C-H activation of imines by trimethylphosphine-supported iron complexes and their reactivities

Article abstract of DOI:10.1021/om800828j

The activation and functionalization of C-H bonds by solution-phase iron metal based systems are presented with an emphasis on the activation of aromatic C-H bonds. The study reported the synthesis of ortho-metalated mono-iron complexes of monodentate N-d

Full text of DOI:10.1021/om800828j

2300
Organometallics 2009, 28, 2300–2310
C-H Activation of Imines by Trimethylphosphine-Supported Iron
Complexes and Their Reactivities
Sebnem Camadanli,*,† Robert Beck,† Ulrich Flo¨rke,‡ and Hans-Friedrich Klein†
Eduard-Zintl-Institut fu¨r Anorganische and Physikalische Chemie, Technische UniVersita¨t Darmstadt,
Petersenstrasse 18, Darmstadt, 64287, Germany, and Anorganische und Analytische Chemie, UniVersita¨t
Paderborn, Warburger Strasse 100, Paderborn, 33098, Germany
ReceiVed August 25, 2008
Chart 1
Introduction
The direct and catalytic transformation of hydrocarbons to
various useful chemicals via C-H bond activation is of
considerable interest to chemical industries and remains a
challenge to chemists due to the inherent difficulty associated
with breaking such robust bonds.1 The introduction of transition
metals into this area has given new opportunities, and there has
been a massive effort to achieve selective C-H bond activation
by transition metal complexes.2
landmark discovery of highly active bis(imino)pyridine iron
complexes for ethylene polymerization and R-olefin oligomer-
ization reported by Gibson,7 DuPont,8 and Brookhart.9 Iron
dihalide precatalysts are noteworthy in their ability to oligo-
merize R-olefins.10 Besides that, there are some very recently
reported iron catalysts with N-donor functionality, for example,
iron catalyst for the asymmetric hydrogenation of polar bonds
by Morris et al.,11 iron catalysts for olefin hydrogenation by
Chirik et al.,12 and the achiral iron catalyst by Casey and Guan
for ketone and imine hydrogenation.13
Activation of aromatic C-H bonds by ortho-metalation is a
promising example of synthetically applicable catalytic systems.3
In most cases, the direct use of aromatic compounds in synthesis
relies on the presence of a more reactive group C-X (X ) Cl,
Br, I) than a C-H bond.4 This chemistry can be very successful,
but the manufacture of aryl halides is not an environmentally
friendly process. Furthermore, these reactions typically produce
halide salts as byproducts. Therefore, the bulk synthesis of aryl
derivatives proceeding by such C-H bond activation requires
the development of practical catalytic ways to directly activate
C-H bonds of arenes. Iron-based catalysts of comparable
activity would be desirable owing to their potentially lower cost
and lack of toxicity and environmental impact. Despite its
advantages, iron was relatively underrepresented in the field of
catalysis compared to the other transition metals.5 Even though
strong Lewis acid FeCl3-catalyzed Friedel-Crafts reactions of
electron-rich arenes are a well-known process for the formation
of new C-C bonds from aromatic C-H bonds, rearrangements
can occur to produce a more highly substituted product.6 There
are some well-known iron-based catalysts, for example, the
Syntheses with catalytic amounts of ruthenium or rhodium,
preferentially using an N donor as anchoring group in a substrate
molecule, when followed by a coordination of a suitable co-
substrate and elimination of the metal, have become an
indispensable method of C,C-coupling in organic chemistry.14
Surprisingly, exploring the coordination chemistry of the
postulated [N,C]-cyclometalated intermediates has remained a
great challenge to date.15 Using complexes of low-valent iron
(1, 2, and 4) and cobalt, we have recently conducted cyclom-
etalation reactions that mimic the first steps in the proposed
catalytic cycle (Chart 1).16
* To whom correspondence should be addressed. E-mail:
sebnem.camadanli@iom-leipzig.de.
In this paper, the activation and functionalization of C-H
bonds by solution-phase iron metal-based systems are presented,
with an emphasis on the activation of aromatic C-H bonds.
We herein report the synthesis and structural analyses of a series
† Technische Universita¨t Darmstadt.
‡ Universita¨t Paderborn.
(1) (a) Crabtree, R. H. J. Organomet. Chem. 2004, 689, 4083. (b)
Kakiuchi, F.; Chatani, N. AdV. Synth. Catal. 2003, 345, 1077.
(2) (a) Shilov, E.; Shul’pin, G. B. Chem. ReV. 1997, 97, 2879. (b)
Kakiuchi, F.; Murai, S. ActiVation of UnreactiVe Bonds and Organic
Synthesis; Springer: New York, 1999. (c) Dyker, G. Angew. Chem., Int.
Ed. 1999, 38, 1698. (d) Fujiwara, Y.; Takaki, K.; Taniguchi, Y. Synlett
1996, 591. (e) Gupta, M.; Hagen, C.; Kaska, W. C.; Cramer, R. E.; Jensen,
C. M. J. Am. Chem. Soc. 1997, 119, 840. (f) Reis, P. M.; Silva, J. A. L.; da
Silva, J. J. R. F.; Pomberio, A. J. L. Chem. Commun. 2000, 1845.
(3) (a) Murai, S.; Kakiuchi, F.; Sekine, S.; Tanaka, Y.; Kamatani, A.;
Sonoda, M.; Chatani, N. Nature 1993, 366, 529. (b) Lenges, C. P.;
Brookhart, M. J. Am. Chem. Soc. 1999, 121, 6616. (c) Matsumoto, T.;
Taube, D. J.; Periana, R. A.; Taube, H.; Yoshida, H. J. Am. Chem. Soc.
2000, 122, 7414.
(4) (a) Beletskaya, I. P.; Cheprakov, A. V. Chem. ReV. 2000, 100, 3009.
(b) Littke, A. F.; Dai, C.; Fu, G. C. J. Am. Chem. Soc. 2000, 122, 4020.
(5) Bolm, C.; Legros, J.; Le Paih, J.; Zani, L. Chem. ReV. 2004, 104,
6217.
(6) (a) Bandini, M.; Melloni, A.; Umani-Ronchi, A. Angew. Chem., Int.
Ed. 2004, 43, 550. (b) Wang, Z.; Sun, X.; Wu, J. Tetrahedron 2008, 64,
5013.
(7) Britovsek, G. J. P.; Gibson, V. C.; Kimberely, B. S.; Maddox, P. J.;
Solan, G. A.; White, A. J. P.; Williams, D. J. Chem. Commun. 1998, 849.
(8) Bennett, A. M. A. (DuPont) World Patent Application 98/27124,
1998.
(9) Small, B. L; Brookhart, M.; Bennett, A. M. A. J. Am. Chem. Soc.
1998, 102, 4049.
(10) Gibson, V. V.; Spitzmesser, S. K. Chem. ReV. 2003, 103, 283.
(11) Sui-Seng, C.; Freutel, F.; Lough, A. J.; Morris, R. H. Angew. Chem.,
Int. Ed. 2008, 47, 940.
(12) (a) Bart, S. C.; Lobkovsky, E.; Chirik, P. J. J. Am. Chem. Soc.
2004, 126, 13794. (b) Bart, S. C.; Hawrelak, E. J.; Lobkovsky, E.; Chirik,
P. J. Organometallics 2005, 24, 5518.
(13) Casey, C. P.; Guan, H. J. Am. Chem. Soc. 2007, 129, 5816.
(14) Kakiuchi, F.; Murai, S. Acc. Chem. ReV. 2002, 35, 826.
(15) Coalter, J. N., III; Streib, W. E.; Caulton, K. G. Inorg. Chem. 2000,
39, 3749.
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Chem., Int. Ed. 2005, 44, 975.
10.1021/om800828j CCC: $40.75
2009 American Chemical Society
Publication on Web 03/12/2009

C-H ActiVation of Imines by Iron Complexes
Organometallics, Vol. 28, No. 7, 2009 2301
Scheme 1
carbon gives a triplet with a resonance at around 23 ppm, and
the two isochronic trans phosphines appear at 18 ppm as
doublets in both cases.
The molecular structure of 1 shows a slightly distorted
octahedral frame of donor atoms centered by an iron atom that
bears three meridional PMe3 donor groups (Figure 2). C, N,
and H atoms of the metalacycle occupy three remaining ligand
positions. The angle P3-Fe1-P1 ) 152.878(18) Å shows a
significant deviation from 180° because of spatial relaxation.
The ortho-metalated imine ligand acts with a bite angle of
79.0(6)°, and the sum of internal angle for the five-membered
metalacycle (539.90°) approach the ideal value for a planar five-
membered ring (540°). The Fe-P distances are in the typical
range of 2.18-2.22 Å.20 The Fe1-P2 distance is lengthened
due to the trans influence of the carbon donor, while N1-Fe1
and C1-Fe1 distances are also in typical ranges.21 The CdN
bond is lengthened upon coordination from 1.237(3) Å to
1.314(2) Å.22 The Fe1-H1 1.480(19) Å is in the typical range
for molecular iron hydrides.23
of ortho-metalated hydrido-iron and methyl-iron complexes and
their reactivities.
Results and Discussion
1. Reactions of Fe(PMe3)4 with Ketimines, PhRCdNH
(R ) C6H5, C(CH3)3). The M-H bond plays an important role
in organometallic chemistry because metal hydrides can undergo
insertion with a wide variety of unsaturated compounds to give
stable species or reaction intermediates containing M-C
bonds.17 Not only are these synthetically useful, but many of
the catalytic reactions involve hydride insertion as the key step.18
Fe(PMe3)4 upon reaction with ketimines were transformed to
Fe-H complexes under mild reaction conditions.
A view of the molecular geometry of 2 is shown in Figure 3.
The X-ray diffraction study on a single crystal of 2 confirms
the structure proposed in Scheme 1 and shows the same
structural characteristics as 1.
2. Reactions of Fe(CH3)2(PMe3)4 with Diphenylketimine
(Ph2CdNH). The possibility of direct introduction of a new
C-C bond via direct C-H bond transformation is a highly
attractive synthetic strategy in synthesis owing to the ubiquitous
nature of C-H bonds in organic substances, where the range
of substrates is virtually unlimited. The activation of C-H bonds
and the formation of C-C bonds in a single preparative step
combine economy, efficiency, and elegance. The reaction of
diphenylketimine with Fe(CH3)2(PMe3)4 afforded a methyl-
iron(II) complex with a C,C-coupling between an sp2 carbon
of the aromatic backbone and an sp3 carbon of the CH3 fragment
(Scheme 2). The C,C-coupling in this reaction suggests an
unusual reaction pathway. Fe(CH3)2(PMe3)4 reacts first with
diphenylketimine to produce a methyl-iron(II) intermediate by
elimination of methane. C,C-coupling between methyl and
phenyl groups and reductive elimination afford the new aromatic
backbone. The Fe(0) complex in solution reinserts into the ortho
C-H bond of the unsubstituted phenyl ring and forms the
hydrido-Fe(II) complex 3.
Stoichiometric amounts of diphenylketimine and tert-bu-
tylphenylketimine reacted with Fe(PMe3)4 in pentane at -70
°C. During warmup to room temperature, the color of the
mixtures changed from dark brown to violet for 1 and to reddish
violet for 2 (Scheme 1).16
The reaction likely begins with the coordination of the iron
adduct to the nitrogen or CdN bond by substituting one of the
trimethylphosphines, which brings the metal closer to the ortho
C-H bond (Scheme 1). This chelation assistance results in an
easier and highly selective C-H bond cleavage to give the
cyclometalated iron(II) complex.
