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1. Coinage metal-ethylene complexes of sterically demanding 1,10-phenanthroline ligands

   https://doi.org/10.1039/d4dt00822g  

   Karade, Deepika V; Phan, Vo_Quang Huy; Dias, H_V Rasika (June 2024, Dalton Transactions)

   Bulky phenanthroline provides ideal support to stabilize ethylene complexes of copper(i), silver(i) and gold(i), permitting their complete characterization. Copper complexes catalyze the carbene insertion to C–H bonds of adamantane. 

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2. Activator-free single-component Co( i )-catalysts for regio- and enantioselective heterodimerization and hydroacylation reactions of 1,3-dienes. New reduction procedures for synthesis of [L]Co( i )-complexes and comparison to in situ generated catalysts

   https://doi.org/10.1039/d2dt01484j  

   Parsutkar, Mahesh M.; Moore, Curtis E.; RajanBabu, T. V. (June 2022, Dalton Transactions)

   Warren Piers (Ed.)

   Although cobalt( i ) bis-phosphine complexes have been implicated in many selective C–C bond-forming reactions, until recently relatively few of these compounds have been fully characterized or have been shown to be intermediates in catalytic reactions. In this paper we present a new practical method for the synthesis and isolation of several cobalt( i )-bis-phosphine complexes and their use in Co( i )-catalyzed reactions. We find that easily prepared ( in situ generated or isolated) bis-phosphine and (2,6- N -aryliminoethyl)pyridine (PDI) cobalt( ii ) halide complexes are readily reduced by 1,4-bis-trimethylsilyl-1,4-dihydropyrazine or commercially available lithium nitride (Li 3 N), leaving behind only innocuous volatile byproducts. Depending on the structures of the bis-phosphines, the cobalt( i ) complex crystallizes as a phosphine-bridged species [(P∼P)(X)Co I [μ-(P∼P)]Co I (X)(P∼P)] or a halide-bridged species [(P∼P)Co I [μ-(X)] 2 Co I (P∼P)]. Because the side-products are innocuous, these methods can be used for the in situ generation of catalytically competent Co( i ) complexes for a variety of low-valent cobalt-catalyzed reactions of even sensitive substrates. These complexes are also useful for the synthesis of rare cationic [(P∼P)Co I -η 4 -diene] + X − or [(P∼P)Co I -η 6 -arene] + X − complexes, which are shown to be excellent single-component catalysts for the following regioselective reactions of dienes: heterodimerizations with ethylene or methyl acrylate, hydroacylation and hydroboration. The reactivity of the single-component catalysts with the in situ generated species are also documented. 

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3. Binding Interactions in Copper, Silver and Gold π‐Complexes

   https://doi.org/10.1002/chem.202103984  

   Mehara, Jaya; Watson, Brandon_T; Noonikara‐Poyil, Anurag; Zacharias, Adway_O; Roithová, Jana; Rasika_Dias, H_V (February 2022, Chemistry – A European Journal)

   Abstract 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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4. Classical Gold Carbonyl Complexes in Tetrahedral and Trigonal‐Planar Settings

   https://doi.org/10.1002/chem.202303339  

   Vanga, Mukundam; Muñoz‐Castro, Alvaro; Dias, H_V_Rasika (December 2023, Chemistry – A European Journal)

   Abstract A unique four‐coordinate, classical gold(I)‐carbonyl complex with substantial backdonation from gold has been isolated by using a B‐methylated and fluorinated tris(pyridyl)borate chelator. Its lighter silver(I) and copper(I) analogs enabled a study of trends in the coinage‐metal family. The B‐arylated ligand version also afforded a gold–carbon monoxide complex that displays a notably low C−O stretch value, but with trigonal planar geometry at the gold. A computational analysis shows that the Au^I−CO bonds of these tris(pyridyl)borate ligand‐supported molecules consist of electrostatic attraction, OC→Au σ‐donation, and very significant Au→CO π‐back‐bonding components. The latter is responsible for the observed C−O stretching frequencies, which are lower than in free CO. 

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5. Atomic data calculations for Au i –Au iii and exploration in the application of collisional-radiative theory to laboratory and neutron star merger plasmas

   https://doi.org/10.1093/mnras/stab3285  

   McCann, Michael; Bromley, S; Loch, S D; Ballance, C P (December 2021, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT Neutron binary star mergers have long been proposed as sufficiently neutron rich environments that could support the synthesis of rapid neutron capture elements (r-process elements) such as gold. However, the literature reveals that beyond neutral and singly ionized systems, there is an incompleteness of atomic data for the remaining ion stages of importance for mergers. In this work, we report on relativistic atomic structure calculations for Au i–Au iii using the grasp0 codes. Comparisons to calculations using the Flexible Atomic Code suggest uncertainties on average of 9.2 per cent, 5.7 per cent, and 3.8 per cent for Au i–Au iii level energies. Agreement around ∼50 per cent is achieved between our computed A-values and those in the literature, where available. Using the grasp0 structure of Au i, we calculated electron-impact excitation rate coefficients and use a collisional-radiative model to explore the excitation dynamics and line ratio diagnostics possible in neutron star merger environments. We find that proper accounting of metastable populations is critical for extracting useful information from ultraviolet–visible line ratio diagnostics of Au i. As a test of our data, we applied our electron-impact data to study a gold hollow cathode spectrum in the literature and diagnosed the plasma conditions as Te = 3.1 ± 1.2 eV and $$n_\textrm {e} = 2.7^{+1.3}_{-0.9}\times 10^{13}$$ cm−3. 

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