1 , 5-Diaminopentane As A Structure-Directing Agent for Zincophosphate Networks : Zn 3 ( PO 4 ) 2 ( C 5 H 14 N 2 ) 2 · 3 H 2 O and C 5 H 16 N 2 · Zn 3 ( PO 4 ) 2 ( HPO 4 ) · H 2 O

The crystal structures of two zincophosphate networks prepared in the presence of 1,5-diaminopentane (dap) are described. In Zn3(PO4)2(C5H14N2)2·3H2O (1) the dap forms Zn–N coordinate bonds to generate an unusual three-dimensional “hybrid” framework constructed from ZnO3N, ZnO2N2 and PO4 tetrahedra with three different types of elongated channels occupied by water molecules. In C5H16N2·Zn3(PO4)2(HPO4)·H2O; (2) the doubly-protonated H2dap acts in a more typical way to template double layers of vertex-sharing ZnO4, PO4 and HPO4 tetrahedra incorporating 10-rings and interacts with the inorganic component via N–H O hydrogen bonds. Crystal data: 1 (C10H34N4O11P2Zn3), Mr = 644.46, monoclinic, C2 (No. 4), Z = 4, a = 25.302 (7) Å, b = 4.9327 (13) Å, c = 19.808 (6) Å, β = 107.377 (8)°, V = 2359.4 (12) Å, R(F) = 0.054, wR(F) = 0.139. 2 (C5H19N2O13P3Zn3), Mr = 604.24, monoclinic, P21/c (No. 14), Z = 4, a = 11.3275 (15) Å, b = 8.3235 (11) Å, c = 18.588 (2) Å, β = 96.979 (3)°, V = 1739.6 (4) Å, R(F) = 0.056, wR(F) = 0.119.


Introduction
Linear-chain alkyl diamines of formula H 2 N(CH 2 ) n NH 2 are versatile and effective templates for a wide variety of porous inorganic networks incorporating many different metal ions [1][2][3][4].As might be OPEN ACCESS expected, the chain length n of the methylene groups of the diamine plays an important role in defining the resulting crystal structure: this is demonstrated with diamine-templated zinc phosphates (ZnPOs) and varied structures with n = 2 (i.e., ethylenediamine) [5], n = 3 [6], n = 4 [7] and n = 6 [8] have been described.
As an extension of these studies we now describe the structures of two zincophosphate networks incorporating the n = 5 member of this series, 1,5-diaminopentane [H 2 N(CH 2 ) 5 NH 2 ; C 5 H 14 N 2 ; dap], as the structure-directing agent.In Zn 3 (PO 4 ) 2 (C 5 H 14 N 2 ) 2 •3H 2 O (1) the neutral dap molecule bonds directly to the zinc ions as a bridging ligand to generate an unusual structure containing elongated "hybrid" channels containing water molecules, whereas in C 5 H 16 N

Crystal Structure of Zn
The asymmetric unit of compound 1 contains four Zn atoms, two P atoms, 11 O atoms (three of which belong to water molecules) and two C 5 H 14 N 2 (dap) molecules (Figure 1).

