Synthesis of palladium(II), -(III), and -(IV) complexes with acyclic diaminocarbene ligands

Article abstract of DOI:10.1021/om300201s

The reaction of [PdI{C,N-C(=NHXy)C₆H₄NH ₂-2}CNXy]TfO with XyNC (1:2, TfO = CF₃SO₃, Xy = C₆H₃Me₂-2,6) gives the cationic carbene complex [PdI{C,C-C(=NHXy)C₆H₄{NHC(NHXy)}-2}CNXy]TfO (4), while that of [PdCl₂{C(=NHXy)C₆H₄NH ₂-2}] with isocyanides (1:1, 50-60 °C) gives the neutral carbene complexes [PdCl₂{C,C-C(=NHXy)C₆H₄{NHC(NHR)}-2}] (R = ^tBu (8), Xy (9)), from which mono- and dicationic derivatives [PdCl{C,C-C(=NHXy)C₆H₄{NHC(NHXy)}-2}L]X (L = XyNC, X = TfO (10); L = PPh₃, X = Cl (11)) and [Pd{C,C-C(=NHXy)C₆H ₄{NHC(NHXy)}-2}(CNXy)₂](TfO)₂ (12), respectively, have been isolated. Dehydrochlorination of complex 9 with TlTfO and NaOAc (1:2:2) or with NEt₃ (1:1) affords the dinuclear complexes [(PdX)₂{μ-N,C,C-C(=NXy)C₆H₄{NHC(NHXy)}-2} ₂] (X = OAc (13), Cl (14)), which in turn react with PPh₃ to give [PdX{C,C-C(=NXy)C₆H₄{NHC(NHXy)}-2}PPh₃] (X = OAc (15), Cl (16)). Oxidative addition of 2-iodobenzoic acid to 13 leads to the Pd(IV) complex [{PdI(C₆H₄CO₂-2)} ₂{μ-N,C,C-C(=NXy)C₆H₄{NHC(NHXy)}-2} ₂] (17), while the reaction of 14 with PhICl₂ affords the Pd(III) derivative [(PdCl₂)₂{μ-N,C,C-C(=NXy)C ₆H₄{NHC(NHXy)}-2}₂] (18). The crystal structures of 4, 9, and 12 have been determined, and the atomic connectivity in 18 has been established.

Full text of DOI:10.1021/om300201s

Article
pubs.acs.org/Organometallics
Synthesis of Palladium(II), -(III), and -(IV) Complexes with Acyclic
Diaminocarbene Ligands
́ ́
Antonio-Jesus Martınez-Martınez, María-Teresa Chicote,* Delia Bautista, and Jose
́ ́
Vicente*,†
†
,†
‡
†
Grupo de Quım
́ ́
ica Organometalica, Departamento de Quımica Inorganica, Facultad de Quımica, Universidad de Murcia, Apartado
́ ́ ́
4
021, 30071 Murcia, Spain
‡
SAI, Facultad de Quım
́
ica, Universidad de Murcia, Apartado 4021, 30071 Murcia, Spain
*
S Supporting Information
ABSTRACT: The reaction of [PdI{C,N-C(NHXy)C H NH -
6
4
2
2
}CNXy]TfO with XyNC (1:2, TfO = CF SO , Xy = C H Me -2,6)
3 3 6 3 2
gives the cationic carbene complex [PdI{C,C-C(NHXy)-
C H {NHC(NHXy)}-2}CNXy]TfO (4), while that of [PdCl {C-
6
4
2
(
NHXy)C H NH -2}] with isocyanides (1:1, 50−60 °C) gives
6
4
2
the neutral carbene complexes [PdCl {C,C-C(NHXy)-
2
t
C H {NHC(NHR)}-2}] (R = Bu (8), Xy (9)), from which
6
4
mono- and dicationic derivatives [PdCl{C,C-C(NHXy)-
C H {NHC(NHXy)}-2}L]X (L = XyNC, X = TfO (10); L =
6
4
PPh , X = Cl (11)) and [Pd{C,C-C(NHXy)C H {NHC(NHXy)}-2}(CNXy) ](TfO) (12), respectively, have been isolated.
3
6
4
2
2
Dehydrochlorination of complex 9 with TlTfO and NaOAc (1:2:2) or with NEt (1:1) affords the dinuclear complexes
3
[
(PdX) {μ-N,C,C-C(NXy)C H {NHC(NHXy)}-2} ] (X = OAc (13), Cl (14)), which in turn react with PPh to give
2
6
4
2
3
[
PdX{C,C-C(NXy)C H {NHC(NHXy)}-2}PPh ] (X = OAc (15), Cl (16)). Oxidative addition of 2-iodobenzoic acid to 13
6 4 3
leads to the Pd(IV) complex [{PdI(C H CO -2)} {μ-N,C,C-C(NXy)C H {NHC(NHXy)}-2} ] (17), while the reaction of
6
4
2
2
6
4
2
1
4 with PhICl affords the Pd(III) derivative [(PdCl ) {μ-N,C,C-C(NXy)C H {NHC(NHXy)}-2} ] (18). The crystal
2
2 2
6
4
2
structures of 4, 9, and 12 have been determined, and the atomic connectivity in 18 has been established.
INTRODUCTION
Since the pioneering works of Wanzlick, Ofele, and Lappert,
the chemistry of complexes with N-heterocyclic carbene ligands
NHCs) has experienced a great development, particularly
Scheme 1
■
1
2
3
̈
4
(
5
during the past few years. This can be attributed to their
6
7
applications, mostly as catalysts.
Complexes with acyclic diaminocarbene ligands (ADCs)
have attracted much less attention than those with NHCs, in
spite of the fact that they are almost contemporary and their
synthesis, by attack of amines at isocyanide metal complexes, is
8
9,10
easier. Later on, when the first stable ADC was reported,
a
reaction occurs in the opposite direction: that is, by reacting a
chelating o-amino(iminiumbenzoyl) complex of type A with an
isocyanide to give B followed by the attack of the amino group
at the coordinated isocyanide (Scheme 1). We have reported
few complexes were also prepared by coordination of the ligand
10−13
to a variety of metals.
palladium complexes are equally
catalysts in various processes has triggered interest in these
The recent recognition that ADC
14,15
16,17
or even more
efficient
2
2,23
1
8,19
the unique complexes of types A and B
corresponding deprotonated iminobenzoyl derivatives,
as well as their
compounds.
The advantages of using ADC complexes as
2
3,24
catalysts reside in their larger N−C−N carbene bond angle,
which can be isolated in spite of bearing both amine and
isocyanide ligands. In this work we report the conditions under
which the unprecedented intramolecular addition of an amine
to an isocyanide ligand takes place. We have described a related
process in the synthesis of a Pd(II) complex containing a
making them more sterically demanding and strongly
1
3,20
donating,
and in their steric flexibility. These differentiating
features allow an easier tuning of the catalytic properties of
1
2,17,19
ADC complexes.
Recently, a mixed gold(I) complex with
21
both types of ligands has been reported.
C,N,C-pincer (iminobenzoyl)imidocarbene ligand, [Pd-
In this paper, we describe the first complexes containing a
chelating C,C-(iminiumbenzoyl)carbene ligand (type C,
Scheme 1). In contrast with the main method for the synthesis
of ADC complexes, which involves the attack of an added
amine at a coordinated isocyanide, in the present case, the
3
{
κ C,N,C-C(NXy)C H {NC(O)N(Tol)C(NHXy)}-2}-
6
4
Received: March 12, 2012
Published: May 2, 2012
©
2012 American Chemical Society
3711
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Article
CNXy], by reacting with base an iminobenzoyl(isocyanide)
acetophenone reaction, which showed it to be the carbene
14
complex derived from an ortho-palladated arylurea.
The recent interest in the study of organic reactions catalyzed
complex [PdI{C,C-C(NHXy)C H {NHC(NHXy)}-2}-
6
4
CNXy]TfO (4; Scheme 2). As we assumed the formation of
4 to occur through the intermediacy of 2, the equilibrium 3 +
XyNC ⇆ 2 must be very displaced to the left due to the
insolubility of 3 and the reactions 2 → 4 and 2 + MeC(O)Ph
→ D (R = Me, R′ = Ph) must be slow. Otherwise, as both are
probably irreversible, they would afford 4 and D as the only
reaction products. Correspondingly, we could isolate 4 by
reacting 3, in a chlorinated solvent, with 2 equiv of XyNC (70%
yield) or when the 1:1 reaction mixture was heated at 60 °C for
2
5,26
by organo-Pd(IV) complexes
number of such complexes in the literature.
only a few isolated organometallic Pd(III) complexes have been
is behind the growing
2
5,27−30
In contrast,
3
1
reported. We have recently described the synthesis and
reactivity of the first family of Pd(IV) pincer complexes, the
29
unprecedented synthesis of a Pd(IV) complex by addition of an
27
aryl iodide, namely 2-iodobenzoic acid, to a Pd(II) complex,
and its involvement in a Pd(II)/Pd(IV) catalytic cycle in a
32
t
Heck-type reaction. In this paper, we describe the synthesis of
the first ADC complexes of Pd(IV) and Pd(III). Both were
obtained by oxidative addition, using 2-iodobenzoic acid and
5 h (76% crude yield). The reaction of 3 with BuNC produced
a complex mixture from which we could not separate or identify
any species.
