The crystal structure of Rb5Mo27Se31, pentarubidium heptacosamolybdenum hen
triacontaselenium, consists of a mixture of Mo12Se14Se6 and Mo15Se17Se6 clu
ster units in a 1:1 ratio. Both types of cluster are interconnected through
inter-unit Mo-Se bonds. Rb+ cations occupy large voids between the differe
nt cluster units.