No abstract

No abstract

Rearrangement of the W(0) d6 ^-alkyne complex /ac-(dppe)(OC)3W(j/2-PhC=CH) (dppe = Ph2PCH2CH2PPh2) yields a meridional tricarbonyl tungsten vinylidene complex, zner-(dppe) (OC)3W=C=CHPh, which provides an M-C-C framework for further ligand-based transformations. Electrophilic addition at the 0-carbon of the vinylidene ligand generates a cationic tungsten carbyne, [wr-(dppe)(OC)3W5=CCH2Ph] [BF4]. This carbyne cation undergoes carbon monoxide substitution

No abstract

260ChemInform Abstract Substitution of acetone in the fac-W(0) complex (I) by the terminal alkynes (II) leads to the alkyne adducts (III). Chemical and spectroscopic properties indicate that the alkyne ligand is weakly bound in these labile octahedral d6 monomers. The phenylacetylene adduct (R: Ph) isomerizes cleanly to the vinylidene derivative mer-W(CO)3(Ph2PCH2CH2PPh2)(=C=CHPh). Internal alkyl and aryl alkynes do notyield clean products under similar conditions, but the electron poor ester substituted alkyne (IV) (DMAC) forms the bis-alkyne complex (V). A single-crystal X-ray study of this complex (space group P1, Z=2) confirms the trans alkyne-cis dicarbonyl geometry anticipated from spectroscopic data.

In this laboratory experiment students synthesize a precatalyst, [Ni(P(OEt)3)4]. The precatalyst is protonated insitu to make [HNi(P(OEt)3)4]+, a nickel hydride, which is an active catalyst for alkene isomerization. Students produce the nickel hydride in the presence of 1-heptene at 0 ° C and monitor the extent of heptene isomerization by gas chromatography as a function of time. Students use this data to assess the effectiveness of their catalyst. The catalytic mechanism involves common reactions in organometallic chemistry such as: ß-hydride elimination and alkene insertion. This experiment combines synthetic and physical techniques to introduce students to synthetic and mechanistic organometallic chemistry.

No abstract

Organometallics 1986, 5, 94-98 distance is considerably longer, at 3.155 (10) A as would be expected for a Lewis acid-base interaction.indicate that a large number of bimetallic complexes can be successfullv DreDared. " _ -Acknowledgment. This work was performed under the auspices of the u.s. Department of Energy and, in part, under the auspices of the Division of Chemical Energy Sciences, Office of Basic Energy Sciences, u.s. Department of Energy.The chemistry of the Cp*,Th(PR& complexes and other actinide analogues, in combination with a number of late-transition-metal fragments, is currently under investigation in our laboratory. Preliminary results, including the preparation of the above-mentioned nickel complex, Registry No.