Synthesis and X-ray crystal structure of an oxorhenium(V) complex with a double Schiff base

Abstract

The reaction of the double Schiff bases, RL, formed from 2,6-diformyl-4-methyl-phenol and p-RC₆H₄NH₂ (R=H, Me, OMe, Cl) with ReOCl₃(PPh₃)₂ afforded red coloured complexes of the type RevOCl₃(RL). The X-ray structure of the R = Me complex (crystal data: ReOCl₃(MeL)·CH₂Cl₂, triclinic, space group PI, a = 8.736(2), B=10.632(3), C=10.575(5)Å, a=104.64(2)°, β=93.22(2)°, γ = 110.57(2)°, V = 1376.6(7) Å, Z =2, R = 3.06%, R_w = 3.51%) revealed meridional chloro coordination in an ReOCl₃(ON) coordination sphere. The RL ligand binds in the bidentate ON mode, the second imine function occurring in the protonated from (N---H···O hydrogen bonding). IR and ¹H NMR data indicate that the solid-state structure is substantially retained in solution. The complexes display a quasi-reversible Re^VIO/Re^VO couple whole potential depends on the R substituent.