Supramolecular Isomerism and Isomorphism in the Structures of 1,4-Butanebisphosphonic Acid and Its Organic Ammonium Salts Amir H. Mahmoudkhani*,‡ and Vratislav Langer§
CRYSTAL GROWTH & DESIGN 2002 VOL. 2, NO. 1 21-25
Department of Chemistry, Go¨ teborg University, SE-412 96 Go¨ teborg, Sweden, and Department of Inorganic Environmental Chemistry, Chalmers University of Technology, SE-412 96 Go¨ teborg, Sweden Received September 19, 2001;
Revised Manuscript Received October 30, 2001
ABSTRACT: 1,4-Butanebisphosphonic acid crystallizes as two concomitant polymorphs, a triclinic phase (1a) and an orthorhombic phase (1b), both comprising pillared-layered hydrogen-bonded networks and exhibiting supramolecular isomerism. Two organic salts of this acid with aniline (2) and p-phenylazoaniline (3) were synthesized and characterized by X-ray diffraction analysis. Compounds 2 and 3 show supramolecular isomorphism with pillaredbilayered frameworks. Our results demonstrate the potential use of bisphosphonic acids for the synthesis of new solid materials. Introduction The use of phosphonic acid in the context of supramolecular chemistry and crystal engineering has been limited mainly to metal phosphonates, important organic-inorganic hybrid materials.1 Developments in the chemistry of metal phosphonates, due to their variety of properties such as a host for intercalation, catalysis, sorption, and ion-exchange, resulted from tunable structures by appropriate choice of organic phosphorus acids. Studies1 have shown that monophosphonic acids, RPO3H2, react with metal ions to form predominately layered compounds, in which the inorganic frameworks are separated by the organic moieties. On the other hand, multifunctional phosphonic acids, such as bisphosphonic acids, aminophosphonic acids, and carboxyphosphonic acid, have proven to be good candidates for the preparation of pillared-layered structures and formation of microporous solids.2 The idea of using bisphosphonic acids, H2O3P-R-PO3H2, has been first introduced by Dines et al.2a for incorporating microporous voids within the layers of metal phosphonates. The rich chemistry of organic phosphorus acids apparently plays a key role in the development of crystal engineering strategies for the synthesis of two- and three-dimensional frameworks based on metal phosphonates. It has been shown that another interesting property of organic phosphorus acids, namely, the potential to form extended hydrogen-bonded assemblies, could be utilized for preparation of one-, two-, and threedimensional networks.3 We believe understanding of structure correlations between organic and inorganic salts of phosphonic acids gives an insight into structural possibilities and facilitates the design of new solid materials. Indeed, structural elucidation of metal phosphonates often suffers from the lack of crystalline material suitable for single crystal or powder diffraction studies. Therefore, results from the structural studies * Corresponding author: A. H. Mahmoudkhani, Telephone: +4631-7722861, Fax: +46-31-7722853, E-mail:
[email protected]. ‡ Go ¨ teborg University. § Chalmers University of Technology. E-mail:
[email protected].
of soluble organic or inorganic salts of phosphonic acids are of principle value in the field.4 Phenylphosphonic acid and its organic ammonium salts4f exhibit layered structures that are structurally relevant to their inorganic analogues, metal phenylphosphonates. Here we report the structure of two polymorphs of 1,4-butanebisphosphonic acid (1a,b) and its organic salts with aniline (2) and p-phenylazoaniline (3). We demonstrate that bisphosphonic acids are remarkably versatile building blocks for assembling extended structures of organic salts as found for their inorganic salts. Experimental Procedures 1,4-Butanebisphosphonic acid (1) was purchased from ACROS. ORGANICS. 1,6-Hexamethylenediamine was donated by DuPont. Other chemicals were obtained from Aldrich and Fluka and were used without any further purification. For compound 1, careful examination of the crystals obtained from methanol-water (70:30) solution using an optical microscope revealed the presence of plate (1a) and needle (1b) shaped crystals in the ratio of 2:3. Both types were of diffraction quality. Recrystallization from the solution in water gave only aggregates of needle crystals. Our attempt to crystallize plate crystals in pure form has not been successful yet. Compounds 2 and 3 have been obtained by mixing 1 and organic amines (with the ratio of 1:2) dissolved separately in the ethanol. After the solvent was heated to the boiling point for about 5 min, the solutions were set aside to crystallize, exposed to air. In a nominal experiment, 20 mg (∼0.092 mmol) of 1 dissolved in 5 mL of ethanol was mixed with 36 mg (∼0.183 mmol) of p-phenylazoaniline dissolved in 5 mL of ethanol.
