G. Pilloni et al., SYNTHESIS AND STRUCTURE OF THE 1ST PHOSPHINE OXIDE COMPLEX OF COPPER(I) - EVIDENCE FOR A MARKED BORDERLINE CHARACTER OF THE METAL CENTER, Journal of the Chemical Society. Dalton transactions, (11), 1993, pp. 1777-1778
The remarkable stability of [Cu(dppf)(odppf)]BF4 [dppf = 1,1'-bis(diph
enylphosphino)ferrocene, odppf = 1,1'-bis(oxodiphenylphosphoranyl)ferr
ocene], characterized in the solid state by X-ray analysis and in solu
tion by P-31 NMR spectroscopy, reveals a marked borderline character o
f copper(I).