Conversion of (2-methyl-1-azabuta-1,3-diene)tricarbonyliron(0) complexes into tertiary (enamine)tricarbonyliron(0) complexes

Article abstract of DOI:10.1016/S0022-328X(00)00511-8

Treatment of (2-methyl-1-azabuta-1,3-diene)tricarbonyliron(0) complexes with lithium diethylamide followed by a methyl iodide, benzyl bromide or allyl bromide quench leads to the formation of tertiary (enamine)tricarbonyliron(0) complexes in good yield. The crystal structures of two complexes, (2-(N-methyl-N-(4-methoxyphenyl)amino)-4-phenylbuta-1,3-diene)tricarbonyliron(0) (19) and (2-(N-allyl-N-isopropylamino)-4-phenylbuta-1,3-diene)tricarbonyliron(0) (24) are reported.

Full text of DOI:10.1016/S0022-328X(00)00511-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 613 (2000) 200–207
Conversion of (2-methyl-1-azabuta-1,3-diene)tricarbonyliron(0)
complexes into tertiary (enamine)tricarbonyliron(0) complexes
Philip M. Branton, Timothy N. Danks *, Mark E. Howells, David C. Povey,
Gallienus W. Smith
Department of Chemistry, Uni6ersity of Surrey, Guildford, Surrey GU2 5XH, UK
Received 26 June 2000; accepted 22 July 2000
Abstract
Treatment of (2-methyl-1-azabuta-1,3-diene)tricarbonyliron(0) complexes with lithium diethylamide followed by a methyl
iodide, benzyl bromide or allyl bromide quench leads to the formation of tertiary (enamine)tricarbonyliron(0) complexes in good
yield.
The
crystal
structures
of
two
complexes,
(2-(N-methyl-N-(4-methoxyphenyl)amino)-4-phenylbuta-1,3-di-
ene)tricarbonyliron(0) (19) and (2-(N-allyl-N-isopropylamino)-4-phenylbuta-1,3-diene)tricarbonyliron(0) (24) are reported.
© 2000 Elsevier Science B.V. All rights reserved.
Keywords: 1-Azabuta-,3-diene; Iron; Enamine tricarbonyliron
1. Introduction
In this paper, we report that this rearrangement
reaction can be used for the synthesis of tertiary enam-
ine complexes. Although tertiary enamine complexes in
the cyclohexa-1,3-diene series have been previously syn-
thesised [4] our deprotonation strategy represents the
first synthesis of acyclic tertiary (enamine)-
tricarbonyliron(0) complexes (Table 1).
During our investigations of the reaction between
(2-methyl-1-azabuta-1,3-diene)tricarbonyliron(0) com-
plexes and lithiated amines we demonstrated that for
complexes 1–4, which contain a methyl group at C-2,
the reaction leads to deprotonation, followed by rear-
rangement of the intermediate anion and consequently
yields
secondary
(2-amino
homo-1,3-di-
ene)tricarbonyliron(0) complexes 5–8 in good yield
[1,2] (Scheme 1).
We have also illustrated that when the substituent at
C-2 of the coordinated 1-azabuta-1,3-diene is an ethyl
group complexes 9–10 rearrange in a stereospecific
manner to exclusively yield the endo enamine complexes
11–12 [3]. The stereochemistry of complexes (11) and
1
(12) was assigned by a combination of H-NMR and
Scheme 1.
nOe difference spectroscopy (Scheme 2). In this work,
nOe difference spectroscopy was used to demonstrate
that the stereochemical outcome of these rearrange-
ments was probably due to a conformationally con-
strained ethyl group at C-2 of the coordinated
1-azabuta-1,3-diene complexes 9 and 10 [3].
* Corresponding author. Tel.: +44-1483-876829; fax: +44-1483-
876851.
E-mail address: t.danks@surrey.ac.uk (T.N. Danks).
Scheme 2.
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00511-8

P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
201
Table 1
Synthesis of tertiary (enamine)tricarbonyliron(0) complexes from (1-azabuta-1,3-diene)tricarbonyliron(0) complexes
Entry
1-Azabuta-1,3-diene complex
Alkylating agent
Tertiary enamine complex
Yield (%)
1
2
3
4
5
6
7
8
1
1
1
2
2
2
3
3
3
4
4
4
CH3I
13
14
15
16
17
18
19
20
21
22
23
24
82
46
68
58
76
82
46
54
66
64
48
72
C6H5CH2Br
H2CꢀCHCH2Br
CH3I
C6H5CH2Br
H2CꢀCHCH2Br
CH3I
C6H5CH2Br
H2CꢀCHCH2Br
CH3I
C6H5CH2Br
H2CꢀCHCH2Br
9
10
11
12
2. Results and discussion
Complex 19 has a monoclinic unit cell containing
eight molecular units. The iron atom is bound to three
carbonyl ligands and is approximately equidistant from
each of the carbon atoms comprising the buta-1,3-diene
fragment. The buta-1,3-diene fragment itself shows a
dihedral angle of 7.66° between C(4) and C(7) and may
be considered as approximately planar as in (buta-1,3-
diene)tricarbonyliron(0) [6]. The minor deviation from
planarity is attributed to the substituents at C(7) and
C(5). The dihedral angle C(6)ꢁC(7)ꢁC(11)ꢁC(10) (6.33°)
indicates that the phenyl substituent at C(7) is essen-
tially co-planar to the buta-1,3-diene fragment. In the
case of the substituents at nitrogen the methyl is slightly
below the plane of the buta-1,3-diene fragment and the
4-methoxy phenyl group shows a pronounced twist
along the N(1)ꢁC(21) bond. Selected bond lengths,
bond angles and dihedral angles for this complex are
shown in Tables 3–5.
