Non-metal Cations Research Articles

Elastomeric polyurethanes modified with geminal bisphosphonate groups

Three types of elastomeric segmented polyurethanes represented by a polyether-urethane, a polyurethane-urea, and a polycarbonate-urethane were introduced into a modified low-temperature variant of base-induced N-alkylation of urethane hard segments with an excess of 1,6-dibromohexane in N,N′-dimethylacetamide (DMAc), resulting in the modification of polymers with 0.08–0.26 mmol/g of pendant 6-bromohexyl groups. Either lithium diisopropylamide (LDA) or sodium hydride was used to initiate the reaction, although LDA was found to be more suitable for the bromoalkylation. Selected bromoalkylated polyurethanes of all three types were reacted with thiol-containing bisphosphonates, to yield the polymers modified with 0.08–0.12 mmol/g of geminal nonesterified covalently attached bisphosphonate groups. Two thiol-containing geminal bisphosphonates used in the modifications were prepared via reactions of nucleophilic addition to vinylidene-bisphosphonic acid. All three types of polyurethanes were found equally suitable for the modifications. The bisphosphonate-modified polyurethanes with nonmetallic cations on the bisphosphonate groups remain soluble in the solvents suitable for the dissolution of nonmodified polymers and can be processed into films by solvent casting. After the exchange of nonmetallic cations to sodium, the polymers become insoluble in any solvent, probably as a result of the intermolecular coordination of bisphosphonate groups with the metal cations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 105–116, 2001

The oxidation of dimethyl sulphide, trimethylamine, and trimethylphosphine by solvated copper(II) or thallium(III) hexafluorometallates in acetonitrile

Dimethyl sulphide, trimethylamine, and trimethylphosphine are oxidized by solvated copper(II) hexafluorophosphate or solvated thallium(III) hexafluorouranate(V) in acetonitrile at room temperature. The reactions are all very similar and spectroscopic studies suggest that the oxidized products are the dinuclear, non-metal cations [Me2SSMe]+, [Me3NNMe2]+, and [Me3PPMe3]2+. The compound [Me3PPMe3][PF6]2 is obtained from the oxidation of PMe3 by diiodine in MeCN, followed by treatment with nitrosonium hexafluorophosphate. Coloured intermediates observed in the reactions of solvated CuII are formulated as redox-active cations [CuLx(NCMe)y]2+, L = SMe2, NMe3, or PMe3, and a generalized reaction scheme is proposed. Keywords: copper(II), thallium(III), acetonitrile, oxidation, fluorometallate.

Stability of homopolyatomic non-metal cations in anhydrous hydrogen fluoride

Stability of homopolyatomic non-metal cations in anhydrous hydrogen fluoride

The possible existence of the cation POBr 2+ and some properties of phosphorus oxybromide, gallium tribromide, and their ionic 1:1 addition compound

Phase studies show that phosphorus oxybromide reacts with gallium tribromide to form a 1:1 addition compound melting at 154·0°. This complex is less stable than the corresponding chloro-compound, POCl 2 +GaCl 4 +, but otherwise has similar properties and is considered to contain the new non-metal cation POBr 2 +. At 161·2° the molten compound has a density of 2·875 g ml −1, a dynamic viscosity of 4·92 cP, and a specific conductivity of 1·0 × 10 −3 Ω −1 cm −1. The density, surface tension, viscosity, and related properties of the reacting components POBr 3 and Ga 2Br 6 have been determined over a range of temperature and the conductivity of both liquid and solid phosphorus oxybromide has been shown to be <4·10 −8 Ω −1 cm −1.