C-Br versus C-H bond activation in palladium (II) cyclopalladated compounds. Crystal and molecular structure of [Pd{C6H4C(H)=NCy}(MeCOCHCOMe)]

Article abstract of DOI:10.1016/S0022-328X(02)01882-X

Treatment of N-(2-bromobenzylidene)cyclohexylamine, 2-BrC₆H₄C(H)=NCy (a), with tris(dibenzylideneacetone) palladium(0) in refluxing benzene gave the cyclometallated compound [Pd{C₆H₄C(H)=NCy}(Br)]₂ (1). Treatment of 1 with thallium acetylacetonate gave the mononuclear cyclometallated compound [Pd{C₆H₄C(H)=NCy}(MeCOCHCOMe)] (2). Reaction of a with palladium(II) acetate in refluxing acetic acid gave the dinuclear Pd(II) compound [Pd{2-BrC₆H₃C(H)= NCy}(O₂CMe)]₂ (3). Treatment of 3 with aqueous sodium chloride gave the dimer complex [Pd{2- BrC₆H₃C(H)=NCy}(Cl)]₂ (4). Reaction of 4 with tertiary phosphines gave the cyclometallated complexes [Pd{2-BrC₆H₃C(H)=NCy}(L)] (5: L = PPh₃; 6: L = PEtPh₂; 7: L = PMePh₂), with the phosphine ligand trans to the imine nitrogen atom. Treatment of 2-Br=4,5- tris(dibenzylideneacetone)palladium(0) gave [Pd{4,5-(MeO)₂C₆H₂C(H)=NCH₂ CH₂NMe₂}(X)] (8: X = Cl; 16: X = Br, respectively) and with the ligand as [C, N, N] terdentate. Treatment of 8 with tertiary phosphines gave [Pd{4,5-(MeO)₂C₆H₂ C(H)=NCH₂CH₂NMe₂}(Cl)(L)] (9: L = PPh3; 10: L = PEtPh₂; 11: L = PMePh₂). Reaction of 1,4-{2-Br-4,5-(MeO)₂C₆H₂C(H)-N} ₂C₆H₄ (c), with PdCl₂, Li₂[PdCl₄] or K₂[PdCl₄] gave the tetranuclear compound [1,4-{Pd[4,5-(MeO)₂C₆ H₂C(H)=N](Cl)}₂C₆H₄] ₂ (12), which when treated with tertiary phosphines gave the dinuclear species 13-15. The molecular structure of 2 has been determined by X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(02)01882-X

Journal of Organometallic Chemistry 663 (2002) 239Á248
/
www.elsevier.com/locate/jorganchem
CÃ
/
Br versus CÃ
/
H bond activation in palladium(II) cyclopalladated
compounds.
Crystal and molecular structure of [Pd{C6H4C(H)Ä
/
NCy}(MeCOCHCOMe)]
Jose´ M. Vila a,ꢀ, Teresa Pereira a, Juan M. Ortigueira a, Adriana Amoedo a,
Mar´ıa Grana a, Gemma Alberdi a, Margarita Lo´pez-Torres b, Alberto Ferna´ndez b
˜
a
´ ´
Departamento de Quımica Inorganica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
b
´
Departamento de Quımica Fundamental, Facultad de Ciencias, Universidad de La Coruna, E-15071 La Coruna, Spain
˜
˜
Received 10 June 2002; accepted 4 September 2002
Dedicated to Professor Pascual Royo on the occasion of his 65th birthday
Abstract
Treatment of N-(2-bromobenzylidene)cyclohexylamine, 2-BrC6H4C(H)Ä
refluxing benzene gave the cyclometallated compound [Pd{C6H4C(H)ÄNCy}(Br)]2 (1). Treatment of 1 with thallium acetylace-
tonate gave the mononuclear cyclometallated compound [Pd{C6H4C(H)ÄNCy}(MeCOCHCOMe)] (2). Reaction of a with
palladium(II) acetate in refluxing acetic acid gave the dinuclear Pd(II) compound [Pd{2-BrC6H3C(H)ÄNCy}(O2CMe)]2 (3).
Treatment of 3 with aqueous sodium chloride gave the dimer complex [Pd{2-BrC6H3C(H)ÄNCy}(Cl)]2 (4). Reaction of 4 with
tertiary phosphines gave the cyclometallated complexes [Pd{2-BrC6H3C(H)ÄNCy}(L)] (5: LꢁPPh3; 6: LꢁPEtPh2; 7: Lꢁ
PMePh2), with the phosphine ligand trans to the imine nitrogen atom. Treatment of 2-BrÃ4,5-(MeO)2C6H2C(H)ÄNCH2CH2NMe2
(b), with palladium(II) chloride in refluxing octane or with tris(dibenzylideneacetone)palladium(0) gave [Pd{4,5-(MeO)2C6H2C(H)Ä
NCH2CH2NMe2}(X)] (8: XꢁCl; 16: XꢁBr, respectively) and with the ligand as [C, N, N] terdentate. Treatment of 8 with tertiary
phosphines gave [Pd{4,5-(MeO)2C6H2C(H)ÄNCH2CH2NMe2}(Cl)(L)] (9: LꢁPPh3; 10: LꢁPEtPh2; 11: LꢁPMePh2). Reaction of
1,4-{2-BrÃ4,5-(MeO)2C6H2C(H)ÄN}2C6H4 (c), with PdCl2, Li2[PdCl4] or K2[PdCl4] gave the tetranuclear compound [1,4-{Pd[4,5-
(MeO)2C6H2C(H)ÄN](Cl)}2C6H4]2 (12), which when treated with tertiary phosphines gave the dinuclear species 13Á15. The
/
NCy (a), with tris(dibenzylideneacetone)palladium(0) in
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
molecular structure of 2 has been determined by X-ray crystallography.
# 2002 Published by Elsevier Science B.V.
Keywords: Palladium(II) cyclopalladated compounds; Crystal and molecular structures; X-ray crystallography
1. Introduction
cally active components [8,9], and as species with
specific antitumor activity [10,11], among others.
The chemistry of cyclometallated compounds [1,2] is a
thoroughly developed area of organometallic chemistry
and abundant articles and reviews have been published
related to their syntheses, reactivity and fruitful applica-
tions, such as their use as active catalysts [3,4], as
intermediates in the synthesis of new organometallic and
Our interest in this field has mainly dealt with Pd(II)
compounds, i.e. derivatives of differently substituted
[C,N] Schiff bases [12,13], ferrocenylimines [14], or
substituted imidazoles [15], as well as derivatives of
[C,N,X] (Xꢁ
Metallation of the organic substrate may be achieved
through activation of a CÃH bond by electrophilic
/
N, O, S) terdentate ligands [16Á
/18].
organic compounds [5Á7], in the preparation of opti-
/
/
attack of Pd(II) pertaining to salts such as palladium(II)
chloride, palladium(II) acetate or potassium tetrachlor-
ꢀ Corresponding author. Fax: ꢂ34-81-595012
E-mail address: qideport@usc.es (J.M. Vila).