PhICl , respectively. While the former is also the first dinuclear
Given that complex 1 does not transform into a carbene
complex, even when heated, while its conjugate acid 2 does, we
assumed that other iminiumacyl isocyanide complexes, such as
2
organo-Pd(IV) complex, for Pd(III) complexes this is the usual
nuclearity, because of their tendency to form diamagnetic
species with a metal−metal bond. Only two Pd(IV) complexes
t
[PdCl {C(NHXy)C H NH -2}(CNR)] (R = Bu (5), Xy
2
6
4
2
2
8,33
containing NHC ligands have been recently reported.
(6); Scheme 3), which we prepared from [PdCl {C,N-C(
2
RESULTS AND DISCUSSION
Antecedents. As mentioned above, we have isolated
iminiumbenzoyl complexes of type B (Scheme 1),
Scheme 3
■
2
2,23
as well
as some of their deprotonated derivatives (iminobenzoyl
complexes; for example, trans-[PdI{C(NXy)C H NH -2}-
6
4
2
2
3,24
(
CNXy) ] (1; Scheme 2)
that, in spite of containing both
2
an isocyanide ligand and an amine group, do not evolve to give
ADC complexes.
Scheme 2
22
NHXy)C H NH -2] (7) and RNC, could behave similarly.
6
4
2
However, as they were stable at room temperature, we refluxed
them in CHCl , obtaining the complexes [PdCl {C,C-C(
3
2
t
NHXy)C H (NHC(NHXY))-2}CNR] (R = Bu (8),
6
4
C H Me -2,6 = Xy (9); 65−70% yield). Alternatively, these
6
3
2
22
complexes could be prepared by refluxing a mixture of 7 and
equiv of RNC or by using 2 equiv or more of XyNC at room
1
temperature. The above results seem to confirm that
protonation of the iminoacyl group increases the electro-
philicity of the isocyanide carbon atom bonded to Pd,
facilitating the nucleophilic attack of the amino group. It also
appears that the positive charge of 2 helps such an attack
because (1) its conjugate base 1 does not give a carbene
complex and (2) complex 4 forms from the cationic 2 at room
temperature while formation of 8 and 9 requires refluxing
In an attempt to isolate in CH Cl the complex [PdI{C(
2
2
NHXy)C H NH -2}(CNXy) ]TfO (2; Scheme 2), the sup-
6
4
2
2
posed intermediate in the synthesis of dihydroquinazolinium
complexes of type D from 1 and a carbonyl compound, the
complex [PdI{C,N-C(NHXy)C H NH -2}CNXy]TfO (3)
CHCl solutions of the neutral complexes 5 and 6.
6
4
2
3
23
precipitated instead. With the same purpose, 3 was reacted
Homologues of 4, [PdCl{C,C-C(NHXy)C H {NHC-
6
4
with 1.2 equiv of XyNC in CH Cl but a mixture was obtained
(NHR)}-2}(L)]X (X = TfO, L = XyNC (10); X = Cl, L =
2
2
containing 3 and a small amount of another product (X) that
we could not separate or characterize. Traces of X were also
detected in the reaction between 1, HTfO, and acetophenone,
which mainly gave 3 and the corresponding dihydroquinazo-
linium complex of type D (Scheme 2; R = Me, R′ = Ph). We
concluded that X formed by decomposition of 2.
Synthesis of Carbene Complexes. Complex X was
identified by an X-ray diffraction study using a single crystal
obtained from the mother liquor of the 1 + HTfO +
PPh (11); Scheme 3), were prepared by reacting 9 with XyNC
3
and TlTfO (1:1:1) at room temperature or with PPh (1:2) at
3
120 °C, respectively. The dicationic carbene complex [Pd{C,C-
C(NHXy)C H {NHC(NHR)}-2}(CNXy) ](TfO) (12;
6
4
2
2
Scheme 4) could be prepared by reacting XyNC and TlTfO
with 4 or 10 (1:1:1), but the easiest way is the reaction of 7
with XyNC and TlTfO in a 1:3:2 molar ratio.
A dehydrochlorination process can be effected in complex 9
by reacting it in two steps with TlTfO and, after removing TlCl,
3
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Scheme 4
Scheme 6
with NaOAc (1:2:2) or with NEt (1:1) to give respectively the
3
complexes [(PdX) {μ-N,C,C-C(NXy)C H {NHC(NHXy)}-
2
6
4
2
} ], where X = OAc (13), Cl (14) (Scheme 5). We
2
immediate precipitation of [(PdCl ) {μ-N,C,C-C(NXy)-
C H {NHC(NHXy)}-2} ] (18) as a crystalline red solid,
6 4 2
2
2
Scheme 5
which is stable in solution only for a short period of time,
13
precluding the measurement of a C NMR spectrum (Scheme
). The reaction produced the same result when 1 or 2 equiv or
6
1
more of PhICl was used. The elemental analyses, H NMR,
2
and a preliminary X-ray crystal structure determination (see
below) agree with the formulation of 18 as a Pd(III) dinuclear
complex.
Complexes 4, 9, 11, 13, and 14 crystallized with various
amounts of water, in spite of being heated in a vacuum oven.
The water content deduced from their elemental analyses was
1
confirmed in all cases by their H NMR spectra. Complex 18
could not be heated because of its instability, and according to
its elemental analyses, it crystallized with one molecule of
CHCl , as could be confirmed by integration of the CHCl
unsuccessfully attempted to synthesize 13 in one step from 9
and NaOAc (1:2), probably because of the poor solubility of
NaOAc. The reaction of complexes 13 and 14 with 2 equiv of
3
3
resonance, relative to the TMS, in the CDCl /TMS solvent and
3
in a CDCl /TMS solution of 18.
3
PPh caused bridge splitting, giving rise to the mononuclear
X-ray Crystal Structures. The crystal structures of
3
complexes [PdX{C,C-C(NXy)C H {NHC(NHXy)}-
complexes 4·CHCl (Figure 1), 9·0.5CHCl (Figure 2), and
6
4
3
3
2
}PPh ] (X = OAc, (15), Cl (16)), which were isolated in
12 (Figure 3) have been determined by X-ray diffraction. An
3
good yield.
attempt to measure the crystal structure of 18·2CHCl allowed
3
We have recently shown, for the first time, that a Pd(IV)
complex could be obtained by oxidative addition of an aryl
iodide, namely 2-iodobenzoic acid, to a pincer(acetato) Pd(II)
us to establish the atomic connectivity only (Figure 4). The
structure could not be refined because it contains a poorly
resolved region of residual electron density around the center
2
7
complex. The reaction produced a Pd(IV) complex bearing a
of symmetry, likely due to CHCl , that could not be adequately
3
iodo and a chelating C,O-C H CO -2 ligand, with liberation of
modeled or removed using the SQUEEZE procedure in
6
4
2
acetic acid. On the basis of this experience, we decided to study
the reaction of 13 with 2-iodobenzoic acid and found that,
working under a nitrogen atmosphere at 0 °C, the dinuclear
Pd(IV) complex [{PdI(C H CO -2)} {μ-N,C,C-C(NXy)-
PLATON. In 9·0.5CHCl there are two asymmetric units in
3
the unit cell. In all cases, the metal atom is in a square-planar
environment, slightly distorted because of the small bite of the
C,C-chelate (C(1)−Pd(1)−C(11)). In all complexes, the
carbene fragment adopts the E configuration. The Xy group
in the iminiumbenzoyl fragment is folded toward the aryl group
in complex 9, but it points toward the palladium moiety in 4
and 12. This difference could be explained by the involvement
of the imino N(3)−H fragment in hydrogen bonding in 9. In
complexes 4 and 9, the C−N bond distances within the carbene
fragment are intermediate between the standard mean values
6
4
2
2
C H {NHC(NHXy)}-2} ] (17) could be isolated in 71%
6
4
2
yield after a short reaction time (Scheme 6). The compound is
rather insoluble and unstable; the solid can be stored for a few
days below −30 °C, under a nitrogen atmosphere. The
1
13
elemental analyses and the H and C NMR spectra, as well as
the HRMS (ESI) spectrum measured on a freshly prepared
CH Cl solution containing 13 and 2-iodobenzoic acid in 1:2
2
2
2
2
34
molar ratio, fully agree with the formulation proposed for 17
found for single and double C(sp )−N(sp ) bonds, in
agreement with the expected electron delocalization over the
N(1)−C(1)−N(2) moiety. However, in complex 12, the
predominant contribution of the N(1)−C(1)N(2) reso-
nance form is apparent. On the other hand, although the
iminiumacyl moiety in all these complexes could be also
considered as an aminocarbene ligand, the C(11)−N(3) bond
(
see below).
