Jian Tian, Lopez Gary V, Wang Lai-Sheng
Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States.
J Phys Chem B. 2016 Mar 3;120(8):1635-40. doi: 10.1021/acs.jpcb.5b08327. Epub 2015 Oct 12.
Boronyl (BO) is a monovalent σ radical with a B≡O triple bond. Its chemistry has remained relatively unknown, though analogy has been established for BO with monovalent atoms, such as H or Au. Here we report a photoelectron spectroscopic study of BiAu(-) and BiBO(-), showing further evidence of the analogy between Au and BO. The photoelectron spectra of BiAu(-) and BiBO(-) are found to be similar, suggesting that they possess similar electronic structure and chemical bonding. The electron affinities of BiAu and BiBO are measured to be 1.38(4) and 1.84(3) eV, respectively. The ground states of both BiAu and BiBO are shown to be a triplet (X (3)Σ(-)). In addition, vibrational structures are resolved in the spectra of BiBO(-). Two vibrational frequencies at 320(30) and 1860(50) cm(-1) are measured for the ground state of BiBO, corresponding to the Bi-B and B-O stretching modes, respectively. The low-lying electronic excited states of BiAu and BiBO are also found to be similar: their first four excited states are A (1)Δ, B (1)Σ(+), C (3)Π, and D (1)Π, with excitation energies at 0.71, 1.29, 2.54, and 2.67 eV for BiAu and 0.63, 1.26, 3.68, and 3.82 eV for BiBO, respectively, above the (3)Σ(-) ground state. Weak photoelectron features related to two-electron detachment transitions are also observed for both anions because of strong electron correlation effects in the ground state of the anions.
硼酰基（BO）是一种具有B≡O三键的一价σ自由基。尽管已建立起BO与一价原子（如H或Au）之间的类比关系，但其化学性质仍相对不为人知。在此，我们报告了对BiAu(-)和BiBO(-)的光电子能谱研究，进一步证明了Au与BO之间的类比关系。发现BiAu(-)和BiBO(-)的光电子能谱相似，表明它们具有相似的电子结构和化学键。测得BiAu和BiBO的电子亲和能分别为1.38(4)和1.84(3) eV。BiAu和BiBO的基态均为三重态（X (3)Σ(-)）。此外，在BiBO(-)的光谱中分辨出了振动结构。测得BiBO基态的两个振动频率分别为320(30)和1860(50) cm(-1)，分别对应于Bi-B和B-O伸缩模式。还发现BiAu和BiBO的低电子激发态相似：它们的前四个激发态分别为A (1)Δ、B (1)Σ(+)、C (3)Π和D (1)Π，对于BiAu，相对于(3)Σ(-)基态的激发能分别为0.71、1.29、2.54和2.67 eV，对于BiBO分别为0.63、1.26、3.68和3.82 eV。由于阴离子基态中强烈的电子关联效应，在两种阴离子的光电子能谱中还观察到了与双电子脱离跃迁相关的微弱光电子特征。
