Rafael Usón

Anionic perfluorophenyl complexes of gold(I) and gold(III)

Abstract The preparation of organogold(I) anions of the types [AuRX]−, [AuR2]− and [AuRR′]− (R,R′ = C6F5 or 2,4,6,-C6F3H2; X = Cl, i, SCN. CN or N3) is accomplished in which the tetrahydrothiophen group of AuR(tht) is substituted by X,R or R′. Oragnogold(III) complexes of the general formulae [Aur2X2]−, [AuRR′X2]−, [AuR3X]− and [AuR4]− (R, R′ = C6F5, 2,3,4,6-C6F4H or 2,4,6,-C6F3H2; X = Cl, Br or I) are obtained either by oxidation of the above-mentioned gold(I) complexes or by substitution reactions of AuCl3(tht). The assignment of the cis- or, respectively, trans-configuration of the [AuR2X2]− derivatives is based on their IR spectra.

A new route for the synthesis of binuclear organometallic and inorganic palladium(II) complexes

Abstract A new generally applicable route for the preparation of binuclear organometallic palladium(II) complexes is described. Compounds of the general formula [Pd(μ-Cl)RL] 2 (R being C 6 F 5 or C 6 Cl 5 ; L being a neutral ligand with N, P, As, Sb or S as donor atom) have been obtained by the reaction of organometallic compounds of the PdR 2 L 2 type with PdCl 2 in acetone solution at room temperature. The reaction with PdCl 2 had also been used for the systhesis of inorganic palladium(II) derivatieves of the [PdCl 2 L] 2 type. The structure of the novel organometallic complexes is discussed.

(Polyhalophenyl)silver(I) complexes as arylating agents: Crystal structure of [(μ-2,4,6-C6F3H2)(AuPPh3)2]ClO4

Abstract The arylsilver derivatives AgR (R = C6F5, 2,4,6-C6F3H2 or C6Cl5) react with chlorogold(I) precursors [AuCl(tht), AuCl(PPh3), ClAu(dppm)AuCl (tht = tetrahydrothiophene, dppm = bis(diphenylphosphino)methane], to give the corresponding arylgold complexes in good yield. With gold precursors in higher oxidation state, AgC6Cl5 either causes reduction to gold(I) or gives no reaction, whereas AgC6F5 and AgC6F3H2 lead to gold(II) complexes (R2Au(dppm)AuR2) or gold (III) complexes [Au(C6F3H2)(C6F5)2(PPh3); Au(C6F3H2)2(C6F5)(tht); Au(C6F5)3(tht); Au(C6F3H2)3(tht)].

Mononuclear (Pd, Pt) and binuclear (Pd, Pd; Pd, Ag; Pt, Ag) complexes containing the bis(diphenylphosphino) amine ligand

Abstract By appropriate choice of precursors and solvent, complexes of the type M(C 6 X 5 ) 2 (dppa) 2 or M(C 6 X 5 ) 2 (dppa) (M = Pd, X = F, Cl; dppa = Ph 2 PNHPPh 2 ) can be prepared. Reaction of trans -M(C 6 F 5 ) 2 (dppa) 2 withAgClO 4 gives hereto-binuclear complexes of the type[(C 6 F 5 ) 2 M(μ-dppa) 2 Ag]ClO 4 . Addition of dppa to the perchlorato complexes Pd(OClO 3 )(C 6 F 5 )L 2 (L = PR 3 ) gives the cationic singly-bridged homo-binuclear species. [{Pd(C 6 F 5 )L 2 } 2 (μ-dppa)](ClO 4 ) 2 . The binuclear Pd 1 complex [{Pd(C 6 F 5 } 2 (μ-dppa) 2 ] has been obtained from the reaction between Pd(C 6 F 5 ) 2 (dppa) 2 and Pd 2 (dba) 3 ·CHCl 3 and its insertion reactions have been studied. The dppa ligand acts as monodentate, bidentate-chelate or bidentate-bridging ligand depending on the precursors, the solvent, and the reaction conditions.

Binuclear organopalladium(II) complexes with bridging biimidazolate, bibenziimidazolate or tetramethylbiimidazolate anions

Abstract Neutral and anionic pentachloro- or pentafluorophenyl palladium(II) complexes containing biimidazolate, bibenziimidazolate or 4,5-4′,5′-tetramethylbiimidazolate anions, which act as tetradentate bridging ligands, have been prepared by reacting mononuclear palladium acetylacetonate complexes with 2,2′-biimidazol, 2,2′-bibenziimidazol or, respectively 4,5-4′,5′-tetramethylbiimidazol, or by treating the thallium salts of these ligands with binuclear halide-bridged palladium(II) derivatives. The structure of the resulting complexes has been elucidated by conductance studies and IR spectroscopy.

Tris(pentafluorophenyl)gold(III) complexes with O-, N- or S-donor ligands

Abstract Au(C6F5)3(OEt2) is a better intermediate complex than Au(C6F5)3·tht (tht = tetrahydrothiophen). The former compound can be prepared from (NBu4)ue5f8 [Au(C6F5)3Br] and AgClO4 in diethylether and the ether ligand can be easily displaced by neutral ligands [L = THF, OCMe2, diox, EtOH, SPPh3, SPPh2Me, OPPh3, OAsPh3, NCMe, NCPh, NCPr, NCCHue5fbCH2, oue5f8(NC)2C6H4] as well as cationic ones [(X)PPh2CH2ue5f8 PPh2R]+ [X = S, R = Me, CH2C6F5, COOMe, CH2Ph; X = O, R = CH2Ph] to give the corresponding neutral or cationic tris(pentafluorophenyl)gold(III) complexes most of which were hitherto unaccessible.

