REACTIONS OF VINYL AMIDO LIGANDS IN TP'(CO)(2)W[N(R')CH=CHR] COMPLEXES PREPARED FROM ADDITION OF PRIMARY AMINES TO COORDINATED ALKYNES

Reaction of [Tp'(CO)(2)W(RC=CH)I[BF4] with NH(2)R' generates neutral complexes of the type Tp'(CO)(2)W[N(R')CH-CHR] (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate, R = Ph, R' = Ph (1a), Bu(t) (1b), CH(2)Ph (1c), Bu(n) (1d); R = Bu(t), R' = CH(2)Ph (1e); R = Bu(n), R' = CH(2)Ph (1f, 1f', 1f '')). Donation of the lone pair of electrons on the nitrogen of the amido ligand to the tungsten center is reflected by the low IR stretching frequencies of the carbonyl ligands and their downfield carbon resonance in the C-13 NMR. NMR spectra and an X-ray structure of Tp'(CO)(2)W[N(CH(2)Ph)CH=CHPh] (1c) indicate that the planar vinyl group of the amido ligand lies on the molecular mirror plane. Complex 1c crystallized in the monoclinic space group <P(1)over bar> with unit cell dimensions of a = 12.497(5), b = 13.414(5), c = 10.992(5) Angstrom, and alpha = 111.94(3)degrees, beta = 91.47(4)degrees, and gamma = 72.60(3)degrees with Z = 2. Refinement of 389 variables over 4632 reflections led to R = 4.0% and R(w) = 4.5%. The short W-N distance of 1.997(5) Angstrom indicates a W-N double bond. As in related amido complexes, an acute OC-W-CO angle was found in the solid state. Reaction of the vinyl amido complex 1c with [Ph(3)C][BF4] produces a cationic vinyl nitrene complex, [Tp'(CO)(2)W=N(CH=CHPh)][BF4] (2). Reaction of [Tp'(CO)(2)W=N(CH=CHPh)][BF4] (2) with LiBH4 adds hydride to the terminal vinyl site and generates a neutral azavinylidene complex, Tp'(CO)(2)WN=CHCH2-Ph (3). Protonation of the azavinylidene complex 3 occurs at the carbon atom beta to the metal to produce a cationic nitrene complex, [Tp'(CO)(2)W=N(CH(2)CH(2)Ph)][BF4] (4), with the saturated substituent on the nitrogen reflecting sequential H-, H+ addition to the vinyl tail of [Tp'(CO)(2)W=N(CH=CHPh)][BF4]