Optical and ODMR Studies of Luminescent Halo(dimethylphenylphosphine)gold(I) Crystals

Crystals of {(Me2PhP)AuX} n (Me = methyl; Ph = phenyl; X = Cl, Br, I; n = 2, 3) show emission from two excited states. Both states are assigned a triplet multiplicity, on the basis of their lifetimes and zero-field splittings. The structured, higher energy emission originates at ≈360 nm and has the greater relative intensity at low temperatures. It is assigned as intraligand phosphorescence from a phenyl-localized 3ππ* state. The unstructured, lower energy emission has a peak wavelength that varies in the range 630−730 nm. It is assigned as phosphorescence from the triplet state due to the gold-based σ(p) ← σ*(s,d) excitation. The corresponding singlet state is observed at 290−310 nm. The results of SCF−Xα−SW calculations on the model complexes H3PAuX and (H3PAuX)2 are also presented.