Syntheses and Properties of Tin‐Containing Conjugated Heterocycles

Abstract

Heterocycles that contain tin atoms can be aromatic in a similar sense to well-known aromatic compounds such as benzene or thiophene, but such examples are rare. However, due to the low-lying σ*-orbitals of the tin-substituent bond in stannoles, they are capable of σ*-π* conjugation in a way that is exclusive to heavier element containing heterocycles. This makes stannoles very interesting alternatives for purely organic heterocycles in material applications, in which optoelectronic properties are of interest. This Concept article will highlight the synthesis, reactivity and physical properties of stannoles and related fluorenostannoles. At first, a brief introduction to different types of tin-containing heterocycles is presented, followed by a discussion on different approaches to prepare stannoles, their reactivity and their physical properties. In addition, the first stannole-containing polymer will be reviewed.

Recent Synthetic and Catalytic Applications of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes

“…In addition to being highly selective, Cp 2 Zr(py)(η 2 ‐btmsa) tolerates functional groups. This was shown by Staubitz and co‐workers for the case of tin containing conjugated hetrocycles for the synthesis of a polymer containing stannole units in the main chain . The bis(thienyl) substituted octadiyne was converted in an intermolecular coupling reaction to the zirconacyclopentadiene with the iodide substituents remaining intact.…”

Synthesis, Structure, Thermal Behavior and cis/trans Isomerization of 2,2′-(EMe3)2 (E = C, Si, Ge, Sn) Substituted Azobenzenes

“…However, size is not the only change; optophysical properties can also be influenced substantially. For example, it has been shown that for cyclopentadiene analogs, in which the sp 3 substituted C atom is replaced by a heavier group 14 element, the HOMO-LUMO gap (HOMO = highest occupied molecular orbital; LUMO = lowest unoccupied molecular orbital) is reduced due to σ*-π* conjugation [2,3,4,5,6]. Due to our interest in both main group chemistry and photoswitchable molecules, we systematically investigated the influence that could be exerted by tetrels in the ortho -position of azobenzenes, as well as the structural influences this substitution might trigger: Azobenzenes are thermally and photochemically stable molecular switches that can undergo a reversible trans – cis isomerization under illumination.…”

Synthesis of Stannole‐Containing π‐Conjugated Polymers by Post‐Element Transformation of Organotitanium Polymer

“…In fact, π‐conjugated polymers containing silole units are reported to exhibit remarkably low LUMO energy levels which enable their potential application to the electron‐transporting layers in the electroluminescence (EL) devices . Heteroles containing heavier group 14 elements such as germole and stannole are also expected to serve as electron‐accepting building blocks through the analogous σ*‐π* orbital interactions . Nevertheless, within the knowledge of the authors, only one preceding work on the synthesis of a stannole‐containing π‐conjugated polymer has been described by Staubitz and coworkers, in which a 1,1‐diphenylstannole‐containing polymer was obtained by the Stille coupling reaction of a relatively stable 1,1‐diphenylstannole‐containing aryl diiodide with a distannylthiophene and the resulting polymer exhibits a relatively narrow band gap (1.7 eV) in film .…”