Novel Sulfonated CNN Pincer Ligands for Facile C−H Activation at a Pt(II) Center

Two novel sulfonated CNN‐pincer ligands 1b and 1c and the corresponding chloro and aqua complexes K[ CNN LPtCl] and CNN LPt(H 2 O), 3b – 3c and 2b – 2c , were prepared and fully characterized including single crystal X‐ray diffraction. Along with the previously described complexes 2a and 3a , the derivatives of a CNN pincer ligand 1a , these complexes form a family of structurally similar compounds where the pincer core rigidity increases in the series 2a (3a) < 2b (3b) < 2c ( 3c ), as deduced from their XRD data. The increased ligand rigidity affects the aqua ligand dissociation energy of the CNN LPt(H 2 O) complexes, as it follows from DFT calculations and as is reflected in the increased reactivity of the aqua complexes 2a , 2b and 2c in processes that involve aqua ligand loss. Among these processes the formation of the presumed dinuclear complexes CNN L 2 Pt 2 and, importantly, catalytic C−D bond cleavage in C 6 D 6 were studied in 2,2,2‐trifluoroethanol solutions. The C−D bond cleavage reactivity was quantified as the rate of H/D exchange between C 6 D 6 and CF 3 CH 2 OH at 80 °C.