Synthesis of Mononuclear Strontium Complexes with Polyether and β‑Diketonato Ligands

Strontium β-diketonate
complexes were synthesized by the
substitution reaction of the bis(trimethylsilyl) amide of Sr(btsa)2·2DME with an ethereal group and β-diketonate ligands.
The compounds [Sr(tmge)(btsa)]2 (1), [Sr(tod)(btsa)]2 (2), Sr(tmgeH)(tfac)2 (3), Sr(tmgeH)(acac)2 (4), Sr(tmgeH)(tmhd)2 (5), Sr(todH)(tfac)2 (6), Sr(todH)(acac)2 (7), Sr(todH)(tmhd)2 (8), Sr(todH)(hfac)2 (9), Sr(dmts)(hfac)2 (10), [Sr(mee)(tmhd)2]2 (11), and Sr(dts)(hfac)2·DME (12) were obtained and analyzed by various
techniques, including FT-IR, NMR, TGA (thermogravimetric analyses),
and elemental analysis. Complexes 1, 3, 8, 9, 10, 11, and 12 were further structurally confirmed by single-crystal X-ray
crystallography, where complexes 1 and 11 showed dimeric structures with μ2-O bonds of ethereal
groups or tmhd ligands, and complexes 3, 8, 9, 10, and 12 displayed
monomeric structures. Interestingly, compounds 10 and 12, which preceded trimethylsilylation of the coordinating
ethereal alcohols such as tmhgeH and meeH in the presence of HMDS
as by-products due to highly increasing acidity of them, originated
from electron-withdrawing two hfac ligands.