Preparation, crystal structures and NMR characterization of substituted-benzoate complexes Nickel(II)-N3-macrocycles

Article abstract of DOI:10.1016/j.poly.2006.09.068

Substituted-benzoate complexes of nickel(II) of the types bidentate [Ni(mcN₃)(Bz)](PF₆) and monodentate [Ni(mcN₃)(Bz)(H₂O)](PF₆) have been prepared by acid-base reaction between the hydroxo complexes

Full text of DOI:10.1016/j.poly.2006.09.068

Polyhedron 26 (2007) 1029–1036
www.elsevier.com/locate/poly
Preparation, crystal structures and NMR characterization
of substituted-benzoate complexes Nickel(II)-N3-macrocycles
a,
a
a
a
*
´
´
´
M. Dolores Santana , Gabriel Garcıa , Gregorio Lopez , Abel Lozano ,
a
b
b,
*
´
´ ´
Consuelo Vicente , Luıs Garcıa , Jose Perez
a
Departamento de Quı´mica Inorga´nica, Universidad de Murcia, 30071 Murcia, Spain
´
b
Departamento de Ingenierı´a Minera, Geolo´gica y Cartogra´fica, Area de Quı´mica Inorga´nica, Universidad Polite´cnica de Cartagena,
E-30203 Cartagena, Spain
Received 6 September 2006; accepted 26 September 2006
Available online 30 September 2006
Abstract
Substituted-benzoate complexes of nickel(II) of the types bidentate [Ni(mcN3)(Bz)](PF6) and monodentate [Ni(mcN3)(Bz)
(H2O)](PF6) have been prepared by acid-base reaction between the hydroxo complexes [Ni(mcN3)(l-OH)]2(PF6)2 (mcN3 = 2,4,4-tri-
methyl-1,5,9-triazacyclododec-1-ene (Me3-mcN3) or its 9-methyl derivative (Me4-mcN3)) and the corresponding benzoic acid. The para-
magnetic nickel(II) complexes have been characterized in solution by NMR spectroscopy. The influence of the substituents on the
hyperfine shift patterns for substituted-benzoate complexes of nickel(II) has been studied. The substituent effects upon the coordination
mode of substituted benzoates have been established by X-ray diffraction.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: Nickel; Carboxylate ligands; Macrocyclic ligands; Substituent effects; Solid-state structures; NMR
1. Introduction
magnetic interactions while the mononuclear complexes
are likely to play an important role in modelling metallo-
protein sites [5]. However, the nickel-carboxylate com-
plexes characterized structurally are limited [6]. On the
other hand, the study of paramagnetic molecules using
two-dimensional NMR techniques has been prevented by
the fast nuclear relaxation rate [7], recently COSY and
NOESY spectra of paramagnetic complexes [8] and metal-
loproteins have appeared [9]. The aim of this investigation
has been to elucidate the influence of the substituents on
the hyperfine shift patterns for substituted-benzoates com-
plexes of nickel(II). The NMR spectroscopy has shown to
be a sensitive method for the characterization of paramag-
netic nickel complexes in solution. We now report a
systematic study of the substituent effects upon the coordi-
nation of substituted benzoates. The solid-state structures
of nickel(II) complexes are sensitive to the nature of sub-
stituents on the carboxylate and both bi- and monodentate
benzoates complexes can be isolated. Crystal structures of
The design and synthesis of transition metal complexes
with carboxylate ligands have been received a considerable
interest in coordination chemistry, due to the fact that this
type of complexes has potential applications in molecular-
based magnets, catalysis, supramolecular chemistry and
biological systems [1,2]. The carboxylate anion can adopt
a wide range of bonding modes that includes monodentate,
symmetric and asymmetric chelating and bidentate and
monodentate bridging [3]. In addition, it is well known that
hydrogen bonding plays an important role in bioinorganic
chemistry and is a gateway to molecular organisation [4]
and even to crystal engineering. The dinuclear nickel com-
plexes with bridging carboxylates are interesting for their
*
Corresponding authors. Tel.: +34 968367458; fax: +34 968364148
(M.D. Santana).
E-mail address: dsl@um.es (M.D. Santana).
0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.09.068

1030
M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
representative compounds are presented, as well as the
NMR studies of these paramagnetic nickel(II) complexes.
FAB+, m/z: 435 [M]+. IR (cmꢀ1): 3297, 3267 m(N–H),
1672 m(C@N), 1530, 1375 m(CO). UV–Vis in acetone, k
(nm), e (Mꢀ1 cmꢀ1): 616 (57), 381 (360).
2. Experimental
[Ni(Me3-mcN3)(4-NH2Bz)](PF6) (3): Yield 87 mg (66%).
Anal. Calc. for C19H31F6N4NiO2P: C, 41.41; H, 5.67; N,
10.17. Found: C, 41.35; H, 5.65; N, 10.14%. FAB+, m/z:
405 [M]+. IR (cmꢀ1): 3418, 3395 m(N–H2), 3289, 3256
m(N–H), 1665 m(C@N), 1624 d(N–H2), 1501, 1375 m(CO).
