Electronic and structural properties of Ben-1On2- (n = 3-6) , MgBe2O42- and CuBe2O42-

Recently, a new class of free stable gas-phase dianions with general formula Ben-1On2- was discovered experimentally and, moreover, a CuBe2O42- dianion as well as an unidentified half-integral m/z signal at 53.5 tentatively assigned to MgBe2O42- were detected. Here, the structural and electronic properties of these dianions are investigated by means of high-level ab initio calculations. It is demonstrated that the Ben-1On2- (n ⩾ 4), MgBe2O42- and CuBe2O42-dianions exhibit linear geometries and represent electronically stable dianions in the gas phase. Relations of these dianions to other known free stable dianions are discussed.