We have synthesised (Et4N)ReBr2(NCCH3)(2)(CO)(2)] 1 in two steps from ReBr3(CO)(3)](2-). Complex I is water and air stable and the two Br- ligands are easily exchanged for coordinating solvent molecules such as water. The reactivity of I with several ligands such as imidazole (imz) and 2-picolinic acid (2-pic) are easily possible with substitution exclusively occurring in trans-position to the carbonyl groups. The resulting complexes Re(iMZ)(2)(NCCH3)(2)(CO)(2)](+) and Re(2-pic)(NCCH3)(2)(CO)(2)] have been isolated and structurally characterised. The two acetonitrile ligands are strongly bound and are not substituted under any conditions. Complex I represents therefore the new moiety ``tran,cis-Re(NCCH3)(2)(CO)(2)](+)'' which can be considered as a further building block in organometallic chemistry. (C) 2006 Elsevier B.V. All rights reserved.