A comparison of DFT is made for the calculation of geometry, bond dissociation energy (BDE), and dispersion interaction differences between complexes with ligand carbodiphosphorane-analogues (called tetrylones) [(CO)5W{E(PH3)2}] (W5-EP2) and complexes with ligand N-heterocyclic carbene-analogues (called tetrylenes) [(CO)5W{NHEMe}] (W5-NHEMe) when E = C - Pb. Gradient-corrected (BP86) density-functional calculations were chosen to study the structures and energies of two systems using quantum chemical calculations at BP86/TZVPP // BP86/SVP level of theory. The calculated equilibrium structures of the complexes [(CO)5W-{E(PH3)2}] show that the carbone ligand C(PH3)2 is bonded head-on to the metal fragment in the adduct W5-CP2, but the heavier homologues W5-SiP2 to W5-PbP2 have side-on bonded ligands E(PH3)2. The trend of the bond dissociations energies (BDEs) for the W-E bond in W5-EP2 system is W5-CP2 W5-SiP2 W5-GeP2 W5-SnP2 W5-PbP2. In contrast,.the complexes [(CO)5W{NHEMe}] (W5-NHEMe) possess end-on-bonded NHEMe ligands with E W5-NHSiMe W5-NHGeMe W5-NHSnMe W5-NHPbMe. The BDEs calculated for the W-E bonds in W5-EP2 and W5-NHEMe systems considering dispersion interactions show that the effect of bulky ligands E(PH3)2 and NHEMe influence the intrinsic W-E bond strength. These results suggest that this interesting class of compounds is worth further study.