Preparation of thiocarboxylate, thiocarbamate and xanthate complexes of pentacoordinate nickel(II): Insertion of heterocumulenes into nickel(II) hydroxido complexes

Article abstract of DOI:10.1002/ejic.200700466

The hydroxido complexes [Ni(N₃-mc)(μ-OH)]₂[PF ₆]₂ [N₃-mc = 2,4,4-trimethyl-1,5,9- triazacyclododec-1-ene (N₃-mc1) or 2,4,4,9-tetramethyl-1,5,9- triazacyclododec-1-ene (N₃-mc2)] r

Full text of DOI:10.1002/ejic.200700466

FULL PAPER
DOI: 10.1002/ejic.200700466
Preparation of Thiocarboxylate, Thiocarbamate and Xanthate Complexes of
Pentacoordinate Nickel(II): Insertion of Heterocumulenes Into Nickel(II)
Hydroxido Complexes
M. Dolores Santana,*[a] Magalí Sáez-Ayala,[a] Luís García,[b] José Pérez,[b] and
Gabriel García[a]
Keywords: Nickel / Macrocyclic ligands / S ligands / Insertion / NMR spectroscopy / X-ray diffraction
The hydroxido complexes [Ni(N3-mc)(µ-OH)]2[PF6]2 [N3-mc
= 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (N3-mc1) or
2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (N3-mc2)]
react in the presence of alcohols with CS2 or PhNCS to yield
xanthate [(N3-mc)Ni{S2C(ORЈ)}][PF6] or O-alkyl N-phenyl-
thiocarbamate [(N3-mc)Ni{PhNC(ORЈ)S}][PF6] complexes;
these compounds represent the first examples of N,S-chelat-
ing thiocarbamates bound to nickel(II). The reactions of
[Ni(N3-mc)(µ-OH)]2[PF6]2 with thiocarboxylic acids yield the
corresponding thiocarboxylate derivatives [(N3-mc)Ni{S-
C(O)RЈ}][PF6]. These paramagnetic nickel(II) complexes were
1
characterized by both one- and two-dimensional (COSY) H
NMR spectroscopic techniques. The crystal structures of
[(N3-mc2)Ni(S2COCH3)][PF6] (2), [(N3mc2)Ni{PhNC(OCH2-
CH3)S}][PF6] (8), [(N3-mc2)Ni{SC(O)CH3}][PF6] (10) and [(N3-
mc1)Ni{SC(O)Ph}][PF6] (11) were determined.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
accepted mechanism for urease activity suggests that urea
is activated by coordination to one nickel(II) ion in con-
junction with extensive hydrogen bonding within the active-
site pocket of the protein, and it is subsequently attacked by
nucleophilic hydroxide ion bound to the opposite nickel(II)
centre; the resulting carbamate species then decomposes
further to yield carbonic acid and another molecule of am-
monia.[9] Bioinorganic synthetic complexes are particularly
relevant to the study of the active site of metalloenzymes,
because they provide spectroscopic information against
which theoretical results can be compared, and they can
also be used to carry out hydrolytic transformations at di-
nuclear nickel(II) cores that mimic the urease active site.[10]
In previous studies we described the preparation of binu-
clear carbonate complexes [{Ni(N3-mc)}2(µ-CO3)][PF6]2
when CO2 was bubbled (or taken up directly from the atmo-
sphere) through a solution of [Ni(N3-mc)(µ-OH)]2[PF6]2 in
acetone [or if (NH4)HCO3 was added].[11] Following our
systematic study of the reactivity of hydroxido complexes
of nickel, we next investigated the reactivity of nonorgano-
metallic hydroxido nickel complexes such as [Ni(N3-mc)(µ-
OH)]2[PF6]2 with related heterocumulenes; carbon disulfide,
CS2, or phenylisothiocyanate, PhCNS, in the presence of
alcohols RЈOH, to form O-alkyl dithiocarbonate (xanthate)
or O-alkyl N-phenylthiocarbamate pentacoordinate
nickel(II) complexes, respectively. We report herein the first
crystal structure of a N,S-chelating N-phenylthiocarbamate
nickel complex (3D Search using the Cambridge Structural
Database, CSD version 5.27, Aug. 2006 release). Thiocar-
boxylate complexes were also prepared by the acid–base re-
Introduction
Dimeric hydroxido complexes [Ni(N3-mc)(µ-OH)]2[PF6]2
[N3-mc = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (N3-
mc1) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene
(N3-mc2)] have been shown to be good precursors in the
synthesis of new coordination compounds. The acid–base
reaction of these hydroxido complexes with protic acids
leads to the formation of mono-[1–3] or dinuclear[4–6] com-
plexes depending on the nature of the deprotonated ligand.
