Abstract
Reduction of the tetranuclear {[(t-Bu)NPPh2]-Cr[mu-(t-Bu)NPPh2]Cr}(2)(mu-Cl)(2) (1) with either KC8 or vinyl Grignard afforded the dinuclear, mixed-valence (Me3P)Cr[mu-(t-Bu)NPPh2](3)Cr (2) with the two metals possessing distinctively different coordination environments. According to the formulation of 2 as Cr(I)/Cr(II) mixed-valence species, 2 acts as a self-activating catalyst, producing under pressure of ethylene a mixture of 1-butene and 1-hexene. Activation with three different activators selectively produced three different products, namely, 1-butene with TEAL, 1-hexene with DMAO/TEAL, and LAO-free highly linear HMWPE with DMAO. Mixtures of 1-hexene and 1-butene were also obtained upon activation with vinyl Grignard. In this case it was possible to isolate, albeit in very low yield, an intriguing butadiene/butadiene-diyl cluster, {[(eta(4)-butadiene)Cr (mu,eta(4)-butaclienediyl)(mu-NP)Mg](2)(mu-Cl)(4)Mg(THF)(2)}{[(THF)(3)Mg](2)(mu-Cl)(3)}(2) (3), which is also a highly selective self-activating trimerization catalyst.