Synthesis, properties and structures of NbOF3 complexes and comparisons with NbOCl3 analogues

Abstract

The first series of complexes of niobium(V) oxide trifluoride, [NbOF₃(OPR₃)₂] (R = Me or Ph), [NbOF₃(dppmO₂)] (dppmO₂ = Ph₂P(O)CH₂P(O)Ph₂), [NbOF₃(dmso)₂], [NbOF₃(tmeda)] (tmeda = Me₂N(CH₂)₂NMe₂) and [NbOF₃(diimine)] (diimine = 2,2′-bipy, 1,10-phen) have been prepared, either by reaction of the corresponding complexes of NbF₅ and hexamethyldisiloxane (HMDSO) in CH₂Cl₂–MeCN solution, or directly from NbF₅, ligand and HMDSO. They were characterised by IR, ¹H, ³¹P{¹H} and ¹⁹F{¹H} NMR spectroscopy, and X-ray crystal structures are reported for [NbOF₃(OPR₃)₂] (R = Me or Ph) and [NbOF₃(dppmO₂)]. Complexes of NbOCl₃, [NbOCl₃(OPPh₃)₂], [NbOCl₃(dppmO₂)], [NbOCl₃(dppeO₂)] (dppeO₂ = Ph₂P(O)(CH₂)₂P(O)Ph₂), [NbOCl₃(tmeda)] and [NbOCl₃(diimine)] were made from NbCl₅ and HMDSO in MeCN (which forms [NbOCl₃(MeCN)₂] in situ), followed by addition of the neutral ligand. Their properties are compared with the oxide fluoride analogues. X-ray structures are reported for [NbOCl₃(dppmO₂)], [NbOCl₃(dppeO₂)], [NbOCl₃(tmeda)] and [NbOCl₃(2,2′-bipy)]. The synthesis and spectroscopic characterisation of [MF₅L] (M = Nb or Ta; L = OPR₃, OAsPh₃) and [MF₄(diimine)₂][MF₆] are also described, and the key properties of the four series of complexes compared.