The first crystal and molecular structure of a syn-acetato-bridged dinuclear cyclometallated complex [Pd{2,3,4-(MeO)3C6HC(H)=NCH2 CH2OH}(μ-OAc)]2

Article abstract of DOI:10.1002/1099-0682(200209)2002:9<2389::AID-EJIC2389>3.0.CO;2-M

Treatment of the Schiff base ligands 2,3,4-(MeO)₃C₆H₂C(H)=NR (R = CH₂CH₂OH, 1; R = Me, 17; R = Et, 18; R = Pr, 19; R = tBu, 20) with palladium(II) acetate in toluene gave the dinuclear cyclometallated complexes [Pd{2,3,4-(MeO)₃C₆HC(H)=NR} (μ-O₂CMe}]₂ (R = CH₂CH₂OH, 2; R = Me, 21; R = Et, 22; R = Pr, 23; R = tBu, 24), with the ligand bonded to the palladium atom through the imine nitrogen and the C6 carbon atoms. The ¹H and ¹³C{¹H} NMR spectra of the complexes showed the presence of the anti and syn isomers in solution. The anti/syn ratio varies with the solvent and the nature of the imine nitrogen substituent R. Complex 24 with the bulky tBu group showed a 28:1 ratio in chloroform whilst the less bulky substituted complexes showed lower ratios. The X-ray crystal structure of the syn isomer of complex 2 is described. Reaction of the acetato-bridged complex 2 with PPh₃ gave the mononuclear complex 4, in a bridge-splitting reaction. Reaction of 2 with the diphosphanes dppm, dppp and dppb in a 1:1 molar ratio gave the dinuclear cyclometallated complexes 5, 6 and 7, respectively. Treatment of 2 with an aqueous solution of sodium chloride gave the chloro-bridged complex 3. Treatment of the cyclometallated chloro-bridged complex 3 with PPh₃ in acetone yielded the mononuclear complex 8, and reaction of 3 with silver triflate gave the cyclometallated complex 9, with the palladium atom bonded to four different atoms C, N, O and P. Treatment of 3 with the tertiary diphosphanes dppp, dppb and dppf, in a 1:1 molar ratio gave the dinuclear complexes 10, 11 and 12, respectively, with terminal chloride ligands. However, reaction of 3 with the small "bite" diphosphane dppm gave 13, with a bridging chloride ligand. Reaction of 11 with silver triflate in acetone gave the new dinuclear complex 14, with the Schiff base ligand as [C,N,O] terdentate. Reaction of 3 with the diphosphane dppe in a 1:2 molar ratio, and silver perchlorate, gave the mononuclear complex 15. Treatment of 3 with the triphosphane bis(2-diphenylphosphanylethyl)phenylphosphane in a 1:2 molar ratio, followed by treatment with sodium perchlorate, gave 16, in which the palladium atom was bonded to the triphosphane through the three phosphorus atoms. The X-ray crystal structures of complexes 8, 9, 15 and 16 are also reported. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200209)2002:9<2389::AID-EJIC2389>3.0.CO;2-M

FULL PAPER
The First Crystal and Molecular Structure of a syn-Acetato-Bridged Dinuclear
Cyclometallated Complex [Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}-
(µ-OAc)]2
[a]
[a]
[a]
´
´
´
´
´
Jesus J. Fernandez,
Alberto Fernandez,*
Digna Vazquez-Garcıa,
[a]
[a]
[a]
[b]
´
´
´
Margarita Lopez-Torres, Antonio Suarez, Samuel Castro-Juiz, and Jose M. Vila*
Keywords: C-H activation / Cyclometallation / P ligands / Schiff bases / Palladium
Treatment of the Schiff base ligands 2,3,4-(MeO)3C6H2C(H)=
NR (R = CH2CH2OH, 1; R = Me, 17; R = Et, 18; R = Pr, 19;
R = tBu, 20) with palladium(II) acetate in toluene gave the
bridged complex 3 with PPh3 in acetone yielded the mononu-
clear complex 8, and reaction of 3 with silver triflate gave the
cyclometallated complex 9, with the palladium atom bonded
to four different atoms C, N, O and P. Treatment of 3 with the
tertiary diphosphanes dppp, dppb and dppf, in a 1:1 molar
ratio gave the dinuclear complexes 10, 11 and 12, respect-
ively, with terminal chloride ligands. However, reaction of 3
with the small ‘‘bite’’ diphosphane dppm gave 13, with a
bridging chloride ligand. Reaction of 11 with silver triflate in
acetone gave the new dinuclear complex 14, with the Schiff
base ligand as [C,N,O] terdentate. Reaction of 3 with the di-
phosphane dppe in a 1:2 molar ratio, and silver perchlorate,
dinuclear
cyclometallated
complexes
[Pd{2,3,4-(Me-
O)3C6HC(H)=NR}(µ-O2CMe)]2 (R = CH2CH2OH, 2; R = Me,
21; R = Et, 22; R = Pr, 23; R = tBu, 24), with the ligand bonded
to the palladium atom through the imine nitrogen and the
C6 carbon atoms. The 1H and 13C{1H} NMR spectra of the
complexes showed the presence of the anti and syn isomers
in solution. The anti/syn ratio varies with the solvent and the
nature of the imine nitrogen substituent R. Complex 24 with
the bulky tBu group showed a 28:1 ratio in chloroform whilst
the less bulky substituted complexes showed lower ratios. gave the mononuclear complex 15. Treatment of 3 with the
The X-ray crystal structure of the syn isomer of complex 2 is triphosphane bis(2-diphenylphosphanylethyl)phenylphos-
described. Reaction of the acetato-bridged complex 2 with phane in a 1:2 molar ratio, followed by treatment with so-
PPh3 gave the mononuclear complex 4, in a bridge-splitting
reaction. Reaction of 2 with the diphosphanes dppm, dppp
and dppb in a 1:1 molar ratio gave the dinuclear cyclo-
metallated complexes 5, 6 and 7, respectively. Treatment of 2
with an aqueous solution of sodium chloride gave the chloro-
bridged complex 3. Treatment of the cyclometallated chloro-
dium perchlorate, gave 16, in which the palladium atom was
bonded to the triphosphane through the three phosphorus
atoms. The X-ray crystal structures of complexes 8, 9, 15 and
16 are also reported.
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
acetate, which gives dimeric acetato-bridged complexes with
the characteristic open-book geometry;[13,14] these species
are good starting materials for a great number of cyclo-
metallated derivatives. Two different dispositions are pos-
sible for such compounds: the syn isomer with overall Cs
symmetry, and the anti isomer with overall C2 symmetry.
The latter is by far the most common, and the known crys-
tal structures of dinuclear acetato-bridged complexes corre-
spond to the anti isomer.[10,15Ϫ27] We therefore sought to
isolate and characterise the syn isomer in a pure form by
modifying the steric requirements of the substituent at the
imine nitrogen atom, i.e., substituents with small or negli-
gible steric hindrance, which should allow the nitrogen
atoms to lie above each other in the syn form without repul-
sions arising from the N-R groups, and in the present paper
we report the crystal and molecular structure of a dinuclear
acetato-bridged cyclometallated complex 2, which, to the
best of our knowledge, is the first example of a syn isomer.
Compound 2 was obtained as an equilibrium mixture of
the anti and syn isomers, and the features involved in the
Cyclometallated compounds have attracted much atten-
tion in recent years and abundant reports concerning them
have appeared.[1Ϫ7] They are important not only because
they show numerous applications in organic and organo-
metallic synthesis[8] and in biologically active com-
pounds,[9,10] among others, but also due to the new struc-
tural features they promote.[11,12] Lately, we have been inter-
ested in the study of Schiff base cyclometallated complexes
prepared by direct reaction of the ligand with palladium()
[a]
´
Departamento de Quımica Fundamental, Universidad de La
Corun˜a,
15071 La Corun˜a, Spain
Fax: (internat.) ϩ34-981/167-065
E-mail: qiluaafl@udc.es
[b]
´
´
Departamento de Quımica Inorganica, Universidad de
Santiago de Compostela,
15782 Santiago de Compostela, Spain
Fax: (internat.) ϩ34-981/595-012
E-mail: qideport@usc.es
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0909Ϫ2389 $ 20.00ϩ.50/0
2389

´
A. Fernandez, J. M. Vila et al.
FULL PAPER
equilibrium are also described. As we have observed before
in related compounds with terdentate [C, N, X] (X ϭ N, O,
S] ligands,[28Ϫ31] the reactivity of the acetate dimeric com-
pounds, and of their chloro-bridged derivatives, is fairly
extensive, especially when they react with mono-, di- and
triphosphanes, and herein we also report this chemistry, as
well as the synthesis of [C, N, O] derivatives with PdϪO
bond formation via halide abstraction by a silver() salt.
The crystal structures of the cyclometallated compounds 8,
9, 15 and 16 are also given.
Figure 1. Isomers of compound 2
(see Figure 1), with the anti disposition being by far the
most frequent.[14]
Results and Discussion
If both isomers are present in the final product two res-
onances would be expected for the HCϭN and aromatic
For the convenience of the reader the compounds and protons and three for the MeCOO protons in the 1H NMR
reactions are shown in Schemes 1, 2 and 3. The compounds spectrum: one for the anti isomer and two for the syn iso-
1
described in this paper were characterised by elemental ana- mer. Thus, the H NMR spectrum of 2 shows two sets of
lysis (C, H, N), IR spectroscopy and by H, 31P{1H} and, signals, one for each isomer. The resonance corresponding
1
in part, 13C{1H} NMR spectroscopy and FAB mass spec- to the HCϭN proton appears as a singlet (δ ϭ 7.57 and
trometry (data in the Exp. Sect.).
7.81 ppm, for the anti and syn isomers, respectively) shifted
Reaction of the Schiff base ligand 2,3,4-(MeO)3- to lower frequency due to the coordination of the imine
C6H2C(H)ϭNCH2CH2OH (1) with palladium() acetate group to the palladium atom through the lone pair of the
(Scheme 1) gave the dinuclear acetato-bridged complex nitrogen atom.[32] The H5 resonance also appears as a sing-
[Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}(µ-O2CMe)]2 let, confirming metallation of the C6 carbon. The 1H NMR
(2) as an orange air-stable solid which was fully charac- spectrum shows the signal of the MeCOO protons as a sing-
terised. Syn and anti isomers are possible for the folded let at δ ϭ 2.07 ppm, for the anti isomer, and as two singlets
arrangement of the acetato-bridged dimers: the anti isomer at δ ϭ 2.25 and 2.02 ppm for the syn isomer. The IR spec-
with C2 symmetry and the syn isomer with Cs symmetry trum of 2 shows the ν(CϭN) stretch at 1604 cmϪ1, shifted
Scheme 1. (i) Pd(ACO)2, (toluene), (ii) NaCl (acetone/water), (iii) PPh3 (acetone), (iv) dppm, dppp or dppb (acetone, 1:1 molar ratio)
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Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
to lower wavenumbers (relative to the free ligand) due to N- The resonances for the anti and syn isomers were ascribed
coordination of the imine.[33,34] The IR spectrum also shows accordingly (see Exp. Sect.).
strong bands assigned to the symmetric and asymmetric
The integration of the signals corresponding to both iso-
ν(COO) vibrations, in agreement with bridging acetate li- mers showed that the anti/syn ratio is ca. 7.5:1 for com-
gands[35] (see Exp. Sect.). The ν(OϪH) stretch appears at plexes 21, 22 and 23 in CDCl3, whereas in [D6]acetone a
3384 cmϪ1, close to its position in the spectrum of the free 5:1 ratio is observed (cf. compound 2), and for complex 24,
ligand, in agreement with a noncoordinated hydroxyl group. with the bulky tBu moiety bonded to the imine nitrogen a
From the integration of the peaks corresponding to both value of 28:1 is found.