Crystal Structure Determination All data were collected using a Siemens SMART CCD diffractometer with MoKR radiation (λ ) 0.71073 Å, graphite monochromator) equipped with a LT-2A lowtemperature device. The structures were solved by direct methods and refined by full-matrix least squares on all F2 data using SHELXTL.5a The non-H atoms were refined anisotropically, while hydrogen atoms are refined isotropically. The crystallographic and refinement data for compounds 1-3 are summarized in Table 1.
10.1021/cg015553f CCC: $22.00 © 2002 American Chemical Society Published on Web 12/07/2001
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Mahmoudkhani and Langer
Table 1. Crystallographic and Refinement Data empirical formula crystal system space group a [Å] b [Å] c [Å] R [°] β [°] γ [°] V [Å3] Z, F(calc) [g‚cm-3] T [K] µ [mm-1] refl. collec./unique refl. R (int) R1/wR2 for obs. dataa R1/wR2 for all dataa a
1a
1b
2
3
C4H12O6P2 triclinic P-1 (no. 2) 5.8745(3) 8.9512(5) 9.6833(5) 63.469(1) 88.364(1) 88.702(1) 455.35(4) 2, 1.591 297(2) 0.469 5926/2724 0.031 0.039/0.097 0.055/0.106
C4H12O6P2 orthorhombic Pca21 (no. 29) 10.7794(3) 5.7405(2) 14.2480(4) 90 90 90 881.65(5) 4, 1.643 183(2) 0.485 9576/3097 0.050 0.063/0.169 0.076/0.180
C16H26N2O6P2 monoclinic P2/c (no. 13) 18.7245(6) 6.7899(3) 8.0295(3) 90 91.394(1) 90 1020.55(7) 2, 1.316 163(2) 0.246 7436/3067 0.055 0.060/0.144 0.097/0.173
C28H34N6O6P2 monoclinic C2/c (no. 15) 65.3761(8) 6.3533(1) 7.4586(5) 90 90.291(1) 90 3097.92(7) 4, 1.313 299(2) 0.208 9494/2277 0.028 0.036/0.095 0.047/0.102
R1 ) ∑||Fo| - |Fc||/∑|Fo|, wR2 ) {∑[w(Fo2 - Fc2)2]/∑w(Fo2)2}1/2. Table 2. The Geometry of Hydrogen Bonds [Å,°]a
notation [a] [b] [c] [d] [a] [b] [c] [d] [a] [b] [c] [d] [a] [b] [c] [d]
D-H‚‚‚A 1a O11-H11‚‚‚O23i O12-H12‚‚‚O13ii O21-H21‚‚‚O23iii O22-H22‚‚‚O13 1b O11-H11‚‚‚O23i O12-H12‚‚‚O23ii O21-H21‚‚‚O13iii O22-H22‚‚‚O13iv 2 N1-H111‚‚‚O1 N1-H112‚‚‚O1i N1-H113‚‚‚O2ii O3-H3‚‚‚O2iii 3 N1-H1A‚‚‚O3i N1-H1B‚‚‚O2 N1-H1C‚‚‚O3ii O1-H1‚‚‚O2i C1-H1B‚‚‚O1iii C12-H12‚‚‚O3
d(D-H) d(H‚‚‚A) d(D‚‚‚A) ∠(DHA) 0.80(2) 0.80(2) 0.77 (2) 0.78(2)
1.81(2) 1.77(2) 1.84(2) 1.80(2)
2.601(2) 2.570(2) 2.608(2) 2.570(2)
169(4) 175(4) 174(3) 173(4)
0.84 0.84 0.84 0.84
2.11 1.77 1.81 2.18
2.620(6) 2.549(5) 2.549(5) 2.623(6)
119 154 145 113
0.86(2) 0.87(2) 0.90(2) 0.79(2)
1.83(2) 1.91(2) 1.81(2) 1.79(2)
2.688(2) 2.779(3) 2.710(3) 2.574(2)
175(3) 174(4) 173(3) 170(4)
0.89 0.89 0.89 0.79(2) 0.97 0.93
1.80 1.85 1.81 1.78(2) 2.58 2.47
2.679 (2) 2.734(2) 2.692(2) 2.563(2) 3.257(3) 3.400(3)