We studied also the oxidation of 14 with PhICl at 0 °C
2
using a very small volume of solvent in order to avoid the
reverse reaction favored by the evolution of Cl2 upon
concentration. One minute after the reagents were mixed, the
addition of a cold mixture of Et O and n-pentane caused
2
3
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Figure 1. Crystal structure of 4·CHCl . The solvent and hydrogen
Figure 3. Crystal structure of 12. The solvent and hydrogen atoms are
omitted for clarity. The thermal ellipsoids are displayed at the 50%
probability level. Selected bond lengths (Å) and angles (deg): Pd(1)−
C(1) = 2.026(2), Pd(1)−C(11) = 1.988(2), Pd(1)−C(21) =
2.013(2), Pd(1)−C(31) = 2.057(2), N(1)−C(1) = 1.343(3), N(2)−
C(1) = 1.313(3), N(3)−C(11) = 1.300(3), C(11)−C(42) = 1.462(3);
C(11)−Pd(1)−C(1) = 85.39(8), C(11)−Pd(1)−C(21) = 92.66(9),
C(21)−Pd(1)−C(31) = 87.53(9), C(1)−Pd(1)−C(31) = 93.94(8),
N(2)−C(1)−N(1) = 117.69(19), C(11)−N(3)−C(12) = 126.36(19).
3
atoms are omitted for clarity. The thermal ellipsoids are displayed at
the 50% probability level. Selected bond lengths (Å) and angles (deg):
Pd(1)−C(1) = 2.025(6), Pd(1)−C(11) = 1.982(5), Pd(1)−C(21) =
1.997(6), C(1)−N(1) = 1.335(7), C(1)−N(2) = 1.330(7), C(11)−
N(3) = 1.293(7), C(11)−C(42) = 1.457(7), Pd(1)−I(1) = 2.6621(6);
C(11)−Pd(1)−C(1) = 85.3(2), C(11)−Pd(1)−C(21) = 92.0(2),
C(1)−Pd(1)−I(1) = 93.54(15), C(21)−Pd(1)−I(1) = 89.31(15).
Figure 4. Atomic connectivity in 18.
Figure 2. Crystal structure of 9·0.5CHCl . The solvent and hydrogen
3
atoms are omitted for clarity. The thermal ellipsoids are displayed at
the 50% probability level. Selected bond lengths (Å) and angles (deg):
Pd(1)−C(1) = 1.955(5), Pd(1)−C(11) = 1.974(5), C(1)−N(1) =
4
·CHCl , the cation and the triflate anion are connected
3
... ...
through classical N−H O and nonclassical C−H O hydrogen
bonds giving double chains along b axis (Figure 1, right). In 12,
the cation (Figure 3, top left) and the triflate anions are
connected through two N−H···O and two C−H···O hydrogen
bonds (Figure 3, top right) and two such units are connected
into a dimer through N(3)−H(03)···O(2) hydrogen bonds
1
.343(6), C(1)−N(2) = 1.326(6), C(11)−N(3) = 1.308(6), C(11)−
C(42) = 1.456(6), Pd(1)−Cl(1) = 2.3847(12), Pd(1)−Cl(2) =
2
=
=
.3765(12); C(1)−Pd(1)−C(11) = 87.84(18), C(11)−Pd(1)−Cl(2)
91.14(13), C(1)−Pd(1)−Cl(1) = 90.89(14), Cl(2)−Pd(1)−Cl(1)
89.97(4), N(2)−C(1)−N(1) = 116.0(4), C(11)−N(3)−C(12) =
134.1(4).
(
Figure 3, bottom).
2
2
distances are even shorter than the standard C(sp )N(sp )
IR and NMR Spectra. The IR spectra show from one to
3
4
−1
distance, discarding that possibility.
three bands in the 3100−3340 cm region, corresponding to
the NH stretching modes. They are of weak to medium
intensity and broad. The bands of the N−C−N delocalized
system cannot be assigned unequivocally, since other
absorptions attributable to the various aromatic rings existing
in the complexes appear in the same region. The ν(CN)
In 9·0.5CHCl the two asymmetric molecules in the unit cell
3
are connected through a classical N(1A)−H(01A)···Cl(2)
hydrogen bond. The molecules are also linked through another
N−H···Cl bond and two nonclassical C−H···Cl hydrogen
bonds, giving sheets parallel to (110) (Figure 2, right). In
3
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stretching bands appear around 2200 cm−1 in isocyanide
complexes.
187.1 (C ), 251.5 vs 204.9 (C ), respectively), which is
consistent with the higher oxidation state of the palladium atom
in 17.
1
8
Some resonances are missing in the poor-quality 13C NMR
spectrum of 8, which we could not improve despite various
attempts. The 13C NMR spectra of 18 could not be measured
because of its instability.
CONCLUSION
■
(
We report the first metal complexes containing a chelating C,C-
iminiumbenzoyl)carbene ligand, which include the first acyclic
Although these complexes could contain the carbene ligands
in an E or Z configuration, the NMR spectra show that only
one isomer is obtained in all cases. On the basis of the crystal
structures we could measure (4·CHCl , 9·0.5CHCl , and 12),
diaminocarbene (ADC) complexes of Pd(III) and Pd(IV). The
last species is also the first dinuclear organo-Pd(IV) complex. In
contrast with the main method for the synthesis of ADC
complexes, which involves the attack of an added amine at a
coordinated isocyanide, in the present case, the synthesis of the
reported complexes is achieved by addition of an isocyanide to
a complex containing a ligand bearing an amine group.
3
3
we assume that all the carbene ligands in our complexes adop3t
the E configuration. This leaves plenty of room for the Xy
3
group (R in Chart 1) to rotate freely, as observed in the
mononuclear complexes 4 and 9−12, which display a single set
of resonances. However, the rotation of this group is restricted
in all the remaining complexes, as shown by duplicated Xy3
resonances. In the dinuclear derivatives, this could be explained
by assuming that the central six-membered Pd−C−N−Pd′−
C′−N′ ring adopts a boat disposition, as we have found in a few
EXPERIMENTAL SECTION
■
General Considerations. When not stated, the reactions were
carried out without precautions to exclude light or atmospheric oxygen
or moisture. Melting points were determined on a Reichert apparatus
and are uncorrected. Elemental analyses were carried out with a Carlo
Erba 1106 microanalyzer. IR spectra were recorded on a Perkin-Elmer
Spectrum 100 spectrophotometer using Nujol mulls between
polyethylene sheets. NMR spectra were recorded with Bruker Avance
00, 300, and 400 NMR spectrometers. The NMR assignments were
performed, in some cases, with the help of APT, COSY, HMQC,
HMBC, and NOESY experiments. The atom numbering used in NMR
3
5
other bridging xylyl(iminobenzoyl) palladium complexes.
1
This could leave the Xy group in the PdC(NXy) moiety
3
close to the Xy group of the Pd′C′(N′Xy′) subunit.
In 12, the NH resonances of the iminiumbenzoyl and
carbene fragments are rather deshielded with respect to their
homologues in the remaining complexes, which we attribute to
2
1
its dicationic nature. In general, the N H resonance (Chart 1)
appears between 11 and 14 ppm, the same region found in
2
3,35
other iminiumbenzoyl complexes.
Chart 1. Numbering Scheme Used in the NMR Assignment
3
Among the carbene NH resonances, N H (in the wide range
of 8.15−13.55 ppm) seems to be sensitive not only to the R
group but also to the palladium ligand disposed trans to the
3
iminiumbenzoyl moiety, supporting the E configuration of the
3
carbene ligand which leaves the N H pointing toward that
3
particular ligand. In fact, the N H resonance appears very
t
shielded in 8 (8.15 ppm) having R = Bu; it is more shielded in
the iodo complex 4 (8.99 ppm) than in its homologous chloro
complex 10 (9.49 ppm), and it is most deshielded in the
acetato complex 13 (13.55 ppm), likely because of its
participation in N−H···OAc hydrogen bonding. In contrast,
2
assignments is shown in Chart 1. High-resolution ESI mass spectra
were recorded on an Agilent 6220 Accurate Mass TOF LC/MS
the N H resonance (Chart 1) is rather invariant and, with the
only exception of 12 (see above), appears in all complexes in
t
spectrometer. [PPN]Cl, PPh , BuNC, XyNC, Tl CO , and TfOH
1
3
3
2
3
the narrow range of 6.9−7.7 ppm. In the C NMR spectra, the
(
(
Fluka), PhI and IC H CO H-2 (Aldrich), NEt (Merck), and NaOAc
Sigma) were obtained from commercial sources. TlTfO was prepared
6 4 2 3
most noticeable feature is the presence of the iminiumbenzoyl
1
8
(
C , 179−188 ppm) and carbene (C , 203−224 ppm)
from Tl CO3 and TfOH (1:2, in water) and recrystallized from
2
resonances in the regions previously found for other Pd(II)
carbene complexes. The P{ H} NMR spectra of complexes
acetone/Et O. PhICl was prepared by bubbling Cl through PhI,
2
2
2
36
31
1
filtering the suspension, and washing the solid with cold n-pentane. It
1
1, 15, and 16 show a singlet resonance in the range of 23.3−
must be kept below 0 °C. The syntheses of [PdI{C,N-C(
2
3
1 8
NHXy)C H NH -2}(CNXy)]TfO (3), cis-[PdCl {C(NHXy)-
24.2 ppm. The singlet resonance found for both the C and C
6
4
2
2
t
22
13
1
C H NH }-2}(CNR)] (R = Bu (5), Xy (6)), and [PdCl {C,N-
6
4
2
2
nuclei in the C{ H} NMR spectra of these complexes
prevents us, in the absence of crystallographic data, from
unambiguously assigning their structures. However, the
22
C(NHXy)C H NH -2}] (7) were recently reported by us.
