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

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Abstract
The first‐ and second‐order molecular Zeeman effect has been observed in fluorobenzene to give the molecular g values of g aa = − (0.0670 ± 0.0008) , g bb = − (0.0397 ± 0.0015) , g cc = + (0.0266 ± 0.0017) , and the magnetic susceptibilityanisotropies of 2χ aa − χ bb − χ cc = + (52.9 ± 0.8) × 10 −6 erg / G 2 · mole and 2χ bb − χ cc − χ aa = + (63.6 ± 1.5) × 10 −6 erg / G 2 · 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 susceptibilityanisotropies with the average magnetic susceptibility we can show that the signs must be as assigned above. The diagonal elements in the total magnetic susceptibilitytensor are χ aa = − (40.6 ± 0.8) × 10 −6 , χ bb = − (37.1 ± 0.8) × 10 −6 , and χ cc = − (97.2 ± 2.0) × 10 −6 erg / G 2 · mole . The diamagnetic and paramagneticsusceptibilities are given as χ aa d = − (293.3 ± 1.7) × 10 −6 , χ aa p = (252.7 ± 0.7) ± 10 −6 , χ bb d = − (509.7 ± 3.6) × 10 −6 , χ bb p = (472.6 ± 2.6) × 10 −6 , χ cc d = − (732.4 ± 5.0) × 10 −6 , and χ cc p = (635.2 ± 4.0) × 10 −6 erg / G 2 · mole . The molecular quadrupole moments are Q aa = − (1.9 ± 0.8) × 10 −26 , Q bb = + (5.1 ± 1.5) × 10 −26 , and Q cc = − (3.2 ± 1.5) × 10 −26 esu · cm 2 . The values of the second moment of the electronic charge distribution are 〈a 2 〉 = (111.8 ± 0.7) × 10 −16 , 〈b 2 〉 = (60.8 ± 0.7) × 10 −16 , and 〈c 2 〉 = (8.4 ± 0.7) × 10 −16 cm 2 .