An analytical approach to solve the CO-factored force fields of Hg[Co(CO)(4)](2) belonging to D-3d Point group is described here. The approach leads to relationships which allow direct calculation of carbonyl stretching force constants and CO-CO interaction constants from C-O stretching frequencies of an all (CO)-C-12-O-16 molecule. The force constants calculated by these relationships have been found to be in excellent agreement with those obtained from the Cos beta parameter method. In addition, carbonyl stretching frequencies of the mono (CO)-C-13 substituted derivatives of Hg[CO(CO)(4)](2) have been estimated. The results exhibit agreement between calculated and observed frequencies, showing thereby that the analytical approach presented here gives a valid solution to the CO-factored force field of the molecule under study.