Hydrothermal synthesis, characterization and crystal structures of two new zinc(II) phosphonates: Zn2[(O3PCH2)2NHCH2CO 2] and Zn2[HO3PCH2NH(CH2PO3) 2]

Article abstract of DOI:10.1039/b202096n

The hydrothermal reaction of zinc(II) acetate with N,N-bis(phosphonomethyl)aminoacetic acid [(H₂O₃PCH₂)₂NCH₂CO ₂H, H₅L¹] and nitrilotris(methylenephosphonic acid) [N(CH₂PO₃H₂)₃, H₆L²] at 180°C afforded two new zinc coordination polymers with a similar 3D network structure. Zn₂[(O₃PCH₂)₂NHCH₂CO ₂] (complex 1) is hexagonal, P6₁, with a = 8.0677(12), c = 27.283(6) A, u = 1537.9(5) A³, Z = 6. In complex 1, the Zn(II) atoms are tetrahedrally coordinated by three phosphonate oxygen atoms and one carboxylate oxygen atom from four ligands. The ZnO₄ tetrahedra are further interconnected through bridging phosphonate and carboxylate groups into a three dimensional network. Zn₂[HO₃PCH₂NH(CH₂PO₃) ₂] (complex 2) is also hexagonal, P6₁ with a = 8.3553(8), c = 26.657(4) A, u = 1611.6(3) A³, Z = 6. The structure of complex 2 features a 3D network built from ZnO₄ tetrahedra linked together by bridging phosphonate groups. One zinc and three phosphonate oxygen atoms are disordered. The two zinc atoms in the asymmetric unit are tetrahedrally coordinated by four phosphonate oxygen atoms of four ligands. Each ligand connects with eight zinc atoms. The effect of the extent of deprotonation of phosphonic acids and substitution groups on the type of complexes formed are discussed.

Full text of DOI:10.1039/b202096n

View Article Online / Journal Homepage / Table of Contents for this issue
Hydrothermal synthesis, characterization and crystal structures
of two new zinc(II) phosphonates: Zn [(O PCH ) NHCH CO ]
and Zn [HO PCH NH(CH PO ) ]
2
3
2 2
2
2
2
3
2
2
3 2
Jiang-Gao Mao, Zhike Wang and Abraham Clearfield*
Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station,
TX, 77843-3255, USA. E-mail: clearfield@mail.chem.tamu.edu
Received (in New Haven, CT, USA) 20th February 2002, Accepted 24th March 2002
First published as an Advance Article on the web
The hydrothermal reaction of zinc(II) acetate with N,N-bis(phosphonomethyl)aminoacetic acid
1
2
ꢀ
[
(H
2
O
3
PCH
2
)
2
NCH
2
CO
2
H, H
5
L ] and nitrilotris(methylenephosphonic acid) [N(CH
2
PO
[(O
3
H
2
)
3
, H
PCH
complex 1) is hexagonal, P6 , with a ¼ 8.0677(12), c ¼ 27.283(6) A, u ¼ 1537.9(5) A , Z ¼ 6. In complex 1, the
6
L ] at 180 C
afforded two new zinc coordination polymers with a similar 3D network structure. Zn
(
Zn(II) atoms are tetrahedrally coordinated by three phosphonate oxygen atoms and one carboxylate oxygen
atom from four ligands. The ZnO tetrahedra are further interconnected through bridging phosphonate and
carboxylate groups into a three dimensional network. Zn [HO PCH NH(CH PO ] (complex 2) is also
hexagonal, P6 with a ¼ 8.3553(8), c ¼ 26.657(4) A, u ¼ 1611.6(3) A , Z ¼ 6. The structure of complex 2 features
2
3
2
)
2
NHCH CO ]
2
2
+
+
3
1
4
2
3
2
2
3 2
)
+
+
3
1
4
a 3D network built from ZnO tetrahedra linked together by bridging phosphonate groups. One zinc and three
phosphonate oxygen atoms are disordered. The two zinc atoms in the asymmetric unit are tetrahedrally
coordinated by four phosphonate oxygen atoms of four ligands. Each ligand connects with eight zinc atoms.
The effect of the extent of deprotonation of phosphonic acids and substitution groups on the type of complexes
formed are discussed.
Metal phosphonate chemistry has been an area of interest to
both inorganic and materials chemists in recent years due to
potential applications in the areas of catalysis, ion exchange,
proton conductivity, intercalation chemistry, photochemistry,
Few studies have been done on metal complexed with N,N-
bis(phosphonomethyl)aminoacetic acid [(H PCH NCH
PMIDA in that
PMIDA has been replaced by a
2
O
3
2
)
2
2
1
CO
2 5 4
H, H L ], which differs slightly from H
one acetate group in H
4
1
and materials chemistry. Most of the compounds studied are
phosphonate group. X-Ray structural analysis of its plati-
num(II) complexes indicated that the ligand forms a 5-member
chelate ring with Pt(II) ion by using the amine group and the
layered species in which the metal octahedra are bridged by
phosphonate tetrahedra to form two-dimensional layers that
are separated by the hydrophobic regions of the organic
9
acetate group, the phosphonate groups remain uncoordinated.
