Synthesis and reactivity of molybdenum imido alkylidene bis-pyrazolide complexes.

Reaction of Li(3,5-R(2)-pyrazolide) (R = tBu or Ph, dXpz) with Mo(NAr)(CHCMe(2)Ph)(OTf)(2)(DME) yields Mo(NAr)(CHCMe(2)Ph)(dXpz)(2) in good yield. These complexes react with alcohols or the surface silanols of silica, to yield bis-alkoxy and surface mono-siloxy alkene metathesis catalysts, respectively.

Molybdenum tris(2,5-dimethylpyrrolide), a rare homoleptic molybdenum(III) monomer.

The monomeric, homoleptic molybdenum(III) complex molybdenum tris(2,5-dimethylpyrrolide) has been prepared. Reduction with KC 8 in THF yields the molybdenum(II) complex potassium [molybdenum tris(2,5-dimethylpyrrolide)], while protonation with [H(OEt 2) 2][BAr (F) 4] yields a cationic species that contains an eta (1)-3 H-pyrrole ligand.

A tungstenVI nitride having a W2(mu-N)2 core.

The tungsten nitrido species, [W(mu-N)(CH2-t-Bu)(OAr)2]2 (Ar = 2,6-diisopropylphenyl), has been prepared in a reaction between the alkylidyne species, W(C-t-Bu)(CH2-t-Bu)(OAr)2, and organonitriles. The dimeric nature of the nitride was established in the solid state through an X-ray study and in solution through a combination of 15N NMR spectroscopy and vibrational spectroscopy. Reaction of the nitride with trimethylsilyl trifluoromethanesulfonate afforded the monomeric trimethylsilyl imido species, W(NSiMe3)(CH2-t-Bu)(OAr)2(OSO2CF3), which was also characterized crystallographically.

Tris(pyrrolyl-alpha-methyl)amines that sterically protect a trigonal metal site.

Three substituted tris(pyrrolyl-alpha-methyl)amines (H(3)[Aryl(3)TPA]) (Aryl = 2,4,6-C(6)H(2)Me(3), 2,4,6-C(6)H(2)(i-Pr)(3) (Trip), or 3,5-C(6)H(3)(CF(3))(2)) have been prepared. An X-ray study of [Trip(3)TPA]MoCl shows it to be a distorted trigonal bipyramidal species in which the 2,4,6-triisopropylphenyl substituents surround and protect the apical chloride. Attempts to prepare other Mo, Zr, and Hf complexes yielded species in which one pyrrole-containing arm remained free (Mo) or dimethylamine remained in the coordination sphere of [Aryl(3)TPA](3-) complexes (Zr, Hf).