Compounds 1 and 2 crystallize from pentane at -27 °C as
dark violet prisms. While compound 2 is moderately sensitive,
compound 1 is extremely hygroscopic. Under 1 bar of argon,
the solids decompose at 105-118 °C. IR spectra of the
compounds give evidence for hydrido-iron(II) complexes with
ν(Fe-H) stretching frequencies at 1730 cm-1 for 1 and 1795
cm-1 for 2. ν(N-H) bands are observed with bathochromic
shifts between 45 and 70 cm-1, indicating coordination through
1
the N atom. In H NMR spectra, Fe-H resonances appear at
IR and NMR data support the structure assigned for 3. In
the IR spectrum, the absorption bands at 3279 and 1761 cm-1
,
-16.4 ppm for 1 and -17.5 ppm for 2 as doublets of triplets
due to the coupling of the hydride nucleus with trans- and cis-
disposed trimethylphosphines.19 Both compounds show two sets
of anisochronic PMe3 groups, which indicate that the iron centers
have an octahedral coordination environment made up of three
meridional PMe3 ligands (Figure 1). The presence of the ortho-
metalated imine complexes is also supported by the 13C{1H}
NMR spectra. Compound 1 contains a doublet at 180.2 ppm
(JP,C ) 10.3 Hz) due to a coupling of the imine carbon with
one of the P nuclei and a multiplet at 204.1 ppm assigned to
the metalated aromatic carbon. In compound 2, these resonate
as multiplets at 186.1 ppm (CdN) and 200.1 ppm (Fe-C). The
31P{1H} NMR spectra of the two compounds, which are
temperature invariant, show two sets of PMe3 groups with
couplings of 37 Hz. The PMe3 group trans to the metalated
respectively, represent ν(N-H) and ν(Fe-H) vibrations (Table
1 summarizes the properties of complexes 1-3). In the 1H NMR
spectrum the new CH3 group formed by C,C-coupling appears
as a singlet at 2.21 ppm. The Fe-H group resonates at -17.2
ppm as a doublet of triplets. In 13C{1H} NMR the Ar-CH3
carbon appears as a singlet at 21.1 ppm. The imine carbon atom
resonates at 181.2 ppm as a doublet (3JP,C ) 9.8 Hz), and the
metalated carbon gives a multiplet at 203.1 ppm. In the 31P{1H}
NMR the trans PMe3 groups resonate as a multiplet at 15.7
ppm and PMe3 cis disposed to H appears as a triplet with a
2
coupling constant JP,P of 38.3 Hz. These data support a mer-
octahedral hydrido-Fe(II) complex with three PMe3 ligands and
a coordinated imine backbone.
(20) Fru¨hauf, H.-W.; Wolmersha¨user, G. Chem. Ber. 1982, 115, 1070.
(21) Trovitch, R. J.; Lobkovsky, E.; Chirik, P. J. Inorg. Chem. 2006,
45, 7252.
(22) Archer, A. M.; Bouwkamp, M. W.; Cortez, M. P.; Lobkovsky, E.;
Chirik, P. J. Organometallics 2006, 18, 4269.
(23) (a) Bau, R.; Yuan, H. S. H.; Baker, M. V.; Field, L. Inorg. Chim.
Acta 1986, 114, L27. (b) Baker, M. V.; Field, L. Appl. Organomet. Chem.
1990, 4 (5), 543.
(17) Dedieu, A. Transition Metal Hydrides; VCH: New York, 1992.
(18) (a) Masters, C. Homogenous Catalysis; Chapman Hall: London,
1981. (b) Parshall, G. W. Homogenous Catalysis, Wiley-Interscience: New
York, 1980. (c) Jordan, R. B. Reaction Mechanisms of Inorganic and
Organometallic Systems; Oxford University Press: Oxford, 1991.
(19) Allen, R. O.; Dalgarno, S. J.; Field, L. D. Organometallics 2008,
27, 3328.

2302 Organometallics, Vol. 28, No. 7, 2009
Camadanli et al.
1
Figure 1. H NMR spectra of 2 (500 MHz, d8-THF, 300 K).
Figure 2. Molecular structure of 1 (ORTEP plot with hydrogen
atoms, FeH position indicated).
Figure 3. Molecular structure of 2 (ORTEP plot with hydrogen
atoms omitted, FeH position indicated).
X-ray diffraction analysis of 3 indicates that the imine reactant
binds to iron through the N1 and C1 atoms and forms a five-
membered metallacycle with a bite angle N1-Fe1-C1 of
79.52(6)° (Figure 4). The sum of internal angles is that of a
planar five-membered ring. An octahedral coordination is formed
by three PMe3 ligands in meridional positions and is completed
by a hydride ligand in calculated position trans to nitrogen. Two
trimethylphosphine groups are in opposite positions, P2-Fe1-P3
) 149.64(2)°, and one trimethylphosphine group is cis to
nitrogen, N1-Fe1-P1 ) 87.25(4)°. The most striking feature
in the molecular structure of 3 is the methyl substituent (C14)
attached to the non-metalated phenyl ring. Table 2 summarizes
the structural properties of complexes 1-3.
Because of strong trans influence of the aromatic sp2 carbon,
the Fe-P bond length, which is trans to the metalated carbon,
is clearly longer than the other Fe-P distances in all three
structures. They all attain a distorted octahedral geometry, and

C-H ActiVation of Imines by Iron Complexes
Organometallics, Vol. 28, No. 7, 2009 2303
Scheme 2
Figure 4. Molecular structure of 3 (ORTEP plot with hydrogen
atoms omitted).
Scheme 3
Table 1. Properties of Fe-H Metalacycles 1-3
yield [%]
color
dec [°C]
ν˜ [cm-1
]
1
2
3
78
48
74
violet
violet
violet
<105
<118
<104
3281 (N-H), 1730 (Fe-H)
3335 (N-H), 1795 (Fe-H)
3279 (N-H), 1761 (Fe-H)
Table 2. Selected Bond Lengths and Angles of Hydrido-Fe(II)
Complexes 1-3
Benzylic imines (N-methyl-, N-isopropyl-, and N-phenylben-
zylidenimines) reacted with Fe(CH3)2(PMe3)4 in pentane at -70
°C through the elimination of methane to afford the hexacoor-
dinate iron(II) complexes 4-6 (Scheme 3).
1
2
3
Bond Lengths [Å]
Fe-C1
Fe-N1
N1-C7
Fe-P1
Fe-P2
Fe-P3
1.9860(15)
1.9434(13)
1.314(2)
1.9660(2)
1.9316(19)
1.297(3)
1.9820(17)
1.9438(14)
1.306(2)
2.1784(5)
2.2180(5)
2.1751(5)
While violet solutions of 4 and 5 in pentane deposited violet
crystals at -27 °C, petroleum green crystals of 6 deposited at
4 °C. The solids have moderate air-sensitivity and under argon
decompose at 115, 116, and 119 °C, respectively. Elemental
compositions are consistent with loss of methane and one of
the trimethylphosphine groups during the reaction. The infrared
spectrum of each compound exhibits an ν(CdN) absorption of
the coordinated imine ligand (R ) CH3, 1572 cm-1 (m); R )
CH(CH3)2, 1519 cm-1 (m); R ) C6H5, 1543 cm-1 (w)), which
occurs at significantly lower energies than the free imine CdN
stretching absorptions, e.g., ν(CdN) at 1651 cm-1 in free
PhCHNMe. In all three spectra, δ (Fe-CH3) absorptions appears
at 1180 cm-1 (4); 1162 cm-1 (5); and 1193, 1170 cm-1 (6),
although intensities are weak.
2.1874(5)
2.2146(5)
2.1803(5)
2.1739(5)
2.2146(5)
2.1739(5)
Bond Angles [deg]
C1-Fe-N1
C1-Fe-P1
C1-Fe-P2
C1-Fe-P3
P1-Fe-P3
N1-Fe-P1
N1-Fe-P2
N1-Fe-P3
79.60(6)
78.93(9)
79.52(6)
88.23(5)
166.77(5)
87.04(5)
149.64(2)
105.75(5)
87.25(4)
102.82(5)
87.08(4)
86.71(2)
167.36(5)
87.59(4)
168.96(7)
86.71(2)
152.878(18)
102.13(4)
87.76(4)
153.16(3)
102.105(17)
90.03(6)
103.01(4)
102.105(17)
the iron atom is part of a five-membered metalacycle of a
chelating imine ligand.
The solid state characterization of 4 as an ortho-metalated
imine complex is derived from an X-ray diffraction experiment
on a single crystal (Figure 5). The coordination geometry around
the iron atom is octahedral with two P-donor atoms occupying
trans positions (P1-Fe1-P3 ) 168.05(4)°) along the normal
of a plane that is defined by the atoms C2 and N1 of the ortho-
metalatedN-methylbenzylideneimine(N1-Fe1-C2)80.36(13)°),
forming a five-membered ring with the iron atom, the P2 atom
of the trimethylphosphine group disposed trans to C2 (C2-
Fe1-P2 ) 176.99(10)°), and the CH3 ligand located in a
positionoppositethenitrogenatom(N1-Fe1-C1)169.89(13)°).
The Fe1-N1 bond length of 2.016(3) Å, Fe1-C1 bond length
3. Reactions of Fe(CH3)2(PMe3)4 with Benzylic Imines,
PhCHdNR (R ) CH3, CH(CH3)2, C6H5). Cyclometalation
reactions of simple imines (R2CdNR) with basic iron com-
pounds have not been described to date, although such reactions
have been carried out with other transition metal complexes
and have drawn much attention.24 Their particular activity is
well-known from the palladium N-isopropylbenzylidenimine
catalyst for the Suzuki reaction, which catalyzes the coupling
of aryl bromides and phenylboronic acid with extremely high
efficieny.25
of 2.088(3) Å, and Fe1-C2 bond distance of 1.987(3) Å are
(24) (a) Fryzuk, M. D.; Piers, W. E. Organometallics 1990, 9, 986. (b)
Martin, G. C.; Boncella, J. M. Organometallics 1989, 8, 2968. (c) Lopez,
O.; Crespo, M.; Font-Bardia, M.; Solans, X. Organometallics 1997, 16,
1233. (d) Knight, D. A.; Dewey, M. A.; Stark, G. A.; Bennett, B. K.; Arif,
M. A.; Gladysz, J. A. Organometallics 1993, 12, 4523. (e) Faller, J. W.;
Ma, Y.; Smart, C. J.; DiVerdi, M. J. J. Organomet. Chem. 1991, 420, 237.
(f) Makioka, Y.; Taniguchi, Y.; Fujiwara, Y.; Takaki, K.; Hou, Z.;
Wakatsuki, Y. Organometallics 1996, 15, 5476. (g) Cross, R. J.; Davidson,
M. F.; Rocamora, M. J. Chem. Soc., Dalton Trans. 1988, 1147.
27
typical for Fe-N,26 Fe-Calkyl
,
and Fe-Caryl single bonds.28
(26) Bart, S. C.; Bowman, A. C.; Lobkovsky, E.; Chirik, P. J. J. Am.
Chem. Soc. 2007, 129, 7212.
