New in Situ Condensation Reaction of Amino Diphosphonic Acids: A

New in Situ Condensation Reaction of Amino Diphosphonic Acids: A Series of Bicyclic Phosphonate Derivatives and Three Novel Water Clusters Shuo-ping Chen,† Guang-xi Huang,† Ming Li,‡ Ling-ling Pan,† Yi-xuan Yuan,† and Liang-jie Yuan*,†

CRYSTAL GROWTH & DESIGN 2008 VOL. 8, NO. 8 2824–2833

College of Chemistry and Molecular Sciences, Wuhan UniVersity, Wuhan 430072, P. R. China, and College of Chemical Engineering, Wuhan UniVersity of Science and Engineering, Wuhan 430072, P. R. China ReceiVed NoVember 11, 2007; ReVised Manuscript ReceiVed May 14, 2008

ABSTRACT: A new in situ low-temperature, low-pressure hydrothermal condensation reaction of amino diphosphonic acids affords a series of phosphonate derivatives with bicyclic structures. By using such bicyclic phosphonate ligands, three compounds, namely, [Zn2(L1)(phen)4] · 12H2O (1), [Ni(Im)6]3(L2)2(ImH)2 · 24H2O (2), and [Cu2(L3)(phen)2(H2O)2] · 9H2O (3) (phen ) 1,10-phenanthroline, Im ) imidazole, L1H4, L2H4, and L3H4 represent different bicyclic phosphonate derivatives), have been synthesized and structurally characterized by single-crystal X-ray crystallography. Novel water clusters with different structural motifs, such as T4(3)5(0)A0 water tape in 1, TU water tape in 2, and L5(4)5(5)15(14) water layer in 3, are discussed in detail. The coordination mode of the metal ion and the use of the appropriate second ligand, which would influence the reaction and structures of the final products are also discussed. Introduction As an important part of phosphorus chemistry, organophosphonates and their metal compounds have attracted considerable attention in the past two decades due to their novel structures and potential functions.1 Therefore, the design and synthesis of such novel organophosphonate ligands is not only an important task but also a challenge to chemists, and new synthetic methods for preparing organophosphonates need to be explored. Water is of fundamental importance for human beings, and it also plays an important role in many chemical and biological systems.2 It is necessary to study the existent state and kinetic characteristics of water. In fact, water is the congeries of a great deal of water molecules that connect to each other by hydrogen bonds. The key to understanding the behavior of water is the precise structural data of various hydrogen-bonded water networks. A water cluster is the simple model of water in bulk.3 Studying water clusters may be the key to understanding the unusual properties of water and may explain many natural phenomena.4 Moreover, some of the water clusters are important in several biological processes.5 Water clusters with different topologies can be obtained via crystal engineering, that is, designing and constructing some channels or cavities with different shapes and sizes.6 Therefore, the structure of the host complex plays a crucial role in constructing the water cluster. Some metal-organophosphonate compounds can be good hosts for the formation of water clusters. First, such compounds can provide not only different kinds of channels and cavities, but also strong hydrogen bonds with water molecules to stabilize the water clusters. Second, the topological model of the water cluster can be modified by changing of organophosphonate ligand in the host. For example, inthemetal-organophosphonatecompound(enH2)3[Zn(AEDP)2] · 6H2O (AEDPH4 ) 1-aminoethylidenediphosphonic acid, enH2 ) ethylenediamine) in our previous work,7 the Zn(AEDP)26* Corresponding author. E-mail: [email protected]. Tel: +86-27-8721-8264. Fax: +86-27-6875-4067. † Wuhan University. ‡ Wuhan University of Science and Engineering.

Figure 1. Structure (a) and coordination environment (b) of L14- in 1.

anions and enH2+ cations interconnect through various hydrogen bonds to form the host with extended one-dimensional (1D) channels, in which an ice-like T4(2)6(2) water tape penetrates to serve as the guest. It is observed that an organophosphonate ligand with more phosphorus oxygen atoms may have better hydrophilic properties and form more hydrogen bonds with water molecules. It is well-known that in situ hydrothermal reactions often show unusual reaction models and afford compounds with novel structures.8 Whereas in situ hydrothermal reactions reported previously always displayed certain specific examples, recently, we observed a new in situ hydrothermal reaction by which amino diphosphonic acids with the formula of RC(NH2)(PO3H2)2 (R ) -Ph, -Et, -CH2C6H5) can condense to form a

10.1021/cg7011149 CCC: $40.75  2008 American Chemical Society Published on Web 07/17/2008

