenyl
Cp
Ci
Ca
Cb
CH3(Si)
C1,C8
124.6
C2,C7 C3,C6
C4,C5 C9
125.95 120.6 43.3 146.4
43.5 145.4
C10, C13
C11,C12
141.3
cf.
1
SiMe3(flu) [26]
FcÃSiMe2Cl
ꢂ2.5
2.9
126.6
125.6
a
a
68.0
68.17 68.24 73.7
68.3
72.9
71.7
1b
2
FcÃSiMe2(flu)
FcÃSiMe(Ph)Cl
70.9 ꢂ4.2
124.5
b
125.1
119.7
140.5
b
68.8
66.9
73.5
73.4
74.4
73.9
73.0
70.7
71.8
71.7
1.5
c
2b
FcÃSiMe(Ph)(flu)
68.3
66.3
71.5 ꢂ7.8
70.8
124.9
124.4
125.8
125.6
125.3
125.3
119.7
119.5
42.0 145.0
144.8
140.7
140.5
c
3
3b
FcÃSiMeCl2
FcÃSiMe(flu)2
69.3
68.1
66.0
65.5
or 72.3
6.5
a
a
73.9 ꢂ4.3
124.9
124.9
126.1
125.9
125.7
125.6
120.1
119.8
41.0 145.2
144.9
141.1
140.8
4
4b
FcÃSiCl3
FcÃSiCl(flu)2
69.4
68.8
69.8
64.4
73.7
71.6
72.9
74.1
125.1
124.4
124.7
126.4
126.3
126.0
125.1
125.7
119.9
119.8
42.2 142.8
142.7
141.3
141.1
a
a
a
5
fc[SiMe2Cl]2
fc[SiMe2(flu)]2
fc[SiMeCl]
69.3
69.1
33.5
73.3
73.8
75.7
73.6
75.3
75.2
72.5
2.9
5b
6
71.6 ꢂ4.2
125.6
126.3
119.7
119.7
43.4 145.2
37.7 143.0
140.4
140.6
78.6
78.3
0.4
a
6b
fc[SiMe(flu)]
36.7
33.6
71.6 ꢂ9.9
77.5
a
Assignment to Ca confirmed by NOE and/or 2D 13CÁ1
H HETCOR experiments (see Section 2.3).
/
b
c
13C-NMR data of the phenyl substituent in 2: 136.0 (i), 133.5 (o), 130.2 (p), 127.9 (m)d.
13C-NMR data of the phenyl substituent in 2b: 136.8 (i), 134.3 (o), 129.4 (p), 127.8 (m)d.
13C-NMR data for PhÃSiMe3: 140.1 (i), 133.4 (o), 128.9 (p), 127.8 (m) [25].
d
the two midpoints of the cyclopentadienyl rings (Table
3).
For the assignment of the 13C-NMR signals to the
cyclopentadienyl carbon atoms Ca and Cb, 2D 13CÁ1
/
H
HETCOR experiments were used in several cases (1/1b,
3/3b, 5/5b, 6/6b). The 13C-NMR signal for the quatern-
ary ipso carbon atom, Ci, can easily be identified on the
basis of its low intensity and ATP (attached proton test)
experiments. The complexes 2 and 2b, in which each
silicon atom bears four different substituents, show four
different signals for the 1H and 13C atoms in the
positions a, a? and b, b?. A similar situation with
four different cyclopentadienyl signals (a, a?, b, b?) is
characteristic of the 1-sila-[1]ferrocenophanes 6, 6a and
6b; two 13Ci-NMR signals are observed in 6a and 6b but
not in the parent complex fc[SiMeCl] (6) (d(13Ci) 33.5).
2.3. NMR spectra
1
The H-, 13C- and 29Si-NMR spectroscopic data of
the new indenyl and fluorenyl complexes are compiled in
the Tables 4Á7. The following numbering scheme has
/
been used for the ferrocene unit and for the indenyl and
fluorenyl substituents (Scheme 4).
In the case of the fluorenyl substituents in the
complexes 1bÁ6b, the NMR numbering system corre-
/
sponds to that used in the X-ray-determined molecular
structures of the three fluorenyl derivatives 3b, 4b and 6b
(Figs. 1 and 2).
