Unexpected Synthesis of an Unsymmetrical mu-Oxido Divanadium(V) Compound through a Reductive Cleavage of a N-O Bond and Cleavage-Hydrolysis of a C-N Bond of an N,N-Disubstituted Bis-(hydroxylamino) Ligand (Journal article)

Nikolakis, V. A./ Stathopoulos, P./ Exarchou, V./ Gallos, J. K./ Kubicki, M./ Kabanos, T. A.

Reaction of the N,N-disubstituted bis-(hydroxylamino) ligand 2,6-bis [hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine, H(2)bihyat, with V(IV)OSO(4)center dot 5H(2)O in water for 6 h followed by the addition of methyl alcohol resulted in the isolation of the unsymmetrical mu-oxido divanadium(V) compound [V(2)(V)O(2)(mu(2)-O)(bihyat)(hyta)(hyto)]center dot 3H(2)O (1 center dot 3H(2)O) and of the methylhydroxylamido derivative [V(V)O(bihyat)(CH(3)NHO)]center dot H(2)O (2 center dot H(2)O). The N,N-disubstituted mono(hydroxylamino) ligands Hhyta, Hhyto, and CH(3)NHOH were formed by the decomposition of the ligand H(2)bihyat in the presence of vanadium. The structures of compounds 1 center dot 3H(2)O and 2 center dot H(2)O were determined by X-ray crystallography. The structure of 1 center dot 3H(2)O consists of one five-coordinate vanadium(V) atom and one six-coordinate vanadium(V) atom bridged by an oxido group and ligated to a tridentate bihyat(2-) and two bidentate hyta(-) and hyto(-) ligands, respectively. The two terminal oxido groups in 1 center dot 3H(2)O are syn-directed, lying on the same side of the V-O-V plane. The coordination environment of the vanadium atom in 2 center dot H(2)O approximates to a highly distorted pentagonal pyramid with the oxido ligand occupying the apical position. Compounds 1 center dot 3H(2)O and 2 center dot H(2)O were studied by multinuclear NMR ((1)H, (13)C, and (51)V) to elucidate their solution structures. The (51)V NMR of 1 center dot 3H(2)O in anhydrous CD(2)Cl(2) gave two signals at -199 and -508 ppm, which were assigned to the five- and six-coordinate vanadium(V) atoms, respectively. The resonance of the five-coordinate vanadium nucleus, in a field much lower than that expected from Rehder's [Inorg. Chem., 1988, 27, 584-587] referencing scale, was attributed to the low-energy ligand-to-metal charge transfer transition at 605 nm [epsilon(M)=5050 M(-1) cm(-1)] of 1 center dot 3H(2)O according to Pecoraro et al. [J. Am. Chem. Soc., 1992, 114, 9925-9933], Electrospray ionization-mass spectrometry studies were used to follow the decomposition products of H(2)bihyat in the presence of vanadium.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Keywords: vanadium-dependent haloperoxidases,density-functional theory,solid-state,electron-transfer,v-51 nmr,spectroscopic characterization,structural-characterization,pot conversion,active-site,acetic-acid
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/9808
ISSN: 0020-1669
Link: <Go to ISI>://000272935800009
Publisher: American Chemical Society
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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