We have investigated the photoionization of ammonia borane (AB) and determined adiabatic ionization energy to be 9.26 � 0.03 eV for the X + 2 E ! X 1 A 1 transition. Although the threshold photoelectron spectrum appears at first glance to be similar to the one of the isosteric ethane, the electronic situation differs markedly, due to different orbital energies. In addition, an appearance energy AE 0K -(NH 3 BH 3 , NH 3 BH 2 + ) = 10.00 � 0.03 eV has been determined, corresponding to the loss of a hydrogen atom at the BH 3 -site. From the data, a 0 K bond dissociation energy for the BÀ H bond in the cation of 71.5 � 3 kJ mol À 1 was derived, whereas the one in the neutral compound has been estimated to be 419 � 10 kJ mol À 1 .

We report the mass-selected threshold photoelectron spectrum (ms-TPES) of iminoborane (HBNH), generated by pyrolysis of borazine. The adibatic ionization energy (IE) of the X+ 2Π <-- X 1Σ transition was...

Due to their unusual electronic structure, the biradical m-benzyne, C6H4, and its cation are of considerable interest in chemistry. Here, the photoion mass-selected threshold photoelectron spectrum of the m-benzyne biradical is presented. An adiabatic ionization energy of 8.65 ± 0.015 eV is derived, while a vibrational progression of 0.10 eV is assigned to the ν9 + ring breathing mode, in excellent agreement with computations. The experimental spectrum was reproduced well by Franck–Condon spectral modeling of the 2A1 ← X 1A1 transition, in which the cation retains a monocyclic C6 framework. The energetically close-lying bicyclic 2A2 cation state exhibits low Franck–Condon factors, due to the large change in geometry, and thus cannot be observed.

Trimethylborane (TMB) and its chemistry upon pyrolysis have been investigated by threshold photoelectron spectroscopy. TMB itself shows an unstructured spectrum and its adiabatic ionization energy (IEad) has been determined to...

Jahn–Teller distortion of the ammonia borane cation is presented symbolically by a molecule surfing at the edge of its own potential energy surface. The surfboard symbolises the method (photoelectron spectroscopy) that is used to explore its electronic structure. More information can be found in the Research Article by P. Hemberger, I. Fischer and co‐workers (DOI: 10.1002/chem.202201378).