C(sp)–H, S–H, and Sn–H Bond Activation with a Cobalt(I) Pincer Complex

This study focuses on the stoichiometric reactions of {2,6-(ⁱPr₂PO)₂C₆H₃}Co(PMe₃)₂ with terminal alkynes, thiols, and tin hydrides as part of an effort to develop catalytic, two-electron processes with cobalt. This specific Co(I) pincer complex proves to be effective for cleaving the C(sp)–H, S–H, and Sn–H bonds to give oxidative addition products with the general formula {2,6-(ⁱPr₂PO)₂C₆H₃}CoHX(PMe₃) (X = alkynyl, thiolate, and stannyl groups) along with the free PMe₃. These reactions typically reach completion when the substituents on acetylene, sulfur, and tin are electron-withdrawing groups (e.g., phenyl, pyridyl, and alkenyl groups). In contrast, alkyl-substituted acetylenes, 1-pentanethiol, and tributyltin hydride are partially converted due to the equilibria with the corresponding oxidative addition products. The Co(I) pincer complex is not a hydrothiolation catalyst but capable of catalyzing the hydrostannation of terminal alkynes with Ph₃SnH to produce β-(Z)-alkenylstannanes selectively.