The Stability of Diphosphino-Boryl PBP Pincer Backbone: PBP to POP Ligand Hydrolysis.

Abstract

Since moisture may frequently be present in many solvents, it is important to know the reactivity of a catalyst against water for catalytic reactions. In order to explore the stability and understand the transformation process of diphosphino-boryl-based PBP pincer platform, [PdCl{B(NCH2 Pt Bu2 )2 -o-C6 H4 }] (1) was treated with PdCl2 , HB(NCH2 PPh2 )2 -o-C6 H4 was reacted with [PdCl2 (cod)] (cod=cyclo-octa-1,5-diene) and [Pd2 (dba)3 ] (dba=dibenzylideneacetone), respectively, in the presence of water. Some novel palladium POP complexes, [Pd2 Cl2 (μ-Cl){μ-κ3 -P,O,P-OB(NCH2 Pt Bu2 )2 -o-C6 H4 }] (2 a), [Pd4 (μ-Cl)2 (μ-O)2 {μ-κ3 -P,O,P-OB(NCH2 PPh2 )2 -o-C6 H4 }2 ] (2 b), [Pd2 {μ-κ4 -P,P,P,P-O(B(NCH2 PPh2 )2 -o-C6 H4 )2 }{μ-κ2 -P,P-(NHCH2 PPh2 )2 -o-C6 H4 }] (3), were obtained. It was found that the PBP pincer backbone can easily be converted into a POP backbone in the presence of water. From the crystal structures of the resultant palladium complexes, possible pincer backbone transformation pathways were discussed.