Diiron-aminocarbyne complexes with amine or imine ligands: C-N coupling between imine and aminocarbyne ligands promoted by tolylacetylide addition to [Fe2{μ-CN(Me)R}(μ-CO)(CO)(NH=CPh2)(Cp) 2][SO3CF3]

Article abstract of DOI:10.1016/j.jorganchem.2004.09.043

A terminally coordinated CO ligand in the complexes [Fe₂{μ- CN(Me)R}(μ-CO)(CO)₂(Cp)₂][SO₃CF ₃] (R = Me, 1a; R = Xyl, 1b; Xyl = 2,6-Me₂C ₆H₃), is readily displaced by primary and secondary amines (L), in the presence of Me₃NO, affording the complexes [Fe ₂{μ-CN(Me)R}(μ-CO)(CO)(L)(Cp)₂][SO ₃CF₃] (R = Me, L = NH₂Et, 4a; R = Xyl, L = NH₂Et, 4b; R = Me, L = NH₂Prⁱ, 5a; R = Xyl, L = NH₂Prⁱ, 5b; R = Xyl, L = NH₂C ₆H₁₁, 6; R = Xyl, L = NH₂Ph, 7; R = Xyl, L = NH₃, 8; R = Me, L = NHMe₂, 9a; R = Xyl, L = NHMe ₂, 9b; R = Xyl, = NH(CH₂)₅, 10). In the absence of Me₃NO, NH₂Et gives addition at the CO ligand of 1b, yielding [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(O)NHEt}(Cp) ₂] (11). Carbonyl replacement is also observed in the reaction of 1a-b with pyridine and benzophenone imine, affording [Fe₂{μ-CN(Me) R}(μ-CO)(CO)(L)(Cp)₂][SO₃CF₃] (R = Me, L = Py, 12a; R = Xyl, L = Py, 12b; R = Me, L = HNCPh₂, 13a; R = Xyl, L = HNCPh₂, 13b). The imino complex 13b reacts with p-tolylacetylide leading to the formation of the μ-vinylidene-diaminocarbene compound [Fe ₂{μ-η¹:η²- CC(Tol)C(Ph) ₂N(H)CN(Me)(Xyl){(μ-CO)(CO)(Cp₂)] (15) which has been studied by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2004.09.043

Journal of Organometallic Chemistry 690 (2005) 348–357
www.elsevier.com/locate/jorganchem
Diiron-aminocarbyne complexes with amine or imine ligands:
C–N coupling between imine and aminocarbyne
ligands promoted by tolylacetylide addition to
[Fe2{l-CN(Me)R}(l-CO)(CO)(NH@CPh2)(Cp)2][SO3CF3]
*
Luigi Busetto, Fabio Marchetti, Stefano Zacchini, Valerio Zanotti , Eleonora Zoli
`
Dipartimento di Chimica Fisica ed Inorganica, Universita di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
Received 20 July 2004; accepted 20 September 2004
Abstract
A terminally coordinated CO ligand in the complexes [Fe2{l-CN(Me)R}(l-CO)(CO)2(Cp)2][SO3CF3] (R = Me, 1a; R = Xyl, 1b;
Xyl = 2,6-Me2C6H3), is readily displaced by primary and secondary amines (L), in the presence of Me3NO, affording the complexes
[Fe2{l-CN(Me)R}(l-CO)(CO)(L)(Cp)2][SO3CF3] (R = Me, L = NH2Et, 4a; R = Xyl, L = NH2Et, 4b; R = Me, L = NH2Pri, 5a;
R = Xyl, L = NH2Pri, 5b; R = Xyl, L = NH2C6H11, 6; R = Xyl, L = NH2Ph, 7; R = Xyl, L = NH3, 8; R = Me, L = NHMe2, 9a;
R = Xyl, L = NHMe2, 9b; R = Xyl, = NH(CH2)5, 10). In the absence of Me3NO, NH2Et gives addition at the CO ligand of 1b,
yielding [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO){C(O)NHEt}(Cp)2] (11). Carbonyl replacement is also observed in the reaction of 1a–
b with pyridine and benzophenone imine, affording [Fe2{l-CN(Me)R}(l-CO)(CO)(L)(Cp)2][SO3CF3] (R = Me, L = Py, 12a;
R = Xyl, L = Py, 12b; R = Me, L = HN@CPh2, 13a; R = Xyl, L = HN@CPh2, 13b). The imino complex 13b reacts with p-tolylacety-
lide leading to the formation of the l-vinylidene-diaminocarbene compound [Fe2{l-g1:g2- C@C(Tol)C(Ph)2N(H)CN(Me)(Xyl){(l-
CO)(CO)(Cp2)] (15) which has been studied by X-ray diffraction.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Amine; Imine; Diaminocarbene; Vinylidene; Diiron complexes; Crystal structure
1. Introduction
the carbonyl (organo-cuprates, acetylides) and cyclo-
pentadienyl ligand (organo-lithium or Grignard rea-
gents), respectively [1]. On the other hand, weaker
nucleophiles, including isocyanides, CNꢀ, nitriles, ha-
lides and phosphines react with 1 and 2, giving CO
replacement, under thermal, photolytic or chemical
activation [2]. Reactions involving the bridging amino-
carbyne ligand of 1 have been limited to the addition
of hydride (from NaBH4) and cyanide (from
NBu4CN), affording the corresponding aminocarbene
complexes [3]. More recently, we have reported on
the insertion of alkynes (R0CCR00) into the metal–car-
byne carbon bond of the acetonitrile complexes
[Fe2{l-CN(Me)R}(l-CO)(CO)(NCMe)(Cp)2][SO3CF3]
Diiron bridging aminocarbyne complexes [Fe2{l-
CN(Me)R}(l-CO)(CO)2(Cp)2][SO3CF3] (R = Me, 1a;
R = Xyl, 1b; Xyl = 2,6-Me2C6H3) and [Fe2(l-CNMe2)2-
(CO)2(Cp)2][SO3CF3]2 (2) exhibit a remarkable electro-
philic character. It has been shown that carbon
nucleophiles ðR0ꢀÞ react with 1 to give [Fe2{l-CN(Me)-
R}(l-CO)(CO)(COR0)(Cp)2] or [Fe2{l-CN(Me)R}(l-
CO)(CO)2(g4-C5H5R0)Cp)] via selective addition at
*
Corresponding author. Tel.: +39 051 209 3700; fax: +39 051 209
3690.
E-mail address: valerio.zanotti@unibo.it (V. Zanotti).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.09.043

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
349
(R = Me, 3a; Xyl, 3b; CH2Ph, 3c), which leads to the
formation of bridging vinyliminium complexes [Fe2-
{l-r:g3-C(R0)@C(R00)C@N(Me)(R)}(l-CO)(CO)(Cp)2]-
[SO3CF3] (R0 = Me, COOMe, SiMe3, Ph, Tol; R00 = H,
Me, Et, Ph) via coupling of the alkyne and amino-
carbyne ligand [4].
including secondary amines and ammonia, but not terti-
ary amines (NMe3, NEt3), react analogously affording
the complexes [Fe2{l-CN(Me)R}(l-CO)(CO)(NHR0R00)-
(Cp)2][SO3CF3] (5–10) in comparable yields (Scheme 1).
Complexes 4–10 have been characterized by IR and
NMR spectroscopy and elemental analysis. Moreover,
the structure of 4a has been ascertained by an X-ray dif-
fraction experiment; its molecular structure is reported
in Fig. 1, whereas the main bond lengths and bond an-
gles are reported in Table 1.
