Nitro-sonium complexation by the tetra-phospho-nate cavitand 5,11,17,23-tetra-methyl-6,10:12,16:18,22:24,4-tetra-kis-(phenyl-phospho-nato-κ2O, O)resorcin(4)arene

Abstract

The crystal structure of a new supra-molecular complex between the tetra-phos-pho-nate cavitand 5,11,17,23-tetra-methyl-6,10:12,16:18,22:24,4-tetra-kis(phenyl-phospho-nato-κ²O,O')resorcin(4)arene and the nitrosyl cation NO⁺, as the BF₄^- salt, is reported. The complex, of general formula [(C₅₆H₄₄P₄O₁₂)(NO)]BF₄·CH₂Cl₂ or NO@Tiiii[H, CH₃, C₆H₅] BF₄·CH₂Cl₂, crystallizes in the space group P-1. The nitrosyl cation is disordered over two equivalent positions, with occupancies of 0.503 (2) and 0.497 (2), and inter-acts with two adjacent P=O groups at the upper rim of the cavitand through dipole-charge inter-actions. In the lattice, the cavitands are connected through a series of C-H⋯π inter-actions involving the methyl and methyl-enic H atoms and the aromatic rings of the macrocycle. The structure is further stabilized by the presence of C-H⋯F inter-actions between the hydrogen atoms of the cavitands and the F atoms of the tetra-fluorido-borate anion. As a result of the disorder, the lattice di-chloro-methane mol-ecules could not be modelled in terms of atomic sites, and were treated using the PLATON SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The complexation process has also been studied in solution through NMR titrations.

Keywords: C—H⋯F inter­actions; C—H⋯π inter­actions; crystal structure; inclusion compounds; nitro­sonium ion; tetra­phospho­nate cavitands.

Figure 1

Selected portions of the ¹H NMR (400 MHz, CDCl₃, 298 K) spectra recorded during the titration of the cavitand with increasing equivalents of NOBF₄.

Figure 2

Top and side views of the title compound, NO@Tiiii[H, CH₃, C₆H₅], with a partial atom-labelling scheme. Displacement ellipsoids are drawn at the 20% probability level. Only one of the two disordered NO⁺ ions is shown. In the side view, the hydrogen atoms and the BF₄ ⁻ counter-ion are not shown for clarity. Cation–dipole inter­actions are represented as blue dashed lines.

Figure 3

C—H⋯π inter­actions (green dashed lines) forming a ribbon along the a-axis direction of the unit cell. Centroids Cg1 (C9B–C14B), Cg2 (C9D–C14D) and Cg3 (C1A–C6A) are represented as red, green and blue spheres, respectively.

Figure 4

View of the BF₄ ⁻ ion surrounded by the five closest cavitands through C—H⋯F inter­actions. [Symmetry codes: (i) x, y − 1, z; (ii) −x + 1, −y + 1, −z; (iii) x, y, z − 1; (iv) −x, −y + 1, −z + 1.]

Figure 5

Comparison of the inter­action modes of GOTCAT, JAHFOO (side view), and of the title compound, NO@Tiiii[H, CH₃, C₆H₅] (top view), highlighting the disorder of the guest over two equivalent positions. The space-filling view is only partial for reasons of clarity.