Pentacoordinate Nickel(II) Complexes Double Bridged by Phosphate Ester of Phosphinate Ligands: Spectroscopic, Structural, Kinetic and Magnetic Studies

Article abstract of DOI:10.1002/chem.200305367

The bis(phosphatediester)-bridged complexes [{Ni([12]aneN ₃)(μ-O₂P(OR)₂)}₂](PF ₆)₂ {[12]aneN₃= Me₃[12]aneN ₃, 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene; R=Me (1), Bu (2), Ph (3), Ph-4-NO₂ (4); [12]aneN₃= Me ₄[12]aneN₃, 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene; R=Me (5), Bu (6), Ph (7), Ph-4-NO₂ (8)} were prepared by hydrolysis of the phosphate triester with the hydroxo complex [{Ni([12]aneN₃)(μ-OH)} ₂](PF₆)₂ or by acid-base reaction of the dialkyl or diaryl phosphoric acid and the above hydroxo complex. The acid-base reaction was also used to synthesise the phosphinate-bridged complexes [{Ni([12]aneN₃)(μ-O₂PR₂)} ₂](PF₆)₂ {[12]aneN₃=Me ₃[12]aneN₃, R=Me (9), Ph (10); [12]aneN ₃=Me₄[12]aneN₃, R=Me (11), Ph (12)}. The molecular structures of complexes 2, 3 and 12 were established by single crystal X-ray diffraction studies. The eight-membered rings defined by the nickel atoms and the bridging ligands show distorted twist-boat, chair and boat-boat conformations in 2, 3 and 12, respectively. The experimental susceptibility data for compounds 2, 3 and 12 were fitted by least-squares methods to the analytical expression given by Ginsberg. The best fit was obtained with values of J= -0.11 cm^-1, D=-9.5 cm^-1 and g=2.20 for 2; J=-0.97 cm^-1, D=-9.3 cm^-1 and g=2.21 for 3; and J=-0.14 cm^-1, D=-11.9 cm^-1 and g=2.195 for 12. The magnetic-exchange pathways must involve the phosphate/phosphinate bridges, because these favour antiferromagnetic interactions. The observation of a higher exchange parameter for compound 3 is a consequence of a favourable disposition of the O-P-O bridges. The kinetics for the hydrolysis of TNP (tris(4-nitrophenyl)phosphate) with the dinuclear nickel(II) hydroxo complex [{Ni(Me₃[12]aneN₃)(μ-OH)}₂]-(PF ₆)₂ was studied by UV-visible spectroscopy. The proposed mechanism for TNP-promoted hydrolysis can be described as one-substrate/two-product, and can be fitted to a Michaelis-Menten equation.

Full text of DOI:10.1002/chem.200305367

FULL PAPER
Pentacoordinate Nickel(ii) Complexes Double Bridged by Phosphate Ester
or Phosphinate Ligands: Spectroscopic,Structural,Kinetic,and Magnetic
Studies
M. Dolores Santana,*[a] Gabriel GarcÌa,*[a] A. Abel Lozano,[a] Gregorio LÛpez,[a]
Josÿ Tudela,[b] Josÿ Pÿrez,[c] Luis GarcÌa,[c] Luis Lezama,[d] and TeÛfilo Rojo[d]
Abstract: The bis(phosphatediester)-
bridged complexes [{Ni([12]aneN3)(m-
R=Me (11), Ph (12)}. The molecular
structures of complexes 2, 3 and 12
were established by single crystal X-ray
diffraction studies. The eight-mem-
bered rings defined by the nickel atoms
and the bridging ligands show distorted
twist-boat, chair and boat boat confor-
mations in 2, 3 and 12, respectively.
The experimental susceptibility data
for compounds 2, 3 and 12 were fitted
by least-squares methods to the analyt-
ical expression given by Ginsberg. The
best fit was obtained with values of J=
ꢀ0.11 cmꢀ1, D=ꢀ9.5 cmꢀ1 and g=2.20
for 2; J=ꢀ0.97 cmꢀ1, D=ꢀ9.3 cmꢀ1
and g=2.21 for 3; and J=ꢀ0.14 cmꢀ1,
D=ꢀ11.9 cmꢀ1 and g=2.195 for 12.
The magnetic-exchange pathways must
involve the phosphate/phosphinate
bridges, because these favour antiferro-
magnetic interactions. The observation
of a higher exchange parameter for
compound 3 is a consequence of a fa-
O2P(OR)2)}2](PF6)2
{[12]aneN3 =
Me3[12]aneN3, 2,4,4-trimethyl-1,5,9-tri-
azacyclododec-1-ene; R=Me (1), Bu
(2), Ph (3), Ph-4-NO2 (4); [12]aneN3 =
Me4[12]aneN3,
2,4,4,9-tetramethyl-
1,5,9-triazacyclododec-1-ene; R=Me
(5), Bu (6), Ph (7), Ph-4-NO2 (8)} were
prepared by hydrolysis of the phos-
phate triester with the hydroxo com-
plex [{Ni([12]aneN3)(m-OH)}2](PF6)2 or
by acid base reaction of the dialkyl or
diaryl phosphoric acid and the above
hydroxo complex. The acid base reac-
tion was also used to synthesise the
ꢀ ꢀ
vourable disposition of the O P O
bridges. The kinetics for the hydrolysis
of TNP (tris(4-nitrophenyl)phosphate)
with the dinuclear nickel(ii) hydroxo
complex [{Ni(Me3[12]aneN3)(m-OH)}2]-
(PF6)2 was studied by UV-visible spec-
troscopy. The proposed mechanism for
TNP-promoted hydrolysis can be de-
scribed as one-substrate/two-product,
phosphinate-bridged
complexes
Keywords: kinetics
¥
magnetic
[{Ni([12]aneN3)(m-O2PR2)}2](PF6)2
and can be fitted to
Menten equation.