Initially the reaction between lithium diethylamide
and complex 1 followed by a methyl iodide quench was
studied. A solution of complex 1 in tetrahydrofuran
was added to a solution of lithium diethylamide in
THF at 0°C and the reaction was stirred for 3 h under
an atmosphere of nitrogen. An excess of methyl iodide
was added and the reaction was stirred for a further 0.5
h whilst warming up to room temperature (r.t.). Filtra-
tion of the reaction mixture following chromatography
led to the isolation of a yellow oil, which crystallised on
standing to yield yellow crystals identified from their
spectroscopic and analytical data as complex 13.
The applicability of this reaction was also studied
using benzyl bromide and allyl bromide as quenchers
for the rearranged intermediates derived from com-
plexes 1–4. Incorporation of an allyl group at nitrogen
has allowed a useful reactive functionality to be intro-
duced onto these enamine complexes, and hence, ex-
pand their potential application in organic synthesis
(Scheme 3).
All attempts to generate the tertiary enamine com-
plexes 13–24 by treatment of secondary enamine com-
plexes 5–8 with alkylating agents in the presence of a
mild base failed and only the starting complexes 1–4
were obtained. When lithiated secondary enamine com-
plexes, generated by the reaction of complexes 5–8 with
butyl-lithium, were quenched with alkylating agents the
reactions lead to the formation of tertiary enamine
complexes in acceptable yields. It appears therefore that
these tertiary enamine complexes are only accessible by
alkylation of the lithiated enamine complexes by either
quenching the rearrangement of 1-azabuta-1,3-diene
complexes, or the anion generated by reaction of sec-
ondary enamine complexes with butyl-lithium (Scheme
4).
For complex 24 the unit cell is again monoclinic and
in this case contains four molecular units. A similar
arrangement of the buta-1,3-diene and carbonyl ligands
to those described for complex 19 exists. The dihedral
angle C(4)ꢁC(5)ꢁC(6)ꢁC(7) in this case is 13.48°. The
C(8) of the allyl fragment is below the buta-1,3-diene
Scheme 3.
Crystal structures of complexes 19 (Fig. 1) and 24
(Fig. 2) were obtained. Relevant data is summarised in
Table 2.
Scheme 4.

202
P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
Fig. 1. Crystal structure of (2-(N-methyl-N-(4-methoxyphenyl)amino)-4-phenylbuta-1,3-diene)tricarbonyliron(0) (19).
Fig. 2. Crystal structure of (2-(N-allyl-N-isopropylamino)-4-phenylbuta-1,3-diene)tricarbonyliron(0) (24).
whilst C(9) and C(10) of the alkene fragment is above.
The methine carbon of the isopropyl fragment is ap-
proximately in the plane of the buta-1,3-diene while the
methyl groups are orientated above and below the
plane of the buta-1,3-diene fragment. The phenyl group
at C(7) shows similar behaviour to that observed for
complex 19. Selected bond lengths, bond angles and
dihedral angles for complex 24 are shown in Tables
6–8.
In both complexes 19 and 24 one of the hydrogens at
C(4) [H(42)] is situated over the tricarbonyliron(0) moi-
ety and explains the high chemical shift observed for
1
these atoms in the H-NMR spectrum [5].
In both complexes the FeꢁC and CꢁO bond lengths
associated with the carbonyl groups are approximately
equal and characteristic of those expected for a (buta-
1,3-diene)tricarbonyliron(0) complex [6]. Also, for com-
plexes 19 and 24 the nitrogen atoms at C(2) are

P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
203
Table 4
approximately planar and the C(2)ꢁN(1) bond lengths
Selected bond angles (°) for complex 19
,
are 1.367 and 1.373 A, respectively. This is consistent
with the presence of a planar sp2 nitrogen bound to an
sp2 carbon [7] and suggests a degree of delocalisation
into the buta-1,3-diene fragment.
