Gravar-mail: Structure and Properties of fac-[Re(I)(CO)(3)(NTA)](2−) (NTA(3−) = Tri-anion of Nitrilotriacetic Acid) and fac-[Re(I)(CO)(3)(L)](n−) Analogs Useful for Assessing the Excellent Renal Clearance of the fac-[(99m)Tc(I)(CO)(3)(NTA)](2−) Diagnostic Renal Agent