Donor and ate-coordination in rare-earth metal bis(dimethylsilyl)amide complexes

Complete thf donor exchange is observed when complexes Ln[N(SiHMe2)(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(SiHMe2)(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(SiHMe2)(2)](3)(phen) (Ln = Sc, La, Nd), Nd[N(SiHMe2)(2)](3)(dmpe), and La[N(SiHMe2)(2)](3)(tmeda). The phen adducts are isostructural as demonstrated for the large Nd3+ and small Sc3+ 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(SiHMe2)(2)](4)Li}(2) can be isolated and crystallized from Y(OTf)(3)-Li[N(SiHMe2)(2)}-hexane reaction mixtures. Dimerization is accomplished by unusual intermolecular Li center dot center dot center dot H-Si interactions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).