Atoms
Angle
Atoms
Angle
C(1)ꢁFe(1)ꢁC(2)
C(1)ꢁFe(1)ꢁC(3)
C(2)ꢁFe(1)ꢁC(3)
C(4)ꢁFe(1)ꢁC(5)
C(5)ꢁFe(1)ꢁC(6)
C(6)ꢁFe(1)ꢁC(7)
C(5)ꢁFe(1)ꢁC(7)
C(4)ꢁFe(1)ꢁC(6)
C(7)ꢁFe(1)ꢁC(4)
Fe(1)ꢁC(1)ꢁO(1)
Fe(1)ꢁC(2)ꢁO(2)
Fe(1)ꢁC(3)ꢁO(3)
100.3(2)
101.1(2)
91.7(2)
39.3(1)
39.25(9)
39.6(1)
69.6(1)
70.3(1)
79.8(1)
178.6(3)
179.4(3)
177.8(4)
C(6)ꢁC(5)ꢁC(4)
C(7)ꢁC(6)ꢁC(5)
C(5)ꢁC(4)ꢁH(41)
C(5)ꢁC(4)ꢁH(42)
114.2(3)
118.4(3)
118.9(17)
117.5(22)
H(41)ꢁC(4)ꢁH(42) 112.9(26)
Table 2
C(5)ꢁC(6)ꢁH(6)
C(7)ꢁC(6)ꢁH(6)
C(6)ꢁC(7)ꢁH(7)
C(6)ꢁC(7)ꢁC(11)
C(4)ꢁC(5)ꢁN(1)
C(6)ꢁC(5)ꢁN(1)
C(8)ꢁN(1)ꢁC(21)
C(5)ꢁN(1)ꢁC(21)
C(5)ꢁN(1)ꢁC(8)
119.7(18)
171.7(17)
119.6(16)
122.9(3)
123.0(3)
122.1(3)
118.0(3)
120.8(3)
120.5(3)
Crystallographic data for complexes 19 and 24
Complex 19
Complex 24
Empirical formula
Formula weight
Temperature (K)
C21H19NFeO4
405.23
293
C19H21NFeO3
367.23
293
Fe(1)ꢁC(4)ꢁH(42) 119.5(21)
Fe(1)ꢁC(4)ꢁH(41) 109.4(15)
,
Wavelength (A)
0.71069
Monoclinic
C2/c
23.005
7.909
21.285
90
0.71073
Monoclinic
P21/n
17.132
8.470
12.699
90
Crystal system
Space group
,
a (A)
Table 5
,
b (A)
Selected dihedral angles for complex 19
,
c (A)
h (°)
i (°)
k (°)
Bonds
Angle Bonds
Angle
15.64
90
90
97.93
3835.6
8
1.396
8.0
93.86
1838.5
4
1.327
8.3
C(4)ꢁC(5)ꢁC(6)ꢁC(7)
C(4)ꢁC(5)ꢁN(1)ꢁC(8)
C(5)ꢁN(1)ꢁC(21)ꢁC(26)
7.66 C(6)ꢁC(5)ꢁN(1)ꢁC(8)
3
,
Volume (A )
Z
155.27 C(6)ꢁC(7)ꢁC(11)ꢁC(10)
6.33
65.26 C(6)ꢁC(7)ꢁC(11)ꢁC(12) 172.96
Dcalc (g cm−3
Absorption
)
C(5)ꢁN(1)ꢁC(21)ꢁC(22) 116.48
coefficient (cm−1
)
F(000)
1536
0.4×0.4×0.15
05h528, 05k59, 05h521, 05k510,
768
0.3×0.3×0.3
Table 6
Crystal size (mm3)
Index ranges
,
Selected interatomic distances (A) for complex 24
−265l526
Reflections collected 4140
−155l515
3999
Bond
Length
Bond
Length
Independent
reflections
I\s3(I)
2902
2850
Fe(1)ꢁC(1)
Fe(1)ꢁC(2)
Fe(1)ꢁC(3)
Fe(1)ꢁC(4)
Fe(1)ꢁC(5)
Fe(1)ꢁC(6)
Fe(1)ꢁC(7)
C(4)ꢁC(5)
C(5)ꢁC(6)
1.782(3)
1.795(4)
1.778(4)
2.102(3)
2.214(3)
2.064(3)
2.120(3)
1.441(4)
1.424(4)
C(6)ꢁC(7)
C(7)ꢁC(11)
C(4)ꢁH(41)
C(4)ꢁH(42)
C(6)ꢁH(6)
C(7)ꢁH(7)
N(1)ꢁC(8)
N(1)ꢁC(17)
N(1)ꢁC(5)
1.422(4)
1.476(4)
1.00(3)
0.90(3)
0.90(2)
0.86(3)
1.454(4)
1.484(4)
1.367(3)
Refinement method a FMLSSF
Data/restraints/param
eters
FMLSSF
1.095
Goodness-of-fit on
1.059
F2
R(F)
0.0339
0.0394
0.0337
0.0393
wR(F2)
a FMLSSF=Full-matrix least-squares structure factors.
