A new series of water‐soluble Ir complexes with N‐heterocyclic carbene ligands that bear ester and amide groups has been obtained and fully characterized. The new complexes are highly reactive and selective for the alkylation of amines with alcohols with a 1:1 ratio of reactants in water and in the absence of base or other additives. The catalytic system has a broad substrate scope, which allows the synthesis of a variety of primary and secondary amines in excellent yields. A tolerance to a large range of functional groups was obtained.

The cationic piano-stool iron complexes containing the N-heterocyclic carbene ligand tethered to a tetramethylcyclopentadienyl ring [(Cp*-NHC)Fe(CO)(L)]-[X] (L = NCMe, DMSO; X = BF 4 , OTf) have been prepared and analyzed by spectroscopic, electrochemical, and crystallographic methods. Oxidation reactions of the cationic complex [(Cp*-NHC)Fe(CO)(NCMe)][BF 4 ] (2) with silver tetrafluoroborate and tert-butyl hydroperoxide in acetonitrile yield the dicationic iron(III) complexes [(Cp*-NHC)Fe(NCMe) 2 ][BF 4 ] 2 and [(Cp*-NHC)Fe(H 2 O)][BF 4 ] 2 , respectively. When the reaction of 2 with AgBF 4 is performed in dichloromethane, the cationic complex [(Cp*-NHC)FeCl][BF 4 ] is obtained. These new iron(III) complexes have been characterized by Mossbauer spectroscopy and in one case by X-ray diffraction studies. DFT calculations were used to rationalize experimental results. The cationic complex [(Cp*-NHC)Fe(CO)(NCMe)][OTf] is catalytically active toward the reduction of benzaldehyde and acetophenone using phenylsilane under neat conditions and in the absence of visible light irradiation.

Fluorescence quenching is widely used to obtain association constants between proteins and ligands. This methodology is based on assumption that ground-state complex between protein and ligand is responsible for quenching. Here, we call the attention about the risk of using the temperature criterion for decision of applying or not fluorescence quenching data to measure association constants. We demonstrated that hydrophobic effect can be the major force involved in the interaction and, as such, superposes the well-established rationalization that host/guest com-

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