Many studies have been carried out in our laboratory on
1
moieties. Studies from our group and from others have shown
that a variety of metal ions, including group 4 and 14 elements
and divalent and trivalent ions, form this type of layered
2
L ],
nitrilotris(methylenephosphonic acid) [N(CH
in which both acetate groups of H
2
PO
3
H
2
)
3
, H
PMIDA have been
6
4
1
–3
compound.
Research on metal complexes with phosphonic acids attached
with aza-crown ethers show those compounds have many
substituted by phosphonate groups. The structures of nitrilo-
tirs(methylenephosphonic acid) with amines such as 1,7-phe-
nanthroline, 1,10-phenanthroline, acridine and tripropylamine
in a 1 : 1 ratio feature a hydrogen bonded 3D hexagonal
1
,4
unusual structural features.
tional carboxylate groups, such as N-(phosphonomethyl)
Phosphonic acids with func-
1
0
network. For its metal(II) phosphonate complexes, two dif-
ferent types of 1 : 1 (M:L) complexes have been isolated by
using various metal–ligand ratios in the synthesis, namely,
M[NH(CH PO H) (H O) ] (M ¼ Mn, Co, Ni, Zn, Cu, Cd)
iminodiacetic acid (H PMIDA) are also interesting, since
4
they can adopt various kinds of coordination modes under
different reaction conditions. A mixed phosphate-phosphonate
layered zirconium compound was made by reaction of a zir-
2
3
3
2
3
1
1
whose structure features a hydrogen bonded 2D layer, and
the dehydrated Mn[NH(CH PO H) ] whose structure is a 3D
conium salt with a mixture of phosphoric acid and H PMIDA
4
2
3
3
5
solutions. When the above reactions were carried out in the
absence of phosphoric acid, a linear chain compound was
12
network. The metal ion in the hydrated complexes is octahed-
rally coordinated by three aqua ligands and three phosphonate
oxygen atoms, whereas Mn(II) ion in the non-hydrated com-
plex is five coordinated by five phosphonate oxygen atoms
6
isolated. In both cases the iminodiacetic moieties are only
involved in hydrogen bonding. Under less acidic conditions,
O)
1
2
we isolated two novel complexes, [Co
2
(PMIDA)(H
2
5
]ꢁH
2
O
with a distorted square pyramid geometry. Hydrothermal
reaction of zinc(II) acetate with N,N-bis(phosphonomethyl)
whose structure contains double layers of Co(II) carboxylate
interconnected by layers of Co(II) phosphonate, and a zinc car-
boxylate-phosphonate hybrid layered complex, [Zn (PMIDA)
1
L ] and nitrilo-
aminoacetic acid [(H
2
O
3
PCH
2
)
2
NCH
2
CO
2
H,H
tris(methylenephosphonic acid) in a 2 : 1 (M:L) molar ratio at
5
2
7
ꢀ
(
CH
3
CO
2
H)]ꢁ2H
2
O. With the complete depronation by
8
180 C afforded two new zinc coordination polymers with a
similar 3D network framework, namely, Zn [(O PCH ) NH
adding potassium hydroxide, Wood and his co-workers
obtained the canted antiferromagnet [K Co(PMIDA)] O,
2
3
2 2
2
6
ꢁxH
2
CH
2
CO
2
] (complex 1) and Zn
2
[HO
3
PCH
2
NH(CH
(complex 2). Herein we report their synthesis, characterization
2
3 2
PO ) ]
whose crystal structure features a hexameric ring in the chair
conformation.
and crystal structures.