Reactions of the diiron l-aminocarbyne complexes
with amines have been scarcely investigated. It has been
shown that 2 undergoes addition of HNR02 at the CO
yielding the carbamoyl complexes [Fe2(l-CNMe2)2(l-
CO){C(O)NR0}(Cp)2][SO3CF3]. Primary amines gener-
ate carbamoyl intermediates which further react, by
dehydration, giving isocyanide derivatives [2b].
On the light of a renewed interest towards nitrogen-
containing ligands, mainly due to applications in the
field of catalysis [5], we have been interested at determin-
ing whether nitrogen ligands, including amines and imi-
nes, could be coordinated to the Fe atom in the
aminocarbyne complexes 1a–b and 3a–b, and at investi-
gating their chemistry. Our findings are the matter of
this paper.
The Cp ligands in 4a adopt a cis geometry relative to
the mean plane determined by the Fe2(l-C)2 core, as
previously reported for analogous diiron complexes con-
taining a bridging aminocarbyne ligand [1,2,6]. The
˚
C(12)–N(1) interaction [1.305(15) A] exhibits a consider-
ably double bond character, suggesting that the l-ami-
nocarbyne ligand can be alternatively described as a
l-iminium ligand; in agreement with this, both N(1)
and C(12) show an almost perfect sp2 hybridisation
[sum angles 360.0(22)ꢁ and 359.7(6)ꢁ, respectively]. The
˚
Fe(2)–N(2) interaction [2.023(8) A] indicates a pure r-
bond, as expected for a coordinated amine ligand. The
compound 4a exists in the solid state as {[Fe2{l-
CNMe2}(l-CO)(CO)(NH2Et)(Cp)2][SO3CF3]}2 dimers,
because of the presence of hydrogen bonds between
the twoꢀNH2 protons of the cations and two different
CF3SO3 anions (Fig. 2). Thus, each triflate anion acts
as a bridging hydrogen bond acceptor between two dis-
tinct [Fe2{l-CNMe2}(l-CO)(CO)(NH2Et)(Cp)2]+ cati-
ons, via two of its three oxygen atoms.
2. Results and discussion
2.1. Reactions with amines
The reactions of compounds 1a–b, in tetrahydrofuran
solution, at room temperature, with an excess of ethyl-
amine in the presence of Me3NO, result in the formation
of the amino complexes [Fe2{l-CN(Me)R}(l-CO)
(CO)(NH2Et)(Cp)2][SO3CF3] (R = Me, 4a; R = Xyl,
4b) (Scheme 1), which have been isolated in about 65–
70% yields after filtration on alumina. Other amines,
The IR spectra of compounds 4–10, in CH2Cl2 solu-
tion, exhibit the usual m-CO band pattern, consisting in
one terminal and one bridging absorption (e.g., for 4a at
1
1969 and 1800 cmꢀ1). The H and 13C NMR spectra of
+
R
Me
Fe
+
C13
R
Me
Fe
N
C
C14
N
C
OC
C17
CO
OC
NHR'R''
NHR'R''
Fe
H2b
N1
Fe
H2c
C
O
Me3NO
- CO2
C
O
O11
N2
C12
C11
C16
R
NHR’R’’
NH2Et
R
Me
Xyl
Me
Xyl
Xyl
Xyl
Xyl
Me
Xyl
Xyl
4a
4b
5a
5b
6
Me
Xyl
1a
1b
Fe2
NH2Et
NH2Pri
NH2Pri
Fe1
C15
O15
NH2C6H11
NH2Ph
7
NH3
8
NHMe2
NHMe2
NH(CH2)5
9a
9b
10
Fig. 1. Molecular structure of 4a, with key atoms labelled (all H
atoms, apart from H2b and H2c, have been omitted). Displacement
ellipsoids are at 30% probability level. Only the main images of the
disordered Cp ligands are drawn.
Scheme 1.

350
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
Table 1
+
+
Me
Xyl
Xyl
Fe
˚
Me
Fe
Selected bond lengths (A) and angles (ꢁ) for complex 4a
N
C
N
Fe(1)–Fe(2)
Fe(1)–C(11)
Fe(1)–C(12)
Fe(2)–C(12)
Fe(1)–C(15)
Fe(2)–C(15)
Fe(2)–N(2)
2.491(3)
C(11)–O(11)
C(15)–O(15)
C(12)–N(1)
N(1)–C(13)
N(1)–C(14)
N(2)–C(16)
C(16)–C(17)
1.162(14)
1.206(15)
1.305(15)
1.48(2)
OC
OC
NHR'R''
NHR'R''
C
1.729(12)
1.895(12)
1.800(13)
1.938(14)
1.843(15)
2.023(8)
Fe
Fe
C
O
C
O
1.480(18)
1.456(17)
1.484(19)
Fig. 3. Isomers due to the different orientations of the amino carbyne
substituents.
Fe(1)–C(12)–Fe(2)
Fe(1)–C(15)–Fe(2)
C(12)–N(1)–C(13)
C(12)–N(1)–C(14)
84.7(6)
82.4(5)
C(13)–N(1)–C(14)
Fe(2)–N(2)–C(16)
Fe(1)–C(12)–N(1)
Fe(2)–C(12)–N(1)
113.3(12)
120.1(9)
122.0(13)
124.7(13)
135.9(10)
139.1(10)
CO, in a way similar to that reported for the reactions
of [Fe2(l-CNMe2)2(CO)2(Cp)2][SO3CF3]2 (2) with
NH2R [2b]. For example, the reaction of [Fe2{l-
CN(Me)(Xyl)}(l-CO)(CO)2)(Cp)2][SO3CF3] (1b) with a
large excess of NH2Et, generates the complex [Fe2{l-
CN(Me)(Xyl)}(l-CO)(CO){C(O)NHEt}(Cp)2] (11). As
for the mononuclear complex [Fe(CO)3Cp]+ [7], the
reaction presumably proceeds via nucleophilic addition
at the coordinated CO, followed by deprotonation due
to the excess of amine. The addition is reversible and re-
moval of the volatile materials, including the amine,
shifts the equilibrium toward the starting complex. Bet-
ter yields are obtained upon treatment of the reaction
mixture with NaH (Scheme 2).
O20'
S1'
O10'
H2B'
O30'
N2
H2C
N2'
H2C'
O30
S1
H2B
O10
O20
Complex 11 has been characterized by NMR and IR
spectroscopy (see Section 3). The presence of the
C(O)NHEt ligand is supported by the observed 1H
NMR broad resonance at 5.74 ppm, attributable to
the N–H, and by the 13C NMR signal at 202.9 ppm
due to the carboxamido carbon.
Fig. 2. Representation of the hydrogen bonded {[Fe2{l-CNMe2}-
(l-CO)(CO)(NH2Et)(Cp)2][SO3CF3]}2 dimers in 4a[CF3SO3]. N(2)ꢁꢁꢁO(20)
0
˚
˚
3.098(14) A, N(2)ꢁ ꢁ ꢁO(10 ) 3.001(12) A.
