Synthesis and characterization of heterotrinuclear complexes of nickel and palladium with pyridinecarboxylate as bridging ligands

Article abstract of DOI:10.1002/ejic.200500123

Heterotrinuclear pyridinecarboxylate complexes of nickel(II) and palladium(II) of the types [Ni(mcN₃)(pyridine-carboxylate)] ₂{μ-[Pd(C₆F₅)₂]}(PF ₆)₂ [mcN₃ = 2,4,4-trim

Full text of DOI:10.1002/ejic.200500123

FULL PAPER
Synthesis and Characterization of Heterotrinuclear Complexes of Nickel and
Palladium with Pyridinecarboxylate as Bridging Ligands
José Ruiz,*[a] María Dolores Santana,*[a] Abel Lozano,[a] Consuelo Vicente,[a]
Gabriel García,[a] Gregorio López,[a] José Pérez,[b] and Luis García[b]
Keywords: Palladium / Nickel / Pyridinecarboxylate / Heterotrinuclear complexes / Mononuclear complexes
Heterotrinuclear pyridinecarboxylate complexes of nickel(II
)
monomeric pyridinecarboxylic acid/ester complexes of palla-
dium have also been prepared. The crystal structures of two
precursors [Ni(Me4-mcN3)(NC5H4-3-COO)]PF6 and cis-
[Pd(C6F5)2(NC5H4-4-CH2COOCH3)2] have been established
by X-ray diffraction.
and palladium(II of the types [Ni(mcN3)(pyridine-
)
carboxylate)]2{μ-[Pd(C6F5)2]}(PF6)2 [mcN3 = 2,4,4-trimethyl-
1,5,9-triazacyclododec-1-ene (Me3-mcN3) or 2,4,4,9-tet-
ramethyl-1,5,9-triazacyclododec-1-ene (Me4-mcN3)] have
been prepared by two different routes. The corresponding
monomeric pyridinecarboxylate complexes of nickel and the
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
Results and Discussion
Synthesis and Characterization of Monomeric
Pyridinecarboxylate ligands tend to bind metal ions with
both, pyridine and carboxylate groups to form extended
networks, where the carboxylate groups balance the metal
charges.[1–6] The deliberate, stepwise and controlled synthe-
sis of molecular squares and dinuclear macrocycles using
pyridinecarboxylates as spacers has been recently reported
by Hor et al.[7]
The versatile carboxylate anion can adopt a wide range
of bonding modes including monodentate, symmetric and
asymmetric chelating and bidentate and monodentate
bridging.[8] It is generally agreed that the carboxylate com-
plexes of the 3d elements, including several examples of
nickel derivatives, play an important role in biochemistry.[9]
In this paper we report the preparation by two different
routes and the spectroscopic behavior of heterotrinuclear
pyridinecarboxylate complexes of nickel and palladium in
which the two nickel(ii) ions are in a pentacoordinate envi-
ronment. The corresponding monomeric pyridinecarboxyl-
ate complexes of nickel and the monomeric pyridinecarbox-
ylic acid/ester complexes of palladium have also been pre-
pared.
Pyridinecarboxylate Complexes of Nickel(II
)
The reaction between [Ni(mcN3)(μ-OH)]2(PF6)2 [mcN3 =
2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me3-mcN3)
or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me4-
mcN3)] and carboxylic acids [HA = isonicotinic (Hisonic)
or nicotinic (Hnic) acid] leads to the formation of the car-
boxylate complexes [Ni(mcN3)(A)](PF6) 1–4 shown in
Scheme 1.
The acid-base reaction occurs at room temperature in
acetone with the concomitant liberation of water. This syn-
thetic method has previously been used for the preparation
of pentacoordinate nickel(ii) complexes containing N,S-do-
nor,[10] oxamidate,[11] hydroxamate,[12] and pyridonate li-
gands,[13] as well as phosphate esters and phosphinate deriv-
atives.[14]
Complexes 1–4 are air-stable both in the solid state and
in solution. They have been characterized by partial ele-
mental analyses, FAB+ mass spectrometry and spectro-
1
scopic (IR, UV/Vis, and H NMR) methods. The IR spec-
tra of complexes 1–4 show characteristic absorptions for the
mcN3 ligands:[12,14] 3287–3121 cm–1 for ν(N–H), ca.
˜
1660 cm–1 for ν(C=N), and two strong bands as a result of
˜
–
the PF6 ion at 840 and 560 cm–1. The κ2-coordination
[a] Departamento de Química Inorgánica, Universidad de Murcia,
30071 Murcia, Spain
mode in compounds 1–4 is revealed by the IR spectra,
which contain symmetric OCO stretching bands at ca.
1550 cm–1.[15,16] The κ2-coordination mode in 4 was authen-
ticated by an X-ray crystal structure determination (vide
infra). The electronic spectra of 1–4 are quite similar and
Fax: +34-968-364-148
E-mail: jruiz@um.es
dsl@um.es
[b] Departamento de Ingeniería Minera, Geológica y Cartográfica.
Área de Química Inorgánica, Universidad Politécnica de Car-
tagena,
30203 Cartagena, Spain
show two d-d transitions in acetone solution with λmax Ϸ
Eur. J. Inorg. Chem. 2005, 3049–3056
DOI: 10.1002/ejic.200500123
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3049

J. Ruiz, M. D. Santana et al.
FULL PAPER
Scheme 1. Monomeric nickel complexes.