/
opalladate; and also by activation of CÃ
/
X bonds, which
0022-328X/02/$ - see front matter # 2002 Published by Elsevier Science B.V.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 8 8 2 - X

240
J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á248
/
supplies a means to reach the metallated compound in
an oxidative addition reaction of the ligand with Pd(0)
reagents such as [Pd2(dba)3] [19]. In the former case,
substitution of a metallation site by, e.g. Me, MeO
13C{1H}-NMR for 2 showed resonances at d 171.0 (CÄ
/
N), 157.0 (C2) and 146.1 (C1) shifted to higher
frequency, also confirming metallation of the organic
ligand [19]. There was no noticeable quadrupolar
broadening of these resonances with the 105Pd (22%
groups or halogens, hinders CÃ
the metal is directed towards a remaining CÃ
the ligand, whereas in the latter, metallation proceeds
via the CÃX carbon atom, as opposed to the CÃH bond.
/Pd bond formation and
/
H bond in
natural abundance, Iꢁ5/2) nucleus. The crystal struc-
/
ture of compound 2 has been determined by X-ray
crystallography (vide infra). We and others have shown
/
/
In the present paper, we report our more recent
findings related to cyclometallated Pd(II) compounds
derived from 2-bromobenzylideneimines, where forma-
that treatment of the related ligand, 2-ClC6H4C(H)Ä
/
NCH2CH2NMe2, with Pd(II) salts such as palladium(II)
acetate or Li2[PdCl4] did not produce activation of the
tion of the CÃ
remainder substituents of the phenyl ring. Thus, 2-
BrC6H4C(H)ÄNCy follows the expected metallation
pattern upon treatment with Pd(0) or Pd(II), whereas
2-BrÃ4,5-(MeO)2C6H2C(H)ÄNCH2CH2NMe2 and 1,4-
{2-BrÃ4,5-(MeO)2C6H2C(H)ÄN}2C6H4 exhibit CÃPd
bonds at the C2 carbon atom when treated with
Pd(II), instead of the expected C(6)ÃPd bonds.
/
Pd bond seems to depend on the
CÃ
/
H or CÃ
/
Cl bonds; only reduction to Pd(0) was
observed [19,23]. However, in the present case reaction
of ligand a with palladium(II) acetate in boiling acetic
acid yielded the dinuclear cyclometallated complex with
/
/
/
acetate-bridging ligands [Pd{2-BrC6H3C(H)Ä
(O2CMe)]2 (3), after CÃH activation at the C6 atom,
/NCy}-
/
/
/
/
which was fully characterized (see Section 4 and Table
1). The Dn value for the asymmetric and symmetric
n(COO) stretching modes was consistent with bridging
acetate ligands [24]. In contrast to complex 2, only three
aromatic proton resonances were assigned at d 7.11
(H3), 6.99 (H5) and 6.83 (H4), in accordance with
metallation of the C6 carbon atom. Compound 3 was
converted to the chloro-bridged species [Pd{2-
/
2. Results and discussion
2.1. Cyclometallated compounds
The Schiff base ligands a, b and c were prepared by
reaction of 2-bromobenzaldehyde or 2-bromo-4,5-di-
methoxybenzaldehyde with cyclohexylamine, N,N-di-
methylethylendiamine or 1,4-phenylenediamine as
appropriate (see Section 4). The IR spectra showed the
BrC6H3C(H)Ä
/
NCy}(Cl)]2 (4), after a simple metathesis
reaction by treatment of 3 in acetone with aqueous
sodium chloride. In contrast to compound 1, the
dinuclear species 4 was obtained pure and complete
analytical data are given (see Section 4). The IR
spectrum showed the absence of the acetate bands and
n(CÄ
and the HCÄ
8.78, c. The oxidative adition reaction of N-(2-bromo-
benzylidene)cyclohexylamine, NCy,
2-BrC6H4C(H)Ä
with tris(dibenzylideneacetone)palladium(0) in benzene
gave the Pd(II) compound [Pd{C6H4C(H)ÄNCy}(Br)]2
/
N) stretch at 1638, a, 1635, b, and 1596, c, cmꢃ1
N resonance at d 8.66, a, and 8.54, b, and
/
the presence two n(PdÃ
/Cl) stretches at 316 and 247
cmꢃ1, consistent with an asymmetric Pd2Cl2 bridging
unit [25]. However, attempts to make compound 4 by
direct metallation of ligand a with palladium(II) chlo-
ride or Li2[PdCl4] failed, and only a residue of black
palladium metal was obtained. Reaction of 4 with
tertiary phosphines gave the cyclometallated complexes
/
/
(1), which was fully characterized. Although owing to its
poor solubility in the more common organic solvents the
final product was not obtained pure; we were able to
identify the corresponding signals in the 1H-NMR
spectrum (see Table 1). To fully assert this was
compound 1, we reacted the crude product with thallium
acetylacetonate which gave the very soluble species
[Pd{2-BrC6H3C(H)Ä
PEtPh2; 7: LꢁPMePh2). Compounds 5Á
stable solids which have been fully characterized by
elemental analysis (C, H, N) and by IR and 1H- and 31P-
NMR spectroscopy (see Section 4 and Table 1). In the
1H-NMR spectra the HCÄ
pling to the phosphorus nucleus with J(PH) ca. 8.5 Hz.
In the 31P{1H} spectra the resonance of the coordinated
phosphine was a singlet at d 39.1, 5; 36.9, 6; 24.4, 7; in
agreement with a phosphorus trans to nitrogen arrange-
/
NCy}(Cl)(L)] (5: Lꢁ
/
PPh3; 6: Lꢁ
/
/
/7 were air-
[Pd{C6H4C(H)Ä
/
NCy}(MeCOCHCOMe)] (2), as a yel-
low solid for which full 1H- and 13C-NMR were
obtained (see Section 4 and Table 1). The shift of the
/N resonance showed cou-
n(CÄ
/
N) stretch in the IR spectrum toward lower
wavenumbers, 1609 cmꢃ1, and the shift of the HCÄ
/
N
resonance to lower frequency in the 1H-NMR spectrum,
d 7.92, as compared to their values in the spectra of the
non-coordinated ligand, were in agreement with palla-
ment [26Á
In view of the peculiar behavior of ligand a, as
opposed to the Schiff base 2-ClC6H4C(H)Ä
NCH2CH2NMe2, where only oxidative addition was
possible, we tested other species with CÃBr bonds in the
C2 position in order to study their behavior towards
Pd(II) salts, namely 2-BrÃ4,5-(MeO)2C6H2C(H)Ä
NCH2CH2NMe2 (b), and 1,4-{2-BrÃ4,5-(MeO)2-
/28].
