Semiclassical and quantum mechanical studies of bound and resonance states for the model H-C-C → H + C=C Hamiltonian are compared. Excellent agreement is found between the semiclassical and quantum mechanical bound-state eigenvalues and resonance positions. The close-coupling and stabilization graph with analytic continuation methodologies are used for the quantum calculations, and they give resonance positions and widths which are in good agreement. Resonance lifetimes vary by 5 orders of magnitude within a 1 kcal/mol energy interval. A correspondence between quasi-periodic/chaotic classical motion and regular/irregular quantum states is found for both bound and resonance states.