Dioxaneferrocenylimine cyclometalated compounds as precursors to novel functionalized Di- and tetranuclear metallacycles leading to 1,3-double palladation of an η5-C5H5 ring

Article abstract of DOI:10.1021/om2008698

Reaction of the Schiff base ligands CpFe[η⁵-C ₅H₂{C(H)O(CH₂)₃O}C(H)=NR] (R = 2,4,6-Me₃C₆H₂, a; R = Cy, b) derived from the 1,2-disubstituted formylferrocene CpFe[(CHO){C(H)O(CH₂) ₃O}-η⁵-C₅H₃] 1, with Li ₂[PdCl₄] in methanol at room temperature for 48 h, gave the chlorine-bridged complexes [Pd{CpFe[η⁵-C₅H ₂{C(H)O(CH₂)₃O}C(H)=NR]}(Cl)]₂, 1a and 1b, after C-H activation of the cyclopentadienyl ring bearing the cyclic acetal. The reactions of 1a and 1b with the Ph₂P(CH₂) _nPPh₂ diphosphines in a 1:2 ratio, plus addition of ammonium hexafluorophosphate, gave the dinucelar compounds [Pd{CpFe[η ⁵-C₅H₂{C(H)O(CH₂) ₃O}C(H)=NR]}-(Ph₂P(CH₂)_nPPh ₂-P,P)][PF₆] 2a, 3a and 2b, 3b with the diphosphine in a chelating mode, as 1:1 electrolytes. Treatment of the latter with aqueous acetic acid gave the corresponding functionalized compounds with transformation of the 1,3-dioxane ring into a formyl group on the metalated ring, 4a, 5a and 4b, 5b.The Schiff base condensation reaction of 5b with 2-(methylthio)aniline in refluxing chloroform gave [Pd(Ph₂P(CH₂) ₂PPh₂){(CpFe)η⁵-C₅H ₂[C(H)=NCy][C(H)=N(2-SMeC₆H₄]}][PF ₆] 6b, with regeneration of the C=N double bond, which, when treated with lithium tetrachloropalladate in methanol for 48 h, gave the novel compound [Pd(Ph₂P(CH₂)₂PPh₂){(CpFe) η⁵-C₅H[C(H)=NCy][C(H)=N(2-SMeC₆H ₄]}PdCl][PF₆] 7b, which is the first ferrocene metallacycle displaying 1,3-double cyclopalladation.

Full text of DOI:10.1021/om2008698

Article
pubs.acs.org/Organometallics
Dioxaneferrocenylimine Cyclometalated Compounds as Precursors
to Novel Functionalized Di- and Tetranuclear Metallacycles Leading
to 1,3-Double Palladation of an η5-C5H5 Ring
Marta Marino,† Javier Martínez,† Marcelo Caamano,† Ma Teresa Pereira,† Juan M. Ortigueira,†
̃
̃
Eduardo Gayoso,† Alberto Fernandez,‡ and Jose M. Vila*,†
́
́
†Departamento de Química Inorgan
‡Departamento de Química Fundamental, Universidade da Coruna, E-15071 La Coruna, Spain
́
ica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
̃
̃
ABSTRACT: Reaction of the Schiff base ligands CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)
NR] (R = 2,4,6-Me3C6H2, a; R = Cy, b) derived from the 1,2-disubstituted formylferrocene
CpFe[(CHO){C(H)O(CH2)3O}-η5-C5H3] 1, with Li2[PdCl4] in methanol at room temper-
ature for 48 h, gave the chlorine-bridged complexes [Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C-
(H)NR]}(Cl)]2, 1a and 1b, after C−H activation of the cyclopentadienyl ring bearing the
cyclic acetal. The reactions of 1a and 1b with the Ph2P(CH2)nPPh2 diphosphines in a 1:2 ratio,
plus addition of ammonium hexafluorophosphate, gave the dinucelar compounds [Pd{CpFe[η5-
C5H2{C(H)O(CH2)3O}C(H)NR]}-(Ph2P(CH2)nPPh2-P,P)][PF6] 2a, 3a and 2b, 3b with
the diphosphine in a chelating mode, as 1:1 electrolytes. Treatment of the latter with aqueous
acetic acid gave the corresponding functionalized compounds with transformation of the 1,3-
dioxane ring into a formyl group on the metalated ring, 4a, 5a and 4b, 5b.
The Schiff base condensation reaction of 5b with 2-(methylthio)aniline in refluxing chloroform gave [Pd(Ph2P(CH2)2PPh2)-
{(CpFe)η5-C5H2[C(H)NCy][C(H)N(2-SMeC6H4]}][PF6] 6b, with regeneration of the CN double bond, which, when
treated with lithium tetrachloropalladate in methanol for 48 h, gave the novel compound [Pd(Ph2P(CH2)2PPh2){(CpFe)η5-
C5H[C(H)NCy][C(H)N(2-SMeC6H4]}PdCl][PF6] 7b, which is the first ferrocene metallacycle displaying 1,3-double
cyclopalladation.
