Matching of Host-Guest Symmetry/Orientation and Molecular Dynamics in Two Double Perovskite-Like Azido Coordination Polymers.

Two new double perovskite-like azido coordination polymers with trimethylammonium as the guest cation, namely, (Me3NH)2[CrNa(N3)6] and (Me3NH)2[CrK(N3)6], have been prepared. The molecular dynamics for both compounds are investigated and are clearly uncovered by the first-principles molecular dynamics simulation and the significant dielectric relaxation. Structural analyses of these compounds in combination with their analogue (Me3NH)[Mn(N3)3] reveal that the guest trimethylammonium has flexible structural adaptability, especially with a variety of disordered distributions, to match the different symmetries of varied metal-azido frameworks. Interestingly, the replacement of the divalent metal ion by mixed monovalent/trivalent metal ions can change the symmetry, shape, and charge distribution of the host cage unit; thus it may influence and regulate the arrangement of the guest inclusion and its molecular dynamics as well as the structural phase transition.