The chirality of the indenyl compounds, FcÃ
/SiMe2(ind)
1
(1a) and fc[SiMe2(ind)]2 (5a), can be deduced from the
fact that 1a possesses two and 5a four methyl signals
The H-NMR signals of the ferrocene sandwich units
were assigned to the hydrogens in positions a (close) and
b (distant), relative to the substituent R, on the basis of
1D and 2D NOE experiments for the complexes 1b, 3b,
5b and 6a,b. For example, irradiation into the methyl
1
both in the H and 13C spectra (cf. Tables 6 and 7),
whereas a single signal is observed in the spectra of the
parent chlorosilanes FcÃ/SiMe2Cl (1) and fc[SiMe2Cl]2
absorption (d(1H) 0.21) of FcÃ
/
SiMe(flu)2 (3b) gives the
(5) as well as in the corresponding fluorenyl compounds,
1b and 5b.
NOE response for the pseudo-triplet at d 4.19 which
therefore corresponds to the a protons. The number of
The chemical shifts d(29Si) change in the usual way
[24] dependent on the substituent pattern. The influence
of indenyl and fluorenyl groups on d(29Si) is very similar
in the complexes 1a,b and 5a,b, whereas the 29Si nuclear
shielding in the [1]ferrocenophane 6a is slightly in-
creased by 3.4 ppm with respect to the fluorenyl
derivative 6b, although the relevant structural para-
assigned ferrocene H- and 13C-NMR signals in related
complexes is limited in the literature, but the data
reported for fc[SiMe3]2 [22], fc[SiMe2Cl]2 (5) [12], and
1
for
fc[SnMe2Cl]2, fc[SnMeCl2]2, fc[SnCl3]2 [23] are fully
consistent with the assignments given in the Tables 1Á3.
the
stannyl-substituted
series
fc[SnMe3]2,
/

M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á
/80
77
Table 6
1H- and 29Si-NMR data of the indenyl complexes 1a, 5a and 6a in CDCl3
aIf not indicated otherwise all 1H-NMR signals are multiplets except of the 1H(SiMe) and 1H(Cp) signals. b 3J(H1, H2)ꢀ1.9 Hz, 4J(H1, H3)ꢀ1.6
Hz. c 3J(H2, H3)ꢀ5.3 Hz, 3J(H2, H1)ꢀ1.9 Hz. d 3J(H3, H2)ꢀ5.3 Hz, 4J(H3, H1)ꢀ1.6 Hz, 4J(H3, H4)ꢀ0.7 Hz. eAssignment to Ha confirmed by
NOE and/or 2D 13CÁ1
H HETCOR experiments.
/
meters for 6a and 6b differ only slightly in the solid state
(vide supra).
3.1.1. Instrumentation
1H-, 13C- and 29Si-NMR spectroscopy: Bruker ARX
250 (CDCl3 solutions); typical mixing times for NOE
experiments [28] were 0.8Á
/
1.2 s; 2D 13CÁ1
/
H HETCOR
180 Hz, using
experiments were based on J(13C, H)ꢀ
/
1
1
the BIRD pulse for suppression of non-geminal HÁ1
/
H
1
3. Experimental
coupling [29]; 29Si-NMR spectra were recorded by using
1
refocused INEPT experiments with H decoupling [30].
Mass spectrometry: Finnigan MAT 8500 (EI-MS). X-
ray crystallography: Siemens P4 Four-Circle-Diffrac-
3.1. General
tometer (3b, 4b and 6b), STOE IPDS (6a); MoÁ
/
Ka
The syntheses were carried out in Schlenk vessels
under purified Ar, using carefully dried and oxygen-free
solutions. The solvents were dried under reflux (C6H14
over Na/K alloy, THF over LiAlH4 and CH2Cl2 over
P4O10) and distilled before use in a stream of Ar.
radiation (lꢀ71.073 pm) with graphite monochroma-
/
tor; crystals were sealed under Ar in Lindemann
capillaries. The crystal data and experimental details
of the structure determination are given in Table 8.
