64345-32-0Relevant academic research and scientific papers
Synthesis and Reactions of Dinuclear Palladium Complexes Containing Methyls and Hydride on Adjacent Palladium Centers: Reductive Elimination and Carbonylation Reactions
Young, S. J.,Kellenberger, B.,Reibenspies, Joseph H.,Himmel, S. E.,Manning, M.,et al.
, p. 5744 - 5753 (2007/10/02)
The transmetalation reaction of trimethylaluminum with the palladium chloride dimer Pd2Cl2(μ-dppm)2 (1) (dppm = bis(diphenylphosphino)methane) at -78 deg C gave an intermediate, Pd2ClMe(μ-dppm)2 (2), which disproportionated at ca. 10 deg C to yield the trans-face-to-face palladium dimer Pd2Cl2Me2(μ-dppm)2 (3) and a palladium dimer Pd2Cl2(μ-CH2)(μ-dppm)2 (5).The use of excess trimethylaluminum at -40 deg C gave the dimethyl complex, Pd2Me2(μ-dppm)2 (7).When 2 and 7 were protonated, a stable A-frame chloro-bridged dimer + (6) and a hydride-bidged dimer + (8) were obtained.Warming 6 in solution to ambient temperature caused the reductive elimination of methane; 8 lost methane and ethane at ambient temperatures.Both reductive eliminations were strictly intramolecular as determined by crossover experiments.The reaction of 6 with CO (1 atm) at -20 deg C first gave a carbonyl-bridged complex + (10) that rearranged to the acyl complex + (11) and then on warming eliminated acetaldehyde.The carbonylation of 8 (1 atm) proceeded stepwise to give first the mono- and then the diacyl complexes.The diacyl complex + (13) underwent the reductive elimination of acetaldehyde at ambient temperatures.
Synthesis and reactivity of Pd2Mn, MPdFe, MPdMn2, and MPdFe2 clusters (M = Pd, Pt) stabilized by Ph2PCH2PPh2 (dppm) ligands. Crystal structure of [Pd2Mn2(μ3-CO)(μ-CO)(CO) 7(μ-dppm)2]
Braunstein, Pierre,De Bellefon, Claude De Méric,Ries, Michel,Fischer, Jean
, p. 332 - 343 (2008/10/08)
Heterotetranuclear dppm-stabilized metalloligated clusters have been prepared by reaction of [Fe(CO)3NO]- or [Mn(CO)5]- with the dinuclear d9-d9 complexes [PdMCl2(μ-dppm)2] (M = Pd, Pt). These clusters, of formula [PdMFe2(CO)5(NO)2(μ-dppm)2] (M = Pd, 1a; M = Pt, 1b) and [PdMMn2(CO)9(μ-dppm)2] (M = Pd, 4a; M = Pt, 4b), are characterized by an almost planar metal core, whose Pd-M, M-Fe, and M-Mn edges are bridged by a dppm ligand. The metalloligand Fe(CO)3NO or Mn(CO)5 is always connected to the triangular core PdMFe or PdMMn, respectively, via a Pd atom. This was established by an X-ray diffraction study on 4a: monoclinic, space group P21/c, with Z = 4, a = 17.561 (7) A?, b = 21.319 (8) A?, c = 19.461 (8) A?, β = 113.50 (2)°, and d(calcd) = 1.44 g/cm3. The structure was solved by using 4473 reflections with I > 3σ(I) and refined to conventional R = 0.059 and Rw = 0.082. The Pd(2)-Mn(1) distance (2.580 (2) A?) is shorter than the Pd(1)-Mn(1) distance (2.698 (2) A?) and the exocyclic, unsupported Pd(1)-Mn(2) distance (2.821 (2) A?). The Pd(1)-Pd(2) distance is 2.681 (1) A?. Whereas the coordination about Mn(2) is octahedral, that about Mn(1) can be viewed as highly distorted octahedral. These clusters result from the formal insertion of a Fe(CO)2NO or Mn(CO)4 fragment into the Pd-P bond of the dinuclear precursor. This accounts for the complete regioselective formation of the platinum-containing clusters in which the less labile Pt-P bonds have been retained. The chemistry reported here for the dinuclear MPdP4 and for the MPdFe2P4 or MPdMn2P4 systems takes place within their plane, in contrast to the chemistry leading to A-frame structures. Furthermore, the exocyclic Pd-Fe or Pd-Mn bond of 1 or 4, respectively, is very labile and may be broken sometimes reversibly in dissociating solvents or by other nucleophiles, e.g., halides. Whereas clusters 1 do not react with CO, [PdMFeI(CO)2(NO)(μ-dppm)2] affords cationic clusters in the presence of Tl[PF6], which are characterized by a Pd-bound terminal CO. An effect of platinum that renders its neighboring palladium center more electron-rich is noted and influences the reactivity of the clusters. The Mn-containing clusters are generally more labile than their Fe analogues, and 4b slowly rearranges in solution with formation of the binuclear cation [(OC)4Mn(μ-dppm)Pt(dppm)]+. All complexes were characterized by elemental analyses and IR, 1H NMR, and 31P{1H} NMR spectroscopies. The latter is particularly informative because of the inequivalence of the four phosphorus atoms, and comparisons are made between related systems.
