Syntheses and solid state structures of zinc (II) complexes with Bi-dentate N-(Aryl)imino-acenapthenone (Ar-BIAO) ligands

We have synthesized five zinc complexes of molecular formulae [ZnCl 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1a ), [ZnBr 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1b ), [ZnI 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1c ), [ZnBr 2 (mes-BIAO)] 2 ( 2b) and [ZnBr 2 (dipp-BIAO)] ( 3b) with rigid unsymmetrical iminoacenaphthenone ligands, (2,6-dimethylphenyl-BIAO) ( 1 ), (mesityl-BIAO) ( 2 ) and (2,6-diisopropylphenyl-BIAO) ( 3 ). The zinc complex 1a was prepared by the reaction of ZnCl 2 and neutral (mesityl-BIAO) ( 1 ). However, complexes 1b , 2b and 3b were obtained by the treatment of ZnBr 2 and neutral ligands 1 – 3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI 2 with (2,6-dimethylphenyl-BIAO) ( 1 ) in dichloromethane the corresponding iodo-complex 1c was obtained in good yield. All the zinc (II) complexes are characterized by FT-IR, 1 H and 13 C{ 1 H} NMR spectroscopic techniques. The solid state structures of the complexes 1a , 1b , 1c , 2b and 3b are confirmed by single crystal X-ray diffraction analysis. The molecular structures of complexes 1a , 1b , 1c and 2b reveal the dimeric nature of the complexes and subsequently the centre atom zinc is penta-coordinated to adopt distorted trigonal bipyramidal geometry around it. In contrast, the complex 3b is in monomeric in nature due to bulkier size of the ligand and zinc ion is tetra coordinated to adopt distorted tetrahedral geometry. Graphical Abstract We report five zinc complexes of molecular formulae [ZnCl 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1a ), [ZnBr2(2,6-dimethylphenyl-BIAO)] 2 ( 1b ), [ZnI2(2,6-dimethylphenyl-BIAO)] 2 ( 1c ), [ZnBr2(mes-BIAO)] 2 (2 b ) and [ZnBr2(dipp-BIAO)] (3b) with rigid unsymmetrical iminoacenaphthenone ligands, (2,6-dimethylphenyl-BIAO) ( 1 ), (mesityl-BIAO) ( 2 ) and (2,6-diisopropylphenyl-BIAO) ( 3 ). The solid state structures of all the zinc complexes were established by single crystal x-ray diffraction analysis.