a Michaelis
properties ¥ nickel ¥ phosphates ¥
phosphinates
{[12]aneN3 =Me3[12]aneN3,
R=Me
(9), Ph (10); [12]aneN3 =Me4[12]aneN3,
Introduction
Many enzymes, including those that hydrolyse phosphate
esters, use two metal ions in a bifunctional catalytic mecha-
nism.[1] For example, phosphotriesterases, which hydrolyse
phosphate triesters and have been employed as insecticides
and chemical warfare agents, require divalent metal ions
(Zn, Cd, Ni, Co, Mn) for their activities.[2] The binuclear
ZnII ion site of the phosphotriesterase (PTE) from Pseudo-
monas diminuta has been confirmed by a 2.1 ä resolution
X-ray crystal structure.[3] Nonredox-active metal ions such
as NiII and ZnII are potentially of interest as hydrolytic
cleaving agents. Moreover, their reactivity in model systems
may lead to functional DNA-cleaving molecules, because
synthetic metal complexes can be used as simple model sys-
tems for hydrolytic enzymes. To this purpose, dinuclear
CuII,[4] CoIII,[5] LaIII[6] or ZnII[7] complexes have been studied
in order to analyse the binding and activation of phosphate
[a] Dr. M. D. Santana, Prof. G. GarcÌa, A. A. Lozano, Prof. G. LÛpez
Departamento de QuÌmica Inorgµnica
Universidad de Murcia, 30071 Murcia (Spain)
Fax : (+34)968-364148
E-mail: ggarcia@um.es
[b] Dr. J. Tudela
Departamento de BioquÌmica y BiologÌa Molecular A
Universidad de Murcia, 30071 Murcia (Spain)
[c] Dr. J. Pÿrez, Dr. L. GarcÌa
Departamento de IngenierÌa Minera, GeolÛgica y Cartogrµfica
Universidad Politÿcnica de Cartagena
30203 Cartagena (Spain)
[d] Dr. L. Lezama, Prof. T. Rojo
Departamento de QuÌmica Inorgµnica
Facultad de Ciencias, Universidad del PaÌs Vasco
48080 Bilbao (Spain)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
1738
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/chem.200305367
Chem. Eur. J. 2004, 10, 1738 1746

1738 1746
esters. Interestingly, NiII-substituted phosphotriesterase has
a higher specific activity than the native ZnII enzyme.[2]
However, synthetic nickel(ii) complexes that are able to hy-
drolyse phosphate esters are rare.[8] Recently, in order to un-
derstand the mechanistic roles of the metal ions in phos-
phate ester hydrolysis, Yamaguchi et al. reported the hydrol-
ysis activities of hydroxo- or carboxylate-bridged dinuclear
NiII and CuII complexes.[9] They found that the hydrolysis ac-
tivities of the dinuclear NiII complexes were significantly
higher than those of the CuII and ZnII complexes. On the
other hand, Cheng and co-workers prepared an iron(iii)
nickel(ii) heterodinuclear complex with a bridging and a ter-
minal diphenylphosphate.[10] Although these nickel(ii) com-
plexes contained one bridging phosphate group, dinuclear
pentacoordinate nickel(ii) complexes bridged solely by two
phosphate ester (or phosphinate) ligands have not been re-
ported. Thus, to augment our understanding of hydroxo-
bridged dinickel(ii) complexes we here describe the synthe-
ses and characterisation of pentacoordinate dinuclear nick-
el(ii) complexes that contain two bridging phosphate ester
or phosphinate ligands. Moreover, we investigated the abili-
ty of the dinuclear nickel(ii) hydroxo complex [{Ni-
phinate-bridged complexes [{Ni([12]aneN3)(m-O2PR2)}2]-
(PF6)2 (9 12). These complexes are green or blue-green
solids that are stable to air both in the solid state and in sol-
ution. The new complexes have been characterised by parti-
al elemental analysis, FAB+ mass spectrometry and spectro-
scopic (UV-visible, IR, 1H NMR) techniques.
The electronic spectra of 1 12 are quite similar and show
two d d transitions in acetone with lmax (e) between 620
640 nm (~30mꢀ1 cmꢀ1) and 380–390 nm (~100mꢀ1 cmꢀ1).
3
These can be assigned to 3B1(F)! E(F) and 3B1(F)!
3A2,3E(P) transitions, respectively.[12] Both lmax values and
molar absorptivities are consistent with a five-coordinate en-
vironment around the nickel(ii) ion,[13] and provide evidence
that the molecule maintains its integrity in solution.
The IR spectra of complexes 1 12 show characteristic ab-
sorptions for the [12]aneN3 ligands[13]
:
3291 3258 cmꢀ1
ꢀ1
ꢀ
n(N H), ~1660 cm n(C=N), and two strong bands as a
ꢀ
result of the PF6 ion at 840 and 560 cmꢀ1. The IR spectra of
1 8 also exhibit two bands in the 1164 1045 and 924
905 cmꢀ1 regions; these can be assigned to the n((P)-O-C)
and n(P-O-(C)) vibrations, respectively.[14] The bands caused
by the na(PO2) and ns(PO2) vibrations fall in the 1264 1202
and 1122 976 cmꢀ1 regions, respectively, for complexes 1 8
and in the 1293 1189 and 1196 1077 cmꢀ1 regions for com-
plexes 9 12. The bands around 450 cmꢀ1 can be assigned to
(Me3[12]aneN3)(m-OH)}2](PF6)2
(Me3[12]aneN3 =2,4,4-tri-
methyl-1,5,9-triazacyclododec-1-ene) and its 9-methyl deriv-
ative (Me4[12]aneN3),[11] to promote the hydrolysis of phos-
phate esters. We also report a study conducted on the geo-
metrical conformation of the bridging unit and its role in
the magnetic interactions that arise between the nickel ions.
ꢀ
n(Ni O) vibrations.
The H NMR spectra of the complexes exhibit relatively
1
sharp and well-resolved resonances, and have a chemical
shift range that spans over 350 ppm. The representative
1H NMR spectra for complexes 7 and 10 are shown in Fig-
ures 1 and 2, respectively. Assignments of the relatively
sharp isotropically shifted resonances were made on the
basis of our previous experience with similar paramagnetic
pentacoordinate nickel(ii) complexes.[15] The spectra show
the expected resonance line pattern, and because of a domi-
nant spin-polarisation mechanism, the eight resonance sig-
nals for the a-CH protons are shifted downfield, whereas
the six resonance signals for the b-CH protons are shifted
upfield, with respect to the diamagnetic position. Further-
more, axial protons are expected to experience smaller con-
tact shifts than equatorial protons, because of the angular
dependence of the hyperfine coupling constant.[16] The spec-
tra of certain derivatives exhibited separate downfield reso-
Results and Discussion
The green bis(phosphate)-bridged dinuclear complexes
[{Ni([12]aneN3)(m-O2P(OR)2)}2](PF6)2 (1 8) can be prepared
in acetone in two different ways (Scheme 1). They can be
obtained by hydrolysis of the phosphate triester with the hy-
droxo complex [{Ni([12]aneN3)(m-OH)}2](PF6)2 (Scheme 1a)
or by acid base reaction of the dialkyl or diaryl phosphoric
acid and the above hydroxo complex (2:1 molar ratio)
(Scheme 1b). The hydrolytic synthesis afforded lower yields
of 1 8 and required longer reaction times. As described in
Scheme 1c, the acid base reaction provided higher yields
(82 93%) and could be applied to the synthesis of the phos-
Scheme 1. Scheme showing the different routes to complexes 1 12.
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

M. D. Santana, G. GarcÌa et al.
FULL PAPER
Figure 1. 1H NMR spectra (in [D6]acetone at room temperature) of com-
pound 7.
