title: Vanadium(V) compounds with the bis-(hydroxylamino)-1,3,5-triazine ligand, H2bihyat: synthetic, structural, and physical studies of [V2(V)O3(bihyat)2] and of the enhanced hydrolytic stability species cis-[V(V)O2(bihyat)]-.
abstract: Reaction of the ligand 2,6-bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine (H(2)bihyat) with NaV(V)O(3) in aqueous solution followed by addition of either Ph(4)PCl or C(NH(2))(3)Cl, respectively, gave the mononuclear vanadium(V) compounds Ph(4)P[V(V)O(2)(bihyat)].1.5H(2)O (1) and C(NH(2))(3)[V(V)O(2)(bihyat)] (2). Treatment of V(IV)OSO(4).5H(2)O with the ligand H(2)bihyat in methyl alcohol under specific conditions gave the oxo-bridged dimer [V(V)(2)O(2)(mu(2)-O)(bihyat)(2)] (3). The structures for 1 and 3 were determined by X-ray crystallography and indicate that these compounds have distorted square-pyramidal arrangement around vanadium. The ligand bihyat(2-) is bonded to vanadium atom in a tridentate fashion at the pyridine-like nitrogen atom and the two deprotonated hydroxylamino oxygen atoms. The high electron density of the triazine ring nitrogen atoms, which results from the resonative contribution of electrons of exocyclic nitrogen atoms (Scheme 4 ), leads to very strong V-N bonds. The cis-[V(V)O(2)(bihyat)](-) species exhibits high hydrolytic stability in aqueous solution over a wide pH range, 3.3-11.0, as it was evidenced by (1)H and (51)V NMR spectroscopy and potentiometry. The high affinity of the H(2)bihyat ligand for the V(V)O(2)(+) unit, its tridentate character, as well as its small size, paves the way for potential applications in medicine, analysis, and catalysis for the C(NH(2))(3)[V(V)O(2)(bihyat)] compound. The molecular structures, vibrational and electronic spectra, and the energetics of the metal-ligand interaction for compounds 1 and 3 have been studied by means of density functional calculations.
authors.affiliation: Department of Chemistry, Section of Inorganic and Analytical Chemistry, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Vladimiros A
authors.initials: VA
authors.lastname: Nikolakis
authors.forename: John T
authors.initials: JT
authors.lastname: Tsalavoutis
authors.forename: Marios
authors.initials: M
authors.lastname: Stylianou
authors.forename: Evgenios
authors.initials: E
authors.lastname: Evgeniou
authors.forename: Tamas
authors.initials: T
authors.lastname: Jakusch
authors.forename: Artem
authors.initials: A
authors.lastname: Melman
authors.forename: Michael P
authors.initials: MP
authors.lastname: Sigalas
authors.forename: Tamas
authors.initials: T
authors.lastname: Kiss
authors.forename: Anastasios D
authors.initials: AD
authors.lastname: Keramidas
authors.forename: Themistoklis A
authors.initials: TA
authors.lastname: Kabanos
mesh_terms: D018360:Crystallography, X-Ray; D004355:Drug Stability; D006868:Hydrolysis; D006898:Hydroxylamines / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure; D009025:Morpholines / Q000737:chemistry; D012995:Solubility; D014227:Triazines / Q000737:chemistry*; D014638:Vanadates / Q000737:chemistry; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D006898:Hydroxylamines; D008024:Ligands; D009025:Morpholines; D014227:Triazines; D017968:Vanadium Compounds; D014638:Vanadates