Insertion of isocyanides across the Pd-C bond of phosphinoquinoline allyl palladium complexes bearing η1- and η3-coordinated allyl groups. A synthetic and mechanistic study

Article abstract of DOI:10.1021/om500057h

We undertook an exhaustive study on the structural characteristics and reactivity toward the insertion of isocyanides across the Pd-C bond of palladium complexes bearing coordinated chloride, bidentate phosphoquinolines as spectator ligands, and differently substituted allyl groups. It was shown that the allyl hapticity is influenced not only by the nature of the spectator ligand but also by the position of the methyl substituents on the allyl fragment. Thus, in the presence of chloride, the κ¹-η³ configuration is always assumed when the distorted 8-(diphenylphosphino)-2- methyl quinoline (DPPQ-Me) acts as ancillary ligand, whereas the unsubstituted 8-(diphenylphosphino)quinoline ligand (DPPQ) generally favors the κ²-η¹ configuration with the exception of the complex with the 2-methyl-substituted allyl fragment, which adopts the κ²-η³ configuration with chloride as the counterion. We have determined the reactivity toward the insertion of the isocyanide on the Pd-C bond, and we have observed decidedly different rate laws when η³- or η¹-allyl complexes were investigated. In particular, the rate law of the reaction involving the η¹- allyl derivatives displays a second-order dependence on complex and isocyanide concentration, whereas the insertion on η³-allyl complexes is better described by a first-order process. We have interpreted such experimental results on the basis of a general pre-equilibrium mechanism in which the observed rates of the studied reactions are governed by the magnitude of the equilibrium constant. Finally, we have determined the solid-state structure of the insertion product palladium(chloro)(8-(diphenylphosphino)quinoline)(2,6- dimethyl-N-(4-methylpent-3-enylidene)benzenamine) (complex 1Bd).

Full text of DOI:10.1021/om500057h

Article
pubs.acs.org/Organometallics
Insertion of Isocyanides across the Pd−C Bond of
Phosphinoquinoline Allyl Palladium Complexes Bearing η1- and
η3‑Coordinated Allyl Groups. A Synthetic and Mechanistic Study
L. Canovese,*,† F. Visentin,† C. Santo,† and V. Bertolasi‡
†Dipartimento di Scienze Molecolari e Nanosistemi, Universita
̀
Ca’ Foscari, Venice, Italy
‡Dipartimento di Chimica e Centro di Strutturistica Diffrattometrica, Universita
̀
di Ferrara, Ferrara, Italy
S
* Supporting Information
ABSTRACT: We undertook an exhaustive study on the structural
characteristics and reactivity toward the insertion of isocyanides
across the Pd−C bond of palladium complexes bearing coordinated
chloride, bidentate phosphoquinolines as spectator ligands, and
differently substituted allyl groups. It was shown that the allyl
hapticity is influenced not only by the nature of the spectator ligand
but also by the position of the methyl substituents on the allyl
fragment. Thus, in the presence of chloride, the κ1-η3 configuration is
always assumed when the distorted 8-(diphenylphosphino)-2-methyl
quinoline (DPPQ-Me) acts as ancillary ligand, whereas the
unsubstituted 8-(diphenylphosphino)quinoline ligand (DPPQ) gen-
erally favors the κ2-η1 configuration with the exception of the complex
with the 2-methyl-substituted allyl fragment, which adopts the κ2-η3 configuration with chloride as the counterion. We have
determined the reactivity toward the insertion of the isocyanide on the Pd−C bond, and we have observed decidedly different
rate laws when η3- or η1-allyl complexes were investigated. In particular, the rate law of the reaction involving the η1-allyl
derivatives displays a second-order dependence on complex and isocyanide concentration, whereas the insertion on η3-allyl
complexes is better described by a first-order process. We have interpreted such experimental results on the basis of a general pre-
equilibrium mechanism in which the observed rates of the studied reactions are governed by the magnitude of the equilibrium
constant. Finally, we have determined the solid-state structure of the insertion product palladium(chloro)(8-
(diphenylphosphino)quinoline)(2,6-dimethyl-N-(4-methylpent-3-enylidene)benzenamine) (complex 1Bd).
therefore undertaken a further study in which two differently
characterized isocyanides react with some palladium phosphi-
noquinoline allyl complexes. Taking advantage of previous
findings,7e,v,12 we have chosen the palladium substrates on the
basis of the hapticity of the allyl group and the governing
difference in the electronic and steric characteristics of the
inserting isocyanides. The allyl complexes, the isocyanides
employed, and the ensuing insertion products together with
their numbering scheme are reported in Scheme 1.
INTRODUCTION
■
Metal-mediated organic synthesis is a widely studied topic, and
in particular the insertion of unsaturated molecules across the
palladium−carbon bond probably represents one of the most
investigated fields.1,2 Unsaturated molecules such as alkynes,3
alkenes,4 allenes,5 carbon monoxide,6 and isocyanides7 were
employed as inserting moieties across the metal−carbon bond
in alkyl, aryl, and acyl palladium complexes.5−8 However, the
insertion of isocyanides across the palladium allyl bond was
comparatively less studied,7v,9 although the allyl fragment
represents an interesting theoretical challenge and might give
different attractive insertion products owing to its propensity to
adopt different hapticities. As a matter of fact, it is well known
that the allyl fragment in the presence of strong nucleophiles or
chelating spectator ligands can drop its customary η3-
coordinative mode to assume the monohapto configuration7v,10
and therefore to give nontrivial organic derivatives as a
consequence of insertion reactions.11 Recently, our group
studied the amination reaction of phosphinoquinoline allyl
complexes of palladium and found that the hapticity of the allyl
group strongly affects the reactivity of the complexes and in
part the regioselectivity of the amine attack.12 We have
RESULT AND DISCUSSION
■
Starting Complexes. The reaction in chlorinated solvents
of the dimers [Pd(μ-Cl)(η3-allyl)]2 and [Pd(μ-Cl)(η3-1,1-Me2-
allyl)]2 with two equivalents of the ligands 8-
(diphenylphosphino)quinoline (DPPQ) or 8-(diphenylphos-
phino)-2-methylquinoline (DPPQ-Me) yields the neutral
complexes 1A,B and 2A,B, respectively. The hapticity of the
allyl group is dictated by the nature of the spectator ligand since
in the presence of coordinated chloride DPPQ-Me favors η3-
Received: January 20, 2014
Published: March 27, 2014
© 2014 American Chemical Society
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(see Supporting Information: Figure S1). Finally, the allyl
carbons in the 13C NMR spectra are compatible with the η3-κ2
structure reported in Scheme 1 with the carbon trans to
phosphorus and the one trans to nitrogen resonating at ca. 80
and 50 ppm, respectively. Moreover, the 31P NMR data confirm
the κ2-coordination of the DPPQ ligand since the signal of
phosphorus resonates at ca. 35 ppm, whereas in the case of
complexes with the allyl group η3 and the DPPQ-Me ligand κ1-
coordinated via phosphorus and the chloride bound to
palladium (2A, 2B, 2C) the same signal shifts about 10 ppm
upfield of the complexes. The ensuing result, which is evidently
imposed by the nature of the allyl fragment bearing a methyl
group in position 2, is unexpected.15
Scheme 1. Starting Substrates and Complexes Obtained
from the Isocyanide Insertion Reaction
The DPPQ-Me ligand displays a reduced coordinative
capability of the nitrogen donor with respect to DPPQ due
to the distortion induced on the scaffold of the complex by the
methyl substituent, as observed elsewhere in the case of
palladium complexes bearing pyridylthioether ligands.8a,b
Therefore, the reaction of the complex [Pd(η3-C3H4Me)(μ-
Cl)]2 with DPPQ-Me yields the complex 2C. In this respect,
the 1H and 13C NMR spectra of complex 2C do not
substantially differ from those of the complexes 2A and 2B
already published.12 Moreover, in the case of the latter
compounds, an NMR investigation at variable temperature
shows that the general fluxionality observed at RT (which is
caused by nucleophilic interaction of the free chloride with the
complexes) slows down at low temperature, indicating that the
cationic κ2-η3 configuration is predominant. Complex 2C
displays similar behavior and the κ1-η3 ↔ κ2-η3 temperature-
modulated equilibrium position can be observed also in this
case (Scheme 2).