Figure 3. ORTEP plot of the cation of [{Ni(Me3[12]aneN3)(m-
O2P(OBu)2)}2](PF6)2 (2).
Figure 2. 1H NMR spectra (in [D6]acetone at room temperature) of com-
pound 10.
nances for the a-protons (Figure 1), whereas in other cases
the signals were not well resolved, because of the large line
width (Figure 2). Moreover, the isotropically shifted reso-
nance signals observed for the methyl groups appear as fol-
lows: 2-Me, ~ꢀ17 ppm; 4-Me(a,b), ~40 and 20 ppm; and 9-
Me, ~120 ppm.[15] The resonance signals for the alkyl and
aryl groups of the phosphate ester and phosphinate ligands
farthest from the nickel atom had smaller shifts with respect
to the diamagnetic position, and were all downfield from
the signal for TMS. This is to be expected in a system that
contains a dominant s-delocalisation pattern of spin density,
as well as two unpaired electrons in the ground state nick-
el(ii) s-symmetry orbitals (dx2ꢀy2, dz2). Finally, it is notewor-
thy that the magnitude of the downfield shifts is greatest for
the phosphinate derivatives (6.5 ppm for 1 versus 14.5 ppm
for 9).
Figure 4. ORTEP plot of the cation of [{Ni(Me3[12]aneN3)(m-
O2P(OPh)2)}2](PF6)2 (3).
Crystal structures: The crystal structures for the cations of
complexes 2, 3 and 12 are shown in Figures 3, 4 and 5, re-
spectively, while selected bond lengths and bond angles are
contained in Table 1.
The coordination geometry around the nickel atom is dis-
torted trigonal bipyramidal for 2 and distorted square pyra-
midal for 3. This can be ascertained by the Reedijk×s t pa-
rameter[17] (t=0 and 1 for square-pyramidal and trigonal-bi-
pyramidal structures, repectively), which has a value of 0.4
and 0.0 for complexes 2 and 3, respectively. In complex 12,
Figure 5. ORTEP plot of the cation of [{Ni(Me4[12]aneN3)(m-
O2PPh2)}2](PF6)2¥2Me2CO¥Et2O (12).
1740
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Chem. Eur. J. 2004, 10, 1738 1746

Pentacoordinate Nickel(ii) Complexes
1738 1746
Table 1. Selected bonds [ä] and angles [8] for 2, 3 and 12.
2
3
12
ꢀ
Ni1 N1
2.038(3)
2.056(3)
2.039(4)
2.034(3)
2.010(3)
2.030(4)
2.043(4)
2.034(4)
2.021(3)
2.022(3)
2.029(5)
2.044(5)
2.031(5)
2.026(4)
2.032(4)
2.053(4)
2.081(4)
2.065(5)
2.025(3)
2.027(3)
2.062(4)
2.079(4)
2.064(4)
1.988(3)
2.043(3)
88.43(17)
93.15(18)
99.78(17)
161.98(16)
90.32(15)
85.72(15)
163.19(15)
104.63(16)
97.02(16)
90.39(13)
88.10(16)
92.37(16)
102.36(16)
88.17(14)
172.64(14)
146.45(15)
90.77(15)
111.10(15)
94.97(14)
88.77(12)
ꢀ
Ni1 N2
ꢀ
Ni1 N3
ꢀ
Ni1 O1
ꢀ
Ni1 O2
ꢀ
Ni2 N4
ꢀ
Ni2 N5
ꢀ
Ni2 N6
ꢀ
Ni2 O3
ꢀ
Ni2 O4
ꢀ
ꢀ
N1 Ni1 N2
90.96(15)
91.9(2)
94.8(2)
101.4(2)
162.56(19)
90.6(2)
85.87(19)
163.82(19)
101.4(2)
ꢀ
ꢀ
N1 Ni1 N3
ꢀ
ꢀ
N2 Ni1 N3
ꢀ
ꢀ
N1 Ni1 O1
ꢀ
ꢀ
N1 Ni1 O2
ꢀ
ꢀ
N2 Ni1 O1
ꢀ
ꢀ
N2 Ni1 O2
ꢀ
ꢀ
N3 Ni1 O1
ꢀ
ꢀ
N3 Ni1 O2
95.61(18)
86.96(14)
ꢀ
ꢀ
O1 Ni1 O2
ꢀ
ꢀ
N4 Ni2 N5
ꢀ
ꢀ
N4 Ni2 N6
ꢀ
ꢀ
N5 Ni2 N6
ꢀ
ꢀ
N4 Ni2 O3
ꢀ
ꢀ
N4 Ni2 O4
ꢀ
ꢀ
N5 Ni2 O3
ꢀ
ꢀ
N5 Ni2 O4
ꢀ
ꢀ
N6 Ni2 O3
Figure 6. ORTEP view of the eight-membered rings of the bridge core
showing the atom-labelling scheme.
ꢀ
ꢀ
N6 Ni2 O4
ꢀ
ꢀ
O3 Ni2 O4
the geometry around each nickel atom is very different (t=
0.0 and 0.4 for Ni1 and Ni2, respectively).
The coordinated macrocycles in complexes 2 and 12 ex-
hibit chairlike conformations in the two six-membered rings
that do not contain the C=N bond. This is the most frequent
conformation in complexes that contain such macrocycles.[18]
In accord with the classification from Allen et al.,[19] the
eight-membered rings defined by the nickel atoms and the
bridging ligands show a distorted twist-boat, chair and
boat boat conformation for complexes 2, 3 and 12, respec-
tively (Figure 6). The torsion angles in the complexes do not
conform to the ideal of around 208.
The Ni¥¥¥Ni distances are 4.863(1), 5.424(1) and 5.116(1) ä
for 2, 3 and 12, respectively. These distances indicate a flat-
tening of the eight-membered ring that constitutes the
bridge core (least-square planes defined by the eight-mem-
bered ring have a root mean square (rms) of 0.502, 0.097
and 0.419 for 2, 3 and 12, respectively). Moreover, the
Ni¥¥¥Ni distance for 3 is longer than those reported for the
[M2(m-phosphato)2] core (M¥¥¥M is 4.189 ä when M=Fe,[20]
and ranges from 4.931 to 5.367 ä when M=V[21,22]).
Magnetic properties: The thermal variation of the inverse of
the magnetic molar susceptibility (cmꢀ1) and the cmT product
for compounds 2, 3 and 12 are shown in Figure 7. As can be
seen, the Curie Weiss law is only followed in the high tem-
perature range. Values of Cm =2.42 (2), 2.45 (3) and
2.41 cm3 Kmolꢀ1 (12), and q=ꢀ0.7 (2), ꢀ2.6 (3) and ꢀ0.8 K
(12) have been calculated. In each case the cmT product de-
creases as the temperature decreases, and this occurs more
ꢀ1
Figure 7. Thermal evolution of cm and cmT for compounds 2 (a), 3 (b)
and 12 (c). Solid lines on the cmT curves correspond to the best fits ob-
tained using the Ginsberg equation. Solid lines on the cm curves corre-
spond to the expected Curie Weiss behaviour.
