0000000000798170
AUTHOR
Francesca Dibianca
Preparation and protonation of 2-pyrimidyl- and 2-pyrazylpalladium(II) complexes
Abstract The oxidative addition of 2-chloropyrimidine or 2-chloropyrazine to [Pd(PPh 3 ) 4 ] yields a mixture of trans -[PdCl(C 4 H 3 N 2 - C 2 )(PPh 3 ) 2 ] (I) and [PdCl(μ-C 4 H 3 N 2 - C 2 , N 1 )(PPh 3 (II) (C 4 H 3 N 2 = 2-pyrimidyl or 2-pyrazyl group). The mononuclear complexes I are quantitatively converted into the binuclear species II upon treatment with H 2 O 2 . The reaction of II with HCl gives the N -monoprotonated derivatives cis -[PdCl 2 (C 4 H 4 N 2 - C 2 )(PPh 3 )] (III), from which the cationic complexes trans -[PdCl(C 4 H 4 N 2 - C 2 )(L) (L = PPh 3 , IV; PMe 2 Ph, V; PEt 3 , VI) can be prepared by ligand substitution reactions. Reversible proton dissociation occurs in so…
Migration of bidentate anionic ligands in binuclear compounds derived from 1,2-bis(imino)propyl-palladium(II) complexes
Abstract The complexes [Pd(AB){C(NR)CMeNR}(PPh3)] (I; AB = 2,4-pentanedionate, N-methylsalicylaldiminate, pyrrole-2-N-methylaldiminate; R = p-C6H4OMe) react with ‘MCl2’ (‘MCl2’ = CoCl2, NiCl2, CuCl2, ZnCl2, [PdCl2(NCMe)2], K[PtCl3(CH2CH2)]) to give either the binuclear adducts [(PPh3)(AB)Pd{C(NR)CMeNR}MCl2] (II) or the zwitterionic isomers [(PPh3)Cl2Pd{C( NR)CMeNR}M (AB)] (III) depending on the nature of the metal M and of the anionic ligand AB. The formation of products III is accounted for in terms of an intramolecular migration of ligands between the two metal centers Pd and M of the initially formed MCl2 adducts II.
Structural studies on 2-pyridyl complexes of the platinum triad metals. The crystal and molecular structure of the 2-pyridylium derivative trans-[PdCl(C5H5NC2)(PMe2Ph)2]ClO4
Abstract In solution, the complex trans -[PdCl(C 5 H 4 N C 2 )(PMe 2 Ph) 2 ] ( 1 ) is in equilibrium with a small amount of the binuclear species [{PdCl(μ-C 5 H 4 N C 2 , N )(PMe 2 Ph)} 2 ] ( 2 ), which can be isolated upon recrystallization. The compound 1 is easily N-protonated by HClO 4 to the 2-pyridylium product trans -[PdCl(C 5 H 5 N C 2 )(PMe 2 Ph) 2 ]ClO 4 ( 3 ), which crystallizes in the orthorhombic space group P2 1 2 1 2 1 , with cell parameters a =15.761(3), b =14.369(2), c =11.132(2) A and Z =4. The X-ray crystal structure analysis of 3 , using 3744 observed reflections in the refinement and resulting in a final R value of 0.0298, shows that the coordination around palladium…
INSERTION OF ISOCYANIDES INTO THE PALLADIUM CARBON BOND OF C-2-PALLADATED HETEROCYCLES - SYNTHESIS OF TRANS-[PDCL(C(RN)=NR) (PPH3)2] COMPLEXES (RN = 2-PYRIDYL, 2-PYRAZYL - R = ALKYL OR ARYL GROUP)
The titles complexes trans-[PdCl{C(RN)NR}(PPh3)2] (RN = 2-pyridyl (2-py), R = p-C6H4OMe, Me; RN = 2-pyrazyl (2-pyz), R = p-C6H4OMe) can be prepared by reaction of the N-protonated compounds, cis-[PdCl2(RNH)(PPh3] (RNH = 2-pyridylium (2-pyH) or 2-pyrazylium (2-pyzH) group), with PPh3, followed by addition of the isocyanide CNR and deprotonation with triethylamine, in a molar ratio Pd/PPh3/CNR/NEt3 of 1/1/1/1.1. The reaction sequence involves the successive formation of the cationic intermediates trans-[PdCl(RNH)(PPh3)2]+, trans-[Pd(RNH)(CNR)(PPh3)2]2+ and trans-[Pd(RN)(CNR)(PPh3)2]+, which were isolated and characterized as perchlorate salts for RN = 2-pyridyl. In the final step the coordin…