Scheme 2. Temperature-Dependent Hapticity of Complex
2C
coordination (2A, 2B), whereas the unsubstituted DPPQ
induces the monohapticity of the allyl group (1A, 1B). These
complexes were synthesized and characterized elsewhere, and
their 1H and 13C NMR spectra allowed unequivocal
identification of the hapticity of the allyl fragment, which was
definitely established by the crystal structure determination of
complex 1A in the case of the η1 derivatives.12 Interestingly, at
variance with the complexes 1A and 1B, derivative 1C displays
the 2-methylallyl group η3-coordinated with the chloride acting
as the counterion. As a matter of fact, the 1H NMR spectrum of
complex 1C recorded at 223 K (in order to minimize η3−η1−η3
fluxionality) does not differ from the spectrum of the cationic
complex 1C-ClO4, which was synthesized in mixed solvents
(CH2Cl2−MeOH) in the presence of NaClO4 acting as a
dechlorinating agent.13 In particular, the RT 1H NMR spectrum
of complex 1C displays a broad singlet at 3.67 ppm ascribable
to all the allyl protons, which at low temperature (223 K) split
into a couple of doublets traceable back to the syn and anti
protons trans to phosphorus (Hsyn = 5.02 ppm; Hanti = 4.18
ppm) and a signal ascribable to the syn and anti protons trans to
nitrogen at 3.32 ppm resonating as a broad singlet due to the
residual selective η3−η1−η3 isomerization still operative even at
223 K.12 Remarkably, the high-field position of such a singlet
rules out the possible presence of chloride in trans position (see
later). In the case of complex 1C-ClO4, owing to the absence of
chloride,14 no fluxional rearrangements are observed, and its
Characterization of the Insertion Products. All the
insertion reactions were followed by NMR technique before
any synthetic attempt was tried. The reactions were carried out
under almost stoichiometric conditions, and the ensuing stable
imino derivatives are represented in Scheme 1. Remarkably,
only the monoinsertion products were observed in our cases,
although isocyanides sometime can give polyinsertion.16 The
monoinsertion observed in our case is probably due to the
steric hindrance and the reduced nucleophilicity of the
monoinserted imino fragment, which severely hampers any
further attack of the isocyanide, which moreover is only in
slight excess with respect to the allyl complex.
Among all the possible products of the 2,6-dimethylphenyl
isocyanide (DIC) insertion, only the complexes 1Bd, 2Bd, and
1Cd were stable enough to be isolated and characterized. As a
matter of fact, DIC insertion on the complexes 1A and 2A
proceeds smoothly, taking some hours or a few minutes,
respectively, but the reaction products undergo massive
decomposition and cannot be separated pure, although they
1
RT H NMR spectrum is almost coincident with that of 1C
recorded at low temperature, apart from the splitting of the allyl
protons (syn and anti) trans to nitrogen into a couple of signals
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can be identified in solution. Conversely, all the 1-
(isocyanomethylsulfonyl)-4-methyl benzene (TOSMIC) deriv-
atives were stable compounds.
Table 1. Reaction Times Determined by Preliminary NMR
Investigations Carried out in CD2Cl2 at 298 K for the
Reaction: Complex + Isocyanide → Insertion Product
It is worth noting that the signals of the inserted isocyanides
resonate at significantly different frequencies with respect to
those of the free molecules. Thus, the H NMR spectra of the
isocyanides
1
complex
TOSMIC (min)
DIC (min)
b
DIC derivatives are characterized by the presence of up-field
shifts of the signals of the inserted isocyanide (inserted DIC,
Hc, Hd within 6.5−7 ppm, CH3 1.8−2 ppm; free DIC Hc, Hd
7.1, 7.2 ppm, CH3 2.44 ppm), whereas the TOSMIC complexes
are identified by the diastereotopicity of the CH2-SO2 protons
(see later). Moreover, in the 13C NMR spectra the peak of the
iminic functional group of the insertion products is always
observed at ca. 180 and 190 ppm in the case of DIC and
TOSMIC derivatives, respectively. As for the IR spectra, the
imine stretchings νCN are observed at ca. 1600 cm−1. No hints
of signals at ca. 2100 cm−1 are detected, so the mere
coordination of the isocyanide to palladium can be safely
ruled out.
1A
1B
1C
2A
2B
2C
35
18
240
60
60
a
<8
a
b
<8
40
a
a
<8
<8
b
a
<8
240
a
b
Reactions too fast to be recorded by NMR technique. Reactions
proceeding with decomposition of the products.
(1) In reactions between the same complex and different
isocyanides, TOSMIC is always more reactive than DIC
thanks to its higher electrophilicity and reduced steric
hindrance at carbon.
(2) In the case of neutral η1-complexes, the reactivity of the
3,3′-Me2-allyl derivative 1B is higher than that of
complex 1A owing to the enhanced nucleophilicity of
the dimethylated allyl fragment. Consequently, it is
possible to state that the hindrance of the peripheral
methyl groups probably does not interfere with the
intimate insertion mechanism.
(3) A comparison of the reactivity of neutral complexes
bearing the η3-coordinated allyl groups 2A, 2B, and 2C,
while confirming the highest reactivity of the complex
bearing the 3,3-disubstituted allyl group, highlights the
marked reduction of reaction rate of complex 2C.