ꢀ1
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¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

M. D. Santana, G. GarcÌa et al.
FULL PAPER
Table 2. Selected distances and angles for Ni-O-P-O-Ni magnetic-ex-
change pathways for complexes 2, 3 and 12 (atom labels are given in
Figure 6).
rapidly below 50 K. This behaviour, which is usually associ-
ated with a large nickel(ii) single-ion zero-field splitting, in-
dicates the existence of a weak antiferromagnetic coupling
between the metallic centers.
For the theoretical analysis of the magnetic behaviour of
compounds 2, 3 and 12, the analytical expression developed
by Ginsberg et al.[23] was used. This is based upon the fol-
lowing Hamiltonian in which the nickel(ii) ion is assumed to
be magnetically isotropic [Eq. (1)]:
ꢀ
Interacting atoms
Ni Ni[a] [ä]
Ni-O-P [8]
P-O-Ni [8]
2
Ni1-O1-P1-O2-Ni2
Ni1-O4-P2-O3-Ni2
7.028(3)
7.018(3)
146.7(2)
128.2(19)
132.6(2)
151.3(2)
3
Ni1-O1-P1-O2-Ni2
7.014(4)
136.5(2)
157.2(3)
148.9(2)
12
Ni1-O1-P2-O3-Ni2
Ni1-O2-P1-O4-Ni2
7.022(3)
7.073(3)138.6(2)
154.7(2)
139.5(2)
H ¼ ꢀ2JS1S2ꢀDðS1z2 þ S2z2 ÞꢀgbHðS1 þ S2Þꢀz0J0ShSi
ð1Þ
[a] Length of exchange pathway.
In Equation (1) J is the usual intradimeric exchange pa-
rameter, while D is the zero-field splitting of the single-ion
ground state in which a negative value corresponds to the
Ms =0 value lying below the M1 =Æ1 doublet. Because of
the possible interdimer contacts, a mean field correction
term to the Hamiltonian, which is parameterised by z’J’, was
also included. It is worth mentioning that the parameters D
and z’J’ are very strongly correlated to each other, but are
only weakly correlated to g and J. As a result, the estimated
g and J values are more accurate than the D and z’J’ values.
ꢀ ꢀ
consequence of the favourable disposition of the O P O
bridges; these are practically coplanar with the dx2ꢀy2 mag-
netic orbitals in the NiII ions (see Figure 6). The coordina-
tion geometry around the nickel atoms is square pyramidal
for 3. The basal atoms and the bridging ligands define a
least-square plane that has an rms of 0.211, and the Ni
atoms are displaced 0.291(2) ä out of the basal plane
toward the apical atom. To our knowledge, the present com-
plexes are the first pentacoordinate nickel(ii) compounds
with this type of bridge. Moreover, in six-coordinated NiII
phosphates/phosphonates, even if this type of bridge is not
unusual, the exchange interactions are mainly propagated
through oxygen atoms shared by two adjacent polyhedra.
Therefore, a comparative analysis of the sign and strength of
the magnetic interactions cannot be carried out. However, it
is noteworthy that the study performed by Gao et al. on a
family of NiII diphosphonates, in which nickel(ii) is simulta-
neously six-, five- and fourfold coordinate, indicates the ex-
istence of very weak exchange interactions that have mag-
netic orderings below 4 K.[29]
The experimental susceptibility data for compounds 2, 3
and 12 were least-squares fitted to the analytical expression
given by Ginsberg. The best fit was obtained with values of:
J=ꢀ0.11 cmꢀ1, D=ꢀ9.5 cmꢀ1 and g=2.20 (2); J=
ꢀ0.97 cmꢀ1, D=ꢀ9.3 cmꢀ1 and g=2.21 (3); and J=
ꢀ0.14 cmꢀ1, D=ꢀ11.9 cmꢀ1 and g=2.195 (12). Introduction
of a reasonable z’J’ parameter did not improve the quality
of the fit and this term was finally neglected. The excellent
agreement between the experimental and calculated data
for the three compounds can be observed in Figure 7. The
zero-field splitting of octahedral NiII compounds and the
consequences this has on the magnetic properties have been
extensively studied.[24] High D values, as large as 20 cmꢀ1 in
some compounds, are commonly observed in distorted envi-
ronments.[25] However, calculations for D terms on NiII pen-
tacoordinate complexes are not available. To support the
validity of the D values obtained for compounds 2, 3 and 12,
EPR measurements were carried out at X band, but no sig-
nals were observed in the temperature range 4.2 300 K.
These results are in good agreement with the values calcu-
lated for the zero-field splitting parameters. In considering
the structural features exhibited by these compounds, the
magnetic exchange pathways must involve the phosphate/
Kinetics of the tris(4-nitrophenyl)phosphate hydrolysis: We
examined the hydrolysis of TNP (tris(4-nitrophenyl)phos-
phate) with the dinuclear nickel(ii) hydroxo complex [{Ni-
ꢀ
(Me3[12]aneN3)(m-OH)}2](PF6)2 (L1Ni OH) as a model re-
action for PTE by UV-visible spectroscopy. The proposed
mechanism for TNP hydrolysis by the dinuclear metal com-
plex can be described as one-substrate/two-product
(Scheme 2); this is analogous to the enzymatic catalysis of
phosphinate bridges (Ni O P O Ni). From 31P NMR stud-
ꢀ ꢀ ꢀ ꢀ
ies it is well known that spin transfer through s and p phos-
phorous orbitals plays an important role in the exchange
mechanisms of many transition-metal phosphates.[26,27]
Moreover, these types of exchange pathways usually favour
antiferromagnetic interactions. If the angles that correspond
Scheme 2. One-substrate/two-product mechanism for TNP hydrolysis in
the presence of a dinuclear NiII complex.
to the Ni O P O Ni exchange pathways (Table 2) and
PTE proposed recently.[30] The steady-state rate of 4-nitro-
phenol (4NP) formation (Vo) should display an hyperbolic
dependence with TNP and must be able to be fitted to a Mi-
chaelis Menten equation [Eq. (2)]:
ꢀ ꢀ ꢀ ꢀ
Goodenough×s rules[28] are taken into account, the interac-
tions in compounds 2, 3 and 12 were expected to be antifer-
romagnetic, and indeed, are in good agreement with the ex-
perimental results. The low calculated J values are not sur-
prising if one considers the relatively large distances be-
tween paramagnetic centers (See Table 2). The higher ex-
Vmax½TNPŠ
kcat½L1NiꢀOHŠ ½TNPŠ
0
0
0
ð2Þ
V0 ¼
¼
KM þ ½TNPŠ
KM þ ½TNPŠ
0
0
change parameter observed for compound
3
is
a
1742
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 1738 1746

Pentacoordinate Nickel(ii) Complexes
1738 1746
in which kcat =k2k3/(k2 +k3) and KM =k3(kꢀ1 +k2)/k1(k2 +k3).