Table 7
Selected bond angles for complex 24
Atoms
Angle
Atoms
Angle
Table 3
Selected interatomic distances (A) for complex 19
,
C(1)ꢁFe(1)ꢁC(2)
C(1)ꢁFe(1)ꢁC(3)
C(2)ꢁFe(1)ꢁC(3)
C(4)ꢁFe(1)ꢁC(5)
C(5)ꢁFe(1)ꢁC(6)
C(6)ꢁFe(1)ꢁC(7)
C(4)ꢁFe(1)ꢁC(6)
C(7)ꢁFe(1)ꢁC(4)
Fe(1)ꢁC(1)ꢁO(1)
Fe(1)ꢁC(2)ꢁO(2)
Fe(1)ꢁC(3)ꢁO(3)
96.7(2)
90.8(1)
101.5(2)
38.9(1)
38.7(1)
39.7(1)
70.3(1)
80.1(1)
177.3(3)
178.1(3)
177.7(4)
C(4)ꢁC(5)ꢁC(6)
C(5)ꢁC(6)ꢁC(7)
C(5)ꢁC(4)ꢁH(41)
C(5)ꢁC(4)ꢁH(42)
H(41)ꢁC(4)ꢁH(42)
C(5)ꢁC(6)ꢁH(6)
C(7)ꢁC(6)ꢁH(6)
C(6)ꢁC(7)ꢁH(7)
C(4)ꢁC(5)ꢁN(1)
C(6)ꢁC(5)ꢁN(1)
C(8)ꢁN(1)ꢁC(17)
C(5)ꢁN(1)ꢁC(17)
C(5)ꢁN(1)ꢁC(8)
113.6(3)
119.3(3)
116.9(17)
119.5(21)
111.9(25)
119.5(15)
120.9(15)
112.5(17)
123.7(3)
122.3(2)
117.7(2)
122.0(2)
119.5(2)
Bond
Length
Bond
Length
Fe(1)ꢁC(1)
Fe(1)ꢁC(2)
Fe(1)ꢁC(3)
Fe(1)ꢁC(4)
Fe(1)ꢁC(5)
Fe(1)ꢁC(6)
Fe(1)ꢁC(7)
C(5)ꢁC(4)
C(6)ꢁC(5)
1.79(4)
C(7)ꢁC(6)
C(7)ꢁC(11)
C(4)ꢁH(41)
C(4)ꢁH(42)
C(6)ꢁH(6)
C(7)ꢁH(7)
C(5)ꢁN(1)
N(1)ꢁC(8)
N(1)ꢁC(21)
1.423(4)
1.489(4)
1.14(3)
0.87(3)
0.97(3)
1.02(3)
1.373(4)
1.455(4)
1.441(4)
1.797(3)
1.787(4)
2.104(3)
2.170(3)
2.077(3)
2.119(3)
1.437(5)
1.429(4)
Fe(1)ꢁC(4)ꢁH(41) 120.9(16)
Fe(1)ꢁC(4)ꢁH(42) 108.2(20)

204
P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
Table 8
difference map R fell to 0.087. Anisotropic full-matrix
refinement, initially with the iron atom alone and
then with the remaining non-hydrogen atoms con-
verged at R=3.39, Rw=3.94 and S=1.059.
Selected dihedral angles for complex 24
Atoms
Angle Atoms
Angle
C(4)ꢁC(5)ꢁC(6)ꢁC(7)
C(4)ꢁC(5)ꢁN(1)ꢁ(C8)
C(5)ꢁN(1)ꢁC(8)ꢁC(9)
13.48 C(5)ꢁN(1)ꢁC(17)ꢁC(19) 99.91
154.48 C(6)ꢁC(5)ꢁN(1)ꢁC(17) 171.94
82.78 C(6)ꢁC(7)ꢁC(11)ꢁC(12) 20.59
For complex 24 the coordinates of the iron atom
were derived from a Patterson synthesis but a subse-
quent Fo map only revealed 19 further atoms of the
ligand. Subsequent structure factor/Fourier cycles
eventually produced the complete molecule. With the
inclusion of hydrogen atoms in fixed calculated posi-
C(5)ꢁN(1)ꢁC(17)ꢁC(18) 134.47 C(6)ꢁC(7)ꢁC(11)-C(16) 156.73
,
tions (dH=1.0 A) R fell to 0.096. Anisotropic full-
matrix refinement, initially with the iron atom alone
and then with the remaining non-hydrogen atoms
converged at R=3.37, Rw=3.93 and S=1.095
3. Experimental
All reactions carried out under an atmosphere of
dry nitrogen were performed using standard vacuum
and Schlenk line techniques [8]. Complexes 1–4 were
synthesised in accordance with literature procedures
[1,2]. Diethyl ether was dried over lithium alumini-
umhydride and was distilled, toluene was dried over
sodium metal and was distilled and tetrahydrofuran
was dried over potassium benzophenone ketyl and
was distilled. Diethylamine was redistilled and butyl-
lithium was used as a 1.6 M solution in hexanes.
Melting points were recorded on a Kofler hot-stage
micro-melting point apparatus and are uncorrected.