Condensation Reaction of Amino Diphosphonic Acids

Crystal Growth & Design, Vol. 8, No. 8, 2008 2825

Scheme 1. Chemical Structures of APhMDPH4, APDPH4, APhEDPH4, L1H4, L2H4, and L3H4, and the Transformation between Them

kind of bicyclic phosphonate derivative. This reaction represents a common phenomenon for amino diphosphonic acids, because it has been discovered in several low-temperature, low-pressure hydrothermal systems: (1) reaction of 1-amino-1-phenylmethane1,1-diphosphonic acid (APhMDPH4) and ZnO with 1,10phenanthroline (phen); (2) reaction of 1-aminopropane-1,1diphosphonic acid (APDPH4) and Ni(OH)2 with imidazole (Im); (3) reaction of 1-amino-2-phenylethane-1,1-diphosphonic acid (APhEDPH4) and CuO with phen. These reaction systems afford three phosphonate compounds: [Zn2(L1)(phen)4] · 12H2O (1), [Ni(Im)6]3(L2)2(ImH)2 · 24H2O (2), and [Cu2(L3)(phen)2(H2O)2] · 9H2O (3). In compounds 1-3, the three amino diphosphonic acid precursors (APhMDPH4, APDPH4, and APhEDPH4) all undergo a condensation process, generating three bicyclic phosphonates L1H4, L2H4, and L3H4, respectively (see Scheme 1). L1H4, L2H4, and L3H4 are new chemical substances not reported before. Only one similar compound (L0H4) was reported by R. Kurze.9 L0H4 is the homologue of L2H4 (the ethyl in L2H4 is substituted by methyl in L0H4), which can be prepared by treating P4O6 with AcOH and urea in MeCN (see Scheme 1).

With the help of single-crystal X-ray crystallography, the accurate structures of such bicyclic phosphonates are obtained for the first time. There are ten phosphorus oxygen atoms in such bicyclic phosphonate molecules, which implies that these kinds of phosphonates may be excellent precursors for constructing novel water cluster structures. Compounds 1-3 all contain interesting water clusters with dissimilar 1D or twodimensional (2D) structural motifs. Herein, we report the experimental process of the in situ condensation reaction, as well as the characterization and crystal structures of the bicyclic phosphonates and water clusters. Experimental Section Materials and Measurements. The three amino diphosphonic acid precursors (APhMDPH4, APDPH4, and APhEDPH4) were prepared following the procedures in U.S. Patent 4,239,695.10 Other starting materials were purchased from commercial sources and used without further purification (ZnO, Ni(OH)2, and CuO were purchased from Sinopharm Chemical Reagent Co., Ltd.; phen and Im were purchased from Alfa Aesar Chemical Reagent Co., Ltd.). The elemental analysis data (C, H, N) were obtained with a Perkin-Elmer 240B elemental

2826 Crystal Growth & Design, Vol. 8, No. 8, 2008

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Table 1. Crystallographic Data and Structure Refinement Parameters for Compounds 1-3

empirical formula formula weight crystal system space group a, Å b, Å c, Å R, deg β, deg γ, deg V, Å3 Z Dc, g · cm-3 µ, mm-1 F(000) crystal size, mm3 θ range for data collection, deg reflns collected/unique refinement method completeness to θ ) 28.00° data/restraints/params GOF on F2 final R indices [I > 2σ(I)]a R indices (all data)a largest diff. peak and hole, e · Å-3 a

1

2

3

C62H67N9O22P4Zn2 1544.87 monoclinic C2/c 25.38(2) 10.696(7) 25.55(2) 90 110.225(9) 90 6509(7) 4 1.576 0.922 3192 0.61 × 0.30 × 0.11 2.09-28.00 20705/7783 [R(int) ) 0.0347] full-matrix least-squares on F2 99.1% 7783/18/495 1.066 R1 ) 0.0490, wR2 ) 0.1480 R1 ) 0.0652, wR2 ) 0.1579 0.781 and -0.672

C72H152N42O44P8Ni3 2734.25 triclinic P1j 12.8261(8) 16.646(2) 17.189(2) 64.065(2) 79.105(2) 73.958(2) 3161.9(4) 1 1.436 0.638 1434 0.43 × 0.40 × 0.36 2.28-28.00 21148/14686 [R(int) ) 0.0157] full-matrix least-squares on F2 96.3% 14686/60/905 1.084 R1 ) 0.0532, wR2 ) 0.1698 R1 ) 0.0676, wR2 ) 0.1799 0.967 and -0.681

C40H53N5O21P4Cu2 1190.83 monoclinic P2(1)/c 10.8584(6) 18.939(2) 24.305(2) 90 92.812(2) 90 4992.3(5) 4 1.584 1.064 2456 0.48 × 0.18 × 0.17 2.16-28.00 33183/11945 [R(int) ) 0.0280] full-matrix least-squares on F2 99.1% 11945/24/741 1.201 R1 ) 0.0534, wR2 ) 0.1719 R1 ) 0.0730, wR2 ) 0.1826 1.306 and -1.120

R1 ) [∑(|F0| - |F0|) /∑|F0|; wR2 ) [∑[w(|F0|2 - |F0|2)2]/∑[w(|F0|2)2]1/2; w ) 1/[σ2|F0|2 + (xp)2 + yp], where p ) [|F0|2 + 2|F0|2]/3.