The proposed molecular mechanism is depicted in
Scheme 3. In this mechanism, TNP binds to the nickel(ii)
Figure 8. Michaelis Menten kinetics for the hydrolysis of TNP with
ꢀ
!
*
L1Ni OH. Acetone ( ), MeCN ( ), and nonlinear regression fitted to
Scheme 3. Proposed molecular mechanism for the hydrolysis of phos-
phate triesters in the presence of a dinuclear NiII complex.
ꢀ
Equation (2) (c). Assay conditions: 2.5% H2O, [L1Ni OH]=10mm,
208C.
atom by coordinating to the phosphoryl oxygen. This inter-
action then weakens the binding of the bridging hydroxide
to the second nickel(ii) atom. The metal oxygen interaction
polarises the phosphoryl oxygen bond and makes the phos-
phorous atom more electrophilic. As a consequence of the
nucleophilic attack by the bound hydroxide, the bond to the
leaving group weakens. In the next step, a molecule of 4NP
is released and a dinuclear nickel(ii) complex in which a
phosphate diester bridges the nickel atoms is obtained. Fi-
nally, the diester phosphate is displaced by a water molecule
to regenerate the catalyst. This mechanism is supported by
the crystal structure of the nickel(ii) complex which has two
bridging phosphodiesters and was prepared by triester phos-
phate hydrolysis.
Table 3. Kinetic parameters[a] for L1Ni OH hydrolysis of TNP.
ꢀ
Solvent
kcat [sꢀ1 î102]
KM [mm]
kcat/KM [mꢀ1 sꢀ1
]
acetone
MeCN
7.3Æ0.1
4.1Æ0.1
0.25Æ0.01
0.40Æ0.03
292Æ12
103Æ8
ꢀ
[a] Assay conditions: 2.5% H2O, [L1Ni OH]=10mm, 208C. Nonlinear
regression fitted to Equation (2), R2 >0.99.
1.6î10ꢀ3 sꢀ1. If the different reaction media are not consid-
ered, then the kinetic parameters for the [{Ni(Me3[12]-
aneN3)(m-OH)}2](PF6)2 hydrolysis of TNP are an improve-
ment on the previously published results for other models,
but are still a far cry from the kinetic parameters obtained
for the paraoxon hydrolysis of PTE[30] (kcat =3000 sꢀ1 and
kcat/KM =5¥107 mꢀ1 sꢀ1).
ꢀ
The solubilities of TNP and (L1Ni OH) were tested in
several organic solvents. The best results were obtained with
acetone and MeCN. A kinetic study was carried out in
which the linearity of the time-drive recordings, the negligi-
ble TNP hydrolysis in the absence of catalyst, as well as the
Experimental Section
ꢀ
concentration effects of H2O, L1Ni OH and TNP were
General methods: C, H and N analyses were carried out with a microana-
lyser Carlo Erba model EA 1108. Infrared spectra were recorded on a
Perkin Elmer 16F PC FT-IR spectrophotometer on Nujol mulls between
polyethylene sheets. The UV-visible spectra (in acetone) were recorded
over the 300 800 nm range on a UNICAM 520 spectrophotometer equip-
ped with matched quartz cells. The 1H NMR spectra were recorded on a
Bruker model AC 200E or a Bruker AV-400 spectrometer. Fast-atom
bombardment (FAB) mass spectra were run on a Fisons VG Autospec
spectrometer operating in the FAB+ mode. Magnetic susceptibilities of
powdered samples were measured in the 5 300 K temperature range with
a Quantum Design MPMS-7 SQUID magnetometer. The experimental
susceptibilities were corrected for the diamagnetism of the sample hold-
ers and the constituent atoms (Pascal tables), as well as for temperature-
independent paramagnetism (estimated to be 100î10ꢀ6 cm3 molꢀ1). A
Bruker ESP300 spectrometer operating at X band and equipped with
standard Oxford low-temperature devices was used to record the ESR
powder spectra at different temperatures. The magnetic field was cali-
brated by an NMR probe and the frequency inside the cavities was deter-
mined with a Hewlett Packard 5352B microwave frequency counter.
Most chemicals were purchased from Aldrich and were used without fur-
ther purification. Tris(4-nitrophenyl)phosphate (TNP) was obtained from
Fluka, whereas acetone and acetonitrile (MeCN) of chromatographic
quality (<0.1% water) were purchased from Merck. Milli-Q system (Mil-
taken into consideration (Supporting Information). The ki-
netic behaviour followed the Michaelis Menten model
[Eq. (2)]. Plots of the hydrolysis rate (V0) against [TNP]0
gave a saturation curve (Figure 8). In accordance with the
reaction mechanism proposed, this fact suggests the reversi-
ble formation of a (L1Ni-TNP) complex prior to TNP hy-
drolysis. Thus, the Michaelis Menten equation was applied,
and the catalytic (kcat) and Michaelis constant (KM) were de-
termined by nonlinear regression fittings (Table 3).
Only a few kinetic studies on the hydrolysis of phospho-
triesters have been undertaken, and most of them have been
conducted in aqueous media. Kady et al.[31] found that mono-
nuclear ZnII models with N3 and N3O ligands showed kobs
values of between 4.5î10ꢀ2 and 1.5î10ꢀ6 sꢀ1 for diethyl(4-
nitrophenyl)phosphate hydrolysis in water. Itoh et al.[32]
studied the catalytic hydrolysis of 2,4-dinitrophenyl ethyl-
phosphate using mononuclear CuII complexes with N3 li-
gands. These displayed kcat values of between 0.7î10ꢀ6 and
1743
Chem. Eur. J. 2004, 10, 1738 1746
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

M. D. Santana, G. GarcÌa et al.
FULL PAPER
lipore Corp.) ultrapure water was used. Solvents were dried and distilled
by general methods before use. The complexes [{Ni(Me3[12]aneN3)(m-
C42H90F12N6Ni2O8P4 (1276.5): C 39.52, H 7.11, N 6.58; found: C 39.35, H
7.31, N 6.54.
