Abstract
Complete thf donor exchange is observed when complexes Ln[N(SiHMe~2~)~2~]~3~(thf)~2~ (Ln = La, Nd) are treated with the monofunctional donor molecules triphenylphosphane oxide, N‐methylimidazole, and 1,3‐dimethylimidazolin‐2‐ylidene. The resulting complexes Ln[N(SiHMe~2~)~2~]~3~(donor)~2~ exhibit a trigonal‐bipyramidal coordination geometry with the donor molecules located in the apical positions. Bifunctional chelating donors 1,10‐phenanthroline, 1,2‐bis(dimethylphosphanyl)ethane, and N,N,N′,N′‐tetramethylethylenediamine give discrete complexes Ln[N(SiHMe~2~)~2~]~3~(phen) (Ln = Sc, La, Nd), Nd[N(SiHMe~2~)~2~]~3~(dmpe), and La[N(SiHMe~2~)~2~]~3~(tmeda). The phen adducts are isostructural as demonstrated for the large Nd^3+^ and small Sc^3+^ centers by X‐ray structure analyses and display a distorted square‐pyramidal coordination geometry in the solid state. The distinct coordination of various donor molecules implies subtle changes of the Si–H bonding which can be straightforwardly examined by NMR and FTIR spectroscopy. Ate complex {Y[N(SiHMe~2~)~2~]~4~Li}~2~ can be isolated and crystallized from Y(OTf)~3~–Li[N(SiHMe~2~)~2~]–hexane reaction mixtures. Dimerization is accomplished by unusual intermolecular Li···H–Si interactions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)