دورية
Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids
| العنوان: | Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids |
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| المؤلفون: | Hitzbleck, Julia, O'Brien, Anna Y., Forsyth, Craig M., Deacon, Glen B., Ruhlandt‐Senge, Karin |
| المصدر: | Chemistry - A European Journal; July 2004, Vol. 10 Issue: 13 p3315-3323, 9p |
| مستخلص: | Two series of heavy alkaline earth metal pyrazolates, [M(Ph2pz)2(thf)4] 1 a–c(Ph2pz=3,5‐diphenylpyrazolate, M=Ca, Sr, Ba; THF=tetrahydrofuran) and [M(Ph2pz)2(dme)n] (M=Ca, 2 a, Sr, 2 b, n=2; M=Ba, 2 c, n=3; DME=1,2‐dimethoxyethane) have been prepared by redox transmetallation/ligand exchange utilizing Hg(C6F5)2. Compounds 1 aand 2 bwere also obtained by redox transmetallation with Tl(Ph2pz). Alternatively, direct reaction of the alkaline earth metals with 3,5‐diphenylpyrazole at elevated temperatures under solventless conditions yielded compounds 1 a–cand 2 a–cupon extraction with THF or DME. By contrast, [M(Me2pz)2(Me2pzH)4] 3 a–c(M=Ca, Sr, Ba; Me2pzH=3,5‐dimethylpyrazole) were prepared by protolysis of [M{N(SiMe3)2}2(thf)2] (M=Ca, Sr, Ba) with Me2pzH in THF and by direct metallation with Me2pzH in liquid NH3/THF. Compounds 1 a–cand 2 a–cdisplay η2‐bonded pyrazolate ligands, while 3 a,bexhibit η1‐coordination. Complexes 1 a–chave transoidPh2pz ligands and an overall coordination number of eight with a switch from mutually coplanar Ph2pz ligands in 1 a,bto perpendicular in 1 c. In eight coordinate 2 a,bthe pyrazolate ligands are cisoid,whilst 2 chas an additional DME ligand and a metal coordination number of ten. By contrast, 3 a,bhave octahedral geometry with four η1‐Me2pzH donors, which are hydrogen‐bonded to the uncoordinated nitrogen atoms of the two transMe2pz ligands. The application of synthetic routes initially developed for the preparation of lanthanoid pyrazolates provides detailed insight into the similarities and differences between the two groups of metals and structures of their complexes. |
| قاعدة البيانات: | Supplemental Index |
| تدمد: | 09476539 15213765 |
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| DOI: | 10.1002/chem.200400076 |