Table 7
13C-NMR data of the indenyl complexes 1a, 5a and 6a in CDCl3
aAssignment to Ca confirmed by NOE and 2D 13CÁ1
H HETCOR experiments.
/

78
M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á80
/
Table 8
Crystal data and experimental details of the structure determinations
a
b
Complex
3b
4b
6a
6b
Formula
C
38H32FeSi
C36H27ClFeSi
578.97
C20H17FeSi
341.28
C24H20FeSi
392.34
Molecular mass
Diffractometer
Temperature (K)
643.48
Siemens P4
293(2)
Siemens P4
296(2)
0.71073
STOE IPDS
293(2)
0.71073
Siemens P4
293(2)
0.71073
˚
Wave length (A)
0.71073
Triclinic
Crystal system
Space group
Unit cell dimensions
Triclinic
¯
Orthorhombic
Pbca
Monoclinic
P21/c
¯
/
P1/
/
P1/
˚
a (A)
10.6640(12)
12.2043(11)
14.1828(19)
65.448(7)
70.113(9)
77.647(7)
1573.1(3)
2
9.9345(14)
10.6423(17)
13.4753(14)
77.240(9)
84.402(9)
82.753(10)
1374.8(3)
2
19.350(4)
7.6250(15)
21.579(4)
7.943(2)
13.192(3)
18.230(6)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
101.87(2)
3
V (A )
˚
3183.9(11)
8
1869.4(9)
4
Z
Dcalc (g cmꢂ3
)
1.358
0.714
1.339
0.714
1.424
1.015
1.394
0.875
Absorption coefficient
(mmꢂ1
)
Crystal size (mm)
Theta range (u)
Index ranges
0.18ꢃ0.14ꢃ0.12
0.25ꢃ0.18ꢃ0.12
1.97 to 27.50
ꢂ125h 51,
ꢂ135k 513,
ꢂ175l 517
7314
0.20ꢃ0.16ꢃ0.06
2.16 to 28.08
ꢂ255h 525,
ꢂ105k 59,
ꢂ285l 528
28065
0.25ꢃ0.16ꢃ0.12
1.92 to 25.00
ꢂ95h 51,
ꢂ15k 515,
ꢂ215l 521
4389
1.65Á24.99
/
ꢂ15h 512,
ꢂ135k 513,
ꢂ165l 516
6309
Reflections observed
Independent reflections
Rint
5371
0.0271
6238
0.0583
3848
0.1259
3266
0.0692
Absorption correction
Max/min transmission
R[I ꢀ2s(I)]
Empirical (c-scans)
0.4657/0.3781
R1ꢀ0.0618
0.1815
Empirical (c-scans)
0.4124/0.3667
R1ꢀ0.0440
0.0980
Numerical
-
Empirical (c-scans)
0.4466/0.3254
R1ꢀ0.0622
0.1495
R1ꢀ0.0471
0.0985
wR2
a
The hydrogen atoms are in calculated positions. All non-hydrogen atoms were refined with anisotropic temperature factors. The hydrogen atoms
were refined applying the riding model with fixed isotropic temperature factors.
b
The elementary cell contains 2 molecules CH2Cl2.
3.2. Synthesis of the educts 1Á
/
6
3.2.2. Preparation of the chlorosilyl-ferrocene educts
3.2.1. Lithiation of ferrocene (general procedures)
(a) Ferrocene (5.00 g, 26.88 mmol) was dissolved in 30
ml of THF. In the course of 15 min a solution of 26.9
mmol t-BuLi (17.9 ml of a 1.5 M C5H12 solution) was
added dropwise at 0 8C. Hexane (40 ml) was then
3.2.2.1. Chlorodimethylsilyl-ferrocene, FcÃ
/
SiMe2Cl (1).
A THF solution (20 ml) containing 0.67 g (3.5 mmol)
FcLi was dropwise added to a THF solution (10 ml) of
1.67 ml (13.9 mmol) SiMe2Cl2 at ꢂ30 8C. The com-
30 8C and
/
bined solutions were kept for 30 min at ꢂ
/
added, and the solution was kept at ꢂ
/
78 8C for 15 min,
then stirred over night at room temperature (r.t.). The
solvent THF was evaporated together with the excess of
SiMe2Cl2 under vacuum, the orange residue dissolved in
C6H14 (30 ml) and the solution filtered over Na2SO4.
