Syntheses and characterisation of rhenium-(III) and -(V) complexes containing aminophosphine ligands. Crystal structures of [Re-V(OCl2)(OMe)L] and [Re-III(Cl3L)(PPh3)], L equals o-(diphenylphosphino)-N,N'-dimethylaniline

Substitution reactions of labile rhenium(V) precursors with o-(diphenylphosphino)-N,N?-dimethylaniline, L, gave a series of monooxorhenium(V) complexes of general formula [ReOX2Y(L)] (X = Y = Cl 1; X = Cl, Y = OMe 2) and [ReOX2(OEt)L] (X = Cl 3, Br 4 or 15). These complexes, which contain only one aminophosphine chelate, have a distorted-octahedral geometry, as evidenced by a crystal structure determination of 2. Reactions conducted in basic media, or treatment of 2 in the presence of the weakly co-ordinating trifluoromethanesulfonic acid, gave the bis(chelate) cationic complexes [ReO2L2]+ 6 and [ReCl2L2]+ 7, respectively. Similar ligand-exchange reactions between the lower-oxidation-state precursor [ReIIICl3(MeCN)(PPh3)2] and L or L? [o-(diphenylphosphino)aniline] still produced mono-substituted aminophosphine complexes, i.e. [ReIIICl3L(PPh3)] 8 or [ReIIICl3L?(PPh3)] 9 in which there is a meridional arrangement of chloride ligands along with a cis-phosphorus co-ordination. The crystal structure of 8 was determined: On the contrary, treatment of [ReIIIX3(MeCN)(PPh3)2] (X = Cl or Br) with L? in the presence of co-ordinating hydrohalogenic acid gave bis-substituted cationic complexes [ReX2L?2]+ (X = Cl 10 or Br 11). In spite of the paramagnetism of the low-spin d4 ion, all of the rhenium(III) complexes can be conveniently characterised in solution by proton NMR spectroscopy.