1
isomers in the H NMR spectrum we concluded that the
anti/syn ratio is ca. 5:1
Molecular Structure of [Pd{2,3,4-(MeO)3C6HC(H)؍
NCH2CH2OH}(µ-OAc)]2 (2)
The 13C{1H} NMR spectrum showed the presence of sig-
nals corresponding to both isomers, with the CϭN, C6 and
C1 resonances shifted toward higher frequency, thus con-
firming that metallation had occurred.[28] The mass FAB
spectrum of 2 shows a cluster of peaks, centred at 808 amu,
which correspond to [M]ϩ. The isotopic pattern is in good
agreement with the expected dinuclear structure.
Suitable crystals were grown by slowly evaporating a
chloroform/n-hexane solution of the complex. The molecu-
lar structure is illustrated in Figure 2. Crystal data are given
in Table 1 and selected bond lengths and angles with estim-
ated standard deviations are shown in Table 2.
The synthesis of complex 2 was performed under differ-
ent reaction conditions: toluene at 60 °C, chloroform at
room temperature and boiling methanol. Irrespective of the
method used the anti/syn ratio is ca. 5:1 in all cases, which
seems to be the equilibrium ratio. Although we cannot as-
certain completely that the solid state of 2 contains only
crystals of the syn form, the 1H NMR spectrum of the solid,
freshly dissolved in CDCl3, also shows the presence of both
isomers in the resulting solution in a 5:1 ratio, and the relat-
ive amount of isomers does not vary perceptively with tem-
perature: heating a chloroform solution does not change the
1H NMR spectrum of 2, nor its concentration. However,
the solvent in which the spectra were recorded does have a
1
noticeable effect on the isomer ratio. Thus, the H NMR
Figure 2. Molecular structure of [Pd{2,3,4-(MeO)3C6HC(H)ϭ
NCH2CH2OH)}(µ-OAc)]2 (2), with labelling scheme; hydrogen
atoms have been omitted for clarity
spectrum in [D3]acetonitrile shows an anti/syn ratio of 3:1
and a solution in [D6]acetone a ratio of ca. 4:1, whereas
dissolution in [D6]DMSO causes partial decomposition of
the compound. Nevertheless, the 1H NMR spectrum re-
corded after removal of [D6]acetone from the NMR tube
The structure consists of dimeric molecules at van der
and dissolution of the product in CDCl3, again shows the Waals distances. The molecular structure corresponds to
initial 5:1 ratio. Therefore, it seems that solubility factors the syn isomer, with the cyclometallated moieties in an
could account for such an equilibrium. Furthermore, we open-book disposition and two acetate ligands bridging the
also considered that steric factors should be regarded, i.e., palladium atoms. Although a large number of crystal struc-
the bulkiness of the -NϪR group could also influence the tures of dinuclear acetato-bridged cyclometallated com-
anti/syn ratio. It is known that most of the acetato-bridged plexes have been reported, to the best of our knowledge this
dimer complexes for which the existence of syn and anti is the first example of a syn disposition of the metallated li-
isomers has been reported are phenylimidazole derivatives. gands.
˚
The imidazole ligand, after [C,N] coordination to the palla-
The Pd(1)ϪPd(2) bond length of 2.8514(13) A is similar
dium atom, adopts a quasi planar disposition,[36Ϫ39] and we to values reported for related complexes
and can be re-
[13]
therefore suppose that the small steric repulsion between garded as nonbonding. Each palladium atom is bonded in
the imidazole rings in the syn disposition should favour this a slightly distorted square-planar geometry to four atoms:
geometry. However, Schiff base ligands with more or less a carbon atom of the phenyl ring and the imine nitrogen
bulky substituents at the imine nitrogen should favour a atom of the Schiff base ligand, and two oxygen atoms of
trans disposition in order to avoid the steric hindrance. In the bridging acetate ligands.
complex 2, the CH2CH2OH moiety allows a cis disposition
The sum of the angles around the palladium atoms is
of the ligands. To confirm this we prepared analogues to approximately 360°. The angles between adjacent atoms in
1, ligands 17؊20, which, upon reaction with palladium() the coordination sphere are close to the expected value of
acetate in toluene (Scheme 1), gave the acetato-bridged 90°, with the most noticeable distortions corresponding to
complexes [Pd{2,3,4-(MeO)3C6HC(H)ϭNR}(µ-O2CMe)]2, the C(1)ϪPd(1)ϪN(1) and C(13)ϪPd(2)ϪN(2) angles
(21, R ϭ Me; 22, R ϭ Et; 23, R ϭ Pr; 24, R ϭ tBu). [81.9(4) and 82.1(4)°, respectively] due to chelation. The
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401
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´
A. Fernandez, J. M. Vila et al.
FULL PAPER
Table 1. Crystallographic Data for complexes 2, 8, 9 and 16
2
8
9
15
16
Empirical formula
Formula mass
T [K]
C28H42N2O14Pd2
843.44
293(2)
C30H31NO4ClPPd
642.38
293(2)
C31H31NO7F3ClPPdS
756.00
293(2)
C38H40NO8ClP2Pd
842.50
293(2)
C46H49NO8ClP3Pd
978.62
293(2)
˚
λ [A]
0.71073
0.71073
0.71073
0.71073
0.71073
Crystal system
Space group
Monoclinic
P21/a
10.552(1)
28.406(2)
12.173(1)
Triclinic
P1
Triclinic
P1
Orthorhombic
Pbca
17.267(2)
18.250(2)
24.162(3)
Monoclinic
P21/n
11.397(2)
21.492(4)
19.189(4)
¯
¯
˚
a [A]
9.631(1)
10.174(1)
15.029(1)
96.623(1)
107.717(1)
95.514(1)
1386.9(1)
2
9.280(1)
10.860(1)
17.512(1)
99.472(1)
104.640(1)
106.296(1)
1585.4(1)
2
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
109.814(2)
106.739(4)
3
˚
V [A ]
3432.7(5)
4
1.114
7614.0(1)
8
0.693
4501.0(1)
4
0.632
Z
µ [mmϪ1
]
0.860
0.767
Max., min.
0.81, 0.73
0.88, 0.75
0.70, 0.70
0.95, 0.75
0.96, 0.83
transmissions
ρcalc. [gcmϪ3
θ range [°]
Reflections
collected
]
1.632
1.43 to 25.00
18957
1.538
1.43 to 29.10
10056
1.584
2.02 to 28.32
11258
1.470
1.69 to 28.32
45948
1.444
1.46 to 26.45
9253
Independent
reflections
6053
(Rint ϭ 0.020)
0.0776
6786
(Rint ϭ 0.037)
0.0460
7716
(Rint ϭ 0.017)
0.0294
9254
(Rint ϭ 0.072)
0.0412
9253
(Rint ϭ 0.028)
0.0466
[a]
R1
[b]
wR2
0.1690
0.1992
0.0776
0.1137
0.0829
[a]
[b]
2
2 2
R1 ϭ Σ||F0| Ϫ |Fc||/Σ|F0|, [F Ͼ 4σ(F)]. wR2 ϭ Σ[w(F0 Ϫ Fc ) /Σw(F02)2]1/2, all data.
˚
are forced to lie above one another in the dimeric molecules.
This leads to inter-ligand repulsions and results in the coor-
dination planes of the palladium atoms (planes 1 and 2)
being tilted at an angle of 25.0°. The disposition of the che-
lating C,N ligands is not completely eclipsed, probably as a
consequence of these repulsions. This is shown by the di-
Table 2. Selected bond lengths (A) and angles (°) for complex 2
Pd(1)ϪPd(2)
Pd(1)ϪC(1)
Pd(1)ϪN(1)
Pd(1)ϪO(9)
Pd(1)ϪO(11)
C(1)ϪC(6)
C(6)ϪC(7)
N(1)ϪC(7)
2.8514(13)
1.973(11) Pd(2)ϪC(13)
1.963(10)
2.012(9)
2.064(8)
2.130(8)
2.018(9)
2.084(7)
2.131(7)
Pd(2)ϪN(2)
Pd(2)ϪO(10)
Pd(2)ϪO(12)
1.396(15) C(13)ϪC(18)
1.434(15) C(18)ϪC(19)
1.276(13) N(2)ϪC(19)
1.384(15) hedral angles C(1)ϪPd(1)ϪPd(2)ϪC(13), N(1)ϪPd(1)Ϫ
1.424(14)
1.298(13)
Pd(2)ϪN(2), O(9)ϪPd(1)ϪPd(2)ϪO(10) and O(11)Ϫ
Pd(1)ϪPd(2)-0(12) of 17.3(5), 17.6(4), 15.3(3) and 14.0(3)°,
respectively. No intra- or intermolecular OϪH···OϪH
C(1)ϪPd(1)ϪN(1)
C(1)ϪPd(1)ϪO(9)
N(1)ϪPd(1)ϪO(9) 175.1(4)
C(1)ϪPd(1)ϪO(11) 178.6(4)
N(1)ϪPd(1)ϪO(11) 97.7(4)
O(9)ϪPd(1)ϪO(11) 87.2(3)
81.9(4)
93.3(4)
C(13)ϪPd(2)ϪN(2) 82.1(4)
bonding is observed.
C(13)ϪPd(2)ϪO(10) 95.0(4)
N(2)ϪPd(2)ϪO(10) 175.8(3)
C(13)ϪPd(2)ϪO(12) 176.0(4)
N(2)ϪPd(2)ϪO(12) 94.8(4)
O(10)ϪPd(2)ϪO(12) 88.2(3)
Reactivity of the Acetato-Bridged Complex 2
The reaction of 2 with aqueous sodium chloride gave the
chloro-bridged
complex
[Pd{2,3,4-(MeO)3C6HC(H)ϭ
NCH2CH2OH}(µ-Cl)]2 (3; Scheme 2), which was fully char-
Pd(1)ϪC(1) and Pd(2)ϪC(13) bond lengths of 1.973(11) acterised (see Exp. Sect.). The IR spectrum of this complex
and 1.963(10) A, respectively, are somewhat shorter than shows the absence of the ν(COO) bands. The 1H NMR
˚
the values predicted from their covalent radii[40] but similar spectra of 3 shows the HCϭN and H5 resonances at δ ϭ
to values found earlier.[13,14] However, the Pd(1)ϪN(1) and 8.08 and 7.51 ppm, respectively.
˚
Pd(2)ϪN(2) bond lengths of 2.018(9) and 2.012(9) A, re-
Reaction of 2 with PPh3 gave the complex [Pd{2,3,4-(Me-
spectively, are in agreement with the value based on the sum O)3C6HC(H)ϭNCH2CH2OH}(O2CMe)(PPh3)] (4) as an
of the covalent radii for nitrogen and palladium,[40] and are air-stable solid which was fully characterised (see Exp.
similar to values reported previously.[13,14] The differing Sect.). The IR spectrum of 4 shows strong bands at 1290
Pd(1)ϪO(9) and Pd(1)ϪO(11) [2.084(7) and 2.131(7) A, re- and 1570 cmϪ1 assigned to the symmetric and asymmetric
˚
spectively] and Pd(2)ϪO(10) and Pd(2)ϪO(11) [2.064(8) ν(COO) vibrations, respectively, in agreement with those ex-
and 2.130(8) A, respectively] bond lengths reflect the higher pected for monocoordinate acetate ligands.[35] The IR spec-
˚
trans influence of the aryl carbon as compared to the imine trum also shows the νCϭN stretch at 1613 cmϪ1. This ab-
nitrogen atom.
sorption is shifted to lower wavenumbers relative to the free
As a result of the palladium atoms being bridged by two ligand due to N-coordination of the imine;[32] the ν(OϪH)
mutually cis µ-acetate ligands the metallated Schiff bases band at 3400 cmϪ1 (3402 cmϪ1 in the free ligand) is as ex-
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Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
Scheme 2. (i) PPh3 (acetone), (ii) dppm, dppp, dppb or dppf (acetone, 1:1 molar ratio), (iii) AgCF3SO3 (acetone)
pected for a noncoordinated OH group. The 1H NMR spec- NMR spectra show the coupling of the HCϭN and the H5
trum shows the HCϭN and H5 resonances coupled to the resonances to the phosphorus nucleus, and in the 31P{1H}
phosphorus nucleus [δ ϭ 8.31 (JP,H ϭ 7.8) and δ ϭ 5.70 NMR spectra the resonance of the phosphorus nuclei ap-
(JP,H ϭ 5.8 Hz), respectively], and the C(4)ϪOCH3 reson- pears as a singlet at ca. δ ϭ 31 ppm in accordance with
ance shifted towards lower frequency by ca. 0.8 ppm, relat- the centrosymmetric nature of the complexes. We tentatively
ive to complex 2, due to the shielding effects of the phos- propose this structure in accordance with the conductivity
phane phenyl ring;[41] in the 31P{1H} spectrum the reson- data for 5, 6 and 7, which show them to be nonelectrolytes.
ance of the coordinated phosphane appears as a singlet at
Reaction of the cyclometallated chloro-bridged complex
δ ϭ 40.8 ppm. These findings are in agreement with a phos- 3 with PPh3 in acetone yielded the mononuclear complex
phorus trans to nitrogen arrangement, as we and others [Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}(Cl)(PPh3)] (8)
have observed earlier, which seems to be the more common which was fully characterised (see Exp. Sect.). The IR and
arrangement for the entering phosphane.[41Ϫ46] The novel NMR spectra of 8 are similar to those for complex 4; the
term transphobia has been introduced by J. Vicente et al. to most noticeable difference in the IR spectra is the absence
describe the restricted coordination of mutually trans phos- of the ν(COO) bands.