The solvent C6H14 was removed under vacuum and the
product heated to 50 8C under high vacuum for 1 h in
order to sublime the impurities of ferrocene off. The
remaining dark-orange oil (yield 0.69 g, 70.75%) can be
used directly for further reactions (cf. [7], yield 78%, b.p.
before the orange precipitate was filtered off, washed
with small portions of C6H14 and dried in a high vacuum
(10ꢂ2 mbar). Yield: 4.50 g (87.2%) FcLi.
(b) Ferrocene (5.00 g, 26.88 mmol) was dissolved in
100 ml of C6H14. A solution containing 9.2 ml (60
mmol) tetramethylethylenediamine (tmeda) and 35 ml
(56 mmol) of a 1.6 M C6H14 solution of n-BuLi in 30 ml
of C6H14 was then dropwise added, and the reaction
mixture was stirred over night. The orange precipitate of
fcLi2 (tmeda) was collected and directly used for further
reactions.
98Á
The educts 2Á
manner.
/
100 8C/0.5 mmHg).
/
4 were obtained in an analogous

M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á
/80
79
3.2.3. Chloromethylphenylsilyl-ferrocene,
FcÃSiMe(Ph)Cl (2)
3.3. Synthesis of the indenyl- and fluorenyl-substituted
silanes
/
Starting from 1.20 g (6.25 mmol) FcLi, dissolved in 50
ml of THF, and 4.0 ml (25 mmol) SiMe(Ph)Cl2 in 20 ml
of THF, a crop of 1.43 g (67%) yellow crystals was
obtained by crystallisation from a concd. C6H14 solution
3.3.1. General procedure
About 3 mmol of the chlorosilyl educt (1Á
dissolved in 20Á50 ml of THF, and a THF solution (40Á
50 ml) containing a slight excess (5Á15%) of the
respective stoichiometric amount of either indenyl- or
fluorenyl-lithium is slowly added at ꢂ30 8C. The
/
6) are
/
/
at ꢂ80 8C.
/
/
/
3.2.4. Dichloromethylsilyl-ferrocene, FcÃ
/
SiMeCl2 (3)
solution is stirred at r.t. for 20 h (over night). The
solvent THF is then evaporated in a high vacuum (10ꢂ2
mbar) and the residue redissolved in C6H14, CH2Cl2 or
mixtures of these solvents. After filtration over Na2SO4,
the solutions were cooled to ꢂ
products in nearly all cases.
The reaction of a THF solution (20 ml) containing
1.40 g (7.29 mmol) FcLi with another THF solution (10
ml) containing 3.4 ml (29 mmol) SiMeCl3 gave, after
workup, 1.50 g (68.8%) FcÃ
/
SiMeCl2 as a dark-orange
/
80 8C to give crystalline
oil (cf. [9], 23%, dark-red crystalline solid, b.p. 130 8C/
0.05 mmHg).
3.3.2. FcÃ
/
SiMe2(ind) (1a)
Starting from 1.10 g (3.9 mmol) 1 and 0.50 g (4.10
mmol) indenyl-lithium, a dark-orange oil was obtained
(1.07 g, 76.6%) which could not be crystallised. EI-MS:
3.2.5. Trichlorosilyl-ferrocene, FcÃ
/
SiCl3 (4)
A solution of 2.60 g (13.54 mmol) FcLi in dimethox-
yethane (DME, 10 ml) was added dropwise to 7.0 ml (61
mmol) SiCl4, and the reaction mixture was stirred over
night. The solvent was evaporated and the residue
dissolved in 30 ml of C5H12. The C5H12 solution was
filtered over Na2SO4, brought to dryness and the residue
heated to 50 8C under high vacuum. Yellow powder of
m/eꢀ
/
358 [Mꢁ, 77%], 234 (
/
FcÃSiMeꢁ2 ; 100%).
