Insertion reactions of SO₂into Pd–OR bonds: preparation of alkyl sulfito complexes of palladium(ii)

Abstract

Mononuclear palladium-hydroxo complexes of the type [Pd(N-N)(C6F5)(OH)][(N-N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me2bipy), or N,N,N',N'-tetramethylethylenediamine (tmeda) react with SO2(1 atm) at room temperature in alcohol (methanol, ethanol, propanol or isopropanol) to yield alkyl sulfito palladium complexes [Pd(N-N)(C6F5)(SO2OR)](R = Me, Et, Pr or iPr). Similar alkyl sulfito complexes [Pd(N-N)(C6F5)(SO2OR)](N-N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me or Et) are obtained when [Pd(N-N)(C6F5)Cl] is treated with KOH in the corresponding alcohol ROH and SO2 is bubbled through the solution. The reaction of [Pd(bipy)(C6F5)(OH)] with SO2 in tetrahydrofuran gives [Pd(N-N)(C6F5)(SO2OH)]. The X-ray diffraction study of [Pd(tmeda)(C6F5)(SO2OPr)] has established the sulfur coordination of the propyl sulfito ligand.

Palladium(II) and Platinum(II) Organometallic Complexes with the Model Nucleobase Anions of Thymine, Uracil, and Cytosine: Antitumor Activity and Interactions with DNA of the Platinum Compounds

“…NMR Data for Complexes 10 − 13. The characteristic resonances of the chelate ligands are observed in the 1 H NMR spectra, ,,− and the assignments presented in the Experimental Section are based on the atom numbering given in Scheme . The 19 F NMR spectra of complexes 10 − 13 at room temperature show hindered rotation of the C 6 F 5 ring around the Pd−C bond, and two separate signals are observed for the o -fluorine atoms but only one for the p -fluorine atom.…”

“…On the other hand, the hydroxo complexes [Pd(dmba)(μ-OH)] 2 (dmba = N,C-chelating 2-((dimethylamino)methyl)phenyl) and [Pd(C 6 F 5 )(N−N)(OH)] (N−N = bpy, Me 2 bpy, or tmeda with bpy = 2,2‘-bipyridine, Me 2 bpy = 4,4‘-dimethyl-2,2‘-bipyridine, tmeda = N , N , N ‘, N ‘-tetramethylethylenediamine) have shown to be excellent precursors in organometallic synthesis. − …”

Pentafluorophenyl imidato palladium(ii) complexes: catalysts for Suzuki cross-coupling reactions

“…We have recently described 34, 35 the synthesis of monomeric hydroxo palladium(II) complexes of the type [Pd(N-N)(C 6 F 5 )(OH)] (N-N = bipy, Me 2 bipy, phen or tmeda) and their reactions with CO or SO 2 in methanol at room temperature to yield the corresponding methoxy carbonyl or alkylsulfito complexes [Pd(N-N)(C 6 F 5 )(X)] (X = CO 2 Me or SO 3 Me)]. We have also shown 36 the reactions of the monomeric hydroxo complexes [Pd(N-N)(C 6 F 5 )(OH)] with some active methyl (CH 3 COR or CH 3 NO 2 ) and methylene (CH 2 X 2 ) (X = CO 2 Et or CN) to yield the corresponding C-bound enolate palladium complexes.…”

Condensation reactions of monomeric hydroxo palladium complexes with active methyl and methylene compounds

“…Recently abstraction of the a-proton of a carbonyl compound by a hydroxo palladium complex has been reported to be a key for the synthetically useful enantioselective catalysis. 29 We have recently described 30,31 the synthesis of monomeric hydroxo palladium(II) complexes of the type [Pd(N-N)(C 6 F 5 )(OH)] (N-N = bipy, Me 2 bipy, phen or tmeda) and their reactions with CO or SO 2 in methanol at room temperature to yield the corresponding methoxy carbonyl or alkylsulfito complexes [Pd(N-N)(C 6 F 5 )(X)] (X = CO 2 Me or SO 3 Me)]. The reactions of the monomeric hydroxo complexes [Pd(N-N)(C 6 F 5 )(OH)] with some active methyl (CH 3 COR or CH 3 NO 2 ) and methylene (CH 2 X 2 ) (X = CO 2 Et or CN) compounds have now been examined and we report herein the first crystal structure of a dicyanomethanide-palladium complex (3D Search using the Cambridge Structural Database, CSD version 5.25, April 2004 release), together with the crystal structures of an acetonyl-palladium complex, a nitromethyl-palladium complex, and a dimethyl malonate-palladium complex.…”