The metastable CH2I-I and CHI2-I isomers formed by UV photolysis of CH2I2, and CHI3 transfer methylene and iodomethylene groups, respectively, to a variety of cycloalkenes, leading to their cyclopropanation. More than a 100-fold increase of the reaction rate with increasing solvent polarity suggests a dipolar transition state. The fastest second-order rates observed were in CH3CN. However, CH2Cl2 will be the more appropriate reaction medium because the isomer thermal stability is greater in CH2Cl2 than in the more polar CH3CN.
Tarnovsky, Alexander N.; Pascher, Irmin; and Pascher, Torbjorn, "Reactivity Of Iso-diiodomethane And Iso-iodoform, Isomers Of Ch2i2 And Chi3, Toward The Double Bond Of A Variety Of Cycloalkenes" (2007). Chemistry Faculty Publications. 99.
Journal Of Physical Chemistry A