Since complexes 4–10 have been obtained from 1a–b
via CO displacement, their syntheses could be alterna-
tively accomplished by removal of the labile MeCN
from [Fe2{l-CN(Me)R}(l-CO)(CO)(NCMe)(Cp)2][SO3-
CF3] (R = Me, 3a; Xyl, 3b). However, it should be con-
sidered that coordinated nitriles are also susceptible of
nucleophilic addition by amines, with formation of me-
tal amidinates [8]. In order to determine which of the
two possibilities (addition vs. substitution) prevails, 3b
has been treated with amines (NH2Pri, NH2Ph). Our
findings show that the reactions proceed with replace-
ment of the nitrile ligand; thus the observed products
are the amine complexes 5b and 7, respectively, obtained
in comparable yields with respect to the synthesis
the complex 4a show two signals of the same intensity
for the non-equivalent N-bonded methyl groups (at
4.68, 4.25 and 54.0, 52.5 ppm, respectively) and indicate
the presence of a single isomer. The two N-bonded
hydrogens of the NH2Et ligand are also non-equivalent
and originate two high field shifted broad multiplets (at
2.45 and 2.76 ppm). The spectra of 4b, 5b, 6–8, 9b and
10, which contain the asymmetrically substituted l-
CN(Me)(Xyl), show the presence of minor amounts of
a second isomeric form, as usually found in complexes
of the type [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO)(L)(Cp)2]+
(L = CNR, NCR, PR3) and [Fe2{l-CN(Me)(Xyl)}(l-
CO)(CO)(L)(Cp)2] (L = C(O)R, CH2 CN, CN, Cl)
[1,2]. This is due to the different orientations that Me
and Xyl groups can assume with respect to the non-
equivalent Fe atoms, and are consequence of the double
bond character of the l-C@N interaction, which do not
allow inter-conversion of the isomers via rotation
around the C–N bond (Fig. 3).
+
Xyl
Fe
Me
O
Xyl
Fe
Me
N
C
N
C
OC
C NHEt
OC
CO
1) NH2Et
2) NaH
Fe
Characteristic feature in the 13C NMR spectra of all
the complexes 4–10 is the low field resonance of the
bridging carbyne carbon (in the 335–340 ppm range).
It is worth noting that the syntheses above described
take place only in the presence of Me3NO; otherwise,
the amine attack occurs at the terminally coordinated
Fe
C
O
C
O
11
1b
Scheme 2.

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
351
+
+
Me
Fe
R
R
Me
Fe
Me
R
N
C
N
C
N
C
OC
OC
OC
CO
CO
NH2R'
NaH
Fe
Fe
Ph
Ph
Fe
Fe
H
H
C
O
N=C
Py
C
O
Me3NO
Me3NO
1a-b
+
+
Me
Fe
R
14a, R = Me
14b, R = Xyl
Me
R
5a, R = Me, R' = Pri
N
C
5b, R = Xyl, R' = Pri
N
C
H
Ph
Ph
OC
N=C
Py
OC
6, R = Xyl, R' = C6H11
Fe
Fe
Fe
C
O
Scheme 4.
C
O
the known bridging hydride complexes [Fe2{l-
CN(Me)(R)}(l-H)(CO)2 (Cp)2] (R = Me, 14a; R = Xyl,
14b) [2c] have been formed (Scheme 4). The reaction
resembles that described for the mononuclear complex
[CpRu(HNMe2)(PPh3)2]+, in which deprotonation of
the coordinated amine was followed by b-hydrogen
elimination from the N–Me, leading to the formation
of the hydride complex [CpRu(H)(PPh3)2], with release
of MeN@CH2 [11b]. A difference consists in the fact that
in 14, the hydride ligand is bridging instead of terminally
coordinated. This is in accordance with the preference of
Hꢀ for the bridging coordination and with the exchange
that easily occurs between bridging and terminal coordi-
nation positions within the Fe2(CO)2Cp2 frame. Support
to the above assumptions comes by observing that com-
pound 7, in which the aniline ligand cannot undergo b-
hydrogen transfer, does not form the hydride complex
14, under the same reaction conditions.
Stable azavynilidene complexes can be generated by
deprotonation of coordinated imines [12]. However, we
have recently reported that the azavinylidene complex
[Fe2{l-CN(Me)(Xyl)}(l-CO)(CO){NC(C„CTol)But}-
(Cp)2] is unstable and undergoes an intramolecular rear-
rangement, with coupling of the azavinylidene with the
aminocarbyne ligands [13]. The reaction ultimately led
to the formation of the l-allenyl-diaminocarbene com-
plex [Fe2{l-g1:g3-C(Tol)@C@C(CMe3)N(H)CN(Me)-
(Xyl)}(l-CO)(CO)(Cp2)][SO3CF3]. In the light of these
observations, we have investigated the reactions of
13a–b with NaH, in order to obtain the deprotonation
of the imine ligand and possibly promote further rear-
rangements and C–N bond formation. Unfortunately,
these attempts failed to produce any stable product.
However, we have found that the coordinated imine
can be attacked by acetilydes. In fact, addition of
TolC„CLi (2.5–3 equivalents) to a THF solution of
13b, at low temperature, results, after work up, in the
new neutral complex [Fe2{l-g1:g2-C@C(Tol)C(Ph)2-
(NH)CN(Me)(Xyl)}(l-CO)(CO) (Cp2)] (15), obtained in
moderate yields (52%) (Scheme 5). The nature of 15 has
beenfully elucidated by X-ray and the molecular structure
is reported in Fig. 4, whereas relevant bond lengths and
angles are reported in Table 2.
12a, R = Me
12b, R = Xyl
13a, R = Me
13b, R = Xyl
Scheme 3.
reported in Scheme 1, and no addition at the coordi-
nated MeCN has been revealed to any extent.
2.2. Reactions with pyridine and benzophenone imine
Replacement of CO from 1a–b, in the presence of
Me3NO, has been accomplished also by pyridine
(Py = NC5H5), and benzophenone imine (HN@CPh2).
The reactions lead to the formation of [Fe2{l-
CN(Me)R}(l-CO)(CO)(L)(Cp)2][SO3CF3] (R = Me, L =
Py, 12a; R = Xyl, L = Py 12b; R = Me, L = HN@CPh2,
13a; R = Xyl, L = HN@CPh2, 13b) (Scheme 3). Com-
pounds 12 and 13 exhibit spectroscopic properties similar
to those of 4–10. Imine coordination in 13a–b is revealed
by the IR absorption m(N–H) at 3314 cmꢀ1 (in KBr pel-
lets), and the 1H NMR resonance at ca. 6.1–6.3 ppm. Ma-
jor features of the 13C NMR spectrum of 13a–b include
the expected low-field resonance of the l-aminocarbyne
carbon, and the resonance attributable to the imine car-
bon at about 191 ppm.
The above-described reactions indicate that replace-
ment of the coordinated CO or NCMe by amines are
the favourite routes, and that the l-aminocarbyne
ligand remains unaffected. This result is not obvious,
because other related cationic diiron complexes of the
type [Fe2{l-C(SMe2)CN}(l-CO)(CO)2)(Cp)2]+ [3],
[Fe2(l-CAr)(g8-C8H8)(CO)4)]+ [9] and [Fe2(l-CH)(s-
CO)(CO)2)(Cp)2]+ [10] have been shown to react with
amines at the bridging carbene or carbyne carbon,
rather than involving the terminally coordinated CO.
