ZINC(II) COMPLEXES WITH THE TETRADENTATE SCHIFF BASE LIGAND N,N?-BIS(1-PYRIDIN-2-YL-ETHYLIDENE)PROPANE-1,3-DIAMINE: SYNTHESIS AND CRYSTAL STRUCTURES
Two new zinc(II) complexes [ZnL(N3)]?BF4 (1) and [ZnBrL]?BF4 (2), derived from the tetradentate Schiff base ligand N,N?-bis(1-pyridin-2-yl-ethylidene)propane-1,3-diamine (L), are prepared and characterized by physicochemical methods and single crystal X-ray crystallography. The crystal of (1) is triclinic: space group P-1, a = 8.593(1) ?, b = 8.752(1) ?, c = 13.393(2) ?, a = 97.153(1)°, b = 93.046(1)°, g = 91.577(1)°, V = 997.4(2) ?3, Z = 2. The crystal of (2) is triclinic: space group P-1, a = 8.351(1) ?, b = 8.956(1) ?, c = 13.139(2) ?, a = 92.716(1)°, b = 94.241(2)°, g = 95.016(1)°, V = 974.8(2) ?3, Z = 2. The geometries of the penta-coordinated zinc atoms in both complexes are intermediate between the square pyramid and the trigonal bipyramid having the Addison parameters of 0.39 and 0.47 respectively. The syntheses of the complexes show distinct preference for the anions in the order Br– >N3-> CH3COO–.
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The geometries of the penta-coordinated zinc atoms in both complexes are intermediate between the square pyramid and the trigonal bipyramid having the Addison parameters of 0.39 and 0.47 respectively. <...> The syntheses of the complexes show distinct preference for the anions in the order Br– > 3N > > CH3COO–. <...> The Schiff bases derived from salicylaldehyde and its derivatives represent an important class of ligands in coordination chemistry, and a large number of metal complexes with them have been reported [ 4—6 ]. <...> The lanthanide and transition metal complexes derived from the Schiff base N,N-bis(1-pyridin-2-yl-methylidene)propane-1,3-diamine have widely been reported [ 7—10 ]. <...> In the present paper, two new zinc(II) complexes [ZnL(N3)]ŒBF4 (1) and [ZnBrL]ŒBF4 (2) have been prepared and characterized. <...> Sodium azide, ammonium fluoroborate, zinc acetate dihydrate, and zinc bromide were obtained from Beijing Chemical Reagent Company and were used as received. <...> Although no problems were encountered in this work, sodium azide and the complexes containing sodium ligands are potentially explosive. <...> Complex (2) was prepared according to the method described for (1), only with zinc acetate dihydrate replaced by zinc bromide (225 mg, 1 mmol). <...> The hydrogen atoms were calculated with appropriate riding models. <...> Fluoroborate is an anion similar to perchlorate and a number of complexes with it have been reported [ 20—22 ], however, no complexes with L bearing such anions have been reported so far. <...> In the present work, a reaction of L, NaN3, NH4BF4, and Zn(CH3COO)2 for (1) or ZnBr2 for (2) yielded two mononuclear zinc complexes with fluoroborate anions. <...> The syntheses of the complexes show distinct preference for the > CH3COO–. <...> The air-stable and moisture-insensitive complexes are soluble in common organic solvents such anions in the order Br– > 3N > as methanol, ethanol, dichloromethane, acetonitrile, and DMF, but are insoluble in water. <...> The occurrence of bands at about 1066 cm–1 (broad, strong) and bands at about 522 cm–1 (sharp, medium) in the IR spectra of both complexes indicates that the fluoroborate anions are present in their regular tetrahedral geometry, which is in accordance with that observed in most examples where the fluoroborate anions are not coordinated to the metal atoms [ 20 <...>
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