Figure 2. (a) Hydrogen bonding motif within the 1D T4(3)5(0)A0 water tape and (b) the space filling view of the T4(3)5(0)A0 water tape and its connections to the [Zn2(L1)(phen)4] molecule. [Zn2(L1)(phen)4] molecule is depicted in green. analyzer. IR spectra were recorded as KBr pellets at a range of 400-4000 cm-1 on a Nicolet 5700 FT-IR spectrometer with a spectral resolution of 4.00 cm-1. Thermogravimetric analysis (TGA) was carried out with a NETZSCH STA 449C at a heating rate of 10 K/min in air.

Low-Temperature, Low-Pressure Hydrothermal Method. Single crystals of compounds 1-4 were obtained by a low-temperature, lowpressure hydrothermal method. In this method, we employ a small plastic centrifuge tube to replace an expensive Teflon reactor, which



Figure 3. (a) Structure of L24- in 2 and (b) 3D porous supramolecule network constructed by L24- anions, [Ni(Im)6]2+ cations, and ImH+ cations. is widely used in normal hydrothermal reactions. The reaction temperature is set at 80 °C so that we can prevent the vaporization of water just by sealing with thread tape. In general, reactants will deposit in the bottom of the tube at first, and then single crystals of final product will grow from these powders over several days. The crystal growth can be observed at any moment. This method is simple, cheap, and convenient for single-crystal growth. Synthesis of [Zn2(L1)(phen)4] · 12H2O (1). APhMDPH4 (0.0667 g, 0.25 mmol), ZnO (0.0101 g, 0.125 mmol), phen (0.0466 g, 0.25 mmol), and distilled water (1 mL) were sealed in a small centrifuge tube and then heated at 80 °C for 3 days. Colorless crystals for single-crystal diffraction analysis were obtained. Yield: 80% (based on ZnO). Elemental Analysis: Found, %: C 48.17, H 4.35, N 8.19. Calcd for C62H67N9O22P4Zn2: C 48.20, H 4.37, N 8.16. Synthesis of [Ni(Im)6]3(L2)2(ImH)2 · 24H2O (2). APDPH4 (0.0274 g, 0.125 mmol), Ni(OH)2 (0.0116 g, 0.125 mmol), Im (0.0766 g, 1.125 mmol), and distilled water (1 mL) were sealed in a small centrifuge tube and then heated at 80 °C for 5 days. Blue crystals for singlecrystal diffraction analysis were obtained. Yield: 57% (based on Ni(OH)2). Elemental Analysis: Found, %: C 31.73, H 5.58, N 21.56. Calcd for C72H152N42O44P8Ni3: C 31.63, H 5.60, N 21.52. Synthesis of [Cu2(L3)(phen)2(H2O)2] · 9H2O (3). APhEDPH4 (0.0703 g, 0.25 mmol), CuO (0.0099 g, 0.125 mmol), phen (0.0248 g, 0.125 mmol), and distilled water (1 mL) were sealed in a small centrifuge tube and then heated at 80 °C for 3 days. Green crystals for singlecrystal diffraction analysis were obtained. Yield: 84% (based on CuO). Elemental Analysis: Found, %: C 40.37, H 4.51, N 5.86. Calcd for C40H53N5O21P4Cu2: C 40.34, H 4.49, N 5.88.

Single-Crystal X-ray Crystallography. Crystallographic measurements were obtained on a Bruker SMART CCD area-detector diffractometer. These structures were performed at room temperature using graphite monochromated Mo KR radiation (λ ) 0.710 73). The structures were analyzed by direct methods using the SHELXS-97 program.11 Non-hydrogen atoms were refined with anisotropic thermal parameters by full-matrix least-squares calculations on F2 using SHELXL-97. Hydrogen atoms were directly obtained from difference Fourier maps, and several DFIX commands were applied on hydrogen atoms in compounds 1-3. Crystallographic data and structural refinement parameters are listed in Table 1. Selected bond lengths (Å) and angles (deg) of the three compounds are listed in Table S8 of the Supporting Information. Hydrogen bond distances (Å) and angles (deg) are listed in Table 2 and Table S9 of the Supporting Information. Crystallographic data have been deposited with the Cambridge Crystallographic Centre as Supplementary Publication Nos. CCDC 646495 (1), 646496 (2), and 648992 (3). Copies of the data may be obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge CB21EZ, U.K. (fax (+44) (1223) 336033; e-mail for inquiry [email protected].).

