Luminescent Iridium(III) Cyclometalated Complexes with 1,2,3-Triazole “Click” Ligands

A series of cyclometalated iridium­(III) complexes with either 4-(2-pyridyl)-1,2,3-triazole or 1-(2-picolyl)-1,2,3-triazole ancillary ligands to give complexes with either 5- or 6-membered chelate rings were synthesized and characterized by a combination of X-ray crystallography, electron spin ionization–high-resolution mass spectroscopy (ESI-HRMS), and nuclear magnetic resonance (NMR) spectroscopy. The electronic properties of the complexes were probed using absorption and emission spectroscopy, as well as cyclic voltammetry. The relative stability of the complexes formed from each ligand class was measured, and their excited-state properties were compared. The emissive properties are, with the exception of complexes that contain a nitroaromatic substituent, insensitive to functionalization of the ancillary pyridyl-1,2,3-triazole ligand but tuning of the emission maxima was possible by modification of the cyclometalating ligands. It is possible to prepare a wide range of optimally substituted pyridyl-1,2,3-triazoles using copper Cu­(I)-catalyzed azide alkyne cycloaddition, which is a commonly used “click” reaction, and this family of ligands represent an useful alternative to bipyridine ligands for the preparation of luminescent iridium­(III) complexes

Synthesis, Structural Characterization, and Gas-Phase Unimolecular Reactivity of the Silver Hydride Nanocluster [Ag₃((PPh₂)₂CH₂)₃(μ₃‑H)](BF₄)₂

A bis­(diphenylphosphino)­methane-ligated trinuclear silver hydride nanocluster, [Ag₃((Ph₂P)₂CH₂)₃(μ₃-H)]­(BF₄)₂, featuring three silver­(I) ions coordinated to a μ₃-hydride, and its deuteride analogue, [Ag₃((Ph₂P)₂CH₂)₃(μ₃-D)]­(BF₄)₂, have been isolated and structurally characterized using electrospray ionization mass spectrometry (ESI-MS), X-ray crystallography, NMR and IR spectroscopy. The position of the deuteride in [Ag₃((Ph₂P)₂CH₂)₃(μ₃-D)]­(BF₄)₂ was determined by neutron diffraction. ESI-MS of [Ag₃L₃(μ₃-H/D)]­(BF₄)₂ [L = ((Ph₂P)₂CH₂)₂] produces [Ag₃L₃(μ₃-H/D)]²⁺ and [Ag₃L₃(μ₃-H/D)­(BF₄)]⁺. A rich gas-phase ion chemistry of [Ag₃L₃(μ₃-H/D)]²⁺ is observed under conditions of collision-induced dissociation (CID) and electron-capture dissociation (ECD). CID gives rise to the following complementary ion pairs: [Ag₃L₂]⁺ and [L+(H/D)]⁺; [Ag₂(H/D)­L₂]⁺ and [AgL]⁺; [Ag₂(H/D)­L]⁺ and [AgL₂]⁺. ECD gives rise to a number of dissociation channels including loss of the bis­(phosphine) ligand, fragmentation of a coordinated bis­(phosphine) ligand via C–P bond activation, and loss of a hydrogen (deuterium) atom with concomitant formation of [Ag₃L₃]⁺. Under CID conditions, [Ag₃L₃(μ₃-H/D)­(BF₄)]⁺ fragments via ligand loss, the combined loss of a ligand and [H,B,F₄], and cluster fragmentation to give [Ag₂(BF₄)­L₂]⁺ and [Ag₂(L-H)­L]⁺ [where (L-H) = (Ph₂P)₂CH^–]

Gas-Phase Structural and Optical Properties of Homo- and Heterobimetallic Rhombic Dodecahedral Nanoclusters [Ag_{14–<i>n</i>}Cu_<i>n</i>(CC<i>t</i>Bu)₁₂X]⁺ (X = Cl and Br): Ion Mobility, VUV and UV Spectroscopy, and DFT Calculations

The rhombic dodecahedral nanocluster [Ag₁₄(CC<i>t</i>Bu)₁₂Cl]⁺, which has been structurally characterized using X-ray crystallography, was transferred to the gas phase using electrospray ionization, where it was characterized by ion mobility (IM), vacuum ultraviolet (VUV), and ultraviolet (UV) spectroscopies in conjunction with DFT calculations. IM reveals a single peak, and modeling of the collision cross-section with the X-ray structure suggests that the cluster maintains its condensed phase structure upon transfer to the gas phase. The VUV spectra exhibit rich fragmentation, including: photoionization to give [Ag₁₄(CC<i>t</i>Bu)₁₂Cl]^2+• with an onset of 8.84 ± 0.08 eV; cluster fission fragmentation via losses of (AgCC<i>t</i>Bu)_<i>n</i> and (AgCC<i>t</i>Bu)_<i>n</i>−1(AgCl); and via reductive elimination of (<i>t</i>BuCC)₂. Apart from channels associated with photoionization, similar fragment ions are observed in the UVPD spectra, although their relative intensities differ. The TDDFT absorption spectra are symmetry-allowed transitions including A_u → A_g, E_u → A_g, and E_u → E_g irreducible representations. Comparing the collision cross-sections with the X-ray structures for the related clusters [Ag₈Cu₆(CC<i>t</i>Bu)₁₂Cl]⁺, [Ag₁₄(CC<i>t</i>Bu)₁₂Br]⁺, and [Ag₈Cu₆(CC<i>t</i>Bu)₁₂Br]⁺ suggests that they maintain their condensed-phase structures in the gas phase. The VUV spectra of [Ag₈Cu₆(CC<i>t</i>Bu)₁₂Cl]⁺ and [Ag₁₄(CC<i>t</i>Bu)₁₂Br]⁺ exhibit similar fragmentation channels and ionization onsets (8.86 ± 0.03 and 8.86 ± 0.05, respectively) compared with [Ag₁₄(CC<i>t</i>Bu)₁₂Cl]⁺