1. Symmetry of PolyoxometalateBased Late-Transition-MetalOxo Complexes And The “Oxo
Wall”
Mixtli Campos-Pineda
Group Theory. December 4th, 2013

2. Outline

Introduction
◦ The Oxo Wall
◦ The Vanadyl Ion (C4v)

Late transition metal M=O symmetries
◦ AuO (C2v)
◦ Pt-oxo and Pd-oxo (C4v)

Revisiting the late transition metal M=O
complexes.
◦ The square planar Pd unit (D4h)

Conclusions

3. Introduction

Terminally bound oxo species are
proposed as intermediates of
important catalyzed reactions.

The Oxo Wall:
◦ “M=O groups are stabilized at metal
centers with an oxidation state of no less
than 4+ and no more than four d
electrons”

4. Groups 3-6 are stable
 Groups 7-8 are more reactive
 Groups 9-11 are rare (electrons begin
to populate antibonding orbitals)


5. The Vanadyl Ion
 C4v symmetry of VO(H2O)5


6. s-orbitals transform as A1
 p-orbitals transform as A1+E
 d-orbitals transform as A1+B1+B2+E


a.s.=5
1 1 3 1 = 2A1+B1+E

8. 
B2 is a non bonding orbital

9. 
Transitions (B2 initial state)
◦ B2 (A1+E)=B2 + E
◦ Only 2B2E is symmetry allowed
◦ 2B22B1 and 2B2 2A1 are vibronically
allowed

10. Late transition metal M=O
symmetries

AuO

11. 
C2v symmetry of AuO
s-orbital transforms as A1
 p-orbitals transform as A1+B1+B2
 d-orbitals transform as A1+A2+B1+B2


13. 
Transitions (A2 initial)
◦ A2 (A1+B1+B2)= A2+B1+B2
◦ A2A1 transition is a vibronic one

14. 
Pt-oxo and Pd-oxo

15. s-orbitals transform as A1
 p-orbitals transform as A1+E
 d-orbitals transform as A1+B1+B2+E


a.s.=5
1 1 3 1 = 2A1+B1+E

17. 
Transitions (E initial state)
◦ E (A1+E)=E + A1+A2+B1+B2
◦ All allowed transitions

Transitions (B2 initial state)
◦ B2 (A1+E)=E +B2
◦ Only pure electronic transitions to states
with E or B2 symmetry are allowed.

18. 
Electronic transitions:

19. Revisiting the late transition
metal M=O complexes.

The square planar Pd unit (D4h)

20. 
D4h symmetry of Pd unit

21. s-orbital transforms as A1g
 p-orbitals transform as Eu+A2u
 d-orbitals transform as
Eg+B1g+B2g+A1g
 a.s.=4 0 0 2 0 0 0 4 2 0= A1g+B1g+Eu


Transitions (tentatively)
◦ EB1 becomes EgB1g
◦ EA1becomes EgA1g
◦ B2B1 becomes B2gB1g

22. Conclusions
Group Theory can help us assign and
describe the symmetry of MOs.
 We can assess the symmetry of
transitions even if we don’t know their
energy.
 Group Theory can’t help us in
structure determinations, since it
requires us to postulate a structure
with a point group


23. References
C J Ballhausen et al, Inorg. Chem.
1962, 1(1), 111.
 K P Halloran et al, Inorg. Chem.,
2012, 51 (13), 7025–7031.
 T M Anderson et al, Science, 2012,
306, 2074 .
 T M Anderson et al, J. Am. Chem.
Soc., 2005, 127, 11948.
 R Cao et al, J. Am. Chem. Soc., 2007,
129, 11118.
