Dirk J. A. De Waal

The novel cyclodimerization of phenylacetylene at a ruthenium(II) centre. The synthesis and X-ray structural characterization of the first metallacyclopentatriene, [(η-C5H5)Ru(C4Ph2H2)Br], and its facile conversion into metallacyclopentadienes

Cyclodimerization of two molecules of phenylacetylene at the ruthenium(II) centre in [(η-C5H5)Ru(η-C8H12= cyclo-octa-1,5-diene) gives the novel ruthenacyclopentatriene [(η-C4H5)Ru(C4Ph2H2)Br] characterized by 1H and 13C n.m.r. spectroscopy and by X-ray analysis; the triene undergoes facile ‘oxidative addition’ with donor ligands L (e.g. morpholine, trimethyl phosphite, dimethylphenylphosphine) in a bimolecular reaction involving an associative mode of activation to give the ruthenacyclopentadienes [(η-C5H5)Ru(L)(C4Ph2H2)Br].

The chemistry of cyclopentadienyl-ruthenacyclopentatrienes: novel carbon monoxide and isocyanide insertion reactions in [η5-C5H5)Ru(η4-C5Ph2H2NBut)Br]

Abstract Reaction of the novel ruthenacyclopentatriene [(η5-C5H5)Ru(C4Ph2H2)Br] (1) with isocyanides gives the imino-2,5-diphenylcyclopentadiene complexes [(η5-C5H5Ru(η4-C5Ph2H2NR)Br] (2, R = Me, Et, Cy, t-Bu, 2,6-Me2C6H3); a novel fluxional process involving phenyl substituent rotation and imino nitrogen inversion has been identified for 2 (R = t-Bu, 2,6-Me2C6H3), the interpretation of which is supported by the X-ray crystal structure determination of 2 (R = t-Bu).

Preparation of (η-cyclo-octa-1,5-diene)halogenohydridobis(phosphine)-iridium(III) salts and kinetic study of the oxidative-addition reactions of (η-cyclo-octa-1,5-diene)bis(phosphine)iridium(I) salts with hydrohalogenic acids: evidence for anionic intermediates

The complexes [IrH(X)(cod)L2][PF6][cod = cyclo-octa-1,5-diene, X = Cl, Br, or I, L = PPh2(OMe) or PMePh2; X = Cl or Br, L = PEtPh2] and [IrHX2(cod)L](X = Br or I, L = PMePh2 or PEtPh2) have been synthesised from HX (X = Cl, Br, or I) and the salts [Ir(cod)L2][PF6][L = PPh2(OMe), PMePh2, or PEtPh2]. The equilibrium (i)[Ir(cod)L2]++ Cl–⇌[IrCl(cod)L]+ L (i) exists due to steric crowding, and explains the presence of the second chloride in the end product. Kinetic studies on both the oxidative-addition reactions of [Ir(cod)L2]+ and [lrCl(cod)L] with HCl have revealed that the nucleophilic attack of Cl– precedes the protonation of the complexes.

Kinetics and mechanism of reactions of gold(III) complexes. VI. Substitution reactions by methyl substituted diethylenetriamines in tetrachlorogold(III)

Abstract The reaction, AuCl4− + am→AuCl2am+ + 2Cl− where am = xN, yN′-(x+y)methylethylenediamine (x = 1, 2; y = 0, 1, 2) in aqueous acid medium obeys the rate law where k and k′ are constants. The formation of ion pairs between the protonated amines and chloride ion is considered as a possibility for explaining this rate law. Data ware taken at different amine, hydrogen, and chloride ion concentrations and temperatures.

Preparation of the five-co-ordinate complexes [PdX2(PMe2Ph)3](X = Cl, Br, or I) and the crystal and molecular structure of dichlorotris-[dimethylphenylphosphine]palladium

The preparation of tris(dimethylphenylphosphine) dihalogenopalladium(II) complexes and the crystal structure of dichlorotris(dimethyIphenylphosphine)palladium(II) are reported. The co-ordination of the palladium ion is distorted square pyramidal with one palladium–chloride bond of 2.96 A.The possibility of the five-co-ordinate complex being a tight ion-pair. [PdX(PMe2Ph)3][X], is discussed in terms of the u.v.–visible spectra of [PdX2(PMe2Ph)3] and [PdX(PMe2Ph)3][PF6].

Nucleophilic attack on a ligand as a pre-requisite for ligand replacement. Kinetics and mechanism of the replacement of PMe2Ph by P(OMe)3 in [Ru(S2CH)(PMe2Ph)3{P(OMe)3}]+

Kinetic data reveal that nucleophilic attack of added PMe2Ph on the dithioformato carbon atom of the title complex catalyses the substitution of PMe2Ph by P(OMe)3to give [Ru(S2CH)(PMe2Ph)2{P(OMe)3}2]+; the structure of one of the intermediates is inferred from the isolation of [Ru{S2C(H)PMe2Ph}(PMe2Ph)2{P(OMe)2Ph}]+.

Kinetic evidence for a possible end-on oxidative addition of dioxygen to a five-co-ordinate iridium(I) complex

Kinetic measurements have been shown dioxygen to react faster with the five-co-ordinate complex [(cod)Ir(phen)I](cod = cyclo-octa-1,5-diene; phen = 1,10-phenanthroline) than with the four-co-ordinate complex [(cod)Ir(phen)]Cl to form the peroxide complex [(cod)Ir(phen)O2]X (X = Cl, I).

Kinetics and mechanism of cyclo- and decyclo-metallation of some iridium triaryl phosphite complexes. Evidence for the electrophilic displacement mechanism

The formation of [IrH(P–C)(cod)L]X [P–C = P(OC6H3Me-o)(OC6H4Me-o)2, cod = cyclo-octa-1,5-diene, L = P(OC6H4Me-o)3 or PMe2Ph] from [Ir(P–C)(cod) L] and HX (X = ClO4, PF6, or BF4) is proposed to occur by a mechanism involving direct proton attack at the metallated carbon for ring opening, followed by electrophilic displacement of a proton from an ortho-C–H by a preformed iridium(III) hydride in the ring closing step; a similar mechanism is proposed for the ring opening in the reaction of [Ir(P–C)(cod)L] with halogen acids HX (X = Cl, Br, or I) to give [IrHX2(cod)L].

Evidence for an anionic intermediate in the mechanistic pathway of the oxidative addition reaction of [(cyclo-octadiene)IrCl(PEtPh2)] with hydrochloric acid

[(cod)IrCl(PEtPh2)] reacts with HCl to form the oxidative addition product [(cod)IrHCl2(PEtPh2)]via the intermediate [(cod)IrCl2(PEtPh2)]–(cod = cyclo-octadiene).