/
dium coordination to the nitrogen atom [20Á22]. Four
/
distinct resonances were assigned to the phenyl ring
protons, d 7.51 (H6), 7.23 (H3), 7.14 (H5) and 7.04
(H4), corroborating metallation of the aromatic ring at
the C2 position, with removal of the bromine atom. The
/
/
/
/

J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á
/248
241
Table 1
31P a- and 1H b-NMR data
c,d
Compound
31P
Aromatic
Others
1
7.51 [d, J(HH)ꢁ7.5, 1H, H6]
7.22 [dd, J(HH)ꢁ7.2, 1.9, 1H, H5]
7.03 [m, 2H, H3, H4]
7.88 [s, 1H, HCÄN]
2
7.51 [dd, J(HH)ꢁ7.5, 1.1, 1H, H6]
7.23 [dd, J(HH)ꢁ7.5, 1.5, 1H, H3]
7.14 [td, J(HH)ꢁ7.5, 1.5, 1H, H5]
7.04 [td, J(HH)ꢁ7.5, 1.1, 1H, H4]
7.92 [s, 1H, HCÄN]
5.36 [s, 1H, acac]
2.06 [s, 3H, Me]
1.99 [s, 3H, Me]
e
3
4
7.11 [dd, J(HH)ꢁ7.8, 1.1, 1H, H3]
6.99 [dd, J(HH)ꢁ7.8, 1.1, 1H, H5]
6.83 [t, J(HH)ꢁ7.8, 1H, H4]
7.32 [dd, J(HH)ꢁ7.2, 1.0, 1H, H3]
7.14 [dd, J(HH)ꢁ7.2, 1.0, 1H, H5]
7.14 [t, J(HH)ꢁ7.2, 1H, H4]
7.68 [d, 1H, HCÄN, 1.5 ]
2.16 [s, 6H, MeCOO]
e
8.17 [d, 1H, HCÄN, 1.1 ]
f
5
6
7
8
39.1s
36.9s
24.4s
6.98 [dd, J(HH)ꢁ6.5, 1.1, 1H, H3]
8.59 [d, 1H, HCÄN, 8.6 ]
6.30 [m, 2H, H4, H5]
f
6.97 [dd, J(HH)ꢁ6.8, 1.9, 1H, H3]
8.54 [d, 1H, HCÄN, 8.5 ]
6.39 [m, 2H, H4, H5]
6.99 [dd, J(HH)ꢁ7.8, 1.2, 1H, H3]
8.54 [dd, 1H, HCÄN, 8.5 , 1.2
f
e
]
6.34 [m, 2H, H4, H5]
7.27 [s, 1H, H6]
6.88 [s, 1H, H3]
7.92 [s, 1H, HCÄN]
3.97 [s, 3H, MeO]
3.86 [m, 2H, CH2]
3.84 [s, 3H, MeO]
2.97 [m, 2H, CH2]
2.75 [s, 6H, NMe2]
9
20.9s
17.3s
14.7s
7.04 [s, 1H, H6]
6.95 [s, 1H, H3]
7.61 [s, 1H, HCÄN]
3.94 [s, 3H, MeO]
3.90 [s, 3H, MeO]
3.82 [m, 2H, CH2]
2.66 [m, 2H, CH2]
2.36 [s, 6H, NMe2]
10
11
7.06 [s, 1H, H6]
6.90 [s, 1H, H3]
7.59 [s, 1H, HCÄN]
3.91 [s, 3H, MeO]
3.87 [s, 3H, MeO]
3.83 [m, 2H, CH2]
2.61 [m, 2H, CH2]
2.37 [s, 6H, NMe2]
7.09 [s, 1H, H6]
6.94 [s, 1H, H3]
7.64 [s, 1H, HCÄN]
3.94 [s, 3H, MeO]
3.90 [s, 3H, MeO]
3.96 [m, 2H, CH2]
2.62 [m, 2H, CH2]
2.39 [s, 6H, NMe2]
12
13
14
15
16
7.77 [s, 1H, H6]
7.00 [s, 1H, H3]
7.30 [s, 4H, C6H4]
8.77 [s, 1H, HCÄN]
4.53 [s, 3H, MeO]
4.49 [s, 3H, MeO]
18.0s
16.5s
13.2s
7.72 [s, 1H, H6]
7.00 [s, 1H, H3]
7.20 [s, 4H, C6H4]
8.72 [s, 1H, HCÄN]
3.94 [s, 3H, MeO]
3.89 [s, 3H, MeO]
7.70 [s, 1H, H6]
6.73 [s, 1H, H3]
7.31 [s, 4H, C6H4]
8.78 [s, 1H, HCÄN]
3.95 [s, 3H, MeO]
3.91 [s, 3H, MeO]
7.80 [s, 1H, H6]
6.75 [s, 1H, H3]
7.33 [s, 4H, C6H4]
8.80 [s, 1H, HCÄN]
3.99 [s, 3H, MeO]
3.94 [s, 3H, MeO]
7.49 [s, 1H, H6]
7.81 [s, 1H, HCÄN]

242
J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á248
/
Table 1 (Continued)
Compound
31P
Aromatic
Others
6.78 [s, 1H, H3]
3.95 [s, 3H, MeO]
3.85 [m, 2H, CH2]
3.80 [s, 3H, MeO]
2.93 [m, 2H, CH2]
2.70 [s, 6H, NMe2]
a
In CDCl3. Measured at 100.6 MHz (ca. 20 8C); chemical shifts (d) in ppm (90.1) to high frequency of 85% H3PO4.
b
c
d
e
f
In CDCl3, unless otherwise stated. Measured at 250 MHz (ca. 20 8C); chemical shifts (d) in ppm (90.01) to high frequency of SiMe4.
Coupling constants in Hz.
s, singlet; d, doublet; dd, doublet of doublets; t, triplet; td, triplet of doublets; m, multiplet.
J(HH5).
J(PH).
C6H2C(H)Ä
with palladium(II) chloride in boiling octane gave
[Pd{4,5-(MeO)2C6H2C(H)ÄNCH2CH2NMe2}(Cl)] (8),
and N](Cl)}2C6H4]2
/
N}2C6H4 (c). Thus, treatment of b and c
lower trans influence of the nitrogen atom as compared
to the phenyl carbon atom; and in 13Á15, the C(4)Ã
MeO resonance was not shifted towards lower frequency
as would be expected in the case of a trans PÃPdÃ
arrangement, due to the shielding effects of the phos-
phine phenyl rings [30]. In the 31P{1H} spectrum of 9Á
11 and 13Á15 the resonance of the coordinated phos-
phine was a singlet shifted to lower frequency ca. 20
ppm, as compared to the value found in compounds 5Á
7, in accordance with the assumption that a ligand of
greater trans influence shifts the resonance of the
phosphorus atoms trans to it to lower frequency [31].
