136827-07-1

Basic information

• Product Name: Pd2{(η6-C6H5)Cr(CO)3}2(μ-Cl)2(PPh3)2
• Synonyms: Pd2{(η6-C6H5)Cr(CO)3}2(μ-Cl)2(PPh3)2
• CAS NO: 136827-07-1
• Molecular Weight: 1234.59
• Mol File: 136827-07-1.mol
• Article Data: 1

Chemical Properties

• CAS DataBase Reference: Pd2{(η6-C6H5)Cr(CO)3}2(μ-Cl)2(PPh3)2(CAS DataBase Reference)
• NIST Chemistry Reference: Pd2{(η6-C6H5)Cr(CO)3}2(μ-Cl)2(PPh3)2(136827-07-1)
• EPA Substance Registry System: Pd2{(η6-C6H5)Cr(CO)3}2(μ-Cl)2(PPh3)2(136827-07-1)

Safety Data

• Hazardous Substances Data: 136827-07-1(Hazardous Substances Data)

Upstream product

• 14221-01-3 tetrakis(triphenylphosphine) palladium⁽⁰⁾ 
• 12082-03-0 tricarbonyl(η6-chlorobenzene)chromium 
• 32005-36-0 bis(dibenzylideneacetone)-palladium⁽⁰⁾ 

Downstream Products

• 136805-09-9 trans-Pd{(η6-C6H5)Cr(CO)3}Cl(PPh2Et)2 
• 136805-10-2 cis-Pd{(η6-C6H5)Cr(CO)3}Cl(dppe) 
• 136805-14-6 Pd2{(η6-C6H5CO)Cr(CO)3}2(μ-Cl)2(PPh3)2 
• 136805-08-8 trans-Pd{(η6-C6H5)Cr(CO)3}Cl(PEt2Ph)2 
• 136827-08-2 trans-Pd{(η6-C6H5)Cr(CO)3}Cl(dpph) 
• 13965-03-2 bis-triphenylphosphine-palladium(II) chloride 
• 136805-06-6 trans-Pd{(η6-C6H5)Cr(CO)3}Cl(PPh3)2 

Relevant articles and documents

Bimetallic activation in homogeneous catalysis. 3. Mechanistic study of the methoxycarbonylation of tricarbonyl(chlorobenzene)chromium: Isolation and reactivity of possible reaction intermediates

The coordination of the Cr(CO)3 moiety to the aromatic ring allows the carbonylation of chlorobenzene, catalyzed by palladium complexes, to esters, aldehydes, amides or α-oxo-amides. The mechanism of methoxycarbonylation of tricarbonyl(chlorobenzene)chromium, (η6-C6H5Cl)Cr(CO)3, and the role of the Cr(CO)3 moiety are now investigated. Tricarbonyl(chlorobenzene)chromium reacts at room temperature with Pd(PPh3)4 or Pd(dba)2 and PR3 via an oxidative addition to give aryl-palladium complexes of the type {Pd[(η6-C6H5)Cr(CO)3](Cl)L y}2/y, which are monomers (L = PPh3 (1), PEt2Ph (4), PPh2Et (5)) or dimers (L = PPh3 (2), PCy3 (3)). By comparison, the oxidative addition of PhCl to Pd(PPh3)4 is known to proceed at 140 °C, indicating that the coordination of Cr(CO)3 to PhCl greatly enhances the rate of this reaction. However, this reaction does not proceed with L2 = dppe or dpph, but the same complexes can be prepared by Cl-bridge cleavage and/or phosphine exchange with PR3 on Pd2[(η6-C6H5)Cr(CO) 3]2(μ-Cl)2(PPh3)2 to give the monomers (L = PEt2Ph (4), PPh2Et (5); L2 = dppe (6), dpph (7)) and the dimer (L = PCy3 (3)). The X-ray structures of complexes trans-Pd2[(η6-C6H5)Cr(CO) 3]2(μ-Cl)2(PCy3)2 (3) and cis-Pd[(η6-C6H5)Cr(CO)3]Cl (dppe) (6) have been determined. Crystal data for 3: orthorhombic with the space group Pccm; a = 18.486 (8) A?, b = 20.401 (7) A?, c = 17.255 (6) A?, V = 6508 A?3, Z = 8. Crystal data for 6: monoclinic with the space group P21/n, a = 9.841 (2) A?, b = 12.783 (5) A?, c = 28.377 (2) A?, β = 92.23 (1)°, V = 3567 A?3, Z = 4. These aryl-palladium complexes react at room temperature with CO under atmospheric pressure (L = PPh3, PEt2Ph; L2 = dpph) or 5 bar (L = PCy3) to give the corresponding monomeric or dimeric acyl-palladium complexes of the type {Pd[(η6-C6H5CO)Cr(CO) 3](Cl)Ly}2/y (y = 2: L = PPh3 (8), PEt2Ph (9), L2 = dpph (10); y = 1: L = PPh3 (11), PCy3 (12)). The reaction does not proceed with L2 = dppe even under 30 bar of CO; Cl-bridge cleavage and phosphine exchange with dppe on Pd2[(η6-C6H5CO)-Cr(CO) 3]2(μ-Cl)2(PPh3)2 enable the formation of cis-Pd[(η6-C6H5CO)Cr(CO) 3]Cl(dppe) (13). Methanolysis of complexes Pd[(η6-C6H5CO)Cr(CO) 3]Cl(PPh3)2 (8) and Pd2[(η6-C6H5CO)Cr(CO) 3]2(μ-Cl)2(PPh3)2 (11) in the presence of triethylamine at room temperature proceeds rapidly and leads to the formation of (η6-C6H5COOMe)Cr(CO)3, which is the product of methoxycarbonylation of (η6-C6H5Cl)Cr(CO)3. Complexes {Pd[(η6-C6H5)Cr(CO)3]Cl(PPh 3)y}2/y (1, 2) and {Pd[(η6-C6H5CO)Cr(CO) 3]Cl(PPh3)y}2/y (8, 11) then appear to be reasonable intermediates in the catalytic cycle of methoxycarbonylation of (η6-C6H5Cl)Cr(CO)3. A possible mechanism for this reaction is discussed.