The coordination chemistry of copper(I) in liquid ammonia, trialkyl and triphenyl phosphite, and tri-n-butylphosphine solution.

The coordination chemistry of the solvate complexes of the relatively soft electron-pair acceptor copper(I) has been studied in solution and solid state in seven solvents with strong electron-pair donor properties, liquid ammonia, trimethyl, triethyl, triisopropyl, tri-n-butyl and triphenyl phosphite, and tri-n-butylphosphine. The solvate complexes have been characterised by means of EXAFS and 63Cu NMR spectroscopy, and in some cases also by 65Cu NMR spectroscopy. The copper(I) ion is three-coordinated, most probably in a coplanar trigonal fashion, in liquid ammonia with a mean Cu-N bond distance of 2.00(1) Angstroms. No 63Cu NMR signal has been detected from the ammonia solvated copper(I) ion in liquid ammonia, which supports a three-coordination. The phosphite and phosphine solvated copper(I) ions are tetrahedral with Cu-P bond distances in the range 2.24-2.28 Angstrom in both solution and solid state as determined by EXAFS spectroscopy. The tetrahedral configuration of these complexes has been confirmed by 63Cu and 65Cu NMR spectroscopy through the J(63Cu-31P) and J(65Cu-31P) couplings. The fact that two of the investigated complexes, [Cu(P(OC6H5)3)4]+ and [Cu(P(C4H9)3)4]+, are 63Cu and 65Cu NMR silent is probably caused by a significantly angular distorted tetrahedral configuration.