(27) Bouwkamp, M. W.; Bart, S. C.; Hawrelak, E. J.; Trovitch, R. J.;
Lobkovsky, E.; Chirik, P. J. Chem. Commun. 2005, 3406.
(28) Imhof, W.; Goebel, A.; Schweda, L.; Goerls, H. Polyhedron 2005,
18, 3082.
(25) Weissman, H.; Milstein, D. Chem. Commun. 1999, 1901.

2304 Organometallics, Vol. 28, No. 7, 2009
Camadanli et al.
Table 3. Selected Bond Lengths and Angles of Methyl-Fe(II)
Complexes 4 and 6
4
6
Bond Angles [deg]
1.987(3)
Fe-C(sp3)
Fe-C(sp2)
N1-C8
Fe-N1
2.0182(15)
2.0974(17)
1.317(2)
2.0128(13)
2.2954(5)
2.2500(5)
2.2369(5)
2.088(3)
1.289(5)
2.016(3)
2.2574(10)
2.2039(11)
2.2242(11)
Fe-P1
Fe-P2
Fe-P3
Bond Lengths [Å]
80.36(13)
C(sp2)-Fe-N1
C(sp3)-Fe-N1
N1-Fe-Pax
80.11(6)
175.05(6)
94.67(4)
93.38(4)
175.15(4)
161.468(18)
169.89(13)
93.76(9)
94.51(9)
176.99(10)
168.05(4)
N1-Fe-Pax
C(sp2)-Fe-Ptrans
Ptrans-Fe-P
Scheme 4
Figure 5. Molecular structure of 4 (ORTEP plot with hydrogen
atoms).
1.4436(19) and 1.438(2) Å are both marginally shorter than the
corresponding bond lengths of 1.460(3) and 1.496(3) Å in the
free imine. The Fe-N (2.0128(13) Å), Fe-C(sp2) (2.0182(15)
Å), and Fe-P distances fall within the literature range and are
comparable with compounds 1-4.30 Table 3 presents selected
bond lengths and angles of 4 and 6.
Similar to the hyrido-iron(II) complexes, the reaction is
believed to begin with coordination of the iron adduct to the
nitrogen or π-bond by substitution of one trimethylphosphine,
bringing the metal closer to the ortho C-H bond. This chelation
assistance facilitates highly selective C-H bond cleavage to
give a cyclometalated iron(IV) intermediate. Reductive elimina-
tion of CH4 results in an ortho-metalated methyl-iron(II)
complex with three trimethylphosphine ligands that is coordi-
natively saturated, like other alkyl complexes of iron(II)
containing Cp and CO ligands.31 It is the existence of several
decomposition pathways that makes many transition metal alkyls
unstable. The lack of a ꢀ-decomposition pathway due to a Fe-
CH3 group, a blocking imine ligand, and a PMe3 ligand are in
favor of stable compounds 4-6. The principles governing their
stability make a useful starting point in order to understand some
of the most important organometallic reactions.
4. Iodomethane Reactions of Hydrido-Iron(II) Complexes.
The hydrido-iron(II) complexes 1-3 are good candidates for
oxidative addition reactions. Potential ligands that do not have
a lone pair or filled π-type orbitals are still able to interact with
transition metal complexes by breaking a σ-bond. Using
iodomethane as a substrate, the interesting question arises as to
whether attack by the metal would proceed as a regioselective
addition or promote ring opening through a subsequent reductive
C,C-coupling reaction. Reactions of 1-3 in pentane proceed
as described in Scheme 4.
Figure 6. Molecular structure of 6 (ORTEP plot with hydrogen
atoms).
The Fe-P distances are in the range 2.20-2.26 Å and are in
agreement with the values previously found in complexes 1-3.
In complex 6, the configuration about the iron atom is close
to octahedral; the principal distortions are related to the angle
of 80.11(6)° subtended by the chelating atoms and to a bending
along the P2-Fe-P3 positions (Figure 6). The chelate ligand
coordinates via Fe-N and M-C σ-bonds in an ortho position
of the benzylidene phenyl ring that is analogous to compound
5. At variance with the methyl-iron(II) intermediate of com-
pound 3 (Scheme 2), no reductive C,C-coupling is observed in
the formation of compound 6. On the whole, the configuration
of the coordinated imine ligand closely resembles that of free
benzylideneimines.29 The aniline phenyl ring is rotated by 61.2°
away from the imine plane in the complex; the corresponding
twist in the free ligand is 55°. The other phenyl ring is coplanar
with the imine group, forming a dihedral angle of 3.0° with the
imine plane, as compared to a value of 10° in the free imine.
The CdN bond is lengthened upon coordination from 1.237(3)
Å to 1.317(2) Å. The N1-C9 and C7-C8 distances of
When iodomethane is added to the hydrido-iron(II) complexes
at -70 °C, evolution of gas is observed during warmup.
Compounds 7-9 crystallize from pentane at 4 °C. IR spectra
(30) Carthy, A. J.; Mott, G. N.; Taylor, N. J. J. Organomet. Chem. 1979,
182, C69.
(31) Kerber, R. C. ComprehensiVe Organometallic Chemistry II; Per-
gamon, Vol. 7, 1995.
(29) Burgi, H. B.; Dunitz, J. D. HelV. Chim. Acta 1970, 53, 1747.

C-H ActiVation of Imines by Iron Complexes
Organometallics, Vol. 28, No. 7, 2009 2305
Scheme 5
Scheme 6
tion environment, may be an active catalyst for C-C and C-H
bond forming reactions.35
5. Iodomethane Reactions of Methyl-Iron(II) Complexes.
Similar to the hydrido-iron(II) compounds 1-3, methyl-iron
compounds 4 and 5 react with iodomethane to produce iodo-
iron(II) compounds 10 and 11 (Scheme 5).
Figure 7. Molecular structure of 7 (ORTEP plot with hydrogen
atoms).
give a first clue to the structures of 7-9. Strong stretching
vibrations of Fe-H over 1700 cm-1 are absent, and there is a
Pink crystals of 10 and light violet crystals of 11 are obtained
from pentane at 4 °C. Elemental analysis shows the expected
decrease in carbon and hydrogen contents. Thermal stabilities
of the solids are improved, as 10 melts at 142 °C and 11
decomposes at 145 °C. IR spectra of 10 and 11 show the absence
of characteristic deformation bands (δs Fe-CH3) of methyl-
iron(II) complexes 4 and 5. In the 1H NMR spectra, resonances
at 1.14 ppm as a singlet in 10 and at 0.84 ppm as a pseudotriplet
1
bathochromic shift in all characteristic bands. In the H NMR
spectra, there is no Fe-H resonance at high field and trimeth-
ylphosphine resonances are shifted to low field. We can see
more clearly the metalated carbons in lower field than in the
hydrido-iron(II) compounds. The observed patterns in the
31P{1H} NMR spectra are consistent with a meridional arrange-
ment of the three trimethylphoshines. On the basis of chemical
shifts, the electron density at the iron nucleus is subject to the
σ-electron-withdrawing power of the halides.32
4
(|2JP,H + JP,H| ) 5.9 Hz) in 11 are assigned to the trimeth-
ylphosphine ligands in mutual trans positions. Cis-arranged
trimethylphosphines resonate at 1.56 ppm as a singlet in 10 and
at 1.50 ppm as a doublet (2JP,H ) 6.4 Hz) in 11. Aromatic
protons typically appear at 6.7-7.7 ppm. In the 13C{1H} NMR
metalated carbon nuclei resonate at 212.7 and 199.7 ppm,
respectively. 31P{1H} NMR resonances of 10 and 11 confirm
the suggested structures in Scheme 6. Two phosphorus nuclei
appear as a doublet at 5.8 ppm (2JP,P ) 54.3 Hz, complex 10)
and 28.3 ppm (2JP,P ) 28.3 Hz, complex 11), while the singular
phosphorus nuclei form triplets at 14.9 ppm (2JP,P ) 54.3 Hz,
complex 10) and 21.8 ppm (2JP,P ) 28.3 Hz, complex 11). This
pattern is consistent with a mer-octahedral coordination geometry.
An X-ray structural determination was performed on a single
crystal of compound 10 grown from pentane (Figure 8). The
Fe1-C1 and Fe1-N1 bond lengths (1.949(4) and 2.027(5) Å)
fall in the range of values found in the related complexes 7 and
8. The Fe1-I1 bond length of 2.7974(8) Å lies above the
literature value (e.g., the Fe-I distance of 2.61(3) Å in the
cis,trans-Fe(CO)2(PMe3)2(p-C6H5)I complex synthesized by
Cardaci) because of the strong trans influence of the carbon
atom.36 The acute angle C1-Fe1-N1 (81.2(2)°) reflects the
big bite of the N-methylbenzylideneimine ligand. The sum of
the cis angles involving Fe and the atoms C1, N1, I1, and P2
(the equatorial plane) is 359.77°, and the sum of the internal
angles in the five-membered metallacycle is 539.80°, consistent
with planarity.
A molecule of the compound 7 is depicted in Figure 7. In an
octahedral geometry, a meridional arrangement of the three
trimethylphosphines is recognized. The remaining three coor-
dination sites are occupied by an iodide and a chelating imine
ligand. The iodide and one trimethylphosphine P-donor are
almost coplanar with the metalacycle, forming an angle
P2-Fe1-I1 of 97.87(3)°. Because of its weak trans influence,
the iodide is coordinated trans to the metalated carbon
(C1-Fe1-I1 166.44(9)°) and the Fe1-C1 distance is 0.029 Å
smaller than Fe1-C1 in compound 1. Complex 7 is less
distorted than 1 because the iodo ligand restricts the flexibility
of the trimethylphosphine groups. The Fe1-I1 distance (2.7616(5)
Å) agrees with the Fe1-I1 distance (2.6646 Å) in the ortho-
metalated octahedral Fe(II) compound Fe(CO)2{P(OPh)3}-
{(PhO)2POC6H4}(I).33 The two mutually trans trimethylphos-
phine groups have long Fe-P distances (mean 2.25 Å) compared
with the one that is trans to the N atom (Fe-P ) 2.2350(9) Å)
due to a sizable trans influence of trialkylphosphines. All bond
lengths are well matched with the other structural features.34
The resulting iodo-iron(II) complexes are interesting as
versatile nucleophiles with applications in organometallic and
organic synthesis. The independent reports by Brookhart and
Gibson using five-coordinate Fe(II) dihalide complexes as
precatalysts for the polymerization of ethylene and R-olefins
suggest the idea that iron(II), when in an appropriate coordina-
(35) (a) Small, B. L.; Brookhart, M. Macromolecules 1999, 32, 2120.
(b) Britovsek, G. J. P.; Mastroianni, S.; Solan, G. A.; Baugh, S. P. D.;
Redshaw, C.; Gibson, V. C.; White, A. J. P.; Williams, D. J.; Elsegood,
M. R. J. Chem.-Eur. J. 2000, 6, 2221. (c) Britovsek, G. J. P.; Gibson,
V. C.; Mastroianni, S.; Oakes, D. C. H.; Redshaw, C.; Solan, G. A.; White,
A. J. P.; Williams, D. J. Eur. J. Inorg. Chem. 2001, 431.
(32) Fagnon, K.; Lautens, M. Angew. Chem., Int. Ed. 2002, 41, 26.
