Synthesis and Characterization of New Strontium Complexes with Multidentate Ligands

Abstract

AbstractA series of new strontium complexes, [Sr(tmtad)(btsa)]2 (1), [Sr(ptmtad)(btsa)]2 (2), [Sr(etmtad)(btsa)]2 (3), [Sr(tmtad)(tmhd)]2 (4), [Sr(ptmtad)(tmhd)]2 (5), and [Sr(etmtad)(tmhd)]2 (6), were successfully synthesized by substitution reactions between btsa, aminoalkoxide ligands, and tmhdH (btsa=bis(trimethylsilyl) amide, tmtadH=2,5,9,12‐tetramethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, ptmtadH=2,5,7,9,12‐pentamethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, etmtadH=7‐ethyl‐2,5,9,12‐tetramethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, tmhdH=2,2,6,6‐tetramethyl‐3,5‐heptanedione). Thermogravimetric analysis (TGA) of the new strontium compounds showed low residual masses (4‐11 %) where complex 4 displayed the highest volatility and thermal stability. Single crystal X‐ray study of complexes 1, 3, and 6 revealed that the respective complexes crystalize in a triclinic space group as a dimer with a hexa‐ or hepta‐coordination. Furthermore, dimethylamino nitrogen atoms of aminoalkoxide ligands are freely pendent without coordinating to the central strontium metal due to their steric hindrance on the coordination sphere. Compounds 1–6 were characterized by 1H‐ and 13C‐nuclear magnetic resonance (NMR) spectroscopy, Fourier‐transform infrared (FT‐IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis.