Chemical Exchange Saturation Transfer (CEST) as a Tool to Measure Ligand Flexibility of Chelating Chiral Di-N-heterocyclic Carbene Complexes

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• 作者：Matthew S. Jeletic ; Claire E. Lower ; Ion Ghiviriga ; Adam S. Veige
• 刊名：Organometallics
• 出版年：2011
• 出版时间：November 14, 2011
• 年：2011
• 卷：30
• 期：21
• 页码：6034-6043
• 全文大小：1022K
• 年卷期：v.30,no.21(November 14, 2011)
• ISSN：1520-6041

文摘

A series of eight [(diNHC)Rh(CO)<sub>2sub>][OTf] complexes, 1鈥?R, 2鈥?R, and 3鈥?R (where diNHC = DEAM, trans-9,10-ss="uu">dihydro-9,10-ss="uu">ethanoss="uu">anthracene-11,12-diylss="uu">methanediyl carbene, and DEA, trans-9,10-ss="uu">dihydro-9,10-ss="uu">ethanoss="uu">anthracene-11,12-diyl carbene ligands; R = R-methylphenylmethane (R-CHMePh), diphenylmethane (diPh), benzyl (Bn), methyl (Me), isopropyl (<sup>isup>Pr), and o-methylbenzyl (o-MeBn); carbene heterocycle = imidazol-2-ylidene, and benzimidazol-2-ylidene), are synthesized and characterized. The purpose for the synthesis of these complexes was to examine the relationship between carbene N-heterocycle, R-group substitution, and metallocycle ring size (DEAM = 9, DEA = 7 atom ring) on ligand flexibility. The complexes were examined by chemical exchange saturation transfer to measure the rate of conformational isomerization. The results indicate that flexibility is not significantly altered by choice of carbene heterocycle and R group. However, the constrained DEA diNHC derivative does not undergo conformational isomerization.