Dithioacid ligands have rich coordination and organo-
metallic chemistry.[7] These ligands and their metal com-
plexes deserve continuous attention due to their interesting
structural and chemical properties, as well as their wide
range of applications, for example, industrially as pesticides,
vulcanization accelerators, lubricants but also as potent
biological pesticides.[8] Those metal complexes were gen-
erally prepared by metathesis reactions of transition halides
with the alkali metal salt of the corresponding thioacid.[8]
In the past decade, growing interest has been directed
towards nickel as a biological and spectroscopically relevant
metal. The nickel-containing enzyme urease degrades urea
to ammonia and carbamate (and finally CO2). The widely
[a] Departamento de Química Inorgánica, Universidad de Murcia,
30071 Murcia, Spain
Fax: +34-968-364-148
E-mail: dsl@um.es
[b] Departamento de Ingeniería Minera, Geológica
y Car-
tográfica – Área de Química Inorgánica, Universidad Pol-
itécnica de Cartagena,
30203 Cartagena, Spain
4628
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4628–4636

Thiocarboxylate, Thiocarbamate and Xanthate Complexes of Nickel(II)
action of the hydroxido complexes and the corresponding
As observed before for related systems,[14] CS2 was in-
thioacid. These paramagnetic nickel(II) complexes were serted in the presence of one equivalent of methanol to
characterized by both one- and two-dimensional (COSY) yield xanthogenate complexes. The insertion of p-nitro-
1H NMR spectroscopic techniques; these techniques can phenyl isothiocyanate in ethanol-stabilized chloroform pro-
provide a wealth of unique information on the electronic, duced iminothiocarbonate complexes.[15]
magnetic and molecular properties of the metal-binding
sites; however, relatively few two-dimensional 1H NMR
spectroscopic studies involving NiII ions in either model
complexes or biological systems have been reported.[12]
Moreover, the reactions of [NBu4]2[{(C6F5)2Ni(µ-OH)}2]
with alcohols or amines in the presence of carbon disulfide
to afford the corresponding xanthate or dithiocarbamate
complexes were previously reported.[16]
Xanthate complexes 1–4 exhibit three IR bands in the
1240–1030 cm–1 region that are related to the vibrations of
the S2CORЈ group.[17–20] The 1240 cm–1 band has a sub-
stantial contribution from C–O–C stretching, the band
around 1170 cm–1 is mainly a contribution of the ν(C–O)
mode and the absorption around 1040 cm–1 is entirely
ν(C=S).[21]
The presence of the thiocarbamate ligand in 5–8 is sup-
ported by the IR spectra, which show a band at 1537 or
1524 cm–1 assignable to ν(C=N). These values are compar-
able to those reported for thiocarbamate palladium com-
plexes where the thiocarbamate is coordinated to the metal
in a N,S-chelating mode.[22] The IR spectra of complexes 1–
8 also show the characteristic absorptions of the macro-
cyclic ligands N3-mc1 and N3-mc2 at 3290–3230 cm–1 ν(N–
H) and ca. 1660 cm–1 ν(C=N) and two strong bands as a
result of the presence of the PF6– ion at 840 and 560 cm–1.[4]
The electronic spectra of 1–8 are quite similar and show
Results and Discussion
Xanthate and Thiocarbamate Complexes
The hydroxido complexes [Ni(N3-mc)(µ-OH)]2[PF6]2
(N3-mc = N3-mc1, N3-mc2) react with CS2 in RЈOH solu-
tion to yield the nickel xanthate complexes [(N3-mc)-
Ni{S2C(ORЈ)}][PF6] (1–4) shown in Scheme 1. The reaction
of the nickel hydroxido complexes with PhNCS and
alcohols proceeds likewise to yield the O-alkyl N-phenyl-
thiocarbamate complexes [(N3-mc)Ni{PhNC(ORЈ)S}][PF6]
(5–8; Scheme 1). The complexes are air-stable, both in solid
state and in solution. The new complexes were charac-
terized by partial elemental analyses, FAB+ mass spectrom-
etry and spectroscopic methods (IR, UV/Vis and 1H
NMR). In acetone solution, these complexes behave as 1:1
electrolytes.[13] The nucleophilicity of the Ni–OH unit in two d–d transitions in acetone solution with λmax between
[Ni(N3-mc)(µ-OH)]2[PF6]2 was used here for the attack on 602 and 639 nm (100–70 –1 cm–1) and between 360 and
cumulated double bond systems. In these reactions, suppos- 380 nm (ca. 300 –1 cm–1), which could be assigned to the
3
edly, the first step consists of the addition of OH across one 3B1(F)Ǟ3E(F) and B1(F)Ǟ3A2,3E(P) transitions, respec-
double bond, and the second step is an esterification of the tively. Both λmax values and molar absorptivities are consis-
coordinated acid [Ni(N3-mc)(S–CS–OH)]+ by the alcohol tent with a pentacoordinate environment around nickel-
solvent leading to complexes 1–8.
(II).[23]
Scheme 1.
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M. D. Santana, M. Sáez-Ayala, L. García, J. Pérez, G. García
FULL PAPER
X-ray diffraction studies were carried out on [(N3-mc2)- Table 1. Selected bond lengths and angles for complex 2.[a]
Ni(S2COCH3)][PF6]·1/2 (CH3)2CO (2). A thermal ellipsoid
drawing of the cation of 2 with a partial labelling scheme is
Bond lengths [Å]
Ni1–N2
Ni1–N1
Ni1–N3
2.038(3)
2.039(3)
2.062(3)
Ni1–S1
Ni1–S2
2.3930(9)
2.5119(9)
shown in Figure 1. Selected geometric data are given in
Table 1. The NiII ion in 2 adopts a distorted square-pyrami-
dal geometry, and the parameter τ[24] shows a value of 0.16.
The three nitrogen atoms of the macrocyclic ligand consti-
tute a trigonal face of the pyramid. The two sulfur atoms
from the xanthate and the two nitrogen atoms of the macro-
cycle form the basal plane (rmsd 0.0591). The nickel ion
lies above this plane and is displaced 0.3976 Å toward the
N3 nitrogen, which constitutes the axial donor. The plane
of the chelate moiety defined by S1, S2, C14 and O1 (rms
0.0015) is inclined by 17.19(6)° to the basal plane. The Ni–
N distances lie within the range reported in complexes con-
taining the {Ni(N3-mc)} moiety.[11] The Ni–S bond lengths
are slightly different [2.3930(9) and 2.5119(9) Å]; thus the
xanthate ligand is bonded in an asymmetric chelating mode.
These bond lengths are longer than those reported for other
crystallographically characterized nickel–xanthate com-
plexes with iminophosphanes in a distorted square-planar
geometry.[25] Octahedral nickel–xanthate complexes con-
taining phenanthroline[26] or pyrazine,[27] as well as penta-
coordinate nickel–xanthate complexes containing triphos-
phanes,[28]have shorter Ni–S bond lengths. The bite angle
of the chelating xanthate anion shows values of 73.46(3)°.
The distortion from square-pyramidal geometry is also re-
flected in the bond angles between the trans ligands. The
N1–Ni–S2 and N2–Ni–S1 bond angles are 162.05(9) and
152.61(8)°, respectively. The deviation of these angles from
the idealized square-pyramidal geometry is also due to the
four-membered chelating ring of the xanthate ligand.
