Yttrium and lanthanide complexes with different P,N ligands in the coordination sphere have been synthesized. First the chloride complexes [{CH(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl] (Ln = Y (1 a), La (1 b), Nd (1 c), Yb (1 d)) having the bulky [CH(PPh2NSiMe3)2]- and the flexible [(Ph2P)2N]- ligands in the same molecule were prepared by three different synthetic pathways. Compounds 1 a-d can be obtained by reaction of [{[CH(PPh2NSiMe3)2]LnCl2}2] with [K(thf)nN(PPh2)2] (n = 1.25, 1.5) or by treatment of [{(Ph2P)2N}LnCl2(thf)3] with K[CH(PPh2NSiMe3)2]. Furthermore, a one-pot reaction of K[CH(PPh2NSiMe3)2] with LnCl3 and [K(thf)nN(PPh2)2] leads to the same products. Single-crystal X-ray structures of 1 a-d show that the conformation of the six-membered metallacycle (N1-P1-C1-P2-N2-Ln) which is formed by chelation of the [CH(PPh2NSiMe3)2]- ligand to the lanthanide atom is influenced by the ionic radius of the central metal atom. In solution dynamic behavior of the [(Ph2P)2N]- ligand is observed, which is caused by rapid exchange of the two different phosphorus atoms. Further reaction of 1 b with KNPh2 resulted in [{(Me3SiNPPh2)2CH}La{N(PPh2)2}(NPh2)] (2). Compounds 1 a-d and 2 are active in the ring-opening polymerization of epsilon-caprolactone and the polymerization of methyl methacrylate. In some cases high molecular weight polymers with good conversions and narrow polydispersities were obtained. In both polymerizations the catalytic activity depends on the ionic radius of the metal center.
Die Trichloride von Lanthan, Neodym, Samarium und Terbium reagieren mit Na(C5Me4H) in THF zu homoleptischen Verbindungen des Typs Ln(C5Me4H)3 [Ln = La (1a), Nd (1b), Sm (1c), Tb (1d)]. Dagegen führt die Reaktion von HoCl3, TmCl3 und LuCl3 mit Na(C5Me4H) nur zu den Dicyclopentadienyl‐Komplexen (C5Me4H)2LnCl(THF) [Ln = Ho (2e), Tm (2f), Lu (2h)]. Die Metallocene (C5Me4H)2Ln(THF)2 [Ln = Sm (3c), Yb (3g)] sind durch Umsetzung von LnI2 (Ln = Sm, Yb) mit Na(C5Me4H) erhältlich. Die neuen Verbindungen wurden durch 1H‐ und 13C‐NMR‐Spektren, die Tricyclopentadienylderivate 1 a und 1 c durch Röntgenstrukturanalysen charakterisiert.
Not germa‐, stanna‐, and plumbaethenes, but ylidic carbene adducts (depicted on the right) are obtained with bis(diisopropylamino)cyclopropenylidenes. The first main group metal complexes with this nucleophilic carbene are interesting alternatives to the intensively studied imidazol‐2‐ylidenes.
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