The reactions of [NBu(4)][ReOCl4] with potentially tetradentate bis(salicylidene)amine ligands (sal(2)en = H(2)L) have been investigated. The bimetallic rhenium(V) complex [NBu(4)](2)[Re2O2Cl6(L)] (2a) is formed if the ligand precursor H(2)L contains two CH2 units bridging the imino groups of the sal(2)en fragments, while monomeric octahedral rhenium(V) compounds [ReOCl(L)] (2b-d) are formed if three carbon atoms form the bridge. In contrast to similar technetium compounds where a symmetrical equatorial arrangement is observed, the rhenium complex exhibits an asymmetric nonplanar coordination of the ligand. The crystal structures of mono- and bimetallic derivatives have been determined. Crystal data are as follows : 2a, monoclinic, space group P2(1)/c, a = 23.003(3) Angstrom, b = 13.385(1) Angstrom, c = 24.344(4) Angstrom, beta = 93.88(7)degrees, R = 0.045 for 7974 reflections; 2b, monoclinic, space group P2(1)/n, a = 12.094(2) Angstrom, b = 15.410(2) Angstrom, c = 14.857(3) Angstrom, beta = 108.49(2)degrees, R = 0.034 for 3415 reflections; 2c, monoclinic, space group P2(1)/n, a = 10.748(1) Angstrom, b = 16.695(2) Angstrom, c = 10.893(2) Angstrom, beta = 105.61(1)degrees, R = 0.028 for 2736 reflections.