A new cyclometalation motif: Synthesis, characterization, structures, and reactivity of pallada-and platinacycles with a bidentate {C(sp2, cyrhetrene), N} - Ligand

Article abstract of DOI:10.1021/om200310r

The synthesis, characterization, X-ray crystal structure, and study of the reactivity of the novel cyretrenyl ligand [{(μ⁵-C ₅H₄-2-C₅H₄N) }Re(CO) ₃ (1) with Pd(OAc) ₂ or [MCl₂(DMSO) ₂] (M = Pd, Pt) are reported. These studies have allowed us to obtain the bis-μ-ligand cyclopalladated complexes [Pd{[k₂-C, N-(μ⁵-C ₅H₃) -2(C₅H₄N)]Re(CO) ₃) }(μ-X)]₂ (X = OAc (2a), Cl (4a)) and monomeric pallada-and platinacycles of the general formula [M{[k₂-C, N-(μ⁵- C₅H₃) -2(C₅H₄N)]Re-(CO) ₃}(X) (L)] (M = Pd, L = PPh3, X = OAc (3a), Cl (5a) ; M = Pd, L = DMSO, X = Cl (6a) ; M = Pt, X = Cl, L = PPh₃ (5b), DMSO (6b)), where compound 1 acts as a {C(sp², cyrhetrene), N} ^- bidentate ligand. All complexes were characterized by elemental analyses, infrared spectroscopy, and one-and twodimensional NMR. The X-ray crystal structures of 5a 3 _1/2CH₂Cl₂, 5b, 6a 3CH₂Cl ₂, and 6b confirm (a) the existence of the five-membered metallacycle, (b) the {C(sp², cyrhetrene), N} ^- mode of binding of the metallo ligand 1, and (c) the cis arrangement between the metalated carbon and the neutral L ligand s (PPh₃ or DMSO) in these products. A comparative study of the structures, spectroscopic properties, and reactivities of the new cyclometalated compounds and those of their analogues with a bidentate {C(sp², ferrocene), N} ^- ligand is also reported.

Full text of DOI:10.1021/om200310r

ARTICLE
pubs.acs.org/Organometallics
A New Cyclometalation Motif: Synthesis, Characterization, Structures,
and Reactivity of Pallada- and Platinacycles with a Bidentate
{C(sp2,cyrhetrene),N}ꢀ Ligand
Teresa Cautivo,† Hugo Klahn,*,† Fernando Godoy,‡ Concepciꢀon Lꢀopez,*,§ Mercꢁe Font-Bardía,||,^
Teresa Calvet,^ Enrique Gutierrez-Puebla,# and Angeles Monge#
†Instituto de Química, Pontificia, Universidad Catꢀolica de Valparaíso, Casilla 4059, Valparaíso, Chile
‡Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40,
Santiago, Chile
§Departament de Quimica Inorgꢁanica, Facultat de Química, Universitat de Barcelona, Martí Franquꢁes 1-11, 08028 Barcelona, Spain
Unitat de Difracciꢀo de Raigs-X, Centre Científic i Tecnolꢁogic de la Universitat de Barcelona, Universitat de Barcelona, Solꢀe i Sabaris 1-3,
08028 Barcelona, Spain
^Departament de Crystal lografia, Mineralogia i Dipꢁosits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquꢁes s/n,
3
08028 Barcelona, Spain
#Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Sor Juana Inꢀes de la Cruz 3,
28049 Madrid, Spain
S Supporting Information
b
ABSTRACT: The synthesis, characterization, X-ray crystal structure, and study of the reactivity of the
novel cyretrenyl ligand [{(η5-C5H4-2-C5H4N)}Re(CO)3 (1) with Pd(OAc)2 or [MCl2(DMSO)2]
(M = Pd, Pt) are reported. These studies have allowed us to obtain the bis-μ-ligand cyclopalladated
complexes [Pd{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re(CO)3)}(μ-X)]2 (X = OAc (2a), Cl (4a)) and
monomeric pallada- and platinacycles of the general formula [M{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re-
(CO)3}(X)(L)] (M = Pd, L = PPh3, X = OAc (3a), Cl (5a); M = Pd, L = DMSO, X = Cl (6a); M = Pt,
X = Cl, L = PPh3 (5b), DMSO (6b)), where compound 1 acts as a {C(sp2,cyrhetrene),N}ꢀ bidentate
ligand. All complexes were characterized by elemental analyses, infrared spectroscopy, and one- and two-
1
dimensional NMR. The X-ray crystal structures of 5a /2CH2Cl2, 5b, 6a CH2Cl2, and 6b confirm
3
3
(a) the existence of the five-membered metallacycle, (b) the {C(sp2,cyrhetrene),N}ꢀ mode of binding of
the metallo ligand 1, and (c) the cis arrangement between the metalated carbon and the neutral L ligands (PPh3 or DMSO) in these
products. A comparative study of the structures, spectroscopic properties, and reactivities of the new cyclometalated compounds and
those of their analogues with a bidentate {C(sp2,ferrocene),N}ꢀ ligand is also reported.
’ INTRODUCTION
studies on cyclometalation of N-donor ferrocenyl ligands
(i.e., amines, imines, azoderivatives, oximes, oxazines, andoxazoli-
dines) have provided pallada- and platinacycles with {C(sp2,
ferrocene),N}ꢀ ligands.8b,c,11,12 Some of these products exhibit
outstanding chemical and physical properties, catalytic and/or
antitumoral activities,8b,c and interesting applications in different
fields, including their utility as precursors in organometallic
synthesis12e,13 or even in the design of molecular machines
(i.e., pH-based molecular switches).12c
Despite these facts and the prochiral nature of the cyrhetrenyl
unit in the cyclometalation process,9f,14 examples of pallada- and
platinacycles containing a bidentate {C(sp2,cyrhetrene),X}ꢀ (X =
N, P, S, O) ligand are extremely scarce.15 Only two types of
palladacycles have been described15 (Figure 1), and in both cases
the two donoratomsofthe {C(sp2,cyrhetrene),P}ꢀ unitbelongto
The synthesis of functionalized half-sandwich rhenium com-
plexes derived from [(η5-C5H5)Re(CO)3] (cyrhetrene) or [(η5-
C5H5)Re(L1)(L2)(L3)] (L1, L2, L3 = neutral monodentate
ligands) is one of area of organometallic chemistry now experi-
encing increasing development.1ꢀ5 This is mainly due to (a) their
interesting and useful photochemical properties and reactivity,1,2
(b) their utility in the syntheses of heterodi-, heterotri-, and in
general polymetallic organometallic compounds,1ꢀ3 and (c) their
potential applications in outstanding catalytic chemical processes,4
such as hydrogenation of enamines and allylic alkylations.4 More
recently, cyrhetrenylꢀhormone compounds have also been
described.5
On the other hand, cyclopalladated and cycloplatinated com-
plexes derived from N-donor ligands have attracted great interest
for a long time.6ꢀ12 Most of the articles published so far have
focused on complexes with a σ{MꢀC(sp2,aryl)} bond or to a
lesser extent a σ{MꢀC(sp3)} bond.6ꢀ10 More recently, parallel
Received: April 11, 2011
Published: October 04, 2011
r
2011 American Chemical Society
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two different ligands of the rhenium complex. Furthermore, rela-
ted platinum(II) complexes still remain unknown.
which are characteristic of the terminal CO ligands of related
rhenium complexes.16
In view of these findings and due to our present interest in (a)
cyrhetrene derivatives3,16 and (b) pallada- and platinacycles with
bi- or terdentate ligands ({C(sp2,ferrocene,N)}ꢀ and {C(sp2,
ferrocene),N,X}ꢀ, respectively),12,13c,17 we decided to prepare
the novel cyrhetrene derivatives [(η5-C5H4R)Re(CO)3] with R
groups having an additional heteroatom (such as N) with good
donor ability and the proper orientation so as to allow the forma-
tion of metallacycles with {C(sp2,cyrhetrene),N}ꢀ ligands.
Here, we report our first contribution in this field and in par-
ticular (a) the syntheses and characterization of the new cyrhe-
trene derivative [{(η5-C5H4)-2-(C5H4N)}Re(CO)3] (1), bear-
ing a pyridyl group, (b) a new class of pallada- and platinacycles in
which 1 behaves as a {C(sp2,cyrhetrene),N}ꢀ ligand, and (c) a
comparative study of the properties of these new metallacycles
and those of their analogues with a {C(sp2,ferrocene),N}ꢀ
ligand.
The X-ray crystal structure of 1 confirmed the existence of
molecules of [{(η5-C5H4)-2(C5H4N)}Re(CO)3] (Figure 2)
with the expected three-legged piano-stool structure and the pre-
sence of a pyridyl unit attached to the C5H4 ring. Average values
of the ReꢀCO (1.908(6) Å) and CꢀO (1.147(2) Å) bond
lengths and the Reꢀcentroid distance (1.961(6) Å) are similar
to those reported for [{(η5-C5H4)CH2NH(C6H4-4-OCH3)}-
Re(CO)3] (1.904 Å).16a
The C5H4N ring is planar and forms an angle of 9.6ꢀ with the
(C5H4) cycle; its bond lengths and angles agree with those
reported for complexes containing a 2-substituted pyridyl group.19
In the crystal, two proximal molecules of 1 are connected by
two weak intermolecular N H interactions (the distance
3 3 3
N
H(2) is 2.739 Å), giving dimers. The assembly of
3 3 3
these units through CꢀH
network.20,23
O contacts20ꢀ22 and CꢀH
π
3 3 3
3 3 3
intermolecular interactions20,23 results in a three-dimensional
Compound 1 was also characterized in solution by NMR
experiments. The assignment of all signals detected in the 1H and
13C{1H} NMR spectra was achieved with the aid of two-
’ RESULTS AND DISCUSSION
The Ligand {(η5-C5H4)-2(C5H4N)}Re(CO)3 (1). The prepara-
tion of this product was carried out in one pot, following a
strategy similar to that reported for di-, tri-, and tetraferrocene
arenes.18 The method consisted of the sequence of reactions
AꢀC depicted in Scheme 1. In the first step, cyrhetrene was
easily converted into its lithium derivative by treatment with
n-butyllithium (Scheme 1, step A). The subsequent reaction with
ZnCl2 produced the Zn(II) derivative (Scheme 1, step B), and
finally a cross-coupling reaction of the product formed with
2-bromopyridine in the presence of catalytic amounts of [PdCl2-
(PPh3)2] gave, after workup, compound 1 in fairly good yield
(88%) (Scheme 1, step C).
1
13
dimensional {1Hꢀ H} NOESY, {1Hꢀ C} HSQC and HMBC
1
experiments. The H NMR spectrum of 1 in CDCl3 at 298 K
exhibited (a) the typical pattern of monosubstituted cyrhetrene
derivatives16 and (b) a group of four signals due to the pyridyl
Elemental analysis of 1 agreed with the proposed formula, and
its ESI+ mass spectrum showed a peak at m/z 414, which is con-
sistent with the value expected for the cation {[M] + H}+. The IR
spectrum exhibited two intense bands at 2023 and 1929 cmꢀ1
,
Figure 2. ORTEP diagram of [{(η5-C5H4)-2(C5H4N)}Re(CO)3] (1).
