Highly efficient reduction of ferrocenyl derivatives by borane

Article abstract of DOI:10.1016/S0022-328X(01)00936-6

Borane, as a DMS or a THF complex, can efficiently reduce a large range of ferrocenyl derivatives (aldehydes, ketones, ethers, acetals, carboxylic acids, esters,...) if they bear at least one oxygen at a carbon at the α position. On the contrary, similar molecules, which contain nitrogen instead of oxygen, do not react with borane.

Full text of DOI:10.1016/S0022-328X(01)00936-6

Journal of Organometallic Chemistry 637–639 (2001) 364–371
www.elsevier.com/locate/jorganchem
Highly efficient reduction of ferrocenyl derivatives by borane
Lucie Routaboul, Je´roˆme Chiffre, Gilbert G.A. Balavoine, Jean-Claude Daran,
Eric Manoury *
Laboratoire de Chimie de Coordination, LCC-CNRS, 205 route de Narbonne, F-31004 Toulouse, France
Received 10 January 2001; received in revised form 27 February 2001; accepted 28 February 2001
Abstract
Borane, as a DMS or a THF complex, can efficiently reduce a large range of ferrocenyl derivatives (aldehydes, ketones, ethers,
acetals, carboxylic acids, esters,…) if they bear at least one oxygen at a carbon at the a position. On the contrary, similar
molecules, which contain nitrogen instead of oxygen, do not react with borane. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Iron; Ferrocene; Reduction; Borane
1. Introduction
Thus each of the 3 hydrogens of borane can be trans-
ferred. Further, BH3·THF can be used instead of
BH3·SMe2 with a similar efficiency (Table 1, entry 6).
Various aldehydes and ketones have been successfully
reduced into the corresponding alkylferrocenes (Table
1, entries 7–13). Even hindered compounds like 2-
tris(n-butyltin)ferrocenecarboxaldehyde (1b) and 2-
diphenylphosphinoferrocene-carboxaldehyde (1c) can
be quantitatively converted. In particular, 2-tris(n-
butyltin)ferrocenecarboxaldehyde (1b) have been re-
duced without any detectable loss of the tris(n-butyl)tin
group whereas it was completely removed by using
TiCl4–NaBH3CN [6] or TiCl4–HSiEt3 [7] as the reduc-
ing agents [8].
Borane is very active in the reduction of aldehydes or
ketones. Therefore, as it is interesting to know if ferro-
cenyl alcohols can also be reduced to alkylferrocenes
under similar conditions, various primary, secondary
and tertiary a-ferrocenyl alcohols have been tested (see
Table 2). Within 30 min the different alcohols were
quantitatively converted into the corresponding alkyl-
ferrocenes (Table 2, entries 1–7) except for the ex-
tremely hindered ferrocenyl(t-butyl)methanol (2d)
which required 4 h to be completely reduced (Table 2,
entry 4). Only 1-phenyl-1-ferrocenylethanol (2f) could
not be reduced as it had been quickly and quantita-
tively dehydrated to a-ferrocenylstyrene (24) (Table 2,
entry 6). Moreover, the 2-ferrocenyl-1,2-ethanediol (2h)
had been selectively transformed to 2-ferrocenylethanol
(26) even in the presence of a very large excess of
Ferrocene chemistry was revived during the last years
because ferrocenyl derivatives have found numerous
uses in various fields of science from biology to materi-
als chemistry [1]. However, the main achievements with
ferrocenes have been found in asymmetric catalysis [2].
During the course of our studies on ferrocenes with
various substitution patterns [3,4], we observed that
during the protection of a diphenylphosphinoferrocene
bearing an aldehyde function by borane, the formyl
group was not reduced to a hydroxymethyl group as
expected [5] but to a methyl group. This unusual reac-
tivity of borane initiated us to study the reducing power
of borane on the various ferrocenyl derivatives.
2. Results and discussion
We first studied the reduction of ferrocenecarbox-
aldehyde by BH3·SMe2 (see Table 1). Ferrocenecarbox-
aldehyde (1a) was quantitatively reduced into
methylferrocene (13) even at room temperature (Table
1, entry 1). Two equivalents of borane (0.67 mol of BH3
per mole of FcCHO) are sufficient for the complete
reduction to methylferrocene (13) (Table 1, entry 5).
