Nitrosonium complexation by the tetraphosphonate cavitand 5,11,17,23-tetramethyl-6,10:12,16:18,22:24,4-tetrakis(phenylphosphonato-κ2 O,O)resorcin(4)arene

The crystal structure of a new supramolecular complex between the tetraphosphonate cavitand 5,11,17,23-tetramethyl-6,10:12,16:18,22:24,4-tetrakis(phenylphosphonato- k2-2O,O0)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] BF4CH2Cl2, crystallizes in the space group P1. The nitrosyl cation is disordered over two equivalent positions, with occupancies of 0.503 (2) and 0.497 (2), and interacts with two adjacent P O groups at the upper rim of the cavitand through dipole–charge interactions. In the lattice, the cavitands are connected through a series of C—H...pi interactions involving the methyl and methylenic H atoms and the aromatic rings of the macrocycle. The structure is further stabilized by the presence of C—H...F interactions between the hydrogen atoms of the cavitands and the F atoms of the tetrafluoridoborate anion. As a result of the disorder, the lattice dichloromethane molecules 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