Role of electronic factors in the formation of anionic complexes of tellurium(IV): Crystal structure of bis(4-methylbenzoylmethyltriphenylphosphonium) hexabromotellurate(IV)

摘要

Reactions of [(4-MeOC6H4COCH2)Ph3P]Br (1c) with (4-XC6H4COCH2)(2)TeBr2 (X = H, 2a; Me, 2b; OMe, 2c) lead to Te-C bond cleavage to afford [(4-MeOC6H4COCH2)Ph3P](2)[TeBr6] (3c). The analogous complexes [(4-MeC6H4COCH2)Ph3P](2)[TeBr6] (3b) and [(C6H5COCH2)Ph3P](2)[TeBr6](3a) are obtained from the reaction of the corresponding phosphonium bromide with 2c. The 1:1 adducts [(4-Xc(6)H(4)coCH(2))Ph3P](+)[(4-XC6H4COCH2)(2)TeBr3](-), formed as intermediates, could be isolated only in case of X = H or Me. The crystal structure of 3b, which crystallizes with one molecule of dichloromethane, shows the presence of close C-H center dot center dot center dot Br/Cl contacts among the ions and solvated molecules. These weak interactions distort, though marginally, the otherwise ideal octahedral shape of the [TeBr6]- anion adopted as a consequence of stereochemical inertness of the lone pair on the central tellurium atom. The supramolecular extended arrays of ionic molecular units formed by means of solvated head-to-tail linkers are identified. (c) 2005 Elsevier Ltd. All rights reserved.