AMoPO (A = Rb, Cs) and RbMoPO: new molybdophosphates with distinct polyanionic configurations.

The exploration of A-Mo-P-O (A = Rb, Cs) systems has allowed several new Mo(V) phosphates, RbMoPO, RbMoPO and CsMoPO, to be synthesized through the spontaneous nucleation method. Single-crystal X-ray diffraction analysis reveals that the identical stoichiometry compounds RbMoPO and CsMoPO belong to different space groups 2/ and , respectively. Both compounds consist of dissimilar 1D [Mo-O-P] chains with different repeated building units, while monovalent cations fill in spaces to form 3D structures. However, RbMoPO and CsMoPO are isostructural and crystallize in the same space group of 2/. They exhibit a 3D framework structure with 0D MoOOPO groups, which are separated by Rb/Cs atoms. Interestingly, structural relationships between the different monophosphates of the A-Mo-P-O (A = Rb, Cs) systems are presented in which distinct polyanionic configurations appear owing to the A/P ratios, as well as the size of the univalent cations. Further, detailed structural comparisons, optical properties and theoretical calculations are also discussed.