Solution and Solid State Properties of [N-(2-Hydroxyethyl)iminodiacetato]vanadium(IV), -(V), and -(IV/V) Complexes

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• 作者：Mohammad Mahroof-Tahir ; Anastasios D. Keramidas ; Ron B. Goldfarb ; Oren P. Anderson ; Mary M. Miller ; and Debbie C. Crans
• 刊名：Inorganic Chemistry
• 出版年：1997
• 出版时间：April 9, 1997
• 年：1997
• 卷：36
• 期：8
• 页码：1657 - 1668
• 全文大小：364K
• 年卷期：v.36,no.8(April 9, 1997)
• ISSN：1520-510X

文摘

A mononuclear vanadium(IV), a mononuclear vanadium(V),and a binuclear mixed valence vanadium(IV/V)complex with the ligand N-(2-hydroxyethyl)iminodiaceticacid (H₃hida) have been structurallycharacterized.Crystal data for[VO(Hhida)(H₂O)]·CH₃OH(1): orthorhombic;P2₁2₁2₁; a= 6.940(2), b = 9.745(3), c= 18.539(4) Å; Z = 4. Crystal data forNa[V(O)₂(Hhida)₂]·4H₂O(2): monoclinic; P2₁/c;a = 6.333(2), b =18.796(2),c = 11.5040(10) Å; = 102.53(2);Z = 4. Crystal data for(NH₄)[V₂(O)₂(-O)(Hhida)₂]·H₂O(3): monoclinic;C2/c; a = 18.880(2), b= 7.395(2), c = 16.010(2) Å; =106.33(2); Z = 4. The mononuclearvanadium(IV)and vanadium(V) complexes are formed from the monoprotonatedHhida^2- ligand, and their structural andmagneticcharacteristics are as expected for six-coordinate vanadium complexes.An interesting structural feature in thesecomplexes is the fact that the two carboxylate moieties are coordinatedtrans to one another, whereas the carboxylatemoieties are coordinated in a cis fashion in previously characterizedcomplexes. The aqueous solution propertiesof the vanadium(IV) and -(V) complexes are consistent with theirstructures. The vanadium(V) complex waspreviously characterized; in the current study structuralcharacterization in the solid state is provided.X-raycrystallography and magnetic methods show that the mixed valencecomplex contains two indistinguishablevanadium atoms; the thermal ellipsoid of the bridging oxygen atomsuggests a type III complex in the solid state.Magnetic methods show that the mixed valence complex contains afree electron. Characterization of aqueoussolutions of the mixed valence complex by UV/vis and EPR spectroscopiessuggests that the complex may bedescribed as a type II complex. TheHhida^2- complexes have some similarities, butalso some significantdifferences, with complexes of related ligands, such asnitrilotriacetate (nta),N-(2-pyridylmethyl)iminodiacetate(pmida), andN-(S)-[1-(2-pyridyl)ethyl]iminodiacetate(s-peida). Perhaps most importantly, the mixedvalenceHhida^2- complex is significantly less stablethan the corresponding pmida and s-peida complexes of similaroverallcharge but very similar in stability to the nta andV₂O₃³⁺ complexes with highercharges. Thus, there is thepotential for designing stable mixed valence dimers.