Bond angles [°]
N2–Ni1–N1
N2–Ni1–N3
N1–Ni1–N3
N2–Ni1–S1
N1–Ni1–S1
90.46(11)
102.71(11)
92.87(11)
152.61(8)
98.48(8)
N3–Ni1–S1
N2–Ni1–S2
N1–Ni1–S2
N3–Ni1–S2
S1–Ni1–S2
102.64(8)
90.26(8)
162.05(9)
104.45(8)
73.46(3)
[a] Symmetry transformations used to generate equivalent atoms:
#1: –x + 1, y, –z + 5/2.
plane (rmsd 0.0330) by 0.3642 Å. The plane of the chelate
moiety defined by the S1, N4, C14 and O1 (rmsd 0.0066)
atoms is inclined by 9.49(9)° to the basal plane, and the
attached phenyl ring is somewhat rotated [65.33(7)°] about
the N4–C17 axis. The C14–O1–C15 angle of 119.26(19)°
suggests that the oxygen atom can be considered to be in
the sp2-hybridized state, and the C–O bond lengths agree
with the values expected for a C(sp2)–O–C(sp3) system.[29]
The C14–S1 bond length of 1.722(2) Å is indicative of a
C(sp2)–S single bond,[30] whereas double bond character is
well-defined in the N4–C14 bond of 1.301(3) Å. Thus, the
negative charge within the bidentate ligand seems to be
mainly localized on the sulfur atom.[31]
Figure 2. ORTEP drawing of the cation of complex 8 (ellipsoids
at 50% probability level) with atom-labelling scheme. For clarity
hydrogen atoms are omitted.
Figure 1. ORTEP drawing of the cation of complex 2 (ellipsoids
at 50% probability level) with atom-labelling scheme. For clarity
hydrogen atoms are omitted.
Table 2. Selected bond lengths and angles for complex 8.
Bond lengths [Å]
Ni1–N1
Ni1–N2
Ni1–N4
2.034(2)
2.048(2)
2.067(2)
Ni1–N3
Ni1–S1
2.089(2)
2.4927(6)
Structural studies were also carried out for the complex
[(N3-mc2)Ni{PhNC(OCH2CH3)S}][PF6] (8). As shown in
Figure 2 (selected bond lengths and angles in Table 2) the
Ni atom has a distorted square-pyramidal geometry with a
value of 0.14 for τ. Distortions from the idealized square
pyramidal geometry are almost localized in the equatorial
plane where the bidentate ligand subtends an angle of
68.17(6)° to the metal. The Ni atom lies above of the basal
Bond angles [°]
N1–Ni1–N2
N1–Ni1–N4
N2–Ni1–N4
N1–Ni1–N3
N2–Ni1–N3
90.42(9)
N4–Ni1–N3
N1–Ni1–S1
N2–Ni1–S1
N4–Ni1–S1
N3–Ni1–S1
101.95(8)
161.37(6)
93.68(6)
68.17(6)
103.50(6)
100.95(8)
152.82(8)
93.39(8)
101.91(8)
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Eur. J. Inorg. Chem. 2007, 4628–4636

Thiocarboxylate, Thiocarbamate and Xanthate Complexes of Nickel(II)
The 1H NMR spectra of complexes 1–8 exhibit sharp signed by inspection of their peak areas. Therefore, on the
isotropically shifted signals from 375 to –40 ppm, in ace- basis of X-ray structures of 2 and 8, the larger distortions
tone solution. The spectra show the resonance line pattern in the square-pyramid for 8 as a result of the small bite of
observed for the N3-mc ligands that was assigned on the the N,S-chelating thiocarbamate moiety (68.17°) results in
basis of previous studies of nickel macrocyclic com- a larger magnetic anisotropy that in turn induces a larger
plexes.[1–6] A representative 1H NMR spectrum for complex dipolar shift[34] for the O-alkyl substituents. The complete
1 is shown in Figure 3. The eight resonance signals due to assignment of these isotropically shifted signals required the
1
the α-CH protons were shifted downfield, whereas the six use of two-dimensional H NMR spectroscopic techniques.
resonance signals for the β-CH protons were shifted upfield A magnitude COSY spectrum of 6 (Figure 4), recorded at
relative to the diamagnetic position because of a dominant 25 °C, clearly shows cross signals between the resonances at
spin polarization mechanism.[32] Moreover, the equatorial δ = 27.2 and 17.8 ppm and also between resonances at 17.8,
protons were expected to experience larger contact shifts –0.9 and –4.8 ppm. These signals can be assigned to the
than the axial protons because of the angular dependence CH3O- and N-phenyl m-H (17.8), o-H (–0.9) and p-H (–4.8)
of the hyperfine coupling constant,[33] and therefore, the protons, respectively, of the O-alkyl N-phenylthiocarbamate
most downfield resonances are due to the α-CHeq protons ligand. The shift direction alternation of the N-phenyl pro-
and the most upfield ones to the β-CHeq protons. The iso- tons is characteristic if the π-contact shift is dominant. The
1
tropically shifted H NMR signals observed for the methyl net spin density in the dπ orbitals could be polarized by the
groups [2-Me, 4-Me(a, b) and 9-Me-N] and the alkyl groups unpaired electrons in the dx2–y2 and dz2 orbitals through
of the xanthates and thiocarbamates can be initially as- spin-orbit coupling. A similar behaviour was observed else-
where.[35]
Thiocarboxylate Complexes
When [Ni(N3-mc)(µ-OH)]2[PF6]2 was treated with
thioacids HSC(O)CH3 or HSC(O)Ph in acetone, complexes
9–12 were obtained in moderate-to-high yields (Scheme 1).
The acid–base reaction occurred at room temperature in
acetone with the concomitant liberation of water for com-
plexes 9–12. The thiocarboxylates anions, RC(O)S–, consti-
tute an interesting class of ligand having a soft sulfur donor
site and a hard oxygen donor site.[36] Furthermore, the
chemistry of these ligands was relatively unexplored relative
Figure 3. 1H NMR spectra [in (CD3)2CO solution at room tem-
perature] of complex 1.
to thiolate or thiocarbamate ligands.[37,38] The IR spectra
of complexes 9–12 show characteristic absorptions for the
N3-mc ligands at 3294–3264 cm–1 ν(N–H) and ca.
1660 cm–1 ν(C=N), and two strong bands due to the pres-
ence of the PF6– ion at 840 and 560 cm–1 are also observed.
