A structural study of ligand exchange on chalcogen‐passivated copper nanoclusters is far less developed. Herein, we report the synthesis of polyhydrido copper nanoclusters [Cu20H11{Se2P(O
iBu)2}9] (2) passivated by Se‐donor ligands via ligand replacement reaction on [Cu20H11{S2P(O
iPr)2}9] (1) with NH4[Se2P(O
iBu)2]. In parallel to the synthesis of 2, cluster [Cu20H11{S2P(CH2CH2Ph)2}9] (4) was produced by the ligand exchange reaction on a new derivative of 1, that is [Cu20H11{S2P(O
nPr)2}9] (3). Solid state structures of both clusters 2 and 4 were unequivocally established by single‐crystal X‐ray diffraction studies and cluster 4 epitomizes exceptional case to preserve both the shape and size of the nanocluster during the course of ligand exchange. Structurally precise cluster 2 is the second example where the copper hydride nanocluster is stabilized by Se‐donor ligands. The anatomy of 2 can be visualized as a twisted cuboctahedral Cu13 core, two triangular faces of which are capped by a Cu6 cupola and a single Cu atom along the C3 rotational axis.
The prnr spectra of paramagnetic octahedral complexes of nickel(I1) with ethylene(dinitril0)-N,N,N',N'-tetraacetate (EDTA), 1,2-propane( dinitri10)-N,N, N', "tetraacetate (PDTA), and trans-1,P-cyclohexane(dinitri10)-N, N, N', "-tetraacetate (CyDTA) are reported. The spectra are interpreted on the basis of the well-established dependence of hyperfine coupling constant upon dihedral angle. It is postulated that the in-plane axial acetate protons do not contribute to the spectra of any of the complexes, and the cyclohexane ring protons nearest the metal are also not observed. All the chelate rings are puckered, but the acetate chelate rings of Ni(EDTA)z-are not as puckered as those in Ni(EDDA). The out-ofplane acetate rings of Ni(CyDTA)Z-are the most nearly planar of the acetate rings studied. It is surmised that the average ligand coordination number is between 5 and 6 with Ni(CyDTA)2-having a greater fraction of hexadentate species than Ni(EDTA)2-or Ni(PDTA)*-. The acetate protons are found t o undergo stereospecific base-catalyzed deuterium exchange; the out-of-plane acetate protons exchange about lo4 times faster than the in-plane acetate protons, and an axial proton exchanges about three times faster than an equatorial proton. No significant nitrogen inversion was observed for Ni-(CYDTA)~-in l week a t 100'. However, nitrogen inversion is the mode of acetate scrambling in Ni(PDTA)2-, while A,A conversion and nitrogen inversion contribute equally to acetate scrambling in Ni(EDTA)*-.(2) The symbols A and A will be used to designate the absolute configurations of the complexes. The assignments are based on the corresponding Ni(EDDA) isomers in which the two acetates are both out of plane. A more appropriate, but more cumbersome, symbolism is described in a later section of this paper and in (1960), have reviewed earlier work critically in presenting thermodynamic data which indicate a coordination number of 6 for EDTA in Ni(EDTA)2 -.
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