2.3. Reactions of the coordinated amine and imine ligands
Deprotonation of coordinated primary or secondary
amines represents a possible route to the synthesis of
amide complexes [11], thus the compounds 5a–b and 6
containing NH2Pri and NH2C6H11, respectively, have
been treated with NaH or BuLi with the aim of obtain-
ing the corresponding amide complexes. Unexpectedly,

352
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
Ph
the different electronic environment of the two iron
Ph
+
H
atoms. In particular, Fe(1) results to be electron richer
than Fe(2), because the former is bound to a r-donating
diaminocarbene ligand, whereas the latter is attached to
Tol
Fe
C
Me
Xyl
OC
Xyl
N
C
C
C
N
C
H
Ph
Ph
N
OC
N=C
Me
LiC CTol
Fe
p-acidic CO ligand. The bridging l-g1:g2-
Fe
Fe
a
C
O
C
O
C@C(Tol)C(Ph)2N(H)CN(Me)(Xyl) ligand contains
two distinct groups; i.e., the bridging vinylidene and a
terminal diaminocarbene, linked by a saturated CPh2
group. The bridging vinylidene l-C@C is bound almost
symmetrically to the iron atoms and the C(13)–C(14)
13b
15
Scheme 5.
˚
distance [1.341(4) A] is typical for bridging vinylidenes
[14]. Despite the remarkable differences between N(1)
and N(2) (i.e., different substituents, one is endo-cyclic
the other exo-cyclic), the distances C(35)–N(1)
˚
˚
[1.353(4) A] and C(35)–N(2) [1.355(4) A] are almost
identical and show partial double bond character, sug-
gesting electron donation from the two nitrogen atoms
to the central carbon. As a consequence, all three atoms
show a nearly perfect sp2 hybridisation [sum angles
359.5(4)ꢁ, 360(3)ꢁ and 360.0(5)ꢁ at C(35), N(1) and
N(2), respectively] and the diaminocarbene unit is al-
most planar [N(1)–C(35)–N(2)–Fe(1) torsion angle
171.84(47)ꢁ]. Fe(1) can also be viewed as part of a six
membered ring constituted by Fe(1), C(35), N(1),
C(22), C(14) and C(13) which can be described as a 1-
metalla-3-aza-1,5-hexadiene with a boat conformation.
The IR spectrum of 15, in CH2Cl2, shows two bands
at 1934 vs and 1734 s cmꢀ1, attributable to the terminal
and bridging CO ligands, respectively, These bands are
strongly shifted toward lower frequencies compared to
the starting complex 13b (1978vs and 1813s cmꢀ1), as
a direct consequence of the different charge of the two
complexes. The main features of the 1H NMR spectrum
of 15 in CD2Cl2 are the presence of two distinct reso-
nances for the inequivalent Cp ligands and a broad res-
onance at 8.87 ppm due to the NH group. The bridging
vinylidene ligand l-Ca@Cb shows two resonances in the
13C NMR spectrum at 286–280 ppm (Ca) and 149–141
ppm (Cb), which are typical regions for this class of lig-
ands [14]. The resonance due to Ca falls in the high fre-
quencies region of the spectrum, very close to the one
due to l-CO, whereas Cb resonates in the same region
of the quaternary carbons of the aromatic rings (see Sec-
tion 3 for further details). Two other resonances are pre-
sent at relatively high frequencies, i.e., 220.5 and 216.3
ppm attributable to the diaminocarbene carbon and
the terminal CO, respectively. Finally, the ESI MS spec-
trum of 15 in CH3CN shows the presence of a positive
ion at m/z = 740, due to ionisation of 15.
H1n
N1
C22
C14
C37
O12
C12
N2
C35
C13
C36
Fe1
Fe2
C11
O11
Fig. 4. Molecular structure of 15, with key atoms labelled (all H
atoms, apart from H1n, have been omitted). Displacement ellipsoids
are at 30% probability level.
Table 2
˚
Selected bond lengths (A) and angles (ꢁ) for complex 15
Fe(1)–Fe(2)
Fe(1)–C(12)
Fe(1)–C(11)
Fe(2)–C(11)
Fe(1)–C(13)
Fe(2)–C(13)
Fe(1)–C(35)
C(11)–O(11)
2.5353(9)
1.741(4)
1.842(4)
2.002(4)
1.898(3)
1.906(3)
1.951(4)
1.199(4)
C(12)–O(12)
C(13)–C(14)
C(14)–C(22)
C(22)–N(1)
N(1)–C(35)
C(35)–N(2)
N(2)–C(36)
N(2)–C(37)
1.144(4)
1.341(4)
1.537(4)
1.503(4)
1.353(4)
1.355(4)
1.476(5)
1.439(4)
Fe(1)–C(11)–Fe(2)
Fe(1)–C(13)–Fe(2)
C(13)–C(14)–C(22)
C(22)–N(1)–C(35)
C(22)–N(1)–H(1n)
C(35)–N(1)–H(1n)
82.41(15)
83.60(14)
116.8(3)
128.8(3)
115(2)
N(1)–C(35)–N(2)
N(1)–C(35)–Fe(1)
N(2)–C(35)–Fe(1)
C(35)–N(2)–C(36)
C(35)–N(2)–C(37)
C(36)–N(2)–C(37)
111.8(3)
121.6(2)
126.1(2)
122.9(3)
124.5(3)
112.6(3)
116(2)
The molecule contains a novel g1:g2 vinylidene-
diaminocarbene ligand [i.e., l-g1:g2-C@C(Tol)C(Ph)2-
N(H)CN(Me)(Xyl)] coordinated to a Fe2(l-CO)(CO)-
(Cp2) core. The latter shows the usual cis arrangement
of the Cp ligands, and the Fe–Fe distance [2.5353(9)
A] is typical for a single bond. The bridging CO ligand
presents a significant asymmetry [Fe(1)–C(11),1.842(4)
˚
A; Fe(2)–C(11), 2.002(4) A], which is probably due to
Unfortunately, the reaction reported in Scheme 5 is
not of general character. Thus, addition of TolC„
CLi to a THF solution of [Fe2{l-CN(Me)2}(l-CO)-
(CO)(Ph2C@NH)(Cp)2][SO3CF3] (13a) failed to produce
any identifiable product. Also changing the acetylide
reagent has a dramatic effect on the reaction. Therefore,
the reaction of PhC„CLi with 13b led to the formation
˚
˚

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
353
of the g1:g2 vinylidene-diaminocarbene [Fe2{l-g1:g2-
C@C(Ph)C(Ph)2N(H)CN(Me)(Xyl)}(l-CO)(CO)(Cp2)]-
(16), in lower yields (31%), whereas the corresponding
reaction with CH3(CH2)3C„CLi resulted in a mixture
of decomposition products.
acetylide ligand, r-coordinated, could be directly availa-
ble for coupling with the imine carbon group or, alterna-
tively, could be transformed, after protonation, into a
bridging vinylidene ligand. Several examples describe
the transformation of alkynes into l-vinylidenes in dinu-
clear complexes [15]. In both cases, coupling with {l-
C[N(Me)(Xyl)][NC(Ph)2]} necessarily involves the Cb
carbon of the acetilyde in order to explain the observed
C–C bond formation (Scheme 6).
This hypothesis, far from providing any exhaustive
interpretation of the mechanism leading to the novel
vinylidene-diaminocarbene 15, simply underlines the
complexity of the reaction, which further emphasizes
the attitude of dinuclear aminocarbyne complexes in
promoting C–C and C–N bond formation [1,4,13,16].
The formation of 15 is worth some more comments.
