(μ-Acetato-κ2 O:O′)[μ-2,6-bis({bis[(pyridin-2-yl-κN)methyl]amino-κN}methyl)-4-methylphenolato-κ2 O:O](methanol-κO)dizinc bis(perchlorate)

The binuclear title complex, [Zn2(C33H33N6O)(CH3COO2)(CH3OH)](ClO4)2, was synthesized by the reaction between 2,6-bis({[bis(pyridin-2-yl)methyl]amino}methyl)-4-methylphenol (H-BPMP), Zn(OAc)2 and NaClO4. The two ZnII ions are bridged by the phenolate O atom of the octadentate ligand and the acetate group. An additional methanol ligand is terminally coordinated to one of the ZnII ions, rendering the whole structure unsymmetric. Other symmetric dizinc complexes of BPMP have been reported. However, to the best of our knowledge, the present structure, in which the two ZnII ions are distinguishable by the number of coordinating ligands and the coordination geometries (octahedral and square-pyramidal), is unique. The dizinc complex is a dication, and two perchlorate anions balance the charge. The –OH group of the coordinating methanol solvent molecule forms a hydrogen bond with a perchlorate counter-anion. One of the anions is disordered over two sets of sites with an occupancy ratio of 0.734 (2):0.266 (2).

The binuclear title complex, [Zn 2 (C 33 H 33 N 6 O)(CH 3 COO 2 )-(CH 3 OH)](ClO 4 ) 2 , was synthesized by the reaction between 2,6-bis({[bis(pyridin-2-yl)methyl]amino}methyl)-4-methylphenol (H-BPMP), Zn(OAc) 2 and NaClO 4 . The two Zn II ions are bridged by the phenolate O atom of the octadentate ligand and the acetate group. An additional methanol ligand is terminally coordinated to one of the Zn II ions, rendering the whole structure unsymmetric. Other symmetric dizinc complexes of BPMP have been reported. However, to the best of our knowledge, the present structure, in which the two Zn II ions are distinguishable by the number of coordinating ligands and the coordination geometries (octahedral and square-pyramidal), is unique. The dizinc complex is a dication, and two perchlorate anions balance the charge. The -OH group of the coordinating methanol solvent molecule forms a hydrogen bond with a perchlorate counter-anion. One of the anions is disordered over two sets of sites with an occupancy ratio of 0.734 (2):0.266 (2).

Comment
The crystal and molecular structure of the dinuclear Zn II complex [Zn 2 (µ-OAc)(MeOH)(BPMP)] 2+ , where OAc = acetate and H-BPMP = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol, has been determined. The complex is rendered asymmetric by the coordination of the methanol molecule. Thus, the two metal sites may be distinguished by their coordination geometries and the number of donor groups at each metal center. Zn1 is in an N 3 O 3 coordination environment with slightly distorted octahedral geometry and an average metal-ligand bond length of 2.119 Å; whereas Zn2 is in distorted square pyramidal geometry with N 3 O 2 coordination geometry and with an average bond length of 2.077 Å. The Zn1-Zn2 distance is 3.5528 (2) Å and the two metals are bridged by the phenolate oxygen (O1) and the syn,syn-µ-1,3-acetate. The Zn1-O1-Zn2 angle is 122.57 (9)°, which is a value that is intermediate between those

Experimental
The ligand HBPMP was prepared by following the procedure reported by Torelli et al. (2000). For the synthesis of [Zn 2 (µ-acetato)(MeOH)(BPMP)](ClO 4 ) 2 , a 30 ml methanolic solution of 0.25 g (0.471 mmol) of HBPMP in a 100 ml round bottom flask was prepared. To this solution, 0.173 g (0.943 mmol) of Zn(OAc) 2 was added, and the solution was stirred for two hrs, followed by addition of 0.1153 g (0.942 mmol) of sodium perchlorate. The resultant solution was stirred vigorously for 1 hr. The solvent was removed under vacuum and washed initially with 10 ml of ice cold water to remove unreacted salts and thereafter with 20 ml of diethyl ether. The resultant solid was collected in a round bottom flask and was dried under vacuum to yield a white powder that was dissolved in 2 ml of dry methanol. Colorless crystals of [Zn 2 (µ-OAc)(MeOH)(BPMP)](ClO 4 ) 2 suitable for X-ray crystallography were grown from this methanol solution by slow diffusion of diethyl ether.

Refinement
The oxygen atoms of one of the ClO 4anions were disordered over two sites with occupancy ratio of 0.73/0.27. The OH hydrogen atom was located from the difference Fourier map but the isotropic refinement was not satisfactory. Therefore, the OH hydrogen atom was constrained to ride on its parent atom, with U iso = 1.5 U eq (parent atom). Other hydrogen atoms were positioned geometrically and constrained to ride on their parent atoms, with C-H = 0.95-0.99 Å, and U iso = 1.2-1.5 U eq (parent atom). The highest peak is located 0.71 Å from atom Zn1 and the deepest hole is located 0.51 Å from atom

(methanol-κO)dizinc bis(perchlorate)
Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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 R-factors(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 )
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