(33) Manning, A. R.; Cunningham, D.; Gallagher, J. F. Inorg. Chim.
Acta 2002, 327, 98.
(34) (a) Vela, J.; Vaddadi, S.; Cundari, T. R.; Smith, J. M.; Gregory,
E. A.; Lachicotte, R. J.; Flaschenriem, C. J.; Holland, P. L. Organometallics
2004, 23, 5226. (b) Feiken, N.; Schreuder, P.; Siebenlist, R.; Fru¨hauf, H.-
W.; Vrieze, K. Organometallics 1996, 15, 2148.
(36) Bellachioma, G.; Cardaci, G.; Macchioni, A.; Reichenbach, G.;
Foresti, E.; Sabatino, P. J. Organomet. Chem. 1997, 531, 227.

2306 Organometallics, Vol. 28, No. 7, 2009
Camadanli et al.
Figure 8. Molecular structure of 10 (ORTEP plot with hydrogen
atoms).
Figure 9. Molecular structure of 14. Selected bond lengths (Å)
and angles (deg): Fe1-C1 2.095(3), Fe1-C2 1.714(3), C2-O1
1.159(4), Fe1-C3 1.971(3), N1-C9 1.303(3), Fe1-N1 2.080(2),
Fe1-P1 2.2257(9), Fe1-P2 2.2231(8); C3-Fe1-N1 80.71(10),
N1-Fe1-C2 176.95(14), Fe1-C2-O1 178.2(4), C3-Fe1-C1
174.19(11),P2-Fe1-P1177.29(3),N1-Fe1-P291.36(6),C3-Fe1-P1
89.26(8),C1-Fe1-C287.87(15),C1-Fe1-P186.60(10),C1-Fe1-P2
95.87(10), C2-Fe1-P1 90.47(10), C2-Fe1-P2 88.52(10).
Table 4. Selected Bond Lengths and Angles of Iodo-Fe(II)
Complexes 7 and 10
7
10
Bond Lengths [Å]
1.957(3)
Fe-C1
Fe-N1
Fe-I
N1-C7
Fe-P1
Fe-P2
Fe-P3
1.949(4)
2.027(5)
2.7974(8)
1.294(7)
2.2629(15)
2.246(3)
1.940(2)
2.7616(5)
1.294(4)
2.2587(9)
2.2350(9)
2.2568(9)
bands are observed at 1153, 1151, and 1193 cm-1 for 12-14,
respectively. In contrast to their parent methyl complexes, 13
and 14 do not easily decompose in deuterated solvents. So the
spectroscopic characterization of 13 gives the structure solution
2.2490(15)
1
Bond Angles [deg]
80.05(12)
of 5. In the H NMR spectra metal-coordinated CH3 groups
show triplets at -0.67 ppm (3JP,H ) 6.8 Hz for 12), -0.59 ppm
(3JP,H ) 7.3 Hz for 13), and -0.71 ppm (3JP,H ) 8.1 Hz for
14). For compound 14, we can observe the expected pseudo-
triplet at 0.93 ppm (|2JP,H + 4JP,H| ) 4.7 Hz), while PMe3 groups
in trans positions appear as broad singlets around 0.9 ppm for
12 and 13. The 31P{1H} NMR spectra display singlets for trans-
trimethylphosphine groups. The carbonyl region of the 13C{1H}
NMR spectra of 13 and 14 comprises triplet resonances
consistent with CO groups coupled to two equivalent P nuclei.
The ORTEP drawing of the molecular structure of 14 is
shown in Figure 9. The slight distortions from octahedral
geometry may be illustrated by angles for some trans arrange-
ments: P2-Fe1-P1 177.29(3)°, N1-Fe1-C2 176.95(14)°,
C3-Fe1-C1 174.19(11)°. The main feature of this structure is
the five-membered metallacycle derived from ortho-metalation
of the imine ligand, and the bite angle N1-Fe1-C3 is
80.71(10)°. The constrained bite angle of the chelate ligand is
considered to be the ultimate source of the distortions from
octahedral geometry exhibited by 14. The Fe-CH3, Fe-CO,
and C2-O1 bond lengths (2.095(3), 1.714(3), and 1.159(4) Å,
respectively) are in literature ranges as compared with isoelec-
tronic benzoyl acetones.37
C1-Fe-N1
C1-Fe-I
N1-Fe-P2
P1-Fe-P3
81.2(2)
166.44(9)
175.24(9)
172.52(4)
171.94(15)
175.22(13)
175.33(6)
In order to detect the iron(IV) intermediate, the stoichiometric
ratios and conditions were modified but resulted in the same
products with lower yields. Instead of methane loss, products
of oxidative addition reductively eliminate ethane. Like com-
pounds 7-9, complexes 10 and 11 form thermally stable solids.
In contrast to its parent complex, 10 does not decompose in
deuterated solvents, and full characterization of its structure
confirms that of 5, also. Table 4 summarizes the crystallographic
data of 7 and 10.
6. Carbon Monoxide Reactions of Methyl-Iron(II) Com-
plexes. Since aromatic imines catalytically react with CO and/
or olefins in the presence of Ru3(CO)12 to form new C-C bonds
regioselectively in the ortho position with respect to the imine
substituent, the reaction of the ortho-metalated Fe(II) complexes
with CO might well serve as model reactions for the initial steps
of catalytic C-C bond formation. Under 1 bar of CO, methyl-
iron(II) compounds 4-6 in pentane solution form the mono-
carbonyl complexes 12-14 (Scheme 6). Carbon monoxide
substitutes one of the trimethylphosphines, selectively occupying
the ligand position opposite the nitrogen atom of the imine
group.
12 and 13 form dark pink crystals, and 14 forms light green
crystals. When compared with parent methyl-trimethylphosphine
complexes, they show increased thermal stability but decompose
at 134, 135, and 138 °C, respectively. Elemental analysis
confirms the substitution of a trimethylphosphine group by a
carbon monoxide ligand. The complexes 12-14 exhibit very
strong terminal CO stretching bands at 1869, 1879, and 1870
cm-1, which are at lower energies, reflecting strong back-
bonding and weaker C-O bonds. Fe-CH3 stretching absorption
Carbon monoxide reactions of methyl-iron complexes 4-6
afforded monocarbonyl derivatives.38 Possible insertion reactions
of CO into metal-carbon or metal-methyl bonds were not
observed. The substitution of one trimethylphosphine ligand and
the coordination of the CO stabilize the complexes. 13 and 14
(37) Cravero, R. M.; Gonzalez-Sierra, M.; Oliveri, A. C. J. Chem. Soc.,
Perkin Trans. 2 1993, 1067.
(38) (a) Chen, Z.; Schmalle, H. W.; Fox, T.; Berke, H. Dalton Trans.
2005, 580. (b) Liang, F.; Jacobsen, H.; Schmalle, H. W.; Fox, T.; Berke,
H. Organometallics 2000, 19, 1950. (c) Ho¨ck, J.; Jacobsen, H.; Schmalle,
H. W.; Artus, G. R. J.; Fox, T.; Amor, J. I.; Ba¨th, F.; Berke, H.
Organometallics 2001, 20, 1533.

C-H ActiVation of Imines by Iron Complexes
Organometallics, Vol. 28, No. 7, 2009 2307
General Procedure for the Preparation of Iron Complexes.
Fe(PMe3)4 or Fe(CH3)2(PMe3)4 in pentane solution was combined
with stoichiometric amounts of ligands (imines) at -70 °C. The
mixture was warmed to 20 °C and kept stirring for 16 h. The
volatiles were then removed in vacuo, and the residue was extracted
with pentane. Combined solutions were cooled to afford crystalline
material.
do not decompose in deuterated solvents, and their melting
points lie above those of their parent complexes. Full charac-
terization of their structure supports the molecular structure of
5 derived from NMR spectroscopic data.
Summary
SynthesisofHydrido[2-[(imino-KN)phenylmethyl]phenyl-KC]tris-
(trimethylphosphine)iron(II) (1). Fe(PMe3)4 (1.44 g, 3.99 mmol)
in pentane was combined with 0.72 g (3.99 mmol) of diphe-
nylketimine to afford violet crystals of 1, which crystallize in
pentane at -27 °C. Yield: 1.451 g (78%). Mp: 105-107 °C. Anal.
Calcd for C22H38FeNP3: C, 56.79; H, 8.23; N, 3.01; P, 19.79. Found:
C, 57,06; H, 7.58; N, 2.96; P, 20.09. IR (Nujol, cm-1): 3281 w (ν
H-NdC); 3068 vw, 3043 vw, 3020 w (ν H-CdC); 1730 vs (ν
Fe-H); 1598 m, 1567 m (ν CdC); 1500 m (ν CdN); 1449 vw;
1427 m (δas PCH3); 1392 s; 1293 m, 1273 s (δs PCH3); 1229 w;
1191 vw; 1176 vw; 1143 m; 1099 vw; 1072 vw; 1028 w; 1010
vw; 994 w; 936 vs (F1 PCH3); 849 s (F2 PCH3); 834 vw; 812 m;
777 s, 758 w, 737 vw, 729 m (γ C-Harom); 709 vw, 698 s (νas
PC3); 657 s (νs PC3); 622 vw; 587 s; 512 m (ν Fe-C); 463 w,
Using a C-H bond activation strategy, we have synthesized
the first examples of ortho-metalated mono-iron complexes of
monodentate N-donor functional ligands. Treatment of ben-
zylicimines and ketimines with Fe(CH3)2(PMe3)4 and Fe(PMe3)4
under mild conditions results in ortho-metalated hydrido-iron(II)
and methyl-iron(II) complexes in high yields. Besides C-H
activation, the reaction of diphenylketimine with Fe(CH3)2-
(PMe3)4 presented a noteworthy hydrido-iron(II) complex with
a C,C-coupling between an sp2 carbon of the aromatic backbone
and an sp3 carbon of the CH3 fragment. Iodomethane reactions
of hydrido-iron(II) and methyl-iron(II) compounds give ther-
mally stable iodo-iron(II) compounds, which are interesting
versatile nucleophiles in organometallic and organic chemistry.
Carbon monoxide reactions of methyl-iron complexes afford
monocarbonyl derivatives, where possible insertion reactions
of CO into the Fe-C or Fe-CH3 bonds were not observed.
