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Ab initio study on the coordination structures of AsO3−, VO3− and CO32− with alkali cations

1992; Elsevier BV; Volume: 253; Linguagem: Inglês

10.1016/0166-1280(92)87102-6

1872-7999

Fabio Ramondo, L. Bencivenni, Nico Sanna, Stella Nunziante Cesaro,

Inorganic Fluorides and Related Compounds

This study reports the results of an ab initio Hartree-Fock - Self-Consistent-Field study carried out on D3h symmetry AsO3−, VO3− and CO3·- and on the coordination structures of these anions with alkali cations. Geometry optimizations and vibrational frequencies were calculated from polarized split-valence basis sets. Bidentate, monodentate and tridentate coordination structures were considered for LiAsO3, LiVO3, Li2CO3, Na2CO3 and LiNaCO3. Bidentate binding is the most stable coordination structure for all the molecules, whereas the monodentate structures of Li2CO3, Na2CO3 and LiNaCO3 are first-order saddle points with regard to the in-plane migration of the metal atom and are the transition states between equivalent bidentate structures. Monodentate LiAsO3 and LiVO3 are second-order saddle points with respect to the in-plane and out-of-plane motion of the alkali metal. The trigonal pyramidal structures of all the molecules are the highest energy configurations and are higher-order saddle points. This work includes MP2/6-31G∗ geometry optimizations of the bidentate coordination structures of HCO2Li, HCO2Na, LiNO2, NaNO2, LiPO2, LiClO2, LiSO2, NaSO2, LiBO2, NaBO2 and of LiNO3 and LiPO3.