These findings were in agreement with a phosphorus
trans to carbon arrangement, as opposed to the results
/
/
/
[1,4-{Pd[4,5-(MeO)2C6H2C(H)Ä
/
/
/
N
(12) [29], as air-stable solids, which were fully character-
1
ized (see Section 4 and Table 1). The H-NMR spectra
/
showed two singlet resonances at d 7.49, 6.78, 8, and
7.77, 7.00, 12, assigned to the H6 and H3 protons,
respectively; the NMe2 resonance in 8 was shifted to
higher frequency upon coordination of the amine
nitrogen atom to the metal. The 13C{1H}-NMR spectra
showed the shift of the C2 carbon resonance towards
higher frequency by ca. 19 ppm in both cases, in
accordance with metallation of the C2 atom, whereas
the C6 resonance was only slightly shifted by ca. 5, 8,
and 3, 12, ppm (see Section 4). Therefore, both ligands,
b and c, are bonded to the metal atom through the C2
/
/
shown for compounds 5Á/7 and to others observed
earlier, for which a trans PÃ
/
PdÃN geometry seems to
/
be the more common disposition for the entering
phosphine [26,28,32]. Although the novel term transfo-
bia has been introduced by Vicente et al. to describe the
restricted coordination of mutually trans phosphines
and phenyl carbon atoms [33,34], this is clearly not the
carbon, leaving the C(6)Ã
/
H bond unreacted; and ligand
8 is [C, N, N] terdentate. The different behavior of
ligands a and b, c could stem from steric hindrance due
to the C(5)Ã/MeO group, in b and c, which impedes
case for compounds 9Á
/
11 and 13Á15.
/
approach of the palladium atom, as we have observed
earlier [13]. Treatment of ligand b with tris(dibenzylide-
neacetone)palladium(0), in an oxidative addition reac-
2.2. Molecular structure of complex 2
tion,
gave
[Pd{4,5-(MeO)2C6H2C(H)Ä/NCH2CH2-
NMe2}(Br)] (16), in good yield, where metallation is
through the C(2) carbon atom as expected; the 1H-
NMR spectrum is similar to that for 8 (see Section 4).
Reaction of ligand c with Li2[PdCl4] or K2[PdCl4] also
produced 12. Treatment of 8 and 12 with tertiary
Suitable crystals of the title compound were grown by
slow evaporation of a dichloromethaneÁn-hexane solu-
/
tion of the complex. The numbering scheme is shown in
Fig. 1. Crystallographic data and selected bond lengths
and angles are listed in Tables 2 and 3. The crystal
structure consists of discrete dinuclear molecules sepa-
rated by normal van der Waals distances.
phosphines
C6H2C(H)Ä
(MeO)2C6H2C(H)Ä
13: LꢁPPh3; 10, 14: Lꢁ
gave
NCH2CH2NMe2}(Cl)(L)] and [1,4-{Pd[4,5-
N](Cl)(L)}2C6H4], respectively (9,
PEtPh2; 11, 15: LꢁPMePh2),
compounds
[Pd{4,5-(MeO)2-
/
/
The coordination sphere around the palladium atom
/
/
/
consists of an ortho carbon of the phenyl ring, the CÄ
/N
as air-stable solids which were fully characterized (see
1
Section 4 and Table 1). The H-NMR spectra showed
nitrogen atom, and two oxygen atoms from the 2,4-
pentanedionate group. The angles between adjacent
atoms in the coordination sphere are close to the
the HCÄ
phosphorus nucleus pointing towards a trans PÃ
disposition, as opposed to compounds 5Á7 where a
trans PÃPdÃN geometry was observed. This was con-
firmed by the higher n(PdÃCl) values found for 9Á11
and 13Á15, with respect to 5Á7, in agreement with the
/
N and H3 resonances were not coupled to the
/
PdÃ/C
expected value of 908, in the range 81.30(14)Á
94.17(11)8, with the more noticeable distortions in the
N(1) 81.30(14)8 consequent
/
/
/
/
‘bite’ angle C(1)Ã
/
Pd(1)Ã
/
/
/
upon chelation. The sum of angles at palladium is
/
/
360.18. This is reflected in the somewhat large value of

J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á
/248
243
Table 3
˚
Selected bond lengths (A) and angles (8) for complex 2
Bond lengths
Pd(1)ÃC(1)
Pd(1)ÃO(1)
C(1)ÃC(6)
N(1)ÃC(7)
O(2)ÃC(15)
1.967(4)
2.013(2)
1.408(5)
1.287(5)
1.287(5)
Pd(1)ÃN(1)
Pd(1)ÃO(2)
C(6)ÃC(7)
O(1)ÃC(17)
2.022(3)
2.077(3)
1.451(5)
1.297(5)
Bond angles
C(1)ÃPd(1)ÃN(1)
O(1)ÃPd(1)ÃN(1)
O(1)ÃPd(1)ÃO(2)
C(6)ÃC(1)ÃPd(1)
N(1)ÃC(7)ÃC(6)
81.30(14) C(1)ÃPd(1)ÃO(1)
173.06(13) C(1)ÃPd(1)ÃO(2)
92.22(11) N(1)ÃPd(1)ÃO(2)
92.40(14)
175.11(13)
94.17(11)
113.8(3)
113.4(3)
C(1)ÃC(6)ÃC(7)
C(7)ÃN(1)ÃPd(1)
116.5(3)
114.9(2)
Fig. 1. Molecular structure of compound [Pd{C6H4C(H)ÄNCy}(Me-
COCHCOMe)] (2), with labelling scheme (30% probability level).
Hydrogen atoms have been omitted for clarity.
/
is put forward by the lengthening of the palladiumÃ
/
oxygen distances trans to carbon [Pd(1)ÃO(1)ꢁ
/
/
˚
O(2)ꢁ2.013(2) A].
The aromatic (plane 1) and 2,4-pentanedionate (plane
2.077(3), Pd(1)Ã
/
/
2) rings are planar (mean deviation from the least-
Table 2
Crystallographic data for complex 2
˚
squares plane 0.0025 and 0.0143 A, respectively) and
almost coplanar with the five-membered cyclometal-
˚
lated ring (plane 3; mean deviation 0.0086 A) (angles
Chemical formula
Formula weight
T (8C)
C18H23NO2Pd
391.77
between planes: 1/2ꢁ6.2, 1/3ꢁ2.5, 2/3ꢁ4.98). The
/
/
/
293(2)
0.71073
˚
geometry around the palladium atom is also planar
˚
(mean deviation of 0.0333 A).
l (A)
Crystal system
Space group
Orthorhombic
P212121
˚
a (A)
8.2710(10)
10.4090(10)
19.870(2)
1710.7(3)
4
˚
b (A)
˚
3. Conclusions
c (A)
3
V (A )
˚
Z
The three ligands, all possessing a bromine atom
bonded to the C2 phenyl carbon, seem to show different
behavior when treated with Pd(0) or Pd(II) reagents.
Ligands a and b produce the expected products when
treated with Pd(0) in an oxidative addition reaction.
