The physical properties of compounds have remained an interesting and important area of ​​research since the last century. Various physical properties of a compound depend on the vibrations of the atoms present in it. Lattice dynamics is considered an important tool for studying these atomic vibrations. The study of the lattice dynamics of a compound provides information on the nature of the interatomic forces present and helps to understand its bonding and structural properties. Raman and IR spectral studies represent an important area in the field of lattice dynamics as they contain rich and valuable information. It provides information on the structure and chemical composition of the compound. Raman and infrared spectra are used to identify the molecule. This data is also useful for determining the symmetry of the site occupied by the atom and its exact position within a crystal. Many inorganic compounds with complex structures change their structural phase under particular physical conditions. These transitions in the compound from one phase to another can be determined through Raman and infrared spectral data. Using this, the vibrational frequencies of compounds can also be identified and assigned based on normal coordinate analysis. In recent years, with the rapid development of science and technology, complex structure inorganic compounds have become an important area of ​​theoretical and experimental research. Raman and infrared mode assignment of many recently studied complex structured materials is not available. Therefore, in the present work, studies on the lattice dynamics of some of the complex-structured inorganic compounds were conducted in order to identify and assign their Raman and infrared wavenumbers by applying short... middle of paper.... .. the linear variation of force constants with concentration in this compound suggests that this compound exhibits modal behavior for 0 ≤ x ≤ 0.2. Conclusions A short-range force constant model involving several stretching force constants and bending to evaluate Raman and infrared wavenumbers of structured inorganic complexes composed of Cs2HgCl4, Cs2CdBr4, NaCdAsS3, mixed crystals Ba2-xSrxMWO6 (M = Co, Ni); 0 ≤ x ≤ 1.2 and Bi1-xTa1-xTe2xO4; 0 ≤ x ≤ 0.2. The calculated Raman and infrared modes show good agreement with the experimental results. For the first time, the assignment of frequencies to specific symmetry modes of some of these compounds has been carried out. The linear variation of the force constant with composition suggests single-mode behavior in the Ba2-xSrxMWO6 (M = Co, Ni) mixed crystals for 0 ≤ x ≤ 1.2 and Bi1-xTa1-xTe2xO4 for 0 ≤ x ≤ 0.2.