7681-91-6Relevant articles and documents
Synthesis and characterization of a VO3+ complex of a pentadentate amine alcohol ligand: Towards hydrolytically stable ligands forming model complexes for vanadium-dependent haloperoxidases
Plass, Winfried
, p. 221 - 229 (1996)
The vanadium(V) complex of a hydrolytically stable trivalent, pentadentate amine alcohol ligand has been synthesized by reaction with ammonium meta-vanadate. The ligand was prepared by reduction of the Schiff base precursor N-salicylidene-2-(bis(2-hydroxyethyl)amino)ethylamine and exhibits an enlarged flexibility as compared to its Schiff base analogue. The vanadium(V) complex is characterized by 1H, 13C and 51V NMR, vibrational (IR, Raman and resonance Raman) and electronic spectroscopy. The LMCT transition of the complex has been assigned on the basis of resonance Raman spectroscopy and density functional calculations (LDA). The X-ray crystal structure analysis of C13H19N2O4V (monoclinic, space group C2/c: a = 1948.1(4), b = 1184.9(2), c = 1328.3(2) pm, β = 114.86(1)°, Z = 8) shows that the vanadium(V) center has a distorted octahedral environment with the oxo group in the trans position to the tertiary amine nitrogen. In the solid state racemic pairs of the vanadium(V) complex are formed by hydrogen bridges (N-H ... O). The bond valence sum (BVS) analysis is applied to the complex prepared in this work and compared with the results obtained for a series of more than twenty relevant six-coordinate complexes. In solution a second isomer with the oxo group trans to the secondary amine nitrogen is observed. The ratio of the two isomers varies with the solvent, as was determined by 51V NMR spectroscopy. The methanolysis as well as hydrolysis reaction of the vanadium(V) complex is studied by 51V NMR. The implications of the results for the proposed model of the active site of vanadium-dependent haloperoxidases are discussed.
A Mixed-Valence VIV/Valkoxo-polyoxovanadium cluster series [V6O8(OCH3)11] n+l-: Exploring the Influence of a μ-Oxo ligand in a spin frustrated structure
Daniel, Charles,Hartl, Hans
, p. 5101 - 5114 (2009/09/30)
The synthesis and structural characterization of the neutral mixed-valence methoxo-polyoxovanadium cluster [V 6 O 8 (OCH 3 ) 11 ] (1) and its single oxidation product in the hexachloroantimonate salt [V 6 O 8 (OCH 3 ) 11 ][SbCl 6 ] (2) are presented here. The cluster comprisesa hexauclear polyoxovanadate core of the Lindqvist structure, of which all but one of the μ-bridging oxo ligands are substituted by methoxo. As revealed by cyclic voltammetry, the cluster is highly redox active, displaying several further thermodynamically stable V IV /VV mixed-valence redox derivatives. Furthermore, valence sum calculations performed on the X-ray structural data as well as results from IR and UV-vis spectrometry characterize them as class II mixed-valence compounds. In the present article, we equally present results from cyclic voltammetry, UV-vis spectrometry, and magnetic measurements obtained formembers of the previously reported [V 6 O 7 (OCH3 ) 12 ] - cluster series, which, as opposed to1 and its derivatives, contain exclusively methoxo ligands as μ-brid ging moieties. Magnetic measurements performed on the highly reduced cluster species [V IV 5 VV 1 O 7 (OCH 3 ) 12 ] - and [V IV 6 VVO 7 (OCH 3 ) 12 ] 2- reveal net antiferromagnetic exchange interactions between the d-electrons, which at lower temperatures are in part suppressed for reasons attributed to geometric spin frustration. Among the present results, the comparison of the cyclic voltammograms of 1 and [V 6 O 7 (OCH 3 ) 12 ] has proven to be of considerable interest, showing an unexpectedly pronounced discrepancy in all but one of their corresponding redox potentials. In particular, a detailed analysis of the electrochemical conversions indicates that the observed shift is almost entirely the result of a different degree of d-electron spin-spin interactions in corresponding mixed valence species of the cluster series.
Binding of L-histidine to vanadium. Structure of exo-[VO2{N-(2-oxidonaphthal)-His}]
Vergopoulos, Vassilios,Priebsch, Wolfgang,Fritzsche, Martina,Rehder, Dieter
, p. 1844 - 1849 (2008/10/08)
The VIV complexes VO(H2O)L (2) (H2L is a Schiff base derived from o-hydroxynaphthalenecarbaldehyde and the amino acids glycine or phenylalanine) react with amines under aerobic conditions to VV complexes of the general composition VO(OH)L(amine) (5) (amine = imidazole, methylimidazole, pyrrole, pyridine, histidine, and histidine derivatives). With alcohols, the complexes VO(OR)L(ROH) (6) are formed. Histidine can also replace glycine in 2, forming the title compound 3 with the histidine moiety coordinating through one of the carboxylate-O moieties. Crystallographic data for 3: [VO2{O2CCH(CH2C3H4N 2)N=CHC10H6O}], space group C2; Z = 4, a = 13.7077(17) ?, b = 6.7390(6) ?; c= 17.1851(15) ?, β = 95.644(8)°, V = 1579.8(3) ?3, R = 0.0325, Rw = 0.0358, 3011 reflections (2916 with I > 2σ(I). The geometry around vanadium is square pyramidal. The two nitrogens of the imidazole unit are linked by intermolecular hydrogen bonds to the carboxylate oxygens and to the oxo group in the tetragonal plane. 3 models several of the active site features for vanadate-dependent haloperoxidases from marine brown algae.
