Cationic Complexes of Iridium:  Diiodobenzene Chelation, Electrophilic Behavior with Olefins, and Fluxionality of an Ir(I) Ethylene Complex

Abstract

The synthesis of a series of dicationic Ir(III) complexes is described. Reaction of Ir(CO)(dppe)I (dppe = 1,2-bis(diphenylphosphino)ethane)) with RI (R = CH(3) and CF(3)) results in formation of the Ir(III) precursors IrR(CO)(dppe)(I)(2) (R = CH(3) (1a) and CF(3) (1b)). Subsequent treatment with AgOTf (OTf = triflate) generates the bis(triflate) analogues IrR(CO)(dppe)(OTf)(2) (R = CH(3) (2a) and CF(3) (2b)), which undergo clean metathesis with NaBARF (BARF = B(3,5-(CF(3))(2)C(6)H(3))(4)(-)) in the presence of 1,2-diiodobenzene (DIB) forming the dicationic halocarbon adducts [IrR(CO)(dppe)(DIB)][BARF](2) (R = CH(3) (3a) and CF(3) (3b)). Complexes 3a and 3b demonstrate facile exchange chemistry with acetonitrile and carbon monoxide forming complexes 4 and 5, respectively. NMR investigation of the mechanism reveals that the process proceeds through an eta(1)-diiodobenzene adduct, where labilization at the coordination site trans to the alkyl group occurs first. Complex 3a reacts with ethylene forming the cationic iridium(I) product [Ir(C(2)H(4))(2)(CO)(dppe)][BARF] (6), which demonstrates fluxional behavior. Variable-temperature NMR studies indicate that the five-coordinate complex 6 undergoes three dynamic processes corresponding to ethylene rotation, Berry pseudorotation, and intermolecular ethylene exchange in order of increasing temperature based on NMR line shape analyses used to determine the thermodynamic parameters for the processes. The DIB adducts 3a and 3b were also found to promote olefin isomerization of 1-pentene, and polymerization/oligomerization of styrene, alpha-methylstyrene, norbornene, beta-pinene, and isobutylene via cationic initiation.

Additive Enhanced Crystallization of Solution‐Processed Perovskite for Highly Efficient Planar‐Heterojunction Solar Cells

“…[ 32,33 ] On the other hand, bidentate chelation is also more favorable than monodentate chelation from a thermodynamic perspective as observed in some metal complex systems. [ 34,35 ] The formation of the chelated ring structures of the former allow less confi gurational entropy loss during coordination, resulting in a much smaller Gibbs free energy. Therefore, the temporary chelation of Pb 2+ with DIO will participate in the evolving dynamic equilibrium of the drying and annealing fi lm, co-existing with the coordination of Pb 2+ with methyl ammonium iodide (MAI) during crystal growth until DIO fully evaporates.…”

Copolymerization of Ethylene/Polar Monomer Catalyzed by Phosphinoarenesulfonate (PO) Metal Catalysts and the Catalytic Mechanism

“…图式 1 邻膦基-苯磺酸钯配合物引发的四类独特的聚合反应 Scheme 1 Four unique polymerizations initiated by palladium phosphine-sulfonate complexes [36,37] . 最近, Carrow 等 [38] 发现阳离子二膦基羰基金属配合物也可以发挥与膦基-磺酸盐配合物类似的催化效果, 使乙烯与极性单体共 聚.…”

16 The noble metals

“…83 Using para-hydrogen to enhance the hydride NMR spectra enabled a more thorough study of the stereochemistry of the oxidative addition of 85 In organoiridium chemistry, the striking synthesis of [Ir(CO) 6 ] 3ϩ introduced the first tripositive homoleptic carbonyl cation from the reaction of [IrF 6 ] and CO in the presence of SbF 90 The CF 3 complex and its methyl analogue are easily substituted by ethene and other alkenes, forming such complexes as [Ir(C 2 H 4 ) 2 (CO)(dppe)] ϩ , which shows three different fluxional processes. 91 Among many papers on Ir alkene complexes, the first Ir() ethene complex was reported from the one-electron oxidation of the Ir() complex of tris ( 3 ] exists as syn-and anti-isomers depending on the backbone methyl groups being on the same or opposite sides of the Pd-Pd bond. The greater reactivity of the former, as in the formation of (µ-S) complexes, has been shown by a crystal structure determination, which revealed the exposure of the Pd-Pd bond, and NMR spectroscopy, which showed the retention of configuration in solution.…”