However, ligands a, b and c react differently towards
Pd(II) salts. Thus, whilst a is metallated at the C6
carbon atom, b and c are metallated at the C2 carbon,
with loss of the bromine atom, possibly due to steric
hindrance of a methoxy group. Another interesting
feature of the compounds stems from the comparison
of the coordination mode of the phosphine ligand. In
m (mmꢃ1
)
1.091
3183
Collected reflections
Unique reflections
2924 [Rintꢁ0.0201]
0.0337
0.0896
a
R1
b
wR2
Absolute structure parameter
Largest difference peak and hole (e A
0.04(5)
1.045 and ꢃ1.430
ꢃ3
˚
)
a
R1ꢁa jjFojꢃjFcjj/a jFoj, [F ꢀ4s(F)].
wR2 ꢁ[a [w(Fo2 ꢃFc2)2=a w(Fo2)2]1=2; all data.
b
/
the C(2)Ã
ladiumÃcarbon bond length [Pd(1)Ã
is shorter than the predicted value of 2.081 A, based on
the sum of covalent radii for carbon(sp2) and palladium,
/
C(1)ÃPd(1) angle of 128.2(3)8. The pal-
/
˚
C(1)ꢁ1.967(4) A],
/
/
/
compounds 5Á
in accordance with the transfobia effect, whereas for
compounds 9Á11 and 13Á P disposi-
/
7, a trans-NÃ
/
PdÃ/P geometry was found
˚
/
/
15, a trans-CÃ
/
PdÃ
/
˚
0.771 and 1.31 A, respectively, suggesting some degree
tion was observed.
of multiple-bond character in the PdÃ
has been observed before [16,19,35]. The palladiumÃ
nitrogen bond length [Pd(1)Ã
good agreement with the predicted value of 2.01 A,
based on the sum of covalent radii for nitrogen(sp2) and
˚
palladium, 0.701 and 1.31 A, respectively [36].
/
C(aryl) linkage, as
/
˚
N(1)ꢁ2.022(3) A is in
/
/
4. Experimental
˚
4.1. Materials and instrumentation
The PdÃO distances [Pd(1)ÃO(1) 2.013(2) and Pd(1)Ã
O(2) 2.077(3) A] are within the expected values for PdÃ
O single-bonds. The stronger trans influence of the
phenyl carbon as compared to the imine nitrogen atom,
/
/
/
All reactions were carried out in an atmosphere of dry
Ar. Solvents were purified by standard methods [37].
Chemicals were reagent grade. Pd2(dba)3 and the
phosphines PPh3, PEtPh2 and PMePPh2 were purchased
˚
/

244
J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á248
/
from Aldrich Chemie. Microanalyses were carried out at
the Servicio de Ana´lisis Elemental at the University of
vacuo, and recrystallized from CH2Cl2ÁC6H14 to give
the required complex as a yellow solid in 89% yield.
Anal. Found: C, 55.1; H, 5.6; N, 3.4. C18H23NO2Pd
/
Santiago using a CarloÁErba Elemental Analyser,
/
Model 1108. NMR spectra were obtained as CDCl3
solutions and referenced to SiMe4 (1H, 13C{1H}) or 85%
H3PO4 (31P{1H}) and were recorded on Bruker WM250,
AMX-300 and AC-200 spectrometers. All chemical
shifts were reported downfield from standards.
requires: C, 55.2; H, 5.9; N, 3.6%. IR: n(CÄ
/
N) 1609s,
O) 1580s, 1515s cmꢃ1 13C{1H}-NMR data, phen-
n(CÃ
/
.
yl: 157.0 (C2), 146.1 (C1), 128.7, 129.6, 130.5, 131.1 (C3,
C4, C5, C6). Cy group: 25.9 (C9, C11), 26.4 (C10), 32.7
(C8, C12), 66.9 (C7). Others: 171.0 (CÄ
/
N), acac: 28.0
The syntheses of the Schiff bases 2-BrC6H4C(H)Ä
NCy (a), 2-BrÃ4,5-(MeO)2C6H2C(H)ÄNCH2CH2NMe2
(b), and 1,4-{2-BrÃ4,5-(MeO)2C6H2C(H)ÄN}2C6H4 (c),
/
(Me), 28.4 (Me), 100.5 (CH).
/
/
/
/
were performed by heating a CHCl3 solution of the
appropriate quantities of 2-bromobenzaldehyde or 2-
bromo-4,5-dimethoxybenzaldehyde, and cyclohexyla-
mine, N,N-dimethylethylendiamine or 1,4-phenylene-
4.4. Synthesis of [Pd{2-BrC6H3C(H)Ä
/
NCy}(O2CMe)]2 (3)
A mixture of 2-BrC6H4C(H)Ä/NCy (300 mg, 1.13
diamine, as appropriate, in a DeanÁ
under reflux. The ligands were characterized by their IR
and NMR spectra. IR spectra: a, n(CÄN), 1638s; b,
n(CÄN), 1635s; c: n(CÄ
N), 1596m cmꢃ1 1H-NMR
spectra: a, 8.66 [s, 1H, HCÄN], 8.01 [dd, J(HH)ꢁ7.5,
1.9, 1H, H6], 7.55 [dd, J(HH)ꢁ8.2, 1.5, 1H, H3], 7.29
[m, 2H, H3, H4]; b, 8.54 [s, 1H, HCÄN], 7.53 [s, 1H, H2],
6.97 [s, 1H, H5], 3.90 [s, 3H, MeO], 3.88 [s, 3H, MeO],
3.75 [m, Nꢁ11, 2H, N(CH2)2N], 2.65 [m, Nꢁ11, 2H,
N],
/Stark apparatus
mmol) and palladium(II) acetate (230 mg, 1.02 mmol)
in glacial AcOH (40 cm3) was refluxed under dry
dinitrogen for 3 h. After cooling the mixture to r.t. the
AcOH was removed under vacuum. The residue was
treated with water and extracted with CH2Cl2. The
combined extracts were dried over anhydrous Na2SO4,
filtered and concentrated in vacuo to give orange oil.
This was chromatographed on a column packed with
/
/
/
.
/
/
/
/
/
/
silica gel. Elution with CH2Cl2Á
/
EtOH (1%) removed
N(CH2)2N], 2.31 [s, 6H, NMe2]; c, 8.78 [s, 1H, HCÄ
/
unchanged starting material. Elution with CH2Cl2Á
/
7.77 [s, 1H, H6], 7.30 [s, 4H, C6H4], 7.05 [s, 1H, H3]; 3.98
[s, 3H, MeO]; 3.94 [s, 3H, MeO].
EtOH (4%) afforded the final product as an orange
powder after concentration in 67% yield. Anal. Found:
C, 41.7; H, 4.1; N, 3.3. C30H36Br2N2O4Pd2 requires: C,
13C{1H}-NMR spectra: a, phenyl: 125.3 (C1), 135.4
(C2), 128.0, 129.3, 131.9, 133.3 (C3, C4, C5, C6). Cy
group: 25.1 (C9, C11), 26.0 (C10), 34.8 (C8, C12), 70.3
41.8; H, 4.2; N, 3.3%. IR: n(CÄ
/N) 1609s, nas(COO)
1581s, ns(COO) 1406m cmꢃ1
.
(C7). Others: 158.1 (CÄ
(C4), 127.3 (C2), 116.9 (C1), 115.3 (C6), 110.4 (C3).
N), 60.4, 59.0 (MeO), 56.5, 56.4
/
N). b, phenyl: 151.9 (C5), 149.0
Others: 160.9 (CÄ
/
4.5. Synthesis of [Pd{2-BrC6H3C(H)Ä
/
NCy}(Cl)]2 (4)
(NCH2), 46.1 (Me2). c, phenyl: 152.3 (C5), 148.3 (C4),
131.5 (C2), 121.6 (C6H4), 110.7 (C1), 117.3 (C8), 112.9
An aq. solution of NaCl (ca. 10ꢃ2 M) was added
dropwise to a solution of 3 (290 mg, 0.36 mmol) in
C3H6O. The product immediately precipitated out as a
yellow solid. After stirring for 16 h the solid was filtered
off and dried in vacuo. Yield: 0.087 g, 89%. Anal.
