The influence of the FeCp(CO)₂⁺moiety on the dynamics of the metalloid [Ge₉(Si(SiMe₃)₃)₃]⁻cluster in thf: synthesis and characterization by time-resolved absorption spectroscopy

Abstract

Photoexcitation of a newly synthesized, neutral tetrasubstituted Ge9cluster with a covalently bound transition metal substituent led to a complete ground state recovery within 150 ps indicating the strong influence of the Fe moiety.

Photoexcitation of Ge9− Clusters in THF: New Insights into the Ultrafast Relaxation Dynamics and the Influence of the Cation

“…Molecules 2019, 24, x FOR PEER R EVIEW 3 of 22 relaxation pathways. This study also includes results obtained from a new experimental setup [5,41] that now allows long timescale (1 ns) broadband probe in the UV -Vis as well as in the NIR spectral range. This should allow the observation of at least a section of the high-energy tail of the solvated electron spectrum in THF, which still peaks (ca.…”

“…In all investigated compounds, the DAS (A 3 ) are similar to the spectra, which can be attributed to the cluster in its excited state with or without the detached electron. To explain these experimental findings, we take into account another concept known for charge transfer processes after photoexcitation, which was applied to explain excited state dynamics of [Ge 9 (Hyp) 3 FeCp(CO) 2 ] [5]. In this case, no solvated electron or long-lived states occur, but a trap state exists with a lifetime of~150 ps that can be attributed to a charge transfer state.…”

“…The observation/tracking of electrons in photoexcited molecules, nanoclusters or particles is a very interesting research field in chemistry involving intra-and intermolecular electron transfer, conduction mechanisms or magnetic properties of molecules with regard to photochemical reactions and photocatalysis [1][2][3][4][5][6][7][8][9][10]. Transient absorption spectroscopy is a versatile tool to investigate photophysical and chemical mechanisms and processes, for example (bi-)radical lifetimes [11] by transition metal ions like Cu + , Ag + , Au + [26] or Zn 2+ , Cd 2+ , Hg 2+ [27] to build up a neutral dimer in the latter case.…”

“…With single wavelength probing in the near infrared (NIR) region, indications for excess electron formation were found whereas in the UV-Vis regime cluster dynamics were observed [2]. In another publication, we also investigated a neutral complex [Ge 9 (Hyp) 3 FeCp(CO) 2 ] which gave new insights into ultrafast dynamics of this cluster-type [5]. Surprisingly, no long-lived excited states exceeding lifetimes of more than several hundreds of picoseconds were observed, which was attributed to the special role of cationic iron.…”

“…Complementing studies on [(Hyp) 3 Ge 9 ZnGe 9 (Hyp) 3 ] [27,33] (Ge 9 ZnGe 9 ) show a strong influence of dimerization on the long timescale dynamics of the cluster which is crucial for the understanding of possible relaxation pathways. This study also includes results obtained from a new experimental setup [5,41] that now allows long timescale (1 ns) broadband probe in the UV-Vis as well as in the NIR spectral range. This should allow the observation of at least a section of the high-energy tail of the solvated electron spectrum in THF, which still peaks (ca.…”