Molecular g Values, Magnetic Susceptibility Anisotropies, Molecular Quadrupole Moments, and the Second Moment of the Electronic Charge Distribution in OCF2, CH2CF2, cis-CHFCHF, and CH2F2

The rotational molecular Zeeman effect is observed under high resolution and high magnetic fields in OCF₂, CH₂CF₂, cis‐CHFCHF, and CH₂F₂. The absolute values of the molecular $g$ values ${\mathrm{(g}}_{\mathrm{aa}}{\mathrm{,\; g}}_{\mathrm{bb}},\mathrm{and}{g}_{\mathrm{cc}})$ and the signs and magnitudes of the magnetic susceptibility anisotropies ${\text{[(2χ}}_{\mathrm{aa}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{bb}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{cc}})\mathrm{and}{\text{(2χ}}_{\mathrm{bb}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{aa}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{cc}}\mathrm{)]}$ in the principal inertial axes are obtained and listed. Arguments are presented to show that all molecular $g$ values are negative leading to the molecular quadrupole moments. For ease of comparison, the values are given below in an arbitrary $\mathrm{x,\; y,}$ and $z$ axis system. The $x$ and $y$ axes are in the heavy‐atom molecular plane, and the $x$ axis bisects the FCF angle in all of the molecules. The units of $\chi$ are 10⁻⁶ erg/G²·mole and the units of $Q_{\mathrm{xx}}$ are 10⁻²⁶ esu·cm². $$\begin{array}{ccccc}& {\mathrm{OCF}}_2& {\mathrm{CH}}_2={\mathrm{CF}}_2& \mathrm{cis‐}\mathrm{CHF}=\mathrm{CHF}& {\mathrm{H}}_2{\mathrm{CF}}_2\\ g_{\mathrm{xx}}& \text{−\hspace{0.17em}(0.0568\hspace{0.17em}±\hspace{0.17em}0.0006)}& \text{−\hspace{0.17em}(0.0421\hspace{0.17em}±\hspace{0.17em}0.0005)}& \text{−\hspace{0.17em}(0.0296\hspace{0.17em}±\hspace{0.17em}0.0003)}& \text{−\hspace{0.17em}(0.0411\hspace{0.17em}±\hspace{0.17em}0.0004)}\\ g_{\mathrm{yy}}& \text{−\hspace{0.17em}(0.0747\hspace{0.17em}±\hspace{0.17em}0.0004)}& \text{−\hspace{0.17em}(0.0466\hspace{0.17em}±\hspace{0.17em}0.0004)}& \text{−\hspace{0.17em}(0.1015\hspace{0.17em}±\hspace{0.17em}0.0009)}& \text{−\hspace{0.17em}(0.0725\hspace{0.17em}±\hspace{0.17em}0.0006)}\\ g_{\mathrm{zz}}& \text{−\hspace{0.17em}(0.0328\hspace{0.17em}±\hspace{0.17em}0.0006)}& \text{−\hspace{0.17em}(0.0119\hspace{0.17em}±\hspace{0.17em}0.0004)}& \text{−\hspace{0.17em}(0.0158\hspace{0.17em}±\hspace{0.17em}0.0002)}& \text{−\hspace{0.17em}(0.0398\hspace{0.17em}±\hspace{0.17em}0.0004)}\\ {\text{(2χ}}_{\mathrm{xx}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{yy}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{zz}})& \text{+\hspace{0.17em}(1.6\hspace{0.17em}±\hspace{0.17em}0.9)}& \text{−\hspace{0.17em}(2.3\hspace{0.17em}±\hspace{0.17em}0.6)}& \text{−\hspace{0.17em}(1.6\hspace{0.17em}±\hspace{0.17em}0.3)}& \text{+\hspace{0.17em}(0.8\hspace{0.17em}±\hspace{0.17em}0.4)}\\ {\text{(2χ}}_{\mathrm{yy}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{xx}}{\mathrm{\hspace{0.17em}-\hspace{0.17em}\chi }}_{\mathrm{zz}})& \text{+\hspace{0.17em}(5.3\hspace{0.17em}±\hspace{0.17em}0.6)}& \text{+\hspace{0.17em}(7.7\hspace{0.17em}±\hspace{0.17em}0.5)}& \text{+\hspace{0.17em}(5.7\hspace{0.17em}±\hspace{0.17em}0.4)}& \text{−\hspace{0.17em}(3.9\hspace{0.17em}±\hspace{0.17em}0.5)}\\ Q_{\mathrm{xx}}& \text{−\hspace{0.17em}(3.7\hspace{0.17em}±\hspace{0.17em}0.7)}& \text{+\hspace{0.17em}(2.4\hspace{0.17em}±\hspace{0.17em}0.5)}& \text{+\hspace{0.17em}(3.0\hspace{0.17em}±\hspace{0.17em}0.3)}& \text{+\hspace{0.17em}(1.9\hspace{0.17em}±\hspace{0.17em}0.3)}\\ Q_{\mathrm{yy}}& \text{−\hspace{0.17em}(0.2\hspace{0.17em}±\hspace{0.17em}0.5)}& \text{−\hspace{0.17em}(0.9\hspace{0.17em}±\hspace{0.17em}0.4)}& \text{−\hspace{0.17em}(1.7\hspace{0.17em}±\hspace{0.17em}0.4)}& \text{−\hspace{0.17em}(4.1\hspace{0.17em}±\hspace{0.17em}0.4)}\\ Q_{\mathrm{zz}}& \text{+\hspace{0.17em}(3.9\hspace{0.17em}±\hspace{0.17em}1.1)}& \text{−\hspace{0.17em}(1.5\hspace{0.17em}±\hspace{0.17em}0.8)}& \text{−\hspace{0.17em}(1.3\hspace{0.17em}±\hspace{0.17em}0.5)}& \text{+\hspace{0.17em}(2.2\hspace{0.17em}±\hspace{0.17em}0.6)}\end{array}$$ The diagonal elements in the paramagnetic susceptibility tensor and the anisotropies in second moment of the electronic charge distributions are computed from the above results and the known molecular structures. The above results are used along with additivity relations for the second moment of the electronic charge distribution to give estimates of the diamagnetic and total magnetic susceptibility tensor elements.