Found: C, 38.3; H, 3.5; N, 3.2. C26H30Br2Cl2N2Pd2
(C6), 110.2 (C3). Others: 149.3 (CÄ
4.2. Synthesis of [Pd{C6H4C(H)ÄNCy}(Br)]2 (1)
2-BrC6H4C(H)ÄNCy (116 mg, 437 mmol) and tris(di-
/
N), 56.5 (MeO).
/
/
benzylideneacetone)dipalladium(0) (200 mg, 218 mmol)
were added to 25 cm3 of dry C6H6 to give a dark-red
solution which was heated under reflux for 4 h, after
which a dark suspension resulted. After cooling to room
temperature (r.t.) the product was filtered off to give a
solid slightly unpurified with Pd(0). Due to its poor
solubility the crude product was used without further
requires: C, 38.4; H, 3.7; N, 3.4%. IR: n(CÄ
/
N) 1607s,
n(PdÃ
/
Cl) 316w, 247w cmꢃ1
.
4.6. Synthesis of [Pd{2-BrC6H3C(H)Ä
/
NCy}(PPh3)]
(5)
purification. IR (KBr): n(CÄ
/
N), 1608s cmꢃ1
.
To a suspension of the cyclometallated halide-bridged
complex 4 (100 mg, 0.12 mmol) in 15 cm3 of CH2Cl2,
PPh3 (60 mg, 0.24 mmol) was added. The mixture was
stirred for 8 h, after which the white solid formed was
4.3. Synthesis of [Pd{C6H4C(H)Ä
/NCy}(acac-O,O)]
(2)
To a suspension of 1 (40 mg, 0.05 mmol) in CHCl3 (20
cm3), thallium-2,4-pentanedionate (33 mg, 0.11 mmol)
was added and the mixture stirred at r.t. for 4 h. The
resulting mixture was filtered over celite, concentrated in
filtered off and recrystallized from CH2Cl2ÁC6H14.
/
Yield: 70%. Anal. Found: C, 55.3; H, 4.4; N, 2.0.
C31H30BrClNPPd requires: C, 55.6; H, 4.5; N, 2.1%. IR:
n(CÄ
/
N) 1617m, n(PdÃ
/
Cl) 310w cmꢃ1 (Scheme 1).

J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á
/248
245
was heated to reflux for 10 h. After cooling to r.t. the
solution was filtered through celite to remove the small
amount of black Pd formed. The solution was concen-
trated until a yellow crystalline precipitate appeared.
The solid was filtered off and washed with n-C6H14.
Yield: 63%. Anal. Found: C, 41.2; H, 5.0; N, 7.3.
C13H19ClN2O2Pd requires: C, 41.4; H, 5.1; N, 7.4%. IR:
n(CÄ
spectra, phenyl: 152.0 (C5), 150.3 (C4), 149.2 (C2), 143.8
N), 64.7
/
N) 1607m, n(PdÃ
/
Cl) 339w cmꢃ1 13C{1H}-NMR
.
(C1), 121.4 (C6), 112.6 (C3). Others: 174.5 (CÄ
/
(NCH2), 56.4, 56.1 (MeO), 55.4 (CH2NMe2), 49.1, 48.7
(Me2).
4.10. Synthesis of [Pd{4,5-(MeO)2C6H2C(H)Ä
/
NCH2CH2NMe2}(Cl)(PPh3)] (9)
PPh3 (30 mg, 0.12 mmol) was added to a solution of 8
(40 mg, 0.12 mmol) in C3H6O (15 cm3). The mixture was
stirred for 6 h, the solvent removed and the product
recrystallized from CH2Cl2ÁC6H14 to give the desired
/
complex as an orange solid. Yield: 69%. Anal. Found:
C, 58.0; H, 5.5; N, 4.3. C31H34ClN2O2PPd requires: C,
58.2; H, 5.4; N, 4.4%. IR: n(CÄ
/
N) 1591m, n(PdÃ
/Cl)
332w cmꢃ1 (Scheme 2).
Compounds 10 and 11 were obtained following a
procedure similar to 9.
Scheme 1. (i) [Pd2(dba)3]/benzene, reflux; (ii) Tl(acac)/CHCl3, stir; (iii)
PdAcO)2/AcOH, reflux; (iv) NaCl/Me2CO/water; (v) L/acetone, stir
[Lꢁ
/
PPh3 (5); PEtPh2 (6); PMePh2 (7)]; (vi) PdCl2/octane, reflux;
Li2[PdCl4]/MeOH/r.t.
4.11. Synthesis of [Pd{4,5-(MeO)2C6H2C(H)Ä
/
NCH2CH2NMe2}(Cl)(PEtPh2)] (10)
4.7. Synthesis of [Pd{2-BrC6H3C(H)Ä
NCy}(PEtPh2)] (6)
/
Yield: 82%. Anal. Found: C, 54.7; H, 5.8; N, 4.6.
C27H34ClN2O2PPd requires: C, 54.8; H, 5.8; N, 4.7%.
To a suspension of the cyclometallated halide-bridged
complex 4 (20 mg, 0.03 mmol) in 25 cm3 of dry THF,
PEtPh2 (10 mg, 0.05 mmol) was added and the mixture
was refluxed under nitrogen for 6 h. Removal of the
solvent in vacuo gave a solid which was recrystallized
IR: n(CÄ
/
N) 1591m, n(PdÃ
/
Cl) 341w cmꢃ1
.
4.12. Synthesis of [Pd{4,5-(MeO)2C6H2C(H)Ä
/
NCH2CH2NMe2}(Cl)(PMePh2)] (11)
from CH2Cl2Á
H, 4.8; N, 2.3. C27H30BrClNPPd requires: C, 52.2; H,
Cl) 308w cmꢃ1
.
Compound 7 was obtained following a similar
procedure.
/
C6H14. Yield: 80%. Anal. Found: C, 52.1;
Yield: 74%. Anal. Found: C, 54.0; H, 5.8; N, 4.6.
C26H34ClN2O2PPd requires: C, 53.9; H, 5.9; N, 4.8%.
4.9; N, 2.3%. IR: n(CÄ
/
N) 1628m, n(PdÃ
/
IR: n(CÄ
/
N) 1589m, n(PdÃ
/
Cl) 333w cmꢃ1
.
4.13. Synthesis of [1,4-{Pd[4,5-(MeO)2C6H2C(H)Ä
/
N](Cl)}2C6H4}]2 (12)
4.8. Synthesis of [Pd{2-BrC6H3C(H)Ä
/
NCy}(PMePh2)] (7)
4.13.1. Method 1
To a solution of 1,4-{2-BrÃ
/
4,5-(MeO)2C6H2C(H)Ä
/
Yield: 70%. Anal. Found: C, 51.3; H, 4.6; N, 5.5.
