Atom efficient cyclotrimerization of dimethylcyanamide catalyzed by aluminium amide: a combined experimental and theoretical investigation

Abstract

A novel method for the cyclotrimerization of dimethylcyanamide to form hexamethylmelamine has been developed using an aluminium amide catalyst; detailed DFT modelling of the catalytic cycle supports a triple insertion, nucleophilic ring closure, deinsertion mechanism.

Impact of the Nature of the Organic Spacer on the Crystallization Kinetics of UiO‐66(Zr)‐Type MOFs

“…The formation of the acyclic trimer 4 is unique because trimerization of nitriles usually gives cyclic triazines 3. 17 It is clearly the specific cooperative influence of Lewis pair 1 which favors the chain oligomerization over cyclization. Oligomers were not obtained with AlR 3 derivatives (R= t Bu, i Bu), which afford simple adducts instead, for example, t Bu 3 Al←NC‐N(CH 2 CH 2 ) 2 O.…”

“…In conclusion, in an unprecedented reaction Lewis pair 1 catalyzes selectively the oligomerization of cyanamides and the assembly of chains of alternating nitrogen and carbon atoms. The formation of the thermodynamically strongly favored cyclic trimer is suppressed 17. Separation of the mixtures and isolation of specific oligomers will allow the detailed study of their physical properties, in particular of their redox behavior.…”

Ein Al‐N‐basiertes Lewis‐Paar als effektiver Katalysator für die Oligomerisierung von Cyanamiden – Bildung von acyclischen C‐N‐Oligomeren anstelle von thermodynamisch begünstigten cyclischen Trimeren

“…[4a] Die NC-N-Gruppe ist nahezu linear [174.5(1)8], die übrigen Winkel der Kette variieren zwischen 117.50(9) und 126.12(9)8. Die Bildung des acyclischen Trimers 4 ist einzigartig, da Nitrile bevorzugt cyclische Triazine ergeben, [3,17] .…”

Hybrid amidinates and guanidinates of main group metals

“…[19] Page 4 of 32 A c c e p t e d M a n u s c r i p t 4 Scheme 2: Main reaction pathways for preparation of amidinate metal complexes Scheme 3: One of special cases of reactions leading to amidines Analogously to the described reaction pathways for synthesis of metal amidinates (Scheme 2), various guanidinates can be prepared according to the Scheme 4. In contrast to amidinates, for synthesis of guanidinates, having one more nitrogen atom participating in the central skeleton, it is necessary to use aminonitriles [20] or metal amides [21] instead of simple nitriles or organometallic species. Moreover the deprotonation of remaining N-H group yields guanidinates (2- Another two subjects are the variations of the ordinary silyl-, chain or cyclic both saturated or unsaturated organic groups to the group functionalized by an adjacent donor group, or a group which can be deprotonated and thus a dianionic usually tridentate ligand system can be formed.…”