1
010
New J. Chem., 2002, 26, 1010–1014
DOI: 10.1039/b202096n
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2002

View Article Online
+
ꢀ
Table 1 Bond lengths (A) and angles ( ) for complexes 1 and 2
Results
Complex 1
Crystal structure of Zn [O CCH NH(CH PO ) ], 1
2
2
2
2
3 2
Zn(1)–O(4)#1
Zn(1)–O(3)#3
Zn(2)–O(2)#4
Zn(2)–O(6)#6
P(1)–O(1)
P(1)–O(3)
P(2)–O(5)
O(4)#1–Zn(1)–O(1)#2 106.0(3)
O(1)#2–Zn(1)–O(3)#3 105.2(3)
1.909(6) Zn(1)–O(1)#2
1.937(6) Zn(1)–O(8)
1.922(6) Zn(2)–O(5)#5
1.937(6) Zn(2)–O(7)
1.495(7) P(1)–O(2)
1.528(7) P(2)–O(6)
1.511(6) P(2)–O(4)
1.922(7)
1.992(7)
1.936(6)
1.988(6)
1.515(6)
1.503(7)
1.530(7)
An ORTEP representation of the asymmetric unit of complex
is shown in Fig. 1. There are two zinc atoms in an asym-
1
metric unit. Both Zn1 and Zn2 atoms are tetrahedrally coor-
dinated by three phosphonate oxygen atoms and one
carboxylate oxygen atom from four different ligands. The
Zn–O(carboxylate) distances [1.992(7) and 1.988(6) A, res-
pectively, for Zn1 and Zn2] are slightly longer than the Zn–O-
+
O(4)#1–Zn(1)–O(3)#3 122.9(3)
O(4)#1–Zn(1)–O(8)
O(3)#3–Zn(1)–O(8)
O(2)#4–Zn(2)–O(6)#6 111.5(3)
103.1(3)
109.5(3)
O(1)#2–Zn(1)–O(8)
O(2)#4–Zn(2)–O(5)#5 98.2(3)
O(5)#5–Zn(2)–O(6)#6 115.2(3)
109.9(3)
+
(
(
phosphonate) bonds, which range from 1.909(6) to 1.937(6) A
Table 1). Each ligand is connected with 8 zinc atoms. Both
O(2)#4–Zn(2)–O(7)
O(6)#6–Zn(2)–O(7)
116.9(3)
107.2(3)
O(5)#5–Zn(2)–O(7)
107.9(3)
phosphonate and carboxylate groups of the ligand are
deprotonated, but the amine group is still protonated, hence
each ligand carries a charge of ꢂ4. Therefore, two Zn(II) ions
are required to balance the negative charges. The ligand in the
Pt(II) complex adopts a bidentate chelating coordination
mode: only the amine group and one carboxylate oxygen are
coordinated to the metal ion, the two phosphonate groups
remain protonated and are not involved in the coordination
Complex 2
Zn(1)–O(1)
Zn(1)–O(9)#2
0
1.79(2) Zn(1)–O(5 )#1
1.912(7) Zn(1)–O(3)#3
2.00(2) Zn(1)–O(5)#1
1.908(16)
1.928(9)
2.077(16)
2.010(19)
2.16(3)
1.896(8)
1.934(8)
1.44(2)
0
Zn(1)–O(1 )
0
0
0
0
Zn(1 )–O(6 )#4
Zn(1 )–O(5)#1
Zn(1 )–O(6)#4
1.88(2) Zn(1 )–O(9)#2
0
0
2.10(2) Zn(1 )–O(1 )
2.18(2) Zn(2)–O(7)#5
1.928(7) Zn(2)–O(4)#6
0
Zn(2)–O(8)#4
Zn(2)–O(2)
O(1)–Zn(1)–O(5 )#1
9
0
bonding.
1.964(8) P(1)–O(1 )
0
80.0(9)
O(1)–Zn(1)–O(9)#2 106.3(7)
O(1)–Zn(1)–O(3)#3 113.9(7)
O(9)#2–Zn(1)–O(3)#3 124.9(4)
4
The ZnO tetrahedra are further interconnected by bridging
0
O(5 )#1–Zn(1)–O(9)#2 105.5(5)
O(5 )#1–Zn(1)–O(3)#3 117.0(6)
phosphonate and carboxylate groups, resulting in the forma-
tion of a 3D network (Fig. 2). It is interesting to note that two
types of 12-membered rings are formed. One such ring con-
tains 3 Zn, 3 P and 6 O atoms [Fig. 3(a)], whereas the other
ring is composed of 3 Zn, 2 P, 1 C and 6 O atoms [Fig. 3(b)],
that is one phosphonate group in Fig. 3(a) being substituted by
a carboxylate group.
0
0
0
0
O(5 )#1–Zn(1)–O(1 )
0
99.3(8)
100.6(7)
O(9)#2–Zn(1)–O(1 ) 105.5(6)
O(1)–Zn(1)–O(5)#1 104.4(8)
O(3)#3–Zn(1)–O(5)#1 102.0(6)
O(5 )#1–Zn(1 )–O(1) 99.7(14)
O(7)#5–Zn(2)–O(4)#6 107.3(3)
O(3)#3–Zn(1)–O(1 )
O(9)#2–Zn(1)–O(5)#1 102.7(5)
0
0
0
O(1 )–Zn(1)–O(5)#1
123.1(7)
O(7)#5–Zn(2)–O(8)#4 110.3(3)
O(8)#4–Zn(2)–O(4)#6 114.3(3)
O(8)#4–Zn(2)–O(2)
O(7)#5–Zn(2)–O(2)
O(4)#6–Zn(2)–O(2)
115.7(3)
108.6(3)
100.8(3)
Symmetry transformations used to generate equivalent atoms.