63 (ca. 80 m–1 cm–1) and 390 nm (ca. 200 m–1 cm–1) which
could be assigned to 3B1(F) Ǟ 3E(F) and 3B1(F) Ǟ
3A2,3E(P) transitions, respectively. Both λmax values and
molar absorptivities are consistent with a pentacoordinate
environment around the nickel(ii) center.[17]
NMR Spectroscopic Study of Complexes 1–4
1
All of the complexes exhibit sharp hyperfine-shifted H
NMR signals in acetone solution in the 370 to –35 ppm
chemical shift range. The 1H NMR spectra of complexes 1–
4 show the resonance line pattern observed for the mcN3
ligands that was assigned on the basis of previous studies
of (macrocycle)nickel complexes[10–14] and from the tem-
perature dependence of the resonances. A representative 1H
NMR spectrum for complex 4 is shown in Figure 1. The
α-methylene proton signals shift downfield whereas the β-
methylene proton signals shift upfield with regard to the
diamagnetic position.[18] Moreover, the signals of the equa-
torial protons are expected to experience larger contact
shifts than those of the axial protons[19] and therefore the
1
Figure 1. H NMR spectra (in [D6]acetone solution at room tem-
perature) of complex 4.
Description of the Crystal Structure of Complex 4
The crystal structure of the cation of complex 4 is shown
most downfield resonances are due to α-CHeq and the most in Figure 3. Selected geometric data are given in Table 1. In
1
upfield ones to β-CHeq. The isotropically shifted H NMR each crystallized cation of complex 4, the nickel atom is
signals observed for the methyl groups [2-Me, 4-Me(a,b), five-coordinate, with a square-pyramid arrangement of the
and 9-Me-N] and phenyl groups of carboxylates can be ini- chelating atoms. The Reedijk τ parameter[21] (τ = 0 and 1
tially assigned by inspection of their peak areas. All the res- for square-pyramidal and trigonal-bipyramidal structures,
onances of the phenyl rings are downfield to TMS in ac- respectively) shows a value of 0.005. The three nitrogen
cordance with a dominant σ-delocalization pattern of spin atoms of the N3 macrocycle are found at the apical position
density, consistent with the ground state of nickel(ii), al- and two adjacent basal ones, whereas the other two basal
though the unpaired electrons could polarize the net spin positions correspond to the O,OЈ-carboxylate group. The
density in the dπ orbitals. A similar behavior has been ob- basal plane is formed by N(1), N(2), O(1), and O(2), with
served elsewhere.[20] Curie plots of proton resonances of an r.m.s. deviation of fitted atoms of 0.0108 Å. The Ni atom
complex 4 in [D6]acetone are shown in Figure 2. These is 0.3054(13) Å above the corresponding basal plane
plots illustrate the general tendency for the contact shifts to towards the apical N(3) atom. The coordinated macrocycle
increase more rapidly at lower temperatures and exhibit a exhibits a chairlike conformation for the two six-membered
temperature dependence closely proportional to T–1.
rings that do not contain the C=N bond. This is the most
3050
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org Eur. J. Inorg. Chem. 2005, 3049–3056

Heterotrinuclear Complexes of Nickel and Palladium with Pyridinecarboxylate as Bridging Ligands
FULL PAPER
dral[22–24] geometry. The bite angle of the carboxylate anion
shows a value of 62.76(8)°. The torsion angle between the
pyridine ring and the nickel-bound carboxylate group is
2.27(8)°. This is the first crystal structure of a pentacoordi-
nate (nicotinato)nickel(ii) complex (3D search using the
Cambridge Structural Database, CSD version 5.25, July
2004 release).
Figure 3. ORTEP drawing of complex 4 showing the atom number-
ing scheme. Displacement ellipsoids are drawn at the 50% prob-
ability level. For clarity hydrogen atoms of the macrocycle are omit-
ted.
Table 1. Selected bond lengths [Å] and angles [°] for complex 4.
Bond lengths
Bond angles
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–O(1)
Ni(1)–O(2)
1.988(2)
2.008(2)
2.044(3)
2.129(2)
2.085(2)
N(1)–Ni(1)–N(2)
N(1)–Ni(1)–N(3)
N(1)–Ni(1)–O(1)
N(1)–Ni(1)–O(2)
N(2)–Ni(1)–N(3)
N(2)–Ni(1)–O(1)
N(2)–Ni(1)–O(2)
N(3)–Ni(1)–O(1)
N(3)–Ni(1)–O(2)
O(2)–Ni(1)–O(1)
92.37(10)
94.91(11)
100.87(9)
157.29(9)
102.68(10)
156.97(9)
98.73(9)
94.93(10)
101.82(10)
62.76(8)
Table 2. Hydrogen bonds for complex 4 [Å and °].
D–H···A
d(D–H) d(H···A) d(D···A) Ͻ(DHA)
Figure 2. Curie plots of proton resonances of complex 4.
N(2)–H(2)···N(4)#1
C(16)–H(16)···O(2)#1
Symmetry transformations used to generate equivalent atoms:
0.93
0.95
2.08
2.44
2.991(4)
3.284(4)
166.3
147.6
frequent conformation in complexes having these macro-
cycles.[13] The Ni–O bond lengths in 4 are close to each
other [2.085(2)–2.129(2) Å]. The carboxylate ligands are
bonded in a symmetric (or almost) chelating mode with a
ΔO = {[Ni–O(2)] – [Ni–O(1)]} value of 0.034 Å. There is a
classical intermolecular hydrogen bonding between N(2)–
H(2) and N(4) of a neighbor cation generated by (–x + 2,
–y + 2, –z) symmetry operation, and a “non-classical” hy-
drogen bonding between C(16)–H(16) and O(2), generated
by the same symmetry operation. The hydrogen bonds of
complex 4 are summarised in Table 2 (see Figure 4). These
bond lengths are comparable to those reported for other
crystallographically characterized nickel carboxylate com-
#1: –x + 2, –y + 2, –z
Figure 4. Hydrogen bonding in complex 4. ORTEP drawing (ellip-
plexes with a distorted square-pyramidal[22] or octahe- soids at 50% probability level) with atom labeling scheme.