* Corresponding author. Tel.: +33-5-61-33-3186; fax: +33-5-61-
33-3131.
E-mail address: manoury@lcc-toulouse.fr (E. Manoury).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00936-6

L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
365
borane (Table 2, entries 8 and 9); the hydroxy group in
the a position from the ferrocene is completely removed
leaving the other unactivated hydroxy group
untouched.
Owing to the high reducing power of the borane–
methylsulfide complex, we tried other functions like
ethers and acetals, which are normally not reduced by
boranes [5]. These compounds, even the crowded ones,
could be easily transformed to the corresponding alkyl-
ferrocenes if they bore a ferrocenyl group at the a
carbon (Table 3, entries 1–4)
known to be slowly reduced to alcohols. Therefore, the
methyl ferrocenecarboxylic ester (8) has been tested
under the same conditions; the reaction was much
slower than for ferrocenecarboxylic acid but yielded
exclusively methylferrocene (13) without traces of alco-
hol (Table 3 entry 6). We also tested amides and nitriles
that are known to be reduced by borane to amines [5].
N,N-Dimethyl-ferrocenecarboxamide (9) has been
quickly reduced with an excess of borane to a mixture
of methylferrocene (13) (17%) and N,N-dimethyl-
aminomethylferrocene (11) (74%) (Table 3, entry 7).
First, we thought that methylferrocene was obtained
from N,N-dimethylaminomethylferrocene. Therefore,
increasing the reaction time, should allow more amine
to be converted into methylferrocene. However, if the
Borane is also known to reduce the carboxylic acids
into alcohols [5] efficiently. In our study, ferrocenecar-
boxylic acid (7) was quantitatively reduced into methyl-
ferrocene (13) (Table 3 entry 5). Similarly, esters are
Table 1
Reduction of ferrocenyl aldehydes and ketonesa
Entry Substrate
Borane (amount Reaction time
Product (yield) c
in equivalents) b
1
2
3
4
5
6
7
FcCHO (1a)
FcCHO (1a)
FcCHO (1a)
FcCHO (1a)
FcCHO (1a)
FcCHO (1a)
(S)-2-Tris(n-butyltin)-
ferrocene-carboxaldehyde (1b)
(S)-2-Diphenylphosphino-
ferrocene-carboxaldehyde (1c)
1,1%-Ferrocene-dicarboxaldehyde (1d)
Acetylferrocene (1e)
1,1%-Diacetylferrocene (1f)
FcC(O)CH2CH2CH3 (1g)
FcC(O)Ph (1h)
BH3·SMe2 (12)
BH3·SMe2 (12)
BH3·SMe2 (3)
BH3·SMe2 (3)
BH3·SMe2 (2.1) 15 min
BH3·THF (3)
BH3·THF (3)
16 h d
15 min
1 h
FcCH3 (13) (97%)
FcCH3 (13) (96%)
FcCH3 (13) (97%)
FcCH3 (13) (99%)
FcCH3 (13) (98%)
FcCH3 (13) (97%)
(S)-2-(Tris(n-butyltin)) methylferrocene (14) (92%)
15 min
15 min
15 min
8
BH3·THF (3)
16 h d
(S)-2-(Diphenyl(trihydridoboryl)
(phosphino)methylferrocene. (15) (99%)
1,1%-Dimethylferrocene (16) (96%)
Ethylferrocene (17) (99%)
1,1’-Diethylferrocene (18) (99%)
FcCH2CH2CH2CH3 (19) (97%)
FcCH2Ph (20) (99%)
9
10
11
12
13
BH3·THF (6)
BH3·SMe2 (3)
BH3·SMe2 (6)
BH3·SMe2 (3)
BH3·SMe2 (3)
15 min
15 min
15 min
15 min
5 min
a Reaction conditions: in THF at reflux (concentration in substrate=ca. 0.2 mol l−1).
b In equivalents/substrat considering 3H available on borane.
c Isolated yield.
d Reaction carried out at RT instead of THF reflux.
