Inorganic-organic hybrids of the p,p′-diphenylmethylenediphosphinate ligand with bivalent metals: A new 2D-layered phenylphosphinate zinc(II) complex

Article abstract of DOI:10.1016/j.jssc.2003.09.011

By reaction of Zn(CH₃COO)₂ with p,p′- diphenylmethylenediphosphinic acid in water a new inorganic-organic polymeric hybrid of formula [Zn(CH₂(P(Ph)O₂)₂)] has been synthesized and completely characterized. The X-ray analysis established that the structure consists of 2D-layered polymeric array, the 2D-sheets being built up through strong covalent linkages between the zinc metal and the oxygen donors of the phenylphosphinate ligand. The 2D-layers, which are featuring a mesh-net fashion, present voids of various dimensionality, up to 24-membered rings. The organic parts of the hybrid ligand, namely the phenyl rings, are shielding the inorganic skeleton of the layers, preventing the propagation of the polymer in the third dimension. No water molecules are present in the lattice, both of coordination and crystallization. Crystal data are: monoclinic, P2₁/c, a=11.840(2), b=9.646(9), c=12.516(5)A, β=95.03(2), V=1423.9(15)A³, Z=4. The solid material has been characterized by ³¹P MAS NMR spectroscopy and thermogravimetric analysis.

Full text of DOI:10.1016/j.jssc.2003.09.011

ARTICLE IN PRESS
Journal of Solid State Chemistry 177 (2004) 786–792
Inorganic–organic hybrids of the p,p0-diphenylmethylenediphosphinate
ligand with bivalent metals: a new 2D-layered
phenylphosphinate zinc(II) complex
Franco Cecconi,a Dainis Dakternieks,b Andrew Duthie,b Carlo A. Ghilardi,a Pedro Gili,c
Pablo A. Lorenzo-Luis,c Stefano Midollini,a and Annabella Orlandinia,Ã
a Istituto di Chimica dei Composti Organometallici, CNR, Polo Scientifico, Via Madonna del Piano, 50019 Sesto Fiorentino, Firenze, Italy
b Centre for Chiral and Molecular Technologies, Deakin University, Geelong, Victoria 3217, Australia
c Departamento de Quimica Inorganica, Facultad de Farmacia, Universidad de La Laguna, 38204-La Laguna, Tenerife, Canary Islands, Spain
Received 17 July 2003; accepted 17 September 2003
Abstract
By reaction of Zn(CH3COO)2 with p; p0-diphenylmethylenediphosphinic acid in water a new inorganic–organic polymeric hybrid
of formula [Zn(CH2(P(Ph)O2)2)] has been synthesized and completely characterized. The X-ray analysis established that the
structure consists of 2D-layered polymeric array, the 2D-sheets being built up through strong covalent linkages between the zinc
metal and the oxygen donors of the phenylphosphinate ligand. The 2D-layers, which are featuring a mesh-net fashion, present voids
of various dimensionality, up to 24-membered rings. The organicparts of the hybrid ligand, namely the phenyl rings, are shielding
the inorganicskeleton of the layers, preventing the propagation of the polymer in the third dimension. No water molecules are
present in the lattice, both of coordination and crystallization. Crystal data are: monoclinic, P21=c; a ¼ 11:840ð2Þ; b ¼ 9:646ð9Þ;
c ¼ 12:516ð5Þ A, b ¼ 95:03ð2Þ; V ¼ 1423:9ð15Þ A3, Z ¼ 4: The solid material has been characterized by 31P MAS NMR
spectroscopy and thermogravimetric analysis.
r 2003 Elsevier Inc. All rights reserved.
Keywords: Zinc; Phosphinate; Hybrid material; X-ray structure; Thermal analysis; MAS NMR
1. Introduction
constructed by single, double, triple or double-ribbon
bridges.
Among the inorganic–organic hybrid complexes the
metal phosphonates [1–8] and/or phosphinates [9–16]
represent a research field of great interest for their
potential capability to be used in diverse applications
(molecular sieves, selective catalysts, absorbers, ionic
exchangers, matrices for electric and magnetic devices).
In particular some metal monophosphinates, owing to
their aptitude to polymerization, were already known in
the past to be used in the coating and grease thickeners
industry [9].
