198632-61-0Relevant academic research and scientific papers
Heterobimetallic complexes of IrM (M = FeII, CoII, and NiII) core and bridging 2-(diphenylphosphino)pyridine: Electronic structure and electrochemical behavior
Cherepakhin, Valeriy,Hellman, Ashley,Lan, Zhenzhuo,Mallikarjun Sharada, Shaama,Williams, Travis J.
, p. 10509 - 10515 (2020)
Three complexes based on an Ir-M (M = FeII, CoII, and NiII) heterobimetallic core and 2-(diphenylphosphino)pyridine (Ph2PPy) ligand were synthesized via the reaction of trans-[IrCl(CO)(Ph2PPy)2] and the corresponding metal chloride. Their structures were established by single-crystal X-ray diffraction as [Ir(CO)(μ-Cl)(μ-Ph2PPy)2FeCl2]·2CH2Cl2 (2), [IrCl(CO)(μ-Ph2PPy)2CoCl2]·2CH2Cl2 (3), and [Ir(CO)(μ-Cl)(μ-Ph2PPy)2NiCl2]·2CH2Cl2 (4). Time-dependent DFT computations suggest a donor-acceptor interaction between a filled 5dz2 orbital on iridium and an empty orbital on the first-row metal atom, which is supported by UV-vis studies. Magnetic moment measurements show that the first-row metals are in their high-spin electronic configurations. Cyclic voltammetry data show that all the complexes undergo irreversible decomposition upon either reduction or oxidation. Reduction of 4 proceeds through an ECE mechanism. While these complexes are not stable to electrocatalysis conditions, the data presented here refine our understanding of the bonding synergies of the first-row and third-row metals.
IrPd, IrHg, IrCu, and IrTl binuclear complexes bridged by the short-bite ligand 2-(diphenylphosphino)pyridine. Catalytic effect in the hydroformylation of styrene due to the monodentate P-bonded 2-(diphenylphosphino)pyridine ligands of trans-[Ir(CO)(Ph2PPy)2Cl]
Franciò, Giancarlo,Scopelliti, Rosario,Arena, Carmela Grazia,Bruno, Giuseppe,Drommi, Dario,Faraone, Felice
, p. 338 - 347 (2008/10/08)
The complex trans-[Ir(CO)Cl(Ph2PPy)2] (1; Ph2PPy = 2-(diphenylphosphino)pyridine) was obtained in good yield from the reaction of [Ir(p-toluidine)(CO)2Cl] with Ph2PPy. It has a square-planar geometry, as does the analogous Vaska complex, with two monodentate Ph2PPy ligands P-bonded to the iridium(I) center. Compound 1 exhibits a reactivity reminiscent of Vaska's complex; in fact, it adds SO2, halogens, HCl, and CH3I. The addition of HCl to 1 initially occurs at the pyridine nitrogen atoms of the pendant Ph2PPy and subsequently at the iridium(I) center, affording [Ir(CO)H(Cl)2(Ph2PPyH)2][Cl]2 (6). The addition of a benzene solution of[Pd(PhCN)2Cl2] to a solution of 1 in the same solvent yielded, nearly quantitatively, the IrIIPdI complex [IrPd(CO)Cl3(μ-Ph2PPy)2] (8). The reaction of 1 with HgCl2, in benzene, in a 1:1 molar ratio afforded the binuclear complex [Ir(CO)Cl2(μ-Ph2PPy)2HgCl] (9). Using a 1:2 molar ratio the product [Ir(CO)Cl2(HgCl2)(μ-Ph2PPy) 2HgCl]·2CH2Cl2 (10) was obtained. Compounds 8 and 10 were also characterized by a single-crystal X-ray diffraction analysis. The reaction of 1 with [Cu(NCCH3)4]BF4 afforded, almost quantitatively, the ionic compound [Ir(CO)Cl(μ-Ph2PPy)2Cu]BF4 (11) as an orange solid. The compound [Ir(CO)Cl(μ-Ph2PPy)2Tl]-PF6 (12) obtained from the reaction of 1 with TlPF6, shows the Ir-Tl bonding and is luminescent in frozen CH2Cl2 solution at 77 K with a lifetime of 5 ns (±10%). As opposed to analogous compounds, in the bimetallic complexes 8-12 the bridging Ph2PPy ligands assume a head-to-head structure. The aim of the work was to obtain some insight into the beneficial effect of catalytic precursors containing the pendant Ph2PPy ligand in the hydroformylation catalytic cycle. Using complex 1 as a precatalyst in the hydroformylation of styrene, at 80°C and under 80 atm of CO/H2 (1:1) pressure, the rate of the catalytic process increases significantly with respect to that observed with Vaska's complex, making clear a favorable effect of the pendant Ph2PPy ligand. However, the chemoselectivity of the process was low. A scheme of the catalytic cycle is proposed. The new aspects of the catalytic cycle are: (i) the protonation under equilibrium conditions of one of the two pyridine nitrogen atoms of the pendant Ph2PPy ligands in the reductive elimination of HCl from the dihydride-iridium(III) species formed by oxidative addition of H2 to 1 and (ii) protonolysis, by the proton coordinated to the pyridine nitrogen atom, of the acyl or σ-alkyl groups present in the intermediates formed in the reaction pathway. Unexpectedly, 11 and 12 exhibit catalytic activity comparable with that of 1. This occurs because under the experimental conditions used the Cu-N or Tl-N bonds are broken, giving 1.