Eur. J. Inorg. Chem. 2005, 3049–3056
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3051

J. Ruiz, M. D. Santana et al.
FULL PAPER
Synthesis and Characterization of Monomeric
Pyridinecarboxylic Acid/Ester Complexes of Palladium(II
{NH=CMe2}2],[25] [Pd(C6F5)2{NH=C(OMe)Me}2][35] and
[Pd(C6F5)2(pz···H···pz)] (pz = pyrazolate).[27] The Pd–C6F5
bond lengths are in the range found in the literature for
(pentafluorophenyl)palladium complexes.[36–38] In addition,
there are some interconnections by hydrogen bonds involv-
)
The labile complex cis-[Pd(C6F5)2(PhCN)2] has been
used as starting material for the preparation of several pal-
ladium complexes.[25–28] When cis-[Pd(C6F5)2(PhCN)2][29]
was treated with the pyridinecarboxylic acids NC5H4-4-
COOH (isonicotinic), NC5H4-3-COOH (nicotinic) or
NC5H4-4-CH2COOH (in methanol), complexes 5–7 were
obtained in high yields (Scheme 2). Complexes 5–7 are all
white, air-stable solids. Their IR spectra show the character-
istic absorptions of the C F group (ν = 1630 m, 1490 vs,
˜
6
5
1050 s, 950 vs cm–1)[30] and a split band at ν Ϸ 800 cm–1
˜
assigned to the cis-Pd(C6F5)2 moiety.[31,32] The IR spectra
of 5 and 6 show the expected strong ν(C=O) band at ν Ϸ
˜
1720 cm–1, a frequency that is typical for aromatic carbox-
ylic acids.[33,34] In complex 7 the ν(C=O) band is observed
at ν = 1744 cm–1. The 19F NMR spectra of complexes 5–7
˜
show the presence of two equivalent freely rotating C6F5
rings giving three resonances with relative intensities of
4:2:4 due to the ortho-, para-, and meta-F atoms, respec-
tively. The 1H NMR spectrum of complex 7 shows the
methoxy resonance of the pyridinecarboxylic ester ligands
at δ = 3.66 ppm.
Figure 5. ORTEP drawing of complex 7 showing the atom number-
ing scheme. Displacement ellipsoids are drawn at the 50% prob-
ability level.
Description of the Crystal Structure of Complex 7
Figure 5 depicts the structure of the neutral palladium
complex. Selected bond lengths and angles are given in
Table 3. The coordination around Pd is square-planar. The
N1, N2, C1, and C7 atoms form a perfect plane with the
Pd atom 0.0037(7) Å above this plane. The angle between
the two C6F5 rings is 90.72(7)° and the angle between the
two N-donor ligands is 90.16(5)°. The Pd–N distances lie
within the range reported in complexes containing the
Table 3. Selected bond lengths [Å] and angles [°] for complex 7.
Bond lengths
Bond angles
Pd(1)–C(1)
Pd(1)–C(7)
Pd(1)–N(2)
Pd(1)–N(1)
2.0012(17)
2.0031(17)
2.0866(14)
2.0897(14)
C(1)–Pd(1)–C(7)
90.72(7)
C(1)–Pd(1)–N(2) 178.78(6)
C(7)–Pd(1)–N(2) 88.08(6)
C(1)–Pd(1)–N(1) 91.04(6)
C(7)–Pd(1)–N(1) 178.15(6)
N(2)–Pd(1)–N(1) 90.16(5)
{Pd(C6F5)2N2}
moiety,
such
as
[Pd(C6F5)2-
Scheme 2. Monomeric palladium complexes.
3052
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3049–3056

Heterotrinuclear Complexes of Nickel and Palladium with Pyridinecarboxylate as Bridging Ligands
FULL PAPER
ing some of the para-, meta-, and ortho-fluorine atoms as [Pd(C6F5)2(PhCN)2], which takes place with the concomi-
proton acceptors, with short intermolecular C–H···F dis- tant release of PhCN. The second method is based on the
tances (Table 4).[25,39]
treatment of the monomeric pyridinecarboxylic derivatives
of palladium(ii) 5–7 with the hydroxo complex
[Ni(mcN3)(μ-OH)]2(PF6)2 (mcN3 = Me3-mcN3 or Me4-
mcN3). Complexes 8–12 are air-stable both in the solid state
and in solution. They were characterized by partial elemen-
tal analyses, FAB+ mass spectrometry and spectroscopic
Table 4. Selection of the shorter intermolecular F···H distances [Å]
in complex 7.
F8H25(i)
2.600
2.568
2.565
2.586
2.546
2.577
F10H13(iii)
F9H28A(ii)
F6H17(iv)
F1H21(iv)
F2H22(iv)
1
(IR and H NMR) methods. The IR spectra of complexes
8–12 show characteristic absorptions for the mcN3 li-
gands,[12,14] the absorption of the pyridinecarboxylate li-
gands, the characteristic absorptions of the C6F5 group[30]
i: 2 – x, 2 – y, 2 – z; ii: 0.5 + x, 1.5 – y, –0.5 + z;
iii: 1.5 – x, –0.5 + y, 1.5 – z; iv: 1.5 – x, 0.5 + y, 1.5 – z
and a split band at ν Ϸ 800 cm–1 assigned to the cis-
˜
Pd(C6F5)2 moiety.[31,32] Two strong bands as a result of the
PF6 ion at ν = 840 and 560 cm–1 are also observed.
–
˜
Synthesis and Characterization of Heterotrinuclear
Pyridinecarboxylate Complexes of Nickel(II) and
NMR Study of Complexes 8–12
Palladium(II
)
The 19F NMR spectra of complexes 8–12 show the pres-
Heterotrinuclear pyridinecarboxylate complexes of nick- ence of two equivalent freely rotating C6F5 rings giving
el(ii) and palladium(ii) of the types [Ni(mcN3)(pyridinecar- three resonances with relative intensities of 4:2:4 due to the
boxylate)]2{μ-[Pd(C6F5)2]}(PF6)2 (mcN3 = Me3-mcN3 or ortho-, para-, and meta-F atoms, respectively. The 1H NMR
Me4-mcN3) 8–12 have been prepared by two different spectra of the complexes 8–12 also show relatively sharp
routes (Scheme 3). The first method is based on the reaction and well-resolved resonances for the macrocyclic protons as
of the monomeric pyridinecarboxylate complexes of nick- well as the expected resonance line pattern. The magnitudes
el(ii) [Ni(mcN3)(A)](PF6) 1–4 with the labile complex cis- of these shifts are also similar to those observed for the
Scheme 3. Heterotrinuclear complexes.