1
2
433 m. H NMR (d8-THF, 300 K, ppm): -16.4 (dt, JP,H ) 22.8
2
Hz, JP,H ) 81.3 Hz, 1H, Fe-H); 0.94 (s, 18H, PCH3); 1.42 (d,
3
2JP,H ) 4.7 Hz, 9H, PCH3); 6.72 (t, JH,H ) 7.0 Hz, 1H, Ar-H);
3
3
6.82 (t, JH,H ) 7.1 Hz, 1H, Ar-H); 7.30 (t, JH,H ) 7.1 Hz, 1H,
3
3
Ar-H); 7.38 (t, JH,H ) 7.2 Hz, 2H, Ar-H); 7.47 (t, JH,H ) 7.8
Experimental Section
Hz, 3H, Ar-H); 7.89 (d, 3JH,H ) 6.4 Hz, 1H, Ar-H); 9.40 (s, 1H,
N-H). 13C{1H} NMR (d8-THF, 300 K, ppm): 22.5 (dt′, |1JP,C
+
General Remarks. All air-sensitive and volatile materials were
handled using standard vacuum techniques.39 Syntheses, transport,
and storages of chemicals were done under an atmosphere of
purified argon (BTS-Catalyst).40 Solvents were dried according to
known procedures and freshly distilled prior to use. All reagents
were used as purchased (Aldrich, Acros, Alfa Aesar) without further
purification. Literature methods were applied for the preparation
of [Fe(PMe3)4],41 [Fe(CH3)2(PMe3)4],42 and tert-butylphe-
nylketimine.43 Trimethylphosphine was synthesized in diethyl ether
from methylmagnesium chloride and triphenylphosphite according
to a modified procedure given by Wolfsberger and Schmidbaur,
which allows a convenient synthesis in yields from 85 to 92%.44
Air-sensitive samples were provided in capillaries sealed under
vacuum and were analyzed by H. Kolbe Microanalytical Laboratory,
Mu¨lheim/Ruhr, FRG. C, H, N analytical identification of air-stable
substances was performed in the microanalysis laboratory of
Clemens-Scho¨pf-Institut for Organic Chemistry and Biochemistry
at TU-Darmstadt using Perkin-Elmer CHN 240 A and CHN 240 B
devices. The melting and decomposition points were measured on
a Bu¨chi 510 melting point apparatus and are uncorrected. Air-
sensitive substances were sealed in capillaries under 1 bar of argon.
IR spectra were obtained as Nujol mulls between KBr plates
using a Bruker FRA 106 spectrophotometer and recorded in the
3JP,C| ) 12.1 Hz, 3JP,C ) 3.2 Hz, PCH3); 22.3 (td, 1JP,C ) 13.7 Hz,
3JP,C ) 2.3 Hz, PCH3); 118.6 (s, CH); 123.0 (d, JP,C ) 1.7 Hz,
4
CH); 125.9 (s, CH); 127.9 (s, CH); 128.1 (s, CH); 129.4 (s, CH);
3
142.1 (s, C); 146 (s, C); 152.3 (s, CH); 180.2 (d, JP,C ) 10.3 Hz,
CdN); 204.1 (m, Fe-C). 31P{1H} NMR (d8-THF, 296 K, ppm):
2
2
18.2 (d, JP,P ) 37.4 Hz, 2P, PCH3), 22.5 (t, JP,P ) 37.4 Hz, 1P,
PCH3).
Synthesis of Hydrido[2-[(imino-KN)phenylmethyl]-1,1-dimeth-
ylethyl-KC]tris (trimethylphosphine)iron(II) (2). Fe(PMe3)4 (1.27
g, 3.53 mmol) in pentane was combined with 0.57 g (3.53 mmol)
of tert-butylphenylketimine to afford reddish-violet crystals of 2,
which crystallize at 4 °C. Yield: 0.753 g (48%). Mp: 118-120 °C.
Anal. Calcd for C20H42FeNP3: C, 53.94; H, 9.51; N, 3.15; P, 20.87.
Found: C, 53,89; H, 9.35; N, 3.61; P, 19.03. IR (Nujol, cm-1):
3335 m (ν H-NdC); 3060 m, 3026 m (ν H-CdC); 1795 mbr (ν
Fe-H); 1565 m (ν CdC); 1433 s (δas PCH3); 1389 s; 1357 m;
1293 m, 1270 s (δs PCH3); 1194 w; 1173 w; 1149 w; 999 vw; 940
vs (F1 PCH3); 852 m, 843 m (F2 PCH3); 813 w; 770 w, 730 s (γ
C-Harom); 698 m (νas PC3); 656 s (νs PC3); 618 vw; 506 vw; 409 s.
1H NMR (d8-THF, 300 K, ppm): -17.5 (dt, 2JP,H ) 21.8 Hz, 2JP,H
2
) 80.0 Hz, 1H, Fe-H); 0.88 (s, 18H; PCH3), 1.40 (d, JP,H ) 4.5
3
Hz, 9H, PCH3); 1.46 (s, 9H; C(CH3)3); 6.71 (dd, JH,H ) 6.5 Hz,
1
range 4000-400 cm-1. H, 13C{1H}, and 31P{1H} NMR spectra
3
3JH,H ) 7.6 Hz, 2H, Ar-H); 7.74 (d, JH,H ) 7.4 Hz, 1H, Ar-H);
(500, 125, and 202 MHz, respectively) were recorded on a Bruker
DRX 500 spectrometer at the Organic Chemistry Institute of TU
7.85 (d, 3JH,H ) 6.5 Hz, 1H; Ar-H); 9.13 (s, 1H, N-H). 13C{1H}
NMR (d8-THF, 300 K, ppm): 22.3 (dt, 3JP,C ) 2.6 Hz, 1JP,C ) 12.8
Hz, PCH3); 23.3 (td, 1JP,C ) 12.8 Hz, 3JP,C ) 2.6 Hz, PCH3); 29.8
(s, C(CH3)3); 40.1 (s, C(CH3)3); 117.6 (s, CH); 122.4 (s, CH); 126.5
(s, CH); 144.8 (s, C); 152.9 (s, CH); 186.1 (m; CdN), 200.1 (m;
Fe-C). 31P{1H} NMR (d8-THF, 300 K, ppm): 18.2 (d, 2JP,P ) 36.5
1
13
Darmstadt. H and C NMR chemical shifts were referenced to
external TMS, and 31P{1H} chemical shifts were referenced to
external 85% H3PO4. 13C{1H} and 31P{1H} resonances were
obtained with broadband proton decoupling. Magnetic suscepitbility
data were obtained by the Faraday method using a Cahn D 200
torsion balance (Bruker) at 1.5 T.
2
Hz, 2P, PCH3); 23.7 (t, JP,P ) 36.5 Hz, 1P, PCH3).
Synthesis of Hydrido[2-[(imino-KN)phenylmethyl]-2-methylphe-
nyl-KC]tris (trimethylphosphine)iron(II) (3). Fe(CH3)2(PMe3)4 (0.94
g, 2.41mmol) in pentane was combined with 0.44 g (2.41 mmol)
of diphenylketimine to afford violet crystals of 3, which crystallize
at -27 °C. Yield: 0.740 g (74%). Mp: 108-110 °C. Anal. Calcd
for C23H40FeNP3: C, 57.63; H, 8.41; N, 2.92; P, 19.39. Found: C,
58.01; H, 8.43; N, 2.92; P, 18.99. IR (Nujol, cm-1): 3279 vw (ν
H-NdC); 3063 vw, 3021 vw (ν H-CdC); 1761 s (ν Fe-H);
1570 w (ν CdC), 1500 w (ν CdN); 1439 w, 1420 vw (δas PCH3);
(39) Strohmeier, W. Chem. Ber. 1955, 88, 1218.
(40) Schu¨tze, M. Angew. Chem. 1958, 70, 697.
(41) Karsch, H. H.; Klein, H.-F.; Schmidbaur, H. Chem. Ber. 1977, 110,
2200.
(42) Karsch, H. H. Chem. Ber. 1977, 110, 2699.
(43) (a) Richey, H. G.; Erickson, W. F. J. Org. Chem. 1983, 48, 4349.
(b) Imhof, W. Organometallics 1999, 18, 4845.
(44) Wolfsberger, W.; Schmidbaur, H. Synth. React. Inorg. Metal-Org.
Chem. 1974, 4, 149.

2308 Organometallics, Vol. 28, No. 7, 2009
Camadanli et al.
1396 m; 1293 m, 1268 m (δs PCH3), 1277 vw; 1152 vw; 1111 vw;
1091 vw; 1042 vw; 993 vw; 955 w, 935 vs (F1 PCH3); 845 m (F2
PCH3); 802 vw; 764 m, 729 s (γ C-Harom); 707 s, 681 w (νas PC3);
660 m, 650 m (νs PC3); 598 m, 505 w (ν Fe-C); 482 w. 1H NMR
(d8-THF, 300 K, ppm): -17.2 (dt, JP,H ) 22.5 Hz, JP,H ) 82.3
Hz, 1H, Fe-H); 0.99 (s, 18H, PCH3); 1.41 (d, 2JP,H ) 3.3 Hz, 9H,
PCH3); 2.21 (s, 3H, Ar-CH3); 6.65 (t, 3JH,H ) 6.0 Hz, 1H, Ar-H);
which crystallize at 4 °C. Yield: 1.480 g (73%). Mp: 119-121 °C.
Anal. Calcd for C23H40FeNP3: C, 57.63; H, 8.41; N, 2.92; P, 19.39.
Found: C, 57.80; H, 8.10; N, 2.95; P, 19.32. IR (Nujol, cm-1):
3038 vw (ν H-CdC); 1594 w, 1571 w (ν CdC); 1543 w (ν CdN);
1422 m, 1412 w (δas PCH3); 1333 m; 1295 m, 1277 m (δs PCH3);
1223 vw; 1193 w, 1170 w (δs Fe-CH3); 1149 w; 1072 vw; 1026
vw; 993 vw; 942 vs (F1 PCH3); 886 w; 852 m (F2 PCH3); 765 s,
750 m (γ C-Harom); 727 s, 701 s (νas PC3); 659 w (νs PC3); 636
2
2
3
3
6.79 (t, JH,H ) 6.1 Hz, 1H, Ar-H); 7.02 (d, JH,H ) 6.9 Hz, 1H,
3
3
1
Ar-H); 7.10 (t, JH,H ) 6.1 Hz, 1H, Ar-H); 7.16 (t, JH,H ) 6.9
Hz, 1H, Ar-H); 7.23 (m, 2H, Ar-H); 7.89 (s, 1H, Ar-H); 9.25
(s, 1H, N-H). 13C NMR (d8-THF, 300 K, ppm): 21.1 (s, Ar-CH3);
23.2 (m, PCH3); 118.2 (s, CH); 122.8 (s, CH); 126.4(d, 3JP,C ) 8.1
Hz, CH), 128.5 (s, CH); 129.4 (s, CH); 131.2 (s; C); 136.6 (s, C);
vw; 572 w; 537 vw. H NMR (d8-THF, 300 K, ppm): -0.96 (sbr,
2
3H, Fe-CH3); 1.11 (s, 18H, PCH3); 1.42 (d, JP,H ) 4.5 Hz, 9H,
PCH3); 6.82-7.06 (m, 2H, Ar-H); 7.14-7.26 (m, 3H; Ar-H);
3
3
7.33 (t, JH,H ) 7.0 Hz, 1H, Ar-H); 7.41 (t, JH,H ) 7.1 Hz, 1H,
3
3
Ar-H); 7.50 (t, JH,H ) 7.1 Hz, 1H, Ar-H); 7.83 (t, JH,H ) 7.8
Hz, 1H, Ar-H); 8.38 (s, 1H, H-CdN). 13C{1H} NMR (d8-THF,
300 K, ppm): -13.8 (dt, 2JP,C ) 25.6 Hz, 2JP,C ) 8.2 Hz, Fe-CH3);
3
142.6 (s, C); 147.3 (s, CH); 152.1 (s, CH); 181.2 (d, JP,C ) 9.8
Hz, C)N); 203.1 (m, Fe-C). 31P NMR (d8-THF, 296 K, ppm):
2
14.2 (dt′ |1JP,C + JPC| ) 9.3 Hz, JP,C ) 2.3 Hz, PCH3); 22.0 (d,
1JP,C ) 12.5 Hz, PCH3); 119.0 (s, CH); 122.1 (s, CH); 127.0(s,
CH); 128.1 (s, CH); 129.0(s, CH); 129.3 (s, CH); 131.0 (s, CH);
3
3
15.7 (m, 2P, PCH3); 21.2 (t, JP,P ) 38.3 Hz, 1P, PCH3).