For complex 1: #1 x ꢂ y þ 2, x þ 1, z þ 1=6; #2 x ꢂ y þ 1, x þ 1, z þ 1=6;
Crystal structure of Zn [HPO CH NH(CH PO ) ], 2
2
3
2
2
3 2
#
3 x þ 1, y þ 1, z; #4 x þ 1, y, z; #5 x, y ꢂ 1, z; #6 x ꢂ y þ 1, x, z þ 1=6.
The structure of complex 2 also features a 3D network struc-
ture similar to that in complex 1. As shown in Fig. 4, the
asymmetric structural unit of complex 2 contains two zinc
atoms and one ligand. The Zn1 atom is disordered and has two
For complex 2: #1 x ꢂ y, x ꢂ 1, z þ 1=6; #2 x ꢂ 1, y, z; #3 x ꢂ y, x,
z þ 1=6; #4 x ꢂ 1, y ꢂ 1, z; #5 y, ꢂ x þ y, z ꢂ 1=6; #6 x, y ꢂ 1, z.
0
orientations (Zn1 and Zn1 with 89.6% and 10.4% occu-
pancies, respectively). Three phosphonate oxygen atoms (O1,
O5 and O6) are also disordered and each has two orientations
0 0 0
(
Each zinc atom is tetrahedrally coordinated by four phos-
O1, O1 , O5, O5 , O6 and O6 with 50% occupancy each).
phonate oxygen atoms from four ligands. The Zn–O distances
range from 1.79(2) to 2.18(2) A (Table 1). These values repre-
sent too broad a range but are a reflection of the disorder. The
+
Fig. 2 View of crystal structure of complex 1 along the a axis. C-PO
tetrahedra are in black. Zn, N, carboxylate C and O atoms are shown
as open (large), open (small), black and crossed circles, respectively.
3
+
average Zn–O value for Zn2 is 1.931 A which is normal for 4-
coordinate zinc. Two phosphonate groups of the ligand are
completely deprotonated. The amine group and the third
phosphonate group, however, remain still 1H-protonated, as
indicated by the metal–ligand ratio. Nevertheless, it is not easy
to accurately determine which phosphonate group is protona-
ted due to the disorder problem. According to the ordered
model we refined at first, the O6 atom is most likely protonated.
Fig. 1 ORTEP representation of the asymmetric unit of complex 1.
Thermal ellipsoids are drawn at 50% probability.
New J. Chem., 2002, 26, 1010–1014
1011

View Article Online
Fig. 3 Two types of 12-membered rings in complex 1= Zn, P, C and
O atoms are represented by open, hatched, black and crossed circles,
respectively.
Fig. 5 View of crystal structure of complex 2 along the a axis. C-PO
tetrahedra are in black. Zn and amine N atoms are shown as large
3
open and octanded circles, respectively. For the sake of clarity, the
structure is drawn with the ordered model.
0
Fig. 4 View of the asymmetric unit of complex 2. Zn1 (Zn1 ), O1
0
0
0
(O1 ), O5 (O5 ) and O6 (O6 ) are disordered. The dashed lines re-
present the bonds related to disordered atoms.
Fig. 6 Two types of 12-membered rings in complex 2. Zn, P, N, C
and O atoms are represented by open, hatched, octanded black and
crossed circles, respectively. For the sake of clarity, the Zn1 atom is
shown by only one orientation.
The ZnO4 tetrahedra are interconnected by phosphonate
groups, resulting in the formation of a complex 3D network as
shown in Fig. 5, and rings of various sizes. Two types of 12-
membered rings are created (Fig. 6). One such ring contains 3
Zn, 3 P and 6 O atoms, the other 12-membered ring is com-
posed of 2 Zn, 3 P, 4 O, 2 C and one N atoms. We can view the
latter ring is formed by replacing one ZnO4 tetrahedra in the
former ring by an amine tetrahedron.
weight loss of 12.32% is in good agreement with the calculated
value (11.29%). The second step corresponds to the burning of
ꢀ
the remaining organic group, completed at about 800 C. The
2 2 7
final product is Zn P O , a metal pyrophosphate. The total
weight loss of 21.8% is in good agreement with the calculated
ꢀ
The ligand adopts an octadentate coordination mode, and
bridges with 8 Zn(II) atom. This is different from that in its
hydrated and non-hydrated divalent metal complexes. In the
one (22.0%). Complex 2 is stable up to 394 C. The TGA
diagram for complex 2 shows two steps of major weight loss
that are overlapped. The first step is the release of water
molecules formed by the condensation of hydrogen phospho-
M[NH(CH
2
PO
3
H)
3
(H
2
O)
3
] (M ¼ Co, Mn, Ni, Cu, Zn, Cd)
complexes, all the phosphonate groups are 1-H protonated,
each one is unidentately coordinated to a metal ion, forming
a 1D chain. Such chains are further interconnected into a
ꢀ
nate groups, which starts at 394 C. The second step is the
ꢀ
burning of organic groups, which is complete at about 950 C.
