The crystal structures of tetra­kis­(μ-n-butyrato-κ(2) O:O′)bis[bromidorhenium(III)] and tetra­kis­(μ-n-butyrato-κ(2) O:O′)bis[chlorido­rhenium(III)] aceto­nitrile disolvate

The title complexes, [Re(2)Br(2)(O(2)CC(3)H(7))(4)], (1), and [Re(2)(O(2)CC(3)H(7))(4)Cl(2)]·2CH(3)CN, (2), both exhibit paddlewheel structures with four carboxyl­ate ligands bridging two Re(III) atoms. The Re—Re distances are 2.2325 (2) and 2.2299 (3) Å, indicating quadruple bonds between the Re(III) atoms in each complex. Both complexes contain an inversion center at the mid-point of the Re—Re bond. The Re—Br bond [2.6712 (3) Å] in (1) is 0.1656 (6) Å longer than the Re—Cl distance [2.5056 (5) Å] of (2). In (2), the N atom of each co-crystallized aceto­nitrile solvent mol­ecule is nearly equidistant between and in close contact with two carboxyl­ate C atoms.