Chinese Puzzle Molecule: A 15 Hydride, 28 Copper Atom Nanoball

Abstract

The syntheses of the first rhombicuboctahedral copper polyhydride complexes [Cu28 (H)15 (S2 CNR)12 ]PF6 (NR=N(n) Pr2 or aza-15-crown-5) are reported. These complexes were analyzed by single-crystal X-ray and one by neutron diffraction. The core of each copper hydride nanoparticle comprises one central interstitial hydride and eight outer-triangular-face-capping hydrides. A further six face-truncating hydrides form an unprecedented bridge between the inner and outer copper atom arrays. The irregular inner Cu4 tetrahedron is encapsulated within the Cu24 rhombicuboctahedral cage, which is further enclosed by an array of twelve dithiocarbamate ligands that subtends the truncated octahedron of 24 sulfur atoms, which is concentric with the Cu24 rhombicuboctahedron and Cu4 tetrahedron about the innermost hydride. For these compounds, an intriguing, albeit limited, H2 evolution was observed at room temperature, which is accompanied by formation of the known ion [Cu8 (H)(S2 CNR)6 ](+) upon exposure of solutions to sunlight, under mild thermolytic conditions, and on reaction with weak (or strong) acids.

Neutron Diffraction Studies of a Four-Coordinated Hydride in Near Square-Planar Geometry

“…[Cu 20 (H) 11 {S 2 P(O i Pr) 2 } 9 ] was prepared using a previously reported synthetic method; 12 details of the synthesis and crystal preparation are provided in the Experimental Section. A yellow crystal with dimensions of 0.20 mm × 0.50 mm × 0.65 mm (0.065 mm 3 ) was placed on a single-crystal diffractometer.…”

“…The neutron diffraction analysis of [Cu 20 (H) 11 {S 2 P-(O i Pr) 2 } 9 ] revealed that the Cu 2 -centered elongated triangular orthobicupola structure consists of 20 Cu atoms, 11 hydrides, and nine dithiophosphate (dtp) ligands ( Figure 2a). The precise locations of the 11 hydrides, whose positions are similar to those identified from X-ray data and DFT calculations, were determined.…”

“…One of these copper polyhydrides characterized by neutron diffraction is the recently communicated "Chinese puzzle molecule", [Cu 28 (H) 15 {S 2 CN( n Pr) 2 } 12 ](PF 6 ), 11 which contains one central interstitial hydride (μ 4 -H) in a tetrahedral geometry, eight outer-triangular-face-capping hydrides (μ 3 -H), and six square face-truncating hydrides [2(μ 6 -H)+4(μ 5 -H)] to form an unprecedented bridge between the inner tetrahedral and outer rhombicuboctahedral copper atom arrays ( Figure 1). The other copper polyhydride is [Cu 20 (H) 11 {S 2 P(O i Pr) 2 } 9 ], which is the first example of an elongated triangular orthobicupola copper atom array of C 3h symmetry. 12 This cluster was characterized by X-ray diffraction, multinuclear NMR spectroscopy, electrospray ionization (ESI) mass spectroscopy, and DFT calculations.…”

“…Thus, the characterization of the square planarity revealed in three (i.e., μ 4 -H) of the 11 hydrides of the Cu 20 cluster using the same technique will be of urgent interest. For this reason, we performed a neutron diffraction study and herein report the high-resolution, single-crystal neutron diffraction results for [Cu 20 (H) 11 {S 2 P(O i Pr) 2 } 9 ], which unequivocally authenticate a four-coordinated hydride in near square-planar geometry.…”

Facile Insertion of Carbon Dioxide into Cu2(μ‐H) Dinuclear Units Supported by Tetraphosphine Ligands

“…[7] By contrast, as to copper hydride complexes with lower nuclearity, which are potentially important as hydrogen-donor key reductants, very few isolated and characterized examples of di-and trinuclear complexes, […”