3.3.3. FcÃ
Crystallisation from C6H14 gave 0.54 g (73.5%)
yellowÁorange crystals, m.p. 70Á72 8C. EI-MS: m/
eꢀ
408 [Mꢁ, 73%], 243 (FcÃSiMeꢁ2 ; 100%).
/
SiMe2(flu) (1b)
/
/
/
/
FcÃ
/
SiCl3, yield 2.7 g (64.3%) (cf. [10], yield 25% after
77 8C).
vacuum sublimation, m.p. 75Á
/
3.3.4. FcÃ
/
SiMe(Ph)(flu) (2b)
The reaction of 0.33 g (0.97 mmol) 2 with 0.17 g (0.99
mmol) fluorenyl-lithium gave, after crystallisation from
3.2.6. 1,1?-Bis[chloromethylsilyl]ferrocene,
fc[SiMe2Cl]2 (5)
C6H14Á
yield 0.37 g (81%). EI-MS: m/eꢀ
(FcÃ
SiMePhꢁ, 100%).
/
CH2Cl2 (1:4) orange crystals, m.p. 75Á
/
77 8C,
470 [Mꢁ, 92%], 305
A suspension of 8.44 g (26.87 mmol) fcLi2(tmeda) in
C6H14 (100 ml) was added dropwise to a C6H14 solution
(40 ml) of 12.9 ml (107.4 mmol) SiMe2Cl2. The reaction
mixture was stirred for 4 h. The volatile components
(including SiMe2Cl2 and tmeda) were removed under
high vacuum. The residue was redissolved in C6H14, and
/
/
3.3.5. FcÃ
Yellow crystals (from C6H14), m.p. 78Á
0.55 g (50%). EI-MS: m/eꢀ
558 [Mꢁ, 27%], 393 (FcÃ
SiMe(flu)ꢁ, 100%).
/
SiMe(flu)2 (3b)
/
81 8C, yield
/
/
the solution was filtered over Na2SO4. The orangeÁ
solution was concentrated to ca. 20 ml and cooled to ꢂ
80 8C over night. Orange crystals of fc[SiMe2Cl]2, yield
5.40 g (54.1%) (cf. [11], yellowÁorange solid, m.p.
89 8C).
/
red
/
3.3.6. FcÃ
/
SiCl(flu)2 (4b)
/
The reaction of 0.27 g (0.82 mmol) 4 with 0.31 g (1.80
mmol) fluorenyl-lithium (in 80 ml THF) produced, after
crystalisation from CH2Cl2, yellow crystals (0.27 g
(56.9%), m.p. 219 8C (dec.). EI-MS: m/eꢀ
/
578 [Mꢁ,
3.2.7. 1-Chloromethylsila-[1]ferrocenophane,
fc[SiMeCl] (6)
A C6H14 solution (100 ml) of 3.4 ml (29 mmol)
65%], 413 (FcÃ
/
SiCl(flu)ꢁ, 100%).
3.3.7. fc[SiMe2(ind)]2 (5a)
Orange oil, yield 0.30 g (47%). EI-MS: m/eꢀ
[Mꢁ, 81%], 415 (fc(SiMe2)2(ind)ꢁ, 100%), 300
fc(SiMe2)ꢁ2 ; 62%).
SiMeCl3 was slowly added at ꢂ78 8C to the educt
/
/
530
fcLi2(tmeda) which had been prepared from 5.00 g
(26.88 mmol) ferrocene (see above). The reaction
mixture was stirred over night, then brought to dryness
and the residue redissolved in C6H14. Filtration over
(/
Na2SO4 and concentration to ca. 20 ml gave an orangeÁ
/
3.3.8. fc[SiMe2(flu)]2 (5b)
Yellow crystals from C6H14Á
206 8C, yield 75%. EI-MS: m/eꢀ
(fc(SiMe2)2(flu)ꢁ, 100%), 300 (fc(SiMe2)ꢁ2 ; 12%).
red C6H14 solution. Upon cooling to ꢂ80 8C, orangeÁ
/
/
/
CH2Cl2 (1:2), m.p. 204Á
/
red crystals of fc[SiMeCl] were obtained, yield 5.95 g
(84.3%) (cf. !27![13], yield 88%).
