Electron Transfer from Hexameric Copper Hydrides

Abstract

The octahedral core of 84-electron LCuH hexamers does not dissociate appreciably in solution, although their hydride ligands undergo rapid intramolecular rearrangement. The single-electron transfer proposed as an initial step in the reaction of these hexamers with certain substrates has been observed by stopped-flow techniques when [(Ph3P)CuH]6 is treated with a pyridinium cation. The same radical cation has been prepared by the oxidation of [(Ph3P)CuH]6 with Cp*2Fe(+) and its reversible formation observed by cyclic voltammetry; its UV-vis spectrum has been confirmed by spectroelectrochemistry. The 48-electron trimer [(dppbz)CuH]3 has been prepared by use of the chelating ligand 1,2-bis(diphenylphosphino)benzene (dppbz).

Synthesis and Characterization of a Cu14 Hydride Cluster Supported by Neutral Donor Ligands

“…For several decades, copper hydrides have attracted widespread interest for their ability to catalyze the reduction of α,β‐unsaturated carbonyls, electron deficient alkenes, alkynes, and even CO 2 1. More recently, the structural chemistry of copper hydrides has seen increased attention, partly in an effort to better understand their reactivity 2. For example, several large Cu I hydride clusters have been structurally characterized in recent years, including [(Me 3 ‐tach) 3 Cu 6 (μ 6 ‐H)Cl 4 ] 2+ , [Cu 7 H(S 2 P(O i Pr) 2 ) 6 ], [Cu 18 H 7 (1,2‐S(C 6 H 4 )PPh 2 ) 10 (I)], [Cu 20 H 11 (S 2 P(O i Pr) 2 ) 9 ], and [Cu 28 H 15 (S 2 CN n Pr 2 ) 12 ] + 3.…”

[Cu32(H)20{S2P(OiPr)2}12]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction

“…Nevertheless, molecular compounds of the type LCuH (L=phosphine or carbene) have been reported 10. 11 Such complexes have been applied extensively in catalytic reductions in organic synthesis12 with electron‐transfer characteristics during hydrogenation 12c. Hydride complexes of the two other Group 11 metals, gold and silver, are scarce by comparison,13, 14 which is counterintuitive given their real or perceived role in metal nanoparticle formation from both a fundamental and applied point of view.…”

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

“…and [ 12 ]PF 6 (R = nPr, R 2 = aza-15-crown-5), which confine 15 hydride anions in the rhombicuboctahedral Cu 24 cage as a sort of hydrogen reservoir. [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, […”

“…(L= N-heterocyclic carbene (NHC), [9a] cyclic alkylA C H T U N G T R E N N U N G (amino)carbene (CAAC)), [10] [Cu 3 A C H T U N G T R E N N U N G (m 3 -H)(Cy 2 PCH 2 PCy 2 ) 3 ] 2 + , [11] and [ [12] have been reported. …”