A Cavity-Shaped Gold(I) Fragment Enables CO2 Insertion into Au–OH and Au–NH Bonds

A cavity-shaped linear gold(I) hydroxide complex acts as a platform to access unusual gold monomeric species. Notably, this sterically crowded gold fragment enables the trapping of CO2 via insertion into Au–OH and Au–NH bonds to form unprecedented monomeric gold(I) carbonate and carbamate complexes. In addition, we succeeded in the identification of the first gold(I) terminal hydride bearing a phosphine ligand. The basic nature of the Au(I)-hydroxide moiety is also explored through the reactivity toward other molecules containing acidic protons such as trifluoromethanesulfonic acid and terminal alkynes.


Crystal structure experiemnts
Crystallographic details. Low-temperature diffraction data were collected on a D8 Quest APEX-III single crystal diffractometer with a Photon III detector and a IμS 3.0 microfocus X-ray source at the Instituto de Investigaciones Químicas, Sevilla. Data were collected by means of ω and φ scans using monochromatic radiation λ(Mo Kα1) = 0.71073 Å. The diffraction images collected were processed and scaled using APEX-III software. All structures were solved using SHELXT and refined against F 2 on all data by fullmatrix least squares with SHELXL. 1 All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included in the model at geometrically calculated positions and refined using a riding model.
The isotropic displacement parameters of all hydrogen atoms were fixed to 1.2 times the U value of the atoms to which they are linked (1.5 times for methyl groups). In six of the seven reported structures we used the program SQUEEZE to compensate for the contribution of disordered solvent molecules and counteranions, which account for 1 pentane (3), 2 pentane (4), 4 pentane (7), 8 pentane (8), 2 pentane (11) and 3 dichloromethane (12) in the unit cell. Besides, compounds 3 and 10 contain as well 5 and 3 dichloromethane molecules, respectively, which could be modelled from the Fourier map. These, as well as some disordered tert-butyl groups were, modelled using anisotropic displacement parameter restraints.
Compounds 3 and 7 contain two independent gold molecules per unit cell.
A summary of the fundamental crystal and refinement data are given in Table S1 and Table S2. Atomic coordinates, anisotropic displacement parameters and bond lengths and angles can be found in the cif files, which have been deposited in the Cambridge Crystallographic Data Centre with no. 2246839-2246845.
These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Figure S38. ORTEP diagram of complex 3 showing the hydrogen bonding interactions of the hydrogencarbonate moieties that connect the two independent molecules of gold. Hydrogen atoms, except those involve in the hydrogen bonding, are excluded for clarity. Thermal ellipsoids are set at 50% probability. All carbon atoms are represented in wireframe format for clarity. Hydrogen bonding is highlighted in green. Geometry optimizations were carried out without geometry constraints, using the 6-31G(d,p) 5 basis set to represent the C, H, O and P atoms and the Stuttgart/Dresden Effective Core Potential and its associated basis set (SDD) 6 to describe the Au atoms. Bulk solvent effects (dichloromethane) were included at the optimization stage with the SMD continuum model 7 . The stationary points and their nature as minima or saddle points (TS) were characterized by vibrational analysis, which also produced enthalpy (H), entropy (S) and Gibbs energy (G) data at 298.15 K. The minima connected by a given transition state were determined by perturbing the transition states along the TS coordinate and optimizing to the nearest minimum.