Peculiarities of structure formation of layered chalcogenides with mix
ed tetrahedral and octahedral cation coodination are considered. The c
riterion for purposive search of new layered compounds was proposed. N
ew layered compounds as Cu(Ag)Ga2.5In2.5S8, Mg0.5Ga2InS5, CuIn5S3Se5 a
nd others were obtained and studied.