1
phanes and phenyl carbon atoms.[44,45]
The H NMR spectrum shows doublets assigned to the
The FAB-mass spectrum shows peaks centred at 666 and HCϭN and H5 protons coupled to the 31P nucleus [δ ϭ
608 amu assigned to the [MH]ϩ and [M Ϫ OAc]ϩ frag- 8.38 ppm (JP,H ϭ 8.3) and δ ϭ 5.74 ppm (JP,H ϭ 6.3 Hz),
ments, respectively.
respectively], and the 31P{1H} NMR spectrum shows a
Reaction of complex 2 with Ph2PCH2PPh2 (dppm), singlet resonance at δ ϭ 40.3 ppm. The mass FAB spectrum
Ph2P(CH2)3PPh2 (dppp) or Ph2P(CH2)4PPh2 (dppb), in a shows peaks centred at 606 amu corresponding to the [M
1:1 complex-to-phosphane molar ratio gave the dinuclear Ϫ Cl]ϩ fragment.
cyclometallated complexes [{Pd[2,3,4-(MeO)3C6HC(H)ϭ
Treatment of
3
with the tertiary diphosphanes
NCH2CH2OH](O2CMe)}2(µ-Ph2P(CH2)nPPh2)] (5, n ϭ 1; Ph2P(CH2)3PPh2 (dppp), Ph2P(CH2)4PPh2 (dppb) and
6, n ϭ 3; 7, n ϭ 4). The IR spectra of these complexes are Ph2PC5H4FeC5H4PPh2 (dppf) in a 1:1 molar ratio gave the
in agreement with monocoordinate acetate ligands and with dinuclear
complexes
[{Pd[2,3,4-(MeO)3C6HC(H)ϭ
noncoordinated hydroxyl groups (vide supra). The 1H NCH2CH2OH](Cl)}2{µ-Ph2P(CH2)nPPh2}], (10, n ϭ 3; 11,
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401
2393

´
A. Fernandez, J. M. Vila et al.
FULL PAPER
n ϭ 4), and the trinuclear compound [{Pd[2,3,4-(MeO)3- 13C{1H} NMR spectra of cyclometallated complexes de-
C6HC(H)ϭNCH2CH2OH](Cl)}2{µ-Ph2PC5H4FeC5H4- rived from the Schiff base ligand 2-ClC6H4C(H)ϭ
PPh2}] (12), respectively. The IR and NMR spectra of these NCH2CH2NMe2 with formation of a new PdϪNMe2 bond
complexes show similar features to those described for the after treatment with a silver() salt.[29] Conductivity meas-
spectra of compound 8 suggesting a similar disposition urements carried out in dry acetonitrile gave a value for the
around the palladium atoms. The 31P{1H} NMR spectrum molar conductivity of 116.2 ohmϪ1 cm2 molϪ1, character-
shows a singlet resonance for the phosphorus nuclei indicat- istic of 1:1 electrolytes.[47]
ing the symmetric nature of the complexes. Conductivity
Similarly, when compound 11 was treated with silver
measurements in dry acetonitrile showed the complexes to triflate in acetone the new dinuclear complex [{Pd[2,3,4-
be molecular nonelectrolytes.
However, when complex
(MeO)3C6HC(H)ϭNCH2CH2OH]}2{µ-Ph2P(CH2)4PPh2}]-
was reacted with [CF3SO3]2 (14) was obtained with the Schiff base ligand as
3
Ph2PCH2PPh2 (dppm) the dinuclear complex [{Pd[2,3,4- [C,N,O] terdentate. The IR spectrum of this complex shows
(MeO)3C6HC(H)ϭNCH2CH2OH]}2(µ-Cl)(µ-Ph2PCH2- a broad band due to the ν(OϪH) stretch centred at ca. 3250
PPh2)][Cl] (13) was obtained (see Exp. Sect.). The 1H NMR cmϪ1. The 1H NMR spectrum shows similar features to
spectrum also shows coupling of the HCϭN and H5 pro- those observed for the spectrum of 9. Similarly, the 13C{1H}
tons to the phosphorus nucleus and the 31P{1H} NMR NMR spectrum shows the signals assigned to the methylene
spectra shows a singlet resonance. The specific molar con- carbon atoms at δ ϭ 66.3 and 57.5 ppm. Conductivity
ductivity in dry acetonitrile (175.1 ohmϪ1 cm2 molϪ1) is in measurements carried out in dry acetonitrile showed the
agreement with the value expected for a 1:1 electrolyte.[47] complex to be a 1:2 electrolyte.
This behaviour is in contrast to that observed for com-
Reaction of complex
3
with the diphosphane
pound 5, where a 1:1 electrolyte formulation with both pal- Ph2P(CH2)2PPh2 (dppe) in a 1:2 molar ratio, followed by
ladium atoms bridged by the diphosphane and by one acet- treatment with sodium perchlorate, gave the mononuclear
ate ligand would be possible. However, the low conductivity complex
[Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}-
values preclude this formulation for 5. {PPh2(CH2)2PPh2-P, P }][ClO4] (15; Scheme 3) as an air-
In order to promote coordination of the hydroxyl oxygen, stable solid which was fully characterised (see Exp. Sect.).
1
thus giving a coordinated [C,N,O] ligand, we treated the The H NMR spectrum shows the signal corresponding to
cyclometallated complexes 8 and 11 with silver triflate to H5 at δ ϭ 5.93 ppm, coupled to both phosphorus atoms
remove the chloride moiety. Thus, treatment of 8 with silver (JH,P ϭ 8.8, 5.8 Hz). However, the HCϭN resonance only
triflate gave the complex [Pd{2,3,4-(MeO)3C6HC(H)ϭ shows coupling to the 31P nucleus trans to nitrogen (δ ϭ
NCH2CH2OH}(PPh3)][CF3SO3] (9) and an AgCl precipit- 8.50 ppm; JH,P ϭ 8.3 Hz). The 31P{1H} NMR spectrum
ate. The IR spectrum shows a band assigned to the ν(OϪH) shows two doublets for the two nonequivalent phosphorus
vibration at 3245 cmϪ1 shifted to lower wavenumber (3402 nuclei (δ ϭ 61.0, 43.0 ppm; JP,P ϭ 25.4 Hz). The resonance
and 3365 cmϪ1 in the spectra of the free ligand and com- at lower frequency was assigned to the phosphorus nucleus
pound 8, respectively) due to PdϪO bond formation.[48] trans to the phenyl carbon atom in accordance with the
The most noteworthy differences in the 1H NMR spectrum higher trans influence of the latter with respect to the Cϭ
of 9 from that of 8 are in the lowfield shift of the -OH N nitrogen atom.[49] The 13C{1H} spectrum shows coupling
hydroxyl proton resonance which appears as a triplet at δ ϭ of the C6 resonance to the two phosphorus nuclei (δ ϭ
7.02 ppm (JH,H ϭ 5.6 Hz), (for complex 8 a broad reson- 156.0 ppm; JP,C ϭ 12.0, 5.6 Hz). Conductivity measure-
ance at ca. δ ϭ 3.2 ppm was assigned to OH) and the res- ments were in accordance with a 1:1 electrolyte formula-
olution of the CH2CH2OH signals, which appear as a mul- tion.
tiplet in the spectrum of 8 at δ ϭ 4.03 ppm and as two
broad resonances at δ ϭ 4.13 and 3.89 ppm for 9.
Treatment of 3 with the triphosphane bis(2-diphenyl-
phosphanylethyl)phenylphosphane in a 1:2 molar ratio, fol-
In the 13C{1H} NMR spectrum the resonances assigned lowed by treatment with sodium perchlorate, gave
to the CH2CH2OH carbon atoms appear at δ ϭ 67.7 and [Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}{(PPh2CH2-
56.8 ppm shifted to high and low frequency, respectively, CH2)2PPh-P, P, P }][ClO4] (16; Scheme 3). The phosphorus
relative to compound 8 (δ ϭ 62.9 and 61.8 ppm in the spec- resonances in the 31P{1H} NMR spectrum of 16 are shifted
trum of 8). We have observed a similar behaviour in the downfield from their values in the free phosphane sug-
Scheme 3. (i) 1: dppe or triphos (acetone, 1:2 molar ratio), 2: NaClO4
2394
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
˚
gesting coordination of the three phosphorus atoms to the
metal centre. A triplet resonance at δ ϭ 86.0 ppm was as-
signed to the central 31P nucleus trans to the phenyl carbon
atom, and a doublet at δ ϭ 44.5 was assigned to the two
equivalent mutually trans phosphorus nuclei. This latter sig-
Table 3. Selected bond lengths (A) and angles (°) for complexes 8,
9, 15 and 16
8
9
15
16
Pd(1)ϪC(1)
2.061(5)
1.997(2) 2.052(4)
2.064(4)
nal appears at lower frequency due to the higher trans influ-
ence of the phosphane ligand.[49] The resonance of the pro-
ton in the ortho position to the metallated carbon atom ap-
pears as a doublet of triplets showing coupling to the cent-
ral 31P atom (JP,H ϭ 8.8 Hz) and to the terminal
phosphorus atoms (JP,H ϭ 2.4 Hz). The shift of the ν(Cϭ
Pd(1)ϪP(1)
Pd(1)ϪN(1)
Pd(1)ϪCl(1)
Pd(1)ϪO(1)
Pd(1)ϪP(2)
Pd(1)ϪP(3)
C(1)ϪC(6)
2.2443(13) 2.2751(5) 2.2557(10) 2.2893(12)
2.093(4)
2.028(2) 2.108(3)
2.480(3)
2.4263(15)
2.208(1)
2.33347(10) 2.2773(11)
2.3243(12)
1.407(7)
1.482(8)
1.285(7)
1.411(3) 1.409(5)
1.387(5)
1.456(5)
1.274(4)
N) stretching vibration to lower wavenumber in the IR C(6)ϪC(7)
1.448(3) 1.447(5)
1.271(3) 1.279(5)
N(1)ϪC(7)
spectrum and the upfield shift of the HCϭN proton reson-
ance in the 1H NMR spectra indicate the existence of a
palladium-nitrogen interaction in solution. These results
C(1)ϪPd(1)ϪN(1) 82.80(19) 82.31(7) 80.6(1)
N(1)ϪPd(1)ϪP(1) 171.37(12) 177.29(5) 175.22(9)
C(1)ϪPd(1)ϪP(1) 92.60(15) 99.85(5) 95.9(1)
C(1)ϪPd(1)ϪCl(1) 171.38(14)
P(1)ϪPd(1)ϪCl(1) 94.48(5)
N(1)ϪPd(1)ϪCl(1) 90.78(13)
76.0(1)
113.81(9)
95.9(1)
strongly agree with those previously obtained by us in re-
lated pentacoordinate palladium() species,[12] and al-
though the proposed structure in Scheme 3 seems slightly
different from the solid state structure (Figure 6), we sug-
gest the former as the probable solution disposition; for a
N(1)ϪPd(1)ϪO(1)
77.46(6)
159.33(7)
100.19(4)
thorough discussion regarding this issue see ref.[12] The Cϭ C(1)ϪPd(1)ϪO(1)
N signal in the 13C{1H} NMR spectrum at δ ϭ 167.3 ppm
P(1)ϪPd(1)ϪO(1)
P(2)ϪPd(1)ϪP(1)
coupled to the central phosphorus (JP,C ϭ 5.7 Hz) is also
P(2)ϪPd(1)ϪN(1)
84.52(4)
98.79(9)
176.8(1)
84.24(4)
109.69(9)
173.7(1)
90.61(9)
155.43(4)
85.01(4)
92.4(1)
indicative of a Pd-N interaction. Molar conductivity meas-
C(1)ϪPd(1)ϪP(2)
urements showed that complex 16 is a 1:1 electrolyte. The
FAB-mass spectrum shows a set of peaks centred at 979
and 877 amu assigned to the [M]ϩ and the [M Ϫ ClO4]ϩ
fragments, respectively.
