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Inorganica Chimica Acta 360 (2007) 710–714

Note

Template synthesis, structure and magnetic property of a newopen-framework manganese borophosphate:

(C4N2H12)Mn[B2P3O12(OH)]

Min Li a,b, Dongpo Xie a, Jiazhong Chang b, Hengzhen Shi a,*

a Department of Chemistry, Zhoukou Normal University, Zhoukou 466001, Henan Province, PR Chinab Analytical Testing Centre, Zhoukou Normal University, Zhoukou 466001, Henan Province, PR China

Received 2 May 2006; received in revised form 28 July 2006; accepted 3 August 2006Available online 23 August 2006

Abstract

A new manganese borophosphate compound, (C4N2H12)Mn[B2P3O12(OH)], has been hydrothermally synthesized, and structurallydetermined by single crystal X-ray diffractions. The crystal structure of the compound is characterized by corner-sharing BO4 andPO4 groups, leading to 1-D infinite chains built from alterative tetrahedra with a sequence of two corner-sharing borate tetrahedra,whose remaining corners are shared with two loop branching phosphate groups followed by a phosphate unit, which is interconnectedby MnO6 octahedral groups to construct a three-dimensional open-framework topology with unidimensional channels, which are occu-pied by diprotonated piperazinium ions. Magnetic measurement reveals an antiferromagnetic interaction system. Other characterizationsby elemental analysis, IR and thermal analyses are also discussed.� 2006 Published by Elsevier B.V.

Keywords: Boron; Phosphorus; Borophosphate; Crystal structure; Magnetic properties

1. Introduction

Template synthesis of microporous solids utilizing host–guest relationships remains an open challenge. Such a mate-rial is of interest for its potential application in performing asion exchangers, molecular sieves, catalyts, etc. [1–3]. A vari-ety of open-framework compounds with different structureshave been synthesized in the presence of template moleculesacting as structure-directing agents, such as aluminosilicate[4], titanosilicate [5], aluminophosphate [6], gallophosphate[7], and beryllium [8], zinc [9], cobalt [10], nickel [11], iron[12], vanadium [13] and molybdenum phosphate [14]. Thecurrent interest in the preparation of borophosphate com-pounds with open-framework structures derives from phys-iochemical properties and structural diversities. Today,numerous borophosphates and their crystal structures have

0020-1693/$ - see front matter � 2006 Published by Elsevier B.V.

doi:10.1016/j.ica.2006.08.010

* Corresponding author. Tel.: +86 394 8592279; fax: +86 394 8593141.E-mail address: hzshi@zknu.edu.cn (H. Shi).

already been reported [15]. Sevov reported the first zeolite-like borophosphate, CoB2P3O12OH Æ C2H10N2, with an infi-nite framework [16]. Kniep firstly reported transition metalborophosphates, MIMII(H2O)2[BP2O8] Æ H2O (MI = Na,K;MII = Mg,Mn,Fe, Co,Ni,Zn), which contain 61 helicesfrom the tetrahedral ribbon [BP2O8]n [17], and then proposeda first approach to borophosphates structural chemistry [18].The structural chemistry of borophosphates with the anioniccomponents composed of BO3 (BO4) and PO4 groups as wellas metal coordination in tetragonal bipyramides, squarebipyramides and octahedral moieties extends from isolatedspecies, oligomers, rings, chains, layers to three-dimensionalopen-frameworks. By using organic molecules template con-trolled linking of these basic building blocks has also led tosome novel borophosphates [16,19]. Nevertheless, amongthe reported compounds only three notable manganeseborophosphates, MIMn(H2O)2[BP2O8] Æ H2O [17], Mn-(C2H10N2)[B2P3O12(OH)] [15i] and [NH4]4[Mn9B2(OH)2-(HPO4)4(PO4)6] [20], are successfully synthesized, and

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M. Li et al. / Inorganica Chimica Acta 360 (2007) 710–714 711

display an open-framework structure. Manganese borophos-phate MIMn(H2O)2[BP2O8] Æ H2O contains a chiral octahe-dral–tetrahedral framework, related to the CZP topology.The crystal structure of Mn(C2H10N2)[B2P3O12(OH)] con-sists of tetrahedral layers built from BO4 and PO4 groupsvia sharing corner interconnected by distorted octahedraMnO6, resulting in a three-dimensional structure with chan-nels. Its framework of the third manganese borophosphate[NH4]4[Mn9B2(OH)2(HPO4)4(PO4)6] consists of anionicmanganese-phosphate layers, [Mn9(OH)2(HPO4)4(PO4)6]10�,which are pillared by BO4 groups forming a 3-D open frame-work with 2-D 8-MR channels.

