Transient Ni(dtc)2(dtc⋅) complex in photochemistry of thiuram disulfide and dithiocarbamate Ni(II) complex solutions

The optical and ESR spectra of the radical complex Ni(dtc)2(dtc⋅) (where Ni(dtc)2 is a flat dithiocarbamate Ni(II) complex), have been recorded in frozen matrices. The dtc⋅ radicals (R2NCS2⋅) were produced by photodissociation of thiuram disulfide molecules (tds≡R2NC(S)S–S(S)CNR2, where R is an alkyl group) at a low temperature close to the melting point of the solvent. Coordination of radicals gives rise to both the optical spectrum with intense absorption bands in the range 200–800 nm and the ESR spectrum with anisotropic g-factor (gxx=2.154, gyy=2.136, and gzz=2.040). For some solvents, forming a polycrystalline matrix upon freezing, the ESR spectrum of the Ni(dtc)2(dtc⋅) complex transforms into a wide singlet line due to the increased local concentration.