A structural and magnetic study of pentachloro-bis(1,5-dithiahexane)dirhenium

Abstract
The compound Re$_2$Cl$_5$(C$_4$H$_{10}$S$_2$)$_2$ crystallizes in the monoclinic system with a unit cell of dimensions a = 8.023 $\pm$ 0.008 $\overset{\circ}{\mathrm A}$, b = 14.355 $\pm$ 0.005 $\overset{\circ}{\mathrm A}$, c = 8.423 $\pm$ 0.006 $\overset{\circ}{\mathrm A}, \beta$ = 105.5 $\pm$ 0.1$^\circ$ occupied by two formula units. The space group is P2$_1$/m. The structure, which has been refined to a discrepancy index of 0.064, consists of binuclear units with a staggered rotational configuration. This result together with magnetic data suggests that the compound is best formulated as a zwitterion, Cl(C$_4$H$_{10}$S$_2$)$_2$Re$^+$(II) $\equiv$ Re$^-$(III)Cl$_4$, with the single unpaired electron occupying a singly degenerate orbital localized on the rhenium atom which has a formal oxidation state of III. The metal-metal bond then has an order of 3. This bonding may be compared with the Re-Re bonding in the octachlorodirhenium (III) anions and other related structures.