Crystal Structures [Zn2(L1)(phen)4] · 12H2O (1). The asymmetric unit of 1 contains one zinc ion, a half of L14- anion, two phen ligands, and six water molecules (see Figure S1 in Supporting Information). The L1H4 molecule is completely deprotonated to serve


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Figure 4. (a) Hydrogen bonding motif within the 1D TU water tape and (b) the space filling view of the TU water tape and its connections to the host. The L24- anions, [Ni(Im)6]2+ cations, and ImH+ cations are highlighted in green.

as L14- anion in 1. As depicted in Figure 1, the structure of L14- can be described as the derivative of bicyclic [3.3.1]nonane: in L14-, four phosphor atoms (P1, P2, P1A, P2A) are connected by two phosphonic anhydride oxygen atoms (O4 and O4A) and two carbon atoms (C32 and C32A), generating a eightmembered ring; meanwhile a nitrogen atom (N5) bridges the carbon atoms in opposite sides (C32 and C32A), dividing the eight-membered ring into two six-membered rings. The bond lengths of the phosphonic anhydride group (P1-O4 ) 1.622(2) Å, P2-O4 ) 1.619(2) Å) and imino group (C32-N5 )1.495(3) Å) are in the range of normal P-O and C-N bonds.12 The eight-membered ring in L14- adopts a boat-like conformation, while the two six-membered rings are chair like (angles ∠P1-O4-P2 ) 123.98(12)°, ∠C32-N5-C32A ) 121.3(3)°, ∠O4-N5-O4A ) 66.49(5)°; torsion angles ∠P2-O4-P1-C32 ) 59.0(2)°, ∠P1-C32-N5-C32A ) 63.2(2)°). Therefore, the unitary conformation of L14- anion can be described as a rocking chair. It is observed that L24- in 2 and L34- in 3 both illustrate similar conformations to L14-. Therefore the rocking chair conformation may be the preferred one for such bicyclic phosphonates. In addition, the two phenyl rings of L14-are staggered with an angle of 30.41(8)°. The zinc center in 1 is octahedrally coordinated by two oxygen atoms from a chelated

L14- ion and four nitrogen atoms from two chelated phen ligands. Meanwhile, The L14- ion acts as a tetradentate ligand and bonds to two zinc ions, generating a [Zn2(L1)(phen)4] binuclear molecule. The Zn-O distances (2.053(2)-2.064(2) Å) are similar to other zinc-organophosphonate compounds.13 The lattice water molecules in compound 1 are self-assembled to generate an interesting T4(3)5(0)A0 water tape, which is shown in Figure 2. First, six water molecules (O1W, O2W, O3W, O4W, O5W, O6W) form a (H2O)6 cluster with a motif of bicyclo[2.1.1]hexane, that is, a five-membered water ring and a four-membered water ring are joined together by sharing three water molecules. Then water molecules in the neighboring (H2O)6 clusters are connected to each other via hydrogen bond O3W-H2W3 · · · O5W#3 (2.69(2) Å) with the rotation of 180°. Thus, a 1D infinite wavelike water tape along the b axis is built, which can be described as a T4(3)5(0)A0 water tape based on the nomenclature by L. Infantes et al.14 The O · · · O distances in this water tape are in the range of 2.69(2)-3.05(3) Å, with an average of 2.86 Å, which are close to that of liquid water (2.85 Å).15 Because the L14- anion is completely deprotonated, neighboring [Zn2(L1)(phen)4] binuclear units are unable to connect each other directly via hydrogen bonds. Therefore, the



Figure 5. Structure (a) and coordination environment (b) of L34- in 3.

T4(3)5(0)A0 water tape plays an important role in connecting adjacent [Zn2(L1)(phen)4] units: O2W, O5W, and O6W can form hydrogen bonds with the phosphonate group of L14- anion with O · · · O distances of 2.736(6)-2.95(2) Å. [Ni(Im)6]3(L2)2(ImH)2 · 24H2O (2). There are one L24- anion, one and a half [Ni(Im)6]2+ cations, one ImH+ cation, and 12 lattice water molecules in the asymmetric unit of compound 2 (see Figure S2 in Supporting Information). The L2H4 molecule also acts as L24- anion in 2. The main difference between L14and L24- is their side groups: there is a phenyl in L14-, while there is an ethyl in L24-. Moreover, the two ethyl groups of L24- are almost coplanar. The L24- in 2 is uncoordinated. Combined with strong hydrogen bonds between imidazole ligands and phosphonate groups, each [Ni(Im)6]2+ ion is linked to four L24- anions, and one L24- anion bonds to six [Ni(Im)6]2+ ions. Meanwhile, neighboring L24- anions are joined together to form a dimer via the bridging effect of a pair of ImH+ ions. Thus, a threedimensional (3D) porous supramolecular network is constructed (see Figure 3). As displayed in Figure 4, water molecules located in the interspaces of the 3D supramolecular network are interconnected to form a (H2O)24 knobby water tape. The structural motif for this water tape is so complex that we cannot define it appropriately but only designate it as TU water tape (U ) unique). The repeating unit of the water tape contains a (H2O)10 cluster and a (H2O)14 cluster. First, five water molecules (O2W, O3W, O4W, O5W, and O11W) are joined together to generate a (H2O)5 cluster with a motif of bicyclo[1.1.1]hexane, that is, two four-membered water rings are joined together by sharing three water molecules. The (H2O)5 water cluster is further connected to water molecules O12W and O1W, resulting in a (H2O)7 cluster (O12W-H2WC · · · O3W, 2.96(2) Å; O1WH1W1 · · · O2W, 3.045(9) Å; and O1W-H1W1 · · · O5W, 3.03(2) Å). Two neighboring (H2O)7 clusters are self-assembled to form the (H2O)14 cluster via symmetrical hydrogen bond O3W-

