Merriles Dakota M, Morse Michael D
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
J Phys Chem Lett. 2023 Aug 24;14(33):7361-7367. doi: 10.1021/acs.jpclett.3c01712. Epub 2023 Aug 11.
Predissociation thresholds corresponding to dissociation at ground state separated atom limits (SALs) have been recorded in this group for more than 100 - and -block metal-containing molecules. The metal atom electronic degeneracies in these molecules generate a dense manifold of electronic states that allow high-lying vibronic levels to couple to pathways leading to dissociation. However, CrN, CuB, and AuB fail to dissociate at their ground SAL. Instead, the molecules remain bound at energies that far surpass their bond dissociation energies (BDEs), and their bonds break only when excited at or above an excited SAL. Sharp predissociation thresholds at excited SALs nevertheless allowed BDEs to be derived: D(CrN): 3.941(22) eV; D(CuB): 2.26(15) eV; D(AuB): 3.724(3) eV. A previous measurement of D(AlCr) is re-evaluated as dissociating to a higher energy limit, giving a revised value of D(AlCr) = 1.32(2) eV. A discussion of this physical behavior is presented.
在该研究组中，已经记录了对应于基态分离原子极限（SALs）下解离的预解离阈值，涉及100多种含 - 族金属的分子。这些分子中金属原子的电子简并性产生了密集的电子态流形，使得高能振转能级能够与导致解离的途径耦合。然而，CrN、CuB和AuB在其基态SAL处未能解离。相反，这些分子在远超过其键解离能（BDEs）的能量下仍保持束缚状态，并且只有在激发态SAL或更高能量激发时其键才会断裂。尽管如此，激发态SAL处尖锐的预解离阈值使得能够推导出BDEs：D（CrN）：3.941(22) eV；D（CuB）：2.26(15) eV；D（AuB）：3.724(3) eV。先前对D（AlCr）的测量重新评估为解离到更高的能量极限，得到修订值D（AlCr） = 1.32(2) eV。本文对这种物理行为进行了讨论。
