The Structure and Dipole Moment of Isothiocyanic Acid

``Thiocyanic acid'' in the vapor state has been found to be at least 95 percent HNCS. From an analysis of the microwave rotational spectrum the following bond distances and bond angle were determined rH–N=1.01A (assumed), rN–C=1.218A, rC–S=1.557A, H–N–C angle 136°. Analysis of the Stark spectrum indicates that the component of dipole moment along the molecular figure axis is 1.72 D. Stark components from transitions forbidden in the zero-field spectrum have been observed.