N(1)ϪPd(1)ϪP(3)
P(1)ϪPd(1)ϪP(3)
P(2)ϪPd(1)ϪP(3)
C(1)ϪPd(1)ϪP(3)
Molecular Structure of Complexes 8, 9, 15 and 16
Suitable crystals were grown by slowly evaporating chlo-
roform solutions of the complexes. Crystal data are given in
Table 1 and selected bond lengths and angles with estimated
standard deviations are shown in Table 3.
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}(Cl)-
(PPh3)] (8)
The crystal structure of this complex (Figure 3) consists
of discrete molecules separated by van der Waals distances.
The palladium atom is bonded in a slightly distorted
square-planar geometry to the C(1) carbon atom of the
phenyl ring, to the imine N(1) atom of the Schiff base li-
gand, to the Cl(1) atom and to the P(1) phosphorus atom
of the triphenylphosphane ligand. The angles between adja-
cent atoms in the coordination sphere of palladium are
close to the expected value of 90° with the most noticeable
Figure 3. Molecular structure of complex [Pd{2,3,4-(Me-
O)3C6HC(H)ϭNCH2CH2OH}(Cl)(PPh3)] (8), with labelling
scheme; hydrogen atoms have been omitted for clarity
gen H(1) and the Cl(1) atom are bonded by intramolecular
˚
H-bonding [O(1)ϪH(1)···Cl(1): 3.079(6) A, 173.8°].
distortions
corresponding
to
the
bite
angle
C(1)ϪPd(1)ϪN(1) of 82.8(2)°. The sum of the angles about
palladium is approximately 360°.
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}(PPh3)]-
[CF3SO3] (9)
The geometry around palladium is planar [mean devi-
ation from the least-square plane Pd(1), C(1), N(1), P(1),
The crystal structure of this complex (Figure 4) contains
Cl(1), (plane 1), of 0.960 A] and approximately co-planar one [Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH)}(PPh3)]ϩ
˚
Ϫ
with the metallated ring [Pd(1), C(1), C(6), C(7), N(1), cation and one CF3SO3 anion per asymmetric unit.
˚
mean deviation 0.0166 A (plane 2)] and with the phenyl
The palladium atom is bonded in a slightly distorted
˚
ring [plane 3, mean deviation of 0.0031 A] (angles between square-planar geometry to the C(1) carbon atom of the
planes are: plane 1:2, 6.0°; plane 1:3, 10.1°; 2:3, 5.0°). All phenyl ring, the imine N(1) nitrogen atom, the O(1) oxygen
bond lengths and angles are normal. The OH group, hydro- atom and to the phosphorus atom of the triphenylphos-
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401
2395

´
A. Fernandez, J. M. Vila et al.
FULL PAPER
Figure 4. Perspective view of the cation of complex [Pd{2,3,4-(Me-
O)3C6HC(H)ϭNCH2CH2OH}(PPh3)][CF3SO3] (9), with labelling
scheme; hydrogen atoms have been omitted for clarity
Figure 5. Perspective view of the cation of complex [Pd{2,3,4-
(MeO)3C6HC(H)ϭNCH2CH2OH}{PPh2(CH2)2PPh2-P, P }][ClO4]
(15), with labelling scheme; hydrogen atoms have been omitted
for clarity
phane ligand P(1). The angles between adjacent atoms in
the coordination sphere of palladium are close to the ex-
pected value of 90°, with the most noticeable distortions
and O(3s) oxygen atom of the perchlorate anion was found
[O(1)ϪH(1)···O(3s): 3.021(6) A, 156(11)°].
˚
corresponding
to
the
C(1)ϪPd(1)ϪN(1)
and
Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}{(PPh2-
CH2CH2)2PPh-P,P,P}][ClO4] (16)
N(1)ϪPd(1)ϪO(1) angles of 81.31(7)° and 78.46(6)°, re-
spectively. The sum of the angles about palladium is ap-
proximately 360°.
The crystal structure of this complex (Figure 6) contains
one [Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}{(PPh2-
The cation of 9 forms hydrogen bonds with the CF3SO3
Ϫ
CH2CH2)2PPh-P, P, P }]ϩ cation and one ClO4 anion per
˚
anion [O(1)ϪH(1)···O(2s): 3.783(3) A, 165(4)°].
asymmetric unit. The palladium atom is bonded to the C(1)
carbon atom of the metallated ring and to the three phos-
phorus atoms P(1), P(2) and P(3), of the triphos ligand.
A fifth interaction with the imine nitrogen completes the
coordination sphere about the palladium atom.
The most noticeable differences between the structures of
complexes 8 and 9 correspond to a shortening of the PdϪC
˚
˚
and PdϪN bond lengths [2.061(5) and 2.093(4) A, respect-
ively, for complex 8 vs. 1.997(2) and 2.028(2) A, also re-
spectively, for complex 9] and the greater C(1)ϪPd(1)ϪP(1)
angle [92.60(15)° for complex 8; 99.85(5)° for complex 9].
The latter is probably due to the steric repulsion between
the large chlorine Cl(1) atom in complex 8, as opposed to
the smaller O(1) oxygen atom in complex 9, and the bulky
PPh3 ligand. In complex 9, the small ‘‘bite’’ of the
NCH2CH2OH chelate [shown by the N(1)ϪPd(1)ϪO(1)
bond angle of 77.46(6)°], which forces the O(1) hydroxyl
oxygen and the phosphorus P(1) atoms apart, also reduces
repulsion.
˚
The Pd(1)ϪN(1) distance of 2.480(3) A is somewhat
˚
longer than the values of 2.338(3) A, reported recently by
us in a similar complex with a triphos ligand[51] and 2.23(2)
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}{PPh2-
(CH2)2PPh2-P,P}][ClO4] (15)
The crystal structure of this complex (Figure 5) contains
one [Pd{2,3,4-(MeO)3C6HC(H)ϭNCH2CH2OH}{PPh2-
Ϫ
(CH2)2PPh2-P, P }]ϩ cation and one ClO4 anion per asym-
metric unit. The palladium atom is bonded to four atoms:
the adjacent C(1) carbon atom and the N(1) nitrogen of the
Schiff base ligand 1, and the phosphorus atoms P(1) and
P(2) of the dppe ligand. The different trans influences of
the C(1) carbon atom and the N(1) nitrogen atom are re-
flected in the somewhat enlarged Pd(1)ϪP(2) bond length
˚
˚
Figure 6. Perspective view of the cation of complex [Pd{2,3,4-
(MeO)3C6HC(H)ϭNCH2CH2OH}{(PPh2CH2CH2)2PPh-P, P, P }]-
[ClO4] (16), with labelling scheme; hydrogen atoms have been
of 2.3335(1) A [Pd(1)ϪP(1): 2.256(1) A]. These distances
are in agreement with values previously reported.[28,48,50]
Hydrogen bonding between the OϪH(1) hydroxyl hydrogen omitted for clarity
2396
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
˚
The Schiff base ligands 19 and 20 were prepared similarly.
A found in an authentic pentacoordinate palladium()
complex.[52] However, the PdϪN bond length is shorter
than the weak interactions in the range 2.576(4)Ϫ2.805(5)
2,3,4-(MeO)3C6H2C(H)؍NCH2CH2CH3 (19): Yield: 3.50 g (90%).
IR (nujol mull): ν(CϭN) ϭ 1638s cmϪ1 1H NMR (200 MHz,
.
found
in
other
five-coordinate
complexes
of
CDCl3): δ ϭ 0.90 (t, JH,H ϭ 7.3 Hz, 3 H, NCH2CH2CH3), 1.67
(m, 2 H, NCH2CH2CH3), 3.51 (t, JH,H ϭ 7.3 Hz, 2 H, NCH2CH2),
palladium.[44,53Ϫ58] The coordination around the palladium
atom may be viewed as a trigonal bipyramid, with the 3.83, 3.88 (s, 9 H, OMe), 6.67 (d, JH5,H6 ϭ 8.8 Hz,1 H, H5), 7.64
(d, 1 H, H6), 8.47 (s, 1 H, Hi) ppm.
Pd(1), N(1), P(1) and P(3) atoms in the equatorial plane
(r.m.s. for the mean plane; 0.0158 A); the metallated carbon
2,3,4-(MeO)3C6H2C(H)؍NC(CH3)3 (20): Yield: 3.91 g (95%). IR
˚
atom and the central phosphorus atom are at the apical
positions. However, the trigonal bipyramidal geometry is
severely distorted as shown by the N(1)ϪPd(1)ϪP(1) and
N(1)ϪPd(1)ϪP(3) bond angles of 113.81(9) and 91.61(9)°,
respectively, which differ considerably from the ideal value
of 120°. Nevertheless, the bond angle values at palladium
preclude the geometry from being considered as square pyr-
amidal.
(nujol mull): ν(CϭN) ϭ 1636s cmϪ1. 1H NMR (200 MHz, CDCl3):
δ ϭ 1.15 [s, 9 H, NC(CH3)3], 3.73, 3.79 (s, 9 H, OMe), 6.56 (d,
J
H5,H6 ϭ 8.8 Hz, 1 H, H5), 7.56 (d, 1 H, H6), 8.42 (s, 1 H, Hi) ppm.
Preparation of 2,3,4-(MeO)3C6H2C(H)؍NCH3 (17): A pressure
tube containing 2,3,4-(MeO)3C6H2COH (3.21 g, 16.38 mmol) and
40 cm3 of dry chloroform was cooled to Ϫ20 °C and an excess of
NH2Me (1.53 g, 49.14 mmol; 200% excess), also cooled to Ϫ20 °C,
was added. The tube was sealed and heated to 80 °C for 24 h.
After cooling to room temperature, the solvent and the unreacted
˚
The Pd(1)ϪC(1) bond length of 2.064(4) A is similar to
values reported for related five-coordinate complexes.[12,51] NH2Me were removed under vacuum to give a yellow oil. Yield:
The Pd(1)ϪP(1), Pd(1)ϪP(2) and Pd(1)ϪP(3) bond lengths
3.26 g (95%). IR (nujol mull): ν(CϭN) ϭ 1644s cmϪ1 1H NMR
.
(200 MHz, CDCl3): δ ϭ 3.50 (s, 3 H, NϪCH3), 3.87, 3.88, 3.92 (s,
9 H, OMe), 6.71 (d, JH5,H6 ϭ 8.8 Hz, 1 H, H5), 7.63 (d, 1 H, H6),
8.52 (s, 1 H, Hi) ppm.
˚
of 2.2893(12), 2.2773(11) and 2.3243(12) A, respectively, are
also similar to those found in related PdII complexes.[12,51]
Hydrogen bonding between the OϪH(4) hydroxyl hydro-
gen and the O(7) oxygen atom of the disordered perchlorate
Ligand 18 was prepared similarly.
