Triplet excited state distortions in a pyrazolate bridged platinum dimer measured by X-ray transient absorption spectroscopy.
The excited-state structure of a dinuclear platinum(II) complex with tert-butyl substituted pyrazolate bridging units, [Pt(ppy)(μ-(t)Bu(2)pz)](2) (ppy = 2-phenylpyridine; (t)Bu(2)pz = 3,5-di-tert-butylpyrazolate) is studied by X-ray transient absorption (XTA) spectroscopy to reveal the transient electronic and nuclear geometry. DFT calculations predict that the lowest energy triplet excited state, assigned to a metal-metal-to-ligand charge transfer (MMLCT) transition, has a contraction in the Pt-Pt distance. The Pt-Pt bond length and other structural parameters extracted from fitting the experimental XTA difference spectra from full multiple scattering (FMS) and multidimensional interpolation calculations indicates a metal-metal distance decrease by approximately 0.2 Å in the triplet excited state. The advantages and challenges of this approach in resolving dynamic transient structures of nonbonding or weak-bonding dinuclear metal complexes in solution are discussed.
Chemical Sciences and Engineering Division and X-ray Sciences Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
Jenny V
JV
Lockard
Aaron A
AA
Rachford
Grigory
G
Smolentsev
Andrew B
AB
Stickrath
Xianghuai
X
Wang
Xiaoyi
X
Zhang
Klaus
K
Atenkoffer
Guy
G
Jennings
Alexander
A
Soldatov
Arnold L
AL
Rheingold
Felix N
FN
Castellano
Lin X
LX
Chen
D019281:Dimerization; D008958:Models, Molecular; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*; D011789:Quantum Theory; D056928:X-Ray Absorption Spectroscopy
D009944:Organoplatinum Compounds; D011720:Pyrazoles; D010984:Platinum