77462-40-9Relevant academic research and scientific papers
The Reaction of Di-iodoacetylene with : Formation of and
Davies, Julian A.,Pinkerton, A. Alan,Syed, Rashid,Vilmer, Mark
, p. 47 - 49 (1988)
The complex reacts with di-iodoacetylene to yield and , which have been characterized by spectroscopic methods and by X-ray crystallography; formation of the bridged dichlorovinylidene complex involves a formal 1,2-halide shift accompanied by C-I/Pd-Cl bond methathesis.
Synthesis and spectroscopy of binuclear phosphine bridged palladium hydrides: Pd2HX3[dppm]2 (X = Br, I; dppm = bis[diphenylphosphino]methane)
Kirss, Rein U.,Forsyth, David A.,Plante, Marc A.
, p. 206 - 215 (2007/10/03)
Reactions of orange-red dichloromethane solutions of Pd2 X2dppm2 (X=Br, I; dppm=bis{diphenylphosphino} methane) with aqueous, concentrated HBr or HI at ambient temperature yields dark green solids which analyze for Pd2HX3 dppm2 (1a X=Br and 1b X=I). No reaction is observed between Pd2X2dppm2 and aqueous, concentrated HCl. Line shape analysis of dynamic 31P-NMR spectra for 1a and 1b over a 100 °C range indicates that in each case a system involving two sets of chemically equivalent 31P nuclei, mutually coupled, is exchanging 31P environments via initial exchange with a less populated intermediate system in which all four 31P nuclei are equivalent. From lineshape analysis of the 31P spectra, activation parameters for the rates going to the symmetrical intermediates are as follows: 1a: Δ G ?(-78°)=7.8±0.2 kcal mol-1, Δ H ?=7.5 kcal mol-1, Δ S ?=-1.3 e.u. and for 1b: Δ G ? (-78°)=9.7±0.3 kcal mol-1, Δ H ?=8.9 kcal mol-1, Δ S ?=-3.9 e.u. Similar analysis of dynamic 1H spectra for 1b over a 80 °C range reveals two exchanging Pd-H sites with activation parameters for the exchange: Δ G ?(-78°)=9.5±0.3 kcal mol-1, Δ H ?=8.2 kcal mol-1, Δ S ?=-6.9 e.u. Compounds 1a and 1b decompose to a 1:2 mixture of Pd2X2dppm2 and PdX 2dppm in solution with the evolution of hydrogen. Compound 1b reacts with PPh3 yielding [HPPh3+] [I-] and Pd2I2dppm2 while reaction of 1b with KOH also yields Pd2I2dppm 2. Decomposition of 1b is unchanged in the presence of styrene with no evidence for the formation of iodoethylbenzene or ethylbenzene.
Kinetic and mechanistic aspects of sulfur recovery from Pd2I2(μ-S)(μ-dpm)2 using I2 and structures of Pd(II) complexes with the chelated monosulfide of dpm
Wong, Terrance Y.H.,Rettig, Steven J.,James, Brian R.
, p. 2143 - 2149 (2008/10/08)
The Pd2X2(μ-S)(dpm)2 complexes (2) (X = I, Br) react with halogens to yield PdX2(dpm) (3) and elemental sulfur. Kinetic and mechanistic studies on the X = I system in CHCl3 reveal that the reaction pr
Complexes with a trifluorophosphine ligand bridging a tripalladium triangle. Structure of [Pd3(μ3-PF3)(μ3-I) (μ-bis(diphenylphosphino)methane)3]I
Balch, Alan L.,Davis, Brian J.,Olmstead, Marilyn M.
, p. 3937 - 3942 (2008/10/08)
Synthetic and structural work describe the first examples of bridging monophosphine ligands. Treatment of Pd2(μ-dpm)2X2 (1; dpm is bis(diphenylphosphino)methane; X is Cl or I) with excess trifluorophosphine yields brown [P
Trimethylsilyl halide adducts of dinuclear phosphine-bridged palladium halide complexes: Synthesis, spectroscopy, and reactions of Pd2X2(dppm)2·Me3SiX′ (X, X′ = Cl, Br, I)
Kirss, Rein U.