1H- and 13C-NMR spectra were recorded on a Bruker
AC 300 instrument at 300 and 75.4 MHz, respec-
tively. All chemical shifts are quoted in parts per mil-
lion relative to a tetramethylsilane standard. Flash
chromatography was performed on Merck (40–63
mm) silica. IR spectra were recorded on a Perkin–
Elmer System 2000 FT-IR spectrometer. Filtrations
through alumina were performed using deactivated
Brockmann (grade 4) alumina. Elemental analyses
were performed on a Leeman Laboratories CE 477
instrument.
4.2. (2-(N-Methyl-N-phenylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (13)
Diethylamine (0.01 g, 1.38 mmol) was added to
tetrahydrofuran (5 ml) and the resulting solution was
cooled to 0°C. Butyl-lithium (1.6 M, 0.88 ml, 1.40
mmol) was added and the solution was stirred at 0°C
for 0.25 h under an atmosphere of nitrogen. A solu-
tion of complex 1 (0.10 g, 0.28 mmol) in tetrahydro-
furan (5 ml) was added and the dark solution
produced was stirred at 0°C for 3 h under an atmo-
sphere of nitrogen. Iodomethane (0.20 g, 1.38 mmol)
was added and the reaction mixture was allowed to
warm up to r.t. The dark mixture produced was
filtered through a plug of alumina to remove the
solid residue and the solvent was removed under re-
duced pressure to yield a yellow gum. This gum was
chromatographed on silica using 1:10 diethyl ether–
hexane as the eluent to yield a yellow oil which crys-
tallised on standing to yield yellow crystals (0.085 g,
82%). M.p. 101–102°C. Found: C, 64.02; H, 4.42; N,
3.64. C20H17FeNO3 requires: C, 63.99; H, 4.57; N,
3.73%. IR (C4Cl6): wmax 2038vs (CꢂO) and 1973vs br
cm−1 (CꢂO). 1H-NMR (300 MHz; CDCl3): l 0.67
(1H, d, Ja–3 5.0 Hz, CꢀCHb), 1.86 (1H, d, J 8.2 Hz,
PhCHꢀCH), 2.09 (1H, dd, Ja–3 1.8 Hz and Ja–b 5.0
Hz, CꢀCHa), 3.28 (3H, s, NCH3), 5.19 (1H, d, J 7.7
Hz, PhCHꢀCH) and 7.10–7.41 (10H, m, 2×arylꢁH).
13C-NMR (75 MHz; CDCl3): l 35.30 (CꢀCH2), 38.70
(NCH3), 55.15 (C4), 63.05 (C3), 124.93, 125.06,
125.77, 126.10, 127.20, 128.41, 129.45, 141.84 and
146.87 (2×arylꢁH and C2).
4. Crystal structures
4.1. Data collection and processing
Crystal structures were determined using an Enraf–
Nonius
CAD4
diffractometer
using
graphite
,
monochromated Mo–Ka radiation (u=0.71073 A),
Structures were solved and refined with SHELEX-87
using standard procedures [9].
4.3. (N-Benzyl-N-phenylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (14)
For complex 19 the coordinates of the iron atom
were derived from a Patterson synthesis and a subse-
quent Fo map revealed all but four atoms of the lig-
and and a subsequent structure factor/Fourier cycle
produced the complete molecule. With the inclusion
of hydrogen atoms in positions determined from a
Yellow crystals. (0.060 g, 46%). M.p. 119–121°C.
Found: C, 69.14; H, 4.74; N, 2.86. C26H21NFeO3
requires: C, 69.17; H, 4.96; N, 3.10%. IR (C4Cl6):

P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
205
wmax 2038vs (CꢂO), 1973vs (CꢂO) and 1961vs cm−1
.
(300 MHz; CDCl3): l 0.48 (1H, d, J 5.4 Hz, CꢀCHb),
1.79 (1H, d, J 8.0 Hz, PhCHꢀCH), 2.21 (1H, dd, Ja–3
1.9 Hz and Ja–b 5.3 Hz, CꢀCHa), 4.33 (2H, d, J 15.9
Hz, 2×PhCHHN), 4.51 (2H, d, J 15.9 Hz, 2×
PhCHHN), 5.19 (1H, d, J 7.4 Hz, PhCHꢀCH) and
7.05–7.38 (15H, m, 3×arylꢁH). 13C-NMR (75 MHz;
CDCl3): l 32.80 (CꢀCH2), 55.31 (C4), 55.38 (2×
PhCH2), 63.53 (C3), 125.69, 126.03, 127.48, 127.53,
128.39, 128.72 and 137.36 (3×Ph and C2).
(CꢂO)1H-NMR (300 MHz; CDCl3): l 0.72 (1H, d, J 5.0
Hz, C=CHa), 1.80 (1H, d, J 8.1 Hz, PhCH=CH),
2.14 (1H, dd, Ja–3 1.9 Hz and Ja–b 5.1 Hz, CꢀCHa),
4.73 (1H, d, J 16.6 Hz, PhCHHN), 5.03 (1H, d, J 16.6
Hz, PhCHHN), 5.14 (1H, d, J 7.6 Hz, PhCHꢀCH) and
7.01–7.40 (15H, m, 3×arylꢁH). 13C-NMR (75 MHz;
CDCl3): l 37.17 (CꢀCH2), 55.15 (C4), 55.90 (CH2Ph),
64.29 (C3), 125.30, 125.77, 125.83, 126.05, 126.64,
127.35, 128.39, 128.84, 129.69, 138.15 and 141.71 (3×
Ph and C2).
