Proton solvates, HC$nH2O$mL, formed by diphosphine dioxides with chlorinated cobalt(III) dicarbollide acid

Interaction of hydrated proton, H5O2 C$(H2O)4, in dichloroethane solutions with diphosphine dioxides (L) having methyl (Ph4Me), ethyl (Ph4Et) and polyoxyethylene chains (Ph4PEG) linking two diphenyl phosphine oxide groups has been investigated. A bulky counter ion: chlorinated cobalt(III) bis(dicarbollide), [Co(C2B9H8Cl3)2]K, minimizes perturbation of the cation. At low concentrations, Ph4Et and Ph4PEG form anhydrous 1:1 complexes with (Pa)O–HC–O(aP) fragment having very strong symmetrical H-bonds. At these conditions Ph4Me form another compound, H5O2 C$L(H2O)2, due to lower PaO basicity and optimal geometry of the chelate cycle. At higher concentrations, Ph4Me and Ph4Et form isostructural complexes H5O2 C$L2, whereas Ph4PEG forms only a 1:1 complex with proton dihydrate, H3OC$H2O. In excess of free Ph4Me and Ph4Et a water molecule is introduced to the first coordination sphere of H5O2 C and the average molar ratio L/H5O2 C of the complexes exceeds 2. The composition of these complexes as a function of L and its concentration is discussed. q 2005 Elsevier B.V. All rights reserved