The ionic salts of rhenium(IV) of formula (Cat)(2)[Rel(6)] with Cat = Li+ (1), Na+ (2), K+ (3), Rb+, (4), Cs+ (5), NH4+ (6), and AsPh4+ (7) [AsPh4+ = tetraphenylarsonium cation] have been synthesized, and the structures of two of them (namely, 3 and 6) were determined by single-crystal X-ray diffraction. 3 crystallizes in the monoclinic system, space group Pn, with a = 7.815(1) Angstrom, b = 7.874(1) Angstrom, c = 11.335(1) Angstrom, beta = 90.38(1)degrees, and Z = 2 whereas 6 crystallizes in the tetragonal system, space group P4/mnc, with a = 7.881(1) Angstrom, b = 7.881(1) Angstrom, c = 11.474(2) Angstrom, and Z = 2. The structures of 3 and 6 are made up of discrete [Rel(6)](2-) anions and K+ (3) or NH4+ (6) cations held together by electrostatic forces (3 and 6) and N-H...I hydrogen bonds (6). The rhenium(IV) cation in 3 and 6 is surrounded by six iodide ligands in an octahedral environment with the Re-I bond lengths varying in a very narrow range [2.704(3)-2.738(3) and 2.716(1)-2.722(2) Angstrom for 3 and 6, respectively]. The [Rel(6)](2) anions in 6 describe a tetragonally distorted body-centered cubic structure. In 3, the arrangement of these units is similar but more distorted, The different arrangement of the anions in 3 and 6 accounts for the centrosymmetric (6) and non-centrosymmetric (3) structures observed. The magnetic properties of 1-7 were investigated in the temperature range 2.0-300 K. The magnetic behavior of 7 is that of a magnetically diluted Re(IV) complex with a large value of the zero-field splitting of the ground level (\2D\ = 49.8 cm(-1)) whereas those of 1, 2, and 4-6 are typical of antiferromagnetically coupled systems with susceptibility maxima at 28 (1), 27 (2), 21 (4). 16 (5), and 20 K (6). In the case of compound 3, its magnetic behavior in the high-temperature range is parallel to that observed in the parent salts but below 24 K it is a weak ferromagnet with a canting angle of ca. 1.2degrees.