H2W3 · · · O3W#6 (3.19(2) Å). On the other hand, another six water molecules (two O8W, two O9W, and two O10W) are self-assembled to generate a cyclic water hexamer; then two water dimers (O6W, O7W) are connected to the cyclic water hexamer via hydrogen bond O6W-H2W6 · · · O8W (3.33(3) Å), generating the (H2O)10 cluster. Finally, neighboring (H2O)10 and (H2O)14 clusters are alternately connected by hydrogen bond O10W-H1WA · · · O11W (2.86(8) Å), resulting in a 1D infinite knobby water tape. Compared with the T4(3)5(0)A0 water tape in 1, the O · · · O distances among the TU water tape represent a broader range (2.55(2)-3.33(3) Å), and the average O · · · O distance of the TU water tape is 2.96 Å, which is larger than that of the T4(3)5(0)A0 water tape. The water tape is connected to the host via various Ow-H · · · O and N-H · · · Ow hydrogen bonds to L24- anions and [Ni(Im)6]2+ ions. [Cu2(L3)(phen)2(H2O)2] · 9H2O (3). The asymmetric unit of 3 is composed of one molecule of [Cu2(L3)(phen)2(H2O)2] and nine water molecules as solvent of crystallization (see Figure S3 in Supporting Information). The L3H4 in 3 also serves as L34- anion. The L34- can be regarded as the homologue of L14in which phenyl is substituted with benzyl. Different from compound 1, each copper center in compound 3 displays a square-pyramidal geometry, which is chelated by a L34- ion and a phen ligand, and one coordinated water molecule is located at the vertex of the square pyramid. The L34- ion acts as a tetradentate ligand and bonds to two copper ions, generating the [Cu2(L3)(phen)2(H2O)2] binuclear molecule. Interestingly, each phenyl ring is approximatively parallel to a phen ligand, while the two phenyl rings of L34- are staggered with an angle of 35.5(3)°. Distances between Cu2+ ion and coordinated water molecule range from 2.266(4) to 2.328(4) Å, while other Cu-O distances range from 1.919(3) to 1.943(2) Å, similar to other copper-organophosphonate compounds16 (see Figure 5). Similar to the [Zn2(L1)(phen)4] molecules in 1, the [Cu2(L3)(phen)2(H2O)2] molecules are also unable to interconnect directly via hydrogen bonds, whereas the hydrogen-bonded


Chen et al.

Figure 6. (a) Hydrogen bonding motif within the 2D L5(4)5(5)15(14) water layer and (b) the space filling view of the L5(4)5(5)15(14) water layer and its connections to the [Cu2(L3)(phen)2] molecule. [Cu2(L3)(phen)2] molecule is depicted in green.

assembly of coordinated water molecules and lattice water molecules results in the formation of a 2D L5(4)5(5)15(14) water layer. As shown in Figure 6, eight water molecules are self-assembled to form a (H2O)8 cluster with a motif of bicyclo[3.3.0]octane, that is, two five-membered water rings are joined together sharing two water molecules. Such (H2O)8 clusters are extended to form a 1D zigzag water chain along the a axis via the bridging effect of water molecule O3W (O6W-H1W6 · · · O3W#5 ) 2.709(7) Å, O1W-H1W1 · · · O3W ) 2.85(2) Å). Then water dimers are formed by O2W and O9W, which further links the adjacent 1D water chains, generating a 2D water layer along the ab plane (O9W-H2W9 · · · O2W#8 ) 3.16(2)Å;O5W-H2W5 · · · O9W#8)3.04(2)Å;O2W-H2W2 · · · O1W#6 ) 3.32(2) Å). This water layer contains 15-membered water rings with large apertures of ca. 5 × 8 Å2. Such a formation of two-dimensional water morphology made up of discrete water molecules with the large aperture is rare in the supramolecular chemistry.17 The [Cu2(L3)(phen)2(H2O)] mol-

ecules are occupied in the apertures of the water rings and connected to the 2D water layer via Cu-Ow coordination bonds and hydrogen bonds between water molecules and L34- anion. The O · · · O distances in this water layer are in the range of 2.709(7)-3.32(2) Å, with an average of 2.92 Å, slightly lager than that of 1. Discussion Influence of the Second Ligand. It is observed that the second ligand plays an important role in this reaction and strongly affects the structure of the final product. The reaction systems of the condensation reaction can be divided into two parts based on different second ligands: (1) The second ligand is a chelated ligand with large size, such as phen. In the final products, like compounds 1 and 3, the bicyclic phosphonate anions act as tetradentate ligands. Each anion can chelate two metal ions to form a binuclear complex. (2) The second ligand



Table 2. Hydrogen Bonds for Water Clusters in Compounds 1-3 donor-H · · · acceptor

d(donor · · · acceptor)

