A Redox-Switchable Germylene and its Ligating Properties in Selected Transition Metal Complexes
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- 作者：Dr. Florian Walz ; Dr. Eric Moos ; Dr. Delphine Garnier ; Dr. Ralf Kö ; ppe ; Dr. Christopher E. Anson and Prof. Dr. Frank Breher
- 刊名：Chemistry - A European Journal
- 出版年：2017
- 出版时间：January 23, 2017
- 年：2017
- 卷：23
- 期：5
- 页码：1173-1186
- 全文大小：2290K
- ISSN：1521-3765
文摘
The synthesis, structure, and full characterization of a redox-switchable germylene based on a [3]ferrocenophane ligand arrangement, [Fc(NMes)2Ge] (4), is presented. The mesityl (Mes)-substituted title compound is readily available from Fc(NHMes)2 (2) and Ge{N(SiMe3)2}2, or from the dilithiated, highly air- and moisture-sensitive compound Fc(NLiMes)2⋅3 Et2O (3) and GeCl2. Cyclic voltammetry studies are provided for 4, confirming the above-mentioned view of a redox-switchable germylene metalloligand. Although several 1:1 RhI and IrI complexes of 4 (5–7) are cleanly formed in solution, all attempts to isolate them in pure form failed due to stability problems. However, crystalline solids of [Mo(κ1Ge-4)2(CO)4] (8) and [W(κ1Ge-4)2(CO)4] (9) were isolated and fully characterized by common spectroscopic techniques (8 by X-ray diffraction). DFT calculations were performed on a series of model compounds to elucidate a conceivable interplay between the metal atoms in neutral and cationic bimetallic complexes of the type [Rh(κ1E-qE)(CO)2Cl]0/+ (qE=[Fc(NPh)2E] with E=C, Si, Ge). The bonding characteristics of the coordinated Fc-based metalloligands (qE/qE+) are strongly affected upon in silico oxidation of the calculated complexes. The calculated Tolman electronic parameter (TEP) significantly increases by approximately 20 cm−1 (E=C) to 25 cm−1 (E=Si, Ge) upon oxidation. The change in the ligand-donating abilities upon oxidation can mainly be attributed to Coulombic effects, whereas an orbital-based interaction appears to have only a minor influence.