Synthesis, structure and reactivity of PdII complexes with the terdentate imino alcohol ligand C6H3-3,4-(OMe)2-C(H)=N-CH2 CH2OH

Article abstract of DOI:10.1039/b006140i

The reaction of the imino alcohol C₆H₃-3,4-(OMe)₂-C(H)=NCH₂ CH₂OH, 1, with Pd(OAc)₂ yields the dinuclear orthometallated compound [Pd(μ-OAc){C₆H₂-4,5-(OMe)₂

Full text of DOI:10.1039/b006140i

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Synthesis, structure and reactivity of PdII complexes with the
terdentate imino alcohol ligand C H -3,4-(OMe) –C(H)2N-
6 3
2
CH CH OH¤
2
2
Carlos Cativiela,a Larry R. Falvello,b Juan Carlos Gines,a Rafael Navarro*b and
Esteban P. Urriolabeitiab
a Departamento de Qu•mica Organica, Instituto de Ciencia de Materiales de Aragon, Universidad
de Zaragoza-Consejo Superior de Investigaciones Cient•Ðcas, E-50009 Zaragoza, Spain
b Departamento de Qu•mica Inorganica, Instituto de Ciencia de Materiales de Aragon,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cient•Ðcas, E-50009 Zaragoza,
Spain. E-mail: rafanava=posta.unizar.es
Received (in Montpellier, France) 28th July 2000, Accepted 7th November 2000
First published as an Advance Article on the web 23rd January 2001
The reaction of the imino alcohol C H -3,4-(OMe) -C(H)2NCH CH OH, 1, with Pd(OAc) yields the dinuclear
6
3
2
2
2
2
orthometallated compound [Pd(l-OAc)MC H -4,5-(OMe) -2-C(H)2NCH CH OH-j2-C,NN] , 2, which, by
6
2
2
2
2
2
reaction with excess LiCl in MeOH, can be transformed into the halide-bridged complex [Pd(l-Cl)MC H -4,5-
6
2
(OMe) -2-C(H)2NCH CH OH-j2-C,NN] , 3. Complex 3 reacts with neutral monodentate ligands L that promote
2
2
2
2
the cleavage of the halide bridging system to give the mononuclear [Pd(Cl)MC H -4,5-(OMe) -2-
6
2
2
C(H)2NCH CH OH-j2-C,NN(L)] (L \ PPh 4; py 5) complexes. The OH group does not interact with the Pd
2
2
3
atom in complexes 2È5. The reaction of 3 with AgClO in NCMe gives the cationic monosolvate [PdMC H -4,5-
4
6 2
(OMe) -2-C(H)2NCH CH OH-j3-C,N,ON(NCMe)](ClO ), 6, in which the orthometallated ligand is now C,N,O-
2
2
2
4
terdentate through coordination of the OH group. The strength of the PdÈO(H) bond has been studied. Complex 6
reacts with an excess of a neutral monodentate ligand L to give [PdMC H -4,5-(OMe) -2-C(H)2NCH CH OH-j3-
6
2
2
2
2
C,N,ON(L)](ClO ) (L \ PPh 7; py 8), in which the incoming ligand L replaces the NCMe but does not cleave the
4
3
PdÈO(H) bond. Alternatively, complexes 7 and 8 can be obtained by reaction of 3 with AgClO and L. Complex 6
4
reacts with bidentate N-donor ligands, yielding [PdMC H -4,5-(OMe) -2-C(H)2NCH CH OH-j3-C,N,ON(LÈL-j1-
6
2
2
2
2
N)](ClO ) (LÈL \ bipy 9; N,N,N@,N@-tmeda 10), in which the bipy or tmeda ligand is coordinated through only one
4
N atom. The rupture of the PdÈO(H) bond can be accomplished by reacting 6 with diphosphine ligands, such as
dppe, giving [PdMC H -4,5-(OMe) -2-C(H)2NCH CH OH-j2-C,NN(dppe-P,P)](ClO ), 11. Complexes 4 É CHCl
6
2
2
2
2
4
3
and 7 have been characterized by X-ray di†raction.
The synthesis of cyclometallated complexes has long been an
active, expanding Ðeld of chemical research, and numerous
reviews have recorded the ongoing developments in this area
over the years.1 The interest of chemists in this type of com-
pound derives from their versatility as well as from their
numerous applications. The recent literature includes contri-
butions in which cyclometallated complexes are reported to
serve as active catalysts,2 to promote stoichiometric asym-
metric transformations,3 to be useful as analytical tools,4 for
the synthesis of heterocycles5 and carbocycles,6 to allow the
resolution of racemic mixtures into their pure optically active
components,7 to promote unusual coordination environ-
ments,8 and to give chiral metal complexes with the metal
atom as a stereogenic center.9
Our interest in C,N-cyclometallated systems has been
centred mainly on their use as ancillary ligands in the reacti-
vity of PdII and PtII complexes towards a-stabilised phos-
phorus ylides10 and towards a-amino acids.4,11 We have now
focussed our attention on C,N-cyclometallated systems with
pendant auxiliary fragments, which could in principle act as
terdentate ligands. Within this class of terdentate ligands, the
[C,N,N] and [N,C,N] structural arrangements have been
extensively studied by several groups.1g,2g,3d,12 However, as
far as we know, the synthesis and coordination properties of
C,N,O-cyclometallated ligands have been much less studied,13
in spite of the stability provided by the C,N-chelate and the
hemilabile14 behaviour of the oxygen fragment, which could
confer upon it interesting catalytic properties. Moreover, very
few Pd(II) complexes containing an alcoholic oxygen coordi-
nated to the Pd(II) centre have been reported.15
In this context, we have explored the synthesis of Pd(II)
complexes with the potentially terdentate Schi† base C H -
6
3
3,4-(OMe) -C(H)2NCH CH OH, 1, which combines three
2
2
2
very di†erent donor atomsÈa ““softÏÏ orthometallatable C
aryl
atom, an iminic nitrogen and a ““hardÏÏ alcoholic oxygen. A
related system derived from ferrocene, and its reactivity
towards PdII and PtII complexes, has been reported very
recently.16 In this paper we report the synthesis of cyclo-
metallated complexes of Pd(II) derived from 1, in which this
ligand acts as [C,N]-bidentate or [C,N,O]-terdentate. The
PdÈO(H) bond in [C,N,O] complexes shows remarkable sta-
bility, the oxygen atom cannot be displaced from the coordi-
nation sphere of the Pd centre by addition of phosphines
(PPh ) or classical N-chelating ligands, such as tmeda (N,N,
3
N@,N@-tetramethylethylenediamine) or bipy (2,2@-bipyridine).
Results and discussion
Synthesis of [C,N]-orthometallated derivatives (Scheme 1)
The imino alcohol C H -3,4-(OMe) -C(H)2NCH CH OH, 1,
¤ Dedicated to Professor Rafael Uson on the occasion of his 75th
birthday.
6
3
2
2
2
is easily prepared by condensing 3,4-dimethoxybenzaldehyde
344
New J. Chem., 2001, 25, 344È352
DOI: 10.1039/b006140i
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2001

View Article Online
Scheme 1
with ethanolamine in the presence of MgSO . The character-
ization of 1 has been carried out using its analytical and spec-
troscopic data. The IR spectrum of solid 1 shows a strong
absorption at 1645 cm~1, indicating the presence of the iminic
N2C bond, and another strong, broad, absorption at 3195
broad, strong absorption in the IR spectrum of 2 at 1607
cm~1, which probably also contains the absorption corre-
sponding to the imine group. The shift of the iminic stretch in
2 to lower energy, compared to 1, suggests the N-coordination
of the imine.18 The IR spectrum of 2 also shows two sharp
absorptions at 3515 and 3383 cm~1, attributed to the OH
stretch, which are shifted to higher energies as compared to 1
and thus suggest that the oxygen atom does not interact with
the Pd atom. The 1H NMR spectrum of 2 shows only one set
of signals. In the aromatic region, three clear singlet reso-
nances are seen, at 7.43 [C(H)2N], 6.64 and 6.34 (H and H )
4
cm~1, corresponding to the l
stretch. This absorption
OH
appears at lower frequencies than those reported for ““freeÏÏ
OH groups (range 3650È3590 cm~1)17 and suggests in the
solid state, the presence of some inter- or intramolecular H-
bonds. The IR spectrum of 1 in solution (CHCl ) shows two
3
broad absorptions at 3610 and 3404 cm~1, suggesting that
3
6
these interactions disappear in solution at room temperature.
