Synthesis and Characterization of Structurally Diverse Alkaline-Earth Salen Compounds for Subterranean Fluid Flow Tracking

A family of magnesium and calcium salen-derivatives was synthesized and characterized for use as subterranean fluid flow monitors. For the Mg complexes, di-n-butyl magnesium ([Mg(Bun)2]) was reacted with N,N′-ethylene bis(salicylideneimine) (H2-salen), N,N′-bis(salicylidene)-1,2-phenylenediamine (H2-saloPh), N,N′-bis(3,5-di-t-butylsalicylidene)-ethylenediamine (H2-salo-But), or N,N′-bis(3,5-di-t-butylsalicylidene)-1,2-phenylenediamine (H2-saloPh-But), and the products were identified by single-crystal X-ray diffraction as [(κ3-(O,N,N′),μ-(O′)saloPh)(μ-(O),(κ2-(N,N′),μ-(O′)saloPh)2(μ-(O),κ3-(N,N′,O′)saloPh′)Mg4]·2tol (1·2tol; saloPh′ = an alkyl-modified saloPh derivative generated in situ), [(κ4-(O,N,N′,O′)saloPh)Mg(py)2]·py (2·py), [(κ4-(O,N,N′,O′)salo-But)Mg(py)2] (3), [(κ4-(O,N,N′,O′)saloPh-But)Mg(py)2]·tol (4·tol), and [(κ3-(O,N,N′),μ-(O′)saloPh-But)Mg]2 (5), where tol = toluene; py = pyridine. For the Ca species, a calcium amide was independently reacted with H2-salo-But and H2-saloPh-But to generate ...