1,3-Diborata-2,4-diphosphoniocyclobutane-1,3-diyls communicate through a para-phenylene linker

The presence of a second 1,3-diborata-2,4-diphosphoniocyclobutane-1,3-diyl in the para-position of a phenylene linker favors the diradical form over the 1,3-diborata-2,4-diphosphoniobicyclo[1.1.0]butane bond stretch isomer, as long as the two planar diradical units are coplanar with the linker. This demonstrates that two BPBP diradicals communicate through the phenyl ring.     

Topics of 1,3-diphosphacyclobutane-2,4-diyl derivatives: Structural aspects and functionality of isolable heavier congeners of cyclobutane-1,3-diyl and the related molecules

This minireview summarizes recent findings on isolable congeners of cyclobutane-1,3-diyl from the views of structural characters, usefulness for organo electronics, and activation of small molecules. Recent findings on isolable cyclopentane-1,3-diyl, 2,4-dimethylene-1,3-cyclobutanediyl, and cyclobutadiene are also overviewed. This article focuses on the reports on the isolable biradicals that have been published since 2013.     

Valence Isomerization in the Solid State: From 1,3-Diphosphacyclobutane-2,4-diyl to 1,2-Dihydro-1,2-diphosphete

The butadiene-like phosphanylcarbene 2 is, according to ab initio calculations, the intermediate in the conversion of 1 into 3 in the solid state [Eq. (a)]; it is only 1.3 kJ mol⁻¹ higher in energy than 1 . For this conversion, only minor changes in the endocyclic bonds are required throughout the entire reaction. R₂N=2,2,6,6-Me₄C₅H₆N.     

Ring opening of 1-methylcyclopropene and cyclopropene: matrix infrared spectroscopic identification of 2-butene-1,3-diyl and propene-1,3-diyl

Triplet 2-butene-1,3-diyl (T-11) was generated on irradiation of 1-methylcyclopropene (10) in a bromine-doped xenon matrix and was characterized by means of IR spectroscopy for the first time. Experimental results suggest that triplet propene-1,3-diyl (T-3) is formed from cyclopropene (1) under similar conditions. In accordance with theoretical calculations, the experimental data indicate that the reactions 1-->3 and 10-->11 are the lowest energy ground-state pathways for the ring opening of 1 and 10, respectively.     

Valence Isomerization of a 1,3-Diphosphacyclobutane-2,4-diyl: Photochemical Ring Closure to 2,4-diphosphabicyclo[1.1.0]butane and Its Thermal Ring Opening to gauche-1,4-Diphosphabutadiene

The bond stretch isomer 1,3-diphosphacyclobutane-2,4-diyl 1 was transformed photochemically to give the previously unknown 2,4-diphosphabicyclo[1.1.0]butane 2 , which itself can be converted thermally into gauche-1,4-diphosphabutadiene 3 . The crystal structures of these three energy-rich valence isomers of 1,2-diphosphete have been determined. R=SiMe₃; Mes*=2,4,6-tBu₃C₆H₂.     

Reaction of 2,4-Diaryl-1,3-dithia-2,4-diphosphetane-2,4-disulfides with resorcinol

Russian Journal of General Chemistry -