Almost Clean Formation of Indene in the Allyl + o-Benzyne Reaction

Polycyclic aromatic hydrocarbons (PAHs) have been known to exist in the ISM for nearly four decades, however, no unique identification of a single member of the family had been made. This changed radically with the recent individual detections of a few PAHs in the cold Taurus Molecular Cloud. The polycyclic molecule indene was amongst the detected species, suggesting that a barrierless reaction leading to this molecule must be active. In this contribution we report on a combined experimental and theoretical investigation of the reaction between o-benzyne (c-C<alternatives>6\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{6}\end{document}</alternatives>H<alternatives>4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{4}\end{document}</alternatives>) and the resonance stabilized radical (RSR) species allyl (C<alternatives>3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{3}\end{document}</alternatives>H<alternatives>5\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{5}\end{document}</alternatives>) and show that this reaction is barrierless and that indene (C<alternatives>9\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{9}\end{document}</alternatives>H<alternatives>8\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}_\textbf{8}\end{document}</alternatives>) is the dominant product.