Perhalophenyl complexes of palladium(II) containing keto-stabilized phosphorus ylides of the type Ph2P(CH2)nPPh2CHC(O)R

Abstract From suitable perhalophenyl derivatives of palladium(II), viz.: Pd(C6F5)2-(SC4H8)2, [Pd(μ-X′) (C6X5)2]2(NBu4)2, [Pd(μ-Cl)(C6X5)(SC4H8)]2 (X = F, Cl, X′ = Cl, Br), new complexes of various types have been prepared, viz.: trans-Pd(C6F5)2(Y)2, Pd(C6X5)2(Y), PdCl(C6X5)(Y) (X = F, Cl). The neutral ligand Y is a keto-stabilized phosphorus ylide of the type Ph2P(CH2)nPPh2CHC(O)R (n = 1, R = CH3, C6H5; n = 2, R = C6H5) acting in a terminal monodentate P-donor or a bidentate chelate P,C-donor mode. The reaction of PdCl(C6F5)(Y) complexes with HCl leads to the corresponding PdCl2(C6F5)(YH) complexes in which the phosphonium cation [YH]+ behaves as monodentate P-donor at its phosphinic end. IR and 31P NMR spectroscopy were used to decide the coordination mode of the ligands and, in some cases, to reveal the presence of two isomers.

Anionic perhaloaryl-palladium and -platinum complexes as sources of unusual homo- and hetero-nuclear compounds

As we began our work in the field of organometallic chemistry our choice of perhaloatyl groups (C6X5, X = F, Cl) as the organic ligands was determined by the expectation they would give rise to stronger M-&i (b) the decrease in the electron density on the metal, which leads to contraction of its filled d orbitals and so a decrease in the repulsion between them and the group attached to the a-carbon atom; (c) the contraction of the metal orbital forming the metal-carbon u-bond, and thus an increase in the strength of this bond in R, as opposed to R, complexes; (d) the possibility of back donation of electron density from filled d orbitals to rr*-orbitals on the aryl ligands; (e) the h and, possibly, (f) a greater inertness of the M-R, bond, involving a greater kinetic stability of the perhalo derivatives [l]. Since our aim was the synthesis of organometalhc compounds stable enough for the study of the reactions at the metal centres, strong or inert Mr-C bonds were a requisite if the organometallic character was to be preserved throughout the reactions. To date there has been no direct proof of the greater strength of M-GX, (M = Pd, Pt) relafive to M-QH, bonds; for instance, the M-C distances are very similar (2.06 A) in aryl and perfluoroaryl complexes [2], although only few comparable cases have been studied. It is a fact, however, that the perhaloaryl derivatives, whatever the reason, are more stable: time and again we have attempted the preparation of the corresponding aryl derivatives only to find that the synthetic procedures that allowed isolation of GX, stable derivatives in good yield led to decomposition to metallic powders if C,H, groups were present instead C,X, in the precursor. Furthermore, we have seen our initial expectations generally confirmed,

Stereospecific reactions of the M(C6F5)2 (M=Pd or Pt) synthons towards cis-dithiolato complexes

Abstract Complexes of the general formula cis -[M(SC 6 F 5 ) 2 L 2 ] (M ue5fb Ni, Pd, or Pt; L 2 ue5fb dppm [bis(diphenylphosphino)methane], dppe [ 1,2-bis(diphenylphosphino)ethane], or 2PPh 3 were synthesized by the reaction (1 : 2 between the corresponding cis -[MCl 2 L 2 ] and Tl(SC 6 F 5 ). When treated with cis -[M(C 6 F 5 ) 2 (THF) 2 ] (M ue5fb Pd or Pt; THF ue5fb OC 4 H 8 they yield geminal homo- or hetero-binuclear compounds, which were characterized by IR, NMR and mass spectroscopy.

Synthesis of (NBu4)2[Pd2(μ-Br)2(C6X5)2Br2] (X=F, Cl), new and more versatile precursors of pentahalophenyl derivatives of palladium(II)

Abstract The title compounds (1, X=F; 2, X=Cl) were obtained in quantitative yield by refluxing together (NBu4)2[Pd2(μ-Br)2(C6X5)4] and (NBu4)2[Pd2(μ-Br)2Br4]. Treatment of 1 or 2 with AgClO4 (Pd:Ag= 1:1) gave solutions which behaved as containing ‘Pd(C6X5)Br’. 1, 2 and the ‘Pd(C6X5)Br’ solutions were checked as precursors of mono-pentahalophenyl derivatives, yielding a variety of complexes [Pd(C6X5)Br(L-L)] (L-L=bipy, tmen, dpe, COD), [Pd(C6X5)BrL2] (L=p-TolNH2, py, PPh3, AsPh3, SbPh3), [Pd2(μ-Br)2(C6X5)2L2] (X=F, L=AsPh3; X=Cl, L=SbPh3) and (NBu4)[Pd(C6X5)Br2L] (X=F, L= py, AsPh3, SbPh3; X=Cl, L=p-TolNH2, py, PPh3, AsPh3, SbPh3). The solutions of ‘Pd(C6X5)Br’ proved to be the best general precursors of complexes [Pd(C6X5)BrL2] although complexes with OPPh3 could not be obtained.