The 1H NMR spectrum of 1 shows only one set of signals,
indicating that the imine is present in only one of the two
possible geometric isomers (Z or E). This spectrum shows the
expected aromatic and aliphatic resonances, in addition to a
singlet at 8.14 ppm, attributed to the iminic proton C(H)2N,
and a broad resonance at 2.82 ppm, attributed to the hydroxyl
proton. The latter moves to 5.66 ppm on cooling (CD Cl ,
ppm. The presence of only two singlet resonances for H and
3
H
suggest the orthometallation of the phenyl ring in the 6-
6
position in 1, and the upÐeld shift of the resonance ascribed to
the iminic proton indicates that the imine is in the E form.18
The 1H NMR also shows signals attributed to the OMe,
OCH CH N, and acetate groups, and a poorly resolved
2
2
triplet resonance at 3.22 ppm (3J
\ 5 Hz) assigned to the
HhH
OH proton. In accord with the IR observations, the chemical
shift of the OH group also suggests that there is no interaction
between the Pd centre and the OH group. From all these data
we propose for complex 2 the stereochemistry shown in
Scheme 1Èa dinuclear C,N-orthometallated complex with
bridging acetate ligands [Pd(l-OAc)MC H -4,5-(OMe) -2-
2
2
218 K) but does not show Ðne structure. The 13CM1HN NMR
spectrum of 1 shows the expected resonances for the proposed
stoichiometry.
Ligand 1 reacts with Pd(OAc) (OAc \ acetate) in reÑuxing
2
methanol to give an orange solid of stoichiometry
6
2
2
[Pd(OAc)MC H -(OMe) -C(H)2NCH CH OHN], 2, according
C(H)2NCH CH OHN] . The 13CM1HN NMR spectrum of 2
shows the expected signals for the proposed stoichiometry.
6
2
2
2
2
2
2
2
to its elemental analysis and mass spectrum. The presence of
the acetate ligand can be inferred from the observation of a
As expected, complex 2 reacts with an excess of LiCl in
New J. Chem., 2001, 25, 344È352
345

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MeOH, resulting in the replacement of the acetate bridging
groups by chloride bridging ligands, giving the complex
[Pd(l-Cl)MC H -4,5-(OMe) -2-C(H)2NCH CH OHN] , 3, as
solid. The elemental analysis of 6 clearly shows the presence
of only one molecule of NCMe per cyclometallated unit, and
the mass spectrum shows the correct isotopic pattern for
the cation [PdMC H (OMe) C(H)NCH CH OHN(NCMe)]`
(m/z \ 355 amu). The IR spectrum of 6 shows a broad absorp-
tion centered at 3251 cm~1, assigned to the OH stretch, which
has shifted to lower energies as compared to the correspond-
ing values in 2È5, suggesting the coordination of the alcoholic
oxygen. In addition, the IR spectrum shows absorptions cor-
responding to the presence of the coordinated nitrile and the
orthometallated imine. The 1H NMR spectrum of 6 also pro-
vides valuable stereochemical information. The resonance
attributed to the OH proton appears as a triplet at 5.01 ppm
6
2
2
2
2
2
an insoluble yellow solid. Complex 3 has the correct elemental
analysis and mass spectrum. Its IR spectrum shows the disap-
pearance of the acetate absorption and the appearance of a
new absorption at 277 cm~1, assigned to the PdÈCl stretch,
whose position conÐrms the presence of the chloride bridging
system. The imine absorption appears as a sharp band at 1618
cm~1 and the OH stretch appears at 3529 cm~1.
6
2
2
2
2
Complex 3 is insoluble in most of the usual organic solvents
employed in NMR measurements, but it is sufficiently soluble
in DMSO-d . The 1H NMR spectrum shows, in the aromatic
6
region, a pattern of resonances similar to that described for 2,
(3J
\ 5 Hz), clearly shifted downÐeld from the values
HhH
a broad singlet at 4.77 ppm attributed to the OH proton and
a broad resonance (3.73È3.69 ppm) in which the methoxy and
methylene protons coincide. More informative is the APT
13CM1HN NMR spectrum (APT \ attached proton test), since
it shows clear and separate resonances for all the expected
carbon atoms in the molecule. The signal of the iminic carbon
appears at 177.71 ppm, the orthometallated phenyl ring
appears as six resonances (four with negative phase and two
with positive phase) between 152 and 112 ppm; two negative
peaks (around 60 ppm) and two positive peaks (around 55
ppm) account for the presence of the methylene and the
methoxy groups, respectively.
found for the preceding complexes 2È5, indicating the coordi-
nation of the oxygen atom. Similar downÐeld shifts have been
reported in the literature15b,21 and this shift, together with
that observed for the l
absorption in the IR spectrum,
OH
seems to be diagnostic for the coordination of the alcoholic
oxygen. Moreover, only one resonance attributable to coordi-
nated NCMe appears in the 1H NMR spectrum (2.09 ppm)
and in the 13CM1HN NMR spectrum (1.07 ppm). All of these
data conÐrm the stereochemistry proposed for 6 in Scheme 1.
In light of the surprisingly easy coordination of the alco-
holic oxygen in the presence of a solvent with good coordi-
nating ability (acetonitrile)Èa signal that the PdÈO(H) bond
is relatively strongÈwe have examined the stability of the
PdÈO(H) bond towards di†erent ligands by reacting complex
6 with a variety of monodentate and bidentate ligands.
Complex 3 reacts with monodentate ligands L to give the
mononuclear derivatives [PdClMC H -4,5-(OMe) -2-C(H)2N-
6
2
2
CH CH OHNL] (L \ PPh 4; pyridine 5) through cleavage of
2
2
3
the halide bridging system. The elemental analyses and mass
spectra of 4 and 5 are in good agreement with the proposed
stoichiometry. The IR spectra of 4 and 5 show the expected
The reaction of complex 6 with an excess of monodentate
ligands (L \ PPh , pyridine) in CH Cl at room temperature
3
2 2
a†ords the corresponding cationic derivatives [PdMC H -4,5-
6
2
absorptions corresponding to the presence of the PPh and py
(OMe) -2-C(H)2NCH CH OH-j-C,N,ON(L)]ClO (L \ PPh
3
2
2
2
4
3
ligands, and the iminic stretch appears at 1621 (4) and 1622 (5)
7; py 8), in accord with their elemental analyses. The mass
spectra of 7 and 8 show the correct isotopic pattern for the
cations[PdMC H (OMe) C(H)NCH CH OHN(PPh )]`(m/z\
cm~1. The l absorption appears at 3459 (4) and 3394 (5)
OH
cm~1, suggesting that the OH group does not interact with
6
2
2
6
2
2
3
the Pd atom, while l
appears at 293 (4) and 304 (5) cm~1,
576 amu) and [PdMC H (OMe) C(H)NCH CH OHN(py)]`
PdCl
2
2
2
2
shifted to higher energies with respect to 3, in accord with the
change from bridging to terminal chloride.
(m/z \ 393 amu). Thus, the reaction proceeds with simple sub-
stitution of the NCMe ligand in 6 by one incoming ligand L,
without displacement of the alcoholic oxygen from the coordi-
nation sphere of the palladium centre, in spite of an excess of
ligand L. This result can be rationalized, for complex 7, taking
into account that the ““hardÏÏ oxygen atom is stabilized when
trans to the ““softÏÏ orthometallated carbon atom,10 as we have
observed in the chemistry of a-keto-stabilized phosphorus
ylides, and that the incorporation of a ““softÏÏ phosphine
ligand trans to the carbon atom is an unfavourable process.20
This explanation is not so straightforward in the case of
complex 8, since pyridine ligands can easily be accommodated
trans to a carbon atom.10 Complexes 7 and 8 can also be
The 1H NMR spectra of 4 and 5 show, at room tem-
perature, resonances corresponding to all expected protons,
except for the OH proton. At 218 K the latter resonance also
appears, centered at 3.24 (4) and at 3.30 (5) ppm as triplets
(3J
\ 5 Hz). The iminic proton appears in 4 as a doublet at
HhH
8.09 ppm (4J \ 8.1 Hz), indicating the trans arrangement of
PhH
the phosphine ligand and the iminic nitrogen (see Scheme 1).