UV–Vis in acetone, k (nm), e (Mꢀ1 cmꢀ1): 623 (65), 380
(230).
[Ni(Me4-mcN3)(2-NH2Bz)](PF6) (4): Yield 77 mg (57%).
Anal. Calc. for C20H33F6N4NiO2P: C, 42.50; H, 5.89; N,
9.91. Found: C, 42.37; H, 5.96; N, 9.84%. FAB+, m/z:
419 [M]+. IR (cmꢀ1): 3485, 3359 m(N–H2), 3265 m(N–H),
1660 m(C@N), 1614 d(N–H2), 1503, 1376 m(CO). UV–Vis
in acetone, k (nm), e (Mꢀ1 cmꢀ1): 632 (66), 385 (232).
[Ni(Me4-mcN3)(2-NO2Bz)](PF6) (5): Yield 117 mg
(82%). Anal. Calc. for C20H31F6N4NiO4P: C, 40.36; H,
5.25; N, 9.41. Found: C, 40.19; H, 5.34; N, 9.50%.
FAB+, m/z: 449 [M]+. IR (cmꢀ1): 3270 m(N–H), 1666
m(C@N), 1540, 1376 m(CO). UV–Vis in acetone, k (nm), e
(Mꢀ1 cmꢀ1): 632 (65), 381 (445).
2.1. General methods
C, H, and N analyses were carried out with a microan-
alyzer Carlo Erba model EA 1108. Infrared spectra were
recorded on a Perkin–Emer 16F PC FT-IR spectropho-
tometer using Nujol mulls between polyethylene sheets.
The UV–Vis spectra (in acetone) were recorded on a Hit-
achi 2000V spectrophotometer for 300–700 nm range.
1
The H and 19F NMR spectra (in acetone) were recorded
on a Bruker AC 200E, Bruker AC 300E or Bruker AV-
400 spectrometer. Chemical shifts (in ppm) are reported
with respect to the residual solvent signal or CFCl3 (as
standard), respectively. The 1H COSY spectrum was
obtained at 20 °C for 4 with 256 data points in the F1
dimension and 2048 data points in the F2 dimension with
a delay time of 150 or 20 ms. An unshifted sine-bell-
squared weighting function was applied prior to Fourier
transformation followed by baseline correction in both
dimensions and symmetrization. Fast atom bombardment
(FAB) mass spectra were run on a Fisons VG Autospec
spectrometer operating in the FAB+ mode. All chemicals
were purchased from Aldrich and were used without
further purification. Solvents were dried and distilled by
general methods before use. The complexes [Ni(mcN3)-
(l-OH)]2(PF6)2 (mcN3 = 2,4,4-trimethyl-1,5,9-triazacyclo-
dodec-1-ene (Me3-mcN3) and its 9-methyl derivative
(Me4-mcN3)) were prepared by procedures previously
described [10,11].
[Ni(Me4-mcN3)(4-NH2Bz)](PF6) (6): Yield 99 mg (73%).
Anal. Calc. for C20H33F6N4NiO2P: C, 42.50; H, 5.89; N,
9.91. Found: C, 42.43; H, 5.85; N, 9.94%. FAB+, m/z:
419 [M]+. IR (cmꢀ1): 3453, 3342 m(N–H2), 3280 m(N–H),
1671 m(C@N), 1606 d(N–H2), 1502, 1375 m(CO). UV–Vis
in acetone, k (nm), e (Mꢀ1 cmꢀ1): 628 (66), 381 (320).
2.2.2. [Ni(mcN3)(Bz)(H2O)](PF6) (mcN3 = Me3-mcN3,
Bz = 4-NO2Bz (7), 2,3,4,5,6-F5Bz (8); mcN3 = Me4-mcN3,
Bz = 4-NO2Bz (9), 2,3,4,5,6-F5Bz (10))
Complexes 7–10 were prepared by allowing
[Ni2(mcN3)2(l-OH)2](PF6)2 (0.12 mmol) to react with the
corresponding benzoic acid (0.24 mmol) in acetone
(25 mL). After stirring for 12 h the solvent was removed
under reduced pressure and the addition of diethyl ether
caused the precipitation of a green solid, which was col-
lected by filtration, washed with diethyl ether and air-dried.
[Ni(Me3-mcN3)(4-NO2Bz)(H2O)](PF6) (7): Yield 112 mg
(78%). Anal. Calc. for C19H31F6N4NiO5P: C, 38.08; H,
5.21; N, 9.35. Found: C, 38.01; H, 5.15; N 9.52%. FAB+,
m/z: 435 [M+ꢀH2O]. IR (cmꢀ1): 3577 m(OH), 3294, 3254
m(N–H), 1657 m(C@N), 1555, 1347 m(CO). UV–Vis in ace-
tone, k (nm), e (Mꢀ1 cmꢀ1): 621 (63), 381 (483).
