Dynamic Copper(I) and Silver(I) Complexes of Tri-tert-butyl-cyclotriphosphane

The reaction of cyclo-(P₃tBu₃) with Cu^I and Ag^I salts led to the di- and tetranuclear complexes [Cu_n(micro-Br)_n{micro-cyclo-(P₃tBu₃)-κP¹,κP²}₂] with n = 2 (1) and n = 4 (2) and [Ag_n(OTf)_n(CH₃CN)_{2 n -2}{micro-cyclo-(P₃tBu₃)-κP¹,κP²}₂] with n = 2 (4) and n = 4 (5). Complexes 1, 2, 4 and 5 were isolated as crystalline powders or single crystals and characterized by X-ray diffraction. In solution, these complexes exhibit a dynamic equilibrium which involves continuous dissociation and reforming of phosphorus-metal bonds leading to isomeric intermediates. This behavior was demonstrated by low-temperature ³¹P{¹H} NMR spectroscopy and the conclusions were corroborated by DFT calculations.