38425-01-3Relevant academic research and scientific papers
Synthesis and reactivity of mixed-metal Pd2Mo, PdPtMo and Pd2W clusters containing Ph2PCH2PPh3(dppm) ligands. Molecular structure of 3-CO)2-(μ-dppm)2>
Braunstein, Pierre,Ries, Michel,Bellefon, Claude de Meric de,Dusausoy, Yves,Mangeot, Jean-Paul
, p. 533 - 550 (1988)
The quantitative synthesis of the heterotrinuclear chlorocarbonyl clusters (Cp=η-C5H5, dppm=Ph2PCH2PPh2, M1=Pd, M=Mo, 1; M1=Pd, M=W, 2; M1=Pt, M=Mo, 3) was achieved by the reaction of - (M=Mo, W) with the dinuclear d9-d9 complexes (M1=Pd, Pt) in THF.These clusters are characterized by a triangular metal core, whose Pd-M1 and M1-M edges are bridged by a dppm ligand.The two carbonyl ligands attached to M interact in a triply semi-bridging fashion with the three metals, on either side of the trimetallic plane.The chloride atom is always bonded to the trimetallic core PdM1M via the Pd atom.This was established by an X-ray diffraction study on 1: triclinic, space group P1(C1i), with Z=2, a 13.664(2), b 13.946(5), c 18.223(6) Angstroem, α 110.30(3), β 93.89(2), χ 102.22(2) deg, V 3144.3(1) Angstroem3.The number of data used was 5675 (with I>5 ?(I)),giving values of R=0.046 and Rw=0.046 after refinement.In the presence of Tl, clusters 1 and 2 react with CO to give the cationic clusters + (M=Mo, +; M=W, +) which possess a CO ligand terminally bound to Pd, or with THF to give the solvento clusters + (M=Mo, +; M=W, +).The heterotetranuclear metalloligated clusters (M1=Pd, M=Mo, 9; M1=Pd, M=W, 10; M1=Pt, M=Mo, 11) have been prepared from 1-3, respectively.Their relevance to the mechanism of formation of clusters 1-3 is discussed, particularly in view of the lability of their exocyclic, equatorial Pd-M bond.
Acid-catalysed Additions of Acetylenes to (X=Cl, Br, or I) to give Dimetallated Olefin Complexes of Type (R=H, Ph, or C6H4Me-p)
Higgins, Simon J.,Shaw, Bernard L.
, p. 457 - 460 (1988)
The addition of acetylenes to (dppm=Ph2PCH2PPh2; X=Cl, Br, or I) is catalysed by traces of acid and (in some cases) methanol, giving (R=H, Ph, or C6H4Me-p) containig the dipalladated olefin ligand HC=CR.These r
Photoinduced oxidative degradation of unsaturated M3(dppm)3CO2+ clusters (M = Pd, Pt) by chlorocarbons and chloride ion
Harvey, Pierre D.,Provencher, Rejean,Gagnon, Jonathan,Zhang, Tianle,Fortin, Daniel,Hierso, Karine,Drouin, Marc,Socol, Steve M.
, p. 2268 - 2278 (1996)
Both M3(dppm)3CO2+ clusters (M = Pd, Pt) photoreact with chlorocarbons (Cl-R; R = CCl3, CHCl2, CH2Cl, C6H5, C10H15 (adamantyl)) and chloride ion (slowly) to produce the oxidized mononuclear species M(dppm)Cl2 as a sole isolated M-coordinated inorganic product. Such reactions do not proceed in the dark, except for R = CH2C6H5. Among the organic products, the coupling compound R-R (R = C6H5) is observed along with many phosphine compounds such as P(C6H5)3. In an attempt to elucidate the photoinduced mechanism at the early stage of the phototransformations, the following have been investigated : the ground state binding constants (K11 for M = Pd in methanol), the photochemical quantum yields of cluster disappearance (Φdis for M = Pd) as a function of substrates, substrate concentrations, excitation wavelengths, solvents (ethanol vs toluene), and presence of CO, and the emission lifetimes (τe for M = Pt) at 77 K as a function of substrate concentrations (CH2Cl2 and CHCl3) in ethanol and toluene. Some of the experimental conclusions have also been corroborated theoretically using density functional theory. Geometry optimization calculations have been performed for the model compounds Pd3(PH3)6CO2+...Cl-, Pd3(PH3)62+, Pd3(PH3)6CO2+...Cl0, Pd3(PH3)6CO2+...Cl-CH 3, and Pd3(PH3)6CO3+in their ground states.