Nevertheless, regardless of the profuse chemistry related to
ferrocene palladacycles,15 examples of 2-fold cyclopalladation
on a single cyclopentadienyl ring remain outstanding, that is,
complexes with a tetradentate [2C(sp2, ferrocene), N, X]2− or
with a multidenate [2C(sp2, ferrocene), N, X, N, X]2− ligand;
albeit for phenyl rings, as much as a 3-fold cyclopalladation of a
single benzene ring has been reported.16 To achieve this, it
would first be necessary to introduce the donor atoms, other
than carbon, on the five-membered ring to give the 1,2-
disubstituted ferrocene. We reasoned that substitution by
formyl groups, followed by condensation with the appropriate
NH2 moieties, would be an adequate route for introducing the
appropriate nitrogen and sulfur donors, via formation of the
corresponding CN double bonds, followed by double
palladation. An alternative route would be the preparation of
ferrocene palladacyles bearing a free formyl group, in a similar
fashion to complexes reported by us earlier,17 condensation and
ulterior metalation. We envisaged the latter method as an
adequate route to meet our goal and, accordingly, herein we
report the results of the research that has led to the synthesis of
a series of new metallacycles: functionalized ferrocenylimine
cyclometalated palladium(II) complexes leading to the first 1,3-
dicyclopalladated bis(imine)ferrocene.
1. INTRODUCTION
Despite that cyclometalated complexes, particularly pallada-
cyles, have been abundantly researched for the past decades,
they continue to constitute one of the major topics within
organometallic chemistry, and they are well documented for a
great variety of ligands.1 They have been successfully used in
organic synthesis,2 photochemistry,3 optical resolution pro-
cesses,4,5 catalysis,6 as potential biologically active materials,7
and liquid crystals.8 One of the milestones that has greatly
contributed to widening the scope of these species is ferrocene;
in fact, although the preparation and characterization of
ferrocene, as well as the description of the metal-ring bonding,9
dates from the early 1950s, it is still a cornerstone for an ample
range of derivatives. Electrophilic substitution at the ring yields
species with added donor atoms that support coordination of
the ferrocene moiety to a metal center, thus greatly extending
its chemistry.10 One of the developments in this area has been
the cyclometalated ferrocene derivatives containing bidentate
[C(sp2, ferrocene), N]− and terdentate [C(sp2, ferrocene), N,
X]− (X = N, S, O) ligands; typical examples are the
ferrocenylimine11 and ferrocenylthiosemicarbazone12 pallada-
cyles. Their importance is put forward, to name but a few, in
their use as building blocks in macromolecular chemistry,13 or
as chiral discriminators,4 due to the prochiral nature that
activation of the C(sp2)H bond introduces in the ferrocenyl
unit.14
Received: September 19, 2011
Published: January 20, 2012
© 2012 American Chemical Society
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Article
substituted ring, with the latter one at the highest frequency
due to the anisotropic effect of the CN double bond, and a
singlet for the unsubstituted ring. Reaction of a or b with
Li2[PdCl4] in methanol gave 1a and 1b, respectively, as air-
stable solids, which were fully characterized (preparative details,
2. RESULTS AND DISCUSSION
The sequence of reactions leading to the compounds reported
in the present paper can be seen in Scheme 1. In our quest to
Scheme 1. (i) Li2[PdCl4], Methanol; (ii) 1:2
Ph2P(CH2)nPPh2/NH4PF6, Acetone; (iii) AcOH/H2O; (iv)
2-SMeC6H4NH2/CHCl3; (v) Li2[PdCl4]/NaAcO/MeOH (2,
4: n = 1; 3, 5: n = 2)
1
characterizing microanalytical, IR, and H and 13C NMR data
are in the Experimental Section). The υ(CN) band was
shifted to lower wavenumbers upon complex formation by ca.
60 cm−1, in agreement with coordination of the palladium atom
to the CN moiety through the nitrogen lone pair.19,20 The IR
spectrum showed two bands at ca. 330 and 260 cm−1 assigned
to the υ(Pd−Cl) stretches consequent on the differing trans
influence of the C,N donors. Accordingly, the 1H NMR showed
the characteristic high-frequency shift of the HCN
resonance, consequent of Pd−N bond formation,21 and the
absence of the H5 resonance after metalation of the
cyclopentadienyl ring. The results showed that only one set
1
of resonances was recorded in the H NMR spectra, despite
2
that the activation of the Csp −H bond in ferrocene introduces
planar chirality (Rp or Rs) in the ferrocenyl arrangement.22 The
13C-{1H} NMR spectra confirmed the assigned structures, with
downfield shifts of the CN, C1, and C5 resonances (the
latter, at ca. 30 ppm), confirming metalation of the ring. Also,
there was no noticeable quadrupolar broadening of the
resonances by coupling with the 105Pd (22% natural abundance,
I = 5/2) nucleus for these and for the remaining complexes
herein reported.
