Early transition-metal carbene complexes L2M:CH2---equilibrium structures and rotational barriers

Theoretical Studies on the Decomposition Mechanism of Tetraalkyl Titanium Complexes

“…The alkylidene product 3 is slightly pyramidalized at the Ti atom (C 1 symmetry) with the 3-21G basis set, but is “planar” with C 2 v symmetry with the HW3 basis set, in agreement with the results of previous calculation on titanium alkylidene analogues . The two methyls favor a staggered conformation with respect to the TiCH 2 bond.…”

An Infrared Spectroscopic and Theoretical Study of Group 4 Transition Metal CH2MCl2 and HC÷MCl3 Complexes

“…Although α-H transfer may be faster than α-Cl transfer, the latter is much more favorable energetically. The CH 2 TiCl 2 complex has been studied theoretically over the last two decades; − however, this is the first experimental observation to our knowledge.…”

1,n-Dicarbanionic Titanium Intermediates from Monocarbanionic Organometallics and Their Application in Organic Synthesis

“…The intermediate 3 has not been isolated as a pure compound; however, its phosphine complexes are known and have been characterized spectroscopically. − In accordance with theoretical considerations, the methylenetitanocene 3 is a 16-electron species with an empty orbital on titanium lying in the plane bisecting the Cp−Ti−Cp bond angle. Any ligand with unpaired electrons, such as a carbonyl group, may coordinate. − The carbonyl olefinations with the Tebbe reagent 2 have been reviewed extensively. , The reaction of 2 with cyclohexanone, for example, in toluene solution proceeds at −15 °C to room temperature to produce methylenecyclohexane in 65% yield . Since the Wittig methylenation can only be applied to aldehydes and ketones, it is a particular advantage of Tebbe's reagent 2 that it also smoothly reacts with carboxylic acid derivatives such as esters and lactones.…”