Related Experiment Video
Updated: May 23, 2025

Analysis of Complex Molecules and Their Reactions on Surfaces by Means of Cluster-Induced Desorption/Ionization Mass Spectrometry
Published on: March 1, 2020
Observation of Structural Isomers and Isomerization of an Atom-Precise Gold Hydride Nanocluster Using Ion Mobility
Jia Dong1, Patrick Weis2, Vaibhav Wani1
1Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Abstract:
Ion mobility spectrometry (IMS) is a powerful technique to determine structures and isomers of gas phase clusters and complex molecules. It is also a valuable tool to investigate ligand-protected atom-precise nanoclusters that cannot be readily crystallized and examined by X-ray diffraction. Here we use IMS to study a diphosphine-protected gold hydride nanocluster, [Au22H3(dppee)7]3+ (dppee = bis(2-diphenylphosphino)ethyl ether), which was synthesized previously and hypothesized to contain two Au11 units with different bridging ligands. Surprisingly, our IMS data revealed the coexistence of two structural isomers in the as-synthesized product with a population of ∼85% for the main isomer and ∼15% for the minor isomer. The two isomers are found to be interconvertible at high activation voltages. Comparison between the IMS data and theoretical calculations confirm that the main and minor isomers consist of one and three bridging ligands, respectively. The isomers and isomerization process uncovered in this work provide opportunities to study the structure-property relationship of atomically precise metal nanoclusters.
Related Concept Videos
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
High-Resolution Mass Spectrometry (HRMS)
Mass Spectrometry of Amines
Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit...
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Chemical Ionization (CI) Mass Spectrometry
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

