Density Functional Theory implemented in ADF 2012.01 was used to know about the relative spatial displacements of the three/four metals and the 12 surrounding CO groups in the 5 poly-nuclear transition metal carbonyls. A number of NMR parameters namely Chemical Shifts of the metals, the carbon and the oxygen species (δ M, 13δ C, δ17O), their Total NMR Shielding Tensors (σ M, σ 13C, σ17O) along with their four paramagnetic [paramagnetic (b^) tensor, paramagnetic (u^) tensor, paramagnetic(s^) tensor and paramagnetic gauge tensor] and two diamagnetic [diamagnetic core tensor and diamagnetic valence tensor] contributions were obtained. These parameters [δ 13C, δ 17O, σ 13C and σ17O] were also compared with the Total Coordination Shifts [Δδ13CT and Δδ17OT], the atomic electron valence density (integrated)/ L value of oxygen and the charges on both oxygen and metal atoms. The Effective Spin Hamiltonian (H^) of the metals and the carbon atoms were calculated from their k and j values. In none of these carbonyls, the three/four metals and any two among the 12COs were both spatially and magnetically equivalent. Of course, many metals and CO groups were found to be spatially equivalent. When the perturbing species was the first metal and the responding species was the spatially equivalent other metal /s or vice versa, their sets of k and j values remained to be the same. Similarly, for CO groups directly attached to one metal and the spatially equivalent CO groups attached to the other metal /s, the sets of k and j values of 13C nuclei remained to be the same. It classified all the (3n-6) fundamental bands of the carbonyls into four types according to their IR-/ Raman- activity. The NMR studies corroborated well with the results already known from their IR/Raman studies in confirming the π – acid character of the carbonyls. Some optimization and thermal parameters of these carbonyls were also calculated.