171 170 173 169(3) 127 174
Figure 1. Representation of the pillared-layered structure of 1a. The (C-)H atoms are omitted for clarity.
a Symmetry transformations used to generate equivalent atoms: 1a: (i) x - 2, y, z; (ii) -x, -y + 2, -z; (iii) -x + 1, -y + 1, -z + 1; 1b: (i) -x + 3/2, y, z + 1/2; (ii) -x + 3/2, y + 1, z + 1/2; (iii) -x + 1, -y - 1, z - 1/2; (iv) -x + 1, -y, z - 1/2; 2: (i) x, -y + 1, z - 1/2; (ii) x, -y, z - 1/2; (iii) x, -y, z + 1/2; 3: (i) x, -y + 1, z - 1/2; (ii) x, y + 1, z; (iii) x, -y, z + 1/2.
More details could be found in respective CIF file for each compound. Molecular graphics were obtained using Diamond.5b Results and Discussion 1,4-Butanebisphosphonic acid (1) exhibits polymorphism, and our examination revealed the presence of two concomitant polymorphs. Polymorph 1a with a plate shape crystallized in the triclinic system with space group P-1 (no. 2), while polymorph 1b with needle shape crystallizes in the orthorhombic system with space group Pca21 (no. 29). It is possible to obtain polymorph 1b in pure form from water solution. Indeed, it has been the only form obtained as a residue of starting materials in the reaction of 1 with calcium, strontium, and barium ions in water as well. The asymmetric unit of 1a contains two independent molecules of 1. The arrangement of molecules is shown
Figure 2. The two-dimensional hydrogen-bonding network in the structure of 1a. Only (PO3H2) groups are shown for clarity. Hydrogen-bond notations are given in Table 2.
in Figure 1. The compound exhibits a pillared-layered structure, in which two-dimensional hydrogen-bonded networks are covalently pillared by alkyl chains. The hydrogen-bonding network in a layer is shown in Figure 2. The phosphonic acid groups are acting as both donors and acceptors of hydrogen bonds. Four independent hydrogen bonds are forming supramolecular motifs: dimers, chains, and rings. The first-level graph-set descriptors9 are D1,1(2); C1,1(9); C2,2(18); and
Supramolecular Isomerism of 1,4-Butanebisphosphonic Acid
Figure 3. Representation of the pillared-layered structure of 1b. The (C-)H atoms are omitted for clarity.
Crystal Growth & Design, Vol. 2, No. 1, 2002 23
Figure 5. The two-dimensional hydrogen-bonding network in the structure of 1b. Only (PO3H2) groups with s.o.f. of 0.83 are shown for clarity. Hydrogen-bond notations are given in Table 2.
Figure 4. The (PO3H2) groups are disordered in two positions. The minor parts are shown in yellow.
