Hydrothermal synthesis and structural characterization of anorganically-templated zincophosphite:

½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O

Wenjun Dong, Guanghua Li, Zhan Shi, Wensheng Fu, Dong Zhang, Xiaobo Chen,Zhimin Dai, Lei Wang, Shouhua Feng *

State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130023, PR China

Received 25 January 2003; accepted 8 March 2003

Abstract

A new three-dimensional organically templated ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O was hydrothermally synthesized and charac-

terized by single crystal X-ray diffraction. The three-dimensional framework is built up from two-dimensional layers with 4.8-mem-

bered rings and one-dimensional chains of 4-membered rings. The structure has strictly alternating ZnO4 tetrahedra andHPO3 pseudo

pyramids which are linked through their vertices giving rise to the three-dimensional architecture with 8,12-membered ring channels.

The protonated water molecules and diprotonated piperazine are located in the 8-membered and 12-membered channels, respectively.

The compound crystallizes in monoclinic system, space group P21=n with cell parameters, a ¼ 9:6739ð16Þ �AA, b ¼ 8:4528ð13Þ �AA,c ¼ 20:257ð4Þ �AA, b ¼ 97:966ð5Þ�, Z ¼ 4, R ¼ 0:023, and Rw ¼ 0:060. It was characterized by the powder X-ray diffraction, differentialthermal-thermogravimetric analyses, IR spectroscopy and proton-decoupled 31P MAS NMR solid-state spectroscopy.

� 2003 Elsevier Science B.V. All rights reserved.

Keywords: Hydrothermal synthesis; Organically templated; Zincophosphite; Crystal structure

1. Introduction

Since the first organically templated zincophosphite

was reported by Harrison in 1997 [1], a number of

studies on metal phosphites have been carried out for

novel structures and properties [1–5]. Organically tem-

plated zincophosphites are basically built up from Zn-

centered tetrahedra (ZnO4 or ZnO3N) and P-centeredHPIIIO2�

3 pseudo pyramids, which are generally pre-

pared under hydrothermal conditions. The zinc-

ophosphites exhibit rich structural and compositional

diversity, such as ½H2NðCH2Þ2NH2� � 0:5ZnHPO3½2�ðN4C2H4ÞZnHPO3 [5] containing a similar 4,8-net and

ðNC5H12Þ2Zn3ðHPO3Þ with 16-membered ring windows[6]. In contrast to the large numbers of zinc phosphites,

the reports of organically templated zinc phosphites arestill rare. Moreover, the replacement of phosphate by

phosphite in these systems has been taken accounts for,

since the incorporations of the pseudo pyramidal hy-

drogen phosphite group ½HPO3�2� create some novel

structures. In order to extend the knowledge about the

open-framework of phosphites, we attempt to focus our

attention on the zinc phosphite diammonium system.

Our group has developed the hydrothermal synthesis

of inorganic–organic zinc phosphites, and found½H3NCH2NH3CHCH3�½Zn2ðHPO3Þ3� �H2O; ðC6H14N2Þ½Zn3ðHPO3Þ4�; ðC4H12N2Þ½Zn3ðHPO3Þ4�; ½H3NðCH2Þ6NH3� ½Zn3ðHPO3Þ4�, etc. [7,8]. In this work, we describethe synthesis and characterization of ½C4N2H12�0:5 �½Zn3ðHPO3Þ4� �H3O with zeolite like topologies, a new

three-dimensional structure templated by piperazine.

2. Experimental

2.1. Synthesis

The title compound was synthesized by a hydrother-

mal method. A typical synthetic procedure began with

Inorganic Chemistry Communications 6 (2003) 776–780

www.elsevier.com/locate/inoche

*Corresponding author. Tel.: +86-431-567-0650; fax: +86-431-5671-

974.

E-mail address: shfeng@mail.jlu.edu.cn (S. Feng).