Recently, we have reported an isomorphous series
of metal phosphinates complexes of formula
[M(pcp)(H2O)3] Á H2O, where M ¼ MnðIIÞ; Co(II),
Ni(II) and pcp is the bifunctional p; p0-diphenylmethy-
lenediphosphinate ligand, where the structure is ar-
ranged in the form of 2D-layers [17]. Interestingly in
such series the metals can be replaced by other metals
without changes of the primary structure. As a matter of
fact isomorphous mixed metal/pcp complexes have been
also obtained. The importance of the presence in the
lattice of water molecules, both of crystallization and
coordination, is well recognized, as the propagation of
the structures in 2D extended networks is just attribu-
table to strong hydrogen bonding interactions. The
cementing power of the H-bonding is exemplified also in
another pcp complex, reported recently by us, contain-
ing the beryllium metal [18]. The removal of the water
However, while the metal phosphonates are charac-
terized by a poly shaped structural typology as they are
suitable to form up to 3D arrays, the phosphinates
generally present polymericmonodimensional structures
ÃCorresponding author. Fax: +39-055-5225203.
E-mail address: annabella.bianchi@iccom.cnr.it (A. Orlandini).
0022-4596/$ - see front matter r 2003 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2003.09.011

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
787
molecules in such compounds appears of importance
2.3. Synthesis of [Zn(pcp)]
in the design of open coordination site moieties,
which is useful in the catalytic and intercalation
chemistry [19].
A solution of Zn(CH3COO)2 Á 2H2O (60 mg, 0.37 mmol)
in water (40 cm3) at 363 K was added to a solution of
H2pcp Á H2O (116 mg, 0.37 mmol) in 40 cm3 of the same
solvent at the same temperature. Standing of the
resulting solution at 363 K overnight afforded colorless
crystals of Zn(pcp). These were filtered, washed with
boiling water and dried in air. Yield ca. 83%. Anal.
Calcd. for C13H12O4P2Zn: C, 43.42; H, 3.36%. Found:
C, 43.46; H, 3.42%.
With the bifunctional ligand pcp we have now
succeeded in synthesizing two other hybrid polymers
of formula [M(pcp)], where M ¼ ZnðIIÞ and Pb(II),
characterized by the complete absence of water mole-
cules, both of crystallization or coordination. While the
Pb derivative presents a polymericoclumnar 1D
structure, whose description has been already published
[20], the Zn complex shows a bidimensional polymeric
array, characterized by 2D layers built by strong
covalent linkages.
2.4. X-ray structure determination
The complex has been characterized by X-ray
structure determination, 31P MAS NMR spectroscopy
and thermogravimetricanalysis.
Diffraction data for the zinc derivative were collected
at room temperature on an Enraf Nonius CAD4
automatic diffractometer. Unit cell parameters were
determined by least-squares refinement of the setting
angles of 25 carefully centered reflections. Crystal data
and data collection details are given in Table 1. The
intensities I were assigned the standard deviations sðIÞ
calculated by using a value of 0.03 for the instability
factor k [22]. They were corrected for Lorentz-polariza-
tion effects and an empirical absorption correction
(c scans) was applied [23]. Atomic scattering factors for
neutral atoms were taken from Ref. [24]. Both Df 0
and Df 00 components of anomalous dispersion were
included for all non-hydrogen atoms [25]. The structure
was solved by direct methods and refined by full-matrix
F2 refinement, with anisotropicthermal parameters
2. Experimental
2.1. Materials
All reagents were analytical grade commercial pro-
ducts and were used without further purification. The
p; p0-diphenylmethylenediphosphinicacid was prepared
as previously described [21]. The crude material was
recrystallized from 0.2 M solution of HCl to give
microcrystals of H2pcp Á H2O.
2.2. General physical methods
Table 1
Crystal data and structure refinement
Elemental analysis (C, H, N) were performed with an
EA 1108 CHNS-0 automaticanalyser. FT-IR spetcra
were recorded on a ThermoNicolet spectrometer (mod.
