Ruthenium\nComplexes Bearing a Tetradentate Hemilabile\nLigand: Synthesis, Structure, Hemilabile Feature, and Catalytic Application\nto C–H Borylation of Unactivated Arenes

Ruthenium complexes bearing a rationally designed tetradentate\nhemilabile ligand have been developed. The structures of the complexes\nand the hemilabile feature of the ligand have been disclosed by X-ray\ncrystallography and NMR analyses. Moreover, in a ruthenium-catalyzed\nC(sp<sup>2</sup>)–H borylation of unactivated arenes, such\na type of complex was found to show superior catalytic reactivity\ncompared to tetradentate or tridentate phosphine ligands, which suggested\nthat the hemilabile feature of the ligand is the key factor in promoting\nthe reaction efficiently.