Mononuclear and Polynuclear Chemistry of Rhenium (III): Its Pronounced Homophilicity

Science  18 Sep 1964:
Vol. 145, Issue 3638, pp. 1305-1307
DOI: 10.1126/science.145.3638.1305


Extensive chemical, spectrophotometric, and x-ray structural studies have shown that trivalent rhenium is strongly homophilic—that is, it tends to form bonds to other Re111 atoms—and it forms at least three different series of [ReX4]nn- complexes. The mononuclear, square complex, [ReBr4]-, adds two water molecules to give trans-[ReBr4(H2O)2]-. The binuclear complexes [Re2Cl8]2- and [Re2Br8]2- have strong Re-Re bonds, unsupported by halide bridges. The trinuclear species, [Re3X12]3- or Re3X9L3, contain the triangular Re3X9 clusters. Use of ReCI3 appears always to lead directly to products containing Re3Cl9; this unit exists in ReCl3 itself and does not appear to be kinetically labile. The [Re2X8]2- ions are obtained by reduction of ReO4- in aqueous HCl or HBr. Salts of [ReBr4(H2O)2]- can be obtained directly from solutions of ReBr3 in HBr along with numerous other compounds, some containing trinuclear clusters.