Synthesis, characterization and molecular structures of homo- and heterometallic nickel(II) aminoalkoxides

Article abstract of DOI:10.1016/S0277-5387(01)00814-2

Soluble Ni(II) alkoxides, namely the dimethylaminoisopropoxide clathrate with toluene, Ni(η²-OR^N)₂· C₇H₈ (I) and the solvent free crystalline Ni(OR^N)₂(R^N = CHMeCH₂NMe₂) species (II), obtained by sublimation of I in vacuo, were characterized by X-ray diffraction. The reaction between Ni(OR^N)₂ and copper carboxylates such as propionate and copper acetate hydrate in hydrocarbons afforded [CuNi₂(O₂CEt)₃(OR^N)₃ (R^NOH)] (III) and [Ni(Ni_0.25Cu_0.75)₂(μ₃-OH) (μ-OAc)(η¹-OAc)₂(μ,η²-OR ^N)₂(η²-R^NOH)] (IV), respectively. The structures of I and II are based on square planar molecules of the trans isomer. The structure of IV corresponds to triangular aggregates with a M₃(μ₃-OH) central core. The remarkable feature is the presence of three types of coordination sphere, one metal is coordinated octahedrally and corresponds to nickel and the other two have square pyramidal and square planar coordinations, respectively, and an electronic density corresponding to Cu (75%) and Ni (25%). The monodentate behavior of the two acetato ligands is stabilized by intramolecular hydrogen bonding involving the hydroxyl functionalities of the μ₃-hydroxo (2.776(9) A?) and the solvated aminoalcohol ligand (2.573(6) A?). Magnetic data in the 20-300 K temperature range for III and IV account for three uncoupled metal centers at high temperature whereas ferromagnetic exchange interactions are likely below 20 K.

Full text of DOI:10.1016/S0277-5387(01)00814-2

Polyhedron 20 (2001) 2163–2169
www.elsevier.com/locate/poly
Synthesis, characterization and molecular structures of homo- and
heterometallic nickel(II) aminoalkoxides Ni(h2-ORN)2 and
Ni(Ni0.25Cu0.75)2(m3-OH)(m-OAc)(h1-OAc)2(m,h2-ORN)2(h2-RNOH)
(RN=CHMeCH2NMe2)
Pia Werndrup a, Suresh Gohil a, Vadim G. Kessler a,*, M. Kritikos b,
Liliane G. Hubert-Pfalzgraf c,*
a Department of Chemistry, Swedish Uni6ersity of Agricultural Sciences, P.O. Box 7015, 75007 Uppsala, Sweden
b Department of Structural Chemistry, Arrhenius Laboratory, 10691 Stockholm, Sweden
c Uni6ersite´ Claude Bernard Lyon I, IRC, 2 a6enue A. Einstein, 69626 Villeurbanne Cedex, France
Received 3 January 2001; accepted 23 April 2001
Abstract
Soluble Ni(II) alkoxides, namely the dimethylaminoisopropoxide clathrate with toluene, Ni(h2-ORN)2·C7H8 (I) and the solvent
free crystalline Ni(ORN)2 (RN=CHMeCH2NMe2) species (II), obtained by sublimation of I in vacuo, were characterized by X-ray
diffraction. The reaction between Ni(ORN)2 and copper carboxylates such as propionate and copper acetate hydrate in
hydrocarbons afforded [CuNi2(O2CEt)3(ORN)3(RNOH)] (III) and [Ni(Ni0.25Cu0.75)2(m3-OH)(m-OAc)(h1-OAc)2(m,h2-ORN)2(h2-
RNOH)] (IV), respectively. The structures of I and II are based on square planar molecules of the trans isomer. The structure of
IV corresponds to triangular aggregates with a M3(m3-OH) central core. The remarkable feature is the presence of three types of
coordination sphere, one metal is coordinated octahedrally and corresponds to nickel and the other two have square pyramidal
and square planar coordinations, respectively, and an electronic density corresponding to Cu (75%) and Ni (25%). The
monodentate behavior of the two acetato ligands is stabilized by intramolecular hydrogen bonding involving the hydroxyl
,
,
functionalities of the m3-hydroxo (2.776(9) A) and the solvated aminoalcohol ligand (2.573(6) A). Magnetic data in the 20–300 K
temperature range for III and IV account for three uncoupled metal centers at high temperature whereas ferromagnetic exchange
interactions are likely below 20 K. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Nickel; Copper; Functional alkoxides; Carboxylates; Sol–gel; Heteronuclear; X-ray structures
sition metals [5], such derivatives have been less studied
for late-transition metals due to the low solubility and/
or stability of classical alkoxide ligands [6]. Alkoxides
with donor sites or aryloxides are required generally for
overcoming these drawbacks [7].