6
4
2
X-ray Crystallography. Compounds 4·CHCl , 9·0.5CHCl and
3
3
1
2 were measured on a Bruker Smart APEX instrument. Data were
NOESY spectrum of 11 measured in CDCl at −60 °C reveals
3
collected using monochromated Mo Kα radiation in ω-scan mode.
The structures were solved by direct methods and refined anisotropi-
1
an interaction between Xy and PPh , suggesting that the
3
2
iminiumbenzoyl xylyl fragment is situated cis to the PPh3
ligand, as shown in the crystal structure of 4, in which the
anionic ligand, I, is trans to the iminiumbenzoyl ligand, leaving
cally on F . The hydrogens of NH were refined freely and were also
refined with DFIX in compounds 4·CHCl and 9·0.5CHCl . The
3
3
ordered methyl groups were refined using rigid groups (AFIX 137),
and the other hydrogens were refined using a riding model. Special
the position trans to carbene for the neutral ligand.
The 13C NMR spectrum measured in acetone-d at −60 °C
features: for 4·CHCl , the xylyl group is disordered over two positions,
3
6
ca. 62:38%; for 12, there is a poorly resolved region of residual
electron density, and this could be adequately modeled as a
superposition of diethyl ether and chloroform. We prefer this way
than using the program SQUEEZE. Further details on crystal data,
data collection, and refinements are summarized in Table 1
(Supporting Information).
of a fresh sample of the Pd(IV) complex 17, prepared in situ
from 13 and 2-iodobenzoic acid in a 1:3 molar ratio (see the
1
2
Supporting Information), shows the resonances of C , C , and
8
C highly deshielded with respect to the same nuclei in the
2
precursor Pd(II) complex 13 (172.4 vs 146.7 (C ), 205.9 vs
3
715
dx.doi.org/10.1021/om300201s | Organometallics 2012, 31, 3711−3719

Organometallics
Article
2
3
1
13
1
Synthesis of [PdI{C,C-C(NHXy)C H {NHC(NHXy)}-2}CNXy]-
N H), 10.43 (br s, 1 H, N H), 11.76 (v br s, 1 H, N H). C{ H}
6
4
1
TfO (4). To a suspension of [PdI{C,N-C(NHXy)C H NH -
NMR (100.8 MHz, CDCl , 25 °C, TMS): δ 18.3 (Me, Xy ), 18.4 (Me,
Xy ), 120.2 (CH ), 122.8 (C ), 124.5 (CH ), 124.6 (CH ), 129.1 (p-
Xy or p-Xy ), 129.2 (m-Xy ), 129.5 (m-Xy ), 129.7 (p-Xy or p-Xy ),
132.4 (o-Xy ), 132.5 (ipso-Xy ), 133.9 (CH ), 135.3 (o-Xy ), 137.6
(ipso-Xy ), 141.3 (C ), 179.8 (C ), 216.2 (C ). IR (Nujol, cm ):
ν(NH) 3242. Anal. Calcd for C H Cl N Pd: C, 54.10; H, 4.73; N,
7.89. Found: C, 53.75; H, 4.85; N, 7.79. Crystals of 9·0.5CHCl3
suitable for an X-ray diffraction study were obtained by slow
evaporation of a solution of the complex in CHCl3.
6
4
2
3
23
3
7
3
4
5
2
}(CNXy)]TfO (3; 173 mg, 0.23 mmol) in CH Cl (15 mL) was
2
2
1
3
3
1
1
3
added XyNC (65 mg, 0.50 mmol). The reaction mixture was stirred
for 3 h. The resulting solution was concentrated under vacuum (1
3
1
6
1
3
2
1
8
−1
mL), and Et O (20 mL) was added to give a suspension, which was
2
filtered. The solid that was collected was recrystallized from a 1/20
cold mixture of CH Cl and Et O (21 mL, 0 °C) and dried first by
24
25
2
3
2
2
2
suction and then in an oven under vacuum (70 °C, 12 h) to give
4
1
·H O as a pale yellow solid. Yield: 147.5 mg, 0.17 mmol, 70%. Mp:
2
1
48 °C dec. H NMR (400 MHz, CHCl , 25 °C, TMS): δ 1.62 (br s, 2
Synthesis of [PdCl{C,C-C(NHXy)C H {NHC(NHR)}-2}CNXy]-
TfO (10). To a solution of 9 (75 mg, 0.14 mmol) in CH Cl (15 mL)
2 2
3
6 4
3
H, H O), 2.17 (s, 6 H, Me, Xy ), 2.19 (v br s, 3 H, Me), 2.34 (v br s, 3
2
H, Me), 2.48 (v br s, 3 H, Me), 2.65 (v br s, 3 H, Me), 6.66 (v br s, 1
were succesively added XyNC (20 mg, 0.15 mmol) and TlTfO (50
mg, 0.14 mmol). The suspension was stirred for 6 h and then filtered
through Celite. The solution was concentrated under vacuum (1 mL),
4
3
4
H, m-Xy), 6.91 (dd, 1 H, H , J = 8 Hz, J = 1 Hz), 7.10 (d, 2 H,
HH
HH
Pd
3
Pd 3
m-Xy , J = 8 Hz), 7.15 (t, 1 H, p-Xy , J = 8 Hz), 7.25−7.32
m, 3 H), 7.36 (m, 2 H), 7.45 (“dt”, 1 H, H , J = 8 Hz, J = 1
HH
HH
5
3
4
(
cold Et O was added (20 mL, 0 °C), the suspension was filtered, and
HH
HH
2
6
3
4
Hz), 7.54 (“dt”, 1 H, H , J = 8 Hz, J = 1 Hz), 7.66 (s, 1 H,
the solid that was collected was recrystallized from a cold CH Cl /
HH
HH
2
2
2
7
3
4
N H), 7.86 (dd, 1 H, H , J = 8 Hz, J = 1 Hz), 8.99 (s, 1 H,
Et O mixture (1/20, 21 mL, 0 °C) and washed with Et O (5 mL). The
HH
HH
2
2
3
1
1
N H), 13.02 (v br s, 1 H, N H). H NMR (400 MHz, CHCl , −20 °C,
solid was dried, first by suction and then in a vacuum oven at 60 °C for
8 h, to give 10 as a pale yellow solid. Yield: 91.7 mg, 0.12 mmol, 84%.
