DALTON FULL PAPER J. Chem. Soc., Dalton Trans., 1999, 2147–2149 2147 Synthesis and characterisation of the first unidimensional cobalt hydrogen phosphate, [H3N(CH2)3NH3][Co(HPO4)2] Andrew R. Cowley and Ann M. Chippindale * Chemical Crystallography Laboratory, University of Oxford, 9 Parks Road, Oxford, UK OX1 3PD Received 22nd February 1999, Accepted 19th May 1999 The first unidimensional organically templated cobalt hydrogenphosphate, [H3N(CH2)3NH3][Co(HPO4)2], has been synthesized at 433 K under solvothermal conditions in the presence of 1,3-diaminopropane and the structure determined at 150 K using single-crystal X-ray diVraction.The compound contains anionic chains of formula [Co(HPO4)2]22 constructed from edge-sharing 4-membered rings of alternating CoO4 and HPO4 tetrahedra from which hang additional “pendant” HPO4 groups. The chains, which are structurally similar to those found recently in unidimensional aluminophosphates, are held together by a network of hydrogen bonds involving both interchain and chain–diamine interactions.Introduction The considerable interest shown recently in the synthesis and characterisation of open-framework metal phosphates reflects their potential applications as molecular sieves, ion-exchange materials and heterogeneous catalysts. The use of organic amines in phosphate synthesis has led to a plethora of new materials with either 3- or lower-dimensional structures. The structure-directing properties of these amines are not as yet well understood and use of one amine can lead to the formation of a number of diVerent framework structures.This is clearly illustrated by 1,3-diaminopropane, which may form 3- dimensional structures including [H2N(CH2)3NH3][HAl3- P3O14]?H2O,1 [ H3N(CH2)3NH3][(VO)3(OH)2(H2O)2(PO4)2] 2 and [H3N(CH2)3NH3]2[Fe4(OH)3(HPO4)2(PO4)3]?xH2O,3 2-dimensional structures such as [H3N(CH2)3NH3]0.5[VO][VO4] 4 and [H3N(CH2)3NH3]0.5[Co(PO4)]?0.5H2O5 or unidimensional chain structures such as [H3N(CH2)3NH3][Ga(HPO4)(PO4)].6 In this paper we describe the use of 1,3-diaminopropane in the synthesis of the first organically templated unidimensional cobalt hydrogenphosphate, and the structural characterisation of this material using single-crystal X-ray diVraction.Experimental The compound [H3N(CH2)3NH3][Co(HPO4)2] was prepared under predominantly non-aqueous solvothermal conditions. The oxide CoO (0.4 g) was suspended in ethylene glycol (6 cm3) by stirring and 1,3-diaminopropane (1.5 cm3) added to act as structure-directing agent.The mixture was stirred until homogeneous and then aqueous H3PO4 (1.5 cm3, 85% by weight) added with further stirring to give a gel of overall composition CoO:20 HOC2H4OH: 3.4 H2N(CH2)3NH2 : 4.1 H3PO4 : 3.9 H2O. The gel was placed in a Teflon-lined stainless-steel autoclave and heated at 433 K for 7 d. The resulting solid product consisted of a biphasic mixture of deep-blue needles of the [H3N(CH2)3NH3][Co(HPO4)2] and colourless blocks.The latter were identified by single-crystal X-ray diVraction as the diammonium hydrogenphosphate hydrate [H3N(CH2)3NH3][HPO4]? H2O7 (monoclinic, space group P21/c, lattice parameters a = 6.9808(8), b = 16.724(1), c = 7.8550(7) Å, b = 113.657(9)8 at 200 K). The solid was washed with 3 × 20 cm3 glacial acetic acid and 3 × 20 cm3 methanol to remove the diammonium hydrogenphosphate hydrate and dried in air at 344 K.The resulting product was shown by powder X-ray diVraction (Fig. 1) to be monophasic. Combustion analysis results are C 10.78, H 4.70 and N 8.29% by weight, which are in good agreement with the values of C 11.02%, H 4.31% and N 8.57% calculated for the formula [H3N(CH2)3NH3][Co(HPO4)2]. Although stable indefinitely in dry air, a finely ground sample of the compound reacted rapidly with water at room temperature to form a palepink gelatinous solid which was shown to be amorphous by powder X-ray diVraction.An infrared spectrum of the compound (Perkin-Elmer 1710 FT spectrophotometer, KBr disc) showed a broad, strong absorption band in the range 3600–2300 cm21 and a number of sharp, medium-intensity bands in the range 1670–1170 cm21. Bands in the former region are compatible with OH, NH and CH stretching modes and in the latter with NH3, CH2 and OH deformation