Eur. J. Inorg. Chem. 2005, 3049–3056
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3053

J. Ruiz, M. D. Santana et al.
FULL PAPER
corresponding monomeric pyridinecarboxylate derivatives
of nickel (1–4). However, the coordination to the cis-
Pd(C6F5)2 moiety through the nitrogen atom of pyridine-
carboxylate disturbs the spin density into the pyridine ring
and the shifts of pyridinecarboxylate in heterotrinuclear de-
rivatives are in general larger than in monomeric complexes.
The temperature dependence of the shifts of 11 in Figure 6
follows the established pattern, with the shifts moving away
from the diamagnetic position and increasing with T–1.
Experimental Section
General Methods: The C, H, N analyses were performed with a
Carlo Erba model EA 1108 microanalyzer. The H and 19F NMR
1
spectra were recorded with a Bruker AC 200E, Bruker AC 300E or
Bruker AV-400 spectrometer, using SiMe4 or CFCl3 as standards,
respectively. IR spectra were recorded with a Perkin–Elmer 16F PC
FT-IR spectrophotometer using Nujol mulls between polyethylene
sheets. Fast-atom bombardment (FAB) mass spectra were run with
a Fisons VG Autospec spectrometer operating in the FAB+ mode.
The UV/Vis spectra (in acetone) were recorded with a UNICAM
520 spectrophotometer equipped with matched quartz cells in the
300–800 nm range. The chemicals were purchased from Aldrich
and were used without further purification. Solvents were dried
and distilled by general methods before use. The starting com-
pound [{Ni(Me3-mcN3)(μ-OH)}2](PF6)2 and its 9-methyl deriva-
tive,[40,41] as well as cis-[Pd(C6F5)2(PhCN)2][29] were prepared by
procedures described elsewhere.
Preparation of Complexes
Complexes
1 and 3: NC5H4-4-COOH or NC5H4-3-COOH
(0.30 mmol) was added to a solution of [Ni(Me3-mcN3)(μ-OH)]2-
(PF6)2 (100 mg, 0.15 mmol) in acetone (25 mL). The mixture was
stirred overnight at room temperature and the solvent was partially
evaporated under reduced pressure. On addition of diethyl ether,
the blue-green complexes precipitated and were filtered off, washed
with diethyl ether and air-dried. 1: Yield: 115 mg (92%).
C18H29F6N4NiO2P (537): calcd. C 40.25, H 5.44, N 10.43; found
C 39.96, H 5.71, N 10.14. MS (FAB+): m/z (%) = 391 (100) [M+].
IR (nujol): ν = 3286, 3268 (NH), 1650 (C=N), 1548 (OCO) cm–1.
˜
1H NMR [(CD3)2CO, TMS]: δ = 290.8 (Hα), 263.0 (Hα), 192.3 (Hα,
2 H), 161.4 (Hα), 85.0 (Hα, 2 H), 57.3 (Hα), 38.7 (4-Me, 3 H), 22.7
(4-Me, 3 H), 9.6 (Hisonic, 4 H), –11.0 (Hβ), –13.3 (Hβ, 2 H), –15.2
(Hβ), –17.3 (Hβ), –20.3 (2-Me, 3 H), –33.0 (Hβ) ppm. 3: Yield:
117 mg (94%). C18H29F6N4NiO2P (537): calcd. C 40.25, H 5.44, N
10.43; found C 40.03, H 5.61, N 10.14. MS (FAB+): m/z (%) = 391
(100) [M+]. IR (nujol): ν = 3287, 3269 (NH), 1659 (C=N), 1552
˜
(OCO) cm–1. 1H NMR [(CD3)2CO, TMS]: δ = 366.8 (Hα), 321.9
(Hα), 226.8 (Hα, 2 H), 207.8 (Hα), 99.7 (Hα, 2 H), 65.5 (Hα), 53.1
(4-Me, 3 H), 16.3 (4-Me, 3 H), 13.4 (2-H + 4-H, 2 H), 9.4 (5-H +
6-H, 2 H), –11.8 (Hβ, 2 H), –13.2 (Hβ), –16.8 (2-Me, 3 H), –24.0
(Hβ), –27.9 (Hβ), –30.2 (Hβ) ppm.
Complexes 2 and 4: NC5H4-4-COOH or NC5H4-3-COOH (0.30
mmol) was added to a solution of [Ni(Me4-mcN3)(μ-OH)]2(PF6)2
(100 mg, 0.12 mmol) in acetone (25 mL). The mixture was stirred
overnight at room temperature and the solvent was partially evapo-
rated under reduced pressure. On addition of diethyl ether, the blue-
green complexes precipitated and were filtered off, washed with
diethyl ether and air-dried. 2: Yield: 103 mg (83%).
C19H31F6N4NiO2P (551): calcd. C 41.41, H 5.67, N 10.17; found
C 41.64, H 6.04, N 10.15. MS (FAB+): m/z (%) = 405 (100) [M+].
IR (nujol): ν = 3270 (NH), 1659 (C=N), 1552 (OCO) cm–1. 1H
˜
NMR [(CD3)2CO, TMS]: δ = 315.0 (Hα), 290.7 (Hα), 252.3 (Hα),
236.9 (Hα, 2 H), 135.6 (9-Me, 3 H), 98.3 (Hα, 2 H), 65.0 (4-Me, 3
H), 48.5 (Hα), 20.2 (4-Me, 3 H), 11.1 (3-H + 5-H, 2 H), 9.1 (2-H
+ 6-H, 2 H), –9.8 (Hβ, 2 H), –13.4 (Hβ), –16.9 (2-Me, 3 H), –25.2
(Hβ), –32.7 (Hβ,
2
H) ppm. 4: Yield: 113 mg (91%).
