TERNARY CHLORIDES WITH TRIGONAL-BIPYRAMID AL CLUSTERS - [M(5)(C-2)]CL-9 (M=LA-PR)

The chlorides [M(5)(C-2)]Cl-9 (M = La-Pr) are obtained by metallotherm ic reduction of the respective trichlorides MCl(3) with caesium in the presence of the lanthanide metal and carbon in sealed niobium ampoule s at 800 degrees C. They contain trigonal-bipyramidal clusters [M(5)(C -2)] crystallizing with the triclinic crystal system. Only seven of th e nine edges of the trigonal bipyramids are brigded by chloride (Cl-i) . Each cluster is surrounded by twelve terminal ligands (Cl-a) so that units of the composition [M(5)(C-2)Cl-7(i)]Cl-12(a) have to be consid ered. These are connected not only via Cl-i-a and Cl-a-a-a bridges. Ra ther, Cl-a-a (one linear and one bent) and C1(i-i) bridges are also ob served.