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AuCl crystallizes in the tetragonal I4_1/amd space group. The structure is one-dimensional and consists of four AuCl ribbons oriented in the (1, 0, 0) direction. Au1+ is bonded in a linear geometry to two equivalent Cl1- atoms. Both Au–Cl bond lengths are 2.33 Å. Cl1- is bonded in a water-like geometry to two equivalent Au1+ atoms.
AuCl crystallizes in the tetragonal P4_2/ncm space group. The structure is one-dimensional and consists of two AuCl ribbons oriented in the (1, 1, 0) direction. Au1+ is bonded in a linear geometry to two equivalent Cl1- atoms. Both Au–Cl bond lengths are 2.35 Å. Cl1- is bonded in an L-shaped geometry to two equivalent Au1+ atoms.
AuCl is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Au1+ is bonded to four equivalent Cl1- atoms to form corner-sharing AuCl4 tetrahedra. All Au–Cl bond lengths are 2.61 Å. Cl1- is bonded to four equivalent Au1+ atoms to form corner-sharing ClAu4 tetrahedra.
AuCl(PF3) crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four AuCl(PF3) clusters. Au1- is bonded in a linear geometry to one P5+ and one Cl1- atom. The Au–P bond length is 2.21 Å. The Au–Cl bond length is 2.30 Å. P5+ is bonded in a 4-coordinate geometry to one Au1- and three F1- atoms. There is one shorter (1.56 Å) and two longer (1.57 Å) P–F bond length. Cl1- is bonded in a distorted single-bond geometry to one Au1- atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one P5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one P5+ atom.
AuClO2 crystallizes in the monoclinic P2_1/m space group. The structure is one-dimensional and consists of two hydrogen peroxide molecules and two AuCl ribbons oriented in the (0, 1, 0) direction. In each AuCl ribbon, Au5+ is bonded in an L-shaped geometry to two equivalent Cl1- atoms. Both Au–Cl bond lengths are 2.42 Å. Cl1- is bonded in an L-shaped geometry to two equivalent Au5+ atoms.
Magnetic circular dichroism of transition metal complexes and open-shell systems are challenging to simulate and analyze, mainly due to the interplay of spin–orbit couplings and finite-magnetic-field induced Zeeman effects with the complex selection rules dictated by the circularly polarized light. In this study, we introduce an ab initio relativistic two-component formalism based on the restricted magnetic-balanced Hamiltonian for simulating MCD spectra. Both homogeneous finite magnetic field and relativistic effects are included variationally in the ground state reference. Finite-field London orbitals are used to enforce the constrained gauge-origin independence in the calculation using localized atomic orbitals. Through benchmark studies of AuCl 4 – , Pt(CN) 4 2– , and Mo(CN) 8 3– , we discuss how relativistic effects are manifested in MCD for both closed-shell and open-shell molecular complexes and how the interplay between spin–orbit coupling and magnetic field modulates the MCD selection rules. Finally, an investigation on temperature-dependent MCD is carried out and compared to experiment.
Bipolar membranes (BPMs) which consist of a cation exchange layer (CEL) and anion exchange layer (AEL) are quite effective as membranes in gas phase electrolyzers. However, such membranes can also serve as a host to embed photocatalysts and electrocatalysts. By selectively exchanging cations with Cd 2+ and anions with AuCl 4 – , we were able to synthesize CdS and Au nanoparticles in CEL and AEL layers, respectively, through sequential chemical and photocatalytic reactions. Reacting Cd 2+ with thioacetamide formed the CdS nanoparticles in CEL. The photogenerated electrons from CdS were then used to reduce AuCl4– in an H-cell configuration to produce Au nanoparticles in AEL and thus prepare a photocatalytically active BPM film (referred to as a CdS/BPM/Au film). Such a concerted design of BPM allows “vectorial” electron transfer between two layers of BPM leading to its transfer to an acceptor molecule (methyl viologen) in solution. Designing photocatalytically active BPM and understanding the vectorial electron flow between two separate ion-selective layers offer new opportunities in water splitting and CO 2 reduction.
The Cs 4 Au II Au III 2 Cl 12 perovskite (1), featuring AuCl 4 trimers separated by vacancies, enables the first high-pressure study of Au 2+/3+ mixed-valence. Our computational analysis of the gold frontier orbitals suggests that the Au 2+ →Au 3+ intervalence charge transfer (IVCT) occurs across the vacancies. Computational structures indicate that these vacancies rapidly shrink with pressure and the Au 2+ and Au 3+ coordination spheres become very similar at the phase transition to nearly cubic symmetry at ca. 15 GPa─enabling facile IVCT. Although the activation energy of conductivity of 0.73(4) meV and far-infrared absorption indicate a small but nonzero bandgap, ambient thermal energy drives the IVCT, affording metallic properties: prominent infrared reflectivity and transport values of 10 2 S·cm –1 . This prompted us to perform the first high-pressure studies of magnetoresistance (MR) and Hall effect in halide perovskites. At 16 GPa, the MR increases by 9.3% at 2 K and 9 T; this value is maintained up to 27 GPa, when a local distortion drives electronic localization. By globally fitting the MR and Hall resistance to a two-carrier model we quantify how the carrier densities and mobilities evolve with pressure. Thus, metal-like transport and MR in 1 is driven by a pressure-induced transition from localized to partially delocalized mixed-valence.