The mechanism of dissociative electron transfer (ET) to a series of organic chlorides has been investigated both at an inert electrode and at a catalytic surface such as Ag; electrocatalysis is important only when breaking of the carbon–halogen bond is concerted with the ET.

Two new cyclometallated platinum(II) complexes have been prepared that incorporate a terdentate N^C^N-coordinating ligand and a monodentate acetylide co-ligand. The complexes, namely [PtL³–CC–C₆H₃F₂] and [PtL⁶–CC–C₆H₃F₂] (where HL³ = 5-methyl-1,3-di(2-pyridyl)benzene; HL⁶ = 5-mesityl-1,3-di(2-pyridyl)benzene; H–CC–C₆H₃F₂ = 3,5-difluorophenylacetylene), were prepared by ligand metathesis from the corresponding chloro complex PtLⁿCl. Both of the new complexes are intensely luminescent in solution, displaying quantum yields superior to PtLⁿCl. OLEDs have been prepared using the new compounds as phosphorescent emitters. Although both lead to efficient devices, the best electroluminescence quantum efficiencies are obtained with the derivative of HL⁶, having the mesityl group on the cyclometallated phenyl ring. The superior performance with this complex can be rationalised in terms of the greater steric hindrance that serves to reduce aggregate-induced quenching.