title: Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.
abstract: The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.
authors.affiliation: Dipartimento di Scienze Molecolari e Nanosistemi, Università di Venezia Ca' Foscari , Via Torino 155, I-30170 Mestre, Venice, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bortoluzzi
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Ferretti
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Marchetti
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Pampaloni
authors.affiliation: ICCOM-CNR UOS Pisa , Research Area, Via Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: Calogero
authors.initials: C
authors.lastname: Pinzino
authors.affiliation: Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Zacchini