The Reactions of Oxotitanium(IV) Tetraphenylporphyrin with Methyl Methacrylate Radicals: A DFT Study

A theoretical analysis of potential reactions between oxotitanium(IV) tetraphenylporphyrin with methyl methacrylate radicals was made.The structures of possible products were calculated and the energies of their formation were estimated.The oxotitanium(IV) tetraphenylporphyrin ((TPP)Ti=O) and the CH 3 -CH 2 -C • (CH 3 )(C(O)OCH 3 ) radical, which simulated a poly(methyl methacrylate) propagating radical, were used as the model particles for quantumchemical calculations.It has been shown that addition of the radical to the titanium atom does not occur, among other reactions the addition of radical to the O atom (extraligand) is the most likely process.As a result, the metal-centered radical (TPP)Ti • -O-R is formed, which can act as a trap for other methyl methacrylate radicals.Such radical addition occurs on the opposite side from the extraligand.In the (TPP)Ti(OR)(R) product, the radical is added to the titanium atom not by the C atom but by the O atom of the carbonyl group.Furthermore, it has been shown that β-H transfer does not occur with participation of the titanium atom belonging to (TPP)Ti=O, but is principally possible with involvement of the extraligand.The β-H transfer involving the titanium atom in (TPP)Ti • -O-R is energetically unfavorable.