Hydrogen atoms have been omitted for clarity. Selected bond lengths
(in Å) and bond angles (in deg): Re(1)ꢀG* , 1.969; C(1)ꢀC(9),
1.453(8); C(2)ꢀC(1), 1.422(7); C(2)ꢀC(1)ꢀC(9), 125.7(5); C(5)ꢀ
C(1)ꢀC(9), 128.0(5); N(1)ꢀC(9)ꢀC(1), 116.3(5); C(3)ꢀC(2)ꢀ
C(1), 109.3(5); C(2)ꢀC(1)ꢀC(5), 105.9(5).
Figure 1. Mono- and dinuclear palladacycles derived from half-sand-
wich rhenium complexes described previously (X = Cl, Br, I and
L = neutral ligand such as PR3).15
Scheme 1a
a Legend: (i) in THF, n-butyllithium at ꢀ78 ꢀC for 1.5 h; (ii) ZnCl2 for 1.5 h; (iii) [PdCl2(PPh3)2] and 2-bromopyridine for 1.5 h.
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moiety in the same region as those reported by Butler et al.24 for
the ferrocene analogue.
105.3) corresponds to the ipso carbon (C1) of the C5H4 ring,
(b) a singlet at δ ∼194 (due to the CO ligands), and (c) a group
of resonances between 115 and 155 ppm assigned to the carbon-
13 nuclei (C9ꢀC13) of the 2-substituted pyridyl group.
Study of the Reactivity of 1 with Palladium(II) Salts or
Complexes. In a first attempt to evaluate the binding ability of
compound 1 toward palladium(II) and to elucidate if the activa-
tion of the σ{C(sp2,cyrhetrene)ꢀH} bond could be induced by
palladium(II) salts or complexes, we decided to use one of the
most common procedures described for the cyclopalladation of
N-donor ligands.6a,25 This method consists of the reaction be-
tween the ligand and Pd(OAc)2 in acetic acid. Treatment of 1
with an equimolar amount of Pd(OAc)2 in refluxing glacial acetic
acid for 24 h gave, after workup, a brown solid (hereafter referred
to as 2a) (Scheme 2, step A).
The 13C{1H} NMR spectrum of 1 showed (a) three signals in
the range 80.0 < δ < 110.0 ppm, the least intense of which (at δ
Scheme 2a
Elemental analyses of 2a agreed with those expected for the
cyclopalladated complex [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]-
Re(CO)3}(μ-OAc)]2. In the IR spectrum of 2a, the separation
between the bands due to the asymmetric and symmetric
stretchings of the carboxylato moiety (at 1563 and 1415 cmꢀ1),26
suggested, according to the bibliography,25,26 that the OAcꢀ
groups behaved as a O,O0 bridging ligands. All these findings, as
well as the ESI+ mass spectrum of 2a, agreed with data expected
for [Pd{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re(CO)3}(μ-OAc)]2,
in which 1 adopted a {C(sp2,cyrhetrene),N}ꢀ mode of binding.
To the best of our knowledge, palladacycles with this type of
bidentate ligand have not been described yet.
The 1H NMR spectra of 2a in acetone-d6 at 298 K showed two
sets of superimposed signals (Figure 3), thus suggesting the
coexistence of two isomeric species (2aI and 2aII) in solution.
Variable-temperature NMR experiments revealed that the rela-
tive abundance of 2aI and 2aII did not change substantially
on cooling (molar ratios 2aI:2aII = 2.50 (at 298 K) and 2.56
(at 188 K)).
a Legend: (i) Pd(OAc)2 in HOAc, reflux for 24 h; (ii) PPh3 in CDCl3 for
3 min; (iii) NaCl in CH2Cl2/H2O for 12 h; (iv) PPh3 in benzene for
12h; (v) [MCl2(DMSO)2] (M=Pd(II), Pt(II)), intoluene, reflux for 12 h.
Figure 3. 1H NMR spectrum (500 MHz) of [Pd{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re(CO)3}(μ-OAc)]2 (2a) in acetone-d6 at 298 K, showing the two
sets of superimposed signals ascribed to the two isomers 2a1 and 2aII, together with an expansion of the region 6.8 < δ < 8.3 ppm. Labeling of the peaks
refers to the numbers assigned to the protons in Scheme 2, and the labels in italics correspond to the minor isomer present in solution (2aII).
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It is well-known that dimeric cyclopalladated complexes with
bridging OAcꢀ groups may exhibit different isomeric forms
depending on the relative arrangement of the halves of the mole-
cule (cis or trans).25ꢀ27 Furthermore, the activation of one of the
σ{C(sp2,cyrhetrene)ꢀH} bonds on the ortho sites of 1 induces
planar chirality.9f,14
When the crystal used for the X-ray studies was dissolved in
acetone-d6, its 1H NMR spectrum was identical with that of the
crude product 2a, indicating the presence of 2aI and 2aII in
solution. It is well-known that the planar chirality of enantio- or
diastereomerically pure complexes with {C(sp2,ferrocene),N}ꢀ
ligands and 1,2-disubstituted η5-C5H3 rings remains in solu-
tion.17h,i,29,30 Thus, the formation of 2aII upon dissolution of the
single crystal should be related to other factors. Previous studies
on related palladacycles have demonstrated that the coexistence
of isomers in solution is generally due to a trans / cis iso-
merization of the dinuclear products.25,27
1
The {1Hꢀ H} NOESY spectrum of 2a revealed that 2aI and
2aII (a) adopted an open-book type structure (Chart 1) and (b)
differed in the relative disposition of the two {C(sp2,cyrhetrene,
N)}ꢀ units (trans in 2aI and cis in 2aII). However, no evidence of
the interconversion 2aI / 2aII was detected.
Unfortunately attempts to separate 2aI and 2aII failed and only
a poor-quality crystal was isolated. Despite this, X-ray diffraction
studies28 (Figure 4) confirmed the trans arrangement of the
halves of the molecule and the open-book-like structure of the
product. This is the most common arrangement of ligands found
in palladacycles of the type [Pd(C,N)(μ-OAc)]2.19,27
Treatment of 2a with PPh3 (in the molar ratio PPh3:2a = 2)
produced [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(OAc)-
(PPh3)] (3a) (Scheme 2, step B). Its 31P{1H} NMR showed
a singlet at δ 34.7. This chemical shift is indicative of a cis
arrangement between the phosphine and the metalated carbon
atom (C2), in good agreement with the so-called transphobia
effect.31
When a CH2Cl2 solution of 2a was treated with an excess of
NaCl (in H2O), a brown solid formed. It was identified as the
di-μ-chloro derivative [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re-
(CO)3}(μ-Cl)]2 (4a) (Scheme 2, step C). Compound 4a is air-
stable, but it is practically insoluble in the common solvents used
for NMR studies. This is the typical behavior of most pallada-
cycles of general formula [Pd{(k2-(C,N-ligand)}(μ-Cl)]2, and
commonly their NMR spectra are registered in the presence of
deuteriated pyridine (py-d5).25f,32
Chart 1
Addition of a slight excess of py-d5 to a suspension of 4a in
1
CDCl3 at 298 K produced a pale yellow solution. Its H and
31C{1H} NMR spectra suggested the presence of [Pd{[k2-C,
N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}Cl(py-d5)], which arises
from the cleavage of the central “Pd(μ-Cl)2Pd” ring and the
Figure 4. Molecular structure of the trans isomer (2aI) of [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(μ-OAc)]2 (2a).
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Figure 5. ORTEP diagram of [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]-
Re(CO)3}Cl(PPh3)] 1/2CH2Cl2 (5a 1/2CH2Cl2). The solvate mole-
3
3
cule and hydrogen atoms have been omitted for clarity. Selected bond
ꢀ
lengths (in Å) and angles (in deg): Pd(1)ꢀC(2), 1.992(5); Pd(1)ꢀ
N(1), 2.131(4); Pd(1)ꢀP(1),2.254(13); Pd(1)ꢀCl(1), 2.371(13); C-
(1)ꢀC(9), 1.444(7); N(1)ꢀPdꢀCl(1), 91,61(11); C(2)ꢀPd(1)ꢀN-
(1), 81,59(17); C(2)ꢀPd(1)ꢀP(1), 97.84(13); Cl(1)ꢀPd(1)ꢀP(1),
88.97(5); C(2)ꢀC(1)ꢀC(9) 119.8(4); C(5)ꢀC(1)ꢀC(9), 131.0(5);
N(1)ꢀC(9)ꢀC(1), 113.1(4).
Figure 6. ORTEP diagram of [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]-
Re(CO)3}Cl(DMSO)] (6a). Hydrogen atoms have been omitted for
ꢀ
clarity. Selected bond lengths (in Å) and angles (in deg): PdꢀC(2),
1.979(3); PdꢀN, 2.091(3); PdꢀS, 2.2283(12); PdꢀCl, 2.3964(13);
C(1)ꢀC(9), 1.455(5); C(2)ꢀPdꢀN, 80.93(14); NꢀPdꢀCl, 95.21(10);
C(2)ꢀPdꢀS, 94.63(11); ClꢀPdꢀS, 90.12(5); C(1)ꢀC(2)ꢀC(3),
107.0(7); C(2)ꢀC(1)ꢀC(9), 118.3(3); C(1)ꢀC(9)ꢀN, 112.0(5).
incorporation of the py-d5 ligand in a cis arrangement with regard
to the metalated carbon.
Treatment of a suspension of 4a in benzene with PPh3 (in the
molar ratio phosphine:4a = 2; Scheme 2, step D) produced, after
recrystallization, [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}-
and NaOAc 3H2O in refluxing toluene for 12 h (Scheme 2,
3
step E). Characterization data of the yellowish crystalline solid
isolated agreed with those expected for [Pd{[k2-C,N-(η5-C5H3)-
2-(C5H4N)]Re(CO)3}Cl(DMSO) CH2Cl2] (6a CH2Cl2). In
1
1
Cl(PPh3)] /2CH2Cl2 (5a /2CH2Cl2). Characterization data
3
3
(see the Experimental Section) agreed with the proposed for-
mula, and its X-ray crystal structure confirmed the existence of
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}Cl(PPh3)] (5a)
and CH2Cl2 molecules in a 2:1 molar ratio. In 5a (Figure 5), the
palladium(II) is in a slightly distorted square-planar environ-
ment,33 bound to the N and the C(2) atoms of the cyrhetrenyl
moiety. This confirms (a) the {C(sp2,cyrhetrene),N}ꢀ mode of
binding of 1 in the complex and (b) the existence of a five-
membered metallacycle. This cycle is practically planar and forms
angles of 5.2 and of 3.4ꢀ with the C5H3 unit and the pyridyl ring,
respectively.
3
3
the heterodimetallic units (6a) (Figure 6) the palladium(II) is
bound to the C(2) and N atoms of 1. The difference between the
PdꢀC(2) bond lengths in 6a (1.979(11) Å) and 5a (1.992(5) Å)
does not clearly exceed 3σ, while the variation of the PdꢀN bond
length (2.091(3) Å in 6a and 2.131(4) Å in 5a) can be attributed
to the different trans influences of the neutral ligands (L = PPh3
(in 5a), DMSO (in 6a)). The sulfur atom of the DMSO occupies
the coordination site adjacent to the PdꢀC(2) bond, and a Clꢀ
ligand fullfils the coordination sphere. The PdꢀCl bond length
(2.3964(13) Å) is similar to that found in [Pd{[k2-C,N-(2,4-
Me2-C6H2)CHdNNHC(O)C6H5)}Cl(DMSO)].35
The two remaining coordination sites are occupied by a
chloride (Cl(1)), and the phosphorus of the PPh3 ligand.