/
630 [Mꢁ, 65%], 465
/

80
M. Herberhold et al. / Journal of Organometallic Chemistry 656 (2002) 71Á80
/
[12] A. Spannenberg, P. Arndt, M. Oberthur, R. Kempe, Z. Anorg.
¨
Allg. Chem. 623 (1997) 389.
3.3.9. fc[SiMe(ind)] (6a)
The reaction of 0.66 g (2.51 mmol) 6 with 0.34 g (2.78
mmol) indenyl-lithium in 70 ml of THF gave, upon
[13] D.L. Zechel, K.C. Hultzch, R. Rulkens, D. Balaishis, Y. Ni, J.K.
Pudelski, A.J. Lough, I. Manners, Organometallics 15 (1996)
1972.
crystallisation from C6H14Á
/
CH2Cl2 (2:1), 0.57 g (66%)
342 [Mꢁ,
red crystals, m.p. 149Á
/
153 8C. EI-MS: m/eꢀ
/
[14] L. Silaghi-Dumitrescu, I. Haiduc, R. Cea-Olivares, I. Silaghi-
100%], 227 (fc[SiMe]ꢁ, 69%).
Dumitrescu, J. Escudie´, C. Couret, J. Organomet. Chem. 545Á
/
546
(1997) 1.
[15] M.J. MacLachlan, A.J. Lough, W.E. Geiger, I. Manners,
Organometallics 17 (1998) 1873.
[16] M.J. MacLachlan, M. Ginzburg, J. Zheng, O. Knoll, A.J. Lough,
¨
3.3.10. fc[SiMe(flu)] (6b)
YellowÁ
/
orange crystals (from CH2Cl2), m.p. 142Á
/
145 8C, yield 66%. EI-MS: m/eꢀ
392 [Mꢁ, 100%],
/
I. Manners, New J. Chem. (1998) 1409.
227 (fc[SiMe]ꢁ, 100%).
[17] V.V. Deme´ntev, F. Cervantes-Lee, L. Parka´nyi, H. Sharma, K.H.
Pannell, M.T. Nguyen, P. Diaz, Organometallics 12 (1993) 1983.
[18] M. Herberhold, Angew. Chem. 107 (1985) 1985; M. Herberhold,
Angew. Chem. Int. Ed. Engl. 34 (1985) 1837.
4. Supplementary information
[19] (a) K.H. Pannell, V.V. Dementiev, H. Li, F. Cervantes-Lee, M.T.
Nguyen, A.F. Diaz, Organometallics 13 (1994) 3644;
(b) M.Y. Antipin, I.I. Vorontsov, I.I. Dubovik, V. Papkov, F.
Cervantes-Lee, K.H. Pannell, Can. J. Chem. 78 (2000) 1511.
[20] W. Finckh, B. Tang, D.A. Foucher, D.B. Zambie, R. Ziembinski,
A. Lough, I. Manners, Organometallics 12 (1993) 823.
[21] (a) H. Stoeckli-Evans, A.G. Osborne, R.H. Whiteley, Helv. Chim.
Acta 59 (1976) 2402;
Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre,
CCDC nos. 186753 (3b), 186754 (4b), 186755 (6a) and
186752 (6b). Copies of this information may be obtained
free of charge from the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK [Fax: ꢁ44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk].
(b) cf. H. Stoeckli-Evans, A.G. Osborne, R.H. Whiteley, J.
Organomet. Chem. 194 (1980) 91.
[22] F.H. Kohler, W.A. Geike, N. Hertkorn, J. Organomet. Chem. 334
¨
/
(1987) 359.
[23] M. Herberhold, W. Milius, U. Steffl, K. Vitzithum, B. Wrack-
meyer, R.H. Herber, M. Fontani, P. Zanello, Eur. J. Inorg. Chem.
(1999) 145.
Acknowledgements
[24] (a) H. Marsmann, in: R. Diehl, E. Fluck, R. Kosfeld (Eds.),
NMR*Basic Principles and Progress, vol. 17, Springer, Berlin,
/
1981, p. 65;
Support of this work by the Deutsche Forschungsge-
meinschaft, the Deutsche Akademische Austauschdienst
(DAAD) and the Fonds der Chemischen Industrie is
gratefully acknowledged.
