3,5-Dimethyl and 3,5-di-tert-butylpyrazolato complexes with alkali metals: monomeric, dimeric, cluster, and 1D chain structures

The pyrazolato complexes (Me(2)pz)(THF)Li] (1), ((t)Bu(2)pz)Li](4) (2), ((t)Bu(2)pzH)((t)()Bu(2)pz)Li](2) (2a), (Me(2)pz)Na] (3), ((t)Bu(2)pz)Na](4), ((t)Bu(2)pz)(6)(OH)Na(7)] (4a), ((t)Bu(2)pz)(18-crown-6)Na] (4b), and ((t)Bu(2)pz)K] (5) were synthesized by metalation reactions between R(2)pzH (R = Me, (t)()Bu) and alkyllithium, elemental sodium, or potassium. All the complexes were characterized by spectroscopic methods and microanalysis, and in addition, the crystal structures of 2, 2a, 3, 4a, 4b, and 5 were obtained by single-crystal X-ray diffraction. They show monomeric, dimeric, cluster, and 1D chain structures in the solid state. Ab initio calculations on the structure and stabilities of the monomeric pzM complexes were performed at the MP2 level of theory showing good agreement with the coordination preferences of the pyrazolato ligand to a particular alkali ion.