ABSTRACT
The vast majority of organic molecules contain some or all of these chemical elements. However, sulfur, silicon, and the halogens are also found in organic molecules. This chapter discusses the infrared spectra of these molecules. There are a variety of organic functional groups that contain sulfur. Sulfur is commonly found bonded to one, two, three, or four oxygen atoms, and each of these structural units gives rise to a set of functional groups. The thiol functional group contains S-H and C-S single bonds. Thiols are the 'sulfur analog' of alcohols, with the alcohol oxygen being replaced by a sulfur atom. One of the disagreeable properties of thiols is their strong odor. The infrared bands of thiols are usually medium to weak in intensity because of the small dipole moments of C-S and S-H bonds. The most commonly encountered organic molecules that contain silicon atoms are called siloxanes.