∠(donor-H · · · acceptor)

T4(3)5(0)A0 Water Tape in Compound 1a O(6W)-H(2W6) · · · O(2) O(6W)-H(1W6) · · · O(4W)#1 O(5W)-H(2W5) · · · O(3)#2 O(5W)-H(1W5) · · · O(3W) O(4W)-H(2W4) · · · O(5W)#1 O(3W)-H(2W3) · · · O(6W) O(3W)-H(1W3) · · · O(5W)#3 O(2W)-H(2W2) · · · O(3)#2 O(2W)-H(1W2) · · · O(3W) O(1W)-H(2W1) · · · O(2W) O(1W)-H(1W1) · · · O(4W)#1

2.95(2) 2.86(3) 2.766(8) 3.05(3) 2.87(3) 2.78(2) 2.69(2) 2.736(6) 2.77(2) 2.95(2) 2.92(4)

180(11) 179(11) 140(11) 149(12) 152(24) 118(15) 158(22) 121(7) 123(8) 147(9) 155(12)

TU Water Tape in Compound 2b O(1W)-H(1W1) · · · O(2W) O(1W)-H(1W1) · · · O(5W) O(1W)-H(2W1) · · · O(10)#3 O(2W)-H(1W2) · · · O(5W) O(2W)-H(2W2) · · · O(3W) O(3W)-H(1W3) · · · O(4) O(3W)-H(2W3) · · · O(4)#6 O(3W)-H(2W3) · · · O(3W)#6 O(4W)-H(1W4) · · · O(3W) O(4W)-H(2W4) · · · O(5W) O(5W)-H(2W5) · · · O(9)#3 O(6W)-H(1W6) · · · O(1) O(6W)-H(2W6) · · · O(8W) O(7W)-H(1W7) · · · O(6W) O(7W)-H(2W7) · · · O(7)#3 O(8W)-H(1W8) · · · O(9W) O(8W)-H(2W8) · · · O(10W) O(9W)-H(1W9) · · · O(10W)#7 O(9W)-H(2W9) · · · O(10)#2 O(10W)-H(1WA) · · · O(11W) O(11W)-H(1WB) · · · O(2W) O(11W)-H(2WB) · · · O(4W) O(12W)-H(1WC) · · · O(2)#6 O(12W)-H(2WC) · · · O(3W)

3.045(9) 3.03(2) 2.760(5) 3.11(2) 2.617(8) 2.690(6) 2.672(6) 3.19(2) 3.01(2) 2.55(2) 2.653(9) 2.88(2) 3.33(3) 2.99(2) 2.88(2) 2.95(4) 2.67(6) 3.25(7) 2.825(7) 2.86(8) 2.99(2) 3.16(2) 2.694(8) 2.96(2)

136(7) 122(6) 150(7) 164(7) 147(7) 111(15) 138(16) 125(14) 179(14) 173(13) 154(15) 125(14) 172(17) 176(18) 178(20) 180(36) 121(32) 177(10) 132(9) 122(53) 137(14) 180(18) 143(11) 149(12)

L5(4)5(5)15(14) Water Layer in Compound 3c O(12)-H(12A) · · · O(4W)#2 O(13)-H(13A) · · · O(5W)#3 O(12)-H(12B) · · · O(6W)#4 O(13)-H(13B) · · · O(6W)#4 O(1W)-H(1W1) · · · O(3W) O(1W)-H(2W1) · · · O(8W) O(2W)-H(1W2) · · · O(5)#5 O(2W)-H(2W2) · · · O(1W)#6 O(3W)-H(1W3) · · · O(8)#7 O(3W)-H(2W3) · · · O(5)#7 O(4W)-H(1W4) · · · O(5W)#6 O(4W)-H(2W4) · · · O(7W) O(5W)-H(1W5) · · · O(1W) O(5W)-H(2W5) · · · O(9W)#8 O(6W)-H(1W6) · · · O(3W)#5 O(6W)-H(2W6) · · · O(3)#9 O(7W)-H(1W7) · · · O(8W)#6 O(7W)-H(2W7) · · · O(10)#1 O(8W)-H(1W8) · · · O(8)#7 O(8W)-H(2W8) · · · O(2)#10 O(9W)-H(1W9) · · · O(2)#10 O(9W)-H(2W9) · · · O(2W)#8

2.767(8) 2.84(2) 2.996(8) 2.812(8) 2.85(2) 2.70(2) 2.853(7) 3.32(2) 2.842(6) 2.754(8) 3.08(2) 2.76(2) 2.70(2) 3.04(2) 2.709(7) 2.958(6) 2.838(8) 2.750(8) 2.717(5) 2.658(5) 2.98(2) 3.16(2)

