Water-free neodymium 2,6-naphthalenedicarboxylates coordination complexes and their application as catalysts for isoprene polymerization.

A series of four coordination polymers based on neodymium have been hydrothermally synthesized with different carboxylic acids as a linker. The structures of the compounds Nd(2)(2,6-ndc)(3)(H(2)O)(3)·H(2)O (1), Nd(2)(2,6-ndc)(2)(ox)(H(2)O)(2) (2), and Nd(2,6-ndc)(form) (3) (2,6-ndc = 2,6-naphthalenedicarboxylate; ox = oxalate; and form = formate) have been determined by single-crystal X-ray diffraction analysis. They exhibit rather dense networks built up from infinite chains of NdO polyhedra connected to each other through the 2,6-ndc ligand. Terminal and bridging aquo species are present in the coordination sphere of Nd for 1, whereas some of them are partially replaced by oxalate groups in 2 and fully substituted by formate groups in 3. The water-free phase 3 as well as the compound Nd(form)(3) (4) were considered for catalytic reaction for polymerization of isoprene in the presence of Al-based cocatalyst, affording cis-polyisoprene with good conversions. Residual Nd material with unchanged structure was found in the polymeric material. The neodymium luminescence of compounds 3 and 4 was also measured.