Distinct orientations studied for the Pt⋯water systems. (a) Orientations designated for cisplatin (Ddp), (b) monoaquo (Madp) species, and (c) diaquo (Dap) structures. Orthogonal are also denominated set 1 (Ddp-I, Madp-I to IV, Dap-I and Dap-II). Orthogonal Pt⋯HOH are also named set 2 (Ddp-II, Madp-V to VIII and Dap-III to V). The approaches through the platinum plane are named set 3 (Ddp-III to V, Madp-IX to XII and Dap-VI to VIII) and Pt⋯HOH. are denominated set 4 (Ddp-VI to Ddp-VIII, Madp-XIII to XVI and Dap-IX to Dap-XI).
Potential energy curves calculated for the cisplatin-water orientations. △: ; ▲: ; ◼: ; ●: .
Electrostatic energy curves calculated for the cisplatin-water orientations at the level of theory. ●: Mulliken, ▲: CHELPG, and ◼: NBO charges. The solid line is the quantum mechanical PEC.
Electrostatic energy curves calculated for the monoaquo-water and diaquo-water orientations at the level of theory. ●: Mülliken, ▲: CHELPG and ◼: NBO charges. The solid line (—) is the quantum mechanical PEC and the dotted line (⋯) is the PEC with the BSSE correction.
Nonelectrostatic curves calculated for some monoaquo-water and diaquo-water orientations. The curve represents the quantum mechanical potential subtracted from the electrostatic contribution calculated using CHELPG charges. The LJ(12-6) is the Lennard–Jones Potential evaluated with the parameters given in TABLE IV.
Minima located on the MP2 B3LYP and HF potential energy curves for the cisplatin-water system. and (Å).
Minima located on the MP2 potential energy curves for the system. The (⋯) represents a repulsive curve. and (Å).
Minima located on the MP2 potential energy curves for the system. The (⋯) represents a repulsive curve. The repulsive curve for structure Dap-IX, found at all levels of theory was omitted from the table. and (Å).
Intermolecular LJ (12–6) potential parameters for the platinum compounds. Parametrized for cisplatin molecule without BSSE corrections. The TIP3P model (Ref. 38) is used for water: , .
BSSE correction using the counterpoise approach for the minima located on the potential energy curve (PEC) for the cisplatin-water system. The values for the individual contributions are also included.
Estimative of the correlation energy contribution to the MPn and B3LYP interaction energies for the cisplatin-water complex, using the basis set.
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