Apparently, the methyl group at position 2 of the allyl
fragment heavily interferes with the inserting isocyanide.
Unfortunately, owing to the observed high rates, such a
hypothesis could not be verified in the case of the
reactions with TOSMIC.
Furthermore, the NMR spectra of the inserted complexes are
characterized by the presence of all the signals belonging to the
spectator ligands resonating at different frequencies from those
of the allyl precursors. In particular the 31P NMR spectra of the
inserted complexes display the phosphorus signal within 23 and
28 ppm.
As for the allyl fragments we have observed that the alkyl
protons CH2CN of the DIC derivatives, owing to the
deshielding induced by the iminic group, resonate as a doublet
at ca. 3 ppm, whereas in the case of the TOSMIC complexes
the CH2CN protons resonate as a couple of doublets due to
their diastereotopicity.
The CH2CN carbons are in any case observed within 43−54
ppm, and these signals appear as doublets owing to the long-
range coupling with phosphorus (JCP ≈ 10 Hz).
The olefinic protons resonate within 4.5 and 6 ppm, and the
observed multiplicity is in any case consistent with the structure
of the allyl group. The corresponding olefinic carbons appear
within 110 and 145 ppm with the central carbons resonating at
higher field. The full description of the NMR spectra of all the
new complexes is given in detail in the Experimental Section.
The diastereotopicity of the CH2CN and CH2SO2 protons in
the TOSMIC complexes is probably due to hindered rotation
about the Pd−C bond. As a matter of fact, the NOESY spectra
of the TOSMIC derivatives display an intense cross-peak
among one of the CH2SO2 protons and some aromatic protons
of the phenyl substituents on phosphorus. Such an
experimental evidence suggests that the CH2SO2C6H4-Me
fragment cis to the palladium center is sterically engaged with
the phenyl substituents on phosphorus (see Supporting
Information: Figures S2 and S3).
(4) The complex 2C is less reactive than the cationic
complex 1C. Reasonably, the positive charge on
palladium increases the electrophilicity of the precoordi-
nated isocyanide and renders nucleophilic attack of the
allyl fragment easier.
(5) Finally, the neutral complexes bearing the allyl group η1-
coordinated (1A and 1B) are less reactive than those
with the allyl group η3-coordinated (2A and 2B).
We have therefore undertaken a detailed kinetic investigation
in order to assess the intimate mechanism of the isocyanide
insertion on different allyl fragments coordinated to the
palladium center with different hapticity. We have chosen as
a spot check the reactions yielding stable products and
displaying an amenable rate under NMR conditions, and in
this respect we decided to lower the experimental temperature
to 288.15 K.
Mechanistic Investigation. In order to rationalize the
reactivity of the isocyanides across the palladium−carbon bond,
we decided to investigate in detail the mechanism of insertion
of DIC and TOSMIC across the Pd−C bond in palladium
complexes bearing the allyl groups with different hapticity. A
First of all, we have investigated the reaction of the complex
1
1B with DIC and TOSMIC isocyanides by means of H NMR
1
preliminary study was carried out by monitoring the H and
technique in CD2Cl2. The concentration profiles detected as
the integration areas of the feasible NMR signals of the starting
complex and product versus time for both the reactions carried
out under almost equimolecular conditions for the complex and
the isocyanide are described by a second-order rate law of the
type
when possible the 31P NMR spectra of solutions obtained by
mixing almost equimolecular solutions (∼1.6 × 10−2 mol
dm−3) of the complex and the isocyanide under study in
CD2Cl2 at 298 K. The ensuing results are summarized in Table
1.
From the preliminary results it was possible to deduce the
following general conclusions:
rate = −d[complex]/dt = k2[complex][isocyanide]
(1)
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1
■
Figure 1. (a) H NMR spectra in CD2Cl2 recorded at 288.15 K and (b) the corresponding best fits of the concentrations of the complexes 1B ( )
([1B]0 = 1.2 × 10 −2; [TOSMIC]0 = 1 × 10 mol L ) and 1Bt ( ) vs time for the reaction 1B + TOSMIC → 1Bt.
−2
−1
▲
1
Figure 2. H (left) and 31P{1H} NMR (right) spectra for the reaction 1C + DIC → 1Cd in CD2Cl2 recorded at 288 and 223 K, respectively. (a)
NMR spectra of the starting complex 1C. (b) NMR spectra of the starting complex 1C immediately after the addition of DIC; the signals of the
coordinated DIC in the intermediate are indicated by the arrows. (c) NMR spectra of the final product. The inserted DIC is indicated by the arrows.
Regression analysis of the concentration versus time data yields
the second-order rate constants for both the isocyanides (k2 =
0.287 0.006 in the case of TOSMIC and k2 = (3.21 0.02) ×
10−2 L mol−1 s−1 for DIC, respectively). Notably, these values
agree with the qualitative data of Table 1 and with the general
remarks reported above (see point 1).
The H NMR spectra and the best fits of the concentration
versus time data for the reaction between complex 1B and
TOSMIC are reported in Figure 1a,b.
constant value (k2 = (5.64 0.08) × 10−2 L mol−1 s−1) proves
the lower nucleophilicity and consequently the reduced
reactivity of the unsubstituted allyl fragment (see Supporting
Information, Figure S4; in Figure S5 we report the regression
analysis for the reaction of 1B with DIC under similar
experimental conditions). Notably, complex 1C behaves
differently from the η1-derivatives. As can be seen in Figure 2
1
1
the H NMR spectra of the reaction of complex 1C with DIC
In order to verify the second relevant point of the comments
raised before, we have studied the reaction between the
complex 1A and the isocyanide TOSMIC. The regression
analysis, while confirming the rate law governing the insertion
mechanism on η1-derivatives, allows the determination of the
related second-order rate constant k2. In particular, the rate
clearly show the immediate and quantitative formation of an
intermediate species that slowly rearranges to the reaction
product.
In this case, the reaction progress (Figure 3) is conveniently
interpreted as a first-order monoexponential decay of the type
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Some features related to the nature of intermediate I can be
deduced from the analysis of the NMR spectra in Figure 2b. In
particular signals due to the coordinated isocyanide are
detectable at higher field with respect to the free and at
lower field to the inserted one, respectively, and significant
shifts for the signals of the spectator ligand DPPQ are observed
rate = −d[intermediate]/dt
= d[inserted product]/dt
= k1[intermediate]
(2)
1
in both the H and 31P NMR spectra. Unfortunately, the allyl
fragment undergoes a fluxional rearrangement at any safely
attainable temperature (down to 188 K), probably triggered by
the chloride counterion, and therefore its hapticity cannot be
established.18
Furthermore, the formation of an intermediate bearing the
isocyanide coordinated to palladium is also suggested by the IR
spectrum of a CH2Cl2 solution of an almost equimolecular
mixture of 1C and DIC ([1C] ≈ [DIC] ≈ 1.8 × 10−2 mol L−1)
recorded immediately after mixing. The νCN at 2124 cm−1 of
the uncoordinated isocyanide shifts to 2181 cm−1 (see
Supporting Information, Figure S6), which represents the
typical frequency of a coordinated isocyanide in cationic
palladium complexes.7v Such a signal disappears with time with
a rate comparable with that determined by the temperature-
Figure 3. Best fit of the concentrations of the complexes 1C and 1Cd
−2
([1C]0 = 1.2 × 10 −2; [DIC] = 2.0 × 10 mol L−1) vs time for the
reaction 1C + DIC → 1Cd.
