Palladium(II) Complexes of the Hemilabile Pincer Ligand PPh( o ‐C 6 H 4 SMe) 2 as Highly Active and Recyclable Mizoroki–Heck Catalysts

Pd II complexes with PPh( o ‐C 6 H 4 SMe) 2 acting as a pincer ligand in an S , S ′, P ‐ or S , P ‐coordination mode have been synthesized. The complexes include [PdCl 2 {PPh( o ‐C 6 H 4 SMe) 2 }] ( 1 ), [Pd(Me)Cl{PPh( o ‐C 6 H 4 SMe) 2 }] ( 2 ), and [Pd(X){PPh( o ‐C 6 H 4 SMe) 2 }]A [A = CF 3 SO 3 , X = Cl ( 3 ); A = CF 3 SO 3 , Me ( 4 ); A = PF 6 , X = Me ( 5 )]. Insertion of CO into the Pd–Me bond of these complexes leads to [Pd(COMe)Cl{PPh( o ‐C 6 H 4 SMe) 2 }] ( 6 ) and [Pd(COMe){PPh( o ‐C 6 H 4 SMe) 2 }]A [A = CF 3 SO 3 ( 7 ); A = PF 6 ( 8 )]. Some of these complexes are good Mizoroki–Heck catalysts (for the reactions between iodobenzene and methyl acrylate or styrene). The most active catalyst was found to be [Pd(Me)Cl{PPh( o ‐C 6 H 4 SMe) 2 }] ( 2 ). This catalyst could be retained on a silica gel column, recovered, and reused several times without losing activity.