| Abstract
| - Density functional (DFT) studies and hybrid QM/MM-DFT calculations demonstrate that the presence or absence of attractive π−π stacking interactions distinctly alters the coordination geometry of two exemplary d8 palladium complexes, PdBr(p-NCC6H4)({S}-MeO-Biphep) and PdBr(C6F5)({S}-MeO-Biphep).
- Density functional (DFT) studies and hybrid QM/MM-DFT calculations demonstrate theimportance of π−π stacking interactions in determining the structural features of twoexemplary d8 palladium complexes, PdBr(p-NCC6H4)({S}-MeO-Biphep), 1, and PdBr(C6F5)({S}-MeO-Biphep), 2. Despite the superficial similarity of the two compounds, the formershows marked distortions from square planar geometry, while the latter exhibits an almostideal structure. Attractive π−π stacking interactions between two pairs of P-phenyl ringsand the arene backbone of the MeO-Biphep are the main origin of the distortion in complex1. The planar structure of complex 2 is preferred as a consequence of an additional stackinginteraction between one P-phenyl ring and the pentafluorophenyl σ-ligand. The artificialintroduction of an analogous stacking interaction in complex 1 reestablishes an ideal squareplanar geometry, thus demonstrating that switching on/off specific π−π interactions distinctlyalters the coordination geometry. These results reveal a previously unrecognized role forπ−π stacking interactions in the stabilization of structural features in transition metalcompounds. This suggests π−π stacking interactions as a potential new design principle intailoring coordination compounds.
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