The thiocarboxylate ligand in compounds 9–12 exhibits a
κ2-coordination mode to the nickel atom, which is sug-
gested by the IR spectra. The spectra show strong absorp-
tion bands at ca. 1500 and ca. 980 cm–1, which can be as-
signed to ν(CO) and ν(CS), respectively, and they are con-
sistent with a symmetrical bidentate coordination.[39] This
coordination mode was authenticated by X-ray crystal
structure determination on 10 and 11 (vide infra). The crys-
tal structures of cations [(N3-mc2)Ni{SC(O)CH3}][PF6]
(10) and [(N3-mc1)Ni{SC(O)Ph}][PF6] (11) are shown in
Figures 5 and 6. Selected distances and angles for these
complexes are given in Tables 3 and 4. In each crystallized
cation, the nickel atom is five-coordinate, with a square-
pyramid arrangement of the chelating atoms. The structure
of complex 10 shows the presence of two independent mole-
cules. In each one, the Ni atom shows τ values of 0.26 and
0.27 for 10 and 0.35 for 11. The three nitrogen atoms of the
Figure 4. Portion of the 1H COSY spectrum of complex 6 [in
N3-macrocycle hold the apical position and two adjacent
(CD3)2CO solution at 25 °C]. Only the relevant region to assign
basal ones, whereas the other two basal positions corre-
the O-alkyl N-phenylthiocarbamate resonances is shown in the top
trace.
spond to the S,O-thiocarboxylate group. The basal plane is
Eur. J. Inorg. Chem. 2007, 4628–4636
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M. D. Santana, M. Sáez-Ayala, L. García, J. Pérez, G. García
FULL PAPER
formed by N1, N2, O1 and S1, with a rms deviation of Table 3. Selected bond lengths and angles for complex 10.
fitted atoms of 0.1076, by N4, N5, O2 and S2, rmsd 0.1132,
for 10 and by N1, N2, O1 and S1, rmsd 0.1448, for complex
11. The Ni atoms are 0.3850(17) and 0.3888(18) Å above of
the corresponding basal plane towards the apical N3 or N6
atom in complex 10 and 0.3346(8) Å in 11. The Ni–O bond Ni1–O1
lengths in 10 are 2.119(3) and 2.121(3) Å; in complex 11 the
Bond lengths [Å]
Ni1–N1
Ni1–N2
Ni1–N3
2.013(4)
2.030(4)
2.047(4)
2.119(3)
2.4045(13)
Ni2–N4
Ni2–N5
Ni2–N6
Ni2–O2
Ni2–S2
2.014(4)
2.017(4)
2.054(4)
2.121(3)
2.4047(13)
Ni1–S1
Ni–O bond length is 2.1000(15) Å. These bond lengths are
comparable to those reported for other crystallographically
Bond angles [°]
N4–Ni2–N5
N1–Ni1–N2
92.25(15)
94.47(15)
102.78(15)
163.40(14)
89.70(14)
101.17(14)
102.17(11)
148.10(11)
104.24(11)
68.73(10)
91.93(16)
94.45(16)
102.31(15)
163.65(14)
89.50(14)
101.16(15)
102.87(12)
147.34(11)
105.31(11)
68.42(10)
characterized homoleptic nickel–thiobenzoate complexes
with distorted octahedral[38] geometries. The bite angle of
the carboxylate anion shows values of 68.73(10) and
68.42(10)° for complex 10 and 69.05(4)° for 11. The plane
of the chelate moiety defined by S1, O1, C14 and C15 (rmsd
0.0066) is inclined 13.93(15)° with respect to the basal plane N2–Ni1–S1
N1, N2, O1 and S1; and the plane S2, O2, C29 and C30
(rmsd 0.0020) is inclined by 18.96(16)° to the basal N4, N5,
N1–Ni1–N3
N2–Ni1–N3
N1–Ni1–O1
N2–Ni1–O1
N3–Ni1–O1
N1–Ni1–S1
N4–Ni2–N6
N5–Ni2–N6
N4–Ni2–O2
N5–Ni2–O2
N6–Ni2–O2
N4–Ni2–S2
N5–Ni2–S2
N6–Ni2–S2
O2–Ni2–S2
N3–Ni1–S1
O1–Ni1–S1
O2 and S2 in complex 10. In complex 11, the plane of the
chelate moiety defined by S1, O1, C13 and C14 (rmsd
Table 4. Selected bond lengths and angles for complex 11.
Bond lengths [Å]
0.0041) is inclined by 18.51(8)° to the basal plane N1, N2,
O1 and S1, and the angle between the phenyl ring and the
nickel-bounded thiocarboxylate group is 16.29(10)°.
Ni1–N1
Ni1–N3
Ni1–N2
2.0016(18)
2.0202(18)
2.0274(17)
Ni1–O1
Ni1–S1
2.1000(15)
2.4028(6)
Bond angles [°]
N1–Ni1–N3
N1–Ni1–N2
N3–Ni1–N2
N1–Ni1–O1
N3–Ni1–O1
93.21(7)
93.04(7)
101.79(7)
168.51(7)
97.66(7)
N2–Ni1–O1
88.41(6)
104.65(5)
104.33(5)
147.34(5)
69.05(4)
N1–Ni1–S1
N3–Ni1–S1
N2–Ni1–S1
O1–Ni1–S1
complexes. The spectra show the expected resonance line
pattern because of a dominant spin-polarization mecha-
nism.[32] The spectra of thiocarboxylate derivatives 9–12 are
similar to those of corresponding complexes 1–8 in signals
and magnitudes of contact shifts. The mean difference is
the large isotropic shift for the –CH3 and –Ph protons,
which are consistent with the close proximity of theses
groups to the paramagnetic nickel(II) centre. The spectrum
of complex 12 is shown in Figure 7, and from its inspection
it can be seen that all the resonances of the phenyl rings
Figure 5. ORTEP drawing of the cation of complex 10 (ellipsoids
at 50% probability level) with atom-labelling scheme. For clarity
hydrogen atoms are omitted.
Figure 6. ORTEP drawing of the cation of complex 11 (ellipsoids
at 50% probability level) with atom-labelling scheme. For clarity
hydrogen atoms are omitted.
Complexes 9–12 exhibit relatively sharp hyperfine-shifted
1H NMR signals in acetone solution spanning from 390 to
–35 ppm. The spectra were assigned on the basis of our
Figure 7. 1H NMR spectra [in (CD3)2CO solution at room tem-
previous studies of paramagnetic nickel(II) macrocyclic perature] of complex 12.
