A first study of diastatides: BeAt2, BAt2 and CAt2

Effective core potentials (ECPs) augmented with large, flexible valence bas is sets (tested on HAt) have been used to obtain the geometries and harmoni c vibrational frequencies of the diastatide compounds BeAt2, BAt2 and CAt2 for the first time. For CAt2, the ground electronic state is calculated to be the (A) over tilde (1)A(1) state, and the lowest singlet-triplet gap is calculated to be larger than that of CI2, which is against expectations bas ed upon electronegativity. (C) 2000 Elsevier Science B.V. All rights reserv ed.