Molecular g Values, Magnetic Susceptibility Anisotropies, and Molecular Quadrupole Moments in Ethylene Oxide

Abstract

The first- and second-order molecular Zeeman effect has been recorded in ethylene oxide to yield the molecular g values and magnetic susceptibility anisotropies in the molecule. The magnetic susceptibility anisotropies are 2χaa − χbb − χcc = + (18.06 ± 0.58) × 10−6 and 2χbb − χaa − χcc = + (0.78 ± 0.97) × 10−6erg/G2·mole. The b axis bisects the COC angle and the a axis is also in the COC plane. Only the relative signs of the g values are experimentally determined. Arguments are presented which favor one of the two sets of signs giving gaa = − (0.0946 ± 0.0003), gbb = + (0.0189 ± 0.0004), and gcc = +(0.0318 ± 0.0006. The molecular quadrupole moments, with this choice of signs, are Qaa = + (2.5 ± 0.4) × 10−26, Qbb = − (4.3 ± 0.5) × 10−26, and Qcc = + (1.8 ± 0.8) × 10−26esu·cm2. The diagonal elements in the paramagnetic susceptibility tensor are χaap = (60.6 ± 0.3) × 10−6, χbbp = (67.3 ± 0.5) × 10−6, and χccp = (88.3 ± 0.5) × 10−6erg/G2·mole. The known value of the average magnetic susceptibility is combined with our values for the paramagnetic susceptibilities and anisotropies of the total susceptibility to yield the diagonal elements in the total and diamagnetic susceptibility tensors. The total susceptibilities are χaa = − (24.7 ± 0.7) × 10−6, χbb = − (30.4 ± 0.7) × 10−6, and χcc = − (37.0 ± 0.8) × 10−6erg/G2·mole and the diamagnetic susceptibilities are χaad = − (85.4 ± 0.9) × 10−6, χbbd = − (97.7 ± 1.1) × 10−6, and χccd = − (125.4 ± 2.0) × 10−6erg/G2·mole. The second moment of the ground-state electronic charge distribution is 〈a2〉 = (16.3 ± 0.4) × 10−16, 〈b2〉 = (13.3 ± 0.4) × 10−16, and 〈c2〉 = (6.8 ± 0.4) × 10−16cm2.