The copper(I), silver(I), and gold(I) metals bind π‐ligands by σ‐bonding and π‐back bonding interactions. These interactions were investigated using bidentate ancillary ligands with electron donating and withdrawing substituents. The π‐ligands span from ethylene to larger terminal and internal alkenes and alkynes. Results of X‐ray crystallography, NMR, and IR spectroscopy and gas phase experiments show that the binding energies increase in the order Ag

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Organic azide complexes of copper­(I) and silver­(I), [(SIPr)­CuN­(1-Ad)­NN]­[SbF6], [(SIPr)­CuN­(2-Ad)­NN]­[SbF6], [(SIPr)­CuN­(Cy)­NN]­[SbF6], and [(SIPr)­AgN­(1-Ad)­NN]­[SbF6] have been synthesized by using Ag­[SbF6] and the corresponding organic azides with (SIPr)­CuBr and (SIPr)­AgCl (SIPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazolin-2-ylidene). The copper and silver organic azide complexes were characterized by various spectroscopic techniques and X-ray crystallography. Group trends of isoleptic Cu­(I), Ag­(I), and Au­(I) organic azide complexes are presented on the basis of experimental data and a detailed computational study. The νasym(N3) values of the metal-bound 1-AdNNN in [(SIPr)­MN­(1-Ad)­NN]+ follow the order Ag < Cu < Au. DFT calculations show that gold­(I) forms the strongest bond with 1-AdNNN in this series, while silver has the weakest interaction. Furthermore, auxiliary ligand free coinage metal N-heterocyclic carbene complexes, [(SIPr)­M]­[SbF6], have been synthesized via metathesis reactions of (SIPr)­MCl (M = Cu, Ag, Au) with Ag­[SbF6]. X-ray crystal structures of dinuclear [(SIPr)­Ag]2[SbF6]2 and [(SIPr)­Au]2[SbF6]2 are also reported. They show close metallophilic contacts. [(SIPr)­Au]2[SbF6]2 reacts with OEt2, SMe2, and CN t Bu to afford [(SIPr)­Au­(OEt2)]­[SbF6], [(SIPr)­Au­(SMe2)]­[SbF6], and [(SIPr)­Au­(CN t Bu)]­[SbF6] adducts, respectively.

Protein post‐translational modifications and protein interactions are the central research areas in mass‐spectrometry‐based proteomics. Protein post‐translational modifications affect protein structures, stabilities, activities, and all cellular processes are achieved by interactions among proteins and protein complexes. With the continuing advancements of mass spectrometry instrumentations of better sensitivity, speed, and performance, selective enrichment of modifications/interactions of interest from complex cellular matrices during the sample preparation has become the overwhelming bottleneck in the proteomics workflow. Therefore, many strategies have been developed to address this issue by targeting specific modifications/interactions based on their physical properties or chemical reactivities, but only a few have been successfully applied for systematic proteome‐wide study. In this review, we summarized the highlights of recent developments in the affinity enrichment methods focusing mainly on low stoichiometric protein lipidations. Besides, to identify potential glyoxal modified arginines, a small part was added for profiling reactive arginine sites using an enrichment reagent. A detailed section was provided for the enrichment of protein interactions by affinity purification and chemical cross‐linking, to shed light on the potentials of different enrichment strategies, along with the unique challenges in investigating individual protein post‐translational modification or protein interaction network.