In this paper by employing hydrothermal conditions andusing piperazine as the templating agent a new manganeseborophosphate, (C4N2H12)Mn[B2P3O12(OH)], is prepared.Its structure contains 1-D infinite loop-branched boro-phosphate chains, which are interconnected by MnO6

octahedral groups to construct a three-dimensional open-framework topology with unidimensional channels. Mag-netic measurement reveals an antiferromagnetic interactionsystem.

2. Experimental

2.1. Characterization

The IR spectrum was recorded on a Bruker Vertex 70FTIR plus spectrometer in the KBr matrix in the rangeof 400–4000 cm�1. The elemental analysis results wereobtained with an Elementar Analysensysteme GmbHinstrument. The thermogravimetry and differential thermalanalyses were performed using a DT-30 Shimadzu thermalanalyzer under an air flow of 100 mL/min with a heatingrate of 3 �C/min from room temperature to 1000 �C. Themagnetic data were obtained from 1.8 to 300 K in anapplied magnetic field of 2.0 kG on a Quantum DesignMPMS-XL SQUID magnetometer.

2.2. Synthesis

MnCl2 Æ 4H2O, H3BO3, phosphoric acid (85 wt%), piper-azine hexahydrate, H2C2O4 Æ 2H2O and distilled water weremixed in a molar ratio of 1.33:4:2:1:1.33:37. The mixturewas sealed in Teflon-lined stainless steel autoclaves andheated at 170 �C for 8 days under autogenous pressure.The resulting pure phase as platelike crystals was obtainedby filtration, washed with distilled water and acetone, anddried at an ambient temperature, giving 13% yields basedon Mn. The X-ray powder diffraction (XRD) data werecollected on a X-ray diffractometer with Cu Ka radiation(k = 1.54178 A). The powder XRD pattern is in agreementwith the simulated XRD pattern based on single-crystalstructural data, proving the phase purity of the as-synthe-sized product as shown in Fig. 1. The elemental analysis:the contents of N, C and H were 5.95, 10.55 and2.89 wt%, respectively (calc.: N, 6.00; C, 10.29 and2.79 wt%).

2.3. X-ray crystallography

The data for the crystals 0.20 mm · 0.17 mm · 0.17 mmwere collected on a Rigaku AXIS-IV imaging plate areadetector with graphite monochromated Mo Ka radiation(k = 0.71073 A). The data were collected at a temperatureof 291(2) K to a maximum 2h value of 51�. Of the 2322reflections that were collected, 690 reflections were unique(Rint = 0.0444). The structure was solved by direct methodsand expanded using Fourier techniques. The non-hydrogenatoms were refined anisotropically. The final cycle of thefull-matrix least squares refinement on F2 was based on690 observed reflections as well as 143 variable parametersand converged. All calculations were performed using theSHELXL-97 crystallographic software package [21]. Thenon-hydrogen atoms were refined anisotropically. Thestructure details, atomic coordinates and equivalent isotro-pic displacement parameters as well as selected bondlengths and angles are listed in Tables 1 and 2, respectively.The deposited number is CCDC 602463.

3. Results and discussion

The crystal structure of the title compound is similar to(C4N2H12)M[B2P3O12(OH)] (M = Co, Zn) [19], Na5-[B2P3O13] [22] and Rb3[B2P3O11(OH)2] [23], and is wellordered. In the crystal structure, 13 H atoms are locatedin difference Fourier maps. Of them 12 H atoms belongto the diprotonated piperazinium ions, while the other oneis attached to O9 in the phosphorus–oxygen polyhedron

Table 1Crystal data and structure refinement

Empirical formula C4H13N2MnB2P3O13

Formula weight 466.63Temperature (K) 291(2)Wavelength (A) 0.71073Crystal system orthorhombicSpace group Ima2Unit cell dimensions

a (A) 12.599(3)b (A) 9.5174(19)c (A) 11.585(2)a (�) 90b (�) 90c (�) 90

Volume (A3) 1389.1(5)Z 4Calculated density (g/cm3) 2.231Absorption coefficient (mm�1) 1.376F(000) 940Crystal size (mm) 0.20 · 0.17 · 0.17Index ranges �146 h6 10, �96 k6 11,

�116 l 6 14Collected/unique [Rint] 2322/690 [0.0444]Data/restraints/parameters 690/2/143Goodness-of-fit on F2 1.086Final R indices [I > 2r(I)] R1 = 0.0317; wR2 = 0.0778R indices (all data) R1 = 0.0319 wR2 = 0.0779Largest difference in peak and hole (e A�3) 0.586 and �0.431

Table 2Selected bond lengths (A) and angles (�)

