1,1-Enediamines as highly polarized olefin ligands

1,1-Enediamines were prepared by reaction of N,N-dimethylacetamide dimethyl acetal, Me2NC(OMe)2CH3, with the cyclic amines piperidine, homopiperidine, and morpholine. The resulting unsymmet-ric 1-morpholino-1-(dimethylamino)ethene ( 1 ) and the symmetric 1,1-dipiperidinoethene ( 2a ), 1,1-dihomopiperidinoethene ( 2b ) and 1,1-dimorpholinoethene ( 2c ) were reacted with [(THT)AuCl] (THT = tetrahydrothiophene), trans-PdCl2(NCPh)2 and B(C6F5)3, respectively, to afford a series of gold, palladium, and boron complexes 3a-f . The new complexes were fully characterized by NMR spec-troscopy and X-ray diffraction analysis, revealing their analogy with N-heterocyclic olefins (NHO) by eta 1-coordination through highly polarized C -C double bonds. Chloride abstraction from (1,1-dimorpholinoethene)gold(I)-chloride ( 3c ) with AgPF6 in presence of another equivalent of free lig-and afforded bis(1,1-dimorpholinoethene)gold(I)-hexafluorophosphate ( 4 ) as the first homoleptic bis(1,1-enediamine) metal complex.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a series of 1,1-enediamines were synthesized and transformed into corresponding complexes with gold, palladium, and boron ligands. The new complexes were fully characterized by NMR spectroscopy and X-ray diffraction analysis, revealing their similarities to N-heterocyclic olefins in terms of structural features.