This stereochemistry is supported by the upÐeld shift of the
resonance attributed to H (5.83 ppm), due to the anisotropic
6
shielding promoted by the phenyl rings of the PPh ligand cis
3
to the orthometallation position.19 Moreover, the P-trans-to-
N arrangement is the usual result of reactions between C,N-
cyclometallated complexes and phosphine ligands,19 due to
the transphobic e†ect.20 Similar conclusions can be derived
from the analysis of the 1H NMR spectrum of 5 (py-trans-to-
easily obtained by treatment of 4 and 5 with AgClO in
acetone. For complex 7 both methods gave good yields of
4
analytically pure product, but in the case of complex 8, this
second route gave better results and, for this reason, this is the
only method described (see Scheme 1 and Experimental).
The characterization of 7 and 8 as possessing [C,N,O]-
coordinated ligands has been conÐrmed on the basis of their
spectroscopic parameters. The IR spectra of 7 and 8 do not
show the OH absorption, probably because this absorption is
hidden in the polyethylene region (below 3100 cm~1), which
means that this absorption has been shifted to lower energies
compared to complexes 4 and 5. Moreover, the 1H NMR
spectrum of 7 in CD Cl at room temperature shows the OH
N), since in this case the H singlet signal appears at 5.50 ppm
6
and the C(H)2N singlet resonance appears at around 7.90
ppm. The 31PM1HN NMR spectrum of 4 shows a single reso-
nance at 43.42 ppm and the 13CM1HN NMR spectra of 4 and 5
show the expected resonances.
In complexes 2È5, the OH group does not show any inter-
action with the Pd atom, as implied by the IR and NMR data,
and as seen in the crystal structure of 4 (see below). The cre-
ation of coordination vacancies by halide abstraction has been
a successful route to the O-coordination of the OH group.15b
2
2
resonance at 5.50 ppm as a triplet; the position of this signal
does not vary appreciably on cooling (218 K), suggesting a
static structure on the NMR timescale. On the other hand, the
Synthesis and reactivity of [C,N,O] complexes (Scheme 1)
1H NMR spectrum of 8 in acetone-d at room temperature
6
Complex 3 reacts with AgClO in a coordinating solvent
shows the OH resonance as a broad signal at 4.92 ppm. This
4
(NCMe) to give the monosolvate [PdMC H -4,5-(OMe) -2-
shift to low-Ðeld, together with the aforementioned bands in
the IR spectra of 7 and 8, clearly signal the OH coordination
6
2
2
C(H)2NCH CH OH-j-C,N,ON(NCMe)]ClO , 6, as a yellow
2
2
4
346
New J. Chem., 2001, 25, 344È352

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in these compounds. The 31PM1HN NMR spectrum of 7 shows
a sharp singlet at 37.17 ppm and the 13CM1HN NMR spectra
of 7 and 8 show the expected resonances for the proposed
structures. Moreover, the O-coordination of the OH group in
complex 7 has been unambiguously established by X-ray crys-
tallographic methods (see below).
by coupling with the 31P nuclei. Also, the resonance assigned
to the OH proton appears at 2.75 ppm, shifted to higher Ðeld
compared to the starting compound 6.
X-Ray crystal structures of complexes 4 Æ CHCl and 7
3
Similar results have been obtained in reactions between the
solvate complex 6 and classical chelating N,N-bidentate
ligands such as bipy (2,2@-bipyridyl) or tmeda (N,N,N@,N@-
tetramethylethylenediamine). The reaction of 6 with bipy or
tmeda results in the precipitation of orange solids of stoichi-
ometry [PdMC H (OMe) C(H)NCH CH OHN(LÈL)](ClO )
Crystals of complexes 4 and 7 of sufficient quality for X-ray
measurements were grown by slow vapour condensation of
Et O over a CHCl (4) or CH Cl (7) solution of the corre-
sponding compound. The more relevant parameters concern-
ing the data collection and reÐnement are presented in Table
1, and selected bond distances and angles are collected in
2
3
2 2
6
2
2
2
2
4
(LÈL \ bipy 9; tmeda 10), in accord with their elemental
analyses and mass spectra. The IR spectra of 9 and 10 show a
feature similar to that described for 7 and 8Èthat is, the
apparent disappearance of the OH band, probably obscured
by the strong polyethylene absorption. The 1H NMR spec-
trum of 9 is particularly informative. The resonance attributed
to the OH proton appears as a poorly deÐned triplet at 5.06
ppm, in the same region as that observed for complexes 6È8,
suggesting the coordination of the OH group. The aromatic
region (6.5È9 ppm) shows the presence of seven di†erent reso-
nances, with relative intensities 2 : 2 : 2 : 1 : 2 : 1 : 1. The three
resonances with intensity 1 can be attributed to the iminic
proton and to the aromatic protons H and H of the ortho-
Tables 2 (4 É CHCl ) and 3 (7). Fig. 1 shows a drawing of
3
complex 4 and Fig. 2 a drawing of the cationic organometallic
fragment of complex 7.
The palladium atom in 4 is located in a slightly distorted
square-planar environment, surrounded by the C and N
atoms of the orthometallated imine ligand, the P atom of the
PPh ligand and the Cl atom. The structural parameters
3
(bond distances and angles) of the PPh and the chlorine
3
Table
1 Crystal data and structure reÐnement for complexes
4 É CHCl and 7
3
3
6
metallated group, by comparison of their chemical shifts with
those seen for the preceding complexes. Thus, the four reso-
nances with intensity 2 should be assigned to the aromatic
protons of the bipy ligand, indicating that the two rings
behave as equivalent on the NMR time scale. This fact strong-
ly suggests that the bipy ligand is not coordinated through
both nitrogen atoms, since in that case the OH group would
no longer be bonded to the Pd atom (in spite of its chemical
shift) and because the two halves of the bipy ligand would be
inequivalent, giving eight di†erent resonances. Moreover, the
equivalence of the two halves of the bipy ligand also suggests
that the molecular plane is a plane of symmetry on the NMR
time scale, which can easily be rationalized through either a
dissociative mechanism of the PdÈN bond or a Ñuxional
process. The Ñuxional process could be ““a single oscillatory
motion of the potentially didentate ligand via a trigonal-
bipyramidal transition stateÏÏ, which has been reported to
account for the behaviour of (NBu )[Pt(C F ) (LÈL)] (LÈ
4 É CHCl
7
3
Empirical formula
Formula weight
C
731.78
296(2)
0.710 73
Monoclinic
H
Cl NO PPd
C
676.35
293(2)
0.710 73
Orthorhombic
H
ClNO PPd
30 30
4
3
29 29
7
T /K
j/A
Crystal system
Space group
P2 /c
Pna2
1
1
a/A
b/A
c/A
b/¡
16.795(3)
23.732(2)
12.090(3)
17.268(2)
116.549(12)
3136.6(10)
4
1.015
7456
8.039(2)
14.922(2)
U/A
Ž
3
2846.8(8)
4
0.850
2606
Z
k/mm~1
Collected reÑections
Unique reÑections
7172
2600
R
0.0184
0.0340
0.0826
0.0436
0.0506
0.1054
int
R a[I [ 2p(I)]
1
wR b[I [ 2p(I)]
2
4
6 5 3
a R \ &pF o [ o F p/& o F o . b wR \ [&w(F2 [ F2)2/&w(F2)2]1@2.
L \ phen, bipy).22 Unfortunately, complex 9 is only soluble in
1
o
c
o
2
o
c
o
DMSO-d (and then only slightly), precluding measurements
at low temperature and also the measurement of the 13C
6
NMR spectrum.
We believe that all of these facts are in good agreement with
the stereochemistry depicted in Scheme 1 for complex 9, in
which the OH fragment remains coordinated to the Pd atom
and the bipy ligand acts as an N-monodentate ligand. The
analysis of the 1H NMR spectrum of 10 leads to similar con-
clusions.
