3‐(1‐Adamantyl)‐, 3‐Ferrocenyl‐, and 3‐(2‐Furanyl)‐Substituted 5‐(2‐Pyridyl)pyrazole as well as Lithium and Zinc Complexes

3‐(2‐Furanyl)‐5‐(2‐pyridyl)pyrazole ( 1 ) and 3‐(1‐adamantyl)‐5‐(2‐pyridyl)pyrazole ( 2 ) crystallize as hydrogen‐bridged tetrameric molecules, whereas 3‐ferrocenyl‐5‐(2‐pyridyl)pyrazole ( 3 ) forms hydrogen‐bridged dimers in the solid state. Deprotonation of the appropriate pyrazole with n ‐butyllithium in ethereal solvents or with diethylzinc yields the dimers of (η 1 ‐1, 2‐dimethoxyethane)lithium 3‐(2‐furanyl)‐5‐(2‐pyridyl)pyrazolate ( 4 ), (η 1 ‐1, 4‐dioxane)lithium 3‐(1‐adamantyl)‐5‐(2‐pyridyl)pyrazole ( 5 ), and ethylzinc 3‐(2‐furanyl)‐5‐(2‐pyridyl)pyrazolate ( 6 ). Exposure of a solution of 6 to ambient conditions leads to hydrolytic decomposition and the formation of bis{(ethylzinc hydroxide) zinc bis[3‐(2‐furanyl)‐5‐(2‐pyridyl)pyrazolate]} ( 7 ). This tetranuclear zinc complex contains two tetra‐ and two hexa‐coordinate metal atoms.