Transition metal complexes with pyrazole derivatives as ligands

Degradation reactions of scorpionates were observed in the presence of transition metal salts MX2 to give complexes of transition metal and pyrazole derivatives. Otherwise, pyrazolato complexes of transition metals and weakly coordinating anions such as nitrates have been synthesized from transition metal nitrates and 3-phenyl- and 4-phenyldiazo-pyrazole. A number of complexes with pyrazole derivatives as ligands, [Zn(3-tBupzH)2Cl2], [Fe2(3-Phpz)6Cl4], [Cu(pzH)4Br2], [Ni(py)2(pzH)2Cl2], [Li(THF)4][Ti2(μ-pz)3Cl4(NMe2)2], [Zn2(μ-3-Phpz)2(3-PhpzH)2][(NO3)2], [M(3-PhpzH)4(NO3)2] (M = Co, Ni, Cu, Zn, Cd), [Zn(3-PhpzH)2(NO3)2], [Zn(4-PhNNpzH)2(NO3)2](H2O), and [Cd(4-PhNNpzH)2(NO3)2(H2O)2], have been crystallized and characterized by single-crystal X-ray diffraction.

Graphical abstractDegradation reactions of scorpionates were observed in the presence of transition metal salts MX2 to give complexes of transition metal and pyrazole derivatives. An important factor influencing the stability of scorpionates appears to be the degree of steric crowding around the boron center.Figure optionsDownload full-size imageDownload as PowerPoint slide