1
We think that these experimental results can be interpreted
on the basis of the general mechanism reported in Scheme 3.
The first step of this scheme involves the fast and reversible
formation of the ion-pair intermediate I bearing the η1-allyl
group cis to the isocyanide, which slowly evolves into the
reaction products.17 In the case of complexes 1A and 1B, for
which no intermediates were observed, the value of the
equilibrium constant Ke ought to be small. Thus, the reaction
rate takes the experimentally observed form
controlled H NMR experiment (see above).
Crystal Structure Determination. In order to assess
unambiguously the structure of the insertion products, we have
carried out the diffractometric determination of the solid-state
structure of complex 1Bd.
An ORTEP19 view of complex 1Bd is shown in Figure 4. The
Pd(II) exhibits square-planar coordination with Cl and P trans
to each other and an imino group trans to the nitrogen N1 of
the quinoline moiety. The compound exhibits a slight
distortion from planarity at the Pd center, with the largest
deviation from the coordination plane Pd1/P1/N1/Cl1/C22 of
0.015(2) Å for the imine C22 atom. The quinoline ligand is
rotated with respect to the Pd coordination plane by 17.52(4)°.
The Pd1−N1 bond length of 2.180(2) Å is in agreement
with Pd−N(sp2) distances in the range 2.13−2.18 Å of
complexes having similar square-planar coordination arrange-
ments.12,20−22 These bonds are relatively long compared to the
mean distance of 2.06(2) Å in [Pd(P−N)Cl2] complexes where
the nitrogen is trans to a Cl, showing that the C(sp2) carbon
determines a trans influence on N greater than the Cl atom.
The plane of the imino group (N2C22−C23) makes a
dihedral angle of 69.9(2)° with the mean Pd coordination
plane.
d[product]/dt = −d[complex]/dt = k2[complex][DIC]
(3)
where k2 = Kekins, the latter constants not being independently
accessible.
On the contrary, in the case of complex 1C the immediate
and quantitative formation of a transient species I is observed
(see Figure 2). Apparently, the Ke value is high and the
formation of the final product P proceeds smoothly via the
intramolecular insertion with a rate described by the relation-
ship
d[product]/dt = −d[I]/dt = kins[I]
(4)
which is coincident with the experimentally observed rate law
and provides the true value of the insertion rate constant.
Scheme 3. Insertion of Isocyanides on η1- or η3-Allyl Palladium Phosphoquinoline Complexes: General Mechanism
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The rate of insertion reactions of isocyanides on the
palladium allyl complexes is governed by the hapticity of the
allyl group. Thus, the monohapto allyl derivatives react
following a second-order rate law, whereas the trihapto complex
displays a first-order rate. The experimental results were
interpreted on the basis of a common mechanism involving a
pre-equilibrium reaction, in which the value of the pre-
equilibrium constant determines the observed rate law.
We have eventually determined the solid-state structure of
complex 1Bd.
EXPERIMENTAL SECTION
■
Materials. All solvents were purified by standard procedures and
distilled under argon immediately before use. 1D- and 2D-NMR
spectra were recorded using a Bruker 300 Avance spectrometer.
Chemical shifts (ppm) are given relative to TMS (1H and 13C NMR)
and 85% H3PO4 (31P NMR).
Peaks are labeled as singlet (s), doublet (d), triplet (t), quartet (q),
multiplet (m), and broad (br). The proton and carbon assignment was
1
1
1
performed by H−2D COSY, H−2D NOESY, H−13C HMQC, and
Figure 4. ORTEP view of the complex 1Bd showing thermal ellipsoids
at the 30% probability level.
HMBC experiments.
IR spectra were recorded on a Perkin-Elmer Spectrum One
spectrophotometer.
The crystal data are given in Table S1. Selected bond
distances and angles are given in Table 2.
The ligands DPPQ23 and DPPQ-Me,3 the starting complexes
[Pd(μ-Cl)(η3-C3H5)]2,24 [Pd(μ-Cl)(η3-1,1-Me2C3H3)]2, and [Pd(μ-
Cl)(η3-2-Me-C3H4)]2,16 and the derivatives 1A, 1B, 2A, and 2B12 were
prepared following literature procedures. All other chemicals were
commercial grade and were used without further purification.
Synthesis of Complex 1C. A mixture of 75.5 mg (0.192 mmol) of
the complex [Pd(μ-Cl)(η3-2-Me-C3H4)]2 and 125.2 mg (0.399 mmol)
of DPPQ dissolved in 20 mL of anhydrous CH2Cl2 was stirred under
inert atmosphere (Ar) for 20 min. Evaporation under vacuum to a
small volume and addition of diethyl ether yields 174.4 mg of the title
Table 2. Selected Bond Distances and Angles (Å and deg) of
1Bd
Distances
Pd1−N1
Pd1−P1
Pd1−Cl1
Pd1−C22
C22−N2
C22−C23
2.180(2)
2.2191(5)
2.3554(6)
1.993(2)
1.254(2)
1.516(3)
1
complex as a dark yellow solid. Yield: 89%. H NMR (300 MHz,
CD2Cl2, T = 298 K, ppm) δ: 1.91 (s, 3H, allyl−CH3), 3.67 (bs, 4H,
allyl−H), 7.47−7.79 (m, 12H, H3, H6, PPh2), 8.00 (m, 1H, H7), 8.17
(dt, 1H, 3JH,H = 8.1, 4JH,H =1.2 Hz, H5), 8.54 (dt, 1H, 3JH,H = 8.4, 4JH,H
Angles
3
4
1
1.7 Hz, H4), 9.89 (dd, 1H, JH,H = 4.9, JH,H 1.6 Hz, H2). H NMR
P1−Pd1−N1
P1−Pd1−Cl1
N1−Pd1−Cl1
C22−Pd1−Cl1
P1−Pd1−C22
N1−Pd1−C22
Pd1−C22−N2
Pd1−C22−C23
N2−C22−C23
82.62(5)
176.78(2)
94.18(5)
88.28(6)
94.93(6)
177.44(7)
118.6(1)
118.6(2)
122.4(2)
(300 MHz, CDCl3, T = 223 K, ppm) δ: 2.14 (s, 3H, CH3−allyl), 3.32
3
(bs, 2H, allyl−Hsyn, allyl Hanti trans-N), 4.18 (bd, 1H, JH,H = 9.0 Hz,
3
allyl Hanti trans-P), 5.02 (bd, 1H, JH,H = 4.8 Hz, allyl−Hsyn, trans-P),
7.47−7.60 (m, 10H, PPh2), 7.88 (t, 1H, 3JH,H = 8.1 Hz, H6), 7.99−8.07
(m, 2H, H3, H7), 8.38 (d, 1H, 3JH,H = 8.1 Hz, H5), 8.84 (d, 1H, 3JH,H
=
8.4 Hz, H4), 9.82 (d, 1H, 3JH,H = 4.7 Hz, H2). 13C{1H} NMR (CDCl3,
T = 223 K, ppm) δ: 24.8 (CH3, CH3−allyl), 50.6 (CH2, allyl−CH2
2
trans-N), 83.4 (d, CH2, JP,C = 28.8 Hz, allyl−CH2 trans-P), 124.8
3
(CH, C7), 128.7 (d, CH, JP,C = 6.4 Hz, C6), 133.6 (CH, C5), 138.6
(CH, C3), 141.1 (CH, C4), 150.7 (C, C10), 151.0 (C, C9), 160.3 (CH,
C2). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 35.5. IR
(KBr pellets): νCN 1607, 1593, 1569 cm−1. Anal. Calcd for
C25H23ClNPPd: C, 58.84; H, 4.54; N, 2.74. Found: C,58.61; H,
4.63; N, 2.97.