Table 2
Reduction of ferrocenyl alcoholsa
Entry Substrate
Borane (amount in
equivalents) b
Reaction time
Product (yield) c
1
2
3
FcCH2OH (2a)
FcCHPhOH (2b)
BH3·SMe2 (3)
BH3·SMe2 (3)
BH3·SMe2 (3)
15 min
15 min
30 min
FcCH3 (13) (97%)
FcCH2Ph (20) (98%)
(4-Methoxyphenyl)-
ferrocenylmethanol (2c)
FcCHt-BuOH (2d)
FcCHn-BuOH (2e)
FcC(CH3)PhOH (2f)
FcC(CH3)2OH (2g)
FcCHOHCH2OH (2h)
FcCHOHCH2OH (2h)
(4-methoxyphenyl)-ferrocenylmethane (21)
(96%)
FcCH2t-Bu (22)(97%)
FcCH2n-Bu (23) (99%)
a-ferrocenylstyrene (24) (98%)
FcCH(CH3)2 (25)
4
5
6
7
8
9
BH3·SMe2 (3)
BH3·SMe2 (3)
BH3·SMe2 (3)
BH3·SMe2 (3)
BH3·SMe2 (6)
BH3·SMe2 (24)
4 h
30 min
15 min
15 min
1 h
FcCH2CH2OH (26) (87%)
FcCH2CH2OH (26) (93%)
1 h
a Reaction conditions: in THF at reflux (concentration in substrate=ca. 0.2 mol l−1).
b In equivalents/substrat considering 3H available on borane.
c Isolated yield.

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L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
Table 3
Reduction of various ferrocenyl compoundsa
Entry
Substrate
Borane (amount in
equivalents) b
Reaction time
Product (yield) c
1
2
3
4
5
6
FcCH2OMe (3)
BH3·SMe2 (12)
BH3·SMe2 (12)
BH3·SMe2 (3)
BH3·SMe2 (12)
BH3·SMe2 (12)
BH3·SMe2 (12)
15 min
15 min
30 min
3 h
30 min
16 h
FcCH3 (13) (93%)
FcCH3 (13) (96%)
FcCH3 (13) (87%)
FcCH3 (13) (97%)
FcCH3 (13) (95%)
FcCH3 (13) (61%) FcCOOMe 8
(38%)
2-Ferrocenyl-1,3-dioxane (4)
2-Ferrocenyl-1,3-dioxolane (5)
4-(Methoxymethyl)-2-ferrocenyl)-1,3-dioxane (6)
FcCOOH (7)
FcCOOMe (8)
7
8
FcC(O)NMe2 (9)
FcC(O)NMe2 (9)
BH3·SMe2 (12)
BH3·SMe2 (12)
1 h
FcCH3 (13) (17%) FcCH2NMe2 (11)
(74%)
FcCH3 (13) (18%) FcCH2NMe2 (11)
(75%)
18 h
9
10
11
FcCN (10)
FcCH2NMe2 (11)
FcCH2NMe3,I (12)
BH3·SMe2 (12)
BH3·SMe2 (12)
BH3·SMe2 (12)
16 h
18 h
18 h
No conversion
No conversion
No conversion
a Reaction conditions: in THF at reflux (concentration in substrate=ca. 0.2 mol l−1).
b In equivalents/substrat considering 3H available on borane.
c Isolated yield.
Scheme 1.
gered. The absolute configuration for molecule 15 was
confirmed by refining Flack’s enantiopole parameter
[10] and agrees with the synthetic pathway used.
In compound 20 (Fig. 1) it is interesting to point out
that the benzyl moiety CH2C6H5 is pointing away from
the ferrocene fragment. The dihedral angle between the
phenyl ring and the corresponding Cp ring is 96.8°.
Such an arrangement has been already observed in
related compounds as the 1,3,1%,3%-tetrabenzylbifer-
rocene [11] and in the 1,1%-di(p-bromobenzyl)biferro-
cene [12].
Compound 15 (Fig. 2) presents one of the rare
structural examples of a ferrocenyl phosphine bearing a
BH3 group. Indeed, to the best of our knowledge, only
three structures, the (S,S)-1,1%-bis((t-butyl)methyl-
(trihydridoboryl)phosphino) ferrocene [13], the (S,S)-
1,1% - bis ( 2 - methoxyphenyl ( phenyl ) ( trihydridoboryl )-
phosphino) ferrocene [14] and the 1,1%-bis(diphenyl(tri-
hydridoboryl)phosphino) ferrocene [15], have been re-
reaction time was increased from 1 to 18 h, the same
reaction mixture was obtained (Table 3, entry 8). More-
over, as the N,N-dimethylaminomethylferrocene (11)
did not react with borane (Table 3, entry 11) the amine
could not be reduced further to methylferrocene (13).