The total weight loss is 11.14%, which is in good agreement
with the calculated weight loss of 11.73% if the final products
2
phosphonate oxygen atoms.
D layer via hydrogen bonding between the uncoordinated
1
1
The ligand in the Mn
2 2 7
are assumed to be zinc pyrophosphate (Zn P O ) and zinc
metaphosphate [Zn(PO ) ] in a 1 to 2 ratio. Our previous TGA
3 2
[
2 3 3
NH(CH PO H) ] complex is pentadenate, and bridges with
five metal ions. Two phosphonate groups are bidentate, and
the third one remains unidentate as in hydrated complexes.
The 5-coordinated Mn(II) ions are interconnected by bridging
phosphonate groups into a 3D network, instead of the layer
studies indicate that metaphosphate phases can be formed
when the number of phosphonate groups per metal ion in the
initial metal phosphonates is larger than one, such as in
divalent metal complexes with N-methyliminobis(methylene-
1
2
structure in its hydrated complex.
1
3
phosphonic acid).
Thermogravimetric study
NMR analysis
A TGA diagram of complex 1 shows two weight losses. The
first step is the loss of the carboxylate group of the ligand,
which begins at about 403 C and is completed at 541 C. The
3
1
2
The P NMR spectra of the two ligands were acquired in D O
ꢀ
ꢀ
31
solution while those of complexes 1 and 2 were solid P MAS
1
012
New J. Chem., 2002, 26, 1010–1014

View Article Online
1
2
NMR spectra. The free ligands, H
phosphorus peaks of the phosphonate groups at 7.968 and
.335 ppm, respectively, thus all phosphonate groups of each
5
L and H
6
L , show single
complexes with nitrilotriacetic acid [N(CH
has three carboxylate groups instead of the three phosphonate
2 3
COOH) ], which
1
4,15
8
groups in nitrilotris(methylenephosphonic acid).
Usually
ligand have the same environment. Upon complexing with
zinc(II) ions, their chemical shifts moved upfield to 6.871 and
bases such as alkali hydroxide and amines are added to remove
protons on the carboxylate groups during the preparation of
the metal complexes. The ligand in these complexes chelates
with a metal ion in two different ways. The first type of che-
lation involves three carboxylate oxygen atoms from three
carboxylate groups and a nitrogen atom and three 5-mem-
6
.496 ppm, respectively, for complexes 1 and 2. There is no
splitting of peaks, indicating that all phosphonate groups in
each zinc complex have the same coordination environment.
1
4
bered chelate rings are formed, whereas in the second type of
chelation, only two carboxylate oxygen atoms and a nitrogen
atom chelate with a metal ion, and thus only two 5-membered
chelate rings are formed, the third carboxylate group remains
Discussion
Hydrothermal reaction of zinc(II) acetate with N,N-bis(pho-
sphonomethyl)aminoacetic acid [H
and nitrilotris(methylenephosphonic acid) [N(CH PO H ) ]
2 3 2 2 2 2
O PCH ) NCH CO H]
1
5
uncoordinated. Both types of chelation are adopted in the
2
3
2 3
1
6
Fe(III) complex. From these studies, it is concluded that with
more carboxylate groups replacing the phosphonate groups in
the ligand, the deprotonation of the amine group becomes
much easier and chelation coordination modes are preferred.
resulted in two new zinc(II) phosphonates, namely, Zn
PCH ) NHCH CO ] (complex 1) and Zn [HO PCH NH(CH
2
PO ) ] (complex 2). Both complexes have a similar 3D network
3 2
2 3
[O
2
2
2
2
2
3
2
structure. In both complexes, the ZnO tetrahedra are inter-
4
connected through bridging phosphonate and=or carboxylate
groups. The amine group in both complexes is protonated and
hence has tetrahedral geometry.
Experimental
For divalent metal complexes with nitrilotris(methylene-
phosphonic acid) it is interesting to note that the structures of
the complexes obtained are affected by the ligand-to-metal
ratio used in the synthesis. The hydrated complexes with a
hydrogen bonded layer structure and a formula of M[NH
Materials and methods
Deionized water used in all experiments was purified to a
resistivity of 17.6 MO cm with a Barnstead Nanopure II Sys-
tem. All other chemicals were of reagent grade quality
obtained from commercial sources and used without further
purification. Solution NMR was recorded on a Varian Unity
(
CH
2
PO
3
H)
3
](H
2
O)
3
(M ¼ Co, Mn, Ni, Cu, Zn, Cd) were
isolated when the ligand-to-metal ratio is in the range of 1 : 1
to 5 : 1. With the ratio increased to 10 : 1, the aqua ligands
were replaced by phosphonate oxygen atoms and the Mn
complex thus formed has a 3D network structure. The phos-
phonate groups in both hydrated and non-hydrated complexes
are 1H-protonated.
replaced by an additional divalent metal ion when the ratio
of ligand-to-metal is equal to or less than 1 : 2, as in Zn [HPO
NH(CH PO ] (complex 2).