Avatar 360 FT/IR) and the samples were prepared as
KBr discs. Thermal analyses were carried out on a
PerkinElmer system (mod. Pyris Diamond TG/DTA)
Empirical formula
Formula weight
Temperature (K)
Wavelength
C13H12O4P2Zn
359.54
295(2)
0.71073 A
Monoclinic, P21=c
Crystal system, space group
Unit-cell dimensions
a (A)
under a nitrogen atmosphere (flow rate: 80 cm3 minÀ1
from 25ꢀC to 550ꢀC. The samples (ca. 4 mg) were heated
in an aluminum crucible (45 mL) at a rate of 10ꢀC minÀ1
)
11.840(2)
9.646(9)
b (A)
c (A)
12.516(5)
90
.
a (deg)
The TG curves were analyzed as percentage mass loss as
a function of temperature. The number of decomposi-
tion steps were identified using the derivative thermo-
gravimetric curve (DTG). The DTA curves were
analyzed as differential thermal analysis (DTðmVÞ).
The 31P and 207Pb MAS NMR spectra were measured
using a JEOL Eclipse Plus 400 spectrometer at 161.83
and 83.42 MHz, respectively, and are referenced against
aqueous H3PO4 (90%) and PbMe4 using crystalline
NH4H2PO4 (d 0.95) and Pb(p-Tol)4 (d À148:8) as
secondary references. At least two experiments with
sufficiently different spinning rates, ranging from 4 to
10 kHz, were recorded in order to determine the
isotropic chemical shift.
b (deg)
95.03(2)
90
g (deg)
Volume (A3)
1423.9(15)
4, 1.677
Z; Calculated density (g cmÀ3
Absorption coefficient (mmÀ1
F(000)
)
)
1.957
728
Crystal size (mm)
y range for data collection (deg)
Limiting indices
0.40 Â 0.38 Â 0.10
2.67–21.98
À12php12; 0pkp10; 0plp13
1834/1735 ½Rint ¼ 0:0352Š
Full-matrix least-squares on F2
1735/0/181
Reflections collected/unique
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
1.029
Final R indices ½I42sðIފ
R1 ¼ 0:0329; wR2 ¼ 0:0829
R1 ¼ 0:0446; wR2 ¼ 0:0880
0.415 and À0.475
R indices (all data)
Largest diff. peak and hole (e AÀ3
)

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
788
Table 2
Atomicocordinates ( Â 104) and equivalent isotropicdisplaecment
parameters (A2 Â 103)
x
y
z
Ueq
Zn(1)
P(1)
P(2)
10744(1)
8304(1)
8951(1)
9390(2)
8066(2)
10164(2)
8751(2)
8320(4)
7130(3)
7301(4)
6385(4)
5307(5)
5124(4)
6030(4)
8227(3)
7102(4)
6529(5)
7085(6)
8173(5)
8758(4)
4864(1)
4766(1)
7011(1)
4082(3)
4754(3)
6547(3)
8549(3)
6556(4)
3979(4)
3067(4)
2544(6)
2945(6)
3858(6)
4376(5)
6148(4)
6457(5)
5802(7)
4837(6)
4536(6)
5165(5)
3444(1)
29(1)
29(1)
31(1)
33(1)
35(1)
35(1)
38(1)
32(1)
33(1)
43(1)
60(1)
70(2)
66(2)
48(1)
35(1)
51(1)
68(2)
70(2)
65(2)
48(1)
4280(1)
2657(1)
4031(2)
5446(2)
2762(2)
2543(2)
3864(3)
3517(3)
2696(3)
2064(4)
2239(5)
3041(5)
3682(4)
1534(3)
1231(4)
363(4)
O(1)
O(2)
O(3)
O(4)
C(1)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
Fig. 1. Perspective view of a portion of the polymer [Pb(pcp)], showing
the coordination environment of the lead atom. ORTEP-III drawing
with 30% probability ellipsoids.
À217(4)
70(4)
945(4)
Ueq is defined as one-third of the trace of the orthogonalized Uij
tensor.
assigned to all non-hydrogen atoms. The hydrogen
atoms were introduced in their calculated positions
riding on their carbon atoms, with thermal parameters
20% larger than those of the respective carbon atoms.
Fig. 2. Perspective view of some symmetry related units of [Pb(pcp)]
showing the propagation of the 1D polymer along the b-axis.