Even the methylated (ferrocenylmethyl)-trimethylam-
monium iodide (12) which possesses a much better
leaving group than the corresponding amine was left
untouched by borane (Table 3, entry 10). Strangely,
ferrocenylcyanide (10) which possesses a nitrile func-
tion, usually reduced by borane [5,9], did not react
either (Table 3, entry 9).
During the course of our studies, crystals suitable for
X-ray analysis have been obtained for benzylferrocene
(20), 2-methyl-1-diphenyl(trihydroboryl)phosphino fer-
rocene (15) and for 1-phenyl-1-ferrocenylethanol (2f)
(see Scheme 1).
The molecular views and the atom-labelling scheme
are shown in Figs. 1–3. Important bond distances and
bond angles are given in Table 4. In the three com-
pounds mentioned above, the geometry of the ferrocene
framework is as expected and the FeꢀC and CꢀC
distances are within the usual range found for such
molecules. In compounds 20 and 2f, the Cp rings are
perfectly eclipsed whereas in 15 they are slightly stag-
,
ported so far. The BꢀP bond length of 1.923(3) A is
comparable to the values found in the above com-
,
pounds. The phosphorus atom lies 0.124 A above the
plane of the Cp ring whereas the boron atom is dis-
,
placed by 0.912 A out of this plane towards the iron.
This displacement of the boron towards the iron is

L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
367
Fig. 1. CAMERON view of molecule 20 with atom labelling scheme.
Ellipsoids are drawn at 50% probability.
Fig. 3. CAMERON view of molecule 2f with atom labelling scheme.
Ellipsoids are drawn at 50% probability.
certainly responsible for the slightly staggered confor-
mation (13.5°) of the Cp rings. Nevertheless, there is a
,
short HꢀH contact of 2.36 A between one of the H of
the BH3 group and the H attached to the C(10) atom of
the Cp ring below.
In compound 2f (Fig. 3), there is an unusual in-
tramolecular hydrogen bond between the OH group
and the iron as shown not only by the relative orienta-
tion of the OH towards the iron but also by the rather
,
short 2.94(3) A Fe···H distance. This distance is less
,
than the sum of the van der Waals radii (3.77 A) but
definitely more than the sum of the covalent radii (1.75
,
A) typical of a weak interaction. This Fe···H interaction
is confirmed by the larger dihedral angle, 4.31°, ob-
served between the Cp ring when compare with the
values of 0.8 and 1.1° observed in compounds 20 and
15, respectively. This Fe···H interaction is a good illus-
tration of the basicity of the iron atom in ferrocenes
[16]. To the best of our knowledge, there is only one
structural example of such intramolecular interaction
between a hydroxy group and an iron atom (dFeꢀH
=
4
,
2.99(3) A) in the h -a-[(RS)-(1Z,3E)-3-[(R)-1-hydroxy-
but-3-enyl]-1-p-tolylsulfinyl-1,3-pentadien-5-ol]-tricar-
bonyl-iron(0) complex [17].
In conclusion, borane, as a THF or SMe2 complex,
can efficiently reduce a large range of a-ferrocenyl
compounds (aldehydes, ketones, alcohols, carboxylic
acids, esters, ethers, acetals,…) to the corresponding
Fig. 2. CAMERON view of molecule 15 with atom labelling scheme.
Ellipsoids are drawn at 50% probability.

368
L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
Table 4
In the reduction of aldehydes, ketones, carboxylic
acids or esters, borates are the probable intermediates
which can be reduced to alkylferrocenes. In the case of
alcohols, borates can also be reactive intermediates (see
Scheme 2) but the complexation of borane on the
oxygen of the alcohols could be responsible for the
activation of the CꢀO bond towards reduction. These
type of intermediates are, for us, the most probable for
the molecules lacking an hydroxy group, namely ethers
and acetals. For N,N-dimethylferrocenecarboxamide,
we proved that methylferrocene did not come from a
reduction of N,N-dimethylaminomethylferrocene so we
proposed that a common intermediate (A) can be re-
duced to methylferrocene or N,N-dimethylaminomethyl
ferrocene in 18:74 ratio (see Scheme 2).
