Synthesis and crystal structures of the first C2-symmetric bis-aldimine NCN–pincer complexes of platinum and palladium

(S,S)-2,6-bis[(N-α-methylbenzyl)imino]phenylpalladium bromide was synthesised by oxidative addition of palladium(0) to (S,S)-1-bromo-2,6-bis[(N-α-methylbenzyl)imino]benzene. In contrast, (S,S)-2,6-bis[(N-α-methylbenzyl)imino]phenylplatinum chloride was synthesised by direct C–H activation from the reaction of potassium tetrachloroplatinate with (S,S)-1,3-bis[(N-α-methylbenzyl)imino]benzene. The X-ray crystal structures of both pincer complexes were obtained. Treatment of both complexes with silver hexafluoroanimonate gave effective but not stereoselective catalysts for a Michael reaction between methyl vinyl ketone and methyl 2-cyanopropanoate.

Graphical abstractC2-symmetric (S)-α-methylbenzylamine derived bis-aldimine pincer complexes of platinum(II) and palladium(II) were synthesised and fully characterised. X-ray diffraction crystallographic structures and computational analysis were correlated to the stereochemical outcome of a pincer catalysed reaction of Michael reaction between methyl 2-cyanopropanoate and methyl vinyl ketone.Figure optionsDownload full-size imageDownload as PowerPoint slide