(CuI)3P4S4: Preparation, structural, and NMR spectroscopic characterization of a copper(I) halide adduct with β-P4S4

Abstract

(CuI)3P4S4 is obtained by reaction of stoichiometric amounts of CuI, P, and S in evacuated silica ampoules. The yellow compound consists of monomeric β-P4S4 cage molecules that are separated by hexagonal columns of CuI. (CuI)3P4S4 crystallizes isotypic to (CuI)3P4Se4 in the hexagonal system, space group P63cm (no. 185) with a= 19.082(3), c = 6.691 (1) Å, V= 2109.9(6) Å3, and Z=6. Three of the four phosphorus atoms are bonded to copper, whereas no bonds between copper and sulfur are observed. The two crystallographically distinct copper sites are clearly differentiated by 65Cu magic-angle spinning (MAS) NMR spectroscopy. Furthermore, an unequivocal assignment of the 31P MAS-NMR spectra is possible on the basis of homo- and heteronuclear dipole-dipole and scalar interactions. Dipolar coupling to the adjacent quadrupolar spins 63.65Cu generates a clear multiplet structure of the peaks attributable to P1 and P2, respectively. Furthermore, the utility of a newly developed two-dimensional NMR technique is illustrated to reveal direct connectivity between P atoms based on (31P-31P) scalar interactions.