R2,2(8), while the second-level descriptors are assigned as D2,3(7); D3,3(19); C3,3(17); C3,3(27); C2,2(8); R4,4(26); and C2,2(18). Hence, dimerizations through {b} and {c} hydrogen bonds forming R2,2(8) ring motifs results in first-level descriptors, while apparently larger R4,6(20) ring motifs formed by {d, a, c, d, a and c} or {a, b, d, a, b and d} hydrogen bonds could be assigned as higher-level descriptors. Polymorph 1b also exhibits a pillared-layered structure, although the arrangement of molecules is different than for polymorph 1a, and the layers are aligned parallel to the ab plane (see Figure 3). Both phosphonic acid groups were disordered over two positions with site occupancies of 0.83 and 0.17 as shown in Figure 4. This behavior seems to be an intrinsic (static) disorder since it has been observed within a wide range of temperatures from 183 to 297 K and for crystals obtained at different conditions. The H-bonding network in the structure of 1b is shown in Figure 5 in which only dominant (PO3H2) groups (s.o.f. of 0.83) have been taken into account; however, the minor parts (s.o.f. of 0.17) also build a similar pattern. Both phosphonic acid groups are involved in hydrogen bonds and act as both donor and acceptor. The first-level graph-set descriptors include only the C1,1(9) motif that comprises head-to-tail linked molecules. Nevertheless, the second-level descriptors are a set of C2,2(18); C1,2(6); and C2,2(8) motifs. However, R3,4(14) ring motifs, as seen in Figure 5, belong to fourth-level graph-set descriptors, and they are formed
Figure 6. The pillared-bilayered structure of 2. The (C-)H atoms are omitted for clarity.
by linking four phosphonic acid groups through hydrogen bonds. The crystal structures of three homologues [H2O3P(CH2)n-PO3H2, n ) 1, 2, and 3] of 1 have been reported earlier,7 all having extended hydrogen-bonding network, but only homologues n ) 1 and 2 showing the same supramolecular organization as 1a and 1b, and no polymorphism has been reported.7a A comparison of the hydrogen-bonding network for 1a and 1b reveals that they are not only concomitant polymorphs, but they also show supramolecular isomerism. These characteristics are of interest and challenging in the field of crystal engineering.8a,b In the crystal structure of anilinium butanebisphosphonate 2, the bisphosphonate dianion lies on the center of symmetry, and thus the asymmetric unit includes a half of dianion and one anilinium cation, the cation-toanion ratio being 2:1. The supramolecular organization comprises hydrogen-bonded bilayers aligned parallel to the bc plane, in which two layers are pillared by the alkyl chain of bisphosphonate dianion (see Figure 6).
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Crystal Growth & Design, Vol. 2, No. 1, 2002
Figure 7. The hydrogen-bonding network of a layer for 2. Only (NH3) and (PO3H) groups are shown. Hydrogen-bond notations are given in Table 2.
Mahmoudkhani and Langer
Figure 9. The hydrogen-bonding network for 3. Hydrogenbond notations are given in Table 2.
D2,2(10); C1,1(4); C1,1(9); and C2,2(18) motifs, while second level descriptors are assigned as C1,2(4); C2,2(6); C2,2(11); C2,3(13); C3,3(15); C3,3(25); and R4,4(22). Furthermore, a R3,3(10) ring motif is formed by the {b, a and d} hydrogen bonds, and a R3,5(12) ring motif is a result of {c, d, b, c and a} hydrogen bonds. Hence, one can conclude that 2 and 3 are supramolecular isomorphs. The crystal structure of three organic diammonium salts of ethanebisphosphonic acid have been reported,3b,c among them only the salt with piperazine3c has a pillared-layered structure. Conclusion
Figure 8. The pillared-bilayered structure of 3. The (C-)H atoms are not shown for clarity.
