Photoinitiation of polymerization of styrene by oxotris(dimethyl dithiocarbamato) vanadium(V)

Oxotris(dimethyl dithiocarbamato) vanadium(V) [VO(S 2 CN(CH 3 ) 2 ) 3 ] sensitizes the polymerization of styrene when irradiated by light of λ = 365 nm at 25°C. Under the experimental conditions employed, no retardation occurs, and the rate of initiation is independent of monomer concentration. The mean values of the quantum yield of iniiation (ϕ i ) and polymerization (ϕ o ) are 2.85 × 10 −3 and 6.72 respectively. Spectroscopic analysis shows that initiation occurs predominatly through scission of the N , N ‐dimethyl dithiocarbamate ligand (—SC(S)N(CH 3 ) 2 ) with reduction of vanadium(V) to (IV), and VO (S 2 CN(CH 3 ) 2 ) 2 is the final photolytic product. A reaction mechanism is proposed based on an intramolecular photoredox reaction which leads to the primary formation of SC(S)N(CH 3 ) 2 radicals and a vanadium(IV) chelate complex. The rellevant kinetic parameters are evaluated. The polystyrene produced shows a photoactivity when irradiated with UV‐light.