Synthesis and characterisation of new N1-alkyl-3,5-dipyridylpyrazole derived ligands. Study of their reactivity with Pd(II) and Pt(II)

摘要

Two new pyrazole-derived ligands, 1-ethyl-3,5-bis(2-pyridyl)pyrazole (L-1) and 1-octyl-3,5-bis(2-pyridyl)pyrazole (L-2), both containing alkyl groups at position 1 were prepared by reaction between 3,5-bis(2-pyridyl) pyrazole and the appropriate bromoalkane in toluene using sodium ethoxide as base.The reaction between L-1, L-2 and [MCl2(CH3CN)(2)] (M = Pd(II), Pt(II)) resulted in the formation complexes of formula [MCl2(L)] (M = Pd(II), L = L-1 (1); M = Pd(II), L = L-2 (2); M = Pt(II), L = L-1 (3); M = Pt(II), L = L-2 (4)). These complexes were characterised by elemental analyses, conductivity measurements, infrared, H-1, C-13{H-1} NMR and HMQC spectroscopies. The X-ray structure of the complex [PtCl2(L-2)] (4) was determined. In this complex, Npyridine and Npyrazole donor atoms coordinate the ligand to the metal, which complete its coordination with two chloro ligands in a cis disposition. (c) 2005 Elsevier B.V. All rights reserved.