The displacement of the OH group from the coordination
sphere of the Pd atom can be accomplished easily by using
strong phosphorus chelating ligands, such as dppe
[bis(diphenylphosphino)ethane]. The reaction of 6 with dppe
gives an orange solid identiÐed as [PdMC H -4,5-(OMe) -2-
6
2
2
C(H)2NCH CH OHN(dppe)](ClO ), 11, according to its ele-
2
2
4
mental analysis. The IR spectrum of 11 now clearly shows the
OH stretch at 3500 cm~1, suggesting that the oxygen atom of
the OH group is not bonded to the Pd atom, as described for
2È5. Moreover, the 31PM1HN NMR spectrum of 11 shows the
presence of two chemically inequivalent P atoms, strongly
shifted downÐeld with respect to their position in the free
phosphine, indicating that both P atoms are bonded to the Pd
centre, as depicted in Scheme 1. The 1H NMR spectrum of 11
gives additional proof of the proposed stereochemistry, with
Fig. 1 Thermal ellipsoid plot of complex [Pd(C H -4,5-(OMe) -2-
6
2
2
C(H)2NCH CH OH)Cl(PPh )], 4. Ph groups of the PPh fragment
2
2
3
3
the resonances attributed to the iminic proton and to the H
(except C ) are omitted for clarity. Atoms are drawn at 50% prob-
3
ipso
and H protons appearing as doublets or doublets of doublets
ability level.
6
New J. Chem., 2001, 25, 344È352
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Table 2 Selected bond lengths (A) and angles (¡) for 4 É CHCl
3
Pd(1)ÈC(1)
2.025(2)
2.2625(8)
1.390(3)
1.393(4)
1.399(4)
1.429(4)
1.373(3)
1.445(3)
1.467(3)
1.409(4)
1.823(3)
81.53(9)
174.34(6)
91.27(6)
122.0(2)
116.8(2)
119.3(2)
128.69(18)
110.2(3)
107.04(12)
113.21(9)
114.88(10)
Pd(1)ÈN(1)
2.103(2)
2.3892(8)
1.406(4)
1.367(3)
1.416(4)
1.371(4)
1.394(4)
1.275(3)
1.496(4)
1.822(3)
1.825(3)
95.01(7)
166.81(7)
92.98(3)
121.2(2)
118.8(2)
112.02(17)
111.5(2)
103.81(12)
103.45(12)
113.39(9)
Pd(1)ÈP(1)
Pd(1)ÈCl(1)
C(1)ÈC(2)
C(1)ÈC(6)
C(2)ÈC(3)
C(3)ÈO(1)
C(3)ÈC(4)
O(1)ÈC(9)
C(8)ÈO(2)
C(4)ÈC(5)
C(4)ÈO(2)
C(5)ÈC(6)
C(6)ÈC(7)
C(7)ÈN(1)
N(1)ÈC(10)
C(10)ÈC(11)
C(11)ÈO(3)
P(1)ÈC(24)
P(1)ÈC(18)
P(1)ÈC(12)
C(1)ÈPd(1)ÈN(1)
N(1)ÈPd(1)ÈP(1)
N(1)ÈPd(1)ÈCl(1)
C(5)ÈC(6)ÈC(1)
C(1)ÈC(6)ÈC(7)
C(7)ÈN(1)ÈC(10)
C(10)ÈN(1)ÈPd(1)
O(3)ÈC(11)ÈC(10)
C(24)ÈP(1)ÈC(12)
C(24)ÈP(1)ÈPd(1)
C(12)ÈP(1)ÈPd(1)
C(1)ÈPd(1)ÈP(1)
C(1)ÈPd(1)ÈCl(1)
P(1)ÈPd(1)ÈCl(1)
C(5)ÈC(6)ÈC(7)
N(1)ÈC(7)ÈC(6)
C(7)ÈN(1)ÈPd(1)
N(1)ÈC(10)ÈC(11)
C(24)ÈP(1)ÈC(18)
C(18)ÈP(1)ÈC(12)
C(18)ÈP(1)ÈPd(1)
Fig. 2 Thermal ellipsoid plot of the [Pd(C H -4,5-(OMe) -2-
6
2
2
C(H)2NCH CH OH)(PPh )]` cation of complex 7. Ph groups of the
2
2
3
PPh fragment (except C ) and H atoms are omitted for clarity.
3
ipso
Atoms are drawn at 50% probability level.
ligands are similar to those found in other complexes contain-
ing these coordinated groups.23 The PdÈC(1) [2.025(2) A] and
the PdÈN(1) [2.103(2) A] bond distances, corresponding to
the orthometallated imine, are slightly longer that those
found in other metallated imines. For instance, the values
reported in the related dinuclear complexes [PdM3,4-
(OCH O)C H C(H)2N(Cy)-C2,NN(l-O CMe)] and [PdM3,4-
4 by chloride abstraction is thus occupied by the oxygen
atom. The bond distances PdÈC(1) [2.002(12) A], PdÈN(1)
[2.015(8) A] and PdÈP(1) [2.264(3) A] are similar to values
found for related [C,N,O]-complexes.13a The PdÈO(1) bond
distance is 2.216(8) A, longer than those reported previously
for similar structural situations. The PdÈO(H) bond distances
found in related palladium complexes are: 2.076(4) A in
2
6
2
2
2
(OCH CH O)C H C(H)2N(Cy)-C6,NN(l-O CMe)] for PdÈ
2
2
6
2
2
2
C are 1.974(2) and 1.949(6) A, and for PdÈN 2.018(2) and
2.015(5) A, respectively.12c On the other hand, there is no
hydrogen bond between the OH group and the Cl ligand, in
spite of their proximity. This type of intramolecular H-
bonding is not uncommon and it has been reported in com-
plexes such as [PdBrMC H (CH CH OH)-2N(tmeda)].15b
[PdMC H (CH CH OH)-2N(tmeda)]NO ,15b 2.045(6)
A in
6
4
2
2
3
[PdClL] [Pd Cl ] [where L \ 1-(2-hydroxyethyl)-(2-amino-
2
2 6
ethyl-N2)-5-methylisocytosine],15d 2.059(4) A in M[Me C(OH)-
2
CH C(O)NMe ]PdCl(NO )N ,15a and 2.148(2) A in [PdCl -
MPh PCH S(O)MeN(MeOH)].15c This long PdÈO bond dis-
2
2
2 2
2
2
2
6
4
2
2
tance can be explained taking into account the O-
coordination trans to the soft aryl carbon atom and the
high trans inÑuence of the latter. For example, the PdÈO
The palladium atom in complex 7 is also located in a slight-
ly distorted square-planar environment, now surrounded by
the C and N atoms of the orthometallated imine ligand, the P
bond
distance
reported
for
the
aqua-complex
atom of the PPh ligand and the oxygen atom of the alcoholic
3
[Pd(dmba)MC(H)(PPh )C(O)NMe N(OH )]ClO , [2.200(5)
group, showing the terdentate [C,N,O]-coordination of the
3
2
2
4
A],24 (in which the OH ligand is O-bonded trans to the
functionalised imine ligand. The vacant position generated in
2
orthometallated carbon atom) is similar to that found here.
Finally, there is an intermolecular hydrogen bond between the
hydroxyl group of the organometallic cation and one oxygen
of the perchlorate anion [O(1)ÈH(1)ÈO(6), 2.90(2) A,
H(1)É É ÉO(6), 2.24 A, O(1)ÈH(1)É É ÉO(6) 137.5¡].