Synthesis of Methyl[2-[(methylimino-KN)methyl]phenyl-KC]tris-
(trimethylphosphine)iron(II) (4). Fe(CH3)2(PMe3)4 (1.0 g, 2.56
mmol) was combined with 0.31 g (2.56 mmol) of N-methylben-
zylidenimine in pentane to afford violet crystals of 4, which
crystallize at 4 °C. Yield: 0.753 g (65%). Mp: 115-117 °C (dec).
Anal. Calcd for C18H38FeNP3: C, 51.81; H, 9.18; N, 3.36; P, 22.27.
Found: C, 51.52; H, 9.38; N, 3.37; P, 22.27. IR (Nujol, cm-1):
3053 vw, 3034 vw (ν H-CdC); 1572 m (ν CdC); 1521 m (ν
CdN); 1416 w (δas PCH3); 1294 m, 1276 s (δs PCH3); 1221 w;
1180 w (δs Fe-CH3); 1118 w; 1020 w; 996 w; 937 vs (F1 PCH3);
844 m (F2 PCH3); 746 w, 730 m (γ C-Harom); 712 vw, 702 w (νas
3
153.2 (s, C); 169.7 (s, C); 171.7 (d, JP,C ) 5.5 Hz, CdN), 203.7
(dt, JP,C ) 22.2 Hz, JP,C ) 5.5 Hz, Fe-Cm). 31P{1H} NMR (d8-
2
2
2
THF, 296 K, ppm): 8.2 (t, JP,P ) 37.4 Hz, 1P, PCH3), 19.1 (d,
2JP,P ) 37.4 Hz, 2P, PCH3).
General Procedure for Iodomethane Reactions. Iodomethane
was added to a sample of cyclometalated complex in pentane at
-70 °C, and the mixture was allowed to warm to 20 °C. After 5 h
stirring, the mixture was filtered and the solution was kept at 4 °C
to afford crystals.
1
PC3); 677 w, 658 w (νs PC3); 646 vw. H NMR (d8-THF, 298 K,
Synthesis of Iodo[2-[(imino-KN)phenylmethyl]phenyl-KC]tris-
(trimethylphosphine)iron(II) (7). 1 (610 mg, 1.31 mmol) was
combined with 186 mg (0.82 mL, 1.31 mmol) of CH3I in pentane
to afford reddish-pink crystals of 7, which crystallize at 4 °C. Yield:
0.597 g (77%). Mp: 143-145 °C. Anal. Calcd for C22H37FeINP3:
C, 44.69; H, 6.31; N, 2.37; P, 15.72. Found: C, 44.68; H, 6.67; N,
2.31; P, 15.64. IR (Nujol, cm-1): 3287 w (ν H-NdC); 3055 w (ν
H-CdC); 1597 vw, 1572 m, 1513 m (ν CdC); 1489 vw (ν CdN);
1407 m (δas PCH3); 1298 m, 1271 m (δs PCH3); 1236 w; 1213 w;
1157 w; 1099 vw; 1077 vw; 995 w; 945 vs (F1 PCH3); 847 s (F2
PCH3); 783 s, 755 w, 727 s (γ C-Harom); 700 vs (νas PC3); 664 m
(νs PC3); 589 w; 513 w (ν Fe-C); 463 vw. 1H NMR (d8-THF, 300
ppm): -1.38 (sbr, 3H, Fe-CH3); 0.71 (sbr, 18H, PCH3); 1.49 (sbr,
9H, PCH3); 3.65 (s, 3H, N-CH3); 6.74 (s, 1H, Ar-H); 6.85 (s,
1H, Ar-H); 7.30 (s, 1H, Ar-H); 7.87 (s, 1H, Ar-H); 8.48 (s, 1H,
NdC-H). 13C{1H} NMR (d8-THF, 298 K, ppm): -16.6 (dt, 2JP,C
) 25.6 Hz, 2JP,C ) 8.2 Hz, Fe-CH3); 16.9 (dt′ |1JP,C + 3JPC| ) 9.3
3
1
Hz, JPC ) 2.3 Hz, PCH3); 24.0 (d, JP,C ) 12.5 Hz, PCH3), 54.8
3
(d, JP,C ) 3.6 Hz, N-CH3); 119.1 (s, CH); 124.7 (s, CH); 126.0
(s, CH); 143.5 (s, CH); 149.5 (s, C); 174.4 (d, 3JP,C ) 5.5 Hz, CdN),
206.6 (dt, JP,C ) 26.2 Hz, JP,C ) 6.2 Hz, Fe-C). 31P{1H} NMR
(d8-THF, 296 K, ppm): 7.6 (t, 2JP,P ) 35.6 Hz, 1P, PCH3), 16.7 (d,
2JP,P ) 35.6 Hz, 2P, PCH3).
2
2
4
K, ppm): 1.09 (t′, |2JP,H + JP,H| ) 6.6 Hz, 18H, PCH3); 1.66 (d,
Synthesis of Methyl[2-[[(1-methylethyl)imino]methyl]phenyl-
KC]tris(trimethylphosphine)iron(II) (5). Fe(CH3)2(PMe3)4 (1.06 g,
2.72 mmol) in pentane was combined with 0.39 g (2.72 mmol) of
N-(1-methylethyl)benzylidenimine to afford violet crystals of 5,
which crystallize at -27 °C. Yield: 0.840 g (69%). Mp: 116-118
°C. Anal. Calcd for C20H42FeNP3: C, 53.94; H, 9.51; N, 3.15; P,
20.87. Found: C, 54.09; H, 8.54; N, 2.88; P, 19.75. IR (Nujol, cm-1):
3037 vw (ν H-CdC); 1571 m, 1561 m (ν CdC); 1519 m (ν CdN);
1415 s (δas PCH3); 1360 w; 1292 s, 1272 s (δs PCH3); 1222 m;
1162 m (δs Fe-CH3); 1148 m; 1107 m; 1031 m; 941 vs (F1 PCH3);
868 w; 846 m (F2 PCH3); 748 s, 729 s (γ C-Harom); 708 m, 695 s
3
2JP,H ) 6.6 Hz, 9H, PCH3); 6.67 (t, JH,H ) 7.3 Hz, 1H, Ar-H);
3
4
6.79 (dt, JH,H ) 8.1 Hz, JH,H ) 1.5 Hz, 1H, Ar-H); 7.43 (dd,
3JH,H ) 7.8 Hz, JH,H ) 0.9 Hz, 1H, Ar-H); 7.47 (td, JH,H ) 7.1
4
3
4
Hz, JH,H ) 1.5 Hz, 1H, Ar-H); 7.49-7.53 (m, 2H, Ar-H);
7.57-7.59 (t, 3JH,H ) 7.8 Hz, 3H, Ar-H); 7.61 (d, 3JH,H ) 7.8 Hz,
1H, Ar-H); 9.49 (sbr, 1H, N-H). 13C{1H} NMR (d8-THF, 300 K,
ppm): 19.1 (t′, |1JP,C + JP,C| ) 22.3 Hz, PCH3); 24.2 (d, JP,C
)
3
1
18.8 Hz, PCH3); 119.1 (s, CH); 127.1 (s, CH); 128.3 (s, CH); 129.7
4
(s, CH), 129.9 (s, CH); 149.4 (d, JP,C ) 4.8 Hz, C); 181.9 (m,
CdN), 208.1 (m, Fe-C). 31P{1H} NMR (d8-THF, 296 K, ppm):
2
2
1
11.3 (d, JP,P ) 57.0 Hz, 2P, PCH3), 17.7 (t, JP,P ) 57.0 Hz, 1P,
(νas PC3); 658 s (νs PC3); 636 w; 567 vw; 537 vw; 451 vw. H
PCH3).
NMR (d8-THF, 298 K, ppm): -1.06 (sbr, 3H, Fe-CH3); 0.91 (sbr,
3
18H, PCH3); 1.16 (sbr, 9H, PCH3); 1.33 (d, JH,H ) 6.7 Hz, 6H,
Synthesis of Iodo[2-[(imino-KN)phenylmethyl]-1,1-dimethylethyl-
KC]tris(trimethylphosphine)iron(II) (8). 2 (774 mg, 1.74 mmol)
was combined with 247 mg (1.09 mL, 1.74 mmol) of CH3I in
pentane to afford reddish-pink crystals of 8, which crystallize at 4
°C. Yield: 0.745 g (75%). Mp: 160-162 °C (dec). Anal. Calcd for
C20H41FeINP3: C, 42.05; H, 7.23; N, 2.45; P, 16.27. Found: C,
41.85; H, 6.95; N, 2.20; P, 16.55. IR (Nujol, cm-1): 3320 w (ν
H-NdC); 3070 vw, 3042 vw, 3012 vw (ν H-CdC), 1565 m (ν
H-CdC); 1565 m, 1556 w (ν CdC); 1525 vw (ν CdN); 1406 m
(δas PCH3); 1353 w; 1297 m, 1281 m (δs PCH3); 1231 m; 1205
vw; 1176 vw; 1152 vw; 1107 w; 1016 w; 999 w; 941 vs (F1 PCH3);
868 vw; 851 m (F2 PCH3); 815 w; 776 w, 738 s (γ C-Harom); 716 s,
CH-CH3); 3.44-3.48 (m, 1H, NCH(CH3); 6.96 (s, 1H, Ar-H);
7.20 (s, 1H, Ar-H); 7.52 (s, 1H, Ar-H); 7.83 (s, 1H, Ar-H); 8.36
(s, 1H, NdC-H). 13C{1H} NMR (d8-THF, 298 K, ppm): -14.2
2
2
(dt, JP,C ) 25.4 Hz, JP,C ) 8.1 Hz, Fe-CH3); 15.7 (dt′ |1JP,C
+
3JPC| ) 9.1 Hz, JPC ) 2.1 Hz, PCH3); 22.1 (d, JP,C ) 12.5 Hz,
PCH3), 25.4 (s, CH-CH3); 54.8 (d, 3JP,C ) 4.0 Hz, N-CH-CH3);
121.1 (s, CH); 128.7 (s, CH); 129.2 (s, CH); 139.6 (s, CH); 149.5
(s, C); 169.7 (d, 3JP,C ) 5.5 Hz, CdN), 200.7 (dt, 2JP,C ) 20.2 Hz,
2JP,C ) 7.2 Hz, Fe-C). 31P{1H} NMR (d8-THF, 296 K, ppm): 7.1
(t, 2JP,P ) 31.0 Hz, 1P, PCH3), 15.6 (d, 2JP,P ) 33.6 Hz, 2P, PCH3).
