Metal-phthalocyanie adsorbed on metal surfaces are class of materials particularly promising as a building blocks for molecular electronic devices. Their application rely on the electrochemically induced switching of their electronic and magnetic state has been demonstrated [1]. The knowledge of their molecular geometry and electronic structure as a single entities and when adsorbed on surface are crucial points in order to understand their interaction with surfaces. By means of density functional theory (DFT) we have investigated conformational interconversion ( see Fig. 1) of single MPc molecules as their interaction with Ag(111) silver surfaces. Structural analysis using B3-LYP functional; and DZVP2 and TZVPP2 [2] basis set has been performed to evaluate the transition state (TS) and energy barrier of this conversion. We have found two different mechanism of inversion for SnPc and PbPc. To study the adsorption of metal-phthalocyanies MPc (M=Co; Sn; Pb) bonded parallel to the Ag(111) surface we used cluster representation of surface (55 and 169 silver atoms). To perform this calculations the generalized gradient approximation (GGA) parameterisation by Pedrew-Burke-Ernzerhof (PBE) for exchange-correlation energy [3] and multipole resolution of identity [4] method were used. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). For each of these systems we have found good agreement in binding geometries with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [4;5]. Binding energies and geometries for all systems are given. We have used electronic structure calculations to better understand these molecules as a separate entities and as a devices