1387-7003/03/$ - see front matter � 2003 Elsevier Science B.V. All rights reserved.

doi:10.1016/S1387-7003(03)00100-X

0:297 g ZnðNO3Þ2 � 6H2O, 0.388 g of piperazine hexa-

hydrate, 2 ml H2O and 0:328 g H3PO3 to form a solu-

tion, to which 0.027 ml ethylenediamine was added with

stirring to form a reaction mixture. The reaction mixture

was further stirred for 1 h and sealed in a 23 ml Teflon-lined stainless steel autoclave with a filling capacity of

�15%, and then heated at 180 �C for 3 days. Plate-like

single crystals were separated by sonication and further

washed by distilled water and then air-dried.

2.2. Characterization

The powder X-ray diffraction (XRD) patterns wererecorded on a Siemens D5005 diffractometer with

Cu-Ka radiation (k ¼ 1:5418 �AA) with a graphite

monochromator. The step size was 0.02� and the counttime was 4 s. The element analysis and inductively

coupled plasma (ICP) analysis were performed on a

Perkin–Elmer 2400 Element analyzer and Perkin–El-

mer Optima 3300DV spectrometer, respectively. The

thermal gravimetric analysis (TGA) and differentialthermal analysis (DTA) were carried out on a Perkin–

Elmer DTA 1700 differential thermal analyzer and a

Perkin–Elmer TGA 7 thermogravimetric analyzer in

air with a heating rate of 10 �C/min. The IR spectrum

was recorded on a Nicolet Impact 410 FTIR spec-

trometer using KBr pellets. The 31P MAS-NMR

spectrum was collected on a Varian Unity-400 NMR

spectrometer.

2.3. Determination of crystal structure

A suitable single crystal with dimensions 0:350:32 0:20 mm was selected for single-crystal X-ray

diffraction analysis. The intensity data collected on a

Siemens SMART CCD diffractometer with graphite-

monochromated Mo-Ka (k ¼ 0:71073 �AA) radiation ata temperature of 298 2 K. Data processing was ac-

complished with the SAINT processing program [9].

The structure was solved by direct methods using the

SHELXTL crystallographic software package [10]. The

zinc and phosphorus atoms were first located, whereas

the carbon, nitrogen, and oxygen atoms were found in

the difference Fourier maps. The hydrogen atoms of

C, N residing on the amine molecules were placedgeometrically. The hydrogen atoms residing on the

phosphorus and protonation H3Oþ were located by

Fourier maps. The total number of measured reflec-

tions and observed unique reflections were 6935 and

2368 and the intensity data of 6935 independent re-

flections (�106 h6 10, �96 k6 9, �226 l6 19) were

collected in the x scan mode. Crystallographic data

for title compound are listed in Table 1. The struc-ture factor parameters have been deposited at the

Cambridge Crystallographic Data Centre (CCDC

201542).

3. Result and discussion

3.1. Characterization

Fig. 1 shows the experimental and simulated XRD

patterns for the product. The experimental XRD pattern

is in agreement with the simulated XRD pattern which

illustrated that the product is pure.

The ICP analysis indicated that the product contains

33.9 wt% Zn and 21.4 wt% of P, the calculated value of

33.83 and 21.52 wt% of P. The elemental analysisshowed that it contains 4.24 wt% C, 2.23 wt% H, and

2.36 wt% N (calcd 4.15 wt% C, 2.25 wt% H and 2.42

wt% N). This corresponded to a formula of

C2H13NO13P4Zn3, which was further confirmed by sin-

gle-crystal structure analysis.

Table 1

Crystal data and structure refinement for ðC3H12N2Þ�½Zn2ðHPO3Þ3� �H2O

Empirical formula ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O

Fw 634.25

T (K) 293(2)

k (�AA) 0.71073

Space group P21=na (�AA) 9.6739(16)

b (�AA) 8.4528(13)

c (�AA) 20.257(4)

b (�) 97.966(5)

V (�AA3) 2050.7(6)

Z 4

qcalc: ðmg=m�3Þ 2.345

l ðmm�1Þ 4.802

R1a ½I > 2hðIÞ� 0.0227

wR2b ½I > 2hðIÞ� 0.0602

aR1 ¼ RjjFoj � jFcjj=RjFoj.bwR2 ¼ fR½wðF 2

o � F 2c Þ

2�=R½wðF 2o Þ

2�g1=2.