C19H31F6N4NiO2P (551): calcd. C 41.41, H 5.67, N 10.17; found
C 41.27, H 5.94, N 9.97. MS (FAB+): m/z (%) = 405 (100) [M+].
IR (nujol): ν = 3121 (NH), 1661 (C=N), 1530 (OCO) cm–1. 1H
˜
NMR [(CD3)2CO, TMS]: δ = 320.0 (Hα), 296.0 (Hα), 257.1 (Hα),
243.8 (Hα), 136.8 (9-Me, 3 H), 101.9 (Hα, 2 H), 67.4 (4-Me, 3 H),
46.7 (Hα), 41.5 (Hα), 20.8 (4-Me, 3 H), 9.2 (2-H + 4-H + 5-H, 3
Figure 6. Curie plots of proton resonances of complex 11.
3054
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3049–3056

Heterotrinuclear Complexes of Nickel and Palladium with Pyridinecarboxylate as Bridging Ligands
H), 7.4 (6-H), –9.7 (Hβ, 2 H), –13.7 (Hβ), –16.5 (2-Me, 3 H), –25.7 Fp, Jmp = 25.4 Hz), –164.8 (m, 4 Fm) ppm. 31P NMR ([D6]acetone,
FULL PAPER
(Hβ), –32.7 (Hβ), –33.7 (Hβ) ppm.
H3PO4): δ = –143.6 (sept, 2 P, JPF = 709 Hz) ppm.
Complexes 5–7: NC5H4-4-COOH, NC5H4-3-COOH, or NC5H4-4-
CH2COOH (0.31 mmol) was added to a solution of cis-[Pd-
(C6F5)2(PhCN)2] (100 mg, 0.15 mmol) in methanol (10 mL), the
solution was stirred for 24 h, and the solvent was partially evapo-
rated under reduced pressure. On addition of water, the white com-
plexes precipitated and were filtered off and air-dried. 5: Yield:
80 mg (75%). C24H10F10N2O4Pd (687): calcd. C 41.9, H 1.5, N 4.1;
Complexes 9 and 11. Method 1: Pd(C6F5)2(PhCN)2 (45.3 mg,
0.07 mmol) was added to a solution of complex 2 or 4 (0.14 mmol)
in acetone (25 mL). The mixture was stirred at room temperature
for 24 h. The solution was concentrated under reduced pressure
and the addition of diethyl ether caused the precipitation of a pale
blue solid, which was collected by filtration, washed with diethyl
ether and air-dried. Yields: 105 mg (97%) (for 9) and 96 mg (89%)
(for 11). Method 2: [Ni(Me4-mcN3)(μ-OH)]2(PF6)2 (65.3 mg,
0.073 mmol) was added to a solution of complex 5 or 6 (50.1 mg,
0.073 mmol) in acetone (15 mL) and the resulting solution was re-
fluxed for 5 h. The solvent was partially evaporated under reduced
pressure. On addition of Et2O, the blue complexes precipitated and
were filtered off and air-dried. Yields: 79 mg (70%) (for 9) and
86 mg (76%) (for 11). 9: C50H62F22N8Ni2O4P2Pd (1542): calcd. C
38.9, H 4.2, N 7.3; found C 38.5, H 4.4, N 7.3. MS (FAB+): m/z
(%) = 405 (100) [Ni(Me4-mcN3)(isonic)+], 1395 (1) [M+]. IR (nujol):
found C 41.6, H 1.4, N 4.1. MS (FAB+): m/z (%) = 519 (100) [M+
–
1
C F ]. IR (nujol): ν = 1720 (C=O), 798, 787 (Pd–C F ) cm–1. H
˜
6
5
6 5
NMR [(CD3)2CO, TMS]: δ = 9.27 (d, JHH = 6 Hz, 4 H, H2,6), 8.34
(d, JHH = 6 Hz, 4 H, H3,5) ppm. 19F NMR [(CD3)2CO, TMS]: δ
= –117.2 (d, 4 Fo, Jom = 24.0 Hz), –163.5 (t, 2 Fp, Jmp = 19.0 Hz),
–165.8 (m, 4 Fm) ppm. 6: Yield: 85 mg (80%). C24H10F10N2O4Pd
(687): C 41.9, H 1.5, N 4.1; found C 41.7, H 1.5, N 4.0. IR (nujol):
ν = 1705 (C=O), 796, 784 (Pd–C F ) cm–1. 1HNMR [(CD3)2CO,
˜
6
5
TMS]: δ = 9.21 (s, 2 H, 2-H), 8.99 (d, JHH = 5 Hz, 2 H, 6-H), 8.48
(d, JHH = 7 Hz, 2 H, 4-H), 7.72 (dd, JHH = 5 Hz, 2 H, 5-H) ppm.
19F NMR [(CD3)2CO, TMS]: δ = –117.0 (d, 4 Fo, Jom = 28.0 Hz),
–163.2 (t, 2 Fp, Jmp = 17.0 Hz), –165.5 (m, 4 Fm). 7: Yield: 85 mg
(74%). C28H18F10N2O4Pd (743): C 45.3, H 2.4, N 3.8; found C
ν = 3269 (N–H), 1657 (C=N), 1547 (OCO), 797, 780 (Pd–C F )
˜
6
5
cm–1. 1H NMR [(CD3)2CO, TMS]: δ = 317.7 (Hα), 259.8 (Hα),
242.9 (Hα), 210.5 (Hα, 2 H), 128.9 (9-Me, 3 H), 92.5 (Hα), 87.8 (Hα,
2 H), 56.9 (4-Me, 3 H), 19.0 (4-Me, 3 H), 11.4 (2-H + 6-H, 2 H),
10.4 (3-H + 5-H, 2 H), –10.4 (Hβ, 2 H), –12.9 (Hβ), –18.3 (2-Me,
44.9, H 2.5, N 3.8. MS (FAB+): m/z (%) = 575 (100) [M+ – C6F5].