Table 3 Selected bond lengths (A) and angles (¡) for 7
Pd(1)ÈC(1)
2.002(12)
2.216(8)
1.339(16)
1.418(18)
1.391(19)
1.39(2)
1.397(18)
1.370(16)
1.480(19)
1.445(15)
82.6(5)
Pd(1)ÈN(1)
2.015(8)
2.264(3)
1.438(16)
1.439(17)
1.380(17)
1.374(17)
1.275(17)
1.279(17)
1.46(2)
Pd(1)ÈO(1)
Pd(1)ÈP(1)
C(1)ÈC(6)
C(1)ÈC(2)
C(2)ÈC(3)
C(2)ÈC(9)
Conclusion
C(3)ÈC(4)
C(4)ÈO(2)
In conclusion, we have synthesized orthometallated complexes
derived from the imino alcohol C H -3,4-(OMe) -
C(4)ÈC(5)
C(5)ÈO(3)
C(5)ÈC(6)
O(2)ÈC(7)
6
3
2
O(3)ÈC(8)
C(9)ÈN(1)
C(H)2NCH CH OH 1, in which this ligand acts as a C,N-
2
2
N(1)ÈC(10)
C(10)ÈC(11)
chelating ligand (2È5, 11) or as a C,N,O-terdentate ligand
(6È10). The stability of the PdÈOH bond has been investigated
and we have shown that this bond is remarkably stable
C(11)ÈO(1)
O(1)ÈH(1)
0.8200
160.4(4)
96.1(4)
C(1)ÈPd(1)ÈN(1)
N(1)ÈPd(1)ÈO(1)
N(1)ÈPd(1)ÈP(1)
C(6)ÈC(1)ÈC(2)
C(2)ÈC(1)ÈPd(1)
C(3)ÈC(2)ÈC(9)
C(4)ÈC(3)ÈC(2)
O(2)ÈC(4)ÈC(5)
O(3)ÈC(5)ÈC(4)
C(4)ÈC(5)ÈC(6)
C(7)ÈO(2)ÈC(4)
N(1)ÈC(9)ÈC(2)
C(9)ÈN(1)ÈPd(1)
C(11)ÈC(10)ÈN(1)
C(11)ÈO(1)ÈPd(1)
Pd(1)ÈO(1)ÈH(1)
C(1)ÈPd(1)ÈO(1)
C(1)ÈPd(1)ÈP(1)
O(1)ÈPd(1)ÈP(1)
C(6)ÈC(1)ÈPd(1)
C(3)ÈC(2)ÈC(1)
C(1)ÈC(2)ÈC(9)
O(2)ÈC(4)ÈC(3)
C(3)ÈC(4)ÈC(5)
O(3)ÈC(5)ÈC(6)
C(1)ÈC(6)ÈC(5)
C(8)ÈO(3)ÈC(5)
C(9)ÈN(1)ÈC(10)
C(10)ÈN(1)ÈPd(1)
O(1)ÈC(11)ÈC(10)
C(11)ÈO(1)ÈH(1)
77.9(5)
towards neutral monodentate ligands L (PPh , py) and even
174.6(3)
118.9(12)
108.7(9)
122.0(12)
117.9(12)
116.3(13)
116.8(13)
119.0(13)
123.7(13)
114.9(12)
115.8(9)
110.2(12)
110.3(8)
126.9
103.5(2)
132.4(10)
120.2(12)
117.7(12)
121.8(13)
121.6(12)
124.2(15)
122.4(12)
118.8(12)
126.5(9)
116.6(10)
109.8(14)
109.5
3
towards classical neutral N,N-bidentate chelating ligands such
as bipy or tmeda. The stability of the PdÈOH bond, together
with the possibility of modifying the substituents on the
orthometallated ring or of introducing chirality into the alco-
holic fragment, suggests interesting possibilities for the uti-
lisation of complexes of this type as versatile chiral catalysts.
In fact, preliminary results of the catalytic activity of complex-
es 2, 3, 6 and 7 in the Heck reaction of methyl acrylate with
iodobenzene, 4-bromobenzonitrile or 4-bromobenzaldehyde
show that these complexes behave as good catalysts, giving
yields of the corresponding oleÐn of about 80% with catalyst
concentrations as low as 10~3 mol%. These results, together
348
New J. Chem., 2001, 25, 344È352

View Article Online
with the synthesis of new chiral complexes based on chiral
amino alcohols and their applications in asymmetric Heck-
type reactions, will be reported in due course.
(C2N), 149.20, 148.57, 146.30, 136.73, 113.97, 109.77 (C H ),
6
2
61.09, 60.82 (2 CH ), 56.15, 55.85 (2 CH O), 24.39 (CH ).
2
3
3
[Pd(l-Cl){C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
6
2
3
2
2
2
C ,N} ] , 3. As described for 2, a suspension of Pd(OAc) (0.50
Experimental
1
2
2
g, 2.2 mmol) in MeOH (20 mL) and the imine 1 (0.46 g, 2.2
mmol) were reÑuxed for 1.5 h. The hot solution was Ðltered in
order to remove the Pd0 formed. The resulting orange solu-
tion was treated with LiCl (0.19 g, 4.5 mmol), resulting in the
precipitation of 3 as a yellow solid, which was Ðltered, washed
with MeOH (20 mL) and air dried. Obtained: 0.640 g (81.6%
Safety note: Caution! Perchlorate salts of metal complexes
with organic ligands are potentially explosive. Only small
amounts of these materials should be prepared and they
should be handled with great caution. See ref. 25.
General procedures
yield). Anal. calc. for C
N, 4.00%. Found: C, 37.89; H, 4.71; N, 4.05%. MS (FAB])
m/z (%): 665 (19) [M [ Cl]`. IR (l cm~1): 3529 (l ), 1618
H
Cl N O Pd : C, 37.73; H, 4.03;
22 28
2
2
6
2
Solvents were dried and distilled under nitrogen before use:
diethyl ether and tetrahydrofuran over benzophenone ketyl,
dichloromethane and chloroform over P O , acetonitrile over
OhH
(l
), 1589, 1549 (l
), 277 (l
). 1H NMR (DMSO-d ,
C/N
C/C
PdhCl
6
2
5
RT) d: 7.95 (s, 1H, HC2N), 7.67, 7.12 (2s, 2H, H , H ), 4.77 (s,
CaH , methanol over magnesium and n-hexane and toluene
3
6
2
1H, OH), 3.73È3.69 (m, 10H, 2 CH O ] 2 CH ). 13CM1HN
over sodium. Elemental analyses were carried out on a
3
2
NMR (DMSO-d , RT) d: 177.71 (C2N), 151.68, 149.25,
PerkinÈElmer 240-B microanalyser. Infrared spectra (4000È
200 cm~1) were recorded on a PerkinÈElmer 883 infrared
spectrophotometer from nujol mulls between polyethylene
sheets. 1H (300.13 MHz), 13CM1HN (75.47 MHz) and 31PM1HN
6
146.25, 138.38, 115.27, 112.00 (C H ), 60.65, 59.35 (2 CH ),
6
2
2
55.59, 55.34 (2 CH O).
3
(121.49 MHz) NMR spectra were recorded in CDCl or
[PdCl{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
3
6
3
2
3
2
2
2
CD Cl solutions at room temperature (unless otherwise
C ,N}(PPh )], 4. To a yellow suspension of complex 3 (0.502
2
2
1
stated) on a Bruker ARX-300 spectrometer; 1H and 13CM1HN
were referenced using the solvent signal as internal standard
and 31PM1HN was externally referenced to H PO (85%).
g, 0.71 mmol) in 20 mL of CH Cl , PPh (0.376 g, 1.43 mmol)
2
2
3
was added, giving a yellow solution within a few seconds. This
solution was stirred at room temperature for 1.5 h, then
evaporated to dryness. The yellow residue was treated with
3
4
Mass spectra (positive ion FAB) were recorded on a VG
Autospec spectrometer from CH Cl solutions.
Et O (25 mL), giving 4 as a yellow solid. This solid was Ðl-
2
2
2
tered, washed with Et O (20 mL) and air dried. Obtained:
2
Syntheses
0.793 g (90.7% yield). Anal. calc. for C
56.87; H, 4.77; N, 2.28%. Found: C, 56.71; H, 4.67; N, 2.15%.
H
ClNO PPd: C,
29 29
3
C H -3,4-(CH O) -C(H)2NCH CH OH, 1. To a solution
MS (FAB]) m/z (%): 576 (100) [M [ Cl]`. IR (l cm~1):
6
3
3
2
2
2
of 3,4-dimethoxybenzaldehyde (4.90 g, 29.5 mmol) in CH Cl
3459 (l ), 1621 (l
), 1579, 1551 (l
), 293 (l
). 1H
2
2
4
OhH C/N
C/C
PdhCl
(20 mL), H NCH CH OH (1.84 g, 29.51 mmol) and MgSO
NMR (CD Cl , 218 K) d: 8.09 (d, 1H, C(H)2N, 4J \ 8.1),
2
2
2
2
2
PhH
were added. The resulting mixture was stirred at room tem-
perature for 2 h, then Ðltered. The resulting solution was
evaporated to dryness and the solid residue was treated with
n-hexane, giving 1 as a white solid. This solid was Ðltered,
washed with additional n-hexane (20 mL) and air dried.
7.70È7.64 (m, 6H, H , Ph), 7.5È7.45 (m, 3H, H , Ph), 7.40È7.36
o
p
(m, 6H, H , Ph), 6.85 (s, 1H, H ), 5.83 (d, 1H, H , 4J \ 6),
PhH
3.94, 3.90 (m, 4H, 2 CH ), 3.65 (s, 3H, CH O), 3.24 (t, 1H, OH,
m
3
6
2
3
3J
\ 5 Hz), 2.73 (s, 3H, CH O). 31PM1HN NMR (CDCl ,
HhH
3
3
RT) d: 43.42. 13CM1HN NMR (CDCl , RT) d: 176.08 (C2N),
3
Obtained: 4.81 g (77% yield). Anal. calc. for C
63.14; H, 7.22; N, 6.69%. Found: C, 62.62; H, 7.74; N, 7.43%.