CONCLUSION
■
Synthesis of Complex 1C-ClO4. A mixture of 75.5 mg (0.192
mmol) of the complex [Pd(μ-Cl)(η3-2-Me-C3H4)]2 and 125.2 mg
(0.399 mmol) of DPPQ dissolved in 20 mL of anhydrous CH2Cl2 was
stirred under an inert atmosphere (Ar) for 20 m. To the resulting
yellow solution was added 52 mg (0.37 mmol) of NaClO4.H2O
dissolved in 2.5 mL of MeOH. A cloudy suspension of NaCl
immediately formed. The mixture was stirred for a further 30 m, dried
under vacuum, and redissolved in CH2Cl2 in the presence of activated
charcoal. The suspension containing NaCl and NaClO4 in excess was
filterd off on a Celite filter, and the resulting clear solution
concentrated under vacuum. Addition of diethyl ether induces the
precipitation of 91.5 mg of the title complex as a yellow solid, which
was dried under vacuum. Yield: 88%. 1H NMR (300 MHz, CDCl3, T =
223 K, ppm) δ: 2.14 (s, 3H, CH3−allyl), 2.90 (s, 1H, Hanti trans-N),
3.79 (s, 1H, Hsyn trans-N), 4.27 (d, 1H, 3JH,H = 9.5 Hz, allyl Hanti trans-
P), 5.02 (m, 1H,allyl−Hsyn, trans-P), 7.49−7.60 (m, 10H, PPh2), 7.83
We have synthesized some palladium phosphoquinoline chloro
complexes bearing unsubstituted and substituted allyl groups.
The hapticity of the allyl group is governed by an interplay of
the structural and electronic features of the allyl itself and the
spectator ligands. In this respect, the palladium derivatives of
DPPQ always display a chelate spectator ligand P−N
independently of the hapticity of the allyl fragment. Thus, the
allyl and 3,3-dimethylallyl derivatives adopt the κ2-η1
configuration, whereas the 2-Me-allyl derivative 1C prefers
the κ2-η3 arrangement with the Cl− forced out of the
coordination sphere and acting as a counterion.
Conversely, DPPQ-Me favors the formation of κ1-η3
derivatives with the quinoline nitrogen uncoordinated and the
chloride occupying the fourth coordination position.
1705
dx.doi.org/10.1021/om500057h | Organometallics 2014, 33, 1700−1709

Organometallics
Article
(t, 1H, 3JH,H = 8.1 Hz, H6), 7.96 (m, 1H, H7), 8.24 (m, 1H, H3), 8.34
IR (KBr pellets): νCN = 1602 cm−1. Anal. Calcd for C34H32ClN2PPd:
3
3
(d, 1H, JH,H = 8.1,Hz, H5), 8.64 (d, 1H, JH,H = 8.3 Hz, H4), 9.74 (d,
C, 63.66; H, 5.03; N, 4.37. Found: C, 63.77; H, 5.21; N, 4.18.
1
1H, 3JH,H = 5.0 Hz, H2). 13C{1H} NMR (CDCl3, T = 223 K, ppm) δ:
Complex 2Bd. Dark yellow solid. Yield: 78%, 20 min. H NMR
2
(300 MHz, CD2Cl2, T = 298 K, ppm) δ: 1.14 (s, 3H, CH3cis), 1.57 (s,
3H, CH3trans), 2.00 (s, 6H, Ph−CH3), 3.13 (s, 3H, CH3quinoline), 3.33 (d,
24.1(CH3, CH3−allyl), 52.5 (d, CH2, JP,C = 2.3 Hz, allyl−CH2 trans-
N), 82.0 (d, CH2, 2JP,C = 28.8 Hz, allyl−CH2 trans-P), 124.6 (CH, C7),
3
3
128.4 (d, CH, JP,C = 6.3 Hz, C6), 133.2 (CH, C5), 138.4 (CH, C3),
2H, JH,H = 6.6 Hz, CH2−CH), 5.30 (m, 1H, CHCH2), 6.92 (m,
3H, H−Phortho, H−Phmeta), 7.34−7.60 (m, 13H, H3, H6, H7, PPh2),
7.93 (d, 1H, 3JH,H = 8.1, 4JH,H = 1.3 Hz, H5), 8.15 (dd, 1H, 3JH,H = 8.4,
4JH,H = 1.5 Hz, H4). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K,
ppm) δ: 27.6. IR (KBr pellets): νCN =1650 cm−1. Anal. Calcd for
C36H36ClN2PPd: C, 64.58; H, 5.42; N, 4.18. Found: C, 64.91; H, 5.71;
N, 4.29.
140.5 (CH, C4), 150.8 (C, C10), 151.1 (C, C9), 160.8 (CH, C2).
31P{1H} NMR (300 MHz, CDCl3, T = 298 K, ppm) δ: 32.391. IR
(KBr pellets): νCN 1593, 1571 cm−1
. Anal. Calcd for
C25H23ClNO4PPd: C, 52.28; H, 4.04; N, 2.44. Found: C, 52.57; H,
4.29; N, 2.37.
