Proton solvates, H +· nH 2O· mL, formed by diphosphine dioxides with chlorinated cobalt(III) dicarbollide acid

Abstract

Interaction of hydrated proton, H 5O 2 +·(H 2O) 4, in dichloroethane solutions with diphosphine dioxides (L) having methyl (Ph 4Me), ethyl (Ph 4Et) and polyoxyethylene chains (Ph 4PEG) linking two diphenyl phosphine oxide groups has been investigated. A bulky counter ion: chlorinated cobalt(III) bis(dicarbollide), [Co(C 2B 9H 8Cl 3) 2] −, minimizes perturbation of the cation. At low concentrations, Ph 4Et and Ph 4PEG form anhydrous 1:1 complexes with (P )O–H +–O( P) fragment having very strong symmetrical H-bonds. At these conditions Ph 4Me form another compound, H 5O 2 +·L(H 2O) 2, due to lower P O basicity and optimal geometry of the chelate cycle. At higher concentrations, Ph 4Me and Ph 4Et form isostructural complexes H 5O 2 +·L 2, whereas Ph 4PEG forms only a 1:1 complex with proton dihydrate, H 3O +·H 2O. In excess of free Ph 4Me and Ph 4Et a water molecule is introduced to the first coordination sphere of H 5O 2 + and the average molar ratio L/H 5O 2 + of the complexes exceeds 2. The composition of these complexes as a function of L and its concentration is discussed.