Compound 7: 1H NMR ([D6]acetone, TMS): d=303.1 (Ha), 282.9 (Ha),
265.6 (Ha), 202.0 (Ha), 127.8 (3H; 9-Me), 83.2 (Ha), 50.0 (3H; 4-Me),
40.0 (Ha), 34.2 (Ha), 22.5 (3H; 4-Me), 16.3 (Ha), 8.3 (3H; OPh), 7.5 (2H;
OPh), ꢀ10.1 (2H; Hb), ꢀ13.8 (Hb), ꢀ18.5 (3H; 2-Me), ꢀ27.4 (Hb), ꢀ35.1
OH)}2](PF6)2
(Me3[12]aneN3 =2,4,4-trimethyl-1,5,9-triazacyclododec-1-
ene) and its 9-methyl derivative (Me4[12]aneN3) were prepared by previ-
ously described procedures.[11]
[{Ni([12]aneN3)(m-O2P(OR)2)}2](PF6)2 {[12]aneN3 =Me3[12]aneN3, R=
Me (1),Bu (2),Ph (3),Ph-4-NO
(5),Bu (6),Ph (7),Ph-4-NO
ꢀ
(Hb), ꢀ35.8 ppm (Hb); IR (nujol): n˜ =3262 (N H), 1660 (C=N), 1204
(4); [12]aneN3 =Me4[12]aneN3, R=Me
2
(PO2)a, 1164 ((P)-O-C), 1122 (PO2)s, 924 (P-O-(C)), 480 cmꢀ1 (Ni O);
ꢀ
(8)}: Complexes 1 8 were prepared by re-
2
MS (FAB+): m/z (%): 1209 (12) [M]+, 532 (100) [M/2]+ ; elemental anal-
ysis calcd (%) for C50H74F12N6Ni2O8P4 (1356.4): C 44.27, H 5.50, N 6.20;
found: C 44.34, H 5.68, N 6.01.
action of [{Ni([12]aneN3)(m-OH)}2](PF6)2 (0.12 mmol) with the corre-
sponding tris(alkyl) or tris(aryl) phosphate (0.24 mmol) in acetone
(25 mL). After stirring for 24 h the solution was concentrated under re-
duced pressure, and upon addition of diethyl ether a green solid precipi-
tated. This was collected by filtration, washed with diethyl ether and air-
dried. Yields: 57 78%. Higher yields of 1 8 were obtained from a mix-
ture of [{Ni([12]aneN3)(m-OH)}2](PF6)2 (0.12 mmol) and dialkyl or diaryl
phosphoric acid (0.24 mmol) in acetone (25 mL). After stirring for 3 h
the solutions were handled in a manner analogous to that described
above. Yields: 82 93%.
Compound 8: 1H NMR ([D6]acetone, TMS): d=314.2 (Ha), 285.7 (Ha),
271.6 (Ha), 215.7 (Ha), 131.4 (3H; 9-Me), 82.3 (Ha), 55.8 (3H; 4-Me),
40.7 (Ha), 36.1 (Ha), 23.2 (3H; 4-Me), 15.1 (Ha), 8.7 (2H; OPh-4-NO2),
7.5 (2H; OPh-4-NO2), ꢀ9.7 (2H; Hb), ꢀ13.6 (Hb), ꢀ18.2 (3H; 2-Me),
ꢀ
ꢀ27.6 (Hb), ꢀ36.0 ppm (2H; Hb); IR (nujol): n˜ =3267 (N H), 1661 (C=
N), 1213 (PO2)a, 1161 ((P)-O-C), 1102 (PO2)s, 906 (P-O-(C)), 449 cmꢀ1
+
+
(Ni O); MS (FAB ): m/z (%): 1388 (4) [M] , 622 (100) [M/2]+ ; elemen-
tal analysis calcd (%) for C50H70F12N10Ni2O16P4 (1536.4): C 39.09, H 4.59,
N 9.12; found: C 39.03, H 4.86, N 8.97.
ꢀ
Compound 1: 1H NMR ([D6]acetone, TMS): d=236.1 (Ha), 234.3 (Ha),
201.6 (Ha), 89.5 (Ha), 48.2 (3H; 4-Me), 33.8 (Ha), 32.4 (Ha), 28.7 (Ha),
21.8 (3H; 4-Me), 16.5 (Ha), 6.5 (3H; OMe), ꢀ9.7 (Hb), ꢀ13.1 (2H; Hb),
ꢀ16.9 (3H; 2-Me), ꢀ27.8 (Hb), ꢀ33.1 (Hb), ꢀ34.6 ppm (Hb); IR (nujol):
[{Ni([12]aneN3)(m-O2PR2)}2](PF6)2 {[12]aneN3 =Me3[12]aneN3, R=Me
(9),Ph (10); [12]aneN 3 =Me4[12]aneN3, R=Me (11),Ph (12)} : Com-
plexes 9 12 were prepared by allowing [{Ni([12]aneN3)(m-OH)}2](PF6)2
(0.12 mmol) to react with the corresponding alkyl or aryl phosphinic acid
(0.24 mmol) in acetone (25 mL). After stirring for 30 min, the solvent
was removed under reduced pressured and diethyl ether was added to
the solution. This was then cooled to ꢀ188C, and the resultant blue-
green solid was collected by filtration, washed with diethyl ether and air-
dried.
ꢀ
n˜ =3286, 3259 (N H), 1662 (C=N), 1242 (PO2)a, 1045 ((P)-O-C), 981
(PO2)s, 908 (P-O-(C)), 469 cmꢀ1 (Ni O); MS (FAB ): m/z (%): 394 (100)
+
ꢀ
[M/2]+ ; elemental analysis calcd (%): for C28H62F12N6Ni2O8P4 (1080.1): C
31.14, H 5.79, N 7.78; found: C 31.05, H 6.10, N 7.71.
Compound 2: 1H NMR ([D6]acetone, TMS): d=235.9 (Ha), 234.0 (Ha),
202.4 (Ha), 89.4 (Ha), 49.1 (3H; 4-Me), 34.5 (Ha), 32.9 (Ha), 28.7 (Ha),
21.9 (3H; 4-Me), 17.1 (Ha), 7.9 (2H; OCH2), 4.4 (2H; CH2), 3.2 (2H;
CH2), 1.3 (3H; CH3), ꢀ9.9 (Hb), ꢀ13.3 (2H; Hb), ꢀ17.2 (3H; 2-Me),
ꢀ27.9 (Hb), ꢀ33.6 (Hb), ꢀ35.1 ppm (Hb); IR (nujol): n˜ =3286, 3258
Compound 9: Yield: 0.110 g (97%); 1H NMR ([D6]acetone, TMS): d=
236.4 (Ha),185.0 (Ha), 86.5 (Ha), 42.1 (3H; 4-Me), 36.2 (Ha), 30.5 (Ha),
28.5 (Ha), 27.1 (Ha), 21.6 (3H; 4-Me), 19.0 (Ha), 14.5 (3H; Me), ꢀ8.9
(Hb), ꢀ13.1 (2H; Hb), ꢀ17.0 (3H; 2-Me), ꢀ27.5 (Hb), ꢀ32.9 (Hb),
ꢀ
(N H), 1660 (C=N), 1245 (PO2)a, 1065 ((P)-O-C), 976 (PO2)s, 905 (P-O-
(C)), 468 cmꢀ1 (Ni O); MS (FAB ): m/z (%): 1101 (4) [M] , 478 (100)
[M/2]+ ; elemental analysis calcd (%) for C40H86F12N6Ni2O8P4 (1248.4): C
38.48, H 6.94, N 6.73; found: C 38.36, H 6.75, N 6.91.