Bond lengths and angles around the palladium fall in the
range expected for most palladacycles with “Pd{(C,N),Cl,P}”
cores.17f,g,19,30 The value of the C(2)ꢀPdꢀP bond angle
(97.84(13)ꢀ)} confirms the cis arrangement between the C(2)
atom and the neutral ligand, in good agreement with the
conclusions reached by NMR and the transphobia effect.31
The relative arrangement of the three rings forming the [5.5.6]
tricyclic system is similar to that of 5a (the mean plane of the
C5H3 ring forms angles of 5.2 and 7.9ꢀ with those of the metalla-
cycle and the pyridyl unit, respectively).
In the crystal state molecules of 6a are connected by weak
CꢀH O interactions20 between the O(4) and the H(15A)
3 3 3
atoms of close units. In addition to that, there are short CꢀH
3 3 3
In the crystal, there are two weak CꢀH Cl intermolecular
Cl contacts between the peripheral atoms of the CH2Cl2 and
3 3 3
interactions between the hydrogen atoms of the CH2Cl2
and the Clꢀ ligands of two different units of 5a (distance
Cl(1) H(32A) = 2.634 Å)34 and CꢀH O contacts between
units of 6a.20
1
It should be noted that since crystals of 5a /2CH2Cl2 and
6a CH2Cl2 are centrosymmetric, they contain a mixture of the
3
3 3 3
3 3 3
3
the pair of oxygen atoms O(2) and O(3) of a molecule at (x, y, z)
and two hydrogen atoms (H(11) and H(21)) of vicinal units at
(ꢀx, 2 ꢀ y, ꢀz) and (1/2 ꢀ x, 1/2 ꢀ y, 1/2 ꢀ z), respectively.
The activation of the σ{C(sp2,cyrhetrene)ꢀH} bond was also
achieved by reaction of equimolar amounts of 1, [PdCl2(DMSO)2],
two enantiomers Sp and Rp. This is consistent with the absence of
any factor inducing chirality in the reaction medium.
1H and 13C{1H} NMR data of 5a are presented in the
Experimental Section. The position of the singlet detected in
its 31P{1H} NMR spectrum (at δ 33.9) is similar to that of 3a
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Figure 7. ORTEP diagram of [Pt{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re-
(CO)3}Cl(DMSO)] (6b). Hydrogen atoms are omitted for clarity.
Figure 8. ORTEP diagram of [Pt{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re-
(CO)3}Cl(PPh3)] (5b). Hydrogen atoms are omitted for clarity. Selec-
ꢀ
Selected bond lengths (in Å) and angles (in deg): PtꢀC(2), 1.995(6);
ꢀ
ted bond lengths (in Å) and angles (in deg): PtꢀC(2), 1.969(5);
PtꢀN, 2.102(5); PtꢀS, 2.203(2); PtꢀCl(1), 2.386(2); C(1)ꢀC(9),
1.476(10); C(2)ꢀPtꢀN, 80.6(2); NꢀPtꢀCl(1), 93.91(16); C(2)ꢀ
PtꢀS, 95.01(19); Cl(1)ꢀPtꢀS, 90.40(8); 105.5(5); C(2)ꢀC(1)ꢀ
C(9), 116.6(5); C(11)ꢀC(9)ꢀN, 113.2(5).
PtꢀN, 2.127(4); PtꢀP, 2.2295(15); PtꢀCl, 2.3814(16); C(1)ꢀC(9),
1.437(7); C(2)ꢀPtꢀN, 80.48(18); NꢀPtꢀCl, 92.42(13); ClꢀPtꢀP,
86.85(6); C(2)ꢀPtꢀP, 100.20(4); C(2)ꢀC(1)ꢀC(9), 116.9(5);
C(5)ꢀC(1)ꢀC(9), 134.2(5); C(1)ꢀC(9)ꢀN, 114.7(5).
(δ 34.7). These signals are shifted upfield in comparison with
those of [Pd{C(sp2,ferrocene),N}(X)(PPh3)] complexes (X =
OAcꢀ, Clꢀ (37.0 < δ < 39.0))17f,30,36 but fall in the range reported
for palladacycles with terdentate ligands {C(sp2,ferrocene),N,E}q
(q = ꢀ1 (for E = N, S, O), ꢀ2 (for E = O)).17b,37
The crystal structures of 5b and 6b confirmed the existence of
the heterodimetallic molecules of [Pt{[k2-C,N-(η5-C5H3)-
2-(C5H4N)]Re(CO)3}Cl(L)] with L= DMSO (in 6b) or PPh3
(in 5b) (Figures 7 and 8, respectively). In compounds 6b and 5b,
the Pt(II) atom is in a slightly distorted square-planar environ-
ment38 and the distribution of ligands is identical with those of
their palladium(II) analogues (6a and 5a, respectively).
The PtꢀC bonds of 5b (1.969(5) Å) and 6b (1.985(6) Å) are
a bit shorter than those of [Pt{[k2-C,N-(η5-C5H3)-C(Me)d
N(C6H4-4-Br)]Fe(η5-C5H5)}Cl(PPh3)]39 and platinacycles
[Pt{C(sp2,ferrocene),N(sp2,imine)]Cl(DMSO)] (in the range
1.98ꢀ2.05 Å),17h,i,40 but the PtꢀCl distance does not vary signi-
ficantly from the values reported.17h,i,19,39,40
When the reaction was performed in the absence of NaOAc
3
3H2O under identical experimental conditions, the formation of
6a was also detected but the yield decreased from 78 to 56%.
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}Cl-
(DMSO)] (6a) could be easily transformed into 5a by treatment
with PPh3 in benzene at 298 K (Scheme 2, step F). Compound
5a was also obtained from ligand 1 through three consecutive
reactions (A, C, and D in Scheme 2, path I). However, the
procedure summarized in steps E and F of Scheme 2 (path II)
allows the isolation of 5a (a) in shorter reaction periods, (b) with
greater yields (global yields 70% (path II) versus 32% (path I)),
and (c) in a cheaper way. Thus, the use of cis-[PdCl2(DMSO)2]
as metalating agent followed by treatment with PPh3 appears to
be the most convenient method for the preparation of 5a.
Study the Reactivity of 1 with Platinum(II) Salts or
Complexes. In view of the increasing interest in platina-
cycles8aꢀc,10d,12a,12c,17h,17i,37a and the lack of compounds with
“Pt{C(sp2,cyrhetrene),N}” cores, we also studied the reactivity
of 1 toward platinum(II). For comparison purposes, we decided
to follow the same methodology as for the synthesis of 6a
(Scheme 2, step E), but using cis-[PtCl2(DMSO)2] as starting
material. The final product isolated under identical experimental
conditions was identified (see below) as [Pt{[k2-C,N-(η5-C5H3)-
2-(C5H4N)]Re(CO)3}Cl(DMSO)] (6b). Further treatment of
6b with an equimolar amount of PPh3 in benzene produced
[Pt{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}Cl(PPh3)] (5b)
(Scheme 2, step F).
The pyridyl ring is planar and nearly coplanar with the 1,2-
disubstituted η5-C5H3. cycle as reflected in the values of the torsion
angles NꢀC(9)ꢀC(1)ꢀC(2) (5.08ꢀ (in 5b) and 2.36ꢀ (in 6b)).
In the crystals of 5b two molecules are assembled by weak
CꢀH Cl interactions forming dimers, which are connected by
3 3 3
intermolecular C(23)ꢀH(23) O(2) and C(22)ꢀH(22)
π
3 3 3
3 3 3
2
interactions, while in 6b there is a R2 (8) hydrogen bond
structural motif41 between the O(4) and H(14C) atoms of two
DMSO ligands.
On the other hand, it is well-known that an upfield shift in 195Pt
NMR is related to a strong donor interaction.12a,c,17i,42,43 Thus, the
differences detected in the 195Ptchemicalshifts of 5b (δ ꢀ4062 (d,
1JPꢀPt = 4098 Hz)) and6b (δ ꢀ3664) and those of their analogues
[Pt{C(sp2,ferrocene),N}Cl(L)] (with L = PPh3 (ꢀ4150 > δ >
ꢀ4300). DMSO (ꢀ3800 > δ > ꢀ3900))12a,c,17i can be used as a
measure of the different donor abilities of these two types of
bidentate ligands {C(sp2,cyrhetrene),N}ꢀ and {C(sp2,ferrocene),
N}ꢀ in the metallacycles.
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Table 1. Absorption and Emission Properties of the Free
Ligand [{(η5-C5H4-2-C5H4N)}Re(CO)3] (1) and the Mon-
omeric Pallada- and Platinacycles [M{[k2-C,N-(η5-C5H3)-
2-(C5H4N)]Re(CO)3}Cl(L)] (M = Pd, Pt and L = PPh3,
DMSO) in CH2Cl2 Solution (at 298 K)a
absorption spectroscopic datab
λ1
λ2
λ3
emission data
compd
M
L
(log ε1)
(log ε2)
(log ε3)
λmax
1
229 (3.3) 274 (3.1)
230 (3.6) 269b
228 (3.7) 245c
none
5a
5b
6a
6b
Pd PPh3
Pt PPh3
316 (2.9)
308 (2.7)
342 (2.5)
367
e
227 (3.5)
d
230 (3.5) 262 (2.9)
394
e
231 (3.4) 255 (2.8) 330 (2.2)
Pd DMSO 229 (3.5) 258c
229 (3.3)
Pt DMSO 230 (3.1) 263 (2.9)
326 (2.9)
312(2.7)
365 (2.3)
354
e
d
386
e
228 (3.0) 257 (2.6) 353 (2.7)
a Wavelengths λi (i = 1ꢀ3) and λmax are given in nm and extinction
Figure 9. UVꢀvisible spectra of the free ligand (1) and the mono-
nuclear cyclometalated complexes 5a and 6a in CH2Cl2 at 298 K.
coefficient εi in Mꢀ1 cmꢀ1. b For comparison purposes, absorption spec-
c
troscopic data in acetone at 298 K are presented in italics. Shoulder.
d This band was partially overlapped by that at higher energies (λ1), and
its resolution did not allow us to determine accurately the position of the
maximum. e Not studied in acetone.
Further treatment of [M{[k2-C,N-(η5-C5H3)-2-(C5H4N)]-
Re(CO)3}Cl(PPh3)] (M = Pd (5a), Pt (5b)) with PPh3 in
CH2Cl2 or CDCl3 at 298 K did not produce the opening of the
metallacycle and the incorporation of a second PPh3 molecule
in the coordination sphere of the M(II) atom. This behavior,
also observed for their analogues containing ferrocenylimines as
chelating ligands, suggested that the MꢀN bond exhibits low
lability.
assigned as a metal-to-ligand charge transfer (MLCT) transition
from the 4d or 5d orbitals (for M = Pd(II), Pt(II), respectively) to
a π orbital of the ligand.