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Eur. J. Inorg. Chem. 2007, 4628–4636

Thiocarboxylate, Thiocarbamate and Xanthate Complexes of Nickel(II)
[(N3-mc1)Ni(S2COCH3)][PF6] 1: Yield: 46 mg (36%). ΛM
=
are shifted downfield relative to TMS in accordance with a
dominant σ-delocalization pattern of spin density that is
consistent with the ground state of nickel(II) although the
unpaired electrons could polarize the net spin density in the
dπ orbitals.[6]
142 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
375.8 (α-H), 361.7 (α-H), 234.1 (α-H), 189.9 (α-H), 67.0 (α-H), 54.5
(4-Me, 3 H), 31.3 (2 α-H), 24.8 (4-Me, 3 H), 24.0 (α-H), 22.5
(CH3O-, 3 H), –7.9 (β-H), –13.3 (2 β-H), –13.9 (2-Me, 3 H), –28.5
(β-H), –31.0 (β-H), –31.4 (β-H) ppm. IR (nujol): ν = 3271, 3237
˜
(N–H), 1658 (C=N), 1238 (COC), 1178 (CO), 1046 (CS) cm–1. UV/
Vis (acetone): λ (ε, –1 cm–1) = 611 (100), 384 (446) nm. MS
(FAB+): m/z (%) = 376 (100) [M]+. C14H28F6N3NiOPS2 (522.18):
calcd. C 32.20, H 5.40, N 8.05, S 12.28; found C 32.33, H 5.26, N
7.97, S 11.84.
Conclusions
[(N3-mc2)Ni(S2COCH3)][PF6] (2): Yield: 62 mg (51%). ΛM
=
Because many questions still remain about the mecha-
nism of action of the urease metalloenzyme, such as the
nature of the hydrolytic attack[40] and the feasibility of car-
bamate as the first intermediate formed in the reaction,[41]
this study investigated the possibility of attack on cumu-
lated double bond systems. In these reactions the proposed
first step is the addition of OH across one double bond
followed by esterification; however, the external attack by
RЈO– of the coordinated heterocumulene cannot be ruled
out. Moreover, the proton resonances of the synthetic mo-
nonuclear pentacoordinate nickel(II) complexes of rele-
vance to urease were completely assigned by using 1D and
139 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
286.2 (α-H), 243.3 (α-H), 173.3 (α-H), 113.8 (9-Me, 3 H), 59.2 (α-
H), 49.4 (4-Me, 3 H), 34.1 (α-H), 30.6 (α-H), 24.3 (4-Me, 3 H), 22.6
(α-H), 20.7 (CH3O-, 3 H), 18.9 (α-H), –6.4 (β-H), –11.2 (β-H),
–14.4 (2-Me, 3 H), –17.6 (β-H), –26.9 (β-H), –29.4 (β-H), –33.3 (β-
H) ppm. IR (nujol): ν = 3271 (N–H), 1651 (C=N), 1228 (COC),
˜
1170 (CO), 1044 (CS) cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 639
(100), 392 (395) nm. MS (FAB+): m/z (%) = 390 (100) [M]+. Green
crystals suitable for X-ray diffraction studies were obtained by dif-
fusion of diethyl ether into an acetone solution of the compound.
C15H30F6N3NiOPS2 (536.21): calcd. C 33.60, H 5.64, N 7.84, S
11.96; found C 33.15, H 5.57, N 8.00, S 11.53.
1
[(N3-mc)Ni(S2COCH2CH3)][PF6]: To a suspension of [Ni(N3-mc)-
(µ-OH)]2[PF6]2 (0.15 mmol) in ethanol (50 mL) CS2 (0.30 mmol)
was added and the resulting mixture was refluxed for 3 h. The sol-
vent was partially evaporated under reduced pressure until ca.
10 mL and then the suspension was filtered. On addition of Et2O
the blue-green complexes precipitated. The solids were filtered off
and air-dried.
2D H NMR spectroscopic methods.
Experimental Section
Materials: Chemicals were purchased from Aldrich and were used
without further purification. Solvents were dried and distilled by
general methods before use. The complexes [Ni(N3-mc)(µ-OH)]2-
[PF6]2 [N3-mc = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (N3-
mc1) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (N3-mc2)]
were prepared by previously described procedures.[42,43]
[(N3-mc1)Ni(S2COCH2CH3)][PF6] (3): Yield: 50 mg (40%). ΛM
=
133 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
371.0 (α-H), 357.1 (α-H), 231.4 (α-H), 186.2 (α-H), 66.5 (α-H), 53.3
(4-Me, 3 H), 31.4 (2 α-H), 24.5 (4-Me, 3 H), 21.7 (α-H), 9.4
(-CH2O-, 2 H), 8.8 (CH3-, 3 H), –7.8 (β-H), –13.2 (2 β-H), –13.6
(2-Me, 3 H), –28.1 (β-H), –30.4 (β-H), –30.9 (β-H) ppm. IR (nujol):
ν = 3274, 3247 (N–H), 1652 (C=N), 1237 (COC), 1159 (CO), 1031
˜
Physical Measurements: C, H, N and S analyses were carried out
with a microanalyzer Carlo Erba model EA 1108. Fast atom bom-
bardment (FAB) mass spectra were obtained with a Fisons VG
Autospec spectrometer operating in the positive mode. Infrared
spectra were recorded with a Perkin–Elmer 16F PC FTIR spectro-
photometer by using Nujol mulls between polyethylene sheets. UV/
Vis spectra (in acetone) were recorded with a UNICAM 520 spec-
trophotometer equipped with matched quartz cells in the 300–
800 nm range. 1H NMR spectra were recorded with a Bruker model
AV 200E or AV 300 spectrometer. Chemical shifts (in ppm) are
(CS) cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 616 (96), 385 (418)
nm. MS (FAB+): m/z (%) = 390 (100) [M]+. C15H30F6N3NiOPS2
(536.21): calcd. C 33.60, H 5.64, N 7.84, S 11.96; found C 33.56,
H 5.46, N 7.55, S 11.56.
