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Dalton Transactions

The international journal for inorganic, organometallic and bioinorganic chemistry



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Dalton Trans., 2010, 39, 883 - 891, DOI: 10.1039/b916336k

Six- and eight-coordinate thio- and seleno-ether complexes of NbF5 and some comparisons with NbCl5 and NbBr5 adducts

Marek Jura, William Levason, Raju Ratnani, Gillian Reid and Michael Webster

The reaction of RS(CH2)2SR (R = Me, Et or iPr) with NbF5 produces [NbF4{RS(CH2)2SR}2][NbF6] which contain distorted eight-coordinate (dodecahedral) cations and octahedral anions, whereas RSe(CH2)2SeR (R = Me or Bun) form six-coordinate [(NbF5)2(-RSe(CH2)2SeR)]. Et2S and Me2Se (L) also form six-coordinate [NbF5(L)], but Me2S forms both [NbF5(Me2S)] and an eight-coordinate cation in [NbF4(Me2S)4][NbF6]. MeS(CH2)2SMe forms eight-coordinate cations in [NbX4{MeS(CH2)2SMe}2][NbX6] (X = Cl or Br), but other complexes of the heavier halides including [NbX5(L)] and [(NbX5)2(-L–L)] (L–L = RSe(CH2)2SeR; o-C6H4(CH2SMe)2 and o-C6H4(CH2SeMe)2) contain six-coordinate niobium. The very unstable [NbCl5(Me2Te)] was characterised spectroscopically, but all other attempts to form telluroether complexes resulted in decomposition, and NbI5 was reduced even by thioethers. The complexes have been characterised by multinuclear NMR (1H, 19F, 93Nb, 77Se or 125Te), IR and UV/visible spectroscopy, and X-ray crystal structures are reported for [NbF4{RS(CH2)2SR}2][NbF6] (R = Me, iPr), [NbF4(Me2S)4][NbF6], [NbCl5(Me2Se)], [NbBr5(Me2S)], [(NbCl5)2{o-C6H4(CH2SMe)2}] and [(NbCl5)2{MeSe(CH2)2SeMe}]. All the complexes are very moisture sensitive and the fluoride complexes decompose slowly with fluorination of the neutral ligand.

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