For platinacycles 5b and 6b, two additional bands in the same
region as 1 were also observed in the spectra, but for 5a and 5b,
the band at λ2 ∼255 nm was poorely defined. These absorptions
are due to metal-perturbed intraligand charge transfer transitions
(MPILCT) (π f π*).
Due to the increasing interest on the photooptical properties
of metallacycles, we also studied the potential emissive properties
of the free ligand and compounds 5a,b and 6a,b. The results
obtained (Table 1) revealed that 1 is not luminescent in CH2Cl2
solution at 298 K. In contrast with these results, for 5a,b and 6a,b
the excitation at the corresponding λ3 produced a weak emis-
sion at λmax (in the range 350 e λmax e 400 nm, Table 1 and
Figure 10). Comparison of data (Table 1) shows that when
Pd(II) in 5a (or 6a) is replaced by Pt(II) in 5b (or 6b), the emis-
sion shifts to the lower energy region. This variation is greater
than that produced by the neutral ligand (DMSO in 5b (or 6b) or
PPh3 in 5a (or 6a)). It should be noted that for the four com-
It should be noted that when [Pd{[k2-C,N-(η5-C5H3)-2-
(C5H4N)]Re(CO)3}(μ-Cl)]2 (4a) was treated with MeO2CCt
CCO2Me (in molar ratios alkyne:4a = 2, 4) in CH2Cl2 or CHCl3
under reflux for 72 h, evidence of the insertion of this alkyne
in the σ{PdꢀC(sp2,cyrhetrene)} bond was not detected by 1H
NMR spectra of the crude material. This indicated that 4a is less
reactive than its analogues with {C(sp2,ferrocene),N}ꢀ ligands.
Furthermore, attempts to achieve platinum(IV) complexes by
treatment of 6b with an excess of CH3I in refluxing acetone
failed, thus showing that in 6b the Pt(II) center is not prone to
undergo the oxidative addition process.
Electronic Spectroscopy. It is well-known that some square-
planar platinum(II) complexes are photoluminescent, with emis-
sive states usually arising from intraligand π f π (IL), metal-to-
ligand charge transfer (MLCT), or even ligand-to-ligand charge
transfer (LL0CT).44 In view of these facts, we also studied the
effect produced by the cyclometalation on the spectroscopic pro-
perties of the new ligand.
plexes the excitation spectra at this low-energy band (λmax
)
resemble their corresponding absorption spectra, thus suggesting
that the emissive states come from the same absorbing species.
Absorption spectra of CH2Cl2 solutions of the free ligand (1)
and complexes [M{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}-
Cl(L)] (M = Pd, Pt and L = PPh3 (5a and 6a, respectively) or
DMSO (5b and 6b)) were also measured at 298 K (Figure 9 and
Table 1). The UVꢀvis spectra of 5a,b and 6a,b (Table 1 and
Figure 9) showed a band in the range 300 nm < λ3 < 400 nm
’ CONCLUSIONS
The new cyrhetrenyl-pyridine ligand [{(η5-C5H4)-2-(C5H4N)}-
Re(CO)3] (1) and the first examples of pallada- (2aꢀ6a) and
platinacycles (5b and 6b), with a {C(sp2,cyrhetrene),N}ꢀ ligand
have been prepared and characterized. The crystal structures of
3
with extinction coefficients between 2.5 ꢁ 103 and 3.0 ꢁ 10
1
M
ꢀ1 cmꢀ1 (Table 1). This absorption was not present in the spec-
trum of the free ligand, and its position was dependent on the
nature of the M(II) ion, the neutral L ligand (PPh3 or DMSO),
and the polarity of the solvent (Table 1). This absorption was
5a /2CH2Cl2, 6a CH2Cl2, 5b, and 6b confirmed (a) the mode
3
3
of binding of 1 in the complexes, (b) a cis arrangement between
the metalated carbon and the neutral ligand (PPh3 (in 5a and
5b) or DMSO (in 6a and 6b)), and (c) the existence of weak
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were registered at the Servei de Espectrometría de Masses (Universitat
de Barcelona) with a LC/MSD-TOF Agilent Technologies instrument.
1
Routine H NMR spectra and 13C{1H} NMR spectra were obtained
with a Mercury-400 instrument. High-resolution 1H NMR spectra
1
13
and the two-dimensional ({1Hꢀ H}-NOESY and -COSY, {1Hꢀ C}-
heteronuclear single quantum coherence (HSQC), and heteronuclear
multiple bond coherence (HMBC)) NMR experiments were recorded
with either a Varian VRX-500 or a Bruker Advance-DMX 500 instru-
ment at 20 ꢀC. The latter instrument was also used for the variable-
temperature NMR studies in the range 188ꢀ298 K. 31P{1H} NMR
spectra of 5a,b were obtained with a Varian 300 MHz instrument at
298 K, and the 195Pt{1H} NMR spectra of 5b and 6b were measured
under identical conditions with a Bruker 250-DXR instrument. The
references used were P(OMe)3 (δ(31P) 140.17) and H2PtCl6 (δ(195Pt)
0.0), respectively. In all cases the NMR studies were performed in
CDCl3 (99.8%) using SiMe4 as internal reference, except for 2a, for
which the solvent was acetone-d6. The chemical shifts (δ) are given in
ppm and the coupling constants (J) in Hz.47 UVꢀvis spectra of CH2Cl2
solutions of the free ligand 1 and complexes 5a,b and 6a,b were recorded
at 298 K with a Cary 100 scan 388 Varian UV spectrometer, and their
emission and excitation spectra were obtained on a Horiba JobinꢀYvon
SPEX Nanolog-TM spectrofluorimeter at 298 K.
Figure 10. Emission spectra of compounds 5a,b and 6a,b in CH2Cl2
at 298 K.
CꢀH O (in 6b) and CꢀH Cl (in the remaining cases)
3 3 3
3 3 3
intermolecular interactions.
Preparation of the Compounds. [{(η5-C5H4)-2-(C5H4N)}Re-
(CO)3] (1). A 200 mg amount of [(η5-C5H5)Re(CO)3] (6.0 ꢁ 10ꢀ4
mol) was dissolved in THF (15 mL). The solution was cooled to 175 K,
and then 0.63 mL (9.6 ꢁ 10ꢀ4 mol) of a 1.6 M solution of butyllithium
in hexane was added. The mixture was stirred at 175 K for 1.5 h. After
this period ZnCl2 (82 mg, 6.9 ꢁ 10ꢀ4 mol) was added, and the reaction
mixture was warmed to room temperature and then kept stirring for
1.5 h. Afterward [PdCl2(PPh3)2] (21 mg, 3.0 ꢁ 10ꢀ5 mol) suspended in
THF (2 mL) and a solution of 2-bromopyridine (57 μL, 6.0 ꢁ 10ꢀ5
mol) in THF (2 mL) were added. The mixture was stirred for 1.5 h at
room temperature and then poured into water (15 mL), and the residue
was extracted with CH2Cl2. The extracts were dried over Na2SO4, fil-
tered through Celite, and evaporated under reduced pressure. The oily
residue that formed was chromatographed over silica gel. Elution with a
hexane/CH2Cl2 (4/1) mixture produced a band that was collected and
concentrated to ca. 3 mL, giving 1 as a white solid. This product was later
recrystallized by slow diffusion of hexane into a CH2Cl2 solution of 1 at
ꢀ10 ꢀC (yield 217 mg, 3.8 ꢁ 10ꢀ4 mol, 88%). Anal. Calcd for C13H8-
NO3Re: C, 37.86; H, 1.96; N, 3.40. Found: C, 37.9; H, 2.1; N, 3.2. MS
(ESI+) m/z: 414 [M + H]+. IR: 2023 (s) and 1929 (vs) cmꢀ1, ν(CO).
1H NMR: 5.41 (t, 2H, 3JHꢀH = 2.3, H3 and H4); 6.06 (t, 2H, 3JHꢀH = 2.3,
H2 and H5); 7.15 (m, 1H, H12); 7.32 (d, 1H, 3JHꢀH = 8.3, H10); 7.62 (dt,
We have also proved that (a) compounds [M{[k2-C,N-(η5-
C5H3)-2-(C5H4N)]Re(CO)3}Cl(L)] (L = PPh3 (5a,b), DMSO
(6a,b)) are not prone to undergo the cleavage of the MꢀN bond,
(b) the σ{PdꢀC(sp2,cyrhetrene)} bond of [Pd{[k2-C,N-(η5-
C5H3)-2-(C5H4N)]Re(CO)3}(μ-Cl)]2 (4a) is less reactive than
the σ{PdꢀC(sp2,ferrocene)} bond of complexes arising from
the metalation of the ferrocene, and (c) complex 6b is reluctant
to oxidize in the presence of MeI.
Furthermore, the UVꢀvis spectra of 5a,b and 6a,b in CH2Cl2
at 298 K showed a metal-to-ligand charge transfer (MLCT) band
in the range 300 e λ3 e 400 nm and excitation at this wavelength
(λ3) produced a weak emission. Despite the fact that these
emissive properties are not spectacular, the complexes presented
here are attractive in view of their potential utility in a variety of
fields. For instance, they are valuable precursors to achieve
related metallacycles with improved photooptical properties or
reactivity (i.e., by (a) incorporation of ligands such as ꢀCCR
or acetylacetonate (that prevent the deactivation of the lowest
emitting exciting state44) or (b) substitution of one (or more) of
the CO ligands of the “Re(CO)3” moiety, respectively). In addi-
tion, they also appear to be excellent candidates for studying not
only their catalytic or antitumoral activities but also their inter-
action with DNA.4 Thus, the results presented here constitute
the first step of further work centered on these fields. Studies on
these areas are currently underway.
3
4
3
1H, JHꢀH = 8.0, JHꢀH = 1.5, H11); 8.51 (d, 1H, JHꢀH = 4.8, H13).
13C{1H} NMR: 83.4 (C2 and C5); 84.7 (C3 and C4); 105.3 (C1);
119.4 (C12); 122.9 (C10); 136.7 (C11); 149.6 (C9); 151.2 (C13); 193.7
(C6, C7, and C8).
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(μ-OAc)]2 (2). To a solu-
tion of 1 (100 mg, 2.4 ꢁ 10ꢀ4 mol) in glacial acetic acid (15 mL) was
added Pd(OAc)2 (54 mg, 2.4 ꢁ 10ꢀ4 mol), and the mixture was refluxed
for 24 h. After this period, the brown-black solution was concentrated
under vacuum, the residue was extracted with CH2Cl2, and the solution
was filtered through Celite. Then the filtrate was concentrated under
reduced pressure to ca. 3 mL. Addition of diethyl ether (15 mL) gave a
brown solid, which was collected by filtration, washed with two (10 mL)
portions of diethyl ether, and dried. Afterward this solid was recrystal-
lized by slow diffusion of hexane into a CH2Cl2 solution of 2 at ꢀ10 ꢀC
(yield 86 mg, 1.5 ꢁ 10ꢀ4 mol, 62%). Anal. Calcd for C30H20N2O10Pd2-
Re2: C, 31.23; H, 1.75; N, 2.43. Found: C, 30.9; H, 1; N, 2.6. MS (ESI+)
m/z: 1143.8 {[M ꢀ CO] + H2O}+; 1084.8 {[M ꢀ CO ꢀ OAc] + H2O}+.