3
3
TMS): δ 1.87 (br s, 2 H, H O), 2.17 (s, 6 H, Me, Xy ), 2.19 (s, 3 H,
2
1
Me), 2.33 (s, 3 H, Me), 2.49 (s, 3 H, Me), 2.64 (s, 3 H, Me), 6.64 (d, 1
Mp: 207 °C dec. H NMR (400 MHz, CDCl , 25 °C, TMS): δ 2.17 (s,
3
3
4
3
3
1
Pd
H, m-Xy, J = 7 Hz), 6.98 (d, 1 H, H , J = 8.0 Hz), 7.12 (d, 2 H,
6 H, Me, Xy ), 2.30 (br s, 6 H, Me, Xy ), 2.51 (br s, 6 H, Me, Xy ),
HH
HH
Pd
Pd
3
3
4
3
4
Pd
m-Xy , J = 8 Hz), 7.18 (t, 1 H, p-Xy , J = 8 Hz), 7.26−7.41
6.92 (dd, 1 H, H , J = 8 Hz, J = 1 Hz), 7.11 (d, 2 H, m-Xy ,
HH
HH
HH HH
5
3
4
3
Pd 3
(
m, 5 H), 7.45 (t, 1 H, H , J = 8 Hz, J = 1 Hz), 7.57 (“dt”, 1 H,
JHH = 8 Hz), 7.15 (t, 1 H, p-Xy , J = 8 Hz), 7.25−7.30 (m, 5 H),
3 5 3 4
HH
HH
HH
6
3
4
7
3
H , J = 8 Hz, J = 1 Hz), 7.85 (d, 1 H, H , J = 8 Hz), 7.86 (s,
H, N H), 8.91 (s, 1 H, N H), 13.02 (v br s, 1 H, N H). C{ H}
7.35 (t, 1 H, J = 7 Hz), 7.42 (“dt”, 1 H, H , J = 8 Hz, J = 1
HH HH HH
HH
HH
HH
2
3
1
13
1
6
3
4
1
Hz), 7.52 (”dt”, 1 H, H , J = 8 Hz, J = 1 Hz), 7.67 (s, 1 H,
N H), 7.84 (dd, 1 H, H , J = 8 Hz, J = 1 Hz), 9.49 (s, 1 H,
N H), 13.12 (v br s, 1 H, N H). H NMR (400 MHz, CDCl , −40 °C,
TMS): δ 2.16 (s, 6 H, Me, Xy ), 2.19 (s, 3 H, Me), 2.35 (s, 3 H, Me),
HH HH
2
7
3
4
NMR (75.5 MHz, CD Cl , 25 °C, TMS): δ 18.5−19.5 (v br s, Me),
2
2
HH
HH
3
1
4
3
1
1
1
8.9 (Me, Xy ), 120.6 (q, J = 320 Hz, CF SO ), 120.8 (C ), 126.1
C ), 127.4 (C ), 128.5 (m-Xy), 130.0 (CH), 130.1 (CH), 130.7
CH), 130.8 (CH), 132.8 (ipso-Xy), 135.0 (C ), 135.6 (o-Xy ), 136.3
br s, ipso-Xy), 140.0 (ipso-Xy ), 140.6 (C ), 185.8 (C ), 224.0 (C );
CF
3
3
3
7
5
3
(
(
(
6
1
3
2.41 (s, 3 H, Me), 2.65 (s, 3 H, Me), 6.70 (d, 1 H, J = 8 Hz), 7.00
HH
3
2
1
8
4
3
Pd 3
(d, 1 H, H , J = 8 Hz), 7.13 (d, 2 H, m-Xy , J = 8 Hz), 7.20 (t,
HH HH
3
−1
3
5 3
C not observed. IR (Nujol, cm ): ν(NH) 3296, 3276, 3182, ν(C
1 H, J = 8 Hz), 7.26−7.41 (m, 5 H), 7.44 (t, 1 H, H , J = 8 Hz),
6 3 7 3
HH
HH
−
1
cm2 mol . Anal. Calcd for
−1
N) 2196. Λ = 113 Ω
7.56 (t, 1 H, H , J = 8 Hz), 7.83 (d, 1 H, H , J = 8 Hz), 7.84 (s,
M
HH HH
2
3
1
13
1
C H F IN O PdS: C, 46.04; H, 4.09; N, 6.32; S, 3.61. Found: C,
1 H, N H), 9.34 (s, 1 H, N H), 12.95 (s, 1 H, N H). C{ H} NMR
3
4
36
3
4
4
4
6.29; H, 3.84; N, 6.45; S, 3.69. Crystals of 4·CHCl suitable for an X-
(75.5 MHz, CDCl , 25 °C, TMS): δ 18.1 (Me), 18.6 (Me), 18.6 (br,
3
3
4
1
7
ray diffraction study were obtained by slow diffusion of Et O into a
Me), 120.0 (C ), 120.1 (q, CF SO , J = 320 Hz), 125.8 (C ), 126.2
(C ), 127.3 (C ), 128.2 (m-Xy ), 129.5 (CH), 129.8 (m-Xy ), 130.2
(CH), 130.6 (CH), 131.5 (C), 133.9 (br, ipso-Xy ), 134.6 (C ),
35.37 (o-Xy ), 135.41 (C), 139.3 (C), 139.9 (C ), 183.7 (C ), 220.7
2
3 3 CF
3
5
Pd
Pd
solution of the complex in CHCl3.
Pd
6
Synthesis of [PdCl {C,C-C(NHXy)C H {NHC(NHR)}-2}CNR]
2
6 4
t
3
2
1
(
R = Bu (8), Xy (9)). To a suspension of 7 (for 8, 115 mg, 0.29
1
8
−1
mmol; for 9, 70 mg, 0.17 mmol) in CHCl (15 mL) was added the
3
(C ). IR (Nujol, cm ): ν(NH) 3272, 3220, 3178; ν(CN) 2198. Λ
M
t
−1
2
−1
appropriate isocyanide (for 8, BuNC, 35 μL, 0.31 mmol; for 9, XyNC,
=
126 Ω cm mol . Anal. Calcd for C H ClF N O PdS: C, 52.52;
34 34 3 4 3
23 mg, 0.18 mmol) in a Carius tube, and the reaction mixture was
H, 4.41; N, 7.21; S, 4.12. Found: C, 52.54; H, 4.64; N, 7.30; S, 3.61.
heated with stirring (8, 50 °C for 7 h; 9, 60 °C, 6 h). For 8, the
reaction mixture was filtered through a short pad of anhydrous
Synthesis of [PdCl{C,C-C(NHXy)C H {NHC(NHR)}-2}PPh ]Cl
6
4
3
(11). To a solution of 9 (60 mg, 0.11 mmol) in CHCl (20 mL) was
3
MgSO , the solution was concentrated under vacuum (1 mL), cold
added PPh (60 mg, 0.23 mmol), and the reaction mixture was heated
4
3
Et O (15 mL, 0 °C) was added, and the resulting suspension was
with stirring in a Carius tube, at 120 °C, overnight. The resulting
2
stirred at 0 °C for 15 min and filtered. For 9, the resulting solution was
solution was filtered through anhydrous MgSO and concentrated
4
concentrated under vacuum (1 mL), Et O (20 mL) was added, and
under vacuum (1 mL), and Et O (20 mL) was added. The suspension
2
2
the yellow suspension was filtered. The solid that was collected was
was filtered and the solid that was collected was washed with Et O (3
2
washed with Et O (for 8, 3 × 3 mL, 0 °C; for 9, 3 × 5 mL) and dried,
× 5 mL) and dried by suction to give 11·2.5H O as a yellow solid.
2
2
1
first by suction and then in a vacuum oven (8, 70 °C for 7 h; 9, 60 °C
Yield: 61.4 mg, 0.07 mmol, 65%. Mp: 232 °C dec. H NMR (300
for 6 h) to give 8·H O and 9 as pale yellow solids.
MHz, CDCl , 25 °C, TMS): δ 1.57 (br s, 5 H, H O), 2.17 (s, 6 H, Me,
2
3
2
3
1
4 3
Data for 8·H O are as follows. Yield: 93.8 mg, 0.19 mmol, 65%. Mp:
Xy ), 2.31 (s, 6 H, Me, Xy ), 6.63 (d, 1 H, H , J = 8 Hz), 6.78 (t, 1
H, H , J = 8 Hz), 6.84 (v br s, 1 H, N H or H ), 7.04 (d, 2 H, m-
HH
Xy , J = 8 Hz), 7.16−7.46 (several m, 15 H), 7.71 (m, 6 H, o-
PPh ), 10.46 (br s, 1 H, N H), 11.77 (br s, 1 H, N H). C{ H} NMR
2
HH
1
5
3
2
7
2
09 °C. H NMR (300 MHz, CDCl , 25 °C, TMS): δ 1.21 (s, 9 H,
3
1
3 3
CMe ), 1.58 (s, 2 H, H O), 2.25 (s, 6 H, Me, Xy ), 7.09 (d, 2 H, m-
Xy , J = 8 Hz), 7.17−7.24 (m, 2 H), 7.49 (m, 2 H), 7.61 (br s, 2 H,
N H + N H), 8.15 (s, 1 H, N H), 8.70 (br d, 1 H, J = 7 Hz), 13.9
v br, 1 H, N H). C{ H} NMR (75.5 MHz, CDCl , 25 °C, TMS): δ
9.3 (Me, Xy ), 29.7 (CMe ), 58.7 (CMe ), 122.9 (v br, C ), 125.9
3
2
HH
1
3
3 1 13 1
HH
3
2
3
3
3
1
3
HH
(75.5 MHz, CDCl , 25 °C, TMS): δ 18.3 (Me, Xy ), 18.5 (Me, Xy ),
3
7 3 4 5
1
13
1
(
1
(
120.2 (br, CH ), 122.8 (C ), 124.5 (CH ), 124.7 (CH ), 128.1 (d, m-
3
1
3
3
1
3
3
3
3
PPh , J = 10 Hz), 129.1 (p-Xy or p-Xy ), 129.2 (m-Xy ), 129.5 (m-
Xy ), 129.6 (d, J = 50 Hz, ipso-PPh ), 129.7 (p-Xy or p-Xy ), 130.5
CP 3
(p-PPh ), 132.4 (o-Xy ), 132.5 (ipso-Xy ), 134.0 (CH ), 135.1 (d, o-
PPh , J = 12 Hz), 135.3 (o-Xy ), 137.6 (ipso-Xy ), 141.3 (C ), 179.8
3 CP
3 CP
1
1
1
1
3
CH), 126.7 (CH), 127.9 (CH), 128.5 (m-Xy + CH), 132.6 (ipso-
1
1
6
1
3
1
6
Xy ), 134.0 (br, o-Xy ), 135.9 (br, CH ), 140.5 (C), 147.8 (C); C and
3
8
−1
3
1
3
2
C not observed. IR (Nujol, cm ): ν(NH) 3101 Anal. Calcd for
1
8
31
1
C H Cl N OPd: C, 47.78; H, 5.41; N, 8.36. Found: C, 47.65; H,
(C ), 216.1 (C ). P{ H} NMR (121.5 MHz, CDCl , 25 °C): δ 23.8.
