Protonation Reactions of Dinuclear Pyrazolato Iridium(I) Complexes

Abstract

The complex [[Ir(mu-Pz)(CNBu(t))(2)](2)] (1) undergoes double protonation reactions with HCl and with HO(2)CCF(3) to give the neutral dihydride complexes [[Ir(mu-Pz)(H)(X)(CNBu(t))(2)](2)] (X = Cl, eta(1)-O(2)CCF(3)), in which the hydride ligands were located trans to the X groups and in the boat of the complexes, both in the solid state and in solution. The complex [[Ir(mu-Pz)(H)(Cl)(CNBu(t))(2)](2)] evolves in solution to the cationic complex [[Ir(mu-Pz)(H)(CNBu(t))(2)](2)(mu-Cl)]Cl. Removal of the anionic chloride by reaction with methyltriflate allows the isolation of the triflate salt [[Ir(mu-Pz)(H)(CNBu(t))(2)](2)(mu-Cl)]OTf. This complex undergoes a metathesis reaction of hydride by chloride in CDCl(3) under exposure to the direct sunlight to give the complex [[Ir(mu-Pz)(Cl)(CNBu(t))(2)](2)(mu-Cl)]OTf. Protonation of both metal centers in [[Ir(mu-Pz)(CO)(2)](2)] with HCl occurs at low temperature, but eventually the mononuclear compound [IrCl(HPz)(CO)(2)] is isolated. The related complex [[Ir(mu-Pz)(CO)(P[OPh](3))](2)] reacts with HCl and with HO(2)CCF(3) to give the neutral Ir(III)/Ir(III) complexes [[Ir(mu-Pz)(H)(X)(CO)(P[OPh](3))](2)], respectively. Both reactions were found to take place stepwise, allowing the isolation of the intermediate monohydrides. They are of different natures, i.e., the metal-metal-bonded Ir(II)/Ir(II) compound [(P[OPh](3))(CO)(Cl)Ir(mu-Pz)(2)Ir(H)(CO)(P[OPh](3))] and the mixed-valence Ir(I)/Ir(III) complex [(P[OPh](3))(CO)Ir(mu-Pz)(2)Ir(H)(eta(1)-O(2)CCF(3))(CO)(P[OPh](3))].

Luminescent Diiridium Complexes with Bridging Pyrazolates: Characterization and Fabrication of OLEDs Using Vacuum Thermal Deposition

“…The imidazolylidene fragments within the dimer are stacked in a face‐to‐face fashion, with an interplanar separation of ≈3.3 Å which is common for intramolecular arene stacking among luminescent transition‐metal complexes . The nonbonded Ir···Ir separation is calculated to be 3.917 Å, which resembles that observed in the dinuclear Ir(III) cyclometalate complexes held together with bridging pyrazolate . The functional pyridyl pyrazolates were also known to form the dinuclear and polynuclear metal complexes with pyrazolate as the bridge …”

Rhodium and Iridium Complexes with α‐Diketimine Ligands: Oxidative Addition of H2 and O2

“…[41] It should be noted that the cationic complex [{Ir(H)(μ-pz) (CNtBu) 2 } 2 -(μ-Cl)][OTf] (pz = pyrazolate) shows one broad signal in the 13 C NMR spectrum at δ = 108.3 ppm, which was assigned to the isocyanide entity at the Ir III center, the latter was also electron poor. [42] The iridaphosphirane complex [Ir(Cp*){κ 2 -(C,P)-P(Mes*)C=NXy}(CNXy)] (Mes* = 2,4,6-(tBu) 3 C 6 H 2 ) shows a signal in the 13 C NMR spectrum at δ = 141.5 ppm for the isocyanide carbon. [43] In addition, the molecular structure of 4 in the solid state was determined by X-ray crystallography.…”

“…42,159.73 (C=N),156.58,152.52,127.20,126.20,three benzene (10 mL) was treated with H 2 for 5 min. After stirring for 12 h at room temperature under a H 2 atmosphere, the brown reaction mixture was dried in vacuo for a short period of time; yield 72 mg (99 %).…”

Nature of the Excited State of Triangulo Silver N-Heterocyclic Carbenes. Insights from Relativistic DFT Calculations

“…N-Heterocyclic carbenes (NHC) have been of great importance in inorganic and organometallic chemistry over the past few decades, leading to a continuous growth of their chemistry , which includes several complexes involving early and late transition metals, as well as, main group and f-block elements. , NHC constitutes an emerging and efficient alternative to the ubiquitous tertiary phosphines, because of their σ-donor capabilities and ease preparation and functionalization, − affording strong metal–ligand interactions allowing to stabilize multimetallic arrangements. , Specially, the chemistry of silver N-heterocyclic carbenes has been extensively studied, giving rise to the characterization of a plethora of compounds since the first report of a Ag(I)–NHC complex, prompted by its potential uses as catalysts, antimicrobial and chemotherapeutic agents in medicine, , luminescent probes, , and ligand transfer agents. − …”