1
IR (nujol): ν = 1744 (C=O), 795, 783 (Pd–C F ) cm–1. H NMR
3
H), –25.0 (Hβ), –30.4 (Hβ), –35.2 (Hβ) ppm. 19F NMR
˜
6
5
–
[(CD3)2CO, TMS]: δ = 8.64 (d, JHH = 6 Hz, 4 H, 2,6-H), 7.47 (d,
JHH = 6 Hz, 4 H, 3,5-H), 3.79 (s, 4 H, PhCH2), 3.66 (s, 6 H, CH3)
[(CD3)2CO, TMS]: δ = –71.6 (d, 12 F, PF6 , JFP = 708 Hz), –116.7
(d, 4 Fo, Jom = 24.5 Hz), –163.4 (t, 2 Fp, Jmp = 20.7 Hz), –165.6 (m,
4 Fm) ppm. 31P NMR ([D6]acetone, H3PO4): δ = –143.3 (sept, 2 P,
JPF = 708 Hz) ppm. 11: C50H64F22N8Ni2O4P2Pd (1542): calcd. C
38.9, H 4.2, N 7.3; found C 38.4, H 4.2, N 7.1. MS (FAB+): m/z
(%) = 405 (100) [Ni(Me4-mcN3)(nic)+], 1394 (1) [M]+. IR (nujol):
ppm. 19F NMR [(CD3)2CO, TMS]: δ = –116.8 (d, 4 Fo, Jom
28.0 Hz), –163.7 (t, 2 Fp, Jmp = 20.0 Hz), –165.8 (m, 4 Fm) ppm.
=
Complexes 8 and 10. Method 1: Pd(C6F5)2(PhCN)2 (45.3 mg,
0.07 mmol) was added to a solution of complex 1 or 3 (0.14 mmol)
in acetone (25 mL). The mixture was stirred at room temperature
for 24 h. The solution was concentrated under reduced pressure
and the addition of diethyl ether caused the precipitation of a pale
blue solid, which was collected by filtration, washed with diethyl
ether and air-dried. Yields: 100 mg (94%) (for 8) and 97 mg (91%)
(for 10). Method 2: [Ni(Me3-mcN3)(μ-OH)]2(PF6)2 (63.1 mg,
0.073 mmol) was added to a solution of complex 5 or 6 (50.1 mg,
0.073 mmol) in acetone (15 mL) and the resulting solution was re-
fluxed for 5 h. The solvent was partially evaporated under reduced
pressure. On addition of Et2O, the blue complexes precipitated and
were filtered off and air-dried. Yields: 81 mg (73%) (for 8) and
78 mg (70%) (for 10). 8: C48H58F22N8Ni2O4P2Pd (1515): calcd. C
38.1, H 3.9, N 7.4; found C 37.7, H 3.9, N 7.4. MS (FAB+): m/z
ν = 3270 (NH), 1657 (C=N), 1547 (OCO), 797, 785 (Pd–C F ) cm–1.
˜
6
5
1H NMR [(CD3)2CO, TMS]: δ = 310.6 (Hα), 287.5 (Hα), 249.7 (Hα),
233.5 (Hα), 134.4 (9-Me, 3 H), 95.6 (Hα, 2 H), 63.5 (4-Me, 3 H), 48.8
(Hα, 2 H), 19.8 (4-Me, 3 H), 9.7 (2-H + 4-H, 2 H), 9.3 (5-H), 8.2 (6-
H), –9.8 (Hβ, 2 H), –13.3 (Hβ), –17.1 (2-Me, 3 H), –25.0 (Hβ), –32.2
(Hβ), –33.4 (Hβ) ppm. 19F NMR [(CD3)2CO, TMS]: δ = –71.2 (d,
–
12 F, PF6 , JFP = 712 Hz), –116.2 (d, 4 Fo, Jom = 26.4 Hz), –162.3
(t, 2 Fp, Jmp = 16.9 Hz), –164.6 (m, 4 Fm) ppm. 31P NMR ([D6]-
acetone, H3PO4): δ = –143.3 (sept, 2 P, JPF = 691 Hz) ppm.
Complex 12: [Ni(Me3-mcN3)(μ-OH)]2(PF6)2 (63.1 mg, 0.073 mmol)
was added to a solution of complex 7 (54.2 mg, 0.073 mmol) in
acetone (15 mL) and the resulting solution was refluxed for 5 h.
The solvent was partially evaporated under reduced pressure. On
addition of Et2O, the blue complexes precipitated and were filtered
off and air-dried. 12: Yield: 96 mg (85%). C50H62F22N8Ni2O4P2Pd
(1543): calcd. C 38.9, H 4.1, N 7.3; found C 38.5, H 4.3, N 7.0.
MS (FAB+): m/z (%) = 405 (100) [Ni(Me3-mcN3)(PyOAc)]+, 1397
(%) = 391 (100) [Ni(Me -mcN )(isonic)]+. IR (nujol): ν = 3285,
˜
3
3
3271 (NH), 1658 (C=N), 1548 (OCO), 795, 778 (Pd–C6F5) cm–1.
1H NMR [(CD3)2CO, TMS]: δ = 254.0 (Hα), 236.3 (Hα, 2 H), 168.5
(Hα), 156.3 (Hα), 101.3 (Hα, 2 H), 72.8 (Hα), 54.5 (4-Me, 3 H), 16.3
(4-Me, 3 H), 10.7 (2-H + 6-H, 2 H), 8.8 (3-H + 5-H, 2 H), –12.3
(Hβ, 2 H), –14.2 (Hβ), –17.3 (Hβ), –17.6 (2-Me, 3 H), –24.6 (Hβ),
28.8 (Hβ), –31.5 (Hβ) ppm. 19F NMR [(CD3)2CO, TMS]: δ = –72.0
(15) [M+ + 1 + PF ]. IR (nujol): ν = 3289, 3266 (NH), 1661 (C=N),
˜
6
1558 (OCO), 795, 783 (Pd–C6F5) cm–1. 1H NMR [(CD3)2CO,
TMS]: δ = 230.2 (Hα, 2 H), 207.4 (Hα), 196.4 (Hα), 185.5 (Hα),
174.3 (Hα), 103.2 (Hα, 2 H), 56.3 (4-Me, 3 H), 19.7(–CH2–, 2 H),
16.8 (4-Me, 3 H), 8.8 (2-H + 6-H, 2 H), 7.4 (3-H + 5-H, 2 H),
–12.0 (Hβ, 2 H), –15.1 (Hβ), –16.4 (2-Me, 3 H), –23.9 (Hβ), 28.8
–
(d, 12 F, PF6 , JFP = 708 Hz), –116.8 (d, 4 Fo, Jom = 24.5 Hz),
–163.5 (t, 2 Fp, Jmp= 20.7 Hz), –165.7 (m, 4 Fm) ppm. 31P NMR
([D6]acetone, H3PO4): δ = –143.5 (sept, 2 P, JPF = 707 Hz) ppm.
