Coordination Behavior of N , N′ ‐Bis(diisopropylphosphinoacetyl)‐ o ‐phenylenediamide with Ni II and Cu I Ions

The reaction of N , N′ ‐bis(diisopropylphosphoniumacetyl)‐ o ‐phenylenediamide dibromide (H 4 L · 2Br) with Ni II [ClO 4 ] · 6H 2 O in the presence of Et 3 N resulted in the formation of N , N′ ‐bis(diisopropylphosphinoacetyl)‐ o ‐phenylenediamidate nickel(II) ([Ni II (L)]). The single‐crystal X‐ray diffraction analysis of [Ni II (L)] revealed that each pair of N and P atoms in L 2– coordinates in a tetradentate fashion to afford a distorted square‐planar Ni II amide complex. On the other hand, N , N′ ‐bis(diisopropylphosphinoacetyl)‐ o ‐phenylenediamide copper(I) bromide ([Cu I (H 2 L)Br]) was isolated by the reaction of H 4 L · 2Br with [Cu I (MeCN) 4 ][PF 6 ] in the presence of Et 3 N. The structural analysis revealed that the two P atoms in H 2 L coordinate in a bidentate fashion to afford a trigonal‐planar Cu I complex, in which the amide moieties remain in free form. Complex [Ni II (L)] showed reversible deprotonation processes on the amidate ligand (L 2– ), whereas the protonated state of the N atoms of the amide ligand (H 2 L) in [Cu I (H 2 L)Br] was maintained, even in the presence of excess Et 3 N, suggesting substantial stability for the protonated state.