Di-μ2-acetato-diacetato-bis{μ2-3,3′,5,5′-tetramethoxy-2,2-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}tricobalt(II,III) dichloromethane disolvate

The trinuclear title compound, [Co3(CH3COO)4(C20H22N2O6)2]·2CH2Cl2, contains mixed-valence cobalt ions in the following order CoIII–CoII–CoIII where all the three cobalt ions are hexacoordinated. The central cobalt ion is situated on an inversion centre and is in an all-oxygen environment, coordinated by four phenolate O atoms and two O atoms from bridging acetate groups, while the terminal cobalt ion is hexacoordinated by two phenolate O atoms, two acetate O atoms and two imine N atoms. This complex contains a high-spin central CoII and two terminal low-spin CoIII i.e. CoIII(S = 0)–CoII(S = 3/2)-CoIII(S = 0). There are weak intermolecular C—H⋯O interactions involving the methoxy groups, as well as intermolecular C—H⋯O interactions involving the acetate anions. In addition, the dichoromethane solvate molecules are held in place by weak C—H⋯Cl interactions.


Related literature
For background to to the use of transition metal complexes with Schiff bases as potential enzyme inhibitors, see: You et al. (2008); Shi et al. (2007). For the use of transition metal complexes for the development of catalysis, magnetism and molecular architectures, see: Yu et al. (2007); You & Zhu (2004); You & Zhou (2007). For the use of transition metal complexes for optoelectronic and also for photo-and electroluminescence applications, see: Yu et al. (2008). For the potential use of transition metal complexes in the modeling of multisite metalloproteins and in nano-science, see: Chattopadhyay et al. (2006). For the importance of tri-nuclear cobalt Schiff base complexes as catalysts for organic molecules and as antiviral agents due to their ability to interact with proteins and nucleic acids, see: Chattopadhyay et al. (2006Chattopadhyay et al. ( , 2008; Babushkin & Talsi (1998). For background to metallosalen complexes, see: Dong et al. (2008). For the magnetic properties of quadridentate metal complexes of Schiff bases, see: He et al. (2006); Gerli et al. (1991). For the antimicrobial activity of Schiff base ligands and their complexes, see: You et al. (2004).

Experimental
Crystal data [Co 3 (C 2 Table 1 Hydrogen-bond geometry (Å , ). Symmetry codes: (i) x þ 1 2 ; Ày þ 3 2 ; z À 1 2 ; (ii) Àx þ 1 2 ; y À 1 2 ; Àz þ 1 2 ; (iii) x þ 1 2 ; Ày þ 1 2 ; z þ 1 2 ; (iv) x À 1 2 ; Ày þ 1 2 ; z þ 1 2 .  et al., 2008) and also for the jack bean urease enzyme (jbU) (Shi et al., 2007). The enzyme XO catalyzes the hydroxylation of hypoxanthine and xanthine to yield uric acid and superoxide anions. Other areas where complexes of transition metals have played roles are in the development of catalysis, magnetism and molecular architecture (Yu et al., 2007, You & Zhu, 2004, You & Zhou, 2007. Complexes of transition metals with Schiff base ligands have also been shown to be useful materials for optoelectronics and also for photo and electro-luminance applications (Yu et al., 2008). Studies for antimicrobial activities of Schiff base ligands as well as those of their corresponding complexes have been investigated (You et al., 2004) where it was shown that Schiff base ligands as well as their complexes exhibited good antibacterial properties. Metallosalen complexes are of great importance due to their use in various catalytic chemical transformations that includes, epoxidation of olefins, symmetric ring opening, azirdination of olefins, olefine cyclopropanation and formation of linear and cyclic hydrocarbonation (Dong et al., 2008).
The importance of tri-nuclear cobalt Schiff base complexes ranges from, catalysts for oxidation of organic molecules, antiviral agents due to their ability to interact with proteins and nucleic acids and they have also used to mimic the biological co-factor such as cobalamin (Chattopadhyay et al., 2008, Babushkin & Talsi, 1998. The quadridentate metal complexes of Schiff bases have been studied extensively as B12 models, their magnetic interaction between bridged paramagnetic metal ions and their applications (Gerli et al., 1991). Magnetic susceptibilities data for the trinuclear mixed valence compound [Co II (OAc) 2 (hapt) 2 Co 2 (III)(py) 2 ](ClO 4 ) 2 [where (hapt) is bis-(2-hydroxyacetophenone) trimethylenediimine] were measured in the temperature range of 300-2 K and it was found that µ eff values are almost constant ranging from 4.37 to 5.00 BM (He et al., 2006). The values obtained suggested that the oxidation states are Co III (S = 0)-Co II (S = 3/2)-Co III (S = 0).
Cyclic tri-nuclear cobalt complexes have also shown some catalytic activities in epoxidation of olefins, autoxidation of hydrocarbons, utility in modeling multinuclear active sites of metalloproteins and their potential use in nanoscience (Chattopadhyay et al., 2006).
The title compound C 50 H 60 Cl 4 Co 3 N 4 O 20 is a trinuclear cobalt Schiff base complex containing a central high spin Co II and two terminal low spin Co III centers. The environment around Co (1)  There are weak intermolecular C-H···O interactions involving the methoxy groups and acetate anions. In addition the dichoromethane solvate molecules are held in place by weak C-H···Cl interactions.

Experimental
The synthesis of the ligand ethylene-bis(2,4-dimethoxy-salicylaldimine) was achieved by adding a solution of (2 g, 33.3 mmol) ethylenediamine in 25 ml s of methanol to the solution of (12.13 g, 66.6 mmol) 2,4-dimethoxysalicylaldehyde in 40 ml s of methanol. The mixture was refluxed overnight while stirring. The reaction mixture was then evaporated under reduced pressure to afford yellow solids. 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.