Dpm Ligands Research Articles

ChemInform Abstract: Carbonyl Difluoride: Reactions with Metal-Phosphine Complexes.

Abstract Nickel complexes of the composition [Ni(L) n ]X 2 [L = bis(diphenylphosphino)methane (dpm), 1,2-bis(diphenylphosphino)ethane (dpe) and 1,3-bis(diphenylphosphino)propane (dpp), X = Cl − , Br − and I − , n = 1, 2] were allowed to react with carbonyl difluoride under homogeneous and heterogeneous conditions at ambient temperature or above. The dpm ligands of [Ni(dpm)]X 2 and [Ni(dpm) 2 ]X 2 were oxidatively fluorinated to the phosphorane but the complexes of the composition [Ni(dpe)]X 2 and [Ni(dpp)]X 2 did not react with carbonyl difluoride under any conditions tried. The 1:2 complexes [Ni(dpe) 2 ]X 2 and [Ni(dpp) 2 ]X 2 reacted with carbonyl difluoride at 25 °C in CH 2 Cl 2 to form fluorinated phosphoranes and the 1:1 complexes [Ni(dpe)]X 2 and [Ni(dpp)]X 2 , respectively. Carbonyl difluoride was found to react with the neutral complexes [Ni(dpp) 2 ] and [Ni(dpe) 2 ] to give the stoichiometric amounts of oxidatively fluorinated phosphoranes.

Synthesis, Characterization, and Photophysical Properties of Three Platinum(II) Complexes Bearing Fluorescent Analogues of the Di-2-pyridylmethane Ligand

Three new ligands of the general formula [RNHCH(py)(2)] (py = pyridine; R = tosyl, Ts-dpm; R = dansyl, Ds-dpm; R = 7-nitro-1,2,3-benzoxadiazole, NBD-dpm) have been synthesized and characterized. Reactions of these ligands with cis-[Pt(DMSO)(2)Cl(2)] (DMSO = dimethyl sulfoxide) in methanol affords [Pt(Ts-dpm)Cl(2)] (1), [Pt(Ds-dpm)Cl(2)] (2), and [Pt(NBD-dpm)Cl(2)] (3). The crystal structures of these complexes reveal bidentate coordination of the ligands to the Pt center with nonplanar chelate rings. Because of inequivalent substituents on the methine carbon atom of the ligands, distinct exo and endo isomers exist in the three complexes. X-ray analyses indicate that 1 crystallizes in the endo conformation, 2 in the exo conformation, and 3 as a mixture of the two conformers. The (1)H NMR and (195)Pt NMR spectra of the complexes display two sets of independent signals corresponding to the chemically inequivalent exo and endo conformers. The exo conformer was determined by 2D NMR spectroscopy to be thermodynamically favored for all three complexes. Density functional theory (DFT), time-dependent DFT, and atoms in molecules calculations were carried out for both conformers of 3 to investigate differences in their electronic structures and to explore intramolecular interactions. In the presence of dioxygen, 1 thermally decomposes at 60 degrees C to form several unidentified products. Compound 2 is thermally stable even in the presence of dioxygen and water but upon light exposure decomposes to form a new platinum(II) species with a (195)Pt NMR shift of -2177 ppm. Compound 3 reacts both thermally and photochemically in the presence of dioxygen and trace amounts of water to form both 4-amino-7-nitro-2,1,3-benzoxadiazole and [Pt(dpk)Cl(2)] (dpk = di-2-pyridyl ketone). Oxidation of 1 and 3 with H(2)O(2) in acetic acid affords a mixture of compounds, two of which contain dpm ligands bound in a tridentate manner to platinum.

(1,10-Phenanthroline-κ2N,N′)bis(2,2,6,6-tetramethylheptane-3,5-dionato-κ2O,O′)nickel(II)

The title compound, [Ni(C11H19O2)2(C12H8N2)], was obtained from the reaction of bis­(2,2,6,6-tetra­methyl­heptane-3,5-dionato)nickel(II), [Ni(dpm)], and 1,10-phenanthroline (phen). The NiII ion is coordinated by four O atoms from two dpm ligands and two N atoms from a phen ligand in a slightly distorted octa­hedral environment. The methyl C atoms of two of the tert-butyl groups are disordered over two sites, having approximate occupancies of 0.85 and 0.15 for the two components. In the crystal structure, there are no direction-specific inter­actions. Thermal studies showed that the title complex is stable to 623 K.

