Preparation and characterization of volatile alkaline-earth metal complexes with multiply coordinated aminoalkoxide ligands

The aminoalkoxide complexes Sr(amak)(2) (1) and Ba(amak), (2) were prepared by treatment of a multiply-chelating fluorinated aminoalcohol ligand HOC(CF3)(2)CH2N(CH2CH2OMe)(2), (amak)H, with the Group 2 metal reagents Sr(OPri)(2) and BaH2 respectively. Single crystal X-ray diffraction studies indicate that complex 1 possesses an 8-coordinate distorted bicapped octahedral geometry with all O and N atoms coordinated to the central Sr cation. However, complex 2 adopts a unique 10-coordinate bicapped square antiprismatic structure. of which the coordination number is increased by two fluorine-to-barium dative interactions. Variable temperature F-19 NMR studies show the existence of two inter-convertible isomers in solution and their possible molecular structures are proposed according to their structures in the solid-state. Preliminary investigation suggests that these complexes are good CVD source reagents for depositing SrF2 and BaF2 thin films.