Thermodynamic and reactivity studies of a tin corrole–cobalt porphyrin heterobimetallic complex

A heterobimetallic complex, (TPFC)Sn–Co(TAP) (TPFC = 5,10,15-tris(pentafluorophenyl)corrole, TAP = 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin), was synthesized. The complex featured a Sn–Co bond with a bond dissociation enthalpy (BDE) of 30.2 ± 0.9 kcal mol(–1) and a bond dissociation Gibbs free energy (BDFE) of 21.0 ± 0.2 kcal mol(–1), which underwent homolysis to produce the (TPFC)Sn radical and (TAP)Co(II) 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)Sn–Co(TAP) promoted the oligomerization of aryl alkynes to give the insertion products (TPFC)Sn–(CH[double bond, length as m-dash]C(Ar))(n)–Co(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.