Fig. 1. Simulated and experimental powder X-ray diffraction patterns

of ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O.

W. Dong et al. / Inorganic Chemistry Communications 6 (2003) 776–780 777

TGA profile shows an obvious weight loss of 3.1 wt%

ca. 340 �C, attributing to removal of H2O (calcd 3.11

wt%) in the product, and the weight loss of 7.6 wt% ca.

380 �C was attributed to the decomposition of pipera-

zine hexahydrate (calcd 7.60 wt%). DTA curve exhibitedone endothermic peak and one exothermic peak at ca.

340 and 380 �C, proving the above TGA results. The

structure of the title compound collapsed and converted

to an amorphous phase after the calcination at 600 �Cfor 2 h. At 800 �C, the amorphous phase recrystallizedto the ZnP2O7 (JCPDS: 34-0623), confirmed by powder

X-ray diffraction.

The IR spectra of the product phase exhibited themedium bands at 2625, 2670 and 2730 cm�1 due to theterminal NHþ

2 stretch and the stretching vibrations of –

CH2– groups at 2935 and 2845 cm�1. The bands at 2385

and 1070 cm�1 were attributed to the terminal P–H

stretch and deformation. The IR results showed clearly

the vibrations from HPO2�3 phosphite group and tem-

plate molecule [11].31P MAS-NMR spectra of the product showed four

resonances at 6.8, 5.0, 3.3 and )0.5 ppm, relative to a

standard of 85% H3PO4. These values agreed well with

the chemical shifts found in similar systems [2,3,12–14].

Four chemical shifts of P atoms correspond to four

crystallographically equivalent phosphorus sites in the

structure as indicated by X-ray structural analysis.

3.2. Description of structure

As seen in Fig. 2, the asymmetric unit consists of 23

distinct nonhydrogen atoms, all of which are at general

position. 19 atoms belong to the host atoms or frame-

work atoms consisting of 3 Zn, 4 P, and 12 O atoms, and

4 atoms to the guest atoms, being 1 N, 1 O and 2 C

atoms in this structure. Zn and P atoms are alternately

linked through bridging oxygen. All Zn atoms are tet-rahedrally coordinated and each shares four oxygen

atoms with adjacent P atoms. Zn–O bond distances are

in the range of 1.903–1.944 �AA [ðZnð1Þ–OÞav ¼ 1:930,ðZnð2Þ–OÞav ¼ 1:935, ðZnð3Þ–OÞav ¼ 1:930 �AA], and the

Zn–O–P bond angles are in the range of 125.0–154.4�(av 134.1�). Each of P atoms has a terminal P–H bond

Fig. 2. ORTEP drawing of the asymmetric unit of ½C4N2H12�0:5�½Zn3ðHPO3Þ4� �H3O (50% thermal ellipsoids).

Fig. 3. View of infinite 4-membered ring chain (a) and the layer (b) of

½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O.

Fig. 4. The framework structure of ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O

along b axis.

778 W. Dong et al. / Inorganic Chemistry Communications 6 (2003) 776–780

and shares three oxygen atoms with adjacent Zn atoms.

The O–P–H and the O–P–O bond angles are in the range

of 102.2–114.0�, indicating a pseudo pyramids of

HPO2�3 .

The structure of ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O

may be viewed as constructed from two different units,one-dimensional chain and two-dimensional layer.

These chains are built up from alternating orthogonal

two kinds of 4-membered rings, which are composed of

two ZnO4 tetrahedra and two HPO3 pseudo pyramids,

fused via Zn–O–P vertices. One 4-membered ring is built

up from two Zn (2) atoms and two P (4) atoms, the

other one from two Zn (2) atoms and two P (1) atoms.