Treatment of 1a and 1b with bidentate tertiary phosphines
gave an array of dinuclear compounds after cleavage of the
Pd2X2 nucleus of the starting material, which kept the dioxane
moiety bonded to the ferrocene ring. Thus, reaction of 1a and
1b with diphosphines in a 1:2 molar ratio gave compounds 2a,
3a and 2b, 3b (see the Experimental Section). The complexes
were 1:1 electrolytes, as shown by molar conductivity
measurements in dry acetonitrile.23 The 31P NMR spectra
showed two doublets for the two nonequivalent phosphorus
nuclei; the resonance at lower frequency was assigned to the
phosphorus nucleus trans to the carbon atom, in agreement
with the differing trans influence of both C,N donors.24
The aforementioned phosphine complexes could be used to
prepare the hitherto outstanding functionalized ferrocenylimine
palladacycles bearing a formyl group on the C2 carbon atom of
the metalated cyclopentadienyl ring. This is reminiscent of
similar functionalized palladacycles obtained by us earlier;17,25
then, the HCO group was spontaneously formed upon
metalation of the ligand, although, in a later stage, double
palladation was later achieved through oxidative-addition
reactions in nonacidic media.26 However, in the present case,
the initial protection of the formyl group by acetalization
allowed us to produce the second group at will after the first
palladation of the ligand. Thus, treatment of 2a, 3a and 2b, 3b
with a mixture of aqueous acetic acid/acetone gave 4a, 5a and
4b, 5b as air-stable solids, which were fully characterized (see
the Experimental Section and Scheme 1). The main differences
with the spectroscopic data for the parent compounds was the
presence of the band assigned to the υ(CO) stretch in the IR
spectra; in the 1H NMR spectra, the absence of the resonances
for the dioxane ring protons, on the one hand, and a singlet at
ca. 10 ppm assignable to the HCO resonance, on the other;
and also the HCO resonance at ca. 194 ppm in the 13C NMR
spectra.
synthesize functionalized ferrocenylimine palladacycles and the
subsequent 1,3-dicyclopalladated species, we sought out to
prepare a 1,2-disubstituted formylferrocene and the subsequent
derivative comprising a protected formyl group, from which to
obtain the corresponding imine ligands. To attain this task, we
first prepared the 1,2-disubstituted CpFe[(CHO){C(H)O-
(CH2)3O}-η5-C5H3] 1, following the method of Bunz et al.,18
where an acetalization reaction protects the second formyl
moiety. Treatment of 1 with 2,4,6-trimethylaniline or cyclo-
hexylamine in refluxing chloroform gave ligands a and b,
respectively, as air-stable solids, which were fully characterized
(see the Experimental Section). The most important feature
was the characteristic υ(CN) band in the IR spectra at ca.
1
1630 cm−1 and, in the H NMR spectra, the HCN and
CHO2 resonances at ca. δ8.35 and δ5.63, respectively, as well as
four signals of relative intensities 1:1:1:5, three for the
cyclopentadienyl resonances H3, H4, and H5 from the
2.1. Dicyclometalated Compounds. Dicyclopalladated
and dicycloplatinated complexes derived from ferrocene have
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Article
been previously obtained.27 However, metalation followed a
1,1′-substitution pattern, with the ensuing metallacycles on
different cyclopentadienyl rings, most surely due to the
impossibility of situating the corresponding donor atoms,
other than carbon, on the same five-membered ring.
Notwithstanding, 1,3-dicyclopalladation of ferrocene may be
achieved through the functionalized compounds described
above, and we now detail our preliminary results concerning
the preparation and characterization of these new species that
open a new field in the chemistry of cyclometalated
compounds. Thus, Schiff base condensation of 5b with 2-
(methylthio)aniline in refluxing chloroform gave 6b with
regeneration of the CN double bond, as a stable solid,
which was completely characterized (see the Experimental
Section and Scheme 1). The IR and NMR spectra failed to
show any evidence for the formyl group put forward by the
absence of the υ(CO) stretch and the HCO (1H) and
HCO (13C) resonances, respectively. Instead, two υ(CN)
bands were observed at 1624 cm−1 (noncoordinated CN
group) and at 1601 cm−1 (coordinated CN group). The
NMR data exhibited a singlet resonance at δ8.37 (1H,
nonbonded CN group) and a doublet at δ8.15 (1H,
coordinated CN) with coupling of the imine proton to the
31P nucleus (4J(PH) = 8.0 Hz); a singlet at δ2.36 was assigned
to the SMe protons. Likewise, the 13C-{1H} NMR spectrum
showed two CN resonances at δ169.9 (coordinated CN)
and 158.3 (noncoordinated CN). The remaining resonances
were assigned accordingly.
Reaction of 6b with lithium tetrachloropalladate in methanol
for 48 h gave the hitherto unknown compound 7b displaying
1,3-double cyclopalladation of the ferrocene cyclopentadienyl
ring, as an air-stable solid (Scheme 1). Characterizing data for
7b are given in the Experimental Section. Cyclopalladation was
readily ascertained by IR and NMR spectroscopies. Accord-
ingly, the shift of the (CN) stretch toward lower wave-
numbers and the upfield shift of the HCN resonance in the
1H NMR spectrum supported nitrogen coordination to the
metal center.19−21 Two signals of relative intensities of 1:5 at
δ3.94 and δ4.43 in the 1H NMR spectrum were assigned to the
cyclopentadienyl resonances, the former for the sole proton of
the metalated ring and the latter for the five equivalent protons
of the unsubstituted ring; also, the SMe resonance was
downfield-shifted by ca. 0.5 ppm, in agreement with Pd−S
coordination. The 13C NMR spectrum showed the downfield
shift of the CN, C1, C2, and C3 resonances upon the second
metalation of the ferrocene ring, with the most noticeable
displacement at C3 at ca. 30 ppm, after metalation.
but the initial step in what we expect to be a new and wide
range of cyclometalated complexes, and the ensuing prepara-
tions are currently in progress.