,
Important bond lengths (A) and bond angles (°)
Compound 20
Bond lengths
C(1)ꢀC(2)
C(1)ꢀC(5)
C(2)ꢀC(3)
C(3)ꢀC(4)
C(4)ꢀC(5)
C(1)ꢀC(11)
1.417(3)
1.426(3)
1.422(3)
1.413(3)
1.418(3)
1.498(3)
C(6)ꢀC(7)
C(6)ꢀC(10)
C(7)ꢀC(8)
C(8)ꢀC(9)
C(9)ꢀC(10)
C(11)ꢀC(111)
1.412(5)
1.365(4)
1.422(4)
1.374(4)
1.344(4)
1.513(3)
Bond angles
C(2)ꢀC(1)ꢀC(11)
124.97(19) C(5)ꢀC(1)ꢀC(11)
127.85(18)
C(11)ꢀC(111)ꢀC(112) 121.98(18) C(11)ꢀC(111)ꢀC(116) 119.26(18)
C(1)ꢀC(11)ꢀC(111)
114.84(16)
Compound 15
Bond lengths
P(1)ꢀC(111)
P(1)ꢀB(1)
C(1)ꢀC(2)
C(1)ꢀC(5)
C(2)ꢀC(3)
C(3)ꢀC(4)
C(4)ꢀC(5)
C(1)ꢀC(11)
1.817(3)
1.923(3)
1.449(4)
1.426(4)
1.439(3)
1.402(4)
1.411(5)
1.488(4)
P(1)ꢀC(121)
P(1)ꢀC(2)
C(6)ꢀC(7)
C(6)ꢀC(10)
C(7)ꢀC(8)
C(8)ꢀC(9)
C(9)ꢀC(10)
1.824(3)
1.784(3)
1.378(7)
1.452(7)
1.382(6)
1.355(6)
1.400(7)
3. Experimental
Ferrocenecarboxaldehyde (1a), 1,1%-dimethylfer-
rocene (16), acetylferrocene (1e), ethylferrocene (17),
1,1%-diacetylferrocene (1f), butyrylferrocene (1g), butyl-
ferrocene (19), benzoylferrocene (1h), ferrocenecar-
boxylic acid (7), ferrocenylmethanol (2a), dimethyl-
amino-methylferrocene (11), ferrocenylmethyltrimethyl-
ammonium iodide (12) are commercially available and
have been used without further purification. 2-Tris(n-
butyltin)ferrocenecarboxaldehyde (1b), 2-(diphenyl-
phoshino)-ferrocenecarboxaldehyde (1c), 1,1%-ferrocene-
dicarboxaldehyde (1d), 1-phenyl-1-ferrocenylethanol
(2f), ferrocenyl-1,2-ethane-diol (2h), 2-ferrocenyl-1,3-
dioxane (4), 2-ferrocenyl-1,3-dioxolane (5), 4-(meth-
oxymethyl)-2-ferrocenyl)-1,3-dioxane (6), ferrocenylni-
trile (10) have been synthesised following well-known
procedures outlined in Refs. [19–24]. (Phenyl)ferro-
Bond angles
B(1)ꢀP(1)ꢀC(2)
B(1)ꢀP(1)ꢀC(111)
C(2)ꢀP(1)ꢀC(111)
P(1)ꢀC(111)ꢀC(112) 119.7(2)
C(2)ꢀC(1)ꢀC(11)
P(1)ꢀC(2)ꢀC(1)
120.38(14) B(1)ꢀP(1)ꢀC(121)
109.61(14) C(2)ꢀP(1)ꢀC(121)
104.09(12) C(111)ꢀP(1)ꢀC(121) 105.63(12)
P(1)ꢀC(111)ꢀC(116) 122.2(2)
127.0(3)
127.7(2)
111.83(14)
104.11(12)
C(5)ꢀC(1)ꢀC(11)
P(1)ꢀC(2)ꢀC(3)
P(1)ꢀC(121)ꢀC(126) 119.4(2)
126.2(3)
125.0(2)
P(1)ꢀC(121)ꢀC(122) 122.2(2)
Compound 2f
Bond length
C(1)ꢀC(2)
C(1)ꢀC(5)
C(2)ꢀC(3)
C(3)ꢀC(4)
C(4)ꢀC(5)
O(1)ꢀC(11)
C(11)ꢀC(12)
O(1)ꢀH(1)
1.431(3)
1.431(3)
1.423(3)
1.429(4)
1.416(3)
1.438(2)
1.527(3)
0.84(3)
C(6)ꢀC(7)
C(6)ꢀC(10)
C(7)ꢀC(8)
1.411(4)
1.424(5)
1.370(4)
1.394(4)
1.407(4)