4.7. (2-(N-(Allyl)-N-benzylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (18)
4.4. (2-(N-Allyl-N-phenylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (15)
Yellow oil (0.083 g, 82%). B.p.\120°C (dec.).
Found: C, 66.40; H, 4.99; N, 3.25% C23H21FeNO3
requires: C, 66.49; H, 5.10; N, 3.37%. IR (thin film):
wmax 2034s (CꢂO), 1966s (CꢂO) and 1959s cm−1 (CꢂO).
1H-NMR (300 MHz; CDCl3): l 0.48 (1H, d, J 5.3 Hz,
CꢀCHb), 1.80 (1H, d, J 8.0 Hz, PhCHꢀCH), 2.22 (1H,
dd, Jb–3 1.9 Hz and Ja–b 5.3 Hz, CꢀCHa), 3.86 (2H, m,
NCH2CHꢀCH2), 4.27 (1H, d, J 16.3 Hz, PhCHHN),
4.45 (1H, d, J 16.3 Hz, PhCHHN), 5.11 (1H, d, J 7.4
Hz, PhCHꢀCH), 5.26 (2H, m, NCH2CHꢀCH2), 5.91
(1H, m, NCH2CHꢀCH2) and 7.10–7.50 (10H, m, 2×
Yellow oil (0.076 g, 68%). B.p.\100°C (dec.).
Found: C, 65.55; H, 4.55; N, 3.29; C22H19FeNO3 re-
quires: C, 65.82; H, 4.77; N, 3.49). B.p.\100°C (dec.)
IR (thin film): wmax 2034vs (CꢂO) and 1958vs br cm−1
1
(CꢂO). H-NMR (300 MHz; CDCl3): l 0.68 (1H, d, J
5.1 Hz, CꢀCHb), 1.82 (1H, d, J 8.1 Hz, PhCHꢀCH),
2.10 (1H, dd, Ja–3 1.9 Hz and Ja–b 5.1 Hz, CꢀCHa),
4.15–4.43 (2H, m, NCH2CHꢀCH2), 5.18 (1H, d, J 7.5
Hz, PhCHꢀCH), 5.22–5.41 (2H, m, NCH2CHꢀCH2),
5.94–6.05 (1H, m, NCH2CHꢀCH2) and 7.07–7.42
(10H, m, 2×arylꢁH). 13C-NMR (75 MHz; CDCl3): l
36.01 (CꢀCH2), 54.52 (NCH2CHꢀCH2), 55.07 (C4),
63.58 (C3), 117.03 (NCH2CHꢀCH2), 125.46, 125.75,
126.05, 126.10, 127.56, 128.41, 129.61, 133.69, 141.93
and 145.92 (2×Ph, C2 and NCH2CHꢀCH2).
arylꢁH). 13C-NMR (75 MHz; CDCl3):
l 31.93
(CꢀCH2), 54.01 (NCH2Ph and NCH2CHꢀCH2), 55.19
(C4), 62.15 (C3), 118.27 (NCH2CHꢀCH2), 125.65,
126.07, 127.07, 127.42, 128.38, 128.80, 129.79, 133.25,
137.62 and 142.12 (2×Ph, C2 and NCH2CHꢀCH2).
4.8. (2-(N-Methyl-N-(4-methoxyphenyl)amino)-4-
phenylbuta-1,3-diene)tricarbonyliron(0) (19)
4.5. (2-(N-Methyl-N-benzylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (16)
Yellow crystals, (0.048 g, 46%). M.p. 124–126°C.
Found: C, 62.10; H, 4.56; N, 3.45%, C21H19NFeO4
requires: C, 62.24; H, 4.73; N, 3.45%. IR (C4Cl6): wmax
2036vs (CꢂO), 1971vs (CꢂO) and 1954vs cm−1 (CꢂO).
1H-NMR (300 MHz; CDCl3): l 0.55 (1H, d, J 5.2 Hz,
CꢀCHb), 1.85 (1H, d, J 8.2 Hz, PhCHꢀCH), 2.02 (1H,
dd, Ja–3 1.9 Hz and Ja–b 5.1 Hz, CꢀCHa), 3.20 (3H, s,
NCH3), 3.83 (3H, s,OCH3), 5.05 (1H, d, J 7.6 Hz,
PhCHꢀCH) and 6.93–7.23 (9H, m, 2×arylꢁH). 13C-
NMR (75 MHz; CDCl3): l 32.68 (CꢀCH2), 39.25
(NCH3), 55.36 (C4), 55.46 (OCH3), 62.18 (C3), 114.77,
125.66, 126.07, 126.95, 128.35, 128.83, 139.33, 142.00
and 57.51 (2×Ph and C2).
