A thorium metallacyclopentadiene complex: a combined experimental and computational study.

The synthesis, structure, and reactivity of a thorium metallacyclopentadiene were comprehensively studied. The reduction of (η(5)-C5Me5)2ThCl2 () with potassium graphite (KC8) in the presence of diphenylacetylene (PhC[triple bond, length as m-dash]CPh) yields the first thorium metallacyclopentadiene complex (η(5)-C5Me5)2Th(η(2)-C4Ph4) (). Density functional theory (DFT) studies suggest that the 5f orbitals are involved in the bonding of the metallacyclopentadiene Th-(η(2)-C[double bond, length as m-dash]C-C[double bond, length as m-dash]C) moiety. Compared to the thorium metallacyclopropene, complex 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 (η(5)-C5Me5)2Th[N(N[double bond, length as m-dash]CHSiMe3)(C4Ph4)] () and (η(5)-C5Me5)2Th[N(N[double bond, length as m-dash]C(C12H8))(C4Ph4)] () and the seven-membered bis(triazenido) complex (η(5)-C5Me5)2Th[N(N[double bond, length as m-dash]N(p-tolyl))(C4Ph4)N(N[double bond, length as m-dash]N(p-tolyl))] (), respectively.