Aminoalcohols generally show higher solubility than
alkoxyalcohols as shown by copper(II) complexes [8].
Soluble Ni(II) alkoxides remain scarce, the few exam-
ples being based on aryloxides [9] or on 2-dimethy-
laminoisopropoxide. The latter could be prepared by
different synthetic routes but its structural characteriza-
tion was hampered by stability problems of the single
crystals [10]. We report herein the molecular structures
of two forms of Ni(h2-OCHMeCH2NMe2)2, the toluene
clathrate I and the solvent free species II, as well as the
1. Introduction
Multicomponent oxides such as perovskites or spinels
based on transition metals like iron, manganese, nickel
or cobalt display a number of attractive properties [1,2].
Rare earth nickelates, LnNiO3, are attractive as elec-
trode materials but low temperature routes are desir-
able in view of their poor stability [3]. Ferroelectrics,
catalysts [4], optical or magnetic materials are some of
their other technological applications. While metal
alkoxides are the usual oxide precursors for early-tran-
* Corresponding authors. Tel.: +4-72-445322; fax: +4-72-445399.
E-mail address: hubert@catalyse.univ-lyon1.fr (L.G. Hubert-Pfalz-
graf).
0277-5387/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0277-5387(01)00814-2

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P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
investigation of the reactions of II with copper carboxy-
lates in non-polar media. Heterometallic CuꢀNi species
III and IV of 1:2 and 1:1 stoichiometry, respectively,
were obtained and the molecular structure of the latter
reported.
2.2. Ni(Ni0.25Cu0.75)2(v3-OH)(v-OAc)(p1-OAc)2-
(v,p2-ORN)2(p2-RNOH) (IV)
Solid Cu2(OAc)4(H2O)2 (0.412 g, 1.0 mmol) was
added to Ni(ORN)2 (1.092 g, 4.2 mmol) in 30 ml of a
toluene–MeOH (5:1) solution giving a dark blue
medium which became transparent in an hour, after the
precipitation of a gray blue compound containing only
nickel. The filtrate was evaporated to dryness and the
green blue residue was redissolved on heating in 10 ml
of THF and 5 ml of hexane. Turquoise crystals of IV
(70% yield with respect to copper acetate) were ob-
tained at 0°C overnight. The identity of the bulk with
the formula established by single-crystal X-ray study
was proved by microanalysis and by indexing the X-ray
powder patterns. Anal. Found: C, 36.65; H, 6.90; N,
6.0. Calc. for C21H47N3O10Ni1.5Cu1.5: C, 36.81; H, 6.90;
N, 6.13%. IR (cm−1): w(OH) 3400 (m br), 1716 (m),
1603 (s), 1567 (s), w(CO2) 1549 (sh), 1286 (w), 1255 (w),
1230 (w), 1135 (s), 1090 (s), 1072 (m), 1047 (w), 1025
(m), 1017 (s), 951 (s), 941 (m), 662 (s), 613 (m), 537 (m),
2. Experimental
All experiments were done routinely under nitrogen
using Schlenk tubes and vacuum line techniques. Com-
pound I was prepared as reported in Ref. [10]. Com-
pound II was obtained by the sublimation of I at
93–95°C under 10−2 mmHg. Cu2(OAc)4(H2O)2 was
purchased from Merck. Cu(O2CEt)2 was obtained from
Cu2(CO3)(OH)2 by dissolution in a propionic anhy-
dride–propionic acid (1:1) mixture, refluxing for 6 h
and subsequent removal of volatiles in vacuo at 60°C.
IR spectra were registered as Nujol mulls with a
Perkin–Elmer IR-1700 spectrometer. UV spectra were
recorded using a U-2001 spectrophotometer. Mass
spectra (electron beam ionization, direct probe intro-
duction) were recorded using a JEOL JMS-SX/SX-
102A spectrometer. The metal ratio in III and IV was
determined by energy dispersive analysis (EDS) (Arrhe-
nius Laboratory, Stockholm University, Sweden) on a
JEOL-820 scanning electron microscope, supplied with
Link AN-10000. Analytical data for I–IV were ob-
tained from Mikrokemi AB, Uppsala, Sweden, and the
Laboratory of Organic Microanalysis of Moscow State
University, Russia.
w(MꢀO) 500 (m). UV–Vis: u (nm) (m, M−1 cm−1
)
(toluene): 675 (600). MS; m/z (I%): 685 (1), 680 (1), 640
(2), 635 (2), 583 (1), 578 (1), 572 (2), 570 (1.5), 568 (1),
563 (3), 560 (3), 557 (4), 555 (3.5), 544 (1.5), 539 (1),
512 (3), 501 (4), 453 (2), 394 (3), 379 (5), 336 (7), 286
(3), 267 (3), 262 (18), 244 (16), 223 (10), 218 (9), 185
(20), 159 (22), 100 (8), 58 (100).