2.2. Syntheses
2.2.1. [Ni(mcN3)(Bz)](PF6) (mcN3 = Me3-mcN3,
Bz = 2-NH2Bz (1), 2-NO2Bz (2), 4-NH2Bz (3);
mcN3 = Me4-mcN3, Bz = 2-NH2Bz (4), 2-NO2Bz (5),
4-NH2Bz (6))
These complexes were prepared by reaction of
[Ni2(mcN3)2(l-OH)2](PF6)2 (0.12 mmol) with the corre-
sponding carboxylic acid (0.24 mmol) in acetone (25 mL).
After stirring for 12 h the solution was concentrated under
reduced pressure and the addition of diethyl ether caused
the precipitation of a green solid, which was collected by
filtration, washed with diethyl ether and air-dried.
[Ni(Me3-mcN3)(2-NH2Bz)](PF6) (1): Yield 91 mg (69%).
Anal. Calc. for C19H31F6N4NiO2P: C, 41.41; H 5.67; N,
10.17. Found: C, 41.19; H, 5.72; N, 10.04%. FAB+, m/z:
405 [M]+. IR (cmꢀ1): 3442, 3333 m(N–H2), 3290, 3244
m(N–H), 1660 m(C@N), 1621 d (N–H2), 1504, 1376 m(CO).
UV–Vis in acetone, k (nm), e (Mꢀ1 cmꢀ1): 622 (72), 380
(174).
[Ni(Me3-mcN3)(2,3,4,5,6-F5Bz)(H2O)](PF6) (8): Yield
112 mg (72%). Anal. Calc. for C19H27F11N3NiO3P: C,
35.43; H, 4.22; N, 6.52. Found: C, 35.30; H, 4.31; N,
6.49%. FAB+, m/z: 480 [M+ꢀH2O]. IR (cmꢀ1): 3603m(O–
H), 3288, 3272 m(N–H), 1650 m(C@N), 1589, 1356 m(CO).
UV–Vis in acetone, k (nm), e (Mꢀ1 cmꢀ1): 625 (58), 385
(173). 19F NMR ((CD3)2CO, ppm): d ꢀ109.2 (Fo, 2 F),
ꢀ144.6 (Fp), ꢀ160.7 (Fm, 2F).
[Ni(Me4-mcN3)(4-NO2Bz)(H2O)](PF6) (9): Yield 119 mg
(81%). Anal. Found: C, 39.19; H, 5.46; N, 9.12. Calc. for
C20H33F6N4NiO5P: C, 39.17; H, 5.42; N, 9.14%. FAB+,
m/z: 449 [MꢀH2O]+. IR (cmꢀ1): 3599 m(OH), 3287
[Ni(Me3-mcN3)(2-NO2Bz)](PF6) (2): Yield 110 mg
(79%). Anal. Calc. for C19H29F6N4NiO4P: C, 39.27; H,
5.03; N, 9.64. Found: C, 39.14; H, 5.13; N, 9.77%.

M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
1031
m(N–H), 1659 m(C@N), 1536, 1358 m(CO). UV–Vis in ace-
tone, k (nm), e (Mꢀ1 cmꢀ1): 622 (65), 382 (462).
benzoic acids HBz-2-NH2, HBz-2-NO2, HBz-4-NH2,
HBz-4-NO2 or HBz-2,3,4,5,6-F5 in acetone, complexes 1–
10 were obtained in moderate high yields (Scheme 1).
The acid-base reaction occurs at room temperature in ace-
tone with the concomitant liberation of water for 1–6 com-
plexes. In contrast, the benzoic acids HBz-4-NO2 and HBz-
2,3,4,5,6-F5, under the same reaction conditions gave
aquo-complexes [Ni(mcN3)(Bz)(H2O)](PF6). Complexes
1–10 are all blue-green air-stable solids and they have been
characterized by partial elemental analyses, FAB+ mass
spectrometry and spectroscopic (IR and NMR) methods.
[Ni(Me4-mcN3)(2,3,4,5,6-F5Bz)(H2O)](PF6) (10): Yield
114 mg (72%). Anal. Calc. for C20H29F11N3NiO3P: C,
36.49; H, 4.44; N, 6.38. Found: C, 36.18; H, 4.53; N,
6.34%. FAB+, m/z: 494 [M+ꢀH2O]. IR (cmꢀ1): 3590,
m(O–H), 3263 m(N–H), 1654 m(C@N), 1604, 1367 m(CO).
UV–Vis in acetone, k (nm), e (Mꢀ1 cmꢀ1): 626 (57), 384
(169). 19F NMR ((CD3)2CO, ppm): d ꢀ105.7 (Fo, 2F),
ꢀ142.9 (Fp), ꢀ161.3 (Fm, 2F).
2.3. X-ray data collection and structure determination
3.2. Infrared and electronic spectra
Data collection was performed on a Bruker Smart CCD
diffractometer with a nominal crystal to detector distance
of 4.5 cm. Diffraction data were collected based on a x
scan run. A total of 1371 (complexes 2 and 3) and 2524
(complexes 4 and 7) frames were collected at 0.3° intervals
and 10 s per frame. The diffraction frames were integrated
using the SAINT package [12] and corrected for absorption
with SADABS [13]. Data collection for 10 was performed
on a Siemens P4 diffractometer. The crystallographic data
are shown in Table 1. The structure were solved by direct
methods [14] and refined anisotropically on F2 [13]. Hydro-
gen atoms were introduced in calculated positions.
