Reaction of Thermally Generated (η²‐Aryne)zirconocene with W(CO)₆, a Novel Route to Carbene Complexes

Abstract

= 1.39 g cm-'. Nicolet R3m diffractometer, w-scan, graphite-monochromated CuKe radiation. Both structures were solved by direct methods and refined anisotropically to give R =0.166 (R,=0.166) and R=0.082 (R,=0.083), respectively, for 2693 and 4225 independent observed reflections [8550", lFol > 3u(lF01)]. The high R value for 7 is a consequence of disorder in the polyether chains and also reflects the presence of disordered solvent fragments in the lattice. Further details of the crystal structure investigations can be obtained from the Director of Cambridge CryStallOgrdphic Data Centre, Lensfield Road, Cambridge CB2 IEW (England), by quoting the full literature citation.

Insertion Chemistry of Lutetacyclopropene toward Unsaturated C−O/C−N Bonds

“…2 and 3 were both characterized by elemental analysis and NMR spectroscopy. In the 13 C NMR spectra, the two low-field resonances (δ = 148.34 and 196.72 ppm for 2, δ = 148.33 and 199.06 ppm for 3) and a high-field resonance (δ = 83.22 for 2 and δ = 81.43 ppm for 3) for the carbon atoms in the five-membered rings are consistent with the lutetadihydrofuran structures of 2 and 3. In the 1 H NMR spectrum of 3, the CH moiety exhibits a singlet at 6.32 ppm, which is significantly upshifted compared with the original formyl group.…”

“…This WÀ C distance is comparable with that of the reported zirconium-oxycarbenetungsten complex. [13,14] In 5, the C1À O1 distance of 1.263(6) Å is considerably shorter than the normal CÀ O single bond distance, while the LuÀ O distance of 2.237(3) Å is quite longer than the LuÀ O σ bond lengths in 2 (2.085(3) Å) and 3 (2.110(3) Å). These observations indicate a remarkable metal acyl character of 5, emphasizing the important contribution from the zwitterionic resonance structure B.…”

“…[15] As far as we are aware, 5 is the first rare-earth metallacyclic oxycarbene complex, although the analogous metallacyclic carbene moieties have been reported for Ti, Zr, and Th. [13][14][15][16] Besides CÀ O unsaturated bonds, the reactions between C=N bonds and 1 were also investigated. The reaction of 1 with N-phenylbenzylimine (PhCHNPh) was carried out to provide a five-membered lutetacycle 6 (Scheme 3b).…”

The hydrolysis of (π-C6H6)Cr(π-C6F5CO2C2H5): an unexpected decarboxylation

“…In these latter molecules the ligand functions as a cycloalkyne rather than as an aryne. Recently, however, it has been shown that a benzyne-zirconocene adduct has a transient existence (23) and can be used in synthesis (24).…”

Synthesis and structural characterization of [(C5H4)SiMe2(N-t-Bu)]Ti[(o-C6H4)C(Ph)C(Ph)], generated via an alkyne-Ti benzyne coupling reaction

“…Subsequent reactivity studies revealed that this Zr-aryne intermediate is capable of reductive coupling with olefins to form zirconaindan derivatives (Eq. (3)) [5] and reacting with W(CO) 6 to afford a Fischertype zirconaoxycarbene complex (Eq. (4) …”