The function minimized during the refinement was
P
2
2
wðFo2 À Fc2Þ ; with w ¼ 1=½s2ðFo2Þ þ ð0:0593PÞ þ
0:59PŠðP ¼ ðmaxðFo2; 0Þ þ 2Fc2Þ=3Þ: All the calculations
were performed on a Pentium processor, using the
package WINGX [26] (SIR97 [27], SHELX97 [28],
ORTEP-III [29]). Table 2 reports final refined atomic
parameters. Crystallographicdata have been deposited
with the Cambridge CrystallographicData Centre as
supplementary publication No. CCDC 220333.
pyramidal geometry, with an evident localization of the
Pb(II) lone pair in the void left free by such hemileptic
coordination. Conversely in the Zn(II) complex, the
metal is surrounded by four oxygen atoms from three
pcp ligand, in an homoleptic tetrahedral coordination.
Starting from these units the building up of the extended
networks differently proceeds in the two hybrids. While
the structure of the lead(II) complex is constituted by a
polymeric1D columnar array (see Fig. 2), the column
being formed by two intersecting sinusoidal ribbons
of Pb atoms, bridged by the phosphinate ligand,
the molecular structure of the Zn hybrid consists of
2D-layered [Zn(pcp)] polymers.
Fig. 3 shows the asymmetricunit of the zincpolymer,
doubled through the center of symmetry to illustrate the
complete connectivity to the metal. Selected bond
distances and angles of the compound are reported in
Table 3.
Each zinc metal is tetrahedrally coordinated by four
phosphinate oxygen donors from three pcp ligands (one
of them in a bidentate and the others in a monodentate
fashion), the pcp ligand using all of its oxygen atoms.
Each ZnO4 tetrahedron is linked to other ZnO4 moieties
through bridging phosphinate groups, so that a complex
3. Results and discussion
The complex, which is synthesized in water solution,
is insoluble both in water and in organicsolvents.
In the polymerichybrids [ M(pcp)] with M ¼ ZnðIIÞ
and Pb(II), unlike the hybrids of the isomorphous
hydrated [M(pcp)(H2O)3] Á H2O (M ¼ Ni; Co, Mn)
series [17], there are no water molecules in the sphere
of coordination nor interspersed in the lattice. The Zn
and Pb structures differ dramatically, with the different
spheres of coordination of the two metals playing an
important role in conditioning the building of the
polymericarrangement. In the Pb derivative, whose
structure has been already described in a previous
communication [20] (see Fig. 1), the metal is surrounded
by five oxygen atoms from four pcp ligands in a square

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
789
Fig. 3. Perspective view of a portion of the polymer [Zn(pcp)],
showing the labeling of the asymmetricunit. ORTEP-III drawing with
30% probability ellipsoids.
Table 3
Selected bond lengths (A) and angles(deg)
Zn(1)–O(4)x1
Zn(1)–O(2)x2
Zn(1)–O(3)
Zn(1)–O(1)
P(1)–O(1)
1.903(3) P(1)–C(11)
1.926(3) P(1)–C(1)
1.932(3) P(2)–O(3)
1.971(3) P(2)–O(4)
1.502(3) P(2)–C(21)
1.510(3) P(2)–C(1)
1.785(4)
1.805(4)
1.499(3)
1.507(3)
1.787(4)
1.798(4)
P(1)–O(2)
O(4)x1–Zn(1)–O(2)x2 110.12(13) O(3)–P(2)–O(4)
116.34(17)
108.65(18)
108.93(19)
108.58(18)
104.25(17)
109.93(19)
130.38(17)
O(4)x1–Zn(1)–O(3)
O(2)x2–Zn(1)–O(3)
O(4)x1–Zn(1)–O(1)
O(2)x2–Zn(1)–O(1)
O(3)–Zn(1)–O(1)
O(1)–P(1)–O(2)
113.18(12) O(3)–P(2)–C(21)
111.54(12) O(4)–P(2)–C(21)
107.40(12) O(3)–P(2)–C(1)
111.78(11) O(4)–P(2)–C(1)
102.57(12) C(21)–P(2)–C(1)
115.59(16) P(1)–O(1)–Zn(1)
Fig. 4. Perspective view of a portion of the [Zn(pcp)] polymer showing
the 24-membered ring. View normal to [100]. The phenyl rings are
omitted for sake of clarity. The unlabeled atoms linked to zinc
represent oxygens.
