Ž. Inorganic Chemistry Communications 3 2000 379–382 www.elsevier.nlrlocaterinoche Hydrothermal synthesis and crystal structure of a novel one-dimensional ž/wx tritungstate: C H N W O 2102 310 Bangbo Yan, Yan Xu ) , Ngoh K. Goh, Lian S. Chia DiÕision of Chemistry, School of Science, Nanyang Technological UniÕersity, 469 Bukit Timah Road, Singapore 259756, Singapore Received 21 February 2000 Abstract Ž.wx Ethylenediammonium tritungstate, C H N W O , has been hydrothermally synthesized and structurally characterized. The 2102 310 structure of title compound consists of infinite chains running parallel to the b axis, that are made up of distorted WO octahedra linked 6 through shared corners and edges. The ethylenediammonium ions occupy interstrand region providing space-filling and charge-compensa- tion to anionic tritungstate matrix. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Hydrothermal synthesis; Tungstate; Crystal structures; Polyanions compounds 1. Introduction Recent years have witnessed a considerable achieve- ment in the crystal engineering of novel organicrinorganic hybrid materials due to their applications in catalysis, sorption, energy storage, molecular electronics, optical ma- wx terials and ceramics 1–4 . A promising synthetic route takes advantage of a low-temperature soft approach, hy- drothermal method, and the structure-directing function of organoamines. Recent developments in this area have proven its viability for the successful preparation of novel wx porous and low-dimensional materials 5–7 . Typical ex- amples include coorperative assembly of organic wx aminesrtransition metal oxides involving iron 8,9 , cobalt wx wx w x 10 , vanadium 11 and molybdenum 5,12,13 . While the combined application of hydrothermal crystallization and amine templates has been extensively exercised for the assembly of periodic elements, systematic investigation of tungsten oxide composite materials remains largely unex- plored. Here, we report the hydrothermal assembly and Ž. crystal structure of a novel one-dimensional tritungstate VI solid structurally directed and stabilized through ethylene- Ž.wx diammonium ions, C H N W O 1. 2102 310 ) Corresponding author. Tel.: q65-460-5179; fax: q65-469-8952. Ž. E-mail address: yxu@nie.edu.sg Y. Xu . 2. Experimental 2.1. Synthesis Ž. A gel mixture of Na WO P2H O 0.67 g, 2 mmol , 24 2 Ž.Ž . Ž ethylenediamine en 0.42 g, 7 mmol and H O 20 ml, 2 . 1.11 mol in the mole ratio 1:3.5:555 was heated at 1908C and autogenous pressure conditions for 62 h. Needle-shape Ž.wx colorless crystals of C H N W O 1 were isolated 2102 310 Ž and recovered yield: 0.37 g, 48% based on Na WO P 24 . w 2H O . The CHN elemental analysis of 1 gave observed 2 Ž.x Ž. Ž. calculated in wt% C, 3.02 3.10 ; H, 1.29 1.30 ;N, Ž. 3.61 3.62 which confirmed an empirical formula of Ž.wx C H N W O for 1. 2102 310 2.2. Thermal analysis Ž. Thermogravimetric analysis TGA was performed us- ing a Sateram TG-DTGrDSC thermogravimetric analyzer on powder specimen of 1 at a heating rate of 58C min y1 in N stream. 2 2.3. Infrared studies IR spectra were recorded using a Perkin–Elmer FT–IR spectrophotometer on KBr pellets in the range 400–4000 cm y1 . 1387-7003r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. Ž. PII: S1387-7003 00 00085-X () B. Yan, et al.rInorganic Chemistry Communications 3 2000 379–382380 Ž.wx Fig. 1. Packing view of C H N W O 1 along the b-axis. 2102 310 2.4. X-ray Crystallographic Studies X-ray crystallographic data of 1 were collected on a Siemens P4 diffractometer. Crystal data: monoclinic () Ž. Ž. Ž. P2 1 rn, as8.9512 10 , bs7.6483 11 , cs16.005 3 ˚˚ 3 Ž. Ž. A, b s92.020 14 8, Vs 1095.0 3 A , D s4.693 g calc cm y3 and Zs4. The structure was solved by direct methods and refined using full-matrix least squares on F 2 wx using the SHELXTL-97 package 14 . Non-hydrogen atoms were refined with anisotropic temperature factors. Hydro- gen atoms were placed at calculated positions and refined using the riding model of SHELXTL program with a fixed ˚ C–H bond length of 0.97 A and a N–H bond length of ˚ 0.90 A. Final refinement was based on 1917 reflections w Ž.x Ž. I)2s I for 134 parameters and converged to RwR 12 Ž. s0.0281 0.0634 . Atomic coordinates, bond lengths and angles and thermal parameters are presented in supplemen- tary crystallographic data. 3. Results and Discussion The title compound is initially isolated from the hy- drothermal reaction of WO , en, NaOH and H O in 32 polycrystalline form. Replacement of NaOH with LiOH produces the same crystalline phase with similar product quality and morphology. The reaction is then rationalized by using Na WO as W 6q source instead of WO that 24 3 gives rise to monophasic product of compound 1 contain- ing large single crystals. TGA shows a weight loss of ca. 7.9% in the temperature range 300–4808C indicating the Ž. release of en molecules calc, 8.0% . The infrared spectra of 1 present the following information: strong absorption y1 Ž. bands at 935 and 975 cm are ascribed to Õ WsO , and the features in the 784–889 cm y1 region are most likely Ž. associated with Õ O–W–O modes. In addition, absorption bands at 1480 and 1624 cm y1 , and a broad band centred at 3400 cm y1 suggest the presence of en species. By replac- ing en with other organodiamines such as 2,2 X -bipyridine Ž X . 