Zwitterionic Alkali-Metal Silanides of Tripodal Ligand Geometry: Synthesis, Structure, and Lewis Acid-Base Chemistry

Vidura D. Thalangamaarachchige, Hui Li, David B. Cordes, Daniel K. Unruh, Clemens Krempner

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A unique family of zwitterionic alkali-metal silanides of general formula [Si(SiMe2OR)3M] (M-3), where M = Li, Na, K and R = CH2CH3 (M-3b), CH(CH3)2 (M-3c), CH2CH(CH3)2 (M-3d), CH2CH2OSCH3 (M-3g), CH2CH2N(CH3)2 (M-3h), have been synthesized and their structures fully characterized. Compounds M-3 were prepared from reactions of the corresponding alkali-metal alkoxides, R′OM (R′ = But, Bui M = Li, Na, K) with the silanes Si(SiMe2OR)4 (2a-h), where R = CH2CH3 (b), CH(CH3)2 (c), CH2CH(CH3)2 (d), CH2CH2OSCH3 (g), CH2CH2N(CH3)2 (h), via selective Si-Si bond cleavage. Analysis of the X-ray data of Li-3a-e,g, Li-h, Li-4, Na-3a-c,e,f,h, and K-3b,d,e,g revealed two major structural motifs in the solid state: infinite chain type and monomeric zwitterions. The reaction of Si(SiMe2OCH2CH3)3Li (Li-3b) with BPh3 in THF gave the zwitterionic Lewis acid-base complex Ph3BSi(SiMe2OCH2CH3)3Li·THF (Li-5b). Reactions of W(CO)6 with Li-3b-d and Na-3b,c resulted in the formation of the zwitterionic silyl tungstenate complexes (CO)5WSi[SiMe2OCH2CH3]3Li (Li-6b), (CO)5WSi[SiMe2OCH(CH3)2]3Li (Li-6c), (CO)5WSi[SiMe2OCH2CH(CH3)2)]3Li (Li-6d), (CO)5WSi(SiMe2OCH2CH3)3Na (Na-6b), and (CO)5WSi[SiMe2OCH(CH3)2]3Na (Na-6c), respectively. The solid-state structures of Li-5b and Na-6b were determined by X-ray crystallography.

Original languageEnglish
Pages (from-to)9869-9879
Number of pages11
JournalInorganic Chemistry
Issue number16
StatePublished - Aug 21 2017


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