Description:
<jats:title>Abstract</jats:title><jats:p>The initial photochromic reaction of dithizonatophenylmercury(II) in solution was investigated by femtosecond transient absorption spectroscopy. Ultrafast excitation within less than 100 fs caused a radiationless photoreaction with a time constant of 1.5 ps, which is interpreted as CN isomerization through a conical intersection. The orthogonally twisted intermediate state was observed through its excited‐state absorption. Bifurcation along pathways towards the ground states of the orange <jats:italic>cis</jats:italic> and blue <jats:italic>trans</jats:italic> configurations occurs below the funnel of the conical intersection. The photochromism of the title compound in a very polar solvent such as methanol is observed for the first time.</jats:p>