Uptake of ammonia by ice surfaces at atmospheric temperatures.

We present an ambient pressure X-ray photoelectron spectroscopy investigation of the adsorption of ammonia on ice over the temperature range -23 °C to -50 °C. Previous flow tube studies have shown significant uptake of ammonia to ice at these temperatures, which was linked to the incorporation of ammonium into the ice crystal lattice. Our present investigation shows a significant uptake of ammonia to the ice interface, with ammonia concentrations exceeding those measured in past studies for the case of bulk snow and ice.

Modular Pincer-type Pyridylidene Amide Ruthenium(II) Complexes for Efficient Transfer Hydrogenation Catalysis.

A set of bench-stable ruthenium complexes with new N,N,N-tridentate coordinating pincer-type pyridyl-bis(pyridylideneamide) ligands was synthesized in excellent yields, with the pyridylidene amide in meta or in para position ( m-PYA and p-PYA, respectively). While complex [Ru( p-PYA)(MeCN)] is catalytically silent in transfer hydrogenation, its meta isomer [Ru( m-PYA)(MeCN)] shows considerable activity with turnover frequencies at 50% conversion TOF = 100 h. Spectroscopic, electrochemical, and crystallographic analyses suggest considerably stronger donor properties of the zwitterionic m-PYA ligand compared to the partially π-acidic p-PYA analogue, imparted by valence isomerization.