Arthur J. Carty

Highly volatile iridium(I) carbonyl complexes (1–5) with three anionic fluorinated chelates, namely ketoiminate, aminoalkoxide, or iminoalkoxide, have been synthesized and their physical properties relevant to CVD are evaluated. A single‐crystal X‐ray diffraction (XRD) study on Ir(CO)₂(amakNMe₂) (3) confirms a square‐planar geometry with two cis‐orientated carbonyl ligands. Metallic iridium, polycrystalline IrO₂ thin films, or even patterned IrO₂ nanowires are deposited using Ir(CO)₂(hfdaNⁿPr) (5) as the CVD precursor. A systematic investigation of the deposition of IrO₂ nanowires is conducted, showing a close correlation of observed crystallite morphology with applied system pressure, underlying growth surface, and deposition temperature. Of particular importance, tilted and vertically aligned IrO₂ nanowires are obtained on LiTaO₃(012) and LiNbO₃(100) surfaces under a pressure of 30 Torr of oxygen at 425 °C. The morphology and structural composition of the IrO₂ are confirmed by scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, and XRD analyses.

The reactions of Mn₂- and Co₂-containing μ-PNⁱPr₂ complexes with NCN carbenes afford the ‘abnormal’ carbene adducts [Mn₂(CO)₈{μ-P(NⁱPr₂)}(4-cyclo-C₃H₂-1,3-(NR)₂))] and [Co₂(CO)₄(μ-dppm){μ-P(NⁱPr₂)(4-cyclo-C₃H₂-1,3-(NR)₂)}] (R = ^tBu, adamantyl), respectively.

The thermally stable, terminal phosphinidene complexes [Cp^†M(CO)₂(η¹-PNⁱPr₂)]AlCl₄ (Cp^† = Cp, Cp*; M = Fe) and [Cp*M(CO)₃(η¹-PNⁱPr₂)]AlCl₄ (M = Cr, Mo, W) react with Ph₂CNN to form terminal P-coordinated η¹-phosphaazine and η³-diazaphosphaallene ligands, respectively, whereas [CpFe(CO)₂(η¹-PNⁱPr₂)]AlCl₄ reacts with Me₃SiCHN₂ affording a terminal phosphorus bound η¹-phosphaalkene complex.

The bridging phosphinidene complexes [Mn₂(CO)₈(μ-PNⁱPr₂)] and [Co₂(CO)₄(μ-dppm)( μ-PNR₂)] (NR₂ = NⁱPr₂, TMP) react with heterocumulenes RN₃, CH₂N₂ and Ph₂CNN to form complexes with μ-η¹,η²-aminophosphaimine, μ-η¹,η²-aminophosphaalkene and μ-η¹,η²-aminophosphadiphenylmethylazaimine ligands, respectively.

The synthesis and characterization of a series of silver pyrazolate complexes [Ag(tfpz)]₃ (1), [Ag(fbpz)]₃ (2), [Ag(dbpz)]₃ (3), and [(py)Ag(tfpz)]₂ (4) are reported, for which tfpz, fbpz, dbpz are abbreviations for the pyrazolate ligands with formulae 3,5‐(CF₃)₂‐pz, 3‐^tBu‐5‐(CF₃)‐pz, and 3,5‐(^tBu)₂‐pz, respectively. These silver complexes were characterized by microanalysis and spectroscopic methods. The CF₃‐substituted complex 1 possesses the highest volatility and stability against thermal decomposition. Low pressure CVD experiments were conducted over the temperature range 250–350 °C. Silver metal thin films were successfully obtained on silicon wafers using pure H₂ as the carrier gas. Scanning electron microscopy (SEM) was used to reveal surface morphologies, while X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) were utilized to determine the atomic composition of the as‐deposited thin films as well as the crystallite packing.

A new series of Os^II‐based carbonyl complexes cis(CO),trans(N_py,N_py),cis(N_tz,N_tz)‐[Os(CO)₂(bptz)₂] (1), cis(CO),cis(N_py,N_py),trans(N_tz,N_tz)‐[Os(bptz)₂(CO)₂] (2), and cis(CO),trans(N_py,N_py),cis(N_tz,N_tz)‐[Os(CO)₂(fptz)₂] (3), where bptz and fptz denote 3‐tert‐butyl‐5‐(2‐pyridyl)‐ and 3‐trifluoromethyl‐5‐(2‐pyridyl)‐1,2,4‐triazolate, respectively, have been designed and synthesized in an effort to achieve high efficiency, room‐temperature blue phosphorescence. Although 1 and 2 are geometric isomers, remarkably different excited‐state relaxation pathways were observed. Complex 1 exhibits strong phosphorescence in CH₃CN (Φ_p∼0.47) and as a single crystal at room temperature, whereas complex 2 is nearly nonemissive under similar conditions. The associated relaxation dynamics have been comprehensively investigated by spectroscopic and relaxation dynamics as well as by theoretical approaches. Our results lead us to the conclusion that for complex 2, the “loose bolt” effect of metal–ligand bonding interactions plays a crucial role in the fast radiationless deactivation of this type of geometrical isomer. Fine adjustment can also be achieved by functionalizing the ligands so that the electron‐withdrawing nature of the CF₃ group in 3 stabilizes the HOMO of the triazolate moiety, thus moving the emission further into the pure “blue” region; this results in highly efficient phosphorescence and renders 3 particularly attractive for application in blue OLED devices.