The IR spectra of complexes 1–10 show characteristic
absorptions for the mcN3 ligands [16]: 3297–3244 cmꢀ1
m(N–H), ꢁ1660 cmꢀ1m(C@N), and two strong bands due
to the presence of the PF6 ion at 840 and 560 cmꢀ1 are
ꢀ
also observed. The benzoate ligand in compounds 1–6
exhibits j2-coordination mode to the nickel atom that is
suggested by the IR spectra. The separation between the
components of m(OCO) is in the range 126–164 cmꢀ1 and
this is consistent with a symmetrical bidentate coordination
[17,18]. For complexes 7–10 where the carboxylate acts as
monodentate ligand, the D value is larger (ca. 200 cmꢀ1).
These coordination modes in 2, 3, 4, 7 and 10 were authen-
ticated by an X-ray crystal structure determination (vide
infra). A broad band in the spectra of 7–10 in the range
3600–3500 cmꢀ1 can be assigned to coordinated water
vibrations.
3. Results and discussion
3.1. Synthesis
The hydroxo complexes [Ni(mcN3)(l-OH)]2(PF6)2
(mcN3 = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me3-
mcN3) and its 9-methyl derivative (Me4-mcN3)) have
been used as starting materials for the preparation of sev-
eral five-coordinate nickel(II) complexes [15]. When
[Ni(mcN3)(l-OH)]2(PF6)2 was treated with substituted
The electronic spectra of the complexes in acetone solu-
tion are all similar and show bands in the 620 and 380 nm
3
regions which could be assigned to 3B1(F) ! E(F) and
3
3B1(F) ! A2, 3E(P) transitions, respectively. The kmax val-
ues and molar absorptivities are consistent with a pentaco-
ordinate environment around nickel(II) [15].
Table 1
Crystal data and summary of data collection and refinement for 2, 3, 4, 7 and 10
Empirical formula
C19H29F6N4NiO4P
C19H31F6N4NiO2P
C20H33F6N4NiO2P
C19H31F6N4NiO5P
C20H29F11N3NiO3P
Formula weight
Crystal system
Unit cell dimensions
581.14
orthorhombic
551.16
monoclinic
565.18
monoclinic
599.16
monoclinic
658.14
monoclinic
˚
a (A)
9.5314(5)
13.4985(7)
18.9838(10)
90
90
90
2442.4(2)
293(2)
P21cn
4
9.3203(4)
21.1419(9)
12.3756(5)
90
105.2400(10)
90
2352.84(17)
293(2)
P21/c
8.1545(4)
15.7841(8)
18.8882(10)
90
90.6570(10)
90
2431.0(2)
293(2)
P21/c
7.6324(3)
16.7099(7)
19.3507(8)
90
92.63
90
2465.32(17)
100(2)
P21/c
12.9840(10)
12.8210(10)
15.8640(10)
90
96.100(10)
90
2625.9(3)
173(2)
Cc
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
Unit cell volume (A )
Temperature
Space group
Z
4
4
4
4
l (mmꢀ1
)
0.939
0.964
0.935
0.936
0.906
Reflections collected
Independent reflections
R1 [I > 2r(I)]
14698
5138
0.0289
0.0785
14505
5235
0.0327
0.0870
27675
5590
0.0462
0.1184
15298
5537
0.0357
0.0967
4616
4616
0.0444
0.1330
wR2 (all data)

1032
M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
Scheme 1. Reaction schemes for substituted-benzoate complexes of nickel(II).