[(N3-mc2)Ni(S2COCH2CH3)][PF6] (4): Yield: 46 mg (37%). ΛM
=
154 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
289.2 (α-H), 246.5 (α-H), 173.8 (α-H), 113.9 (9-Me, 3 H), 59.7 (α-
H), 49.8 (4-Me, 3 H), 34.2 (α-H), 30.7 (α-H), 24.6 (4-Me, 3 H), 22.3
(α-H), 18.8 (α-H), 8.3 (-CH2O-, 2 H), 7.4 (CH3-, 3 H), –6.5 (β-H),
–11.4 (β-H), –14.5 (2-Me, 3 H), –17.0 (β-H), –27.3 (β-H), –29.7 (β-
1
reported with respect to the residual solvent signal. The H COSY
spectrum was obtained at 25 °C for 6 with 512 data points in the
F1 dimension and 4096 data points in the F2 dimension with a
delay time of 150 ms. An unshifted sine-bell-squared weighting
function was applied prior to Fourier transformation followed by
baseline correction in both dimensions and symmetrization. Molar
conductivities were measured in acetone solutions (ca.
10–3 molL–1) with a Crison 525 conductimeter.
H), –33.6 (β-H) ppm. IR (nujol): ν = 3271 (N–H), 1651 (C=N),
˜
1217 (COC), 1158 (CO), 1046 (CS) cm–1. UV/Vis (acetone): λ (ε,

–1 cm–1) = 633 (115), 391 (454) nm. MS (FAB+): m/z (%) = 404
(100) [M]+. C16H32F6N3NiOPS2 (550.23): calcd. C 34.93, H 5.86,
N 7.64, S 11.66; found C 35.03, H 5.76, N 7.38, S 11.39.
[(N3-mc)Ni{PhNC(OCH3)S}][PF6]: To a suspension of [Ni(N3-
mc)(µ-OH)]2[PF6]2 (0.15 mmol) in methanol (60 mL) was added
PhNCS (0.30 mmol). The mixture was stirred at room temperature
for 24 h. The solvent was removed under reduced pressure until a
blue solid began to precipitate, and then diethyl ether was added
to complete precipitation. The solid was filtered off, washed with
diethyl ether and air-dried.
[(N3-mc)Ni(S2COCH3)][PF6]: To a suspension of [Ni(N3-mc)(µ-
OH)]2[PF6]2 (0.15 mmol) in methanol (60 mL) was added CS2
(0.30 mmol). The mixture was stirred at room temperature for 24 h,
and the solvent was partially evaporated under reduced pressure to
ca. 15 mL. The mixture was filtered 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.
[(N3-mc1)Ni{PhNC(OCH3)S}][PF6] (5): Yield: 94 mg (70%). ΛM
=
133 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
Eur. J. Inorg. Chem. 2007, 4628–4636
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4633

M. D. Santana, M. Sáez-Ayala, L. García, J. Pérez, G. García
FULL PAPER
367.2 (α-H), 347.8 (α-H), 230.4 (2 α-H), 182.9 (α-H), 75.7 (α-H), 370.1 (α-H), 357.9 (α-H), 235.5 (α-H), 213.6 (α-H), 87.0 (α-H), 81.9
51.0 (4-Me, 3 H), 33.7 (α-H), 30.3 (α-H), 27.9 (CH3O-, 3 H), 23.1 (CH3-, 3 H), 72.7 (α-H), 54.9 (4-Me, 3 H), 36.7 (α-H), 31.2 (α-H),
(4-Me, 3 H), 17.5 (2 m-H), –2.5 (2 o-H), –6.1 (p-H), –8.8 (2 β-H), 21.8 (4-Me, 3 H), –8.5 (2 β-H), –12.9 (β-H), –13.7 (2-Me, 3 H),
–9.6 (β-H), –13.2 (2-Me, 3 H), –28.6 (β-H), –29.4 (2 β-H) ppm. IR –27.2 (β-H), –29.0 (β-H), –30.5 (β-H) ppm. IR (nujol): ν = 3294,
˜
(nujol): ν = 3290, 3253 (N–H), 1657 (C=N), 1537 (CN) cm–1. UV/
3269 (N–H), 1659 (C=N), 1503 (C=O), 978 (CS) cm–1. UV/Vis
(acetone): λ (ε, –1 cm–1) = 627 (84), 385 (181) nm. MS (FAB+):
m/z (%) = 344 (100) [M]+. C14H28F6N3NiOPS (490.11): calcd. C
34.31, H 5.76, N 8.57, S 6.54; found C 34.55, H 5.80, N 8.63, S
6.44.
˜
Vis (acetone): λ (ε, –1 cm–1) = 602 (70), 366 (272) nm. MS (FAB+):
m/z (%) = 435 (100) [M]+. C20H33F6N4NiOPS (581.23): calcd. C
41.33, H 5.72, N 9.64, S 5.52; found C 40.71, H 5.52, N 9.73, S
5.41.
[(N3-mc2)Ni{PhNC(OCH3)S}][PF6] (6): Yield: 105 mg (79%). ΛM
= 136 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
290.4 (α-H), 281.7 (α-H), 251.7 (α-H), 163.5 (α-H), 151.0 (α-H),
112.4 (9-Me, 3 H), 66.2 (α-H), 47.3 (4-Me, 3 H), 38.7 (α-H), 34.1
(α-H), 27.2 (CH3O-, 3 H), 23.7 (4-Me, 3 H), 17.8 (2 m-H), –0.9 (2
o-H), –4.8 (p-H), –7.5 (β-H), –10.6 (β-H), –11.8 (β-H), –13.9 (2-
Me, 3 H), –25.8 (β-H), –27.5 (β-H), –31.7 (β-H) ppm. IR (nujol):
[(N3-mc1)Ni{SC(O)Ph}][PF6] (11): Yield: 120 mg (94%). ΛM
=
144 Ω–1 cm2 mol–1. 1H NMR [200 MHz, (CD3)2CO, TMS]: δ =
384.7 (α-H), 364.5 (α-H), 239.6 (α-H), 240.7 (α-H), 220.3 (α-H),
89.8 (α-H), 56.7 (4-Me, 3 H), 37.5 (α-H), 32.2 (α-H), 22.2 (4-Me, 3
H), 12.2 (2 o-H), 8.6 (2 m-H), 5.0 (p-H), –8.7 (2 β-H), –13.1 (β-H),
–13.8 (2-Me, 3 H), –27.6 (β-H), –29.3 (β-H), –30.8 (β-H) ppm. IR
(nujol): ν = 3285, 3268 (N–H), 1656 (C=N), 1594 (C=C), 966 (CS)
˜
ν = 3270 (N–H), 1659 (C=N), 1524 (CN) cm–1. UV/Vis (acetone):
˜
cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 631 (86), 387 (183) nm.
