| Abstract
| - The new d10−d10 dimerCu2(dppm)2(O2CCH3)+(as a BF4- salt) has been prepared andcharacterized by X-raycrystallography and by 1H and 31P NMR,vibrational, and electronic spectroscopy. The compound isluminescentat 77 K but not at room temperature. MO calculations and geometryoptimizations have been performed usingthe EHMO and DFT models, respectively. In the solid state theCu2 separation is 2.788(1) Å whereν(Cu2) =87.7 cm-1, indicating the presence of weakCu···Cu interactions. The MO calculations predict thatthe lowestenergy excited states are MLCT from Cu to phenylphosphine/acetate.These predictions have been confirmed byelectronic spectroscopy via a comparison betweenCu2(dppm)2(O2CCH3)+andCu2(dppm)2(O2CC6H5)+.Insolutions, both NMR (1H and 31P) andluminescence spectroscopies (time-resolved spectra and τeanalysis)demonstrate the presence of two metal species in solutions: Cu2(dppm)2(O2CCH3)+andCu2(dppm)(O2CCH3)+.The dimer crystallizes in the triclinic space groupP1̄ with a = 11.572(2) Å,b = 12.552(2) Å, c = 19.543(3)Å,α = 85.274(12)°, β = 82.108(11)°, γ =68.950(12)°, and Z = 2.
- The d10−d10Cu2(dppm)2(O2CCH3)+dimer is luminescent at 77 K and dissociates in solution to produce thebicoordinated and luminescentCu2(dppm)(O2CCH3)+complex. Both emit from 3MLCT* states (Cu →phenylphosphine/acetate).
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