3.3. NMR spectroscopy
regard to the diamagnetic position [21]. The equatorial pro-
tons are expected to experience larger contact shifts than
the axial protons and therefore the most downfield reso-
nances are due to a-CHeq and the most upfield ones to
b-CHeq [22]. The isotropically shifted 1H NMR signals
observed for the methyl groups (2-Me, 4-Me(a,b) and 9-
Me–N) in Table 2 and phenyl groups of benzoates can be
initially assigned by inspection of their peak areas. All
the resonances of the phenyl rings (Table 3) are downfield
to TMS in accordance with a dominant r-delocalization
pattern of spin density consistent with the ground state
All of the complexes exhibit relatively sharp hyperfine-
shifted 1H NMR signals in acetone solution spanning from
1
350 to ꢀ35 ppm. The H NMR spectra of complexes 1–10
have been assigned on the basis of our previous studies of
paramagnetic nickel(II) macrocyclic complexes [19]. The
spectra show (Tables 2 and 3) the expected resonance line
pattern because of a dominant spin-polarisation mecha-
nism [20]. The eight a-methylene protons shift downfield
whereas the six b-methylene protons shift upfield with
Table 2
1H NMR Chemical shift data (ppm) for the macrocyclic ligands
Complex
Ha
Hb
2-Me
4-Me (a,b)
55.4, 18.3
9-Me
1
338.9 (2H), 231.3 (2H), 218.2 (2H), 106.5 (2H)
ꢀ11.3, ꢀ12.2 (2H), ꢀ25.1, ꢀ28.3, ꢀ29.8
ꢀ15.0
2
3
318.7 (2H), 257.0, 222.6 (2H), 194.8, 96.9, 83.9
342.7 (2H), 229.4 (2H), 224.1, 107.5, 43.5 (2H)
344.2, 306.0, 287.6, 248.2, 229.7, 100.6, 45.8, 40.9
335.9, 310.0, 283.2, 248.7, 232.7, 95.5, 51.3 (2H)
347.2, 301.8, 287.6, 244.6, 224.1, 100.1, 91.1, 43.7, 37.8
329.7 (2H), 246.4, 231.4, 206.9, 102.2, 69.3 (2H)
312.5 (2H), 218.6 (2H), 179.1 (2H), 94.3 (2H)
341.7 (2H), 307.3, 283.1, 250.1, 232.5, 97.1, 50.2 (2H)
329.0, 311.0, 284.6, 255.2, 232.1, 93.0, 50.8 (2H)
ꢀ12.2 (2H), ꢀ15.1, ꢀ23.6, ꢀ27.6, ꢀ32.6
ꢀ11.0 (2H), ꢀ12.5, ꢀ25.6, ꢀ27.7, ꢀ30.8
ꢀ9.6 (2H), ꢀ13.3, ꢀ25.4, ꢀ31.5, ꢀ32.8
ꢀ10.0 (2H), ꢀ13.3, ꢀ25.1, ꢀ32.0, ꢀ33.8
ꢀ8.7, ꢀ9.7, ꢀ13.3, ꢀ25.4, ꢀ31.4, ꢀ33.3
ꢀ11.8 (2H), ꢀ13.6, ꢀ24.3, ꢀ28.9, ꢀ30.4
ꢀ12.3 (2H), ꢀ15.4, ꢀ23.2, ꢀ27.4, ꢀ33.7
ꢀ9.8 (2H), ꢀ13.3, ꢀ25.0, ꢀ32.2, ꢀ33.1
ꢀ9.9 (2H), ꢀ13.3, ꢀ25.1 ꢀ31.7, ꢀ34.0
ꢀ18.4
ꢀ14.5
ꢀ15.9
ꢀ17.3
ꢀ15.9
ꢀ16.8
ꢀ19.1
ꢀ17.0
ꢀ17.3
51.7, 14.9
56.3, 19.6
62.9, 20.3
64.6, 19.9
61.5, 20.7
54.4, 16.6
48.3, 14.4
63.9, 19.9
63.4, 19.9
4
129.5
136.2
127.0
5
6
7
8
9
134.1
135.6
10

M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
1033
Table 3
1H NMR Chemical shift data (ppm) for the benzoate ligands
Complex
2-H
3-H
4-H
5-H
6-H
9.8
Other ligands
1
2
6.6 (NH2)
11.1
10.7
6.2
5.8
8.1
6.5 (5-H + 6-H)
3
8.9 (2-H + 6-H)
7.1 (NH2)
7.8 (3-H + 5-H)
11.2
5.4 (NH2)
6.1
4
8.1
10.3
5
10.6 (3-H)
7.9 (3-H + 5-H)
9.9 (3-H + 5-H)
6.1
5.5 (NH2)
6.3 (5-H + 6-H)
6
9.3 (2-H + 6-H)
9.4 (2-H + 6-H)
7
4.7 (H2O)
8.7 (H2O)
5.6 (H2O)
9.8 (H2O)
8
9
10
9.9 (2-H + 6-H)
10.1 (3-H + 5-H)
Fig. 1. 1H NMR spectra (in d6-acetone solution at room temperature) of 3 (left) and 7 (right). Only the phenyl resonances region is shown.
of nickel(II) although the unpaired electrons could polarise
the net spin density in the dp orbitals. A similar behaviour
has been observed elsewhere [7]. In spectra of the 4-NH2 (3,
6) and 4-NO2 (7, 9) derivatives two resonances for the phe-
nyl protons have been observed (Fig. 1). The broad signal
can be assigned to the 2-H and 6-H protons of the aromatic
rings nearer to the nickel atom; moreover for the 4-NO2
derivatives (7, 9) the 3-H and 5-H resonance is more down-
field shifted (9.9 and 10.1 ppm) than for 4-NH2 derivatives
(3, 6) (7.8 and 7.9 ppm). Substitution at the position two
breaks the ring symmetry so that four phenyl resonances
of equal intensity were observed for 1 and 4. The complete
assignment of these isotropically shifted signals required an
application of two-dimensional 1H NMR techniques. A
magnitude COSY spectrum of 4 (Fig. 2), recorded at
20 °C, clearly shows cross signals between the resonances
at 11.2, 8.1 and 6.1 ppm and also between resonances at
10.3 and 8.1 ppm. These signals can be assigned to the phe-
nyl 3-H (11.2), 6-H (10.3), 5-H (8.1), and 4-H (6.1) protons,
respectively, of the benzoate ligand. The spectra of 2-NO2
derivatives (2, 5) show two resonances of intensity corre-
sponding to one and three protons that can be assigned
to 3-H and 4,5,6-H (not well-resolved) respectively. There-
fore, on the basis of the X-ray structure of 2 and 4 (see
below) the distortion in the square pyramidal arrangement
of the nickel atom due to the small bite angle of the che-
lated carboxylate moiety and the substitution on 2-position
of the ring result in a larger magnetic anisotropy that in
turn induces a larger isotropic shift of the 3-H proton.
