Hydrogenation of esters with fe/tridentate ligands complexes

Abstract

The present invention relates to certain iron complexes that have utility in the field of catalytic hydrogenation and, more particularly, to certain iron complexes of tridentate ligands having one amino or imino coordinating groups and two phosphino coordinating groups. These iron complexes can be used in hydrogenation processes for the reduction of ketones, aldehydes, esters or lactones into the corresponding alcohol or diol, respectively.

What is claimed is: 
     
         1 . A complex of formula (2):
   [Fe(L3)(L′)Y 2 ]  (2)
   wherein L′ represents a CO or C 1-11  isonitrile compound;   each Y represents, simultaneously or independently, a hydrogen or halogen atom, a hydroxyl group, or a C 1 -C 6  alkoxy or carboxylic radical or a BH 4  or AlH 4  group;   L3 is a tridentate ligand of formula (A):   
       
         
           
           
               
               
           
         
         wherein the dotted line indicates a single or double bond; 
         z is 0 or 1 when the carbon-nitrogen bond with the dotted line represents a double or single bond respectively; 
         R 1  and R 2 , when taken separately, represent, simultaneously or independently, a linear, branched or cyclic C 1  to C 10  alkyl or alkenyl group optionally substituted, a C 6  to C 10  aromatic group optionally substituted; said groups R 1  and R 2 , when taken together, may form a saturated or unsaturated ring optionally substituted, having 5 to 10 atoms and including the phosphorus atom to which said R 1  and R 2  groups are bonded; 
         R 6  and R 7  represent, simultaneously or independently, a hydrogen atom, a linear, branched or cyclic C 1  to C 6  alkyl or alkenyl group optionally substituted, a C 6 -C 10  aromatic group optionally substituted; when the dotted line represent a single bond, two R 6  taken together, may form a saturated heterocycle, optionally substituted and optionally containing one or two additional nitrogen or oxygen atoms, containing 5 to 10 atoms and including the N atom and the carbon atoms to which said R 6  groups are bonded respectively; and 
         Q represents:
 a group of formula (i): 
 
       
       
         
           
           
               
               
           
         
         
           wherein n is an integer from 1 to 3, and 
           R 4  and R 5  represent, simultaneously or independently, a hydrogen atom, a linear, branched or cyclic C 1  to C 6  alkyl or alkenyl group optionally substituted, a C 6 -C 10  aromatic group optionally substituted; two distinct R 4  and/or R 5  groups, taken together, may form a C 5  to C 8 , saturated ring optionally substituted, including the carbon atoms to which each of said R 4  or R 5  group is bonded; or 
           a diphenyl, dinaphthyl, C 5 -C 12  metallocediyl, phenylene or naphthylene group optionally substituted; and 
         
         the optional substituents of R 4 , R 5 , R 6  and R 7  are one or two halogen, C 1  to C 10  alkoxy groups, halo- or perhalo-hydrocarbon, COOR, NR 2 , quaternary amine or R groups, wherein R is a C 1  to C 6  alkyl, or a C 5  to C 12  cycloalkyl, aralkyl or aromatic group, the latter being also optionally substituted by one, two or three halogen, sulfonates groups or C 1 -C 8  alkyl, alkoxy, amino, nitro, sulfonates, halo- or perhalo-hydrocarbon or ester groups; and 
         the optional substituents of R 1  and R 3  and Q, in particular when said groups are or contains phenyl or aromatic groups or moieties, one to three C 1  to C 8  alkoxy groups, C 1  to C 4  alkyl groups, or NR groups, wherein R is a C 1  to C 6  alkyl or C 5  to C 6  cycloalkyl. 
       
     
     
         2 . A complex according to  claim 1 , wherein L′ represents a CO moiety. 
     
     
         3 . A complex according to  claim 1 , wherein the tridentate L3 ligand is a C 6 -C 40  or a C 6 -C 30  compound. 
     
     
         4 . A complex according to  claim 1 , wherein each Y represents, simultaneously or independently, a hydrogen or chlorine or bromine atom, a methoxy, ethoxy or isopropoxy radical, or a BH 4  group. 
     
     
         5 . A complex according to  claim 1 , wherein each Z represents, simultaneously or independently, a chlorine or bromine atom, a methoxy, ethoxy or isopropoxy radical, or a BH 4  group. 
     
     
         6 . A complex according to  claim 1 , wherein the L3 tridentate ligand is a compound of formula (C): 
       
         
           
           
               
               
           
         
         wherein Alk is a C 3-10  branched or cyclic alkyl group. 
       
     
     
         7 . A complex according to  claim 1 , wherein the L3 tridentate ligand is a compound of formula (C): 
       
         
           
           
               
               
           
         
         wherein Alk is a C 3-6  branched or cyclic alkyl group.