Search results for "Migratory insertion"
showing 6 items of 6 documents
Mechanistic Study of Stepwise Methylisocyanide Coupling and C-H Activation Mediated by a Low-Valent Main Group Molecule
2013
An experimental and DFT investigation of the mechanism of the coupling of methylisocyanide and C-H activation mediated by the germylene (germanediyl) Ge(Ar(Me6))2 (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2) showed that it proceeded by initial MeNC adduct formation followed by an isomerization involving the migratory insertion of the MeNC carbon into the Ge-C ligand bond. Addition of excess MeNC led to sequential insertions of two further MeNC molecules into the Ge-C bond. The insertion of the third MeNC leads to methylisocyanide methyl group C-H activation to afford an azagermacyclopentadienyl species. The X-ray crystal structures of the 1:1 (Ar(Me6))2GeCNMe adduct, the first and final insertion …
Insertion of isocyanides into the 2-one-1-propyl—palladium(II) bond: A convenient synthetic route to C1-palladated 1-amino-3-one-1-butene compounds
1984
Abstract Migratory insertion of isocyanides CNR (R = p -C 6 H 4 OMe, Me) into the palladium—carbon σ bond of trans -[PdCl(CH 2 COMe)(PPh 3 ) 2 ] (I) yields the 1-amino-3-one-1-butenyl complexes trans -[PdCl{C(NHR)CHCOMe}(PPh 3 ) 2 ] (IIa, R = p -C 6 H 4 OMe; IIb, R = Me), which have been characterized by IR, 1 H and 31 P NMR spectra. The reaction of IIa with nickel acetate gives a diamagnetic bischelate complex of the type [Ni(ON) 2 ] , in which the deprotonated 1-amino-3-one-1-butenyl moiety acts as a bidentate O,N ligand.
N-protonated 2-pyridylnickel(II) complexes insertion of isocyanides into the nickel2-pyridyl bond
1987
The reaction of the binuclear complex [NiCl(μ-2-py)(PPh3)]2 (μ-2-py = μ-C5H4N-C2,N) with the phosphines L (L = PPh3, PMePh2, PMe2Ph or PEt3) or dppe (= 1,2-bis(diphenylphosphino)ethane) in the presence of HClO4 yields the N-protonated 2-pyridyl derivatives trans-[NiCl(2-pyH)(L)2]ClO4 or [NiCl(2-pyH)(dppe)] ClO4 (2-pyH = C5H5N-C2) with a square-planar coordination around the nickel(II) center. These products are largely associated through hydrogen bonding between the NH group and the perchlorate anion, both in the solid and in chlorinated solvents. The configuration in solution has been studied by 1H and 31P NMR spectroscopy. In the complex trans-[NiCl(2-pyH)(PMe2Ph)2]ClO4, the planar 2-pyH…
Preparation and reactions of palladium(II) complexes with C2-bonded heteroaromatic ligands trans[PdCl(RN)(PPh3)2] (RN = 2-pyridyl, 2-pirazyl, 2-pyrim…
1986
Abstract The complexes trans -[PdCl(R N )(PPh 3 ) 2 ] (I) [R N = 2-pyridyl (2-Py), 2-pyrazyl (2-pyz), 2-pyrimidyl (2-pym) group] have been prepared in high yield by deprotonation with NEt 3 of the corresponding cationic compounds trans [PdCl(R N H) (PPh 3 ) 2 ] + (R N H = N -protonated C 2 -heteroaromatic ligand) in the presence of an excess of PPh 3 . In chlorinated solvents, complexes I undergo a slow reversible dimerization into the binuclear derivatives [PdCl(μ-R N )(PPh 3 )] 2 (II) (μ-R N = C 2 , N 1 -bridging ligand). From the 31 P NMR spectra in 1,2-dichloroethane the following dissociation constants were obtained: 1.9 mol 1 −1 (R N = 2-py), 5.1 × 10 −2 (2-pym), 6.6 × 10 −3 (2-pyz). …
Preparation and reactions of 1-methylpyrid-6-one-2-yl compounds of palladium(II) and platinum(II)
1984
Abstract The compounds trans -[MCl{(1-Me)C 5 H 3 (6-O)N- C 2 }(L) 2 ] (M = Pd, Pt; L = PPh 3 , PMe 2 Ph), can be prepared from the reaction of the corresponding 1-methyl-6-chloro-2-pyridylium cationic complexes, trans -[MCl{(1-Me)C 5 H 3 (6-Cl)N- C 2 }(L) 2 ]ClO 4 , with a mixture of acetic acid, ethanol, and triethylamine in the molar ratio M/MeCO 2 H/EtOH/NEt 3 of 1/3/3/4. The rate is slow compared to that of the 1-methyl-2-chloropyridinium cation under similar conditions, and is markedly affected by the steric and electronic effects of the trans -MCl(L) 2 unit. The novel 1-methylpyrid-6-one-2-yl derivatives have been characterized by conventional spectroscopic techniques and by reactions…
INSERTION OF ISOCYANIDES INTO THE PALLADIUM CARBON BOND OF C-2-PALLADATED HETEROCYCLES - SYNTHESIS OF TRANS-[PDCL(C(RN)=NR) (PPH3)2] COMPLEXES (RN = …
1985
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…