Allenylidene Complexes Research Articles

The highly reactive thiolate-bridged diruthenium complex [Cp*Ru(.mu.2-Cl)(.mu.2-SPri)2RuCp*][OTf]: its reactions with alkynes to form dinuclear metallacycles and terminal allenylidene complexes

The highly reactive thiolate-bridged diruthenium complex [Cp*Ru(.mu.2-Cl)(.mu.2-SPri)2RuCp*][OTf]: its reactions with alkynes to form dinuclear metallacycles and terminal allenylidene complexes

Vinylidene Transition Metal Complexes, XXII[1]. – Alkyne, Alkynyl(hydrido)1‐, Vinylidene‐, and Vinylvinylidene Complexes of Rhodium from OH‐, NH2‐, and Cl‐Functionalized Alkynes

AbstractThe reaction of [RhCl(PiPr3)2]n with γ1‐functionalized 1‐alkynes HCC‐CRR′X (XOH, OMe, Cl, NH2) at room temperature leads to the formation of either alkyne‐, alkynyl(hydrido)1‐, or vinylidenerhodium complexes. The alkyne and alkynyl‐(hydrido) derivatives rearrange thermally or in the presence of deactivated Al2O3 to the isomeric vinylidenerhodium compounds in almost quantitative yield. On treatment of the γ1‐functionalized vinylidenerhodium complexes trans‐[RhCl(CCH‐CRR′X)(PiPr3)2] with Al2O3 or traces of acids, elimination of HX occurs and (for RH, CH3; R′CH3; XOH, Cl, NH2) the (vinylvinylidene)rhodium compounds trans‐[RhCl(CCH‐CRCH2)(PiPr3)2] are formed. In contrast, the reaction of trans‐[RhCl(CCHCPh2OH)(PiPr3)2] with either Al2O3 or acid gives the allenylidene complex trans‐[RhCl(CCCPh2)(PiPr3)2]. The 1‐hexyne derivatives HCC[CH2]3CH2X (XOH, Cl) react with [RhCl(PiPr3)2]n to give alkyne‐, alkynyl(hydrido)1‐, and vinylidenerhodium compounds; attempts to form the cyclic vinylidene complex trans‐ by HX elimination from trans‐[RhCl(CCCH[CH2]3CH2X)(PiPr3)2] (XOH, Cl) failed. The half‐sandwich‐type (vinylvinylidene)rhodium compounds [C5H5Rh(CCH‐CRCH2)(PiPr3)] (RH, Me) are obtained from [RhH(CC‐CRCH2)Cl(py)(PiPr3)2] and NaC5H5.

A novel CC bond cleavage in hexacarbonyl(hexapentaene)diiron: X-ray crystal structure of a bis(µ3,η2-allenylidene)–iron complex

Aryl-substituted hexacarbonyl(hexapentaene)diiron complexes undergo facile intramolecular CC bond cleavage on treatment with [Fe3(CO)12] to yield the corresponding bis(µ3,η2-allenylidene)–iron complexes; the X-ray crystal structures of phenyl-substituted bis(µ3,η2-allenylidene)–iron and related allenylidene complexes are determined.

Metallacumulenes: preparation of novel alkenyl–allenylidene– and diynyl–ruthenium complexes. Crystal structure of a Ru–CC–CC–C(OSiMe3)Ph2derivative

Complexes (η6-arene)(PR3)RuCl21 react with HCC–CC–CPh2OX derivatives (X = H, SiMe3) to afford, in alcohol or in the presence of HNPh2, 3-alkenyl allenylidene complexes [(η6-arene)(PR3)ClRuCCC(Y)CHCPh2]+(Y = OEt 4a, OPri5a, NPh26) and diynyl–ruthenium derivatives in the presence of HNPri2.

Alkyne Complexes of Rhenium in Intermediate Oxidation States; Synthesis and Molecular Structure of a Rhenium(V)‐Allenylidene Complex

Alkyne Complexes of Rhenium in Intermediate Oxidation States; Synthesis and Molecular Structure of a Rhenium(<scp>V</scp>)‐Allenylidene Complex

Regioselectivity in the reactions of dimolybdenum and ditungsten σ,η2(4e)-allenylidene complexes with nucleophilic and electrophilic reagents; crystal structure and dynamic behaviour of the cationic complex [W2(η-HC2CMe2)(CO)4(η-C5H5)2][BF4

Reaction of the σ,η2(4e)-allenylidene complexes [M2(σ,η2-CCCMe2)(CO)4(η-C5H5)2](M = Mo or W) with K[BHBus3] or HBF4·Et2O results in attack on the γ- or the α-carbon atom forming [M2(σ,η2-CCPri)(CO)4(η-C5H5)2]– and [M2(µ-HC2CMe2)(CO)4(η-C5H5)2]+, respectively; the X-ray crystal structure and solution dynamic behaviour of the cations are discussed in relation to the species [Co3(CCH2)(CO)9]+, and it is shown that the Mo2 cation undergoes an unusual fragmentation reaction on treatment with ButLi.

New pathway for the synthesis of manganese allenylidene complexes

New pathway for the synthesis of manganese allenylidene complexes

Dialkylallenylidenekomplexe mit Pentacarbonylfragmenten der VIb Metalle/Dialkylallenylidene Complexes with Pentacarbonyl Fragments of VI b Metals

Abstract In the context of the synthesis of allenylidene compounds, the reaction of methylpropiolate with a (OC)5CrO(C2H5)2 complex was investigated. The species pentacarbonyl- (methylpropiolate)chromium(0) (1), 2,4-bis(methoxycarbonyl)-cyclobut-2-en-1-yliden-1- pentacarbonylchromium(0) (2) and cis-2,4-dimethoxycarbonyl-1,3-butadien-1 -yliden-1 - pentacarbonylchromium (3) were isolated. Attempts to synthesize allenylidene complexes from 1 were unsuccessful. Di-iso-propyl or di-tert-butylallenylidene complexes with chromium or tungsten centers (4a, 4b, 5a, 5b) were finally obtained by the photochemical reaction of pentacarbonylpropargylates, (OC)5MC(O)C ≡ CCR2O2-, M = Cr, W, and subsequent desoxygenation. The complexes 4 a, b were characterized as triphenylphosphane adducts, di-iso-propylallenylidenetriphenylphosphorane complexes (6a und 6b). The structure of 6 a was determined by X-ray methods.

Synthese allenylidenverbrückter [CpMn(CO) 2] 2-komplexe

Diorganoallenylidene compounds of the [CpMn(CO) 2] 2 fragments are described, which are obtained by the reaction of monomeric CpMn(CO) 2-allenylidene complexes with the CpMn(CO) 2O(C 2H 5) 2 reagents.