A sigmatropic rearrangement follows the addition of these compounds into a nitroarene (“nitro-AIR-een”) in the Bartoli synthesis of 7-substituted indoles. To form cyclopropanols, titanium isopropoxide (“iso-pro-poxide”) first reacts with these compounds in the Kulinkovich reaction. When Keely and Pauson treated cyclopentadiene (“cyclo-penta-diene”) with these compounds followed by iron(III) (“iron-three”) chloride, they unexpectedly made ferrocene instead of fulvalene. Reactions using these compounds often use 1,2-iodoethane to remove an oxide layer. Like Hauser bases, these compounds are treated with dioxane to shift their Schlenk equilibria (10[1])toward the halide salt form. Carbon-carbon single bonds are formed when these compounds add into carbonyls. For 10 points, name these nucleophilic organometallic (10[1])compounds (10[2])with the typical (10[1])formula RMgX (10[2])■END■ (10[1])