Lithium-zinkate mit heteroleptischem Triorganylzinkat-Anion / Lithium Zincates with Heteroleptic Triorganylzincate Anion
| Autor: | Sonja Henkel, Bernd Rademacher, Wolfgang Schwarz, Matthias Westerhausen |
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| Rok vydání: | 1994 |
| Předmět: | |
| Zdroj: | Zeitschrift für Naturforschung B. 49:199-210 |
| ISSN: | 1865-7117 0932-0776 |
| DOI: | 10.1515/znb-1994-0208 |
| Popis: | Bis[bis(trimethylsilyl)methyl]-as well as bis(2,2,4,4,6,6-hexa-methyl-2,4,6-trisila-cyclo-hexyl)zinc react with methyl lithium or phenyl lithium in the pres ence of the tridentate l,3,5-trimethyl-l,3,5-triazinane (TMTA) to yield zincates of the type LiZnR2R'·2TMTA. The compounds are colorless and insoluble in aliphatic or aromatic hydrocarbons. These zincates exist in solution as well as in the crystalline state as separated ions, as confirmed for lithium-methyl-bis(2,2,4,4,6,6-hexamethyl-2,4,6-trisila-cyc/o-hexyl)-zincate · 2TMTA by X-ray diffraction (P1̄; a -1139,5(3); b = 1482,4(4); c = 1528,6(5) pm; α = 95,33(2); β = 100,13(2); γ = 106,91(2)°; Z = 2). The lithium cation is six-coordinated by two TMTA ligands in a distorted anti-prismatic complex. The zinc atom displays a trigonal planar coordination with Zn-C bond lengths of 207 pm to the 2,2,4,4,6,6-hexamethyl-2,4,6-trisila-cyc/o-hexyl ligands and of 202 pm to the methyl group. One trisila-cyc/o-hexyl substi tuent exists in the chair, the other one in the twist conformation. The reaction of lithium bis(trimethylsilyl)amide with bis(trimethylsilylmethyl)zinc yields the benzene soluble lithium-bis(trimethylsilyl)amino-bis(trimethylsilylmethyl)zincate TMTA. The molecular structure was confirmed by X-ray diffraction (P212121; a -1024,8(3); b = 1775,4(7), c = 1918,2(8) pm; Z = 4). The bridging bis(trimethylsilyl)amino ligand displays long Zn-N and Li-N distances of 213 and 208 pm, respectively, due to the steric inter-ligand repulsion. During the reaction of lithium bis(trimethylsilyl)amide with bis[bis(trimethylsilyl)methyl]-zinc no zincate formations observed. The decomposition products lithium bis(trimethylsilyl)-methanide and the heteroleptic bis(trimethylsilyl)amino-bis(trimethylsilyl)methylzinc were detected. |
| Databáze: | OpenAIRE |
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