Synthesis of new heteroleptic strontium complexes stabilized by β-ketoiminato ligands

•Strontium complexes of amine functionalized β-ketoiminato ligands were synthesized.•X-ray analysis confirms dimeric structures.•[Sr(btsa)(L1)]2 complexes exhibit penta-coordinate strontium centers.•[Sr(dmamp)(L1)]2 complex displays hexa-coordinate strontium centers.

Heteroleptic strontium complexes stabilized by amine functionalized tridentate β-ketoiminato ligands in combination with bis(trimethylsilyl)amide [Sr(btsa)(L1)]2 (1) and [Sr(btsa)(L2)]2 (2) and stabilized by β-ketoiminato and aminoalkoxy ligands [Sr(dmamp)(L1)]2 (3) were synthesized and characterized. All the complexes formed as dimers where the strontium metal centers were connected by a pair of μ2-O bridging. In 1 and 2 the β-ketoiminato oxygen bridges the metal centers, leaving the complex in a highly strained state bearing a penta-coordinate strontium. The introduction of aminoalkoxy ligand (dmamp) to 1 gave complex 3, where the aminoalkoxy oxygen assumed the bridging role and allowed β-ketoiminato ligands to attain a more relaxed planar state for its ketoimine backbone and a stable hexa-coordinate metal center. All the complexes were characterized using FT-IR, FT-NMR, elemental analyses, and single crystal X-ray crystallography.

Graphical abstractSyntheses of heteroleptic strontium complexes stabilized by β-ketoiminato/amide and β-ketoiminato/aminoalkoxy ligand combinations were demonstrated. These complexes exhibit interesting structural features because of their dimeric structures which display μ2-O bonding between metal centers.Figure optionsDownload full-size imageDownload as PowerPoint slide