1.501(3)
1.515(3)
2.94(3)
C(8)ꢀC(9)
cenylmethanol
(2b),
(4-methoxyphenyl)ferrocenyl-
C(9)ꢀC(10)
C(1)ꢀC(11)
C(11)ꢀC(111)
H(1)ꢀFe(1)
methanol (2c), (n-butyl)ferrocenylmethanol (2e) and (t-
butyl)ferrocenylmethanol (2d) have been synthesised
with an almost quantitative yield by the action of an
alkyl or aryllithium on ferrocenecarboxaldehyde. Their
physical data are identical with the published data or
given below [25–27]. Methylferrocenecarboxylate (8)
and N,N-dimethylferrocenecarboxamide (9) have been,
respectively, synthesised by the action of FcC(O)Cl on
methanol (Yield: 98%) or Me2NH2Cl (Yield: 95%). The
NMR data are identical with those from the literature
[28,29]. Methylferrocene (13), benzylferrocene (20), i-
propylferrocene (25), 4-methoxyphenylmethylferrocene
(21), 2-ferrocenylethanol (26), 1-ferrocenylstyrene (24)
have been identified by comparing with the published
data [30–33].
Bond angles
O(1)ꢀC(11)ꢀC(1)
C(2)ꢀC(1)ꢀC(11)
C(5)ꢀC(1)ꢀC(11)
C(1)ꢀC(11)ꢀC(111)
C(11)ꢀC(111)ꢀC(112) 119.43(18) C(11)ꢀC(111)ꢀC(116) 122.67(19)
C(11)ꢀO(1)ꢀH(1) 107.3(22) Fe(1)ꢀH(1)ꢀO(1) 123.2(26)
109.95(15) O(1)ꢀC(11)ꢀC(12)
124.69(18) C(1)ꢀC(11)ꢀC(12)
128.09(19) O(1)ꢀC(11)ꢀC(111)
108.4(2)
111.82(18)
106.88(16)
109.4(2)
C(12)ꢀC(11)ꢀC(111) 110.19(16)
alkylferrocenes. This new method is a mild and efficient
alternative to the existing methods [6,7,18]. Further, the
procedure has been extended successfully to new sub-
strates (carboxylic acids, esters, ethers, acetals, etc.). On
the contrary, equivalent nitrogen containing molecules
(nitriles, amines, ammoniums, etc.) do not react with
borane. Only, amides have been partially reduced (up
to 18%) to methylferrocene.
3.1. (S)-2-(Tributylstannyl)methylferrocene (14)
1H-NMR (CDCl3): l 4.22 (m, 1H, subst Cp), 4.20 (t,
J=2.2 Hz, 1H, subst Cp), 4.04 (s, 5H, Cp), 3.89 (dd,
1H, J=2.2 Hz and J=0.8 Hz, subst Cp), 1.96 (s, 3H,

L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
369
Scheme 2.
CH3), 1.65–0.75 (m, 29H, n-Bu). 13C-NMR (CDCl3): l
89.5 (JSnꢀC=40.5 Hz, quat Cp), 73.9 (JSnꢀC=44 Hz,
subst Cp), 71.5 (JSnꢀC=32.3 Hz, subst Cp), 70.3
(JSnꢀC=140 Hz, quat Cp), 69.5 (JSnꢀC=36.6 Hz, subst
Cp), 68.5 (Cp), 29.3 (JSnꢀC=19.0 Hz, CH2), 27.5
(JSnꢀC=59.4 Hz, CH2), 16.4 (CH3), 13.7 (CH3 (n-Bu)),
[h]D −23.2° (c 0.5, CHCl3). MS; m/e (DCI, NH3): 416
([M+18], 100%).
