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On the Geometrical Stability of Square‐Planar Platinum(0) Complexes That Bear a PNP‐Pincer‐Type Phosphaalkene Ligand (Eind 2 ‐BPEP)
Author(s) -
Taguchi Hiroomi,
Tanigawa Ippei,
Takeuchi Katsuhiko,
Ozawa Fumiyuki
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803097
Subject(s) - pincer movement , pincer ligand , ligand (biochemistry) , pyridine , planar , chemistry , crystallography , coordination geometry , materials science , molecule , medicinal chemistry , computer science , organic chemistry , biochemistry , receptor , computer graphics (images) , catalysis , hydrogen bond
The four‐coordinate Pt 0 complex [Pt(PPh 3 )(Eind 2 ‐BPEP)] (Eind=1,1,3,3,5,5,7,7‐octaethyl‐1,2,3,5,6,7‐hexahydro‐ s ‐indacen‐4‐yl; BPEP=2,6‐bis(1‐phenyl‐2‐phosphaethenyl)pyridine), which bears a PNP‐pincer‐type phosphaalkene ligand (Eind 2 ‐BPEP; PNP= N , N ‐bis(diphenylphosphine)‐2,6‐diaminopyridine), were found to adopt a square‐planar configuration around the Pt center ( τ 4 =0.11). This coordination geometry is very uncommon for formal d 10 complexes. In this study, a series of ligands with different electronic properties (i.e., DMAP, 2,6‐lutidine, PMe 3 , t BuNC, and CO) were introduced in place of PPh 3 , and their effects on the coordination geometry were examined. X‐ray diffraction analysis revealed that all complexes adopted a square‐planar configuration ( τ 4 =0.20–0.27). In contrast, DFT calculations indicated that the geometrical stability towards distortion around Pt varied with the ligand. The complexes with pyridine‐based ligands had rigid planar structures, whereas those with π‐accepting ligands, such as CO, were relatively flexible towards distortion. The electronic effects of the ligands were reflected in the spectroscopic properties of the complexes, which showed a large color change in the near‐infrared region.