Phosphorescent Iridium(III) Complexes of Cyclometalated 5‑Aryl‑1<i>H</i>‑1,2,4-Triazole Ligands: Structural, Computational, Spectroscopic, and Device Studies

Ir­(III) complexes of cyclometalated 5-aryl-1<i>H</i>-1,2,4-triazole ligands are highly efficient, phosphorescent emitters. We describe herein a series of <i>fac</i>-IrL₃ complexes, in which the nature of aryl substituents are shown to strongly affect emission wavelength over the range 453–499 nm. Computational and structural studies indicate that for aryl groups the point of attachment and dihedral angle with respect to the cyclometalated ring influence emission color. Significantly, this degree of color tuning may be achieved without resorting to electron-withdrawing or -donating groups. Photo- and electroluminescence device studies of the different emitters indicate that they are generally highly efficient: photoluminescent efficiencies >90% and external quantum efficiencies of up to 22% are observed

Reactions of Sn(Si( Bu)2Me)3 with HM(CO)3C5R5 (M = Cr or Mo, R = H or CH3) and Hg. Ionic, covalent, and μ-CO bonding patterns between transition metals and tin

Hydrogen atom transfer (HAT) reactions to the planar triorganotin radical Sn(Si(tBu)2Me)3 from HMo(CO)3C5H5 and HCr(CO)3C5R5 (R=H, Me) were investigated. Sn(Si(tBu)2Me)3 and HMo(CO)3C5H5 react rapidly to yield HSn(Si(tBu)2Me)3 and [Sn(Si(tBu)2Me)3]+ [Mo(CO)3C5H5]−. Similarly, Sn(Si(tBu)2Me)3 and HCr(CO)3C5H5 react at a slower rate to produce HSn(Si(tBu)2Me)3 and a complex formulated as Cp(CO)2Cr-C=O-Sn(Si(tBu)2Me)3. Reaction of Sn(Si(tBu)2Me)3 and elemental Hg forms the linear trinuclear HgSn2 cluster Hg[Sn(Si(tBu)2Me)3]2.[Display omitted]•New complexes the bulky tin radical Sn(Si(tBu)2Me)3 have been prepared.•Ionic, Covalent, and μ-CO Bonding between Transition Metals and Tin were observed.•The H-Sn(Si(tBu)2Me)3 bond is significantly weaker than typical H-SnR3 compounds.•Structures of Hg[Sn(Si(tBu)2Me)3]2 and BrSn(Si(tBu)2Me)3 are reported.Hydrogen atom transfer (HAT) reactions to the planar triorganotin radical Sn(Si(tBu)2Me)3 from HMo(CO)3C5H5 and HCr(CO)3C5R5 (R=H, Me) have been investigated at room temperature in toluene or pentane solution. Sn(Si(tBu)2Me)3 and HMo(CO)3C5H5 react rapidly to yield the previously unreported tin hydride HSn(Si(tBu)2Me)3 and [Sn(Si(tBu)2Me)3]+[Mo(CO)3C5H5]−. Similarly, Sn(Si(tBu)2Me)3 and HCr(CO)3C5H5 react at a slower rate to produce HSn(Si(tBu)2Me)3 and a complex formulated as Cp(CO)2CrCOSn(Si(tBu)2Me)3 based on its solubility in toluene, infrared spectrum, and computational studies. A product with identical spectroscopic properties to the proposed Cp(CO)2CrCOSn(Si(tBu)2Me)3 is obtained rapidly in the reaction of Sn(Si(tBu)2Me)3 and [Cr(CO)3C5H5]2. Reaction of Sn(Si(tBu)2Me)3 and HCr(CO)3C5Me5 does not occur at a significant rate at room temperature nor does reaction of Cr(CO)3C5Me5 and HSn(Si(tBu)2Me)3. Fast exchange between HCr(CO)3C5H5 and [Cr(CO)3C5H5]2 results in a single broad peak in the cyclopentadienyl area for mixtures of these two complexes in toluene-d8 at room temperature implying that Cr–Cr bond cleavage and also hydrogen atom transfer (HAT) are faster than the NMR time scale. Computational studies accurately reflect experimental observations. The computed Sn–H bond dissociation enthalpy (BDE) of only 66.7kcal/mol in HSn(Si(tBu)2Me)3 places it near the values for M-H BDE in HM(CO)3C5H5 (M=Cr, Mo) leading to a near equilibrium situation with respect to HAT. Reaction of Sn(Si(tBu)2Me)3 and elemental Hg forms the linear trinuclear HgSn2 cluster Hg[Sn(Si(tBu)2Me)3]2. The crystal structures of Hg[Sn(Si(tBu)2Me)3]2 and BrSn(Si(tBu)2Me)3 are reported