BORONYL MIMICS GOLD: A PHOTOELECTRON
SPECTROSCOPY STUDY
Tian Jian, Gary V. Lopez, Lai-Sheng Wang
Department of Chemistry, Brown University
International Symposium on Molecular Spectroscopy 70TH MEETING
JUNE 22-26, 2015
CHAMPAIGN-URBANA, ILLINOIS
Outline
 Background and Motivation
 Experimental Principle and Setup
 Results and Summary
 Acknowledgement
Background
I) Boronyl as a monovalent σ ligand: BO/BO− versus CN/CN− and CO
1s22s21p43s2
Zhai, H. J. et al., Acc. Chem. Res. 2014, 47, 2435−2445
II) BO/Au analogy in B13O− and B12Au−
(a)
(b)
Optimized anion global-minimum structures for (a) B12O- (16) and (b) B12Au- (1)
at the B3LYP/B,O/6-311G(d,p)/Au/Stuttgart_rsc_1997_ecp+2f1g level
(d)
AdNDP analyses for the chemical bonding in (a) B12O- (16) and (b) B12Au- (1)
Bai, H. et al., Phys. Chem. Chem. Phys., 2013, 15, 9646
BO/Au analogy in B3(BO)n− and B3Aun− (n = 1, 2)
Optimized anion global-minimum structures of B3(BO)n− and B3Aun− (n = 1, 2) clusters and their neutrals at the
B3LYP/B,O/aug-cc-pVTZ/Au/Stuttgart_rsc_1997_ecp+2f1g level.
Selected molecular orbitals of B3(BO)n− and B3Aun− (n = 1, 2) that are responsible for the delocalized σ and π bonding
in the B3 core, and the B−Au and B−(BO) σ single bonds
Chen, Q. et al., J. Chem. Phys. 2013, 139, 044308
Motivation
• The BO group demonstrates structural and chemical robustness in boronyl
clusters, suggesting its potential as new inorganic ligands and building blocks in
chemistry.
X-ray molecular structure of trans[(Cy3P)2BrPt(BO)] (2) (left) and
p-MOs of the model complex trans[(Me3P)2BrPt(BO)] (2′) (right).
• Although boronyl (BO/BO−) are isovalent to CN/CN− and CO, the chemistry of
boronyl has remained relatively unknown until recently.
Braunschweig, H. et al., Science. 2010, 328, 345
Photoelectron Spectroscopy Principle
BE  hv  KE
M   hv  M (*)  e 
Detachment continuum
-
M+e
M
-
e KE
Electron Binding Energy
M*
VDE
ADE
h
M
-
Configuration coordinate
M–
M
Experimental Setup
Wang, L.S. et al., J. Chem. Phys. 1995, 102, 9480-9493
Photoelectron spectra of BiAu− and BiBO−
1.228 Å
Au
2.672 Å
BiAu─ CV (2Π)
EA= 1.38 ± 0.04 eV
Photoelectron spectra of BiAu− at three different photon
energies: a)532 nm, b)355 nm, c)266 nm, and d)193 nm.
B
O
2.269 Å
BiBO─ CV (2Π)
EA= 1.84 ± 0.03 eV
Photoelectron spectra of BiBO− at three different photon
energies: a)532 nm, b)355 nm, c)266 nm, and d)193 nm.
Complete list of the observed VDEs including
Features
VDE (eV)a
Exptl.
Final State and electronic
configuration
X
A
B
C
D
E
F
G
H
I
J
K
a
b
c
1.43(4)
2.14(4)
2.72(2)
3.97(2)
4.10(2)
4.44(5)
4.65(5)
4.94(6)
5.14(5)
5.48(5)
5.84(5)
6.02(5)
3.42(3)b
3.52(3)b
3.62(3)b
3Σ- …1σ22σ21π2
X
A
B
C
D
a
1.84(3)
2.47(3)
3.10(3)
5.52(5)
5.66(5)
4.38(5)c
BiAu−
1Δ …1σ22σ21π2
1Σ+ …1σ22σ21π2
3Π …1σ22σ11π3
1Π …1σ22σ11π3
Photoelectron spectra of BiAu− at 193 nm
1Σ+ …1σ21π4
1Σ+ …1σ21π4
1Σ+ …1σ21π4
BiBO−
a
3Σ- …1σ22σ21π2
1Δ …1σ22σ21π2
1Σ+ …1σ22σ21π2
3Π …1σ22σ11π3
1Π …1σ22σ11π3
1Σ+ …1σ21π4
Molecular orbital energy diagram for BiAu−
Numbers in the parentheses present experimental uncertainties in the last digit.
These electronic states are due to two electron processes.
b,c
Vibrational structure of BiBO
BiBO─
1855 (50) cm-1
323 (30) cm-1
Description
Experimental (cm-1)
Theoretical (cm-1)*
B-O stretching
1855 (50)
1815
Bi-B stretching
323 (30)
354
*PW91/B,O/aug-cc-pVTZ/Bi/SDD
Summary
• Anions of Gold-Bismuth and Boronyl-Bismuth clusters have been observed in laser
vaporization experiments.
• Well-resolved photoelectron spectra were obtained at various photon energies and the
electron affinities and low-lying electronic excited states of the neutral BiAu and BiBO
clusters were reported.
• BiAu and BiBO show similar PES patterns, due to the fact that Au and BO are both
monovalent σ ligands. BiAu− and BiBO− clusters can be considered to be isostructural and
isovalent.
• We confirm that the boronyl unit does mimic the gold atom when interacting with Bi atom.
Acknowledgement
Prof. Lai-sheng Wang
Dr. Gary V. Lopez, Tengteng Chen
All Wang group members
Brown University
Thank you!
Questions?
http://en.wikipedia.org/wiki/The_Thinker
Molecular orbitals for BiAu− and BiBO− *
* at PW91/B,O/aug-cc-pVTZ/Au, Bi/SDD