Bis(amino)allenylidene complexes by displacement of the MeO group in methoxy allenylidene complexes of chromium and tungsten. Synthesis, DFT calculations and solid-state structures of new bis(amino)allenylidene complexes

Neutral Ruthenium Carbene Complexes bearing N,N,O Heteroscorpionate Ligands: Syntheses and Activity in Metathesis Reactions

“…In both cases the calculations show a smaller coefficient for the α carbon atom compared to the γ carbon atom. This would mean that weak nucleophiles might attack in γ position, as observed in the case of the chromium complex [Cr(CCC(OMe)NMe 2 )(CO) 5 ] for the reaction with NH 3 . But a rearrangement to the α adduct might also occur, as reported for the rhenium complex [Re(CCCPh 2 )(CO) 2 (triphos)][OTf] after γ addition of ammonia …”

Amino-Substituted Butatrienes: Unusual η1 Ligands Formed by an Unusual Reaction

“…Dimethyldiazomethane, diethyldiazomethane, di- n -propyldiazomethane, 1,3-dimethylimidazolin-2-ylidene, 1,3-dimesitylimidazolin-2-ylidene, and the complexes 1 , 6a , 6b , 7a , 8b, 16 , and 18 were prepared according to literature procedures. Complex 4 was synthesized by γ,γ double substitution from 6b and ethylenediamine, as described in ref . HgO (yellow, Fluka), 3-pentanone (Acros), and 4-heptanone (Aldrich) were commercial products and were used without further purification.…”

“…7,8 Finally, γ,γ addition yields, by double substitution, new allenylidene complexes C γ now being part of a heterocycle. 4,5 Dipolar substrates such as ynamines or imines, e.g. i PrNdC(H)Ph, add either to the C R -C β bond, giving isolable cyclic carbene complexes, 9 or to the C β -C γ bond, yielding initially new vinylidene complexes, C β of the vinylidene ligand being part of a cyclobutene ring.…”

“…The addition of protic nucleophiles HX to the C α atom is usually followed by formation of vinylcarbene complexes . The addition of HX to the C γ atom to form alkynyl complexes can be succeeded by substitution of X for one or both C γ substituents. − The reaction of allenylidene complexes with diprotic dinucleophiles will lead to different products, depending on the initial site of attack (Scheme ). The α,γ sequence gives, via vinylcarbene complexes, new carbene complexes containing a saturated cyclic carbene ligand, whereas the γ,α sequence affords, via initial substitution, complexes with an unsaturated carbene ligand. , Finally, γ,γ addition yields, by double substitution, new allenylidene complexes C γ now being part of a heterocycle. , …”

“…The addition of HX to the C γ atom to form alkynyl complexes can be succeeded by substitution of X for one or both C γ substituents. − The reaction of allenylidene complexes with diprotic dinucleophiles will lead to different products, depending on the initial site of attack (Scheme ). The α,γ sequence gives, via vinylcarbene complexes, new carbene complexes containing a saturated cyclic carbene ligand, whereas the γ,α sequence affords, via initial substitution, complexes with an unsaturated carbene ligand. , Finally, γ,γ addition yields, by double substitution, new allenylidene complexes C γ now being part of a heterocycle. , …”