˚
anion was found [O(1)ϪH(4)···O(7a): 2.692(3) A, 167.3(4)°;
O(1)ϪH(4)···O(7b): 2.990(3) A, 140.7(4)°].
2,3,4-(MeO)3C6H2C(H)؍NCH2CH3 (18): Yield: 3.51 g (96%). IR
(nujol mull): ν(CϭN) ϭ 1638s cmϪ1. 1H NMR (200 MHz, CDCl3):
δ ϭ 1.04 (t, 3 H, NCH2CH3), 3.37 (q, JH,H ϭ 7.3 Hz, 2 H,
˚
NCH2CH3), 3.59, 3.60, 3.66 (s, 9 H, OMe), 6.44 (d, JH5,H6
ϭ
8.8 Hz, 1 H, H5), 7.43 (d, 1 H, H6), 8.29 (s, 1 H, Hi) ppm.
Experimental Section
Preparation of [Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}(µ-
O2CMe)]2 (2): A pressure tube was charged with 2,3,4-(Me-
O)3C6H2C(H)ϭNCH2CH2OH (1) (0.219 g, 0.92 mmol), palla-
dium() acetate (0.206 g, 0.92 mmol) and 20 cm3 of dry toluene
was then sealed under argon. The mixture was heated for 24 h at
60 °C. After cooling to room temp. the solution was filtered
through celite to remove the black palladium formed. The solvent
was then removed under vacuum to give a brown oil, which was
chromatographed on a column packed with silica gel. Elution with
dichloromethane/ethanol (92:8) afforded the final product as a yel-
low oil after solvent removal. Yield: 0.30 g (40%). M.p. 111.3 °C.
C28H38N2O12Pd2 (807.4): calcd. C 41.6, H 4.7, N 3.5; found C 40.9,
H 4.8, N 3.6. IR (polythene disc): ν(OϪH) ϭ 3384m cmϪ1; ν(Cϭ
N) ϭ 1604sh, m cmϪ1; νas(COO) ϭ 1563s cmϪ1; νs(COO) ϭ 1421s
General Remarks: Solvents were purified by standard methods.[59]
Chemicals were reagent grade. The phosphanes PPh3,
Ph2PCH2PPh2 (dppm), Ph2P(CH2)2PPh2 (dppe), Ph2P(CH2)3PPh2
(dppp), Ph2P(CH2)4PPh2 (dppb), Ph2PC5H4FeC5H4PPh2 (dppf)
and (Ph2PCH2CH2)2PPh (triphos), were purchased from Aldrich.
Microanalyses were carried out using a Carlo Erba Elemental Ana-
lyser, Model 1108. IR spectra were recorded as Nujol mulls or poly-
thene discs on a PerkinϪElmer 1330 or on a Mattson spectropho-
tometer. NMR spectra were obtained as CDCl3 solutions. They are
referenced to SiMe4 (1H, 13C{1H}) or 85% H3PO4 (31P{1H}) and
were recorded on a Bruker AC-200F spectrometer. All chemical
shifts are reported downfield from these standards. The FAB mass
spectra were recorded using a VG Quatro mass spectrometer with
a Cs ion gun; 3-nitrobenzyl alcohol was used as the matrix.
1
cmϪ1. H NMR (200 MHz, CDCl3), anti isomer: δ ϭ 2.07 (s, 3 H,
OAc), 3.73, 3.80, 3.84 (s, 9 H, OMe), 2.23 (br. s, 2 H, -CH2), 6.22
(s, 1 H, H5), 7.57 (s, 1 H, Hi); syn isomer: δ ϭ 2.25, 2.02 (s, 3 H,
OAc), 3.20 (br. s, 1 H, OH), 3.68, 3.71, 3.82 (s, 9 H, OMe), 6.00 (s,
1 H, H5), 7.81 (s, 1 H, Hi) ppm. 13C{1H} NMR (50.28 MHz,
CDCl3), anti isomer: δ ϭ 24.4 (CH3COO), 61.7, 61.3, 55.9 (OCH3),
61.6 (C8, C9), 110.2 (C5), 130.7 (C1), 137.9 (C6), 154.4, 151.3,
151.0 (C2, C3, C4), 170.6 (CϭN), 181.5 (CH3COO) ppm; syn iso-
mer: δ ϭ 24.4, 24.1 (CH3COO), 61.6, 60.6, 55.5 (OCH3), 110.6
(C5), 130.3 (C1), 137.3 (C6), 154.1, 151.3, 150.9 (C2, C3, C4), 171.2
(CϭN), 182.2, 180.9 (CH3COO) ppm. FAB-MS: m/z ϭ 808 [M]ϩ,
659 [M Ϫ OAc Ϫ CH2CH2OH]ϩ, 404 [M Ϫ OAc Ϫ L Ϫ Pd]ϩ, 344
[M Ϫ 2OAc Ϫ L Ϫ Pd]ϩ.
CAUTION: Perchlorate salts of metal complexes with organic li-
gands are potentially explosive. Only small amounts of these mat-
erials should be prepared and handled with great caution.
Preparation of 2,3,4-(MeO)3C6H2C(H)؍NCH2CH2OH (1): 2,3,4-
(MeO)3C6H2COH (3.21 g, 16.38 mmol) and NH2CH2CH2OH
(1.01 g, 16.45 mmol) were added to 50 cm3 of dry chloroform. The
mixture was heated under reflux in a DeanϪStark apparatus for
4 h. After cooling to room temperature, the solvent was evaporated
to give a yellow oil. Yield: 3.52 g (90%). IR (nujol mull): ν(OϪH) ϭ
3402m; ν(CϭN) ϭ 1642s cmϪ1. 1H NMR (200 MHz, CDCl3): δ ϭ
3.71, 3.68, 3.67 (s, 9 H, OMe), 3.54 (br. s, 2 H, -CH2), 4.01 (br. s,
2 H, -CH2), 6.50 (d, JH5,H6 ϭ 8.8 Hz,1 H, H5), 7.47 (d, 1 H, H6),
8.36 (s, 1 H, Hi) ppm. 13C{1H} NMR (50.28 MHz, CDCl3): δ ϭ
61.8, 60.8, 55.9 (OCH3), 63.5, 62.3 (C8, C9), 107.7 (C5), 122.1 (C6),
122.4 (C1), 141.7 (C3), 155.9, 153.8 (C2, C4), 158.6 (CϭN) ppm.
FAB-MS: m/z ϭ 240 [MH]ϩ.
Compounds 21, 22, 23 and 24 were prepared similarly and isolated
as yellow solids.
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH3}(µ-O2CMe)]2 (21): Yield:
0.39 g (50%). M.p. 120.3 °C. C26H34N2O10Pd2 (747.4): calcd. C
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401
2397

´
A. Fernandez, J. M. Vila et al.
FULL PAPER
41.8, H 4.6, N 3.7; found C 41.6, H 4.8, N 3.9. IR (polythene disc):
ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 40.8 (s) ppm. FAB-
ν(CϭN) ϭ 1610sh, m cmϪ1; νas(COO) ϭ 1572s cmϪ1; νs(COO) ϭ MS: m/z ϭ 666 [MH]ϩ, 608 [M Ϫ OAc]ϩ.
1413s cmϪ1 1H NMR (200 MHz, CDCl3), anti isomer: δ ϭ 2.13
.
Compounds 5, 6 and 7 were obtained following a similar proced-
ure, using a cyclometallated complex/diphosphane molar ratio of
1:1, as yellow (5 and 6) or white (7) air stable solids.
(s, 3 H, OAc), 2.88 (s, 3 H, NCH3), 3.73, 3.83, 3.86 (s, 9 H, OMe),
6.34 (s, 1 H, H5), 7.27 (s, 1 H, Hi); syn isomer: δ ϭ 2.05, 2.23 (s, 3
H, OAc), 3.28 (s, 3 H, NCH3), 3.69, 3.69, 3.78 (s, 9 H, OMe), 5.99
(s, 1 H, H5), 7.73 (s, 1 H, Hi) ppm.
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH](O2CMe)}2(µ-
Ph2PCH2PPh2)] (5): Yield: 0.027 g (48%). M.p. 166.7 °C (dec.).
C53H60N2O12P2Pd2 (1191.8): calcd. C 53.4, H 5.1, N 2.3; found C
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH3}(µ-O2CMe)]2 (22): Yield:
0.38 g (50%). M.p. 125.7 °C (dec.). C28H38N2O10Pd2 (775.4): calcd.
C 43.4, H 4.9, N 3.6; found C 42.8, H 4.8, N 3.5. IR (polythene
54.0, H 4.9, N 2.4. IR (polythene disc): ν(OϪH) ϭ 3307m cmϪ1
;
ν(CϭN) ϭ 1614m, sh cmϪ1; νas(COO) ϭ 1573s cmϪ1; νs(COO) ϭ
1286s cmϪ1. 1H NMR (200 MHz, CDCl3): δ ϭ 1.65 (s, 3 H, OAc),
2.91 [s, 3 H, C(4)ϪOMe], 3.10 (br. s, 1 H, OH), 3.63, 4.01 (s, 6 H,
OMe), 3.75, 4.03 (br. s, 4 H, -CH2), 5.45 (d, JP,H ϭ 5.4 Hz, 1 H,
H5), 8.36 (d JP,H ϭ 8.2 Hz, 1 H, Hi,) ppm. 31P{1H} NMR
(80.9 MHz, CDCl3): δ ϭ 32.0 (s) ppm. FAB-MS: m/z ϭ 1073 [M
Ϫ 2OAc]ϩ; 728 [MH Ϫ 2OAc Ϫ L Ϫ Pd]ϩ.
disc): ν(CϭN) ϭ 1604sh, m cmϪ1; νas(COO) ϭ 1566s cmϪ1
;
νs(COO) ϭ 1413s cmϪ1. 1H NMR (200 MHz, CDCl3), anti isomer:
δ ϭ 1.10 (t, JH,H ϭ 7.3 Hz, 3 H, NCH2CH3), 2.01 (s, 3 H, OAc),
2.77 (m, 1 H, NCH2CH3), 3.19 (m, 1 H, NCH2CH3), 3.74, 3.81,
3.84 (s, 9 H, OMe), 6.32 (s, 1 H, H5), 7.44 (s, 1 H, Hi); syn isomer:
δ ϭ isomer: 0.85 (t, JH,H ϭ 7.3 Hz, 3 H, NCH2CH3), 1.99, 2.21 (s,
3 H, OAc), 3.65, 3.68, 3.77 (s, 9 H, OMe), 5.99 (s, 1 H, H5), 7.74
(s, 1 H, Hi) ppm.
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH](O2CMe)}2{µ-
Ph2P(CH2)3PPh2}] (6): Yield: 0.032 g (49%). M.p. 217.3 °C (dec.).
C55H64N2O12P2Pd2 (1219.9): calcd. C 54.1, H 5.3, N 2.3; found C
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2CH3}(µ-O2CMe)]2
(23):
Yield: 0.37 g (50%). M.p. 141.3 °C. C30H42N2O10Pd2: calcd. C 44.9,
H 5.3, N 3.5; found C 45.4, H 4.9, N 3.7. IR (polythene disc):
ν(CϭN) ϭ 1606sh, m cmϪ1; νas(COO) ϭ 1558s cmϪ1; νs(COO) ϭ
54.3, H 5.1, N 2.4. IR (polythene disc): ν(OϪH) ϭ 3345m cmϪ1
;
ν(CϭN) ϭ 1612m, sh cmϪ1; νas(COO) ϭ 1573s cmϪ1; νs(COO) ϭ
1284s cmϪ1. 1H NMR (200 MHz, CDCl3): 1.54 (s, 3 H, OAc), 2.99
[s, 3 H, C(4)ϪOMe], 3.69, 3.93 (s, 6 H, OMe), 3.66, 3.88 (br. s, 4
H, -CH2), 5.73 (d, JP,H ϭ 5.3 Hz, 1 H, H5], 8.28 (d, JP,H ϭ 7.3 Hz,
1 H, Hi) ppm. 31P{1H} NMR (80.9 MHz, CDCl3) 32.3 (s) ppm.
FAB-MS: m/z ϭ 756 [M Ϫ 2OAc Ϫ L Ϫ Pd]ϩ.