180(8) 141(8) 169(8) 162(8) 179(14) 146(12) 153(10) 178(12) 125(8) 144(8) 178(9) 180(11) 146(12) 159(13) 154(7) 173(7) 179(9) 171(8) 152(7) 165(7) 179(15) 179(13)

a Symmetry transformations used to generate equivalent atoms: #1 -x + 1, y, -z + 1/2; #2 -x + 1/2, y + 1/2, -z + 1/2; #3 -x + 1/2, y - 1/2, -z + 1/2. b Symmetry transformations used to generate equivalent atoms: #2 -x + 1, -y + 1, -z + 1; #3 x + 1, y, z; #6 -x + 1, -y + 1, -z + 2; #7 -x + 2, -y + 1, -z + 1. c Symmetry transformations used to generate equivalent atoms: #1 -x + 2, -y + 1, -z + 1; #2 x, -y + 1/2, z + 1/2; #3 -x + 1, -y, -z + 1; #4 x + 1, y - 1, z; #5 -x + 1, -y + 1, -z + 1; #6 -x + 1, y + 1/2, -z + 1/2; #7 x, -y + 1/2, z - 1/2; #8 -x + 1, y - 1/2, -z + 1/2; #9 x - 1, y + 1, z; #10 x - 1, -y + 1/2, z - 1/2.

is a small ligand such as Im. In the final products, like compound 2, all the nickel ions form [Ni(Im)6]2+ cations, and the bicyclic phosphonates are uncoordinated. However, if the amino diphosphonic acid coordinates to the nickel ion, the reaction may not

Figure 7. Structure (a) and coordination environment (b) of APhEDP4in 4.

occur. For example, hydrothermal reaction of APhEDPH4, Ni(OH)2, and Im afforded another compound, namely, [Ni2(Im)6(APhEDP)(H2O)] · 2H2O (4).18 In compound 4, the APhEDPH4 remains the original ligand: each APhEDP4- anion chelates two nickel ions, thereby generating a binuclear complex19 (see Figure 7, Scheme 1, and Figure S4 in Supporting Information). The structural types of the three compounds can also be divided into two parts due to different second ligands. Since the L14-, L24-, and L34- in corresponding compounds only act as proton acceptors, some proton donors should be introduced to help to construct the supramolecular structures. In compound 2, the [Ni(Im)6]2+ and ImH+ cations serve as the proton donors. Thus, L24- anions, together with [Ni(Im)6]2+ and ImH+ cations, form a stable 3D porous supramolecular network as the host. Meanwhile, water molecules located in the aperture of the host generate a TU water tape as the guest. Such a host/guest relationship is the typical model for most complexes that contain water clusters. However, in compounds 1 and 3, the coordinated phen ligand is unable to be a proton donor. Therefore, neither the [Zn2(L1)(phen)4] nor the [Cu2(L3)(phen)2(H2O)2] molecule can self-assemble to form the host via hydrogen bonds. Meanwhile, weak π-π stacking interactions existing among the [Zn2(L1)(phen)4] or [Cu2(L3)(phen)2(H2O)2] molecules cannot construct a stable supramolecular framework either. In this case, the water clusters serve as proton acceptors and connect the adjacent [Zn2(L1)(phen)4] or [Cu2(L3)(phen)2(H2O)2] molecules. In addition, the [Cu2(L3)(phen)2(H2O)2] can also link to the water


cluster via coordinated bonds. So different from compound 2, there is no obvious host/guest relationship between the water clusters and [Zn2(L1)(phen)4] or [Cu2(L3)(phen)2(H2O)2] molecules in compounds 1 and 3. Influence of the Coordination Mode of the Metal Ion. In compounds 1 and 3, different coordination modes of metal ions result in the formation of different water clusters. In 1, the Zn2+ ion is in a six-coordinated octahedral geometry, which is chelated by two phen ligands, whereas in 3, the copper center displays a square-pyramidal geometry, which is chelated by only one phen ligand, and one coordinated water molecule locates at the vertex of the square pyramid. Thus, compared with [Zn2(L1)(phen)4] in 1, [Cu2(L3)(phen)2(H2O)2] favors the extension of the water cluster with smaller steric hindrance. In addition, the coordinated water molecules in [Cu2(L3)(phen)2(H2O)2] also participate in constructing the water cluster. Therefore, the water molecules self-assemble to form a 1D tape in 1 and a 2D layer in 3. IR Spectra and TGA Figure S5 in Supporting Information shows the IR spectra of compounds 1-3. The broad peaks centered at 3415-3470 cm-1 reveal the existence of water molecules. The corresponding H-O-H (δHOH) bending vibration bands of the lattice free water molecules are located at 1630 cm-1. In compounds 1 and 3, a series of characteristic peaks in the range of 1425-1587 cm-1 are attributed to the phen ligand; while in compound 2, the stretching vibration at 1449-1542 cm-1 reveals the existence of Im ligands and ImH+ ions. It is observed that there are a series of strong peaks in the region of 1258-1070 cm-1, which can be attributed to the P-O stretching vibrations of such bicyclic phosphonate derivatives. The TGA data for compounds 1-3 are given in Figure S6 of Supporting Information. All three compounds are unstable in air. Compound 1 loses 12 lattice water molecules up to 222 °C. The observed weight loss (11.47%) is slightly smaller than the calculated value (13.98%). The dehydration product, the [Zn2(L1)(phen)4] molecule, is stable up to 290 °C, and then it starts decomposing. Compound 2 loses 24 lattice water molecules up to 120 °C with a weight loss of 15.19% (calcd 15.79%); after that, the framework is stable up to 250 °C, and then it starts decomposing. Compound 3 releases 11 water molecules up to 154 °C with a weight loss of 16.70% (calcd 16.62%). The decomposition of the L4- ions and phen ligands starts at 270 °C. Conclusion In summary, we have carried out an in situ condensation reaction of amino diphosphonic acids in three different systems and discussed the detailed structural characterization of the three compounds: [Zn2(L1)(phen)4] · 12H2O (1), [Ni(Im)6]3(L2)2(ImH)2 · 24H2O (2), and [Cu2(L3)(phen)2(H2O)2] · 9H2O (3). These bicyclic phosphonates are found to be excellent precursors for constructing different kinds of novel water clusters with different structural motifs, such as the T4(3)5(0)A0 water tape in 1, TU water tape in 2, and L5(4)5(5)15(14) water layer in 3. The coordination mode of the metal ion and the choice of the second ligand influence the reaction and the crystal structure of the final products. Current work is promoting further investigation of the rules and mechanism of this reaction and exploring more effective ways to design different kinds of water clusters based on bicyclic phosphonates.

