Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Germany.
Chem Soc Rev. 2012 Dec 7;41(23):7657-72. doi: 10.1039/c2cs35180c.
Today the rare-earth elements play a critical role in numerous high-tech applications. This is why various areas of rare-earth chemistry are currently thriving. In organolanthanide chemistry the search for new ligand sets which are able to satisfy the coordination requirements of the large lanthanide cations continues to be a hot topic. Among the most successful approaches in this field is the use of amidinate and guanidinate ligands of the general types RC(NR')(2) (R = H, alkyl, aryl; R' = alkyl, cycloalkyl, aryl, SiMe(3)) and R(2)NC(NR')(2) (R = alkyl, SiMe(3); R' = alkyl, cycloalkyl, aryl, SiMe(3)), which can both be regarded as steric cyclopentadienyl equivalents. Mono-, di- and trisubstituted lanthanide amidinate and guanidinate complexes are all readily available. Various rare earth amidinates and guanidinates have turned out to be very efficient homogeneous catalysts e.g. for the polymerization of olefins and dienes, the ring-opening polymerization of cyclic esters or the guanylation of amines. Moreover, certain alkyl-substituted lanthanide tris(amidinates) and tris(guanidinates) were found to be highly volatile and are thus promising precursors for ALD (= atomic layer deposition) and MOCVD (= metal-organic chemical vapor deposition) processes in materials science, e.g. for the production of lanthanide nitride thin layers. This tutorial review covers the continuing success story of lanthanide amidinates and guanidinates which have undergone an astonishing transition from mere laboratory curiosities to efficient homogeneous catalysts as well as ALD and MOCVD precursors within the past 10 years.
今天，稀土元素在许多高科技应用中发挥着关键作用。这就是为什么目前各个领域的稀土化学都在蓬勃发展。在有机镧系元素化学中，寻找新的配体体系以满足大镧系阳离子的配位要求，一直是一个热门话题。在该领域最成功的方法之一是使用酰胺基和胍基配体，其一般类型为RC(NR')(2)（R = H、烷基、芳基；R' = 烷基、环烷基、芳基、SiMe(3)）和R(2)NC(NR')(2)（R = 烷基、SiMe(3)；R' = 烷基、环烷基、芳基、SiMe(3)），它们都可以被视为空间位阻环戊二烯基等价物。单取代、二取代和三取代的镧系酰胺基和胍基配合物都很容易获得。各种稀土酰胺基和胍基已被证明是非常有效的均相催化剂，例如用于烯烃和二烯烃的聚合、环状酯的开环聚合或胺的胍基化。此外，某些取代的镧系三（酰胺基）和三（胍基）被发现具有很高的挥发性，因此是原子层沉积（ALD）和金属有机化学气相沉积（MOCVD）等材料科学过程中的有前途的前体，例如用于生产镧系氮化物薄膜。本综述涵盖了过去 10 年来，镧系酰胺基和胍基从仅仅是实验室的好奇心发展为高效均相催化剂以及 ALD 和 MOCVD 前体的惊人转变的持续成功故事。
