104549-22-6Relevant academic research and scientific papers
Crystallographic characterization of the palladium(I) dimers, syn-Pd2Cl2(dppmMe)2 and Pd2Cl2(dppm)2
Besenyei, Gábor,Párkányi, László,Gács-Baitz, Eszter,James, Brian R.
, p. 179 - 187 (2008/10/08)
An X-ray diffraction study on syn-Pd2Cl2(dppmMe)2, syn-1, shows an unusual boat-like conformation of the eight-membered Pd2P4C2 ring. This conformation, containing equatorial Me groups, facilitates access of the Pd-Pd bond to small molecules such as CO, SO2, and elemental sulfur or selenium, and makes the syn isomer more reactive than anti-1. A comparison of bond angles around the Pd and P atoms in the syn- and anti-isomers reveals a more strained geometry of the former, which may also contribute to the stronger propensity of syn-1 to form A-frame adducts. Solution NMR/NOE studies on syn- and anti-1 and their (μ-Se) adducts reveal the structural rigidity of these complexes; the Me groups inhibit the interchange of axial and equatorial positions on the bridging methine C-atom, and solution structures correspond to those in the solid state. The X-ray structure of Pd2Cl2(dppm)2 is, as expected, like that of the corresponding bromo complex; both are analogous to that of anti-1 which adopts a chair conformation within both the fused, five-membered rings.
Synthesis and characterization of dinuclear palladium(I) and mononuclear palladium(II) complexes containing 1,1-bis(diphenylphosphino)ethane (dpmMe) and related mixed-ligand complexes containing dpmMe with either bis(diphenylphosphino)methane (dpm) or 2-(diphenylphosphino)pyridine (Ph2Ppy). X-ray crystal structures of PdCl2(dpmMe) and Pd ...
Lee, Chung-Li,Yang, Ye-Ping,Rettig, Steven J.,James, Brian R.,Nelson, David A.,Lilga, Michael A.
, p. 2220 - 2228 (2008/10/08)
Full title: Synthesis and characterization of dinuclear palladium(I) and mononuclear palladium(II) complexes containing 1,1-bis(diphenylphosphino)ethane (dpmMe) and related mixed-ligand complexes containing dpmMe with either bis(diphenylphosphino)methane (dpm) or 2-(diphenylphosphino)pyridine (Ph2Ppy). X-ray crystal structures of PdCl2(dpmMe) and Pd2Cl2(μ-dpmMe)2. 1,1-Bis(diphenylphosphino) ethane (dpmMe) has been synthesized by treating 1,1-dichloroethane with 2 equiv of LiPPh2. Alkylation of bis(diphenylphosphino)methane (dpm) using n-BuLi and MeI occurs at the methylene carbon and one phosphorus atom to give the phosphonium salt [Ph2PCH(Me)P(Me)Ph2]I, which can be formed also by reaction of CH3I with dpmMe. The complex PdCl2(dpmMe) was prepared from PdCl2(PhCN)2, while Pd2X2(μ-dmMe)2 (X = Cl, Br, I, NCO), Pd2Cl2(μ-dpmMe)(μ-Ph2Ppy), and Pd2Cl2(μ-dpmMe)(μ-dpm) were prepared via ligand substitution of Pd2Cl2(μ-Ph2Ppy)2 with the appropriate bidentate ligand [Ph2Ppy = 2-(diphenylphosphino)pyridine]. The Pd2Cl2(μ-dpmMe)2 complex crystallized as the anti form in the orthorhombic space group Fdd2 with a = 22.249 (1) A?, b = 65.811 (5) A?, c = 12.833 (1) A? and Z = 16; the data were refined to R = 0.039 on the basis of 4470 reflections with I ≥ 3σ(I). A crystal of PdCl2(dpmMe) was triclinic of space group P1 with a = 14.547 (3) A?, b = 19.521 (5) A?, c = 9.788 (3) A? α = 103.60 (1)°, β = 108.34 (1)°, γ = 91.89 (2)°, and Z = 4 (two independent molecules); R = 0.026 from 7123 observed reflections with I ≥ 3σ(I). Of the dinuclear Pd2Cl2 species, only Pd2Cl2(μ-dpmMe)(μ-dpm) reacted with CO in solution to form reversibly the A-frame complex in which the gas has inserted into the metal-metal bond. The solid-state structure of Pd2Cl2(μ-dpmMe)2 shows that rotation of phenyl groups is somewhat inhibited by the presence of the methyl groups, but in solution rotation occurs, as evidenced by NMR data; lack of reactivity toward CO is attributed to a steric problem that would result from the required presence of one methyl group inside a boat ring conformation within a bridged carbonyl product.