2,2 -bipy , piperazine, and 4,4’-bipyridine, a few new organicrinorganic hybrid phases are obtained and struc- turally identified using the single crystal X-ray diffraction method. Brief crystal data of one of the phases, a mono- 4y Ž.wx Fig. 2. Structural building block W O of C H N W O 1. 6 20 2 10 2 3 10 () B. Yan, et al.rInorganic Chemistry Communications 3 2000 379–382 381 Fig. 3. Comparison of the one-dimensional chains adopted by the anions Ž.Ž .wxŽ.Ž .wxwxŽ. in: a C H N W O 1; b C H N Mo O 15 ; and c an 2102 310 2102 310 wxwx open framework solid K W O 16 . 2310 Ž X . clinic one-dimensional solid WO 2,2 -bipy , are summa- 3 rized in a footnote 1 . Ž.wx The structure of C H N W O 1 consists of infi- 2102 310 nite puckered chains of W O 4y separated by interstrand 620 2q Ž 2q . ethylenediammonium ions, C H N enH , as shown 2102 2 in Fig. 1. The W 6q sites exhibit distorted octahedral geometry which receive contributions from 1-, 2- and 4-coordinated oxo groups. Each W O 4y unit consists of a 620 pair of center-of-symmetry-related W O trimers of 310 edge-sharing WO octahedra as shown in Fig. 2. Adjacent 6 WO 4y units are connected by sharing two corners giving 620 rise to the infinite chain of 1 lying parallel to the b-axis. Ž. The coordination geometry of WO at W 1 is defined by 6 two terminal oxo groups and four unsymmetrical bridging Ž. Ž. oxo groups, and at W 2 and W 3 by one terminal oxo Ž. group and five unsymmetrical bridging oxo groups. W 1 site shows typical two short-two intermediate-two long Ž. Ž. bond length pattern of tungsten VI oxides, and W 2 and Ž. W 3 show one short-three intermediate-two long bond length pattern. enH 2q cations occupy interstrand regions 2 of the W O 4y chains and exhibit strong hydrogen bond 620 network to terminal and bridging oxo groups of the anionic chains of W O 4y . 620 1 Ž X . Crystal data for the monoclinic WO 2,2 -bipy phase. chemical 3 formula, C H N O W, M s 388.03, monoclinic space group Cc with 10 823 w ˚ Ž. Ž. Ž . unit cell dimensions as14.323 3 , bs9.608 2 , cs7.2922 15 A, b s ˚ 3 y3 Ž. Ž. 101.980 16 8, Vs981.6 4 A , Zs4, D s2.626 g cm , m s11.759 c mm -1 , Ts297 K. The linkage between WO octahedra in 1 is quite 6 Ž.wxwx distinct from those reported in C H N Mo O 15 2102 310 ŽŽ 4y Fig. 3 b . The anionic chain of W O of 1 is con- 620 structed from corner- and edge-sharing WO octahedra 6 while the one-dimensional chains of Mo O 4y of 620 Ž.wxwx C H N Mo O 15 is built up from MoO octahedra 2102 310 6 through shared corners, edges and faces. It should be Ž.wx further noted that compound C H N W O 1 re- 2102 310 ported in this paper is not analogous to a known tritungstate wxwx 2y phase, K W O 16 , in which W O anions are orga- 2310 310 nized into a three dimensional covalent framework struc- Ž ture through corner- and edge-shared WO octahedra Fig. 6 Ž 3c . Ž.wx The one-dimensional tritungstate C H N W O 1 2102 310 reported in this paper provides novel examples to the hydrothermal cooperate assembly of tungsten oxide com- posite materials. The strong solvating effect of water in combination with the structure-directing role of organoamines under the hydrothermal autogenous condi- tions evidently provides the conducive environment for the rearrangement of tungstenoxoanions, and construction of novel solid architecture from molecular precursors. It opens up the possibility of applying this method for assembling other low-dimensional and open-framework tungsten oxide materials with potentially interesting or useful properties. 4. Conclusion Ž. The successful synthesis of compound C H N 2102 wx WO 1 illustrates the power of hydrothermal synthesis 310 in engineering organicrinorganic solid materials with novel structures. It should be further noted that organic cations play a significant role in the isolation of the tritungstate phases. 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B32 Ž. 1976 1522. . hydrothermal assembly and Ž. crystal structure of a novel one-dimensional tritungstate VI solid structurally directed and stabilized through ethylene- Ž.wx diammonium. , cobalt wx wx w x 10 , vanadium 11 and molybdenum 5,12,13 . While the combined application of hydrothermal crystallization and amine templates has been