Synthesis and reactivity of 3,5-dimethyl-4-aminomethylpyrazole ligands. An entry to new water-soluble pyrazolate rhodium(I) complexes
摘要:
The new pyrazoles 3,5-dimethyl-4-(ethylamino)methylpyrazol (HL1) and 3,5-dimethyl-4-(isopropylamino)methylpyraxole(HL2), both containing aminoalkyl groups at position 4 have been prepared by aminoalkylation of 3,5-dimethylpyrazole and by the reaction between 1-chloromethyl-3,5-dimethylpyrazolium chloride and NH2R amines. The reaction between HL1, HL2 and [RhCl(COD)](2) resulted in complexes of formula [Rh-2(HL1)(2)(COD)(2)]Cl-2 (1) and [Rh-2(HL2)(2)(COD)(2)]Cl-2 (2), which contained the pyrazole ligands in the 'zwitterionic' pyrazolate-ammonium forms. The X-ray structure analysis of 2 confirmed the neutral nature of bridging-pyrazolate ligands and revealed that 1 and 2 belonged to the [Rh-2(Pz)(2)L-2] family of compounds. The same reaction with two equivalents of NaOMe resulted in neutral pyrazolate complexes [Rh-2(L-1)(2)(COD)(2)] (5) and [Rh-2(L-2)(2)(COD)(2)] (6). The reaction between both cationic and neutral pyrazolate complexes and a 1:1 CO-H-2 mixture (20 atm) led to the dinuclear pyrazolate-bridged tetracarbonyl compounds 3, 4, 7 and 8 in good yields. Tetracarbonyl complexes 3 and 4 were not isolated in pure state. All the complexes synthesized are soluble in polar solvents such as water. (C) 2000 Elsevier Science S.A. All rights reserved.
Synthesis and reactivity of 3,5-dimethyl-4-aminomethylpyrazole ligands. An entry to new water-soluble pyrazolate rhodium(I) complexes
摘要:
The new pyrazoles 3,5-dimethyl-4-(ethylamino)methylpyrazol (HL1) and 3,5-dimethyl-4-(isopropylamino)methylpyraxole(HL2), both containing aminoalkyl groups at position 4 have been prepared by aminoalkylation of 3,5-dimethylpyrazole and by the reaction between 1-chloromethyl-3,5-dimethylpyrazolium chloride and NH2R amines. The reaction between HL1, HL2 and [RhCl(COD)](2) resulted in complexes of formula [Rh-2(HL1)(2)(COD)(2)]Cl-2 (1) and [Rh-2(HL2)(2)(COD)(2)]Cl-2 (2), which contained the pyrazole ligands in the 'zwitterionic' pyrazolate-ammonium forms. The X-ray structure analysis of 2 confirmed the neutral nature of bridging-pyrazolate ligands and revealed that 1 and 2 belonged to the [Rh-2(Pz)(2)L-2] family of compounds. The same reaction with two equivalents of NaOMe resulted in neutral pyrazolate complexes [Rh-2(L-1)(2)(COD)(2)] (5) and [Rh-2(L-2)(2)(COD)(2)] (6). The reaction between both cationic and neutral pyrazolate complexes and a 1:1 CO-H-2 mixture (20 atm) led to the dinuclear pyrazolate-bridged tetracarbonyl compounds 3, 4, 7 and 8 in good yields. Tetracarbonyl complexes 3 and 4 were not isolated in pure state. All the complexes synthesized are soluble in polar solvents such as water. (C) 2000 Elsevier Science S.A. All rights reserved.
In the title compound, [Rh-2(C8H15N3)(2)(C8H12)(2)]Cl-2.CH2Cl2 .CH3OH, the dinuclear Rh-I complex has C-2 symmetry and the two pyrazolato ligands act as mu-bridges. The coordination of each Rh-I cation is completed by one cyclooctadiene (COD) ligand. It is shown that the average Rh-C(COD) distance is linearly dependent on the Rh-N(pyrazole) distance in this type of compound, and this is ascribed to the steric hindrance produced by the packing.