Tri- and tetranuclear palladium-cobalt clusters containing bridging Ph2PCH2PPh2 (dppm) ligands. Crystal structures of [Pd2Co2(μ3-CO)2(CO) 5(μ-dppm)2] and [Pd2Co(μ3-CO)2(CO) 2(μ-dppm)2][PF6]
Braunstein, Pierre,De Méric De Bellefon, Claude,Ries, Michel,Fischer, Jean,Bouaoud, Salah-Eddine,Grandjean, Daniel
, p. 1327 - 1337 (2008/10/08)
The heterotetranuclear cluster [Pd2Co2(CO)7(dppm)2] (1) was synthesized in high yield by the reaction of [Co(CO)4]- with [Pd2Cl2(dppm)2] (dppm = μ-Ph2PCH2PPh2), whereas the A-frame complexes [Pd2Cl2(μ-Y)(dppm)2] (Y = CO, CH2) are much less reactive. The molecular structure of 1·2.5THF has been determined by X-ray diffraction. Crystal data: triclinic, space group P1 with Z = 2, a = 18.417 (8) A?, b = 14.798 (6) A?, c = 13.855 (6) A?, α = 113.61 (2)°, β = 107.50 (2)°, γ = 82.20 (2)°, V = 3299 A?3, R = 0.055, Rw = 0.076. This cluster contains a metalloligated triangular core of which two edges are bridged by the dppm ligands in such a way that the four P atoms and the four metal atoms are almost coplanar. The lability of the P→Pd bond of the precursor complex accounts for the easy formal insertion of the Co(CO)3 fragment into this bond. A metal-exchange reaction can be thermally induced that transforms 1 into the triangular cluster [PdCo2(CO)5(dppm)2]. The reaction of 1 with anionic nucleophiles X- was found to regioselectively break the exocyclic Pd-Co bond, and it afforded the clusters [Pd2CoX-(CO)3(dppm)2] (X = Cl, Br, I, OH, SCN). The reversibility of this reaction was investigated, and the reaction leading to the halogeno clusters was best carried out in acetone, proceeding faster depending upon the nature of X- (I- ≈ Br- ? Cl-) and of the corresponding cation (PPN+ ? K+, Na+). Re-formation of the exocyclic Pd-Co bond was observed in Et2O. The cationic cluster [Pd2Co(CO)4(dppm)2]+ was prepared by carbonylation of the halide-substituted Pd2Co clusters in the presence of a halide abstractor. Its unique Pd-bound terminal CO ligand is very labile and can be reversibly and selectively replaced by a solvent molecule (acetone, THF, MeCN) depending upon CO partial pressure. The molecular structure of [Pd2Co(CO)4(dppm)2]-[PF 6]·C3H6O (7·acetone) has been determined by X-ray diffraction. Crystal data: monoclinic, space group Cc with Z = 4, a = 22.87 (2) A?, b = 14.198 (4) A?, c = 22.27 (2) A?, β = 122.35 (5)°, V = 6109 A?3, R = 0.053, Rw = 0.069. The structure of the cation may be considered as derived from that of 1 by the replacement of the terminally bound Co(CO)4 unit by a carbonyl group. Spectroscopic IR and 1H and 31P{1H} NMR data are discussed in relation with the structure and reactivity of these new clusters. The synthesis and chemistry of 1 are characterized by reactions formally taking place within the Pd2P4 plane. The bonding description of the clusters with a Pd2Co(dppm)2 core emphasizes their belonging to a new class of clusters where an anionic 18-electron metal carbonyl fragment is part of a closo structure.
Organo Halide Addition to Pd2(Ph2PCH2PPh2)3. Preparation of Novel Methylene- and Phenylene-Bridged Complexes by Two-Center, Three-Fragment Oxidative Addition
Balch, Alan L.,Hunt, Catherine T.,Lee, Chung-Li,Olmstead, Marilyn M.,Farr, Lames P.
, p. 3764 - 3772 (2007/10/02)
Dihalomethanes react with Pd2(dpm)3 (dpm = bis(diphenylphosphino)methane) to form Pd2(dpm)2(μ-CHR)X2 (X = I, Br, Cl; R = H, CH3).Pd2(dpm)2(μ-CH2)I2 undergoes substitution to form Pd2(dpm)2(μ-CH2)L22+ (L = pyridine, methyl isocyanide).The Pd - C (methylene) bond resists insertion of carbon monoxide, isocyanides, or sulfur dioxide.Reaction of Pd2(dpm)3 with 1,2-diiodobenzene yields Pd2(dpm)2(μ-C6H4)I2.Addition of phenyl isocyanide dichloride to Pd2(dpm)3 yeilds Pd2(dpm)2(μ-CNPh)Cl2 while a corresponding reaction involving oxalyl chloride produces Pd2(dpm)2(μ-CO)Cl2.Addition of methyl halide to Pd2(dpm)3 produces Pd2(dpm)2(CH3)2X2 (X = Br, I) which exist as the molecular A-frame +X- in solution.Protonation of Pd2(dpm)2(μ-CH2)I2 with fluoroboric acid yields brown, crystalline BF4 in which a bridging methylene has been converted into a terminal methyl group.Dynamic aspects of the structure of + and + are described.
