In this work we have performed a systematic study of new organometallic complexes containing penta- and heteropentadienyl (CH2CHCHCHX, X = CH2, O, NH, S) ligands coordinated to beryllium. Calculated complexes were studied using the density functional theory (PBE) in combination with the 6-311++G(3d,2p) basis set. The coordination number on the beryllium atom varies according to the type of ligand. Pentadienyl ligand shows hapticities η(1) and η(5), while heteropentadienyl ligands display η(1) and η(2) hapticities. A Wiberg bond indices study was performed in order to get information about their bond orders.