Diastereomeric metallatetrahedron complexes of the type Re2(MPPh3)(M′PPh3)(µ-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 Re2(MPPh3)(M′PPh3) (μ-PCy2)(CO)7(−)-thiocamphanate have been synthesized, with identical (M = M′ = Au (5a, 5b) and Ag (6a, 6b)) and with mixed coinage metals (M = Au, M′ = Ag (8a, 8b) and Cu (9a, 9b)). After separation, the absolute configuration was determined by single crystal X-ray crystallography for 6a, 8a and 9a. In agreement with solution (31P and 1H NMR) spectral data, the thiocamphanate acts as a μ-S bridging bidentate ligand along the Re-coinage metal edge; in the mixed coinage metal complexes coordination involves the lower homologue of the coinage metals. Signs of the long wavelength absorption bands in the CD spectra were found to correlate with the counter (A) or clockwise (C) configuration of the chiral transition metal core.