O(1)–P(1)–C(11)
O(2)–P(1)–C(11)
O(1)–P(1)–C(1)
110.08(18) P(1)–O(2)–Zn(1)x2 120.64(17)
108.16(18) P(2)–O(3)–Zn(1) 126.20(16)
109.26(17) P(2)–O(4)–Zn(1)x3 131.42(17)
sake of clarity. Although the voids could appear large
enough to be useful in intercalation chemistry, the
phenyl rings project toward the pores and therefore, as it
is evident from the packing diagram in which phenyls
are included (Fig. 6), reduce the size of the voids. A
schematic packing of the polymer with view down the y
axis is represented in Fig. 7. It is evident that
interruption of the structure in the third dimension is
caused by shielding from hydrophobic region of the
ligand (phenyl rings) on the inorganicpart of the hybrid
polymer.
In regard to the coordination of the zinc(II) metal, a
little distortion from the limit tetrahedral geometry is
represented by the spread of the O–Zn–O angles
between 102.57(12)ꢀ and 113.18(12)ꢀ. The Zn–O bond
distances from 1.903(3) to 1.971(3) A appear compar-
able with analogous linkages, in other Zn/phosphonates
reported [30]. Concerning the pcp ligand, bond distances
and angles exhibit expected values; in particular the P–O
bonds appear all very similar, in agreement with the
nature of the linkages displayed.
O(2)–P(1)–C(1)
C(11)–P(1)–C(1)
107.05(17) P(2)–C(1)–P(1)
106.28(19)
119.5(2)
Symmetry transformations used to generate equivalent atoms:
x1 À x þ 2; y À 1=2; Àz þ 1=2; x2 Àx þ 2; Ày þ 1; Àz þ 1; x3 Àx þ
2; y þ 1=2; Àz þ 1=2:
2D layered network results. The sheet, which is
characterized by a mesh-net array, shows various voids
of various dimensions. Besides the six-membered rings
formed upon the chelation of the pcp ligand to the Zn
center (O–P–C–P–O–Zn), there are voids created by
eight- and 24-membered rings. The eight-membered
rings, with a pseudo-chair conformation, are created by
two zincatoms and two phosphinate groups in an
alternating array. The connectivity of the six- and eight-
membered rings is depicted in Fig. 3.
From the linkage of four of the subunits represented
in Fig. 3, a 24-membered moiety is created, whose
connectivity is shown in Fig. 4. The phosphinate
oxygens connect the zinc atoms so that six zinc atoms
are alternated with six phosphinate groups O–P–O. The
propagation of this portion of the polymer in the yz
plane gives a bidimensional sheet, featuring a mesh-net.
Fig. 5 shows the packing diagram of [Zn(pcp)] as viewed
down the x axis, with exclusion of the phenyl rings for
In summary, while several structures of zinc/phos-
phonates hybrid complexes are known, very few zinc/
phosphinates have been reported [16,31–34] and are
generally characterized by monodimensional polymeric
chains with single, double or triple phosphinate bridges.

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
790
Fig. 5. Perspective view of a portion of the [Zn(pcp)] polymer showing the propagation of the layer in the yz plane. Phenyl rings are omitted for sake
of clarity.
Fig. 6. Packing diagram of [Zn(pcp)] with view normal to [100].

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
791
Fig. 7. Packing diagram of [Zn(pcp)] with view normal to [010].
Fig. 8. 31P MAS NMR spectra (161.83 MHz) of [Zn(pcp)] and [Pb(pcp)] at spinning speeds of 6.0 and 9.6 kHz, respectively.
MAS NMR spectra and TG-DTG/DTA analyses of
the [Zn(pcp)] complex and of the related [Pb(pcp)]
derivative were performed for comparison purposes.
The 31P MAS NMR spectra of both compounds are
shown in Fig. 8. The presence of two phosphorus signals
at 24.5 and 31.4 ppm in the spectrum of Pb complex
indicates that the two phosphorus atoms of the ligand
are inequivalent, as actually found in the X-ray results.
Analogously in the spectrum of the Zn derivative there
are two main signals (80–90%) at 25.9 and 35.5 ppm,
attributable to the inequivalent phosphorus atoms.
However, other minor resonances overlapping the
principal ones show the presence at least of another
polymorphicform of [Zn(ppc)]. The formation of
polymorphicphases has been previously observed in
Zn/phosphonate polymers [33]. As we have found a
resonance at 32.8 ppm in the 31P MAS NMR of solid
H2pcp (vs. 28.0 ppm in DMSO solution), there is not
much variation in the position of the 31P MAS NMR
signal for H2pcp, [Zn(pcp] and [Pb(pcp)] compounds.