Homo- and heterobimetallic complexes of rhodium, iridium, palladium, and platinum containing a dimetalated olefin
Mague, Joel T.
, p. 918 - 926 (2008/10/08)
Reaction of [Rh2Cl2(μ-CO)(Ph2Ppy)2] with electrophilic acetylenes gives the dimetalated olefin derivatives [Rh2Cl2(μ-RC=CR′)(Ph2PPy)2] (R = R′ = CO2Me, CF3; R = CO2Me, R′ = H). These add carbon monoxide in terminal sites to form [Rh2Cl2(CO)2(μ-RC=CR′)(Ph 2PPy)2]. Chloride abstraction from [Rh2Cl2(μ-CO)(Ph2Ppy)2] by silver perchlorate yields [Rh2Cl(μ-CO)(Ph2Ppy)2]ClO4 which adds carbon monoxide to give [Rh2(CO)2(μ-Cl)(Ph2Ppy)2]ClO 4. Dimethyl acetylenedicarboxylate (DMAD) also forms the dimetalated olefin complex [Pd2Cl2(μ-DMAD)(Ph2Ppy)2] with [Pd2Cl2(Ph2Ppy)2] while [PtBr2(Ph2Ppy)2] adds to [IrBr2(CO)2)]- to give [PtIrBr3(CO)(Ph2Ppy)2]. Heterobimetallic, dimetalated olefin complexes [IrRhCl2(CO)(μ-CO)(μ-RC=CR)(DPM)2] (R = CO2Me, CF3) are formed from the appropriate acetylene and [IrRh(CO)2(μ-Cl)(DPM)2]Cl. Isomers with the terminal carbonyl bound to iridium and to rhodium are both formed. Loss of one carbonyl ligand occurs at reflux under nitrogen to form the metal-metal bonded complexes [IrRhCl2(CO)(μ-RC=CR)(DPM)2] (R = CO2Me, CF3) Chloride abstraction from [IrRhCl2(CO)(μ-CO)(μ-DMAD)(DPM)2] by silver perchlorate under carbon monoxide yields [IrRh-CO)2Cl(μ-CO)(μ-DMAD)(DPM)2]ClO4 in which the terminal carbonyls are both bound to rhodium. This is readily and reversibly decarbonylated to [IrRhCl(CO)2(μ-DMAD)(DPM)2]ClO4 which contains a metal-metal bond and in which the carbonyl groups are now bound to iridium. The reverse process occurs by initial attack of carbon monoxide at rhodium. The mononuclear complexes [Ir(CO)X(Ph2Ppy)2] (X = Cl, Br) are readily formed, but diiridium complexes bridged by 2-pyridyldiphenylphosphine could be obtained only with difficulty and attempts to form related rhodium-iridium dimers failed. The infrared and 13C and 31P NMR spectra of the new complexes are discussed as are possible mechanisms for the interconversions of [IrRhCl(CO)2(μ-CO)(μ-DMAD)(DPM)2]ClO4 and [IrRhCl(CO)2(μ-DMAD)(DPM)2]ClO4.
