research communications Acta Cryst. (2015). E71, 1219–1221 doi:10.1107/S2056989015017429 1219 Received 8 September 2015 Accepted 17 September 2015 Edited by C. Rizzoli, Universita degli Studi di Parma, Italy † Keywords: crystal structure; rhenium(III); cluster; alkylcarboxylate complex; quadruple metal–metal bond; hydrogen bonding CCDC reference: 1425634 Supporting information: this article has supporting information at journals.iucr.org/e Crystal structure of di-l-isobutyrato-j 4 O:O 0 -bis[cis- dichlorido(dimethyl sulfoxide-jS)rhenium(III)] Alexander A. Golichenko* and Alexander V. Shtemenko Department of Inorganic Chemistry, Ukrainian State University of Chemical Technology, Gagarin Ave. 8, Dnipropetrovsk 49005, Ukraine. *Correspondence e-mail: golichenko_alex@i.ua The title compound, [Re 2 (C 3 H 7 COO) 2 Cl 4 {(CH 3 ) 2 SO} 2 ], comprises binuclear complex molecules [Re—Re = 2.24502 (13) A ˚ ] involving cis-oriented double carboxylate bridges, four equatorial chloride ions and two weakly bonded O atoms from dimethyl sulfoxide ligands in the axial positions at the Re III atoms. In the crystal, molecules are linked into corrugated layers parallel to (101) by very weak C—HCl and C—HO hydrogen-bonding interactions. C— HCl hydrogen bonding provides the links between layers to consolidate a three-dimensional framework. 1. Chemical context Binuclear rhenium(III) clusters are classical complexes with a unique quadruple metal–metal bond (Cotton et al., 2005, Golichenko & Shtemenko, 2006). In our previous work we have shown that such compounds with chloride and alkyl- carboxylate equatorial ligands exhibit antitumor, antiradical and hepato- and nephroprotective biological activity with low toxicity (Dimitrov et al. , 1978, Shtemenko et al. , 2007, 2008, 2009, 2013). Labile axial ligands and equatorial chloride groups are the reactive centers in interactions with other chemical compounds and biological macromolecules in vitro and in vivo (Shtemenko et al. , 2013). In this context, we present the synthesis and the structure of the title dirhenium(III) complex with isobutyrate equatorial ligands as biologically active groups, which can exhibit antitumor activity in the tetra- carboxylate compound Re 2 (i-C 3 H 7 COO) 4 Cl 2 (Shtemenko et al., 2007). ISSN 2056-9890