1415s cmϪ1 1H NMR (200 MHz, CDCl3), anti isomer: δ ϭ 0.76
.
(t, JH,H ϭ 7.3 Hz, 3 H, NCH2CH2CH3), 1.60 (m, 2 H, NCH2CH2),
2.01 (s, 3 H, OAc), 2.55 (m, 1 H, NCH2CH2), 3.13 (m, 1 H,
NCH2CH2), 3.75, 3.81, 3.84 (s, 9 H, OMe), 6.32 (s, 1 H, H5), 7.41
(s, 1 H, Hi); syn isomer: δ ϭ 0.90 (t, JH,H ϭ 7.3 Hz, 3 H,
NCH2CH2CH3), 1.98, 2.20 (s, 3 H, OAc), 3.65, 3.67, 3.77 (s, 9 H,
OMe), 5.98 (s, 1 H, H5), 7.69 (s, 1 H, Hi) ppm.
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH](O2CMe)}2{µ-
Ph2P(CH2)4PPh2}] (7): Yield: 0.030 g (76%). M.p. 187.6 °C (dec.).
C56H66N2O12P2Pd2: calcd. C 54.5, H 5.4, N 2.3; found C 54.2, H
5.0, N 2.7. IR (polythene disc): ν(OϪH) ϭ 3399m cmϪ1; ν(Cϭ
N) ϭ 1614m, sh cmϪ1; νas(COO) ϭ 1573s cmϪ1; νs(COO) ϭ 1286s
[Pd{2,3,4-(MeO)3C6HC(H)؍NC(CH3)3}(µ-O2CMe)]2 (24): Yield:
0.37 g (50%). M.p. 121.7 °C. C32H46N2O10Pd2 (831.5): calcd. C
46.2, H 5.6, N 3.4; found C 46.6, H 5.3, N 3.5. IR (polythene disc):
ν(CϭN) ϭ 1601sh, m cmϪ1; νas(COO) ϭ 1570s cmϪ1; νs(COO) ϭ
1
cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 1.61 (s, 3 H, OAc), 2.97
1413s cmϪ1 1H NMR (200 MHz, CDCl3), anti isomer: δ ϭ 1.10
.
[s, 3 H, C(4)ϪOMe], 3.68, 3.88 (s, 6 H, OMe), 3.71, 3.92 (br. s, 4
H, -CH2), 5.73 (d, JP,H ϭ 5.8 Hz, 1 H, H5), 8.25 (d, JP,H ϭ 7.3 Hz,
1 H, Hi) ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 32.8 (s)
ppm. FAB-MS: m/z ϭ 769 [M Ϫ 2OAc Ϫ L Ϫ Pd]ϩ.
[s, 9 H, NC(CH3)3], 2.04 (s, 3 H, OAc), 3.66, 3.72, 3.86 (s, 9 H,
OMe), 6.13 (s, 1 H, H5), 7.79 (s, 1 H, Hi),; syn isomer: δ ϭ 1.18 [s,
9 H, NC(CH3)3], 1.94, 1.98 (s, 3 H, OAc), 3.95, 3.67, 3.77 (s, 9 H,
OMe), 6.02 (s, 1 H, H5), 8.00 (s, 1 H, Hi) ppm.
Preparation
of
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}-
Preparation of [Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}(µ-Cl)]2
(3): A solution of 2 (0.310 g, 0.384 mmol) in 15 cm3 of acetone was
treated with a saturated solution of NaCl in ca. 20 cm3 of water.
The yellow precipitate formed was filtered off, washed with water
and dried under vacuum. Yield 0.24 g (84%). M.p. 215.1 °C (dec.).
C24H32Cl2N2O8Pd2 (760.2): calcd. C 37.9, H 4.2, N 3.7; found C
37.7, H 4.8, N 3.6. IR (nujol mull): ν(OϪH) ϭ 3487m cmϪ1; ν(Cϭ
(Cl)(PPh3)] (8): PPh3 (0.074 g, 0.28 mmol) was added to a suspen-
sion of 3 (0.108 g, 0.14 mmol) in acetone (15 cm3). The mixture
was stirred for 12 h and the solvent was then removed to give a
white solid which was recrystallised from dichloromethane/hexane.
Yield: 0.12 g (66%). M.p. 199.8 °C (dec.). C30H31ClNO4PPd
(642.4): calcd. C 56.1, H 4.9, N 2.2; found C 56.6, H 4.5, N 2.1.
IR (nujol mull): ν(OϪH) ϭ 3365m cmϪ1; ν(CϭN) ϭ 1619s cmϪ1
.
N) ϭ 1605s cmϪ1 1H NMR (200 MHz, [D6]DMSO): δ ϭ 3.31,
.
1H NMR (200 MHz, CDCl3): δ ϭ 2.82 [s, 3 H, C(4)ϪOMe], 3.2
(br. s, 1 H, OH), 3.70, 3.95 (s, 6 H, OMe), 4.03 (m, 4 H, CH2), 5.74
(d, JP,H ϭ 6.3 Hz, 1 H, H5), 8.38 (d, JP,H ϭ 8.3 Hz, 1 H, Hi) ppm.
13C{1H} NMR: (50.28 MHz, CDCl3): δ ϭ 62.9, 61.8 (C8, C9),
61.8, 60.7, 55.2 (OCH3), 118.0 (d, JP,C ϭ 12.1 Hz, C5), 133.3 (C1),
154.4 (d, JP,C ϭ 5.4 Hz, C6), 154.0, 152.0, 137.5 (C2, C3, C4), 173.1
(d, JP,C ϭ 2.8 Hz, CϭN). P-phenyl: δ ϭ 128.1 (d, JP,C ϭ 11.3 Hz,
Cm), 130.1 (d, JP,C ϭ 50.4 Hz, Ci), 135.4 (d, JP,C ϭ 12.1 Hz, Co),
130.8 (d, JP,C ϭ 2.1 Hz, Cp) ppm. 31P{1H} NMR (80.9 MHz,
CDCl3): δ ϭ 43.0 (s) ppm. FAB-MS: m/z ϭ 606 [M Ϫ Cl]ϩ.
3.62 (br. s, 4 H, -CH2), 3.67, 3.76, 3.84 (s, 9 H, OMe), 4.71 (br. s,
1 H, OH), 7.51 (s, 1 H, H5), 8.08 (s, 1 H, Hi). FAB-MS: m/z ϭ 785
[M ϩ Na]ϩ.
Preparation
of
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}-
(O2CMe)(PPh3)] (4): PPh3 (0.014 g, 0.05 mmol) was added to a
suspension of 2 (0.023 g, 0.03 mmol) in acetone (15 cm3). The mix-
ture was stirred for 12 h and the solvent was then removed to give a
white solid which was recrystallised from dichloromethane/hexane.
Yield: 0.029 g (83%). M.p. 182.5 °C. C32H34NO6PPd (666.0): calcd.
C 57.7, H 5.1, N 2.1; found C 57.6, H 4.8, N 2.3. IR (polythene
Compounds 10, 11, 12 and 13 were synthesised similarly, using a
cyclometallated complex/diphosphane molar ratio of 1:1, as yel-
low solids.
disc): ν(OϪH)
νas(COO) ϭ 1570s cmϪ1; νs(COO) ϭ 1290s cmϪ1
(200 MHz, CDCl3): δ ϭ 1.31 (s, 3 H, OAc), 2.88 [s, 3 H,
ϭ
3400m cmϪ1
;
ν(CϭN)
ϭ
1613s cmϪ1
1H NMR
;
.
C(4)ϪOMe], 3.92, 3.70 (s, 6 H, OMe), 3.74, 3.89 (br. s, 4 H, -CH2), [{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH](Cl)}2{µ-Ph2P-
5.70 (d, JP,H ϭ 5.8 Hz, 1 H, H5), 8.31 (d, JP,H ϭ 7.8 Hz, 1 H, Hi)
(CH2)3PPh2}] (10): Yield: 2.7 mg (76%). M.p. 182.6 °C (dec.).
2398
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
C51H58Cl2N2O8P2Pd2 (1172.7): calcd. C 52.2, H 5.0, N 2.4; found
4.2 Hz, CϭN); P-phenyl: δ ϭ 129.1 (d, JP,C ϭ 10.6 Hz, Cm), 131.8
(d, JP,C ϭ 2.9 Hz, Cp), 134.5 (d, JP,C ϭ 12.1 Hz, Co) ppm. 31P{1H}
C 52.4, H 4.9, N 2.5. IR (nujol mull): ν(OϪH) ϭ 3420m cmϪ1
;
1
ν(CϭN) ϭ 1613s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 2.88 [s, NMR (80.9 MHz, CDCl3): δ ϭ 36.1 (s) ppm. FAB-MS: m/z ϭ 606
3 H, C(4)ϪOMe], 3.67, 3.92 (s, 6 H, OMe), 3.96 (br. s, 4 H, -CH2),
[M Ϫ ϭ 116.2
CF3SO3]ϩ. Specific molar conductivity: Λm
5.74 (d, JP,H ϭ 6.3 Hz, 1 H, H5), 8.26 (d, JP,H ϭ 8.3 Hz, 1 H, Hi) ohmϪ1·cm2·molϪ1 (in acetonitrile).
ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 33.4 (s) ppm. FAB-
Compound 14 was obtained following a similar procedure using
complex 11 as starting material.
MS: m/z ϭ 1136 [MH Ϫ Cl]ϩ, 1103 [MH Ϫ 2Cl]ϩ, 756 [MH Ϫ
2Cl Ϫ L Ϫ Pd]ϩ.
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH]}2{µ-Ph2P(CH2)4-
PPh2}][CF3SO3]2 (14): Yield 0.024 g (63%). M.p. 173.5 °C (dec.).
C54H60F6N2O14P2Pd2S2 (1413.9): calcd. C 45.9, H 4.3, N 2.0; found
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH](Cl)}2{µ-Ph2P-
(CH2)4PPh2}] (11): Yield: 41 mg (79%). M.p. 148.9 °C (dec.).
C52H60Cl2N2O8P2Pd2 (1186.7): calcd. C 52.6, H 5.1, N 2.4; found
C 45.7, H 4.3, N 2.0. IR (nujol mull): ν(OϪH) ϭ 3250m cmϪ1
;
C 52.7, H 5.3, N 2.1. IR (nujol mull): ν(OϪH) ϭ 3426m cmϪ1
;
ν(CϭN) ϭ 1619s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 2.99 [s,
3 H, C(4)ϪOMe], 3.70, 3.94 (s, 6 H, OMe), 3.87, 4.19 (br. s, 4 H, -
CH2), 5.63 (d, JP,H ϭ 5.4 Hz, 1 H, H5), 6.89 (br. s, 1 H, OH),
8.24 (d, JP,H ϭ 9.3 Hz, 1 H, Hi) ppm. 13C{1H} NMR (50.28 MHz,
CDCl3): δ ϭ 66.3, 57.5 (C8, C9), 61.9, 60.7, 55.4 (OCH3), 117.1
(d, JP,C ϭ 11.3 Hz, C5), 138.2 (C1), 146.7 (d, JP,C ϭ 2.8 Hz, C6),
155.1, 154.9, 156.6 (C2, C3, C4), 170.2 (d, JP, C ϭ 2.8 Hz, CϭN);
1
ν(CϭN) ϭ 1614s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 2.88 [s,
3 H, C(4)ϪOMe], 3.70, 3.92 (s, 6 H, OMe), 4.01 (br. s, 4 H, -CH2),
5.79 (d, JP,H ϭ 5.8 Hz, 1 H, H5), 8.32 (d, JP,H ϭ 7.8 Hz, 1 H, Hi)
ppm. 13C{1H} NMR (50.28 MHz, CDCl3): δ ϭ 62.6, 60.4 (C8, C9),
61.8, 60.7, 55.1 (OCH3), 117.4 (d, JP,C ϭ 12.1 Hz, C5), 133.2 (d,
1
J
P,C ϭ 1.4 Hz, C1), 154.5 (d, JP,C ϭ 6.5 Hz, C6), 153.7, 152.1, 137.5
(C2, C3, C4), 172.6 (d, JP,C ϭ 4.2 Hz, CϭN); P-phenyl: δ ϭ 128.6
(d, JP,C ϭ 10.1 Hz, Cm), 130.8 (Cp), 130.0 (d, JP,C ϭ 46.8 Hz, Ci),
P-phenyl: δ ϭ 129.1 (d, JP,C ϭ 10.6 Hz, Cm), 131.6 (d, JP,C
ϭ
2.1 Hz, Cp), 133.8 (d, JP,C ϭ 12.1 Hz, Co);. P(CH2)4P: δ ϭ 27.4 (d,
JP,C ϭ 29.1 Hz, PCH2CH2), 26.2 (d, JP,C ϭ 17.1 Hz, PCH2CH2)
ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 30.2 (s) ppm. FAB-
MS: m/z ϭ 1265 [M Ϫ CF3SO3]ϩ, 770 [MH Ϫ L Ϫ Pd Ϫ
133.9 (d, JP,C ϭ 12.1 Hz, Co); P(CH2)4P: δ ϭ 29.3 (d, JP,C
ϭ
33.3 Hz, PCH2CH2), 26.1 (d, JP,C ϭ 16.3 Hz, PCH2CH2) ppm.
31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 33.9 (s) ppm. FAB-MS:
m/z ϭ 770 [MH Ϫ 2Cl Ϫ L Ϫ Pd]ϩ.