4. EXPERIMENTAL SECTION
4.1. General Remarks. Solvents were purified by standard
methods.28 Reagents were used as supplied; CpFe[(CHO){C(H)O-
(CH2)3O}-η5-C5H3] was synthesized using the Bunz method.18 All
preparations were carried out under dry dinitrogen. Elemental analyses
were performed with a Fisons elemental analyzer, model 1108. IR
spectra were recorded as Nujol mulls or polythene discs on
PerkinElmer 1330, Mattson model Cygnus-100, and Bruker model
IFS-66 V spectrophotometers. 1H NMR spectra in solution were
recorded in CDCl3 at room temperature on a Varian Mercury 300
spectrometer operating at 300.14 MHz using 5 mm o.d. tubes;
chemical shifts, in parts per million, are reported downfield relative to
TMS using the solvent signal (CDCl3, δ1H = 7.26 ppm) as a reference.
31P NMR spectra were recorded at 202.46 MHz on a Bruker AMX 500
spectrometer using 5 mm o.d. tubes and are reported in parts per
million relative to external H3PO4 (85%). Coupling constants are
reported in hertz. The physical measurements were carried out by the
RIAIDT services of the Universidad de Santiago de Compostela.
4.2. Synthesis of the Ligands. CpFe[η5-C5H2{C(H)O(CH2)3O}-
C(H)N-2,4,6-Me3C6H2] (a). CpFe[1-(CHO)-2-{C(H)O(CH2)3O}-
η5-C5H3] (500 mg, 1.666 mmol) and 2,4,6-Me3C6H2NH2 (236 mg,
1.749 mmol) were added in chloroform (40 cm3). The resulting
solution was stirred under reflux for 8 h in a Dean−Stark apparatus.
The solvent was then removed under vacum and the product collected
as a red solid. Yield: 82%. Found: C, 69.2; H, 6.7; N, 3.5.
C24H27FeNO2 (417.32) requires C, 69.1; H, 6.5; N, 3.4. IR νmax
/
cm−1: 1630 s (CN). NMR 1H (CDCl3): δH = 8.35 (s, 1H, HCN),
6.91 (s, 1H, C6H2), 6.78 (s, 1H, C6H2), 5.63 (s, 1H, CHO2), 4.96 [dd,
1H, H5, 3J(H4H5) = 2.7 Hz, 4J(H3H5) = 1.4 Hz], 4.64 [dd, 1H, H3,
3J(H3H4) = 2.7 Hz, 4J(H3H5) = 1.4 Hz], 4.44 [t, 1H, H4, 3J(H4H5)
3
= 2.7 Hz, J(H3H4) = 2.7 Hz], 4.28 (s, 5H, C5H5), 4.19, 3.92, 2.11,
1,38 (m, 6H, CH2), 2.30 (s, 3H, Me), 2.22 (s, 3H, Me), 2.18 (s, 3H,
Me). NMR 13C (CDCl3): δC = 158.5 (CN), 146.1 (Ci), 129.2 (Cm),
128.9 (Cp), 126.4 (Co), 100.2 (C6), 85.4 (C1), 70.3 (C5), 70.1 (C4),
69.2 (C3), 67.4 (C2), 66.3 (C7), 25.1 (C8), 21.9, 18.9 (Me), 69.5 (Cp).
FAB-MS: m/z = 418 [MH]+.
Ligand b was prepared analogously.
CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NCy] (b): Yield: 95%. Found:
C, 66.6; H, 6.9; N, 3.6. C21H27FeNO2 (381.29) requires C, 66.2; H,
1
7.1; N, 3.7. IR νmax/cm−1: 1636 s (CN). NMR H (CDCl3): δH
=
8.34 (s, 1H, HCN), 5.62 (s, 1H, CHO2), 4.77 [dd, 1H, H5,
3J(H4H5) = 2.6 Hz, 4J(H3H5) = 1.7 Hz], 4.51 [dd, 1H, H3,
3J(H3H4) = 2.6 Hz, 4J(H3H5) = 1.7 Hz], 4.29 [t, 1H, H4, 3J(H4H5)
3
= 2.6 Hz, J(H3H4) = 2.6 Hz], 4.14 (s, 5H, C5H5), 4.22, 3.94, 2.19,
1.33 (m, 6H, CH2), 3.05 (m, 1H, H-Cy). NMR 13C (CDCl3): δC
=
158.8 (CN), 100.4 (C6), 86.3 (C1), 70.6 (C5), 70.4 (C4), 69.5 (C3),
68.7 (Ci), 67.4 (C2), 65.9 (C7), 24.8 (C8), 34.3, 25.6, 24.6 (Cy), 69.3
(Cp). FAB-MS: m/z = 382 [MH]+.
