Golcondane (C20H24): Theoretical studies of a novel strained, caged hydrocarbon molecule*

In 1993 Mehta and Reddy reported the synthesis of a new C$_{20}$ polyhedrane, which they named golcondane (C$_{20}$H$_{24}$, D$_{2d}$) in honor of the 400$^{th}$ anniversary of the founding of the Indian city of Hyderabad, whose original name was Golconda. Golcondane is a caged, nonacyclic hydrocarbon that has two fused four-membered rings, four fused five-membered rings, and two fused seven-membered rings. Its chemical structure was determined by $^{13}$C NMR spectroscopy and unpublished X-ray crystal diffraction studies. Motivated by our previous success in using density-functional theory (DFT) to compute the structural, electronic, and vibrational properties of other hydrocarbons such as cubane, octanitrocubane, the medium-sized diamondoid molecule cyclohexamantane, as well as the novel class of materials known as {\it sila-}diamondoids, we have used DFT and tight- binding molecular dynamics (TBMD) to compute from first- principles similar properties for golcondane. Our work is especially significant with the lack of other theoretical or experimental studies on this interesting molecule in the published literature.