3.3. (n-Butyl)ferrocenylmethanol (2e)
1H-NMR (CDCl3): l 4.30 (ddd, J=7.2 Hz, 5.3 Hz
and J=3.2 Hz, 1H, subst Cp), 4.23 (dd, J=3.3 Hz and
J=1.5 Hz, 1H, subst Cp), 4.19 (s, 5H, Cp), 4.16 (m,
3H, subst Cp+CHOH), 1.93 (d, J=3.2 Hz, 1H, OH),
1.7–1.5 (m, 2H, CH2), 1.5–1.25 (m, 4H, CH2), 0.88 (t,
J=3.2 Hz, 3H, CH3). 13C-NMR (CDCl3): l 93.9 (quat
Cp), 69.2 (subst Cp), 67.9 (Cp), 67.5 (subst Cp), 67.3
(subst Cp), 65.1 (subst Cp), 67.5 (subst Cp), 37.5 (CH2),
27.9 (CH2), 22.3 (CH2), 13.9 (CH3). MS; m/e (DCI,
NH3): 255 ([M−17], 100%).
10.3 (J119SnꢀC=345.5 Hz and J117
=330.3 Hz, CH2).
[a]D +29.0° (c 0.5, CHCl3). MS;SnmꢀC/e (DCI, NH3): 490
(M+1, 13%), 433(M−n-Bu, 29%), 291 (SnBu3, 100%).
3.2. (S)-2-(Diphenyl(trihydridoboryl)phosphino)-
methylferrocene (15)
1H-NMR (CDCl3): l 7.7–7.6 (m, 2H, Ph), 7.5–7.4
(m, 8H, Ph), 4.43 (m, 1H, subst Cp), 4.29 (t, J=2.4 Hz,
1H, subst Cp), 4.24 (s, 5H, Cp), 3.77 (br dd, 1H, J=2.4
Hz and J=1.5 Hz, subst Cp), 2.04 (s, 3H, CH3).13C-
NMR (CDCl3): l 133.5 (JPꢀC=9.4 Hz, Ph),133.0
(JPꢀC=9.4 Hz, Ph), 131.4 (JPꢀC=57.8 Hz, quat Ph),
131.3 (JPꢀC=2.3 Hz, Ph), 131.2 (JPꢀC=2.2 Hz, Ph),
131.1 (JPꢀC=59.4 Hz, quat Ph), 128.9 (JPꢀC=10.0 Hz,
Ph), 128.7 (JPꢀC=10.0 Hz, Ph), 89.3 (JPꢀC=13.5 Hz,
3.4. Pentylferrocene (23)
1H-NMR (CDCl3): l 4.08 (s, 5H, Cp), 4.03 (m, 4H,
subst Cp), 2.30 (t, J=7.3 Hz, 2H, CH2), 1.55–1.4 (m,
2H, CH2), 1.35–1.25 (m, 4H, CH2), 0.88 (t, J=6.7 Hz,
3H, CH3). 13C-NMR (CDCl3): l 89.5 (quat Cp), 68.4
(Cp), 68.0 (subst Cp), 66.9 (subst Cp), 31.8 (CH2), 30.8
(CH2), 29.5 (CH2), 22.5 (CH2), 14.1 (CH3). MS; m/e
(DCI, NH3): 257 ([M+1], 100%).
quat Cp), 74.6 (JPꢀC=7.6 Hz, subst Cp), 73.4 (JPꢀC
=
6.3 Hz, subst Cp), 70.8 (Cp), 69.6 (JPꢀC=6.8 Hz, subst
Cp), 69.0 (JPꢀC=66.0 Hz, quat Cp), 15.2 (CH3). 31P-
NMR (CDCl3): l 18.8. 11B-NMR (CDCl3): l −36.5.

