3‐(2‐Pyridyl)‐5‐(2‐thienyl)pyrazole and Complexes of Its Anion with Lithium, Magnesium, Calcium, and Zinc Ions

5‐(2‐Furanyl)‐3‐(2‐pyridyl)pyrazole ( 1 ) and 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazole ( 2 ) oligomerize through hydrogen bridges in the solid state to yield tetramers and dimers, respectively. The pyrazole units are very acidic and, therefore, deprotonation of 2 with the organometallic reagents LiN(SiMe 3 ) 2 , PhLi, ZnMe 2 , and ZnEt 2 allows the synthesis of (tetrahydrofuran)lithium 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate ( 3a ), bis[methylzinc 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate] ( 4a ), and bis[ethylzinc 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate] ( 4b ). Recrystallization of 3a in the presence of 1,4‐dioxane yields catena ‐[(1,4‐dioxane)lithium 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate] ( 3b ). Magnesiation of 2 yields different products depending on the organometallic magnesium reagent applied. The use of butylmagnesium chloride gives tris(tetrahydrofuran)magnesium chloride 3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate ( 5 ). Employment of the diphenylmagnesium–1,4‐dioxane complex leads to the formation of bis(tetrahydrofuran)magnesium bis[3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate] ( 6 ), whereas the more aggressive diethylmagnesium–1,4‐dioxane complex also metalated the thienyl substituent to yield bis[bis(tetrahydrofuran)magnesium 3‐(2‐pyridyl)‐5‐(2‐thienyl‐5‐ide)pyrazolate] ( 7 ). A trinuclear calcium complex, tris(tetrahydrofuran)tricalcium μ 3 ‐hydroxide iodide tetrakis[3‐(2‐pyridyl)‐5‐(2‐thienyl)pyrazolate] ( 8 ), is isolated after calciation of 2 and inadvertent hydrolysis during recrystallization.