{μ-6,6′-Dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}-μ-nitrato-dinitratoterbium(III)zinc(II)

In the title heteronuclear ZnII—TbIII complex (systematic name: {6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato-1κ4 O 6,O 1,O 1′,O 6′}:2κ4 O 1,N,N′,O 1′-μ-nitrato-1:2κ2 O:O′-dinitrato-1κ4 O,O′-terbium(III)zinc(II)), [TbZn(C18H18N2O4)(NO3)3], with the hexadentate Schiff base compartmental ligand N,N′-bis(3-methoxysalicylidene)ethylenediamine (H2 L), the Tb and Zn atoms are triply bridged by two phenolate O atoms of the Schiff base ligand and one nitrate ion. The five-coordinate Zn atom is in a square-pyramidal geometry with the donor centers of two imine N atoms, two phenolate O atoms and one of the bridging nitrate O atoms. The TbIII center has a ninefold coordination environment of O atoms, involving the phenolate O atoms, two methoxy O atoms, two O atoms from two nitrate ions and one from the bridging nitrate ion. Weak intermolecular C—H⋯O interactions generate a two-dimensional layer structure.

In the title heteronuclear Zn II -Tb III complex (systematic name: [TbZn(C 18 H 18 N 2 O 4 )(NO 3 ) 3 ], with the hexadentate Schiff base compartmental ligand N,N 0 -bis(3-methoxysalicylidene)ethylenediamine (H 2 L), the Tb and Zn atoms are triply bridged by two phenolate O atoms of the Schiff base ligand and one nitrate ion. The five-coordinate Zn atom is in a squarepyramidal geometry with the donor centers of two imine N atoms, two phenolate O atoms and one of the bridging nitrate O atoms. The Tb III center has a ninefold coordination environment of O atoms, involving the phenolate O atoms, two methoxy O atoms, two O atoms from two nitrate ions and one from the bridging nitrate ion. Weak intermolecular C-HÁ Á ÁO interactions generate a two-dimensional layer structure.
Experimental H 2 L was prepared by the 2:1 condensation of 3-methoxysalicylaldehyde and ethylenediamine in methanol. Complex (I) was obtained by the treatment of zinc(II) acetate dihydrate (0.188 g, 1 mmol) with H 2 L (0.328 g, 1 mmol) in methanol solution (80 ml) under reflux for 3 h and then for another 3 h after the addition of terbium(III) nitrate hexahydrate (0.453 g, 1 mmol). The reaction mixture was cooled and the resulting precipitate was filtered off, washed with diethyl ether and dried in vacuo. Single crystals of (I) suitable for X-ray analysis were obtained by slow evaporation at room temperature of

Refinement
The H atoms were positioned geometrically and treated as riding on their parent atoms, with C-H distances of 0.97 (methylene), 0.96 Å (methyl) and 0.93 Å (aromaticmethyl), and with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for other H atoms. The main directions of movement of covalently bonded atoms N4, O5 and O6 are enforced to be the same. Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids. All the H atoms on carbon have been omitted for clarity.

O'-terbium(III)zinc(II)
Crystal data [TbZn(C 18   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq