Title:
Hydrogen bonded networks based on lanthanide(III) complexes of N,N
‘-dimethylurea (DMU): preparation, characterisation, and crystal
structures of [Nd(DMU)(6)][NdCl6] and [Nd(NO3)(3)(DMU)(3)]
Abstract:
In order to examine the possibilities of using lanthanide(III) ions in
the crystal engineering of hydrogen bonded coordination complexes, the
compounds [Ln(DMU)(6)][LnCl(6)] and [Ln(NO3)(3)(DMU)(3)] (Ln = Pr,
Nd, Gd, Er; DMU = N,N’-dimethylurea) have been prepared from the
reactions of DMU with the appropriate lanthaniae(III) salts in alcohols.
The representative complexes [Nd(DMU)(6)][NdCl6] (2) and
[Nd(NO3)(3)(DMU)(3)] (6) have been structurally characterised by
single-crystal X-ray studies. The structure of 2 consists of distorted
octahedral [Nd(DMU)(6)](3+) and [NdCl6](3-) ions. In the molecules
of 6, the Nd(III) ion is in a ninecoordinate, monocapped square
antiprismatic geometry, surrounded by three O-bonded DMU ligands and
three bidentate chelating nitrate groups. The [Nd(DMU)(6)](3+) cations
and [NdCl6](3 -) anions self-assemble to form a hydrogen-bonded 3D
architecture in 2. The hydrogen bonding functionalities on the molecules
of 6 create also a 3D structure. Two main motifs of
interionic/intermolecular hydrogen bonds have been observed: N-H... Cl
in 2 and N-H... O(NO3-) in 6; weak C-H... Cl hydrogen bonding
interactions are also present in 2. The complexes were characterised by
magnetic susceptibilities at room temperature and spectroscopic (IR,
far-IR, Raman) techniques. The vibrational data are discussed in terms
of the nature of bonding and the known structures of the neodymium(III)
complexes. (C) 2003 Elsevier Science Ltd. All rights reserved.
