Lanthanide amides

Bis(phenolate) ligands are also present in two new lanthanide guanidinate complexes shown in Scheme 60, which were prepared by insertion of diisopropylcarbodiimide into the Ln-N bonds of appropriate neutral lanthanide amide precursors. ... 

A recent report on bimetallic ytterbium bis(amides) 116 and 117 stabilized by a flexible bridged bis(phenolato) ligand claimed a straightforward polymerization of L-lactide. The conversion is characterized by short reaction times (30 min to 2 h) and PLAs displaying broad PDls (1.71-2.24). The reason for the apparent enhancement of the activity found in the bimetallic lanthanide amides is tentatively explained by cooperative effects within these bimetallic systems [114]. 

Alonso JA, Baibas LC (1996) Density Functional Theory of Clusters of Naontransition Metals Using Simple Models. 182 119-171 Anwander R (1996) Lanthanide Amides. 179 33-112... 

R. Anwander, Lanthanide Amides, in Topics Current Chem, 1996, 179, 33. 

A different synthetic procedure involves lanthanide amides as precursors to mixed metallic alkyls (D, Eq. 14) [142]. 

The historical sketch outlines the class of lanthanide amides this article is to deal with and which is further manifested in Scheme 1. Organometallic amides which can be classified as dialkyl (-aryl, -silyl) amides and amides derived from unsaturated heterocyclic ligands are seen with respect to N-unsubstituted (primary, inorganic) amides. The consideration of more classic coordination compounds like acid amides or sulfonamides, often ascribed as wet chemistry , is excluded. The historical data also demonstrate the relatively late start of lanthanide amide chemistry reflecting the late industrial establishment of the lanthanide elements (separation, purification, etc.) [9], However, lanthanide amides are still the youngest class in conjunction with the most important pillars of organometallic lanthanide chemistry, namely the alkyls/cyclopentadienyls (LnCp3, 1954, [10]) and the alkoxides (Ce(OR)4 1956 [11a] La(OR)3 , 1958 [lib]). Indeed most of the work has been conducted in the last ten years. 

During the last five years lanthanide amides, and in particular the silylam-ides, have attracted considerable attention under the assumed name precursors for electronic and ceramic materials [16,17], Herein the systems Ln[N(SiMe3)2]3, for their part, provide essential precursors for the generation of, e.g., pure alkoxides. However, while the steric environment of the alkoxide ligand declined excessively [18], variation of the amide ligand seemed to stick. This goes hand in hand with the very recent start of the exploration of organometallic lanthanide amides themselves as molecular precursors to, e.g., lanthanide metals or lanthanide nitrides (Sect. 7.2). 

The present article will focus in particular on structurally characterized complexes and will refer to current trends and potential applications, simultaneously aiming at a coherent picture of the entire family of organometallic lanthanide amides including the inorganic derivatives. The elements Sc, Y, La will be treated as lanthanide elements Ln. Previous reviews cover this subject mostly as an aspect wrapped up under a comprehensive depiction of both metal amides [19] and lanthanide chemistry [20]. Other articles focus on special topics in this field, e.g., inorganic amides [21], silylamides [22], phthalocyanines [23] or porphyrins [24],... 

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