Dinuclear PdII/PtIIcomplexes [M2(phosphine)n(thio-ligand)3]Cl incorporating N,S-bridged pyridine-2-thiolate and benzimidazoline-2-thiolate
Lobana, Tarlok S.,Sandhu, Amanpreet K.,Mahajan, Rakesh K.,Hundal, Geeta,Gupta, Sushil K.,Butcher, Ray J.,Castineiras, Alfonso
, p. 25 - 35 (2017/03/01)
Equimolar reaction of [PdCl2(dppm)] {dppm?=?bis(diphenylphosphino) methane} with pyridine-2-thione (pySH) in presence of NaOH base in aqueous ethanol formed dinuclear mixed-ligand complex, [PdII2(μ-κ2:N,S-pyS)3(μ-P,P-dppm)]Cl 1. Similarly, reaction of PdCl2(PPh3)2with benzimidazoline-2-thione (bzimSH) in 1:2?M ratio in the presence of Et3N base in acetonitrile has formed a dinuclear complex, [PdII2(μ-κ2:N,S-bzimS)2(κ1-S-bzimS)(PPh3)3]Cl·2H2O 2. Surprisingly, analogous thio-ligand, 1,3-imidazoline-2-thione (imzSH), merely formed a simple square planar complex, [Pd(κ1-S-imzSH)4]Cl2·2H2O 3. The reaction of H2PtCl6with pySH and dppm (1:1:1?M ratio) in the presence of Et3N base in toluene–ethanol (1:1:: v/v) mixture also formed a mixed-ligand dinuclear complex [PtII2(μ-κ2:N,S-pyS)3(μ-P,P-dppm)]Cl similar to 1. All these complexes have been characterized using analytical data, IR, NMR (1H,31P), UV–vis, fluorescence, ESI-mass and single crystal X-ray crystallographic techniques. The anionic thio-ligands are N,S-bridged in complexes 1 and 4, both N,S-bridged and κ1-S bonded in 2 and as neutral κ1-S bonded in 3. There are short M?M contacts in 1 and 4 (1: 2.7249(5) ? 4: 2.7350(8) ?). Complexes 1, 3 and 4 showed intense fluorescence. ESI mass spectral studies of 1, 3 and 4 revealed the formation of molecular ions and other species.
Variable bonding modes of pyrimidine-2-thione in PdII/Pt II complexes [M(η2-N, S-pymS)(η1-S- pymS)(PPh3)] and [M(η1-S-pymS)2(L-L)] (L-L = dppm, dppe)
Lobana, Tarlok S.,Kaur, Parminderjit,Hundal, Geeta,Butcher, Ray J.,Castineiras, Alfonso
, p. 747 - 753 (2009/04/13)
Reactions of pyrimidine-2-thione (HpymS) with PdII/Pt IV salts in the presence of triphenyl phosphine and bis(diphenylphosphino) alkanes, Ph2P-(CH2) m-PPh2 (m = 1, 2) have yielded two types of complexes, viz. (a) [M(η2-N, S- pymS)(η1-S- pymS)(PPh 3)] (M = Pd, 1; Pt, 2), and (b) [M(η1-S-pymS) 2(L-L)] {L-L, M = dppm (m = 1) Pd, 3; Pt, 4; dppe (m =2), Pd, 5; Pt, 6}. Complexes have been characterized by elemental analysis (C, H, N), NMR spectroscopy (1H, 13C, 31P), and single crystal X-ray crystallography (1, 2, 4, and 5). Complexes 1 and 2 have terminal η1-S and chelating η2-N, S-modes of pymS -, while other Pd/Pt complexes have only terminal η1-S modes. The solution state 31P NMR spectral data reveal dynamic equilibrium for the complexes 3, 5 and 6, whereas the complexes 1, 2 and 4 are static in solution state.
Pyridine-2-thionate as a versatile ligand in Pd(ii) and Pt(ii) chemistry: The presence of three different co-ordination modes in [Pd2(μ 2-S,N-C5H4SN)(μ2- κ2S-C5H4SN)(μ2-dppm) (S-C5H4SN)2]
Mendia, Aranzazu,Cerrada, Elena,Arnaiz, Francisco J.,Laguna, Mariano
, p. 609 - 616 (2007/10/03)
Reactions of [MCl2(L-L)], M = Pt, Pd; L-L = bis(diphenylphosphino)methane (dppm) or bis(diphenylphosphino)ethane (dppe), with NaC5H4SN in a 1: 2 molar ratio lead to mononuclear species [M(S-C5H4SN)2(P-P)], M = Pt; L-L = dppm (1) or dppe (2) and M = Pd; L-L = dppe (3), as well as to the dinuclear [Pd2(μ2-S,N-C5H4SN) (μ2-κ2S-C5H4SN) (μ2-dppm)(S-C5H4SN)2] (4). In contrast, reaction of [MCl2(dppm)] with NaC5H 4SN in a 1: 1 molar ratio leads to [Pd2(μ2- S,N-C5H4SN)3(μ2-dppm)]Cl (5) and trans-[Pt(S-C5H4SN)2(PPh2Me) 2] (6) respectively. The latter is formed in low yield by cleavage of the dppm ligand. The dinuclear derivatives 4 and 5 present an A-frame and lantern structure, respectively. The former showing three different co-ordination modes in the same molecule with a short Pd-Pd distance of 2.9583 (9) A and the latter with three bridging S,N thionate ligands showing a shorter Pd-Pd distance of 2.7291 (13) A. Both distances could be imposed by the bridging ligands or point to some sort of metal-metal interaction. The Royal Society of Chemistry 2006.
