Noriko Chikaraishi Kasuga

Synthesis, structure and properties of dimethyl(alkoxycarbonyl)gold(III) complexes having a triphenylphosphine ligand

Abstract cis -Dimethyl(alkoxycarbonyl)(triphenylphosphine)gold(III) ( cis -AuMe 2 (COOR)(PPh 3 ); R  Me ( 1 ), Et ( 2 ), i Pr ( 3 )) has been synthesized by the reaction of carbon monoxide with dimethyl(methoxo)(triphenylphosphine)gold(III) prepared in situ from cis -dimethyliodo(triphenylphosphine)gold(III) and sodium methoxide in methanol. Thermolysis of 1 in benzene leads to a reductive elimination of both methyl acetate and ethane. Protonolysis of 1 with acids such as hydrogen chloride and acetic acid gives cis -dimethyl(aniono)(triphenylphosphine)gold(III) accompanied by liberation of carbon monoxide and methanol. Reaction of 1 with acetyl chloride liberates methyl acetate and carbon monoxide. The square planar structure of 1 is unequivocally confirmed by an X-ray diffraction study. Related gold(I) complex, (methoxycarbonyl)(triphenylphosphine)gold(I) is also isolated by a similar reaction of chloro(triphenylphosphine)gold(I) with carbon monoxide in the presence of sodium methoxide.

Stereoselective formation and reactions of tetraalkylaurates(III)

Abstract Reactions of cis - (or trans -) dimethylalkyl(triphenylphosphine)gold(III), Au(R 1 )(R 2 ) (R 3 )(PPh 3 ) with alkyllithiums (R 4 Li) lead to selective displacement of the triphenylphosphine ligand by the alkyl anion to give square planar cis - (or trans -)tetraalkylaurates(III), [Au(R 1 ) (R 2 )(R 3 )(R 4 )] − Li + (R 1 = Me, R 2 = R 3 = Me or Et, R 4 = Me, Et, n Pr, n Pr, n Bu or Ph) in benzene. The reactions are stereoselective and no isomerization is observed. Rates of the reactions between the trialkylgold(II) complex and alkyllithiums are first order in the concentration of the gold(III) complex, and an associative mechanism involving the neutral trimethylgold(III) complex and alkyllithiums for the formation of tetraalkylaurates(III) has been proposed as a result from the kinetic study. Hydrolyses of cis - or trans -dimethyldiethylaurates(III) in the presence of triphenylphosphine afford cis -methyldiethyl(triphenylphosphine) gold(III) or trans -di-methylethyl(triphenylphosphine)gold(III) with liberation of an equimolar amount of the corresponding alkane, reflecting the strong trans effect of the alkyl group in the reaction. Molecular structure of cis -methyldiethyl (triphenylphosphine)gold(III) has been unequivocally determined by X-ray structure analysis (monoclinic, P 2 1 / c , a 10.972(6), b 19.898(9), c 10.683(7) A, γ 112.42(4)°, V 2156(2) A 3 , R = 7.8, R w = 11.6 for 3947 reflections (| F o | ⪢ 3 | F o |).

Isolation of a zerovalent iron dinitrogen complex with 1,2-bis(diethylphosphino)ethane ligands

A zerovalent iron dinitrogen complex [Fe(N2)(depe)2] having 1,2-bis(diethylphosphino)ethane ligands has been prepared by reduction of [FeCl2(depe)2] with sodium–naphthalene in tetrahydrofuran under nitrogen at room temperature.