4.3. Synthesis of the Complexes. [Pd{CpFe[η5-C5H2{C(H)O-
(CH2)3O}C(H)N-2,4,6-Me3C6H2]}(Cl)]2 (1a). In a round-bottom 100
mL Schlenk flask, palladium(II) chloride (85 mg, 0.479 mmol) and
lithium chloride (41 mg, 0.958 mmol) were added together in
methanol (40 cm3). The resulting suspension was stirred for 2 h.
Ligand a (200 mg, 0.479 mmol) and sodium acetate were then added,
and the mixture was stirred for 48 h, after which a precipitate formed,
which was filtered off, washed with methanol, and dried under vacum.
Yield: 72%. Found: C, 51.8; H, 4.8; N, 2.8. C48H52N2Cl2Fe2O4Pd2
(1116.37 g/mol) requires C, 51.6; H, 4.7; N, 2.5. IR νmax/cm−1: 1577 s
(CN), 334 s, 267 m (Pd−Cl). NMR 1H (CDCl3): δH = 7.99 (s, 1H,
HCN), 6.96 (s, 1H, C6H2), 6.66 (s, 1H, C6H2), 4.64 (m, 1H, H3),
5.59 (s, 1H, CHO2), 4.59 (m, 1H, H4), 4.33 (s, 5H, C5H5), 4.12, 3.83,
2.52, 1.37 (m, 6H, CH2), 2.95 (s, 3H, Me), 2.30 (s, 3H, Me), 2.24 (s,
3H, Me). NMR 13C (CDCl3): δC = 167.6 (CN), 146.2 (Ci), 129.1
(Cm), 128.8 (Cp), 126.3 (Co), 101.2 (C5), 100.1 (C6), 95.2 (C1), 72.1
3. CONCLUSIONS
We have shown that ferrocenylimine palladacycles may be
obtained as complexes bearing a formyl group, provided that
the organic functionality is protected throughout the metalation
process. This is achieved in the present case by an acetalization
reaction prior to metalation, following the Bunz method, giving
cyclometalated compounds with a dioxane ring, which, after
controlled hydrolysis, yield the aforementioned derivatives. The
reaction between the functionalized palladacycle and a primary
amine, with formation of a CN double bond, and ulterior
treatment with a palladium(II) salt gives a trinuclear compound
presenting a 1,3-double metalated cyclopentadienyl ring from
the ferrocene moiety, a species that is a novelty in
cyclometalation chemistry. The results depicted herein are
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(C4), 72.0 (C3), 68.1 (C2), 66.2 (C7), 25.2 (C8), 21.2, 18.9 (Me), 70.7
(Cp). FAB-MS: m/z = 1116 [MH]+, 1081 [MH − Cl]+.
Hz), 6.69 (s, 1H, C6H2), 6.60 (s, 1H, C6H2), 4.46 (m, 1H, H3), 4.20
(s, 5H, C5H5), 4.06 (m, 1H, H4), 2.35 (s, 3H, Me), 2.32 (s, 3H, Me),
2.25 (s, 3H, Me). NMR 13C (CDCl3): δC = 194.4 (CO), 168.1
(CN), 145.9 (Ci), 135−126 (PPh2 + Cmesityl), 101.2 (C5), 94.1 (C1),
(CDCl3): δP = 54.4 (d, 2J(PP) = 23.1 Hz), 27.5 (d, 2J(PP) = 23.1 Hz).
FAB-MS: m/z = 848 [M − PF6]+.
Compound 1b was prepared similarly.
[Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NCy]}(Cl)]2 (1b): Yield:
62%. Found: C, 49.5; H, 5.8; N, 2.4. C42H52N2Cl2Fe2O4Pd2
(1044.31 g/mol) requires C, 48.3; H, 5.0; N, 2.7. IR νmax/cm−1:
1578 s (CN), 331 s, 250 m (Pd−Cl). NMR 1H (CDCl3): δH = 8.04
(s, 1H, HCN), 5.70 (s, 1H, CHO2), 4.64 (b, 1H, H3), 4.50 (b, 1H,
H4), 4.28 (s, 5H, C5H5), 4.21, 3.90, 2.41, 0.88 (m, 6H, CH2), 3.43 (m,
1H, H-Cy). NMR 13C (CDCl3): δC = 166.9 (CN), 100.2 (C6), 96.1
(C1), 100.5 (C5), 71.9 (C4), 72.0 (C3), 67.9 (C2), 67.5 (Ci), 66.0 (C7),
24.9 (C8), 34.3, 25.1, 24.8 (Cy), 70.6 (Cp). FAB-MS: m/z = 1044
[M]+.
71.7 (C4), 72.1 (C3), 68.3 (C2), 21.1, 18.7 (Me), 71.0 (Cp). NMR 31
P
[Pd{CpFe[η5-C5H2{C(H)O}C(H)N-2,4,6-Me3C6H2]}(Ph2P-
(CH2)2PPh2)][PF6] (5a). Yield: 86%. Found: C, 56.5; H, 4.6; N, 1.7.
