Reaktion von Amidrazonen mit 1.3‐Dicarbonyl‐Verbindungen

Two series of heavy alkaline earth metal pyrazolates, [M(Ph(2)pz)(2)(thf)(4)] 1 a-c (Ph(2)pz=3,5-diphenylpyrazolate, M=Ca, Sr, Ba; THF=tetrahydrofuran) and [M(Ph(2)pz)(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(C(6)F(5))(2). Compounds 1 a and 2 b were also obtained by redox transmetallation with Tl(Ph(2)pz). Alternatively, direct reaction of the alkaline earth metals with 3,5-diphenylpyrazole at elevated temperatures under solventless conditions yielded compounds 1 a-c and 2 a-c upon extraction with THF or DME. By contrast, [M(Me(2)pz)(2)(Me(2)pzH)(4)] 3 a-c (M=Ca, Sr, Ba; Me(2)pzH=3,5-dimethylpyrazole) were prepared by protolysis of [M[N(SiMe(3))(2)](2)(thf)(2)] (M=Ca, Sr, Ba) with Me(2)pzH in THF and by direct metallation with Me(2)pzH in liquid NH(3)/THF. Compounds 1 a-c and 2 a-c display eta(2)-bonded pyrazolate ligands, while 3 a,b exhibit eta(1)-coordination. Complexes 1 a-c have transoid Ph(2)pz ligands and an overall coordination number of eight with a switch from mutually coplanar Ph(2)pz ligands in 1 a,b to perpendicular in 1 c. In eight coordinate 2 a,b the pyrazolate ligands are cisoid, whilst 2 c has an additional DME ligand and a metal coordination number of ten. By contrast, 3 a,b have octahedral geometry with four eta(1)-Me(2)pzH donors, which are hydrogen-bonded to the uncoordinated nitrogen atoms of the two trans Me(2)pz 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.

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Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids

Hitzbleck

O'Brien

Forsyth

et al. 2004

Chemistry A European J

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ChemInform Abstract: RK. VON AMIDRAZONEN MIT 1,3‐DICARBONYL‐VERBINDUNGEN

Neunhoeffer¹,

Weischedel²

1972

Chemischer Informationsdienst

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Amidrazones in the synthesis of heterocycles (review)

Зеленин

Solod

Khrustalev

1989

Chem Heterocycl Compd

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Reaktion von Amidrazonen mit 1.3‐Dicarbonyl‐Verbindungen

Cited by 4 publications

References 3 publications

Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids

Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids

ChemInform Abstract: RK. VON AMIDRAZONEN MIT 1,3‐DICARBONYL‐VERBINDUNGEN

Amidrazones in the synthesis of heterocycles (review)

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