A Copper(I) Homocubane Collapses to a Tetracapped Tetrahedron Upon Hydride Insertion

Abstract

The hydrido copper(I) and silver(I) clusters incorporating 1,1-dicyanoethylene-2,2-dithiolate (i-MNT) ligands are presented in this paper. Reactions of M(I) (M = Cu, Ag) salts, [Bu(4)N](2)[S(2)CC(CN)(2)], with the anion sources ([Bu(4)N][BH(4)] for H(-), [Bu(4)N][BD(4)] for D(-)) in an 8:6:1 molar ratio in THF produce octanuclear penta-anionic Cu(I)/Ag(I) clusters, [Bu(4)N](5)[M(8)(X){S(2)CC(CN)(2)}(6)] (M = Cu, X = H, 1(H); X = D, 1(D); M = Ag, X = H, 2(H); X = D, 2(D)). They can also be produced from the stoichiometric reaction of M(8)(i-MNT)(6)(4-) with the ammonium borohydride. All four compounds have been fully characterized spectroscopically ((1)H and (13)C NMR, IR, UV-vis) and by elemental analyses. The deuteride-encapsulated Cu(8)/Ag(8) clusters of 1(D) and 2(D) are also characterized by (2)H NMR. X-ray crystal structures of 1(H) and 2(H) reveal a hydride-centered tetracapped tetrahedral Cu(8)/Ag(8) core, which is inscribed within an S(12) icosahedron formed by six i-MNT ligands, each in a tetrametallic-tetraconnective (μ(2), μ(2)) bonding mode. The encapsulated hydride in 2(H) is unequivocally characterized by both (1)H and (109)Ag NMR spectroscopies, and the results strongly suggest that the hydride is coupled to eight magnetically equivalent silver nuclei on the NMR time scale. Therefore, a fast interchange between the vertex and capping silver atoms in solution gives a plausible explanation for the perceived structural differences between the Ag(8) geometry deduced from the X-ray structure and the NMR spectra.

Synthesis, Characterization, and Reactivity of the Group 11 Hydrido Clusters [Ag6H4(dppm)4(OAc)2] and [Cu3H(dppm)3(OAc)2]

“…Consequently, Ag I -H complexes have proven to be relatively rare. 21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Moreover, the examples isolated thus far are either homometallic monohydrides, e.g., [ 10 ] 2+ ). 39 Herein, we report the synthesis and characterization of the first structurally characterized homometallic silver polyhydrido cluster, [Ag 6 H 4 (dppm) 4 (OAc) 2 ].…”

Reactivities of Interstitial Hydrides in a Cu11 Template: En Route to Bimetallic Clusters

“…Further,t he stability of 1 was investigated by variable temperature 1 Hand 31 P{ 1 H} NMR (30 to 55 8 8C) in acetone-d 6 (Figure S28 and S29). Ther esults indicate that raising temperature leads to the decomposition of 1 to [Cu 8 H{S 2 P(O i Pr) 2 } 6 ] + , [18] conversion of the alkynyl ligands to styrene,with 1 HNMR resonances in the range 5.20-7.13 ppm, and liberation of H 2 (4.53 ppm). At higher temperature,t he 31 PNMR spectrum of 1,w hich resonates at 99.5 ppm, shifts downfield to 100.4 ppm, which is the resonance frequency of [Cu 8 H{S 2 P(O i Pr) 2 } 6 ] + .Based on these observations,o ne can conclude that, at an elevated temperature (55 8 8C), cluster 1 is not as stable as its precursor template, H 2 Cu 11 .…”

Synthesis and X‐Ray Crystallographic Characterisation of Frustum‐Shaped Ligated [Cu18H16(DPPE)6]2+ and [Cu16H14(DPPA)6]2+ Nanoclusters and Studies on Their H2 Evolution Reactions

“…Face‐centred cubic (FCC) is a common structural motif in many examples of single or twinned crystalline Au NCs and Ag FCC nanocrystals can grow from the Au seed nanocrystals that have triangular‐bifrustum structures . The organisation of the copper kernel in polyhydrido Cu NCs normally adopt zonohedron and other polyhedra such as dodecahedron, tetrahedron, rhombicuboctahedron, orthobicupola, distorted cuboctahedron and octahedron . The FCC kernel motif for Cu NCs was unknown until Chakrahari et al.…”