The bilayers are stacked above each other along the a-axis () 18.7245(6) Å). The two-dimensional network in a layer formed by four independent hydrogen bonds is shown in Figure 7. The first-level graph-set descriptors includes D1,1(2); D2,2(10); C1,1(4); C1,1(9); and C2,2(18) motifs, while second-level descriptors are assigned as C1,2(4); C2,2(6); C2,2(11); C2,3(13); C3,3(15); C3,3(25); and R4,4(22). Furthermore, a R3,3(10) ring motif is formed by the {c, b and d} hydrogen bonds and a R3,5(12) ring motif is a result of {a, d, c, a and b} hydrogen bonds. In the crystal structure of p-phenylazoanilinium butanebisphosphonate (3), the bisphosphonate dianion also lies on the center of symmetry, and thus the asymmetric unit includes a half of the dianion and one anilinium cation, the cation-to-anion ratio being 2:1. The supramolecular organization comprises hydrogen-bonded bilayers aligned parallel to the bc plane (see Figure 8), and thus it is similar to 2. These bilayers are stacked on each other along the a axis () 65.3761(8) Å). The two-dimensional network in a layer formed by four independent hydrogen bonds is shown in Figure 9. The first level graph-set descriptors includes D1,1(2);
The crystal structures of butanebisphosphonic acid (1a,b) and its salts with aniline (2) and p-phenylazoaniline (3) are reported here. We have demonstrated the potential use of bisphosphonic acids, including butanebisphosphonic acid, for assembling extended supramolecular hydrogen-bonded networks, the mean O‚‚‚O distances of about 2.58 Å with the mean ∠DHA of 173° and the mean N‚‚‚O distances of 2.71 Å with ∠DHA angles of about 173°. The existence of supramolecular isomerism (1a and 1b) and isomorphism (2 and 3) are interesting and should be taken into account for crystal engineering of materials comprising phosphonates. We anticipate the strategy of using phosphonateammonium synthons leads to a new class of organic solids, in which strength and directionality of the (P-)O-H‚‚‚O-P and N-H‚‚‚O-P hydrogen bonds are used to assemble novel supramolecular arrays. They are structurally related to metal bisphosphonates, where the inorganic framework is replaced with a hydrogenbonding network. Thus, they can be used as models to design new metal phosphonates and explore the variety of structural possibilities, e.g., multilayered metal phosphonates. Supporting Information Available: X-ray crystallographic information files (CIF) are available for compounds 1a,b-3. This material is available free of charge via the Internet at http://pubs.acs.org.
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Supramolecular Isomerism of 1,4-Butanebisphosphonic Acid Chemistry; Alberti, G., Bein, T., Eds.; Pergamon: New York, 1996; Vol. 7, pp 151-187; Clearfield, A. Prog. Inorg. Chem. 1998, 47, 371. (2) (a) Dines, M. B.; Cooksey, R. E.; Griffith, P. C.; Lane, R. H. Inorg. Chem. 1983, 22, 1003. (b) Yang, H. C.; Aoki, K.; Hong, H.-G.; Sackett, D. D.; Arendt, M. F.; Yau, S.-L.; Bell, C. M.; Mallouk, T. E. J. Am. Chem. Soc. 1993, 115, 11855. (c) Penicaud, V.; Massiot, D.; Gelbard, G.; Odobel, F.; Bujoli, B. J. Mol. Struct. 