Extending the Coordination Chemistry of Molecular P₄S₃:  The Polymeric Ag(P₄S₃)⁺ and Ag(P₄S₃)₂⁺ Cations

Upon reacting P₄S₃ with AgAl(hfip)₄ and AgAl(pftb)₄ [hfip = OC(H)(CF₃)₂; pftb = OC(CF₃)₃], the compounds Ag(P₄S₃)Al(hfip)₄ 1 and Ag(P₄S₃)₂⁺[Al(pftb)₄]^- 2 formed in CS₂ (1) or CS₂/CH₂Cl₂ (2) solution. Compounds 1 and 2 were characterized by single-crystal X-ray structure determinations, Raman and solution NMR spectroscopy, and elemental analyses. One-dimensional chains of [Ag(P₄S₃)_x]_∞ (x = 1, 1; x = 2, 2) formed in the solid state with P₄S₃ ligands that bridge through a 1,3-P,S, a 2,4-P,S, or a 3,4-P,P η¹ coordination to the silver ions. Compound 2 with the least basic anion contains the first homoleptic metal(P₄S₃) complex. Compounds 1 and 2 also include the long sought sulfur coordination of P₄S₃. Raman spectra of 1 and 2 were assigned on the basis of DFT calculations of related species. The influence of the silver coordination on the geometry of the P₄S₃ cage is discussed, additionally aided by DFT calculations. Consequences for the frequently observed degradation of the cage are suggested. An experimental silver ion affinity scale based on the solid-state structures of several weak Lewis acid base adducts of type (L)AgAl(hfip)₄ is given. The affinity of the ligand L to the silver ion increases according to P₄ < CH₂Cl₂ < P₄S₃ < S₈ < 1,2-C₂H₄Cl₂ < toluene.