+
+
ꢀ
ꢀ
ꢀ34.1 ppm (Hb); IR (nujol): n˜ =3291, 3266 (N H), 1660 (C=N), 1293
ꢀ1
+
ꢀ
ꢀ
(PO2)a, 1196 (PO2)s, 1065 (P C), 449 cm (Ni O); MS (FAB ): m/z
(%): 869 (7) [M]+, 362 (100) [M/2]+ ; elemental analysis calcd (%) for
C28H62F12N6Ni2O4P4 (1016.1): C 33.10, H 6.15, N 8.27; found: C 33.09, H
6.23, N 8.21.
Compound 3: 1H NMR ([D6]acetone, TMS): d=250.0 (Ha), 219.5 (Ha),
89.2 (2H; Ha), 53.5 (3H; 4-Me), 37.1 (Ha), 36.7 (Ha), 32.9 (Ha), 22.4
(3H; 4-Me), 17.5 (Ha), 7.9 (3H; OPh), 7.3 (2H; OPh), ꢀ10.1 (Hb), ꢀ13.8
(2H; Hb), ꢀ18.3 (3H; 2-Me), ꢀ28.3 (Hb), ꢀ34.8 (Hb), ꢀ36.1 ppm (Hb);
Compound 10: Yield: 0.133 g (95%); 1H NMR ([D6]acetone, TMS): d=
237.8 (2H; Ha), 202.0 (Ha), 87.9 (Ha), 42.6 (3H; 4-Me), 36.6 (2H; Ha),
29.0 (2H; Ha), 21.7 (3H; 4-Me), 11.5 (2H; Ph), 10.0 (2H; Ph), 7.7 (1H;
Ph), ꢀ10.1 (Hb), ꢀ13.5 (2H; Hb), ꢀ17.5 (3H; 2-Me), ꢀ28.2 (Hb), ꢀ34.2
ꢀ
IR (nujol): n˜ =3278, 3260 (N H), 1658 (C=N), 1202 (PO2)a, 1102 ((P)-O-
C), 1024 (PO2)s, 910 (P-O-(C)), 444 cmꢀ1 (Ni O); MS (FAB ): m/z (%):
+
ꢀ
1181 (5) [M]+, 518 (100) [M/2]+ ; elemental analysis calcd (%) for
C48H70F12N6Ni2O8P4 (1328.4): C 43.40, H 5.31, N 6.33; found: C 43.45, H
5.53, N 6.30.
ꢀ
(Hb), ꢀ35.8 ppm (Hb); IR (nujol): n˜ =3272 (N H), 1657 (C=N), 1189
ꢀ1
+
ꢀ
ꢀ
(PO2)a, 1130 (PO2)s, 1044 (P C), 456 cm (Ni O); MS (FAB ): m/z
(%): 1118 (6) [M]+, 486 (100) [M/2]+ ; elemental analysis calcd (%) for
C48H70F12N6Ni2O4P4 (1264.4): C 45.60, H 5.58, N 6.65; found: C 45.42, H
5.60, N 6.61.
Compound 4: 1H NMR ([D6]acetone, TMS): d=251.6 (Ha), 232.6 (Ha),
91.4 (2H; Ha), 56.8 (3H; 4-Me), 40.3 (Ha), 34.5 (2H; Ha), 22.4 (3H; 4-
Me), 18,3 (Ha), 8.6 (2H; OPh-4-NO2), 7.3 (2H; OPh-4-NO2), ꢀ9.7 (Hb),
ꢀ13.5 (2H; Hb), ꢀ17.1 (3H; 2-Me), ꢀ28.5 (Hb), ꢀ34.7 (Hb), ꢀ35.9 ppm
Compound 11: Yield: 0.096 g (82%); 1H NMR ([D6]acetone, TMS): d=
271.6 (2H; Ha), 259.5 (Ha), 168.7 (Ha), 109.8 (3H; 9-Me), 80.3 (Ha), 37.3
(3H; 4-Me), 28.9 (2H; Ha), 21.6 (3H; 4-Me), 18.5 (Ha), 12.8 (3H; Me),
ꢀ8.7 (Hb), ꢀ11.5 (Hb), ꢀ13.0 (Hb), ꢀ17.4 (3H; 2-Me), ꢀ26.4 (Hb), ꢀ31.9
ꢀ
(Hb); IR (nujol): n˜ =3266 (N H), 1662 (C=N), 1213 (PO2)a, 1161 ((P)-O-
C), 1098 (PO2)s, 910 (P-O-(C)), 452 cmꢀ1 (Ni O); MS (FAB ): m/z (%):
+
ꢀ
1361 (4) [M]+, 608 (22) [M/2]+
;
elemental analysis calcd (%) for
ꢀ
C48H66F12N10Ni2O16P4 (1508.4): C 38.22, H 4.41, N 9.29; found: C 37.97, H
4.63, N 9.21.
(Hb), ꢀ33.7 ppm (Hb); IR (nujol): n˜ =3269 (N H), 1658 (C=N), 1203
ꢀ1
+
ꢀ
ꢀ
(PO2)a, 1077 (PO2)s, 1026 (P C), 435 cm (Ni O); MS (FAB ): m/z
(%): 897 (6) [M]+, 376 (100) [M/2]+ ; elemental analysis calcd (%) for
C30H66F12N6Ni2O4P4 (1044.1): C 34.51, H 6.37, N 8.05; found: C 34.39, H
6.34, N 7.99.