1998, 470, 31. (d) Serre, C.; Ferey, G. Inorg. Chem. 1999, 38, 5370. (e) Serpaggi, S.; Ferey, G. J. Mater. Chem. 1998, 8, 2749. (f) Distler, A.; Lohse, D. L.; Sevov, S. C. J. Chem. Soc., Dalton Trans. 1999, 1805. (g) Poojary, D. M.; Zhang, B.; Clearfield, A. J. Am. Chem. Soc. 1997, 119, 12550. (h) Poojary, D. M.; Zhang, B.; Bellinghausen, P.; Clearfield, A. Inorg. Chem. 1996, 35, 4942. (i) Alberti, G.; Vivani, R.; Murcia Mascaros, S. J. Mol. Struct. 1998, 470, 81. (j) Alberti, G.; Marcia-Mascaros, S.; Vivani, R. J. Am. Chem. Soc. 1998, 120, 9291. (3) (a) Ferguson, G.; Glidewell, C.; Gregson, R. M.; Meehan, P. R. Acta Crystallogr. Sec. B 1998, 54, 129. (b) Glidewell, C.; Ferguson, G.; Lough, A. J. Acta Crystallogr. Sec. C. 2000, 56, 855. (c) Wheatley, P. S.; Lough, A. J.; Ferguson, G.; Burchell, C. J.; Glidewell, C. Acta Crystallogr. Sec. B 2001, 57, 95. (d) Sharma, C. V. K.; Clearfield, A. J. Am. Chem. Soc. 2000, 122, 4394. (e) Sharma, C. V. K.; Hessheimer, A. J.; Clearfield, A. Polyhedron 2001, 20, 2095. (4) (a) Mahmoudkhani, A. H.; Langer, V. Solid State Sci. 2001, 3, 519. (b) Mahmoudkhani, A. H.; Langer, V. Acta Crystallogr. Sec. E 2001, 57, i19. (c) Mahmoudkhani, A. H.; Langer, V. Phosphorus, Sulfur, Silicon 2001, in press. (d) Mahmoudkhani, A. H.; Langer, V. Acta Crystallogr. Sec. E 2001, 57, o866. (e) Mahmoudkhani, A. H.; Langer, V. J. Mol. Struct. 2001, in press. (f) Mahmoudkhani, A. H.; Langer, V. J. Mol.
Crystal Growth & Design, Vol. 2, No. 1, 2002 25
(5)
(6)
(7)
(8) (9)
Struct. 2001, accepted for publication. (g) Mahmoudkhani, A. H.; Langer, V.; Smrcok, L. Solid State Sci. 2001, submitted. (a) Sheldrick, G. M. SHELXTL (Version 6.10), Structure Determination Programs, Bruker AXS Inc., Madison, Wisconsin, USA, 2001. (b) Brandenburg, K. Diamond: Visual Crystal Structure Information System (Version 2.1d), Crystal Impact GbR, Bonn, Germany, 2000. (a) Etter, M. C. Acc. Chem. Res. 1990, 23, 120. (b) Etter, M. C.; Bernstein, J.; MacDonald, J. C. Acta Crystallogr. Sec. B 1990, 46, 252. (c) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N. Angew. Chem., Int. Ed. Engl. 1995, 34, 1555. (d) Grell, J.; Bernstein, J.; Tinhofer, G. Acta Crystallogr. Sec. B 1999, 55, 1030. (e) Motherwell, D. S.; Shields, G. P.; Allen, F. H. Acta Crystallogr. Sec. B 1999, 55, 1044. (a) Peterson, S. W.; Gebert, E.; Reis, A. H., Jr.; Druyan, M. E.; Mason, G. W.; Peppard, D. F. J. Phys. Chem. 1977, 81, 466. (b) Gebert, E.; Reis, A. H., Jr.; Druyan, M. E.; Peterson, S. W.; Mason, G. W.; Peppard, D. F. J. Phys. Chem. 1977, 81, 471. (a) Bernstein, J.; Davey, R. J.; Henck, J.-O. Angew. Chem., Int. Ed. Engl. 1999, 38, 3440. (b) Moulton, B.; Zaworotko, M. J. Chem. Rev. 2001, 101, 1629. Assignment of the H-bond descriptors are based on the graph-set theory and described in refs 6a-d. The full sets of the first- and second-level descriptors for 1-3 have been obtained using the program PLUTO according to ref 6e. For convenience, the notation Xa,d(n) has also been adopted in this paper, in which X is the pattern descriptor, a is number of acceptors, d is number of donors, and n is the number of atoms comprising the pattern.
CG015553F