, p. 3451 - 3458 (2008/10/08)
Reaction of Pd2X2(dppm)2 (1, X = Cl; 2, X = Br; 3, X = I) with Me3SiX′ (X′ = Cl, Br, I) in dichloromethane produced transient dark green solutions for all combinations of X and X′ with the exception of X = X′ = Cl. Net halide exchange was observed for reactions of 1 with Me3SiBr or Me3SiI and for 2 with Me3SiI, apparently without oxidative addition of the silicon-halide bond. Mono- and dinuclear palladium complexes Pd2(μ-CH2)Cl2(dppm)2 (4) and PdCl2(dppm) (5) also exchanged Pd-Cl bonds for Pd-Br bonds in reactions with Me3SiBr. Low-temperature 1H and 31P NMR spectroscopy provided evidence for formation of adducts of formulas Pd2Cl2(dppm)2·Me3-SiCl, Pd2Br2(dppm)2·Me3SiCl, Pd2Br2(dppm)2·Me3SiBr, Pd2I2(dppm)2·Me3SiBr, and Pd2I2(dppm)2·Me3SiI in the reactions of 1-3 with Me3SiX′. Dark green solids of formula Pd2X2(dppm)2·Me3SiX′ (6: (a) X = Cl, X′ = I; (b) X = Br, X′ = I; (c) X = Br, X′ = Br; (d) X = Cl, X′ = Br; (e) X = I, X′ = Br; (f) X = I, X′ = I) could be isolated from the reaction mixtures. The green color is proposed to result from a weakening of the metal-metal bond in 1-3 upon coordination of the trimethylsilyl halide. The presence of oxygen in reactions of 1-3 with Me3SiX′ (X = Cl, Br, I) did not interfere with the formation of the adduct but led to the formation of siloxanes and mononuclear palladium complexes PdXX′(dppm). There was no evidence for Si-Si bond formation in these systems. Halide exchange was also observed in reactions of 1, 2, and 5 with methyl iodide.
Di(phosphine)-bridged complexes of palladium. Parahydrogen-induced polarization in hydrogenation reactions and structure determination of tris(μ-bis(diphenylphosphino)methane)dipalladium, Pd2(dppm)3
Kirss, Rein U.,Eisenberg, Richard
, p. 3372 - 3378 (2008/10/08)
Reduction of Pd2Cl2(dppm)2 (dppm = bis(diphenylphosphino)methane) with excess NaBH4 produces a dark purple solid, I, which shows a reaction chemistry consistent with the stoichiometry Pd2Hx(dppm)2. Reaction of I with excess dppm produces the known compound Pd2(dppm)3. Crystals of Pd2(dppm)3 are monoclinic in space group P21/c with cell dimensions a = 14.733 (5) ?, b = 14.760 (5) ?, c = 29.720 (6) ?, and β = 97.44 (1)°. The structure of Pd2(dppm)3 is similar to that of the structurally characterized Pt2(dppm)3 analogue with approximate C3h symmetry. A total of 1 equiv of H2 and 1 equiv of methane is evolved per 3 Pd(dppm) units when I is treated with aqueous HCl and methyl iodide, respectively. The corresponding metal-containing products are Pd2Cl2(dppm)2 and a mixture of [Pd2I(CH3)(dppm)2]I and PdI2(dppm). The latter compound is also obtained upon oxidation of I with I2. Reaction of I with CH2I2 in dichloromethane yields a mixture of Pd2I2(μ-CH2)(dppm)2 and Pd2Cl2(μ-CH2)(dppm)2, while reaction with either Me3SiCl or Me2SiCl2 produces Pd2Cl2(dppm)2. Complex I is active in the catalytic hydrogenation of alkenes and alkynes. Parahydrogen-induced polarization (PHIP) is observed in the styrene product when solutions of I and phenylacetylene in CDCl3 are stored at -196°C under 3-4 atm of H2 for >8 h prior to reaction at 60-70°C. Similar results are obtained when para-enriched H2 is used without the storage time. Complex I decomposes upon heating in CDCl3 to mixtures of Pd2Cl2(dppm)2, PdCl2(dppm), and an unidentified red palladium compound. While this mixture is also active in hydrogenation and gives rise to PHIP, Pd2Cl2(dppm)2 by itself gives weak polarization under hydrogenation conditions and PdCl2(dppm) gives no polarization.