The difference between the chemical shifts of H2pcp in
solution and in the solid state may be ascribed to the
presence of hydrogen bonds in the solid state.
The 207Pb MAS NMR spectrum of [Pb(pcp)] shows
an extremal broad signal at À2675 ppm (W1=2
¼
5000 Hz). The value of the chemical shift appears to be
consistent with the values reported for other lead
containing compounds, as the donor oxygen atoms of
pcp are remarkable electronegative [35,36].
The [Zn(pcp)] and [Pb(pcp)] compounds show a very
similar thermogravimetricbehavior. The TG-DTG/
DTA curves for both compounds reveal no presence

ARTICLE IN PRESS
F. Cecconi et al. / Journal of Solid State Chemistry 177 (2004) 786–792
792
Table 4
Thermal data of decomposition processes for [Zn(pcp)] 1 and [Pb(pcp)] 2
First and second steps
Complex
Temp.
range (ꢀC)
Temp. of the
DTG peak (ꢀC)
Loss of
wt% found
Temp. of endothermic
peak (ꢀC)
Temp. of exothermic
peak (ꢀC)
1
2
25–434
25–411
—
—
—
—
—
—
—
—
Temp. of exothermicpeak ( ꢀC)
1
2
434–550
411–550
488
439
29.41%
33.0%
476 and 494
449, 488 and 507
of endothermicor exothermicpeaks up to 411–434 ꢀC,
indicating the absence of water molecules, both of
crystallization and coordination (see Figs. 9 and 10 in
Supplementary Material). At higher temperatures pyr-
olisis of the organic part of the complexes takes place,
with changing of the color to black. Thermal data of the
decomposition processes for both compounds are
reported in Table 4. A comparison of the IR spectra
before and after the combustion, evidences the presence
of a new band at 1650 cmÀ1, whereas other bands
disappear in the regions 3050–3060 [aromatic n(C–H)],
1150 [n(P–C)], 1430–1440 [phenyl n(CQC)] cmÀ1, prob-
ably due to oxidation of the remaining organicmatter
[37,38]. The band at 1650 cmÀ1 may be due to an
overtone or combination band of the CPO3 stretching
vibrations or due to the bending vibration of the PO–H–
OP group, which interacts strongly by H-bonding [39].
The analysis of this material shows the presence of
carbon (ca. 12%) and hydrogen (ca. 1.8%), probably
due to an incomplete combustion in our conditions.
[14] K.W. Oliver, S.J. Rettig, R.C. Thomson, J. Trotter, S. Xuia,
Inorg. Chem. 36 (1997) 2465.
[15] D. Grohol, F. Gingl, A. Clearfield, Inorg. Chem. 38 (1999) 751.
[16] M. Shieh, K.J. Martin, P.J. Squattrito, A. Clearfield, Inorg.
Chem. 29 (1990) 958.
[17] E. Berti, F. Cecconi, C.A. Ghilardi, S. Midollini, A. Orlandini, E.
Pitzalis, Inorg. Chem. Commun. 3 (2002) 1041.
[18] F. Cecconi, S. Dominguez, N. Masciocchi, S. Midollini, A. Sironi,
A. Vacca, Inorg. Chem. 42 (2003) 2350.
[19] G. Cao, T.E. Mallouk, Inorg. Chem. 30 (1991) 1434.
[20] F. Cecconi, C.A. Ghilardi, S. Midollini, A. Orlandini, Inorg.
Chem. Commun. 6 (2003) 546.
[21] M.E. Garst, Synth. Commun. 9 (1979) 261.
[22] P.W.R. Corfield, R.J. Doedens, J.A. Ibers, Inorg. Chem. 6 (1967)
197.
[23] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr.
A 24 (1968) 351.
[24] A.J.C. Wilson, International Tables for X-ray Crystallography,
Vol. C, Kluwer Academic Publishers, Dordrecht, 1992,
p. 500.
[25] A.J.C. Wilson, International Tables for X-ray Crystallography,
Vol. C, Kluwer Academic Publishers, Dordrecht, 1992, p. 219.