The bridging vinylidene-diaminocarbene ligand l-
g1:g2-C@C(Tol)C(Ph)2N(H)CN(Me)(Xyl) is clearly the
result of the coupling between the l-aminocarbyne, the
benzophenone imine ligand and the tolylacetylide, how-
ever, the mechanism of formation is not obvious and pre-
sumably requires several steps. New C–N and C–C
bonds [C(35)–N(1) and C(14)–C(22) in Fig. 4] are formed
as a consequence of these couplings. Interestingly, the
new C–C bond is generated between the imine carbon
and the Cb carbon of TolCb„CaLi, and not with Ca,
as it would be expected if the reaction was simply the
nucleophilic addition of the tolylacetylide to the coordi-
nated imine ligand. Therefore, we assume that the first
step of the reaction consists in the deprotonation of the
coordinated imine by the acetylide to give the g1-azav-
inylidene intermediate [Fe2{l-CN(Me)(Xyl)}(l-CO)
(CO)(Ph2C@N)(Cp)2] (Scheme 6). Migration of the
azavinylidene to the bridging carbyne accounts for the
observed C–N bond formation and is in agreement with
a similar rearrangement observed in [Fe2{l-CN(Me)-
(Xyl)}(l-CO)(CO){NC(C„CTol)But}(Cp)2] [13] and
with the existence of species like [Fe2{l-CH(NCPh2)}-
(l-CO)(CO)(Cp)2] [10]. As a consequence of the migra-
tion, an unsaturation is formed on one iron and this
can be occupied by an acetylide ligand. This hypothesis
would explain why the stoichiometry of the reaction re-
quires, at least, 2 moles of acetylide per mole of com-
pound 13a, in order to obtain good yields. The
3. Experimental details
3.1. General
All reactions were carried out routinely under nitro-
gen using standard Schlenk techniques. Solvents were
distilled immediately before use under nitrogen from
appropriate drying agents. Glassware was oven-dried
before use. Infrared spectra were recorded on a Per-
kin–Elmer Spectrum 2000 FT-IR spectrophotometer
and elemental analyses were performed on a Thermo-
Quest Flash 1112 Series EA Instrument. ESI MS spectra
were recorded on a Waters Micromass ZQ 4000 with
samples dissolved in CH3CN. All NMR measurements
were performed on Varian Gemini 300 and Varian Mer-
cury 400 instruments. The chemical shifts for 1H and 13
C
were referenced to internal TMS. The spectra were fully
1
assigned via DEPT experiments and H,13C correlation
through gs-HSQC and gs-HMBC experiments [17]. Un-
less otherwise stated, NMR signals due to trace amounts
of second isomeric form are italicised. All the reagents
were commercial products (Aldrich) of the highest pur-
ity available and used as received. [Fe2(CO)4(Cp)2] was
from Strem and used as received. Compounds [Fe2{l-
CN(Me)R}(l-CO)(CO)2(Cp)2][SO3CF3] (R = Me, 1a;
Xyl, 1b) and [Fe2{l-CN(Me)R}(l-CO)(CO)(NCMe)-
(Cp)2][SO3CF3] (R = Me, 3a; Xyl, 3b) were prepared
as described in the literature [2a,2c,18].
+
Me
Xyl
OC
Me
Fe
Xyl
OC
N
C
H
Ph
Ph
N
C
Ph
Ph
N=C
N=C
LiC CTol
-HCCTol
Fe
Fe
Fe
C
O
C
O
13a
LiC CTol
3.2. Synthesis of [Fe2(l-CNMe2)(l-CO)(CO)(NH2Et)
(Cp)2][SO3CF3] (4a) and [Fe2{l-CN(Me)(Xyl)}(l-
CO)(CO)(NH2Et)(Cp)2][SO3CF3] (4b)
_
Ph
C
Ph
Ph
Ph
C
Me
H
Tol
Fe
C
Tol
Cβ
Cα
Fe
Xyl
Xyl
OC
N
N
C
N
C
C
N
OC
H+
Me
Gaseous NH2Et was bubbled into a stirred solution
of [Fe2(l-CN(Me2)}(l-CO)(CO)(CO)2(Cp)2][SO3CF3]
(1a) (160 mg, 0.30 mmol) in THF (15 ml) containing
Me3NO (39 mg, 0.51 mmol). The mixture was stirred
for 40 min and, then, the volatile material was removed
Fe
Fe
C
O
C
O
Scheme 6.

354
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
in vacuo. Chromatography of the residue on an alumina
column, with MeCN as eluent, gave 4a, which was crys-
tallized from CH2Cl2–Et2O mixture (v/v ratio 1/1). Yield
104 mg (63%). Found: C, 39.66; H, 4.26, N 5.28%.
C18H23F3Fe2N2O5S requires: C, 39.44; H, 4.23, N,
5.11%. IR (CH2Cl2) mmax (cmꢀ1) 1969 vs and 1800s
(CO). 1H NMR (CDCl3) d 4.88, 4.83 (s, 10H, Cp);
4.68, 4.25 (s, 6H, NMe2); 2.45 (br, 1H, NH2); 2.08 (q,
2H, JHH = 7 Hz, N–CH2–CH3); 0.75 (t, 3H, JHH = 7
Hz, N–CH2–CH3); ꢀ2.76 (br, 1H, NH2). 13C NMR
(CDCl3) d 331.3 (l-C); 268.8 (l-CO); 212.9 (CO); 88.1,
86.5 (Cp); 54.0, 52.5 (NMe2); 43.6 (N–C2–CH3); 17.2
(N–CH2–C3).
2.67, 2.17, 2.13 (s, 6H, Me2C6H3); 1.91 (m, 1H, (CH3)2
3
CH); 1.21, 1.13, 0.74, 0.69 (d, 6H, JHH = 6.3 Hz,
2
(CH3)2CH); ꢀ2.22 (d, 1H, JHH = 12.9 Hz, NH2); (Iso-
mers ratio = 10). 13C NMR (CDCl3) d 339.8 (l-C);
266.1 (l-CO); 213.7 (CO); 148.7 (ipso-Me2C6H3);
132.5, 130.4, 129.0 (Me2C6H3); 88.6, 88.0, 87.4, 87.0,
(Cp); 53.9 (NMe); 48.7 (Me2CH); 25.1, 20.9 (Me2CH);
18.8, 17.7 (C6H3Me2). ESI MS: ES + m/z 503; ES
ꢀ m/z 149.
3
3
3.4. Synthesis of [Fe{l-CN(Me)(Xyl)}(l-CO)(CO)-
(NH2R)(Cp)2][SO3CF3] (R = C6H11, 6; R = Ph, 7;
R = H, 8
Compound 4b was obtained reacting NH2Et with 1b
(200 mg, 0.322 mmol), with the same procedure de-
scribed for the synthesis of 4a.
Complexes 6–8 have been obtained by reacting 1b
(100 mg, 0.161 mmol) with the appropriate amine, with
the same procedure described for the synthesis of 5b.
Compound 7 was filtered on Celite instead of alumina.
Ammonia used for the synthesis of 8 was a 0.5 M solu-
tion in 1,4-dioxane.
