A solution and solid state study of niobium complexes University of ...

Chapter 2
Figure 2.5: Structure of trans-[NbCl2(thd)2].
2.6.3 Mono(β-diketonate) niobium(V) complexes:
2.6.3.1 fac-[Nb(NCS)(Opr)3(dbm)] and trans-[Nb(NCS)2(OEt)2(dbm)]
In 1976 Dahan et al. 60,61 published two articles on the structures of 6-
coordinated niobium complexes with dibenzoylmethanato (dbm) as bidentate
ligand. This was done in order to resolve the stereochemistry of the metal
atoms. The X-ray structure of fac-[Nb(NCS)(Opr)3(dbm)] was carried out
following that of trans-[Nb(NCS)2(OEt)2(dbm)]. The average Nb-O(dbm) bond
lengths were determined as 2.09 Å for fac-[Nb(NCS)(Opr)3(dbm)] and 2.04 Å
for trans[Nb(NCS)2(OEt)2(dbm)]. Both crystals were found to be built up of
monomeric molecules and the only intermolecular interactions found were van
der Waals contacts. The niobium atoms for both crystals were at the centre of
a distorted co-ordination octahedron.
60 F. Dahan, R. Kergoat, M. Senechal-Tocquer, J. E. Guerchais, J. Chem. Soc., Dalton Trans., 2202, 1976.
61 F. Dahan, R. Kergoat, M. Senechal-Tocquer, J. E. Guerchias, Acta Cryst., B32, 1038, 1976.
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