Preparation of copper(I) binap-P2N2 complexes; crystal and molecular structure of [Cu(Binap-P2N2)Br]

The interaction of a racemic mixture of N,N′-bis[o-(diphenylphosphino)benzylidene-2,2′-diimino-1,1′-binaphthyl (Binap-P2N2) (I) with 1 equivalent of Cu(Ph3P)2Br and [Cu(CH3CN)4]PF6in CH2Cl2gave Cu(Binap-P2N2)Br (II) and [Cu(Binap-P2N2)]PF6(III) in 60 and 74% yield, respectively. The structure of II was established by X-ray diffraction and can be described as distorted tetrahedral with the bromide ion and the two phosphino groups and one of the two imino groups of I coordinated to the copper. Variable temperature31P {1H} NMR study of II shows that the coordinated and the uncoordinated imino groups of the tridentate Binap-P2N2ligand undergo a facile intramolecular exchange even at -55°C.