5-[4-(Diethoxyphosphoryl)-2,3,5,6-tetrafluorophenyl]-10,15,20-tris-(pentafluorophenyl)porphyrin

The title compound, C(48)H(20)F(19)N(4)O(3)P, prepared by the nucleophilic attack of triethyl phosphite on one of the 4-fluoro atoms of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, contains a single molecule in the asymmetric unit. The porphyrin unit is almost planar [largest non-H atom deviation = 0.174 (6) Å], and has the planes of the neighbouring benzene rings oriented at angles ranging from 64.3 (2) to 89.6 (3)° relative to the porphyrin core. The P=O group is almost coplanar with the attached benzene ring, subtending an angle of 4.0 (3)°. Several weak supramolecular interactions, namely C-H...π, C-F...π, P=O...π, C-H...(O,F) and F...F contacts, contribute to the crystal packing.

The title compound, C 48 H 20 F 19 N 4 O 3 P, prepared by the nucleophilic attack of triethyl phosphite on one of the 4-fluoro atoms of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, contains a single molecule in the asymmetric unit.The porphyrin unit is almost planar [largest non-H atom deviation = 0.174 (6) A ˚], and has the planes of the neighbouring benzene rings oriented at angles ranging from 64.3 (2) to 89.6 (3) relative to the porphyrin core.The P O group is almost coplanar with the attached benzene ring, subtending an angle of 4.0 (3) .Several weak supramolecular interactions, namely C-HÁ Á Á, C-FÁ Á Á, P OÁ Á Á, C-HÁ Á Á(O,F) and FÁ Á ÁF contacts, contribute to the crystal packing.

Comment
New synthetic strategies and primary building blocks have been developed for the specific design of multidimensional coordination polymers which combine a wide range of metallic centres with ligands having multiple binding sites.For this purpose, porphyrin macrocycles can be designed having several coordination-capable groups located at the periphery of their core, which may ultimately also allow fine tuning of the framework topology (Natarajan & Mahata, 2009;Choi et al., 2009).Compared with carboxylate-based ligands, phosphonates are less commonly used to prepare coordination polymers, due to three main factors: (i) dense layered materials are usually formed, compared with the more interesting porous frameworks which may exhibit high surface areas; (ii) the growth of single crystals with phosphonates is generally more difficult because they often precipitate rapidly as less ordered and insoluble phases; (iii) the coordination chemistry of phosphonate groups is more complex due to their various stages of deprotonation (Natarajan & Mahata, 2009;Shimizu et al., 2009).Despite all these limitations, phosphonate-based ligands are still highly attractive molecules to prepare hybrid materials with different structures and interesting properties.
The asymmetric unit of (I) comprises a single molecule of the porphyrin derivative (Fig. 1).The porphyrin central core is approximately planar, with the largest distance from one atom (C14) to the average plane being 0.174 (6) A ˚.The substituent benzene rings subtend angles with the porphyrin core in the range 64.3 (2)-89.6 (3) .These values agree well with those typically observed in related materials [a search of the Cambridge Structural Database (Version 5.32; Allen, 2002) yields 66 hits, with all of the angles being in the range ca 60-90 , with a mean of 77.5 ], and allow a minimization of the steric repulsion between the F atoms and the porphyrin core.
The P O group of the phosphoryl moiety is located in the approximate average plane of the benzene ring to which it is attached [the ringÁ Á ÁP O angle is about 4.0 (3) ].This conformation of the phosphoryl group enables a significant reduction of the steric impediment associated with the presence of the two pendant and highly flexible ethyl groups (Fig. 1).The conformational arrangements of the two ethyl substituents are different.Firstly, while methylene atom C1 forms an antiperiplanar angle with its neighbouring O3-P1-C28 group, for methylene atom C3 the antiperiplanar angle is instead formed with its neighbouring O2-P1-O3 group.
The molecule of (I) lacks typical hydrogen-bonding donors, and therefore strong supramolecular interactions mediating the crystal packing are absent.In addition, the asymmetric nature of the molecule also seems to avoid the presence of The molecular structure of (I), showing the atom-labelling scheme.Displacement ellipsoids are drawn at the 50% probability level.typicalinteractions.Thus, the crystal packing is ensured by weak interactions such as C-HÁ Á Á, C-FÁ Á Á, P OÁ Á Á, C-HÁ Á Á(O,F) and FÁ Á ÁF contacts (Fig. 2; see Table 2 for geometric details of all these interactions).Molecules of (I) form supramolecular layers in the ab plane of the unit cell, having essentially C-HÁ Á Á contacts between the cores of adjacent porphyrin rings.The bulky phosphonate groups point towards these interlayer spaces and are engaged in a number of weak C-HÁ Á ÁO and C-HÁ Á ÁF interactions (Fig. 2 and Table 2).
It is noteworthy that the crystal structure contains a small void volume of ca 46 A ˚3 (Fig. 2).Although this empty space is suitable for the inclusion of a small solvent molecule, such as water, the total electron density found within the cavity is less than four electrons and highly smeared out, thus avoiding a sensible location and refinement of additional molecular entities within the crystal structure.

Crystal data
Crystals of (I) were systematically isolated as very small blocks.The largest crystal isolated from several batches had a maximum dimension of 0.08 mm and, even for long exposure times at 150 K, the R int value for a resolution better than ca 1.2 A ˚was always above 0.10.At this resolution range, in particular between 0.99 and 0.96 A ˚, the crystal diffracted very weakly, with the mean I/ value being only of about 1.3.In addition, the existence of empty voids within the crystal structure, which most certainly contain highly disordered solvent molecules, also contributed to the high refined R factors.Symmetry codes: (i) Àx, y + 1 2 , Àz + 3 2 ; (ii) Àx + 1, y À 1 2 , Àz + 3 2 ; (iii) Àx, Ày, Àz + 1; (iv) Àx + 1, Ày + 1, Àz + 2; (v) x À 1, y, z; (vi) x, y + 1, z.

Figure 2 A
Figure 2 A schematic representation of the crystal packing of (I), viewed in perspective along the [010] direction of the unit cell.H atoms not engaged in supramolecular interactions (dashed lines) have been omitted for clarity [in the electronic version of the paper, C-HÁ Á Á(N,O) interactions are orange dashed lines and C-HÁ Á Á interactions are blue dashed lines].The void volumes within the crystal structure are depicted schematically as transparent (blue) spheres.