Figure 1.
The asymmetric unit of 1 (50% displacement ellipsoids) expanded to show the Zn coordination spheres.Atoms with a * suffix to their labels are symmetry generated (see Table 1).The zinc ions in 1 adopt two coordination modes: Zn1 and Zn2 (which both lie on crystallographic twofold axes) are coordinated by two O and two N atoms and Zn3 and Zn4 are bonded to three O and one N atom in tetrahedral geometries (Table 1).The global mean Zn-O and Zn-N separations are 1.937 Å and 2.038 Å, respectively, which are very similar to the equivalent geometrical data for related compounds [11].The XO 4 tetrahedral angular variances, defined as where ϑ is the O-X-O bond angle (°) [12], indicate that all the Zn-centred tetrahedra in 1 are significantly distorted: values of 98.4°2, 79.8°2, 81.2°2 and 85.9°2 arise for Zn1, Zn2, Zn3 and Zn4, respectively.All the O atoms also link to an adjacent P atom (mean Zn-O-P = 124.5°)and the N atoms are all parts of neutral dap molecules.Both PO 4 groups in 1 are close to regular tetrahedra (mean P1-O = 1.538Å, angular variance = 2.7°2; mean P2-O = 1.541Å, angular variance = 1.4°2) and all the O atoms link to an adjacent Zn atom, thus there are no terminal or "dangling" P=O or P-OH bonds [13] in 1.The geometrical parameters for the two unique dap molecules are unexceptional [14], and both molecules are in essentially extended conformations (mean absolute values of the N-C-C-C and C-C-C-C torsion angles = 177.6°and 174.7°, respectively).
The polyhedral connectivity of the Zn-and P-centred moieties leads to (100) sheets of vertex-sharing tetrahedra (Figure 2), in which there is prefect alternation of the Zn and P nodes (i.e., no Zn-O-Zn or P-O-P links).These sheets can be decomposed into four-ring ladders [15] propagating in [010] built up from the Zn3-and Zn4-centred species and the phosphate groups, with Zn1 and Zn2 (i.e., the ZnN 2 O 2 species) providing inter-chain links, as parts of polyhedral 8-rings.For any [010] stack of 8-rings, all the Zn1 (or Zn2) tetrahedra point in the same direction.
The dap molecules form bridges (via both their N atoms) to the adjacent (100) polyhedral sheets to generate a distinctive porous network (Figure 3), in which elongated [010] channels are bounded by the methylene groups of the dap molecules on their "long" sides and by the ZnPO framework on their "short" sides.Measured atom-to-atom, their dimensions are about 4.5 Å × 11.3 Å.It remarkable that there are three distinct types of channel in this structure: one contains four water molecules per b unit-cell repeat distance (type-A), one contains two water molecules (type-B) and the third (type-C) is empty.It is apparent from Figure 3 that the type-A channels "bulge out" to accommodate the water molecules and the type-C channels are consequently compressed inwards and are empty.Within the type-A channel, the water molecules interact via O-HLO hydrogen bonds (Table 2), such that a C(2) chain of O12-H6WLO12 bonds propagates up the central region of the channel.The other H atom attached to O12 forms a link to O11, which in turn forms two hydrogen bonds to framework O atoms.The -NH 2 groups of the dap molecules form N-HLO hydrogen bonds to framework O atoms as well as the water molecules to reinforce this rather intricate network, which occurs in a largely hydrophobic environment.The asymmetric unit of 2 contains three Zn atoms, two PO 4 groups, one HPO 4 group, a water molecule and a doubly-protonated H 2 dap dication (Figure 4).3).The hydrogen bonds are indicated by double-dashed lines.Note the three-coordinate O4 atom and the Zn1-O4-Zn2 bond.
The three Zn atoms form the centers of ZnO 4 tetrahedra (mean Zn1-O =1.943 Å, mean Zn2-O = 1.939Å, mean Zn3-O = 1.939Å).These are somewhat less distorted than the zinc polyhedra in 1 as indicated by the angular variances of 32.2°2, 37.4°2, and 47.2°2, for Zn1, Zn2 and Zn3, respectively.Atoms P1 and P2 (mean P-O = 1.534Å and 1.536 Å, respectively; angular variances = 2.9°2 and 2.4°2, respectively) are the central atoms of essentially regular phosphate groups and all their O atoms link to nearby zinc atoms.Atom P3 (mean P-O = 1.534Å, angular variance = 14.9°2) forms three links to Zn but also possesses a terminal bond to O12.Its length of 1.587 (4) Å indicates that it must by protonated (i.e., a P-OH species) and the corresponding H atom could indeed be located in a difference map.Geometrical data for 2 are summarized in Table 3.In the extended structure of 2, atom O4 plays an important role in the linking of the tetrahedra, as it forms bonds to Zn1, Zn2 and P1 (bond-angle sum = 357.6°).This results in "dimers" of the zinc species (Figure 4), but the Zn-O-Zn connectivity does not extend any further than this [16].The mean value of the Zn-O-P bond angle for the other O atoms is 133.7°,almost 10 degrees larger than the corresponding value in 1.
In the extended structure of 2, the inorganic layers form infinite (100) sheets containing 4-and 10-rings (Figure 5).The sheets sandwich the H 2 dap cations and the extra-layer water molecule (O13) (Figure 6).The water molecule accepts an O-HLO hydrogen bond from the hydrogen phosphate group and also probably forms O-HLO links to framework oxygen atoms.The protonated -NH 3 + groups of the H 2 dap cation form three N-HLO hydrogen bonds each (Table 4), which is a thoroughly typical bonding mode for a protonated amine in a ZnPO [5].The conformation of the carbon chain of the H 2 dap species is somewhat uncertain, but its contorted geometry is clearly different to the extended conformation found for the bridging dap molecules in 1.

Figure 2 .
Figure 2. Part of a (100) tetrahedral sheet in 1. Color key: Zn tetrahedra yellow, P tetrahedra green, O atoms red, N atoms blue.

Figure 3 .
Figure 3.View approximately down [010] of the unit-cell packing in 1, showing the three types of elongated channels with different water-molecule occupancies (see text).Color key as for Figure2; in addition, C dark grey, H white.

Figure 4 .
Figure 4.The asymmetric unit of 2 (50% displacement ellipsoids; indicative spheres for the C atoms), expanded to show the complete coordination spheres of the zinc atoms.Atoms with a * suffix are symmetry generated (see Table3).The hydrogen bonds are indicated by double-dashed lines.Note the three-coordinate O4 atom and the Zn1-O4-Zn2 bond.

Figure 6 .
Figure 6.The packing of 2 viewed down [010] showing the (100) inorganic layers sandwiching the organic cations and water molecules (pink spheres); other polyhedron/atom colors as in Figures 2 and 3.