20
27
2
3
3
−
1
−1
2
−1
5
.04; N, 8.28.
IR (Nujol, cm ): ν(NH) 3271, 3177. Λ = 114 Ω cm mol . Anal.
M
Data for 9 are as follows. Yield: 65.3 mg, 0.12 mmol, 68%. Mp: 227
Calcd for C H Cl N O PPd: C, 59.48; H, 5.35; N, 4.95. Found: C,
42
45
2
3
2.5
1
°
C dec. H NMR (400 MHz, CDCl , 25 °C, TMS): δ 2.17 (s, 6 H,
59.69; H, 5.27; N, 4.91.
Synthesis of [Pd{C,C-C(NHXy)C H {NHC(NHR)}-2}(CNXy) ]-
3
3
1
4 3
Me, Xy ), 2.31 (s, 6 H, Me, Xy ), 6.63 (d, 1 H, H , J = 8 Hz), 6.78
HH
6
4
2
5
3
7 3
(
t, 1 H, H , J = 8 Hz), 6.84 (d, 1 H, H , J = 8 Hz), 7.04 (d, 2 H,
(TfO) (12). To a suspension of 10 (50 mg, 0.06 mmol) in CH Cl
HH
HH
2
2
2
3
3
3 3
m-Xy , J = 8 Hz), 7.18 (t, 1 H, p-Xy , J = 8 Hz), 7.23 (d, 2 H,
m-Xy , J = 7 Hz), 7.27−7.34 (m, 2 H, H + p-Xy ), 7.48 (br s, 1 H,
(15 mL) were successively added XyNC (10 mg, 0.08 mmol) and
TlTfO (23 mg, 0.07 mmol). The reaction mixture was stirred for 8 h at
HH
HH
1
3
6
1
HH
3
716
dx.doi.org/10.1021/om300201s | Organometallics 2012, 31, 3711−3719

Organometallics
Article
room temperature and filtered through Celite, the solution was
concentrated under vacuum (1 mL), and cold n-pentane was added
Me), 2.38 (s, 3 H, Me), 2.39 (s, 3 H, Me), 2.50 (s, 3 H, Me), 6.45 (d, 1
4
3
5 3
H, H , J = 8 Hz), 6.62 (s, 1 H, H , J = 8 Hz), 6.70 (m, 2 H,
HH
HH
7
3
3
(
20 mL, 0 °C). The suspension was filtered, and the solid that was
including H ), 6.81 (t, 1 H, J = 7 Hz), 6.87 (d, 1 H, J = 7 Hz),
7.04 (t, 1 H, J = 8 Hz), 7.17−7.20 (m, 2 H), 7.23−7.27 (m, 2 H),
7.24 (s, 1 H, N H), 10.00 (s, 1 H, N H). C{ H} NMR (100.8 MHz,
HH HH
3
collected was recrystallized from a cold CH Cl /n-pentane mixture (1/
2
2
HH
2
3
13
1
2
0, 21 mL, 0 °C) and dried, first by suction and then in a vacuum oven
(
60 °C, 8 h), to give 12 as a pale yellow solid. Yield: 56.5 mg, 0.06
CDCl , 25 °C, TMS): δ 18.4 (Me), 18.8 (Me), 19.8 (Me), 20.6 (Me),
3
1
mmol, 86%. Mp: 141 °C dec. H NMR (400 MHz, CDCl , 25 °C,
TMS): δ 1.87 (s, 3 H, Me), 2.21 (s, 6 H, Me, Xy ), 2.26 (s, 3 H, Me)
123.9 (CH), 124.0 (CH), 125.1 (CH), 127.6 (C), 127.7 (CH), 128.5
(CH), 128.97 (CH), 129.05 (CH), 129.09 (CH), 129.15 (CH), 129.6
(C), 131.3 (C), 132.8 (C), 135.9 (C), 136.0 (C), 138.2 (C), 147.5
3
3
1
2
.35 (s, 6 H, Me, Xy ), 2.52 (s, 3 H, Me), 2.70 (s, 3 H, Me), 6.47 (d, 1
4
3
3
5
2
1
8
−1
H, H , J = 8 Hz), 6.52 (br d, 1 H, J = 6.8 Hz), 6.88 (t, 1 H, H ,
(C ), 187.9 (C ), 203.5 (C ). IR (Nujol, cm ): ν(NH) 3423. Anal.
HH
HH
3
3
3
JHH = 8 Hz), 6.97 (br d, 1 H, J = 6.8 Hz), 7.04 (t, 1 H, J = 8
Calcd for C H Cl N O Pd : C, 56.54; H, 5.04; N, 8.24. Found: C,
HH
HH
48 51
2
6
1.5
2
3
3
Hz), 7.09 (d, 2 H, m-Xy, J = 8 Hz), 7.14 (d, 3 H, m-Xy + Ar, J
8
=
=
HH
56.50; H, 5.03; N, 8.25.
Synthesis of [PdX{C,C-C(NXy)C
OAc (15), Cl (16)). To a solution of the appropriate complex (for 15,
3 (134 mg, 0.13 mmol; for 16, 14, 50 mg, 0.05 mmol) in degassed
CHCl (10 mL) was added PPh (for 15, 30 mg, 0.27 mmol; for 16,
HH
HH
6
3
Hz), 7.18−7.22 (m, 2 H), 7.29−7.38 (m, 2 H), 7.47 (t, 1 H, H , J
8 Hz), 7.55 (d, 1 H, H , J = 8.0 Hz), 10.78 (s, 1 H, N H), 11.24
H {NHC(NHR)}-2}PPh ] (X =
6 4 3
7
3
2
HH
3
1
1
1
(
s, 1 H, N H), 13.90 (br s, 1 H, N H). H NMR (400 MHz, CDCl ,
3
3
−
3
6
60 °C, TMS): δ 1.86 (s, 3 H, Me), 2.20 (br s, 6 H, Me, Xy ), 2.23 (s,
H, Me) 2.35 (s, 6 H, Me, Xy ), 2.56 (s, 3 H, Me), 2.69 (s, 3 H, Me),
3
3
1
3
0 mg, 0.11 mmol). The reaction mixture was heated in a Carius tube
4
3
3
at 70 °C for 12 h. The resulting solution was filtered through
.50 (d, 1 H, H , J = 8 Hz), 6.54 (d, 1 H, J = 6.8 Hz), 696 (t, 1
HH HH
5
3
3
anhydrous MgSO and concentrated under vacuum (1 mL), and Et O
H, H , J = 8 Hz), 7.01 (d, 1 H, J = 7.0 Hz), 7.09−7.51 (several
m, 12 H), 10.77 (s, 1 H, N H), 11.11 (s, 1 H, N H), 13.72 (s, 1 H,
4
2
HH
HH
2
3
(
20 mL) was added to give a suspension that was filtered. For 15, the
solid that was collected was recrystallized from a 1/20 cold mixture of
CH Cl and Et O (21 mL, 0 °C) and dried, first by suction and then in
1
13
1
N H). C{ H} NMR (100.8 MHz, CDCl , 25 °C, TMS): δ 18.0
3
(
Me), 18.57 (Me), 18.60 (Me), 18.64 (Me), 18.7 (Me), 19.8 (Me),
2
2
2
1
7
4
a vacuum oven (70 °C, 7 h), to give a yellow solid. For 16, the solution
was concentrated under vacuum (1 mL) and cold n-pentane (20 mL, 0
1
20.3 (q, J = 320 Hz, CF SO ), 122.12 (C ), 122.16 (C ), 123.5
CF 3 3
3
5
(
(
(
C ), 124.8 (C ), 127.2 (CH), 128.39 (m-Xy), 128.43 (m-Xy), 128.8
CH), 129.0 (CH), 129.6 (CH), 129.7 (CH), 130.2 (CH), 131.3
CH), 131.5 (C), 133.6 (C), 134.8 (C), 135.1 (CH), 135.5 (o-Xy),
°
C) was added. The suspension was filtered, and the solid that was
collected was washed with n-pentane (3 × 3 mL) and dried, first by
suction and then in a vacuum oven (60 °C, 8 h), to give a pale yellow
solid.