3
1
Synthesis of Methyl[2-[(phenylimino-KN)methyl]phenyl-KC]tris-
(trimethylphosphine)iron(II) (6). Fe(CH3)2(PMe3)4 (1.40 g, 3.58
mmol) in pentane was combined with 0.65 g (3.58 mmol) of
N-phenylbenzylidenimine to give petroleum green crystals of 6,
1
692 w (νas PC3); 660 m (νs PC3); 648 vw; 507 vw. H NMR (d8-
THF, 300 K, ppm): 1.06 (s, 18H, PCH3), 1.51 (s, 9H, C(CH3)3);
1.61 (d, 2JP,H ) 5.9 Hz, PCH3); 6.69 (m, 2H, Ar-H); 7.51 (d,4JP,H

C-H ActiVation of Imines by Iron Complexes
Organometallics, Vol. 28, No. 7, 2009 2309
Table 5. Crystal Data for Compounds 1-4 and 6
1
2
3
4
6
empirical formula
molecular mass
cryst size [mm]
cryst syst
space group
a [Å]
C22H38FeNP3
465.29
C20H42FeNP3
445.31
0.40 × 0.20 × 0.18
orthorhombic
Pnma
9.6581(7)
13.5905(10)
18.7569(14)
90
90
90
2462.0(3)
4
1.201
C23H40FeNP3
479.32
C18H38FeNP3
417.25
C23H40FeNP3
479.32
0.12 × 0.10 × 0.08
monoclinic
P21/n
8.6450(6)
17.2303(9)
17.5171(12)
90
102.068(6)
90
2551.6(3)
4
1.248
0.788
150(2)
0.12 × 0.10 × 0.08
0.45 × 0.30 × 0.20
0.15 × 0.10 × 0.10
triclinic
triclinic
triclinic
j
j
j
P1
P1
P1
9.2765(12)
11.4028(13)
13.4638(16)
65.433(9)
78.456(10)
74.456(10)
1243.2(3)
2
1.243
0.807
150(2)
1.67 e θ e 26.92
-11 e h e 11
-14 e k e 14
-17 e l e 17
18 486
9.2537(4)
9.3794(4)
14.8576(6)
94.603(1)
90.404(1)
93.928(1)
1282.27(9)
2
1.241
0.784
298(2)
2.18 e θ e 28.24
-12 e h e 12
-12 e k e 12
-19 e l e 18
16 331
8.6470(14)
14.882(4)
17.814(3)
103.140(16)
95.330(13)
90.060(17)
2222.1(7)
4
1.247
0.895
150
1.62 e θ e 26.86
-10 e h e 10
-18 e k e 18
-22 e l e 22
26 214
b[Å]
c [Å]
R [deg]
ꢀ [°deg]
γ [deg]
V [Å3]
Z
Dcalcd [g/cm3]
µ(Mo KR) [mm-1
temperature [K]
θ range [deg]
h
]
0.812
298(2)
1.85 e θ e 28.20
-11 e h e 12
-18 e k e 18
-24 e l e 24
29 358
1.68 e θ e 26.85
-10 e h e 10
-21 e k e 21
-22 e l e 22
35 729
k
l
no. reflns measd
no. unique data
5253
3145
6316
9308
5410
[Rint ) 0.0990]
396
[Rint ) 0.0486]
143
[Rint ) 0.0194]
263
[Rint ) 0.0727]
437
[Rint ) 0.0562]
253
no. params
no. restraints
0
0
0
0
0
GoF on F2
1.109
0.997
1.067
1.056
1.080
R1 [I g 2σ(I)]
wR2 (all data)
0.0294
0.0791
0.0378
0.1098
0.0365
0.1048
0.0525
0.1266
0.0290
0.0737
3
) 7.4 Hz, 1H, Ar-H); 7.76 (d, JH,H ) 6.7 Hz, 1H, Ar-H); 9.50
2.60; P, 17.58. IR (Nujol, cm-1): 3056 vw (ν H-CdC); 1591 s,
1572 s (ν CdC); 1529 m (ν CdN); 1421 s (δas PCH3); 1296 s,
1280 s, 1273 s (δs PCH3); 1236 w; 1219 w; 1156 w; 1124w;
1105 w; 1038 vw; 1008 w; 997 w; 939 vs (F1 PCH3); 856 m (F2
PCH3); 753 m, 746 m (γ C-Harom); 727 s, 713 s (νas PC3); 694
vw; 663 m (νs PC3); 642 vw; 537 vw, 471 vw. 1H NMR (d8-THF,
298 K, ppm): 1.14 (s, 18H, PCH3); 1.56 (s, 9H, PCH3); 3.83 (s,
3H, N-CH3); 6.70 (m, 2H, Ar-H); 7.27 (s, 1H, Ar-H); 7.54 (s,
1H, Ar-H); 8.43 (s, 1H, NdC-H). 13C{1H} NMR (d8-THF, 298
(sbr, 1H, N-H). 13C{1H} NMR (d8-THF, 300 K, ppm): 18.9 (t′,
|1JP,C + 3JP,C| ) 22.1 Hz, PCH3); 24.3 (td, 1JP,C ) 18.5 Hz, 3JP,C
)
2.2 Hz, PCH3); 29.3(s, CCH3); 39.8 (s, CCH3); 118.3 (s, CH); 126.2
3
(s, CH); 129.3 (s, CH); 146.1 (d, JP,C ) 7.9 Hz, CH); 148.3 (d,
4JP,C ) 4.6 Hz, C); 187.8 (t, JP,C ) 8.6 Hz, CdN); 208.4 (m,
3
Fe-C). 31P{1H} NMR (d8-THF, 300 K, ppm): 13.1 (d, 2JP,P ) 55.9
2
Hz, 2P, PCH3); 19.9 (t, JP,P ) 55.9 Hz, 1P, PCH3).
Synthesis of Iodo[2-[(imino-KN)phenylmethyl]-2-methylphenyl-
KC]tris (trimethylphosphine)iron(II) (9). 3 (598 mg, 1.25 mmol)
in pentane was combined with 177 mg (0.78 mL, 1.25 mmol) of
CH3I to afford reddish-pink crystals of 9, which crystallize at 4
°C. Yield: 544 mg (72%). Mp: 146-148 °C (dec). Anal. Calcd for
C23H39FeINP3: C, 45.64; H, 6.49; N, 2.31; P, 15.35. Found: C,
45.17; H, 5.38; N, 1.80; P, 16.28. IR (Nujol, cm-1): 3289 vw (ν
H-NdC); 3050 w, 3019 vw (ν H-CdC); 1570 m (ν CdC);
1514 w (ν CdN); 1408 m (δas PCH3); 1297 w, 1280 w (δs PCH3),
1231 vw; 1152 vw; 993 vw; 940 vs (F1 PCH3); 850 m (F2 PCH3);
782 w, 760 m (γ C-Harom); 738 s, 719 m (νas PC3); 658 m (νs
K, ppm): 18.9 (t′ |1JP,C + 3JP,C| ) 21.3 Hz, PCH3); 24.5 (d, 1JP,C
)
20.9 Hz, PCH3); 55.3 (s, N-CH3); 119.3 (s, CH); 126.7 (m, CH);
128.3 (s, CH); 146.3 (s, C); 162.4 (s, CH); 174.7 (s, CdN), 212.7
2
(s, Fe-C). 31P{1H} NMR (d8-THF, 296 K, ppm): 5.8 (d, JP,P
54.3 Hz, 2P, PCH3); 14.9 (t, JP,P ) 54.3 Hz, 1P, PCH3).
)
2
Synthesis of Iodo[2-[[(1-methylethyl)imino-KN]methyl]phenyl-
KC]tris (trimethylphosphine)iron(II) (11). 5 (1.02 g, 2.29 mmol)
was combined with 0.33 g (0.93 mL, 1.43 mmol) of CH3I in pentane
to afford light violet crystals of 11, which crystallize at 4 °C. Yield:
0.88 g (69%). Mp: 145-147 °C. Anal. Calcd for C19H39FeINP3:
C, 40.96; H, 7.05; N, 2.51; P, 16.68. Found: C, 40.94; H, 7.15; N,
2.46; P, 16.47. IR (Nujol, cm-1): 3088 w (ν H-CdC); 1594 m,
1572 m (ν CdC); 1533 w (ν CdN); 1423 m (δas PCH3); 1313 w;
1298 s, 1273 m (δs PCH3); 1236 w; 1221 w; 1163 w; 1121w;
1108 w; 1005 w; 944 vs (F1 PCH3); 870 w; 844 w (F2 PCH3); 746 m
1
PC3); 596 w; 500 vw. H NMR (d8-THF, 300 K, ppm): 1.17 (t′
|2JP,H + 4JP,H| ) 6.4 Hz, 18H, PCH3); 1.67 (d, 2J P,H ) 6.4 Hz, 9H,
PCH3); 2.17 (s, 3H, Ar-CH3); 6.61 (t, 3JH,H ) 7.3 Hz, 1H, Ar-H);
3
4
6.75 (dt, JH,H ) 8.1 Hz, J
) 1.4 Hz, 1H, Ar-H); 7.01 (d,
3
H,H
3JH,H ) 8.1 Hz, 1H, Ar-H); 7.31 (t, JH,H ) 7.8 Hz, 2H, Ar-H);
3
4
7.40 (dt, JH,H ) 7.4 Hz, JH,H ) 1.4 Hz, 1H, Ar-H); 7.42 (dd,
3JH,H ) 6.5 Hz, JH,H ) 1.2 Hz, 1H, Ar-H); 7.62 (d, JH,H ) 7.8
4
3
Hz 1H, Ar-H); 9.42 (s, 1H, N-H). 13C{1H} NMR (d8-THF, 300
1
K, ppm): 19.5 (t′ |1JP,H
+
3JP,H| ) 22.5 Hz, PCH3); 21.8 (s,
(γ C-Harom); 728 s, 714 m (νas PC3); 660 m (νs PC3). H NMR
1
(d8-THF, 298 K, ppm): 0.84 (t′, |2JP,H +4JP,H| ) 5.9 Hz, 18H, PCH3);
Ar-CH3); 24.1 (d, J
) 18.8 Hz, PCH3); 118.9 (s, CH); 126.7
P,C
3
2
2
(s, CH); 127.4(s, CH), 128.3 (s, C); 129.4 (s, CH); 130.1 (d; JP,C
1.69 (d, JP,H ) 6.4 Hz, 6H, CH(CH3)2); 1.50 (d, JP,H ) 6.4 Hz,
4
2
) 16.9 Hz, CH); 131.8 (s, C); 136.1 (s, C); 145.7 (d, JP,C ) 7.1
9H, PCH3); 5.38 (sep, JH,H ) 6.2 Hz, 1H, CH(CH3)2); 7.11 (m,
Hz, CH); 182.9 (m, CdN); 228.4 (m, Fe-C). 31P{1H} NMR (d8-
1H, Ar-H); 7.17 (m, 1H, Ar-H); 7.51 (m, 1H, Ar-H); 7.65 (m,
2
THF, 300 K, ppm): 10.8 (d, JP,P ) 57.5 Hz, 2P, PCH3); 19.2 (t,
1H, Ar-H), 8.29 (s, 1H, NdC-H). 13C{1H} NMR (d8-THF, 298
2JP,P ) 57.5, 1P, PCH3.
