Heavy atom- and deuterim isotope effect in bis-(phenylethinyl)-mercury

The influence of mercury as a heavy atom on the spin orbit coupling is investigated in bis-(phenylethinyl)-mercury and its deuterated derivative. From the experimental results we draw the following conclusions: a) the symmetry of the molecule is D2, b) the large spin orbit coupling of the mercury atom is introduced via dsub(pi) psub(pi)-interaction, c) local sigma pi-transitions and vibronic coupling the fact that the triple bonds act as strong energy acceptors. (orig.)