C47H44NF6FeOP3Pd (1008.04 g/mol) requires C, 56.0; H, 4.4; N, 1.4.
IR νmax/cm−1: 1667 m (CO), 1601 w (CN). NMR 1H (CDCl3):
δH = 9.99 (s, 1H, CHO), 8.59 (d, 1H, HCN, 4J(PH) = 7.9 Hz), 6.37
(s, 1H, C6H2), 6.23 (s, 1H, C6H2), 5.03 (b, 1H, H3), 4.17 (b, 1H, H4),
4.10 (s, 5H, C5H5), 2.16 (s, 3H, Me), 2.11 (s, 3H, Me), 1.81 (s, 3H,
Me). NMR 13C (CDCl3): δC = 193.9 (CO), 167.7 (CN), 145.8
(Ci), 135−126 (PPh2 + Cmesityl), 100.1 (C5), 94.5 (C1), 72.3 (C4), 70.9
(C3), 68.4 (C2), 21.0, 18.7 (Me), 71.3 (Cp). NMR 31P (CDCl3): δP =
57.6 (d, 2J(PP) = 25.2 Hz), 44.3 (d, 2J(PP) = 25.2 Hz). FAB-MS: m/z
= 862 [M − PF6]+.
[Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)N-2,4,6-Me3C6H2]}(Ph2P-
(CH2)P-Ph2-P,P)][PF6] (2a). Compound 1a (30 mg, 0.026 mmol) and
Ph2P(CH2)PPh2 (20 mg, 0.052 mmol) were added together in acetone
(15 cm3). The mixture was stirred for 24. NH4PF6 was then added,
and stirring continued for 1 h. Addition of water produced a
precipitate that was filtered off, dried under vacum, and recrystallized
from dichloromethane/hexane. Yield: 44%. Found: C, 55.7; H, 4.4; N,
1.5. C49H48NF6FeO2P3Pd (1052.09 g/mol) requires C, 55.9; H, 4.6;
N, 1.3. IR νmax/cm−1: 1575 m (CN). NMR 1H (CDCl3): δH = 8.34
[Pd{CpFe[η5-C5H2{C(H)O}C(H)NCy]}(Ph2PCH2PPh2)][PF6] (4b):
Yield: 78%. Found: C, 54.7; H, 4.3; N, 1.8. C43H42NF6FeOP3Pd
(957,98 g/mol) requires C, 53.9; H, 4.4; N, 1.5. IR νmax/cm−1: 1721 w
1
4
(CO), 1590 m (CN). NMR H (CDCl3): δH = 9.91 (s, 1H,
(d, 1H, HCN, J(PH) = 7.9 Hz), 6.68 (s, 2H, C6H2), 5.45 (s, 1H,
3
CHO), 5.21 [d, 1H, H3, J(H3H4) = 2.4 Hz], 4.41 (s, 5H, C5H5),
CHO2), 4.27 (b, 1H, H3), 4.32, 3.88 (m, 6H, CH2), 4.15 (s, 5H,
C5H5), 3.72 (b, 1H, H4), 2.38 (s, 3H, Me), 2.30 (s, 3H, Me), 2.06 (s,
3H, Me). NMR 13C (CDCl3): δC = 167.2 (CN), 146.0 (Ci), 135−
126 (PPh2 + Cmesityl), 102.0 (C5), 100.0 (C6), 95.1 (C1), 72.3 (C4),
71.9 (C3), 68.0 (C2), 66.1 (C7), 25.0 (C8), 20.9, 18.7 (Me), 70.9 (Cp).
NMR 31P (CDCl3): δP = 51.3 (d, 2J(PP) = 20.1 Hz), 27.2 (d, 2J(PP) =
20.1 Hz). FAB-MS: m/z = 907 [MH − PF6]+.
4.28 [d, 1H, H4, 3J(H3H4) = 2.4 Hz]. NMR 13C (CDCl3): δC = 194.1
(CO), 167.5 (CN), 135.1, 131.3, 128.4, 125.1 (PPh2),101.4 (C5),
95.1 (C1), 73.0 (C4), 72.0 (C3), 68.9 (C2), 68.2 (Ci), 33.9, 25.9, 24.7
(Cy), 71.4 (Cp). NMR 31P (CDCl3): δP = 28.4 (d, 2J(PP) = 52.0 Hz),
2
−2.2 (d, J(PP) = 52.0 Hz). FAB-MS: m/z = 812 [M − PF6]+.
[Pd{CpFe[η5-C5H2{C(H)O}C(H)NCy]}(Ph2P(CH2)2PPh2)][PF6] (5b):
Yield: 79%. Found: C, 55.1; H, 4.5; N, 1.7. C44H44NF6FeOP3Pd
(972.00 g/mol) requires C, 54.4; H, 4.6; N, 1.4. IR νmax/cm−1: 1719 m
Compounds 3a, 2b, and 3b were synthesized analogously.
[Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)N-2,4,6-Me3C6H2]}(Ph2P-
(CH2)2P-Ph2-P,P)][PF6] (3a): Yield: 39%. Found: C, 56.8; H, 4.4; N,
1.4. C50H50NF6FeO2P3Pd (1066.11 g/mol) requires C, 56.3; H, 4.7;
N, 1.3. IR νmax/cm−1: 1572 w (CN). NMR 1H (CDCl3): δH = 8.34
1
(CO), 1601 m (CN). NMR H (CDCl3): δH =10.36 (s, 1H,
3
CHO), 5.22 [d, 1H, H3, J(H3H4) = 2.7 Hz], 4.40 (s, 5H, C5H5),
3.97 (b, 1H, H4). NMR 13C (CDCl3): δC = 194.2 (CO), 170.0
(CN), 135.0, 130.2, 128.5, 126.1 (PPh2), 102.3 (C5), 94.8 (C1),
72.9 (C4), 71.7 (C3), 68.8 (C2), 68.0 (Ci), 33.8, 25.8, 24.9 (Cy), 71.7
4
(d, 1H, HCN, J(PH) = 8.1 Hz), 6.43 (s, 1H, C6H2), 6.20 (s, 1H,
C6H2), 5.44 (s, 1H, CHO2), 4.59 (b, 1H, H3), 4.17, 3.88, 1.42 (m, 6H,
CH2), 4.04 (s, 5H, C5H5), 3.73 (b, 1H, H4), 2.21 (s, 3H, Me), 2.11 (s,
3H, Me), 1.78 (s, 3H, Me). NMR 13C (CDCl3): δC = 166.9 (CN),
146.3 (Ci), 135−125 (PPh2 + Cmesityl), 101.7 (C5), 100.5 (C6), 96.4
(C1), 72.4 (C4), 71.8 (C3), 68.1 (C2), 66.4 (C7), 25.2 (C8), 22.3, 19.1
(Me), 70.8 (Cp). NMR 31P (CDCl3): δP = 56.7 (d, 2J(PP) = 26.8 Hz),
2
(Cp). NMR 31P (CDCl3): δP = 57.4 (d, J(PP) = 26.3 Hz); 42.3 (d,
2J(PP) = 26.3 Hz). FAB-MS: m/z = 826 [M − PF6]+.
[Pd(Ph2P(CH2)2PPh2){(CpFe)η5-C5H2[C(H)NCy][C(H)N(2-
SMeC6H4]}][PF6] (6b). Compound 5b (40 mg, 0.041 mmol) and 2-
methylthioaniline (5.7 mg, 0.042 mmol) in benzene were heated
together under reflux in a Dean−Stark apparatus. After cooling and
evaporation of the solvent, the desired product was obtained as a red
solid. Yield: 81%. Found: C, 56.1; H, 4.6; N, 2.6; S, 2.8.
C51H51N2F6FeP3PdS (1093.19 g/mol) requires C, 56.0; H, 4.7; N,
2.6; S, 2.9. IR νmax/cm−1: 1624 m, 1601 m (CN). NMR 1H
(CDCl3): δH = 8.37 (s, 1H, HCN), 8.15 (d, 1H, HCN, 4J(PH) =
8.0 Hz), 7.00 (m, 4H), 5.28 [d, 1H, H3, 3J(H3H4) = 2.9 Hz], 4.38 (s,
5H, C5H5), 4.01 (b, 1H, H4), 2.36 (s, 3H, SMe). NMR 13C (CDCl3):
δC = 169.9, 158.3 (CN), 150.1 (C1′), 135−124 (PPh2 + Cthioaniline),
118.0 (C3′), 101.4 (C5), 93.9 (C1), 84.9 (C2), 71.8 (C4), 71.5 (C3),
68.1 (Ci), 34.0, 25.0, 24.9 (Cy), 24.5 (SMe), 71.9 (Cp). NMR 31P
(CDCl3): δP = 57.2 (d, 2J(PP) = 26.0 Hz), 42.5 (d, 2J(PP) = 26.0 Hz).
FAB-MS: m/z = 947 [M − PF6]+.
2
42.3 (d, J(PP) = 26.8 Hz). FAB-MS: m/z = 922 [MH − PF6]+.
[Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NCy]}(Ph2P(CH2)P-Ph2-
P,P)][PF6] (2b): Yield: 50%. Found: C, 54.0; H, 4.9; N, 1.6.
C46H48NF6FeO2P3Pd (1016.06 g/mol) requires C, 54.4; H, 4.8; N,
1.4. IR νmax/cm−1: 1590 w (CN). NMR 1H (CDCl3): δH = 8.47 (d,
4
1H, HCN, J(PH) = 8.4 Hz), 5.29 (s, 1H, CHO2), 4.51 (b, 1H,
H3), 3.95, 3.57 (m, 6H, CH2), 4.04 (s, 5H, C5H5), 3.85 (b, 1H, H4),
3.31 (m, 1H, H-Cy). NMR 13C (CDCl3): δC = 172.2 (CN), 133.9,
131.0, 128.3, 127.5 (PPh2), 101.4 (C6), 102.1 (C5), 93.3 (C1), 72.3
(C4), 71.8 (C3), 68.4 (C2), 67.9 (Ci), 65.8 (C7), 24.9 (C8), 34.5, 25.2,
2
25.0 (Cy), 71.1 (Cp). NMR 31P (CDCl3): δP = 30.4 (d, J(PP) = 52
2
Hz); −4.7 (d, J(PP) = 52.0 Hz). FAB-MS: m/z = 870 [M − PF6]+.
[Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NCy]}(Ph2P(CH2)2PPh2-
P,P)][PF6] (3b): Yield: 60%. Found: C, 55.3; H, 4.8; N, 1.5.
C47H50NF6FeO2P3Pd (1030.08 g/mol) requires C, 54.8; H, 4.9; N,
1.4. IR νmax/cm−1: 1591 w (CN). NMR 1H (CDCl3): δH = 8.52 (d,
[Pd(Ph2P(CH2)2PPh2){(CpFe)η5-C5H[C(H)NCy][C(H)N(2-
SMeC6H4]}PdCl]-[PF6] (7b). Compound 6b (50 mg, 0.046 mmol),
Li2[PdCl4] (11.3 mg, 0.043 mmol) (prepared in situ from PdCl2 and
LiCl), and sodium acetate (24.6 mg, 0.3 mmol) were added in
methanol (30 cm3). The mixture was stirred for 48 h at room
temperature under nitrogen. The resulting red precipitate was filtered
off, washed with ethanol, and dried. Yield: 52%. Found: C, 49.4; H,
4.2; N, 2.2; S, 2.6. C51H50N2ClF6FeP3Pd2S (1234.03 g/mol) requires
C, 49.6; H, 4.1; N, 2.3; S, 2.6. IR νmax/cm−1: 1605 m, 1601 m (CN).
NMR 1H (CDCl3): δH = 8.17 (s, 1H, HCN), 8.10 (d, 1H, HCN,
4
1H, HCN, J(PH) = 9.4 Hz), 5.42 (s, 1H, CHO2), 4.45 (b, 1H,
H3), 4.20 (m, 6H, CH2), 3.93 (s, 5H, C5H5), 3.61 (b, 1H, H4), 2.90
(m, 1H, H-Cy). NMR 13C (CDCl3): δC = 171.1 (CN), 101.3 (C6),
134.2, 130.1, 129.5, 127.1 (PPh2), 102.3 (C5), 93.7 (C1), 72.0 (C4),
71.8 (C3), 68.2 (C2), 67.8 (Ci), 65.9 (C7), 25.0 (C8), 34.2, 25.7, 25.1
(Cy), 71.5 (Cp). NMR 31P (CDCl3): δP = 57.2 (d, 2J(PP) = 26.8 Hz);
2
44.5 (d, J(PP) = 26.8 Hz). FAB-MS: m/z = 884 [M − PF6]+.
3
4J(PH) = 7.9 Hz), 8.04 (d, 1H, H6′, J(H6′H5′) = 7.9 Hz), 7.95 (d,
[Pd{CpFe[η5 -C5 H2 {C(H)O}C(H)N-2,4,6-Me3 C6 H2 ]}-
(Ph2PCH2PPh2)][PF6] (4a): Yield: 88%. Found: C, 56.1; H, 4.5; N, 1.7.
C46H42NF6FeOP3Pd (994.01 g/mol) requires C, 55.6; H, 4.3; N, 1.4.
IR νmax/cm−1: 1726 w (CO), 1591 sh,m (CN). NMR 1H
(CDCl3): δH = 9.99 (s, 1H, CHO), 8.59 (d, 1H, HCN, 4J(PH) = 8.1
1H, H3′, 3J(H3′H4′) = 8.1 Hz), 3.91 (b, 1H, H4), 4.43 (s, 5H, C5H5),
2.81 (s, 3H, SMe). NMR 13C (CDCl3): δC = 172.2, 170.1 (CN),
147.9 (C1′), 135.6−123 (PPh2 + Cthioaniline), 117.5 (C3′), 102.7 (C3),
101.8 (C5), 99.5 (C1), 90.4 (C2), 73.6 (C4), 67.8 (Ci), 33.7, 25.3, 24.8
893
dx.doi.org/10.1021/om2008698 | Organometallics 2012, 31, 890−894

Organometallics
Article
(Cy), 26.7 (SMe), 71.5 (Cp). NMR 31P (CDCl3): δP = 57.0 (d, 2J(PP)
(15) Perez, S.; Lopez, C.; Caubet, A.; Solans., X.; font-Bardía, M.;
Roig, A.; Molíns, E. Organometallics 2006, 25, 596 andreferences
therein.
́
́
́
2
= 26.2 Hz), 42.1 (d, J(PP) = 26.2 Hz). FAB-MS: m/z = 1089 [M −
PF6]+.
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́
ez-Torres, M.;
AUTHOR INFORMATION
■
́
́
Corresponding Author
*E-mail: josemanuel.vila@usc.es.
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ACKNOWLEDGMENTS
■
We thank the Xunta de Galicia (projects 10DPI209017PR and
10PXIB209226PR) for financial support. J.M. acknowledges an
Isidro Parga Pondal contract from the Xunta de Galicia. A small
sample of 1 was kindly supplied by Dr. W. Steffen for an initial
trial, for which we are greatly indebted.
́ ́
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