Isoxazoles complexation with metal ions

Despite the weak basicity of isoxazoles, complexes of the parent methyl and phenyl derivatives with numerous metal ions such as copper, zinc, cobalt, etc. have been described (79AHC(25) 147). Many transition metal cations form complexes with Imidazoles the coordination number is four to six (70AHC(12)103). The chemistry of pyrazole complexes has been especially well studied and coordination compounds are known with thlazoles and 1,2,4-triazoles. Tetrazole anions also form good ligands for heavy metals (77AHC(21)323). 

Although isoxazoles are comparatively weak electron donors, complexes with numerous metal ions, notable metal(II) ions, have been reported. The ligands include isoxazole and its methyl, phenyl, amino and hydroxy derivatives. They are listed with references in Table 5. 

Symmetrical N2S2 tetradentate SBs incorporating pyrazole or isoxazole have been prepared and their complexes with different 3d metal ions investigated.111 A Co11 complex having a N3S2 environment was found to exhibit thermal-induced spin-crossover behavior and its structure was determined at two temperatures corresponding to the different spin states.112... 

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