Dendritic systems based on dinuclear ruthenium or rhodium units generating peripheral catalytic sites
Author(s)
Cherioux, Frederic
Thomas, Christophe M.
Date issued
2002
In
Chem. - Eur. J.
Vol
19
No
8
From page
4377
To page
4382
Subjects
rhodium ruthenium phenolthiolato bridged cationic complex prepn dendrimer prepn ruthenium phenolthiolato bridged cationic complex benzene triscarboxylate phosphinylation rhodium ruthenium phenolthiolato bridged cationic complex dendrimer methanol carbonylation cocatalyst ruthenium phenolthiolato bridged phosphine carboxylate complex crystal structure rhodium phenolthiolato bridged cationic complex mol structure rhodium phenolthiolato bridged cationic complex
Abstract
A series of dendritic cations contg. Ru2S3 or Rh2S3 units, either in the core or in the dendrons, was prepd. and characterized. Reaction of [LMCl(?-Cl)]2 with 4-mercaptophenol afforded [LM(?-SC6H4-4-OH)3ML]Cl cationic complexes (1, L = ?6-cymene, M = Ru; 2, L = Cp* = ?5-C5Me5, M = Rh), which were then condensed with 1,3,5-C6H3(COCl)3 in 3:1 ratio to give first-generation dendritic trications with 6 free phenol groups (the same L, 3, M = Ru; 4, M = Rh). The x-ray crystal structure anal. of 2-Cl shows a trigonal bipyramidal Rh2S3 core with propeller-like para-hydroxyphenyl substituents at the sulfur atoms. Esterification of the peripheral OH groups of 1 and 2 with 2-(diphenylphosphino)benzoic acid resulted in the formation of phosphine-functionalized cations [LM(?-SC6H4-4-OR-?S:?S)3ML]Cl (R = 2-PPh2-C6H4CO; 5, LM = (?6-cymene)Ru; 6, LM = Cp*Rh), the same reaction of 3 and 4 gave phosphine-bearing dendrimers 7 and 8. The modification of catalytic activity of [Rh(CO)2Cl]2 in methanol carbonylation reaction by monomeric and dendritic complexes 5-8 was studied. The ruthenium-contg. monocation 5, with three PPh2 functions at the periphery, acts as ligand for rhodium(I) and enhances significantly the catalytic activity of [Rh(CO)2Cl]2 for the carbonylation of methanol. On the other hand, addns. of dendritic 7 and 8, as well as rhodium monocation 6 deactivated the catalyst. [on SciFinder(R)]
Publication type
journal article