2.3. Crystallography of I, II and IV
Crystals of I and of II were chosen from the mother
liquor and from the sublimate, respectively, and
mounted into Lindeman capillaries. Data collection was
carried out with a SMART CCD Bruker diffractometer.
The rotation photographs taken with different exposure
times showed that the crystals of I melted and recrystal-
lized under the X-ray beam giving polycrystals. There-
fore a large (1.20×0.80×0.80 mm3) single crystal was
chosen for I and the data were collected with rather
short exposure time (1 s per frame). The unit cell
parameters and orientation matrix were determined
after the data collection using 1556 and 1493 reflections
with I]6|(I) for I and II, respectively. The data
collection for the air-stable crystals of IV was carried
out using a Siemens P3/PC diffractometer. The unit cell
parameters were determined using 48 randomly chosen
intense reflections. Basic crystallographic information is
shown in Table 1.
2.1. CuNi2(O2CEt)3(ORN)3(RNOH) (III)
Dissolution of Cu(O2CEt)2 (0.273 g, 1.3 mmol) in a
solution of Ni(ORN)2 (0.340 g, 1.3 mmol) in 15 ml of
toluene gave a turquoise solution. The latter was evapo-
rated and the residue redissolved in THF (2 ml) and
MeOH (0.5 ml) and left overnight at −30°C. A light
blue crystalline solid was collected by filtration (yield
:40% with respect to copper propionate). Anal.
Found: C, 41.25; H, 7.50; N, 6.50. Calc. for
C29H56N4O10CuNi2: C, 42.99; H, 7.96; N, 6.92%. IR
(cm−1): 3400 (m br), w(OH) 3240 (sh), 1712 (m), 1592
(s br), 1541 (m), w(CO2), 1297 (m), 1282 (w), 1262 (w),
1223 (w), 1134 (m), 1090 (s), 1050 (m), 1026 (m), 1014
(m), 942 (s), 881 (m), 869 (m), 841 (m), 810 (m br), 610
(m), w(MꢀO) 531 (m). UV–Vis: u (nm) (m, M−1 cm−1
)
The structures were solved by direct methods using
SHELXTL-NT programs [11]. The positions of all non-
hydrogen atoms were refined anisotropically by full-
matrix least-squares techniques. The hydrogen atoms
were included in the final refinement in calculated posi-
(toluene): 686 (900). MS; m/z (I%): 733 (1) (P), 689 (1),
631 (1.5), (P−Me), 600 (3), 570 (2), 529 (2), 422 (2),
393 (3), 368 (6), 364 (4), 272 (27), 262 (55), 223 (26), 199
(54), 159 (18), 58 (100).

P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
2165
tions with temperature factors Uiso=1.5Ueq(Ci), where
3. Results and discussion
Ci is the carbon atom to which the corresponding
hydrogen atom is bonded. Absorption corrections for I
and II were applied using SADABS. No absorption
correction was made for IV. The disorder in the occu-
pation of metal atom positions in IV could not be
resolved by free variation of occupation factors in view
of the very close electron density of Cu and Ni [and
thus the ability to diffract X-rays]. Therefore a com-
parison of different models proposed on the basis of
metal analysis was carried out (Table 2), the best
agreement with the experimental data was obtained for
a distribution of Cu and Ni (0.75Cu+0.25Ni) between
the positions M(1) and M(2).
3.1. Molecular structures of Ni(II) aminoalkoxides
Nickel(II) alkoxides based on the 1,2-dimethylamino-
2-propoxide ligand (ORN=OHCHMeCH2NMe2) were
prepared either by metathesis between NiCl2 or
[Ni(NH3)6]Cl2 and the sodium aminoalkoxide [10]. The
compounds were highly soluble in toluene and iso-
propanol. Mass spectrometry data displayed only
monomeric fragments whereas the UV–Vis spectrum in
toluene was comparable to that of [cis-NiCl2(h2-
ORN)2]. Previous attempts to get solid state structural
data were precluded by the lack of stability of the single
crystals.