Structure of the hexanuclear Cu(II) β-diketonate complex

The structure of the hexanuclear copper(II) β-diketonate complex with gfa (hexafluoroacetylacetone) and dpm (dipivalylmethanate) ligands was studied by low-temperature (T = 100 K) X-ray diffraction. Crystal data for Cu6(gfa)4(dpm)4(OH)4 [C64H84Cu6F24O20]: a = 28.2364(7) A, b = 12.8072(3) A, c = 24.7199(7) A, β= 115.900(1)°, V = 8041.5(4) A3, space group C2/m, Z = 4, d calc 1.661 g/cm3. The coordination polyhedra of the copper atoms — squares and octahedra — are formed by the oxygen atoms of the gfa and dpm ligands and groups. In all cases, the Cu-O distances vary from 1.89 A to 2.13 A. The complexes follow the sites of the rhombohedral sublattice with the parameters a c ≈ 14.4 A and a c ≈ 61.5°.

In Situ Infrared Spectroscopic Study on a Titanium Source in MOCVD

The optimum deposition condition in liquid source metalorganic chemical vapor deposition (MOCVD) of films was significantly dependent on the chemical structures of titanium source molecules. To clarify the origin of this dependence, we investigated the reaction mechanisms of the individual titanium sources by in situ infrared absorption spectroscopy. A systematic study on the reaction mechanism of MOCVD source molecules was carried out using a novel titanium source molecule, [methylpentanediolbis(dipivaloylmethanato)titanium]. The obtained data on were discussed by comparing with those on the conventional titanium CVD sources such as [bis (tert-butoxy)bis(dipivaloylmethanato)titanium] and [bis(iso-propoxy)bis(dipivaloylmethanato)titanium]. is about as thermally stable as and more stable than The thermal stability of the organometallic molecules as a whole is determined by the stability of the moieties other than the DPM ligands. The addition of have little influence on the temperature dependence of the infrared absorption of in the gas phase under the actual CVD conditions. The competition between thermal decomposition and oxidation of titanium sources is also sensitive to the structures of their ligand groups other than DPM groups. © 2004 The Electrochemical Society. All rights reserved.

Carbonyl difluoride: reactions with metal-phosphine complexes

Nickel complexes of the composition [Ni(L) n]X 2 [L = bis(diphenylphosphino)methane (dpm), 1,2-bis(diphenylphosphino)ethane (dpe) and 1,3-bis(diphenylphosphino)propane (dpp), X = Cl −, Br − and I −, n = 1, 2] were allowed to react with carbonyl difluoride under homogeneous and heterogeneous conditions at ambient temperature or above. The dpm ligands of [Ni(dpm)]X 2 and [Ni(dpm) 2]X 2 were oxidatively fluorinated to the phosphorane but the complexes of the composition [Ni(dpe)]X 2 and [Ni(dpp)]X 2 did not react with carbonyl difluoride under any conditions tried. The 1:2 complexes [Ni(dpe) 2]X 2 and [Ni(dpp) 2]X 2 reacted with carbonyl difluoride at 25 °C in CH 2Cl 2 to form fluorinated phosphoranes and the 1:1 complexes [Ni(dpe)]X 2 and [Ni(dpp)]X 2, respectively. Carbonyl difluoride was found to react with the neutral complexes [Ni(dpp) 2] and [Ni(dpe) 2] to give the stoichiometric amounts of oxidatively fluorinated phosphoranes.

Binuclear methylene- and alkyne-bridged complexes of rhodium not containing accompanying metalmetal bonds