Yellow crystals, (0.061 g, 58%). M.p. 78–79°C.
Found: C, 64.63; H, 4.79; N, 3.59% C21H19NFeO3
requires: C, 64.77; H, 4.92; N, 3.60%. IR (C4Cl6): wmax
2037s (CꢂO), 1972s (CꢂO) and 1955s cm−1 (CꢂO).1H-
NMR (300 MHz; CDCl3): l 0.49 (1H, d, J 5.2 Hz,
CꢀCHb), 1.84 (1H, d, J 8.0 Hz, PhCHꢀCH), 2.20 (1H,
dd, Ja–3 2.0 Hz and Ja–b 5.1 Hz, CꢀCH), 2.85 (3H, s,
NCH3), 4.23 (1H, d, J 15.8 Hz, PhCHHN), 4.35 (1H,
d, J 15.8 Hz, PhCHHN), 5.12 (1H, d, J 7.2 Hz,
PhCHꢀCH) and 7.09–7.39 (10H, m, 2×arylꢁH). 13C-
NMR (75 MHz; CDCl3): l 31.61 (CꢀCH2), 38.27
(NCH3), 55.33 (C4), 56.38 (NCH2Ph), 61.65 (C3),
125.66, 126.08, 127.24, 127.50, 128.38, 128.81, 129.44,
137.56 and 142.09 (2×Ph and C2).
4.9. (2-(N-Benzyl-N-(4-methoxyphenyl)amino)-4-
phenylbuta-1,3-diene)tricarbonyliron(0) (20)
4.6. (2-(N,N-Dibenzylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (17)
Yellow oil, (0.068 g, 54%). B.p.\100°C (dec.).
Found: C, 67.20: H, 4.87; N, 2.80. C27H23FeNO4 re-
quires: C, 67.35; H, 4.82: N, 2.91%. IR (thin film): wmax
2034vs (CꢂO) and 1967vs, br cm−1 (CꢂO)1H-NMR
(300 MHz; CDCl3): l 0.60 (1H, d, J 5.2 Hz, CꢀCHb),
Yellow oil, (0.094 g, 76%). M.p.\100°C (dec.)
.Found: C, 69.44; H, 4.80; N, 3.00; C27H23NFeO3 re-
quires: C, 69.66, H 4.98; N, 3.01. IR (thin film): wmax
1
2033vs (CꢂO) and 1942vs br cm−1 (CꢂO). H-NMR

206
P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
1.80 (1H, d, J 8.1 Hz, PhCHꢀCH), 2.06 (1H, dd, Ja–3
1.8 Hz and Ja–b 5.2 Hz, CꢀCHa), 3.80 (3H, s,OCH3),
4.63 (1H, d, J 16.2 Hz, PhCHHN), 4.88 (1H, d, J 16.2
Hz, PhCHHN), 5.02 (1H, d, J 7.7 Hz, PhCHꢀCH) and
6.70–7.38 (15H, m, 3×arylꢁH). 13C-NMR (75 MHz;
CDCl3): l 34.81 (CꢀCH2), 55.34 (C4), 55.42 (OCH3),
56.37 (NCH2Ph), 63.30 (C3), 114.92, 125.86, 126.04,
126.92, 127.33, 127.97, 128.31, 129.09, 137.99, 141.76
and 141.90 (3×Ph and C2).
d, J 4.9 Hz,CꢀCHb), 1.27 (3H, d, J 6.3 Hz,CH(CH3)2),
1.32 (3H, d, J 6.3 Hz, CH(CH3)2), 1.80 (1H, dd, Ja–3
1.7 Hz and Ja–b 4.9 Hz,CꢀCHa), 1.85 (1H, d, J 7.9 Hz,
PhCHꢀCH), 3.26–3.63 (2H, m, PhCH2N), 5.13 (1H, d,
J 7.9 Hz, PhCHꢀCH) and 6.83–7.29 (10H, m, 2×
arylꢁH). 13C-NMR (75 MHz; CDCl3): l 22.22 and
23.90 (CH(CH3)2), 29.69 (CH(CH3)2), 30.87 (CꢀCH2),
44.89 (NCH2Ph), 54.54 (C4), 60.68 (C3), 125.57,
126.04, 128.29, 128.38, 128.59 and 128.90 (2×Ph and
C2).
4.10. (2-(N-Allyl-N-(4-methoxyphenyl)amino)-4-
phenylbuta-1,3-diene)tricarbonyliron(0) (21)
4.13. (2-(N-Allyl-N-isopropylamino)-4-phenylbuta-
1,3-diene)tricarbonyliron(0) (24)
Yellow oil, (0.075 g, 66%). B.p.\100°C (dec.).
