Nascent laser-ablated lanthanide metal ions, Ln + , were reacted with cyclohexacarbons, C 6 H 6+2n (n ) 0, 1, 2, or 3), and the resulting organometallic complex ions, {Ln + }-{C p H q }, were identified by time-of-flight mass spectrometry. Cyclohexane and cyclohexadiene were especially reactive, primarily undergoing one or more dehydrogenations to produce adduct ions corresponding to the benzene and benzyne complexes, {Ln + }-{C 6 H 6 } and {Ln + }-{C 6 H 4 }. Also identified as minor products were the "sandwich" complexes, {C 6 H 6 }-{Ln + }-{C 6 H 6 }. Carbon-carbon bond activation was generally an unimportant reaction channel, with small yields of {Ln + }-{C p H q } for p e 5. Significant differences were observed in product yields and distributions between the several Ln + studied, providing the following comparative reactivities: Ce unreactive]. These differences are explained by the metal ion ground state electronic configurations (typically 4f n-1 6s 1 ) and promotion energies (PE) for excitation of a (nonbonding) 4f electron to a valence 5d orbital. For example, upon reaction with 1,3-cyclohexadiene, Eu + (PE ) 394 kJ mol -1 ) was virtually inert while Tb + (PE ) 38 kJ mol -1 ) produced abundant Tb + ‚{C 6 H 6 }. The distinctive Ln + reactivities indicate that most ablated Ln + were in the ground or a low-lying (j0.3 eV) electronic state. Contrasting the reactivities of two or more Ln + co-ablated from a multicomponent target circumvented effects of experimental variables and provided especially reliable comparative reactivities. In addition to the primary chemical effects, variations in product abundances with ion velocity indicated enhanced H 2 loss for high-energy ion-molecule collisions.