μ-OXO-BIS[TRIS(PYRROLIDINO-N)PHOSPHONIUM] TRIFLUOROMETHANESULFONATE, A SALT WITH A DIPHOSPHONIUM ION WITH A NON-LINEAR P‒O‒P SEQUENCE

The title compound contains the diphosphonium ion, [(C 4 H 8 N) 3 P‒O‒P(NC 4 H 8 ) 3 ] 2+ . The structure of the compound is disordered at room temperature. By slow cooling, it goes through a phase transition near −100°C and as a result becomes ordered. Unlike the similar cations [(Me 2 N) 3 P‒O‒P(NMe 2 ) 3 ] 2+ , and [(OC 4 H 8 N) 3 P‒O‒P(NC 4 H 8 O) 3 ] 2+ , it has a non-linear P‒O‒P sequence both in the disordered and ordered phase with P‒O‒P angles between 155.5(3) and 159.2(3)°. The X-ray crystallographic study of the title compound, both at 273 and 103 K, shows that the P‒O and P‒N bond lengths are very similar to those of the linear cations. The P‒O and P‒N bond lengths in the title compound ranges from 1.578(4) to 1.602(4) Å and from 1.585(5) to 1.605(5) Å, respectively.