Synthese, Struktur und Reaktivität von Tris‐, Bis‐ und Mono(2,4‐dimethylpentadienyl)‐Komplexen des Neodyms, Lanthans und des Yttriums

Abstract

Abstract The tris(2,4‐dimethylpentadienyl) complexes [Ln( η 5 ‐Me 2 C 5 H 5 ) 3 ] (Ln = Nd, La, Y) are obtained analytically pure by reaction of the tribromides LnBr 3 · n THF with the potassium compound K(Me 2 C 5 H 5 )(thf) n in THF in good yields. The structural characterization is carried out by X‐ray crystal structure analysis and NMR‐spectroscopically. The tris complexes can be transformed into the dimeric bis(2,4‐dimethylpentadienyl) complexes [Ln 2 ( η 5 ‐Me 2 C 5 H 5 ) 4 X 2 ] (Ln, X: Nd, Cl, Br, I; La, Br, I; Y, Br) by reaction with the trihalides THF solvates in the molar ratio 2:1 in toluene. Structure and bonding conditions are determined for selected compounds by X‐ray crystal structure analysis and NMR‐spectroscopically in general. The dimer‐monomer equilibrium existing in solution was investigated NMR‐spectroscopically in dependence of the donor strength of the solvent and could be established also by preparation of the corresponding monomer neutral ligand complexes [Ln( η 5 ‐Me 2 C 5 H 5 ) 2 X(L)] (Ln, X, L: Nd, Br, py; La, Cl, thf; Br, py; Y, Br, thf). Finally the possibilities for preparation of mono(2,4‐dimethylpentadienyl)lanthanoid(III)‐dibromid complexes are shown and the hexameric structure of the lanthanum complex [La 6 ( η 5 ‐Me 2 C 5 H 5 ) 6 Br 12 (thf) 4 ] is proved by X‐ray crystal structure analysis.