2
1
36.2 (o-Xy), 136.75 (C), 136.82 (C), 137.2 (C), 142.2 (C ), 185.7
1
8
−1
(
=
C ), 222.5 (C ). IR (Nujol, cm ): ν(NH) 3182, ν(CN) 2200. Λ
M
−1
2
−1
Data for 15 are as follows. Yield: 137.1 mg, 0.18 mmol, 71%. Mp:
159 Ω cm mol . Anal. Calcd for C H F N O PdS : C, 51.69;
44
43
6
5
6
2
1
2
07 °C dec. H NMR (300 MHz, CDCl , 25 °C, TMS): δ 1.62 (s, 3
H, 4.24; N, 6.85; S, 6.27. Found: C, 51.34; H, 3.96; N, 6.78; S, 5.82.
Crystals of 12 suitable for an X-ray diffraction study were obtained by
slow diffusion of Et O into a solution of the complex in CHCl .
3
H, AcO), 1.85 (s, 3 H, Me), 2.37, 2.38 (both s, 3 H each, Me), 2.50 (s,
3
3
4
3
=
H, Me), 5.39 (d, 1 H, J = 6 Hz), 6.45 (dd, 1 H, J = 8 Hz, J
HH HH HH
2
3
3
4
1 Hz), 6.64 (dd, 1 H, J = 8v Hz, J = 1 Hz), 6.68−6.73 (m, 2
3 3
Synthesis of [(PdOAc) {μ-N,C,C-C(NXy)C H {NHC(NHR)}-
HH
HH
2
6
4
2
} ] (13). To a solution of 9 (150 mg, 0.28 mmol) in acetone (20
H), 6.82 (t, 1 H, JHH = 7 Hz), 6.87 (br d, 1 H, JHH = 7 Hz), 7.06
2
3
4
mL) was added TlTfO (230 mg, 0.65 mmol). The suspension was
stirred overnight and filtered through Celite, NaOAc (50 mg, 0.61
mmol) was added to the solution, and the reaction mixture was stirred
for 6 h, filtered through Celite, and concentrated to dryness. The
resulting oily residue was stirred with CH Cl (10 mL), and the
(“dt”, 1 H, JHH = 8 Hz, JHH = 1 Hz), 7.17−7.46 (various m, 6 H),
13 1
7.67−7.87 (m, 12 H), 9.96 (s, 1 H, NH). C{ H} NMR (75.5 MHz,
CDCl , 25 °C, TMS): δ 18.4 (Me), 18.8 (Me), 19.8 (Me), 20.6 (Me),
25.3 (Me, OAc), 119.2 (CH), 123.8 (CH), 123.9 (CH), 125.1 (CH),
3
3
127.6 (C), 127.7 (CH), 128.5 (CH), 129.0 (m-PPh , JCP = 9 Hz),
129.1 (CH), 134.0 (o-PPh , JCP = 10 Hz), 135.8 (CH), 136.0 (C),
3
2
2
3
2
suspension was filtered through a short pad of Celite. The solution was
2
1
8
concentrated under vacuum (1 mL), and a 1/2 cold mixture of Et O
138.2 (C), 147.5 (C ), 180.6 (C, OAc), 187.8 (C ), 203.5 (C ); ipso-
2
1
and n-pentane (30 mL, 0 °C) was added. The resulting suspension was
stirred at 0 °C for 15 min and filtered, and the solid that was collected
was dried, first by suction and then in a vacuum oven (70 °C, 7 h) to
PPh
δ 24.2. IR (Nujol, cm ): ν(NH) 3187. Anal. Calcd for
PPd: C, 67.56; H, 5.41; N, 5.37. Found: C, 67.73; H,
5.46; N, 5.10.
Data for 16·H1
Mp: 188 °C dec. H NMR (400 MHz, CDCl
not observed. 31P{ H} NMR (121.5 MHz, CDCl
, 25 °C, TMS):
3 3
−
1
C H N O
44 42 3 2
give 13·2.5H O as a white solid. Yield: 131.0 mg, 0.12 mmol, 86%.
2
1
Mp: 217 °C dec. H NMR (300 MHz, CDCl , 25 °C, TMS): δ 1.60 (s,
2
O are as follows. Yield: 65.9 mg, 0.09 mmol, 86%.
, 25 °C, TMS): δ 1.60 (s,
3
3
H, Me), 1.74 (s, 3 H, OAc), 1.83 (br s, 5 H, H O), 2.24 (s, 3 H,
3
2
4
3
3
1
Me), 2.41 (s, 3 H, Me), 2.54 (s, 3 H, Me), 6.43 (d, 1 H, H , J = 8
Hz), 6.61 (d, 1 H, H , J = 8 Hz), 6.65−6.71 (m, 2 H, including
H ), 6.85 (t, 1 H, J = 8 Hz), 6.94 (d, 1 H, J = 7.2 Hz), 7.04
2 H, H O), 1.85 (s, 3 H, Me, Xy ), 2.37 (s, 3 H, Me, Xy ), 2.39 (s, 3 H,
2
HH
5
3
1
3
4
3
4
Me, Xy ), 2.49 (s, 3 H, Me, Xy ), 6.45 (dd, 1 H, H , JHH = 8 Hz, JHH
HH
7
3
3
5
3
7
= 1 Hz), 6.64 (d, 1 H, H , JHH = 8 Hz), 6.71 (m, 2 H, H + Xy), 6.83
HH
HH
3
4
3
3
(
7
“dt”, 1 H, J = 8 Hz, J = 1.2 Hz), 7.10−7.21 (m, 4 H), 7.23−
(t, 1 H, JHH = 7 Hz), 6.88 (br d, 1 H, JHH = 7 Hz), 7.06 (“dt”, 1 H,
HH
HH
2
3
13
1
3
4
.27 (m, 4 H, including N H), 13.55 (br s, 1 H, N H). C{ H} NMR
J
HH = 8 Hz, JHH = 2 Hz), 7.14−7.21 (m, 3 H), 7.24−7.49 (various m,
3
4
(
2
75.5 MHz, CDCl , 25 °C, TMS): δ 18.2 (Me), 18.4 (Me), 18.9 (Me),
12 H), 7.55 (“tq”, 1 H, J = 8 Hz, J = 2 Hz, PPh ), 7.64−7.74
3
HH
HH
3
3 31 1
0.2 (Me), 24.4 (Ac), 119.2 (CH), 123.3 (CH), 123.4 (CH), 124.9
(m, 4 H, PPh ), 9.97 (s, 1 H, N H). P{ H} NMR (162.3 Hz, CDCl ,
3
3
−1
(
(
1
CH), 127.8 (CH), 128.1 (CH), 128.48 (CH), 128.52 (CH), 129.9
25 °C, TMS): δ 23.3. IR (Nujol, cm ): ν(NH) 3319. Anal. Calcd for
C H ClN OPPd: C, 64.95; H, 5.32; N, 5.41. Found: C, 64.62; H,
CH), 129.05 (C), 129.10 (CH), 131.2 (C), 134.0 (C), 135.2 (C),
4
2
41
3
2
1
36.1 (C), 139.0 (C), 146.7 (C ), 179.6 (OAc), 187.1 (C ), 204.9
4.98; N, 5.34.
8
−1
(
C ). IR (Nujol, cm ): ν(NH) 3335, 3173. Anal. Calcd for
Synthesis of [{PdI(O,O-O CC H -2)} {μ-N,C,C-C(NXy)-
2
6
4
2
C H N O Pd : C, 57.57; H, 5.48; N, 7.75. Found: C, 57.60; H,
C
H
6
4
{NHC(NHXy)}-2}
2
] (17). To a solution of 13 (48 mg, 0.05
mmol) in cold CH Cl (5 mL, 0 °C) was added, under nitrogen, o-
2 2
52
59
6
6.5
2
5
.09; N, 7.51.
Synthesis of [(PdX) {μ-N,C,C-C(NXy)C H {NHC(NHR)}-2} ]
14). To a suspension of 9 (250 mg, 0.47 mmol) in CH Cl (10
2 2
iodobenzoic acid (30 mg, 0.12 mmol). The reaction mixture was
stirred in a water/ice bath for 1 h. The resulting red suspension was
filtered, and the solid that was collected was washed with cold CH Cl
2
2
6
4
2
(
mL) was added NEt (132 μL, 0.94 mmol). The reaction mixture was
3
2
stirred for 6 h and concentrated under vacuum to dryness, the residue
was treated with cold MeOH (5 mL, 0 °C), and the resulting
suspension was filtered. The solid that was collected was washed with
cold MeOH (3 mL, 0 °C) and dried, first by suction and then in a
(2 mL, 0 °C) and dried by suction under a nitrogen stream to give 17
as a crystalline deep orange solid. Yield: 46.3 mg, 0.03 mmol, 73%.