’ EXPERIMENTAL SECTION
General Procedures. All reactions were carried out under nitrogen
using standard Schlenk techniques. All solvents except benzene were
purified and dried by conventional methods and distilled under nitrogen
prior to use.45 The complexes [(η5-C5H5)Re(CO)3], [PdCl2(PPh3)2],
and [MCl2(DMSO)2] (M = Pd, Pt) were prepared by the published
procedures,46 while the remaining reagents were obtained from Aldrich
and used as received. Caution! Some of the preparations described here
required the use of benzene which should be handled with care.
IR spectra were recorded on a Perkin-Elmer FT-1605 spectrophot-
ometer using KBr pellets (for solid samples) or NaCl disks (for solution
studies). Elemental analyses (C, H, N, and S) were carried out at the
Serveis Cientifico-Tꢀecnics (Universitatde Barcelona). Mass spectra (ESI+)
IR: 2011(s) and 1921 (vs), ν(CO); 1563 (m) and 1413 (m) cmꢀ1
,
ν(ꢀCOO). Two isomers (2aI and 2aII) coexisted in acetone-d6 in the
molar ratios 2aI:2aII = 1.00:0.40 (at 298 K) and 1.00:0.39 (at 188 K).
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1H NMR for 2aI: 2.83 (s, 6H, 2OAc); 4.92 (dd, 2H,3JHꢀH = 2.5, 4JHꢀH
=
Method b. Triphenylphosphine (21 mg, 8 ꢁ 10ꢀ5 mol) was added to
3
3
1.0, 2H3); 5.18 (t, 2H, JHꢀH = 2.5, 2H4); 5.83 (dd, 2H, JHꢀH = 3.0,
a solution of 6a CH2Cl2 (50 mg, 7.0 ꢁ 10ꢀ5 mol) in benzene (10 mL).
3
4JHꢀH =1.0, 2H5);7.20(td, 2H,3JHꢀH =7.0, 4JHꢀH =1.5, 2H12);7.42 (dd,
The reaction mixture was stirred at room temperature overnight and then
concentrated under vacuum. The residue was dissolved in the minimum
amount of CH2Cl2. Addition of hexane produced the precipitation of a
pale yellow solid, which was collected, dried, and recrystallized as de-
scribed in method a (yield 53.2 mg, 7.4 ꢁ 10ꢀ4 mol, 89%).
2H, 3JHꢀH = 8.0, 4JHꢀH = 0.5, 2H10); 7.88 (dt, 2H, 3JHꢀH = 8.0, 4JHꢀH
=
1.5, 2H11); 8.22 (ddd, 2H, 3JHꢀH = 5.5, 4JHꢀH = 1.5, 5JHꢀH = 1.0, 2H13).
1H NMR for 2aII: 2.05 (s, 3H, OAc); 2.12 (s, 3H, OAc); 5.10 (dd, 2H,
3JHꢀH = 2.5, 4JHꢀH = 1.0, 2H3); 5.39 (t, 2H, 3JHꢀH = 2.5, 2H4); 6.06 (dd,
2H, 3JHꢀH =2.7, 4JHꢀH =1.2, 2H5); 6.98 (td, 2H, 3JHꢀH =6.6, 4JHꢀH =1.3,
2H12); 7.36 (ddd, 2H, 3JHꢀH = 8.0, 4JHꢀH = 1.0, 5JHꢀH = 0.5, 2H10); 7.72
(td, 2H, 3JHꢀH = 7.7, 4JHꢀH = 1.5, 2H11); 8.01 (ddd, 2H, 3JHꢀH = 5.5,
Characterization data for 5a 1/2CH2Cl2 are as follows. Anal. Calcd
3
for C31H22ClNO3PPdRe 1/2CH2Cl2: C, 44.09; H, 2.70; N, 1.63.
3
Found: C, 44.1; H, 2.7; N, 1.6. MS (ESI+) m/z: 779.99 [M ꢀ Cl]+;
821 {[M ꢀ Cl] + CH3CN}+. IR: 2014 (s) and 1920 (vs) cmꢀ1, ν(CO).
1H NMR: 3.42 (dd, 1H, 3JHꢀH = 2.5, 4JHꢀH = 1.0, H3); 4.95 (td, 1H,
5
4JHꢀH = 1.5, JHꢀH = 0.5, 2H13). 13C{1H} NMR data for 2aI: 24.3
(MeCOO); 83.1 (C5); 84.2 (C3); 85.1 (C4); 118.0 (C12); 122.4 (C10);
139.2 (C11) 152.3 (C9); 151.9 (C13); 184.2 (COOꢀ); 196.4 (C6, C7, and
C8). The signals due to the quaternary carbon atoms C1 and C2 could not
be detected in the 13C{1H}NMR spectrum. 13C{1H} NMR data for 2aII:
23.2 (MeCOO); 82.8 (C5); 83.8 (C3); 85.3 (C4); 118.8 (C12); 122.4
(C10); 140.8(C11) 152.0 (C13, partially masked by the signal due to the
C13atom of 2aII); 183.3 (ꢀCOOꢀ); 196.2 (C6, C7, and C8).
3JHꢀH = 3.0, 4JHꢀH = 1.0, 1H, H4); 5.85 (dd, 1H, 3JHꢀH = 3.0, 4JHꢀH
=
1.5, H5); 7.19 (m, 1H, H12); 7.27 (dd, 1H, 3JHꢀH = 7.5, JHꢀH = 0.5,
H10); 7.43 (m, 9H, aromatic protons of PPh3); 7.74 (td, 1H, 3JHꢀH = 7.5,
4JHꢀH = 1.0, H11); 7.81 (m, 6H, aromatic protons of PPh3); 9.40 (br,
1H, H13). 13C{1H} NMR: 83.7 (C4); 85.6 (C5); 89.6 (C3); 108.5 (C1);
109.5 (C2), 118.0 (C10); 122.9 (C12); 132.2 (C11); 151.4 (C13); 159.4
(C9); 195.8 (C6, C7, and C8); four additional doublets centered at 129.5,
131.1, 132.2, 136.3 (due to the four types of carbon-13 nuclei of the PPh3
ligand). 31P{1H} NMR: 33.9.
4
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(OAc)(PPh3)] (3a). This
compound was prepared in solution on an NMR scale and characterized
by 1H and 31P{1H} NMR spectroscopy. Compound 2a (13 mg, 1.1 ꢁ
10ꢀ5 mol) was introduced into an NMR tube, and then 0.4 mL of CDCl3
was added. The resulting suspension was treated with a solution con-
taining triphenylphosphine (6.0 mg, 2.3 ꢁ 10ꢀ5 mol) and 0.3 mL of
CDCl3. The solution was shaken vigorously at 298 K for 3 min. This
produced the complete dissolution of 2a, giving a pale brown solution.
1H NMR: 1.46 (br, 3H, OAc); 4.04 (d, 1H, 3JHꢀH = 2.5, H3); 4.87 (t,
[M{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(DMSO)Cl] nCH2Cl2 (M =
3
Pd and n = 1, 6a; M = Pt and n = 0, 6b). A 2.4 ꢁ 10ꢀ4 mol amount of
the corresponding [MCl2(DMSO)2] complex (with M = Pd (80.2 mg),
Pt (101 mg)), ligand 1 (100 mg), and a 2-fold excess of NaOAc 3H2O
3
(68.0 mg, 5.0 ꢁ 10ꢀ4 mol) were suspended in 20 mL of toluene. The
resulting mixture was refluxed for 12 h; afterward, it was concentrated
under reduced pressure to ca. 3 mL and the addition of diethyl ether
(20 mL) followed by vigorous stirring at room temperature produced
3
3
1H, JHꢀH = 2.7, H4); 5.83 (d, 1H, JHꢀH = 3.0, H5); 7.16 (td, 1H,
3JHꢀH = 7.2, 4JHꢀH = 1.5, H12); 7.30 (d, 1H, 3JHꢀH = 7.8, H10); 7.46 (m,
6H, aromatic protons of PPh3); 7.74 (dd, 1H, 3JHꢀH = 7.8, 4JHꢀH = 1.5,
H11); 7.80 (m, 9H, aromatic protons of PPh3); 8.43 (br, 1H, H13).
31P{1H} NMR: 34.7.
the precipitation of complexes 6a CH2Cl2 and 6b (as yellowish micro-
3
crystalline products), which were later collected and dried under vacuum
(yields 119 mg (1.65 ꢁ 10ꢀ4 mol), 68% for 6a CH2Cl2 and 141 mg
3
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(μ-Cl)}]2 CH2Cl2 (4a).
(1.97 ꢁ 10ꢀ4 mol), 81% for 6b). Characterization data for 6a CH2Cl2
3
3
A solution of 2 (100 mg, 9.0 ꢁ 10ꢀ5 mol) in CH2Cl2 (10 mL) was
added to a saturated solution of NaCl in water (10 mL), and the mixture
was stirred overnight at room temperature. The brown solid formed was
collected by filtration, washed with two (10 mL) portions of H2O and
then with CH2Cl2 (2 ꢁ 10 mL), and dried under vacuum (yield 67 mg,
are as follows. Anal. Calcd for C15H13ClNO4PdReS CH2Cl2: C, 28.44;
3
H, 2.39; N, 2.22; S, 5.08. Found: C, 28.39; H, 2.35; N, 2.2; S, 5.0. MS
(ESI+) m/z: 637.97 {[M ꢀ Cl] + CH3CN}+; 545.88 [M ꢀ 3CO]+. IR:
2014 (s) and 1920 (vs) cmꢀ1, ν(CO), H NMR: 3.52 (s, 3H, Me-
1
(DMSO)); 3.54 (s, 3H, Me(DMSO)); 5.40 (t, 1H, 3JHꢀH = 2.8, H4);
5.75 (dd, 1H, 3JHꢀH = 2.8, 4JHꢀH = 1.2, H3); 5.79 (dd, 1H, 3JHꢀH = 2.8;
4JHꢀH = 1.2, H5); 7.22 (td, 1H, 3JHꢀH = 7.2; 4JHꢀH = 1.2; H12); 7.35 (d,
1H, 3JHꢀH = 7.6, H10); 7.84 (td, 1H, 3JHꢀH = 7.6; 4JHꢀH = 1.2; H11);
5.6 ꢁ 10ꢀ5 mol, 65%). Anal. Calcd for C26H14Cl2N2O6Pd2Re2
3
CH2Cl2: C, 27.22; H, 1.35; N, 2.35. Found: C, 27.25; H, 1.4; N,
2.5. MS (ESI+) m/z: 1049.74 {[M] ꢀ 2CO}+; 1152.83 {[M ꢀ Cl] +
2CH3CN}+. IR: 2019 (s) and 1917 (vs) cmꢀ1, ν(CO). H NMR (in
9.17 (d, 1H, JHꢀH = 5.6, H13). 13C{1H} NMR: 47.2 (Me(DMSO));
1
3
presence of py-d5, selected data): 4.43 (dd, 1H, 3JHꢀH = 2.4, 4JHꢀH = 1.2,
47.4 (Me(DMSO)); 83.8 (C4); 86.3 (C5); 86.9 (C3); 117.7 (C10);
121.8 (C12); 140.75 (C11); 150.2 (C13); 153.1 (C9); 196.1 (C6; C7, and
C8). Characterization data for 6b are as follows. Anal. Calcd for
C15H13ClNO4PtReS: C, 25.02; H, 1.82; N, 1.95; S, 4.45. Found: C,
25.1; H, 1.7, N, 1.9; S, 4.4. MS (ESI+) m/z: 725.00 {[M ꢀ Cl] +
H3); 5.25 (t, 1H, 3JHꢀH = 2.8, H4); 5.78 (dd, 1H, 3JHꢀH = 2.8, 4JHꢀH
=
1.2, H5); 7.14 (td, 1H, JHꢀH = 6.0, JHꢀH = 1.6, H12); 7.27 (m, 1H,
H10); 7.77 (td, 1H, 3JHꢀH = 7.6, 4JHꢀH = 1.6, H11); 9.33 (br, 1H, H13).