modes, consistent with the presence of H3N(CH2)3NH3 21 and OH groups. A single crystal suitable for X-ray diVraction study (size 0.06 × 0.12 × 0.40 mm) was selected from the as-synthesized material and mounted on a nylon fibre using a drop of perfluoropolyether oil.It was then rapidly cooled to 150 K in a flow of cold nitrogen using an Oxford Cryosystems CRYOSTREAM cooling system. Data were collected on an Enraf-Nonius DIP2020 diVractometer using graphite-monochromated Mo-Ka radiation (l = 0.71069 Å). Images were processed using the DENZO and SCALEPACK suite of programs.8 Data were corrected for Lorentz and polarisation eVects and a partial absorption correction applied by multiframe scaling of the image-plate data using equivalent reflections. The systematic absences in the data (h00, h odd; 0k0, k odd; 00l, l odd) indicated the space group to be P212121. 2030 Unique reflections were measured of which 1721 were observed with I > 3s(I). Full experimental information is given in Table 1. The structure was solved using direct methods (SIR92) 9 and all non-hydrogen atoms located.Framework hydrogen atoms were subsequently located in Fourier-diVerence maps and the hydrogen atoms of the diamine placed geometrically after each cycle of refinement. Full-matrix least-squares refinement on F of 153 parameters (atomic coordinates and anisotropic thermal parameters of non-hydrogen atoms, atomic coordinates only of hydroxyl hydrogen atoms) was carried out using the program CRYSTALS.10 A Chebychev 3-term polynomial weighting scheme was applied.The final residual electron densities were 20.789 and 0.671 e Å23. The crystal was found to be a racemic2148 J. Chem. Soc., Dalton Trans., 1999, 2147–2149 twin with twin ratio ca. 50%. Selected bond lengths and angles are given in Table 2. CCDC reference number 186/1474. See http://www.rsc.org/suppdata/dt/1999/2147/ for crystallographic files in .cif format. Discussion The structure consists of one-dimensional polymeric cobalt hydrogenphosphate anions of formula [Co(HPO4)2]22 running parallel to the a axis.The Co21 ions are tetrahedrally coordinated by four O atoms, which is consistent with the deepblue colour of the compound. The Co–O bond lengths (average 1.952 Å) are similar to those observed in other cobalt phosphates, for example, in [H3N(CH2)2NH3]0.5[Co(PO4)], Co–Oav 1.95 Å.11 The structure contains two crystallographically distinct HPO4 22 ions. One of the P–O distances of each PO4 tetrahedron is significantly longer than the other three (P(1)–O(1), Fig. 1 Powder X-ray diVraction pattern of a finely ground sample of the compound (Philips PW1700 diVractometer, graphite-monochromated Cu-Ka radiation). Fig. 2 View of one polymeric anion of the compound along the vector [011], showing zigzag chains of four-membered rings built from CoO4 and HP(1)O4 tetrahedra linked to pendant HP(2)O4 groups. Intra-chain hydrogen bonds are shown as dotted lines. Key: black circles, Co; grey circles, P; large white circles, O; small white circles, H.Drawing package ATOMS.12 1.565(3) and P(2)–O(5), 1.584(3) Å), suggesting that these O atoms are protonated. The presence of hydroxyl groups was confirmed by the observation of peaks in Fourier-diVerence maps close to O(1) and O(5) corresponding to the H atom positions. The CoO4 and HP(1)O4 units are linked alternately to form a zigzag “backbone” constructed from edge-sharing fourmembered rings of tetrahedra (Fig. 2). The HP(2)O4 group is bonded to these chains through only one bridging oxygen, O(6), to form “pendant” groups.In addition to the hydroxyl group, the pendant phosphorus carries two terminal oxygen atoms with P–O distances suYciently short to suggest the presence of some degree of multiple bonding (P(2)–O(7) and P(2)–O(8), 1.521(3) Å). The hydroxyl groups of the pendant HP(2)O4 units form intra-chain hydrogen bonds to bridging oxygen atoms of the backbone (O(5) ? ? ? O(2) = 2.654(4) Å) (Fig. 2) whilst the hydroxyl groups of the backbone HP(1)O4 units form interchain hydrogen bonds to P]] O oxygens of the pendant HP(2)O4 units (O(1) ? ? ? O(8) = 2.455(4) Å) (Fig. 3). In order to balance the charge of the polymeric anion, the organic counterion must be diprotonated. Each NH3 group forms three