H
NO : C,
151.43, 148.91, 145.57, 139.51, 110.78 (C H ), 121.51 (d, C ,
11 15
3
6
2
6
p
3J \ 14.5), 135.38 (d, C , Ph, 2J \ 12.05), 130.91 (d, C ,
ChP ChP
Ph, 4J \ 1.5), 130.87 (d, C , 1J \ 50.5), 128.15 (d, C ,
ChP ChP
3J \ 11.3 Hz), 62.5, 60.34 (2 CH ), 55.82, 55.03 (2 CH O).
ChP
o
IR (l, cm~1): 3195 (l ), 1645 (l
), 1602, 1586, 1515 (l
).
OhH
C/N
C/C
i
m
1H NMR (CDCl , RT) d: 8.14 (s, 1H, HC2N), 7.35 (d, 1H,
3
2
3
H , 4J
\ 1.2), 7.06 (dd, 1H, H , 3J
\ 8.4, 4J
\ 1.2),
2
HhH
6
HhH
HhH
6.81 (d, 1H, H , 3J
\ 8.4 Hz), 3.86 (m, 8H, 2 CH O
[PdCl{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
5
HhH
3
] CH ), 3.67 (m, 2H, CH ), 2.82 (br, 1H, OH). 1H NMR
6
2
3
2
2
2
C ,N}(py)], 5. Complex 5 was obtained in a similar way as
2
2
(CD Cl , 218 K) d: 7.80 (s, 1H, HC2N), 7.16 (s, 1H, H ), 6.74,
1
that described for 4: complex 3 (0.30 g, 0.42 mmol) reacts with
2
2
2
6.72 (m, 2H, H , H ), 5.66 (br, 1H, OH), 3.86 (m, 8H, 2 CH O
pyridine (0.066 g, 0.84 mmol) in CH Cl (20 mL) to give 5 as a
5
6
3
] CH ), 3.56 (m, 2H, CH ). 13CM1HN NMR (CDCl , RT) d:
162.76 (C2N), 151.39, 149.19, 128.94 (C , C , C ), 123.29,
2
2
yellow solid. Obtained 0.327 g (90% yield). Anal. calc. for
2
2
3
1
C
H
ClN O Pd: C, 44.77; H, 4.46; N, 6.53%. Found: C,
4
3
110.28, 109.65 (C , C , C ), 63.22, 62.29 (CH ), 55.88 (2 over-
16 19
2 3
45.28; H, 4.53; N, 6.68%. MS (FAB]) m/z (%): 393 (20)
2
5
6
2
lapped CH O).
[M [ Cl]`. IR (l cm~1): 3394 (l ), 1622 (l
), 1604, 1591,
). 1H NMR (CD Cl , 218 K) d: 8.78 (d,
\ 5), 7.90È7.85 (m, 2H, H (py) ] HC2N),
3
OhH
C/N
1548 (l
), 304 (l
[Pd(l-OAc){C H -4,5-(CH O) - 2-C(H)2NCH CH OH-
C/C
2H, H , py, 3J
PdhCl
2 2
6
2
3
2
2
2
j-C ,N} ] , 2. To a methanolic (20 mL) suspension of
o
HhH
p
7.43È7.38 (m, 2H, H , py), 6.90 (s, 1H, H ), 5.50 (s, 1H, H ),
1
2
Pd(OAc) (1.65 g, 7.35 mmol), the imine 1 was added (2.00 g,
9.57 mmol) and the resulting mixture was reÑuxed for 1.5 h.
m
3
2
6
3.96 (s, 2H, CH ), 3.78È3.74 (m, 5H, NCH ] CH O), 3.42 (s,
2
2
3
3H, CH O), 3.30 (t, 1H, OH, 3J
\ 5 Hz). 13CM1HN NMR
Some decomposition was evident and the hot solution was
Ðltered over celite. After cooling, a yellow solid precipitated,
3
HhH
(CDCl , RT) d: 176.10 (C2N), 153.23, 151.75, 146.37, 138.17,
3
114.49, 110.57 (C H ), 149.96, 138.00, 125.36 (py), 61.74, 61.56
which was collected, washed with MeOH (10 mL) and Et O
6
2
(2 CH ), 56.13, 55.48 (2 CH O).
2
(30 mL), air dried and identiÐed as 2. Obtained: 1.90 g (69.0%
2
3
yield). Anal. calc. for C
H
N O Pd : C, 41.74; H, 4.58; N,
26 34
2
10
2
3.75%. Found: C, 41.11; H, 4.59; N, 3.01%. IR (l cm~1):
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
6 2 3 2 2 2
3515, 3383 (l ), 1607 (l
] l ), 1577, 1552 (l
). 1H
C ,N,O}(NCMe)](ClO ), 6. To a solution of 3 (1.194 g, 1.70
1 4
OhH
C/N
CO
C/C
NMR (CD Cl , 218 K) d: 7.43 (s, 1H, HC2N), 6.64, 6.34 (2s,
mmol) in NCMe (50 mL), AgClO (0.707 g, 3.40 mmol) was
2
2
4
2H, H , H ), 3.78 (s, 3H, CH O), 3.69 (s, 3H, CH O), 3.61 (br,
added. The resulting suspension was stirred at room tem-
3
6
3
3
2H, CH ), 3.22 (t, 1H, OH, 3J
\ 5), 3.08 (d, 1H, CH ,
perature for 30 min with exclusion of light. The AgCl precipi-
tated was removed by Ðltration and the resulting yellow
solution was evaporated to dryness. The yellow residue was
2
HhH
2
2J
\ 12.6), 2.82 (d, 1H, CH , 2J
\ 12.6 Hz), 2.08 (s, 3H,
HhH
2
HhH
OAc). 13CM1HN NMR (CDCl , RT) d: 181.67 (CO ), 173.49
3
2
New J. Chem., 2001, 25, 344È352
349

View Article Online
treated with Et O (50 mL) giving 6 as a yellow solid, which
and its colour changed from yellow to orange. Stirring was
continued at room temperature and, after the initial disso-
lution, an orange solid precipitated. This suspension was
stirred for 4 h and the solid obtained, 9, was Ðltered, washed
with CH Cl and air dried. Obtained: 0.225 g (85.8% yield).
2
was Ðltered, washed with additional Et O (30 mL) and air
2
dried. Obtained: 1.215
g
(78.2% yield). Anal. calc. for
C
H
ClN O Pd: C, 34.30; H, 3.76; N, 6.15%. Found: C,
13 17
2 7
33.97; H, 4.11; N, 6.84%. MS (FAB]) m/z (%): 355 (11)
2
2
[M [ ClO ]`, 314 (100) [M [ ClO [ NCMe]`. IR (l
The product precipitated with 1.25 molecules of CH Cl ,
4
4
2 2
cm~1): 3251 (l ), 2328, 2312, 2285 (l ), 1612 (l ), 1590,
which could not be removed by recrystallization, nor by
heating the product. The amount of the solvent of crys-
tallization was determined by 1H NMR integration of
OhH
1553 (l ). 1H NMR (DMSO-d , RT) d: 7.95 (s, 1H, HC2N),
CJC
7.10 (s, 1H, H ), 6.86 (s, 1H, H ), 5.01 (t, 1H, OH, 3J
CK N
CJN
6
3
\ 5
Hz), 3.78 (s, 3H, CH O), 3.70È3.65 (m, 5H, CH O ] CH ),
6
HhH
the
C
corresponding
resonance.
Anal.
calc.
for
3
3
2
3.50 (m, 2H, CH ), 2.09 (s, 3H, NCCH ). 13CM1HN NMR
H ClN O Pd É 1.25CH Cl : C, 39.51; H, 3.65; N, 6.21%.
2
3
21 22
3
7
2 2
(DMSO-d , RT) d: 176.86 (C2N), 149.05, 146.62, 137.87,
Found: C, 39.34; H, 3.58; N, 6.39%. MS (FAB]) m/z (%):
6
114.58, 111.93 (C H ), 60.07, 59.14 (2 CH ), 55.60, 55.48 (2
470 (37) [M [ ClO ]`. IR (l cm~1): 1607 (l
), 1588, 1549
6
2
2
4
C/N
CH O), 1.07 (NCCH ). Two quaternary C atoms were not
found, one in the C H ring and the N3 C carbon.