Plus 300 spectrometer. H PO (EM Science, 85%) was used as
3
4
3
1
31
P standard reference. The P solid state MAS NMR spectra
were obtained on a Bruker MSL-300 unit. Elemental analysis
data were obtained from Desert Analytics, Tucson, AZ.
Thermogravimetric analysis was carried out with a TA 4000
unit, at a heating rate of 10 C min
atmosphere.
1
1,12
Two more protons are removed and
ꢀ
ꢂ1
under an oxygen
2
3
2
3 2
)
Another aspect of interest is the effect of the carboxylate
group attached to the ligand on the structures of the metal
phosphonates formed. The structures of nitrilotris(methyl-
enephosphonic acid) and three of its carboxylate-substituted
derivatives are shown in Scheme 1. The main difference
between complexes 1 and 2 is that one of the phosphonate
groups in complex 2 is replaced by a carboxylate group. This
substitution results in only small changes in the structure of
their metal phosphonates. When two phosphonate groups in
nitrilotris(methylenephosphonic acid) are substituted by two
carboxylate groups, the so-formed PMIDA ligand behaves
very differently. It chelates Co(II) or Zn(II) ions with the
nitrogen, two carboxylate and one phosphonate oxygen atoms.
The interconnection of metal ions by bridging carboxylate
and phosphonate groups resulted in metal carboxylate-
Syntheses
N,N-Bis(phosphonomethyl)aminoacetic acid [(H O PCH )
2 2
2
3
1
NCH CO H, H L ]. The diphosphonic acid with a functional
2
2
5
carboxylate group was prepared by a Mannich type reaction.
Glycine (Aldrich, 7.6 g, 100 mmol) was mixed with hydro-
chloric acid (EM Science, 17.0 cm ), deionized water (17 cm )
and phosphorous acid (Aldrich, 32.8 g, 400 mmol). The mix-
3
3
ꢀ
ture was allowed to reflux at 120 C for 1 h, then paraf-
ormaldehyde (Aldrich, 9.0 g, 300 mmol) was added in small
portions over a period of 1 h, and the mixture was then
refluxed for an additional hour. Removal of solvents afforded
a white powder, which was dissolved in 10 cm of water and
3
recrystallized by adding 100 cm of acetone, yielding 19.5 g of
3
phosphonate hybrid layered compounds, [Co
(
both complexes the amine group of the H PMIDA is not
4
2
(PMIDA)
N,N-bis(phosphonomethyl)aminoacetic acid (yield 74.1%). Its
purity was confirmed by NMR measurements and elemental
H O) ]ꢁH O and [Zn (PMIDA)(CH CO H)]ꢁ2H O. In
2
5
2
2
3
2
2
3
1
1
analysis. P NMR shows only a single peak at 7.968 ppm. H
NMR: 4.203 ppm (–CH CO , 2H, s), 3.499 ppm (–CH –PO
d, 4H, JH-P ¼ 12.9 Hz). Elemental analysis for C H NO P :
7
protonated. Many studies have been reported on the metal
2
2
2
3
,
4
11
8 2
C, 18.33%; H, 4.27%; N, 5.15%; P, 23.38%. Calcd: C,
8.25%; H, 4.18%; N, 5.32% P, 23.57%.
1
Preparation of Zn
Zn [HO PCH NH(CH
2
[(O
3
PCH
PO ) ] (complex 2). Both complexes
2 2 2 2
) NHCH CO ] (complex 1) and
2
3
2
2
3 2
were synthesized by hydrothermal reactions. A mixture of 2.0
mmol of zinc acetate (Fisher Chem.), 1.0 mmol of N,N-
bis(phosphonomethyl)aminoacetic acid or nitrilotris(methyl-
enephosphonic acid) (Fluka) and 10.0 ml of deionized water
was sealed into a bomb equipped with a Teflon liner, and then
ꢀ
heated at 180 C for 5 days. Colorless crystals for complexes
1 and 2 were recovered in ca. 45.6% and 37.3% yields,
Scheme 1 Nitrilotris(methylene phosphonic acid) and its derivatives
substituted by one, two and three carboxylate groups.