4b:Yield 146 mg (72%). Found: C, 47.28; H, 4.35, N
4.11%. C25H29F3Fe2N2O5S requires: C, 47.05; H, 4.58;
N, 4.39%. IR (CH2Cl2) mmax (cmꢀ1) 1966vs and 1802s
(CO). 1H NMR (CDCl3) d 7.54–7.01 (m, 3H, Me2C6H3);
5.01, 4.96, 4.48, 4.40 (s, 10 H, Cp); 4.84 (s, 3H, NMe);
3.01 (br, 1H, NH2); 2.65, 2.16 (s, 6H, Me2C6H3); 2.25
6: Yield 79 mg (67%). Found: C, 49.97; H, 5.14; N,
4.10%. C29H35F3Fe2N2O5S requires: C, 50.16; H, 5.08;
N, 4.03%. IR (CH2Cl2) mmax (cmꢀ1) 1968vs and 1802s
3
(q, 2H, JHH = 7 Hz, N–CH2–CH3); 0.84, 0.76 (t, 3H,
3JHH = 7 Hz, N–CH2–CH3); ꢀ2.70 (br, 1H, NH2); (Iso-
mer ratio = 10). 13C NMR (CDCl3) d 338.6 (l-C); 266.8
(l-CO); 213.5 (CO); 148.6 (ipso-Me2C6H3); 132.6, 132.5,
130.3, 129.0, 128.9 (Me2C6H3); 88.0, 87.1 (Cp); 54.0
(NMe); 44.1 (N–C2–CH3); 18.5, 17.8, 17.4
(Me2C6H3 + NCH2–CH3).
(CO). 1H NMR (CDCl3)
d 7.40–7.28 (m, 3H,
Me2C6H3); 5.05, 4.95, 4.41, 4.33 (s, 10H, Cp); 4.91,
4.81 (s, 3H, NMe); 2.76, 2.66, 2.27, 2.15 (s, 6H,
2
C6H3Me2); 2.40 (d, 1H, JHH = 12.1 Hz, NH2); 2.20–
0.82 (m, 11H, C6H11); ꢀ2.18, ꢀ2.22 (d, 1H,
2JHH = 12.1 Hz, NH2); (Isomers ratio = 10). 13C
NMR (CDCl3) d 340.2 (l-C); 267.4, 266.3 (l-CO);
213.8, 212.5 (CO); 148.5 (ipso-Me2C6H3); 132.7, 132.2,
130.2, 128.9 (Me2C6H3); 88.6, 88.0, 86.9, 86.4 (Cp);
55.6, 54.8, 35.6, 31.1, 25.0, 24.7 (C6H11); 53.5, 52.2
(NMe); 18.5, 17.6 (C6H3Me2).
3.3. Synthesis of [Fe{l-CN(Me)R}(l-CO)(CO)(NH2-
Pri)(Cp)2][SO3CF3] (R = Me, 5a; R = Xyl, 5b)
A solution of 1a (180 mg; 0.340 mmol) in THF (15.0
mL) was treated with Me3NO (50 mg; 0.66 mmol) and
NH2Pri (0.300 mL; 3.52 mmol). The mixture was stirred
for 2 h, then the solvent was removed under reduced
pressure. Chromatography of the residue on alumina
with CH3CN as eluent, afforded 5a. Yield 141 mg
(74%). Found: C, 40.87; H, 4.23; N, 5.10%.
C19H25F3Fe2N2O5S requires: C, 40.66; H, 4.49; N,
4.99%. IR (CH2Cl2) mmax (cmꢀ1) 1970vs and 1802s
(CO). 1H NMR (CDCl3) d 4.84, 4.78 (s, 10H, Cp);
7: Yield 79 mg (71%). Found: C, 50.62; H, 4.41; N,
3.98%. C29H29F3Fe2N2O5S requires: C, 50.64; H, 4.25;
N, 4.07%. IR (CH2Cl2) mmax (cmꢀ1) 1965vs and 1808s
1
(CO). H NMR (CDCl3) d 7.27-6.60 (m, 9H, arom);
4.97, 4.73, 4.35, 4.32 (s, 10H, Cp); 4.84 (s, 3H, NMe);
2
4.45 (d, 1H, JHH = 11.4 Hz, NH2); 2.33, 2.10, 1.97 (s,
2
6H, C6 H3Me2); ꢀ0.16 (d, 1H, JHH = 11.4 Hz, NH2);
(Isomers ratio = 10). 13C NMR (CDCl3) d 338.0 (l-C);
265.9 (l-CO); 214.4 (CO); 148.4, 142.8, 132.6, 130.2,
128.9, 125.3, 120.6 (arom); 88.4, 87.3 (Cp); 54.4
(NMe); 18.5, 17.8 (C6H3Me).
2
4.70, 4.24 (s, 6H, NMe2); 2.10 (d, 1H, JHH = 13 Hz,
NH2); 1.74 (m, 1H, CHMe2); 1.30, 0.61 (d, 6H,
2
3JHH = 6.1 Hz, CH(CH32); ꢀ2.36, (d, 1H, JHH = 13
8: Yield 42 mg (42%). Found: C, 45.01; H, 4.32; N,
4.25%. C23H25F3Fe2N2O5S requires: C, 45.27; H, 4.13;
N, 4.59%. IR (CH2Cl2) mmax (cmꢀ1) 1973 vs and 1810s
(CO). 1H NMR (CD3CN) d 7.47–7.33 (m, 3H,
Me2C6H3); 5.16, 5.12, 4.47, 4.35 (s, 10H, Cp); 4.76,
4.44 (s, 3H, NMe); 2.74, 1.91 (s, 6H, Me2C6H3);
ꢀ0.41, ꢀ0.76 (s, 3H, NH3); (Isomers ratio = 3). 13C
NMR (CD3CN) d 339.0 (l-C); 268.9 (l-CO); 214.1
(CO); 149.2 (ipso-Me2C6H3); 135.1, 133.2, 131.1, 130.0,
129.6 (Me2C6H3); 89.7, 87.1 (Cp); 55.7 (NMe); 19.1,
17.8 (Me2C6H3).
Hz, NH2).
Compound 5b was obtained reacting NH2Pri with 1b
(106 mg, 0.170 mmol), with the same procedure de-
scribed for the synthesis of 5a.
5b: Yield 80.1 mg (72%). Found: C, 48.01; H, 4.65; N,
4.30%. C26H31F3Fe2N2O5S requires: C, 47.74; H, 4.78;
N, 4.28%. IR (CH2Cl2) mmax (cmꢀ1) 1968vs and 1805s
(CO). 1H NMR (CDCl3) d 7.35–7.20 (m, 3H, Me2
C6H3); 4.99, 4.95, 4.36, 4.41 (s, 10H, Cp); 4.85, 4.83 (s,
2
3H, NMe); 2.68 (d, 1H, JHH = 12.9 Hz, NH2); 2.73,

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
355
3.5. Synthesis of [Fe2{l-CN(Me)R}(l-CO)(CO)(NHR02)-
(Cp)2][SO3CF 3] (R = R0 = Me, 9a; R = Xyl, R0 = Me,
9b; R = Xyl, NHR02@NHC5H10)
4.74, 4.23 (s, 10H, Cp); 4.45(s, 3H, NMe); 2.83, 2.74
(m, 2H, N–CH2–CH3); 2.59, 2.15 (s, 6H, Me2C6H3);
3
0.77 (t, 3H, JHH = 7.3 Hz, N–CH2–CH3). 13C NMR
(CD2Cl2) d 334.3 (l-C); 274.1 (l-CO); 214.7 (CO);
202.9 (C(O)NHEt); 149.8 (ipso-Me2C6H3); 135.2,
133.8, 130.4, 128.6, 128.4 (Me2C6 H3); 89.0, 86.8 (Cp);
51.3 (NMe); 35.7 (N–C2–CH3); 19.1, 18.0 (Me2C6H3);
15.9 (N–CH2–C3).
Complexes 9–10 have been obtained by reacting
[Fe2{l-CN(Me)R}(l-CO)(CO)2(Cp)2][CF3SO3] (0.200
mmol) with the appropriate secondary amine, in the
presence of Me3NO, using the same procedure described
for the synthesis of 4a.
