Low Temperature Crystal Growth and Structure of Ordered Ba7F12Cl2

Crystals of composition Ba[7]F[12]Cl[2] were obtained by areaction at room temperature between Ba[2+]/Cl[-]/F[-]in a gel of agar-agar/water. The hexagonal crystals have space group P6, a=1064.69(8), c=417.89(5)pm, V=410.24(8) 10[6] pm[3] and Z=l. The anions form a propeller type network located in tunnels parallel to the c[hex] axis; the chloride ions are located at the center on the propeller axes. The Ba[2+] ions are coordinated by a (distorted) tricapped trigonal environment of fluoride and chloride anions. Disorder is present for one particular Ba[2], site. The average structure is isotypic with the structure of Pb[7]F[12]Cl[2].