Synthesis and characterisation of a bulky chelating bis(phosphine) ligand, 1,2-bis(dinbutylphosphino)ethane (DBPE), and its iron metal coordinated complexes, Fe(DBPE)2Cl2 and Fe(DBPE)2(CCC6H5)2

Abstract The synthesis of a bulky chelating bis(phosphine) ligand, 1,2-bis(di n butylphosphino)ethane, n Bu 2 PCH 2 CH 2 P n Bu 2 ( 1 ) (Bu = Butyl = C 4 H 9 ) (DBPE) is reported. This ligand was coordinated to iron by treatment with FeCl 2 to yield Fe(DBPE) 2 Cl 2 ( 2 ) which is an important precursor of a variety of σ-acetylide complexes, e.g. Fe(DBPE) 2 (CCC 6 H 5 ) 2 ( 3 ). Complex 2 is paramagnetic in solution at room temperature and diamagnetic in the solid state. The optical absorption spectrum of 3 shows strong absorptions associated with π-π★ transition of the acetylenic unit.