Correlation among crystal shape, absolute configuration, and circular dichroism spectrum of enantiomorphs of tris[2-(((2-phenylimidazol-4-yl)methylidene)amino)ethyl]-aminemetal(II) nitrate-methanol (1/1)

A series of metal(III) complexes of a tripod-type ligand with the chemical formulas [M(H3L)](NO3)(2). MeOH (M = Mn (1), Fe (2), Co (3), Ni (4), Zn (6) ) and [Cu(H3L)](NO3)(2). CH3CN .H2O (5) were synthesized and characterized (H3L = tris [2-(((2-phenylimidazol-4-yl)methylidene)amino)ethyl]amine). The crystal structures were determined, in which those of 1-4 and 6 are isomor phous and conglomerates, because they crystallize into the acentric space g roup P2(1)2(1)2(1). Each metal(II) ion of 1-4 and 6 assumes an octahedral c oordination environment with the N-6 donor atoms of the tripod ligand and b ecomes either a C (clockwise) or an A (anticlockwise) enantiomorph because of the screw arrangement of the tripod-type ligand around the metal(II) ion . The crystals were divided into two groups, where their crystal shapes are mirror images and their CD spectra show enantiomeric patterns. The circula r dichroism (CD) spectrum of the crystal used for the X-ray analysis was me asured. The absolute configuration of the enantiomorph of the crystal used for the X-ray analysis was determined by the Flack parameter. The correlati on among the crystal shape, the absolute configuration, and the CD spectral pattern was thus confirmed for 1-4 and 6. On the other hand, 5 assumes a s quare pyramidal coordination geometry with the Ns donor atoms, and hence, t here are no optical isomers.