[26] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 876.
[27] A. Altomare, M.C. Burla, M. Camalli, G.L. Cascarano, C.
Giacovazzo, A. Guagliardi, A.G.C. Moliterni, G. Polidori,
G.R. Spagna, J. Appl. Crystallogr. 32 (1999) 115.
[28] G.M. Sheldrick, SHELX97, University of Gottingen, Gottingen,
Germany, 1997.
References
[29] M.N. Burnett, C.K. Johnson, ORTEP-III, Oak Ridge National
Laboratory, Oak Ridge, TN, 1996.
[1] A. Clearfield, in: K.D. Karlin (Ed.), Progress in Inorganic
Chemistry, Vol. 47, Wiley, New York, 1998, p. 371.
[2] A. Cabeza, M.A.G. Aranda, S. Bruque, J. Mater. Chem. 8 (1998)
2479.
[30] D.M. Poojary, B. Zhang, A. Clearfield, Chem. Mater. 11 (1999)
421.
[31] V. Giancotti, F. Giordano, L. Randaccio, A. Ripamonti,
J. Chem. Soc. A (1968) 757.
[3] C.V.K. Sharma, A. Clearfield, A. Cabeza, M.A.G. Aranda,
S. Bruque, J. Am. Chem. Soc. 125 (2001) 2885.
[32] F. Giordano, L. Randaccio, A. Ripamonti, Acta Crystallogr.
Sect. B 25 (1969) 1057.
[4] A. Cabeza, X. Ouyang, C.V.K. Sharma, M.A.G. Aranda,
S. Bruque, A. Clearfield, Inorg. Chem. 41 (2002) 2325.
[5] S. Ayyappan, G. Diaz de Delgado, A.K. Cheetman, G. Ferey,
C.N.R. Rao, J. Chem. Soc. Dalton Trans. (1999) 2905.
[6] R. LaDuca, D. Rose, J.R.D. Debord, R.H. Haushalter, C.J.
O’Connor, C.J. Zubieta, J. Solid State Chem. 123 (1996) 408.
[7] J.-G. Mao, Z. Wang, A. Clearfield, Inorg. Chem. 41 (2002) 6106.
[8] J.-G. Mao, A. Clearfield, Inorg. Chem. 4 (2002) 2319 (and
references therein).
[33] R. Cini, P.L. Orioli, M. Sabat, H.D. Gillman, Inorg. Chim. Acta
59 (1982) 225.
[34] E. Cole, R.C.B. Copley, J.A.K. Howard, D. Parker, G. Ferguson,
J.F. Gallagher, B. Kaitner, A. Harrison, L. Royle, J. Chem. Soc.
Dalton Trans. (1994) 1619.
[35] F. Fayon, I. Farnan, C. Bessada, J. Coutures, D. Massiot,
J.P. Coutures, J. Am. Chem. Soc119 (1997) 6837.
[36] G.D. Fallon, L. Spiccia, B.O. West, Q. Zhang, Polyhedron
16 (1997) 19.
[9] B.P. Block, Inorg. Macromol. Rev. 1 (1970) 115.
[10] P. Colamarino, P.L. Orioli, W.D. Benzinger, H.D. Gillman,
Inorg. Chem. 15 (1976) 800.
[37] F. Cecconi, C.A. Ghilardi, P. Gili, S. Midollini, P.A. Lorenzo-
Luis, A.D. Lozano-Gorrın, A. Orlandini, Inorg. Chim. Acta 319
(2001) 67.
[11] R. Cini, P. Colamarino, P.L. Orioli, L.S. Smith, P.R. Newman,
H.D. Gillman, P. Nannelli, Inorg. Chem. 16 (1977) 3223.
[12] S.-J. Lin, R.J. Staples, J.P. Fackler Jr., Polyhedron 11 (1992) 2427.
[13] V. Chandrasekhar, A. Chandrasekaran, R.O. Day, J.M. Holmes,
R.R. Holmes, Phosphorus Sulfur Silicon Relat. Elem. 115 (1996)
125.
[38] G.B. Hix, S.J. Kitchin, K.D.M. Harris, J. Chem. Soc. Dalton
Trans. (1998) 2315.
[39] A. Cabeza, M.A.G. Aranda, S. Bruque, J. Mater. Chem. 9 (1999)
571.