K, ppm): 12.3 (t′ |1JP,C + 3JP,C| ) 28.7 Hz, PCH3); 15.8 (d, 1JP,C
)
Synthesis of Iodo[2-[(methylimino-KN)methyl]phenyl-KC]tris-
(trimethylphosphine)iron(II) (10). 4 (623 mg, 1.49 mmol) was
combined with 211 mg (0.93 mL, 1.49 mmol) of CH3I in pentane
to afford rose crystals of 10, which crystallize at 4 °C. Yield: 426
mg (72%). Mp: 142-144 °C. Anal. Calcd for C17H35FeINP3: C,
38.59; H, 6.67; N, 2.65; P, 17.56. Found: C, 38.86; H, 6.53; N,
3
20.3 Hz, PCH3); 19.2 (s, CH(CH3)2); 49.5 (d, JP,C ) 13.9 ppm,
CH(CH3)2); 129.1 (s, CH); 129.6 (d, 4JP,C ) 4.4 Hz, CH); 130.1 (s,
CH); 131.2 (s, CH); 158.9 (s, C); 160.4 (s, CdN); 199.7 (s, Fe-C).
2
31P{1H} NMR (d8-THF, 296 K, ppm): 28.3 (d, JP,P ) 28.3 Hz,
2
2P, PCH3); 21.8 (t, JP,P ) 28.3 Hz, 1P, PCH3).

2310 Organometallics, Vol. 28, No. 7, 2009
Camadanli et al.
General Procedure for Carbon Monoxide Reactions. A sample
of cyclometalated complex was stirred under 1 bar of CO for 10 h.
Upon filtration, the solution was cooled to 4 °C to afford crystals.
Synthesis of Methyl[2-[(methylimino-KN)methyl]phenyl-KC](car-
bonyl)bis(trimethylphosphine)iron(II) (12). A sample of 4 (770 mg,
1.84 mmol) in pentane was stirred under 1 bar of CO to provide
reddish-pink crystals of 12, which crystallize at -27 °C. Yield:
450 mg (66%). Mp: 134-136 °C. Anal. Calcd for C16H29FeNOP2:
C, 52.05; H, 7.92; N, 3.79; P, 16.78. Found: C, 52.30; H, 7.91; N,
3.10; P, 17.32. IR (Nujol, cm-1): 3068 vw, 3028 vw (ν H-CdC);
1869 vs (ν CtO); 1595 m, 1573 w (ν CdC); 1531 w (ν CdN);
1420 m (δas PCH3); 1298 w, 1281 m (δs PCH3); 1240 w; 1218 w;
1153 w (δ Fe-CH3); 1036 vw; 1008 vw; 946 vs (F1 PCH3); 854 m
(F2 PCH3); 751 m (γ C-Harom); 722 s (νas PC3); 668 m (νs PC3);
3063 w, 3012 vw (ν H-CdC); 1870 vs (ν Fe-CtO); 1576 m (ν
CdC), 1514 m (ν CdN); 1350 vw (δas PCH3); 1302 w, 1280 m
(δs PCH3); 1230 vw; 1193 m (δs Fe-CH3); 1107 mbr; 1008 vw;
944 vs (F1 PCH3); 852 m (F2 PCH3); 768 m, 748 m (γ C-Harom);
722 s, 701 m (νas PC3); 670 w (νs PC3); 645 w; 628 w; 600 m;
566 w. 1H NMR (d8-THF, 298 K, ppm): -0.71 (t, 3JP,H ) 8.1 Hz,
4
3H, Fe-CH3); 0.93 (t′ |2JP,H + JP,H| ) 7.3 Hz, 18H, PCH3); 6.83
(t, 3JH,H ) 7.2 Hz 1H, Ar-H); 6.89 (t, 3JH,H ) 7.2 Hz 1H, Ar-H);
3
3
7.02 (d, JH,H ) 7.8 Hz, 2H, Ar-H); 7.19 (t, JH,H ) 7.3 Hz, 1H,
3
3
Ar-H); 7.33 (t, JH,H ) 7.8 Hz, 2H, Ar-H); 7.57 (d, JH,H ) 7.4
Hz, 1H, Ar-H); 8.08 (d, 3JH,H ) 7.3 Hz, 1H, Ar-H); 8.49 (t, 4JP,H
) 4.2 Hz, 1H, NdC-H). 13C{1H} NMR (d8-THF, 298 K, ppm):
2
3
-7.1 (t, JP,C ) 17.2 Hz, Fe-CH3); 15.4 (t′ |1JP,C + JPC| ) 23.2
Hz, PCH3); 120.7 (s, CH); 125.3 (s, CH); 129.2 (s, CH); 130.8 (s,
CH); 144.1 (s, CH); 150.5 (s, C); 152.9 (s, C); 175.8 (t, 3JP,C ) 4.5
Hz, CdN), 215.8 (m, Fe-C); 224.9 (t, 2JP,C ) 35.6 Hz, Fe-CO).
31P{1H} NMR (d8-THF, 296 K, ppm): 18.3 (s, PCH3).
1
646 w; 620 w, 607 w. H NMR (d8-THF, 298 K, ppm): -0.67 (t,
3JP,H ) 6.8 Hz, 3H, Fe-CH3); 0.89 (s, 18H, PCH3); 3.34 (s, 3H,
3
3
N-CH3); 6.72 (t, JH,H ) 6.0 Hz 1H, Ar-H); 6.79 (t, JH,H ) 6.0
Hz, 1H, Ar-H); 7.34 (d, 3JH,H ) 6.0 Hz, 1H, Ar-H); 7.96 (d, 3JP,H
) 5.4 Hz, 1H, Ar-H); 8.33 (s, 1H, NdC-H). 13C{1H} NMR (d8-
In Situ Observation of Methane/Ethane. To detect gaseous
products, we repeated the reactions of Fe(PMe3)4 and
Fe(CH3)2(PMe3)4 with diphenylketimine and complex 4 with CH3I
in NMR Schlenk tubes by condensing 0.8 mL of d8-THF to the
starting materials. Under vacuum, the solutions were frozen to -196
°C, and the NMR tubes were sealed. The reactions were im-
mediately monitored at room temperature by 1H NMR spectroscopy
for 2 h. Together with the all characteristic signals of expected
products, CH4 (0.22 ppm) and C2H6 (0.84 ppm) resonances were
recorded in the high-field region.
General Comments on X-ray Diffraction Studies. Single
crystals were sealed under argon in glass capillaries, whereas air-
stable crystals were glued on a glass fiber. Data collections were
performed on a STOE IPDSII image detector and on a Bruker AXS
SMART APEX diffractometer using Mo KR radiation (λ ) 0.71019
Å). Details of the crystal structure are given in Table 5. Data
collection:45 Stoe X-AREA, Bruker SMART. Data reduction:45 Stoe
X-RED, Bruker SAINT. The structures were solved by direct
methods using SHELXS-97, and anisotropic displacement param-
eters were applied to non-hydrogen atoms in a full-matrix least-
squares refinement based on F2 using SHELXL-97.46 Hydrogen
atoms on C were placed at idealized positions (C-H ) 0.93, 0.96
Å for methyl groups) and were allowed to ride on the parent atom
[Uiso(H) ) 1.2U(C) for CH groups and Uiso(H) ) 1.5U(C) for
methyl groups].
2
THF, 298 K, ppm): -11.5 (t, JP,C ) 18.4 Hz, Fe-CH3); 15.0 (t′
|1JP,C + JPC| ) 23.0 Hz, PCH3); 46.8 (s, N-CH3); 120.0 (s, CH);
3
126.9 (s, CH); 128.1 (s, CH); 143.5 (s, CH); 148.9 (s, C); 174.3 (t,
3JP,C ) 4.4 Hz, CdN), 211.6 (m, Fe-C); 224.2 (s, Fe-CO) ppm.
31P{1H} NMR (d8-THF, 296 K, ppm): 19.1 (s, PCH3) ppm.
Synthesis of Methyl[2-[[(1-methylethyl)imino-KN]methyl]phe-
nyl-KC(carbonyl)bis(trimethylphosphine)iron(II) (13). A sample of
5 (650 mg, 1.46 mmol) in pentane was stirred under 1 bar of CO
to provide reddish-pink crystals of 13, which crystallize at -27
°C. Yield: 336 mg (58%). Mp: 131-133 °C. Anal. Calcd for
C18H33FeNOP2: C, 54.42; H, 8.37; N, 3.53; P, 15.59. Found: C,
54.46; H, 8.43; N, 3.53; P, 16.54. IR (Nujol, cm-1): 3075 vw,
3040 w (ν H-CdC); 1879 vs (ν CtO); 1591 m, 1573 w (ν CdC);
1532 w (ν CdN); 1420 m (δas PCH3); 1299 w, 1279 m (δs PCH3);
1239 vw; 1219 vw; 1151 vw (δs Fe-CH3); 1126 vw; 1113 vw;
1032 vw; 1010 vw; 941 vs (F1 PCH3); 850 m (F2 PCH3); 754 m (γ
C-Harom); 721 s (νas PC3); 667 (νs PC3); 646 m; 629 w; 599 m. 1H
3
NMR (d8-THF, 298 K, ppm): -0.59 (t, JP,H ) 7.3 Hz, 3H,
3
Fe-CH3); 0.90 (sbr, 18H, PCH3); 1.29 (d, JH,H ) 6.5 Hz, 6H,
CH(CH3)2); 4.08 (sep, 3JH,H ) 6.5 Hz, 1H, CH(CH3)2); 6.75 (t, 3JH,H
) 6.9 Hz 1H, Ar-H); 6.82 (t, 3JH,H ) 6.9 Hz 1H, Ar-H); 7.40 (d,
3
3JH,H ) 7.2 Hz, 1H, Ar-H); 7.91 (d, JH,H ) 6.9 Hz, 1H, Ar-H);
8.49 (m, 1H, H-CdN). 13C{1H} NMR (d8-THF, 298 K, ppm):
-13.2 (t, 2JP,C ) 17.2 Hz, Fe-CH3); 13.2 (t′, |1JP,C + 3JPC| ) 11.2
Hz, PCH3); 22.4 (s, CH(CH3)2); 51.4 (s, CH(CH3)2); 118.1 (s, CH);
124.9 (s, CH); 126.4 (s, CH); 141.4 (s, CH); 148.7 (s, C); 168.0 (t,
Supporting Information Available: . Structure determination
summaries and listings of final atomic coordinates, thermal
parameters, bond lengths, and bond angles for compounds 1-4, 6,
7, 10, and 14. This material is available free of charge via the
Internet at http://pubs.acs.org.
2
3JP,C ) 3.6 Hz, CN); 207.3 (t, JP,C ) 21.8 Hz, Fe-C); 222.6 (t,
2JP,C ) 35.6 Hz, Fe-CO). 31P{1H} NMR (d8-THF, 296 K, ppm):
18.7 (s, 2P, PCH3).
Synthesis of Methyl[2-[(phenylimino-KN)methyl]phenyl-KC](car-
bonyl)bis (trimethylphosphine)iron(II) (14). A sample of 6 (490
mg, 1.02 mmol) in pentane was stirred under 1 bar of CO to provide
reddish-pink crystals of 14, which crystallize at -27 °C. Yield:
347 mg (73%). Mp: 137-139 °C (dec). Anal. Calcd for
C24H29FeNOP2: C, 58.48; H, 7.25; N, 3.25; P, 14.36. Found: C,
58.85; H, 6.81; N, 3.24; P, 14.35. IR (Nujol, cm-1): 3075 vw,
OM800828J
(45) Sheldrick, G. M.; Kru¨ger, C.; Goddard, R. Acta Crytallogr. Sect.
A 1990, 46, 467.
(46) (a) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112. (b) Sheldrick,
G. M.; Kru¨ger, C.; Goddard, R. SHELXS-97. and SHELXL-97; Universita¨t
Go¨ttingen, 1997.