Found: C, 63.80; H, 5.01; N, 3.10. C23H21FeNO4 re-
quires: C, 64.02; H, 4.91; N, 3.25%. IR (thin film): wmax
2036s (CꢂO), 1971s (CꢂO) and 1956s cm−1 (CꢂO)1H-
NMR (300 MHz; CDCl3): l 0.57 (1H, d, J 5.2 Hz,
CꢀCHb), 1.81 (1H, d, J 8.1 Hz, PhCHꢀCH), 2.03 (1H,
dd, Ja–3 1.8 Hz and Ja–b 5.2 Hz, CꢀCHa), 3.84 (3H,
S,OCH3), 4.06–4.29 (2H, m, NCH2CHꢀCH2), 5.03 (1H,
Yellow crystals (0.045 g, 72%). M.p. 95–96°C.
Found: C, 62.11; H, 5.78; N, 3.73%C19H21NFeO3 re-
quires: C, 62.14; H, 5.76; N 3.81%. IR (C4Cl6): wmax
2034vs (CꢂO), 1969vs (CꢂO) and 1952vs cm−1 (CꢂO).
1H-NMR (300 MHz; CDCl3): l 0.46 (1H, d, Ja–b5.4
Hz, CꢀCHb), 1.16 (3H, d, J 6.7 Hz, CHCH3), 1.22 (3H,
d, J 6.7 Hz, CHCH3), 1.83 (1H, d, J 7.9 Hz,
PhCHꢀCH), 2.18 (1H, dd, Ja–3 1.8 Hz and Ja–b 5.4 Hz,
CꢀCHa), 3.73 (2H, m, NCH2CHꢀCH2), 4.05 (1H, sept,
J 6.7 Hz, CH(CH3)2), 5.05 (1H, d, J 7.8 Hz,
PhCHꢀCH), 5.30 (2H, m, NCH2CHꢀCH2), 5.96 (1H,
m, NCH2CHꢀCH2), and 7.08–7.26 (5H, m, arylꢁH).
13C-NMR (75 MHz; CDCl3): l 19.53 (CHCH3), 20.86
(CHCH3), 31.29 (CꢀCH2), 47.02 (NCH2CHꢀCH2),
50.26 (CH(CH3)2), 55.06 (C4), 59.81 (C3), 116.13
(NCH2CHꢀCH2), 125.48, 126.08, 128.34, 131.88, 135.96
and 142.66 (Ph, C2 and NCH2CHꢀCH2).
d,
J
7.7 Hz, PhCHꢀCH), 5.20–5.36 (2H, m,
NCH2CHꢀCH2), 5.93–6.02 (1H, m, NCH2CHꢀCH2)
and 6.93–7.26 (9H, m, 2×arylꢁH). 13C-NMR (75
MHz;
CDCl3):
l
33.63
(CꢀCH2),
55.07
(NCH2CHꢀCH2), 55.23 (C4), 55.45 (OCH3), 62.48
(C3), 117.12 (NCH2CHꢀCH2), 114.88, 125.64, 126.08,
128.19, 128.36, 129.13, 133.60, 138.22 and 142.10 (2×
Ph, C2 and NCH2CHꢀCH2).
4.11. (2-(N-Methyl-N-isopropylamino)-4-
phenylbuta-1,3-diene)tricarbonyliron(0) (22)
5. Supplementary material
Yellow oil, (0.066 g, 64%). B.p.\100°C (dec.).
Found C, 59.60; H, 5.75; N, 3.99. C17H19FeNO3 re-
quires: C, 59.81; H, 5.61 N, 4.11%. IR (C4Cl6): wmax
2035vs (CꢂO), 1969vs (CꢂO) and 1954vs cm−1 (CꢂO).
1H-NMR (300 MHz; CDCl3): l 0.44 (1H, d, J 5.2 Hz,
CꢀCHb), 1.19 (6H, d, J 6.6 Hz, CH(CH3)2), 1.85 (1H, d,
J 7.9 Hz, PhCHꢀCH), 2.15 (1H, dd, Ja–3 2.0 Hz and
Ja–b 5.3 Hz, CꢀCHa), 2.73 (3H, s, NCH3), 4.04 (1H,
sept, J 6.6 Hz, CH(CH3)2), 5.04 (1H, d, J 7.1 Hz,
PhCHꢀCH) and 7.08–7.26 (5H, m, arylꢁH). 13C-NMR
(75 MHz; CDCl3): l 19.31 and 19.64 (CH(CH3)2),
29.75 (NCH3), 30.71 (CꢀCH2), 49.75 (CH(CH3)2),
54.84 (C4), 58.50 (C3), 125.46, 125.56, 126.06, 128.33,
131.74 and 142.69 (Ph and C2).
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 142582 for compound (19)
and CCDC No. 142583 for compound (24). Copies of
this information may be obtained free of charge from:
The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax: +44-1223-336-033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.
cam.ac.uk).
Acknowledgements
We thank the E.P.S.R.C. for financial support (MEH
and PMB).
4.12. (2-(N-Benzyl-N-isopropylamino)-4-
phenylbuta-1,3-diene)tricarbonyliron(0) (23)
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1
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P.M. Branton et al. / Journal of Organometallic Chemistry 613 (2000) 200–207
207
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.