(l
C/C
3J
). 1H NMR (DMSO-d , RT) d: 8.86 (d, 2H, H , bipy,
3
3
2
6
d
a
\ 5.5), 8.58 (d, 2H, H , bipy, 3J
\ 7.5 Hz), 8.36 (br,
6
HhH
HhH
pseudo t, 2H, H , bipy), 8.10 (s, 1H, HC2N), 7.86 (br, t, 2H,
c
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
H , bipy), 7.15 (s, 1H, H ), 6.50 (s, 1H, H ), 5.06 (br, t, 1H,
6
2
3
4
2
2
2
b
3
3
6
C ,N,O}(PPh )](ClO ), 7. Method a. To a suspension of
OH), 3.77 (br, 10H, 2 CH O ] 2 CH ). The product was too
1
3
2
complex 4 (0.250 g, 0.408 mmol) in acetone (20 mL), AgClO
insoluble for 13C NMR measurements.
4
(0.085 g, 0.41 mmol) was added and the resulting suspension
was stirred for 30 min at room temperature with exclusion of
light. This suspension was Ðltered and the resulting solution
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
6
2
3
4
2
2
2
C ,N,O}(tmeda)](ClO ), 10. Complex 10 was synthesized fol-
1
was evaporated to dryness. By Et O addition (20 mL) and
lowing the same procedure as for 9. Complex 6 (0.200 g, 0.439
mmol) reacted with N,N,N@,N@-tmeda (0.056 g, 0.44 mmol) in
CH Cl (20 mL), giving 10 as an orange solid. Obtained:
2
continuous stirring, complex 7 was obtained as a yellow solid,
which was Ðltered and air dried. Obtained: 0.244 g (88.4%
yield).
2
2
0.203 g (87.0% yield). Anal. calc. for C
H
ClN O Pd É
17 30
3 7
Method b. To a suspension of complex 6 (0.219 g, 0.481
0.5CH Cl : C, 36.69; H, 5.45; N, 7.33%. Found: C, 36.42; H,
2
2
mmol) in CH Cl (20 mL), PPh was added (0.288 g, 1.098
5.23; N, 7.34%. MS (FAB]) m/z (%): 430 (85) [M [ ClO ]`,
2
2
3
4
C/N
mmol). The initial suspension gradually dissolved and, after 15
min stirring at room temperature, a clear yellow solution was
obtained. Removal of the solvent and treatment of the residue
316 (11) [M [ ClO [ tmeda]`. IR (l cm~1): 1608 (l
),
4
1580, 1553 (l
). 1H NMR (DMSO-d , RT) d: 8.01 (s, 1H,
C/C
6
HC2N), 7.15 (s, 1H, H ), 6.67 (s, 1H, H ), 5.03 (t, 1H, OH,
3
6
with Et O gave 7 as a yellow solid. Obtained: 0.265 g (81.5%
3J
\ 4.8 Hz), 3.87 (s, 3H, CH O), 3.72 (s, 3H, CH O), 3.64
(m, 2H, CH ), 3.53 (m, 2H, CH ), 2.91 (br, 8H, 2 NMe
] CH , tmeda), 2.65 (br, 8H, 2 NMe ] CH , tmeda). The
product was too insoluble for 13C NMR measurements.
2
HhH
3
3
yield). Anal. calc. for C
H
ClNO PPd: C, 51.49; H, 4.32; N,
29 29
7
2
2
2
2.07%. Found: C, 51.46; H, 4.23; N, 1.95%. MS (FAB]) m/z
2
2
2
(%): 576 (100) [M [ ClO ]`, 314 (19) [M [ ClO [ PPh ]`.
4
C/N
4
3
IR (l cm~1): 1632 (l
), 1588, 1551 (l
). 1H NMR
C/C
(CD Cl , 218 K) d: 8.63 (d, 1H, HC2N, 4J \ 9), 7.69È7.42
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
2
2
PhH
(m, 15H, Ph), 6.93 (s, 1H, H ), 5.86 (d, 1H, H , 4J \ 5.1),
6
2
3
2
2
2
C ,N}(dppe)](ClO ), 11. To a suspension of complex 6 (0.200
3
6
PhH
5.50 (t, 1H, OH, 3J
\ 5 Hz), 4.13, 3.91, (m, 4H, 2 CH ),
1
4
g, 0.439 mmol) in CH Cl (20 mL) was added dppe (0.175 g,
HhH
2
3.76, 2.90 (2s, 6H, 2 CH O). 31PM1HN NMR (CDCl , RT) d:
2
2
0.439 mmol). The initial yellow suspension gradually dis-
solved, giving an orange solution. This solution was stirred for
15 min at room temperature, then evaporated to dryness. By
3
3
37.17. 13CM1HN NMR (CDCl , RT) d: 173.03 (C2N), 150.10
3
(d, C , 2J \ 5.4), 147.06, 142.07, 128.78, 112.85 (C H ),
1
PhC
6
6 2
121.68 (d, C , 3J \ 10.9), 135.14 (d, C , PPh , 2J \ 12.6
addition of Et O (25 mL) and continuous stirring, 11 was
ChP
Hz), 132.15 (d, C , PPh , 4J \ 1.9), 129.50 (d, C , PPh ,
ChP
3J \ 11.0 Hz), 67.75, 57.07 (2 CH ), 56.38, 55.55 (2 CH O).
ChP
The C of the PPh ligand was not found.
o
3
ChP
m
2
obtained as an orange solid, which was Ðltered and air dried.
p
3
3
Obtained: 0.192
g
(53% yield). Anal. calc. for
2
3
C
H
ClNO P Pd É 0.75CH Cl : C, 51.75; H, 4.54; N,
i
3
37 38
7 2
2 2
1.59%. Found: C, 51.79; H, 4.43; N, 1.85%. IR (l cm~1): 3500
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
(l ), 1614 (l
), 1584, 1548 (l
). 1H NMR (CDCl , RT)
6
2
3
2
2
2
C ,N,O}(py)](ClO ), 8. Complex 8 was obtained following
OH
C/N
C/C
3
d: 8.28 (d, 1H, HC2N, 4J \ 8.1), 7.84È7.46 (m, 20H, Ph),
1
4
the same experimental method as that described for 7 in
method a. Complex 5 (0.250 g, 0.582 mmol) reacted with
AgClO (0.121 g, 0.582 mmol) in acetone to give 8 as a yellow
solid. Obtained: 0.132 g (45.81% yield). Anal. calc. for
PhH
7.06 (d, 1H, H , 5J \ 3), 6.10 (dd, 1H, H , 4J
\ 5.4,
3
PhH
6
PcishH
2
4J
\ 8.4), 3.74 (s, 3H, OCH ), 3.41 (m, 2H, CH ), 2.93 (s,
PtranshH
3
3H, OCH ), 2.87 (m, 2H, CH ), 2.75 (t, 1H, OH, 3J
\ 6
4
3
2
HhH
Hz), 2.48È2.30 (m, 4H, CH -dppe). 31PM1HN NMR (CDCl ,
RT) d: 61.24 (d, 3J \ 25.6 Hz), 42.69 (d).
PhP
C
H
ClN O Pd: C, 38.96; H, 3.88; N, 5.68%. Found: C,
2
3
16 19
2 7
39.17; H, 3.91; N, 5.43%. MS (FAB]) m/z (%): 393 (100)
[M [ ClO ]`, 314 (65) [M [ ClO [ py]`. IR (l cm~1):
4
C/N
4
1607 (l
), 1588, 1558 (l
). 1H NMR (acetone-d , RT) d:
Crystal structure determination
C/C
6
9.00 (d, 2H, H , py, 3J
\ 5), 8.20 (t, 1H, H , py, 3J
\ 8
o
HhH
p
HhH
Hz), 8.10 (s, 1H, HC2N), 7.77 (dd, 2H, H , py), 7.16 (s, 1H,
Crystals of complexes 4 É CHCl and 7 of sufficient quality for
m
3
H ), 5.59 (s, 1H, H ), 4.92 (br, s, 1H, OH), 3.92 (br, s, 2H,
CH ), 3.75 (s, 3H, OCH ), 3.64 (m, 2H, CH ), 3.49 (s, 3H,
CH O). 13CM1HN NMR (acetone-d , RT) d: 177.18 (C2N),
150.55, 147.57, 139.14, 115.70, 112.71 (C H ), 153.43, 140.40,
127.02 (py), 61.46, 60.47 (2 CH ), 55.91, 55.29 (2 CH O). One
of the quaternary C atoms of the C H group was not found.
