Synthesis and Crystal Structure of Gadolinium Mononuclear Complex with Triethylenetetraaminehexaacetic Acid

The gadolinium complex with triethylenetetraaminehexaacetic acid (abbreviated as H₆ttha), (NH₄)₂ [Gd(Httha)] · 6H₂O was synthesized in aqueous solution, and its crystal structure was determined by X-ray four-cycle diffraction method. The crystal is monoclinic, space group P2₁c, with a=1. 040 0(4) nm, b=1.276 1(4) nm, c=2, 313 2(4) nm, β= 90.89(3)°, V=3. 070(2) nm³, Z=4, D_c=1. 709 g/cm³. The complex was a mononuclear molecule, each gadolinium ion is coordinated by four nitrogen atoms and five carboxyl oxygen atoms from one Httha, forming a coordination polyhedron of mono capped square antiprism.