The excited-state properties of a calcium dicomplex (AM(2)) of 2,5-[bis-[4N-(aza-15-crown-5)phenyl]methylene]cyclopentanone (A) in acetonitrile are investigated by ultrafast absorption spectroscopy. Spectroscopic evidence of an ultrafast cation decoordination following subpicosecond excitation of the chromophore is given. A global analysis of the time-resolved data is performed, and a kinetic scheme is tentatively proposed, which quantitatively describes the dynamics of the deactivation pathway of the AM(2) dicomplex. A first step would involve the disruption of one of the two nitrogen-calcium bonds at a rate constant of 4 x 10(11) s(-1), followed by the diffusion of the cation out of the crown at a rate of 5.8 x 10(10) s(-1). The resulting AM complex would then relax both to its ground state (5.4 x 10(8) s(-1)) and to its triplet state (2.8 x 10(8) s(-1)).