Synthesis of Complex 2C. The title complex was synthesized
following the same procedure as complex 1C using DPPQ-Me as
spectator ligand. Pale yellow microcrystals. Yield: 83%. 1H NMR (300
MHz, CD2Cl2, T = 298 K, ppm) δ: 1.91 (s, 3H, allyl−CH3), 2.71 (s,
3H, CH3−quinoline), 3.50 (bs, 4H, allyl−H), 7.40−7.69 (m, 12H, H3,
H6, H7, PPh2), 8.04 (d, 1H, 3JH,H = 8.0, H5), 8.29 (dd, 1H, 3JH,H = 8.4,
4JH,H =1.7 Hz, H4). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K,
Complex 1At. Yellow solid. Yield: 84%, 35 min. In order to avoid
decomposition, the following reaction mixtures were thermally
quenched at 0 °C (ice bath) at the end of the reaction and before
reduction to a small volume. 1H NMR (300 MHz, CD2Cl2, T = 298 K,
ppm) δ: 2.47 (s, 3H, Ph−CH3), 2.96 (dd, 1H, 2JH,H = 17.0, 3JH,H =7.2
Hz, CH2−CH), 3.22 (dd, 1H, 2JH,H = 17.0, 3JH,H = 7.2 Hz, CH2−CH),
2
3
25
1
4.22 (d, 1H, JH,H = 14.9 Hz, CH2SO2), 4.61 (dm, 1H, JH,H = 17.2,
CH2CHcis), 4.86 (dm, 1H, 3JH,H = 10.1, CH2CHtrans), 5.04 (d, 1H,
2JH,H = 14.9 Hz, CH2SO2), 5.97 (m, 1H, CHCH2), 7.31 (d, 2H,
3JH,H = 7.9 Hz, H−Phortho), 7.43−7.70 (m, 14H, H−Phmeta, H3, H6,
ppm) δ: 23.5. H NMR (300 MHz, CD2Cl2, T = 213 K, ppm) δ:
1.99 (s, 3H, CH3−allyl), 2,99 (s, 3H, CH3−quinoline), 3.23 (bs, 2H,
allyl−Hsyn, allyl Hanti trans-N), 3.85 (bd, 1H, 3JH,H = 10.0 Hz, allyl Hanti
3
trans-P), 5.02 (bd, 1H, JH,H = 5.4 Hz, allyl−Hsyn, trans-P), 7.44−7.59
3
PPh2), 7.89 (m, 1H, H7), 8.15 (d, 1H, JH,H = 8.0 Hz, H5), 8.50 (dt,
(m, 10H, PPh2), 7.70−7.80 (m, 3H, H6, H3, H7), 8.22 (d, 1H, 3JH,H
=
3
4
3
4
1H, JH,H = 8.4, JH,H = 1.8 Hz, H4), 9.82 (dd, 1H, JH,H = 4.9, JH,H
=
7.0 Hz, H5), 8.54 (d, 1H, JH,H = 8.4 Hz, H4). 31P{1H} NMR (300
MHz, CD2Cl2, T = 213 K, ppm) δ: 32.08. IR (KBr pellets): νCN 1635,
1607, 1558 cm−1. Anal. Calcd for C26H25ClNPPd: C, 59.56; H, 4.81;
N, 2.67. Found: C, 59.71; H, 4.98; N, 2.51.
3
1.6 Hz, H2). 13C{1H} NMR (CDCl3, T = 243 K, ppm) δ: 21.9 (CH3,
Ph−CH3), 49.6 (d, CH2, JP,C = 10.2 Hz, CH2−CH), 77.0 (CH2,
3
CH2SO2), 115.1 (CH2, CH2CH), 129.2 (CH, CH−Ph), 129.3
(CH, CH−Ph), 132.4 (CH, C5), 135.7 (CH, CHCH2), 137.4 (CH,
C7), 139.2 (CH, C4), 144.2 (C, C−Phpara), 149.4 (C, C10), 149.7 (C,
C9), 153.1 (CH, C2), 192.8 (C, CN). 31P{1H} NMR (300 MHz,
CD2Cl2, T = 298 K, ppm) δ: 28.5. IR (KBr pellets): νCN = 1615, δSO2
= 1314, 1137, 562 cm−1. Anal. Calcd for C33H30ClN2O2PPdS: C,
57.32; H, 4.37; N, 4.05. Found: C, 57.13; H, 4.45; N, 4.23.
Synthesis of Complex 1Bd. A mixture of 60 mg (0.114 mmol) of
complex 1B and 16.5 mg (0.126 mmol) of 2,6-dimethyl phenyl
isocyanide dissolved in 6 mL of anhydrous CH2Cl2 was stirred under
inert atmosphere (Ar) for ca. 60 min. Evaporation of the dark yellow
solution under vacuum to a small volume and addition of diethyl ether
yields 51.5 mg of the title complex as a dark yellow solid. Yield: 70%.
1H NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 1.16 (s, 3H,
CH3 cis), 1.42 (s, 3H, CH3 trans), 1.87 (s, 6H, Ph−CH3), 2.92 (d, 2H,
3JH,H = 7.1 Hz, CH2−CH), 5.30 (m, 1H, CHCH2), 6.73 (t, 1H,
1
Complex 1Bt. Yellow solid. Yield: 90%, 20 min. H NMR (300
MHz, CD2Cl2, T = 298 K, ppm) δ: 1.30 (s, 3H, CH3cis), 1.65 (s, 3H,
2
3
CH3trans), 2.47 (s, 3H, Ph−CH3), 2.92 (dd, 1H, JH,H = 18.1, JH,H
=
2
3
6.9 Hz, CH2−CH), 3.22 (dd, 1H, JH,H = 18.1, JH,H = 6.9 Hz, CH2−
3
3JH,H = 7.8 Hz, H−Phortho), 6.86 (d, 2H, JH,H = 7.8 Hz, H−Phmeta),
CH), 4.16 (d, 1H, 2JH,H = 14.8 Hz, CH2SO2), 5.04 (d, 1H, 2JH,H = 14.8
7.43−7.56 (m, 6H, PPh2), 7.67−7.75 (m, 2H, H3, H6), 7.83−7.90 (m,
3
Hz, CH2SO2), 5.36 (m, 1H, CHCH2), 7.31 (d, 2H, JH,H = 7.8 Hz,
3
4
5H, H7, PPh2), 8.10 (dt, 1H, JH,H = 8.1, JH,H =1.3 Hz, H5), 8.46 (dt,
H−Phortho), 7.43−7.67 (m, 14H, H−Phmeta, H3, H6, PPh2), 7.84 (m,
1H, 3JH,H = 8.3, JH,H = 1.7 Hz, H4), 9.99 (dd, 1H, 3JH,H = 4.9, JH,H
=
4
4
1H, H7), 8.15 (d, 1H, JH,H = 8.0 Hz, H5), 8.50 (dt, 1H, JH,H = 8.3,
3
3
1.6 Hz, H2). 13C{1H} NMR (CDCl3, T = 243 K, ppm) δ: 18.0 (CH3,
CH3 cis), 19.5 (CH3, Ph−CH3), 26.4 (CH3, CH3 trans), 43.0 (d, CH2,
3JP,C = 10.7 Hz, CH2−CH), 119.3 (CH, CHCH2), 122.0 (CH,
CH−Phpara), 126.8 (C, C−Phortho), 127.8 (CH, CH−Phmeta), 131.8
(CH, C5), 132.7 (C, C(CH3)2, 136.8 (CH, C7), 139.1 (CH, C4), 149.9
(C, C10), 150.2 (C, C9), 150.3 (C, C−Phipso), 154.0 (CH, C2), 181.4
(C, CN). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ:
23.3. IR (KBr pellets): νCN = 1605 cm−1. Anal. Calcd for
C35H34ClN2PPd: C, 64.13; H, 5.23; N, 4.27. Found: C, 64.49; H,
5.04; N, 4.52.
