Synthesis and co-ordination chemistry of the tetradentate chelating ligand 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane: crystal structures of complexes with FeII, CuII, ZnII, AgI and PbII

Autor: John C. Jeffery, Michael D. Ward, Karen L. V. Mann, Jon A. McCleverty
Rok vydání: 1998
Předmět:
Zdroj: Journal of the Chemical Society, Dalton Transactions. :3029-3036
ISSN: 1364-5447
0300-9246
DOI: 10.1039/a804501a
Popis: The new ligand 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane (L) was prepared by reaction of 3-(2-pyridyl)pyrazole with 1,3-dibromopropane under phase-transfer conditions, and contains two bidentate chelating pyridyl/pyrazolyl fragments linked by a flexible trimethylene chain, which permits the angle between the chelating fragments to vary in its complexes. It acts as a tetradentate chelate to a single metal ion, forming a variety of mononuclear complexes which have been structurally characterised. The complex trans-[FeL(dmf)2][ClO4]2 is a high-spin d6 complex in which L co-ordinates equatorially. In [CuL][BF4]2 the [CuL]2+ cations have a significant tetrahedral distortion arising from the inability of the ligand to be planar; chains of [CuL]2+ cations are bridged by [BF4]– anions, with each bridging anion forming semi-co-ordinate interactions with the axial sites of the two [CuL]2+ fragments on either side of it and also hydrogen bonds to the methylene protons of each of the two metal fragments. The complex [(ZnL)3(CO3)][ClO4]4 contains a rare example of the symmetric µ3-bridging mode of carbonate, which has arisen from efficient fixation of atmospheric CO2 by a solution containing L and zinc(II) acetate. Complexes containing the [AgL]+ cation, with either nitrate or perchlorate as the anions, form columnar stacks in the crystal because of weak intermolecular Ag· · ·Ag interactions; the basic geometry of the [AgL]+ cations is very similar to that of [CuL]2+, despite the different stereoelectronic preferences of AgI and CuII. The complex [PbL(NO3)2] is eight-co-ordinate with two bidentate nitrate ligands in addition to L; the lone pair of PbII is stereochemically active, and results in a clear distortion of one square face of the approximately square antiprismatic geometry.
Databáze: OpenAIRE
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