They connect each other through common Zn (2) atom(shown in Fig. 3a).

In the layer mentioned above, there exists one type

of 4-membered ring built up from Zn1, P2, Zn3 and

P4 centered polyhedra which propagate along [0 0 1] as

shown in Fig. 3b. Every 4-membered ring is poly-

hedrally connected with other four same 4-membered

rings by bridge oxygen atoms. As a result, one

8-membered ring came into being that was enclosedby the four 4-membered rings alternating above and

below the sheet. This type of layer structure with al-

ternating 4,8 net has also been observed for the zeolite

APC [15].

The polyhedral connectivity in ½C4N2H12�0:5 �½Zn3ðHPO3Þ4� �H3O results in a three-dimensional to-

pology based on the two-dimensional network and one-

dimensional chain reported above. The Zn(3) centeredtetrahedra of the layer link P(3) centered pseudo pyra-

mids via bridge oxygen atoms to yield the three-di-

mensional structure and result in an anionic network

with a Zn/P ratio of 3/4. This polyhedral connectivity

results in a system of 12 and 8-membered ring channels

propagating along [0 1 0], which appear to have formed

around the ½C4N2H12�2þ and H3Oþ cations, respectively

(shown in Fig. 4). Organic amines and water exit ascharge-balanced cations in the diprotonated state and

serve as H-bond donors to the nearest framework of

oxygen. The piperazine interacts by way of N–H � � �Obonds in 12-member ring channel and water interacts by

way of O–H � � �O bonds in 8-member ring channel with

the three-dimensional framework (Table 2).

4. Conclusions

In summary, a novel three-dimensional open-frame-

work zincophosphites, ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O, has been synthesized under hydrothermal condi-

tions. This structure consists of alternatively linked

ZnO4 tetrahedra and HPO3 pseudo pyramid units. Thisorganically templated zincophosphites possess channels

with 12- and 8-membered ring channels in which the

protonated templated and water are located. The suc-

cessful synthesis of the title compound opens the field of

synthetic chemistry in metal phosphite systems.

Acknowledgements

We thank the National Natural Science Foundation

of China (No. 20071013), the State Basic Research

Project of China (G2000077507) and Foundation for

‘‘Chang-Jiang’’ scholarship by the Ministry of Educa-

tion of China for support.

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Table 2

Hydrogen bonds for ½C4N2H12�0:5 � ½Zn3ðHPO3Þ4� �H3O (�AA and deg.)

D–H � � �A dðD–HÞ (�AA) dðH � � �AÞ (�AA) dðD � � �AÞ (�AA) Angle ðD–H � � �AÞ (�)

Oð1WÞ–Hð1WAÞ � � �Oð6Þ 0.906(10) 1.941(17) 2.833(5) 167(6)

Oð1WÞ–Hð1WBÞ � � �Oð10Þ#1 0.912(10) 2.00(3) 2.858(5) 155(6)

Oð1WÞ–Hð1WCÞ � � �Oð9Þ 0.910(10) 2.24(3) 3.094(5) 156(5)

Oð1WÞ–Hð1WCÞ � � �Oð3Þ 0.910(10) 2.29(4) 2.998(5) 135(5)

Nð1Þ–Hð1AÞ � � �Oð12Þ 0.90 1.99 2.859(4) 162.0

Nð1Þ–Hð1AÞ � � �Oð11Þ 0.90 2.49 3.170(5) 132.5

Nð1Þ–Hð1BÞ � � �Oð2Þ#2 0.90 2.12 2.872(4) 140.4

Nð1Þ–Hð1BÞ � � �Oð1Þ#2 0.90 2.36 3.031(4) 131.2

Symmetry transformations used to generate equivalent atoms: #1-x+1/2, y-1/2, -z+1/2; #2x-1, y+1, z.

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