(b) E. Kupce, E. Lukevics, in: E. Buncel, J.R. Jones (Eds.),
Isotopes in the Physical and Biomedical Sciences, vol. 2, Elsevier,
Amsterdam, 1991, pp. 213Á295.
[25] E. Pretsch, J. Seibl, W. Simon, Th. Clerc, Tabellen zur Struktur-
/
aufklarung organischer Verbindungen mit spektroskopischen
¨
Methoden, 3rd ed., Springer-Verlag, Berlin, New York, Heidel-
berg, 1990.
References
[26] (a) I.V. Borisova, N.N. Zemlyanskii, Yu.N. Luzikov, Yu.A.
Ustynyuk, V.K. Belskii, N.D. Kolosova, M.M. Shtern, I.P.
Be´letskaya, Dokl. Akad. Nau´k SSSR 269 (1983) 369;
(b) I.V. Borisova, N.N. Zemlyanskii, Yu.N. Luzikov, Yu.A.
Ustynyuk, V.K. Belskii, N.D. Kolosova, M.M. Shtern, I.P.
Be´letskaya, Chem. Abstr. 99 (1983) 105383.
[1] P. Escarpa Gaede, J. Organomet. Chem. 616 (2000) 29.
[2] H.G. Alt, R. Zenk, J. Organomet. Chem. 512 (1996) 51.
[3] R. Broussier, M. Laly, P. Perron, B. Gautheron, S. M’Koyan, P.
Kalck, N. Wheatley, J. Organomet. Chem. 574 (1999) 267.
[4] cf. M. Herberhold, Y.-X. Cheng, G.-X. Jin, W. Milius, Z.
Naturforsch. Teil B 55 (2000) 814.
[27] Yu.N. Luzikov, N.M. Sergeyev, Yu.A. Ustynyuk, J. Organomet.
Chem. 65 (1974) 303.
[5] F. Rebiere, O. Samuel, H.B. Kagan, Tetrahedron Lett. 31 (1990)
3121.
[28] (a) G. Bodenhausen, H. Kogler, R.R. Ernst, J. Magn. Reson. 58
(1984) 370;
[6] M.D. Rausch, D.J. Ciappenelli, J. Organomet. Chem. 10 (1967)
127.
(b) G. Wider, S. Macura, A. Kumar, R.R. Ernst, K. Wuthrich, J.
¨
Magn. Reson. 56 (1984) 207.
[7] K.H. Pannell, H. Sharma, Organometallics 10 (1991) 954.
[8] M.D. Rausch, G.C. Schloemer, Org. Prep. Proced. 1 (1969) 131.
[9] D. Foucher, R. Ziembinski, R. Petersen, J. Pudelski, M. Edwards,
Y. Ni, J. Massey, C.R. Jaeger, G.J. Vancso, I. Manners,
Macromolecules 27 (1994) 3992.
[29] (a) J.R. Garbow, D.P. Weitekamp, A. Pines, Chem. Phys. Lett. 93
(1982) 504;
(b) V. Rutar, Chem. Phys. Lett. 106 (1984) 258.
[30] (a) G.A. Morris, R. Freeman, J. Am. Chem. Soc. 101 (1979) 760;
(b) G.A. Morris, J. Am. Chem. Soc. 102 (1980) 428;
(c) D.P. Burum, R.R. Ernst, J. Magn. Reson. 39 (1980) 163.
[31] S.-G. Lee, S.S. Lee, Y.K. Chung, Inorg. Chim. Acta 286 (1999)
215.
[10] M.S. Wrighton, M.C. Palazzotto, A.B. Bocarsly, J.M. Bolts, A.B.
Fischer, L. Nadjo, J. Am. Chem. Soc. 100 (1978) 7264.
[11] D.L. Zechel, D.A. Foucher, J.K. Pudelski, G.P.A. Yap, A.L.
Rheingold, I. Manners, J. Chem. Soc. Dalton Trans. (1995) 1893.