9a: Yield 77 mg (70%) Found: C, 39.63; H, 4.24;
5.16%. C18H23F3Fe2N2O5S requires: C, 39.50; H, 4.24;
N, 5.12%. IR (CH2 Cl2) mmax (cmꢀ1) 1974vs and 1801s
(CO). 1H NMR (CDCl3) d 4.84, 4.69 (s, 10H, Cp);
4.63, 4.20 (s, 6H, l-CNMe2); 1.90, 0.94 (d, 6H,
3JHH = 5.6 Hz, NMe2,); 1.22 (br, 1H, NH). 13C NMR
(CDCl3) d 331.4 (l-C); 269.1 (l-CO); 214.4 (CO); 88.3,
86.6 (Cp); 53.9, 52.30 (l-CNMe2); 47.0, 43.0 (NMe2).
9b: Yield 92 mg (72%). Found: C, 47.19; H, 4.29; N,
4.54%. C25H29F3Fe2N2O5S requires: C, 47.07; H, 4.58;
N, 4.39%. IR (CH2Cl2) mmax (cmꢀ1) 1971vs and 1803s
(CO). 1H NMR(CDCl3) d 7.47–6.97 (m, 3H, Me2C6H3);
5.04, 4.93, 4.39, 4.31 (s, 10H, Cp); 4.91, 4.87 (s, 3H,
NMe); 2.66, 2.21 (s, 6H, C6H3Me2); 2.18 (d, 3H,
3JHH = 6.9 Hz, NMe2,); 1.24 (br, 1H, NH); 1.09 (d,
3.7. Synthesis of [Fe2{l-CN(Me)R}(l-CO)(CO)(Py)-
(Cp)2][SO3CF3] (Py = NC5H5; R = Me, 12a; R = Xyl,
12b)
Complexes 12a–b have been obtained by reacting
pyridine with [Fe2{l-CN(Me)R}(l-CO)(CO)2 (Cp)2]-
[CF3SO3] (0.200 mmol) following the same procedure
described for the synthesis of 5a–b.
12a: Yield 72 mg (68%). Found: C, 47.40; H, 4.11; N,
5.33%. C21H21F3Fe2N2O5S requires: C, 47.56; H, 3.99;
N, 5.28%. IR (CH2Cl2) mmax (cmꢀ1) 1971vs and 1795s
1
3
(CO). H NMR (CDCl3) d 8.15 (d, 2H, JHH = 5.5 Hz,
3
o-Py); 7.37 (t, 1H, JHH = 7.7 Hz, p-Py); 6.94 (t, 2H,
3JHH = 7.0 Hz, m-Py); 4.96, 4.36 (s, 6H, NMe2); 4.94,
4.70 (s, 10H, Cp). 13C NMR (CDCl3) 332.3 (l-C);
272.7 (l-CO); 210.2 (CO); 155.1 (o-Py); 137.3 (p-Py);
124.8 (m-Py); 88.5, 86.7 (Cp); 54.9, 52.8 (N–Me2).
12b: Yield 97 mg (78%):Found: C, 50.18; H, 3.89; N,
4.25%. C28H27F3Fe2N2O5S requires: C, 50.04; H, 4.05;
N, 4.17%. IR (CH2Cl2) mmax (cmꢀ1) 1975vs and 1795s
3
3H, JHH = 6.2 Hz, NMe2,); (Isomers ratio = 10). 13C
NMR (CDCl3) d 339.3 (l-C); 266.3 (l-CO); 215.4.
(CO);148.3 (ipso-Xyl); 132.9, 132.8, 130.5, 129.2, 129.0
(Me2C6H3); 89.4, 88.3, 87.8 86.7, (Cp); 54.2, 53.4
(NMe); 49.1, 47.3, 46.9, 44.8 (NMe2),18.7, 18.0 (C6
H3Me2).
1
(CO). H NMR (CDCl3) d 8.68–6.85 (m, 18H, arom);
10: Yield 94 mg (69%). Found: C, 49.21; H, 5.02; N,
3.99%. C28H33F3Fe2N2O5S requires: C, 49.44; H, 4.89;
N, 4.12%. IR (CH2Cl2) mmax (cmꢀ1) 1969vs and 1801s
(CO). 1H NMR(CDCl3) d 7.40–7.20 (m, 3H, Me2C6H3);
4.99, 4.94, 4.47, 4.42 (s, 10H, Cp); 4.91 (s, 3H, NMe);
2.63, 2.42, 2.17, 2.08 (s, 6H, C6H3Me2); 2.8–2.6, 1.4–
1.0 (m, 11H, C5H10 + NH); (Isomers ratio = 10). 13C
NMR (CDCl3) d 338.5 (l-C); 267.4 (l-CO); 215.3.
(CO); 148.3 (ipso-Xy); 132.7, 132.3, 130.2, 129.1, 128.9
(Xy); 88.5, 87.9, 87.5, 86.4 (Cp); 54.3 (NMe); 57.4,
54.8, 27.4, 27.1, 22.7 (NH(CH2)5); 18.6, 17.7 (C6H3Me2).
5.18, 4.91, 4.51, 4.36, (s, 10H, Cp); 5.21, 4.44 (s, 3H,
NMe); 2.91, 2.66, 2.17, 1.06 (s, 6H, C6H3Me2); (Isomers
ratio = 2). 13C NMR (CDCl3) 339.1, 334.8 (l-C); 271.7,
270.8 (l-CO); 211.4, 210.5. (CO); 155.8–122.8 (arom);
89.4, 88.7, 87.8, 87.5 (Cp); 56.1, 54.4 (NMe); 29.4 25.4
(C6H3Me2).
3.8. Synthesis of [Fe2{l-CN(Me)R}(l-CO)(CO)(HNC@
CPh2)(Cp)2][SO3CF3] (R = Me, 13a; R=Xyl, 13b)
Complexes 13a–b have been obtained by reacting
benzophenone imine (Ph2C@NH) with [Fe2{l-
CN(Me)R}(l-CO)(CO)2(Cp)2][CF3SO3] (0.300 mmol)
following the same procedure described for the synthesis
of 5a–b.
3.6. Synthesis of [Fe2{l-CN(Me)Xyl}(l-CO)(CO)-
{C(O)NHEt}(Cp)2] (11)
Gaseous NH2Et was bubbled into a stirred solution
of [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO)2(Cp)2][CF3SO3]
(1a) (98 mg, 0.158 mmol) in THF(15 ml). Then, NaH
(18 mg, 0.750 mol) was added and the mixture stirred
for further 10 min. Filtration on a celite pad and re-
moval of thevolatile materials gave a green solid residue
of 11. Yield 75 mg(92%). Found: C, 58.31; H, 5.19; N,
5.51%. C25H28Fe2N2O3 requires: C, 58.14; H, 5.43; N,
5.42%. IR (CH2Cl2) mmax (cmꢀ1) 1962vs, 1756s and
13a: Yield 161 (76%). Found: C, 50.91; H, 4.05; N,
4.21%. C29H27F3Fe2N2O5S requires: C, 50.76; H, 3.97;
N, 4.08%. IR (CH2Cl2) mmax (cmꢀ1) 1974vs and 1803s
1
(CO). H NMR (CDCl3) d 7.68–7.20 (m, 10H, arom);
6.09 (s, 1H, NH); 5.00, 4.52 (s, 10H, Cp); 4.80, 4.43 (s,
6H, NMe2). 13C NMR (CDCl3) d 332.0 (l-C); 267.6
(l-CO); 211.8 (CO); 191.5 (N@C); 137.8-126.4(arom);
88.6, 87.6 (Cp); 54.1, 52.7 (N–Me2).
