Paramagnetic closed-shell molecules: the isoelectronic series CH+, BH and BeH-

Coupled Hartree-Fock calculations predict CH+, like its isoelectronic analogue BH, to be paramagnetic. The calculated magnetizability has components χ∥(CH+) = - 1·44 and χ⊥(CH+) = + 10·54 a.u. with a mean value χ(CH+) = + 6·55 a.u. (5·17 × 10-28 J T-2). Predicted nuclear shieldings are σ(C) = - 1250 ppm and σ(H) = + 34·1 ppm. The isolated BeH- anion is predicted to lie on the diamagnetic/paramagnetic borderline, but when placed in a crystal lattice is likely to be weakly diamagnetic.