A Remarkable Isostructural Homologous Series of Mixed Lithium-Heavier Alkali Metal tert-Butoxides [(t-BuO)8Li4M4] (M = Na, K, Rb or Cs)
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- 作者：David R. Armstrong ; William Clegg ; Allison M. Drummond ; Stephen T. Liddle ; and Robert E. Mulvey
- 刊名：Journal of the American Chemical Society
- 出版年：2000
- 出版时间：November 15, 2000
- 年：2000
- 卷：122
- 期：45
- 页码：11117 - 11124
- 全文大小：120K
- 年卷期：v.122,no.45(November 15, 2000)
- ISSN：1520-5126
文摘
Three new mixed lithium-heavier alkali metal tert-butoxides [(t-BuO)8Li4M4] (M = Na, Rb, Cs)are reported which, added to the previously discovered potassium analogue [(t-BuO)8Li4K4], complete thehomologous series. Remarkably, X-ray crystallographic studies reveal that all four heterometallic compoundsadopt a common structure. This sixteen-vertex O8Li4M4 "breastplate" motif is built around novel (M+)4 planes(M = Na, K, Rb, Cs), both faces of which support chelating (O4Li2)2- dianions. Each such dianion is positionedapproximately normal with respect to the other. Bonding within the breastplate structure involves a combinationof 
3-Li, 4-M, 3-O, and 4-O centers. Ab initio MO calculations on model systems predict that formation ofthe heterometallic breastplate from the exclusively 3-bonded frameworks of its component homometallicstructures is a favorable exothermic process. Best regarded as an inherently stable contacted triple ion sandwichcomprising a dianion-tetramonocation-dianion arrangement, the breastplate motif is likely to be more widelyapplicable within heterometallic structural chemistry than so far recognized. This point is discussed with referenceto a previously documented series of heterometallic p-block metal-based imide structures of general formula[(CyN)8M14M24], where M1 = Sb or As and M2 = Ag, Cu, or Na.
3-Li, 4-M, 3-O, and 4-O centers. Ab initio MO calculations on model systems predict that formation ofthe heterometallic breastplate from the exclusively 3-bonded frameworks of its component homometallicstructures is a favorable exothermic process. Best regarded as an inherently stable contacted triple ion sandwichcomprising a dianion-tetramonocation-dianion arrangement, the breastplate motif is likely to be more widelyapplicable within heterometallic structural chemistry than so far recognized. This point is discussed with referenceto a previously documented series of heterometallic p-block metal-based imide structures of general formula[(CyN)8M14M24], where M1 = Sb or As and M2 = Ag, Cu, or Na.