2) or by treatment of Cu(acac)2 with three equivalents of diphenylphosphine in the presence of tri-tert-butylphosphine (eq. 3). The 1 H and 31 P NMR spectra of products from these three methods are equivalent. Compound 1 prepared via eq. 1 forms as yellow prismatic crystals that vary in length from plates to columns from a mixture of greater than 99 : 1 pentane : THF when stored at -30 °C. Two co-crystalized THF molecules per asymmetric unit could be localized with 1.