2CF3SO3]ϩ. Specific molar conductivity: Λm
ohmϪ1·cm2·molϪ1 (in acetonitrile).
ϭ
237.1
[{Pd[2,3,4-(MeO)3 C6 HC(H)؍NCH2 CH2 OH](Cl)}2 {µ-
Ph2PC5H4FeC5H4PPh2}] (12): Yield: 74 mg (71%). M.p. 168.4 °C
(dec.). C58H60Cl2FeN2O8P2Pd2 (1314.6): calcd. C 53.0, H 4.6, N
2.1; found C 52.7, H 5.0, N 2.3. IR (nujol mull): ν(OϪH) ϭ 3399m
Preparation
of
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}-
{PPh2(CH2)2PPh2-P,P}][ClO4] (15): PPh2(CH2)2PPh2 (0.067 g,
0.17 mmol) was added to a suspension of 3 (0.064 g, 0.08 mmol) in
acetone (20 cm3). The mixture was stirred for 1 h, after which an
excess of sodium perchlorate was added. The mixture was stirred
for a further 4 h, and then the complex was precipitated out by
addition of water, filtered off and dried in vacuo. Recrystallization
from dichloromethane/hexane gave the final compound as a yellow
solid. Yield: 0.11 g (80%). C38H40ClNO8P2Pd (842.5): calcd. C
54.2, H 4.8, N 1.7; found C 53.9, H 4.6, N 1.7. IR (nujol mull):
1
cmϪ1; ν(CϭN) ϭ 1614s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ
2.85 [s, 3 H, C(4)ϪOMe], 3.74, 3.96 (s, 6 H, OMe), 4.03 (br. s, 4
H, -CH2), 5.22, 4.53 (br. s, 4 H, Hferr.), 5.76 (d, JP,H ϭ 6.3 Hz, 1
H, H5), 8.36 (d, JP,H ϭ 8.3 Hz, 1 H, Hi) ppm. 31P{1H} NMR
(80.9 MHz, CDCl3): δ ϭ 31.7 (s) ppm. FAB-MS: m/z ϭ 898 [M Ϫ
2Cl Ϫ L Ϫ Pd]ϩ.
[{Pd[2,3,4-(MeO)3C6HC(H)؍NCH2CH2 OH]}2(µ-Cl)(µ-
Ph2PCH2PPh2)][Cl] (13): Yield: 7.9 mg (65%). M.p. 145.6 °C (dec.).
C49H54Cl2N2O8P2Pd2 (1144.6): calcd. C 51.4, H 4.8, N 2.4; found
C 51.0, H 5.1, N 2.7. IR (nujol mull): ν(OϪH) ϭ 3514, 3441m
1
ν(OϪH) ϭ 3555, 3488m cmϪ1; ν(CϭN) ϭ 1606s cmϪ1. H NMR
(200 MHz, CDCl3): δ ϭ 2.97 [s, 3 H, C(4)ϪOMe], 3.73, 3.96 (s, 6
H, OMe), 2.91, 3.42 (br. s, 4 H, -CH2), 5.93 (dd, JP,H ϭ 8.8, 5.8 Hz,
1 H, H5), 8.50 (d, JP,H ϭ 8.3 Hz, 1 H, Hi) ppm. 13C{1H} NMR
(50.28 MHz, CDCl3): δ ϭ 63.6, 59.3 (C8, C9), 62.1, 60.8, 55.5
1
cmϪ1; ν(CϭN) ϭ 1613s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ
2.88 [s, 3 H, C(4)ϪOMe], 3.67, 3.91 (s, 6 H, OMe), 3.99 (br. s, 4
H, -CH2), 4.70 (m, 2 H, PCH2P), 5.50 (d, JP,H ϭ 6.3 Hz, 1 H, H5),
8.24 (d, JP,H ϭ 8.3 Hz, 1 H, Hi) ppm. 31P{1H} NMR (80.9 MHz,
CDCl3): δ ϭ 30.2 (s) ppm. FAB-MS: m/z ϭ 1109 [M Ϫ Cl]ϩ, 728
[M Ϫ 2Cl Ϫ L Ϫ Pd]ϩ. Specific molar conductivity: Λm ϭ 175.1
ohmϪ1·cm2·molϪ1 (in acetonitrile).
(OCH3), 117.5 (dd, JP,C ϭ 12.1, 3.5 Hz, C5), 138.0 (d, JP,C
ϭ
1.4 Hz, C1), 156.0 (dd, JP,C ϭ 12.0, 5.6 Hz, C6), 164.0, 164.6, 153.6
(C2, C3, C4), 179.4 (d, JP,C ϭ 4.5 Hz, CϭN); P-phenyl: δ ϭ 127.3,
126.2 (d, JP,C ϭ 36.9, 50.4 Hz, Ci), 129.9, 129.8 (d, JP,C ϭ 10.6,
11.3 Hz, Cm), 132.5, 132.7 (d, JP,C ϭ 2.8 Hz, Cp), 134.1, 133.4 (d,
JP,C ϭ 12.1, 12.7 Hz, Co); P(CH2)2P: δ ϭ 30.5 (dd, JP,C ϭ 35.1,
18.0 Hz, PCH2CH2P), 26.1 (dd, JP,C ϭ 29.8, 9.2 Hz, PCH2CH2P)
Preparation
of
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}-
ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 43.0 (d, JP,P
ϭ
(PPh3)][F3CSO3] (9): A suspension of 4 (0.093 g, 0.14 mmol) in
acetone (15 cm3) was treated with silver triflate (0.037 g,
0.14 mmol) and stirred for 2 h. The solution was filtered through
Celite to eliminate the AgCl precipitate and then the solvent was
removed to give a yellow solid which was recrystallised from dichlo-
romethane/hexane. Yield: 0.095 g (44%). M.p. 223.7 °C (dec.).
C31H31F3NO7PPdS (756.0): calcd. C 49.2, H 4.1, N 1.8; found C
25.4 Hz), 61.0 (d) ppm. FAB-MS: m/z ϭ 742 [M Ϫ ClO4]ϩ. Specific
molar conductivity: Λm ϭ 142.8 ohmϪ1·cm2·molϪ1 (in acetonitrile).
Compound 16 was obtained following a similar procedure as a
yellow, air stable, solid.
[Pd{2,3,4-(MeO)3C6HC(H)؍NCH2CH2OH}{(PPh2CH2CH2)2-
PPh-P,P,P}][ClO4] (16): Yield: 7.8 mg (59%). C46H49ClNO8P3Pd
49.6, H 4.0, N 1.9. IR (nujol mull): ν(OϪH) ϭ 3245m cmϪ1; ν(Cϭ
N) ϭ 1625s cmϪ1. H NMR (200 MHz, CDCl3): δ ϭ 2.91 [s, 3 H, (978.7): calcd. C 56.4, H 5.0, N 1.4; found C 56.9, H 4.6, N 1.5.
1
C(4)ϪOMe], 3.73, 3.97 (s, 6 H, OMe), 3.89, 4.13 (br. s, 4 H, -CH2),
5.62 (d, JP,H ϭ 4.9 Hz, 1 H, H5), 7.02 (t, JHO,CH ϭ 5.6 Hz, 1 H,
OH,], 8.27 (d, JP,H ϭ 9.8 Hz, 1 H, Hi) ppm.2 13C{1H} NMR
IR (nujol mull): ν(OϪH) ϭ 3501m cmϪ1; ν(CϭN) ϭ 1614s cmϪ1
1H NMR (200 MHz, CDCl3): δ ϭ 2.80 [s, 3 H, C(4)ϪOMe], 3.71,
3.88 (s, 6 H, OMe), 2.82, 3.36 (br. s, 4 H, -CH2), 5.25 (dd, JP,H
.
ϭ
(50.28 MHz, CDCl3): δ ϭ 67.7, 56.8 (C8, C9), 61.9, 60.8, 55.5 8.8, 2.4 Hz, 1 H, H5), 8.40 (s, 1 H, Hi) ppm. 13C{1H} NMR
(OCH3), 117.6 (d, JP,C ϭ 10.6 Hz, C5), 135.9 (C1), 144.4 (d, JP,C ϭ (50.28 MHz, CDCl3): δ ϭ 167.3 (d, JP,C ϭ 5.7 Hz, CϭN), 163.3,
5.7 Hz, C6), 155.0, 155.1, 152.8 (C2, C3, C4), 169.3 (d, JP,C
ϭ
161.1, 154.1 (C2, C3, C4), 154.0 (m, C6), 116.3 (m, C5), 62.8, 61.6
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401
2399

´
A. Fernandez, J. M. Vila et al.
FULL PAPER
[12]
[13]
[14]
´
J. M. Vila, M. T. Pereira, J. M. Ortigueira, J. J. Fernandez, A.
(C8, C9), 62.1, 60.9, 54.8 (OCH3); P(CH2)2P: δ ϭ 32.3, 25.9 (m)
ppm. 31P{1H} NMR (80.9 MHz, CDCl3): δ ϭ 44.5 (d, JP,P ϭ 26.3),
86.0 (t) ppm. FAB-MS: m/z ϭ 979 [M]ϩ, 877 [M Ϫ ClO4]ϩ.
Specific molar conductivity,: Λm ϭ 125.9 ohmϪ1 cm2 molϪ1 (in
acetonitrile).
´
´
Fernandez, M. Lopez-Torres, H. Adams, Organometallics 1999,
18, 5484Ϫ5487.
´
´
B. Teijido, A. Fernandez, M. Lopez-Torres, S. Castro-Juiz, A.
Suarez, J. M. Ortigueira, J. M. Vila, J. J. Fernandez, J. Or-
ganomet. Chem. 2000, 598, 71Ϫ79.
M. Lousame, A. Fernandez, M. Lopez-Torres, D. Vazquez-
Garcıa, J. M. Vila, A. Suarez, J. M. Ortigueira, J. J. Fernandez,
´
´
´
´
´
X-ray Crystallographic Study: Three-dimensional, room temper-
ature X-ray data were collected on a Siemens Smart CCD diffracto-
meter by the ω scan method using graphite-monochromated Mo-
Kα radiation. All the measured reflections were corrected for Lor-
entz and polarisation effects and for absorption by semi-empirical
methods based on symmetry equivalent and repeated reflections.
