Preparation of chiral diimino- and diaminodiphosphine ligands and their Cu-I and Ag-I complexes. X-ray crystal structures of [Cu(1S,2S-cyclohexyl-P2N2)][PF6] and [Ag(1R,2R-cyclohexyl-P2N2H4)][BF4]

The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)-tartrate and 1S,2S-diammoniumcyclohexane mono-(-)-tartrate with 2 equiv. of o-(diphenylphosphino)benzaldehyde in the presence of 2 equiv. of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N'-bis[o-(diphenylphosphino) benzylidene]-1R,2R-diiminocyclohexane [1R,2R-cyclohexyl-P2N2, (R,R)-I] and N,N'-bis[o-(diphenylphosphino)benzylidene]-1S,2S-diiminocyclohexane [1S,2S-cyclohexyl-P2N2, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH4 in ethanol gave the optically pure reduced products N,N'-bis[o-(diphenylphosphino) benzylidene]-1R,2R-diaminocyclohexane [1R,2R-cyclohexyl-P2N2H4, (R,R)-II] and N,N'-bis[o-diphenylphosphino)benzylidene]-1S,2S-diaminocyclohexane [1S,2S-cyclohexyl-P2N2H4, (S,S)-II], respectively, in god yield. The coordination behaviour of I and II toward salts of Cu-I and Ag-I have been examined. The interaction of[Cu(CH3CN)(4)][X] (X = ClO4-, PF6-) with 1 equiv. of optically pure L(4)[L(4) = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL(4)][X] complexes, III-VI [IIIa, L(4) =(R,R)-I, X = PF6- IIIb L(4) = (R,R)-I, X = ClO4- IV, L(4) = (S,S)-I, X = PF6-; Va, L(4) = (R,R)-II, X = PF6-, Vb, L(4) = (R,R)-II X = ClO4-, VI, L(4) = (S,S)-II, X = PF6-], in good yield. For the Cu-I complexes, the L(4) ligand acted as a tetradentate ligand. However a variable-temperature P-31 [H-1] NMR study of IIIb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction af AgBF4 with 1 equiv of optically pure L(4) [L(4) = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [AgL(4)][BF4] complexes, VII-X [VII, L(4) = (R,R)-I; VIII, L(4) = (S,S)-I : IX, L(4) = (R,R)-II; X, L(4) = (S,S)-II], in good yield. For the Ag-I complexes, the L(4) ligand acted as a tetradentate ligand with tilt two amino groups coordinated unsymmetrically to the silver. A variable temperature P-31 [H-1] NMR study of VII suggests that al high temperature the complex exists as a tri-coordinated complex. The structures of IV and IX were established by X-ray diffraction studies. Copyright (C) 1996 Elsevier Science Ltd