MULTIPLE BONDS BETWEEN MAIN-GROUP ELEMENTS AND TRANSITION-METALS .153. RHENIUM(V) OXO COMPLEXES WITH TETRADENTATE SCHIFF-BASES - STRUCTURALCONSIDERATIONS

The reactions of [NBu(4)][ReOCl4] with potentially tetradentate bis(sa licylidene)amine ligands (sal(2)en = H(2)L) have been investigated. Th e bimetallic rhenium(V) complex [NBu(4)](2)[Re2O2Cl6(L)] (2a) is forme d if the ligand precursor H(2)L contains two CH2 units bridging the im ino groups of the sal(2)en fragments, while monomeric octahedral rheni um(V) compounds [ReOCl(L)] (2b-d) are formed if three carbon atoms for m the bridge. In contrast to similar technetium compounds where a symm etrical equatorial arrangement is observed, the rhenium complex exhibi ts an asymmetric nonplanar coordination of the ligand. The crystal str uctures of mono- and bimetallic derivatives have been determined. Crys tal data are as follows: 2a, monoclinic, space group P2(1)/c, a = 23.0 03(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, spac e group P2(1)/n, a = 12.094(2) Angstrom, b = 15.410(2) Angstrom, c = 1 4.857(3) Angstrom, beta = 108.49(2)degrees, R = 0.034 for 3415 reflect ions; 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.