The structures were solved by direct methods and refined by full-
matrix least-squares on F2. Hydrogen atoms were included in calcu-
lated positions (except the -OH hydrogens which were located in a
difference Fourier map) and refined in a riding mode. The O(6),
O(7) and O(8) oxygen atoms of the perchlorate counterion in com-
plex 16 were found to be disordered over two positions (with occu-
pancies of approximately 50%). The refinement was carried out
taking into account both components. Refinement converged at a
final R ϭ 0.0776, 0.0460, 0.0294, 0.0412 and 0.0466 (for complexes
2, 8, 9, 15 and 16, respectively, observed data, F) and wR2 ϭ 0.1690,
0.1992, 0.0776, 0.1137 and 0.0829 (for complexes 2, 8, 9, 15 and
16, respectively, unique data, F2), with allowance for the thermal
anisotropy of all non-hydrogen atoms. The structure solution and
refinement were carried out using the program package SHELX-
97.[60]
´
´
´
Eur. J. Inorg. Chem. 2000, 2055Ϫ2062.
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
G. J. Gainsford, R. Mason, J. Organomet. Chem. 1974, 80,
395Ϫ406.
J. Selbin, K. Abboud, S. F. Watkins, M. A. Gutierrez, F. R.
Fronczek, J. Organomet. Chem. 1983, 241, 259Ϫ268.
A. Albinati, P. S. Pregosin, R. Ruedi, Helv. Chim. Acta 1985,
68, 2046Ϫ2061.
R. Ruger, W. Rittner, P. G. Jones, W. Isenberg, G. M. Sheldrick,
Angew. Chem. Int. Ed. Engl. 1981, 93, 389Ϫ390.
E. Wehman, G. van Koten, J. T. B. H. Jastrzebski, H. Ossor,
M. Pfeffer, J. Chem. Soc., Dalton Trans. 1988, 2975Ϫ2981.
G. Balavoine, J. C. Clinet, P. Zerbib, K. Boubekeur, J. Or-
ganomet. Chem. 1990, 389, 259Ϫ275.
M. Ohff, A. Ohff, D. Milstein, Chem. Commun. 1999,
357Ϫ358.
J. L. Garcia-Ruano, I. Lopez-Solera, J. R. Masaguer, C. Nav-
arro-Ranninger, J. H. Rodriguez, S. Martinez-Carrera, Organo-
metallics 1992, 11, 3013Ϫ3018.
A. Boehm, K. Polborn, K. Suenkel, W. Beck, Z. Naturforsch.,
Teil B 1998, 53, 448Ϫ458.
M. R. Churchill, H. J. Wasserman, G. J. Young, Inorg. Chem.
1980, 19, 762Ϫ770.
W. A. Herrmann, C. Brossmer, K. Ofele, C. P. Reisinger, T.
Priermeier, M. Beller, H. Fischer, Angew. Chem. Int. Ed. Engl.
1995, 34, 1844Ϫ1847.
W. A. Herrmann, V. P. W. Bohm, C. P. Reisinger, J. Organomet.
Chem. 1999, 576, 23Ϫ41.
D. Freiesleben, K. Polborn, C. Robl, K. Sunkel, W. Beck, Can.
J. Chem. 1995, 73, 1164Ϫ1174.
J. M. Vila, M. Gayoso, M. T. Pereira, M. Lopez-Torres, J. J.
Fernandez, A. Fernandez, J. M. Ortigueira, J. Organomet.
Chem. 1997, 532, 171Ϫ180.
[23]
[24]
[25]
CCDC-178027 (2), -178028 (8), -178029 (9), -178030 (15) and
-178031 (16) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB2
1EZ, UK; Fax: (internat.) ϩ44Ϫ1223/336Ϫ033; E-mail:
deposit@ccdc.cam.ac.uk].
[26]
[27]
[28]
´
´
´
[29]
[30]
[31]
Acknowledgments
´
´
´
´
A. Fernandez, P. Urıa, J. J. Fernandez, M. Lopez-Torres, A.
Suarez, D. Vazquez-Garcıa, M. T. Pereira, J. M. Vila, J. Or-
´
´
´
´
We thank the Ministerio de Educacion y Cultura (Proyecto PB98-
ganomet. Chem. 2001, 620, 8Ϫ19.
0638-C02-01/02), the Xunta de Galicia (Proyecto
PGIDT99PXI20907B) and the Universidad de la Corun˜a for finan-
cial support.
´
J. M. Vila, M. T. Pereira, J. M. Ortigueira, M. Lopez-Torres,
D. Lata, M. Gran˜a, A. Suarez, J. J. Fernandez, A. Fernandez,
J. Chem. Soc., Dalton Trans. 1999, 4193Ϫ4201.
D. Vazquez-Garcıa, A. Fernandez, J. J. Fernandez, M. Lopez-
Torres, A. Suarez, J. M. Ortigueira, J. M. Vila, H. Adams, J.
´
´
´
´
´
´
´
´
´
[1]
I. Omae, in Organometallic Intramolecular-Coordination Com-
Organomet. Chem. 2000, 595, 199Ϫ207.
pounds, Elsevier Science, Amsterdam-New York, 1986.
V. V. Dunina, O. A. Zalevskaya, V. M. Potapov, Russ. Chem.
[32]
[33]
[34]
[35]
[36]
[37]
[38]
[39]
[40]
[41]
[2]
Y. Ustynyuk, V. A. Chertov, J. V. Barinov, J. Organomet. Chem.
1971, 29, C53.
H. Onoue, I. Moritani, J. Organomet. Chem. 1972, 43,
Rev. 1984, 571, 250Ϫ269.
G. R. Newkome, W. E. Puckett. W. K. Gupta, G. E. Kiefer,
[3]
431Ϫ436.
Chem. Rev. 1986, 86, 451Ϫ489.
[4]
H. Onoue, K. Minami, K. Nakagawa, Bull. Chem. Soc. Jpn.
1970, 43, 3480Ϫ3485.
K. Nakamoto, IR and Raman Spectra of Inorganic and Coor-
dination Compounds, 5th ed., Wiley & Sons, New York 1997.
A. D. Ryabov, Chem. Rev. 1990, 90, 403Ϫ424.
[5]
M. Pfeffer, Recl. Trav. Chim. Pays-Bas 1990, 109, 567Ϫ576.
[6]
M. Albrecht, G. van Kotten, Angew. Chem. Int. Ed. 2001, 40,
3750Ϫ3781.
[7]
´
F. Zamora, S. Laguna, P. Amo-Ochoa, L. A. Martınez-Cruz,
J. Dupont, M. Pffefer, J. Spencer, Eur. J. Inorg. Chem. 2001,
1917Ϫ1927.
M. Pfeffer, J. P. Sutter, M. A. Rotteveel, A. de Cian, J. Fischer,
A. Vegas, J. Organomet. Chem. 1996, 522, 97Ϫ103.
[8]
´
C. Navarro-Ranninger, F. Zamora, L. A. Martınez-Cruz, R.
Isea, J. R. Masaguer, J. Organomet. Chem. 1996, 518, 29Ϫ36.
A. Suarez, J. M. Vila, M. T. Pereira, E. Gayoso, M. Gayoso,
Synth. React. Inorg. Met.-Org. Chem. 1990, 20, 1425Ϫ1440.
K. Hiraki, Y. Fuchita, H. Nakaya, S. Takakura, Bull. Chem.
Soc. Jpn. 1979, 52, 2531Ϫ2534.
L. Pauling, The Nature of the Chemical Bond, 3rd ed., Cornell
University Press, New York, 1960.
J. M. Vila, M. Gayoso, M. T. Pereira, M. Lopez-Torres, G.
Alonso, J. J. Fernandez, J. Organomet. Chem. 1993, 445,
Tetrahedron 1992, 48, 2427Ϫ2440.
[9]
´
´
´
C. Navarro-Ranninger, I. Lopez-Solera, J. Rodrıguez, J. L.
´
Garcıa-Ruano, P. R. Raithby, J. R. Masaguer, C. Alonso, J.
Med. Chem. 1993, 36, 3795Ϫ3801.
[10]
[11]
´
C. Navarro-Ranninger, I. Lopez-Solera, V. M. Gonzalez, J. M.
´
Perez, A. Alvarez-Valdes, A. Martin, P. R. Raithby, J. R. Masa-
guer, C. Alonso, Inorg. Chem. 1996, 35, 5181Ϫ5187.
´
´
´
´
M. Lopez-Torres, A. Fernandez, J. J. Fernandez, S. Castro-Juiz,
´
´
A. Suarez, J. M. Vila, M. T. Pereira, Organometallics 2001,
20, 1350Ϫ1353.
287Ϫ294.
2400
Eur. J. Inorg. Chem. 2002, 2389Ϫ2401

A syn-Acetato-Bridged Dinuclear Cyclometallated Palladium Complex
FULL PAPER
[42]
[43]
[44]
[45]
[46]
[52]
´
R. Bosque, J. Granell, J. Sales, M. Font-Bardia, X. Solans, J.
Organomet. Chem. 1994, 453, 147Ϫ154.
F. Cecconi, C. A. Ghilardi, S. Midollini, S. Moneti, A. Orland-
ini, G. Scapacci, J. Chem. Soc., Dalton Trans. 1989, 211Ϫ216.
J. Granell, D. Sainz, J. Sales, X. Solans, M. Font-Altaba, J.
Chem. Soc., Dalton Trans. 1986, 1785Ϫ1790.
J. Granell, J. Sales, J. Vilarrasa, J. P. Declercq, G. Germain, C.
Miravilles, X. Solans, J. Chem. Soc., Dalton Trans. 1983,
2441Ϫ2446.
[53]
[54]
´
R. Bosque, J. Granell, J. Sales, M. Font-Bardia, X. Solans, Or-
ganometallics 1995, 14, 1393Ϫ1404.
J. Vicente, A. Arcas, D. Bautista, P. G. Jones, Organometallics
1997, 16, 2127Ϫ2138.
J. Vicente, J. Abad, A. D. Frankland, M. C. Ramırez de Arel-
´
[55]
[56]
[57]
[58]
[59]
[60]
Z. Taira, S. Yamazaki, Bull. Chem. Soc. Jpn. 1986, 59,
lano, Chem. Eur. J. 1999, 5, 3066Ϫ3075.
649Ϫ650.
J. Albert, R. Bosque, J. M. Cadena, S. Delgado, J. Granell, J.
Organomet. Chem. 2001, 634, 83Ϫ89.
W. J. Geary, Coord. Chem. Rev. 1971, 7, 81Ϫ122.
L. A. Villanueva, K. Abboud, J. M. Boncella, Organometallics
1991, 10, 2969Ϫ2972.
D. Onggo, D. C. Craig, A. D. Rae, H. A. Goodwin, Aust. J.
Chem. 1991, 44, 219Ϫ231.
O. Schlager, K. Wieghardt, B. Nuber, Inorg. Chem. 1995, 34,
6449Ϫ6455.
[47]
[48]
´
C. Cativiela, L. R. Falvello, J. C. Gines, R. Navarro, E. P. Urri-
olabeitia, New J. Chem. 2001, 25, 344Ϫ352.
[49]
P. S. Pregosin and R. W. Kuntz, 31P and 13C NMR of Transition
Metal Phosphane Complexes (Eds.: P. Diehl, E. Fluck and R.
Kosfeld), Vol. 16, Springer, Berlin, 1979.
D. D. Perrin, W. L. F. Armarego, Purification of Laboratory
Chemicals, 4th ed., Butterwort-Heinemann, 1996.
G. M. Sheldrick, SHELX-97, An integrated system for solving
and refining crystal structures from diffraction data, University
of Gottingen, Germany 1997.
[50]
[51]
´
J. M. Vila, M. Gayoso, A. Fernandez, H. Adams, N. A. Bailey,
J. Organomet. Chem. 1993, 448, 233Ϫ239.
´
´
´
´
M. Lopez-Torres, A. Fernandez, J. J. Fernandez, A. Suarez, M.
T. Pereira, J. M. Ortigueira, J. M. Vila, H. Adams, Inorg. Chem.
2001, 40, 4583Ϫ4587.
Received January 29, 2002
[I02051]
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2401