Diselenophosphate-Induced Conversion of an Achiral [Cu20 H11 \S2 P(OiPr)2 \9 ] into a Chiral [Cu20 H11 \Se2 P(OiPr)2 \9 ] Polyhydrido Nanocluster
Résumé
A polyhydrido copper nanocluster, [Cu20H11{Se2P(OiPr)2}9] (2H), which exhibits an intrinsically chiral inorganic core of C3 symmetry, was synthesized from achiral [Cu20H11{S2P(OiPr)2}9] (1H) of C(3h) symmetry by a ligand-exchange method. The structure has a distorted cuboctahedral Cu13 core, two triangular faces of which are capped along the C3 axis, one by a Cu6 cupola and the other by a single Cu atom. The Cu20 framework is further stabilized by 9 diselenophosphate and 11 hydride ligands. The number of hydride, phosphorus, and selenium resonances and their splitting patterns in multinuclear NMR spectra of 2H indicate that the chiral Cu20H11 core retains its C3 symmetry in solution. The 11 hydride ligands were located by neutron diffraction experiments and shown to be capping μ3-H and interstitial μ5-H ligands (in square-pyramidal and trigonal-bipyramidal cavities), as supported by DFT calculations on [Cu20H11(Se2PH2)9] (2H') as a simplified model.