Mo(CO)₃(cht) as an air-stable precatalyst for highly Z-selective one-bond isomerization of terminal alkenes

The selective transposition of terminal alkenes to Z-2 alkenes remains a formidable challenge. Here we report that the air stable molybdenum(0) complex 2 (Mo(CO)₃(cht)) serves as a highly efficient precatalyst when combined in a 1:1:1 ratio with tricyclohexylphosphine (PCy₃) and diphenyl phosphate (dpp). Under mild condi-tions (room temperature, 0.2 mol % catalyst) the system delivers >95 % conversion of 1 octene within 1 hour and Z:E ratios exceeding 20:1, outperforming our previously reported Mo(CO)₄(pip)(PCy₃) system. Systematic variation of the phosphine ligand reveals that symmetrical, bulky monodentate phosphines (PCy₃, P(p tolyl)₃) afford the optimal balance of activity and stereocontrol, whereas biaryl phosphines and the less sterically demanding P(Bn)3 give di-minished selectivity. Bidentate ligands (Xantphos, dppf) offer moderate conversion but do not match the 2/PCy₃ benchmark. The catalyst exhibits high turnover numbers (TON > 500) and retains Z selectivity across a broad sub-strate scope, including functionalized alkenes, epoxides, and heteroatom substituted olefins, albeit with reduced effi-ciency for strongly coordinating substrates. Kinetic investigations indicate a zero order dependence on alkene con-centration and an apparent second order dependence on total catalyst concentration, suggesting (a) partial catalyst inhibition or (b) involvement of two catalyst molecules in the same step. Collectively, these findings establish 2/PCy₃/dpp as a general platform for the rapid, highly Z selective isomerization of terminal alkenes and provide mechanistic insight into ligand controlled stereoselectivity in Mo catalyzed alkene migration.