X-ray measurements were obtained by slow vapour conden-
3
6
sation of Et O over a CHCl (4) or CH Cl (7) solution of the
2
3
3
2
2
3
2 2
corresponding crude complex. Geometric and intensity data
were measured using normal procedures on an automated
Nonius CAD-4 four-circle di†ractometer. After preliminary
indexing and transformation of the cell to a conventional
setting, axial photographs were taken of the a-, b- and c-axes
to verify the Laue symmetry and cell dimensions. The scan
parameters for intensity data collection were chosen on the
basis of two-dimensional (uÈh) plots of 25 reÑections. Three
monitor reÑections were measured after every three hours of
6
6
2
2
3
6
2
[Pd{C H -4,5-(CH O) -2-C(H)2NCH CH OH-j-
6
2
3
2
2
2
C ,N,O}(bipy)](ClO ), 9. To a suspension of complex 6 (0.200
1
4
g, 0.439 mmol) in CH Cl , 2,2@-bipyridine (0.070 g, 0.44 mmol)
was added. The initial yellow suspension gradually dissolved
2
2
350
New J. Chem., 2001, 25, 344È352

View Article Online
Asymmetry, 1997, 8, 991; (c) M. Pabel, A. C. Willis and S. B.
Wild, Inorg. Chem., 1996, 35, 1244.
J. M. Vila, M. T. Pereira, J. M. Ortiguera, J. J. Fernandez, A.
Fernandez, M. Lopez-Torres and H. Adams, Organometallics,
1999, 18, 5484.
(a) H. Brunner, Angew. Chem., Int. Ed., 1999, 38, 1195; (b) M. R.
Meneghetti, M. Grellier, M. Pfe†er, J. Dupont and J. Fischer,
Organometallics, 1999, 18, 5560.
beam time, and the orientation of the crystal was checked
after every 400 intensity measurements. Absorption
corrections26 were based on azimuthal scans of 10 (4) or 12 (7)
reÑections that have Eulerian angle s spread between 50 and
[40¡ when in their bisecting positions. Accurate unit cell
dimensions were determined from 25 centered reÑections in
the 2h range 27.2 O 2h O 31.9¡ (4) or 24.0 O 2h O 35.0¡ (7),
each centered at four distinct goniometer positions. The struc-
tures were solved and developed by Patterson and Fourier
methods.27 All non-hydrogen atoms were reÐned with aniso-
tropic displacement parameters. The hydrogen atoms were
placed in idealized positions and treated as riding atoms,
except for those of the methyl groups, which were Ðrst located
in a local slant-Fourier calculation and then reÐned as riding
atoms with the torsion angles about the OÈC(methyl) bonds
treated as variables. Each hydrogen atom was assigned an iso-
tropic displacement parameter equal to 1.2 times the equiva-
lent parameter of its parent atom. The interstitial chloroform
8
9
10 R. Navarro and E. P. Urriolabeitia, J. Chem. Soc., Dalton T rans.,
1999, 4111 and references therein.
11 R. Navarro, J. Garc•a, E. P. Urriolabeitia, C. Cativiela and M. D.
D•az-de-Villegas, J. Organomet. Chem., 1995, 490, 35.
12 (a) C. R. Baar, L. P. Carbray, M. C. Jennings and R. J. Pud-
dephatt, J. Am. Chem. Soc., 2000, 122, 176; (b) A. J. Canty, J.
Patel, B. W. Skelton and A. H. White, J. Organomet. Chem., 2000,
599, 195; (c) B. Teijido, A. Fernandez, M. Lopez-Torres, S.
CastroÈJuiz, A. Suarez, J. M. Ortigueira, J. M. Vila and J. J.
Fernandez, J. Organomet. Chem., 2000, 598, 71 and references
therein; (d) G. W. V. Cave, N. W. Alcock and J. P. Rourke,
Organometallics, 1999, 18, 1801; (e) D. J. Cardenas, A. M. Echa-
varren and M. C. Ram•rez de Arellano, Organometallics, 1999, 18,
3337; ( f ) M. Albrecht, R. A. Gossage, A. L. Spek and G. van
Kooten, J. Am. Chem. Soc., 1999, 121, 11898; (g) A. El Hatimi, M.
Gomez, S. Jansat, G. Muller, M. FontÈBardia and X. Solans, J.
Chem. Soc., Dalton T rans., 1998, 4229; (h) M. H. T. Rietveld,
D. M. Grove and G. van Koten, New J. Chem., 1997, 21, 751; (i)
P. Steenwinkel, S. L. James, D. M. Grove, H. Kooijman, A. L.
Spek and G. van Koten, Organometallics, 1997, 16, 513; ( j) P.
Dani, T. Karlen, R. A. Gossage, W. J. J. Smeets, A. L. Spek and
G. van Koten, J. Am. Chem. Soc., 1997, 119, 11317; (k) J. M. Vila,
M. Gayoso, M. T. Pereira, M. Lopez-Torres, J. J. Fernandez, A.
Fernandez and J. M. Ortigueira, J. Organomet. Chem., 1996, 506,
165 and references therein.
in 4 É CHCl was disordered and modelled as three equally
3
populated congeners and their geometrical parameters
restrained to be similar. The geometrical parameters of the
perchlorate anion in 7 were also restrained to similarity. The
structure was reÐned to F 2 and all reÑections were used in
o
the least-squares calculations.28 Data reduction was done
using the program XCAD4B.29
CCDC reference number 440/240. See http://www.rsc.org/
suppdata/nj/b0/b006140i/ for crystallographic Ðles in .cif
format.
13 (a) A. Fernandez, M. Lopez-Torres, A. Suarez, J. M. Ortigueira,
T. Pereira, J. J. Fernandez, J. M. Vila and H. Adams, J.
Organomet. Chem., 2000, 598, 1; (b) D. R. Billodeaux, F. R.
Fronczek, A. Yoneda and G. R. Newkome, Acta Crystallogr.,
Sect. C, 1998, 54, 1439; (c) P. Arndt, C. Lefeber, R. Kempe and U.
Rosenthal, Chem. Ber., 1996, 129, 207; (d) L. A. van de Kuil,
Y. S. J. Veldhuizen, D. M. Grove, J. W. Zwikker, L. W. Jennes-
kens, W. Drenth, W. J. J. Smeets, A. L. Spek and G. van Koten,
J. Organomet. Chem., 1995, 488, 191; (e) A. Yoneda, T. Hakusi,
G. R. Newkome and F. R. Fronczek, Organometallics, 1994, 13,
4912; ( f ) A. Yoneda, G. R. Newkome, Y. Morimoto, Y. Higuchi
and N. Yasuoka, Acta Crystallogr., Sect. C, 1993, 49, 476.
14 A. Bader and E. Lindner, Coord. Chem. Rev., 1991, 108, 27.
Recent references about hemilability; (a) J. C. Shi, C. H. Yueng,
D. X. Wu, Q. T. Liu and B. S. Kang, Organometallics, 1999, 18,
3796; (b) E. Lindner, M. Schmid, P. Wegner, C. Nachtigal, M.
Steimann and R. Fawzi, Inorg. Chim. Acta, 1999, 296, 103
15 (a) N. H. Kiers, B. L. Feringa, H. Kooijman, A. L. Spek and
P. W. N. M. van Leeuwen, J. Chem. Soc., Chem. Commun., 1992,
1169; (b) P. L. Alsters, J. Boersma, W. J. J. Smeets, A. L. Spek
and G. van Koten, Organometallics, 1993, 12, 1639; (c) G. H.
Quek, P. H. Leung and K. F. Mok, Inorg. Chim. Acta, 1995, 239,
185; (d) C. Price, N. H. Rees, M. R. J. Elsegood, W. Clegg and A.
Houlton, J. Chem. Soc., Dalton T rans., 1998, 2001.
Acknowledgements
Funding by the Direccion General de Ensenanza Superior e
Investigacion Cient•Ðca (Spain, projects PB98-1595-C02-01
and PB98-1593) is gratefully acknowledged, and we thank
Prof. J. Fornies for invaluable logistical support.
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6
7
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351

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29 K. Harms, personal communication, 1995.
352
New J. Chem., 2001, 25, 344È352