3
respectively. Results of the P solid state MAS NMR
1
New J. Chem., 2002, 26, 1010–1014
1013

View Article Online
atom is disordered and thus has two orientations. A disordered
measurements showed a single peak at 6.871 ppm for complex
and a single peak at 6.496 ppm for complex 2. Elemental
analysis for complex 1, C Zn NO : C, 12.20%; H, 1.65%;
N, 3.48%; P, 15.74%. Calcd: C, 12.31%; H, 1.80%; N, 3.59%;
9 3
P, 15.91%. Elemental analysis for complex 2, C Zn NO P :
0
1
model of the zinc atom (Zn1 and Zn1 at 89.6% and 10.4%
occupancies, respectively) resulted in a lower R value (6.56%)
H
4 7
2
8
P
2
1
+
3
+
and a featureless residual (1.246 e A , 0.56 A from C1). The
disordered oxygen atoms, as well as C1 and C2 atoms were
refined with isotropic thermal parameters. All hydrogen atoms
were generated geometrically, assigned fixed isotropic thermal
parameters and included in the structure factor calculations.
Some of the data collection and refinement parameters are
summarized in Table 2. Important bond lengths and angles for
complexes 1 and 2 are listed in Table 1.
H
3 8
2
C, 8.33%; H, 1.74%; N, 3.15%; P, 21.96%. Calcd: C, 8.46%;
H, 1.88%; N, 3.29%; P, 21.84%.
Crystallography
Single crystals of complexes 1 and 2 were mounted on a Bruker
Smart CCD and reflections collected using MoKa radiation
CCDC reference numbers 187598 and 187599. See http:==
www.rsc.org=suppdata=nj=b2=b2020296n= for crystallographic
data in CIF format or other electronic format.
+
(
l ¼ 0.71069 A) and a graphite monochromator at 110(2) K.
The cell constants were indexed from reflections obtained from
0 frames collected with 10 s exposure per frame. A hemi-
sphere of data (1271 frames at 5 cm detector distance) was
6
Acknowledgements
collected by the narrow-frame method with scan widths of
ꢀ
0
.30 in o and exposure time of 30 s per frame. The first 50
We acknowledge with thanks the financial support from the
Robert A. Welch Foundation through Grant No. A673 and
the Department of Energy, Basic Sciences Division, through
Grant No. DOE 448071-00001.
frames were recollected at the end of data collection to assess
the stability of the crystal, and it was found that the decay in
intensity was less than 1%. The data were corrected for
Lorentz factor, polarization, air absorption and absorption
due to variations in the path length through the detector
faceplate. An empirical absorption correction based on the C
scan method was also applied.
References
1
(a) E. Stein, A. Clearfield and M. A. Subramanian, Solid State
Ionics, 1996, 83, 113; (b) G. Alberti and U. Costantino, in Com-
prehensive Suramolecular Chemistry, ed. J. M. Lehn, Pergamon-
Elsevier Science Ltd., London, 1996, p. 1; (c) A. Clearfield, Curr.
Opin. Solid State Mater. Sci., 1996, 1, 268; (d) A. Clearfield, Prog.
Inorg. Chem., 1998, 47, 371 (and references therein).
M. E. Thompson, Chem. Mater., 1994, 6, 1168.
G. Alberti and U. Costantino, in Comprehensive Supramolecular
Chemistry, ed. J. M. Lehn, Pergamon-Elsevier Science Ltd.,
London, 1996, p. 151.
The space group was determined to be either P6 (No. 169)
1
or P6
were solved using direct methods (SHELXTL) in space group
P6 (No. 169) and refined by least-square methods with atomic
coordinates and anisotropic thermal parameters for non-
5
(No. 170) for both complexes 1 and 2. Both structures
1
1
7
2
3
hydrogen atoms. Absolute structure parameters thus refined
are ꢂ0.04(3) and 0.04(3) for complexes 1 and 2, respectively.
5
Refinements of both structures using space group P6 (No.
1
70) resulted in higher final R
1
values (for observed data,
4
(a) B. Zhang and A. Clearfield, J. Am. Chem. Soc., 1997, 119, 2751;
(b) C. V. K. Sharma and A. Clearfield, J. Am. Chem. Soc., 2000,
122, 1558; (c) I. Lukes, J. Kotek, P. Vojtisek and P. Hermann,
Coord. Chem. Rev., 2001, 216–217, 287; (d ) A. Clearfield, D. M.
Poojary, B. Zhang, B. Zhao and A. Derecskei-Kovacs, Chem.
Mater., 2000, 12, 2745.
0
.0573 and 0.0784, for complexes 1 and 2, respectively) and
very large absolute structure parameters [0.738(4) and 0.939(4),
respectively, for complexes 1 and 2]. Hence P6 (No. 169) was
1
used for all refinements of both structures. All atoms in com-
plex 1 are well behaved. However, disorder problems exist for
some atoms in complex 2. An ordered model gave large ther-
mal parameters for Zn1, O1, O5 and O6, and also a residual of
5
6
(a) B. Zhang, D. M. Poojary, A. Clearfield and G.-Z. Peng, Chem.
