Abstract
The [Au(CN)2−]3 trimer in water experiences a strong van der Waals interaction between the d10 gold atoms due to large relativistic effect and can serve as an excellent model system to study the bond formation process in real time. The trimer in the ground state (S0) exists as a bent structure without the covalent bond between the gold atoms, and upon the laser excitation, one electron in the antibonding orbital goes to the bonding orbital, thereby inducing the formation of a covalent bond between gold atoms. This process has been studied by various time-resolved techniques, and most of the interpretation on the structure and dynamics converge except that the structure of the first intermediate (S1) has been debated due to different interpretations between femtosecond optical spectroscopy and femtosecond X-ray solution scattering. Recently, the excitation wavelength of 267 nm employed in our previous scattering experiment was suggested as the culprit for misinterpretation. Here, we revisited this issue by performing femtosecond X-ray solution scattering with 310 nm excitation and compared the results with our previous study employing 267 nm excitation. The data show that a linear S1 structure is formed within 500 fs regardless of excitation wavelength and the structural dynamics observed at both excitation wavelengths are identical to each other within experimental errors.
Highlights
Metal complexes with central metal atoms of gold or silver have attracted much interest due to their unique property called aurophilicity.1–7 The aurophilicity, which is a relativistic effect, causes strong van der Waals interactions between gold atoms with the d10 electron configuration
The data were analyzed by the protocol described in the Experimental section and the results are shown in Secs
Species-associated radial distribution functions (RDFs), r2S(r), of the four transient species determined from the experimental data obtained with 310 nm excitation are shown in Figure 4(b) together with theoretical RDFs calculated from the structures determined in the previous time-resolved X-ray solution scattering (TRXSS) study employing 267 nm excitation
Summary
Signals of trimers corresponds to the bent-to-linear transition of [Au(CN)2À]3 trimer and hinted that the previous TRXSS signal could be contaminated by the contribution of dimer species To resolve this controversy, in this work, we investigate the reaction mechanism of photoinduced Au–Au bond formation of [Au(CN)2À]3 trimer by performing femtosecond TRXSS measurement on the 300 mM solution of Au(CN)2À with 310 nm laser excitation. We can examine whether the reaction mechanism of the Au–Au bond formation changes with excitation wavelength by comparing the reaction mechanisms obtained with excitation at 310 nm and 267 nm Based on this result, we can validate the assumption that the contribution of the dimer excitation to the TRXSS signal of [Au(CN)2À]3 is negligible, which was used for analyzing the TRXSS data measured with 267 nm laser excitation in our previous TRXSS study.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
