Prototypical phosphorus analogues of ethane: general and versatile synthetic approaches to hexaalkylated P-P diphosphonium cations.

Versatile alkylation reactions give access to symmetric, homoleptic nonsymmetric, and heteroleptic symmetric hexaalkylated 1,2-diphosphonium derivatives as bottleable salts in high yields. A series of 1,2-diphosphonium salts has been isolated and characterized, representing prototypical phosphorus analogues of ethane. Additionally, the solid-state structures for four derivatives have been determined crystallographically. Nonsymmetrically substituted derivatives of 1,2-diphosphonium cations enable the direct observation of 1J(PAPB) coupling constants for two tetracoordinate phosphorus centers. The synthetic approaches promise access to a vast array of derivatives and will provide means to the systematic development of phosphorus analogues of hydrocarbon chemistry.