Synthesis and characterization of an oxo-bridged rhenium(V) complex with an amine-phenol tetradentate ligand

The oxo-bridged dinuclear complex [(μ-O){ReO(sal2hpn)}2].EtOH was prepared by the reaction of trans-[ReOCl3(PPh3)2] with N,N’-propylenebis(salicylideneamine) (H2sal2hpn) in ethanol. An X-ray crystallographic study showed that each sal2hpn is coordinated as a tetradentate dianionic chelate. The axis of the molecule is formed by the O=Re-O-Re=O moiety, with the average O=Re-O and Re-O-Re bond angles equal to 165.2(2)° and 164.8(2)° respectively. The average Re=O bond equals 1.697(5) Å, and the Re-O bonds have an average length of 1.928(4) Å. The structure has a monoclinic space group Cc with a = 13.7747(2) Å, b = 26.8715(4) Å, c = 9.6478(1) Å, β = 92.4202(9)°, V = 3567.92(8) Å3 and Z = 4.   KEY WORDS: Oxo-bridge, Rhenium(V), Dimeric, Crystal structure  Bull. Chem. Soc. Ethiop. 2007, 21(1), 83-88.

Synthesis of a ‘4+1’ Re(V) complex from Re(III), and its disproportionation to Re(IV) and Re(VII)

The distorted octahedral oxorhenium(V) complex [ReOCl(had)] (1) (H2had = N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl)dimethylamine) was prepared from the oxidation of [ReCl3(MeCN)(PPh3)2] by dioxygen in the presence of H2had in ethanol. This reaction was done under reflux conditions for a relatively short reaction time of an hour. However, increasing the reaction period to seven days led to the disproportionation of 1 to [ReIVCl(had)(PPh3)](ReVIIO4) (2). Both compounds were characterized by infra-red spectroscopy and X-ray crystallography. KEY WORDS: Oxidation, Rhenium(III), Oxorhenium(V), Disproportionation, X-ray structures  Bull. Chem. Soc. Ethiop. 2010, 24(3), 411-416

Complexes of Rhenium(V) with Aminoacetopehenones and their Reactions with some Bidentate Ligands

Complexes of rhenium(V) with 2-, 3- and 4-aminoacetophenone (H2aap) have been synthesized. The reaction of trans-ReOCl3(PPh3)2 with 2-H2aap in benzene yielded the imido complex [Re(2-aap)Cl3(PPh3)], in which the oxo oxygen and one of the PPh3 groups were substituted by the dianionic imido nitrogen and the neutral ketonic oxygen, respectively. With 3- and 4-H2aap the imido complexes trans-[Re(aap)Cl3(PPh3)2] were isolated. The monodentate coordination mode of these latter two ligands was authenticated by the X-ray crystal structure of trans-[Re(3-aap)Cl3(PPh3)2]; crystals are triclinic, P1, with a = 10.567(5), b = 11.989(6), c = 18.739(8) Å, α= 74.82(4)º, β= 75.27(4)º, γ= 73.15(4)º, U = 2152(2) Å3, Z = 2, R = 0.0469. The further reaction of [Re(3-aap)Cl3(PPh3)2] with the bidentate ligands 2-aminophenol and 8-hydroxyquinoline (HL) led to the isolation of complexes of the type [Re(3-aap)Cl2(PPh3)(L)]. However, with 1,2-diaminobenzene (H2dab), the 3-aap imido moiety was displaced by the imido group {N(C6H4)NH2}, to give the complex trans-[Re(dab)Cl3(PPh3)2]. (Bulletin of The Chemical Society of Ethiopia: 2002 16 (2): 149-156

<b>Synthesis of a ‘4+1’ Re(V) complex from Re(III), and its disproportionation to Re(IV) and Re(VII)</b>

The distorted octahedral oxorhenium(V) complex [ReOCl(had)] (1) (H2had = N,N-bis(2-hydroxybenzyl)-2-(2-aminoethyl)dimethylamine) was prepared from the oxidation of [ReCl3 (MeCN)(PPh3)2] by dioxygen in the presence of H2 had in ethanol. This reaction was done under reflux conditions for a relatively short reaction time of an hour. However, increasing the reaction period to seven days led to the disproportionation of 1 to [ReIVCl(had)(PPh3)](Re sup>VIIO4) (2). Both compounds were characterized by infra-red spectroscopy and X-ray crystallography