Alkyne coupling reactions mediated by organolanthanides. Probing the mechanism by metal and alkyne variation

Journal Article · Wed Sep 01 04:00:00 EDT 1993 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00033a038· OSTI ID:5526396

Forsyth, C M; Nolan, S P; Stern, C L; Marks, T J ^[1]; Rheingold, A L ^[2]

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1. Northwestern Univ., Evanston, IL (United States)
2. Univ. of Delaware, Newark, DE (United States)

This contribution addresses, using the non-redox-active ion La[sup 3+], the constraints under which lanthanide M-C[triple bond]CR functionalities undergo facile coupling to yield binuclear M[sub 2]([mu]-RC[sub 4]R) complexes. The reaction of Cp[prime][sub 2]LaCHTMS[sub 2] (Cp[prime] = [eta][sup 5]-Me[sub 5]C[sub 5]) with PhCCH at room temperature yields the coupled product (Cp[prime][sub 2]La)[sub 2]([mu]-PhC[sub 4]Ph) (monoclinic space group C2/m, [alpha] = 15,600(2) A, b = 14.318 (2) A, c = 15.368(2) A, [beta] = 114.17(1)[degrees], Z = 2, R = 0.050, R[sub w] = 0.063) plus CH[sub 2]TMS[sub 2]. Reaction of Cp[prime][sub 2]LaCHTMS[sub 2] with t-BuCCH at 0[degrees]C, yields the uncoupled dimer (Cp[prime][sub 2]LaC[sub 2]-t-Bu)[sub 2] (plus CH[sub 2]TMS[sub 2]), which, in toluene solution at 50 and 60[degrees]C, undergoes clean unimolecular conversion to the coupled dimer (Cp[prime][sub 2]La)[sub 2]([mu]-t-BuC[sub 4]-t-Bu) (monoclinic space group P2[sub 1]/n, a = 11.232(2) A, b = 14.199(3) A, c = 15.309(4) A, [beta] = 103.35(2)[degrees], Z = 2, R = 0.027, R[sub w] = 0.034). These results argue that excursions in formal metal oxidation state (+3 = +2) are not important along the reaction coordinate, that acetylene aryl substituents are not necessary for the coupling process to occur, and that the immediate kinetic precursor to the coupled product is an uncoupled dimer. 18 refs., 3 figs., 4 tabs.

• OSTI ID: 5526396
• Journal Information: Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 12:9; ISSN ORGND7; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKYNES
CATALYSTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
COUPLING
DIMERS
HYDROCARBONS
KINETICS
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
RARE EARTH COMPLEXES
REACTION KINETICS