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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 30, Number 3
BKCSDE 30(3)
March 20, 2009 

First Hydrogelation of Discrete Metal Complexes. Structures and Fluxional Behavior of Cyclopalladium(II) Complexes
Young Mee Na, Tae Hwan Noh, Byung Jo Ha, Jongki Hong, Ok Sang Jung*
Catenane, Hydrogelation, Metallacycles, Palladium, Si ligands
The reaction of (en)Pd(NO3)2 (en = ethylenediamine) with 1,4-bis(dimethyl-4-pyridylsilyl)benzene (L) affords cyclodimer, [(en)Pd(L)]2(NO3)4, whereas the reaction of (tmeda)Pd(NO3)2 (tmeda = N,N,N’,N’-tetramethylethylenediamine) with L gives cyclotrimer, [(tmeda)Pd(L)]3(NO3)6. Both complexes exist as catenane in water. The catenated cyclodimer is rigid whereas the catenated cyclotrimer is dynamic in water. The catenated cyclotrimers afford hydrogel containing 98.5% water below 2℃. The hydrogel changes to its sol around 38℃, and to its clear solution at 78℃. Such a notable difference between [(en)Pd(L)]2(NO3)4 and [(tmeda)Pd(L)]3(NO3)6 might be explained by their different dynamic behavior via ring size effects.
573 - 576
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