Dynamics Solution NMR Studies

Templeton demonstrated that the two isomers of [W(CO)(dppe)(dtc) (T7 -MeOC=C=CHPh)] interconvert (Tc —120°) on the NMR time scale. Molecular orbital (MO) calculations on the model complex [WH4(CO)(i7 -H0C=C=CH2)] provided the rotational profile shown in Fig. 2 characterized by a low barrier to rotation of the allenyl fragment with respect to the metal (rotation about the z axis) and a higher barrier for rotation about the Cp-Cy double bond. The former process possesses two energy minima 

Rapid rotation of the allenyl fragment in [MoCp P(OMe)3 T)--C(Ph)C=CHPh ] was reported earlier by Green and co-workers (/5). The observation of two AB quartets in the low-temperature P NMR spectrum of 10 was attributed to isomers 10a and 10b which differ by virtue of 

Roialional profile for the model complex WH4(CO)It) -H()C=C=CH ) (see lexl). Adapied from Gamble et ut. U6ci). 

Unusual ligand dynamics in the modified allenyl cluster [Ru,H(CO)i (ju.-i7, rj, 7 --Me2NC=C=CHaHb)] (99) were described by Aime ef al. (56b). 

Simple o--7r-vinyl type motion as shown for [OsiHrrm t i  

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