2.4. Magnetic susceptibility measurements
Compound I isolated from toluene solution turned
out to be a clathrate with toluene, with one solvent
molecule per molecule of complex. The latter is a
monomeric trans isomer with four-coordinated nickel
atoms (Fig. 1, Table 3). The sum of the angles at nickel
is 359.98(13)° showing it to be almost ideally square
The ac magnetic susceptibility on polycrystalline
samples of III and IV were measured (500 Hz and 500
A m−1) in the temperature range 11–320 K using a
Lake Shore Inc. AC Susceptometer, Model 7130,
equipped with a helium cryostat. Corrections for dia-
magnetic contributions were made using Pascal’s con-
stants [12].
,
,
planar. The NiꢀO (1.829(3) A) and NiꢀN (1.931(3) A)
distances lie in the range usually observed for tetra-co-
Table 1
Crystallographic data for compounds I, II and IV
I
II
IV
Chemical formula
Formula weight
Temperature (K)
Crystal system
C
17H32N2O2Ni
C10H24N2O2Ni
263.02
295(2)
monoclinic
P21/c
C21H47N3O10Ni1.5Cu1.5
684.99
295(2)
monoclinic
P21/n
355.16
295(2)
monoclinic
C2
Space group
Unit cell dimensions
,
a (A)
14.969(4)
8.935(4)
8.531(3)
90
121.877(14)
90
968.9(6)
2
1.009
5.6041(16)
10.361(3)
11.559(3)
90
93.237(5)
90
670.0(3)
2
1.434
11.923(5)
16.716(6)
15.600(6)
90
102.32(3)
90
3037.7(19)
4
2.012
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Absorption coefficient v (mm−1
)
Independent reflections
Observed reflections
R1
1614 [Rint=0.0383]
1529 [I\2|(I)]
0.0457
1493 [Rint=0.0468]
1493 [I\2|(I)]
0.0503
7923 [Rint=0.0445]
3950 [I\4|(I)]
0.0662
wR2
0.1117
0.1132
0.1018
Table 2
Different refinement models for IV
Position M(1)
Position M(2)
R1 for 3950 reflections with I\4|(I)
wR2 for all 7885 reflections
Goodness-of-fit
1
2
3
4
5
Cu
Cu
Cu
0.0693
0.06920
0.0690
0.0697
0.0662
0.1464
0.1462
0.1461
0.1475
0.1018
1.077
1.074
1.073
1.083
1.054
0.5Cu+0.5Ni
Cu
Cu
0.5Cu+0.5Ni
Ni
0.75Cu+0.25Ni
0.75Cu+0.25Ni

2166
P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
angle (175.6(10)°), which can serve as an indication of a
slightly more covalent character of NiꢀN bonding in
comparison with NiꢀO, which is very common for
nickel [13]. The bite angles of the aminoalkoxide ligand
have values of 87.98(13) and 92.00(12)°. These values
are larger than those found for NiCl2(h2-
OHCHMeCH2NMe2)2 where nickel is six-coordinated.
The toluene molecules are disordered with two orienta-
tions of the CH3 groups [C(14) and C(14A)], they are
located among the layers of planar Ni(OR)2 molecules
(Fig. 2). This fact explains the easy recrystallization of
I under X-rays that made the determination of its
structure difficult.
Compound I is volatile. Its sublimation at 93–95°C
(0.01 mmHg) yielded brownish green crystals of II, the
volatiles being essentially toluene and the parent alco-
hol (1H NMR). The presence of the latter indicates that
sublimation proceeds with some decomposition. Partial
resublimation of II was achieved at 85°C/10−2 mmHg.
Thus, compound II appears more volatile but less
stable than the copper(II) analog Cu(ORN)2 [8]. Its
molecular structure is essentially the same as that of I
with similar metric parameters (Table 3). The absence
of toluene molecules in the lattice leads to both
N(1)ꢀNi(1)ꢀN(1%) and O(1)ꢀNi(1)ꢀO(1%) angles having
values of 180°.
Fig. 1. Molecular structure of I showing the atom-numbering scheme.