3
4
4JH,H = 1.7 Hz, H4), 9.83 (dd, 1H, JH,H = 4.8, JH,H = 1.6 Hz, H2).
13C{1H} NMR (CDCl3, T = 243 K, ppm) δ: 18.0 (CH3, CH3 cis), 21.9
(CH3, Ph−CH3), 25.8 (CH3, CH3 trans), 44.5 (d, CH2, 3JP,C = 10.9 Hz,
CH2−CH), 76.7 (CH2, CH2SO2), 120.9 (CH, CHCH2), 129.1
(CH, CH−Ph), 129.4 (CH, CH−Ph), 131.5 (C, C(CH3)2), 132.3
(CH, C5), 137.5 (CH, C7), 139.1 (CH, C4), 144.1 (C, C−Phpara),
149.4 (C, C10), 149.7 (C, C9), 153.1 (CH, C2), 193.1 (C, CN).
31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 28.1. IR (KBr
pellets): νCN = 1620, δSO2 = 1315, 1152, 1134, 570 cm−1. Anal. Calcd
for C35H34ClN2O2PPdS: C, 58.42; H, 4.76; N, 3.89. Found: C, 58.73;
H, 4.57; N, 3.91.
The following complexes were synthesized by a similar procedure
using the appropriate allyl complexes and isocyanides. The color of the
ensuing insertion products, the yield, the reaction time previously
determined by NMR experiments, and the spectrometric data are
indicated in sequence.
Complex 1Ct. Yellow solid. Yield: 84%, 15 min. In order to avoid
decomposition, the following complexes were obtained by reduction
under vacuum of the volume of the reaction mixtures immediately
after the predetermined reaction time. 1H NMR (300 MHz, CD2Cl2, T
= 298 K, ppm) δ: 1.51 (s, 3H, C−CH3), 2.45 (s, 3H, Ph−CH3), 2.91
(d, 1H, 2JH,H = 16.8 Hz, CH2−C), 3.27 (d, 1H, 2JH,H = 16.8 Hz, CH2−
C), 4.17 (d, 1H, 2JH,H = 14.8 Hz, CH2SO2), 4.39 (m, 1H, CH2Ccis),
1
Complex 1Cd. Dark yellow solid. Yield: 81%, 90 min. H NMR
(300 MHz, CD2Cl2, T = 298 K, ppm) δ: 1.70 (s, 3H, C−CH3), 2.95
(s, 6H, Ph−CH3), 3.03 (s, 1H, CH2−C), 4.37 (m, 1H, CH2Ccis),
4.55 (m, 1H, CH2Ctrans), 6.78 (m, H−Phortho), 6.85 (m, 2H, H−
Phmeta) 7.39−7.56 (m, 6H, PPh2), 7.64−7.72 (m, 2H, H3, H6), 7.76−
7.89 (m, 5H, H7, PPh2) 8.07 (dt, 1H, 3JH,H = 8.1, 4JH,H = 1.2 Hz, H5),
8.42 (dt, 1H, 3JH,H = 8.3, 4JH,H = 1.7 Hz, H4), 9.98 (dd, 1H, 3JH,H = 4.9,
4JH,H = 1.6 Hz, H2). 13C{1H} NMR (CDCl3, T = 243 K, ppm) δ: 19.5
(CH3, Ph−CH3), 24.1 (CH3, CH3−C), 51.3 (bs, CH2, CH2−C),
113.7 (CH2, CH2C), 123.1 (CH, CH−Phpara), 127.6 (C, C−
Phortho), 131.4 (CH, C5), 135.9 (CH, C7), 138.6 (CH, C4), 142.5 (C,
CCH2), 149.0 (C, C10), 149.3 (C, C9), 153.7 (CH, C2), 178.9. (C,
CN). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 26.2.
2
4.66 (m, 1H, CH2Ctrans), 5.09 (d, 1H, JH,H = 14.8 Hz, CH2SO2),
3
7.29 (d, 2H, JH,H = 8.0 Hz, H−Phortho), 7.43−7.80 (m, 14H, H−
Phmeta, H3, H6, PPh2), 7.89 (m, 1H, H7), 8.15 (dt, 1H, 3JH,H = 8.1, 4JH,H
= 1.3 Hz, H5), 8.50 (dt, 1H, 3JH,H = 8.3, 4JH,H = 1.7 Hz, H4), 9.84 (dd,
3
4
1H, JH,H = 4.9, JH,H = 1.6 Hz, H2). 13C{1H} NMR (CDCl3, T = 243
K, ppm) δ: 21.9 (CH3, Ph−CH3), 22.6 (CH3, CH3−C), 53.8 (d, CH2,
3JP,C = 10.7 Hz, CH2−C), 76.6 (CH2, CH2SO2), 112.9 (CH2; CH2
C), 129.2 (CH, CH−Ph), 129.3 (CH, CH−Ph), 132.3 (CH, C5),
137.4 (CH, C7), 139.2 (CH, C4), 143.5 (C, CCH2), 144.1 (C, C−
Phpara), 149.4 (C, C10), 149.7 (C, C9), 153.1 (CH, C2), 192.0 (C, C
1706
dx.doi.org/10.1021/om500057h | Organometallics 2014, 33, 1700−1709

Organometallics
Article
N). 31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 28.3. IR
(KBr pellets): νCN = 1628, δSO2 = 1310, 1159, 1139, 564 cm−1. Anal.
Calcd for C34H32ClN2O2PPdS: C, 57.88; H, 4.57; N, 3.97. Found: C,
58.07; H, 4.65; N, 4.12.
determination of the suitable substrates, isocyanides, and reagent
concentrations.