MS (FAB+): m/z (%) = 406 (100) [M]+. C19H30F6N3NiOPS
(552.18): calcd. C 41.33, H 5.48, N 7.61, S 5.81; found C 41.45, H
5.39, N 7.53, S 5.70.
λ (ε, –1 cm–1) = 629 (79) 384 (285) nm. MS (FAB+): m/z (%) = 449
(100) [M]+. C21H35F6N4NiOPS (595.25): calcd. C 42.37, H 5.93, N
9.41, S 5.39; found C 42.62, H 5.73, N 9.27, S 5.17.
[(N3-mc)Ni{PhNC(OCH2CH3)S}][PF6]: To a suspension of [Ni(N3-
mc)(µ-OH)]2[PF6]2 (0.15 mmol) in ethanol (40 mL) was added
PhNCS (0.30 mmol), and the resulting mixture was heated at reflux
for 1 h. The solvent was partially evaporated under reduced pres-
sure until a solid began to precipitate. Upon the addition of diethyl
ether, the blue-green complexes precipitated completely. The solid
was filtered off and air-dried.
[(N3-mc2)Ni{SC(O)CH3}][PF6] (10): Yield: 87 mg (77%). ΛM
=
136 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
340.0 (α-H), 304.0 (α-H), 290.5 (α-H), 252.6 (α-H), 198.6 (α-H),
128.6 (9-Me, 3 H), 79.6 (CH3-, 3 H), 74.7 (α-H), 58.3 (4-Me, 3 H),
37.6 (2 α-H), 22.1 (4-Me, 3 H), –6.8 (β-H), –11.9 (β-H), –12.9 (β-
H), –15.6 (2-Me, 3 H), –26.8 (β-H), –32.1 (β-H), –33.4 (β-H) ppm.
IR (nujol): ν = 3264 (N–H), 1656 (C=N), 1519 (C=O), 980 (CS)
˜
[(N3-mc1)Ni{PhNC(OCH2CH3)S}][PF6] (7): Yield: 54 mg (40%).
ΛM = 137 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ
= 363.9 (α-H), 344.5 (α-H), 228.7 (2 α-H), 180.3 (α-H), 74.9 (α-H),
49.9 (4-Me, 3 H), 33.4 (α-H), 30.0 (α-H), 22.9 (4-Me, 3 H), 17.5 (2
m-H), 13.7 (-CH2O-, 2 H), 13.0 (CH3-, 3 H), –2.3 (2 o-H), –6.0 (p-
H), –8.7 (2 β-H), –9.5 (β-H), –13.0 (2-Me, 3 H), –28.3 (β-H), –29.1
cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 628 (88), 384 (164). MS
(FAB+): m/z (%) = 358 (100) [M]+. C15H30F6N3NiOPS (504.14):
calcd. C 35.74, H 6.00, N 8.33, S 6.36; found C 35.70, H 6.00, N
8.29, S 6.32.
[(N3-mc2)Ni{SC(O)Ph}][PF6] (12): Yield: 112 mg (88%). ΛM
=
138 Ω–1 cm2 mol–1. 1H NMR [200 MHz, (CD3)2CO, TMS]: δ =
340.4 (α-H), 311.6 (α-H), 295.6 (α-H), 258.8 (α-H), 204.4 (α-H),
130.8 (9-Me, 3 H), 76.2 (α-H), 60.2 (4-Me, 3 H), 38.6 (2 α-H), 22.6
(4-Me, 3 H), 13.1 (2 o-H), 8.5 (2 m-H), 5.5 (p-H), –6.8 (β-H), –11.8
(β-H), –12.9 (β-H), –15.5 (2-Me, 3 H), –27.1 (β-H), –32.4 (β-H),
(2 β-H) ppm. IR (nujol): ν = 3292, 3252 (N–H), 1659 (C=N), 1537
˜
(CN) cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 607 (75), 364 (293)
nm. MS (FAB+): m/z (%) = 449 (100) [M]+. C21H35F6N4NiOPS
(595.25): calcd. C 42.37, H 5.93, N 9.41, S 5.39; found C 42.49, H
5.84, N 9.30, S 5.47.
–33.7 (β-H) ppm. IR (nujol): ν = 3267 (N–H), 1658 (C=N), 1495
˜
[(N3-mc2)Ni{PhNC(OCH2CH3)S}][PF6] (8): Yield: 58 mg (42%).
ΛM = 134 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ
= 288.2 (α-H), 280.1 (α-H), 251.1 (α-H), 160.6 (α-H), 149.5 (α-H),
117.1 (9-Me, 3 H), 65.1 (α-H), 46.5 (4-Me, 3 H), 38.3 (α-H), 34.0
(α-H), 23.6 (4-Me, 3 H), 17.8 (2 m-H), 14.0 (-CH2O-, 2 H), 12.2
(CH3-, 3 H), –0.6 (2 o-H), –4.6 (p-H), –7.5 (β-H), –10.4 (β-H), –11.8
(β-H), –13.8 (2-Me, 3 H), –27.3 (β-H), –28.3 (β-H), –31.6 (β-H)
(C=O), 967 (CS) cm–1. UV/Vis (acetone): λ (ε, –1 cm–1) = 630 (87),
394 (186). MS (FAB+): m/z (%) = 420 (100) [M]+. C20H32F6N3Ni-
OPS (566.21): calcd. C 42.42, H 5.70, N 7.42, S 5.66; found C
42.49, H 5.65, N 7.39, S 5.56.
Structure Determination and Refinement: Single crystals of com-
plexes 2 (blue block), 8 (blue block), 10 (green block) and 11 (blue
block) suitable for X-ray diffraction studies were obtained by slow
diffusion of diethyl ether onto an acetone solution (10, 11 and 2) or
by slowly evaporation of the reaction solution (8) of the complex.
