Multiple Bonds between Main Group Elements and Transition Metals. 153.1 Rhenium(V) Oxo Complexes with Tetradentate Schiff Bases: Structural Considerations

The reactions of [NBu 4 ][ReOCl 4 ] with potentially tetradentate bis(salicylidene)amine ligands (sal 2 en = H 2 L) have been investigated. The bimetallic rhenium(V) complex [NBu 4 ] 2 [Re 2 O 2 Cl 6 (L)] ( 2a ) is formed if the ligand precursor H 2 L contains two CH 2 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 P 2 1 / c, a = 23.003(3) Å, b = 13.385(1) Å, c = 24.344(4) Å, β = 93.88(7)°, R = 0.045 for 7974 reflections; 2b, monoclinic, space group P 2 1 / n, a = 12.094(2) Å, b = 15.410(2) Å, c = 14.857(3) Å, β = 108.49(2)°, R = 0.034 for 3415 reflections; 2c, monoclinic, space group P 2 1 / n, a = 10.748(1) Å, b = 16.695(2) Å, c = 10.893(2) Å, β = 105.61(1)°, R = 0.028 for 2736 reflections.