Supramolecular Ammine‐Copper rac ‐BINOLAT Salts through in‐situ R ‐ or S ‐BINOL Racemization

The molecule rac ‐1,1'‐binaphthalene‐2,2'‐diol ( rac ‐1,1'‐bi‐2‐naphthol, rac ‐BINOL) shows a propensity for supramolecular, charge‐assisted O–H ··· O – hydrogen‐bonded strand formation when crystallized with its deprotonated form BINOLAT 2– and Cu 2+ in conc. ammonia. The naphthyl‐paneled cavities in the {( rac ‐BINOLAT 2– )( rac ‐BINOL) 2 } strands host the [Cu(NH 3 ) 5 ] 2+ ‐guest cation through second‐sphere N–H ··· O hydrogen bonding in the structure of [Cu(NH 3 ) 5 ] 2+ ( rac ‐BINOLAT 2– )( rac ‐BINOL) 2 . Decreasing the copper(II) and ammonia concentrations in the crystallization leads to {( rac ‐BINOLAT 2– )( rac ‐BINOL)} strands, in which rac ‐BINOLAT 2– coordinates to two copper(II) atoms in the structure of [Cu(NH 3 ) 2 (μ‐ rac ‐BINOLAT 2– ‐κ 2 O,O' :κ O )] 2 ( rac ‐BINOL) 2 . In the {Cu 2+ (NH 3 ) 2 } moiety two BINOLAT‐oxide atoms act as bridging ligands. Both copper structures could be obtained by using the racemic rac ‐BINOL or the enantiomeric R ‐ or S ‐BINOL, through an in‐situ racemization of the latter.