Preface

Both selenium and tellurium are very rare. Selenium has an abundance at 0.05–0.09 parts per million and is among the 25 least common elements in the Earth’s crust. Tellurium is even rarer with an abundance of about one part per billion being rarer than gold, silver, or platinum and ranks about 75th in abundance of the elements in the earth. Selenium is used in glass-making and in electronics. One of the most common uses is in plain-paper photocopiers and laser printers. Selenium is also used to make photovoltaic (“solar”) cells. Most of the tellurium produced today is used in alloys such as tellurium-steel alloy (approx. 0.04% tellurium), which has better machinability than steel without tellurium. Tellurium has potential for a variety of electrical devices such as CdHgTe IR detectors and it can be used to improve picture quality in photocopiers and printers. Recent decades have witnessed significant progress in the chemistry of selenium and tellurium. New compounds with novel bonding arrangements, unprecedented structures, and unusual reactivities have been reported comprising in many cases systems which have been regarded as impossible. Such development extends the theories on molecular structures and bonding. The driving force in the research of inorganic and organic chemistry of selenium and tellurium chemistry also arises from demands of materials science and from advances in biochemistry and medicine. There is an ever-growing need to gain firm understanding of the relationship of molecular and electronic structures with the properties and functionalities observed in the bulk phase. As a result of these investigations, both new and old materials are finding virtually unlimited number of applications. Semiconductors, insulators, coatings, ceramics, catalysts, nanotubes, polymers, and thin films all play a significant role in the current main group chemistry research as well as in the modern technological society. In this context, the increasing need for replacements for fossil fuels has driven forward the development of alternative energy sources in which selenium and tellurium compounds such as cadmium telluride are poised to play an important role. Many selenium and tellurium compounds have also found utility as reagents in synthetic organic and inorganic chemistry. Many selenium species can act as mild oxidants