13C{1H} NMR (in the presence of py-d5, selected data): 81.9 (C4); 83.7
(C3); 86.2 (C5); 108.8 (C1); 109.6 (C2); 118.9 (C10); 123.2 (C12);
124.4 (C11); 151.0 (C9); 153.9 (C13); 195.7 (C6, C7 and C8).
3
4
CH3CN}+; 683.97 [M ꢀ Cl]+. IR: 2015 (s) and 1922 (vs) cmꢀ1
,
1
3
ν(CO). H NMR: 3.59 (s, 3H, JPtꢀH = 21.0, DMSO); 3.61 (s, 3H,
3JPtꢀH = 21.5, DMSO); 5.45 (t, 1H, JHꢀH = 3.0, H3); 5.68 (dd, 1H,
3
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(PPh3)Cl] 1/2CH2Cl2 (5a
3
3
3JHꢀH = 2.5, 4JHꢀH = 1.5, H4); 5.71 (dd, 1H, 3JHꢀH = 2.5, 4JHꢀH = 1.5,
1/2CH2Cl2). This compound was obtained using two alternative procedures
that differ in the nature of the starting material: the di-μ-chloro complex
[Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re(CO)3}(μ-Cl)]2 CH2Cl2 (4a
H5); 7.26 (td, 1H, JHꢀH = 6.5; JHꢀH = 1.5, H12); 7.36 (dm, 1H,
3JHꢀH = 8.0, H10); 7.84 (td, 1H, 3JHꢀH = 7.5, 4JHꢀH = 1.5, H11); 9.40 (ddd,
1H, 3JHꢀH = 5.75, 4JHꢀH = 1.5, 5JHꢀH = 1, H13). 13C{1H} NMR: 47.7
(2JPtꢀC = 52.9, Me(DMSO)); 47.9 (2JCꢀPt = 54.2, Me(DMSO)); 81.6
(3JCꢀPt = 44.2, C4); 86.5 (3JCꢀPt = 79.13, C5); 88.1 (2JCꢀPt = 43.8, C3);
100.2 (C1); 109.9 (C2); 118.8 (C10); 122.9 (C12); 141.9 (C11); 151.4
(C13); 161.1 (C9); 196.2 (C6, C7, and C8). 195Pt{1H} NMR: ꢀ3664.
[Pt{[k2-C,N-{(η5-C5H3)-2(C5H4N)Re(CO)3}(PPh3)Cl] (5b). This com-
plex was isolated as a pale yellow solid following the procedure described
3
4
3
3
CH2Cl2) (method a) and [Pd{[k2-C,N-(η5-C5H3)-2-(C5H4N)]Re-
(CO)3}(DMSO)Cl] CH2Cl2 (6a CH2Cl2) (method b).
3
3
Method a. To a suspension of 4a CH2Cl2 (50 mg, 4.2 ꢁ 10ꢀ5 mol)
3
in benzene (10 mL) was added triphenylphosphine (24 mg, 9.1 ꢁ
10ꢀ5 mol). The reaction mixture was stirred at room temperature
overnight and then concentrated to dryness, and the residue that formed
was treated with the minimum amount of CH2Cl2. Addition of hexane
produced the precipitation of 5a 1/2CH2Cl2 as a pale yellow solid that
in method b for 5a 1/2CH2Cl2, but with 6b (60 mg, 8.3 ꢁ 10ꢀ5 mol) and
3
3
was collected and dried. This product was recrystallized in a hexane/
CH2Cl2 (1/3) mixture at ꢀ10 ꢀC (yield 27.8 mg, 3.2 ꢁ 10ꢀ5 mol,
38.6%).
PPh3 (26 mg, 1.0 ꢁ 10ꢀ4 mol) as starting materials (yield 64 mg, 3.4 ꢁ
10ꢀ5 mol, 85%). Anal. Calcd for C31H22ClNO3PPtRe: C, 41.18; H,
2.45; N, 1.55. Found: C, 41.4; H, 2.5; N, 1.4. MS (ESI+) m/z: 868.05
5586
dx.doi.org/10.1021/om200310r |Organometallics 2011, 30, 5578–5589

Organometallics
ARTICLE
Table 2. Crystal Data and Details of the Refinement of the Crystal Structures of the Free Ligand [{(η5-C5H4)-2(C5H4N)}Re-
1
(CO)3}] (1) and the Cyclometalated Compounds 5a /2CH2Cl2, 5b, 6a CH2Cl2, and 6b
3
3
1
5a 1/2CH2Cl2
5b
6a CH2Cl2
6b
3
3
empirical formula
formula wt
T/K
C
13H8NO3Re
C31H22NO3PPdClRe 1/2CH2Cl2 C31H22NO3PPtRe
C15H13NO3PdReS CH2Cl2 C151H13NO3PtReS
3
3
412.40
293(2)
857.98
293(2)
904.21
293(2)
716.30
195(2)
720.06
293(2)
cryst size/mm
λ/Å
0.40 ꢁ 0.40 ꢁ 0.30 0.50 ꢁ 0.50 ꢁ 0.30
0.20 ꢁ 0.10 ꢁ 0.10 0.20 ꢁ 0.10 ꢁ 0.08
0.20 ꢁ 0.10 ꢁ 0.10
0.710 73
monoclinic
P21/n
0.710 73
monoclinic
P21/n
0.710 73
monoclinic
Cc
0.710 73
triclinic
0.710 73
triclinic
cryst syst
space group
a/Å
P1
P1
11.0260(6)
8,3465(4)
13.8932(7)
90.0
37.933(3)
9.1354(7)
19.5917(16)
90.0
9.282(4)
10.126(4)
16.423(4)
107.84(2)
92.51(2)
104.11(3)
1417.6(8)
2
9.806(4)
10.001(2)
11.644(4)
100.81(2)
103.05(2)
101.79(2)
1055.8(6)
2
9.776(3)
17.657(6)
10.232(8)
90.0
b/Å
c/Å
α/deg
β/deg
107.5920(10)
90.0
116.8010(10)
90.0
99.46(16)
90.0
γ/deg
Volume/Å 3
1218.78(11)
4
6059.9(8)
8
1742.2(16)
4
Z
Dcalcd/Mg mꢀ3
μ/mmꢀ1
F(000)
2.248
1.881
2.118
2.253
2.745
9.968
4.848
9.378
7.079
15.255
768
3304
848
676
1312
no. of collected rflns
9403
22 909
12 832
9992
5068
no. of unique rflns, R(int) 2715, 0.0341
6629, 0.0304
367
7040, 0.0748
328
5225, 0.0391
224
5068, 0.0000
217
no. of params
164
R indices (all data)
R1 = 0.0399,
wR2 = 0.0690
R1 = 0.0319,
wR2 = 0.0663
R1 = 0.0561,
wR2 = 0.0748
R1 = 0.0366,
wR2 = 0.0701
R1 = 0.0518,
wR2 = 0.1390
R1= 0.0502,
wR2 = 0.1371
R1 = 0.0327,
wR2 = 0.0870
R1 = 0.0327,
wR2 = 0.0864
R = 0.0645,
wR2 = 0.0767
R1 = 0.0333,
wR2 = 0.0701
R indices (I > 2σ(I))
[M ꢀ Cl]+; 909.08 {[M ꢀ Cl] + CH3CN}+. IR: 2014 (s) and 1920
(vs) cmꢀ1, ν(CO). 1H NMR: 3.41 (dd, 3JHꢀH = 4.8, 4JHꢀH = 0.8, 1H,
H3); 4.95 (t, 3JHꢀH = 2.4, 1H, H4); 5.83 (dd, 3JHꢀH = 2.5, 4JHꢀH = 1, 1H,
H5); 7.22 (m, 1H, H12); 7.35 (dd, 3JHꢀH = 6.4, 4JHꢀH = 0.4, 1H, H10);
7.43 (m, 1H, H11); 7.45ꢀ7.84 (m, 15H, aromatic protons of PPh3); 9.68
(t, 3JHꢀH = 4.5, 1H, H13). 13C{1H} NMR: 84.4 (3JCꢀPt = 44.7, C4); 85.1
(3JCꢀPt = 36.1, C5); 88.5 (2JCꢀPt = 108.2, C3); 100.4 (C1); 108.0 (C2);
118.0 (C10); 122.7 (C12); 140.8 (C11); 150.2 (C13); 160.3 (C9); 196.1
(C6, C7 and C8); four additional doublets at 129.3, 131.1, 132.2, 136.3 due
to the PPh3 ligand. 195Pt{1H} NMR: ꢀ4062 (d, 1JPꢀPt = 4098). 31P{1H}
NMR: 12.2 (1JPtꢀP = 4103).
w = [σ2(I) + (0.0563P)2 + 0.1984P]ꢀ1 (for 6a CH2Cl2), and w = [σ2(I) +
3
(0.0400P)2]ꢀ1 (for 6b). P = (|Fo|2 + 2|Fc|2)/3; f, f 0, and f 00 were taken
from the bibliography.50 In all cases, H atoms were computed and
refined, using a riding model, with an isotropic temperature factor equal
to 1.2 times the equivalent temperature factor of the atom which to
which it is linked. The final R indices and other relevant parameters
concerning the resolution of the crystal structures of these compounds
are presented in Table 2.
’ ASSOCIATED CONTENT
S
Crystallography. A prismatic crystal (sizes in Table 2) of 1,
Supporting Information. CIF files giving full details of
b
5a 1/2CH2Cl2, 5b, 6a CH2Cl2,or 6b was selected and mounted on a
1
the crystallographic analyses of compounds 1, 5a /2CH2Cl2,
5b, 6a CH2Cl2, and 6b. This material is available free of charge
via the Internet at http://pubs.acs.org.
3
3
3
Bruker-Siemens Smart CCD diffractometer (equipped with a normal-
3
focus, 2.4 kW sealed-tube X-ray source Mo Kα radiation and operating
at 50 kV and 20 mA) for 1 and 5a 1/2CH2Cl2, on a MAR345
3
diffractometer for 5b and 6a CH2Cl2, or on a Enraf- Nonius CAD4
3
four-circle diffractometer with an image plate detector for 6b. In the last
two cases, intensities were collected with graphite-monochromated
Mo Kα radiation. For 6b, three reflections were measured every 2 h
as orientation and intensity control; significant intensity decay was not
observed. Lorentzꢀpolarization and absorption corrections were made.