Table 3
,
Bond lengths (A) and bond angles (°) for I and II
Compound I
Bond lengths
Ni(1)ꢀO(1)
Ni(1)ꢀO(1%)
Ni(1)ꢀN(1)
Ni(1)ꢀN(1%)
1.829(3)
1.829(3)
1.931(3)
1.931(3)
Bond angles
O(1)ꢀNi(1)ꢀO(1%)
O(1)ꢀNi(1)ꢀN(1)
O(1%)ꢀNi(1)ꢀN(1)
O(1)ꢀNi(1)ꢀN(1%)
O(1%)ꢀNi(1)ꢀN(1%)
N(1)ꢀNi(1)ꢀN(1%)
C(5)ꢀO(1)ꢀNi(1)
175.6(10)
87.98(13)
92.00(12)
92.00(12)
87.98(13)
179.6(8)
3.2. Reactions between II and copper(II) carboxylates
Heteroleptic alkoxides of late transition metals such
as Cu and Ni attracted attention during the last decades
due to their unusual magnetic properties namely
ferromagnetism in [Ni(acac)(OMe)(MeOH)]4 [14,15]
and diamagnetism in [Cu4{(O2CMe)(2-C5H4N)2}4-
(OMe)2]2+ for instance [16]. NiꢀCu species of various
nuclearity have been reported, most of them being di-
or trinuclear [16b] but larger aggregates such as
112.9(3)
Compound II
Bond lengths
Ni(1)ꢀO(1)
Ni(1)ꢀO(1%)
Ni(1)ꢀN(1%)
Ni(1)ꢀN(1)
1.829(3)
1.829(3)
1.938(3)
1.938(3)
Bond angles
M6Cu2(m3-OH)4(mhp)2(OCPh)10(Hmhp)4(H2O)2
with
O(1)ꢀNi(1)ꢀO(1%)
O(1)ꢀNi(1)ꢀN(1%)
O(1%)ꢀNi(1)ꢀN(1%)
O(1)ꢀNi(1)ꢀN(1)
O(1%)ꢀNi(1)ꢀN(1)
N(1%)ꢀNi(1)ꢀN(1)
C(1)ꢀO(1)ꢀNi(1)
180.0(2)
91.72(13)
88.28(13)
88.28(13)
91.72(13)
180.0(2)
112.1(3)
Hmhp=6-methyl-2-pyridone and M=Ni have also
been obtained [17]. Reactions between metal alkoxides
and carboxylates have afforded a number of het-
erometallic aggregates of unusual structural features
[18]. We used this strategy to access NiꢀCu species.
The interaction of Ni(ORN)2 with anhydrous copper
propionate in 1:1 ratio afforded a crystalline product
III containing Cu and Ni in 1:2 ratio according to EDS
analysis (Cu, 37.1(7); Ni, 62.9(7)). Its composition was
supported further by analytical and mass spectral data.
The latter displayed the ions originating from the frag-
mentation of III, e.g. with m/z 733 [CuNi2(O2CEt)2-
(ORN)4]+, 689 ([CuNi2(O2CEt)3(ORN)3Me]+), 631
[CuNi2(O2CEt)2(ORN)3]+ and 500 [CuNi2(O2CEt)3-
(ORN)]+ along with some minor fragments characteris-
tic of homometallic species.
Symmetry transformations used to generate equivalent atoms: −x,
−y, −z.
ordinated nickel. They are shorter than the correspond-
ing distances in [Li(iPrOH)Ni(ORN)2Cl] (NiꢀO, 1.937(5)
,
and 2.017(5), and NiꢀN, 2.109(7) and 2.151(8) A) and
in Ni(ORN)2Cl2 (NiꢀO, 2.147(8) and 2.171(7), and
,
NiꢀN, 2.142(9) and 2.148(9) A), where the nickel atoms
are penta- and hexa-coordinated, respectively [10]. It is
to be noticed that the N(1)ꢀNi(1)ꢀN(1%) angle in I
(179.8(6)°) is closer to 180° than the O(1)ꢀNi(1)ꢀO(1%)
The reaction between Ni(ORN)2 and copper(II) ace-
tate hydrate in 2:1 ratio lead to the precipitation of 1

P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
2167
Fig. 2. Packing showing the toluene molecules among I.
equiv. of nickel (presumably as Ni(OH)2) whereas the
isolated crystalline product IV contained Cu and Ni in
a 1:1 ratio (Cu 53.2(7) and Ni 46.8(7) for EDS analy-
ses). The FT-IR spectra of compounds III and IV
displayed absorption bands characteristic of w(CO2)
vibrations in the 1700–1500 cm−1 region as well as
bands around 3400 cm−1 indicating the presence of
hydroxyl functionalities.