Crystals were selected and mounted on a glass fibre for data collec-
tion. Diffraction data were measured with a Bruker SMART
APEX by using Mo-Kα radiation (λ = 0.71073 Å). Crystallographic
data are summarized in Table 5. The diffraction frames were inte-
grated by using the SAINT package[44] and corrected for absorp-
tion with SADABS.[45] The raw intensity data were converted (in-
cluding corrections for Lorentz and polarization effects) to struc-
ture amplitudes and their esd by using the SAINT program. The
structures were solved by direct methods[46] and refined[46] by full-
matrix least-squares techniques by using anisotropic thermal pa-
rameters for non-hydrogen atoms. Hydrogen atoms were set at cal-
culated positions. CCDC-645172 (for 2), -645173 (for 8), -645174
(for 10) and -645175 (for 11) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
ppm. IR (nujol): ν = 3279 (N–H), 1659 (C=N), 1537 (CN) cm–1.
˜
UV/Vis (acetone): λ (ε, –1 cm–1) = 623 (78), 384 (281) nm. MS
(FAB+): m/z (%) = 463 (100) [M]+. Green crystals suitable for X-
ray diffraction studies were obtained by slow evaporation of the
reaction mixture. C22H37F6N4NiOPS (609.28): calcd. C 43.37, H
6.12, N 9.20, S 5.26; found C 43.29, H 5.96, N 9.02, S 5.47.
[(N3-mc)Ni(A)][PF6] [N3-mc = N3-mc1, A = SC(O)CH3 (9), SC(O)-
Ph (11); N3-mc = N3-mc2, A = SC(O)CH3 (10), SC(O)Ph (12)]:
These complexes were prepared by reaction of [Ni(N3-mc)(µ-OH)]2-
[PF6]2 (0.12 mmol) with the corresponding thiocarboxylic acid
[HSC(O)CH3 or HSC(O)Ph, 0.24 mmol] in acetone (25 mL). After
stirring for 1 h, the solution was filtered and concentrated under
reduced pressure to ca. 8 mL. The addition of diethyl ether caused
the precipitation of green solids, which were collected by filtration,
washed with diethyl ether and air-dried.
[(N3-mc1)Ni{SC(O)CH3}][PF6] (9): Yield: 90 mg (79%). ΛM
=
140 Ω–1 cm2 mol–1. 1H NMR [300 MHz, (CD3)2CO, TMS]: δ =
4634
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4628–4636

Thiocarboxylate, Thiocarbamate and Xanthate Complexes of Nickel(II)
Table 5. Crystallographic data for complexes 2, 8, 10 and 11.
Complex
Formula
2
8
10
11
C15H30F6N3NiOPS2·1/2Me2CO C22H37F6N4NiOPS
C15H30F6N3NiO1PS·1/2
Me2CO
C19H30F6N3NiOPS
M
T [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
565.26
100(2)
0.71073
monoclinic
C2/c
22.773(2)
15.2834(15)
14.2077(14)
90
105.6810(10)
90
4760.9(8)
8
1.577
609.30
100(2)
0.71073
triclinic
P1
8.1229(4)
9.0655(5)
10.5412(6)
74.3280(10)
74.4370(10)
67.7310(10)
679.54(6)
1
533.20
100(2)
0.71073
552.20
293(2) K
0.71073
monoclinic
P21/c
8.2180(4)
14.3034(6)
19.6944(9)
90
98.4990(10)
90
2289.56(18)
4
1.602
1.074
triclinic
¯
P1
13.5659(11)
13.8759(11)
14.1725(11)
77.0060(10)
77.2380(10)
62.8690(10)
2291.8(3)
4
γ [°]
V [Å3]
Z
Dcalcd. [Mgm–3]
1.489
0.914
1.545
1.071
µ [mm–1]
1.121
F(000)
2352
26434
318
7946
1112
26502
1144
26189
Reflections collected
Independent reflections
Goodness-of-fit on F2
Final R indices
[IϾ2σ(I)][a,b]
R indices (all data)
5487 (Rint = 0.0374)
1.260
R1 = 0.0563
wR2 = 0.1424
R1 = 0.0572
wR2 = 0.1430
1.021/–0.572
5786 (Rint = 0.0159) 10217 (Rint = 0.0284)
0.807
R1 = 0.0304
wR2 = 0.0730
R1 = 0.0319
wR2 = 0.0739
0.515/–0.258
5329 (Rint = 0.0222)
1.090
R1 = 0.0388
wR2 = 0.0938
R1 = 0.0395
wR2 = 0.0943
0.767/–0.666
1.203
R1 = 0.0716
wR2 = 0.1709
R1 = 0.0765
wR2 = 0.1737
1.340/–0.654
Max/min ∆ρ[eÅ–3]
[a] R1 = Σ ||Fo|–|Fc||/Σ|Fo| for reflections with IϾ2σI. [b] wR2 = {Σ[w(Fo –Fc ) ]/Σ[w(Fo2)2]}1/2 for all reflections; w–1 = σ2(F2) + (aP)2 +
2
2 2
2
bP, in which P = (2Fc + Fo2)/3 and a and b are constants set by the program.
[12] Examples of 1H NMR spectra of nickel(II) complexes: a) R. C.
charge from The Cambridge Crystallographic Data Centre via
Holz, E. A. Evodokimov, F. T. Gobena, Inorg. Chem. 1996, 35,
3808–3814; b) C. Belle, C. Bougault, M.-T. Averbuch, A. Durif,
J.-L. Pierre, J.-M. Latour, L. Le Pape, J. Am. Chem. Soc. 2001,
123, 8053–8066; c) E. Szajna, P. Dobrowolski, A. L. Fuller,
A. M. Arif, L. Berreau, Inorg. Chem. 2004, 43, 3988–3997; d)
A. Sánchez-Méndez, J. M. Benito, E. de Jesús, F. J. de la Mata,
J. C. Flores, R. Gómez, P. Gómez-Sal, Dalton Trans. 2006,
5379–5389.
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
Financial support from the Comunidad Autónoma de la Región de
Murcia (Projects 00484/PI/04 and 03010/PI/05), Spain, is gratefully
acknowledged.
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