Crystal structure of the new A2SnTa6X18 (A = K, Rb, Cs; X = Cl, Br) cluster compounds

Evolution of c parameter versus a parameter of the octahedral cluster compounds crystallizing in the Cs2EuNb6Br18-type structure of space group R−3 and representation of the discrete [M6Xi12Xa6]4- cluster unit. Single-crystal data are denoted by *.223