Mater., 1996, 8, 1333; (b) D. M. Poojary and A. Clearfield,
J. Organomet. Chem., 1996, 512, 237; (c) D. M. Poojary, B. Zhang
and A. Clearfield, Angew. Chem., Int. Ed. Engl., 1994, 33, 2324.
B. Zhang, D. M. Poojary and A. Clearfield, Inorg. Chem., 1998,
37, 249.
+
3
+
3
After splitting O1, O5 and O6 atoms into two orientations (O1,
.5 e A , which is 1.50 A from Zn1. The R
1
was about 8.0%.
0
0
0
O1 , O5, O5 , O6 and O6 ) with 50% occupancy for each site),
the R value was lowered to 7.5%, but the residual around Zn1
7
8
J.-G. Mao and A. Clearfield, Inorg. Chem., 2002, 41, 2319.
S. O. H. Gutschke, D. J. Price, A. K. Powell and P. T. Wood,
Angew. Chem., Int. Ed., 1999, 38, 1088.
1
remained as high as before. Careful examination of the
environment around the residual peak indicate it also had a
tetrahedral geometry. At this point, we realized that the Zn1
9
0
M. Galanski, B. K. Keppler and B. Nuber, Angew. Chem., Int. Ed.
Engl., 1995, 34, 1103.
C. V. K. Sharma and A. Clearfield, J. Am. Chem. Soc., 2000, 122,
1
4
394.
Table 2 Crystal data and structure refinement for complexes 1 and 2
11 C. V. K. Sharma, A. Clearfield, A. Cabeza, M. A. G. Aranda and
S. Bruque, J. Am. Chem. Soc., 2001, 123, 2885.
Complex
1
C
2
C
12 A. Cabeza, X. Ouyang, C. V. K. Sharma, M. A. G. Aranda,
S. Bruque and A. Clearfield, Inorg. Chem., 2002, 41, 2325.
13 (a) D. M. Poojary, B. Zhang and A. Clearfield, J. Am. Chem. Soc.,
1997, 119, 12550; (b) B. Zhang, D. M. Poojary and A. Clearfield,
Inorg. Chem., 1998, 37, 1844; (c) J. G. Mao, Z. Wang and A.
Clearfield, Inorg. Chem., 2002, accepted.
14 (a) Q. Wang, X. Wu, W. Zhang, T. Sheng, P. Lin and J. Li, Inorg.
Chem., 1999, 38, 2223; (b) L. S. White, P. V. Nilsson, L. H.
Pignolet and L. Que Jr., J. Am. Chem. Soc., 1984, 106, 8312; (c) D.
Dakternieks, G. Dyson, R. Tozer and E. R. T. Tiekink, J.
Organomet. Chem., 1993, 458, 29; (d ) S. H. Whitlow, Inorg. Chem.,
1973, 12, 2286.
Empirical formula
M
Crystal system
4
H
7
Zn NO
2
8
P
2
3 8 2 9 3
H Zn NO P
389.79
Hexagonal
P6 (No. 169)
8.0677(12)
27.283(6)
1537.9(5)
6
110(2)
5.021
3597
425.75
Hexagonal
P6 (No. 169)
8.3553(8)
26.657(4)
1611.6(3)
6
110(2)
4.952
9968
Space group
1
1
+
a=A
+
c=A
U=A
+
3
Z
T=K
ꢂ1
m(Mo-Ka)=mm
Reflections collected
Independent reflections
R
1851
0.0764
1380
0.0443
0.0941
0.0686
0.1030
2599
0.0716
2599
0.0656
0.1132
0.0918
0.1269
15 (a) T. Shibahara, H. Hattori and H. Kuroya, J. Am. Chem. Soc.,
1984, 106, 2710; (b) O. P. Gladkikh, T. N. Polynova, M. A. Porai-
Koshits and N. D. Mitrofanova, Koord. Khim., 1990, 16, 758; (c)
N.-H. Dung, B. Viossal, A. Busnot, J. M. G. Perez, S. G. Garcia
and J. N. Gutierrez, Inorg. Chem., 1988, 27, 1227; (d) H. Kobayashi,
T. Shibahara and N. Uryu, Bull. Chem. Soc. Jpn., 1990, 63, 799.
16 W. Clegg, A. K. Powell and M. J. Ware, Acta Crystallogr., Sect. C,
int
Observed reflections [I > 2s(I)]
a
R
1
a
wR [I > 2s(I)]
2
a
1
R (all data)
a
wR
2
(all data)
1
984, 40, 1822.
a
2
2 2
2 2 1=2
) ] }
R
1
¼ SkF j ꢂ jF
o
o
k=SjF
o
j, wR
2
¼ {Sw[(F
o
) ꢂ (F
o
) ] =Sw[(F
o
.
17 G. M. Sheldrick, SHELXTL, Crystallographic Software Package,
version 5.1, Bruker-AXS, Madison, WI, 1998.
1
014
New J. Chem., 2002, 26, 1010–1014