The formation of intermediate I was observed in an IR experiment
in which a concentrated solution of DIC was added by means of a
micropipet to a solution of complex 1C in CH2Cl2. The IR spectrum
between 2260 and 2000 cm−1 was recorded immediately after mixing
in a liquid cell with NaCl windows (d = 0.5 mm).
1
Complex 2At. Yellow solid. Yield: 77%, 15 min. H NMR (300
MHz, CD2Cl2, T = 298 K, ppm) δ: 2.46 (s, 3H, Ph−CH3), 2.73 (dd,
1H, 2JH,H = 17.2, 3JH,H = 6.3 Hz, CH2−CH), 3.21 (dd, 1H, 2JH,H = 17.2,
3JH,H = 6.3 Hz, CH2−CH), 3.28 (s, 3H, CH3quinoline), 4.57 (dm, 1H,
3JH,H = 17.2, CH2CHcis), 4.79 (dm, 1H, 3JH,H = 10.1, CH2CHtrans),
Computational Details. DFT calculations were performed with
15a,b
the DMol3
program; geometries of the compounds were
optimized at the DFT PBE15c level using the double numerical
polarized basis set (DNP).15d Relativistic effects of core electrons were
computed using DFT semi-core pseudopotentials;15e the conductor-
like screening model15f,g (COSMO) was used to simulate a solvent
environment for the calculation.
2
2
4.85 (d, 1H, JH,H = 14.8 Hz, CH2SO2), 5.14 (d, 1H, JH,H = 14.8 Hz,
CH2SO2), 5.74 (m, 1H, CHCH2), 7.28 (d, 2H, 3JH,H = 7.9 Hz, H−
Phortho), 7.45−7.74 (m, 14H, H−Phmeta, H3, H6, PPh2), 7.88 (m, 1H,
H7), 8.02 (d, 1H, 3JH,H = 8.0 Hz, H5), 8.24 (dd, 1H, 3JH,H = 8.5, 4JH,H
=
1.6 Hz, H4). 13C{1H} NMR (CDCl3, T = 243 K, ppm) δ: 21.9 (CH3,
The mathematical treatment of the experimental kinetic data was
carried out in Origin or Scientist environments.
3
Ph−CH3), 29,0 (CH3, CH3quinoline) 48.8 (d, CH2, JP,C = 10.6 Hz,
CH2−CH), 77.2 (CH2, CH2SO2), 114.8 (CH2, CH2CH), 129.1
(CH, CH−Ph), 129.4 (CH, CH−Ph), 131.9 (CH, C5), 135.9 (CH,
CHCH2), 138.3 (CH, C7), 138.3 (CH, C4), 144.2 (C, C−Phpara),
149.9 (C, C10), 150.1 (C, C9), 166.3 (C, C2), 189.7 (C, CN).
31P{1H} NMR (300 MHz, CD2Cl2, T = 298 K, ppm) δ: 28.2. IR (KBr
pellets): νCN = 1633, δSO2 = 1312, 1156, 1136, 557 cm−1. Anal. Calcd
for C34H32ClN2O2PPdS: C, 57.88; H, 4.57; N, 3.97. Found: C, 57.71;
H, 4.72; N, 3.72.
Crystal Structure Determination. The crystal data of compound
1Bd were collected at room temperature using a Nonius Kappa CCD
diffractometer with graphite-monochromated Mo Kα radiation. The
data sets were integrated with the Denzo-SMN package26 and
corrected for Lorentz, polarization, and absorption effects (SOR-
TAV).27 The structure was solved by direct methods using the
SIR9728 system of programs and refined using full-matrix least-squares
with all non-hydrogen atoms anisotropically and hydrogens included
on calculated positions, riding on their carrier atoms.
1
Complex 2Bt. Yellow solid. Yield: 91%, 50 min. H NMR (300
All calculations were performed using SHELXL-9729 and PARST30
implemented in the WINGX31 system of programs (CCDC 982379).
MHz, CD2Cl2, T = 298 K, ppm) δ: 1.31 (s, 3H, CH3cis),1.61 (s, 3H,
2
3
CH3trans), 2.46 (s, 3H, Ph−CH3), 2.76 (dd, 1H, JH,H = 17.5, JH,H
=
−
2
3
7.1 Hz, CH2−CH), 3.21 (dd, 1H, JH,H = 17.5, JH,H = 7.1 Hz, CH2
CH), 3.27 (s, 3H, CH3quinoline) 4.78 (d, 1H, 2JH,H = 14.6 Hz, CH2SO2),
5.15 (d, 1H, 2JH,H = 14.6 Hz, CH2SO2), 5.15 (m, 1H, CHCH2), 7.29
(d, 2H, 3JH,H = 7.9 Hz, H−Phortho), 7.45−7.75 (m, 14H, H−Phmeta, H3,
ASSOCIATED CONTENT
* Supporting Information
■
S
H6, PPh2), 7.83 (m, 1H, H7), 8.01 (d, 1H, JH,H = 8.0 Hz, H5), 8.23
3
Further details of the structure determination, final coordinates,
bond distances and bond angles for 1Bd, NMR and IR spectra,
and concentration vs time profiles. This material is available
free of charge via the Internet at http://pubs.acs.org.
(dd, 1H, 3JH,H = 8.4, 4JH,H = 1.7 Hz, H4). 13C{1H} NMR (CDCl3, T =
246 K, ppm) δ: 18.1 (CH3, CH3cis), 21.9 (CH3, Ph−CH3), 25.7 (CH3,
CH3trans), 29.0 (CH3, CH3quinoline), 43.9 (d, CH2, 3JP,C = 11.7 Hz, CH2−
CH), 76.8 (CH2, CH2SO2), 120.9 (CH; CHCH2), 129.1 (CH,
CH−Ph), 129.4 (CH, CH−Ph), 131.5 (CH, C5), 132.4 (C, C(CH3)2),
134.9 (CH, C7), 138.3 (CH, C4), 144.2 (C, C−Phpara), 149.8 (C, C10),
150.1 (C, C9), 166.2 (C, C2), 190.2 (C, CN). 31P{1H} NMR (300
MHz, CD2Cl2, T = 298 K, ppm) δ: 27.6. IR (KBr pellets): νCN = 1639,
δ SO2 = 1313, 1134, 558 cm−1. Anal. Calcd for C36H36ClN2O2PPdS: C,
58.94; H, 4.95; N, 3.82. Found: C, 59.14; H, 5.07; N, 3.56.
AUTHOR INFORMATION
Corresponding Author
*E-mail: cano@unive.it.
■
Notes
The authors declare no competing financial interest.
1
Complex 2Ct. Yellow solid. Yield: 85%, 15 min. H NMR (300
MHz, CD2Cl2, T = 298 K, ppm) δ: 1.37 (s, 3H, C−CH3), 2.45 (s, 3H,
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