The alkyne-bridged “A-Frame” complex, [Rh 2Cl 2(μ-CF 3C 2CF 3(DPM) 2] (DPM  Ph 2PCH 2PPh 2), reacts with diazomethane to give the unusual species, [Rh 2Cl 2(μ-CH 2(μ-CF 3C 2CF 3)(DPM) 2] ( 2) in which the two DPM ligands, the methylene and the hexafluoro-2-butyne groups bridge the metals with no accompanying RhRh bond. Attempts to produce a methylene-bridged complex from the analogous carbonyl-bridged “A-frame”, [Rh 2Cl 2(μ-CO)(DPM) 2], were unsuccessful as this species did not react with diazomethane. An X-ray structure determination has been carried out on compound 2. This complex crystallizes in the tetragonal space group P4 1 with a 21.334(3), c 14.574(2) Å, V=6633.2 Å 3 and Z = 4. On the basis of 3669 unique observations and 291 parameters varied the structure has converged to R = 0.034 and R w = 0.039. The RhRh separation of 3.466(1) Å indicates that there is no RhRh bond and the wide RhCRh angle at the bridged methylene group (119.5(5)°) is also consistent with the absence of metalmetal bonding. The methylene group in compound 2 is found to be unreactive towards CO, H 2 and protic acids, probably in part because it is protected in the pocket between the two metals, however compound 2 did react with PMe 3 to yield a complex mix of products, from which [Rh 2Cl(μ-Cl)(μ-CH 2)(μ-CF 3C 2CF 3)(PMe 3) 5] ( 3) crystallized in low yield. This complex crystallizes with two molar equivalents of CH 2Cl 2 in the monoclinic space group P2 1/ n with a 11.519(2), b 14.689(7), c 25.250(5) Å, β 93.00(2)°. V 4266.7 Å 3 and Z = 4. Based on 4614 unique observations and 396 parameters varied the structure has converged to R = 0.063 and R w = 0.095. Compound 3 is unusual in that it has resulted from the replacement of the two bridging bidentate DPM groups in 2 by five monodentate PMe 3 ligands. Both rhodium atoms have octahedral geometries in which they share a common face, bridged by the methylene, the alkyne and one chloro group. The RhRh separation of 3.1338(7) Å is consistent with the absence of metalmetal bonding, which is substantiated by the relatively large RhCH 2Rh angle of 100.1(3)°.

Insertion of acetylenes in the PdPd bond of Pd 2 (Ph 2 PCH 2 PPh 2) 2 Cl 2

Dimethylacetylene dicarboxylate and hexafluoro-2-butyne add to Pd 2(dpm) 2Cl 2 (dpm = Ph 2PCH 2PPh 2) to give crystalline adducts Pd 2(dp) 2(μ-acetylene)Cl 2. An X-ray crystal structure of Pd 2(dpm) 2(μ-C 4F 6)Cl 2 reveals that the acetylene has inserted into the metalmetal bond and has been transformed into a cis-dimetallated olefin. The central CC bond length of the bridging olefin is 1.338(16) Å. The coordination about each of the two similar palladium ions is planar and involves two trans-phosphines (one from each of the bridging dpm ligands), a terminal chloride, and one carbon of the bridging olefin. Both Pd 2(dpm) 2Cl 2 and Pd 2(dpm) 2(μ-C 2{CO 2H 3} 2)Cl 2 catalyze the cyclotrimerization of dimethyl-acetylene dicarboxylate.

Reversible insertion of sulfur dioxide into palladiumpalladium bonds. The preparation and structure of Pd 2(μ-SO 2)(Ph 2PCH 2PPh 2) 2 Cl 2

Addition of sulfur dioxide to Pd 2(dpm) 2X 2, (dpm = (C 6H 5) 2PCH 2P(C 6H 5) 2, X = Cl or Br), Pt 2(dpm) 2Cl 2 or Pd 2[(C 6H 5) 2As(CH 2As(C 6H 5) 2]Cl 2 produces 1/1 adducts. The crystal structure of Pd 2(μ-SO 2)(dpm) 2Cl 2 shows two approximately planar palladium centers with coordination sites occupied by two phosphorus atoms from two bridging dpm ligands, a terminal halide ligand, and a bridging SO 2 ligand. The unit cell contains two crystallographically independent molecules. In most aspects the dimensions of the two molecules are similar. However, the ability of crystal packing forces to alter the PdPd distance (3.383 and 3.221 for the two different molecules) reflects the lack of a direct PdPd bond.

Bidentate group VB chelates. Part VI. Four- and five-coordinate nickel(II) complexes of bisdiphenylphosphinomethane

Bisdiphenylphosphinomethane, dpm, forms diamagnetic square-pyramidal [Ni(dpm) 2X]Y (X = Cl, Br, I, NCS, NO 2; Y = ClO 4, BPh 4) in which the ligand chelates to the metal. The [Ni(dpm) 2(NCS) 2] complex is square-planar and contains mono-dentate dpm ligands, while [ Ni(dpm) 2(CN)]CN is square-planar and contains one bidentate dpm and one monodentate dpm ligand. There is evidence that in solution [Ni (dpm) 2I] + becomes four-coordinate. The recent suggestion that [Ni(dpm)(NCS) 2] 2 is pentacoordinate has led us to re-examine the available spectroscopic evidence and suggest an alternative structure to this complex. The structures of the complexes are discussed in the light of their visible and infrared spectra.