title: Aqueous V(V)-peroxo-amino acid chemistry. Synthesis, structural and spectroscopic characterization of unusual ternary dinuclear tetraperoxo vanadium(V)-glycine complexes.
abstract: Vanadium participation in cellular events entails in-depth comprehension of its soluble and bioavailable forms bearing physiological ligands in aqueous distributions of binary and ternary systems. Poised to understand the ternary V(V)-H(2)O(2)-amino acid interactions relevant to that metal ion's biological role, we have launched synthetic efforts involving the physiological ligands glycine and H(2)O(2). In a pH-specific fashion, V(2)O(5), glycine, and H(2)O(2) reacted and afforded the unusual complexes (H(3)O)(2)[V(2)(O)(2)(mu(2):eta(2):eta(1)-O(2))(2)(eta(2)-O(2))(2)(C(2)H(5)NO(2))] x 5/4 H(2)O (1) and K(2)[V(2)(O)(2)(mu(2):eta(2):eta(1)-O(2))(2)(eta(2)-O(2))(2)(C(2)H(5)NO(2))] x H(2)O (2). 1 crystallizes in the triclinic space group P1, with a = 7.805(4) A, b = 8.134(5) A, c = 12.010(7) A, alpha = 72.298(9) degrees, beta = 72.991(9) degrees, gamma = 64.111(9) degrees, V = 641.9(6) A(3), and Z = 2. 2 crystallizes in the triclinic space group P1, with a = 7.6766(9) A, b = 7.9534(9) A, c = 11.7494(13) A, alpha = 71.768(2) degrees, beta = 73.233(2) degrees, gamma = 65.660(2) degrees, V = 610.15(12) A(3), and Z = 2. Both complexes 1 and 2 were characterized by UV/visible, LC-MS, FT-IR, Raman, NMR spectroscopy, cyclic voltammetry, and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium-tetraperoxo-glycine complexes containing [(V(V)=O)(O(2))(2)](-) units interacting through long V-O bonds and an effective glycinate bridge. The latter ligand is present in the dianionic assembly as a bidentate moiety spanning both V(V) centers in a zwitterionic form. The collective physicochemical properties of the two ternary species 1 and 2 project the chemical role of the low molecular mass biosubstrate glycine in binding V(V)-diperoxo units, thereby stabilizing a dinuclear V(V)-tetraperoxo dianion. Structural comparisons of the anions in 1 and 2 with other known dinuclear V(V)-tetraperoxo binary anionic species provide insight into the chemical reactivity of V(V)-diperoxo species in key cellular events such as insulin mimesis and antitumorigenicity, potentially modulated by the presence of glycinate and hydrogen peroxide.
authors.affiliation: Laboratory of Inorganic Chemistry, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Gabriel
authors.forename: M
authors.initials: M
authors.lastname: Kaliva
authors.forename: J
authors.initials: J
authors.lastname: Venetis
authors.forename: P
authors.initials: P
authors.lastname: Baran
authors.forename: I
authors.initials: I
authors.lastname: Rodriguez-Escudero
authors.forename: G
authors.initials: G
authors.lastname: Voyiatzis
authors.forename: M
authors.initials: M
authors.lastname: Zervou
authors.forename: A
authors.initials: A
authors.lastname: Salifoglou
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D005998:Glycine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014638:Vanadates / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; C069276:peroxovanadate; D014638:Vanadates; D005998:Glycine