Genesis of rare molecules using light-induced reactions of matrix-isolated tetrazoles

Tetrazoles exhibit a very rich photochemistry, strongly influenced by the nature of substituents in the tetrazolic ring. Photolysis of representative tetrazoles trapped in a rigid environment of solidified noble gases at cryogenic temperatures (usually argon at 10-15 K) results in photofragmentation of the monomeric species with a wide range of exit channels. Since the obtained fragments are generally confined to the matrix cage where they are formed, no subsequent cross-reactions involving species resulting from photolysis can occur, strongly reducing the number of possible photoproducts in comparison with gas phase or solution studies. These conditions introduce a useful simplification for the interpretation of the reaction mechanisms and enable spectroscopic characterization of novel and/or highly reactive molecules. In this review, we provide an updated report on the photolysis of matrix-isolated tetrazoles, focusing on the scope and usefulness of this methodology for generation of rare molecules and investigation of photocleavage pathways. Special emphasis is placed on mechanistic interpretations and characterization of rare molecules and on the relevance of conformation and tautomerism on the photochemistry of the studied compounds. (C) 2013 Elsevier B.V. All rights reserved.