These structures were solved by direct methods using the SHELXS
computer program48 and refined by full-matrix least-squares methods
with the SHELX97 computer program49 using 2455 (for 1), 5321 (for
5a 1/2CH2Cl2), 12 832 (for 5b), 9992 (for 6a CH2Cl2), or 5068 (for
’ ACKNOWLEDGMENT
H.K. acknowledges the FONDECYT-Chile (Project 1060487)
and D.I. Pontificia Universidad Catꢀolica de Valparaiso. T.C.
acknowledges the CONICYT for doctoral and travel scho-
larships. C.L. is grateful to the Ministerio de Ciencia y Tecnología
of Spain and to FEDER funds for financial support (Grant No.
CTQ2009-11501).
3
3
’ REFERENCES
6b) reflections (very negative intensities were not assumed). The func-
tion minimized was ∑w||Fo|2 ꢀ |Fc|2|2, where w = [σ2(I) + (0.0289P)2 +
1.3732P]ꢀ1 (for 1), w = [σ2(I) + (0.0289P)2 + 24.3025P]ꢀ1 (for
5a 1/2CH2Cl2), w = [σ2(I) + (0.0951P)2 + 0.6924P]ꢀ1 (for 5b CH2Cl2),
(1) O’Connor, J. M. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Perganon: Oxford, U.K.,
1995; Vol. 6, p 167.
3
3
5587
dx.doi.org/10.1021/om200310r |Organometallics 2011, 30, 5578–5589

Organometallics
ARTICLE
(2) (a) Lawes, D. J.; Geftakis, S.; Ball, G. E. J. Am. Chem. Soc. 2005,
127, 4134. (b) Higgith, C. L.; Klahn, A. H.; Moore, M. H.; Partridge,
M. G.; Perutz, R. N. J. Chem. Soc., Dalton Trans. 1997, 1269. (c) Klahn,
A. H.; Moore, M. H.; Perutz, R. N. J. Chem. Soc., Chem. Commun. 1992,
1699. (d) Godoy, F.; Higgitt, C. L.; Klahn, A. H.; Oelckers, B.; Parsons,
S.; Perutz, R. N. J. Chem. Soc., Dalton Trans. 1999, 2039.
(3) (a) Sierra, D.; Mu~noz, A.; Godoy, F.; Klahn, A. H.; Ibꢀa~nez, A.;
Garland, M. T.; Fuentealba, M. Polyhedron 2009, 28, 322. (b) Sierra, D.;
Klahn, A. H.; Ramirez-Tagle, R.; Arratia-Perez, R.; Godoy, F.; Garland,
M. T.; Fuentealba, M. Dalton Trans. 2010, 39, 6295.
(4) (a) Stemmler, R. T.; Bolm, C. Tetrahedron Lett. 2007, 48, 6189.
(b) Bolm, C.; Xiao, L.; Kesselgruber, M. Org. Biomol. Chem. 2003, 1, 145.
(c) Stemmler, R.; Bolm, C. J. Org. Chem. 2005, 70, 9925. (d) Bolm, C.;
Xiao, L.; Hintermann, L.; Focken, T.; Raabe, G. Organometallics 2004,
23, 2362. (e) Eichenseher, S.; Delacroix, O.; Kromm, K.; Hampel, F.;
Gladysz, J. A. Organometallics 2005, 24, 245.
J. J.; Fernꢀandez, A.; Vꢀazquez-García, D.; Lꢀopez-Torres, M.; Rodríiguez,
A.; Vila, J. M. Polyhedron 2009, 28, 3607. (i) Cruz, S.; Bernes, S.; Sharma,
P.; Vꢀazquez, R.; Hernꢀandez, G.; Portillo, R.; Gutiꢀerrez, R. Appl. Organo-
met. Chem. 2010, 24, 8. (j) Lee, K.-E.; Jeon, H.-T.; Han, S.-Y.; Ham, J.;
Kim, Y.-J.; Lee, S. W. Dalton Trans. 2009, 6578. (k) Dupont, J.; Flores,
F. R. Handbook of Green Chemistry: Green Catalysis 2009, 1, 319.
(l) Albert, J.; Crespo, M.; Granell, J.; Rodríguez, J.; Zafrilla, J.; Calvet,
T.; Font-Bardia, M.; Solans, X. Organometallics 2010, 29, 214.
(11) For a general overview on metallacycles with bidentate {C(sp2,
ferrocene),N}ꢀ ligands see for instance: Wu, Y.; Huo, S.; Gong, J.; Cui,
X.; Ding, L.; Ding, K.; Du, C.; Liu, Y.; Song, M. J. Organomet. Chem.
2001, 637ꢀ639, 27 and references therein.
(12) For more recent contributions: (a) Lꢀopez, C.; Pꢀerez, S.; Solans,
X.; Font-Bardía, M.; Calvet, M. T. New J. Chem. 2010, 34, 676. (b) Pou,
D.; Lꢀopez, C.; Pꢀerez, S.; Solans, X.; Font-Bardia, M.; van Leeuwen, P. W.
N. M.; van Strijdonck, G.P. F. Eur. J. Inorg. Chem. 2010, 1642. (c) Pꢀerez,
S.; Lꢀopez, C.; Caubet, A.; Solans, X.; Font-Bardía, M. Eur. J. Inorg. Chem.
2008, 1599. (d) Qian, H.; Cui, X.; Tang, M.; Liu, C.; Liu, C.; Wu, Y.
New J. Chem. 2009, 33, 668. (e) Vꢀazquez-Garcia, D.; Fernꢀandez, A.;
Lꢀopez-Torres, M.; Rodríguez, A.; Gꢀomez-Blanco, N.; Viader, C.; Vila,
J. M.; Fernꢀandez, J. J. Organometallics 2010, 29, 3303.
(5) Ferber, B.; Top, S.; Vessiꢁeres, A.; Welter, R.; Jaouen, G.
Organometallics 2006, 25, 5730.
(6) For a general overview on cyclopallada- and cycloplatinated
compounds and their applications, see: (a) Dupont, J., Pfeffer, M., Eds.
Palladacycles. Synthesis, Characterization and Applications; Wiley-VCH:
Weinheim, Germany, 2008. (b) Godula, K.; Sames, D. Science 2006,
312, 67. (c) Ghedini, M.; Aiello, I.; Crispini, A.; Golemme, A.; La Deda,
M.; Pucci, D. Coord. Chem. Rev. 2006, 250, 1373.
(7) For additional properties of pallada- and platinacycles, see for
instance: (a) Jolliet, P.; Gianini, M.; von Zelewsky, A.; Bernardinelli, G.;
Stoeckli-Evans, H. Inorg. Chem. 1996, 35, 4883. (b) von Zelewsky, A.;
Suckling, A. D.; Stoeckli-Evans, H. Inorg. Chem. 1996, 35, 4889.
(c) Braterman, P. S.; Song, J. I.; Wimmer, F. M.; Wimmer, S.; Kain,
W.; Klein, A.; Peacock, R. D. Inorg. Chem. 1992, 31, 5084. (d) Maestri,
M.; Deuschel-Cornioley, C.; von Zelewsky, A. Coord. Chem. Rev. 1991,
111, 117 and references therein. (e) Oshawa, Y.; Sprouse, S.; King, K. A.;
de Armond, M. K.; Hanck, K. W.; Watts, R. J. J. Phys. Chem. 1987, 91,
1047. (f) King, K. A.; Spellane, P. J.; Watts, R. J. J. Am. Chem. Soc. 1985,
107, 1431.
(13) See for instance: (a) Pfeffer, M.; Sutter, J. P.; de Cian, A.;
Fischer, J. Organometallics 1993, 12, 1167. (b) Pfeffer, M.; Rotteveel,
M. A.; Sutter, J. P.; de Cian, A.; Fischer, J. J. Organomet. Chem. 1989, 371,
C21. (c) Zhao, G.; Wang, Q. G.; Mak, T. C. W. J. Organomet. Chem.
1999, 574, 311. (d) Pꢀerez, S.; Lꢀopez, C.; Caubet, A.; Pawezczyk, A.;
Solans, X.; Font-Bardía, M. Organometallics 2003, 22, 2396.
(14) Brunner, H. Eur. J. Inorg. Chem. 2001, 905.
(15) (a) Friedlein, F. K.; Kromm, K.; Hampel, F.; Gladysz, J. A.
Chem. Eur. J. 2006, 12, 5267. (b) Friedlein, F. K.; Hampel, F.; Gladysz,
J. A. Organometallics 2005, 24, 4103.
(16) (a) Arancibia, R.; Godoy, F.; Buono-Core, G.; Klahn, A. H.;
Gutierrez-Puebla, E.; Monge, A. Polyhedron 2008, 27, 2421. (b) Cautivo,
T.; Godoy, F.; Klahn, A. H.; Bouno-Core, G.; Sierra, D.; Fuentealba, M.;
Garland, M. T. Inorg. Chem. Commun. 2007, 10, 1031.
(17) (a) Moyano, A.; Rosol, M.; Moreno, R. M.; Lꢀopez, C.; Maestro,
M. A. Angew. Chem., Int. Ed. 2005, 44, 1865. (b) Pꢀerez, S.; Lꢀopez, C.;
Caubet, A.; Solans, X.; Font-Bardía, M.; Roig, A.; Molins, E. Organome-
tallics 2006, 25, 596. (c) Bosque, R.; Benito, M.; Lꢀopez, C. New J. Chem.
2001, 25, 827. (d) Benito, M.; Lꢀopez, C.; Morvan, X.; Solans, X.;
Font-Bardía, M. Dalton Trans. 2000, 4470. (e) Bosque, R.; Lꢀopez, C.;
Solans, X.; Font-Bardía, M. Organometallics 1999, 18, 1267. (f) Lꢀopez,
C.; Bosque, R.; Solans, X.; Font-Bardía, M. New J. Chem. 1997, 22, 977.
(g) Lꢀopez, C.; Bosque, R.; Sainz, D.; Solans, X.; Font-Bardía, M. Organo-
metallics 1997, 16, 3261. (h) Lꢀopez, C.; Caubet, A.; Pꢀerez, S.; Solans, X.;
Font-Bardía, M. Chem. Commun. 2004, 540. (i) Lꢀopez, C.; Caubet, A.;
Pꢀerez, S.; Solans, X.; Font-Bardía, M.; Molins, E. Eur. J. Inorg. Chem.
2006, 3974.
(18) (a) Iyoda, M.; Kondo, T.; Okabe, T.; Matsuyama, H.; Sasaki, S.;
Kuwatani, Y. Chem. Lett. 1997, 35. (b) Kowalski, K.; Winter, R.
J. Organomet. Chem. 2008, 693, 2181.
(19) (a) Cambridge Crystallographic Data Base (updated on
November 2010). (b) Allen, T. H. Acta Crystallogr., Sect. B: Struct. Sci.
2002, 58, 380.
(8) (a) Caires, A. F. Anti-Cancer Agents Med. Chem. 2007, 7, 484. (b)
Headford, C. E. L.; Mason, R.; Ranatunge-Bandarage, P. R.; Robinson,
B. H.; Simpson, J. J. Chem. Soc., Chem. Commun. 1990, 601. (c) Mason,
R. W.; McGrouther, K.; Ranatunge-Bandarage, P. R. R.; Robinson, B. H.;
Simpson, J. Appl. Organomet. Chem. 1999, 13, 163. (d) Mdleleni, M. M.;
Bridgewater, J. S.; Watts, R. J.; Ford, P. C. Inorg. Chem. 1995, 34, 2334.
