14409-50-8Relevant academic research and scientific papers
Catalytic properties of [Pd(COOMe)nX2-n(PPh 3)2] (n = 0, 1, 2; X = Cl, NO2, ONO 2, OAc and OTs) in the oxidative carbonylation of MeOH
Amadio, Emanuele,Cavinato, Gianni,Dolmella, Alessandro,Toniolo, Luigi
, p. 3721 - 3729 (2010/06/17)
cis-[Pd(ONO2)2(PPh3)2] (1) reacts under mild conditions with CO in methanol (MeOH) in the presence of pyridine (py), yielding trans-[Pd(COOMe)(ONO2)(PPh3) 2] (1a). The use of NEt3 instead of py leads to a mixture of 1a, trans-[Pd(COOMe)2(PPh3)2] (2), and [Pd(CO)(PPh3)3]. Pure 2 was prepared by reacting cis-[Pd(OTs)2(PPh3)2] with CO in MeOH and subsequently adding NEt3. The nitro complex trans-[Pd(COOMe)(NO 2)(PPh3)2] (3a) was prepared by reacting trans-[Pd(COOMe)Cl(PPh3)2] with AgNO2 or with AgOTs and NaNO2. New syntheses for 1 and trans-[Pd(NO 2)2(PPh3)2] (3) are also reported. All complexes have been characterized by IR and 1H and 31P{1H} NMR spectroscopies. Complexes 1 and 2 exchange irreversibly and quantitatively one nitrato with one carbomethoxy ligand, yielding 1a. 2 in CD2Cl2 at 40 °C decomposes with the formation of dimethyl carbonate (DMC), whereas under 4 atm of CO, DMC and dimethyl oxalate (DMO) are formed, ca. 12% each; in the presence of PPh 3 and in the absence of CO, decomposition occurs at 60 °C with the formation of DMC only, suggesting that decarbonylation involves a five-coordinate intermediate or predissociation of a PPh3 ligand. The oxidative carbonylation of MeOH does not occur when using NaNO2 or NaNO3 as the oxidant and 1, 1a, 3, or 3a as the catalyst precursor. On the contrary, when using benzoquinone (BQ) as the oxidant, these complexes, 2, or [Pd(COOMe)2-nXn(PPh3)2] (X = Cl, OAc, OTs; n = 1, 2) promote selective catalysis to DMO. After catalysis the precursors are transformed into [Pd(BQ)(PPh3)2] 2 H2BQ, [Pd(CO)(PPh3)]3 and [Pd(CO)(PPh3)3]. Also the last with BQ gives selective catalysis to DMO. The solid-state structures of 1 CH2Cl2 and 1a have been determined by means of single-crystal X-ray diffraction.
Reaction of NO2 with Palladium(II) and Platinum(II) Aryl Complexes; The Crystal Structure of trans-
Jones, Christopher J.,McCleverty, Jon A.,Rothin, Anne S.,Adams, Harry,Bailey, Neil A.
, p. 2055 - 2062 (2007/10/02)
and do not react with NO but react with NO2 to give and respectively.The structure of has been confirmed by X-ray crystallography, the metal co-ordination polyhedron being planar with trans monodentate nitrato groups.Reaction of (R = C6H4NO2-p or Ph) with NO2 gave , species shown spectroscopycally to contain monodentate nitrate.Treatment of with NO2 gave , while NO or CO caused deoxygenation of (L = PPh3 or PEt3) and to the nitro species and .Reaction of with NO or NO2 afforded .The possible mechanisms of these oxygen-transfer reactions are briefly discussed.
Synthesis of new CO complexes of palladium
Feltham,Elbaze,Ortega,Eck,Dubrawski
, p. 1503 - 1510 (2008/10/08)
The palladium(II) complexes Pd(NO2)2L2 (L = PPh3, PMePh2, PMe2Ph, PEt3) react with CO to form Pd4(CO)5L4. These reaction products have been characterized by IR and 31P, 1H, and 13C NMR spectroscopy. Pd4(CO)5(PPh3)4 crystallized in the monoclinic space group C2/c with Z = 4, a = 24.957 (5) ?, b = 16.138 (3) ?, c = 17.758 (3) ?, and β = 103.47 (2)°. The palladium atoms are at the corners of a distorted tetrahedron in which five of the six edges are bridged by the carbonyl ligands. The unbridged edge has a Pd-Pd distance of 3.209 (1) ?, indicating the absence of a metal-metal bond. The average bonding Pd-Pd distances are 2.753 (1) and 2.758 (13) ?. The average Pd-P distance is 2.318 (2) ?, and the average Pd-C-Pd angle is 82.0°. Pd(NO2)2(PEt2Ph)2 and PdCl(NO2)(PEt2Ph)2 react with CO to form the novel Pd(I) dimer Pd2(CO)Cl2(PEt2Ph)3, which was also structurally characterized by X-ray crystallography. The compound crystallized in the monoclinic space group P21/a with Z = 4, a = 20.041 (3) ?, b = 11.353 (3) ?, c = 19.920 (5) ?, and β = 129.16 (1)°. The molecule is dimeric with a Pd-Pd bond and is the first example of a semibridging carbonyl ligand in palladium complexes. Pd2 has roughly square-planar geometry with two phosphines, one chloride, and Pd1 comprising its coordination sphere. One phosphine, one chloride, Pd2, and the carbonyl ligand comprise the coordination sphere of Pd1. The semibridging carbonyl produces severe distortion in the coordination geometry of both Pd1 and Pd2. Some important distances and angles include Pd1-Pd2 = 2.6521 (3) ?, Pd1-C = 1.874 (3) ?, Pd2-C = 2.110 (3) ?, and Pd1-C-Pd2 = 83.3 (1)°.