For III, the intensity of most of the fragments observed
is quite low. The salient structural feature is that each
metal has a different coordination geometry: octahedral
with no Jahn–Teller distortion for nickel, tetragonal
pyramidal or square planar for M(1) and M(2), respec-
tively. The square planar coordination geometry of the
M(2) center is distorted slightly, this is in good agree-
ment with the magnetic properties observed (Section
The X-ray single-crystal study of IV showed a trian-
gular framework uncommon for mixed-metal species
displaying a 1:1 stoichiometry (Fig. 3, Table 4). The
first of the three different positions appeared to be
occupied only by Ni atoms, while the other two turned
out to be occupied by Cu (75%) and by Ni (25%),
respectively (this gave the best result on both dis-
crepancy factors and goodness-of-fit, Table 2). It can be
explained chemically by the coexistence in the solid
state of molecules of different compositions, namely
[CuNi2(OH)(OAc)3(ORN)2(RNOH)] and [Cu2Ni(OH)-
(OAc)3(ORN)2(RNOH)], giving an overall 1:1 stoi-
chiometry between the metals. The isotopic fragmenta-
tion patterns for both species (parent ions P+,
[P−HNMe2]+, [P−RNOH]+, [P−RNOH−Me]+,
[P−RNOH−Me−NMe2]+) were observed in the
mass spectra along with those of homometallic species
suggesting that some gas phase chemistry occurs [19].
Fig. 3. Molecular structure of IV showing the atom-numbering
scheme. Dotted lines indicate hydrogen bonding.

2168
P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
Table 4
terminal monodentate ligands. Indeed the Ni(1)ꢀO(8)
and M(1)ꢀO(6) distances have values of 3.294(6) and
,
Selected bond distances (A) and bond angles (°) for IV
,
3.301(6) A, respectively, and O(8) and O(6) are thus
Bond lengths
definitely out of the metal coordination sphere. This
monodentate coordination behavior — quite scarce —
[20] is stabilized actually by intramolecular hydrogen
bonding with the hydroxide ligand (O(1)···O(6),
Ni(1)ꢀO(2)
Ni(1)ꢀO(3)
Ni(1)ꢀO(7)
Ni(1)ꢀO(1)
Ni(1)ꢀO(4)
Ni(1)ꢀN(3)
Ni(1)ꢀM(1)
Ni(1)ꢀM(2)
2.021(3)
2.053(3)
2.053(4)
2.125(4)
2.131(4)
2.145(4)
2.9098(15)
2.9773(12)
M(1)ꢀO(3)
M(1)ꢀO(1)
M(1)ꢀO(5)
M(1)ꢀN(1)
M(1)ꢀO(9)
M(2)ꢀO(2)
M(2)ꢀO(10)
M(2)ꢀO(1)
M(2)ꢀN(2)
1.933(3)
1.953(3)
1.957(4)
2.039(4)
2.304(4)
1.924(3)
1.954(4)
1.961(4)
2.050(5)
,
2.776(9) A) and the hydrogen atom of the solvated
,
alcohol molecule (O(4)···O(8), 2.573(6) A) [21]. The
metal–metal distances are rather short: Ni(1A)ꢀCu(1),
2.9098(15) and Ni(2A)ꢀCu(2), 2.9773(12) A. They are
,
shorter than those observed in [Cu3(m3-OH)L3A(H2O)x]
with L=3-acetylamino-1,2,4-triazolate; A=CF3SO3,
NO3, ClO4 and x=0, 2 [22]. The Ni···M distances are
also shorter than those observed for the Ni(II)
aminoalkoxide cluster [Ni7(m-NO2)8(m-OH)2(m3-OH)2-
(OHR’N)2(OR%N)2]·7H2O with OR%N=1,3-diamino-pro-
poxide=OCH(CH2NMe2)2 [23].
