Gas-Phase Structures of Potassium Tetrakis(hexafluoro- acetylacetonato) Lanthanide(III) Complexes [KLn(C5 HF6 O2 )4 ] (Ln=La, Gd, Lu).

ABSTRACT

The molecular structures of potassium tetrakis(hexafluoroacetylacetonato)lanthanide(III) complexes [KLn(hfa)4 ] (Ln=La, Gd, Lu; hfa=C5 HF6 O2 ,) were studied by synchronous gas-phase electron diffraction/mass spectrometry (GED/MS) supported by quantum-chemical (DFT/PBE0) calculations. The compounds sublime congruently and the vapors contain a single molecular species the heterobinuclear complex [KLn(hfa)4 ]. All molecules are of C1 symmetry with the lanthanide atom in the center of an LnO8 coordination polyhedron, while the potassium atom is coordinated by three ligands with formation of three K-O and three K-F bonds. One hfa ligand is not bonded to the potassium atom. Topological analysis of the electron-density distributions confirmed the existence of ionic-type K-O and K-F bonding. The structures of the free [KLn(hfa)4 ] molecules are compared with those of the related compounds [KDy(hfa)4 ] and [KEr(hfa)4 ] in their crystalline state. The complex nature of the chemical bonding is discussed on the basis of electron-density topology analyses.