13b: 182 mg (78%).Found: C, 55.89; H, 4.28; N,
3.85%. C36H33F3Fe2N2O5 S requires: C, 55.71; H,
4.29; N, 3.61%. IR (CH2Cl2) mmax (cmꢀ1) 1978vs and
1
1556s (CO); 3276m (NH) in KBr. H NMR (CD2Cl2)
d 7.46–7.17 (m, 3H, Me2C6H3); 5.74 (s, br, 1H, NH);

356
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
1
Table 3
Crystal data and experimental details for 4a[CF3SO3] and
15 Æ 0.5CH2Cl2
1813s (CO); 3276m (NH) in KBr. H NMR (CDCl3) d
7.73–6.88 (m, 13H, arom); 6.29 (s, 1H, NH); 4.88,
4.54, 4.36, 4.34 (s, 10H, Cp); 4.94, 4.92 (s, 3H, NMe);
2.58, 2.14 (s, 6H, C6H3Me2); (Isomers ratio = 4). 13C
NMR (CDCl3) 340.3 (l-C); 264.7 (l-CO); 212.3. (CO);
192.0 (N@C); 147.9 (ipso-Xyl); 140.0–125.0 (arom);
88.3, 87.8, 87.3, 87.1 (Cp); 54.2, 53.8 (N–Me); 18.4,
17.5 (C6H3Me). ESI MS: ES + m/z 625; ES ꢀ m/z 149.
Complex
4a[CF3SO3]
15 Æ 0.5CH2Cl2
Empirical formula
Formula weight
T (K)
C18H23F3Fe2N2O5S
548.14
293(2)
C44.5H41ClFe2N2O2
782.94
293(2)
˚
k (A)
Crystal system
0.71073
Monoclinic
P21/c
0.71073
Triclinic
ꢀ
Space group
˚
P1
3.9. Synthesis of [Fe2{l-g1: g2-C@C(Tol)C(Ph)2N(H)-
CN(Me)(Xyl)}(l-CO)(CO)(Cp2)] (15)
a (A)
˚
9.2094(18)
13.888(3)
17.363(4)
90
10.350(2)
10.746(2)
17.380(4)
86.55(3)
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
TolC„CLi (0.58 mmol in THF) was added dropwise
to a solution of 1b (148 mg, 0.19 mmol) in THF (10 mL)
at 50 ꢁC and the resulting solution was stirred at room
temperature for 30 min. The solvent, then, was removed
in vacuo and the residue dissolved in CH2Cl2 (5 mL) and
filtered through an Al2O3 pad. Subsequently, the filtrate
was evaporated and washed with petroleum ether (3 · 5
mL). The final product was further purified by chroma-
tography on an Al2O3 column using CH2Cl2 as eluent.
Yield 73.4 mg (52%). Found: C, 71.33; H, 5.15; N,
4.10%. C44H40Fe2N2O2 requires: C, 71.15; H, 5.43; N,
3.79%. IR (CH2Cl2) mmax (cmꢀ1) 1934vs and 1734s
90.07(3)
90
80.57(3)
87.91(3)
3
˚
Cell volume (A )
2220.8(8)
4
1.639
1902.8(7)
2
1.367
Z
Dc (g cmꢀ3
)
l (mmꢀ1
F(0 0 0)
Crystal size (mm)
)
1.457
1120
0.872
814
0.22 · 0.19 · 0.13
1.17–25.02
19659
0.30 · 0.24 · 0.13
1.19–25.03
16614
h limits (ꢁ)
Reflections collected
Independent reflections
Data/restraints/
3917 [Rint = 0.0819]
3917/182/275
6729 [Rint = 0.0526]
6729/16/483
parameters
Goodness on fit on F2
R1 (I > 2r (I))
wR2 (all data)
1.088
0.0808
0.979
0.0469
1
(CO); 3321m (NH) in KBr. H NMR (CD2Cl2) d 8.87
0.2199
0.953/ꢀ0.722
0.1252
0.416/ꢀ0.403
(br, 1H, NH), 7.78–6.55 (m, 17H, 2Ph + Xyl + Tol),
4.51, 4.08 (s, 10H, Cp), 3.94 (s, 3H, NMe), 2.20 (s,
3H, p-MeC6H4), 2.18, 1.82 (s, 6H, C6H3Me2).13C
NMR (CD2Cl2) d 285.8, 280.6 (l-C@C + l-CO), 220.5
(C@Fe), 216.3 (CO), 149.4, 147.6, 146.7, 141.6, 141.0
(ipso-Xyl + ipso-Tol + ipso-2Ph + l-C@C), 136.0, 134.9,
133.2 (C-Me Tol + Xyl), 131.7–126.5 (C–H arom),
87.2, 86.5 (Cp), 78.2 (CPh2), 43.4 (NMe), 21.0 (p-
MeC6H4), 18.1, 17.6 (C6H3Me2). ESI MS: ES + m/z 740.
Largest difference peak
ꢀ3
˚
and hole (e A
)
data are listed in Table 3. Non-H atoms were refined
anisotropically, unless otherwise stated. H-atoms were
placed in calculated positions, except position of the
N-bonded H atom in 15 Æ 0.5CH2Cl2 which was located
in the Fourier map. H-atoms were treated isotropically
using the 1.2-fold Uiso value of the parent atom except
methyl protons, which were assigned the 1.5-fold Uiso
value of the parent C-atom.
3.10. Synthesis of [Fe2{l-g1:g2-C@C(Ph)C(Ph)2N(H)-
CN(Me)(Xyl)}(l-CO)(CO)(Cp2)] (16)
Crystals of 4a are pseudo-merohedrally twinned.
The TWIN routine of SHELX97 was used during the
refinement with the appropriate twin matrix (1 0 0 0
-1 0 0 0 -1), giving a final BASF factor of 0.41156.
The two Cp rings in 4a[CF3SO3] and the molecule of
CH2Cl2 in 15 Æ 0.5CH2 Cl2 are disordered. Disordered
atomic positions were split and refined isotropically
using similar distance and similar U restraints and one
occupancy parameter per disordered group.
Compound16 was obtained following a procedure
similar to that reported for 15, using PhC„ CLi instead
of TolC„CLi. Yield 42.9 mg (31%). Found: C, 71.22;
H, 4.95; N, 3.68%. C43H37Fe2N2O2 requires: C, 70.94;
H, 5.12; N, 3.85%. IR (CH2Cl2) mmax (cmꢀ1) 1936vs
and 1735s (CO); 3321m (NH) in KBr. 1H NMR
(CD2Cl2) d 7.80 (br, 1H, NH), 7.60–6.53 (m, 18H,
3Ph + Xyl), 4.49, 4.08 (s, 10H, Cp), 3.93 (s, 3H, NMe),
2.16, 1.84 (s, 6H, C6H3Me2).
3.11. Crystallography
4. Supplementary material
Crystal data for 4a[CF3SO3] and 15 Æ 0.5CH2Cl2 were
collected at room temperature on a Bruker AXS
SMART 2000 CCD diffractometer using graphite mon-
ochromated Mo Ka radiation. Structures were solved by
direct methods and structures refined by full-matrix
least-squares based on all data using F2 [19]. Crystal
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crytsallographic
Data Centre, CCDC no. 245010 for 4a[CF3SO3] and
245011 for 15 Æ 0.5CH2Cl2. Copies of this information
can be obtained free of charge from the Director,

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 348–357
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