10: C48H58F22N8Ni2O4P2Pd (1515): calcd. C 38.1, H 3.9, N 7.4;
found C 37.8, H 3.9, N 7.4. MS (FAB+): m/z (%) = 391 (100)
–
(Hβ, 2 H). 19F NMR [(CD3)2CO, TMS]: δ = –72.0 (d, 12 F, PF6 ,
JFP = 709 Hz), –116.2 (d, 4 Fo, Jom = 25.4 Hz), –163.1 (t, 2 Fp, Jmp
= 16.9 Hz), –164.8 (m, 4 Fm) ppm. 31P NMR ([D6]acetone, H3PO4):
δ = –143.6 (sept, 2 P, JPF = 708 Hz) ppm.
[Ni(Me -mcN )(nic)]+, 1367 (2) [M+]. IR (nujol): ν = 3288, 3275
˜
3
3
(NH), 1658 (C=N), 1556 (OCO), 795, 778 (Pd–C6F5) cm–1. 1H
NMR [(CD3)2CO, TMS]: δ = 224.1 (Hα, 2 H), 207.1 (Hα), 96.2
(Hα, 2 H), 73.8 (Hα), 52.1 (4-Me, 3 H), 22.8 (Hα), 16.4 (4-Me, 3
X-ray Data Collection and Structure Determination: Data collection
H), 12.3 (Hα), 9.7 (2-H + 4-H, 2 H), 9.4 (5-H), 8.6 (6-H), –11.9 was performed with a Bruker Smart CCD diffractometer with a
(Hβ, 2 H), –14.3 (Hβ), –17.9 (2-Me, 3 H), –24.6 (Hβ), –28.9 (Hβ),
nominal crystal–detector distance of 4.5 cm. Diffraction data were
collected based on an ω-scan. A total of 1371 (7) and 2524 (4) frames
were collected at 0.3° intervals and 10 s per frame. The diffraction
–32.1 (Hβ) ppm. 19F NMR [(CD3)2CO, TMS]: δ = –71.9 (d, 12 F,
–
PF6 , JFP = 712 Hz), –116.2 (d, 4 Fo, Jom = 22.5 Hz), –162.7 (t, 2
Eur. J. Inorg. Chem. 2005, 3049–3056
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3055

J. Ruiz, M. D. Santana et al.
FULL PAPER
frames were integrated using the SAINT package[42] and corrected
for absorption with SADABS.[43] The crystallographic data are
shown in Table 5. The structures were solved by direct methods[44]
and refined anisotropically on F2.[44] Hydrogen atoms were intro-
duced in calculated positions. CCDC-256615 (4) and -256616 (7)
contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[13] J. Pérez, L. García, A. G. Orpen, M. D. Santana, P. Saez, G.
García, New J. Chem. 2002, 26, 726.
[14] M. D. Santana, G. García, A. A. Lozano, G. López, J. Tudela,
J. Pérez, L. García, L. Lezama, T. Rojo, Chem. Eur. J. 2004,
10, 1738.
[15] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds,, 4th ed., John Wiley & Sons, New
York, 1986.
[16] R. F. R. Jazzar, P. H. Bhatia, M. F. Mahon, M. K. Whittlesey,
Organometallics 2003, 22, 670.
Table 5. Crystal data and summary of data collection and refine-
ment for 4 and 7.
[17] A. B. P. Lever, Inorganic Electronic Spectroscopy, Elsevier, Am-
sterdam, 1984, pp. 513–520.
[18] R. H. Holm, C. J. Hawkins, NMR of Paramagnetic Molecules:
Principles and Applications (Eds.: G. N. La Mar, W. Hor-
rocks, Jr., R. H. Holm), Academic Press, New York, 1973, pp.
243–332.
[19] A. Dei, M. Wicholas, Inorg. Chim. Acta 1989, 166, 151.
[20] M. D. Santana, A. Rufete, G. García, G. López, J. Casabó, A.
Cabrero, E. Molins, C. Miravitlles, Polyhedron 1997, 16, 3713.
[21] A. W. Addison, T. N. Rao, J. Reedijk, J. V. Rijn, G. C. Ver-
schoor, J. Chem. Soc., Dalton Trans. 1984, 1349.
[22] D. D. LeCloux, M. C. Keyes, M. Osawa, V. Reynolds, W. B.
Tolman, Inorg. Chem. 1994, 33, 6361.
[23] B. S. Hammes, C. J. Carrano, Inorg. Chem. 1999, 38, 3562.
[24] A. J. Blake, J. P. Danks, I. A. Fallis, A. Harrison, W.-S. Li, S.
Parsons, S. A. Ross, G. Whittaker, M. Schröder, J. Chem. Soc.,
Dalton Trans. 1998, 3969.
[25] J. Ruiz, V. Rodríguez, N. Cutillas, G. López, J. Pérez, Organo-
metallics 2002, 21, 412.