C26H28BrClNPPd requires: C, 51.4; H, 4.7; N, 2.3%. IR:
N}2C6H4 (520 mg, 1.93 mmol) in dry n-octane (40
cm3), palladium(II) chloride (300 mg, 1.69 mmol) was
added under Ar. The mixture was heated to reflux for 10
h. After cooling to r.t. the solution was filtered through
celite to remove the small amount of black Pd formed.
The solution was concentrated until a yellow solid
appeared, which was filtered off and washed with n-
C6H14. Yield: 79%. Anal. Found: C, 41.8; H, 3.1; N, 4.0.
C48H44Cl4N4O8Pd4 requires: C, 42.0; H, 3.2; N, 4.1%.
n(CÄ
/
N) 1620m, n(PdÃ
/
Cl) 300w cmꢃ1
.
4.9. Synthesis of [Pd{4,5-(MeO)2C6H2C(H)Ä
/
NCH2CH2NMe2}(Cl)] (8)
To a solution of 3,4-(MeO)2C6H2C(H)Ä
/
NCy (200
mg, 0.63 mmol) in dry n-octane (40 cm3) palladium(II)
chloride (101 mg, 0.57 mmol) was added. The mixture
IR: n(CÄ
/
N) 1589m, n(PdÃ
/
Cl) 339, 267w cmꢃ1
.

246
J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á248
/
Scheme 2. (i) PdCl2/octane, reflux; (ii) L/acetone, stir [LꢁPPh3 (9); PEtPh2 (10); PMePh2 (11)]; (iii) [Pd2(dba)3]/benzene, reflux.
/
13C{1H}-NMR spectra, phenyl: 152.7 (C5), 150.3 (C2),
149.2 (C4), 127.6 (C1), 122.5 (C6H4), 118.5 (C8), 115.8
Compounds 14 and 15 were obtained following a
procedure similar to 13.
(C6), 110.9 (C3). Others: 158.7 (CÄ
/
N), 56.7 (MeO).
4.15. Synthesis of [1,4-{Pd[4,5-(MeO)2C6H2C(H)Ä
/
N](Cl)(PEtPh2)}2C6H4] (14)
4.13.2. Method 2
Palladium(II) chloride (200 mg, 1.13 mmol) and LiCl
(100 mg, 2.36 mmol) were added in MeOH and the
resulting mixture was stirred until a dark red color
appeared. Then AcONa (500 mg, 6.1 mmol) and 1,4-{2-
Yield: 81%. Anal. Found: C, 55.9; H, 4.5; N, 2.4.
C52H52Cl2N2O4P2Pd2 requires: C, 56.0; H, 4.7; N, 2.5%.
IR: n(CÄ
/
N) 1590m, n(PdÃ
/
Cl) 324w cmꢃ1
.
BrÃ
/
4,5-(MeO)2C6H2C(H)Ä
/
N}2C6H4 (350 mg, 0.87
4.16. Synthesis of [1,4-{Pd[4,5-(MeO)2C6H2C(H)Ä
/
mmol) were added. The resulting mixture was stirred
for 48 h, after which the precipitate formed was filtered
off and washed with MeOH. The final solid was boiled
in EtOH, filtered hot, cooled to r.t. and separated and
dried in vacuo.
N](Cl)(PMePh2)}2C6H4] (15)
Yield: 76%. Anal. Found: C, 55.2; H, 4.3; N, 2.5.
C50H48Cl2N2O4P2Pd2 requires: C, 55.3; H, 4.5; N, 2.6%.
IR: n(CÄ
/
N) 1590m, n(PdÃ
/
Cl) 332w cmꢃ1
.
Compound 16 was obtained following a similar
procedure to that described for 2.
4.13.3. Method 3
To a mixture of water (6 cm3)Á
K2[PdCl4] (200 mg, 0.61 mmol) and {2-BrÃ
(MeO)2C6H2C(H)Ä
were added. The mixture was stirred for 24 h. The
resulting solid was filtered off, washed with absolute
EtOH and dried in vacuo.
/
EtOH (40 cm3)
4,5-
N}2C6H4 (340 mg, 0.85 mmol)
/
4.17. Synthesis of [Pd{4,5-(MeO)2C6H2C(H)Ä
/
/
NCH2CH2NMe2}(Br)] (16)
Yield: 63%. Anal. Found: C, 37.5; H, 4.6; N, 6.7.
C13H19BrN2O2Pd requires: C, 37.0; H, 4.5; N, 6.6%. IR:
n(CÄ
152.1 (C5), 150.6 (C4), 146.0 (C2), 141.1 (C1), 120.7
N), 64.1 (NCH2),
/
N) 1619m cmꢃ1 13C{1H}-NMR spectra, phenyl:
.
4.14. Synthesis of [1,4-{Pd[4,5-(MeO)2C6H2C(H)Ä
N](Cl)(PPh3)}2C6H4] (13)
/
(C6), 111.3 (C3). Others: 171.6 (CÄ
/
56.6, 56.4 (MeO); 53.2 (CH2NMe2), 48.8, 48.4 (Me2).
PPh3 (150 mg, 0.58 mmol) was added to a solution of
12 (200 mg, 0.15 mmol) in C3H6O (15 cm3). The mixture
was stirred for 8 h, the solvent removed and the product
4.18. X-ray crystallographic study
recrystallized from CH2Cl2Á/C6H14 to give the desired
Three-dimensional, r.t. X-ray data were collected in
complex as a pale yellow solid. Yield: 83%. Anal.
Found: C, 59.4; H, 4.4; N, 2.2. C60H52Cl2N2O4P2Pd2
the u range 2.67Á
diffractometer by the v Á
/
30.408 in a EnrafÁ
/
Nonius CAD4
/2u scan method. Of the 3183
requires: C, 59.5; H, 4.3; N, 2.3%. IR: n(CÄ
/N) 1591m,
reflections measured, all of which were corrected from
Lp effects and for absorption by semi-empirical methods
n(PdÃ
/
Cl) 320w cmꢃ1 (Scheme 3).

J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á
/248
247
Scheme 3. (i) PdCl2/octane, reflux; Li2[PdCl4]/MeOH/r.t.; K2[PdCl4]/MeOH/r.t.; (ii) L/acetone, stir [LꢁPPh3 (13); PEtPh2 (14); PMePh2 (15)].
/
[4] L. Botella, C. Najera, Angew. Chem. Int. Ed. Engl. 41 (2002) 179.
[5] A.D. Ryabov, Synthesis 3 (1985) 233.
(minimum and maximum transmission coefficients
0.677 and 0.719), 2631 independent reflections exceeded
[6] L. Main, B.K. Nicholson, Adv. Met. Org. Chem. 3 (1994) 1.
[7] J. Spencer, M. Pfeffer, Adv. Met.-Org. Chem. 6 (1998) 103.
[8] S.B. Wild, Coord. Chem. Rev. 166 (1997) 291.
the significance level jFj/sjFjꢀ
/
2.0. The structure was
solved by direct methods and refined by full-matrix
least-squares on F2. Hydrogen atoms were included in
calculated positions and refined in riding mode. Refine-
[9] J. Albert, J.M. Cadena, J.R. Granell, X. Solans, M. Font-Bardia,
Tetrahedron: Asymmetry 11 (2000) 1943.
