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ReF6 is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is zero-dimensional and consists of two rhenium hexafluoride molecules. Re6+ is bonded in an octahedral geometry to six equivalent F1- atoms. All Re–F bond lengths are 1.87 Å. F1- is bonded in a single-bond geometry to one Re6+ atom.
ReF6 is beta Np structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four rhenium hexafluoride molecules. Re6+ is bonded in an octahedral geometry to six F1- atoms. All Re–F bond lengths are 1.87 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Re6+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Re6+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Re6+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Re6+ atom.
K2ReF6 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. K1+ is bonded to twelve equivalent F1- atoms to form distorted KF12 cuboctahedra that share corners with six equivalent KF12 cuboctahedra, corners with three equivalent ReF6 octahedra, faces with eight equivalent KF12 cuboctahedra, and faces with three equivalent ReF6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are a spread of K–F bond distances ranging from 2.86–3.02 Å. Re4+ is bonded to six equivalent F1- atoms to form ReF6 octahedra that share corners with six equivalent KF12 cuboctahedra and faces with six equivalent KF12 cuboctahedra. All Re–F bond lengths are 1.99 Å. F1- is bonded in a distorted single-bond geometry to four equivalent K1+ and one Re4+ atom.
CsReF6 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Cs1+ is bonded to twelve equivalent F1- atoms to form CsF12 cuboctahedra that share corners with six equivalent ReF6 octahedra, edges with six equivalent CsF12 cuboctahedra, and faces with two equivalent ReF6 octahedra. The corner-sharing octahedral tilt angles are 37°. There are six shorter (3.18 Å) and six longer (3.41 Å) Cs–F bond lengths. Re5+ is bonded to six equivalent F1- atoms to form ReF6 octahedra that share corners with six equivalent CsF12 cuboctahedra and faces with two equivalent CsF12 cuboctahedra. All Re–F bond lengths are 1.92 Å. F1- is bonded in a distorted single-bond geometry to two equivalent Cs1+ and one Re5+ atom.
Rb2ReF6 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Rb1+ is bonded to twelve equivalent F1- atoms to form distorted RbF12 cuboctahedra that share corners with six equivalent RbF12 cuboctahedra, corners with three equivalent ReF6 octahedra, faces with eight equivalent RbF12 cuboctahedra, and faces with three equivalent ReF6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are a spread of Rb–F bond distances ranging from 3.02–3.15 Å. Re4+ is bonded to six equivalent F1- atoms to form ReF6 octahedra that share corners with six equivalent RbF12 cuboctahedra and faces with six equivalent RbF12 cuboctahedra. All Re–F bond lengths are 1.99 Å. F1- is bonded in a distorted single-bond geometry to four equivalent Rb1+ and one Re4+ atom.
K3ReClF6 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 10-coordinate geometry to two equivalent Cl1- and eight F1- atoms. Both K–Cl bond lengths are 3.08 Å. There are a spread of K–F bond distances ranging from 2.88–3.05 Å. In the second K1+ site, K1+ is bonded to two equivalent Cl1- and four equivalent F1- atoms to form KCl2F4 octahedra that share corners with four equivalent ReF6 octahedra and corners with six equivalent KCl2F4 octahedra. The corner-sharing octahedra tilt angles range from 0–72°. Both K–Cl bond lengths are 3.05 Å. All K–F bond lengths are 3.14 Å. Re4+ is bonded to six F1- atoms to form ReF6 octahedra that share corners with four equivalent KCl2F4 octahedra. The corner-sharing octahedral tilt angles are 72°. All Re–F bond lengths are 1.99 Å. Cl1- is bonded to six K1+ atoms to form corner-sharing ClK6 octahedra. The corner-sharing octahedra tilt angles range from 0–29°. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to three equivalent K1+ and one Re4+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to four K1+ and one Re4+ atom.
The results of tests carried out to determine the properties of polytetrafluorethylene (PTFE) impregnated with rhenium oxides are presented. The tests included measurement of physical properties of the impregnated material and investigation of the effects of preparation process variables. Based on the latter tests a mechanism to describe the permeation process is postulated which identifies the rate controlling step to be diffusion of ReF6 molecules into the solid during the initial ReF6 soak. Physical property tests indicated that the electronic conductance is increased by many orders of magnitude while the desirable properties of the PTFE remain virtually unchanged.