4·MeCN
7
Empirical formula
Formula mass
Crystal system
Unit cell dimensions:
a [Å]
b [Å]
c [Å]
C21H34F6N5NiO2P C28H18F10N2O4Pd
592.21
triclinic
742.84
monoclinic
8.1682(5)
13.0538(8)
13.4683(8)
110.329(1)
98.568(1)
96.192(1)
1311.72(14)
100(2)
14.1830(6)
12.7318(6)
15.6193(7)
90
91.6980(10)
90
2819.2(2)
100(2)
P21/n
α [°]
β [°]
γ [°]
Unit cell volume [Å3]
Temperature [K]
Space group
Z
¯
P1
2
0.871
15437
4
μ [mm–1]
0.763
17361
6309
0.0152
0.0241
0.0609
Reflections collected
[26] J. Ruiz, F. Florenciano, V. Rodríguez, C. de Haro, G. López, J.
Pérez, Eur. J. Inorg. Chem. 2002, 2736.
[27] G. López, J. Ruiz, C. Vicente, J. M. Martí, G. García, P. A.
Chaloner, P. B. Hitchcock, R. M. Harrison, Organometallics
1992, 11, 1417.
Independent reflections 5901
R(int)
0.0233
0.0626
0.1314
R1 [I Ͼ 2σ(I)][a]
wR2 (all data)[b]
[28] G. López, J. Ruiz, G. García, C. Vicente, J. Casabó, E. Molins,
C. Miravitlles, Inorg. Chem. 1991, 30, 2605.
[29] C. De Haro, G. García, G. Sánchez, G. López, J. Chem. Res.
Synop. 1986, 11; J. Chem. Res. (M) 1986, 1128.
[30] D. A. Long, D. Steele, Spectrochim. Acta 1963, 19, 1955.
[31] E. Maslowski, Vibrational Spectra of Organometallic Com-
pounds, Wiley, New York, 1977, p. 437.
Acknowledgments
This work was supported by the Dirección General de Investigación
del Ministerio de Ciencia y Tecnología (Project No. BQU2001-0979-
C02-01), Spain, and the Fundación Séneca de la Comunidad Autó-
noma de la Región de Murcia (Projects No. 00448/PI/04 and 00484/
PI/04). A. A. L. thanks the Fundación Séneca for an FPI grant.
[32] E. Alonso, J. Forniés, C. Fortuño, M. Tomás, J. Chem. Soc.,
Dalton Trans. 1995, 3777.
[33] Z. Qin, M. C. Jennings, R. J. Puddephatt, Inorg. Chem. 2002,
41, 5174.
[1] J. Y. Lu, E. E. Kohler, Inorg. Chem. Commun. 2002, 5, 196.
[2] W. Lin, O. R. Evans, R.-G. Xiong, Z. Wang, J. Am. Chem. Soc.
1998, 120, 13272.
[3] B. Rather, B. Moulton, R. D. B. Walsh, M. J. Zaworotko,
Chem. Commun. 2002, 694.
[4] J. Y. Lu, A. M. Babb, Inorg. Chem. 2001, 40, 3261.
[5] J. Y. Lu, A. M. Babb, Chem. Commun. 2001, 821.
[6] P.-O. Käll, J. G. M. Fahlman, F. Söderlind, Polyhedron 2001,
20, 2747.
[7] P. Teo, D. M. J. Foo, L. L. Koh, T. S. A. Hor, Dalton Trans.
2004, 3389.
[8] H. Adams, S. Clunas, D. E. Fenton, S. E. Spey, J. Chem. Soc.,
Dalton Trans. 2002, 441.
[9] I. G. Eremenko, S. E. Nefedov, A. A. Sidorov, M. A. Golub-
nichaya, P. V. Danilov, V. N. Ikorskii, Y. G. Shevedenkov, V. M.
Novotortsev, I. I. Moiseev, Inorg. Chem. 1999, 38, 3764 and
references cited therein.
[10] M. D. Santana, G. García, A. Rufete, M. C. Ramírez de Arel-
lano, G. López, J. Chem. Soc., Dalton Trans. 2000, 619.
[11] M. D. Santana, G. García, M. Julve, F. Lloret, J. Pérez, M.
Liu, F. Sanz, J. Cano, G. López, Inorg. Chem. 2004, 43, 2132.
[12] M. D. Santana, G. García, J. Pérez, E. Molins, G. López, Inorg.
Chem. 2001, 40, 5701.
[34] M. G. Crisp, E. R. T. Tiekink, L. M. Rendina, Inorg. Chem.
2003, 42, 1057.
[35] J. Ruiz, N. Cutillas, V. Rodríguez, J. Sampedro, G. López, P. A.
Chaloner, P. B. Hitchcock, J. Chem. Soc., Dalton Trans. 1999,
2939.
[36] J. Forniés, F. Martínez, R. Navarro, E. P. Urriolabeitia, J. Or-
ganomet. Chem. 1995, 495, 185.
[37] J. Ruiz, M. T. Martínez, F. Florenciano, V. Rodríguez, G.
López, J. Pérez, P. A. Chaloner, P. B. Hitchcock, Inorg. Chem.
2003, 42, 3650.
[38] J. Ruiz, M. T. Martínez, F. Florenciano, V. Rodríguez, G.
López, J. Pérez, P. A. Chaloner, P. B. Hitchcock, Dalton Trans.
2004, 929.
[39] J. M. Casas, B. E. Diosdado, L. R. Falvello, J. Forniés, A.
Martín, A. J. Rueda, Dalton Trans. 2004, 2733.
[40] J. W. L. Martin, J. H. Johnston, N. F. Curtis, J. Chem. Soc.,
Dalton Trans. 1978, 68.
[41] A. Escuer, R. Vicente, J. Ribas, Polyhedron 1992, 11, 453.
[42] SAINT, Version 6.22, Bruker AXS Inc.
[43] G. M. Sheldrick, SADABS, University of Göttingen, 1996.
[44] G. M. Sheldrick, SHELX-97, Programs for Crystal Structure
Analysis, release 97-2, University of Göttingen, Germany, 1998.
Received: February 9, 2005
Published Online: June 22, 2005
3056
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3049–3056