1
Mp: 201 °C dec. H NMR (300 MHz, dmso-d , 25 °C): δ 1.13 (s, 3
6
H, Me), 1.78 (s, 3 H, Me), 2.04 (s, 3 H, Me), 2.26 (s, 3 H, Me), 6.38
4
3
3
vacuum oven (60 °C, 6 h), to give 14·1.5H O as a very pale yellow
(d, 1 H, H , J = 8 Hz), 6.74 (t, 1 H, J = 8 Hz), 6.86−7.04 (m, 3
2
HH
HH
1
7
3
solid. Yield: 234.0 mg, 0.46 mmol, 98%. Mp: 250 °C dec. H NMR
H, H + Ar), 7.13−7.35 (m, 8 H), 7.84 (t, 1 H, J = 8 Hz), 9.61 (d,
HH
3 3 −1
(
400 MHz, CDCl , 25 °C, TMS): δ 1.53 (s, 3 H, H O), 1.85 (s, 3 H,
1 H, J = 8 Hz), 12.59 (s, 1 H, N H). IR (Nujol, cm ): ν(NH)
3
2
HH
3
717
dx.doi.org/10.1021/om300201s | Organometallics 2012, 31, 3711−3719

Organometallics
Article
3
324, 3295, 3182. HRMS (ESI): m/z calcd for C H I NaN Pd O =
Organometallics 2002, 21, 700. Connon, S. J.; Blechert, S. Angew.
Chem., Int. Ed. 2003, 42, 1900. Mas-Marza, E.; Poyatos, M.; Sanau, M.;
Peris, E. Organometallics 2003, 23, 323. Crudden, C. M.; Allen, D. P.
Coord. Chem. Rev. 2004, 248, 2247. Kantchev, E. A. B.; O’Brien, C. J.;
Organ, M. G. Angew. Chem., Int. Ed. 2007, 46, 2768. Hahn, F. E.;
Jahnke, M. C. Angew. Chem., Int. Ed. 2008, 47, 3122. Kong, Y.; Ren,
H.; Xu, S.; Song, H.; Liu, B.; Wang, B. Organometallics 2009, 28, 5934.
Liu, Z.; Shi, M. Organometallics 2010, 29, 2831. Verma, P.; Patni, P. A.;
Sunoj, R. B. J. Org. Chem. 2011, 76, 5606. Busetto, L.; Cassani, M. C.;
Femoni, C.; Mancinelli, M.; Mazzanti, A.; Mazzoni, R.; Solinas, G.
Organometallics 2011, 30, 5258. Fernandez, F. E.; Puerta, M. C.;
Valerga, P. Organometallics 2011, 30, 5793.
(8) Badley, E. M.; Chatt, J.; Richards, R. L.; Sim, G. A. J. Chem. Soc.,
Chem. Commun. 1969, 1322. Badley, E. M.; Chatt, J.; Richards, R. L. J.
Chem. Soc. A 1971, 21. Busetto, L.; Palazzi, A.; Crociani, B.; Belluco,
U.; Badley, E. M.; Kilby, B. J. L.; Richards, R. L. J. Chem. Soc., Dalton
Trans. 1972, 1800. Bonati, F.; Minghetti, G. Gazz. Chim. Ital. 1973,
103, 373. Muir, K. W.; Walker, R.; Chatt, J.; Richards, R. L.; Royston,
G. H. D. J. Organomet. Chem. 1973, 56, C30. Uguagliati, P.; Crociani,
B.; Belluco, U. J. Organomet. Chem. 1975, 92, 399. Crociani, B.;
Uguagliati, P.; Belluco, U. J. Organomet. Chem. 1976, 117, 189. Chatt,
J.; Richards, R. L.; Royston, G. H. D. J. Chem. Soc., Dalton Trans. 1976,
62
56 2
6
2
4
+
[
M+Na] 1439.0444, found 1439.0446; calcd for C H I KN Pd O
62 56 2 6 2 4
[M + K] 1455.0182, found 1439.0222. Anal. Calcd for
+
=
C H I N O Pd : C, 52.60; H, 3.99; N, 5.94. Found: C, 52.77; H,
62
56 2
6
4
2
4.45; N, 6.39.
Synthesis of [(PdCl ) {μ-N,C,C-C(NXy)C H {NHC(NHXy)}-
} ] (18). To a cold solution of 14 (75 mg, 0.08 mmol) in cold
2
2
2
6
4
2
CHCl (1 mL, 0 °C) was added PhICl (23 mg, 0.08 mmol). The
reaction mixture was stirred for 1 min, and immediately a 1/2 cold
mixture Et O and n-pentane (15 mL, 0 °C) was added. The resulting
red suspension was rapidly filtered, and the solid that was collected
3
2
2
was washed with cold Et O (3 mL, 0 °C) and dried by suction under a
2
nitrogen stream to give 18·CHCl as a crystalline red solid. Yield: 79.8
3
1
mg, 0.07 mmol, 92%. Mp: 242 °C dec. H NMR (400 MHz, CDCl ,
3
2
5 °C, TMS): δ 1.99 (s, 3 H, Me), 2.43 (s, 3 H, Me), 2.56 (s, 3 H,
4 3
Me), 2.58 (s, 3 H, Me), 6.60 (d, 1 H, H , J = 7 Hz), 6.83 (m, 2 H),
HH
3
7
3
6.91 (t, 1 H, J = 7 Hz), 7.02 (m, 2 H, H + Ar), 7.18 (d, 2 H, J
HH HH
3
=
7 Hz), 7.28−7.35 (m, 2 H), 7.57 (s, 1 H, NH), 11.02 (s, 1 H, N H).
−1
IR (Nujol, cm ): ν(NH) 3318. Anal. Calcd for C H Cl N Pd : C,
49
49
7
6
2
49.75; H, 4.18; N, 7.10. Found: C, 49.57; H, 4.34; N, 7.14.
ASSOCIATED CONTENT
■
* Supporting Information
S
5
1
99. Uguagliati, P.; Crociani, B.; Belluco, U. J. Organomet. Chem. 1977,
42, 105. Rotondo, E.; Cusumano, M.; Crociani, B.; Uguagliati, P.;
Plots representing hydrogen bond interactions, a table of crystal
data and structure refinement details for complexes 4·CHCl3,
9
information. This material is available free of charge via the
Internet at http://pubs.acs.org.
Belluco, U. J. Organomet. Chem. 1977, 134, 249. Uson, R.; Laguna, A.;
Vicente, J.; Garcia, J.; Bergareche, B. J. Organomet. Chem. 1979, 173,
349. Uson, R.; Laguna, A.; Vicente, J.; Garcia, J.; Bergareche, B.; Brun,
P. Inorg. Chim. Acta 1978, 28, 237. Vicente, J.; Chicote, M. T.;
Abrisqueta, M. D.; Ramirez de Arellano, M. C.; Jones, P. G.;
Humphrey, M. G.; Cifuentes, M. P.; Samoc, M.; Luther-Davies, B.
Organometallics 2000, 19, 2968.
·0.5CHCl , and 12, and CIF files giving crystallographic
3
AUTHOR INFORMATION
■
Corresponding Author
(
9) Alder, R. W.; Allen, P. R.; Murray, M.; Orpen, A. G. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1121.
10) Vignolle, J.; Cattoen, X.; Bourissou, D. Chem. Rev. 2009, 109,
333.
11) Frey, G. D.; Herrmann, W. A. J. Organomet. Chem. 2005, 690,
*
E-mail: mch@um.es (M.-T.C.); jvs1@um.es (J.V.). Web:
www: http://www.um.es/gqo/.
(
̈
3
Notes
(
The authors declare no competing financial interest.
̈
5
876. Herrmann, W. A.; Ofele, K.; von Preysing, D.; Herdtweck, E. J.
Organomet. Chem. 2003, 684, 235.
12) Frey, G. D.; Rentzsch, C. F.; Herrmann, W. A. J. Organomet.
ACKNOWLEDGMENTS
■
(
We thank the Spanish Ministerio de Ciencia e Innovacion
́
Chem. 2006, 691, 2465.
(13) Denk, K.; Sirsch, P.; Herrmann, W. A. J. Organomet. Chem.
(
grant CTQ2007-60808/BQU, with FEDER support) and
Fundacion
́
Sen
́
eca (grants 02992/PI/05 and 04539/GERM/
2002, 649, 219.
06) for financial support.
(14) Vicente, J.; Abad, J. A.; Lop
C.; Botella-Segura, L. Organometallics 2005, 24, 5044.
15) Moncada, A. I.; Khan, M. A.; Slaughter, L. M. Tetrahedron Lett.
005, 46, 1339. Moncada, A. I.; Manne, S.; Tanski, J. M.
́ ́
ez-Serrano, J.; Jones, P. G.; Najera,
(
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