Molecular g Values, Magnetic Susceptibility Anisotropies, and Molecular Quadrupole Moments in Fluorobenzene

Abstract

The first- and second-order molecular Zeeman effect has been observed in fluorobenzene to give the molecular g values of gaa = − (0.0670 ± 0.0008), gbb = − (0.0397 ± 0.0015), gcc = + (0.0266 ± 0.0017), and the magnetic susceptibility anisotropies of 2χaa − χbb − χcc = + (52.9 ± 0.8) × 10−6erg/G2·mole and 2χbb − χcc − χaa = + (63.6 ± 1.5) × 10−6erg/G2·mole. The a axis passes through the CF bond and the b axis is also in the molecular plane. Only the relative signs of the g values are obtained experimentally. However, by combining our magnetic susceptibility anisotropies with the average magnetic susceptibility we can show that the signs must be as assigned above. The diagonal elements in the total magnetic susceptibility tensor are χaa = − (40.6 ± 0.8) × 10−6, χbb = − (37.1 ± 0.8) × 10−6, and χcc = − (97.2 ± 2.0) × 10−6erg/G2·mole. The diamagnetic and paramagnetic susceptibilities are given as χaad = − (293.3 ± 1.7) × 10−6, χaap = (252.7 ± 0.7) ± 10−6, χbbd = − (509.7 ± 3.6) × 10−6, χbbp = (472.6 ± 2.6) × 10−6, χccd = − (732.4 ± 5.0) × 10−6, and χccp = (635.2 ± 4.0) × 10−6erg/G2·mole. The molecular quadrupole moments are Qaa = − (1.9 ± 0.8) × 10−26, Qbb = + (5.1 ± 1.5) × 10−26, and Qcc = − (3.2 ± 1.5) × 10−26esu·cm2. The values of the second moment of the electronic charge distribution are 〈a2〉 = (111.8 ± 0.7) × 10−16, 〈b2〉 = (60.8 ± 0.7) × 10−16, and 〈c2〉 = (8.4 ± 0.7) × 10−16cm2.