Chen et al.

Acknowledgment. This work was financially supported by the National Natural Science Foundation of China (Grant No. 20671074). We are thankful to Zhong-Jing Li, Jiang-Feng Xiang, Prof. Feng Deng, and Prof. Zhang-Ping Chen for helpful discussions. Supporting Information Available: The ORTEP drawings of compounds 1-4 with thermal ellipsoids at the 30% probability level, IR spectra of compounds 1-3, TG diagrams of compounds 1-3, conceivable steps of the in situ reaction, selected bonds and angles for compounds 1-3, selected hydrogen bonds and angles for compound 2, and X-ray crystallographic information files (CIF) for compounds 1-4. This material is available free of charge via the Internet at http:// pubs.acs.org.

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Condensation Reaction of Amino Diphosphonic Acids 2006, E62, O3287. (13) Li, M.; Xiang, J. F.; Wu, S. M.; Chen, S. P.; Yuan, L. J.; Li, H.; He, H. J.; Sun, J. T. J. Mol. Struct. 2007, 840, 119. (14) Mascal, M.; Infantes, L.; Chisholm, J. Angew. Chem., Int. Ed. 2006, 45, 32. (15) Narten, A. H.; Thiessen, W. E.; Blum, L. Science 1982, 217, 1033. (16) (a) Ding, D. G.; Yin, M. C.; Lu, H. J.; Fan, Y. T.; Hou, H. W.; Wang, Y. T. J. Solid State Chem. 2006, 179, 747. (b) Wu, S. M.; Xiang, J. F.; Li, M.; He, H. J.; Li, H.; Yuan, L. J.; Sun, J. T. J. Coord. Chem. 2007, 60, 2273. (17) (a) Carballo, R.; Covelo, B.; Lodeiro, C.; Va´zquez-Lo´pez, E. M. CrystEngComm 2005, 7, 294. (b) Carballo, R.; Covelo, B.; FernańdezHermida, N.; Garcıá-Martıńez, E.; Lago, A. B.; Va´zquez, M.; Va´zquezLo´pez, E. M. Cryst. Growth Des. 2006, 6, 629. (18) Synthesis of 4: APhEDPH4 (0.0352 g, 0.125 mmol), Ni(OH)2 (0.0116 g, 0.125 mmol), Im (0.0596 g, 0.875 mol), and distilled water (1 mL)

Crystal Growth & Design, Vol. 8, No. 8, 2008 2833 were sealed in a small centrifuge tube and then heated at 80 °C for 20 days. Blue crystals for single-crystal diffraction analysis were obtained. Yield: 11% (based on Ni(OH)2). Elemental Analysis: Found, %: C 36.42, H 4.59, N 21.22. Calcd for C26H39N13O9P2Ni2: C 36.44, H 4.59, N 21.25. (19) Crystal data for 4 (C26H39N13O9P2Ni2): Mw ) 857.06, T ) 298 K, triclinic, space group P1j, a ) 8.6086(5) Å, b ) 14.0222(8) Å, c ) 16.3218(9) Å, R ) 107.026(2)°, β ) 93.350(2)°, γ ) 101.663(2)°, V ) 1830.4(12) Å3, Z ) 2, Dcalcd ) 1.555 g · cm-3, µ ) 1.183 mm-1, R1 ) 0.0431, wR2 ) 0.0962 (all data), goodness-of-fit on F2 ) 1.111. Crystallographic data have been deposited with the Cambridge Crystallographic Centre as Supplementary Publication No. CCDC 648749.

CG7011149

New in Situ Condensation Reaction of Amino Diphosphonic Acids: A

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