Beryllium (II) Chloride Complexes with Phosphoryl Ligands: A DFT Study

Abstract

Beryllium complexes of the types [BeCl2L2] (L = (Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (3) and P(O)F3 (4)) have been theoretically studied by means of DFT geometry optimization and NMR chemical shift calculations (B3LYP/6-31G(d)). A good correlation was found between calculated and experimental data for complex 2. On going from complex 1 to 4, the Be-L bond underwent considerable lengthening, while that of Be-Cl was shortened (Be-O: 1.646 in 1 vs. 1.740 A° in 4; Be-Cl: 2.043 in 1 vs. 1.953 A° in 4). In the same way, the Be-O-P bond angle was found to decrease from 135° for 1 to 124° for 4. The trends are in good agreement with the calculated metal-ligand binding energies of complexes 1-4. Interestingly, the structural changes are Original Research Article Essalah et al.; IRJPAC, 22(1): 38-46, 2021; Article no.IRJPAC.64877 39 accompanied by increased Be chemical shifts towards higher frequencies as the Me2N groups in the ligand are substituted by fluorine atoms. The results were compared to corresponding complexes with tin (IV) chloride, [SnCl4L2]. The theoretical data showed that the use of the 6-31G* basis set could efficiently predict the 9 Be NMR chemical shifts in the complexes [BeCl2L2].