Bond angles
O(2)ꢀNi(1)ꢀO(3)
O(2)ꢀNi(1)ꢀO(7)
O(3)ꢀNi(1)ꢀO(7)
O(2)ꢀNi(1)ꢀO(1)
O(3)ꢀNi(1)ꢀO(1)
O(7)ꢀNi(1)ꢀO(1) 168.0(2)
O(2)ꢀNi(1)ꢀO(4) 168.7(2)
O(3)ꢀM(1)ꢀO(1)
O(3)ꢀM(1)ꢀO(5) 168.5(2)
O(1)ꢀM(1)ꢀO(5)
O(3)ꢀM(1)ꢀN(1)
92.92(14)
97.71(15)
94.03(15)
77.76(14)
75.23(13)
O(1)ꢀM(1)ꢀN(1) 165.6(2)
O(5)ꢀM(1)ꢀN(1)
O(3)ꢀM(1)ꢀO(9)
O(1)ꢀM(1)ꢀO(9)
O(5)ꢀM(1)ꢀO(9)
O(2)ꢀM(2)ꢀO(10) 171.9(2)
O(2)ꢀM(2)ꢀO(1)
O(10)ꢀM(2)ꢀO(1) 98.9(2)
O(2)ꢀM(2)ꢀN(2)
O(10)ꢀM(2)ꢀN(2) 89.6(2)
O(1)ꢀM(2)ꢀN(2) 160.1(2)
91.6(2)
96.0(2)
98.43(15)
95.4(2)
84.17(15)
82.05(15)
The formation of III and IV can be summarized by
the following equations:
85.2(2)
97.9(2)
86.5(2)
2Ni(ORN)2+2Cu(O2CEt3)2
M(1)ꢀO(1)ꢀM(2) 108.0(2)
“[CuNi2(O2CEt3)3(ORN)3(RNOH)]+···
4Ni(ORN)2+Cu2(OAc)4(H2O)2
(1)
M(1)ꢀO(1)ꢀNi(1)
M(2)ꢀO(1)ꢀNi(1)
M(2)ꢀO(2)ꢀNi(1)
M(1)ꢀO(3)ꢀNi(1)
90.94(14)
93.5(2)
97.96(15)
93.73(14)
“[CuNi2(OH)(OAc)3(ORN)2(RNOH)]
+[Cu2Ni(OH)(OAc)3(ORN)2(RNOH)]+···
(2)
The structure of IV accounts for a redistribution
reaction between the aminoalkoxide and the acetate
ligands. The overall formula of III and IV differ essen-
tially by the replacement of one aminoalkoxide ligand
by a hydroxo ligand. This observation is in agreement
with the higher hydrolytic susceptibility of an alkoxide
ligand with respect to a carboxylate one. The structure
of the nonhydroxo compound III for which no suitable
crystals could be obtained is related probably to that of
[Ba2Cu(m3,h2-ORN)2(m,h2-thd)2(thd)2(iPrOH)2] in which
the linkage between the divalent metals is ensured by
the aminoalkoxide ligand and bridging chelating te-
tramethylheptanedionate [24]. One can also notice the
stability of a hydroxo versus an oxo triangular core for
late-transition metals.
Fig. 4. Inverse molar susceptibility vs temperature for III (ꢀ) and IV
(ꢁ).
3.3). The metal–oxygen and metal–nitrogen distances
fall in the range usually observed for both Ni(II) and
Cu(II) aminoalkoxides with the variation MꢀORB
MOAcBM-m-OAcBMꢀN, the distances related to
nickel being longer than those observed for copper. The
NiꢀOR and NiꢀN distances are also longer than those
observed for the mononuclear complexes I and II due
to higher coordination numbers as well as the OR
ligands having bridging functions. The presence of a
M3OH core is confirmed by the pseudotetrahedral oxy-
gen environment, the detection of the hydrogen and by
stoichiometry. While one acetate ligand bridges the
M(1) and M(2) metallic centers, the other two act as
3.3. Magnetic susceptibility studies
Inverse molar susceptibility versus T plots (Fig. 4)
give C=2.76 emu K mol−1, [=6.00 K and C=2.15
emu K mol−1, [=11.7 K for III and IV, respectively.
The expected values of the Curie constants for com-
pletely uncoupled complexes are 2.375 and 2.062
emu K mol−1 for III and IV, respectively. These values
were obtained assuming that g=2.00 for both Cu(II)
and Ni(II) although the actual values are probably
higher [12]. However, this simple isotropic model shows
at least a qualitative agreement with the results ob-

P. Werndrup et al. / Polyhedron 20 (2001) 2163–2169
2169
References
[1] F.S. Gradasso, Structure, properties and preparation of per-
ovskite-type compounds, in: R. Smoluckowski, N. Kurt (Eds.),
International Series of Monographs in Solid State Physics, vol.
5, Pergamon, London, 1965.
[2] (a) A. Chatterjee, D. Das, S.K. Pradhan, D. Chakravorty, J.
Magn. Mater. 127 (1993) 214;
(b) H. Langbein, S. Fischer, Thermochim. Acta 182 (1991) 39.
[3] P. Lacorre, J. Solid State Chem. 91 (1991) 228.
[4] F. Meyer, R. Hempehmann, S. Mathur, M. Veith, J. Mater.
Chem. 9 (1999) 1755.
