The S-0 <-> S-1 spectra of the mild charge-transfer (CT) complexes perylene.tetrachloroethene (P center dot 4ClE) and perylene center dot(tetrachloroethene)(2) (P center dot(4ClE)(2)) are investigated by two-color resonant two-photon ionization (2C-R2PI) and dispersed fluorescence spectroscopy in supersonic jets. The S-0 -> S-1 vibrationless transitions of P center dot 4ClE and P center dot(4ClE)(2) are shifted by delta nu = -451 and -858 cm(-1) relative to perylene, translating to excited-state dissociation energy increases of 5.4 and 10.3 kJ/mol, respectively. The red shift is similar to 30% larger than that of perylene-trans-1,2-dichloroethene; therefore, the increase in chlorination increases the excited-state stabilization and CT character of the interaction, but the electronic excitation remains largely confined to the perylene moiety. The 2C-R2PI and fluorescence spectra of P center dot 4ClE exhibit strong progressions in the perylene intramolecular twist (1a(u)) vibration (42 cm(-1) in S-0 and 55 cm(-1) in S-1), signaling that perylene deforms along its twist coordinate upon electronic excitation. The intermolecular stretching (T-z) and internal rotation (R-c) vibrations are weak; therefore, the P center dot 4ClE intermolecular potential energy surface (IPES) changes little during the S-0 <-> S-1 transition. The minimum-energy structures and inter- and intramolecular vibrational frequencies of P center dot 4ClE and P center dot(4ClE)(2) are calculated with the dispersion-corrected density functional theory (DFT) methods B97-D3, omega B97X-D, M06, and M06-2X and the spin-consistent-scaled (SCS) variant of the approximate second-order coupled-cluster method, SCS-CC2. All methods predict the global minima to be pi-stacked centered coplanar structures with the long axis of tetrachloroethene rotated by tau approximate to 60 degrees relative to the perylene long axis. The calculated binding energies are in the range of -D-0 = 28-35 kJ/mol. A second minimum is predicted with tau approximate to 25 degrees, with similar to 1 kJ/mol smaller binding energy. Although both monomers are achiral, both the P center dot 4ClE and P center dot(4ClE)(2) complexes are chiral. The best agreement for adiabatic excitation energies and vibrational frequencies is observed for the omega B97X-D and M06-2X DFT methods.