Английская Википедия:1,5-Diaza-3,7-diphosphacyclooctanes
1,5-Diaza-3,7-diphosphacyclooctanes are organophosphorus compounds with the formula [R'NCHШаблон:SubP(R)CHШаблон:Sub]Шаблон:Sub, often abbreviated PШаблон:SupШаблон:SubNШаблон:SupШаблон:Sub. They are air-sensitive white solids that are soluble in organic solvents. The ligands exist as meso and d,l-diastereomers, but only the meso forms function as bidentate ligands.[1][2]
Some metal-PШаблон:SupШаблон:SubNШаблон:SupШаблон:Sub complexes catalyze the hydrogen evolution reaction as well as the oxidation of hydrogen (HШаблон:Sub). The catalytic mechanism involves the interaction of substrate with the amines in the second coordination sphere.[3][4]
Synthesis and reactions
The ligands are prepared by the condensation of a primary phosphine, formaldehyde, and a primary amine:
- 2 RPHШаблон:Sub + 4 CHШаблон:SubO + 2 RNHШаблон:Sub → [RNCHШаблон:SubP(R')CHШаблон:Sub]Шаблон:Sub + 4 HШаблон:SubO
Diazadiphosphacyclooctanes function as chelating diphosphine ligands. Typical nickel complexes contain two such ligands are give the formula [Ni(PШаблон:SupШаблон:SubNШаблон:SupШаблон:Sub)Шаблон:Sub]Шаблон:Sup.
Cationic complexes of these PШаблон:SubNШаблон:Sub and related ligands often exhibit enhanced reactivity toward HШаблон:Sub. These complexes serve as electrocatalysts for HШаблон:Sub production.
Related ligands
Azadiphosphacycloheptanes are a related family of diphosphines, but containing only one amine. They are prepared by condensation of 1,2-bis(phenylphosphino)ethane, formaldehyde, and a primary amine.[5] From the meso-isomer, typical nickel complexes contain two such ligands, i.e. [Ni(PШаблон:SupШаблон:SubNR')Шаблон:Sub]Шаблон:Sup. When bound to metals, these ligands adopt a conformation similar to that of 1,4-diazacycloheptanes. Acyclic phosphine-amine ligands have the formula (RШаблон:SubPCHШаблон:Sub)NR'.
References