A diastereoselective synthesis of proline containing aminophosphino cubane-type Mo3S4 clusters, (P)-[Mo3S4Cl3((1S,2R)-PPro)3]Cl (Cl) and (P)-[Mo3S4Cl3((1S,2S)-PPro)3]Cl (Cl), has been achieved in high yields by reacting the corresponding enantiomerically pure PPro ((R)- and (S)-2-[(diphenylphosphino)methyl]pyrrolidine) ligands with the Mo3S4Cl4(PPh3)3(H2O)2 complex. Circular dichroism, nuclear magnetic resonance and X-ray techniques confirm that the Cl and Cl cluster cations are diastereoisomers which combine three sources of stereogenicity provided by the cluster framework, one carbon atom of the aminophosphine ligand and the nitrogen stereogenic center. The higher stability of the (+) cation is due to stabilizing vicinal ClHN interactions as well as due to the cis-fused conformation of the bicyclic system formed upon coordination of the aminophosphine ligand.

Abstract. Hydrido molybdenum and tungsten (IV) cluster cations of formula [M3S4H3(dppe)3] + (dppe = 1,2-(bis)dimethylphosphinoethane), + (M=Mo)

The aminodiphosphane molybdenum (IV) cluster complex of formula [Mo3S4Cl3(κ 2 (P,N)-PNP)3]Cl (PNP = bis[(2-di-i-propylphosphino)ethyl]amine) [Mo-1]Cl has been isolated in high yields by reacting [Mo3S4Cl4(PPh3)3(H2O)2] with stoichiometric amounts of the PNP ligand. Characterization of [Mo-1] + by ESI-MS, 31 P{ 1 H} NMR and single-crystal X-ray diffraction confirms that aminodiphosphanes bind as bidentate ligands to the Mo3S4 unit leaving three uncoordinated phosphino groups. The dangling phosphino groups can substitute the chloride ligands and coordinate to the cluster core in the presence of AgBF4 to give the complex of formula [Mo3S4(κ 3-PNP)3](BF4)4 ([Mo-2](BF4)4). The tridentate coordination of the aminodiphosphane ligands to the Mo3S4 cluster unit in ([Mo-2] + is confirmed by 31 P{ 1 H} NMR and elemental analysis.