A thorium metallacyclopentadiene complex: a combined experimental and computational study†
Abstract
The synthesis, structure, and reactivity of a thorium metallacyclopentadiene were comprehensively studied. The reduction of (η5-C5Me5)2ThCl2 (1) with potassium graphite (KC8) in the presence of diphenylacetylene (PhCCPh) yields the first thorium metallacyclopentadiene complex (η5-C5Me5)2Th(η2-C4Ph4) (2). Density functional theory (DFT) studies suggest that the 5f orbitals are involved in the bonding of the metallacyclopentadiene Th–(η2-CC–CC) moiety. Compared to the thorium metallacyclopropene, complex 2 shows a distinctively different reactivity towards diazoalkanes and organic azides such as Me3SiCHN2, 9-diazofluorene and p-tolylN3, leading to the formation of the six-membered hydrazido complexes (η5-C5Me5)2Th[N(NCHSiMe3)(C4Ph4)] (3) and (η5-C5Me5)2Th[N(NC(C12H8))(C4Ph4)] (4) and the seven-membered bis(triazenido) complex (η5-C5Me5)2Th[N(NN(p-tolyl))(C4Ph4)N(NN(p-tolyl))] (5), respectively.