title: Formation in aqueous solution of a non-oxido V(IV) complex with VN6 coordination. Potentiometric, ESI-MS, spectroscopic and computational characterization.
abstract: The behaviour of the system formed by V(IV)O(2+) ion with all-cis-2,4,6-trimethoxycyclohexane-1,3,5-triamine (tmca) was characterized in aqueous solution through the combined application of electron paramagnetic resonance (EPR) and UV-Vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS), pH-potentiometry and DFT methods. The formation of an unusual non-oxido [V(tmcaH-2)2] species with VN6 coordination, with the ligand in the bianionic form, was demonstrated. The geometry, EPR and UV-Vis spectra and electronic structure of [V(tmcaH-2)2] were simulated with Gaussian 09 and ORCA software and the results were compared with those of similar oxido and non-oxido vanadium(iv) species formed by other polyamine and polyol related ligands, such as 1,3,5-triamino-1,3,5-trideoxy-cis-inositol (taci), 1,3,5-trideoxy-1,3,5-tris(dimethylamino)-cis-inositol (tdci), cis-inositol (ino) and 1,3,5-trideoxy-1,3,5-trimethoxy-cis-inositol (tmci). The results indicate that V(IV)O(2+) species are formed in acid and weakly basic solution and that [V(tmcaH-2)2] is observed above pH 10. In the non-oxido complex, DFT calculations suggest that the two -NH2 groups are in trans position and that the pre-organization of the ligands favours the metal complexation and the formation of the hexa-coordinated species with VN6 coordination.
authors.affiliation: Institute of General Food Chemistry, Technical University of Lodz, ul. Stefanowskiego 4/10, PL-90924, Lodz, Poland.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Lodyga-Chruscinska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szebesczyk
authors.forename: Daniele
authors.initials: D
authors.lastname: Sanna
authors.forename: Kaspar
authors.initials: K
authors.lastname: Hegetschweiler
authors.forename: Giovanni
authors.initials: G
authors.lastname: Micera
authors.forename: Eugenio
authors.initials: E
authors.lastname: Garribba
mesh_terms: D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011199:Potentiometry; D011789:Quantum Theory; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D014639:Vanadium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D012996:Solutions; D014639:Vanadium; D014867:Water; D009584:Nitrogen