[10] C. Navarro-Ranninger, I. Lopez-Solera, V.M. Gonzalez, J.M.
Perez, A. Alvarez-Valdes, A. Martin, P. Raithby, J.R. Masaguer,
C. Alonso, Inorg. Chem. 35 (1996) 5181.
ment converged at a final R1ꢁ
/
0.0337 (wR2ꢁ0.0896 for
/
2924 unique data, 202 parameters) with allowance for
thermal anisotropy of all non-hydrogen atoms. The
structure solution and refinement were carried out using
the program package SHELX-97 [38].
[11] A.G. Quiroga, J.M. Perez, I. Lopez-Solera, J.R. Masaguer, A.
Luque, P. Roman, A. Edwards, C. Alonso, C. Navarro-Rannin-
ger, J. Med. Chem. 41 (1998) 1399.
[12] B. Teijido, A. Ferna´ndez, M. Lo´pez-Torres, S. Castro-Juiz, A.
Sua´rez, J.M. Ortigueira, J.M. Vila, J.J. Ferna´ndez, J. Organomet.
Chem. 598 (2000) 71.
5. Supplementary data
[13] B. Teijido, A. Ferna´ndez, M. Lo´pez-Torres, A. Sua´rez, J.M. Vila,
R. Mosteiro, J.J. Ferna´ndez, Organometallics 21 (2002) 1304.
[14] J.M. Vila, E. Gayoso, M.T. Pereira, M. Marino, J. Mart´ınez, J.J.
˜
Full details of data collection and structure refine-
ment have been deposited with the Cambridge Crystal-
lographic Data Centre, CCDC no. 187370 for
compound 2. Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Ferna´ndez, A. Ferna´ndez, M. Lo´pez-Torres, J. Organomet.
Chem. 637 (2001) 577.
[15] M. Lousame, A. Ferna´ndez, M. Lo´pez-Torres, D. Va´zquez-
Garc´ıa, J.M. Vila, A. Sua´rez, J.M. Ortigueira, J.J. Ferna´ndez,
Eur. J. Inorg. Chem. (2000) 2055.
Union Road, Cambridge CB2 1EZ, UK (Fax: ꢂ44-
1223-336033); e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
/
[16] A. Ferna´ndez, P. Ur´ıa, J.J. Ferna´ndez, M. Lo´pez-Torres, A.
Sua´rez, D. Va´zquez-Garc´ıa, M.T. Pereira, J.M. Vila, J. Organo-
met. Chem. 620 (2001) 8.
[17] A. Ferna´ndez, D. Va´zquez-Garc´ıa, J.J. Ferna´ndez, M. Lo´pez-
Torres, A. Sua´rez, S. Castro-Juiz, J.M. Vila, New J. Chem. 26
(2002) 398.
Acknowledgements
[18] A. Amoedo, M. Grana, J. Mart´ınez, M.T. Pereira, M. Lo´pez-
˜
Torres, A. Ferna´ndez, J.J. Ferna´ndez, J.M. Vila, Eur. J. Inorg.
Chem. 613 (2002) 613.
We thank the Ministerio de Educacio´n y Cultura
(Proyecto PB98-0638-C02-01/02) for financial support.
[19] J.M. Vila, M. Gayoso, M. Teresa Pereira, M. Lo´pez Torres, J.J.
Ferna´ndez, A. Ferna´ndez, J.M. Ortigueira, J. Organomet. Chem.
532 (1997) 171.
[20] H. Onoue, I. Moritani, J. Organomet. Chem. 43 (1972) 431.
[21] H. Onoue, K. Minami, K. Nakagawa, Bull. Chem. Soc. Jpn. 43
(1970) 3480.
References
[22] Y. Ustynyuk, V.A. Chertov, J.V. Barinov, J. Organomet. Chem.
29 (1971) C53.
[1] I. Omae, Organometallic Intramolecular-Coordination Com-
pounds, in Journal of Organometallic Chemistry Library, Else-
vier, Amterdam, 1986.
[23] J. Albert, M. Go´mez, J. Franell, J. Sales, Organometallics 9 (1990)
1405.
[2] O.A. Dunina, V.M. Zalewskaya, V.M. Potapov, Russ. Chem.
Rev. 57 (1988) 434.
[24] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 5th ed., John Wiley & Sons, New
York, 1997.
[3] J. Dupont, M. Pfeffer, J. Spencer, Eur. J. Inorg. Chem. (2001)
1917.

248
J.M. Vila et al. / Journal of Organometallic Chemistry 663 (2002) 239Á248
/
[25] M.T. Pereira, J.M. Vila, E. Gayoso, M. Gayoso, W. Hiller, J.
Strahle, J. Coord. Chem. 18 (1988) 245.
¨
[32] J. Albert, R. Bosque, J.M. Cadena, S. Delgado, J. Granell, J.
Organomet. Chem. 634 (2001) 83.
[26] R. Bosque, J. Granell, J. Sales, M. Fon-Bardia´, X. Solans, J.
Organomet. Chem. 453 (1994) 147.
[33] J. Vicente, A. Arcas, D. Bautista, P.G. Jones, Organometallics 16
(1997) 2127.
[27] J.M. Vila, M. Gayoso, M.T. Pereira, A. Romar, J.J. Ferna´ndez,
M. Thornton-Pett, J. Organomet. Chem. 401 (1991) 385.
[28] R. Bosque, J. Granell, J. Sales, M. Fon-Bardia´, X. Solans,
Organometallics 14 (1995) 1393.
[34] J. Vicente, J. Abad, A.D. Frankland, M.C. Ram´ırez de Arellano,
Chem. Eur. J. 5 (1999) 3066.
[35] J.M. Vila, M.T. Pereira, J.M. Ortigueira, D. Lata, M. Lo´pez-
Torres, J.J. Ferna´ndez, A. Ferna´ndez, H. Adams, J. Organomet.
Chem. 566 (1998) 93.
[29] We suggest a tetranuclear formulation instead of a polynuclear
structure, in view of the results obtained by us earlier in related
species; see J.M. Vila, et al., J. Organomet. Chem. 426 (1992) 267.
[30] J.M. Vila, M. Gayoso, M.T. Pereira, M. Lo´pez-Torres, G.
Alonso, J.J. Ferna´ndez, J. Organomet. Chem. 445 (1993) 287.
[31] P.S. Pregosin, R.W. Kuntz, in: P. Diehl, E. Fluck, R. Kosfeld
(Eds.), 31P and 13C NMR of Transition Metal Phosphine
Complexes NMR Basic Principles and Progress, vol. 16, Springer,
Berlin, 1979.
[36] L. Pauling, The Nature of the Chemical Bond, 3rd ed., Cornell
University Press, New York, 1960.
[37] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory
Chemicals, 4th ed., Butterwort-Heinemann, 1996.
[38] G.M Sheldrick, SHELX-97, An Integrated System for Solving and
Refining Crystal Structures from Diffraction Data, University of
Gottingen, Germany, 1997.
¨