Encapsulated oxo-bridged organometallic cluster catalyst and a process for the preparation thereof

Abstract

The present invention relates to a novel encapsulated organometallic cluster complex catalyst and to a process for the preparation thereof. The oxo-bridged organometallic cluster complex of the invention has at least one atom of cobalt and manganese encapsulated in micro and mesoporous porous solids like aluminosilicate zeolites, aluminophosphates, carbon molecular sieves, silica and is particularly effective for oxidation of aromatic alkyl groups to the carboxyl groups in high yields.

We claim:  
     
         1 . An encapsulated organometallic cluster complex catalyst wherein the organometallic cluster is of the general formula, 
       [M x M′ x′ (O)(RCOO) n L n′ ]Y n″   
       wherein M and M′ are transition metal ions, x and x′ are in the range of 0 to 3 with the proviso that only one of x and x′ may be 0, R is selected from the group consisting of an alkyl group containing 1 to 5 carbon atoms, an axyl group with 1 to 3 benzene rings, substituted alkyl and substituted aryl group, n is in the range of 3 to 6, L is selected from the group consisting of RCOO, pyridine, nitrogen containing organic bases, H 2 O, organic solvent and any like ligand, Y comprises a halide ion selected from the group consisting of ClO 4   − , BF 4   − , PF 6   −  and BrO 3   −  and other like ion, n′ and n″ are each in the range of 0 to 3, said complex being encapsulated in a porous material.  
     
     
         2 . An encapsulated organometallic cluster complex catalyst as claimed in  claim 1  wherein M and M′ are each Co or Mn.  
     
     
         3 . An encapsulated organometallic cluster complex catalyst as claimed in  claim 1  wherein the catalyst comprises CoMn 2 (O)(CH 3 COO) 6 , Co 2 Mn(O)(CH 3 COO) 6 , CoMn 2 (O)(CH 3 COO) y (pyridine) z  and Co 2 Mn(O)(CH 3 COO) y (pyridine) z , wherein y+z=9.  
     
     
         4 . An encapsulated organometallic cluster complex catalyst as claimed in  claim 1  wherein the porous material encapsulant comprises micro and mesoporous materials selected from the group consisting of aluminosilicate zeolites, aluminophosphates, silica and carbon molecular sieves.  
     
     
         5 . A process for the preparation of the encapsulated organometallic cluster complex having general formula, 
       [M x M′ x′ (O)(RCOO) n L n′ ]Y n″   
       wherein M and M′ are transition metal ions, x and x′ are each in the range of 0 to 3 with the proviso that only one of x and x′ may be 0, R is selected from the group consisting of an alkyl group containing 1 to 5 carbon atoms, an aryl group with 1 to 3 benzene rings, substituted alkyl and substituted aryl group, n is in the range of 3 to 6, L is selected from the group consisting of RCOO, pyridine, nitrogen containing organic bases, H 2 O, organic solvent or any like ligand, Y comprises a halide ion selected from the group consisting of ClO 4   − , BF 4   − , PF 6   −  and BrO 3   −  and other like ion, n′ and n″ are each in the range of 0 to 3, said process comprising interacting a zeolite HY with a mixture of solutions of sources of transition metal ions at a temperature in the range of 298 K to 358 K under constant stirring to obtain a solid product, washing and drying the solid product thoroughly at 390 to 410 K, and then adding to it a mixture of an acid, pyridine, salt of alkali metal and water, under constant agitation and in a dynamic aerobic environment for 2 to 4 hours at 298 K and separating and drying the encapsulated complex at 298 K under vacuum to obtain the desired encapsulated oxo-bridged organometallic cluster catalyst.  
     
     
         6 . A process as claimed in  claim 5  wherein the transition metal ions used are selected from cobalt and manganese ions.  
     
     
         7 . A process as claimed in  claim 6  wherein the manganese ion source used is selected from the group consisting of manganese acetate, manganese chloride and manganese nitrate.  
     
     
         8 . A process as claimed in  claim 7  wherein the manganese ion source used is manganese acetate.  
     
     
         9 . A process as claimed in  claim 6  wherein the source of cobalt ions used is selected from the group consisting of cobalt acetate, cobalt chloride and cobalt nitrate.  
     
     
         10 . A process as claimed in  claim 9  wherein the cobalt ion source used is cobalt acetate.  
     
     
         11 . A process as claimed in  claim 5  wherein the alkali metal salt used is selected from the group consisting of sodium bromide, sodium chloride, potassium bromide, potassium chloride and potassium iodide.  
     
     
         12 . A process as claimed in  claim 11  wherein the alkali metal salt used is sodium bromide.  
     
     
         13 . A process as claimed in  claim 5  wherein the porous encapsulant used comprises micro and mesoporous materials selected from the group consisting of aluminosilicate zeolites, aluminophosphates, silica and carbon molecular sieves.  
     
     
         14 . A process as claimed in  claim 5  wherein the acid used is glacial acetic acid.