The 19F NMR spectra of complexes 8 and 10 show the
presence of C6F5(OCO)ꢀ ring giving three resonances with
relative intensities of 2:1:2 due to the ortho-, para-, and
meta-F atoms, respectively.
3.4. Solid state structures of the complexes
The single-crystal X-ray diffraction study on [Ni(Me3-
mcN3)(Bz-2-NO2)](PF6) (2), [Ni(Me3-mcN3)(Bz-4-NH2)]
(PF6) (3) and [Ni(Me4-mcN3)(Bz-2-NH2)](PF6) (4) confirms
that benzoate formed by deprotonation of the correspond-
ing benzoic acid, is bonded to the nickel atom as a biden-
tate ligand. The structures of compounds 2, 3 and 4 are
similar. Selected distances angles for these complexes are
given in Table 4, and Figs. 3–5 show the thermal ellipsoid
diagrams. In these compounds, nickel atoms have distorted
square-pyramidal geometry around the metal ion. The
Reedijk parameter [23] s shows values of 0.240, 0.059
and 0.024 for complexes 2, 3 and 4, respectively. The three

1034
M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
Fig. 3. ORTEP drawing of complex 2 showing the atom numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level.
For clarity hydrogen atoms of macrocycle are omitted.
Fig. 2. Magnitude 1H COSY spectrum of complex 4 at 400 MHz at 20 °C
in d6-acetone solution recorded with a delay time of 150 ms. Only the
region relevant to the assignment of phenyl resonances is shown in the top
trace. The inset on the bottom shows an enlargement of the 5-H–6-H
cross-peak area obtained with a delay time of 20 ms.
Fig. 4. ORTEP drawing of complex 3 showing the atom numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level.
For clarity hydrogen atoms of macrocycle are omitted.
Table 4
˚
Selected bond lengths (A) and angles (°) for complexes 2, 3 and 4
2
3
4
Bond lengths
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–O(1)
Ni(1)–O(2)
1.988(2)
2.012(2)
2.015(2)
2.120(2)
2.080(2)
1.993(2)
2.026(1)
2.020(2)
2.103(1)
2.062(1)
1.987(2)
2.016(2)
2.049(2)
2.110(2)
2.078(2)
Bond angles
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)
95.07(7)
93.38(8)
163.78(7)
101.89(7)
103.82(7)
96.52(7)
149.37(7)
94.83(7)
100.46(7)
62.84(6)
93.93(6)
94.80(6)
98.07(5)
155.55(6)
102.18(6)
151.96(5)
96.62(5)
101.96(6)
104.40(6)
63.52(5)
91.80(8)
95.42(9)
100.67(9)
156.32(8)
101.34(8)
157.75(8)
99.62(8)
95.80(8)
102.48(9)
62.51(8)
Fig. 5. ORTEP drawing of complex 4 showing the atom numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level.
For clarity hydrogen atoms of macrocycle are omitted.
nitrogen atoms of the macrocyclic ligand constitute a trigo-
nal face of the pyramid. The two oxygen atoms from the
benzoate and two nitrogens of the macrocycle form the
basal plane. The nickel ion lies above this plane and is dis-
and 4, respectively, towards the N(3) nitrogen, which con-
stitutes the axial donor. The Ni–N distances lie within the
range reported in complexes containing the {Ni(mcN3)}
˚
placed 0.288(1), 0.374(1) and 0.310(1) A for complexes 2, 3

M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
1035
Table 5
moiety [13,15]. The Ni–O bond distances are close to each
other (2.0802(15) and 2.1198(17) A (2), 2.0622(12) and
˚
Selected bond lengths (A) and angles (°) for complexes 7 and 10
˚
˚
˚
7
10
2.1034(12) A (3) and 2.078(2) and 2.1103(18) A (4)) thus
the benzoate ligand is bonded in a symmetric (or almost)
chelating mode with {[Ni–O(1)]–[Ni–O(2)]} = DO values
Bond lengths
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–O(1)
Ni(1)–O(5)
2.028(2)
2.026(2)
2.030(2)
2.047(1)
2.043(2)
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–O(1)
Ni(1)–O(3)
2.020(5)
2.033(4)
2.054(4)
2.048(4)
2.041(5)
˚
of 0.0396, 0.0412 and 0.0323 A for 2, 3 and 4, respectively.
