Werner Daniel, Bayer Uwe, Schädle Dorothea, Anwander Reiner
Institut für Anorganische Chemie, University of Tübingen (EKUT), Auf der Morgenstelle 18, 72076, Tübingen, Germany.
Chemistry. 2020 Sep 21;26(53):12194-12205. doi: 10.1002/chem.202000625. Epub 2020 Sep 7.
The cerium(IV) pyrazolate complexes [Ce(Me pz) ] and [Ce(Me pz) (thf)] initiate β-hydride abstraction of the bis(dimethylsilyl)amido moiety, to afford a heteroleptic cerium(IV) species containing a dimethylpyrazolyl-substituted silylamido ligand, namely [Ce(Me pz) (bpsa)] (bpsa=bis((3,5-dimethylpyrazol-1-yl)dimethylsilyl)amido; Me pz =3,5-dimethylpyrazolato), along with some cerium(III) species. Remarkably, the nucleophilic attack of the pyrazolyl at the silicon atom and concomitant Si-H-bond cleavage is restricted to the tetravalent cerium oxidation state and appears to proceed via the formation of a transient cerium(IV) hydride, which engages in immediate redox chemistry. When [Ce(Me pz) ] is treated with [Li{N(SiMe ) }], that is, in the absence of the SiH functionality, any redox chemistry did not occur. Instead, the ceric ate complex [LiCe (Me pz) ] and the stable mixed-ligand ceric species [Ce(Me pz) {N(SiMe ) } ] were obtained.
铈（IV）吡唑酸盐配合物[Ce(Me pz) ]和[Ce(Me pz) (thf)]引发双（二甲基硅基）氨基部分的β-氢化物提取，得到一种含有二甲基吡唑基取代硅氨基配体的杂配铈（IV）物种，即[Ce(Me pz) (bpsa)]（bpsa = 双（（3,5-二甲基吡唑-1-基）二甲基硅基）氨基；Me pz = 3,5-二甲基吡唑基），以及一些铈（III）物种。值得注意的是，吡唑基对硅原子的亲核攻击以及伴随的Si-H键断裂仅限于四价铈氧化态，并且似乎是通过形成瞬态铈（IV）氢化物进行的，该氢化物立即参与氧化还原化学。当[Ce(Me pz) ]与[Li{N(SiMe ) }]反应时，即在没有SiH官能团的情况下，没有发生任何氧化还原化学。相反，得到了铈酸盐配合物[LiCe (Me pz) ]和稳定的混合配体铈物种[Ce(Me pz) {N(SiMe ) } ]。
