Synthesis and crystal structures of complexes of Ni (II) to chiral Schiff bases of (R)- and (S)-serine with (S)- and (R)-2-N-(N′-benzylprolyl)-aminobenzophenone

The three-dimensional molecular and crystal structures of a pair of enantiopure mirror complexes of Ni (II) to chiral Schiff bases of (R)- and (S)-serine with (S)- and (R)-2-N-(N′-benzylprolyl)-aminobenzophenone (BPB), denoted as (S,R)-BPB-Ser-Ni and (R,S)-BPB-Ser-Ni, respectively, have been determined by X-ray diffraction. The complexes crystallize in the orthorhombic space group P212121 with unit cell parameters: a = 10.050(2) Å, b = 10.100(2) Å, c = 26.514(5) Å, V = 2691.3(9) Å3, and Z = 4 for (S,R)-BPB-Ser-Ni; and a = 9.878(2) Å, b = 10.130(2) Å, c = 26.304(5) Å, V = 2632.1(9) Å3, and Z = 4 for (R,S)-BPB-Ser-Ni. The Ni atom is square-planar-coordinated to N(1), N(2), O(4), and N(3) of the Schiff base with minor distortion. The hydroxymethyl group on the serine moiety is axial to the coordination plane and parallel to the neighboring phenyl group.