Synthesis and Crystal Structure of a New Potassium Yttrium Diphosphate Dihydrate KYP_2O_7·2H_2O

The dihydrated potassium yttrium diphosphate=KYP2O7·2H2O=has been synthe- sized for the first time. Single-crystal XRD study has allowed the determination of its structure and correct formula. It crystallizes in the monoclinic system=space group P21/c=with the cell parameters a=7.7069(3)=b=10.5801(4)=c=10.0204(5)=β=93.24(3)°=V=815.76(6)3=Z=4=Mr=337.98=F(000)=656=Dc=2.752 g/cm3 and μ=8.073 mm-1. The single-crystal structure was solved from 1856 unique reflections with the final R=0.0365 and wR=0.0772=refined with 119 parameters. The atomic arrangement of KYP2O7·2H2O is built by the P2O7 groups=the YO7 and the KO10 polyhedrons which are connected by corner and edge-sharing to form a three- dimensional framework. Water molecules are directly bonded to the Y and K atoms=and they are located in channels running along the a direction.