Mn(1)–O(2)#1 2.080(6) O(6)#3–Mn(1)–O(1) 87.12(12)Mn(1)–O(8)#2 2.124(6) O(2)–P(1)–O(1) 114.6(4)Mn(1)–O(6) 2.139(4) O(2)–P(1)–O(3)#3 109.7(2)Mn(1)–O(6)#3 2.139(4) O(1)–P(1)–O(3)#3 108.6(2)Mn(1)–O(1) 2.298(6) O(2)–P(1)–O(3) 109.7(2)P(1)–O(2) 1.483(7) O(1)–P(1)–O(3) 108.6(2)P(1)–O(1) 1.530(6) O(3)#3–P(1)–O(3) 105.1(3)P(1)–O(3)#3 1.569(4) O(6)#4–P(2)–O(6) 118.9(4)P(1)–O(3) 1.569(4) O(6)#4–P(2)–O(5) 105.4(2)P(2)–O(6)#4 1.498(4) O(6)–P(2)–O(5) 109.5(2)P(2)–O(6) 1.498(4) O(6)#4–P(2)–O(5)#4 109.5(2)P(2)–O(5) 1.592(4) O(6)–P(2)–O(5)#4 105.4(2)P(2)–O(5)#4 1.592(4) O(5)–P(2)–O(5)#4 107.9(3)P(3)–O(8) 1.489(6) O(8)–P(3)–O(7) 112.3(2)P(3)–O(7) 1.553(4) O(8)–P(3)–O(7)#3 112.3(2)P(3)–O(7)#3 1.553(4) O(7)–P(3)–O(7)#3 107.0(3)P(3)–O(9) 1.566(7) O(8)–P(3)–O(9) 111.1(4)B(1)–O(5) 1.451(8) O(7)–P(3)–O(9) 106.9(2)B(1)–O(4) 1.474(7) O(7)#3–P(3)–O(9) 106.9(2)B(1)–O(3) 1.477(7) O(5)–B(1)–O(4) 111.2(5)B(1)–O(7) 1.490(7) O(5)–B(1)–O(3) 111.5(4)O(2)–Mn(1)#5 2.080(6) O(4)–B(1)–O(3) 109.3(5)O(4)–B(1)#3 1.474(7) O(5)–B(1)–O(7) 105.0(4)O(8)–Mn(1)#6 2.124(6) O(4)–B(1)–O(7) 110.3(5)

O(2)#1–Mn(1)–O(8)#2 98.8(3) O(3)–B(1)–O(7) 109.4(5)O(2)#1–Mn(1)–O(6) 93.90(11) P(1)–O(1)–Mn(1) 117.6(3)O(8)#2–Mn(1)–O(6) 91.82(11) P(1)–O(2)–Mn(1)#5 169.5(5)O(2)#1–Mn(1)–O(6)#3 93.90(11) B(1)–O(3)–P(1) 120.7(4)O(8)#2–Mn(1)–O(6)#3 91.82(11) B(1)#3–O(4)–B(1) 111.7(6)O(6)–Mn(1)–O(6)#3 170.8(2) B(1)–O(5)–P(2) 127.1(3)O(2)#1–Mn(1)–O(1) 96.7(3) P(2)–O(6)–Mn(1) 136.7(2)O(8)#2–Mn(1)–O(1) 164.5(2) B(1)–O(7)–P(3) 125.2(3)O(6)–Mn(1)–O(1) 87.12(12) P(3)–O(8)–Mn(1)#6 141.0(4)

Symmetry transformations used to generate equivalent atoms: #1�x � 1/2,�y + 5/2, z + 1/2; #2 �x � 1/2, �y + 3/2, z + 1/2; #3 �x � 1/2, y, z; #4�x, �y + 2, z; #5 �x � 1/2, �y + 5/2, z � 1/2; #6. �x � 1/2, �y + 3/2,z � 1/2; #7 �x, �y + 1, z.

Fig. 2. ORTEP plot of the title compound.

712 M. Li et al. / Inorganica Chimica Acta 360 (2007) 710–714

[PO3(OH)], confirmed by the IR spectra band at 1621 and3410 cm�1. Fig. 2 depicts the asymmetric unit, which con-sists of two B atoms, three P atoms and one Mn atom aswell as nine O atoms. The B and P atom sites take on tet-rahedral coordination. The B–O distances and O–B–Oangles range from 1.451 to 1.490 A and from 105.0 to111.5� for BO4 group. The interatomic distances and O–P–O angles in the PO4 tetrahedra range from 1.483 to1.592 A and from 105.4� to 118.9�, respectively. The Mnatom may also be looked upon as a severe distortion octa-hedral coordination with one additional longer distance tol3-O(4) (2.569 A). The results of the bond valence sum(BVS) analysis imply that manganese atoms are presentas Mn2+, and the octahedral coordination configurationseems to be more reasonable than the pyramidal configura-tion, compared with (C4N2H12)M[B2P3O12(OH)] (M = Co,Zn) [19], because the +1.88 oxidation state of the manga-nese atom in the pyramidal configuration and the 2.00value in the octahedral coordination configuration aregiven by the BVS calculation [24].

