A heterobimetallic complex, (TPFC)SnCo(TAP) (TPFC = 5,10,15-tris(pentafluorophenyl)corrole, TAP = 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin), was synthesized. The complex featured a SnCo bond with a bond dissociation enthalpy (BDE) of 30.2 0.9 kcal mol1 and a bond dissociation Gibbs free energy (BDFE) of 21.0 0.2 kcal mol1, which underwent homolysis to produce the (TPFC)Sn radical and (TAP)CoII under either heat or visible light irradiation. The novel tin radical (TPFC)Sn, being the first four-coordinate tin radical observed at room temperature, was studied spectroscopically and computationally. (TPFC)SnCo(TAP) promoted the oligomerization of aryl alkynes to give the insertion products (TPFC)Sn(CHC(Ar))nCo(TAP) (n = 1, 2, or 3) as well as 1,3,5-triarylbenzenes. Mechanistic studies revealed a radical chain mechanism involving the (TPFC)Sn radical as the key intermediate.
Chemical Science – Royal Society of Chemistry
Published: May 16, 2018