Molecular Rotational Zeeman Effect in Thioformaldehyde

Abstract

The high-field rotational Zeeman effect has been observed in thioformaldehyde. The magnetic susceptibility anisotropies are 2 χaa − χbb − χcc = 52.3 ± 1.1 (× 10−6 erg/G2 · mole) and 2 χbb − χaa − χcc = −5.1 ± 0.7. The molecular g values with uniquely determined signs are gaa = −5.2602 ± 0.0068, gbb = −0.1337 ± 0.0004, and gcc = −0.0239 ± 0.0004. c is the out-of-plane axis and the a axis is the dipole axis. gaa represents the largest molecular g value yet measured. Use of these five Zeeman parameters and the known structure gives the molecular quadrupole moments: Qaa = 3.0± 0.7 (× 10−26 esu · cm2), Qbb = −2.4 ± 0.5, Qcc = −0.6 ± 1.1; the diagonal elements of the paramagnetic susceptibility tensor: χaap = 45.8 ± 0.3 (× 10−6 erg/G2 · mole), χbbp = 88.3 ± 0.6, χccp = 82.6 ± 0.6; and the anisotropies in the second moments of the electronic charge distribution. By estimating the out-of-plane second moment of the electronic charge distribution as 〈 c2 〉 = 4.6 ± 0.4 (× 10−16 cm2) using free atom values, we have evaluated the remaining individual second moments of the electronic charge distribution to be 〈 a2 〉 = 21.1 ± 0.6 (× 10−16 cm2) and 〈 b2 〉 = 6.6 ± 0.5. The diagonal elements of the diamagnetic and total magnetic susceptibility tensor also follow from the above estimation of 〈 c2 〉 and are χaad = −47.5 ± 2.5 (× 10−6 erg/G2 · mole), χbbd = −109.1 ± 3.0, χccd = −117.6 ± 3.4, χaa = −1.7 ± 2.5, χbb = −20.8 ± 3.1, and χcc = −35.0 ± 3.5, giving the bulk magnetic susceptibility as χ = 13 (χaa + χbb + χcc) = −19.2 ± 1.8 (× 10−6 erg/G2 · mole. These values are then compared to those of the oxygen analog, formaldehyde, and trends in this pair are compared to several other previously studied oxygen-sulfur analogs.