title: Cyanide free contraction of disclosed 1,4-dioxane ring as a route to cobalt bis(dicarbollide) derivatives with short spacer between the boron cage and terminal functional group.
abstract: The 1,4-dioxane derivative of cobalt bis(dicarbollide) reacts with dialkylsulfides and triphenylphosphine to give the corresponding sulfonium and phosphonium derivatives [8-L(CH2CH2O)2-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] (L = SMe2, S(CH2CH2)2O, PPh3). The treatment of the triphenylphosphonium derivative with sodium hydroxide results in contraction of the side chain with formation of [8-HOCH2CH2O-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-). The same product was obtained by treatment of the dimethylsulfonium derivative with the poorly nucleophilic base t-BuOK, whereas the stronger nucleophiles induce the sulfur demethylation to give [8-MeS(CH2CH2O)2-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-). The alcohol was used for the synthesis of a series of other short-spacer functional derivatives [8-XOCH2CH2O-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)](-) (X = NH2, SH, N3). A similar contraction of the disclosed 1,4-dioxane ring via the reactions with SMe2 and PPh3 can be used for the synthesis of short-spacer functional derivatives of nido-carborane, whereas the 1,4-dioxane derivatives of closo-decaborate and closo-dodecaborate anions, being stronger electron donors, are more stable and do not react with dimethylsulfide and triphenylphosphine.
authors.affiliation: A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov Str., 119991, Moscow, Russia. sivaev@ineos.ac.ru.
authors.forename: Akim V
authors.initials: AV
authors.lastname: Shmal'ko
authors.forename: Marina Yu
authors.initials: MY
authors.lastname: Stogniy
authors.forename: Grigorii S
authors.initials: GS
authors.lastname: Kazakov
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Anufriev
authors.forename: Igor B
authors.initials: IB
authors.lastname: Sivaev
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Kovalenko
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Bregadze