The Pd4(dppm)4(H)22+ Cluster: A Precatalyst for the Homogeneous Hydrogenation of Alkynes
Evrard, David,Groison, Katherine,Mugnier, Yves,Harvey, Pierre D.
, p. 790 - 796 (2008/10/09)
The catalytic properties of the title cluster toward the homogeneous hydrogenation of phenylacetylene, diphenylethyne and phenyl-1-propyne have been investigated as a function of temperature, pressure, solvents, substrate and cluster concentrations, and counterions. The title cluster is a precatalyst that exhibits a good catalytic activity under mild conditions (1 atm of H 2 at 20 °C) for the hydrogenation of alkynes and alkenes. For the alkyne substrates, the turnover frequencies (tof's) range between 200 and 500 h-1, and the product distribution varies as: cis-products, 75-90%; trans-products; 0-8% after 3 h of reaction. Based on the graphs -d[substrate]/dt vs [Pd4]1/2, the mechanism indicates a cluster dissociation into two dimers (presumably of the type Pd 2(dppm)2(H)(solvent)+). The variations of tof (or -d[substrate]/dt) as a function of [substrate] and pressure of H 2 are linear. At 1600 psi of H2, the tof can reach 2500-3000 h-1 (in THF). The tof also increases with temperature reaching a maximum at ～35 °C (tof: 1000-1300 h-1), but at higher temperatures cluster decomposition begins to occur, leading to a rapid decrease in rates of catalysis. At 50 °C, no catalysis is observed. The hydrogenation reaction can be stopped at the corresponding cis-alkenes with ～95% yields, depending on the substrate and experimental conditions used. The tof's also vary with the solvent, where stronger coordinating solvent molecules give higher tof's. In addition, the tof's do not change with the nature of the counterion, which acts as spectator in the catalysis.
Bimetallic complexes supported by bis(diphenylphosphino)methane anti and syn to the Mn-Pd bonds
Liu, Ye,Chien, Sheau Wei,Koh, Siok Bee,Vittal, Jagadese J.,Hor, T.S. Andy
, p. 86 - 92 (2008/10/08)
Redox condensation of PPN[Mn2(μ-PPh2)(CO) 8] and PdCl2(η2-dppm) gives bimetallic PdMn(μ-PPh2)(μ-dppm)(CO)3(PPh3) (1) with an unexpected formation of PPh3. The latter can be displaced when 1 reacts with free diphosphines (dppm, dppe, dppf) giving PdMn(μ-PPh 2)(μ-dppm)(CO)3(Ph2P-X-P(=O)Ph2) (2, X=CH2 (2a), C2H4 (2b), C5H 4FeC5H4 (2c)) and [PdMn(CO)3(μ- PPh2)(μ-dppm)]2(μ-Ph2P-X-PPh 2) (3a). Complexes 2 are A-frame -type bimetallic complexes with an syn-dppm bridging the Mn-Pd bond. In contrast, complex 3a is a double A-frame anti-bridged by dppm. As a result, the latter is trans to the Mn-Pd bonds. Both types of dppm bridges are substitutionally inert. Either bridging role is best served by dppm (and not dppe or dppf). The structures of the complexes were derived from NMR analyses of all complexes and X-ray single-crystal diffraction analyses of 1, 2a and 2b. The common and stable A-frame -type core in these bimetallics provides a thermodynamic driving force for the opposite transmetallation migration of phosphide and phosphine (dppm) when 1 is formed.
Self-assembly and anion encapsulation properties of cavitand-based coordination cages
Fochi,Jacopozzi,Wegelius,Rissanen,Cozzini,Marastoni,Fisicaro,Manini,Fokkens,Dalcanale
, p. 7539 - 7552 (2007/10/03)
Two novel classes of cavitand-based coordination cages 7a-j and 8a-d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P-M-P angle close to 90° between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic 1H and 19F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d revealed the presence of a single triflate anion encapsulated. Guest competition experiments revealed that the encapsulation preference of cages 7b,d follows the order BF4- > CF3SO3- ? PF6- at 300 K. ES-MS experiments coupled to molecular modeling provided a rationale for the observed encapsulation selectivities. The basic selectivity pattern, which follows the solvation enthalpy of the guests, is altered by size and shape of the cavity, allowing the entrance of an ancillary solvent molecule only in the case of BF4-.
Reactions of [PdX2(dppm)] complexes with grignard reagents
Stockland Jr., Robert A.,Anderson, Gordon K.,Rath, Nigam P.
, p. 5096 - 5101 (2008/10/08)
Reactions of [PdX2(dppm)] (X = Cl, Br) with a range of Grignard reagents have been investigated. Diorganopalladium complexes of the type [PdR2(dppm)] were obtained in good yield with the bulky mesityl or trimethylsilylmethyl groups,