370
L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
Table 5
Crystal data
20
15
2f
Formula
C17H16Fe
276.15
Box (orange)
0.76×0.62×0.40
Orthorhombic
Pbca
C
398.08
Box (orange)
0.50×0.34×0.22
Orthorhombic
P212121
22H24BFeP
C18H18FeO
306.19
Flattened (yellow)
0.50×0.45×0.15
Orthorhombic
Pna21
Formula weight
Shape (color)
Size (mm)
Crystal system
Space group
Unit cell dimensions
,
a (A)
7.5357(5)
10.7831(7)
32.079(3)
2606.7(3)
8
1.407
1154
11.341
4.6B2qB52.0
14 314
8.8597(8)
14.885(2)
15.614(2)
2059.1(4)
4
1.284
833
8.132
5.9B2qB61.1
30 989
19.267(4)
5.882(1)
12.127(2)
1374.3(4)
4
1.480
641
10.891
5.4B2qB52.1
8489
,
b (A)
,
c (A)
V (A )
3
,
Z
zcalc (g cm−3
F(000)
)
v (Mo–Ka) (cm−1
2q Range (°)
)
Reflections collected
Unique reflections
Merging factor (Rint
2512
0.0384
6005
0.068
2645
0.0467
)
Reflections observed (I\2|(I))
R indices
2163
0.0330
3029
0.0283
2333
0.0301
Rw
0.0414
0.0311
0.0310
Weighting scheme
Coefficient Ar
(Z/|)max
Chebyshev
1.70, 0.37, 1.31
0.045
Chebyshev
1.24, −0.49, 0.76
0.056
Chebyshev
2.28, 0.49, 2.06
0.02
Dzmin/Dzmax
−0.46/0.35
−0.38/0.34
0.00(2)
1.052
−0.66/0.74
0.00(1)
0.991
Flack’s parameter
Goodness-of-fit on F2
Variable parameters
0.976
164
237
187
3.5. (2,2-Dimethylpropyl)ferrocene (22)
squares refinement of 8000 reflections. Only statistical
fluctuations were observed in the intensity monitors
over the course of the data collections.
1H-NMR (CDCl3): l 4.07 (s, 5H, Cp), 4.03 (m, 4H,
subst Cp), 2.24 (s, 2H, CH2), 0.80 (s, 9H, CH3). 13C-
NMR (CDCl3): l 85.6 (quat Cp), 70.2 (subst Cp), 68.5
(Cp), 67.2 (subst Cp), 45.0(CH2), 31.7 (C(CH3)3), 29.3
(CH3). MS; m/e (DCI, NH3) m/e: 257 ([M+1],
100%).
The three structures were solved by direct methods
(
SIR97) [34] and refined by least-squares procedures on
F. All H atoms were located on difference Fourier
syntheses. Those attached to carbon were introduced
,
for calculations in idealised positions (d(CH)=0.96 A)
and their atomic coordinates were recalculated after
each cycle with an isotropic thermal parameter 20%
higher than those of the carbon to which they are
attached. The atomic and isotropic thermal parameters
for the H atom attached to oxygen in 2f were refined.
The absolute configuration for 15 and the absolute
structure for 2f were determined by refining Flack’s
enantiopole parameter [10]. Least-squares refinements
were carried out by minimising the function ꢀw(ꢁFoꢁ−
ꢁFcꢁ), where Fo and Fc are the observed and calculated
structure factors, respectively. The weighting scheme
used in the last refinement cycles was w=w%[1−{DF/
3.6. 2-Ferrocenyl-1,3-dioxane (4)
1H-NMR (CDCl3): l 5.35 (s, 1H, OCHO), 4.30 (t,
J=1.9 Hz, 2H, subst Cp), 4.20(m, 2H, CH2O), 4.17
(s, 5H, Cp), 4.11 (t, J=1.9 Hz, 2H, subst Cp), 3.90
(td, J=2.5 Hz and 12.3 Hz, 2H, CH2O), 2.13 (m, 1H,
CH2), 1.37 (m, 1H, CH2). 13C-NMR (CDCl3): l 100.5
(OCHO), 86.1 (quat Cp), 68.8 (Cp), 67.9 (subst Cp),
67.3 (subst Cp), 66.4 (OCH2), 25.8(CH2). MS; m/e
(DCI, NH3): 273 ([M+1], 100%).
6|(Fo)}2]2 where w%=1/ꢀ1ArTr(x) with three coeffi-
n
3.7. X-ray crystal structure determination
cients Ar for the Chebyshev polynomial ArTr(x) where
x was Fc/Fc (max) [35]. Models reached convergence
with R=ꢀ(ꢁ ꢁFoꢁ−ꢁFcꢁ ꢁ)/ꢀ(ꢁFoꢁ) and Rw=[ꢀw(ꢁFoꢁ−
ꢁFcꢁ)2/ꢀw(Fo)2]1/2, having values listed in Table 5.
For all the three compounds 20, 15 and 2f, the data
were collected on a STOE IPDS diffractometer. The
final unit cell parameters were obtained by the least-

L. Routaboul et al. / Journal of Organometallic Chemistry 637–639 (2001) 364–371
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