Diastereomeric metallatetrahedron complexes of the type Re-2(MPPh3)(M ' PPh3)(mu-PCy2)(CO)(7)(-)-thiocamphanate (M = Ag, Au, M ' = Cu, Ag, Au): synthesis, structure and CD data

Four pairs of diastereomeric metallatetrahedron complexes of the type Re-2( MPPh3)(M'PPh3) (mu -PCy2)(CO)(7) (-)-thiocamphanate have been synthesized, with identical (M = M' = Au (5a, 5b) and Ag (6a, 6b)) and with mixed coinag e metals (M = Au, M' = Ag (8a, 8b) and Cu (9a, 9b)). After separation, the absolute configuration was determined by single crystal X-ray crystallograp hy for 6a, 8a and 9a. In agreement with solution (P-31 and H-1 NMR) spectra l data, the thiocamphanate acts as a mu -S bridging bidentate ligand along the Re-coinage metal edge; in the mixed coinage metal complexes coordinatio n involves the lower homologue of the coinage metals. Signs of the long wav elength absorption bands in the CD spectra were found to correlate with the counter (A) or clockwise (C) configuration of the chiral transition metal core.