These bond distances are comparable to those reported for
other crystallographically characterized nickel-carboxylate
complexes with a distorted square pyramidal [24] or octa-
hedral [25,26] geometry. The bite angle of the chelating car-
boxylate anion shows values of 62.84(6)° 2, 63.52(5)° 3 and
62.51(8)° 4, respectively. The torsion angle between the
aromatic ring and the nickel-bounded carboxylate group
is 57.3 (3) and ꢀ8.5 (3)° for complexes 2 and 3. In addition,
there are some interconnections by hydrogen bonds in
compound 3ꢀthe NH2 groups in the packing are oriented
towards PF6 anions with the shortest Nꢂ ꢂ ꢂF distances of
Bond angles
N(1)–Ni(1)–N(2)
N(1)–Ni(1)–N(3)
N(1)–Ni(1)–O(1)
N(1)–Ni(1)–O(5)
N(2)–Ni(1)–N(3)
N(2)–Ni(1)–O(1)
N(2)–Ni(1)–O(5)
N(3)–Ni(1)–O(1)
N(3)–Ni(1)–O(5)
O(5)–Ni(1)–O(1)
91.75(6)
90.73(6)
179.53(6)
92.77(6)
101.03(6)
87.81(6)
143.98(7)
89.50(6)
114.62(7)
87.50(6)
N(1)–Ni(1)–N(2)
N(1)–Ni(1)–N(3)
N(1)–Ni(1)–O(1)
N(1)–Ni(1)–O(3)
N(2)–Ni(1)–N(3)
N(2)–Ni(1)–O(1)
N(2)–Ni(1)–O(3)
N(3)–Ni(1)–O(1)
N(3)–Ni(1)–O(3)
O(3)–Ni(1)–O(1)
91.95(19)
93.05(18)
167.31(17)
92.6(2)
102.92(17)
82.53(16)
156.79(17)
99.31(18)
99.5(2)
i
ii
˚
˚
88.21(19)
N4ꢂ ꢂ ꢂF3 : 2.937(2) A and N4ꢂ ꢂ ꢂF3 : 3.084(2) A (i: x ꢀ 1,
ꢀy + 3/2, z + 1/2; ii: ꢀx, y + 1/2, ꢀz + 3/2). In complex
4 the aromatic ring is disordered over two positions with
an occupation factor close to 50%. In both positions there
is an intramolecular hydrogen bond with a mean Oꢂ ꢂ ꢂN
and angles of complexes 7 and 10 are listed in Table 5. The
nickel centre is bonded to a N3-macrocyclic ligand, a
monodentate benzoate and a water molecule in a distorted
trigonal bipyramidal geometry for 7 and distorted square-
pyramidal geometry for 10. The s parameter shows values
of 0.593, and 0.175 for complexes 7 and 10, respectively.
The Ni–N (macrocycle) bond distances in 7 and 10 are very
similar to those observed in 2, 3 and 4. The carboxylate
anion acts as a monodentate ligand through the deproto-
nated hydroxyl oxygen. The Ni–O (benzoate) bond dis-
˚
distance of 2.682 A. The molecular structures, with the
atom-numbering schemes, of compounds 7 and 10 are
shown in Figs. 6 and 7, respectively. Selected bond lengths
˚
tances are close to each other 2.0472(13) A for 7 and
2.048(4) A for 10 and the Ni–O (water) distances are also
similar (2.0429(15) A (7) and 2.041(5) A (10)). The nickel
atom in 10 is 0.304(2) A out of de basal plane defined by
˚
˚
˚
˚
˚
N1, N2, O1 and O3. The rmsd of this plane is 0.087 A.
The dihedral angle between the carboxylate group and
the aromatic ring is 22.6(3)° for 7 and 51.0(5)° for 10. In
compound 7 there is an intramolecular strong hydrogen
bond between the water molecule and the carboxylate
Fig. 6. ORTEP drawing of complex 7 showing the atom numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level.
For clarity hydrogen atoms of macrocycle are omitted.
˚
group with an O5ꢂ ꢂ ꢂO2 distance of 2.559(2) A. In the crys-
tal packing, the complexes appear grouped by pairs (Fig. 8)
with a N2ꢂ ꢂ ꢂO3i distance (i: ꢀx + 1, ꢀy + 1, ꢀz) of
Fig. 7. ORTEP drawing of complex 10 showing the atom numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level.
For clarity hydrogen atoms of macrocycle are omitted.
Fig. 8. Molecular grouping in the solid state of complex 7. Hydrogen
atoms of the macrocycle are omitted.

1036
M.D. Santana et al. / Polyhedron 26 (2007) 1029–1036
˚
[5] H. Adams, S. Clunas, D.E. Fenton, S.E. Spey, J. Chem. Soc., Dalton
Trans. (2002) 441.
[6] (a) I.L. Eremenko, S.E. Nefedov, A.A. Sidorov, M.A. Golubnichaya,
P.V. Danilov, V.N. Ikorskii, Y.G. Shvedenkov, V.M. Novotortsev,
I.I. Moiseev, Inorg. Chem. 38 (1999) 3764;
3.054(2) A and the aromatic rings adopt a parallel orienta-
˚
tion having a distance between centroids of 3.741 A and an
angle between the ring normal and the centroid vector of
26.5°. In a similar manner, in 10 there is a strong intramo-
lecular hydrogen bond between the water molecule and the
(b) B.S. Hammes, C.J. Carrano, Inorg. Chem. 38 (1999) 3562;
(c) A.J. Blake, J.P. Danks, I.A. Fallis, A. Harrison, W.-S. Li, S.