[5] L.G. Hubert-Pfalzgraf, in: B.I. Lee, E.I.A. Pope (Eds.), Chemical
Processing of Ceramics, Marcel Dekker, New York, 1994.
[6] D.C. Bradley, R.C. Mehrotra, D.P. Gaur, Metal Alkoxides,
Academic Press, London, 1978.
Fig. 5. Temperature dependence of the effective magnetic moment for
III (ꢀ) and IV (ꢁ).
[7] (a) L.G. Hubert-Pfalzgraf, Coord. Chem. Rev. 177–178 (1998)
967;
(b) L.G. Hubert-Pfalzgraf, H. Guillon, Appl. Organomet. Chem.
12 (1998) 231.
[8] S.C. Goel, K.S. Kramer, M.Y. Chiang, W.E. Buhro, Polyhedron
9 (1990) 611.
[9] H.F. Klein, A. Dal, T. Jung, S. Braun, C. Ro¨hr, U. Florke, H.J.
Haupt, Eur. J. Inorg. Chem. (1998) 621.
[10] L.G. Hubert-Pfalzgraf, V.G. Kessler, J. Vaissermann, Polyhe-
dron 16 (1997) 4197.
tained from the X-ray diffraction data. The tempera-
ture dependence of the effective magnetic moments
(veff) of III and IV is shown in Fig. 5. The data in the
high temperature regions are consistent with the pres-
ence of three uncoupled metal centers for both the
complexes. At temperatures below 20 K, the values of
veff are 5.6 and 5.2 BM for III and IV, respectively. The
continuous increase of veff with decreasing temperature
may originate from ferromagnetic exchange interac-
tions among the three metal centers. No attempts of
modeling the exchange couplings within the trimeric
clusters were made due to insufficient data in the low
temperature region.
[11] G. Sheldrick, SHELXTL-NT Reference Manual, Bruker AXS,
University of Go¨ttingen, 1998.
[12] E.A. Boudreaux, L.N. Mulay, Theory and Applications of
Molecular Paramagnetism, Wiley, New York, 1976.
[13] F. Basolo, R.G. Pearson, Mechanisms of Inorganic Reactions. A
Study of Metal Complexes in Solution, Wiley, New York, 1967.
[14] J.A. Bertrand, A.P. Ginsberg, R.I. Kaplan, C.E. Kirkwood, R.L.
Martin, R.C. Sherwood, Inorg. Chem. 10 (1971) 240.
[15] M. Halcrow, J.S. Sun, J.C. Huffman, G. Christou, Inorg. Chem.
34 (1995) 4167.
4. Supplementary material
[16] (a) V. Tangoulis, C.P. Raptopopoulu, S. Paschalidou, A.E.
Tsohos, Inorg. Chem. 36 (1997) 5270;
(b) R.E.P. Winpenny, Chem. Soc. Rev. 27 (1998) 447 (and
references therein).
[17] E.K. Brechin, S.G. Harris, S. Parsons, R.E.P. Winpenny, J.
Chem. Soc., Chem. Commun. (1996) 1439.
[18] K.G Caulton, L.G. Hubert-Pfalzgraf, Chem. Rev. 90 (1990) 963.
[19] J.B. Vincent, Inorg. Chem. 33 (1994) 5604.
[20] R.L. Rardin, W.B. Tolman, S.J. Lippard, New J. Chem. 15
(1991) 417.
[21] B.A. Vaartstra, J.C. Huffman, P.S. Gradeff, L.G. Hubert-Pfalz-
graf, J.C. Daran, S. Parraud, K. Yunlu, K.G Caulton, Inorg.
Chem. 29 (1990) 3126.
Crystallographic data for structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 149421, 149420, 149422 for I,
II and IV, respectively. Copies of this information may
be obtained free of charge from The Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
[22] S. Ferrer, J.G. Haasnoot, J. Reedijk, E. Muller, M.B. Cingi, M.
Lanfranchi, A.M. Manotti Lanfredi, J. Ribas, Inorg. Chem. 39
(2000) 1859.
.
Acknowledgements
[23] M.S. Elfallah, E. Rentschler, A. Caneschi, R. Sessoli, D. Gat-
teschi, Inorg. Chem. 35 (1996) 3723.
[24] F. Labrize, L.G. Hubert-Pfalzgraf, J. Vaissermann, C.B. Kno-
bler, Polyhedron 15 (1996) 577.
The authors are indebted to Dr A.I. Yanovsky
(Moscow) for the assistance in the solution of the
structure of compound IV.