Transition Metal Complexes of 2,6-Dibenzhydryl Derived Bisphosphine: Synthesis, Structural Studies and Palladium Complex Promoted Suzuki-Miyaura Reactions

Transition metal chemistry of [Ar*N(CH2PPh2)2] (1) derived from the sterically demanding backbone 2,6-dibenzhydryl-4-methylphenyl core is described. The reactions of 1 with 30 % aq. H2O2 and S8 afforded bischalcogenides [Ar*N(CH2P(O)Ph2)2] (2) and [Ar*N(CH2P(S)Ph2)2] (3), respectively. Treatment of 1 with [M(COD)Cl2] (M=Pd, Pt) in 1 : 1 molar ratios produced chelate complexes cis-[MCl2{Ar*N(CH2PPh2)2}-κ2-P,P] (4, M=Pd; 5, M=Pt), whereas similar reaction between 1 and [Pd(η3-C3H5)Cl]2 afforded dinuclear complex [{Pd(η3-C3H5)Cl}2{Ar*N(CH2PPh2)2}-κ1-P,P] (6). The reaction of 1 with [Ru(η5-C5H5)Cl(PPh3)2] in 1 : 1 ratio yielded [{Ru(η5-C5H5)Cl}{Ar*N(CH2PPh2)2}-κ2-P,P] (7). Treatment of 1 with [M(C5H11N)2(CO)4] (M=Mo, W) in 1 : 1 molar ratios afforded cis-[M(CO)4{Ar*N(CH2PPh2)2}-κ2-P,P] (8, M=Mo; 9, M=W). The reaction of 1 with copper(I) halides in 1 : 1 molar ratios produced [Cu(μ2-X)]2 dinuclear complexes [{Cu(μ2-X)}2{Ar*N(CH2PPh2)2}2-κ2-P,P}] [10, X=Cl; 11, X=Br; and 12, X=I]. Most of these compounds show various C−H⋅⋅⋅π interactions. Bischalcogenides 2 and 3 showed intramolecular hydrogen bonding type interactions, C−H⋅⋅⋅O (2.554 Å) and C−H⋅⋅⋅S (2.825 Å) between the methylene hydrogens of –NCH2PPh2 groups with O or S atoms, which was also evinced by QTAIM and NCI analysis. Bisphosphine 1 was found to be very effective in palladium catalyzed Suzuki-Miyaura couplings of aryl chlorides with aryl boronic acids.