Parsons, S.A. Ross, G. Whittaker, M. Schro¨der, J. Chem. Soc.,
Dalton Trans. (1998) 3969.
˚
carboxylate group with an O3ꢂ ꢂ ꢂO2 distance of 2.580(7) A.
i
˚
In this case, the O3ꢂ ꢂ ꢂF9 distance, 2.720(8) A, also suggests
ꢀ
the existence of a hydrogen bond to the PF6 anion
´
[7] J.-M. Moratal, J. Salgado, A. Donaire, H.R. Jimenez, J. Castells,
(i: x + 1, y, z). In these complexes Ni atom and N atoms
from the macrocycle form three six-membered rings. The
conformations adopted for those rings have been used to
characterize the conformation of complexes containing
these macrocycles [27]. In all the structures reported in this
paper the six-membered rings that do not contain the C@N
bond have chair-like conformations; this is the most fre-
quent conformation in this kind of complexes [27].
Inorg. Chem. 32 (1993) 3587.
_ ´
[8] S. Wolowiec, L. Latos-Grazynski, D. Toronto, J.-C. Marchon, Inorg.
Chem. 37 (1998) 724.
[9] (a) I. Bertini, C. Luchinat, NMR of Paramagnetic Molecules in
Biological Systems, Benjamin & Cummings, Menlo Park, CA, 1986;
(b) I. Bertini, P. Turano, A.J. Vila, Chem. Rev. 93 (1993) 2833;
(c) G. La Mar, J.S. de Ropp, NMR Methodology for Paramagnetic
Proteins, vol. 12, Plenum Press, New York, 1993, p. 1.
[10] J.W.L. Martin, J.H. Johnston, N.F. Curtis, J. Chem. Soc., Dalton
Trans. (1978) 68.
[11] A. Escuer, R. Vicente, J. Ribas, Polyhedron 11 (1992) 453.
[12] SAINT, Version 6.22, Bruker AXS Inc.
Acknowledgements
[13] G.M. Sheldrick, SADABS, University of Gottingen, 1996.
[14] G.M. Sheldrick, SHELX-97, Programs for Crystal Structure Analysis
(Release 97-2), University of Go¨ttingen, Germany, 1998.
We wish to thank Dr. Donaire for his valuable sugges-
tions and to Dr. de Godos for recording the NMR spectra.
´
´
[15] (a) M.D. Santana, G. Garcıa, A.A. Lozano, G. Lopez, J. Tudela, J.
´
´
´
We thank also the Fundacion Seneca de la Region de Mur-
´
´
Perez, L. Garcıa, L. Lezama, T. Rojo, Chem. Eur. J. 10 (2004) 1738;
cia (00484/PI/04 and 03010/PI/05) for financial support
´
´
(b) M.D. Santana, G. Garcıa, M. Julve, F. Lloret, J. Perez, M. Liu, F.
´
and the Ministerio de Educacion y Ciencia for partial
´
Sanz, J. Cano, G. Lopez, Inorg. Chem. 43 (2004) 2132;
(c) J. Ruiz, M.D. Santana, A. Lozano, C. Vicente, G. Garcıa, G.
financial support (CTQ2005-09231-C02-01).
´
´
´
´
Lopez, J. Perez, L. Garcıa, Eur. J. Inorg. Chem. (2005) 3049.
´
´
´
[16] M.D. Santana, A. Rufete, G. Garcıa, G. Lopez, J. Casabo, A.
Cabrero, E. Molins, C. Miravitlles, Polyhedron 16 (1997) 3713.
[17] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, Wiley, New York, 1986, p. 236.
[18] H.-L. Zhu, M.-F. Wu, L.-M. Zheng, P. Huang, W.-X. Tang,
Transition Met. Chem. 24 (1999) 346.
Appendix A. Supplementary material
CCDC 613433, 613434, 613435, 613436 and 613437 con-
tain the supplementary crystallographic data for 2, 3, 4, 7
and 10. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary
data associated with this article can be found, in the online
version, at doi:10.1016/j.poly.2006.09.068.
´
´
´
[19] M.D. Santana, G. Garcıa, J. Perez, E. Molins, G. Lopez, Inorg.
Chem. 40 (2001) 5701.
[20] R.H. Holm, C.J. Hawkins, NMR of Paramagnetic Molecules:
Principles and Applications, in: G.N. La Mar, W. HorrocksJr.,
R.H. Holm (Eds.), Academic Press, New York, 1973, p. 243.
´
´
´
[21] M.D. Santana, A.A. Lozano, G. Garcıa, G. Lopez, J. Perez, Dalton
Trans. 1 (2005) 104.
[22] A. Dei, M. Wicholas, Inorg. Chim. Acta 166 (1989) 151.
[23] A.W. Addison, T.N. Rao, J. Reedijk, J.V. Rijn, G.C. Verschoor, J.
Chem. Soc., Dalton Trans. (1984) 1349.
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