The isotypic compound contains loop-branched infinitechains running along the a direction. The 1-D infinite chainis built from the alterative tetrahedra with a sequence oftwo corner-sharing borate tetrahedra, whose remainingcorners are shared with two loop branching phosphategroups followed by a phosphate unit as shown in Fig. 3.The Mn atoms located in the middle between the boro-phosphate anionic chains, being connected with four oxy-gen atoms from the PO4 tetrahedra and two BO4 groupsin the adjacent different chains, give rise to an open frame-

Fig. 3. A view of the one-dimensional chain structure of BO4 and PO4

group linkage.

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M. Li et al. / Inorganica Chimica Acta 360 (2007) 710–714 713

work conformation with one-dimensional channels asgiven in Fig. 4. The channels in the crystal structure areformed from eight polyhedra sharing vertexes in the fol-lowing sequence: –MnO6–PO4–MnO6–PO4–BO4–PO4–BO4–PO4–. The channels are positioned by diprotonatedpiperazinium ions for charge neutrality. Further cross-link-ing occurs via hydrogen-bond interactions between nitro-gen atoms and [B2P3O12(OH)]4� chains as well as stronginterchain hydrogen bonds [N� � �O(5) 2.835(7) A];[N� � �O(1) 2.836(6) A] and [O(9)� � �O(4) 2.601(8) A].

It is noted that a 1-D infinite loop-branched borophos-phate chain is observed in compound (C4N2H12)-Mn[B2P3O12(OH)]. The MnO6 octahedral groups bondedwith adjacent chains together lead to a solid with unidi-mensional pores similar to those in aluminosilicate zeolitesand in certain detemplated aluminophosphates, which haveproven to be useful in guest exchange and catalysis [25–27].

The IR spectrum at 3410 and 1621 cm�1 is attributed toa characteristic O–H deformation vibration, bands at 1428and 3089 cm�1 due to N–H groups. The stretching modesof the –CH2– groups of the piperazinium are in the2548–2980 cm�1 domain, whereas their bending modesrange from 1194 to 1396 cm�1. The intense and complexbands at 545–1120 cm�1 correspond to the modes of thePO4 and BO4 tetrahedra. The bands below 500 cm�1 canbe ascribed to the Mn–O vibrations [28].

Thermal analysis curve shows two stage processesaccompanied by two obvious endothermic/exothermic

Fig. 4. A one-dimensional chain structure linkage of BO4 and PO4 withMnO6 group.

peaks. The first weight loss of 17.17% is observed between470 and 675 �C and attributed to the removal of theorganic amine (calc. 18.88%). A gradual loss of mass6.37% at the second stage in the range from 675 to832 �C is attributed to the dehydration of hydroxyl andloss of oxygen due to framework condensation. The resultof thermal analysis is in agreement with the single crystalX-ray diffraction result.

The variation of the molar magnetic susceptibility as afunction of temperature measured from 300 down to1.8 K with an applied field of 2.0 kG is shown inFig. 5. At higher temperature the sample is paramagneticand obeys the Currie–Weiss law vM = C/(T � h) withCurrie–Weiss constants of C = 4.44 cm�3 K/mol andh = �19.72 K, respectively. The effective magneticmoment at 300 K is 5.92 lB, which is identical with theexpected value (5.9–6.0 lB) for octahedral coordinationof Mn2+ ion. Between 50 and 3 K the molar magneticsusceptibility increases indicating a weak ferromagneticcomponent to the magnetic interactions. The appearanceof a round peak at about 3 K in the vM versus T curveindicates a typical low-dimensional antiferromagneticsystem.

4. Conclusions

This paper demonstrates the template-controlled synthe-sis and structural characterization of the compound,(C4N2H12)Mn[B2P3O12(OH)]. Structural analyses expoundthat the compound contains a crystallographically 1-D infi-nite loop-branched borophosphate chain and the inter-chain H-bonding interactions. The wide frameworkvariation with the structurally known zeolite or molecularsieve, once again, exemplifies the versatility of the boro-phosphate structures.

Acknowledgments

We thank the Natural Science Foundation of HenanProvince and the Key Discipline Foundation of Zhoukou

714 M. Li et al. / Inorganica Chimica Acta 360 (2007) 710–714

Normal University for the financial support of thisresearch.

Appendix A. Supplementary data

Atomic coordinates, equivalent isotropic displacementparameters and thermal analysis figure are shown in sup-plementary data. Supplementary data associated with thisarticle can be found, in the online version, atdoi:10.1016/j.ica.2006.08.010.

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