The first rhenium(V)-imido compounds containing two chelating phosphine ligands of the type trans-[Re(NPh)X(L-L)(2)](2+) (L-L equals bidentate phosphine ligand; X equals halide or hydroxide). The structure of trans-[Re(NPh)(OH)(dppbe)(2)](ClO4)(2)center dot 2H(2)O

The bidentate phosphine ligands 1,2-bis(diphenylphosphino)ethane (dppe), 1,2-bis(diphenylphosphino)ethene (dppee) or 1,2-bis(diphenylphosphino)benzene (dppbe) undergo reactions with the rhenium(V)-imido complex, trans-Re(NPh)Cl-3(PPh(3))(2), in refluxing alcoholic solvent to give mixtures of fac-Re(NPh)Cl-3(L-L) and trans-[Re(NPh)X(L-L)(2)](2+). Mild reaction conditions favor the monosubstituted complexes and harsh conditions favor the salts. The electrochemical properties of the salts reveal subtle differences associated with the backbone of the ligands. The structure of the hydroxy-imido salt trans-[Re(NPh)(OH)(dppbe)(2)](ClO4)(2) . 2H(2)O was determined and shows the rhenium atom displaced 0.536(2) Angstrom above the P-4 equatorial plane, the largest displacement observed for rhenium(V) compounds containing pi-donor ligands, and the Re-N(imido) distance of 1.757(10) Angstrom is the longest observed for rhenium(V)-imido compounds.