hydrogen bonds to O atoms of the anions (N ? ? ? O distances in the range 2.790(5) to 2.963(4) Å), thus forming a 3-dimensional network of hydrogen bonds between chains. Although this compound is the first reported example of a transition-metal phosphate containing this type of tetrahedronbased chain, similar one-dimensional structures have been observed previously in the two aluminophosphates [C10N2H9]- [Al(PO4)(H2PO4)] 13 and [H3N(CH2)2NH3][Al(PO4)(HPO4)].14 However, the chain packing and hydrogen-bonding schemes in the three materials are very diVerent, there being no direct interchain hydrogen bonding in either of the aluminophosphates.Although the present compound contains the same organic amine as the layered cobalt phosphate [H3N(CH2)3NH3]0.5- [Co(PO4)]?0.5H2O,5 there is no apparent structural relationship between the two materials.In contrast to the present compound, the layered material was prepared under aqueous conditions, illustrating the important role played by the solvent in directing framework formation in solvothermal syntheses. Fig. 3 View of the compound along the a axis showing the packing of [Co(HPO4)2]22 chains and charge-balancing [H3N(CH2)3NH3]21 cations.Inter-chain and amine–chain hydrogen bonds are shown as dotted lines. Hydrogen atoms have been omitted for clarity. Key: large black circles, Co; large grey circles, P; white circles, O; small grey circles, N, small black circles, C.J. Chem. Soc., Dalton Trans., 1999, 2147–2149 2149 One possible route to the synthesis of two- and threedimensional open-framework phases is the use of lowdimensional metal-phosphate precursors which contain structural elements present in the desired higher-dimensional framework. Examples of syntheses of novel aluminophosphate Table 1 Crystallographic data for [C3N2H12][Co(HPO4)2] Molecular formula Formula weight T/K Crystal system Space group a/Å b/Å c/Å U/Å3 Z m/mm21 Unique data Observed data with I > 3s(I) Merging R (%) R (%) Rw (%) C3H14CoN2O8P2 327.03 150 Orthorhombic P212121 5.210(1) 12.693(1) 15.518(1) 1026.1 4 2.01 2030 1721 4.50 3.24 3.70 Table 2 Selected bond lengths (Å) and angles (8) Co(1)–O(2) Co(1)–O(3) Co(1)–O(4) Co(1)–O(6) P(1)–O(1) P(1)–O(2) P(1)–O(3) P(1)–O(4) O(1)–H(1) O(2)–Co(1)–O(3) O(2)–Co(1)–O(4) O(3)–Co(1)–O(4) O(2)–Co(1)–O(6) O(3)–Co(1)–O(6) O(4)–Co(1)–O(6) O(1)–P(1)–O(2) O(1)–P(1)–O(3) O(2)–P(1)–O(3) O(1)–P(1)–O(4) O(2)–P(1)–O(4) O(3)–P(1)–O(4) N(1)–C(1)–C(2) C(1)–C(2)–C(3) 1.980(3) 1.945(2) 1.950(3) 1.933(3) 1.565(3) 1.537(3) 1.519(3) 1.523(3) 1.03(6) 108.7(1) 117.6(1) 109.0(1) 101.3(1) 112.6(1) 107.5(1) 105.8(2) 108.5(2) 111.7(1) 107.6(2) 111.4(2) 111.5(2) 110.2(3) 112.6(3) P(2)–O(5) P(2)–O(6) P(2)–O(7) P(2)–O(8) N(1)–C(1) N(2)–C(3) C(1)–C(2) C(2)–C(3) O(5)–H(2) O(5)–P(2)–O(6) O(5)–P(2)–O(7) O(6)–P(2)–O(7) O(5)–P(2)–O(8) O(6)–P(2)–O(8) O(7)–P(2)–O(8) Co(1)–O(2)–P(1) Co(1)–O(3)–P(1) Co(1)–O(4)–P(1) Co(1)–O(6)–P(2) P(1)–O(1)–H(1) P(2)–O(5)–H(2) C(2)–C(3)–N(2) 1.584(3) 1.510(3) 1.521(3) 1.521(3) 1.495(5) 1.492(5) 1.519(5) 1.508(6) 0.82(6) 110.1(2) 104.5(2) 112.7(2) 107.5(2) 110.2(2) 111.6(2) 127.4(2) 129.0(1) 126.7(2) 140.2(2) 113(3) 114(4) 111.5(3) frameworks by this method have previously been reported. For example the unidimensional material [C5H9NH3]5[Al3(PO4)4- (HPO4)] undergoes conversion into the layered phase [C5H9- NH3]2[Al2(PO4)2(HPO4)] on thermal treatment at 473K.15 The unidimensional cobalt hydrogenphosphate reported in this work may have potential utility in this role because the chain of edge-sharing four-membered rings which forms the “backbone” of the structure occurs as a structural element in many zeolite frameworks, e.g.gismondine and chabazite. Loss of the pendant phosphate groups and cross-linking of the chains might therefore result in formation of a 3-dimensional framework material. Work is in progress to study the eVects of thermal treatment on the compound. Acknowledgements A. R. C. would like to thank the Engineering and Physical Sciences Research Council for a studentship. References 1 S.Natarajan, J.-C. P. Gabrial and A. K. Cheetham, Chem. Commun., 1996, 1415. 2 V. Soghomonian, Q. Chen, R. C. Haushalter, J. Zubieta, C. J. O’Connor and Y.-S. Lee, Chem. 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