1, 2-bis(diphenylphosphino)ethane bridged dinuclear copper(I) complexes: Investigations of solid state and solution structures by CP/MAS 31P NMR spectroscopy, X-ray crystallography, IR spectroscopy and solution 31P NMR and 63Cu NMR spectroscopy

Three different complexes of copper(I) with bridging 1, 2-bis(diphenylphosphino)ethane (dppe), namely [Cu2 (μ-dppe) (CH3CN)6[ (ClO4)2, (1), [Cu2 (μ-dppe)2 (CH3 CN)2[ (ClO4)2 (2), and [Cu2 (μ-dppe) (dppe)2 (CH3CN)2[ (ClO4)2 (3) have been prepared. The structure of [Cu2 (μ-dppe) (dppe)2 (CH3CH)2[ (ClO4)2 has been determined by X-ray crystallography. It crystallizes in the space group P 1(with overline) with a=12.984(6) A, b=13.180(6) A, c=14.001 (3) A, α=105.23 (3), β=105.60(2), γ=112.53(4), V=1944(3) A3, and Z=1. The structure was refined by least-squares method with R=0.0365; Rw=0.0451 for 6321 reflections with Fo≥3 σ(Fo). The CP/MAS 31P and IR spectra of the complexes have been analysed in the light of available crystallographic data. IR spectroscopy is particularly helpful in identifying the presence of chelating dppe. 31P chemical shifts observed in solid state are very different from those observed in solution, and change significantly with slight changes in structure. In solution, complex 1 remains undissociated but complexes 2 and 3 undergo extensive dissociation. With a combination of room temperature 1H, 63Cu, and variable temperature 31P NMR spectra, it is possible to understand the various processes occurring in solution. (author). 39 refs., 7 tabs., 7 figs