Spin Accommodation and Reactivity of Aluminum Based Clusters with O2

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• 作者：Arthur C. Reber ; Shiv N. Khanna ; Patrick J. Roach ; William H. Woodward ; A. Welford Castleman ; Jr.
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：December 26, 2007
• 年：2007
• 卷：129
• 期：51
• 页码：16098 - 16101
• 全文大小：230K
• 年卷期：v.129,no.51(December 26, 2007)
• ISSN：1520-5126

文摘

It is shown that spin accommodation plays a determining role in the reactivity of aluminum basedanion clusters with oxygen. Experimental reactivity studies on aluminum and aluminum-hydrogen clustersshow variable reactivity in even electron systems and rapid etching in odd electron systems. The reactivityof even electron clusters is governed by a spin transfer to the singlet cluster through filling of the spindown antibonding orbitals on triplet oxygen. Theoretical investigations show that when the spin transfercannot occur, the species is unreactive. When spin accommodation is possible, more subtle effects appear,such as the required spin excitation energy, which raises the total energy of the system, and the filling ofthe antibonding levels of the O₂ molecule, which is stabilized by becoming an aluminum oxygen bond.This explanation is consistent with observed behavior in oxygen etching reactions with a variety of clustersincluding Al_nH_m^-, Al_n^-, Al_nI_m^-, and Al_nC^-. The proposed reaction mechanism lends a physical interpretationas to why the HOMO-LUMO gap successfully predicts oxygen etching behavior of the considered systems.