(e) Higgins, L.; Neely, S.; Fricker J. Inorg. Biochem. 1993, 49, 149. (f)
Navarro-Ranninger, C.; Lꢀopez-Solera, I.; Pꢀerez, J. M.; Massaguer, J. R.;
Alonso, C. Appl. Organomet. Chem. 1993, 7, 57. (g) Sun, R.W-Y.; Ma,
D. L.; Wong, E.L-M; Che, C.-M. Dalton Trans. 2007, 4883. (h) Spencer,
J.; Casini, A.; Zava, O.; Rathnam, R. P.; Velhanda, S. K.; Pfeffer, M.;
Callear, S. K.; Hursthouse, M. B.; Dyson, P. J. Dalton Trans. 2009, 10731.
(9) For additional applications of pallada- and platinacycles see for
instance: (a) Omae, I. Applications of Organometallic Compounds; Wiley:
Chichester, U.K., 1998; Chapter 20. (b) Klaus, A. J. Modern Colorants:
Synthesis and Structure; Springer: London, 1995; Vol. 3, p 1. (c) Wild,
S. B. Coord. Chem. Rev. 1997, 166, 291. (d) Pfeffer, M. Recl. Trav. Chim.
Pays-Bas 1990, 109, 567 and references therein. (e) Ryabov, A. D.
Synthesis 1985, 3, 233. (f) Sokolov, V. I. Chirality and Optical Activity in
Organometallic Chemistry; Gordon and Breach: London, 1991. (g) Buey,
J.; Espinet, P.; Kitzerow, H. S.; Shours, J. Chem. Commun. 1999, 441 and
references cited therein.
(10) For recent advances in this field: (a) Durand, J.; Gladiali, S.;
Erre, G.; Zangrando, E.; Milani, B. Organometallics 2007, 26, 810. (b)
Robinson, R., Jr.; Sharp, P. R. Organometallics 2010, 29, 1388. (c) Rosby,
S. H.; Clarkson, G. J.; Rourke, J. P. J. Am. Chem. Soc. 2009, 131, 14142.
(d) Anderson, C. M.; Crespo, M.; Tanski, J. M. Organometallics 2010,
29, 2676. (e) Scaffidi-Domianello, Y.Yu.; Nazarov, A. A.; Haukka, M.;
Galanski, M.; Keppler, B. K.; Schneider, J.; Du, P.; Eisenberg, R.;
Kukushkin, V. Y. Inorg. Chem. 2007, 46, 4469. (f) Liu, B.-B.; Wang,
X.-R.; Guo, Z.-F.; Lu, Z.-L. Inorg. Chem. Commun. 2010, 13, 814. (g)
Emin, G. M.; Guemuesada, R.; Oezdemir, N.; Dincer, M.; Cetinkaya, B.
Inorg. Chem. Commun. 2009, 12, 990. (h) Gꢀomez-Blanco, N.; Fernꢀandez,
(20) Desiraju, G. R. Dalton Trans. 2000, 3745.
(21) (a) Scheiner, S. Theor. Appl. Comput. Chem. 2005, 831.
(b) Castellano, R. K. Curr. Org. Chem. 2004, 8, 845.
(22) The distances (in Å) between the oxygen and hydrogen atoms
involved in these interactions are as follows: O(1) H(5#), 2.638;
3 3 3
O(2) H(13*), 2.644; O(1) H(120), 2.694.
3 3 3
3 3 3
(23) Tsuzuki, S.; Fuji, A. Phys. Chem. Chem. Phys. 2008, 10, 2584.
(24) (a) Butler, I. R.; Roustan, J.-L. Can. J. Chem. 1990, 68, 2212.
(b) Butler, I. R.; Burke, N.; Hobson, L. J.; Findenegg, H. Polyhedron
1992, 11, 2435. (c) Butler, I. R. Organometallics 1992, 11, 74.
(25) (a) Hiraki, K.; Fuchita, Y.; Nakaya, H.; Takakura, S. Bull. Chem.
Soc. Jpn. 1979, 52, 2531. (b) Fuchita, Y.; Tsuchiya, H.; Miyafuji, A. Inorg.
Chim. Acta 1995, 233, 91. (c) Lꢀopez-Torres, M.; Juanatey, P.; Fernꢀandez,
J.; Fernꢀandez, A.; Suꢀarez, A.; Mosteiro, R.; Ortigueira, J.; Vila, J. M.
5588
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Organometallics
ARTICLE
Organometallics 2002, 21, 3628. (d) Zamora, F.; Luna, S.; Amo-Ochoa,
P.; Martínez-Cruz, L. A.; Vegas, A. J. Organomet. Chem. 1996, 522, 97.
(e) Gonzꢀalez, A.; Lꢀopez, C.; Solans, X.; Font-Bardía, M.; Molins, E.
J. Organomet. Chem. 2008, 693, 2119. (f) Cꢀardenas, D. J.; Echavarren,
A. M. Organometallics 1999, 18, 3337.
(47) For the assignment of 1H and 13C NMR data, the labels of the
atoms correspond to those depicted in in Schemes 1 and 2.
(48) Sheldrick, G. M. SHELXS: A Computer Program for Automatic
Solution of Crystal Structures; University of G€ottingen, G€ottingen,
Germany, 1997.
(26) Nakamoto, K. Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 5th ed.; Wiley: New York, 1997.
(27) Evans, P. G.; Brown, N. A.; Clarkson, G. J.; Newman, C. P.;
Rourke, J. P. J. Organomet. Chem. 2006, 691, 1251.
(49) Sheldrick, G. M. SHELXL-97: A Program for Refining Crystal
Structures; University of G€ottingen, G€ottingen, Germany, 1997.
(50) International Tables of X-Ray Crystallography; Kynoch Press:
Birmingham, U.K., 1974; Vol. IV, pp 99ꢀ100.
(28) For illustrative purposes, we include the best results obtained
for all the crystals of 2a tested: empirical formula C15H7NO5O8PdRe,
T = 298 K, crystal system monoclinic, a = 16.034(4) Å, b = 17.082(5) Å,
c = 14.781(4) Å, α = γ = 90ꢀ and β = 121.580(3)ꢀ, V = 3448.9(16) Å3,
space group C2/c, crystal dimensions 0.20 ꢁ 0.20 ꢁ 0.20 mm; no. of
reflections 9764 (collected) and 2904 (unique), number of parameters
185; R indices for I > 2σ(I) R1 = 0.1673 and wR2 = 0.3082 and for all
data R1 = 0.2043 and wR2 = 0.3249; completeness to θ = 95.6%.
(29) Zhao, G.; Wang, Q.-G.; Mak, T. C. W. J. Organomet. Chem.
1999, 574, 311.
(30) Benito, M.; Lꢀopez, C.; Solans, X.; Font-Bardía, M. Tetrahedron:
Asymmetry 1998, 9, 4219.
(31) (a) Vicente, J.; Arcas, A.; Bautista, D.; Jones, P. G. Organome-
tallics 1997, 16, 2127. (b) Vicente, J.; Abad, J. A.; Frankland, A. D.;
Ramirez de Arellano, M. C. Chem. Eur. J. 1999, 5, 3066. (c) Vicente, J.;
Abad, J. A.; Martínez-Viviente, E.; Jones, P. G. Organometallics 2002,
21, 4445.
(32) (a) Albert, J.; Granell, J.; Tavera, R. J. Organomet. Chem. 2003,
667, 192. (b) Albert, J.; D’Andrea, L.; Granell, J.; Tavera, R.; Font-Bardía,
M.; Solans, X. J. Organomet. Chem. 2007, 692, 3070.
(33) The sum of the bond angles around the palladium(II) is
360.01ꢀ.
(34) (a) Bondi, A. J. Phys. Chem. 1964, 68, 441. (b) Kitaigorodskii,
A. I. Molecular Crystals and Molecules; Academic Press: London, 1973.
(35) Das, S.; Pal, S. J. Organomet. Chem. 2004, 689, 352.
(36) (a) Lꢀopez, C.; Caubet, A.; Solans, X.; Font-Bardía, M.
J. Organomet. Chem. 2000, 598, 87. (b) Bosque, R.; Lꢀopez, C.; Sales,
J.; Solans, X.; Font-Bardía, M. J. Chem. Soc., Dalton Trans. 1994, 735.
(37) (a) Pꢀerez, S.; Lꢀopez, C.; Caubet, A.; Bosque, R.; Solans, X.;
Font-Bardía, M.; Roig, A.; Molins, E. Organometallics 2004, 23, 224.
(b) Caubet, A.; Lꢀopez, C.; Bosque, R.; Solans, X.; Font-Bardía, M.
J. Organomet. Chem. 1999, 577, 294.
(38) Deviations from the mean plane: 0.035 and 0.046 Å (for 5b and
6b, respectively).
(39) Wu, Y.-J.; Ding, L.; Wang, W.-L.; Du, C.-X. Tetrahedron:
Asymmetry 1998, 9, 4035.
(40) Wu, J.-Y.; Ding, L.; Wang, H.-X.; Liu, Y. H.; Yuan, H. Z.; Mao,
X.-A. J. Organomet. Chem. 1997, 535, 49.
(41) Bernstein, J.; Davies, R. E.; Shimoni, L.; Chang, N.-L. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1555.
(42) (a) Pregosin, P. S. Coord. Chem. Rev. 1982, 44, 247. (b) Still,
B. M.; Kumar, P. G. A.; Aldrich-Wright, J. R.; Price, W. S. Chem. Soc. Rev.
2007, 36, 665.
(43) Riera, X.; Caubet, A.; Lꢀopez, C.; Moreno, V.; Solans, X.;
Font-Bardía, M. Organometallics 2000, 19, 1384.
(44) (a) Williams, J. A. G. Chem. Soc. Rev. 2009, 38, 1783.
(b) Eryazici, I.; Moorefield, C. N.; Newkome, G. R. Chem. Rev. 2008,
108, 1834. (c) J.A.G. Williams, J. A. G.; Develay, S.; Rochester, D. L.;
Murphy, L. Coord. Chem. Rev. 2008, 252, 2596. (d) W€urtz, S.; Glorius, F.
Acc. Chem. Res. 2008, 41, 1523. (e) Wong, K. M.-C.; Yam, V. W.-W.
Coord. Chem. Rev. 2007, 251, 2477. (f) Katz, M. J.; Sakai, K.; Leznoff,
D. B. Chem. Soc. Rev. 2008, 37, 1884.
(45) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann: Oxford, U.K., 1996.
(46) (a) Patton, A. T.; Strouse, C. E.; Knobler, C. B.; Gladysz, J. A.
J. Am. Chem. Soc. 1983, 105, 5804. (b) Szafran, Z.; Pike, R. M.; Singh,
M. M. Microscale Inorganic Chemistry. A Comprehensive Laboratory
Experience; Wiley,: New York, 1991; p 218. (c) Price, J. H.; Williamson,
A. N.; Schramm, R. F.; Wayland, B. B. Inorg. Chem. 1972, 11, 1280.
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