Compound 5: 1H NMR ([D6]acetone, TMS): d=292.5 (Ha), 267.0 (Ha),
250.3 (Ha), 186.0 (Ha), 118.2 (3H; 9-Me), 83.9 (Ha), 46.4 (3H; 4-Me),
41.4 (Ha), 32.7 (Ha), 22,5 (3H; 4-Me), 16.1 (Ha), 6.9 (3H; OMe), ꢀ9.5
(2H, Hb), ꢀ12.7 (Hb), ꢀ17.4 (3H; 2-Me), ꢀ27.4 (Hb), ꢀ33.4 (Hb),
Compound 12: Yield: 0.132 g (91%); 1H NMR ([D6]acetone, TMS): d=
285.8 (Ha), 254.6 (Ha), 246.5 (Ha), 185.3 (Ha), 118.2 (3H; 9-Me), 86.0
(2H; Ha), 36.7 (3H; 4-Me), 28.7 (2H; Ha), 20.4 (3H; 4-Me), 12.7 (2H;
Ph), 10.5 (2H; Ph), 8.3 (1H; Ph), ꢀ9.8 (Hb), ꢀ11.8 (Hb), ꢀ12.9 (Hb),
ꢀ17.6 (3H; 2-Me), ꢀ27.7 (Hb), ꢀ33.5 (Hb), ꢀ35.0 ppm (Hb); IR (nujol):
ꢀ
ꢀ34.7 ppm (Hb); IR (nujol): n˜ =3267 (N H), 1658 (C=N), 1264 (PO2)a,
1107 ((P)-O-C), 1058 (PO2)s, 909 (P-O-(C)), 466 cmꢀ1 (Ni O); MS
ꢀ
(FAB+): m/z (%): 961 (5) [M]+, 408 (100) [M/2]+ ; elemental analysis
calcd (%) for C30H66F12N6Ni2O8P4 (1108.1): C 32.52, H 6.00, N 7.58;
found: C 32.36, H 6.10, N 7.53.
ꢀ
ꢀ
+
n˜ =3266 (N H), 1658 (C=N), 1194 (PO2)a, 1128 (PO2)s, 1045 (P C),
+
+
456 cmꢀ1 (Ni O); MS (FAB ): m/z (%): 1146 (5) [M] , 500 (100) [M/2]
Compound 6: 1H NMR ([D6]acetone, TMS): d=292.4 (Ha), 271.1 (Ha),
248.6 (Ha), 184.3 (Ha), 118.2 (3H; 9-Me), 84.9 (Ha), 45.5 (3H; 4-Me),
33.9 (Ha), 31.8 (Ha), 22.5 (3H; 4-Me), 14.1 (Ha), 8.5 (2H; OCH2), 3.5
(2H; CH2), 3.1 (2H; CH2), 1.5 (3H; CH3), ꢀ9.3 (Hb), ꢀ10.0 (Hb), ꢀ12.5
(Hb), ꢀ17.4 (3H; 2-Me), ꢀ27.6 (Hb), ꢀ34.0 (Hb), ꢀ34.8 ppm (Hb); IR
ꢀ
; elemental analysis calcd (%) for C50H74F12N6Ni2O4P4¥2Me2CO¥Et2O
(1482.7): C 48.60, H 6.52, N 5.67; found: C 48.45, H 6.46, N 5.81.
Determination of the X-ray crystal structure of compounds 2,3 and 12 :
Crystals of [{Ni(Me3[12]aneN3)(m-O2P(OBu)2)}2](PF6)2 (2), [{Ni(Me3[12]-
aneN3)(m-O2P(OPh)2)}2](PF6)2 (3) and [{Ni(Me4[12]aneN3)(m-O2PPh2)}2]-
(PF6)2¥2Me2CO¥Et2O (12) suitable for X-ray diffraction studies were
grown from acetone/diethyl ether liquid diffusion. In all cases, crystals
ꢀ
(nujol): n˜ =3264 (N H), 1658 (C=N), 1230 (PO2)a, 1100 ((P)-O-C), 1028
(PO2)s, 909 (P-O-(C)), 462 cmꢀ1 (Ni O); MS (FAB ): m/z (%): 1130 (3)
+
ꢀ
[M]+, 492 (100) [M/2]+
;
elemental analysis calcd (%) for
1744
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 1738 1746

Pentacoordinate Nickel(ii) Complexes
1738 1746
Table 4. Crystal data and structure refinement for 2, 3 and 12.
2
3
12
formula
Mr
C40H86F12N6Ni2O8P4
1248.45
C48H70F12N6Ni2O8P4
1328.40
C50H74F12N6Ni2O4P4¥2Me2CO¥Et2O
1482.73
crystal system
a [ä]
b [ä]
c [ä]
a [8]
monoclinic
12.0309(9)
20.3278(12)
12.6585(11)
triclinic
triclinic
10.1955(9)
11.1727(9)
13.1453(11)
99.699(6)
96.955(6)
104.977(5)
1404.4(2)
173(2) K
P1
1
12.5277(16)
13.0101(12)
24.744(2)
99.698(7)
96.253(9)
116.679(9)
3473.2(6)
173(2)
90
b [8]
g [8]
111.285(6)
90
2884.6(4)
173(2)
P2(1)
2
V [ä3]
T [K]
space group
Z
P1
2
l [ä]
0.71073
0.852
0.71073
0.881
0.71073
0.719
m [mmꢀ1
]
reflections collected
10630
7782
12686
independent reflections
goodness of fit on F2
final R indices [I>2s(I)][a,b]
R indices (all data)[a,b]
10152 (Rint =0.0172)
1.033
R1 =0.0454, wR2 =0.1200
R1 =0.0515, wR2 =0.1242
1.074/ꢀ0.495
4902 (Rint =0.0259)
1.053
12082 (Rint =0.0281)
0.873
R1 =0.0560, wR2 =0.1369
R1 =0.1022, wR2 =0.1528
0.681/ꢀ0.607
R1 =0.0642, wR2 =0.1732
R1 =0.0869, wR2 =0.1857
0.666/ꢀ0.608
max/min D1 [eäꢀ3
]
1
2
[a] R1 =ꢀkFo jꢀjFc k/SjFo j for reflections with I>2sI. [b] wR2 ={ꢀ[w(F2oꢀF2c)2]/S[w(F2o)2]} = for all reflections; wꢀ1 =s2(F2)+(aP)2 +bP, in which
P=(2F2c +F2o)/3 and a and b are constants set by the program.
were mounted on glass fibres and transferred to a Siemens P4 diffractom-
eter. The crystallographic data are summarised in Table 4. Cell constants
were refined from 65 (2), 57 (3) or 64 (12) reflections in the 2q range 10
258. The structures were solved by the heavy-atom method and refined
anisotropically.[33] Hydrogen atoms were included using a riding model.
For compound 3, the macrocycle that involves N1 and N3, a phenyl
group and the (PF6)ꢀ ion are disordered over two positions.
support (Project BQU2001 0979-C02). A.A.L. thanks FundaciÛn Seneca
for an FPI-grant.
[1] a) E. Kimura, Prog. Inorg. Chem. 1994, 41, 443 491; b) W. N. Lips-
comb, N. Str‰ter, Chem. Rev. 1996, 96, 2375 2434; c) D. E. Wilcox,
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Kinetic analysis: In order to define the best assay conditions, UV-visible
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ꢀ
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ꢀ
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Acknowledgements
We thank the FundaciÛn Sÿneca, CARM (Projects PI-32/00800/FS/01 and
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Received: July 23, 2003
Revised: October 13, 2003 [F5367]
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Chem. Eur. J. 2004, 10, 1738 1746